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Sample records for cyanobacterium gloeobacter violaceus

  1. Oxygen evolution in the thylakoid-lacking cyanobacterium Gloeobacter violaceus PCC 7421.

    PubMed

    Koyama, Kohei; Suzuki, Hiroyuki; Noguchi, Takumi; Akimoto, Seiji; Tsuchiya, Tohru; Mimuro, Mamoru

    2008-04-01

    The oxygen-evolving reactions of the thylakoid-lacking cyanobacterium Gloeobacter violaceus PCC 7421 were compared with those of Synechocystis sp. PCC 6803. Four aspects were considered: sequence conservation in three extrinsic proteins for oxygen evolution, steady-state oxygen-evolving activity, charge recombination reactions, i.e., thermoluminescence and oscillation patterns of delayed luminescence on a second time scale and delayed fluorescence on the nanosecond time scale at -196 degrees C. Even though there were significant differences between the amino acid sequences of extrinsic proteins in G. violaceus and Synechocystis sp. PCC 6803, the oxygen-evolving activities were similar. The delayed luminescence oscillation patterns and glow curves of thermoluminescence were essentially identical between the two species, and the nanosecond delayed fluorescence spectral profiles and lifetimes were also very similar. These results indicate clearly that even though the oxygen-evolving reactions are carried out in the periplasm by components with altered amino acid sequences, the essential reaction processes for water oxidation are highly conserved. In contrast, we observed significant changes on the reduction side of photosystem II. Based on these data, we discuss the oxygen-evolving activity of G. violaceus. PMID:18298941

  2. Artificially acquired chlorophyll b is highly acceptable to the thylakoid-lacking cyanobacterium, Gloeobacter violaceus PCC 7421.

    PubMed

    Araki, Mie; Akimoto, Seiji; Mimuro, Mamoru; Tsuchiya, Tohru

    2014-08-01

    Unicellular cyanobacterium Gloeobacter violaceus is an only known oxygenic photosynthetic organism that lacks thylakoid membrane. Molecular phylogenetic analyses indicate that G. violaceus is an early-branching cyanobacterium within cyanobacterial clade. Therefore, the photosynthetic system of G. violaceus is considered to be partly similar to that of the ancestral cyanobacteria that would lack thylakoid membrane. G. violaceus possesses chlorophyll (Chl) a as the only chlorophyll species like most cyanobacteria. It was proposed that the ancestral oxygenic photosynthetic organism had not only Chl a and phycobilins but also Chl b. However, no organism which contains both Chl a and Chl b and lacks thylakoid membrane has been found in nature. Therefore, we introduced the chlorophyllide a oxygenase gene responsible for Chl b biosynthesis into G. violaceus. In the resultant transformant, Chl b accumulated at approximately 11% of total Chl independent of growth phase. Photosystem I complexes isolated from the transformant contained Chl b at 9.9% of total Chl. The presence of Chl b in the photosystem I complexes did not inhibit trimer formation. Furthermore, time-resolved fluorescence spectrum demonstrated that Chl b transferred energy to Chl a in the photosystem I complexes and did not disturb the energy transfer among the Chl a molecules. These results show that G. violaceus is tolerant to artificially produced Chl b and suggest the flexibility of photosystem for Chl composition in the ancestral oxygenic photosynthetic organism.

  3. Interactions of linker proteins with the phycobiliproteins in the phycobilisome substructures of Gloeobacter violaceus.

    PubMed

    Mendoza-Hernández, Guillermo; Pérez-Gómez, Bertha; Krogmann, David W; Gutiérrez-Cirlos, Emma Berta; Gómez-Lojero, Carlos

    2010-12-01

    Gloeobacter violaceus PCC 7421 is a unicellular oxygenic photosynthetic organism, which precedes the diversification of cyanobacteria in the phylogenetic tree. It is the only cyanobacterium that does not contain internal membranes. The unique structure of the rods of the phycobilisome (PBS), grouped as one bundle of six parallel rods, distinguishes G. violaceus from the other PBS-containing cyanobacteria. It has been proposed that unique multidomain rod-linkers are responsible for this peculiarly organized shape. However, the localization of the multidomain linkers Glr1262 and Glr2806 in the PBS-rods remains controversial (Koyama et al. 2006, FEBS Lett 580:3457-3461; Krogmann et al. 2007, Photosynth Res 93:27-43). To further increase our understanding of the structure of the G. violaceus PBS, the identification of the proteins present in fractions obtained from sucrose gradient centrifugation and from native electrophoresis of partially dissociated PBS was conducted. The identification of the proteins, after electrophoresis, was done by spectrophotometry and mass spectrometry. The results support the localization of the multidomain linkers as previously proposed by us. The Glr1262 (92 kDa) linker protein was found to be the rod-core linker L(RC) (92), and Glr2806 (81 kDa), a special rod linker L(R) (81) that joins six disks of hexameric PC. Consequently, we propose to designate glr1262 as gene cpcGm (encoding L(RC) (92)) and glr2806 as gene cpcJm (encoding L(R) (81)). We also propose that the cpeC (glr1263) gene encoding L(R) (31.8) forms the interface that binds PC to PE.

  4. Reconstitution of Gloeobacter violaceus Rhodopsin with a Light-Harvesting Carotenoid Antenna†

    PubMed Central

    Imasheva, Eleonora S.; Balashov, Sergei P.; Choi, Ah Reum; Jung, Kwang-Hwan; Lanyi, Janos K.

    2009-01-01

    We show that salinixanthin, the light-harvesting carotenoid antenna of xanthorhodopsin, can be reconstituted into the retinal protein from Gloeobacter violaceus expressed in E. coli. Reconstitution of gloeobacter rhodopsin with the carotenoid is accompanied by characteristic absorption changes and the appearance of CD bands similar to those observed for xanthorhodopsin that indicate immobilization and twist of the carotenoid in the binding site. As in xanthorhodopsin, the carotenoid functions as a light-harvesting antenna. The excitation spectrum for retinal fluorescence emission shows that ca. 36% of the energy absorbed by the carotenoid is transferred to the retinal. From excitation anisotropy, we calculate the angle between the two chromophores as ca. 50°, similar to that in xanthorhodopsin. The results indicate that gloeobacter rhodopsin binds salinixanthin in a similar way as xanthorhodopsin, and suggest that it might bind a carotenoid also in vivo. In the crystallographic structure of xanthorhodopsin, the conjugated chain of the carotenoid lies on the surface of helices E and F, and the 4-keto-ring is immersed in the protein at van der Waals distance from the ionone ring of the retinal. The 4-keto-ring is in the space occupied by a tryptophan in bacteriorhodopsin, which is replaced by the smaller glycine in xanthorhodopsin and gloeobacter rhodopsin. Specific binding of the carotenoid and its light-harvesting function are eliminated by a single mutation of the gloeobacter protein that replaces this glycine with a tryptophan. This indicates that the 4-keto-ring is critically involved in carotenoid binding, and suggests that a number of other recently identified retinal proteins, from a diverse group of organisms, could also contain carotenoid antenna since they carry the homologous glycine near the retinal. PMID:19842712

  5. Reconstitution of Gloeobacter violaceus rhodopsin with a light-harvesting carotenoid antenna.

    PubMed

    Imasheva, Eleonora S; Balashov, Sergei P; Choi, Ah Reum; Jung, Kwang-Hwan; Lanyi, Janos K

    2009-11-24

    We show that salinixanthin, the light-harvesting carotenoid antenna of xanthorhodopsin, can be reconstituted into the retinal protein from Gloeobacter violaceus expressed in Escherichia coli. Reconstitution of gloeobacter rhodopsin with the carotenoid is accompanied by characteristic absorption changes and the appearance of CD bands similar to those observed for xanthorhodopsin that indicate immobilization and twist of the carotenoid in the binding site. As in xanthorhodopsin, the carotenoid functions as a light-harvesting antenna. The excitation spectrum for retinal fluorescence emission shows that ca. 36% of the energy absorbed by the carotenoid is transferred to the retinal. From excitation anisotropy, we calculate the angle between the two chromophores as being ca. 50 degrees , similar to that in xanthorhodopsin. The results indicate that gloeobacter rhodopsin binds salinixanthin in a manner similar to that of xanthorhodopsin and suggest that it might bind a carotenoid also in vivo. In the crystallographic structure of xanthorhodopsin, the conjugated chain of the carotenoid lies on the surface of helices E and F, and the 4-keto ring is immersed in the protein at van der Waals distance from the ionone ring of the retinal. The 4-keto ring is in the space occupied by a tryptophan in bacteriorhodopsin, which is replaced by the smaller glycine in xanthorhodopsin and gloeobacter rhodopsin. Specific binding of the carotenoid and its light-harvesting function are eliminated by a single mutation of the gloeobacter protein that replaces this glycine with a tryptophan. This indicates that the 4-keto ring is critically involved in carotenoid binding and suggests that a number of other recently identified retinal proteins, from a diverse group of organisms, could also contain carotenoid antenna since they carry the homologous glycine near the retinal.

  6. The Primitive Thylakoid-Less Cyanobacterium Gloeobacter Is a Common Rock-Dwelling Organism

    PubMed Central

    Mareš, Jan; Hrouzek, Pavel; Kaňa, Radek; Ventura, Stefano; Strunecký, Otakar; Komárek, Jiří

    2013-01-01

    Cyanobacteria are an ancient group of photosynthetic prokaryotes, which are significant in biogeochemical cycles. The most primitive among living cyanobacteria, Gloeobacter violaceus, shows a unique ancestral cell organization with a complete absence of inner membranes (thylakoids) and an uncommon structure of the photosynthetic apparatus. Numerous phylogenetic papers proved its basal position among all of the organisms and organelles capable of plant-like photosynthesis (i.e., cyanobacteria, chloroplasts of algae and plants). Hence, G. violaceus has become one of the key species in evolutionary study of photosynthetic life. It also numbers among the most widely used organisms in experimental photosynthesis research. Except for a few related culture isolates, there has been little data on the actual biology of Gloeobacter, being relegated to an “evolutionary curiosity” with an enigmatic identity. Here we show that members of the genus Gloeobacter probably are common rock-dwelling cyanobacteria. On the basis of morphological, ultrastructural, pigment, and phylogenetic comparisons of available Gloeobacter strains, as well as on the basis of three new independent isolates and historical type specimen, we have produced strong evidence as to the close relationship of Gloeobacter to a long known rock-dwelling cyanobacterial morphospecies Aphanothece caldariorum. Our results bring new clues to solving the 40 year old puzzle of the true biological identity of Gloeobacter violaceus, a model organism with a high value in several biological disciplines. A probable broader distribution of Gloeobacter in common wet-rock habitats worldwide is suggested by our data, and its ecological meaning is discussed taking into consideration the background of cyanobacterial evolution. We provide observations of previously unknown genetic variability and phenotypic plasticity, which we expect to be utilized by experimental and evolutionary researchers worldwide. PMID:23823729

  7. Cyanobacterial Light-Driven Proton Pump, Gloeobacter Rhodopsin: Complementarity between Rhodopsin-Based Energy Production and Photosynthesis

    PubMed Central

    Choi, Ah Reum; Shi, Lichi; Brown, Leonid S.; Jung, Kwang-Hwan

    2014-01-01

    A homologue of type I rhodopsin was found in the unicellular Gloeobacter violaceus PCC7421, which is believed to be primitive because of the lack of thylakoids and peculiar morphology of phycobilisomes. The Gloeobacter rhodopsin (GR) gene encodes a polypeptide of 298 amino acids. This gene is localized alone in the genome unlike cyanobacterium Anabaena opsin, which is clustered together with 14 kDa transducer gene. Amino acid sequence comparison of GR with other type I rhodopsin shows several conserved residues important for retinal binding and H+ pumping. In this study, the gene was expressed in Escherichia coli and bound all-trans retinal to form a pigment (λmax  = 544 nm at pH 7). The pKa of proton acceptor (Asp121) for the Schiff base, is approximately 5.9, so GR can translocate H+ under physiological conditions (pH 7.4). In order to prove the functional activity in the cell, pumping activity was measured in the sphaeroplast membranes of E. coli and one of Gloeobacter whole cell. The efficient proton pumping and rapid photocycle of GR strongly suggests that Gloeobacter rhodopsin functions as a proton pumping in its natural environment, probably compensating the shortage of energy generated by chlorophyll-based photosynthesis without thylakoids. PMID:25347537

  8. Cultivation and Complete Genome Sequencing of Gloeobacter kilaueensis sp. nov., from a Lava Cave in Kīlauea Caldera, Hawai'i

    PubMed Central

    Saw, Jimmy H. W.; Schatz, Michael; Brown, Mark V.; Kunkel, Dennis D.; Foster, Jamie S.; Shick, Harry; Christensen, Stephanie; Hou, Shaobin; Wan, Xuehua; Donachie, Stuart P.

    2013-01-01

    The ancestor of Gloeobacter violaceus PCC 7421T is believed to have diverged from that of all known cyanobacteria before the evolution of thylakoid membranes and plant plastids. The long and largely independent evolutionary history of G. violaceus presents an organism retaining ancestral features of early oxygenic photoautotrophs, and in whom cyanobacteria evolution can be investigated. No other Gloeobacter species has been described since the genus was established in 1974 (Rippka et al., Arch Microbiol 100:435). Gloeobacter affiliated ribosomal gene sequences have been reported in environmental DNA libraries, but only the type strain's genome has been sequenced. However, we report here the cultivation of a new Gloeobacter species, G. kilaueensis JS1T, from an epilithic biofilm in a lava cave in Kīlauea Caldera, Hawai'i. The strain's genome was sequenced from an enriched culture resembling a low-complexity metagenomic sample, using 9 kb paired-end 454 pyrosequences and 400 bp paired-end Illumina reads. The JS1T and G. violaceus PCC 7421T genomes have little gene synteny despite sharing 2842 orthologous genes; comparing the genomes shows they do not belong to the same species. Our results support establishing a new species to accommodate JS1T, for which we propose the name Gloeobacter kilaueensis sp. nov. Strain JS1T has been deposited in the American Type Culture Collection (BAA-2537), the Scottish Marine Institute's Culture Collection of Algae and Protozoa (CCAP 1431/1), and the Belgian Coordinated Collections of Microorganisms (ULC0316). The G. kilaueensis holotype has been deposited in the Algal Collection of the US National Herbarium (US# 217948). The JS1T genome sequence has been deposited in GenBank under accession number CP003587. The G+C content of the genome is 60.54 mol%. The complete genome sequence of G. kilaueensis JS1T may further understanding of cyanobacteria evolution, and the shift from anoxygenic to oxygenic photosynthesis. PMID:24194836

  9. Cultivation and complete genome sequencing of Gloeobacter kilaueensis sp. nov., from a lava cave in Kīlauea Caldera, Hawai'i.

    PubMed

    Saw, Jimmy H W; Schatz, Michael; Brown, Mark V; Kunkel, Dennis D; Foster, Jamie S; Shick, Harry; Christensen, Stephanie; Hou, Shaobin; Wan, Xuehua; Donachie, Stuart P

    2013-01-01

    The ancestor of Gloeobacter violaceus PCC 7421(T) is believed to have diverged from that of all known cyanobacteria before the evolution of thylakoid membranes and plant plastids. The long and largely independent evolutionary history of G. violaceus presents an organism retaining ancestral features of early oxygenic photoautotrophs, and in whom cyanobacteria evolution can be investigated. No other Gloeobacter species has been described since the genus was established in 1974 (Rippka et al., Arch Microbiol 100:435). Gloeobacter affiliated ribosomal gene sequences have been reported in environmental DNA libraries, but only the type strain's genome has been sequenced. However, we report here the cultivation of a new Gloeobacter species, G. kilaueensis JS1(T), from an epilithic biofilm in a lava cave in Kīlauea Caldera, Hawai'i. The strain's genome was sequenced from an enriched culture resembling a low-complexity metagenomic sample, using 9 kb paired-end 454 pyrosequences and 400 bp paired-end Illumina reads. The JS1(T) and G. violaceus PCC 7421(T) genomes have little gene synteny despite sharing 2842 orthologous genes; comparing the genomes shows they do not belong to the same species. Our results support establishing a new species to accommodate JS1(T), for which we propose the name Gloeobacter kilaueensis sp. nov. Strain JS1(T) has been deposited in the American Type Culture Collection (BAA-2537), the Scottish Marine Institute's Culture Collection of Algae and Protozoa (CCAP 1431/1), and the Belgian Coordinated Collections of Microorganisms (ULC0316). The G. kilaueensis holotype has been deposited in the Algal Collection of the US National Herbarium (US# 217948). The JS1(T) genome sequence has been deposited in GenBank under accession number CP003587. The G+C content of the genome is 60.54 mol%. The complete genome sequence of G. kilaueensis JS1(T) may further understanding of cyanobacteria evolution, and the shift from anoxygenic to oxygenic photosynthesis.

  10. Gloeobacter Rhodopsin, Limitation of Proton Pumping at High Electrochemical Load

    PubMed Central

    Vogt, Arend; Wietek, Jonas; Hegemann, Peter

    2013-01-01

    We studied the photocurrents of a cyanobacterial rhodopsin Gloeobacter violaceus (GR) in Xenopus laevis oocytes and HEK-293 cells. This protein is a light-driven proton pump with striking similarities to marine proteorhodopsins, including the D121-H87 cluster of the retinal Schiff base counterion and a glutamate at position 132 that acts as a proton donor for chromophore reprotonation during the photocycle. Interestingly, at low extracellular pHo and negative voltage, the proton flux inverted and directed inward. Using electrophysiological measurements of wild-type and mutant GR, we demonstrate that the electrochemical gradient limits outward-directed proton pumping and converts it into a purely passive proton influx. This conclusion contradicts the contemporary paradigm that at low pH, proteorhodopsins actively transport H+ into cells. We identified E132 and S77 as key residues that allow inward directed diffusion. Substitution of E132 with aspartate or S77 with either alanine or cysteine abolished the inward-directed current almost completely. The proton influx is likely caused by the pKa of E132 in GR, which is lower than that of other microbial ion pumping rhodopsins. The advantage of such a low pKa is an acceleration of the photocycle and high pump turnover at high light intensities. PMID:24209850

  11. Conformational Transitions Underlying Pore Opening and Desensitization in Membrane-embedded Gloeobacter violaceus Ligand-gated Ion Channel (GLIC)

    PubMed Central

    Velisetty, Phanindra; Chalamalasetti, Sreevatsa V.; Chakrapani, Sudha

    2012-01-01

    Direct structural insight into the mechanisms underlying activation and desensitization remain unavailable for the pentameric ligand-gated channel family. Here, we report the structural rearrangements underlying gating transitions in membrane-embedded GLIC, a prokaryotic homologue, using site-directed spin labeling and electron paramagnetic resonance (EPR) spectroscopy. We particularly probed the conformation of pore-lining second transmembrane segment (M2) under conditions that favor the closed and the ligand-bound desensitized states. The spin label mobility, intersubunit spin-spin proximity, and the solvent-accessibility parameters in the two states clearly delineate the underlying protein motions within M2. Our results show that during activation the extracellular hydrophobic region undergoes major changes involving an outward translational movement, away from the pore axis, leading to an increase in the pore diameter, whereas the lower end of M2 remains relatively immobile. Most notably, during desensitization, the intervening polar residues in the middle of M2 move closer to form a solvent-occluded barrier and thereby reveal the location of a distinct desensitization gate. In comparison with the crystal structure of GLIC, the structural dynamics of the channel in a membrane environment suggest a more loosely packed conformation with water-accessible intrasubunit vestibules penetrating from the extracellular end all the way to the middle of M2 in the closed state. These regions have been implicated to play a major role in alcohol and drug modulation. Overall, these findings represent a key step toward understanding the fundamentals of gating mechanisms in this class of channels. PMID:22977232

  12. Cytotoxic sulfated triterpene glycosides from the sea cucumber Pseudocolochirus violaceus.

    PubMed

    Zhang, Shu-Yu; Yi, Yang-Hua; Tang, Hai-Feng

    2006-07-01

    Bioassay-guided fractionation of the active BuOH extract of the sea cucumber Pseudocolochirus violaceus resulted in the isolation of three new sulfated triterpene glycosides, i.e., violaceusides I, II, and III (1-3, resp.), as active compounds causing morphological abnormality of Pyricularia oryzae mycelia. Their structures were elucidated by spectroscopic methods including 2D-NMR and MS experiments, as well as chemical evidence. Compounds 1-3 exhibit the same structural features, i.e., the presence of a 16-oxo group in the holostane-type triterpene aglycone with the C(7)=C(8) bond, but differ in the side chains and the tetrasaccharide moieties. Compound 1 possesses one sulfate group, while 2 and 3 are disulfated glycosides. All the glycosides showed significant in vitro cytotoxicities against human gastric cancer MKN-45 and human colon cancer HCT-116 cells. PMID:17193313

  13. Anthracycline metabolites from Streptomyces violaceus A262. I. Isolation of antibiotic-blocked mutants from Streptomyces violaceus A262.

    PubMed

    Johdo, O; Ishikura, T; Yoshimoto, A; Takeuchi, T

    1991-10-01

    Five mutant (or variant) strains producing new anthracycline antibiotics were derived from Streptomyces violaceus A262 by mutagenesis treatment. Strain SE1-625 showed a limited production of three known beta-rhodomycinone diglycosides while the parent strain produced numerous unidentified beta-rhodomycinone glycosides. Strain SU2-730 was an antibiotic-blocked mutant which produced only epsilon-rhodomycinone glycosides (named epelmycins). Strains SC-7 and SE2-2385 were variants which produced alpha-citromycinone glycosides (named yellamycins) and beta-isorhodomycinone glycosides (named obelmycins), respectively. Strain SE2-2385-A1 produced alpha 2-rhodomycinone glycosides (named alldimycins). Glycosidation-less mutants which accumulated only aglycone were also obtained. Isolation of these mutants or variants and preliminary identification of their anthracycline products are described. PMID:1955394

  14. Production and characterization of an extracellular polysaccharide from Streptomyces violaceus MM72.

    PubMed

    Manivasagan, Panchanathan; Sivasankar, Palaniappan; Venkatesan, Jayachandran; Senthilkumar, Kalimuthu; Sivakumar, Kannan; Kim, Se-Kwon

    2013-08-01

    The isolation, optimization, purification and characterization of an extracellular polysaccharide (EPS) from a marine actinobacterium, Streptomyces violaceus MM72 were investigated. Medium composition and culture conditions for the EPS production by S. violaceus MM72 were optimized using two statistical methods: Plackett-Burman design applied to find the key ingredients and conditions for the best yield of EPS production and central composite design used to optimize the concentration of the three significant variables: glucose, tryptone and NaCl. The preferable culture conditions for EPS production were pH 7.0, temperature 35°C and NaCl concentration 2.0% for 120h with fructose and yeast extract as best carbon and nitrogen sources, respectively. The results showed that S. violaceus MM72 produced a kind of EPS having molecular weight of 8.96×10(5)Da. In addition, the EPS showed strong DPPH radical-scavenging activity, superoxide scavenging and metal chelating activities while moderate inhibition of lipid peroxidation and reducing activities determined in this study. These results showed the great potential of EPS produced by S. violaceus MM72 could be used in industry in place of synthetic compounds. The EPS from S. violaceus MM72 may be a new source of natural antioxidants with potential value for health, food and therapeutics. PMID:23597709

  15. Induction of beta-galactosidase in Streptomyces violaceus.

    PubMed

    Sanchez, J; Hardisson, C

    1979-07-01

    Synthesis of beta-galactosidase by Streptomyces violaceus was induced by D-galactose and L-arabinose, and to a lesser extent by lactose, D-arabinose, and methyl-beta-D-galactopyranoside. The synthesis of the enzyme was linear and started to increase 2--3 h after induction by galactose, reaching a maximum after 5--7 h. The highest level of specific activity was observed in 2% galactose, with an increase of 45 times over the basal level in glycerol. Isopropyl-beta-D-thiogalactopyranoside (IPTG) and methyl-beta-D-thiogalactopyranoside (TMG) inhibited induction by D-galactose, but did not influence enzymatic activity. Cellular extracts hydrolyzed O-nitrophenyl-beta-D-galactopyranoside, but did not significantly hydrolyze lactose, melibiose, p-nitrophenyl-alpha-D-galactopyranoside, p-nitrophenyl-beta-D-fucoside, or p-nitrophenyl-beta-D-glucopyranoside. Rifampicin and chloramphenicol inhibited beta-galactosidase synthesis in non-preinduced and in preinduced cells. The inhibition by chloramphenicol was reversible. PMID:113072

  16. Efficient femtosecond energy transfer from carotenoid to retinal in gloeobacter rhodopsin-salinixanthin complex.

    PubMed

    Iyer, E Siva Subramaniam; Gdor, Itay; Eliash, Tamar; Sheves, Mordechai; Ruhman, Sanford

    2015-02-12

    The retinal proton pump xanthorhodopsin (XR) was recently found to function with an attached carotenoid light harvesting antenna, salinixanthin (SX). It is intriguing to discover if this departure from single chromophore architecture is singular or if it has been adopted by other microbial rhodopsins. In search of other cases, retinal protein encoding genes in numerous bacteria have been identified containing sequences corresponding to carotenoid binding sites like that in XR. Gloeobacter rhodopsin (GR), exhibiting particularly close homology to XR, has been shown to attach SX, and fluorescence measurements suggest SX can function as a light harvesting (LH) antenna in GR as well. In this study, we test this suggestion in real time using ultrafast transient absorption. Results show that energy transfer indeed occurs from S2 of SX to retinal in the GR-SX composite with an efficiency of ∼40%, even higher than that in XR. This validates the earlier fluorescence study, and supports the notion that many microbial retinal proteins use carotenoid antennae to harvest light.

  17. Geographic variation in thermal physiological performance of the intertidal crab Petrolisthes violaceus along a latitudinal gradient.

    PubMed

    Gaitán-Espitia, Juan Diego; Bacigalupe, Leonardo D; Opitz, Tania; Lagos, Nelson A; Timmermann, Tania; Lardies, Marco A

    2014-12-15

    Environmental temperature has profound effects on the biological performance and biogeographical distribution of ectothermic species. Variation of this abiotic factor across geographic gradients is expected to produce physiological differentiation and local adaptation of natural populations depending on their thermal tolerances and physiological sensitivities. Here, we studied geographic variation in whole-organism thermal physiology of seven populations of the porcelain crab Petrolisthes violaceus across a latitudinal gradient of 3000 km, characterized by a cline of thermal conditions. Our study found that populations of P. violaceus show no differences in the limits of their thermal performance curves and demonstrate a negative correlation of their optimal temperatures with latitude. Additionally, our findings show that high-latitude populations of P. violaceus exhibit broader thermal tolerances, which is consistent with the climatic variability hypothesis. Interestingly, under a future scenario of warming oceans, the thermal safety margins of P. violaceus indicate that lower latitude populations can physiologically tolerate the ocean-warming scenarios projected by the IPCC for the end of the twenty-first century.

  18. Geographic variation in thermal physiological performance of the intertidal crab Petrolisthes violaceus along a latitudinal gradient.

    PubMed

    Gaitán-Espitia, Juan Diego; Bacigalupe, Leonardo D; Opitz, Tania; Lagos, Nelson A; Timmermann, Tania; Lardies, Marco A

    2014-12-15

    Environmental temperature has profound effects on the biological performance and biogeographical distribution of ectothermic species. Variation of this abiotic factor across geographic gradients is expected to produce physiological differentiation and local adaptation of natural populations depending on their thermal tolerances and physiological sensitivities. Here, we studied geographic variation in whole-organism thermal physiology of seven populations of the porcelain crab Petrolisthes violaceus across a latitudinal gradient of 3000 km, characterized by a cline of thermal conditions. Our study found that populations of P. violaceus show no differences in the limits of their thermal performance curves and demonstrate a negative correlation of their optimal temperatures with latitude. Additionally, our findings show that high-latitude populations of P. violaceus exhibit broader thermal tolerances, which is consistent with the climatic variability hypothesis. Interestingly, under a future scenario of warming oceans, the thermal safety margins of P. violaceus indicate that lower latitude populations can physiologically tolerate the ocean-warming scenarios projected by the IPCC for the end of the twenty-first century. PMID:25394627

  19. Revision of Campsurus violaceus species group (Ephemeroptera: Polymitarcyidae) with new synonymies and nomina dubia in Campsurus Eaton, 1868.

    PubMed

    Molineri, C; Salles, F F; Emmerich, D

    2015-01-01

    The violaceus species group (formerly notatus species group) of Campsurus Eaton is revised. All the species in the violaceus group are diagnosed. A new species, C. molinai sp. nov. is described based on male imagos from Bolivia, characterized by their large and sclerotized penes. The violaceus group is proposed to include the following species: C. assimilis Traver, C. truncatus Ulmer (=C. mahunkai Puthz = C. melanocephalus Pereira & da Silva, new synonyms), C. violaceus Needham & Murphy (= C. meyeri Navás = C. notatus Needham & Murphy = C. paranensis Navás, new synonyms), C. emersoni Traver, C. decoloratus (Hagen), and C. molinai sp.nov. Additionally we consider the following species as nomina dubia: C. longicauda Navás, C. pfeifferi Navás, C. zikani Navás, C. albicans (orig. Ephemera albicans Percheron in Guerin & Percheron), C. burmeisteri Ulmer, C. dallasi Navás, C. quadridentatus Eaton, C. claudus Needham & Murphy, C. corumbanus Needham & Murphy, C. dorsalis (Burmeister), C. mutilus Needham & Murphy, and C. striatus Needham & Murphy. Given the results presented herein (five species synonymized and 12 proposed as nomina dubia), only 28 valid species remain in the genus Campsurus. Additionally, the nymphal stages of C. violaceus and C. truncatus are described and illustrated. Female adult genitalia (sockets) and eggs of C. decoloratus are described for the first time. Diagnoses, new country records, and redescriptions of selected characters of the imagos for the species of the violaceus group are given. PMID:25781239

  20. Different timing and spatial separation of parental chromosomes in intergeneric somatic hybrids between Brassica napus and Orychophragmus violaceus.

    PubMed

    Ding, L; Zhao, Z G; Ge, X H; Li, Z Y

    2014-01-01

    Experimental and newly formed hybrids and polyploids generated by wide crosses usually show varying degrees of cytological instability. The spatial separation of parental genomes and uniparental chromosome elimination in hybrid cells has been reported in many hybrids from plants and animals. Herein, the behavior of parental genomes in intergeneric somatic hybrids between Brassica napus and Orychophragmus violaceus was analyzed using genomic in situ hybridization (GISH). In mitotic and meiotic cells, the chromosomes from O. violaceus were distinguished from B. napus by their larger size and staining patterns. In interphase nuclei of the hybrid, O. violaceus-labeled chromatin appeared as large heterochromatic blocks that were nonrandomly distributed at prophase, typically distributed toward one side of the nucleus. In pollen mother cells at prophase I of meiosis, O. violaceus chromosomes appeared as one or two deeply stained chromatin blocks that resolved into bivalents at a late stage, after bivalents from B. napus were visible. Thereafter, bivalents of O. violaceus congressed to the equatorial plate and segregated at anaphase I after those from B. napus. The different behavior of O. violaceus chromosomes in the hybrids indicates that they have differential condensation states at interphase and progress later through the cell cycle and meiosis than B. napus chromosomes. This difference in behavior may restrict or prevent the formation of bivalents of mixed genome origin. Differential gene expression of parental alleles including rDNA loci may contribute to their distinct cytological behavior and to the phenotype of hybrids. PMID:24782049

  1. Two copepod species largely confused: Asterocheres echinicola (Norman, 1868) and A. violaceus (Claus, 1889). Taxonomical implications

    NASA Astrophysics Data System (ADS)

    Bandera, M. Eugenia; Conradi, Mercedes

    2009-12-01

    Due to its extremely brief description, Asterocheres echinicola (Norman, 1868) has been confused with some Asterocheres species such as Asterocheres suberitis Giesbrecht, 1897, Asterocheres parvus Giesbrecht, 1897 and Asterocheres latus (Brady, 1872). Furthermore, this species has been considered conspecific with Cyclopicera lata (Brady, 1872) and Asterocheres kervillei Canu, 1898. The objective of this paper is to study the syntypes of Asterocheres echinicola deposited in the Museum of Natural History of London together with abundant material from this and other institutions. Re-examination of these syntypes revealed that Asterocheres echinicola was conspecific with the currently known Asterocheres species, A. violaceus. Therefore, this latter species should be considered as a junior synonym of the former. The specimens described by Brady as Cyclopicera lata represent distinctively Asterocheres echinicola (= Asterocheres violaceus) and are identical to Sars’s Ascomyzom parvum and to Giesbrecht’s Asterocheres echinicola. We propose to rename Cyclopicera lata as Asterocheres latus (Brady, 1872), and raise Sars’ Ascomyzon latus, a species which is different from Asterocheres echinicola (= Asterocheres violaceus) and from Asterocheres latus (= Cyclopicera lata), as a new species. In this paper, we not only redescribe both species A. echinicola and A. latus, but also compare them with their previous descriptions, with the new material available and with their congeners. The redescription of Asterocheres latus revealed new specific differences between this species and Asterocheres kervillei, a species considered as synonymous of Asterocheres latus for almost 40 years. We strongly recommend that these differences are sufficient to consider these two species different. Finally, we analyzed the implications of all these taxonomical changes with respect to the diversity of the hosts utilized by these copepods and their geographical distribution.

  2. Glucose inhibibion of galactose-induced synthesis of beta-galactosidase in Streptomyces violaceus.

    PubMed

    Sánchez, J; Hardisson, C

    1980-03-01

    Various carbon compounds inhibited galactose induced synthesis of a beta-galactosidase activity in Streptomyces violaceus. Glucose and 2-deoxyglucose, but not methyl-alpha-D-glucose, caused inhibition of galactose uptake activity. In addition, glucose, or one of its metabolites, inhibited the synthesis of the glactose uptake system. Therefore it is concluded that the main inhibitory activity of glucose on galactose induced enzyme synthesis is exerted through inducer exclusion. Other carbon sources, such as D-ribose, D-gluconate, cellobiose or DL-alpha-glycerophosphate, did not inhibit uptake of the inducer galactose and may exert their effect through catabolite repression, inactivation or direct enzyme inhibition. PMID:6770791

  3. [Amylase inhibitors from Streptomyces lucensis VKPM Ac-1743 and Streptomyces violaceus VKPM Ac-1734].

    PubMed

    Sharova, N Iu

    2015-01-01

    Inhibitors synthesized by the Streptomyces lucensis VKPM AS-1743 and Streptomyces violaceus VKPM AS-1734 strains were studied for their influence on amylases of different origin. The effect of the inhibitors was shown to be different on fungal amylase, pancreatic amylase, and amylase from human blood. It has been found that the studied inhibitors are substances of a pseudooligosaccharide nature and exhibit their activity and stability over a wide range of pH and temperature values. The physico-chemical and biochemical properties of isolated inhibitors were compared with those of known microbial inhibitors of α-glucosidases. PMID:25842903

  4. [Amylase inhibitors from Streptomyces lucensis VKPM Ac-1743 and Streptomyces violaceus VKPM Ac-1734].

    PubMed

    Sharova, N Iu

    2015-01-01

    Inhibitors synthesized by the Streptomyces lucensis VKPM AS-1743 and Streptomyces violaceus VKPM AS-1734 strains were studied for their influence on amylases of different origin. The effect of the inhibitors was shown to be different on fungal amylase, pancreatic amylase, and amylase from human blood. It has been found that the studied inhibitors are substances of a pseudooligosaccharide nature and exhibit their activity and stability over a wide range of pH and temperature values. The physico-chemical and biochemical properties of isolated inhibitors were compared with those of known microbial inhibitors of α-glucosidases.

  5. New rhodomycin analogs, SS-288A and SS-288B, produced by a Streptomyces violaceus A262 mutant.

    PubMed

    Saito, S; Katsuda, Y; Johdo, O; Yoshimoto, A

    1995-01-01

    Two new rhodomycin metabolites, SS-288A and SS-288B, were specifically produced by a blocked mutant obtained from Streptomyces violaceus A262 and were respectively identified as 7,10-di(O-rhodosaminyl-deoxyfucosyl-deoxyfucosyl)-beta -rhodomycinone and -beta-isorhodomycinone. PMID:7765964

  6. Parental Genome Separation and Elimination of Cells and Chromosomes Revealed by AFLP and GISH analyses in a Brassica carinata × Orychophragmus violaceus Cross

    PubMed Central

    HUA, YU-WEI; LIU, MIN; LI, ZAI-YUN

    2006-01-01

    • Background and Aims The phenomenon of parental genome separation during the mitotic divisions of hybrid cells was proposed to occur under genetic control in intergeneric hybrids between cultivated Brassica species and Orychophragmus violaceus (2n = 24). To elucidate further the cytological and molecular mechanisms behind parental genome separation, Brassica carinata (2n = 34) × O. violaceus hybrids were resynthesized and their chromosome/genomic complements analysed. • Methods F1 hybrids of the cross were obtained following embryo rescue, and were investigated for their cytological behaviour and subjected to genomic in situ hybridization (GISH) and amplified fragment length polymorphism (AFLP) to determine the contribution of parental genomes. • Key Results All the F1 plants with high fertility closely resembled B. carinata in morphological attributes. These were mixoploids with 2n chromosome numbers ranging from 17 to 35; however, 34, the same number as in B. carinata, was the most frequent number of chromosomes in ovary and pollen mother cells (PMCs). GISH clearly identified 16 chromosomes of B. nigra in ovary cells and PMCs with 2n = 34 and 35. However, no O. violaceus chromosome was detected, indicating the presence of the intact B. carinata genome and elimination of the entire O. violaceus genome. However, some AFLP bands specific for O. violaceus and novel for the two parents were detected in the leaves. Cells with fewer than 34 chromosomes had lost some B. oleracea chromosomes. F2 plants were predominantly like B. carinata, but some contained O. violaceus characters. • Conclusions The cytological mechanism for the results involves complete and partial genome separation at mitosis in embryos of F1 plants followed by chromosome doubling, elimination of cells with O. violaceus chromosomes and some introgression of O. violaceus genetic information. PMID:16624845

  7. Male satin bowerbirds (Ptilonorhynchus violaceus) compensate for sexual signal loss by enhancing multiple display features

    NASA Astrophysics Data System (ADS)

    Bravery, Benjamin D.; Goldizen, Anne W.

    2007-06-01

    Numerous studies have focussed on the relationship between female choice and the multiple exaggerated sexual traits of males. However, little is known about the ability of males to actively enhance specific components of their display in response to the loss of one component. We investigated the capacity of male satin bowerbirds (Ptilonorhynchus violaceus) to respond to the loss of one of their sexual signals by performing an experiment in which we removed decorations at their bowers. We found that males compensated for decoration loss by increasing bower construction behaviour and decreasing their latency to bower painting. These results are novel because they suggest that males can assess the quality of their own display and make decisions about how to augment their displays. We discuss these results in the context of previous studies of mate choice in satin bowerbirds, as both of the supplementary behaviours we observed are known correlates of male mating success.

  8. Two new bioactive triterpene glycosides from the sea cucumber Pseudocolochirus violaceus.

    PubMed

    Zhang, Shu-Yu; Yi, Yang-Hua; Tang, Hai-Feng; Li, Ling; Sun, Peng; Wu, Jun

    2006-01-01

    By activity-guided fractionation, two new triterpene glycosides, violaceusides A (1) and B (2), were isolated from the sea cucumber Pseudocolochirus violaceus as active compounds causing morphological abnormality of Pyricularia oryzae mycelia. By extensive 2D NMR techniques and chemical evidence, the structures of the two new glycosides were established as 16beta-acetoxy-3-O-[3-O-methyl-beta-D-glucopyranosyl-(1 --> 3)-beta-D-xylopyranosyl-(1 --> 4)-beta-D-quinovopyranosyl-(1 --> 2)-4-O-sodiumsulphate-beta-D-xylopyranosyl]-holosta-7,24-diene-3beta-ol (1) and 16beta-acetoxy-3-O-[3-O-methyl-beta-D-glucopyranosyl-(1 --> 3)-beta-D-xylopyranosyl-(1 --> 4)-beta-D-glucopyranosyl-(1 --> 2)-4-O-sodiumsulphate-beta-D-xylopyranosyl]-holosta-7,24-diene-3beta-ol (2), respectively. The two glycosides also exhibited significant cytotoxicity against HL-60 and BEL-7402 cancer cell lines. PMID:16753775

  9. Anthracycline metabolites from Streptomyces violaceus A262. III. New anthracycline obelmycins produced by a variant strain SE2-2385.

    PubMed

    Johdo, O; Watanabe, Y; Ishikura, T; Yoshimoto, A; Naganawa, H; Sawa, T; Takeuchi, T

    1991-10-01

    New anthracycline antibiotics, designated as obelmycins A, D, E, F and G, were isolated from the culture broth of a variant strain of beta-rhodomycin-producing Streptomyces violaceus A262, identified as beta-isorhodomycinone glycosides and gamma-isorhodomycinone glycosides and assayed for their in vitro cytotoxicities against murine leukemic L1210 cell culture and the antimicrobial activities in comparison with some known anthracyclines. PMID:1955396

  10. Alteration of chromosome behavior and synchronization of parental chromosomes after successive generations in Brassica napus x Orychophragmus violaceus hybrids.

    PubMed

    Zhao, Zhigang; Ma, Ni; Li, Zaiyun

    2007-02-01

    In an earlier study, the progenies of intergeneric hybrids Brassica napus (2n = 38) x Orychophragmus violaceus (2n = 24) were investigated in successive generations (F1-F4) for the cytological phenomenon of parental genome separation during mitotic and meiotic division. In the present study, inbred lines (F5-F8) derived from 1 such hybrid were characterized for morphology, chromosome pairing behaviour, and genome composition. One F5 plant (2n = 31) with slightly yellow petals and 12:19 and 15:16 segregation ratios in its pollen mother cells (PMCs) produced F6 plants with distinct morphological characteristics and wide variations in fertility and chromosome numbers (2n = 25-38). F7 and F8 lines with distinctive morphology and wide ranges in chromsome numbers were established. In PMCs of F7 plants from 4 F6 plants, 0-12 labelled chromosomes from O. violaceus, which predominantly appeared as bivalents, were identified by genomic in situ hybridization. They behaved synchronously with B. napus chromosomes during meiotic division. The results provide molecular cytogenetic evidence of the inclusion of O. violaceus chromosomes in the original hybrids and the cytology in the hybrids documented earlier. They also show that chromosome behaviour was altered and the parental chromosomes became synchronized after successive generations.

  11. Genome doubling and chromosome elimination with fragment recombination leading to the formation of Brassica rapa-type plants with genomic alterations in crosses with Orychophragmus violaceus.

    PubMed

    Liu, Min; Li, Zai-Yun

    2007-11-01

    In distant hybridization of plants, nonclassical hybrids with unexpected chromosome complements, chromosome elimination, and genetic introgression have been well documented. We obtained intergeneric hybrids between Brassica rapa, B. rapa var. chinensis, and another cruciferous species, Orychophragmus violaceus, following embryo rescue. Hybrids mainly displayed phenotypes of B. rapa, although certain O. violaceus or novel characteristics also appeared. Variable numbers of chromosomes were observed in somatic cells in the roots of plantlets on medium and in ovaries and pollen mother cells (PMCs). However, higher numbers were recorded in the roots. GISH revealed that the majority of ovary cells and PMCs contained 20 chromosomes of B. rapa with or without individual O. violaceus chromosomes or fragments added or introgressed. AFLP analysis showed that fragments deleted from the B. rapa genome were much more frequent than novel and O. violaceus fragments. The mechanisms involved genome doubling and successive elimination of O. violaceus chromosomes accompanied by fragment recombination and introgression, producing B. rapa-type plants with modified genetic constitutions and phenotypes.

  12. Cloning and characterization of a glycosyltransferase gene involved in the biosynthesis of anthracycline antibiotic beta-rhodomycin from Streptomyces violaceus.

    PubMed

    Miyamoto, Yuji; Johdo, Osamu; Nagamatsu, Yasunori; Yoshimoto, Akihiro

    2002-01-10

    A glycosyltransferase gene, rhoG, involved in the biosynthesis of the anthracycline antibiotic beta-rhodomycin was isolated as a 4.1-kb DNA fragment containing rhoG and its flanking region from Streptomyces violaceus by degenerate and inverse PCR. Sequencing analysis showed that rhoG was located in a gene cluster involved in the biosynthesis of the constitutive deoxysugar of beta-rhodomycin. The function of rhoG was verified by gene disruption, which was generated by replacing the internal 0.9-kb region of S. violaceus chromosome with a fragment including the SacI-blunted region. The rhoG disruption resulted in complete loss of beta-rhodomycin productivity, along with the accumulation of a non-glycosyl intermediate epsilon-rhodomycinone. In addition, the complementation test demonstrated that rhoG restored beta-rhodomycin production in this gene disruptant. These results indicated that rhoG is the glycosyltransferase gene responsible for the glycosylation of epsilon-rhodomycinone in beta-rhodomycin biosynthesis. PMID:11814657

  13. Determination of methylenomycin A synthesis by the pSV1 plasmid from Streptomyces violaceus-ruber SANK 95570.

    PubMed

    Aguilar, A; Hopwood, D A

    1982-08-01

    A plasmid (pSV1) of 110 x 10(6) daltons from a methylenomycin A producing strain of Streptomyces violaceus-ruber was detected on an isolated from agarose gels. Elimination of this plasmid by protoplasting and regeneration resulted in the simultaneous loss of methylenomycin A production and resistance. pSV1 hybridized with pBR322 containing a cloned fragment of 1.7 x 10(6) daltons from S. coelicolor A3(2) which codes for methylenomycin A resistance. The pSV1 plasmid could be transferred to S. lividans by conjugation and by transformation and plasmid DNA identical in size to pSV1 could be isolated from the recipient strains. These experiments show that pSV1 codes for methylenomycin A production and resistance, in close analogy to the SCP1 plasmid from S. coelicolor A3(2). PMID:7142961

  14. Anthracycline metabolites from Streptomyces violaceus A262. II. New anthracycline epelmycins produced by a blocked mutant strain SU2-730.

    PubMed

    Johdo, O; Watanabe, Y; Ishikura, T; Yoshimoto, A; Naganawa, H; Sawa, T; Takeuchi, T

    1991-10-01

    New anthracycline antibiotics, identified as epsilon-rhodomycinone glycosides, were isolated from the culture broth of a blocked mutant of beta-rhodomycin-producing Streptomyces violaceus A262. They were designated as epelmycins A, B, C, D and E, and assayed for their in vitro cytotoxicities against murine leukemic L1210 cell culture and the antimicrobial activities in comparison with known anthracycline antibiotics. PMID:1955395

  15. Origin of new Brassica types from a single intergeneric hybrid between B. rapa and Orychophragmus violaceus by rapid chromosome evolution and introgression.

    PubMed

    Xu, Chuan-Yuan; Wan-Yan, Rui-Hong; Li, Zai-Yun

    2007-12-01

    Many novel lines were established from an intergeneric mixoploid between Brassica rapa (2n = 20) and Orychophragmus violaceus (2n = 24) through successive selections for fertility and viability. Pedigrees of individual F(2) plants were advanced to the 10th generation by selfing. Their breeding habit was self-compatible and different from the self-incompatibility of their female parent B. rapa, and these lines were reproductively isolated to different degrees from B. rapa and B. napus. The lines with high productivity showed not only a wide spectrum of phenotypes but also obvious variations in fatty acid profiles of seed oil and glucosinolate contents in seed meal. These lines had 2n = 36, 37, 38, 39 and 40, with 2n = 38 being most frequent (64.56%), and no intact O. violaceus chromosomes were detected by genomic in situ hybridization (GISH) analysis. Amplified fragment length polymorphism (AFLP) analyses revealed a high extent of variation in genomic compositions across all the lines. O. violaceus-specific bands, deleted bands in B. rapa and novel bands for two parents were detected in these lines, with novel bands being the most frequent. The morphological and genetic divergence of these novel types derived from a single hybrid is probably due to rapid chromosomal evolution and introgression, and provides new genetic resources for rapeseed breeding.

  16. Heterocyst differentiation in the cyanobacterium Mastigocladus laminosus

    SciTech Connect

    Nierzwicki-Bauer, S.A.; Balkwill, D.L.; Stevens, S.E. Jr.

    1984-02-01

    The morphological and ultrastructural aspects of heterocyst differentiation in the branching, filamentous cyanobacterium Mastigocladus laminosus were examined with light and electron microscopy. The earliest differentation stages involved cytoplasmic changes, including rapid degradation of carboxysomes, degradation of polysaccharide granules, and accumulation of electron-dense ribosomal or protein material (or both). Intermediate differentiation stages involved synthesis of a homogeneous extra wall layer development of necks leading to adjacent cells, and elaboration of a complex system of intracytoplasmic membranes. Late differentiation stages included further development of necks and continued elaboration of membranes. Mature heterocysts possessed a uniformly electron-dense cytoplasm that contained large numbers of closely packed membranes, some of which were arranged in lamellar stacks. Mature heterocysts lacked all of the inclusion bodies present in undifferentiated vegetative cells, but contained a number of unusual spherical inclusions of variable electron density. Cells in both narrow and wide filaments were capable of differentiating. Heterocysts developed at a variety of locations in the wide, branching filaments, although the majority of them were situated adjacent to branch points. M. laminosus displayed a marked tendency to produce sets of adjacent heterocysts or proheterocysts (or both) that were not separated from each other by vegetative cells. Groups of four or more adjacent heterocysts or proheterocysts occurred frequently in wide filaments, and in some of these filaments virtually all of the cells appeared to be capable of differentiating into heterocysts.

  17. A novel cyanobacterium exhibiting an elevated tolerance for iron.

    PubMed

    Brown, Igor I; Mummey, Daniel; Cooksey, Keith E

    2005-05-01

    Studies directed at cyanobacteria inhabiting iron-depositing hot springs may provide insights into the role of both ancient and contemporary cyanobacteria mediated iron transformations. Here we phylogenetically, morphologically and physiologically characterize a novel cyanobacterium isolated from an iron-depositing hot spring. Phylogenetic analyses indicate that the bacterium is a representative of a new genus, exhibiting a maximum 95.2% homology to database sequences. The isolate is a unicellular cyanobacterium with bladder-like cells typically packed as duplexes, or in extracellular polymeric substance covered clumps and small chains without the ability to produce baeocystes. No growth without added combined nitrogen occurred. While requiring relatively large amounts of iron for growth (>40microM), the isolate was shown to facilitate removal of iron from culture media. These results suggest that the isolate may be an important component of an iron-depositing microbial community. The name "Chroogloeocystis siderophila" for this cyanobacterium is proposed. PMID:16329916

  18. Production of a new hybrid anthracycline 4-O-methylepelmycin by heterologous expression of dnrK in epelmycin-producing Streptomyces violaceus.

    PubMed

    Miyamoto, Y; Ohta, S; Johdo, O; Nagamatsu, Y; Yoshimoto, A

    2000-08-01

    A new hybrid anthracycline antibiotic was produced by heterologous expression of dnrK encoding carminomycin 4-O-metyltransferase in an epelmycin-producing Streptomyces violaceus. pMK100 was constructed by insertion of Steptomyces peucetius dnrK gene in Steptomyces-expression vector pIJ6021 and introduced to the epelmycin producer. The transformant produced a hybrid anthracycline antibiotic together with host epelmycins when cultured in antibiotic production medium in the presence of thiostrepton. The hybrid anthracycline was determined to be 7-O-L-rhodosaminyl-4-O-methyl-epsilon-rhodomycinone (4-O-methylepelmycin D). However, the attempts on production of hybrid 4-O-methylaclarubicin and 4-O-methyl-1-deoxyobelmycin by the transformants of aclarubicin and 1-deoxyobelmycin producers with pMK 100 were unsuccessful. PMID:11079805

  19. Complete Genome Sequence of the Cyanobacterium Anabaena sp. 33047

    PubMed Central

    2016-01-01

    This study presents the complete nucleotide sequence of Anabaena sp. ATCC 33047 (Anabaena CA), a filamentous, nitrogen-fixing marine cyanobacterium, which under salt stress conditions accumulates sucrose internally. The elucidation of the genome will contribute to the understanding of cyanobacterial diversity. PMID:27516507

  20. A primitive cyanobacterium as pioneer microorganism for terraforming Mars.

    PubMed

    Friedmann, E I; Ocampo-Friedmann, R

    1995-03-01

    The primitive characteristics of the cyanobacterium Chroococcidiopsis suggest that it represents a very ancient type of the group. Its morphology is simple but shows a wide range of variability, and it resembles certain Proterozoic microfossils. Chroococcidiopsis is probably the most desiccation-resistant cyanobacterium, the sole photosynthetic organism in extreme arid habitats. It is also present in a wide range of other extreme environments, from Antarctic rocks to thermal springs and hypersaline habitats, but it is unable to compete with more specialized organisms. Genetic evidence suggests that all forms belong to a single species. Its remarkable tolerance of environmental extremes makes Chroococcidiopsis a prime candidate for use as a pioneer photosynthetic microorganism for terraforming of Mars. The hypolithic microbial growth form (which lives under stones of a desert pavement) could be used as a model for development of technologies for large-scale Martian farming.

  1. Biosynthesis of 130-kilodalton mosquito larvicide in the cyanobacterium Agmenellum quadruplicatum PR-6.

    PubMed

    Angsuthanasombat, C; Panyim, S

    1989-09-01

    The 130-kilodalton mosquito larvicidal gene, cloned from Bacillus thuringiensis var. israelensis, was introduced into the cyanobacterium Agmenellum quadruplicatum PR-6 by plasmid transformation. Transformed cells synthesized 130-kilodalton delta-endotoxin protein and showed mosquito larvicidal activity. Results demonstrate a potential use of a cyanobacterium for biological control of mosquitoes.

  2. Draft Genome Sequence of Exopolysaccharide-Producing Cyanobacterium Aphanocapsa montana BDHKU 210001

    PubMed Central

    Bhattacharyya, Sourav; Chandrababunaidu, Mathu Malar; Sen, Deeya; Panda, Arijit; Ghorai, Arpita; Bhan, Sushma; Sanghi, Neha

    2015-01-01

    We report for the first time the draft genome sequence of Aphanocapsa montana BDHKU 210001, a halotolerant cyanobacterium isolated from India. This is a marine exopolysaccharide (EPS)-producing cyanobacterium. The genome of this species is assembled into 11.50 million bases, with 296 scaffolds carrying approximately 7,296 protein-coding genes. PMID:25744997

  3. Chemokinetic motility responses of the cyanobacterium oscillatoria terebriformis

    NASA Technical Reports Server (NTRS)

    Richardson, Laurie L.; Castenholz, Richard W.

    1989-01-01

    Oscillatoria terebriformis, a gliding, filamentous, thermophilic cyanobacterium, exhibited an inhibition of gliding motility upon exposure to fructose. The observed response was transient, and the duration of nonmotility was directly proportional to the concentration of fructose. Upon resumption of motility, the rate of motility was also inversely proportional to the concentration of fructose. Sulfide caused a similar response. The effect of sulfide was specific and not due to either anoxia or negative redox potential. Exposure to glucose, acetate, lactate, or mat interstitial water did not elicit any motility response.

  4. Caldoramide, a Modified Pentapeptide from the Marine Cyanobacterium Caldora penicillata.

    PubMed

    Gunasekera, Sarath P; Imperial, Lorelie; Garst, Christiana; Ratnayake, Ranjala; Dang, Long H; Paul, Valerie J; Luesch, Hendrik

    2016-07-22

    The isolation, structure determination, and biological activities of a new linear pentapeptide, caldoramide (5), from the marine cyanobacterium Caldora penicillata from Florida are described. Caldoramide (5) has structural similarities to belamide A (4), dolastatin 10 (1), and dolastatin 15 (2). We profiled caldoramide against parental HCT116 colorectal cancer cells and isogenic cells lacking oncogenic KRAS or hypoxia-inducible factors 1α (HIF-1α) and 2α (HIF-2α). Caldoramide (5) showed differential cytotoxicity for cells containing both oncogenic KRAS and HIF over the corresponding knockout cells. LCMS dereplication indicated the presence of caldoramide (5) in a subset of C. penicillata samples. PMID:27380142

  5. Chlorophyll f-driven photosynthesis in a cavernous cyanobacterium.

    PubMed

    Behrendt, Lars; Brejnrod, Asker; Schliep, Martin; Sørensen, Søren J; Larkum, Anthony W D; Kühl, Michael

    2015-09-01

    Chlorophyll (Chl) f is the most recently discovered chlorophyll and has only been found in cyanobacteria from wet environments. Although its structure and biophysical properties are resolved, the importance of Chl f as an accessory pigment in photosynthesis remains unresolved. We found Chl f in a cyanobacterium enriched from a cavernous environment and report the first example of Chl f-supported oxygenic photosynthesis in cyanobacteria from such habitats. Pigment extraction, hyperspectral microscopy and transmission electron microscopy demonstrated the presence of Chl a and f in unicellular cyanobacteria found in enrichment cultures. Amplicon sequencing indicated that all oxygenic phototrophs were related to KC1, a Chl f-containing cyanobacterium previously isolated from an aquatic environment. Microsensor measurements on aggregates demonstrated oxygenic photosynthesis at 742 nm and less efficient photosynthesis under 768- and 777-nm light probably because of diminished overlap with the absorption spectrum of Chl f and other far-red absorbing pigments. Our findings suggest the importance of Chl f-containing cyanobacteria in terrestrial habitats.

  6. Novel surface associated polyphosphate bodies sequester uranium in the filamentous, marine cyanobacterium, Anabaena torulosa.

    PubMed

    Acharya, Celin; Apte, Shree Kumar

    2013-12-01

    A filamentous, heterocystous, nitrogen-fixing marine cyanobacterium, Anabaena torulosa, has been shown to harbour surface associated, acid soluble polyphosphate bodies. Uranium immobilization by such polyphosphate bodies, reported in cyanobacteria for the first time, demonstrates a novel uranium sequestration phenomenon.

  7. Cyanobacterium sp. host cell and vector for production of chemical compounds in Cyanobacterial cultures

    DOEpatents

    Piven, Irina; Friedrich, Alexandra; Duhring, Ulf; Uliczka, Frank; Baier, Kerstin; Inaba, Masami; Shi, Tuo; Wang, Kui; Enke, Heike; Kramer, Dan

    2016-04-19

    A cyanobacterial host cell, Cyanobacterium sp., that harbors at least one recombinant gene for the production of a chemical compounds is provided, as well as vectors derived from an endogenous plasmid isolated from the cell.

  8. Cyanobacterium sp. host cell and vector for production of chemical compounds in cyanobacterial cultures

    SciTech Connect

    Piven, Irina; Friedrich, Alexandra; Duhring, Ulf; Uliczka, Frank; Baier, Kerstin; Inaba, Masami; Shi, Tuo; Wang, Kui; Enke, Heike; Kramer, Dan

    2014-09-30

    A cyanobacterial host cell, Cyanobacterium sp., that harbors at least one recombinant gene for the production of a chemical compounds is provided, as well as vectors derived from an endogenous plasmid isolated from the cell.

  9. Structure and composition of cyanophycin granules in the cyanobacterium Aphanocapsa 6308.

    PubMed

    Allen, M M; Weathers, P J

    1980-02-01

    Cyanophycin granules in the unicellular cyanobacterium Aphanocapsa 6308 were examined with the electron microscope in both thin section and by freeze-fracture techniques. Purified granules were examined with the electron microscope, by arginine determinations, by chromatography, and by elemental analysis. They are similar in ultrastructure and composition to those isolated from the nitrogen-fixing cyanobacterium Anabaena cylindrica, consisting of equal molar quantities of L-arginine and L-aspartic acid. PMID:6767696

  10. Photoinhibition and reactivation of photosynthesis in the cyanobacterium Anacystis nidulans

    SciTech Connect

    Samuelsson, G.; Loenneborg, A.; Rosenqvist, E.; Gustafsson, P.; Oequist, G.

    1985-12-01

    The susceptibility of photosynthesis to photoinhibition and its recovery were studied on cultures of the cyanobacterium Anacystis nidulans. Oxygen evolution and low temperature fluorescence kinetics were measured. Upon exposure to high light A. nidulans showed a rapid decrease in oxygen evolution followed by a quasi steady state rate of photosynthesis. This quasi steady state rate decreased with increasing photon flux density of the photoinhibitory light. Reactivation of photosynthesis in dim light after the photoinhibitory treatment was rapid: 85 to 95% recovery occurred within 2 hours. In the presence of the translation inhibitor, streptomycin (250 micrograms per milliliter), no reactivation occurred. We also found that the damage increased dramatically if the high light treatment was done with streptomycin added. A transcription inhibitor, rifampicin, did not inhibit the reactivation process. Based on these data we conclude that the photoinhibitory damage observed is the net result of a balance between the photoinhibitory process and the operation of the repairing mechanism(s).

  11. Induction of anaerobic, photoautotrophic growth in the cyanobacterium Oscillatoria limnetica.

    PubMed Central

    Oren, A; Padan, E

    1978-01-01

    Anaerobic photoautotrophic growth of the cyanobacterium Oscillatoria limnetica was demonstrated under nitrogen in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (5micron), a constant concentration of Na2S (2.5 mM), and constant pH (7.3). The photoanaerobic growth rate (2 days doubling time) was similar to that obtained under oxygenic photoautotrophic growth conditions. The potential of oxygenic photosynthesis is constitutive in the cells; that of anoxygenic photosynthesis is rapidly (2 h) induced in the presence of Na2S in the light in a process requiring protein synthesis. The facultative anaerobic phototrophic growth physiology exhibited by O. limnetica would seem to represent an intermediate physiological pattern between the obligate anaerobic one of photosynthetic bacteria and the oxygenic one of eucaryotic algae. PMID:415043

  12. A New Lyngbyatoxin from the Hawaiian Cyanobacterium Moorea producens

    PubMed Central

    Jiang, Weina; Zhou, Wei; Uchida, Hajime; Kikumori, Masayuki; Irie, Kazuhiro; Watanabe, Ryuichi; Suzuki, Toshiyuki; Sakamoto, Bryan; Kamio, Michiya; Nagai, Hiroshi

    2014-01-01

    Lyngbyatoxin A from the marine cyanobacterium Moorea producens (formerly Lyngbya majuscula) is known as the causative agent of “swimmer’s itch” with its highly inflammatory effect. A new toxic compound was isolated along with lyngbyatoxin A from an ethyl acetate extract of M. producens collected from Hawaii. Analyses of HR-ESI-MS and NMR spectroscopies revealed the isolated compound had the same planar structure with that of lyngbyatoxin A. The results of optical rotation and CD spectra indicated that the compound was a new lyngbyatoxin A derivative, 12-epi-lyngbyatoxin A (1). While 12-epi-lyngbyatoxin A showed comparable toxicities with lyngbyatoxin A in cytotoxicity and crustacean lethality tests, it showed more than 100 times lower affinity for protein kinase Cδ (PKCδ) using the PKCδ-C1B peptide when compared to lyngbyatoxin A. PMID:24824022

  13. Phosphate transport and arsenate resistance in the cyanobacterium Anabaena variabilis

    SciTech Connect

    Thiel, T.

    1988-03-01

    Cells of the cyanobacterium Anabaena variabilis starved for phosphate for 3 days took up phosphate at about 100 times the rate of unstarved cells.Kinetic data suggested that a new transport system had been induced by starvation for phosphate. The inducible phosphate transport system was quickly repressed by addition of P/sub i/. Phosphate-starved cells were more sensitive to the toxic effects of arsenate than were unstarved cells, but phosphate could alleviate some of the toxicity. Arsenate was a noncompetitive inhibitor of phosphate transport; however, the apparent K/sub i/ values were high, particularly for phosphate-replete cells. Preincubation of phosphate-starved cells with arsenate caused subsequent inhibition of phosphate transport, suggesting that intracellular arsenate inhibited phosphate transport. This effect was not seen in phosphate-replete cells.

  14. Outdoor biophotolytic system using the cyanobacterium anabaena cylindrica B629

    SciTech Connect

    Smith, G.D.; Lambert, G.R.

    1981-01-01

    The cyanobacterium Anabaena cylindrica B629 was suspended in small glass beads and incubated in a gas-tight glass vessel outdoors under a gas atmosphere comprising carbon monoxide (0.2%), acetylene (5%), oxygen (6.5%), and nitrogen. The solution phase initially contained sodium bicarbonate (10mM) at pH 7. Under these conditions the organism continuously produced hydrogen gas for over three weeks. The temperature of the culture was maintained below 30 /degree/C and the minimum night temperatures were recorded. The vessel was covered by a shadecloth, which reduced the natural illumination by approximately 70%. The system is an alternative to those requiring the strict absence of oxygen and little nitrogen, and requires virtually no attention during the incubation period. 18 refs.

  15. Interaction effects of mercury-pesticide combinations towards a cyanobacterium

    SciTech Connect

    Stratton, G.W.

    1985-05-01

    The present study supplies interaction data for combinations of mercuric ion (supplied as mercuric chloride), atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine), and permethrin (3-phenoxybenzyl-(1RS)-cis,trans-3-(2,2-dichloro-vinyl)-2,2-dimethyl cyclopropanecarboxylate) when tested towards growth of the cyanobacterium (blue-green alga) Anabaena inaequalis. Mercury is one of the most important heavy metal pollutants and has been widely used in toxicology research. Atrazine is the most heavily used pesticide in the United States and its residues are widely distributed in terrestrial and aquatic ecosystems. Permethrin is an important insecticide with expanding markets and is presently being evaluated for its environmental impact. A. inaequalis has been used extensively in this laboratory in previous interaction studies.

  16. Genetic manipulation of a cyanobacterium for heavy metal detoxivication

    SciTech Connect

    McCormick, P.; Cannon, G.; Heinhorst, S.

    1995-12-31

    Increasing heavy metal contamination of soil and water has produced a need for economical and effective methods to reduce toxic buildup of these materials. Biological systems use metallothionein proteins to sequester such metals as Cu, Cd, and Zn. Studies are underway to genetically engineer a cyanobacteria strain with increased ability for metallothionein production and increased sequestration capacity. Cyanobacteria require only sunlight and CO{sub 2}. Vector constructs are being developed in a naturally competent, unicellular cyanobacterium Anacystis nidulans R2. Closed copies of a yeast copper metallothionein gene have been inserted into a cyanobacterial shuttle vector as well as a vector designed for genomic integration. Transformation studies have produced recombinant cyanobacteria from both of these systems, and work is currently underway to assess the organism`s ability to withstand increasing Cu, Cd, and Zn concentrations.

  17. Lipopeptides from the Tropical Marine Cyanobacterium Symploca sp.

    PubMed Central

    2015-01-01

    A collection of the tropical marine cyanobacterium Symploca sp., collected near Kimbe Bay, Papua New Guinea, previously yielded several new metabolites including kimbeamides A–C, kimbelactone A, and tasihalide C. Investigations into a more polar cytotoxic fraction yielded three new lipopeptides, tasiamides C–E (1–3). The planar structures were deduced by 2D NMR spectroscopy and tandem mass spectrometry, and their absolute configurations were determined by a combination of Marfey’s and chiral-phase GC-MS analysis. These new metabolites are similar to several previously isolated compounds, including tasiamide (4), grassystatins (5, 6), and symplocin A, all of which were isolated from similar filamentous marine cyanobacteria. PMID:24588245

  18. Comparative amperometric study of uptake hydrogenase and hydrogen photoproduction activities between heterocystous cyanobacterium Anabaena cylindrica B629 and nonheterocystous cyanobacterium Oscillatoria sp. strain Miami BG7

    SciTech Connect

    Kumazawa, S.; Mitsui, A.

    1985-08-01

    Heterocystous filamentous cyanobacterium Anabaena cylindrica B629 and nonheterocystous filamentous cyanobacterium Oscillatoria sp. strain Miami BG7 were cultured in media with N/sub 2/ as the sole nitrogen source; and activities of oxygen-dependent hydrogen uptake, photohydrogen production photooxygen evolution, and respiration were compared amperometrically under the same or similar experimental conditions for both strains. Distinct differences in these activities were observed in both strains. The rates of hydrogen photoproduction and hydrogen accumulation were significantly higher in Oscillatoria sp. strain BG7 than in A. cylindrica B629 at every light intensity tested. The major reason for the difference was attributable to the fact that the heterocystous cyanobacterium had a high rate of oxygen-dependent hydrogen consumption activity and the nonheterocystous cyanobacterium did not. The activity of oxygen photoevolution and respiration also contributed to the difference. Oscillatoria sp. strain BG7 had lower O/sub 2/ evolution and higher respiration than did A. cylindrica B629. Thus, the effect of O/sub 2/ on hydrogen photoproduction was minimized in Oscillatoria sp. strain BG7. 32 references, 5 figures.

  19. Comparative Amperometric Study of Uptake Hydrogenase and Hydrogen Photoproduction Activities between Heterocystous Cyanobacterium Anabaena cylindrica B629 and Nonheterocystous Cyanobacterium Oscillatoria sp. Strain Miami BG7

    PubMed Central

    Kumazawa, S.; Mitsui, A.

    1985-01-01

    Heterocystous filamentous cyanobacterium Anabaena cylindrica B629 and nonheterocystous filamentous cyanobacterium Oscillatoria sp. strain Miami BG7 were cultured in media with N2 as the sole nitrogen source; and activities of oxygen-dependent hydrogen uptake, photohydrogen production, photooxygen evolution, and respiration were compared amperometrically under the same or similar experimental conditions for both strains. Distinct differences in these activities were observed in both strains. The rates of hydrogen photoproduction and hydrogen accumulation were significantly higher in Oscillatoria sp. strain BG7 than in A. cylindrica B629 at every light intensity tested. The major reason for the difference was attributable to the fact that the heterocystous cyanobacterium had a high rate of oxygen-dependent hydrogen consumption activity and the nonheterocystous cyanobacterium did not. The activity of oxygen photoevolution and respiration also contributed to the difference. Oscillatoria sp. strain BG7 had lower O2 evolution and higher respiration than did A. cylindrica B629. Thus, the effect of O2 on hydrogen photoproduction was minimized in Oscillatoria sp. strain BG7. PMID:16346850

  20. The search for synonyms among streptomycetes by using SDS-PAGE of whole-cell proteins. Emendation of the species Streptomyces aurantiacus, Streptomyces cacaoi subsp. cacaoi, Streptomyces caeruleus and Streptomyces violaceus.

    PubMed

    Lanoot, B; Vancanneyt, M; Cleenwerck, I; Wang, L; Li, W; Liu, Z; Swings, J

    2002-05-01

    A collection of 93 Streptomyces reference strains were investigated using SDS-PAGE of whole-cell proteins. Computer-assisted numerical analysis revealed 24 clusters encompassing strains with very similar protein profiles. Five of them grouped several type strains with visually identical patterns. DNA-DNA hybridizations revealed homology values higher than 70% among these type strains. According to the current species concept, it is proposed that Streptomyces albosporeus subsp. albosporeus LMG 19403T is considered as a subjective synonym of Streptomyces aurantiacus LMG 19358T, that Streptomyces aminophilus LMG 19319T is considered as a subjective synonym of Streptomyces cacaoi subsp. cacaoi LMG 19320T, that Streptomyces niveus LMG 19395T and Streptomyces spheroides LMG 19392T are considered as subjective synonyms of Streptomyces caeruleus LMG 19399T, and that Streptomyces violatus LMG 19397T is considered as a subjective synonym of Streptomyces violaceus LMG 19360T. PMID:12054245

  1. From hopanoids to cholesterol: Molecular clocks of pentameric ligand-gated ion channels.

    PubMed

    Barrantes, Francisco J; Fantini, Jacques

    2016-07-01

    Pentameric ligand-gated ion channels (pLGICs) and their lipid microenvironments appear to have acquired mutually adaptive traits along evolution: 1) the three-ring architecture of their transmembrane (TM) region; 2) the ability of the outermost TM ring to convey lipid signals to the middle ring, which passes them on to the central pore ring, and 3) consensus motifs for sterol recognition in all pLGICs. Hopanoids are triterpenoid fossil lipids that constitute invaluable biomarkers for tracing evolution at the molecular scale. The cyanobacterium Gloeobacter violaceus is the oldest known living organism in which the X-ray structure of its pLGIC, GLIC, reveals the presence of the above attributes and, as discussed in this review, the ability to bind hopanoids. ELIC, the pLGIC from the bacillus Erwinia chrysanthemi is the only other known case to date. Both prokaryotes lack cholesterol but their pLGICs exhibit the same sterol motifs as mammalian pLGIC. This remarkable conservation suggests that the association of sterols and hopanoid surrogate molecules arose from the early need in prokaryotes to stabilize pLGIC TM regions by means of relatively rigid lipid molecules. The conservation of these phenotypic traits along such a long phylogenetic span leads us to suggest the possible co-evolution of these sterols with pLGICs. PMID:27084463

  2. Fractionation and identification of metalloproteins from a marine cyanobacterium.

    PubMed

    Barnett, James P; Scanlan, David J; Blindauer, Claudia A

    2012-04-01

    Trace metals are essential for the growth of marine cyanobacteria, being required for key cellular processes such as photosynthesis and respiration. Despite this, the metalloproteomes of marine cyanobacteria are at present only poorly defined. In this study, we have probed the major cobalt, iron, manganese, and nickel-binding proteins in the marine cyanobacterium Synechococcus sp. WH8102 by using two different fractionation approaches combined with peptide mass fingerprinting. For the identification of intact metalloproteins, multidimensional native chromatography was used to fractionate the proteome, followed by inorganic mass spectrometry to identify metal-enriched fractions. This approach led to the detection of nickel superoxide dismutase together with its predicted cofactor. We also explored the utility of immobilized metal affinity chromatography (IMAC) to isolate subpopulations of proteins that display affinity for a particular metal ion. We conclude that low-resolution 2D liquid chromatography is a viable fractionation technique to correlate relatively low-abundance metal ions with their few cellular destinations (e.g. Ni), but challenges remain for more abundant metals with multiple destinations such as iron. IMAC has been shown as a useful pre-fractionation technique to screen for proteins with metal-binding capacity, and may become a particularly valuable tool for the identification of metal-trafficking proteins.

  3. Two New Lyngbyatoxin Derivatives from the Cyanobacterium, Moorea producens

    PubMed Central

    Jiang, Weina; Tan, Satoshi; Hanaki, Yusuke; Irie, Kazuhiro; Uchida, Hajime; Watanabe, Ryuichi; Suzuki, Toshiyuki; Sakamoto, Bryan; Kamio, Michiya; Nagai, Hiroshi

    2014-01-01

    The toxin-producing cyanobacterium, Moorea producens, is a known causative organism of food poisoning and seaweed dermatitis (also known as “swimmer’s itch”). Two new toxic compounds were isolated and structurally elucidated from an ethyl acetate extract of M. producens collected from Hawaii. Analyses of HR-ESI-MS and NMR spectroscopies, as well as optical rotations and CD spectra indicated two new lyngbyatoxin derivatives, 2-oxo-3(R)-hydroxy-lyngbyatoxin A (1) and 2-oxo-3(R)-hydroxy-13-N-desmethyl-lyngbyatoxin A (2). The cytotoxicity and lethal activities of 1 and 2 were approximately 10- to 150-times less potent than lyngbyatoxin A. Additionally, the binding activities of 1 and 2 possessed 10,000-times lower affinity for the protein kinase Cδ (PKCδ)-C1B peptide when compared to lyngbyatoxin A. These findings suggest that these new lyngbyatoxin derivatives may mediate their acute toxicities through a non-PKC activation pathway. PMID:25470181

  4. Mutations affecting chromatic adaptation in the cyanobacterium Fremyella diplosiphon.

    PubMed Central

    Cobley, J G; Miranda, R D

    1983-01-01

    The chromatically adapting cyanobacterium, Fremyella diplosiphon, when grown in cool white fluorescent light, contains phycoerythrin as its predominant phycobiliprotein. When grown on agar plates with cool white illumination, mutant colonies deficient or devoid of phycoerythrin can be visibly distinguished from the wild type. A total of 25 anomalously pigmented strains were isolated and examined for their ability to chromatically adapt. Based on absorption spectra of cell extracts and on fluorescence emission spectra of intact filaments, we assigned each mutant to one of three classes. In green mutants (16 strains), the photoinduction of phycoerythrin synthesis by green light was lost or impaired, whereas the photorepression of phycocyanin synthesis by green light still functioned as in the wild type. In blue mutants (eight strains), both the ability to photoinduce phycoerythrin synthesis and the ability to photorepress phycocyanin synthesis were lost or impaired. Filaments of blue mutants exhibited a high fluorescence emission at 660 nm. A black mutant (one strain) exhibited partial induction of phycoerythrin and partial repression of phycocyanin in both red and cool white light. From the data, we suggest that in information transduction for chromatic adaptation, early events are common to both phycoerythrin and phycocyanin regulation and that blue mutants possess lesions in these early events. The lesions in green mutants occur in a subsequent branch of the information transduction pathway which is specific for phycoerythrin photoinduction. PMID:6402499

  5. Sucrose secreted by the engineered cyanobacterium and its fermentability

    NASA Astrophysics Data System (ADS)

    Duan, Yangkai; Luo, Quan; Liang, Feiyan; Lu, Xuefeng

    2016-10-01

    The unicellular cyanobacterium, Synechococcus elongatus PCC 7942 (Syn7942), synthesizes sucrose as the only compatible solute under salt stress. A series of engineered Syn7942 strains for sucrose production were constructed. The overexpression of the native sps (encoding a natively fused protein of sucrose phosphate synthase SPS and sucrose phosphate phosphatase SPP) in Syn7942 wild type caused a 93% improvement of sucrose productivity. The strain FL130 co-overexpressing sps and cscB (encoding a sucrose transporter) exhibited a 74% higher extracellular sucrose production than that overexpressing cscB only. Both results showed the significant improvement of sucrose productivity by the double functional protein SPS-SPP. Afterwards, FL130 was cultivated under a modified condition, and the cell-free culture medium containing 1.5 g L-1 sucrose was pre-treated with an acid hydrolysis technique. Cultivated with the neutralized hydrolysates as the starting media, two widely used microorganisms, Escherichia coli and Saccharomyces cerevisiae, showed a comparable growth with that in the control media supplemented with glucose. These results clearly demonstrated that the cell-free culture of sucrose-secreting cyanobacteria can be applied as starting media in microbial cultivation.

  6. Cryopreservation of the edible alkalophilic cyanobacterium Arthrospira platensis.

    PubMed

    Shiraishi, Hideaki

    2016-10-01

    Efficient cryopreservation conditions for the edible alkalophilic cyanobacterium Arthrospira (Spirulina) platensis were investigated using a model strain A. platensis NIES-39. As a result, it was found that more than 60% of cells were viable upon thawing, when they had been frozen at a cooling rate of approximately -1 °C min(-1) in the presence of 10% (v/v) dimethyl sulfoxide. Further examination with other Arthrospira strains showed that many of them had strain-dependent optimal conditions for cryopreservation. For example, the best freezing conditions for A. platensis SAG 21.99 were snap-freezing in liquid nitrogen in the presence of 5% (v/v) dimethyl sulfoxide, while they were slow cooling at approximately -1 °C min(-1) in the presence of 10% (v/v) methanol for A. platensis NIES-46, NIES-2308 and UTEX 1926. The variety of successful cryopreservation conditions presented in this study is useful when attempting to cryopreserve various Arthrospira strains. PMID:27240586

  7. Export of Extracellular Polysaccharides Modulates Adherence of the Cyanobacterium Synechocystis

    SciTech Connect

    Fisher, ML; Allen, R; Luo, YQ; Curtiss, R

    2013-09-10

    The field of cyanobacterial biofuel production is advancing rapidly, yet we know little of the basic biology of these organisms outside of their photosynthetic pathways. We aimed to gain a greater understanding of how the cyanobacterium Synechocystis PCC 6803 (Synechocystis, hereafter) modulates its cell surface. Such understanding will allow for the creation of mutants that autoflocculate in a regulated way, thus avoiding energy intensive centrifugation in the creation of biofuels. We constructed mutant strains lacking genes predicted to function in carbohydrate transport or synthesis. Strains with gene deletions of slr0977 (predicted to encode a permease component of an ABC transporter), slr0982 (predicted to encode an ATP binding component of an ABC transporter) and slr1610 (predicted to encode a methyltransferase) demonstrated flocculent phenotypes and increased adherence to glass. Upon bioinformatic inspection, the gene products of slr0977, slr0982, and slr1610 appear to function in O-antigen (OAg) transport and synthesis. However, the analysis provided here demonstrated no differences between OAg purified from wild-type and mutants. However, exopolysaccharides (EPS) purified from mutants were altered in composition when compared to wild-type. Our data suggest that there are multiple means to modulate the cell surface of Synechocystis by disrupting different combinations of ABC transporters and/or glycosyl transferases. Further understanding of these mechanisms may allow for the development of industrially and ecologically useful strains of cyanobacteria. Additionally, these data imply that many cyanobacterial gene products may possess as-yet undiscovered functions, and are meritorious of further study.

  8. Radiation characteristics and optical properties of filamentous cyanobacterium Anabaena cylindrica.

    PubMed

    Heng, Ri-Liang; Lee, Euntaek; Pilon, Laurent

    2014-04-01

    This study presents experimental measurements of the absorption and scattering cross sections and the spectral complex index of refraction of filamentous cyanobacteria. Filamentous heterocystous cyanobacterium Anabaena cylindrica was chosen as a model organism. Its filaments consisted of long chains of polydisperse cells. Their average mass scattering and absorption cross sections were measured from 400 to 750 nm at four different times during their batch growth in medium BG-11(-N) under 3000 lux of white fluorescent light. The effective real (or refraction index) and imaginary (or absorption index) parts of the complex index of refraction were retrieved using an inverse method based on a genetic algorithm. The microorganisms were modeled as infinitely long and randomly oriented volume-equivalent cylinders. The absorption index featured peaks corresponding to chlorophyll a (Chl a) at 436 and 676 nm and phycocyanin (PCCN) at 630 nm and a shoulder around 480 nm, corresponding to photoprotective carotenoids. The absorption peaks of Chl a and PCCN concentrations increased and the shoulder due to carotenoids decreased in response to photolimitation caused by biomass growth. Subsequent nitrogen limitation caused the PCCN absorption peak to decrease significantly due to degradation of PCCN as an endogenous source of nitrogen for nitrogenase maintenance and synthesis, as confirmed by increasing heterocyst differentiation. The results can be used for predicting and optimizing light transfer in photobioreactors for wastewater treatment and ammonia or biofuel production. PMID:24695147

  9. Oxidative inactivation of glutamine synthetase from the cyanobacterium Anabaena variabilis.

    PubMed Central

    Martin, G; Haehnel, W; Böger, P

    1997-01-01

    In crude extracts of the cyanobacterium Anabaena variabilis, glutamine synthetase (GS) could be effectively inactivated by the addition of NADH. GS inactivation was completed within 30 min. Both the inactivated GS and the active enzyme were isolated. No difference between the two enzyme forms was seen in sodium dodecyl sulfate-gels, and only minor differences were detectable by UV spectra, which excludes modification by a nucleotide. Mass spectrometry revealed that the molecular masses of active and inactive GS are equal. While the Km values of the substrates were unchanged, the Vmax values of the inactive GS were lower, reflecting the inactivation factor in the crude extract. This result indicates that the active site was affected. From the crude extract, a fraction mediating GS inactivation could be enriched by ammonium sulfate precipitation and gel filtration. GS inactivation by this fraction required the presence of NAD(P)H, Fe3+, and oxygen. In the absence of the GS-inactivating fraction, GS could be inactivated by Fe2+ and H2O2. The GS-inactivating fraction produced Fe2+ and H2O2, using NADPH, Fe3+, and oxygen. Accordingly, the inactivating fraction was inhibited by catalase and EDTA. This GS-inactivating system of Anabaena is similar to that described for oxidative GS inactivation in Escherichia coli. We conclude that GS inactivation by NAD(P)H is caused by irreversible oxidative damage and is not due to a regulatory mechanism of nitrogen assimilation. PMID:9006027

  10. Construction of a cyanobacterium synthesizing cyclopropane fatty acids.

    PubMed

    Machida, Shuntaro; Shiraiwa, Yoshihiro; Suzuki, Iwane

    2016-09-01

    Microalgae have received much attention as a next-generation source of biomass energy. However, most of the fatty acids (FAs) from microalgae are multiply unsaturated; thus, the biofuels derived from them are fluid, but vulnerable to oxidation. In this study, we attempted to synthesize cyclopropane FAs in the cyanobacterium Synechocystis sp. PCC 6803 by expressing the cfa gene for cyclopropane FA synthase from Escherichia coli with the aim of producing FAs that are fluid and stable in response to oxidization. We successfully synthesized cyclopropane FAs in Synechocystis with a yield of ~30% of total FAs. Growth of the transformants was altered, particularly at low temperatures, but photosynthesis and respiration were not significantly affected. C16:1(∆9) synthesis in the desA(-)/desD(-) strain by expression of the desC2 gene for sn-2 specific ∆9 desaturase positively affected growth at low temperatures via promotion of various cellular processes, with the exceptions of photosynthesis and respiration. Estimation of the apparent activities of desaturases suggested that some acyl-lipid desaturases might recognize the lipid side chain. PMID:27263419

  11. High light intensity augments mercury toxicity in cyanobacterium Nostoc muscorum.

    PubMed

    Singh, Ranjana; Dubey, Gunjan; Singh, Vijay Pratap; Srivastava, Prabhat Kumar; Kumar, Sushil; Prasad, Sheo Mohan

    2012-11-01

    The present study is aimed at investigating the role of growth irradiance in determining the extent of mercury (Hg) toxicity on various physiological parameters viz. growth, pigment contents, photosynthesis, respiration, (14)CO(2) fixation, photosynthetic electron transport, photorespiration and enzyme activity of cyanobacterium Nostoc muscorum. A general decline was observed in all these parameters with increasing concentration of Hg except for carotenoids content and respiratory activity which exhibited significant enhancement. This effect was more pronounced in high light (130 μmol photon m(-2) s(-1)) exposed cells as compared to normal (70 μmol photon m(-2) s(-1)) and low (10 μmol photon m(-2) s(-1)) light exposed cells. Among the photosynthetic electron transport activities, whole chain was found to be more sensitive than photosystem II (PSII) and photosystem I (PSI). (14)CO(2) fixation was more affected as compared to O(2) evolution when exposed to Hg and different light intensities. Photorespiratory activity, which is an index of protecting organisms from light-induced damage, also showed a similar declining trend. Enzyme assay revealed that among the carboxylating enzymes, activity of RUBISCO was more severely inhibited than PEPCase. Thus, these results suggest that Hg itself was toxic at all tested concentrations and high light intensity augmented its toxicity in N. muscorum inhibiting the growth, pigment contents and photosynthetic activity of the organism.

  12. Export of Extracellular Polysaccharides Modulates Adherence of the Cyanobacterium Synechocystis

    PubMed Central

    Fisher, Michael L.; Allen, Rebecca; Luo, Yingqin; Curtiss, Roy

    2013-01-01

    The field of cyanobacterial biofuel production is advancing rapidly, yet we know little of the basic biology of these organisms outside of their photosynthetic pathways. We aimed to gain a greater understanding of how the cyanobacterium Synechocystis PCC 6803 (Synechocystis, hereafter) modulates its cell surface. Such understanding will allow for the creation of mutants that autoflocculate in a regulated way, thus avoiding energy intensive centrifugation in the creation of biofuels. We constructed mutant strains lacking genes predicted to function in carbohydrate transport or synthesis. Strains with gene deletions of slr0977 (predicted to encode a permease component of an ABC transporter), slr0982 (predicted to encode an ATP binding component of an ABC transporter) and slr1610 (predicted to encode a methyltransferase) demonstrated flocculent phenotypes and increased adherence to glass. Upon bioinformatic inspection, the gene products of slr0977, slr0982, and slr1610 appear to function in O-antigen (OAg) transport and synthesis. However, the analysis provided here demonstrated no differences between OAg purified from wild-type and mutants. However, exopolysaccharides (EPS) purified from mutants were altered in composition when compared to wild-type. Our data suggest that there are multiple means to modulate the cell surface of Synechocystis by disrupting different combinations of ABC transporters and/or glycosyl transferases. Further understanding of these mechanisms may allow for the development of industrially and ecologically useful strains of cyanobacteria. Additionally, these data imply that many cyanobacterial gene products may possess as-yet undiscovered functions, and are meritorious of further study. PMID:24040267

  13. Gene Transfer to the Desiccation-Tolerant Cyanobacterium Chroococcidiopsis

    PubMed Central

    Billi, Daniela; Friedmann, E. Imre; Helm, Richard F.; Potts, Malcolm

    2001-01-01

    The coccoid cyanobacterium Chroococcidiopsis dominates microbial communities in the most extreme arid hot and cold deserts. These communities withstand constraints that result from multiple cycles of drying and wetting and/or prolonged desiccation, through mechanisms which remain poorly understood. Here we describe the first system for genetic manipulation of Chroococcidiopsis. Plasmids pDUCA7 and pRL489, based on the pDU1 replicon of Nostoc sp. strain PCC 7524, were transferred to different isolates of Chroococcidiopsis via conjugation and electroporation. This report provides the first evidence that pDU1 replicons can be maintained in cyanobacteria other than Nostoc and Anabaena. Following conjugation, both plasmids replicated in Chroococcidiopsis sp. strains 029, 057, and 123 but not in strains 171 and 584. Both plasmids were electroporated into strains 029 and 123 but not into strains 057, 171, and 584. Expression of PpsbA-luxAB on pRL489 was visualized through in vivo luminescence. Efficiencies of conjugative transfer for pDUCA7 and pRL489 into Chroococcidiopsis sp. strain 029 were approximately 10−2 and 10−4 transconjugants per recipient cell, respectively. Conjugative transfer occurred with a lower efficiency into strains 057 and 123. Electrotransformation efficiencies of about 10−4 electrotransformants per recipient cell were achieved with strains 029 and 123, using either pDUCA7 or pRL489. Extracellular deoxyribonucleases were associated with each of the five strains. Phylogenetic analysis, based upon the V6 to V8 variable regions of 16S rRNA, suggests that desert strains 057, 123, 171, and 029 are distinct from the type species strain Chroococcidiopsis thermalis PCC 7203. The high efficiency of conjugative transfer of Chroococcidiopsis sp. strain 029, from the Negev Desert, Israel, makes this a suitable experimental strain for genetic studies on desiccation tolerance. PMID:11244070

  14. Antagonistic interactions between filamentous heterotrophs and the cyanobacterium Nostoc muscorum

    PubMed Central

    2011-01-01

    Background Little is known about interactions between filamentous heterotrophs and filamentous cyanobacteria. Here, interactions between the filamentous heterotrophic bacteria Fibrella aestuarina (strain BUZ 2) and Fibrisoma limi (BUZ 3) with an axenic strain of the autotrophic filamentous cyanobacterium Nostoc muscorum (SAG 25.82) were studied in mixed cultures under nutrient rich (carbon source present in medium) and poor (carbon source absent in medium) conditions. Findings F. aestuarina BUZ 2 significantly reduced the cyanobacterial population whereas F. limi BUZ 3 did not. Physical contact between heterotrophs and autotroph was observed and the cyanobacterial cells showed some level of damage and lysis. Therefore, either contact lysis or entrapment with production of extracellular compounds in close vicinity of host cells could be considered as potential modes of action. The supernatants from pure heterotrophic cultures did not have an effect on Nostoc cultures. However, supernatant from mixed cultures of BUZ 2 and Nostoc had a negative effect on cyanobacterial growth, indicating that the lytic compounds were only produced in the presence of Nostoc. The growth and survival of tested heterotrophs was enhanced by the presence of Nostoc or its metabolites, suggesting that the heterotrophs could utilize the autotrophs and its products as a nutrient source. However, the autotroph could withstand and out-compete the heterotrophs under nutrient poor conditions. Conclusions Our results suggest that the nutrients in cultivation media, which boost or reduce the number of heterotrophs, were the important factor influencing the outcome of the interplay between filamentous heterotrophs and autotrophs. For better understanding of these interactions, additional research is needed. In particular, it is necessary to elucidate the mode of action for lysis by heterotrophs, and the possible defense mechanisms of the autotrophs. PMID:21914201

  15. Combining immunolabeling and catalyzed reporter deposition to detect intracellular saxitoxin in a cyanobacterium.

    PubMed

    Piccini, Claudia; Fabre, Amelia; Lacerot, Gissell; Bonilla, Sylvia

    2015-10-01

    We combined the use of polyclonal antibodies against saxitoxin with catalyzed reporter deposition to detect production of saxitoxin by the cyanobacterium Cylindrospermopsis raciborskii. The procedure is simple, allows detection of intracellular saxitoxin in cyanobacteria filaments by confocal laser microscopy and is a promising tool to study toxin production and metabolism.

  16. Genome Sequence of the Thermophilic Cyanobacterium Thermosynechococcus sp. Strain NK55a.

    SciTech Connect

    Stolyar, Sergey; Liu, Zhenfeng; Thiel, Vera; Tomsho, Lynn P.; Pinel, Nicolas; Nelson, William C.; Lindemann, Stephen R.; Romine, Margaret F.; Haruta, Shin; Schuster, Stephan C.; Bryant, Donald A.; Fredrickson, Jim K.

    2014-01-02

    The genome of the unicellular cyanobacterium, Thermosynechococcus sp. strain NK55a, isolated from Nakabusa hot spring, comprises a single, circular, 2.5-Mb chromosome. The genome is predicted to encode 2358 protein coding genes, including genes for all typical cyanobacterial photosynthetic and metabolic functions. No genes encoding hydrogenases or nitrogenase were identified.

  17. Pitipeptolides C–F, Antimycobacterial Cyclodepsipeptides from the Marine Cyanobacterium Lyngbya majuscula from Guam

    PubMed Central

    Montaser, Rana; Paul, Valerie J.; Luesch, Hendrik

    2011-01-01

    Pitipeptolides A (1) and B (2) are cyclic depsipeptides isolated from the marine cyanobacterium Lyngbya majuscula from Piti Bomb Holes, Guam. Additional analogues have now been isolated by revisiting larger collections of the same cyanobacterium. The four newly identified analogues, pitipeptolides C–F (3–6), are the tetrahydro analogue (3), an analogue with a lower degree of methylation (4) as well as two homologues (5 and 6) of pitipeptolide A. The structures were elucidated using 2D NMR experiments, chiral HPLC analysis and comparison with pitipeptolide A. The newly identified analogues showed weaker cytotoxic activities compared to the two major parent compounds, pitipeptolides A (1) and B (2), against HT-29 colon adenocarcinoma and MCF7 breast cancer cells. On the other hand, pitipeptolide F (6) was the most potent pitipeptolide in a disc diffusion assay against Mycobacterium tuberculosis. The latter finding suggests that the structure of pitipeptolides could be optimized for selective antibacterial activity. PMID:21843895

  18. Pitipeptolides C-F, antimycobacterial cyclodepsipeptides from the marine cyanobacterium Lyngbya majuscula from Guam.

    PubMed

    Montaser, Rana; Paul, Valerie J; Luesch, Hendrik

    2011-11-01

    Pitipeptolides A (1) and B (2) are cyclic depsipeptides isolated from the marine cyanobacterium Lyngbya majuscula from Piti Bomb Holes, Guam. Additional analogues have now been isolated by revisiting larger collections of the same cyanobacterium. The four identified analogues, pitipeptolides C-F (3-6), are the tetrahydro analogue (3), an analogue with a lower degree of methylation (4) as well as two homologues (5 and 6) of pitipeptolide A. Their structures were elucidated using 2D NMR experiments, chiral HPLC analysis and comparison with pitipeptolide A. The identified analogues showed weaker cytotoxic activities compared to the two major parent compounds, pitipeptolides A (1) and B (2), against HT-29 colon adenocarcinoma and MCF7 breast cancer cells. On the other hand, pitipeptolide F (6) was the most potent pitipeptolide in a disc diffusion assay against Mycobacterium tuberculosis. The latter finding suggests that the structure of pitipeptolides could be optimized for selective antibacterial activity.

  19. Apramides A-G, novel lipopeptides from the marine cyanobacterium Lyngbya majuscula.

    PubMed

    Luesch, H; Yoshida, W Y; Moore, R E; Paul, V J

    2000-08-01

    Six new metabolites have been isolated from a lyngbyastatin 2-producing strain of the marine cyanobacterium Lyngbya majuscula collected at Apra Harbor, Guam, and their structures elucidated. These linear lipopeptides have been assigned the trivial names apramides A-F (1-6). From a more recent collection of this cyanobacterium, a structurally related compound, apramide G (7), has been found instead of apramides A-F (1-6). Structure elucidation of the lipopeptides 1-7 is based on spectroscopic techniques and chiral chromatography of hydrolysis products. The apramides appear as NMR-spectroscopically distinguishable conformers in solution, and this has been ascribed to the presence of a thiazole-containing modified amino acid unit.

  20. Bloom of the cyanobacterium Moorea bouillonii on the gorgonian coral Annella reticulata in Japan

    PubMed Central

    Yamashiro, Hideyuki; Isomura, Naoko; Sakai, Kazuhiko

    2014-01-01

    Coral populations are in decline due to environmental changes and biological attacks by predators and infectious diseases. Here, we report a localized bloom of the benthic filamentous cyanobacterium Moorea bouillonii (formerly Lyngbya bouillonii) observed exclusively on the gorgonian (sea fan) coral Annella reticulata at around 20 m depth in Japan. The degree of infection has reached 26% among different sizes of Annella colonies. Thick and continuous growth of Moorea may be sustained partly by symbiotic alpheid shrimp, which affix Moorea filaments to gorgonian corals for use as food and shelter. Most filaments get entangled on the coral colony, some penetrate into the stem of the coral with a swollen end like a root hair, which appears to function as an anchor in Annella. In addition to the cyanobacterium–shrimp interaction, the new trait of anchoring by the cyanobacterium into gorgonian coral may contribute to persistence of this bloom. PMID:25112498

  1. Genetic manipulation of a metabolic enzyme and a transcriptional regulator increasing succinate excretion from unicellular cyanobacterium

    PubMed Central

    Osanai, Takashi; Shirai, Tomokazu; Iijima, Hiroko; Nakaya, Yuka; Okamoto, Mami; Kondo, Akihiko; Hirai, Masami Y.

    2015-01-01

    Succinate is a building block compound that the U.S. Department of Energy (DOE) has declared as important in biorefineries, and it is widely used as a commodity chemical. Here, we identified the two genes increasing succinate production of the unicellular cyanobacterium Synechocystis sp. PCC 6803. Succinate was excreted under dark, anaerobic conditions, and its production level increased by knocking out ackA, which encodes an acetate kinase, and by overexpressing sigE, which encodes an RNA polymerase sigma factor. Glycogen catabolism and organic acid biosynthesis were enhanced in the mutant lacking ackA and overexpressing sigE, leading to an increase in succinate production reaching five times of the wild-type levels. Our genetic and metabolomic analyses thus demonstrated the effect of genetic manipulation of a metabolic enzyme and a transcriptional regulator on succinate excretion from this cyanobacterium with the data based on metabolomic technique. PMID:26500619

  2. Intraspecific variation in growth, morphology and toxin quotas for the cyanobacterium, Cylindrospermopsis raciborskii.

    PubMed

    Willis, Anusuya; Chuang, Ann W; Woodhouse, Jason N; Neilan, Brett A; Burford, Michele A

    2016-09-01

    Cylindrospermopsis raciborskii is a bloom forming cyanobacterium with complex population dynamics and toxicity. In January of 2013 a single sample was collected from surface waters in Lake Wivenhoe, Australia, and twenty-four individual trichomes were isolated. Each isolate exhibited differences in growth rate, toxin cell quota and morphology, in the absence of phylogenetic heterogeneity. This study demonstrates substantial intraspecific isolate variation within a small sample and this has implications for understanding the population dynamics of this species. PMID:27390039

  3. Aeruginazole A, a novel thiazole-containing cyclopeptide from the cyanobacterium Microcystis sp.

    PubMed

    Raveh, Avi; Carmeli, Shmuel

    2010-08-01

    A novel thiazole-containing cyclic peptide, aeruginazole A (1), was isolated from the cyanobacterium Microcystis sp. strain (IL-323), which was collected from a water reservoir near Kfar-Yehoshua, Valley of Armageddon, Israel. The planar structure of aeruginazole A was established using homonuclear and inverse-heteronuclear 2D NMR techniques, as well as high-resolution mass spectrometry. The absolute configuration of the asymmetric centers was determined using Marfey's method. Aeruginazole A potently inhibited Bacillus subtilis.

  4. Cyanobacterium Microcystis aeruginosa response to pentachlorophenol and comparison with that of the microalga Chlorella vulgaris.

    PubMed

    de Morais, Paulo; Stoichev, Teodor; Basto, M Clara P; Ramos, V; Vasconcelos, V M; Vasconcelos, M Teresa S D

    2014-04-01

    Pentachlorophenol (PCP) effects on a strain of the cyanobacterium Microcystis aeruginosa were investigated at laboratory scale. This is the first systematic ecotoxicity study of the effects of PCP on an aquatic cyanobacterium. The microalga Chlorella vulgaris was studied in the same conditions as the cyanobacterium, in order to compare the PCP toxicity and its removal by the species. The cells were exposed to environmental levels of PCP during 10 days, in Fraquil culture medium, at nominal concentrations from 0.01 to 1000 μg L(-1), to the cyanobacterium, and 0.01 to 5000 μg L(-1), to the microalga. Growth was assessed by area under growth curve (AUC, optical density vs time) and chlorophyll a content (chla). The toxicity profiles of the two species were very different. The calculated effective concentrations EC20 and EC50 were much lower to M. aeruginosa, and its growth inhibition expressed by chla was concentration-dependent while by AUC was not concentration-dependent. The cells might continue to divide even with lower levels of chla. The number of C. vulgaris cells decreased with the PCP concentration without major impact on the chla. The effect of PCP on M. aeruginosa is hormetic: every concentration studied was toxic except 1 μg L(-1), which promoted its growth. The legal limit of PCP set by the European Union for surface waters (1 μg L(-1)) should be reconsidered since a toxic cyanobacteria bloom might occur. The study of the removal of PCP from the culture medium by the two species is an additional novelty of this work. M. aeruginosa could remove part of the PCP from the medium, at concentrations where toxic effects were observed, while C. vulgaris stabilized it. PMID:24462928

  5. Interaction of fructose with the glucose permease of the cyanobacterium Synechocystis sp. strain PCC 6803

    SciTech Connect

    Flores, E.; Schmetterer, G.

    1986-05-01

    Fructose was bactericidal for the cyanobacterium Synechocystis sp. strain PCC 6803. Each of ten independently isolated fructose-resistant mutants had an alteration of the glucose transport system, measured as uptake of glucose or of 3-0-methyl-D-glucose. In the presence of the analog, the wild-type Synechocystis strain was protected against fructose. Two mutants altered in photoautotrophy were also isolated.

  6. Adaptation strategies of the sheathed cyanobacterium Lyngbya majuscula to ultraviolet-B.

    PubMed

    Mandal, Sikha; Rath, Jnanendra; Adhikary, Siba Prasad

    2011-02-01

    Lyngbya majuscula is a dominant organism in the east coast of India forming characteristic mat in dried saline soils simultaneously exposed to solar radiation of the tropics. Studies on the growth response, changes in the spectral properties of the methanolic extract and protein profile of this estuarine sheathed cyanobacterium to UV-B revealed existence of effective adaptation mechanism to withstand prolonged UV-B radiation. Carotenoids along with MAAs of the organism was increased with increase in UV irradiation. Increase in thickness of the mucilaginous sheath layer as well as cellular carbohydrate content was observed upon exposure to prolonged UV-B dose. Induction of 21 and 33 kDa low molecular weight proteins, and a 99 kDa protein together with formation of distinct multilayered sheath embedding trichomes with granulated cells were the adaptive features of the organism to cope with UV-B stress. The organism was considerably revived after incubating the irradiated cells in mineral medium under florescent light and in the dark suggesting existence of photoreactivation and dark repair in this cyanobacterium. However more experiments are needed to establish the existence of photoreactivation and dark repair mechanism in the studied cyanobacterium.

  7. Role of manganese in protection against oxidative stress under iron starvation in cyanobacterium Anabaena 7120.

    PubMed

    Kaushik, Manish Singh; Srivastava, Meenakshi; Verma, Ekta; Mishra, Arun Kumar

    2015-06-01

    The cyanobacterium Anabaena sp. PCC 7120 was grown in presence and absence of iron to decipher the role of manganese in protection against the oxidative stress under iron starvation and growth, manganese uptake kinetics, antioxidative enzymes, lipid peroxidation, electrolyte leakage, thiol content, total peroxide, proline and NADH content was investigated. Manganese supported the growth of cyanobacterium Anabaena 7120 under iron deprived conditions where maximum uptake rate of manganese was observed with lower K(m) and higher V(max) values. Antioxidative enzymes were also found to be elevated in iron-starved conditions. Estimation of lipid peroxidation and electrolyte leakage depicted the role of manganese in stabilizing the integrity of the membrane which was considered as the prime target of oxygen free radicals in oxidative stress. The levels of total peroxide, thiol, proline and NADH content, which are the representative of oxidative stress response in Anabaena 7120, were also showed increasing trends in iron starvation. Hence, the results discerned, clearly suggested the role of manganese in protection against the oxidative stress in cyanobacterium Anabaena 7120 under iron starvation either due to its antioxidative properties or involvement as cofactor in a number of antioxidative enzymes.

  8. Ecological genomics of the newly discovered diazotrophic filamentous cyanobacterium ESFC-1

    NASA Astrophysics Data System (ADS)

    Everroad, C.; Bebout, B.; Bebout, L. E.; Detweiler, A. M.; Lee, J.; Mayali, X.; Singer, S. W.; Stuart, R.; Weber, P. K.; Woebken, D.; Pett-Ridge, J.

    2014-12-01

    Cyanobacteria-dominated microbial mats played a key role in the evolution of the early Earth and provide a model for exploring the relationships between ecology, evolution and biogeochemistry. A recently described nonheterocystous filamentous cyanobacterium, strain ESFC-1, has been shown to be a major diazotroph year round in the intertidal microbial mat system at Elkhorn Slough, CA, USA. Based on phylogenetic analyses of the 16s RNA gene, ESFC-1 appears to belong to a unique, genus-level divergence within the cyanobacteria. Consequently, the draft genome sequence of this strain has been determined. Here we report features of this genome, particularly as they relate to the ecological functions and capabilities of strain ESFC-1. One striking feature of this cyanobacterium is the apparent lack of a functional bi-directional hydrogenase typically expected to be found within a diazotroph; consortia- and culture-based experiments exploring the metabolic processes of ESFC-1 also indicate that this hydrogenase is absent. Co-culture studies with ESFC-1 and some of the dominant heterotrophic members within the microbial mat system, including the ubiquitous Flavobacterium Muricauda sp., which often is found associated with cyanobacteria in nature and in culture collections worldwide, have also been performed. We report on these species-species interactions, including materials exchange between the cyanobacterium and heterotrophic bacterium. The combination of genomics with culture- and consortia-based experimental research is a powerful tool for understanding microbial processes and interactions in complex ecosystems.

  9. Physiological and proteomic analysis of salinity tolerance of the halotolerant cyanobacterium Anabaena sp.

    PubMed

    Yadav, Ravindra Kumar; Thagela, Preeti; Tripathi, Keshawanand; Abraham, G

    2016-09-01

    The halotolerant cyanobacterium Anabaena sp was grown under NaCl concentration of 0, 170 and 515 mM and physiological and proteomic analysis was performed. At 515 mM NaCl the cyanobacterium showed reduced photosynthetic activities and significant increase in soluble sugar content, proline and SOD activity. On the other hand Anabaena sp grown at 170 mM NaCl showed optimal growth, photosynthetic activities and comparatively low soluble sugar content, proline accumulation and SOD activity. The intracellular Na(+) content of the cells increased both at 170 and 515 mM NaCl. In contrast, the K(+) content of the cyanobacterium Anabaena sp remained stable in response to growth at identical concentration of NaCl. While cells grown at 170 mM NaCl showed highest intracellular K(+)/Na(+) ratio, salinity level of 515 mM NaCl resulted in reduced ratio of K(+)/Na(+). Proteomic analysis revealed 50 salt-responsive proteins in the cyanobacterium Anabaena sp under salt treatment compared with control. Ten protein spots were subjected to MALDI-TOF-MS/MS analysis and the identified proteins are involved in photosynthesis, protein folding, cell organization and energy metabolism. Differential expression of proteins related to photosynthesis, energy metabolism was observed in Anabaena sp grown at 170 mM NaCl. At 170 mM NaCl increased expression of photosynthesis related proteins and effective osmotic adjustment through increased antioxidant enzymes and modulation of intracellular ions contributed to better salinity tolerance and optimal growth. On the contrary, increased intracellular Na(+) content coupled with down regulation of photosynthetic and energy related proteins resulted in reduced growth at 515 mM NaCl. Therefore reduced growth at 515 mM NaCl could be due to accumulation of Na(+) ions and requirement to maintain higher organic osmolytes and antioxidants which is energy intensive. The results thus show that the basis of salt tolerance is different when the

  10. A new chlorophyll d-containing cyanobacterium: evidence for niche adaptation in the genus Acaryochloris.

    PubMed

    Mohr, Remus; Voss, Björn; Schliep, Martin; Kurz, Thorsten; Maldener, Iris; Adams, David G; Larkum, Anthony D W; Chen, Min; Hess, Wolfgang R

    2010-11-01

    Chlorophyll d is a photosynthetic pigment that, based on chemical analyses, has only recently been recognized to be widespread in oceanic and lacustrine environments. However, the diversity of organisms harbouring this pigment is not known. Until now, the unicellular cyanobacterium Acaryochloris marina is the only characterized organism that uses chlorophyll d as a major photopigment. In this study we describe a new cyanobacterium possessing a high amount of chlorophyll d, which was isolated from waters around Heron Island, Great Barrier Reef (23° 26' 31.2″ S, 151° 54' 50.4″ E). The 16S ribosomal RNA is 2% divergent from the two previously described isolates of A. marina, which were isolated from waters around the Palau islands (Pacific Ocean) and the Salton Sea lake (California), suggesting that it belongs to a different clade within the genus Acaryochloris. An overview sequence analysis of its genome based on Illumina technology yielded 871 contigs with an accumulated length of 8 371 965 nt. Their analysis revealed typical features associated with Acaryochloris, such as an extended gene family for chlorophyll-binding proteins. However, compared with A. marina MBIC11017, distinct genetic, morphological and physiological differences were observed. Light saturation is reached at lower light intensities, Chl d/a ratios are less variable with light intensity and the phycobiliprotein phycocyanin is lacking, suggesting that cyanobacteria of the genus Acaryochloris occur in distinct ecotypes. These data characterize Acaryochloris as a niche-adapted cyanobacterium and show that more rigorous attempts are worthwhile to isolate, cultivate and analyse chlorophyll d-containing cyanobacteria for understanding the ecophysiology of these organisms. PMID:20505751

  11. Genome Erosion in a Nitrogen-Fixing Vertically Transmitted Endosymbiotic Multicellular Cyanobacterium

    PubMed Central

    Vigil-Stenman, Theoden; Nylander, Johan A. A.; Ininbergs, Karolina; Zheng, Wei-Wen; Lapidus, Alla; Lowry, Stephen; Haselkorn, Robert; Bergman, Birgitta

    2010-01-01

    Background An ancient cyanobacterial incorporation into a eukaryotic organism led to the evolution of plastids (chloroplasts) and subsequently to the origin of the plant kingdom. The underlying mechanism and the identities of the partners in this monophyletic event remain elusive. Methodology/Principal Findings To shed light on this evolutionary process, we sequenced the genome of a cyanobacterium residing extracellularly in an endosymbiosis with a plant, the water-fern Azolla filiculoides Lam. This symbiosis was selected as it has characters which make it unique among extant cyanobacterial plant symbioses: the cyanobacterium lacks autonomous growth and is vertically transmitted between plant generations. Our results reveal features of evolutionary significance. The genome is in an eroding state, evidenced by a large proportion of pseudogenes (31.2%) and a high frequency of transposable elements (∼600) scattered throughout the genome. Pseudogenization is found in genes such as the replication initiator dnaA and DNA repair genes, considered essential to free-living cyanobacteria. For some functional categories of genes pseudogenes are more prevalent than functional genes. Loss of function is apparent even within the ‘core’ gene categories of bacteria, such as genes involved in glycolysis and nutrient uptake. In contrast, serving as a critical source of nitrogen for the host, genes related to metabolic processes such as cell differentiation and nitrogen-fixation are well preserved. Conclusions/Significance This is the first finding of genome degradation in a plant symbiont and phenotypically complex cyanobacterium and one of only a few extracellular endosymbionts described showing signs of reductive genome evolution. Our findings suggest an ongoing selective streamlining of this cyanobacterial genome which has resulted in an organism devoted to nitrogen fixation and devoid of autonomous growth. The cyanobacterial symbiont of Azolla can thus be considered at the

  12. Macrolactone Nuiapolide, Isolated from a Hawaiian Marine Cyanobacterium, Exhibits Anti-Chemotactic Activity

    PubMed Central

    Mori, Shogo; Williams, Howard; Cagle, Davey; Karanovich, Kristopher; Horgen, F. David; Smith, Roger; Watanabe, Coran M. H.

    2015-01-01

    A new bioactive macrolactone, nuiapolide (1) was identified from a marine cyanobacterium collected off the coast of Niihau, near Lehua Rock. The natural product exhibits anti-chemotactic activity at concentrations as low as 1.3 μM against Jurkat cells, cancerous T lymphocytes, and induces a G2/M phase cell cycle shift. Structural characterization of the natural product revealed the compound to be a 40-membered macrolactone with nine hydroxyl functional groups and a rare tert-butyl carbinol residue. PMID:26473885

  13. Macrolactone Nuiapolide, Isolated from a Hawaiian Marine Cyanobacterium, Exhibits Anti-Chemotactic Activity.

    PubMed

    Mori, Shogo; Williams, Howard; Cagle, Davey; Karanovich, Kristopher; Horgen, F David; Iii, Roger Smith; Watanabe, Coran M H

    2015-10-01

    A new bioactive macrolactone, nuiapolide (1) was identified from a marine cyanobacterium collected off the coast of Niihau, near Lehua Rock. The natural product exhibits anti-chemotactic activity at concentrations as low as 1.3 μM against Jurkat cells, cancerous T lymphocytes, and induces a G2/M phase cell cycle shift. Structural characterization of the natural product revealed the compound to be a 40-membered macrolactone with nine hydroxyl functional groups and a rare tert-butyl carbinol residue. PMID:26473885

  14. The Effects of the Toxic Cyanobacterium Limnothrix (Strain AC0243) on Bufo marinus Larvae

    PubMed Central

    Daniels, Olivia; Fabbro, Larelle; Makiela, Sandrine

    2014-01-01

    Limnothrix (strain AC0243) is a cyanobacterium, which has only recently been identified as toxin producing. Under laboratory conditions, Bufo marinus larvae were exposed to 100,000 cells mL−1 of Limnothrix (strain AC0243) live cultures for seven days. Histological examinations were conducted post mortem and revealed damage to the notochord, eyes, brain, liver, kidney, pancreas, gastrointestinal tract, and heart. The histopathological results highlight the toxicological impact of this strain, particularly during developmental stages. Toxicological similarities to β-N-Methylamino-l-alanine are discussed. PMID:24662524

  15. Pitiprolamide, a proline-rich dolastatin 16 analogue from the marine cyanobacterium Lyngbya majuscula from Guam.

    PubMed

    Montaser, Rana; Abboud, Khalil A; Paul, Valerie J; Luesch, Hendrik

    2011-01-28

    An unusual cyclic depsipeptide, pitiprolamide (1), was isolated from the marine cyanobacterium Lyngbya majuscula collected at Piti Bomb Holes, Guam. The structure was deduced using NMR, MS, X-ray crystallography, and enantioselective HPLC-MS techniques. Remarkably, proline represents half of the residues forming pitiprolamide (1). Other distinctive features include a 4-phenylvaline (dolaphenvaline, Dpv) moiety initially found in dolastatin 16 and the rare 2,2-dimethyl-3-hydroxyhexanoic acid (Dmhha) unit condensed in a unique sequence in one single molecule. Pitiprolamide (1) showed weak cytotoxic activity against HCT116 colon and MCF7 breast cancer cell lines, as well as weak antibacterial activities against Mycobacterium tuberculosis and Bacillus cereus.

  16. Inhibitory effect of petroleum oil on photosynthetic electron transport system in the cyanobacterium Anabaena doliolum

    SciTech Connect

    Singh, A.K.; Kumar, H.D. )

    1991-12-01

    Virtually nothing is known about the site of action of oil and the mechanism of inhibition of photosynthetic electron transport, a process responsible for the generation of ATP and NADPH, which are essential for carbon fixation. The present study was an attempt to learn something about these aspects. The influence of diesel on photosynthetic O{sub 2}-evolution, {sup 14}CO{sub 2} fixation, and electron transport system has been examined in Anabaena doliolum, a heterocystous cyanobacterium. A. doliolum and other heterocystous cyanobacteria are widely distributed in soil and aquatic ecosystems, and represent an important group of free-living nitrogen fixing microorganisms.

  17. Aerobic hydrogen accumulation by a nitrogen-fixing Cyanobacterium, Anabaena sp

    SciTech Connect

    Asada, Y.; Kawamura, S.

    1986-05-01

    Hydrogen evolution by a nitrogen-fixing cyanobacterium, Anabaena sp. strain N-7363, was tested in order to develop a water biophotolysis system under aerobic conditions. A culture of the strain supplemented with carbon dioxide under an air atmosphere evolved hydrogen and oxygen gas, which reached final concentrations of 9.7 and 69.8%, respectively, after 12 days of incubation. Hydrogen uptake activity was not observed during incubation, and nitrogenase was thought to be the sole enzyme responsible for the hydrogen evolution.

  18. Effects of Aminooxyacetate and Aminoacetonitrile on Glycolate and Ammonia Release by the Cyanobacterium Anabaena cylindrica1

    PubMed Central

    Bergman, Birgitta; Renström, Eva; Hällbom, Lars; Codd, Geoffrey A.

    1985-01-01

    Aminooxyacetate and aminoacetonitrile cause increased excretion of glycolate by the cyanobacterium Anabaena cylindrica. Both compounds also reduce NH4-N release induced by methionine sulfoximine in non-nitrogen-fixing cultures. Changes in amino acid pool sizes together with changes in activities of some enzymes related to glycolate metabolism show that glyoxylate to glycine conversion and glycine to serine conversion are inhibited by aminooxyacetate and aminoacetonitrile, respectively. The results also verify that photorespiratory glycolate metabolism via amination of glyoxylate is operative in A. cylindrica. PMID:16664093

  19. Deciphering the mechanisms against oxidative stress in developing and mature akinetes of the cyanobacterium Aphanizomenon ovalisporum.

    PubMed

    Kaplan-Levy, Ruth N; Hadas, Ora; Sukenik, Assaf

    2015-07-01

    Cells of filamentous cyanobacteria of the orders Nostocales and Stigonematales can differentiate into dormant forms called akinetes. Akinetes play a key role in the survival, abundance and distribution of the species, contributing an inoculum for their perennial blooms. In the cyanobacterium Aphanizomenon ovalisporum, potassium deficiency triggers the formation of akinetes. Here we present experimental evidence for the production of reactive oxygen species (ROS) during akinete development in response to potassium deficiency. The function of ROS as a primer signal for akinete differentiation was negated. Nevertheless, akinetes acquired protective mechanisms against oxidative damage during their differentiation and maintained them as they matured, giving akinetes advantages enabling survival in harsh conditions.

  20. Macrolactone Nuiapolide, Isolated from a Hawaiian Marine Cyanobacterium, Exhibits Anti-Chemotactic Activity.

    PubMed

    Mori, Shogo; Williams, Howard; Cagle, Davey; Karanovich, Kristopher; Horgen, F David; Iii, Roger Smith; Watanabe, Coran M H

    2015-10-01

    A new bioactive macrolactone, nuiapolide (1) was identified from a marine cyanobacterium collected off the coast of Niihau, near Lehua Rock. The natural product exhibits anti-chemotactic activity at concentrations as low as 1.3 μM against Jurkat cells, cancerous T lymphocytes, and induces a G2/M phase cell cycle shift. Structural characterization of the natural product revealed the compound to be a 40-membered macrolactone with nine hydroxyl functional groups and a rare tert-butyl carbinol residue.

  1. Unique thylakoid membrane architecture of a unicellular N2-fixing cyanobacterium revealed by electron tomography

    SciTech Connect

    Liberton, Michelle; Austin II, Jotham R; Berg, R. Howard; Pakrasi, Himadri B

    2011-04-01

    Cyanobacteria, descendants of the endosymbiont that gave rise to modern-day chloroplasts, are vital contributors to global biological energy conversion processes. A thorough understanding of the physiology of cyanobacteria requires detailed knowledge of these organisms at the level of cellular architecture and organization. In these prokaryotes, the large membrane protein complexes of the photosynthetic and respiratory electron transport chains function in the intracellular thylakoid membranes. Like plants, the architecture of the thylakoid membranes in cyanobacteria has direct impact on cellular bioenergetics, protein transport, and molecular trafficking. However, whole-cell thylakoid organization in cyanobacteria is not well understood. Here we present, by using electron tomography, an in-depth analysis of the architecture of the thylakoid membranes in a unicellular cyanobacterium, Cyanothece sp. ATCC 51142. Based on the results of three-dimensional tomographic reconstructions of near-entire cells, we determined that the thylakoids in Cyanothece 51142 form a dense and complex network that extends throughout the entire cell. This thylakoid membrane network is formed from the branching and splitting of membranes and encloses a single lumenal space. The entire thylakoid network spirals as a peripheral ring of membranes around the cell, an organization that has not previously been described in a cyanobacterium. Within the thylakoid membrane network are areas of quasi-helical arrangement with similarities to the thylakoid membrane system in chloroplasts. This cyanobacterial thylakoid arrangement is an efficient means of packing a large volume of membranes in the cell while optimizing intracellular transport and trafficking.

  2. Unique Thylakoid Membrane Architecture of a Unicellular N2-Fixing Cyanobacterium Revealed by Electron Tomography

    SciTech Connect

    Liberton, Michelle L.; Austin, Jotham R.; Berg, R. H.; Pakrasi, Himadri B.

    2011-04-01

    Cyanobacteria, descendants of the endosymbiont that gave rise to modern-day chloroplasts, are vital contributors to global biological energy conversion processes. A thorough understanding of the physiology of cyanobacteria requires detailed knowledge of these organisms at the level of cellular architecture and organization. In these prokaryotes, the large membrane protein complexes of the photosynthetic and respiratory electron transport chains function in the intracellular thylakoid membranes. Like plants, the architecture of the thylakoid membranes in cyanobacteria has direct impact on cellular bioenergetics, protein transport, and molecular trafficking. However, whole-cell thylakoid organization in cyanobacteria is not well understood. Here we present, by using electron tomography, an in-depth analysis of the architecture of the thylakoid membranes in a unicellular cyanobacterium, Cyanothece sp. ATCC 51142. Based on the results of three-dimensional tomographic reconstructions of near-entire cells, we determined that the thylakoids in Cyanothece 51142 form a dense and complex network that extends throughout the entire cell. This thylakoid membrane network is formed from the branching and splitting of membranes and encloses a single lumenal space. The entire thylakoid network spirals as a peripheral ring of membranes around the cell, an organization that has not previously been described in a cyanobacterium. Within the thylakoid membrane network are areas of quasi-helical arrangement with similarities to the thylakoid membrane system in chloroplasts. This cyanobacterial thylakoid arrangement is an efficient means of packing a large volume of membranes in the cell while optimizing intracellular transport and trafficking.

  3. Effect of Light Quality on Phycobilisome Components of the Cyanobacterium Spirulina platensis

    PubMed Central

    Babu, T. Sudhakar; Kumar, Ashok; Varma, Ajit K.

    1991-01-01

    Phycobilisomes from the nonchromatic adapting cyanobacterium Spirulina platensis are composed of a central core containing allophycocyanin and rods with phycocyanin and linker polypeptides in a regular array. Room temperature absorption spectra of phycobilisomes from this organism indicated the presence of phycocyanin and allophycocyanin. However, low temperature absorption spectra showed the association of a phycobiliviolin type of chromophore within phycobilisomes. This chromophore had an absorption maximum at 590 nanometers when phycobilisomes were suspended in 0.75 molar K-phosphate buffer (pH 7.0). Purified phycocyanin from this cyanobacterium was found to consist of three subparticles and the phycobiliviolin type of chromophore was associated with the lowest density subparticle. Circular dichroism spectra of phycocyanin subparticles also indicated the association of this chromophore with the lowest density subparticle. Absorption spectral analysis of α and β subunits of phycocyanin showed that phycobiliviolin type of chromophore was attached to the α subunit, but not the β subunit. Effect of light quality showed that green light enhanced the synthesis of this chromophore as analyzed from the room temperature absorption spectra of phycocyanin subparticles and subunits, while red or white light did not have any effect. Low temperature absorption spectra of phycobilisomes isolated from green, red, and white light conditions also indicated the enhancement of phycobiliviolin type of chromophore under green light. PMID:16668011

  4. Collapsing Aged Culture of the Cyanobacterium Synechococcus elongatus Produces Compound(s) Toxic to Photosynthetic Organisms

    PubMed Central

    Cohen, Assaf; Sendersky, Eleonora; Carmeli, Shmuel; Schwarz, Rakefet

    2014-01-01

    Phytoplankton mortality allows effective nutrient cycling, and thus plays a pivotal role in driving biogeochemical cycles. A growing body of literature demonstrates the involvement of regulated death programs in the abrupt collapse of phytoplankton populations, and particularly implicates processes that exhibit characteristics of metazoan programmed cell death. Here, we report that the cell-free, extracellular fluid (conditioned medium) of a collapsing aged culture of the cyanobacterium Synechococcus elongatus is toxic to exponentially growing cells of this cyanobacterium, as well as to a large variety of photosynthetic organisms, but not to eubacteria. The toxic effect, which is light-dependent, involves oxidative stress, as suggested by damage alleviation by antioxidants, and the very high sensitivity of a catalase-mutant to the conditioned medium. At relatively high cell densities, S. elongatus cells survived the deleterious effect of conditioned medium in a process that required de novo protein synthesis. Application of conditioned medium from a collapsing culture caused severe pigment bleaching not only in S. elongatus cells, but also resulted in bleaching of pigments in a cell free extract. The latter observation indicates that the elicited damage is a direct effect that does not require an intact cell, and therefore, is mechanistically different from the metazoan-like programmed cell death described for phytoplankton. We suggest that S. elongatus in aged cultures are triggered to produce a toxic compound, and thus, this process may be envisaged as a novel regulated death program. PMID:24959874

  5. The Effect of Small Scale Turbulence on the Physiology of Microcystis aeruginosa cyanobacterium

    NASA Astrophysics Data System (ADS)

    Wilkinson, Anne; Hondzo, Miki; Guala, Michele

    2014-11-01

    Microcystis aeruginosa is a single-celled blue-green alga, or cyanobacterium, that is responsible for poor water quality and microcystin production, which in high concentrations can be harmful to humans and animals. These harmful effects arise during cyanobacterium blooms. Blooms occur mainly in the summer when the algae grow uncontrollably and bond together to form colonies which accumulate on the surface of freshwater ecosystems. The relationship between fluid motion generated by wind and internal waves in stratified aquatic ecosystems and Microcystis can help explain the mechanisms of such blooms. We investigated the effect of small scale fluid motion on the physiology of Microcystis in a reactor with two underwater speakers. Different turbulent intensities were achieved by systematically changing the input signal frequency (30-50 Hz) and magnitude (0.1-0.2V) to the speakers. The role of turbulence is quantified by relating energy dissipation rates with the cell number, chlorophyll amount, dissolved oxygen production/uptake, and pH. The results suggest that turbulence mediates the physiology of Microcystis. The findings could be instrumental in designing restoration strategies that can minimize Microcystis blooms. This work was supported by the NSF Graduate Research Fellowship and University of Minnesota start-up funding.

  6. Antiherpetic efficacy of aqueous extracts of the cyanobacterium Arthrospira fusiformis from Chad.

    PubMed

    Sharaf, M; Amara, A; Aboul-Enein, A; Helmi, S; Ballot, A; Schnitzler, P

    2013-05-01

    Natural substances offer interesting pharmacological perspectives for antiviral drug development with regard to broad spectrum antiviral properties and novel modes of action. Drugs currently used to treat cutaneous or genital herpetic infections are effective in limiting disease, but the emergence of drug-resistant viruses in immunocompromised individuals can be problematic. A nontoxic cyanobacterium Arthrospira strain from Chad has been characterized by sequence analysis of the intergenic spacer region of the phycocyanin gene. This cyanobacterium was identified as Arthrospira fusiformis by phylogenetic tree analysis. The antiherpetic activity of crude aqueous extracts from the Chad A. fusiformis isolate was determined. Antiviral efficacy against herpes simplex virus of cold water extract, hot water extract and phosphate buffer extract was assessed in plaque reduction assays and their mode of antiherpetic action was analysed. In virus suspension assays, cold water extract, hot water extract and phosphate buffer extract inhibited virus infectivity by 54.9%, 64.6%, and 99.8%, respectively, in a dose-dependent manner. The mode of antiviral action was determined by addition of cyanobacterial extracts separately at different time periods during the viral infection cycle. Extracts of A. fusiformis strain clearly inhibited herpesvirus multiplication before and during virus infection of host cells. The phosphate buffer extract of the A. fusiformis strain affected free herpes simplex virus prior to infection of host cells and inhibited intracellular viral replication. It is concluded, that Arthrospira compounds warrant further investigation to examine their potential role in the treatment of herpetic infections.

  7. Discovery of an Endosymbiotic Nitrogen-Fixing Cyanobacterium UCYN-A in Braarudosphaera bigelowii (Prymnesiophyceae)

    PubMed Central

    Hagino, Kyoko; Onuma, Ryo; Kawachi, Masanobu; Horiguchi, Takeo

    2013-01-01

    Braarudosphaera bigelowii (Prymnesiophyceae) is a coastal coccolithophore with a long fossil record, extending back to the late Cretaceous (ca. 100 Ma). A recent study revealed close phylogenetic relationships between B. bigelowii, Chrysochromulina parkeae (Prymnesiophyceae), and a prymnesiophyte that forms a symbiotic association with the nitrogen-fixing cyanobacterium UCYN-A. In order to further examine these relationships, we conducted transmission electron microscopic and molecular phylogenetic studies of B. bigelowii. TEM studies showed that, in addition to organelles, such as the nucleus, chloroplasts and mitochondria, B. bigelowii contains one or two spheroid bodies with internal lamellae. In the 18S rDNA tree of the Prymnesiophyceae, C. parkeae fell within the B. bigelowii clade, and was close to B. bigelowii Genotype III (99.89% similarity). Plastid 16S rDNA sequences obtained from B. bigelowii were close to the unidentified sequences from the oligotrophic SE Pacific Ocean (e.g. HM133411) (99.86% similarity). Bacterial16S rDNA sequences obtained from B. bigelowii were identical to the UCYN-A sequence AY621693 from Arabian Sea, and fell in the UCYN-A clade. From these results, we suggest that; 1) C. parkeae is the alternate life cycle stage of B. bigelowii sensu stricto or that of a sibling species of B. bigelowii, and 2) the spheroid body of B. bigelowii originated from endosymbiosis of the nitrogen-fixing cyanobacterium UCYN-A. PMID:24324722

  8. The distribution of a phage-related insertion sequence element in the cyanobacterium, Microcystis aeruginosa.

    PubMed

    Kuno, Sotaro; Yoshida, Takashi; Kamikawa, Ryoma; Hosoda, Naohiko; Sako, Yoshihiko

    2010-01-01

    The cyanophage Ma-LMM01, specifically-infecting Microcystis aeruginosa, has an insertion sequence (IS) element that we named IS607-cp showing high nucleotide similarity to a counterpart in the genome of the cyanobacterium Cyanothece sp. We tested 21 strains of M. aeruginosa for the presence of IS607-cp using PCR and detected the element in strains NIES90, NIES112, NIES604, and RM6. Thermal asymmetric interlaced PCR (TAIL-PCR) revealed each of these strains has multiple copies of IS607-cp. Some of the ISs were classified into three types based on their inserted positions; IS607-cp-1 is common in strains NIES90, NIES112 and NIES604, whereas IS607-cp-2 and IS607-cp-3 are specific to strains NIES90 and RM6, respectively. This multiplicity may reflect the replicative transposition of IS607-cp. The sequence of IS607-cp in Ma-LMM01 showed robust affinity to those found in M. aeruginosa and Cyanothece spp. in a phylogenetic tree inferred from counterparts of various bacteria. This suggests the transfer of IS607-cp between the cyanobacterium and its cyanophage. We discuss the potential role of Ma-LMM01-related phages as donors of IS elements that may mediate the transfer of IS607-cp; and thereby partially contribute to the genome plasticity of M. aeruginosa.

  9. Targeted genetic inactivation of the photosystem I reaction center in the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Smart, L B; Anderson, S L; McIntosh, L

    1991-11-01

    We describe the first complete segregation of a targeted inactivation of psaA encoding one of the P700-chlorophyll a apoproteins of photosystem (PS) I. A kanamycin resistance gene was used to interrupt the psaA gene in the unicellular cyanobacterium Synechocystis sp. PCC 6803. Selection of a fully segregated mutant, ADK9, was performed under light-activated heterotrophic growth (LAHG) conditions; complete darkness except for 5 min of light every 24 h and 5 mM glucose. Under these conditions, wild-type cells showed a 4-fold decrease in chlorophyll (chl) per cell, primarily due to a decrease of PS I reaction centers. Evidence for the absence of PS I in ADK9 includes: the lack of EPR (electron paramagnetic resonance) signal I, from P700+; undetectable P700-apoprotein; greatly reduced whole-chain photosynthesis rates; and greatly reduced chl per cell, resulting in a turquoise blue phenotype. The PS I peripheral proteins PSA-C and PSA-D were not detected in this mutant. ADK9 does assemble near wild-type levels of functional PS II per cell, evidenced by: EPR signal II from YD+; high rates of oxygen evolution with 2,6-dichloro-p-benzoquinone (DCBQ), an electron acceptor from PS II; and accumulation of D1, a PS II core polypeptide. The success of this transformation indicates that this cyanobacterium may be utilized for site-directed mutagenesis of the PS I core.

  10. Discovery of an endosymbiotic nitrogen-fixing cyanobacterium UCYN-A in Braarudosphaera bigelowii (Prymnesiophyceae).

    PubMed

    Hagino, Kyoko; Onuma, Ryo; Kawachi, Masanobu; Horiguchi, Takeo

    2013-01-01

    Braarudosphaera bigelowii (Prymnesiophyceae) is a coastal coccolithophore with a long fossil record, extending back to the late Cretaceous (ca. 100 Ma). A recent study revealed close phylogenetic relationships between B. bigelowii, Chrysochromulina parkeae (Prymnesiophyceae), and a prymnesiophyte that forms a symbiotic association with the nitrogen-fixing cyanobacterium UCYN-A. In order to further examine these relationships, we conducted transmission electron microscopic and molecular phylogenetic studies of B. bigelowii. TEM studies showed that, in addition to organelles, such as the nucleus, chloroplasts and mitochondria, B. bigelowii contains one or two spheroid bodies with internal lamellae. In the 18S rDNA tree of the Prymnesiophyceae, C. parkeae fell within the B. bigelowii clade, and was close to B. bigelowii Genotype III (99.89% similarity). Plastid 16S rDNA sequences obtained from B. bigelowii were close to the unidentified sequences from the oligotrophic SE Pacific Ocean (e.g. HM133411) (99.86% similarity). Bacterial16S rDNA sequences obtained from B. bigelowii were identical to the UCYN-A sequence AY621693 from Arabian Sea, and fell in the UCYN-A clade. From these results, we suggest that; 1) C. parkeae is the alternate life cycle stage of B. bigelowii sensu stricto or that of a sibling species of B. bigelowii, and 2) the spheroid body of B. bigelowii originated from endosymbiosis of the nitrogen-fixing cyanobacterium UCYN-A.

  11. Aluminum effects on uptake and metabolism of phosphorus by the Cyanobacterium Anabaena cylindrica

    SciTech Connect

    Pettersson, A.; Haellbom, L. Bergman, B.

    1988-01-01

    Aluminum severely affects the growth of the cyanobacterium Anabaena cylindrica and induces symptoms indicating phosphorus starvation. Pre- or post-treating the cells with high (90 micromolar) phosphorus reduces the toxicity of aluminum compared to cells receiving a lower orthophosphate concentration. In this study aluminum (ranging from 9 to 36 micromolar) and phosphorus concentrations were chosen so that the precipitation of insoluble AlPO/sub 4/ never exceeded 10% of the total phosphate concentration. The uptake of /sup 32/P-phosphorus is not disturbed by aluminium either at high (100 micromolar) or low (10 micromolar) concentrations of phosphate. Also, the rapid accumulation of polyphosphate granules in cells exposed to aluminum indicates that the incorporation of phosphate is not disturbed. However, a significant decrease in the mobilization of the polyphosphates is observed, as is a lowered activity of the enzyme acid phosphatase, in aluminum treated cells. We conclude that aluminum acts on the intracellular metabolism of phosphate, which eventually leads to phosphorus starvation rather than on its uptake in the cyanobacterium A. cylindrica.

  12. Targeted genetic inactivation of the photosystem I reaction center in the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed Central

    Smart, L B; Anderson, S L; McIntosh, L

    1991-01-01

    We describe the first complete segregation of a targeted inactivation of psaA encoding one of the P700-chlorophyll a apoproteins of photosystem (PS) I. A kanamycin resistance gene was used to interrupt the psaA gene in the unicellular cyanobacterium Synechocystis sp. PCC 6803. Selection of a fully segregated mutant, ADK9, was performed under light-activated heterotrophic growth (LAHG) conditions; complete darkness except for 5 min of light every 24 h and 5 mM glucose. Under these conditions, wild-type cells showed a 4-fold decrease in chlorophyll (chl) per cell, primarily due to a decrease of PS I reaction centers. Evidence for the absence of PS I in ADK9 includes: the lack of EPR (electron paramagnetic resonance) signal I, from P700+; undetectable P700-apoprotein; greatly reduced whole-chain photosynthesis rates; and greatly reduced chl per cell, resulting in a turquoise blue phenotype. The PS I peripheral proteins PSA-C and PSA-D were not detected in this mutant. ADK9 does assemble near wild-type levels of functional PS II per cell, evidenced by: EPR signal II from YD+; high rates of oxygen evolution with 2,6-dichloro-p-benzoquinone (DCBQ), an electron acceptor from PS II; and accumulation of D1, a PS II core polypeptide. The success of this transformation indicates that this cyanobacterium may be utilized for site-directed mutagenesis of the PS I core. Images PMID:1717264

  13. Aluminum Effects on Uptake and Metabolism of Phosphorus by the Cyanobacterium Anabaena cylindrica

    PubMed Central

    Pettersson, Annette; Hällbom, Lars; Bergman, Birgitta

    1988-01-01

    Aluminum severely affects the growth of the cyanobacterium Anabaena cylindrica and induces symptoms indicating phosphorus starvation. Preor post-treating the cells with high (90 micromolar) phosphorus reduces the toxicity of aluminum compared to cells receiving a lower orthophosphate concentration. In this study aluminum (ranging from 9 to 36 micromolar) and phosphorus concentrations were chosen so that the precipitation of insoluble AIPO4 never exceeded 10% of the total phosphate concentration. The uptake of 32P-phosphorus is not disturbed by aluminum either at high (100 micromolar) or low (10 micromolar) concentrations of phosphate. Also, the rapid accumulation of polyphosphate granules in cells exposed to aluminum indicates that the incorporation of phosphate is not disturbed. However, a significant decrease in the mobilization of the polyphosphates is observed, as is a lowered activity of the enzyme acid phosphatase, in aluminum treated cells. We conclude that aluminum acts on the intracellular metabolism of phosphate, which eventually leads to phosphorus starvation rather than on its uptake in the cyanobacterium A. cylindrica. PMID:16665849

  14. Cellular and functional specificity among ferritin-like proteins in the multicellular cyanobacterium Nostoc punctiforme.

    PubMed

    Ekman, Martin; Sandh, Gustaf; Nenninger, Anja; Oliveira, Paulo; Stensjö, Karin

    2014-03-01

    Ferritin-like proteins constitute a remarkably heterogeneous protein family, including ferritins, bacterioferritins and Dps proteins. The genome of the filamentous heterocyst-forming cyanobacterium Nostoc punctiforme encodes five ferritin-like proteins. In the present paper, we report a multidimensional characterization of these proteins. Our phylogenetic and bioinformatics analyses suggest both structural and physiological differences among the ferritin-like proteins. The expression of these five genes responded differently to hydrogen peroxide treatment, with a significantly higher rise in transcript level for Npun_F3730 as compared with the other four genes. A specific role for Npun_F3730 in the cells tolerance against hydrogen peroxide was also supported by the inactivation of Npun_F3730, Npun_R5701 and Npun_R6212; among these, only the ΔNpun_F3730 strain showed an increased sensitivity to hydrogen peroxide compared with wild type. Analysis of promoter-GFP reporter fusions of the ferritin-like genes indicated that Npun_F3730 and Npun_R5701 were expressed in all cell types of a diazotrophic culture, while Npun_F6212 was expressed specifically in heterocysts. Our study provides the first comprehensive analysis combining functional differentiation and cellular specificity within this important group of proteins in a multicellular cyanobacterium. PMID:23992552

  15. Dynamics of the Toxin Cylindrospermopsin and the Cyanobacterium Chrysosporum (Aphanizomenon) ovalisporum in a Mediterranean Eutrophic Reservoir

    PubMed Central

    Fadel, Ali; Atoui, Ali; Lemaire, Bruno J.; Vinçon-Leite, Brigitte; Slim, Kamal

    2014-01-01

    Chrysosporum ovalisporum is a cylindrospermopsin toxin producing cyanobacterium that was reported in several lakes and reservoirs. Its growth dynamics and toxin distribution in field remain largely undocumented. Chrysosporum ovalisporum was reported in 2009 in Karaoun Reservoir, Lebanon. We investigated the factors controlling the occurrence of this cyanobacterium and vertical distribution of cylindrospermopsin in Karaoun Reservoir. We conducted bi-weekly sampling campaigns between May 2012 and August 2013. Results showed that Chrysosporum ovalisporum is an ecologically plastic species that was observed in all seasons. Unlike the high temperatures, above 26 °C, which is associated with blooms of Chrysosporum ovalisporum in Lakes Kinneret (Israel), Lisimachia and Trichonis (Greece) and Arcos Reservoir (Spain), Chrysosporum ovalisporum in Karaoun Reservoir bloomed in October 2012 at a water temperature of 22 °C during weak stratification. Cylindrospermopsin was detected in almost all water samples even when Chrysosporum ovalisporum was not detected. Chrysosporum ovalisporum biovolumes and cylindrospermopsin concentrations were not correlated (n = 31, r2 = −0.05). Cylindrospermopsin reached a maximum concentration of 1.7 µg L−1. The vertical profiles of toxin concentrations suggested its possible degradation or sedimentation resulting in its disappearance from the water column. The field growth conditions of Chrysosporum ovalisporum in this study revealed that it can bloom at the subsurface water temperature of 22 °C increasing the risk of its development and expansion in lakes located in temperate climate regions. PMID:25354130

  16. Molecular Characterization of the Toxic Cyanobacterium Cylindrospermopsis raciborskii and Design of a Species-Specific PCR

    PubMed Central

    Wilson, Kim M.; Schembri, Mark A.; Baker, Peter D.; Saint, Christopher P.

    2000-01-01

    Cylindrospermopsis raciborskii is a toxic-bloom-forming cyanobacterium that is commonly found in tropical to subtropical climatic regions worldwide, but it is also recognized as a common component of cyanobacterial communities in temperate climates. Genetic profiles of C. raciborskii were examined in 19 cultured isolates originating from geographically diverse regions of Australia and represented by two distinct morphotypes. A 609-bp region of rpoC1, a DNA-dependent RNA polymerase gene, was amplified by PCR from these isolates with cyanobacterium-specific primers. Sequence analysis revealed that all isolates belonged to the same species, including morphotypes with straight or coiled trichomes. Additional rpoC1 gene sequences obtained for a range of cyanobacteria highlighted clustering of C. raciborskii with other heterocyst-producing cyanobacteria (orders Nostocales and Stigonematales). In contrast, randomly amplified polymorphic DNA and short tandemly repeated repetitive sequence profiles revealed a greater level of genetic heterogeneity among C. raciborskii isolates than did rpoC1 gene analysis, and unique band profiles were also found among each of the cyanobacterial genera examined. A PCR test targeting a region of the rpoC1 gene unique to C. raciborskii was developed for the specific identification of C. raciborskii from both purified genomic DNA and environmental samples. The PCR was evaluated with a number of cyanobacterial isolates, but a PCR-positive result was only achieved with C. raciborskii. This method provides an accurate alternative to traditional morphological identification of C. raciborskii. PMID:10618244

  17. Crucial role of extracellular polysaccharides in desiccation and freezing tolerance in the terrestrial cyanobacterium Nostoc commune.

    PubMed

    Tamaru, Yoshiyuki; Takani, Yayoi; Yoshida, Takayuki; Sakamoto, Toshio

    2005-11-01

    The cyanobacterium Nostoc commune is adapted to the terrestrial environment and has a cosmopolitan distribution. In this study, the role of extracellular polysaccharides (EPS) in the desiccation tolerance of photosynthesis in N. commune was examined. Although photosynthetic O2 evolution was not detected in desiccated colonies, the ability of the cells to evolve O2 rapidly recovered after rehydration. The air-dried colonies contained approximately 10% (wt/wt) water, and field-isolated, natural colonies with EPS were highly water absorbent and were rapidly hydrated by atmospheric moisture. The cells embedded in EPS in Nostoc colonies were highly desiccation tolerant, and O2 evolution was not damaged by air drying. Although N. commune was determined to be a mesophilic cyanobacterium, the cells with EPS were heat tolerant in a desiccated state. EPS could be removed from cells by homogenizing colonies with a blender and filtering with coarse filter paper. This treatment to remove EPS did not damage Nostoc cells or their ability to evolve O2, but O2 evolution was significantly damaged by desiccation treatment of the EPS-depleted cells. Similar to the EPS-depleted cells, the laboratory culture strain KU002 had only small amount of EPS and was highly sensitive to desiccation. In the EPS-depleted cells, O2 evolution was also sensitive to freeze-thaw treatment. These results strongly suggest that EPS of N. commune is crucial for the stress tolerance of photosynthesis during desiccation and during freezing and thawing.

  18. Bouillonamide: A Mixed Polyketide–Peptide Cytotoxin from the Marine Cyanobacterium Moorea bouillonii

    PubMed Central

    Tan, Lik Tong; Okino, Tatsufumi; Gerwick, William H.

    2013-01-01

    The tropical marine cyanobacterium, Moorea bouillonii, has gained recent attention as a rich source of bioactive natural products. Continued chemical investigation of this cyanobacterium, collected from New Britain, Papua New Guinea, yielded a novel cytotoxic cyclic depsipeptide, bouillonamide (1), along with previously reported molecules, ulongamide A and apratoxin A. Planar structure of bouillonamide was established by extensive 1D and 2D NMR experiments, including multi-edited HSQC, TOCSY, HBMC, and ROESY experiments. In addition to the presence of α-amino acid residues, compound 1 contained two unique polyketide-derived moieties, namely a 2-methyl-6-methylamino-hex-5-enoic acid (Mmaha) residue and a unit of 3-methyl-5-hydroxy-heptanoic acid (Mhha). Absolute stereochemistry of the α-amino acid units in bouillonamide was determined mainly by Marfey’s analysis. Compound 1 exhibited mild toxicity with IC50’s of 6.0 µM against the neuron 2a mouse neuroblastoma cells. PMID:23966034

  19. Diurnal Rhythms Result in Significant Changes in the Cellular Protein Complement in the Cyanobacterium Cyanothece 51142

    SciTech Connect

    Stockel, Jana; Jacobs, Jon M.; Elvitigala, Thanura R.; Liberton, Michelle L.; Welsh, Eric A.; Polpitiya, Ashoka D.; Gritsenko, Marina A.; Nicora, Carrie D.; Koppenaal, David W.; Smith, Richard D.; Pakrasi, Himadri B.

    2011-02-22

    Cyanothece sp. ATCC 51142 is a diazotrophic cyanobacterium notable for its ability to perform oxygenic photosynthesis and dinitrogen fixation in the same single cell. Previous transcriptional analysis revealed that the existence of these incompatible cellular processes largely depends on tightly synchronized expression programs involving ,30% of genes in the genome. To expand upon current knowledge, we have utilized sensitive proteomic approaches to examine the impact of diurnal rhythms on the protein complement in Cyanothece 51142. We found that 250 proteins accounting for,5% of the predicted ORFs from the Cyanothece 51142 genome and 20% of proteins detected under alternating light/dark conditions exhibited periodic oscillations in their abundances. Our results suggest that altered enzyme activities at different phases during the diurnal cycle can be attributed to changes in the abundance of related proteins and key compounds. The integration of global proteomics and transcriptomic data further revealed that post-transcriptional events are important for temporal regulation of processes such as photosynthesis in Cyanothece 51142. This analysis is the first comprehensive report on global quantitative proteomics in a unicellular diazotrophic cyanobacterium and uncovers novel findings about diurnal rhythms.

  20. Draft Genome Sequence of Leptolyngbya sp. KIOST-1, a Filamentous Cyanobacterium with Biotechnological Potential for Alimentary Purposes

    PubMed Central

    Kim, Ji Hyung

    2016-01-01

    Here, we report the draft genome of cyanobacterium Leptolyngbya sp. KIOST-1 isolated from a microalgal culture pond in South Korea. The genome consists of 13 contigs containing 6,320,172 bp, and a total of 5,327 coding sequences were predicted. This genomic information will allow further exploitation of its biotechnological potential for alimentary purposes. PMID:27635005

  1. Draft Genome Sequence of Leptolyngbya sp. KIOST-1, a Filamentous Cyanobacterium with Biotechnological Potential for Alimentary Purposes.

    PubMed

    Kim, Ji Hyung; Kang, Do-Hyung

    2016-01-01

    Here, we report the draft genome of cyanobacterium Leptolyngbya sp. KIOST-1 isolated from a microalgal culture pond in South Korea. The genome consists of 13 contigs containing 6,320,172 bp, and a total of 5,327 coding sequences were predicted. This genomic information will allow further exploitation of its biotechnological potential for alimentary purposes. PMID:27635005

  2. Draft Genome Sequence of Calothrix Strain 336/3, a Novel H2-Producing Cyanobacterium Isolated from a Finnish Lake

    PubMed Central

    Isojärvi, Janne; Shunmugam, Sumathy; Sivonen, Kaarina; Allahverdiyeva, Yagut; Aro, Eva-Mari

    2015-01-01

    We announce the draft genome sequence of Calothrix strain 336/3, an N2-fixing heterocystous filamentous cyanobacterium isolated from a natural habitat. Calothrix 336/3 produces higher levels of hydrogen than Nostoc punctiforme PCC 73102 and Anabaena strain PCC 7120 and, therefore, is of interest for potential technological applications. PMID:25614574

  3. Draft Genome Sequence of a Thermophilic Cyanobacterium from the Family Oscillatoriales (Strain MTP1) from the Chalk River, Colorado

    PubMed Central

    Grogger, Melanie; Mraz, Megan; Veverka, Donald

    2016-01-01

    The draft genome (57.7% GC, 7,647,882 bp) of the novel thermophilic cyanobacterium MTP1 was determined by metagenomics of an enrichment culture. The genome shows that it is in the family Oscillatoriales and encodes multiple heavy metal resistances as well as the capacity to make exopolysaccharides. PMID:26893415

  4. Draft Genome Sequence of a Thermophilic Cyanobacterium from the Family Oscillatoriales (Strain MTP1) from the Chalk River, Colorado.

    PubMed

    Hallenbeck, Patrick C; Grogger, Melanie; Mraz, Megan; Veverka, Donald

    2016-01-01

    The draft genome (57.7% GC, 7,647,882 bp) of the novel thermophilic cyanobacterium MTP1 was determined by metagenomics of an enrichment culture. The genome shows that it is in the family Oscillatoriales and encodes multiple heavy metal resistances as well as the capacity to make exopolysaccharides. PMID:26893415

  5. Genetic transformation of marine cyanobacterium Synechococcus sp. CC9311 (Cyanophyceae) by electroporation

    NASA Astrophysics Data System (ADS)

    Chen, Huaxin; Lin, Hanzhi; Jiang, Peng; Li, Fuchao; Qin, Song

    2013-03-01

    Synechococcus sp. CC9311 is a marine cyanobacterium characterized by type IV chromatic acclimation (CA). A genetic transformation system was developed as a first step to elucidate the molecular mechanism of CA. The results show that Synechococcus sp. CC9311 cells were sensitive to four commonly used antibiotics: ampicillin, kanamycin, spectinomycin, and chloramphenicol. An integrative plasmid to disrupt the putative phycoerythrin lyase gene mpeV, using a kanamycin resistance gene as selectable marker, was constructed by recombinant polymerase chain reaction. The plasmid was then transformed into Synechococcus sp. CC9311 via electroporation. High transformation efficiency was achieved at a field strength of 2 kV/cm. DNA analysis showed that mpeV was fully disrupted following challenge of the transformants with a high concentration of kanamycin. In addition, the transformants that displayed poor growth on agar SN medium could be successfully plated on agarose SN medium.

  6. Flocculation properties of several microalgae and a cyanobacterium species during ferric chloride, chitosan and alkaline flocculation.

    PubMed

    Lama, Sanjaya; Muylaert, Koenraad; Karki, Tika Bahadur; Foubert, Imogen; Henderson, Rita K; Vandamme, Dries

    2016-11-01

    Flocculation holds great potential as a low-cost harvesting method for microalgae biomass production. Three flocculation methods (ferric chloride, chitosan, and alkaline flocculation) were compared in this study for the harvesting of 9 different freshwater and marine microalgae and one cyanobacterium species. Ferric chloride resulted in a separation efficiency greater than 90% with a concentration factor (CF) higher than 10 for all species. Chitosan flocculation worked generally very well for freshwater microalgae, but not for marine species. Alkaline flocculation was most efficient for harvesting of Nannochloropsis, Chlamydomonas and Chlorella sp. The concentration factor was highly variable between microalgae species. Generally, minimum flocculant dosages were highly variable across species, which shows that flocculation may be a good harvesting method for some species but not for others. This study shows that microalgae and cyanobacteria species should not be selected solely based on their productivity but also on their potential for low-cost separation. PMID:27611030

  7. Reductive transformation of methyl parathion by the cyanobacterium Anabaena sp. strain PCC7120.

    PubMed

    Barton, J W; Kuritz, T; O'Connor, L E; Ma, C Y; Maskarinec, M P; Davison, B H

    2004-08-01

    Organophosphorus compounds are toxic chemicals that are applied worldwide as household pesticides and for crop protection, and they are stockpiled for chemical warfare. As a result, they are routinely detected in air and water. Methods and routes of biodegradation of these compounds are being sought. We report that under aerobic, photosynthetic conditions, the cyanobacterium Anabaena sp. transformed methyl parathion first to o,o-dimethyl o-p-nitrosophenyl thiophosphate and then to o,o-dimethyl o-p-aminophenyl thiophosphate by reducing the nitro group. The process of methyl parathion transformation occurred in the light, but not in the dark. Methyl parathion was toxic to cyanobacteria in the dark but did not affect their viability in the light. Methyl parathion transformation was not affected by mutations in the genes involved in nitrate reduction in cyanobacteria. PMID:14758519

  8. On the relation between phosphate uptake and growth of the cyanobacterium Anacystis nidulans.

    PubMed

    Falkner, G; Wagner, F; Falkner, R

    1994-06-01

    The energy dependent phosphate uptake by the cyanobacterium Anacystis nidulans has been analysed in terms of a "linear energy converter" that describes the interrelationship between phosphate incorporation into the polyphosphate pool and the photosynthetic proton flux at the thylakoid membrane. It is assumed that both processes are coupled in such a way that uptake proceeds with optimal efficiency at the prevailing phosphate concentration in the growth medium. On the basis of this model two important parameters of the uptake system can be calculated: first, a conductivity coefficient that reflects the activity of the uptake system and second, a minimal threshold value of external phosphate at which uptake ceases. The theoretical data are shown to fit the experimentally observed uptake behaviour of cyanobacteria when the same population is subjected to a transition from growth on low to high phosphate concentrations, mimicking a situation that frequently leads in natural waters to an algal bloom. PMID:7987705

  9. The regulation of HanA during heterocyst development in cyanobacterium Anabaena sp. PCC 7120.

    PubMed

    Lu, Jing-Jing; Shi, Lei; Chen, Wen-Li; Wang, Li

    2014-10-01

    In response to deprivation of combined nitrogen, the filamentous cyanobacterium Anabaena sp. strain PCC 7120 develops heterocyst, which is specifically involved in the nitrogen fixation. In this study, we focused on the regulation of HanA, a histone-like protein, in heterocyst development. Electrophoretic mobility shift assay results showed that NtcA, a global nitrogen regulator necessary for heterocyst differentiation, could bind to two NtcA-binding motifs in the hanA promoter region. qPCR results also showed that NtcA may regulate the expression of hanA. By using the hanA promoter-controlled gfp as a reporter gene and performing western blot we found that the amount of HanA in mature heterocysts was decreased gradually.

  10. Phenotypic and phylogenetic analyses show Microcoleus chthonoplastes to be a cosmopolitan cyanobacterium.

    PubMed Central

    Garcia-Pichel, F; Prufert-Bebout, L; Muyzer, G

    1996-01-01

    We used micromanipulation to isolate from their environment representative samples of seven geographically distant field populations fitting the description of Microcoleus chthonoplastes (a cyanobacterium) and obtained seven corresponding cultured strains. Samples of both field populations and cultures were phenotypically characterized by microscale techniques, and their partial 16S rRNA gene sequences were compared by denaturing gradient gel electrophoresis and in some cases by sequencing. All field populations and strains were phenotypically extremely coherent, and their 16S rRNA sequences were indistinguishable by DGGE. The sequences determined were identical or virtually identical. Thus, M. chthonoplastes represents a single, well-delimited taxon with a truly cosmopolitan distribution. Comparison with three culture collection strains originally assigned to M. chthonoplastes revealed that strain PCC 7420 belongs to the same tightly delimited group, both phenotypically and in 16S rRNA gene sequence, but that strains SAG 3192 and 10mfx do not. PMID:8795218

  11. Back from the dead; the curious tale of the predatory cyanobacterium Vampirovibrio chlorellavorus

    PubMed Central

    Soo, Rochelle M.; Woodcroft, Ben J.; Parks, Donovan H.; Tyson, Gene W.

    2015-01-01

    An uncultured non-photosynthetic basal lineage of the Cyanobacteria, the Melainabacteria, was recently characterised by metagenomic analyses of aphotic environmental samples. However, a predatory bacterium, Vampirovibrio chlorellavorus, originally described in 1972 appears to be the first cultured representative of the Melainabacteria based on a 16S rRNA sequence recovered from a lyophilised co-culture of the organism. Here, we sequenced the genome of V. chlorellavorus directly from 36 year-old lyophilised material that could not be resuscitated confirming its identity as a member of the Melainabacteria. We identified attributes in the genome that likely allow V. chlorellavorus to function as an obligate predator of the microalga Chlorella vulgaris, and predict that it is the first described predator to use an Agrobacterium tumefaciens-like conjugative type IV secretion system to invade its host. V. chlorellavorus is the first cyanobacterium recognised to have a predatory lifestyle and further supports the assertion that Melainabacteria are non-photosynthetic. PMID:26038723

  12. Use of superoxide as an electron shuttle for iron acquisition by the marine cyanobacterium Lyngbya majuscula.

    PubMed

    Rose, Andrew L; Salmon, Tim P; Lukondeh, Tredwell; Neilan, Brett A; Waite, T David

    2005-05-15

    Reduction of iron from the ferric state to the ferrous state is one strategy employed by microorganisms in nearneutral environments to increase its biological availability. In recent years, the existence of mobile reducing agents produced bymicroorganismsto promote iron reduction, known as electron shuttles, has been demonstrated. Production of electron shuttles has been shown for several organisms, employing a variety of mostly organic molecules as the electron carrier. Here we show that the coastal cyanobacterium Lyngbya majuscula produces iron-reducing superoxide radicals (02*-) and that this facilitates increased iron uptake. We suggest that superoxide is a useful electron shuttle because it reacts rapidly and almost indiscriminately with Fe(lll)-organic complexes and its precursor, dissolved oxygen, is ubiquitous in the photic zone. We further suggest that, for these reasons, the generation of superoxide by marine oxygenic photosynthetic microorganisms and its use in facilitating iron uptake may be a reasonably widespread process.

  13. Pitiprolamide, a Proline-Rich Dolastatin 16 Analogue from the Marine Cyanobacterium Lyngbya majuscula from Guam

    PubMed Central

    Montaser, Rana; Abboud, Khalil A.; Paul, Valerie J.; Luesch, Hendrik

    2010-01-01

    An unusual cyclic depsipeptide, pitiprolamide (1), was isolated from the marine cyanobacterium Lyngbya majuscula collected at Piti Bomb Holes, Guam. The structure was deduced using NMR, MS, X-ray crystallography and enantioselective HPLC-MS techniques. Remarkably, proline represents half of the residues forming pitiprolamide (1). Other distinctive features include a 4-phenylvaline (dolaphenvaline, Dpv) moiety initially found in dolastatin 16 and the rare 2,2-dimethyl-3-hydroxyhexanoic acid (Dmhha) unit condensed in a unique sequence in one single molecule. Pitiprolamide (1) showed weak cytotoxic activity against HCT116 colon and MCF7 breast cancer cell lines, as well as weak antibacterial activities against Mycobacterium tuberculosis and Bacillus cereus. PMID:21138309

  14. Cytochrome c-553 is not required for photosynthetic activity in the cyanobacterium Synechococcus.

    PubMed Central

    Laudenbach, D E; Herbert, S K; McDowell, C; Fork, D C; Grossman, A R; Straus, N A

    1990-01-01

    In cyanobacteria, the water-soluble cytochrome c-553 functions as a mobile carrier of electrons between the membrane-bound cytochrome b6-f complex and P-700 reaction centers of Photosystem I. The structural gene for cytochrome c-553 (designated cytA) of the cyanobacterium Synechococcus sp. PCC 7942 was cloned, and the deduced amino acid sequence was shown to be similar to known cyanobacterial cytochrome c-553 proteins. A deletion mutant was constructed that had no detectable cytochrome c-553 based on spectral analyses and tetramethylbenzidine-hydrogen peroxide staining of proteins resolved by polyacrylamide gel electrophoresis. The mutant strain was not impaired in overall photosynthetic activity. However, this mutant exhibited a decreased efficiency of cytochrome f oxidation. These results indicate that cytochrome c-553 is not an absolute requirement for reducing Photosystem I reaction centers in Synechococcus sp. PCC 7942. PMID:1967057

  15. Flocculation properties of several microalgae and a cyanobacterium species during ferric chloride, chitosan and alkaline flocculation.

    PubMed

    Lama, Sanjaya; Muylaert, Koenraad; Karki, Tika Bahadur; Foubert, Imogen; Henderson, Rita K; Vandamme, Dries

    2016-11-01

    Flocculation holds great potential as a low-cost harvesting method for microalgae biomass production. Three flocculation methods (ferric chloride, chitosan, and alkaline flocculation) were compared in this study for the harvesting of 9 different freshwater and marine microalgae and one cyanobacterium species. Ferric chloride resulted in a separation efficiency greater than 90% with a concentration factor (CF) higher than 10 for all species. Chitosan flocculation worked generally very well for freshwater microalgae, but not for marine species. Alkaline flocculation was most efficient for harvesting of Nannochloropsis, Chlamydomonas and Chlorella sp. The concentration factor was highly variable between microalgae species. Generally, minimum flocculant dosages were highly variable across species, which shows that flocculation may be a good harvesting method for some species but not for others. This study shows that microalgae and cyanobacteria species should not be selected solely based on their productivity but also on their potential for low-cost separation.

  16. nifH,D,K gene organization in the cyanobacterium, Plectonema boryanum

    SciTech Connect

    Barnum, S.R.; Gendel, S.M.

    1986-04-01

    Cyanobacteria are a diverse group of Gram-negative oxygenic photosynthetic prokaryotes with some species capable of fixing atmospheric nitrogen. Detailed studies dealing with the organization of nitrogen fixation genes have been limited to Anabaena, a filamentous, heterocystous cyanobacterium. The authors have determined the organization of nifH,D,K in Plectonema boryanum, a filamentous, nonheterocystous species that fixes nitrogen microaerophilically. It has been demonstrated that nifH,D,K genes are contiguous in cells grown under non-nitrogen fixing conditions using Anabaena nif genes as probes in Southern observed for all three nif genes as probes in southern hybridizations. A change in the pattern of hybridization was observed for all three nif genes isolated from cells grown under nitrogen fixing conditions. Restriction enzyme digestion experiments and analysis of cloned Plectonema nif genes are being used to determine the type of DNA modification and the location.

  17. Molecular cloning of a recA-like gene from the cyanobacterium Anabaena variabilis

    SciTech Connect

    Owttrim, G.W.; Coleman, J.R.

    1987-05-01

    A recA-like gene isolated from the cyanobacterium Anabaena variabilis was cloned and partially characterized. When introduced into Escherichia coli recA mutants, the 7.5-kilobase-pair plasmid-borne DNA insert restored resistance to methyl methanesulfonate and UV irradiation, as well as recombination proficiency when measured by Hfr-mediated conjugation. The cyanobacterial recA gene restored spontaneous but not mitomycin C-induced prophage production. Restriction analysis and subcloning yielded a 1.5-kilobase-pair Sau3A fragment which also restored methylmethane sulfonate resistance and coded for a 38- to 40-kilodalton polypeptide when expressed in an in vitro transcription-translation system.

  18. Purification and properties of glutathione reductase from the cyanobacterium Anabaena sp. strain 7119

    SciTech Connect

    Serrano, A.; Rivas, J.; Losada, M.

    1984-04-01

    An NADPH-glutathione reductase (EC 1.6.4.2) has been purified 6000-fold to electrophoretic homogeneity from the filamentous cyanobacterium Anabaena sp. strain 7119. The purified enzyme exhibits a specific activity of 249 U/mg and is characterized by being a dimeric flavin adenine dinucleotide-containing protein with a ratio of absorbance at 280 nm to absorbance at 462 nm of 5.8, a native molecular weight of 104,000, a Stokes radius of 4.13 nm, and a pI of 4.02. The enzyme activity is inhibited by sulfhydryl reagents and heavy-metal ions, especially in the presence of NADPH, with oxidized glutathione behaving as a protective agent. As is the case with the same enzyme from other sources, the kinetic data are consistent with a branched mechanism. Nevertheless, the cyanobacterial enzyme presents three distinctive

  19. Local Expansion of a Panmictic Lineage of Water Bloom-Forming Cyanobacterium Microcystis aeruginosa

    PubMed Central

    Tanabe, Yuuhiko; Watanabe, Makoto M.

    2011-01-01

    In previous studies, we have demonstrated that the population structure of the bloom-forming cyanobacterium Microcystis aeruginosa is clonal. Expanded multilocus sequence typing analysis of M. aeruginosa using 412 isolates identified five intraspecific lineages suggested to be panmictic while maintaining overall clonal structure probably due to a reduced recombination rate between lineages. Interestingly, since 2005 most strains belonging to one of these panmictic clusters (group G) have been found in a particular locality (Lake Kasumigaura Basin) in Japan. In this locality, multiple, similar but distinct genotypes of this lineage predominated in the bloom, a pattern that is unprecedented for M. aeruginosa. The population structure underlying blooms associated with this lineage is comparable to epidemics of pathogens. Our results may reveal an expansion of the possible adaptive lineage in a localized aquatic environment, providing us with a unique opportunity to investigate its ecological and biogeographical consequences. PMID:21390221

  20. The regulation of HanA during heterocyst development in cyanobacterium Anabaena sp. PCC 7120.

    PubMed

    Lu, Jing-Jing; Shi, Lei; Chen, Wen-Li; Wang, Li

    2014-10-01

    In response to deprivation of combined nitrogen, the filamentous cyanobacterium Anabaena sp. strain PCC 7120 develops heterocyst, which is specifically involved in the nitrogen fixation. In this study, we focused on the regulation of HanA, a histone-like protein, in heterocyst development. Electrophoretic mobility shift assay results showed that NtcA, a global nitrogen regulator necessary for heterocyst differentiation, could bind to two NtcA-binding motifs in the hanA promoter region. qPCR results also showed that NtcA may regulate the expression of hanA. By using the hanA promoter-controlled gfp as a reporter gene and performing western blot we found that the amount of HanA in mature heterocysts was decreased gradually. PMID:24980942

  1. Effects of light and temperature on open cultivation of desert cyanobacterium Microcoleus vaginatus.

    PubMed

    Lan, Shubin; Wu, Li; Zhang, Delu; Hu, Chunxiang

    2015-04-01

    Microalgae cultivation has recently been recognized as an important issue to deal with the increasingly prominent resource and environmental problems. In this study, desert cyanobacterium Microcoleus vaginatus was open cultivated in 4 different cultivation conditions in Qubqi Desert, and it was found Chlorella sp., Scenedesmus sp. and Navicula sp. were the main contaminating microalgal species during the cultivation. High light intensity alone was responsible for the green algae contamination, but the accompanied high temperature was beneficial to cyanobacterial growth, and the maximum biomass productivity acquired was 41.3mgL(-1)d(-1). Low temperature was more suitable for contaminating diatoms' growth, although all the microalgae (including the target and contaminating) are still demand for a degree of light intensity, at least average daily light intensity >5μEm(-2)s(-1). As a whole, cultivation time, conditions and their interaction had a significant impact on microalgal photosynthetic activity (Fv/Fm), biomass and exopolysaccharides content (P<0.001).

  2. Supramolecular organization of phycobiliproteins in the chlorophyll d-containing cyanobacterium Acaryochloris marina.

    PubMed

    Chen, Min; Floetenmeyer, Matthias; Bibby, Thomas S

    2009-08-01

    Here we report the high-resolution detail of the organization of phycobiliprotein structures associated with photosynthetic membranes of the chlorophyll d-containing cyanobacterium Acaryochloris marina. Cryo-electron transmission-microscopy on native cell sections show extensive patches of near-crystalline phycobiliprotein rods that are associated with the stromal side of photosynthetic membranes. This supramolecular photosynthetic structure represents a novel mechanism of organizing the photosynthetic light-harvesting machinery. In addition, the specific location of phycobiliprotein patches suggests a physical separation of photosystem I and photosystem II reaction centres. Based on this finding and the known photosystem's structure in Acaryochloris, we discuss possible membrane arrangements of photosynthetic membrane complexes in this species.

  3. Composition and occurrence of lipid droplets in the cyanobacterium Nostoc punctiforme

    PubMed Central

    Peramuna, Anantha; Summers, Michael L.

    2014-01-01

    Inclusions of neutral lipids termed lipid droplets (LDs) located throughout the cell were identified in the cyanobacterium Nostoc punctiforme by staining with lipophyllic fluorescent dyes. LDs increased in number upon entry into stationary phase and addition of exogenous fructose indicating a role for carbon storage, whereas high-light stress did not increase LD numbers. LD accumulation increased when nitrate was used as the nitrogen source during exponential growth as compared to added ammonia or nitrogen–fixing conditions. Analysis of isolated LDs revealed enrichment of triacylglycerol (TAG), - tochopherol, and C17 alkanes. LD TAG from exponential phase growth contained mainly saturated C16 and C18 fatty acids whereas stationary phase LD TAG had additional unsaturated fatty acids characteristic of whole cells. This is the first characterization of cyanobacterial LD composition and conditions leading to their production. Based upon their abnormally large size and atypical location these structures represent a novel sub-organelle in cyanobacteria. PMID:25135835

  4. Introduction of a synthetic CO₂-fixing photorespiratory bypass into a cyanobacterium.

    PubMed

    Shih, Patrick M; Zarzycki, Jan; Niyogi, Krishna K; Kerfeld, Cheryl A

    2014-04-01

    Global photosynthetic productivity is limited by the enzymatic assimilation of CO2 into organic carbon compounds. Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), the carboxylating enzyme of the Calvin-Benson cycle, poorly discriminates between CO2 and O2, leading to photorespiration and the loss of fixed carbon and nitrogen. With the advent of synthetic biology, it is now feasible to design, synthesize, and introduce biochemical pathways in vivo. We engineered a synthetic photorespiratory bypass based on the 3-hydroxypropionate bi-cycle into the model cyanobacterium, Synechococcus elongatus sp. PCC 7942. The heterologously expressed cycle is designed to function as both a photorespiratory bypass and an additional CO2-fixing pathway, supplementing the Calvin-Benson cycle. We demonstrate the function of all six introduced enzymes and identify bottlenecks to be targeted in subsequent bioengineering. These results have implications for efforts to improve photosynthesis and for the "green" production of high value products of biotechnological interest.

  5. Space-environmental tolerances in a cyanobacterium, Nostoc sp. HK-01

    NASA Astrophysics Data System (ADS)

    Tomita-Yokotani, Kaori; Yokobori, Shin-ichi; Kimura, Shunta; Sato, Seigo; Katoh, Hiroshi; Ajioka, Reiko; Yamagishi, Akihiko; Inoue, Kotomi

    2016-07-01

    We have been investigating the tolerances to space-environments of a cyanobacterium, Nostoc sp. HK-01 (hereafter referred to as HK-01). Dry colonies of HK-01 had high tolerance to dry conditions, but more detailed information about tolerance to high-temperature, UV, gamma-ray and heavy particle beams were not deeply investigated. The obtained dry colonies of HK-01 after exposure to each of the conditions described above were investigated. In all of the tested colonies of HK-01 after exposure, all or some of the cells in the colonies were alive. One of the purposes of space agriculture is growing plants on Mars. In the early stages, of our research, cyanobacteria are introduced on Mars to promote the oxidation of the atmosphere and the formation of soil from Mars's regolith. HK-01 will contribute to each of these factors in the future.

  6. Isolation, purification and characterization of the ATPase complex from the thermophilic cyanobacterium Synechococcus 6716.

    PubMed

    Lubberding, H J; Zimmer, G; van Walraven, H S; Schrickx, J; Kraayenhof, R

    1983-12-01

    The ATPase complex is isolated and purified from membrane vesicles of the thermophilic cyanobacterium Synechococcus 6716 by octyl glucoside and cholic acid by a modification of the procedure for its extraction from spinach chloroplasts. The complex is purified by differential centrifugation and ammonium sulfate precipitation and by gel filtration on Sepharose 6B. The purified fraction, without any phycocyanin contamination, shows ATP hydrolysis activity and Pi/ATP exchange activity of 1564 and 350 nmol X min-1 X mg protein-1, respectively. N,N'-Dicyclohexylcarbodiimide inhibits the ATP hydrolysis activity of this purified fraction. On polyacrylamide gels most typical F1 ATPase polypeptides are identified, but the low-molecular weight polypeptides visible cannot be ascribed to the F0 part of the complex with certainty; non-identified bands around 30 kDa are also present.

  7. Utilization of a terrestrial cyanobacterium, Nostoc sp. HK-01, for space habitation

    NASA Astrophysics Data System (ADS)

    Kimura, Shunta; Tomita-Yokotani, Kaori; Arai, Mayumi; Yamashita, Masamichi; Katoh, Hiroshi; Ajioka, Reiko; Inoue, Kotomi

    2016-07-01

    A terrestrial cyanobacterium, Nostoc sp. HK-01 (hereafter HK-01), has several useful abilities for space habitation; photosynthesis, nitrogen fixation, and space environmental tolerances to vacuum, UV, gamma-ray, heavy particle beam, low and high temperature. Space environmental tolerances are important for transportation to Mars. HK-01 can grow on Martian regolith simulant (MRS) in vitro. Furthermore, HK-01 is useful as food. HK-01 may be utilized as oxygen supply, soil formation and food material for bio-chemical circulation in closed bio-ecosystems, including space habitation such as Mars. HK-01 was adopted as a biological material for the "TANPOPO" mission (JAXA et al.,), because of their high environmental tolerances. The "TANPOPO" mission is performing the space exposure experiments on the Japan Experimental Module (JEM) of the International Space Station (ISS). The results of these experiments will show the ability of HK-01 to survive in space.

  8. Growth and biopigment accumulation of cyanobacterium Spirulina platensis at different light intensities and temperature

    PubMed Central

    Kumar, Manoj; Kulshreshtha, Jyoti; Singh, Gajendra Pal

    2011-01-01

    In order to find out optimum culture condition for algal growth, the effect of light irradiance and temperature on growth rate, biomass composition and pigment production of Spirulina platensis were studied in axenic batch cultures. Growth kinetics of cultures showed a wide range of temperature tolerance from 20 °C to 40 °C. Maximum growth rate, cell production with maximum accumulation of chlorophyll and phycobilliproteins were found at temperature 35 °C and 2,000 lux light intensity. But with further increase in temperature and light intensity, reduction in growth rate was observed. Carotenoid content was found maximum at 3,500 lux. Improvement in the carotenoid content with increase in light intensity is an adaptive mechanism of cyanobacterium S.platensis for photoprotection, could be a good basis for the exploitation of microalgae as a source of biopigments. PMID:24031731

  9. Live Cell Chemical Profiling of Temporal Redox Dynamics in a Photoautotrophic Cyanobacterium

    SciTech Connect

    Sadler, Natalie C.; Melnicki, Matthew R.; Serres, Margrethe H.; Merkley, Eric D.; Chrisler, William B.; Hill, Eric A.; Romine, Margaret F.; Kim, Sangtae; Zink, Erika M.; Datta, Suchitra; Smith, Richard D.; Beliaev, Alex S.; Konopka, Allan; Wright, Aaron T.

    2014-01-01

    Protein reduction-oxidation (redox) modification is an important mechanism that allows microorganisms to sense environmental changes and initiate cellular responses. We have developed a quantitative chemical probe approach for live cell labeling of proteins that are sensitive to redox modifications. We utilize this in vivo strategy to identify 176 proteins undergoing ~5-10 fold dynamic redox change in response to nutrient limitation and subsequent replenishment in the photoautotrophic cyanobacterium, Synechococcus sp. PCC 7002. We detect redox changes in as little as 30 seconds after nutrient perturbation, and oscillations in reduction and oxidation for 60 minutes following the perturbation. Many of the proteins undergoing dynamic redox transformations participate in the major components for the production (photosystems and electron transport chains) or consumption (Calvin-Benson cycle and protein synthesis) of reductant and/or energy in photosynthetic organisms. Thus, our in vivo approach reveals new redox-susceptible proteins, in addition to validating those previously identified in vitro.

  10. Temporal Gene Expression of the Cyanobacterium Arthrospira in Response to Gamma Rays

    PubMed Central

    Badri, Hanène; Monsieurs, Pieter; Coninx, Ilse; Nauts, Robin; Wattiez, Ruddy; Leys, Natalie

    2015-01-01

    The edible cyanobacterium Arthrospira is resistant to ionising radiation. The cellular mechanisms underlying this radiation resistance are, however, still largely unknown. Therefore, additional molecular analysis was performed to investigate how these cells can escape from, protect against, or repair the radiation damage. Arthrospira cells were shortly exposed to different doses of 60Co gamma rays and the dynamic response was investigated by monitoring its gene expression and cell physiology at different time points after irradiation. The results revealed a fast switch from an active growth state to a kind of 'survival modus' during which the cells put photosynthesis, carbon and nitrogen assimilation on hold and activate pathways for cellular protection, detoxification, and repair. The higher the radiation dose, the more pronounced this global emergency response is expressed. Genes repressed during early response, suggested a reduction of photosystem II and I activity and reduced tricarboxylic acid (TCA) and Calvin-Benson-Bassham (CBB) cycles, combined with an activation of the pentose phosphate pathway (PPP). For reactive oxygen species detoxification and restoration of the redox balance in Arthrospira cells, the results suggested a powerful contribution of the antioxidant molecule glutathione. The repair mechanisms of Arthrospira cells that were immediately switched on, involve mainly proteases for damaged protein removal, single strand DNA repair and restriction modification systems, while recA was not induced. Additionally, the exposed cells showed significant increased expression of arh genes, coding for a novel group of protein of unknown function, also seen in our previous irradiation studies. This observation confirms our hypothesis that arh genes are key elements in radiation resistance of Arthrospira, requiring further investigation. This study provides new insights into phasic response and the cellular pathways involved in the radiation resistance of

  11. Temporal Gene Expression of the Cyanobacterium Arthrospira in Response to Gamma Rays.

    PubMed

    Badri, Hanène; Monsieurs, Pieter; Coninx, Ilse; Nauts, Robin; Wattiez, Ruddy; Leys, Natalie

    2015-01-01

    The edible cyanobacterium Arthrospira is resistant to ionising radiation. The cellular mechanisms underlying this radiation resistance are, however, still largely unknown. Therefore, additional molecular analysis was performed to investigate how these cells can escape from, protect against, or repair the radiation damage. Arthrospira cells were shortly exposed to different doses of 60Co gamma rays and the dynamic response was investigated by monitoring its gene expression and cell physiology at different time points after irradiation. The results revealed a fast switch from an active growth state to a kind of 'survival modus' during which the cells put photosynthesis, carbon and nitrogen assimilation on hold and activate pathways for cellular protection, detoxification, and repair. The higher the radiation dose, the more pronounced this global emergency response is expressed. Genes repressed during early response, suggested a reduction of photosystem II and I activity and reduced tricarboxylic acid (TCA) and Calvin-Benson-Bassham (CBB) cycles, combined with an activation of the pentose phosphate pathway (PPP). For reactive oxygen species detoxification and restoration of the redox balance in Arthrospira cells, the results suggested a powerful contribution of the antioxidant molecule glutathione. The repair mechanisms of Arthrospira cells that were immediately switched on, involve mainly proteases for damaged protein removal, single strand DNA repair and restriction modification systems, while recA was not induced. Additionally, the exposed cells showed significant increased expression of arh genes, coding for a novel group of protein of unknown function, also seen in our previous irradiation studies. This observation confirms our hypothesis that arh genes are key elements in radiation resistance of Arthrospira, requiring further investigation. This study provides new insights into phasic response and the cellular pathways involved in the radiation resistance of

  12. Temporal Gene Expression of the Cyanobacterium Arthrospira in Response to Gamma Rays.

    PubMed

    Badri, Hanène; Monsieurs, Pieter; Coninx, Ilse; Nauts, Robin; Wattiez, Ruddy; Leys, Natalie

    2015-01-01

    The edible cyanobacterium Arthrospira is resistant to ionising radiation. The cellular mechanisms underlying this radiation resistance are, however, still largely unknown. Therefore, additional molecular analysis was performed to investigate how these cells can escape from, protect against, or repair the radiation damage. Arthrospira cells were shortly exposed to different doses of 60Co gamma rays and the dynamic response was investigated by monitoring its gene expression and cell physiology at different time points after irradiation. The results revealed a fast switch from an active growth state to a kind of 'survival modus' during which the cells put photosynthesis, carbon and nitrogen assimilation on hold and activate pathways for cellular protection, detoxification, and repair. The higher the radiation dose, the more pronounced this global emergency response is expressed. Genes repressed during early response, suggested a reduction of photosystem II and I activity and reduced tricarboxylic acid (TCA) and Calvin-Benson-Bassham (CBB) cycles, combined with an activation of the pentose phosphate pathway (PPP). For reactive oxygen species detoxification and restoration of the redox balance in Arthrospira cells, the results suggested a powerful contribution of the antioxidant molecule glutathione. The repair mechanisms of Arthrospira cells that were immediately switched on, involve mainly proteases for damaged protein removal, single strand DNA repair and restriction modification systems, while recA was not induced. Additionally, the exposed cells showed significant increased expression of arh genes, coding for a novel group of protein of unknown function, also seen in our previous irradiation studies. This observation confirms our hypothesis that arh genes are key elements in radiation resistance of Arthrospira, requiring further investigation. This study provides new insights into phasic response and the cellular pathways involved in the radiation resistance of

  13. Engineering of photosynthetic mannitol biosynthesis from CO2 in a cyanobacterium.

    PubMed

    Jacobsen, Jacob H; Frigaard, Niels-Ulrik

    2014-01-01

    D-Mannitol (hereafter denoted mannitol) is used in the medical and food industry and is currently produced commercially by chemical hydrogenation of fructose or by extraction from seaweed. Here, the marine cyanobacterium Synechococcus sp. PCC 7002 was genetically modified to photosynthetically produce mannitol from CO2 as the sole carbon source. Two codon-optimized genes, mannitol-1-phosphate dehydrogenase (mtlD) from Escherichia coli and mannitol-1-phosphatase (mlp) from the protozoan chicken parasite Eimeria tenella, in combination encoding a biosynthetic pathway from fructose-6-phosphate to mannitol, were expressed in the cyanobacterium resulting in accumulation of mannitol in the cells and in the culture medium. The mannitol biosynthetic genes were expressed from a single synthetic operon inserted into the cyanobacterial chromosome by homologous recombination. The mannitol biosynthesis operon was constructed using a novel uracil-specific excision reagent (USER)-based polycistronic expression system characterized by ligase-independent, directional cloning of the protein-encoding genes such that the insertion site was regenerated after each cloning step. Genetic inactivation of glycogen biosynthesis increased the yield of mannitol presumably by redirecting the metabolic flux to mannitol under conditions where glycogen normally accumulates. A total mannitol yield equivalent to 10% of cell dry weight was obtained in cell cultures synthesizing glycogen while the yield increased to 32% of cell dry weight in cell cultures deficient in glycogen synthesis; in both cases about 75% of the mannitol was released from the cells into the culture medium by an unknown mechanism. The highest productivity was obtained in a glycogen synthase deficient culture that after 12 days showed a mannitol concentration of 1.1 g mannitol L(-1) and a production rate of 0.15 g mannitol L(-1) day(-1). This system may be useful for biosynthesis of valuable sugars and sugar derivatives from CO2

  14. High-yield production of extracellular type-I cellulose by the cyanobacterium Synechococcus sp. PCC 7002.

    PubMed

    Zhao, Chi; Li, Zhongkui; Li, Tao; Zhang, Yingjiao; Bryant, Donald A; Zhao, Jindong

    2015-01-01

    Cellulose synthase, encoded by the cesA gene, is responsible for the synthesis of cellulose in nature. We show that the cell wall of the cyanobacterium Synechococcus sp. PCC 7002 naturally contains cellulose. Cellulose occurs as a possibly laminated layer between the inner and outer membrane, as well as being an important component of the extracellular glycocalyx in this cyanobacterium. Overexpression of six genes, cmc-ccp-cesAB-cesC-cesD-bgl, from Gluconacetobacter xylinus in Synechococcus sp. PCC 7002 resulted in very high-yield production of extracellular type-I cellulose. High-level cellulose production only occurred when the native cesA gene was inactivated and when cells were grown at low salinity. This system provides a method for the production of lignin-free cellulose from sunlight and CO2 for biofuel production and other biotechnological applications. PMID:27462405

  15. High-yield production of extracellular type-I cellulose by the cyanobacterium Synechococcus sp. PCC 7002.

    PubMed

    Zhao, Chi; Li, Zhongkui; Li, Tao; Zhang, Yingjiao; Bryant, Donald A; Zhao, Jindong

    2015-01-01

    Cellulose synthase, encoded by the cesA gene, is responsible for the synthesis of cellulose in nature. We show that the cell wall of the cyanobacterium Synechococcus sp. PCC 7002 naturally contains cellulose. Cellulose occurs as a possibly laminated layer between the inner and outer membrane, as well as being an important component of the extracellular glycocalyx in this cyanobacterium. Overexpression of six genes, cmc-ccp-cesAB-cesC-cesD-bgl, from Gluconacetobacter xylinus in Synechococcus sp. PCC 7002 resulted in very high-yield production of extracellular type-I cellulose. High-level cellulose production only occurred when the native cesA gene was inactivated and when cells were grown at low salinity. This system provides a method for the production of lignin-free cellulose from sunlight and CO2 for biofuel production and other biotechnological applications.

  16. High-yield production of extracellular type-I cellulose by the cyanobacterium Synechococcus sp. PCC 7002

    PubMed Central

    Zhao, Chi; Li, Zhongkui; Li, Tao; Zhang, Yingjiao; Bryant, Donald A; Zhao, Jindong

    2015-01-01

    Cellulose synthase, encoded by the cesA gene, is responsible for the synthesis of cellulose in nature. We show that the cell wall of the cyanobacterium Synechococcus sp. PCC 7002 naturally contains cellulose. Cellulose occurs as a possibly laminated layer between the inner and outer membrane, as well as being an important component of the extracellular glycocalyx in this cyanobacterium. Overexpression of six genes, cmc–ccp–cesAB–cesC–cesD–bgl, from Gluconacetobacter xylinus in Synechococcus sp. PCC 7002 resulted in very high-yield production of extracellular type-I cellulose. High-level cellulose production only occurred when the native cesA gene was inactivated and when cells were grown at low salinity. This system provides a method for the production of lignin-free cellulose from sunlight and CO2 for biofuel production and other biotechnological applications. PMID:27462405

  17. Draft Genome Sequence of the N2-Fixing Cyanobacterium Nostoc piscinale CENA21, Isolated from the Brazilian Amazon Floodplain.

    PubMed

    Leão, Tiago; Guimarães, Pedro Ivo; de Melo, Aline Grasielle Costa; Ramos, Rommel Thiago Jucá; Leão, Pedro Nuno; Silva, Artur; Fiore, Marli Fatima; Schneider, Maria Paula Cruz

    2016-03-31

    We announce here the draft genome sequence ofNostoc piscinaleCENA21, a diazotrophic heterocyst-forming cyanobacterium isolated from the Solimões River, Amazon Basin, Brazil. It consists of one circular chromosome scaffold with 11 contigs and total size of 7,094,556 bp. Secondary metabolite annotations indicate a good source for the discovery of novel natural products.

  18. Draft Genome Sequence of the N2-Fixing Cyanobacterium Nostoc piscinale CENA21, Isolated from the Brazilian Amazon Floodplain.

    PubMed

    Leão, Tiago; Guimarães, Pedro Ivo; de Melo, Aline Grasielle Costa; Ramos, Rommel Thiago Jucá; Leão, Pedro Nuno; Silva, Artur; Fiore, Marli Fatima; Schneider, Maria Paula Cruz

    2016-01-01

    We announce here the draft genome sequence ofNostoc piscinaleCENA21, a diazotrophic heterocyst-forming cyanobacterium isolated from the Solimões River, Amazon Basin, Brazil. It consists of one circular chromosome scaffold with 11 contigs and total size of 7,094,556 bp. Secondary metabolite annotations indicate a good source for the discovery of novel natural products. PMID:27034496

  19. Draft Genome Sequence of the N2-Fixing Cyanobacterium Nostoc piscinale CENA21, Isolated from the Brazilian Amazon Floodplain

    PubMed Central

    Guimarães, Pedro Ivo; de Melo, Aline Grasielle Costa; Ramos, Rommel Thiago Jucá; Leão, Pedro Nuno; Silva, Artur; Fiore, Marli Fatima; Schneider, Maria Paula Cruz

    2016-01-01

    We announce here the draft genome sequence of Nostoc piscinale CENA21, a diazotrophic heterocyst-forming cyanobacterium isolated from the Solimões River, Amazon Basin, Brazil. It consists of one circular chromosome scaffold with 11 contigs and total size of 7,094,556 bp. Secondary metabolite annotations indicate a good source for the discovery of novel natural products. PMID:27034496

  20. Draft Genome Assembly of the Bloom-Forming Cyanobacterium Nodularia spumigena Strain CENA596 in Shrimp Production Ponds

    PubMed Central

    Popin, Rafael Vicentini; Rigonato, Janaina; Abreu, Vinicius Augusto Carvalho; Andreote, Ana Paula Dini; Silveira, Savênia Bonoto; Odebrecht, Clarisse

    2016-01-01

    We report here the draft genome assembly of the brackish cyanobacterium Nodularia spumigena strain CENA596 isolated from a shrimp production pond in Rio Grande do Sul, Brazil. The draft genome consists of 291 contigs with a total size of 5,189,679 bp. Secondary metabolite annotations resulted in several predicted gene clusters, including those responsible for encoding the hepatotoxin nodularin. PMID:27284148

  1. Effect of hydration and dehydration on initiation and dynamics of some physiological reactions in desiccation tolerant cyanobacterium Scytonema geitleri.

    PubMed

    Tiwari, B S; Tripathi, S N

    1998-06-01

    The effect of hydration and dehydration has been studied on extent and recovery of some metabolic reactions in desiccation tolerant terrestrial cyanobacterium Scytonema geitleri. The results show that the energy transducing reactions like photochemical reactions of photosynthesis recover first, followed by increase in ATP pool size. During later phase of hydration, appearance of energy consuming processes such as CO2 fixation and nitrogen fixation have been observed. Sensitivity of reactions during dehydration followed the pattern reverse to recovery processes. PMID:9803667

  2. Isolation and structure determination of obyanamide, a novel cytotoxic cyclic depsipeptide from the marine cyanobacterium Lyngbya confervoides.

    PubMed

    Williams, Philip G; Yoshida, Wesley Y; Moore, Richard E; Paul, Valerie J

    2002-01-01

    Obyanamide (1) was isolated from a variety of the marine cyanobacterium Lyngbya confervoides collected in Saipan, Commonwealth of the Northern Mariana Islands. Gross structure elucidation of this novel cyclic depsipeptide relied on extensive application of 2D NMR techniques. The absolute stereochemistry was deduced by chiral chromatography of the hydrolysis products and comparison with authentic and synthetic standards. Obyanamide (1) was cytotoxic against KB cells with an IC(50) of 0.58 microg/mL.

  3. Crossbyanols A-D, toxic brominated polyphenyl ethers from the Hawai'ian bloom-forming Cyanobacterium Leptolyngbya crossbyana.

    PubMed

    Choi, Hyukjae; Engene, Niclas; Smith, Jennifer E; Preskitt, Linda B; Gerwick, William H

    2010-04-23

    Periodically, the marine cyanobacterium Leptolyngbya crossbyana forms extensive blooms on Hawai'ian coral reefs and results in significant damage to the subtending corals. Additionally, corals near mats of this cyanobacterium, but not directly overgrown, have been observed to undergo bleaching. Therefore, samples of this cyanobacterium were chemically investigated for bioactive secondary metabolites that might underlie this toxicity phenomenon. (1)H NMR spectroscopy-guided fractionation led to the isolation of four heptabrominated polyphenolic ethers, crossbyanols A-D (1-4). Structure elucidation of these compounds was made challenging by their very low proton to carbon (H/C) ratio, but was completed by combining standard NMR and MS data with 2 Hz-optimized HMBC data. Derivatization of crossbyanol A as the diacetate assisted in the assignment of its structure. Crossbyanol B (2) showed antibiotic activity with an MIC value of 2.0-3.9 microg/mL against methicillin-resistant Staphylococcus aureus (MRSA) and relatively potent brine shrimp toxicity (IC(50) 2.8 ppm).

  4. Responses of a rice-field cyanobacterium Anabaena siamensis TISTR-8012 upon exposure to PAR and UV radiation.

    PubMed

    Rastogi, Rajesh P; Incharoensakdi, Aran; Madamwar, Datta

    2014-10-15

    The effects of PAR and UV radiation and subsequent responses of certain antioxidant enzymatic and non-enzymatic defense systems were studied in a rice field cyanobacterium Anabaena siamensis TISTR 8012. UV radiation resulted in a decline in growth accompanied by a decrease in chlorophyll a and photosynthetic efficiency. Exposure of cells to UV radiation significantly affected the differentiation of vegetative cells into heterocysts or akinetes. UV-B radiation caused the fragmentation of the cyanobacterial filaments conceivably due to the observed oxidative stress. A significant increase of reactive oxygen species in vivo and DNA strand breaks were observed in UV-B exposed cells followed by those under UV-A and PAR radiation, respectively. The UV-induced oxidative damage was alleviated due to an induction of antioxidant enzymatic/non-enzymatic defense systems. In response to UV irradiation, the studied cyanobacterium exhibited a significant increase in antioxidative enzyme activities of superoxide dismutase, catalase and peroxidase. Moreover, the cyanobacterium also synthesized some UV-absorbing/screening substances. HPLC coupled with a PDA detector revealed the presence of three compounds with UV-absorption maxima at 326, 331 and 345 nm. The induction of the biosynthesis of these UV-absorbing compounds was found under both PAR and UV radiation, thus suggesting their possible function as an active photoprotectant.

  5. Effects of Cylindrospermopsin Producing Cyanobacterium and Its Crude Extracts on a Benthic Green Alga-Competition or Allelopathy?

    PubMed

    B-Béres, Viktória; Vasas, Gábor; Dobronoki, Dalma; Gonda, Sándor; Nagy, Sándor Alex; Bácsi, István

    2015-11-01

    Cylindrospermopsin (CYN) is a toxic secondary metabolite produced by filamentous cyanobacteria which could work as an allelopathic substance, although its ecological role in cyanobacterial-algal assemblages is mostly unclear. The competition between the CYN-producing cyanobacterium Chrysosporum (Aphanizomenon) ovalisporum, and the benthic green alga Chlorococcum sp. was investigated in mixed cultures, and the effects of CYN-containing cyanobacterial crude extract on Chlorococcum sp. were tested by treatments with crude extracts containing total cell debris, and with cell debris free crude extracts, modelling the collapse of a cyanobacterial water bloom. The growth inhibition of Chlorococcum sp. increased with the increasing ratio of the cyanobacterium in mixed cultures (inhibition ranged from 26% to 87% compared to control). Interestingly, inhibition of the cyanobacterium growth also occurred in mixed cultures, and it was more pronounced than it was expected. The inhibitory effects of cyanobacterial crude extracts on Chlorococcum cultures were concentration-dependent. The presence of C. ovalisporum in mixed cultures did not cause significant differences in nutrient content compared to Chlorococcum control culture, so the growth inhibition of the green alga could be linked to the presence of CYN and/or other bioactive compounds. PMID:26528991

  6. Effects of Cylindrospermopsin Producing Cyanobacterium and Its Crude Extracts on a Benthic Green Alga—Competition or Allelopathy?

    PubMed Central

    B-Béres, Viktória; Vasas, Gábor; Dobronoki, Dalma; Gonda, Sándor; Nagy, Sándor Alex; Bácsi, István

    2015-01-01

    Cylindrospermopsin (CYN) is a toxic secondary metabolite produced by filamentous cyanobacteria which could work as an allelopathic substance, although its ecological role in cyanobacterial-algal assemblages is mostly unclear. The competition between the CYN-producing cyanobacterium Chrysosporum (Aphanizomenon) ovalisporum, and the benthic green alga Chlorococcum sp. was investigated in mixed cultures, and the effects of CYN-containing cyanobacterial crude extract on Chlorococcum sp. were tested by treatments with crude extracts containing total cell debris, and with cell debris free crude extracts, modelling the collapse of a cyanobacterial water bloom. The growth inhibition of Chlorococcum sp. increased with the increasing ratio of the cyanobacterium in mixed cultures (inhibition ranged from 26% to 87% compared to control). Interestingly, inhibition of the cyanobacterium growth also occurred in mixed cultures, and it was more pronounced than it was expected. The inhibitory effects of cyanobacterial crude extracts on Chlorococcum cultures were concentration-dependent. The presence of C. ovalisporum in mixed cultures did not cause significant differences in nutrient content compared to Chlorococcum control culture, so the growth inhibition of the green alga could be linked to the presence of CYN and/or other bioactive compounds. PMID:26528991

  7. Dispensability of a sulfolipid for photoautotrophic cell growth and photosynthesis in a marine cyanobacterium, Synechococcus sp. PCC 7002.

    PubMed

    Sato, Norihiro; Kamimura, Ryohei; Tsuzuki, Mikio

    2016-09-01

    Sulfoquinovosyl diacylglycerol, which mainly comprises thylakoid membranes in oxygenic photosynthetic organisms, plays species-dependent roles in freshwater microbes. In this study, a sulfoquinovosyl-diacylglycerol deficient mutant was generated in a cyanobacterium, Synechococcus sp. PCC 7002, for the first time among marine microbes to gain more insight into its physiological significance. The mutation had little deleterious impact on photoautotrophic cell growth, and functional and structural properties of the photosystem II complex. These findings were similar to previous observations for a freshwater cyanobacterium, Synechococcus elongatus PCC 7942, but were distinct from those for another freshwater cyanobacterium, Synechocystis sp. PCC 6803, and a green alga, Chlamydomonas reinhardtii, both of which require sulfoquinovosyl diacylglycerol for cell growth and/or photosystem II. Therefore, the functionality of PSII to dispense with sulfoquinovosyl diacylglycerol in Synechococcus sp. PCC 7002, similar to that in Synechococcus elongatus PCC 7942, seemed to have been excluded from the evolution of the PSII complex from cyanobacteria to green algal chloroplasts. Meanwhile, sulfoquinovosyl diacylglycerol was found to contribute to photoheterotrophic growth of Synechococcus sp. PCC 7002, which revealed a novel species-dependent strategy for utilizing SQDG in physiological processes. PMID:27372425

  8. Lab-Scale Study of the Calcium Carbonate Dissolution and Deposition by Marine Cyanobacterium Phormidium subcapitatum

    NASA Technical Reports Server (NTRS)

    Karakis, S. G.; Dragoeva, E. G.; Lavrenyuk, T. I.; Rogochiy, A.; Gerasimenko, L. M.; McKay, D. S.; Brown, I. I.

    2006-01-01

    Suggestions that calcification in marine organisms changes in response to global variations in seawater chemistry continue to be advanced (Wilkinson, 1979; Degens et al. 1985; Kazmierczak et al. 1986; R. Riding 1992). However, the effect of [Na+] on calcification in marine cyanobacteria has not been discussed in detail although [Na+] fluctuations reflect both temperature and sea-level fluctuations. The goal of these lab-scale studies therefore was to study the effect of environmental pH and [Na+] on CaCO3 deposition and dissolution by marine cyanobacterium Phormidium subcapitatum. Marine cyanobacterium P. subcapitatum has been cultivated in ASN-III medium. [Ca2+] fluctuations were monitored with Ca(2+) probe. Na(+) concentrations were determined by the initial solution chemistry. It was found that the balance between CaCO3 dissolution and precipitation induced by P. subcapitatum grown in neutral ASN III medium is very close to zero. No CaCO3 precipitation induced by cyanobacterial growth occurred. Growth of P. subcapitatum in alkaline ASN III medium, however, was accompanied by significant oscillations in free Ca(2+) concentration within a Na(+) concentration range of 50-400 mM. Calcium carbonate precipitation occurred during the log phase of P. subcapitatum growth while carbonate dissolution was typical for the stationary phase of P. subcapitatum growth. The highest CaCO3 deposition was observed in the range of Na(+) concentrations between 200-400 mM. Alkaline pH also induced the clamping of P. subcapitatum filaments, which appeared to have a strong affinity to envelop particles of chemically deposited CaCO3 followed by enlargement of those particles size. EDS analysis revealed the presence of Mg-rich carbonate (or magnesium calcite) in the solution containing 10-100 mM Na(+); calcite in the solution containing 200 mM Na(+); and aragonite in the solution containing with 400 mM Na(+). Typical present-day seawater contains xxmM Na(+). Early (Archean) seawater was

  9. Molecular exploration of the highly radiation resistant cyanobacterium Arthrospira sp. PCC 8005

    NASA Astrophysics Data System (ADS)

    Badri, Hanène; Leys, Natalie; Wattiez, Ruddy

    Arthrospira (Spirulina) is a photosynthetic cyanobacterium able to use sunlight to release oxygen from water and remove carbon dioxide and nitrate from water. In addition, it is suited for human consumption (edible). For these traits, the cyanobacterium Arthrospira sp. PCC 8005 was selected by the European Space Agency (ESA) as part of the life support system MELiSSA for recycling oxygen, water, and food during future long-haul space missions. However, during such extended missions, Arthrospira sp. PCC 8005 will be exposed to continuous artificial illumination and harmful cosmic radiation. The aim of this study was to investigate how Arthrospira will react and behave when exposed to such stress environment. The cyanobacterium Arthrospira sp. PCC 8005 was exposed to high gamma rays doses in order to unravel in details the response of this bacterium following such stress. Test results showed that after acute exposure to high doses of 60Co gamma radiation upto 3200 Gy, Arthrospira filaments were still able to restart photosynthesis and proliferate normally. Doses above 3200 Gy, did have a detrimental effect on the cells, and delayed post-irradiation proliferation. The photosystem activity, measured as the PSII quantum yield immediately after irradiation, decreased significantly at radiation doses above 3200 Gy. Likewise through pigment content analysis a significant decrease in phycocyanin was observed following exposure to 3200 Gy. The high tolerance of this bacterium to 60Co gamma rays (i.e. ca. 1000x more resistant than human cells for example) raised our interest to investigate in details the cellular and molecular mechanisms behind this amazing resistance. Optimised DNA, RNA and protein extraction methods and a new microarray chip specific for Arthrospira sp. PCC 8005 were developed to identify the global cellular and molecular response following exposure to 3200 Gy and 5000 Gy A total of 15,29 % and 30,18 % genes were found differentially expressed in RNA

  10. Classical and Alternative Activation of Cyanobacterium Oscillatoria sp. Lipopolysaccharide-Treated Rat Microglia in vitro.

    PubMed

    Mayer, Alejandro M S; Murphy, Joseph; MacAdam, David; Osterbauer, Christopher; Baseer, Imaan; Hall, Mary L; Feher, Domonkos; Williams, Phillip

    2016-02-01

    The purpose of this investigation was to test the hypothesis that an in vitro exposure to cyanobacterium Oscillatoria sp. Lipopolysaccharide (LPS) might result in classical and alternative activation of rat neonatal microglia. Using Escherichia coli LPS-primed microglia as a positive control, this study revealed that treatment of rat microglia with Oscillatoria sp. LPS for 17 h in vitro resulted in both classical and alternative activation as well as concomitant pro-inflammatory and anti-inflammatory mediator release, in a concentration-dependent manner: (1) treatment with 0.1-10 000 ng/ml Oscillatoria sp. LPS resulted in minimal lactic dehydrogenase (LDH) release, induced concentration-dependent and statistically significant O2 (-) generation, matrix metalloproteinase-9 (MMP-9) release, generation of the cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), and the chemokines macrophage inflammatory protein-2 (MIP-2/CXCL2), interferon γ-induced protein 10 kDa (IP-10/CXCL-10), (MIP-1α/CCL3), monocyte chemotactic protein-1 (MCP-1/CCL2), regulated on activation, normal T cell expressed and secreted (RANTES/CCL5), and the alternative activation cytokine IL-10; (3) in contrast, treatment with 100 000 ng/ml Oscillatoria sp. LPS appeared to damage the microglia cell membrane, because it resulted in minimal O2 (-) generation, statistically significant LDH release, and a decrease in the generation of all the cytokines and chemokines investigated, with the exception of IL-1α and cytokine-induced neutrophil chemoattractant 1 (CINC-1/CXCL1) generation, which was increased. Thus, our results provide experimental support for our working hypothesis, namely that Oscillatoria sp. LPS induces classical and alternative activation of rat brain microglia in vitro in a concentration-dependent manner, namely 0.1-10 000 ng/ml Oscillatoria sp. LPS, when microglia cells were shown to be viable. Furthermore, should cyanobacterium Oscillatoria sp. LPS gain

  11. [Growth and metabolite production of the marine cyanobacterium Synechococcus sp. (Chroococcales) in function to irradiance].

    PubMed

    Rosales-Loaiza, Néstor; Guevara, Miguel; Lodeiros, César; Morales, Ever

    2008-06-01

    Changes in salinity, temperature and irradiance during wet and dry seasons have induced metabolic versatility in cyanobacteria from saline environments. Cyanobacteria from these environments have biotechnological potential for the production of metabolites with pharmaceutical and industrial interest. We studied the growth, dry mass and metabolite production of the cyanobacterium Synechococcus sp. MOF-03 in function of irradiance (78, 156 and 234 micromol q m(-2) s(-1)). All batch cultures were maintained by triplicate in constant aeration, 12:12 h photoperiod, 30 +/- 2 degrees C and 35% per hundred. Maximum values of protein, carbohydrates and lipids, of 530.19 +/- 11.16, 408.94 +/- 4.27 and 56.20 +/- 1.17 microg ml(-1), respectively, were achieved at 78 micromol q m(-2) s(-1). Pigments, analyzed by HPLC, showed maximum values at 78 micromol q m(-2) s(-1) for chlorophyll a with 7.72 +/- 0.16 microg ml(-1), and at 234 micromol q m(-2) s(-1) for beta-carotene and zeaxanthin with 0.70 +/- 0.01 and 0.67 +/- 0.05 microg ml(-1). Chlorophyll a:beta-carotene ratio decreased from 17.15 to 6.91 at 78 and 234 micromol q m(-2) s(-'1); whereas beta-carotene:zeaxanthin ratio showed no changes between 78 and 156 micromol q m(-2) s(-1), around 1.21, and decreased at 234 micromol q m(-2) s(-1), to 1.04. Also, this cyanobacterium produced the greatest cell density and dry mass at 156 micromol q m(-2) s(-1), with 406.13 +/- 21.74 x l0(6) cell ml(-1) and 1.49 +/- 0.11 mg ml(-1), respectively. Exopolysaccharide production was stable between 156 y 234 micromol q m(-2) s(-1), around 110 microg ml(-1). This Synechococcus strain shows a great potential for the production of enriched biomass with high commercial value metabolites.

  12. ABC Transporter Required for Intercellular Transfer of Developmental Signals in a Heterocystous Cyanobacterium

    PubMed Central

    Videau, Patrick; Rivers, Orion S.; Higa, Kelly C.

    2015-01-01

    ABSTRACT In the filamentous cyanobacterium Anabaena, patS and hetN encode peptide-derived signals with many of the properties of morphogens. These signals regulate the formation of a periodic pattern of heterocysts by lateral inhibition of differentiation. Here we show that intercellular transfer of the patS- and hetN-dependent developmental signals from heterocysts to vegetative cells requires HetC, a predicted ATP-binding cassette transporter (ABC transporter). Relative to the wild type, in a hetC mutant differentiation resulted in a reduced number of heterocysts that were incapable of nitrogen fixation, but deletion of patS or hetN restored heterocyst number and function in a hetC background. These epistasis results suggest that HetC is necessary for conferring self-immunity to the inhibitors on differentiating cells. Nine hours after induction of differentiation, HetC was required for neither induction of transcription of patS nor intercellular transfer of the patS-encoded signal to neighboring cells. Conversely, in strains lacking HetC, the patS- and hetN-encoded signals were not transferred from heterocyst cells to adjacent vegetative cells. The results support a model in which the patS-dependent signal is initially transferred between vegetative cells in a HetC-independent fashion, but some time before morphological differentiation of heterocysts is complete, transfer of both signals transitions to a HetC-dependent process. IMPORTANCE How chemical cues that regulate pattern formation in multicellular organisms move from one cell to another is a central question in developmental biology. In this study, we show that an ABC transporter, HetC, is necessary for transport of two developmental signals between different types of cells in a filamentous cyanobacterium. ABC transporters are found in organisms as diverse as bacteria and humans and, as the name implies, are often involved in the transport of molecules across a cellular membrane. The activity of HetC was

  13. Evidence for paralytic shellfish poisons in the freshwater cyanobacterium Lyngbya wollei (Farlow ex Gomont) comb. nov.

    PubMed

    Carmichael, W W; Evans, W R; Yin, Q Q; Bell, P; Moczydlowski, E

    1997-08-01

    Lyngbya wollei (Farlow ex Gomont) comb. nov., a perennial mat-forming filamentous cyanobacterium prevalent in lakes and reservoirs of the southeastern United States, was found to produce a potent, acutely lethal neurotoxin when tested in the mouse bioassay. Signs of poisoning were similar to those of paralytic shellfish poisoning. As part of the Tennessee Valley Authority master plan for Guntersville Reservoir, the mat-forming filamentous cyanobacterium L. wollei, a species that had recently invaded from other areas of the southern United States, was studied to determine if it could produce any of the known cyanotoxins. Of the 91 field samples collected at 10 locations at Guntersville Reservoir, Ala., on the Tennessee River, over a 3-year period, 72.5% were toxic. The minimum 100% lethal doses of the toxic samples ranged from 150 to 1,500 mg kg of lyophilized L. wollei cells-1, with the majority of samples being toxic at 500 mg kg-1. Samples bioassayed for paralytic shellfish toxins by the Association of Official Analytical Chemists method exhibited saxitoxin equivalents ranging from 0 to 58 micrograms g (dry weight)-1. Characteristics of the neurotoxic compound(s), such as the lack of adsorption by C18 solid-phase extraction columns, the short retention times on C18 high-performance liquid chromatography (HPLC) columns, the interaction of the neurotoxins with saxiphilin (a soluble saxitoxin-binding protein), and external blockage of voltage-sensitive sodium channels, led to our discovery that this neurotoxin(s) is related to the saxitoxins, the compounds responsible for paralytic shellfish poisonings. The major saxitoxin compounds thus far identified by comparison of HPLC fluorescence retention times are decarbamoyl gonyautoxins 2 and 3. There was no evidence of paralytic shellfish poison C toxins being produced by L. wollei. Fifty field samples were placed in unialgal culture and grown under defined culture conditions. Toxicity and signs of poisoning for these

  14. Anilofos Tolerance and Its Mineralization by the Cyanobacterium Synechocystis sp. Strain PUPCCC 64

    PubMed Central

    Singh, D. P.; Khattar, J. I. S.; Kaur, Mandeep; Kaur, Gurdeep; Gupta, Meenu; Singh, Yadvinder

    2013-01-01

    This study deals with anilofos tolerance and its mineralization by the common rice field cyanobacterium Synechocystis sp. strain PUPCCC 64. The organism tolerated anilofos up to 25 mg L−1. The herbicide caused inhibitory effects on photosynthetic pigments of the test organism in a dose-dependent manner. The organism exhibited 60, 89, 96, 85 and 79% decrease in chlorophyll a, carotenoids, phycocyanin, allophycocyanin and phycoerythrin, respectively, in 20 mg L−1 anilofos on day six. Activities of superoxide dismutase, catalase and peroxidase increased by 1.04 to 1.80 times over control cultures in presence of 20 mg L−1 anilofos. Glutathione content decreased by 26% while proline content was unaffected by 20 mg L−1 anilofos. The test organism showed intracellular uptake and metabolized the herbicide. Uptake of herbicide by test organism was fast during initial six hours followed by slow uptake until 120 hours. The organism exhibited maximum anilofos removal at 100 mg protein L−1, pH 8.0 and 30°C. Its growth in phosphate deficient basal medium in the presence of anilofos (2.5 mg L−1) indicated that herbicide was used by the strain PUPCCC 64 as a source of phosphate. PMID:23382844

  15. A Novel Epiphytic Chlorophyll d-containing Cyanobacterium Isolated from a Mangrove-associated Red Alga.

    PubMed

    Larkum, Anthony W D; Chen, Min; Li, Yaqiong; Schliep, Martin; Trampe, Erik; West, John; Salih, Anya; Kühl, Michael

    2012-12-01

    A new habitat and a new chlorophyll (Chl) d-containing cyanobacterium belonging to the genus Acaryochloris are reported in this study. Hyperspectral microscopy showed the presence of Chl d-containing microorganisms in epiphytic biofilms on a red alga (Gelidium caulacantheum) colonizing the pneumato-phores of a temperate mangrove (Avicennia marina). The presence of Chl d was further proven by high performance liquid chromatography (HPLC)-based pigment analysis and by confocal imaging of cultured cells. Enrichment of mangrove biofilm samples under near-infrared radiation (NIR) yielded the new Acaryochloris sp. MPGRS1, which was closely related in terms of 16S rRNA gene sequence to an isolate from the hypertrophic Salton Sea, USA. The new isolate used Chl d as its major photopigment; Chl d and Chl a contents were ~98% and 1%-2% of total cellular chlorophyll, respectively. These findings expand the variety of ecological niches known to harbor Chl d-containing cyanobacteria and support our working hypothesis that such oxyphototrophs may be ubiquitous in habitats depleted of visible light, but with sufficient NIR exposure. PMID:27009985

  16. Nostopeptolide plays a governing role during cellular differentiation of the symbiotic cyanobacterium Nostoc punctiforme.

    PubMed

    Liaimer, Anton; Helfrich, Eric J N; Hinrichs, Katrin; Guljamow, Arthur; Ishida, Keishi; Hertweck, Christian; Dittmann, Elke

    2015-02-10

    Nostoc punctiforme is a versatile cyanobacterium that can live either independently or in symbiosis with plants from distinct taxa. Chemical cues from plants and N. punctiforme were shown to stimulate or repress, respectively, the differentiation of infectious motile filaments known as hormogonia. We have used a polyketide synthase mutant that accumulates an elevated amount of hormogonia as a tool to understand the effect of secondary metabolites on cellular differentiation of N. punctiforme. Applying MALDI imaging to illustrate the reprogramming of the secondary metabolome, nostopeptolides were identified as the predominant difference in the pks2(-) mutant secretome. Subsequent differentiation assays and visualization of cell-type-specific expression of nostopeptolides via a transcriptional reporter strain provided evidence for a multifaceted role of nostopeptolides, either as an autogenic hormogonium-repressing factor or as a chemoattractant, depending on its extracellular concentration. Although nostopeptolide is constitutively expressed in the free-living state, secreted levels dynamically change before, during, and after the hormogonium differentiation phase. The metabolite was found to be strictly down-regulated in symbiosis with Gunnera manicata and Blasia pusilla, whereas other metabolites are up-regulated, as demonstrated via MALDI imaging, suggesting plants modulate the fine-balanced cross-talk network of secondary metabolites within N. punctiforme.

  17. Acyl-acyl-carrier protein: lysomonogalactosyldiacylglycerol acyltransferase from the cyanobacterium Anabaena variabilis.

    PubMed

    Chen, H H; Wickrema, A; Jaworski, J G

    1988-12-16

    Membranes isolated from the cyanobacterium, Anabaena variabilis, and washed free of soluble endogenous constituents, were capable of catalyzing the direct transfer of the acyl group from acyl-acyl-carrier protein to an endogenous lysomonogalactosyldiacylglycerol to form monogalactosyldiacylglycerol. Other glycolipids including monoglucosyldiacylglycerol and digalactosyldiacylglycerol were not products of this reaction. The transfer was not dependent on any added cofactors. Palmitoyl-, stearoyl- and oleoyl-acyl-carrier protein were approximately equally active as substrates. Transfer was exclusively to the C-1 of the glycerol, as demonstrated by hydrolysis of all incorporated acyl groups by the lipase from Rhizopus arrhizus delamar. In addition to the single galactolipid, a second minor reaction product was free fatty acid, presumably due to hydrolysis of the acyl-acyl-carrier protein. Using a double-labelled [14C]acyl-[14C]acyl-carrier protein, the reaction was demonstrated to be a transfer reaction, rather than a simple exchange of acyl groups with endogenous monogalactosyldiacylglycerol. The transfer reaction mechanism was also confirmed by increasing activity with the addition of liposomes of lysomonogalactosyldiacylglycerol.

  18. Purification and characterization of alanine dehydrogenase from a cyanobacterium, Phormidium lapideum.

    PubMed

    Sawa, Y; Tani, M; Murata, K; Shibata, H; Ochiai, H

    1994-11-01

    Alanine dehydrogenase (AlaDH) was purified to homogeneity from cell-free extracts of a non-N2-fixing filamentous cyanobacterium, Phormidium lapideum. The molecular mass of the native enzyme was 240 kDa, and SDS-PAGE revealed a minimum molecular mass of 41 kDa, suggesting a six-subunit structure. The NH2 terminal amino acid residues of the purified AlaDH revealed marked similarity with that of other AlaDHs. The enzyme was highly specific for L-alanine and NAD+, but showed relatively low amino-acceptor specificity. The pH optimum was 8.4 for reductive amination of pyruvate and 9.2 for oxidative deamination of L-alanine. The Km values were 5.0 mM for L-alanine and 0.04 mM for NAD+, 0.33 mM for pyruvate, 60.6 mM for NH4+ (pH 8.7), and 0.02 mM for NADH. Various L-amino acids including alanine, serine, threonine, and aromatic amino acids, inhibited the aminating reaction. The enzyme was inactivated upon incubation with pyridoxal 5'-phosphate (PLP) followed by reduction with sodium borohydride. The copresence of NADH and pyruvate largely protected the enzyme against the inactivation by PLP. PMID:7896761

  19. Sublethal detergent concentrations increase metabolization of recalcitrant polyphosphonates by the cyanobacterium Spirulina platensis.

    PubMed

    Forlani, Giuseppe; Bertazzini, Michele; Giberti, Samuele; Wieczorek, Dorota; Kafarski, Paweł; Lipok, Jacek

    2013-05-01

    As a consequence of increasing industrial applications, thousand tons of polyphosphonates are introduced every year into the environment. The inherent stability of the C-P bond results in a prolonged half-life. Moreover, low uptake rates limit further their microbial metabolization. To assess whether low detergent concentrations were able to increase polyphosphonate utilization by the cyanobacterium Spirulina platensis, tolerance limits to the exposure to various detergents were determined by measuring the growth rate in the presence of graded levels below the critical micellar concentration. Then, the amount of hexamethylenediamine-N,N,N',N'-tetrakis(methylphosphonic acid) that is metabolized in the absence or in the presence of sublethal detergent concentrations was quantified by (31)P NMR analysis on either P-starved or P-fed cyanobacterial cultures. The strain tolerated the presence of detergents in the order: nonionic > anionic > cationic. When added to the culture medium at the highest concentrations showing no detrimental effects upon cell viability, detergents either improved or decreased polyphosphonate utilization, the anionic sodium dodecyl sulfate being the most beneficial. Metabolization was not lower in P-fed cells--a result that strengthens the possibility of using, in the future, this strain for bioremediation purposes. PMID:23089958

  20. Engineered xylose utilization enhances bio-products productivity in the cyanobacterium Synechocystis sp. PCC 6803

    SciTech Connect

    Lee, Tai-Chi; Xiong, Wei; Paddock, Troy; Carrieri, Damian; Chang, Ing-Feng; Chiu, Hui-Fen; Ungerer, Justin; Hank Juo, Suh-Hang; Maness, Pin-Ching; Yu, Jianping

    2015-07-01

    Hydrolysis of plant biomass generates a mixture of simple sugars that is particularly rich in glucose and xylose. Fermentation of the released sugars emits CO2 as byproduct due to metabolic inefficiencies. Therefore, the ability of a microbe to simultaneously convert biomass sugars and photosynthetically fix CO2 into target products is very desirable. In this work, the cyanobacterium, Synechocystis 6803, was engineered to grow on xylose in addition to glucose. Both the xylA (xylose isomerase) and xylB (xylulokinase) genes from Escherichia coli were required to confer xylose utilization, but a xylose-specific transporter was not required. Introducing xylAB into an ethylene-producing strain increased the rate of ethylene production in the presence of xylose. Additionally, introduction of xylAB into a glycogen-synthesis mutant enhanced production of keto acids. Moreover, isotopic tracer studies found that nearly half of the carbon in the excreted keto acids was derived from the engineered xylose metabolism, while the remainder was derived from CO2 fixation.

  1. Sulfonamide inhibition studies of the γ-carbonic anhydrase from the Antarctic cyanobacterium Nostoc commune.

    PubMed

    Vullo, Daniela; De Luca, Viviana; Del Prete, Sonia; Carginale, Vincenzo; Scozzafava, Andrea; Capasso, Clemente; Supuran, Claudiu T

    2015-04-15

    A carbonic anhydrase (CA, EC 4.2.1.1) belonging to the γ-class has been cloned, purified and characterized from the Antarctic cyanobacterium Nostoc commune. The enzyme showed a good catalytic activity for the physiologic reaction (hydration of carbon dioxide to bicarbonate and a proton) with the following kinetic parameters, kcat of 9.5×10(5)s(-1) and kcat/KM of 8.3×10(7)M(-1)s(-1), being the γ-CA with the highest catalytic activity described so far. A range of aromatic/heterocyclic sulfonamides and one sulfamate were investigated as inhibitors of the new enzyme, denominated here NcoCA. The best NcoCA inhibitors were some sulfonylated sulfanilamide derivatives possessing elongated molecules, aminobenzolamide, acetazolamide, benzolamide, dorzolamide, brinzolamide and topiramate, which showed inhibition constants in the range of 40.3-92.3nM. As 1,5-bisphosphate carboxylase/oxygenase (RubisCO) and γ-CAs are closely associated in carboxysomes of cyanobacteria for enhancing the affinity of RubisCO for CO2 and the efficiency of photosynthesis, investigation of this new enzyme and its affinity for modulators of its activity may bring new insights in these crucial processes. PMID:25773015

  2. Multiple modes of iron uptake by the filamentous, siderophore-producing cyanobacterium, Anabaena sp. PCC 7120.

    PubMed

    Rudolf, Mareike; Kranzler, Chana; Lis, Hagar; Margulis, Ketty; Stevanovic, Mara; Keren, Nir; Schleiff, Enrico

    2015-08-01

    Iron is a member of a small group of nutrients that limits aquatic primary production. Mechanisms for utilizing iron have to be efficient and adapted according to the ecological niche. In respect to iron acquisition cyanobacteria, prokaryotic oxygen evolving photosynthetic organisms can be divided into siderophore- and non-siderophore-producing strains. The results presented in this paper suggest that the situation is far more complex. To understand the bioavailability of different iron substrates and the advantages of various uptake strategies, we examined iron uptake mechanisms in the siderophore-producing cyanobacterium Anabaena sp. PCC 7120. Comparison of the uptake of iron complexed with exogenous (desferrioxamine B, DFB) or to self-secreted (schizokinen) siderophores by Anabaena sp. revealed that uptake of the endogenous produced siderophore complexed to iron is more efficient. In addition, Anabaena sp. is able to take up dissolved, ferric iron hydroxide species (Fe') via a reductive mechanism. Thus, Anabaena sp. exhibits both, siderophore- and non-siderophore-mediated iron uptake. While assimilation of Fe' and FeDFB are not induced by iron starvation, FeSchizokinen uptake rates increase with increasing iron starvation. Consequently, we suggest that Fe' reduction and uptake is advantageous for low-density cultures, while at higher densities siderophore uptake is preferred. PMID:25943160

  3. Growth enhancing effect of exogenous glycine and characterization of its uptake in halotolerant cyanobacterium Aphanothece halophytica.

    PubMed

    Bualuang, Aporn; Incharoensakdi, Aran

    2015-02-01

    Alkaliphilic halotolerant cyanobacterium Aphanothece halophytica showed optimal growth in the medium containing 0.5 M NaCl. The increase of exogenously added glycine to the medium up to 10 mM significantly promoted cell growth under both normal (0.5 M NaCl) and salt stress (2.0 M NaCl) conditions. Salt stress imposed by either 2.0 or 3.0 M NaCl retarded cell growth; however, exogenously added glycine at 10 mM concentration to salt-stress medium resulted in the reduction of growth inhibition particularly under 3.0 M NaCl condition. The uptake of glycine by intact A. halophytica was shown to exhibit saturation kinetics with an apparent K s of 160 μM and V max of 3.9 nmol/min/mg protein. The optimal pH for glycine uptake was at pH 8.0. The uptake activity was decreased in the presence of high concentration of NaCl. Both metabolic inhibitors and ionophores decreased glycine uptake in A. halophytica suggesting an energy-dependent glycine uptake. Several neutral amino acids showed considerable inhibition of glycine uptake with higher than 50 % inhibition observed with serine, cysteine and alanine whereas acidic, basic and aromatic amino acids showed only slight inhibition of glycine uptake.

  4. Type II Toxin–Antitoxin Systems in the Unicellular Cyanobacterium Synechocystis sp. PCC 6803

    PubMed Central

    Kopfmann, Stefan; Roesch, Stefanie K.; Hess, Wolfgang R.

    2016-01-01

    Bacterial toxin–antitoxin (TA) systems are genetic elements, which are encoded by plasmid as well as chromosomal loci. They mediate plasmid and genomic island maintenance through post-segregational killing mechanisms but may also have milder effects, acting as mobile stress response systems that help certain cells of a population in persisting adverse growth conditions. Very few cyanobacterial TA system have been characterized thus far. In this work, we focus on the cyanobacterium Synechocystis 6803, a widely used model organism. We expand the number of putative Type II TA systems from 36 to 69 plus seven stand-alone components. Forty-seven TA pairs are located on the chromosome and 22 are plasmid-located. Different types of toxins are associated with various antitoxins in a mix and match principle. According to protein domains and experimental data, 81% of all toxins in Synechocystis 6803 likely exhibit RNase activity, suggesting extensive potential for toxicity-related RNA degradation and toxin-mediated transcriptome remodeling. Of particular interest is the Ssr8013–Slr8014 system encoded on plasmid pSYSG, which is part of a larger defense island or the pSYSX system Slr6056–Slr6057, which is linked to a bacterial ubiquitin-like system. Consequently, Synechocystis 6803 is one of the most prolific sources of new information about these genetic elements. PMID:27455323

  5. Optimization of photobioreactor growth conditions for a cyanobacterium expressing mosquitocidal Bacillus thuringiensis Cry proteins.

    PubMed

    Ketseoglou, Irene; Bouwer, Gustav

    2013-08-10

    An Anabaena strain (PCC 7120#11) that was genetically engineered to express Bacillus thuringiensis subsp. israelensis cry genes has shown good larvicidal activity against Anopheles arabiensis, a major vector of malaria in Africa. Response surface methodology was used to evaluate the relationship between key growth factors and the volumetric productivity of PCC 7120#11 in an indoor, flat-plate photobioreactor. The interaction of input CO₂ concentration and airflow rate had a statistically significant effect on the volumetric productivity of PCC 7120#11, as did the interaction of airflow rate and photosynthetic photon flux density. Model-based numerical optimization indicated that the optimal factor level combination for maximizing PCC 7120#11 volumetric productivity was a photosynthetic photon flux density of 154 μmol m⁻² s⁻¹ and air enriched with 3.18% (v/v) CO₂ supplied at a flow rate of 1.02 vessel volumes per minute. At the levels evaluated in the study, none of the growth factors had a significant effect on the median lethal concentration of PCC 7120#11 against An. arabiensis larvae. This finding is important because loss of mosquitocidal activity under growth conditions that maximize volumetric productivity would impact on the feasibility of using PCC 7120#11 in malaria vector control programs. The study showed the usefulness of response surface methodology for determination of the optimal growth conditions for a cyanobacterium that is genetically engineered to have larvicidal activity against malaria vectors. PMID:23732832

  6. Characterization of red-shifted phycobilisomes isolated from the chlorophyll f-containing cyanobacterium Halomicronema hongdechloris.

    PubMed

    Li, Yaqiong; Lin, Yuankui; Garvey, Christopher J; Birch, Debra; Corkery, Robert W; Loughlin, Patrick C; Scheer, Hugo; Willows, Robert D; Chen, Min

    2016-01-01

    Phycobilisomes are the main light-harvesting protein complexes in cyanobacteria and some algae. It is commonly accepted that these complexes only absorb green and orange light, complementing chlorophyll absorbance. Here, we present a new phycobilisome derived complex that consists only of allophycocyanin core subunits, having red-shifted absorption peaks of 653 and 712 nm. These red-shifted phycobiliprotein complexes were isolated from the chlorophyll f-containing cyanobacterium, Halomicronema hongdechloris, grown under monochromatic 730 nm-wavelength (far-red) light. The 3D model obtained from single particle analysis reveals a double disk assembly of 120-145 Å with two α/β allophycocyanin trimers fitting into the two separated disks. They are significantly smaller than typical phycobilisomes formed from allophycocyanin subunits and core-membrane linker proteins, which fit well with a reduced distance between thylakoid membranes observed from cells grown under far-red light. Spectral analysis of the dissociated and denatured phycobiliprotein complexes grown under both these light conditions shows that the same bilin chromophore, phycocyanobilin, is exclusively used. Our findings show that red-shifted phycobilisomes are required for assisting efficient far-red light harvesting. Their discovery provides new insights into the molecular mechanisms of light harvesting under extreme conditions for photosynthesis, as well as the strategies involved in flexible chromatic acclimation to diverse light conditions. PMID:26514405

  7. A biliverdin-binding cyanobacteriochrome from the chlorophyll d-bearing cyanobacterium Acaryochloris marina.

    PubMed

    Narikawa, Rei; Nakajima, Takahiro; Aono, Yuki; Fushimi, Keiji; Enomoto, Gen; Ni-Ni-Win; Itoh, Shigeru; Sato, Moritoshi; Ikeuchi, Masahiko

    2015-01-01

    Cyanobacteriochromes (CBCRs) are linear tetrapyrrole-binding photoreceptors in cyanobacteria that absorb visible and near-ultraviolet light. CBCRs are divided into two types based on the type of chromophore they contain: phycocyanobilin (PCB) or phycoviolobilin (PVB). PCB-binding CBCRs reversibly photoconvert at relatively long wavelengths, i.e., the blue-to-red region, whereas PVB-binding CBCRs reversibly photoconvert at shorter wavelengths, i.e., the near-ultraviolet to green region. Notably, prior to this report, CBCRs containing biliverdin (BV), which absorbs at longer wavelengths than do PCB and PVB, have not been found. Herein, we report that the typical red/green CBCR AM1_1557 from the chlorophyll d-bearing cyanobacterium Acaryochloris marina can bind BV almost comparable to PCB. This BV-bound holoprotein reversibly photoconverts between a far red light-absorbing form (Pfr, λmax = 697 nm) and an orange light-absorbing form (Po, λmax = 622 nm). At room temperature, Pfr fluoresces with a maximum at 730 nm. These spectral features are red-shifted by 48~77 nm compared with those of the PCB-bound domain. Because the absorbance of chlorophyll d is red-shifted compared with that of chlorophyll a, the BV-bound AM1_1557 may be a physiologically relevant feature of A. marina and is potentially useful as an optogenetic switch and/or fluorescence imager. PMID:25609645

  8. Crystal Structure of Allophycocyanin from Marine Cyanobacterium Phormidium sp. A09DM.

    PubMed

    Sonani, Ravi Raghav; Gupta, Gagan Deep; Madamwar, Datta; Kumar, Vinay

    2015-01-01

    Isolated phycobilisome (PBS) sub-assemblies have been widely subjected to X-ray crystallography analysis to obtain greater insights into the structure-function relationship of this light harvesting complex. Allophycocyanin (APC) is the phycobiliprotein always found in the PBS core complex. Phycocyanobilin (PCB) chromophores, covalently bound to conserved Cys residues of α- and β- subunits of APC, are responsible for solar energy absorption from phycocyanin and for transfer to photosynthetic apparatus. In the known APC structures, heterodimers of α- and β- subunits (known as αβ monomers) assemble as trimer or hexamer. We here for the first time report the crystal structure of APC isolated from a marine cyanobacterium (Phormidium sp. A09DM). The crystal structure has been refined against all the observed data to the resolution of 2.51 Å to Rwork (Rfree) of 0.158 (0.229) with good stereochemistry of the atomic model. The Phormidium protein exists as a trimer of αβ monomers in solution and in crystal lattice. The overall tertiary structures of α- and β- subunits, and trimeric quaternary fold of the Phormidium protein resemble the other known APC structures. Also, configuration and conformation of the two covalently bound PCB chromophores in the marine APC are same as those observed in fresh water cyanobacteria and marine red algae. More hydrophobic residues, however, constitute the environment of the chromophore bound to α-subunit of the Phormidium protein, owing mainly to amino acid substitutions in the marine protein. PMID:25923120

  9. [Transport systems for carbonate in the extremely natronophilic cyanobacterium Euhalothece sp].

    PubMed

    Mikhodiuk, O S; Zavarzin, G A; Ivanovskiĭ, R N

    2008-01-01

    The effect of carbonate concentration, pH of the medium, and illumination intensity on the major physiological characteristics (growth rate and the intensities of CO2 assimilation and oxygen photoproduction) of the natronophilic cyanobacterium Euhalothece sp. Z-M001 have been studied. It was established that the investigated microorganism has at least two transport systems (TS) for CO2, which differ in both the pH optimum and substrate affinity: TS I has a pH, 9.4-9.5 and a K(S) 0.5 of 13-17 mM, whereas TS II has a pH(opt) 9.9-10.2 and a K(S) 0.5 of 600-800 mM. The substrate affinity of these transport systems is several orders of magnitude lower than the substrate affinity of the transport systems of freshwater cyanobacteria. It is suggested that they are unique for extremely alkaliphilic cyanobacteria and reflect their adaptation to the seasonal cycles of the lake hydrochemistry. PMID:18825972

  10. Biosafety of biotechnologically important microalgae: intrinsic suicide switch implementation in cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Čelešnik, Helena; Tanšek, Anja; Tahirović, Aneja; Vižintin, Angelika; Mustar, Jernej; Vidmar, Vita; Dolinar, Marko

    2016-01-01

    In recent years, photosynthetic autotrophic cyanobacteria have attracted interest for biotechnological applications for sustainable production of valuable metabolites. Although biosafety issues can have a great impact on public acceptance of cyanobacterial biotechnology, biosafety of genetically modified cyanobacteria has remained largely unexplored. We set out to incorporate biocontainment systems in the model cyanobacteriumSynechocystissp. PCC 6803. Plasmid-encoded safeguards were constructed using the nonspecific nuclease NucA fromAnabaenacombined with different metal-ion inducible promoters. In this manner, conditional lethality was dependent on intracellular DNA degradation for regulated autokilling as well as preclusion of horizontal gene transfer. In cells carrying the suicide switch comprising thenucAgene fused to a variant of thecopMpromoter, efficient inducible autokilling was elicited. Parallel to nuclease-based safeguards, cyanobacterial toxin/antitoxin (TA) modules were examined in biosafety switches. Rewiring ofSynechocystisTA pairsssr1114/slr0664andslr6101/slr6100for conditional lethality using metal-ion responsive promoters resulted in reduced growth, rather than cell killing, suggesting cells could cope with elevated toxin levels. Overall, promoter properties and translation efficiency influenced the efficacy of biocontainment systems. Several metal-ion promoters were tested in the context of safeguards, and selected promoters, including anrsBvariant, were characterized by beta-galactosidase reporter assay.

  11. Introduction of a Synthetic CO2-fixing Photorespiratory Bypass into a Cyanobacterium

    PubMed Central

    Shih, Patrick M.; Zarzycki, Jan; Niyogi, Krishna K.; Kerfeld, Cheryl A.

    2014-01-01

    Global photosynthetic productivity is limited by the enzymatic assimilation of CO2 into organic carbon compounds. Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), the carboxylating enzyme of the Calvin-Benson cycle, poorly discriminates between CO2 and O2, leading to photorespiration and the loss of fixed carbon and nitrogen. With the advent of synthetic biology, it is now feasible to design, synthesize, and introduce biochemical pathways in vivo. We engineered a synthetic photorespiratory bypass based on the 3-hydroxypropionate bi-cycle into the model cyanobacterium, Synechococcus elongatus sp. PCC 7942. The heterologously expressed cycle is designed to function as both a photorespiratory bypass and an additional CO2-fixing pathway, supplementing the Calvin-Benson cycle. We demonstrate the function of all six introduced enzymes and identify bottlenecks to be targeted in subsequent bioengineering. These results have implications for efforts to improve photosynthesis and for the “green” production of high value products of biotechnological interest. PMID:24558040

  12. Release of ecologically relevant metabolites by the cyanobacterium Synechococcus elongates CCMP 1631.

    PubMed

    Fiore, Cara L; Longnecker, Krista; Kido Soule, Melissa C; Kujawinski, Elizabeth B

    2015-10-01

    Photoautotrophic plankton in the surface ocean release organic compounds that fuel secondary production by heterotrophic bacteria. Here we show that an abundant marine cyanobacterium, Synechococcus elongatus, contributes a variety of nitrogen-rich and sulfur-containing compounds to dissolved organic matter. A combination of targeted and untargeted metabolomics and genomic tools was used to characterize the intracellular and extracellular metabolites of S. elongatus. Aromatic compounds, such as 4-hydroxybenzoic acid and phenylalanine, as well as nucleosides (e.g. thymidine, 5'-methylthioadenosine, xanthosine), the organosulfur compound 3-mercaptopropionate, and the plant auxin indole 3-acetic acid, were released by S. elongatus at multiple time points during its growth. Further, the amino acid kynurenine was found to accumulate in the media even though it was not present in the predicted metabolome of S. elongatus. This indicates that some metabolites, including those not predicted by an organism's genome, are likely excreted into the environment as waste; however, these molecules may have broader ecological relevance if they are labile to nearby microbes. The compounds described herein provide excellent targets for quantitative analysis in field settings to assess the source and lability of dissolved organic matter in situ. PMID:25970745

  13. Regulation of the scp Genes in the Cyanobacterium Synechocystis sp. PCC 6803--What is New?

    PubMed

    Cheregi, Otilia; Funk, Christiane

    2015-08-12

    In the cyanobacterium Synechocystis sp. PCC 6803 there are five genes encoding small CAB-like (SCP) proteins, which have been shown to be up-regulated under stress. Analyses of the promoter sequences of the scp genes revealed the existence of an NtcA binding motif in two scp genes, scpB and scpE. Binding of NtcA, the key transcriptional regulator during nitrogen stress, to the promoter regions was shown by electrophoretic mobility shift assay. The metabolite 2-oxoglutarate did not increase the affinity of NtcA for binding to the promoters of scpB and scpE. A second motif, the HIP1 palindrome 5' GGCGATCGCC 3', was detected in the upstream regions of scpB and scpC. The transcription factor encoded by sll1130 has been suggested to recognize this motif to regulate heat-responsive genes. Our data suggest that HIP1 is not a regulatory element within the scp genes. Further, the presence of the high light regulatory (HLR1) motif was confirmed in scpB-E, in accordance to their induced transcriptions in cells exposed to high light. The HLR1 motif was newly discovered in eight additional genes.

  14. Nitrogen availability increases the toxin quota of a harmful cyanobacterium, Microcystis aeruginosa.

    PubMed

    Horst, Geoffrey P; Sarnelle, Orlando; White, Jeffrey D; Hamilton, Stephen K; Kaul, Rajreni B; Bressie, Julianne D

    2014-05-01

    An important objective in understanding harmful phytoplankton blooms is determining how environmental factors influence the toxicity of bloom-forming species. We examined how nutrients and grazers (dreissenid mussels) affect the production of microcystin (a liver toxin) by the cyanobacterium Microcystis aeruginosa, via a combination of field and laboratory experiments, and field observations in Lake Erie. The field experiment revealed no effect of mussel density on microcystin quota (particulate microcystin per unit Microcystis biomass). In contrast, in both field and laboratory experiments, nitrogen-limited conditions led to substantially reduced microcystin quota relative to phosphorus-limited or nutrient-saturated conditions. In the field experiment, microcystin per unit of mcyB gene was strongly reduced under nitrogen-limited conditions, indicating a phenotypic response. Results from a seasonal survey in the western basin of Lake Erie revealed a similar negative influence of nitrogen limitation (as indexed by nitrate concentration) on microcystin quota. Our results are consistent with stoichiometric considerations in that the cell quota of a nitrogen-rich secondary metabolite, microcystin, was reduced disproportionately under nitrogen limitation.

  15. Genomic Structure of an Economically Important Cyanobacterium, Arthrospira (Spirulina) platensis NIES-39

    PubMed Central

    Fujisawa, Takatomo; Narikawa, Rei; Okamoto, Shinobu; Ehira, Shigeki; Yoshimura, Hidehisa; Suzuki, Iwane; Masuda, Tatsuru; Mochimaru, Mari; Takaichi, Shinichi; Awai, Koichiro; Sekine, Mitsuo; Horikawa, Hiroshi; Yashiro, Isao; Omata, Seiha; Takarada, Hiromi; Katano, Yoko; Kosugi, Hiroki; Tanikawa, Satoshi; Ohmori, Kazuko; Sato, Naoki; Ikeuchi, Masahiko; Fujita, Nobuyuki; Ohmori, Masayuki

    2010-01-01

    A filamentous non-N2-fixing cyanobacterium, Arthrospira (Spirulina) platensis, is an important organism for industrial applications and as a food supply. Almost the complete genome of A. platensis NIES-39 was determined in this study. The genome structure of A. platensis is estimated to be a single, circular chromosome of 6.8 Mb, based on optical mapping. Annotation of this 6.7 Mb sequence yielded 6630 protein-coding genes as well as two sets of rRNA genes and 40 tRNA genes. Of the protein-coding genes, 78% are similar to those of other organisms; the remaining 22% are currently unknown. A total 612 kb of the genome comprise group II introns, insertion sequences and some repetitive elements. Group I introns are located in a protein-coding region. Abundant restriction-modification systems were determined. Unique features in the gene composition were noted, particularly in a large number of genes for adenylate cyclase and haemolysin-like Ca2+-binding proteins and in chemotaxis proteins. Filament-specific genes were highlighted by comparative genomic analysis. PMID:20203057

  16. Intercellular transfer along the trichomes of the invasive terminal heterocyst forming cyanobacterium Cylindrospermopsis raciborskii CS-505.

    PubMed

    Plominsky, Álvaro M; Delherbe, Nathalie; Mandakovic, Dinka; Riquelme, Brenda; González, Karen; Bergman, Birgitta; Mariscal, Vicente; Vásquez, Mónica

    2015-03-01

    Cylindrospermopsis raciborskii CS-505 is an invasive freshwater filamentous cyanobacterium that when grown diazotrophically may develop trichomes of up to 100 vegetative cells while differentiating only two end heterocysts, the sole sites for their N2-fixation process. We examined the diazotrophic growth and intercellular transfer mechanisms in C. raciborskii CS-505. Subjecting cultures to a combined-nitrogen-free medium to elicit N2 fixation, the trichome length remained unaffected while growth rates decreased. The structures and proteins for intercellular communication showed that while a continuous periplasmic space was apparent along the trichomes, the putative septal junction sepJ gene is divided into two open reading frames and lacks several transmembrane domains unlike the situation in Anabaena, differentiating a 5-fold higher frequency of heterocysts. FRAP analyses also showed that the dyes calcein and 5-CFDA were taken up by heterocysts and vegetative cells, and that the transfer from heterocysts and 'terminal' vegetative cells showed considerably higher transfer rates than that from vegetative cells located in the middle of the trichomes. The data suggest that C. raciborskii CS-505 compensates its low-frequency heterocyst phenotype by a highly efficient transfer of the fixed nitrogen towards cells in distal parts of the trichomes (growing rapidly) while cells in central parts suffers (slow growth).

  17. Crystal Structure of Allophycocyanin from Marine Cyanobacterium Phormidium sp. A09DM

    PubMed Central

    Gupta, Gagan Deep; Madamwar, Datta

    2015-01-01

    Isolated phycobilisome (PBS) sub-assemblies have been widely subjected to X-ray crystallography analysis to obtain greater insights into the structure-function relationship of this light harvesting complex. Allophycocyanin (APC) is the phycobiliprotein always found in the PBS core complex. Phycocyanobilin (PCB) chromophores, covalently bound to conserved Cys residues of α- and β- subunits of APC, are responsible for solar energy absorption from phycocyanin and for transfer to photosynthetic apparatus. In the known APC structures, heterodimers of α- and β- subunits (known as αβ monomers) assemble as trimer or hexamer. We here for the first time report the crystal structure of APC isolated from a marine cyanobacterium (Phormidium sp. A09DM). The crystal structure has been refined against all the observed data to the resolution of 2.51 Å to Rwork (Rfree) of 0.158 (0.229) with good stereochemistry of the atomic model. The Phormidium protein exists as a trimer of αβ monomers in solution and in crystal lattice. The overall tertiary structures of α- and β- subunits, and trimeric quaternary fold of the Phormidium protein resemble the other known APC structures. Also, configuration and conformation of the two covalently bound PCB chromophores in the marine APC are same as those observed in fresh water cyanobacteria and marine red algae. More hydrophobic residues, however, constitute the environment of the chromophore bound to α-subunit of the Phormidium protein, owing mainly to amino acid substitutions in the marine protein. PMID:25923120

  18. Exposure of mallards (Anas platyrhynchos) to the hepatotoxic cyanobacterium Nodularia spumigena

    USGS Publications Warehouse

    Sipia, V.O.; Franson, J.C.; Sjovall, O.; Pflugmacher, S.; Shearn-Bochsler, V.; Rocke, T.E.; Meriluoto, J.A.O.

    2008-01-01

    Nodularin (NODLN) is a cyclic pentapeptide hepatotoxin produced by the cyanobacterium Nodularia spumigena, which forms extensive blooms during the summer in the Baltic Sea. Nodularin was detected in liver, muscle and/or feather samples of several common eiders (Somateria mollissima) from the Gulf of Finland (northern Baltic Sea) in 2002-2005. Published information on the adverse effects of NODLN in marine birds is scarce. The aim of this study was to evaluate the toxicity of NODLN, and determine the concentrations of NODLN in liver and muscle tissue in mallards (Anas platyrhynchos) exposed to N. spumigena. Mallards received a single or multiple exposure via oral gavage with an aqueous slurry containing toxic N. spumigena. Dosages ranged from 200 to 600 ??g NODLN per kg body weight (bw). There were minimal histopathological changes in liver tissue, and brain cholinesterase activity did not differ among treatment groups. Concentrations of NODLN measured by LC-MS in liver varied between approximately 3-120 ??g kg-1 dry weight (dw) and ducks receiving multiple exposures had significantly greater liver toxin levels than ducks receiving the two lowest single exposures. In muscle, NODLN concentrations were approximately 2-6 ??g kg-1 dw, but did not differ significantly among exposure groups. This is the first in vivo lab study examining the effects and bioaccumulation of NODLN from N. spumigena in birds. The mallards in this study were resistant to adverse effects and did not bioaccumulate substantial levels of NODLN at the doses given. ?? 2008 Taylor & Francis.

  19. Anoxygenic Photosynthesis Controls Oxygenic Photosynthesis in a Cyanobacterium from a Sulfidic Spring

    PubMed Central

    Al-Najjar, Mohammad A. A.; Yilmaz, Pelin; Lavik, Gaute; de Beer, Dirk; Polerecky, Lubos

    2015-01-01

    Before the Earth's complete oxygenation (0.58 to 0.55 billion years [Ga] ago), the photic zone of the Proterozoic oceans was probably redox stratified, with a slightly aerobic, nutrient-limited upper layer above a light-limited layer that tended toward euxinia. In such oceans, cyanobacteria capable of both oxygenic and sulfide-driven anoxygenic photosynthesis played a fundamental role in the global carbon, oxygen, and sulfur cycle. We have isolated a cyanobacterium, Pseudanabaena strain FS39, in which this versatility is still conserved, and we show that the transition between the two photosynthetic modes follows a surprisingly simple kinetic regulation controlled by this organism's affinity for H2S. Specifically, oxygenic photosynthesis is performed in addition to anoxygenic photosynthesis only when H2S becomes limiting and its concentration decreases below a threshold that increases predictably with the available ambient light. The carbon-based growth rates during oxygenic and anoxygenic photosynthesis were similar. However, Pseudanabaena FS39 additionally assimilated NO3− during anoxygenic photosynthesis. Thus, the transition between anoxygenic and oxygenic photosynthesis was accompanied by a shift of the C/N ratio of the total bulk biomass. These mechanisms offer new insights into the way in which, despite nutrient limitation in the oxic photic zone in the mid-Proterozoic oceans, versatile cyanobacteria might have promoted oxygenic photosynthesis and total primary productivity, a key step that enabled the complete oxygenation of our planet and the subsequent diversification of life. PMID:25576611

  20. Cytoplasmic Membrane Changes during Adaptation of the Fresh Water Cyanobacterium Synechococcus 6311 to Salinity 1

    PubMed Central

    Lefort-Tran, Marcelle; Pouphile, Monique; Spath, Susan; Packer, Lester

    1988-01-01

    In this investigation, changes were characterized in cell structure and cytoplasmic membrane organization that occur when the freshwater cyanobacterium Synechococcus 6311 is transferred from `low salt' (0.03 molar NaCl) to `high salt' (0.5 molar NaCl) media (i.e. sea water concentration). Cells were examined at several time points after the imposition of the salt stress and compared to control cells, in thin sections and freeze fracture electron microscopy, and by flow cytometry. One minute after exposure to high salt, i.e. `salt shock,' virtually all intracellular granules disappeared, the density of the cytoplasm decreased, and the appearance of DNA material was changed. Glycogen and other granules, however, reappeared by 4 hours after salt exposure. The organization of the cytoplasmic membrane undergoes major reorganization following salt shock. Freeze-fracture electron microscopy showed that small intramembrane particles (diameters 7.5 and 8.5 nanometers) are reduced in number by two- to fivefold, whereas large particles, (diameters 14.5 and 17.5 nanometers) increase two- to fourfold in frequency, compared to control cells grown in low salt medium. The changes in particle size distribution suggest synthesis of new membrane proteins, in agreement with the known increases in respiration, cytochrome oxidase, and sodium proton exchange activity of the cytoplasmic membrane. Images Fig. 2 Fig. 1 Fig. 5 PMID:11537874

  1. Sequential splicing of a group II twintron in the marine cyanobacterium Trichodesmium

    PubMed Central

    Pfreundt, Ulrike; Hess, Wolfgang R.

    2015-01-01

    The marine cyanobacterium Trichodesmium is unusual in its genomic architecture as 40% of the genome is occupied by non-coding DNA. Although the majority of it is transcribed into RNA, it is not well understood why such a large non-coding genome fraction is maintained. Mobile genetic elements can contribute to genome expansion. Many bacteria harbor introns whereas twintrons, introns-in-introns, are rare and not known to interrupt protein-coding genes in bacteria. Here we show the sequential in vivo splicing of a 5400 nt long group II twintron interrupting a highly conserved gene that is associated with RNase HI in some cyanobacteria, but free-standing in others, including Trichodesmium erythraeum. We show that twintron splicing results in a putatively functional mRNA. The full genetic arrangement was found conserved in two geospatially distinct metagenomic datasets supporting its functional relevance. We further show that splicing of the inner intron yields the free intron as a true circle. This reaction requires the spliced exon reopening (SER) reaction to provide a free 5′ exon. The fact that Trichodesmium harbors a functional twintron fits in well with the high intron load of these genomes, and suggests peculiarities in its genetic machinery permitting such arrangements. PMID:26577185

  2. CyanOmics: an integrated database of omics for the model cyanobacterium Synechococcus sp. PCC 7002.

    PubMed

    Yang, Yaohua; Feng, Jie; Li, Tao; Ge, Feng; Zhao, Jindong

    2015-01-01

    Cyanobacteria are an important group of organisms that carry out oxygenic photosynthesis and play vital roles in both the carbon and nitrogen cycles of the Earth. The annotated genome of Synechococcus sp. PCC 7002, as an ideal model cyanobacterium, is available. A series of transcriptomic and proteomic studies of Synechococcus sp. PCC 7002 cells grown under different conditions have been reported. However, no database of such integrated omics studies has been constructed. Here we present CyanOmics, a database based on the results of Synechococcus sp. PCC 7002 omics studies. CyanOmics comprises one genomic dataset, 29 transcriptomic datasets and one proteomic dataset and should prove useful for systematic and comprehensive analysis of all those data. Powerful browsing and searching tools are integrated to help users directly access information of interest with enhanced visualization of the analytical results. Furthermore, Blast is included for sequence-based similarity searching and Cluster 3.0, as well as the R hclust function is provided for cluster analyses, to increase CyanOmics's usefulness. To the best of our knowledge, it is the first integrated omics analysis database for cyanobacteria. This database should further understanding of the transcriptional patterns, and proteomic profiling of Synechococcus sp. PCC 7002 and other cyanobacteria. Additionally, the entire database framework is applicable to any sequenced prokaryotic genome and could be applied to other integrated omics analysis projects. Database URL: http://lag.ihb.ac.cn/cyanomics.

  3. Biosafety of biotechnologically important microalgae: intrinsic suicide switch implementation in cyanobacterium Synechocystis sp. PCC 6803

    PubMed Central

    Čelešnik, Helena; Tanšek, Anja; Tahirović, Aneja; Vižintin, Angelika; Mustar, Jernej; Vidmar, Vita; Dolinar, Marko

    2016-01-01

    ABSTRACT In recent years, photosynthetic autotrophic cyanobacteria have attracted interest for biotechnological applications for sustainable production of valuable metabolites. Although biosafety issues can have a great impact on public acceptance of cyanobacterial biotechnology, biosafety of genetically modified cyanobacteria has remained largely unexplored. We set out to incorporate biocontainment systems in the model cyanobacterium Synechocystis sp. PCC 6803. Plasmid-encoded safeguards were constructed using the nonspecific nuclease NucA from Anabaena combined with different metal-ion inducible promoters. In this manner, conditional lethality was dependent on intracellular DNA degradation for regulated autokilling as well as preclusion of horizontal gene transfer. In cells carrying the suicide switch comprising the nucA gene fused to a variant of the copM promoter, efficient inducible autokilling was elicited. Parallel to nuclease-based safeguards, cyanobacterial toxin/antitoxin (TA) modules were examined in biosafety switches. Rewiring of Synechocystis TA pairs ssr1114/slr0664 and slr6101/slr6100 for conditional lethality using metal-ion responsive promoters resulted in reduced growth, rather than cell killing, suggesting cells could cope with elevated toxin levels. Overall, promoter properties and translation efficiency influenced the efficacy of biocontainment systems. Several metal-ion promoters were tested in the context of safeguards, and selected promoters, including a nrsB variant, were characterized by beta-galactosidase reporter assay. PMID:27029902

  4. Crystal Structure of Allophycocyanin from Marine Cyanobacterium Phormidium sp. A09DM.

    PubMed

    Sonani, Ravi Raghav; Gupta, Gagan Deep; Madamwar, Datta; Kumar, Vinay

    2015-01-01

    Isolated phycobilisome (PBS) sub-assemblies have been widely subjected to X-ray crystallography analysis to obtain greater insights into the structure-function relationship of this light harvesting complex. Allophycocyanin (APC) is the phycobiliprotein always found in the PBS core complex. Phycocyanobilin (PCB) chromophores, covalently bound to conserved Cys residues of α- and β- subunits of APC, are responsible for solar energy absorption from phycocyanin and for transfer to photosynthetic apparatus. In the known APC structures, heterodimers of α- and β- subunits (known as αβ monomers) assemble as trimer or hexamer. We here for the first time report the crystal structure of APC isolated from a marine cyanobacterium (Phormidium sp. A09DM). The crystal structure has been refined against all the observed data to the resolution of 2.51 Å to Rwork (Rfree) of 0.158 (0.229) with good stereochemistry of the atomic model. The Phormidium protein exists as a trimer of αβ monomers in solution and in crystal lattice. The overall tertiary structures of α- and β- subunits, and trimeric quaternary fold of the Phormidium protein resemble the other known APC structures. Also, configuration and conformation of the two covalently bound PCB chromophores in the marine APC are same as those observed in fresh water cyanobacteria and marine red algae. More hydrophobic residues, however, constitute the environment of the chromophore bound to α-subunit of the Phormidium protein, owing mainly to amino acid substitutions in the marine protein.

  5. A biliverdin-binding cyanobacteriochrome from the chlorophyll d–bearing cyanobacterium Acaryochloris marina

    PubMed Central

    Narikawa, Rei; Nakajima, Takahiro; Aono, Yuki; Fushimi, Keiji; Enomoto, Gen; Ni-Ni-Win; Itoh, Shigeru; Sato, Moritoshi; Ikeuchi, Masahiko

    2015-01-01

    Cyanobacteriochromes (CBCRs) are linear tetrapyrrole-binding photoreceptors in cyanobacteria that absorb visible and near-ultraviolet light. CBCRs are divided into two types based on the type of chromophore they contain: phycocyanobilin (PCB) or phycoviolobilin (PVB). PCB-binding CBCRs reversibly photoconvert at relatively long wavelengths, i.e., the blue-to-red region, whereas PVB-binding CBCRs reversibly photoconvert at shorter wavelengths, i.e., the near-ultraviolet to green region. Notably, prior to this report, CBCRs containing biliverdin (BV), which absorbs at longer wavelengths than do PCB and PVB, have not been found. Herein, we report that the typical red/green CBCR AM1_1557 from the chlorophyll d–bearing cyanobacterium Acaryochloris marina can bind BV almost comparable to PCB. This BV-bound holoprotein reversibly photoconverts between a far red light–absorbing form (Pfr, λmax = 697 nm) and an orange light–absorbing form (Po, λmax = 622 nm). At room temperature, Pfr fluoresces with a maximum at 730 nm. These spectral features are red-shifted by 48~77 nm compared with those of the PCB-bound domain. Because the absorbance of chlorophyll d is red-shifted compared with that of chlorophyll a, the BV-bound AM1_1557 may be a physiologically relevant feature of A. marina and is potentially useful as an optogenetic switch and/or fluorescence imager. PMID:25609645

  6. Proteome-wide analysis and diel proteomic profiling of the cyanobacterium Arthrospira platensis PCC 8005.

    PubMed

    Matallana-Surget, Sabine; Derock, Jérémy; Leroy, Baptiste; Badri, Hanène; Deschoenmaeker, Frédéric; Wattiez, Ruddy

    2014-01-01

    The filamentous cyanobacterium Arthrospira platensis has a long history of use as a food supply and it has been used by the European Space Agency in the MELiSSA project, an artificial microecosystem which supports life during long-term manned space missions. This study assesses progress in the field of cyanobacterial shotgun proteomics and light/dark diurnal cycles by focusing on Arthrospira platensis. Several fractionation workflows including gel-free and gel-based protein/peptide fractionation procedures were used and combined with LC-MS/MS analysis, enabling the overall identification of 1306 proteins, which represents 21% coverage of the theoretical proteome. A total of 30 proteins were found to be significantly differentially regulated under light/dark growth transition. Interestingly, most of the proteins showing differential abundance were related to photosynthesis, the Calvin cycle and translation processes. A novel aspect and major achievement of this work is the successful improvement of the cyanobacterial proteome coverage using a 3D LC-MS/MS approach, based on an immobilized metal affinity chromatography, a suitable tool that enabled us to eliminate the most abundant protein, the allophycocyanin. We also demonstrated that cell growth follows a light/dark cycle in A. platensis. This preliminary proteomic study has highlighted new characteristics of the Arthrospira platensis proteome in terms of diurnal regulation. PMID:24914774

  7. Multiple modes of iron uptake by the filamentous, siderophore-producing cyanobacterium, Anabaena sp. PCC 7120.

    PubMed

    Rudolf, Mareike; Kranzler, Chana; Lis, Hagar; Margulis, Ketty; Stevanovic, Mara; Keren, Nir; Schleiff, Enrico

    2015-08-01

    Iron is a member of a small group of nutrients that limits aquatic primary production. Mechanisms for utilizing iron have to be efficient and adapted according to the ecological niche. In respect to iron acquisition cyanobacteria, prokaryotic oxygen evolving photosynthetic organisms can be divided into siderophore- and non-siderophore-producing strains. The results presented in this paper suggest that the situation is far more complex. To understand the bioavailability of different iron substrates and the advantages of various uptake strategies, we examined iron uptake mechanisms in the siderophore-producing cyanobacterium Anabaena sp. PCC 7120. Comparison of the uptake of iron complexed with exogenous (desferrioxamine B, DFB) or to self-secreted (schizokinen) siderophores by Anabaena sp. revealed that uptake of the endogenous produced siderophore complexed to iron is more efficient. In addition, Anabaena sp. is able to take up dissolved, ferric iron hydroxide species (Fe') via a reductive mechanism. Thus, Anabaena sp. exhibits both, siderophore- and non-siderophore-mediated iron uptake. While assimilation of Fe' and FeDFB are not induced by iron starvation, FeSchizokinen uptake rates increase with increasing iron starvation. Consequently, we suggest that Fe' reduction and uptake is advantageous for low-density cultures, while at higher densities siderophore uptake is preferred.

  8. Paired cloning vectors for complementation of mutations in the cyanobacterium Anabaena sp. strain PCC 7120

    SciTech Connect

    Wolk, C. Peter Wolk; Fan, Qing; Zhou, Ruanbao; Huang, Guocun; Lechno-Yossef, Sigal; Kuritz, Tanya; Wojciuch, Elizabeth

    2007-01-01

    The clones generated in a sequencing project represent a resource for subsequent analysis of the organism whose genome has been sequenced. We describe an interrelated group of cloning vectors that either integrate into the genome or replicate, and that enhance the utility, for developmental and other studies, of the clones used to determine the genomic sequence of the cyanobacterium, Anabaena sp. strain PCC 7120. One integrating vector is a mobilizable BAC vector that was used both to generate bridging clones and to complement transposon mutations. Upon addition of a cassette that permits mobilization and selection, pUC-based sequencing clones can also integrate into the genome and thereupon complement transposon mutations. The replicating vectors are based on cyanobacterial plasmid pDU1, whose sequence we report, and on broad-host-range plasmid RSF1010. The RSF1010- and pDU1-based vectors provide the opportunity to express different genes from either cell-type-specific or -generalist promoters, simultaneously from different plasmids in the same cyanobacterial cells. We show that pDU1 ORF4 and its upstream region play an essential role in the replication and copy number of pDU1, and that ORFs alr2887 and alr3546 (hetF{sub A}) of Anabaena sp. are required specifically for fixation of dinitrogen under oxic conditions.

  9. Fluorapatite as Inorganic Phosphate Source for the Cyanobacterium Anabaena PCC 7120

    NASA Astrophysics Data System (ADS)

    Schaperdoth, I.; Brantley, S.

    2003-12-01

    We investigated the hypothesis that the cyanobacterium Anabaena PCC 7120 is able to use fluorapatite (FAP) as sole phosphate source for growth. In the experimental setup the dissolution of FAP was tested in a phosphate free growth medium in the presence and absence of the Anabaena, as well as the cell free supernatant of an Anabaena culture. The results were compared with that of an Anabaena culture grown without fluorapatite. Parameters measured were pH, dissolved P and Ca, as well as cell density. The FAP grains were analyzed using SEM and XPS. Additionally, the differential expression of secreted proteins in cultures with and without dissolved phosphate was examined. P-limited Anabaena cultures tend to aggregate and in the presence of FAP the cells attached themselves to the mineral grains. The cultures benefit from the presence of FAP. The cells have a very effective P-uptake system that is able to take up dissolved phosphate very efficiently and draw the concentrations down to very low levels. Furthermore, the SEM analysis of FAP showed an etching of the mineral grains in the samples from the Anabaena cultures. The mechanism of apatite dissolution with and without Anabaena will be discussed in terms of these experimental observations.

  10. Transcriptional and Mutational Analysis of the Uptake Hydrogenase of the Filamentous Cyanobacterium Anabaena variabilis ATCC 29413

    PubMed Central

    Happe, Thomas; Schütz, Kathrin; Böhme, Herbert

    2000-01-01

    A 10-kb DNA region of the cyanobacterium Anabaena variabilis ATCC 29413 containing the structural genes of the uptake hydrogenase (hupSL) was cloned and sequenced. In contrast to the hupL gene of Anabaena sp. strain PCC 7120, which is interrupted by a 10.5-kb DNA fragment in vegetative cells, there is no programmed rearrangement within the hupL gene during the heterocyst differentiation of A. variabilis. The hupSL genes were transcribed as a 2.7-kb operon and were induced only under nitrogen-fixing conditions, as shown by Northern blot experiments and reverse transcriptase PCR. Primer extension experiments with a fluorescence-labeled oligonucleotide primer confirmed these results and identified the 5′ start of the mRNA transcript 103 bp upstream of the ATG initiation codon. A consensus sequence in the promoter that is recognized by the fumarate nitrate reductase regulator (Fnr) could be detected. The hupSL operon in A. variabilis was interrupted by an interposon deletion (mutant strain AVM13). Under N2-fixing conditions, the mutant strain exhibited significantly increased rates in H2 accumulation and produced three times more hydrogen than the wild type. These results indicate that the uptake hydrogenase is catalytically active in the wild type and that the enzyme reoxidizes the H2 developed by the nitrogenase. The Nif phenotype of the mutant strain showed a slight decrease of acetylene reduction compared to that of the wild type. PMID:10692368

  11. Response of photosynthetic systems to salinity stress in the desert cyanobacterium Scytonema javanicum

    NASA Astrophysics Data System (ADS)

    Hu, Jinlu; Jin, Liang; Wang, Xiaojuan; Cai, Wenkai; Liu, Yongding; Wang, Gaohong

    2014-01-01

    The present study investigated the physiological and biochemical characteristics of Scytonema javanicum, a pioneer species isolated from desert biological crusts, under salinity stress. Pigment analysis showed that salinity decreased chlorophyll a and phycocyanin content, while low salinity increased carotenoid concentration and high salinity decreased carotenoid concentration. Salinity also inhibited CO2 assimilation rate and photosynthetic oxygen evolution in this cyanobacterium. Chlorophyll a fluorescence transient parameters (φPo, φEo, ψO, RC/ABS, RC/CS, PIABS, and PICS) were decreased under salt stress, while dVo/dto(Mo), Vj and φDo were increased. The decrease of ETRmax and Yield and the change of chlorophyll a fluorescence transients showed that salt stress had an important influence on photosynthesis. These results indicated that the effects of salinity stress on photosynthesis in S. javanicum may depend on the inhibition of electron transport and the inactivation of the reaction centers, but this inhibition may occur in the electron transport pathway at the PSII donor and acceptor sites.

  12. Optimization of photobioreactor growth conditions for a cyanobacterium expressing mosquitocidal Bacillus thuringiensis Cry proteins.

    PubMed

    Ketseoglou, Irene; Bouwer, Gustav

    2013-08-10

    An Anabaena strain (PCC 7120#11) that was genetically engineered to express Bacillus thuringiensis subsp. israelensis cry genes has shown good larvicidal activity against Anopheles arabiensis, a major vector of malaria in Africa. Response surface methodology was used to evaluate the relationship between key growth factors and the volumetric productivity of PCC 7120#11 in an indoor, flat-plate photobioreactor. The interaction of input CO₂ concentration and airflow rate had a statistically significant effect on the volumetric productivity of PCC 7120#11, as did the interaction of airflow rate and photosynthetic photon flux density. Model-based numerical optimization indicated that the optimal factor level combination for maximizing PCC 7120#11 volumetric productivity was a photosynthetic photon flux density of 154 μmol m⁻² s⁻¹ and air enriched with 3.18% (v/v) CO₂ supplied at a flow rate of 1.02 vessel volumes per minute. At the levels evaluated in the study, none of the growth factors had a significant effect on the median lethal concentration of PCC 7120#11 against An. arabiensis larvae. This finding is important because loss of mosquitocidal activity under growth conditions that maximize volumetric productivity would impact on the feasibility of using PCC 7120#11 in malaria vector control programs. The study showed the usefulness of response surface methodology for determination of the optimal growth conditions for a cyanobacterium that is genetically engineered to have larvicidal activity against malaria vectors.

  13. Diazotrophic specific cytochrome c oxidase required to overcome light stress in the cyanobacterium Nostoc muscorum.

    PubMed

    Bhargava, Santosh; Chouhan, Shweta

    2016-01-01

    Diazotrophic, filamentous and heterocystous cyanobacterium Nostoc muscorum perform photosynthesis in vegetative whereas nitrogen fixation occurs in heterocyst only. However, despite their metabolic plasticity, respiration takes place both in vegetative cells and heterocysts. The role of the respiratory electron transport system and terminal oxidases under light stress is not evident so far. As compared to the diazotrophically grown cultures, the non-diazotrophically grown cultures of the N. muscorum show a slight decrease in their growth, chlorophyll a contents and photosynthetic O2 evolution under light stress. Whereas respiratory O2 uptake under identical stress condition increases several fold. Likewise, nitrogen fixing enzyme i.e. nitrogenase over-expresses itself under light stress condition. The terminal enzyme of respiratory electron transport chain i.e. cytochrome c oxidase shows more activity under light stress, whilst light stress has no impact on Ca(++)-dependent ATPase activity. This leads to the conclusion that under light stress, cytochrome c oxidase plays a vital role in mitigating given light stress. PMID:26712617

  14. Mathematical study of pattern formation accompanied by heterocyst differentiation in multicellular cyanobacterium.

    PubMed

    Ishihara, Jun-ichi; Tachikawa, Masashi; Iwasaki, Hideo; Mochizuki, Atsushi

    2015-04-21

    The filamentous cyanobacterium, Anabaena sp. PCC 7120, is one of the simplest models of a multicellular system showing cellular differentiation. In nitrogen-deprived culture, undifferentiated vegetative cells differentiate into heterocysts at ~10-cell intervals along the cellular filament. As undifferentiated cells divide, the number of cells between heterocysts (segment length) increases, and a new heterocyst appears in the intermediate region. To understand how the heterocyst pattern is formed and maintained, we constructed a one-dimensional cellular automaton (CA) model of the heterocyst pattern formation. The dynamics of vegetative cells is modeled by a stochastic transition process including cell division, differentiation and increase of cell age (maturation). Cell division and differentiation depend on the time elapsed after the last cell division, the "cell age". The model dynamics was mathematically analyzed by a two-step Markov approximation. In the first step, we determined steady state of cell age distribution among vegetative cell population. In the second step, we determined steady state distribution of segment length among segment population. The analytical solution was consistent with the results of numerical simulations. We then compared the analytical solution with the experimental data, and quantitatively estimated the immeasurable intercellular kinetics. We found that differentiation is initially independent of cellular maturation, but becomes dependent on maturation as the pattern formation evolves. Our mathematical model and analysis enabled us to quantify the internal cellular dynamics at various stages of the heterocyst pattern formation. PMID:25665721

  15. Fur-type transcriptional repressors and metal homeostasis in the cyanobacterium Synechococcus sp. PCC 7002

    PubMed Central

    Ludwig, Marcus; Chua, Tiing Tiing; Chew, Chyue Yie; Bryant, Donald A.

    2015-01-01

    Metal homeostasis is a crucial cellular function for nearly all organisms. Some heavy metals (e.g., Fe, Zn, Co, Mo) are essential because they serve as cofactors for enzymes or metalloproteins, and chlorophototrophs such as cyanobacteria have an especially high demand for iron. At excessive levels, however, metals become toxic to cyanobacteria. Therefore, a tight control mechanism is essential for metal homeostasis. Metal homeostasis in microorganisms comprises two elements: metal acquisition from the environment and detoxification or excretion of excess metal ions. Different families of metal-sensing regulators exist in cyanobacteria and each addresses a more or less specific set of target genes. In this study the regulons of three Fur-type and two ArsR-SmtB-type regulators were investigated in a comparative approach in the cyanobacterium Synechococcus sp. PCC 7002. One Fur-type regulator controls genes for iron acquisition (Fur); one controls genes for zinc acquisition (Zur); and the third controls two genes involved in oxidative stress (Per). Compared to other well-investigated cyanobacterial strains, however, the set of target genes for each regulator is relatively small. Target genes for the two ArsR-SmtB transcriptional repressors (SmtB (SYNPCC7002_A2564) and SYNPCC7002_A0590) are involved in zinc homeostasis in addition to Zur. Their target genes, however, are less specific for zinc and point to roles in a broader heavy metal detoxification response. PMID:26582412

  16. Characterization and evolution of tetrameric photosystem I from the thermophilic cyanobacterium Chroococcidiopsis sp TS-821.

    PubMed

    Li, Meng; Semchonok, Dmitry A; Boekema, Egbert J; Bruce, Barry D

    2014-03-01

    Photosystem I (PSI) is a reaction center associated with oxygenic photosynthesis. Unlike the monomeric reaction centers in green and purple bacteria, PSI forms trimeric complexes in most cyanobacteria with a 3-fold rotational symmetry that is primarily stabilized via adjacent PsaL subunits; however, in plants/algae, PSI is monomeric. In this study, we discovered a tetrameric form of PSI in the thermophilic cyanobacterium Chroococcidiopsis sp TS-821 (TS-821). In TS-821, PSI forms tetrameric and dimeric species. We investigated these species by Blue Native PAGE, Suc density gradient centrifugation, 77K fluorescence, circular dichroism, and single-particle analysis. Transmission electron microscopy analysis of native membranes confirms the presence of the tetrameric PSI structure prior to detergent solubilization. To investigate why TS-821 forms tetramers instead of trimers, we cloned and analyzed its psaL gene. Interestingly, this gene product contains a short insert between the second and third predicted transmembrane helices. Phylogenetic analysis based on PsaL protein sequences shows that TS-821 is closely related to heterocyst-forming cyanobacteria, some of which also have a tetrameric form of PSI. These results are discussed in light of chloroplast evolution, and we propose that PSI evolved stepwise from a trimeric form to tetrameric oligomer en route to becoming monomeric in plants/algae. PMID:24681621

  17. Production of indole-3-acetic acid by the cyanobacterium Arthrospira platensis strain MMG-9.

    PubMed

    Ahmed, Mehboob; Stal, Lucas; Hasnain, Shahida

    2010-09-01

    The filamentous cyanobacterium Arthrospira platensis strain MMG-9 was isolated from a rice field. The ability of this strain to synthesize the bioactive compound indole-3-acetic acid (IAA) was demonstrated. IAA was extracted from the culture A. platensis strain MMG-9 and its identity was confirmed by thin layer chromatography (TLC) as well as by high performance liquid chromatography (HPLC). The IAA precursor L-tryptophan was required for IAA biosynthesis. Released IAA increased with the increase of the initial concentration of L-tryptophan in the medium and with the incubation time. A. platensis strain MMG-9 accumulates more IAA than it released it into the medium. The bioactivity of the secreted IAA was shown by its effect on the formation of roots by Pisum sativum. There was a significant positive effect of the supernatant of cultures of A. platensis strain MMG-9 on the number of lateral roots of P. sativum while a negative effect on root length was observed. PMID:20890089

  18. Anaerobic biosynthesis of unsaturated fatty acids in the cyanobacterium, Oscillatoria limnetica

    NASA Technical Reports Server (NTRS)

    Jahnke, L. L.; Lee, B.; Sweeney, M. J.; Klein, H. P.

    1989-01-01

    The mechanism for synthesis of monounsaturated fatty acids under aerobic and anaerobic conditions was studied in the facultative anaerobic cyanobacterium, Oscillatoria limnetica. The hexadecenoic acid (C16:1) of aerobically grown O. limnetica was shown to contain both the delta 7 (79%) and delta 9 (21%) isomers, while the octadecenoic (C18:1) acid was entirely the delta 9 acid. Incorporation of [2-14C] acetate into the fatty acids under aerobic conditions resulted in synthesis of the delta 7 and delta 9 C16:1 and the delta 9 C18:1. Synthesis of unsaturated fatty acids in the presence of DCMU required sulfide. Anaerobic incubations in the presence of DCMU and sulfide (less than 0.003% atmospheric oxygen) resulted in a two-fold increase in monounsaturated fatty acids of both delta 7 and delta 9 C16:1 and delta 9 and delta 11 C18:1. The synthesis of these is characteristic of a bacterial-type, anaerobic pathway.

  19. Characterization of red-shifted phycobilisomes isolated from the chlorophyll f-containing cyanobacterium Halomicronema hongdechloris.

    PubMed

    Li, Yaqiong; Lin, Yuankui; Garvey, Christopher J; Birch, Debra; Corkery, Robert W; Loughlin, Patrick C; Scheer, Hugo; Willows, Robert D; Chen, Min

    2016-01-01

    Phycobilisomes are the main light-harvesting protein complexes in cyanobacteria and some algae. It is commonly accepted that these complexes only absorb green and orange light, complementing chlorophyll absorbance. Here, we present a new phycobilisome derived complex that consists only of allophycocyanin core subunits, having red-shifted absorption peaks of 653 and 712 nm. These red-shifted phycobiliprotein complexes were isolated from the chlorophyll f-containing cyanobacterium, Halomicronema hongdechloris, grown under monochromatic 730 nm-wavelength (far-red) light. The 3D model obtained from single particle analysis reveals a double disk assembly of 120-145 Å with two α/β allophycocyanin trimers fitting into the two separated disks. They are significantly smaller than typical phycobilisomes formed from allophycocyanin subunits and core-membrane linker proteins, which fit well with a reduced distance between thylakoid membranes observed from cells grown under far-red light. Spectral analysis of the dissociated and denatured phycobiliprotein complexes grown under both these light conditions shows that the same bilin chromophore, phycocyanobilin, is exclusively used. Our findings show that red-shifted phycobilisomes are required for assisting efficient far-red light harvesting. Their discovery provides new insights into the molecular mechanisms of light harvesting under extreme conditions for photosynthesis, as well as the strategies involved in flexible chromatic acclimation to diverse light conditions.

  20. Apratoxin H and apratoxin A sulfoxide from the Red Sea cyanobacterium Moorea producens.

    PubMed

    Thornburg, Christopher C; Cowley, Elise S; Sikorska, Justyna; Shaala, Lamiaa A; Ishmael, Jane E; Youssef, Diaa T A; McPhail, Kerry L

    2013-09-27

    Cultivation of the marine cyanobacterium Moorea producens, collected from the Nabq Mangroves in the Gulf of Aqaba (Red Sea), led to the isolation of new apratoxin analogues apratoxin H (1) and apratoxin A sulfoxide (2), together with the known apratoxins A-C, lyngbyabellin B, and hectochlorin. The absolute configuration of these new potent cytotoxins was determined by chemical degradation, MS, NMR, and CD spectroscopy. Apratoxin H (1) contains pipecolic acid in place of the proline residue present in apratoxin A, expanding the known suite of naturally occurring analogues that display amino acid substitutions within the final module of the apratoxin biosynthetic pathway. The oxidation site of apratoxin A sulfoxide (2) was deduced from MS fragmentation patterns and IR data, and 2 could not be generated experimentally by oxidation of apratoxin A. The cytotoxicity of 1 and 2 to human NCI-H460 lung cancer cells (IC₅₀ = 3.4 and 89.9 nM, respectively) provides further insight into the structure-activity relationships in the apratoxin series. Phylogenetic analysis of the apratoxin-producing cyanobacterial strains belonging to the genus Moorea, coupled with the recently annotated apratoxin biosynthetic pathway, supports the notion that apratoxin production and structural diversity may be specific to their geographical niche.

  1. Proteome-Wide Analysis and Diel Proteomic Profiling of the Cyanobacterium Arthrospira platensis PCC 8005

    PubMed Central

    Matallana-Surget, Sabine; Derock, Jérémy; Leroy, Baptiste; Badri, Hanène; Deschoenmaeker, Frédéric; Wattiez, Ruddy

    2014-01-01

    The filamentous cyanobacterium Arthrospira platensis has a long history of use as a food supply and it has been used by the European Space Agency in the MELiSSA project, an artificial microecosystem which supports life during long-term manned space missions. This study assesses progress in the field of cyanobacterial shotgun proteomics and light/dark diurnal cycles by focusing on Arthrospira platensis. Several fractionation workflows including gel-free and gel-based protein/peptide fractionation procedures were used and combined with LC-MS/MS analysis, enabling the overall identification of 1306 proteins, which represents 21% coverage of the theoretical proteome. A total of 30 proteins were found to be significantly differentially regulated under light/dark growth transition. Interestingly, most of the proteins showing differential abundance were related to photosynthesis, the Calvin cycle and translation processes. A novel aspect and major achievement of this work is the successful improvement of the cyanobacterial proteome coverage using a 3D LC-MS/MS approach, based on an immobilized metal affinity chromatography, a suitable tool that enabled us to eliminate the most abundant protein, the allophycocyanin. We also demonstrated that cell growth follows a light/dark cycle in A. platensis. This preliminary proteomic study has highlighted new characteristics of the Arthrospira platensis proteome in terms of diurnal regulation. PMID:24914774

  2. Effects of Iron Starvation on the Physiology of the Cyanobacterium Agmenellum quadruplicatum

    PubMed Central

    Hardie, L. P.; Balkwill, D. L.; Stevens, S. E.

    1983-01-01

    The effects of iron starvation on the growth and physiology of the unicellular cyanobacterium Agmenellum quadruplicatum were studied. Uptake of iron from the medium did not occur at a constant rate. The majority of the iron was removed at two different times, when the cells were initially inoculated into the medium and after the cultures had become quite dense and had stopped growing. Iron became limiting for growth 16 h after transfer to an iron-deficient medium, but cultures retained full viability for at least 212 h. Once iron became limiting, c-phycocyanin and chlorophyll a were degraded concurrently. This was followed by an accumulation of intracellular glucose in place of the c-phycocyanin. Nitrate and nitrite reductase activities were elevated through 50 h, after which they decreased steadily. The photosynthetic unit size also increased through 50 h and then decreased. Once iron was restored to the culture medium, growth resumed. The intracellular pigment levels increased rapidly as the glucose level diminished. PMID:16346259

  3. Diazotrophic specific cytochrome c oxidase required to overcome light stress in the cyanobacterium Nostoc muscorum.

    PubMed

    Bhargava, Santosh; Chouhan, Shweta

    2016-01-01

    Diazotrophic, filamentous and heterocystous cyanobacterium Nostoc muscorum perform photosynthesis in vegetative whereas nitrogen fixation occurs in heterocyst only. However, despite their metabolic plasticity, respiration takes place both in vegetative cells and heterocysts. The role of the respiratory electron transport system and terminal oxidases under light stress is not evident so far. As compared to the diazotrophically grown cultures, the non-diazotrophically grown cultures of the N. muscorum show a slight decrease in their growth, chlorophyll a contents and photosynthetic O2 evolution under light stress. Whereas respiratory O2 uptake under identical stress condition increases several fold. Likewise, nitrogen fixing enzyme i.e. nitrogenase over-expresses itself under light stress condition. The terminal enzyme of respiratory electron transport chain i.e. cytochrome c oxidase shows more activity under light stress, whilst light stress has no impact on Ca(++)-dependent ATPase activity. This leads to the conclusion that under light stress, cytochrome c oxidase plays a vital role in mitigating given light stress.

  4. Isolation and characterization of a new reported cyanobacterium Leptolyngbya bijugata coproducing odorous geosmin and 2-methylisoborneol.

    PubMed

    Wang, Zhongjie; Xiao, Peng; Song, Gaofei; Li, Yeguang; Li, Renhui

    2015-08-01

    The earthy-musty compounds geosmin and 2-methylisoborneol (MIB) produced by cyanobacteria are considered as the main biological causes of off-flavor events, especially in aquatic ecosystems. More than 50 filamentous cyanobacteria species have been documented as geosmin or MIB producers; however, little is known about the species coproducing these two metabolites. In this study, an epiphytic sample was collected from a river in Hubei, China. Three isolated strains (A2, B2, and B4) producing earthy odors were successfully isolated and identified as the cyanobacterium Leptolyngbya bijugata Anagnostidis et Komárek 1988 based on morphology and 16S rDNA sequences. Gas chromatography analysis confirmed that the isolated L. bijugata strains were geosmin and MIB coproducers, with accumulation ranging from 13.6 to 22.4 and 12.3 to 57.5 μg L(-1), respectively. The partial fragments of geosmin and MIB synthesis genes in the L. bijugata strains were cloned and sequenced. Further sequences and phylogenetic analysis indicated the high conservation and a common origin of these genes in cyanobacteria. This study is the first to report and characterize the coproduction of geosmin and MIB by L. bijugata, representing a new source for potential risk of off-flavor events.

  5. The stringent response regulates adaptation to darkness in the cyanobacterium Synechococcus elongatus.

    PubMed

    Hood, Rachel D; Higgins, Sean A; Flamholz, Avi; Nichols, Robert J; Savage, David F

    2016-08-16

    The cyanobacterium Synechococcus elongatus relies upon photosynthesis to drive metabolism and growth. During darkness, Synechococcus stops growing, derives energy from its glycogen stores, and greatly decreases rates of macromolecular synthesis via unknown mechanisms. Here, we show that the stringent response, a stress response pathway whose genes are conserved across bacteria and plant plastids, contributes to this dark adaptation. Levels of the stringent response alarmone guanosine 3'-diphosphate 5'-diphosphate (ppGpp) rise after a shift from light to dark, indicating that darkness triggers the same response in cyanobacteria as starvation in heterotrophic bacteria. High levels of ppGpp are sufficient to stop growth and dramatically alter many aspects of cellular physiology, including levels of photosynthetic pigments and polyphosphate, DNA content, and the rate of translation. Cells unable to synthesize ppGpp display pronounced growth defects after exposure to darkness. The stringent response regulates expression of a number of genes in Synechococcus, including ribosomal hibernation promoting factor (hpf), which causes ribosomes to dimerize in the dark and may contribute to decreased translation. Although the metabolism of Synechococcus differentiates it from other model bacterial systems, the logic of the stringent response remains remarkably conserved, while at the same time having adapted to the unique stresses of the photosynthetic lifestyle. PMID:27486247

  6. Production, composition and Pb2+ adsorption characteristics of capsular polysaccharides extracted from a cyanobacterium Gloeocapsa gelatinosa.

    PubMed

    Raungsomboon, Suneerat; Chidthaisong, Amnat; Bunnag, Boosya; Inthorn, Duangrat; Harvey, Narumon W

    2006-12-01

    Pb2+ adsorption by the living cells of the cyanobacterium Gloeocapsa gelatinosa was studied. Cyanobacterial cells with intact capsular polysaccharide (CPS) showed 5.7 times higher Pb adsorption capacity than that of cells without CPS. The adsorbed Pb was desorbed by EDTA, indicating that Pb2+ adsorption occurred mainly on cell surface. Production, sugar content and ability of CPS to remove Pb2+ were then studied in details. CPS production by G. gelatinosa increased when culture time was prolonged. The maximum CPS production was 35.43 mg g(-1) dry weight after 30-day cultivation. Xylose, arabinose, ribose, rhamnose, galactose, glucose, mannose and fructose were the neutral sugars presented in CPS of G. gelatinosa. Acidic sugars including galacturonic and glucuronic acids were also found in CPS. The amount and composition of G. gelatinosa's CPS varied according to its growth phase and culture conditions. The highest amount of acidic sugars was produced when cultured under low light intensity. The extracted CPS rapidly removed Pb2+ from the solution (82.22+/-4.82 mg Pb2+ per g CPS), directly demonstrating its roles in binding Pb2+ ions. Its ability to remove Pb2+ rapidly and efficiently, to grow under sub-optimal conditions (such as low pH and low light intensity), and to produce high amount of CPS with acidic sugars, leads us to conclude that G. gelatinosa is a potential viable bioadsorber for mildly acidic water contaminated with Pb2+.

  7. Apratoxin H and Apratoxin A Sulfoxide from the Red Sea Cyanobacterium Moorea producens

    PubMed Central

    Thornburg, Christopher C.; Cowley, Elise S.; Sikorska, Justyna; Shaala, Lamiaa A.; Ishmael, Jane E.; Youssef, Diaa T.A.; McPhail, Kerry L.

    2014-01-01

    Cultivation of the marine cyanobacterium Moorea producens, collected from the Nabq Mangroves in the Gulf of Aqaba (Red Sea), led to the isolation of new apratoxin analogues, apratoxin H (1) and apratoxin A sulfoxide (2), together with the known apratoxins A-C, lyngbyabellin B and hectochlorin. The absolute configuration of these new potent cytotoxins was determined by chemical degradation, MS, NMR, and CD spectroscopy. Apratoxin H (1) contains pipecolic acid in place of the proline residue present in apratoxin A, expanding the known suite of naturally occurring analogues that display amino acid substitutions within the final module of the apratoxin biosynthetic pathway. The oxidation site of apratoxin A sulfoxide (2) was deduced from MS fragmentation patterns and IR data, and 2 could not be generated experimentally by oxidation of apratoxin A. The cytotoxicity of 1 and 2 to human NCI-H460 lung cancer cells (IC50 = 3.4 and 89.9 nM, respectively) provides further insight into the structure–activity relationships in the apratoxin series. Phylogenetic analysis of the apratoxin-producing cyanobacterial strains belonging to the genus Moorea, coupled with the recently annotated apratoxin biosynthetic pathway, supports the notion that apratoxin production and structural diversity may be specific to their geographical niche. PMID:24016099

  8. The antimicrobial profile of extracts of a Phormidium-like cyanobacterium changes with phosphate levels.

    PubMed

    El Semary, Nermin Adel

    2012-02-01

    The antimicrobial activity of lipophilic extracts of mat-forming Phormidium-like cyanobacterium isolated from Egypt was investigated under different phosphate concentrations. The antimicrobial profile changed with different phosphate levels indicating metabolic changes under stressful conditions. The fractions that resulted in highest antimicrobial activity from the three different phosphate concentrations were chosen for further analyses. The bioactive compounds were identified using chromatographic and spectroscopic techniques including UV, FTIR, GC-MS and proton-NMR. The chemical analyses indicated that the compound at standard phosphate concentration was eugenol whereas the bioactive compound at half phosphate concentration was 4-tert-butylcyclohexanol. The third bioactive compound at quarter phosphate concentration was octadecanoic acid. The eugenol is known for its antimicrobial as well as pain relief properties and can be used in many pharmaceutical preparations whereas the octadecanoic acid and cyclohexanol derivative are used in some antimicrobial pharmaceuticals. The study highlights the change in antimicrobial profile of bioactive compounds derived from cyanobacteria through manipulating the concentration of a key nutrient in growth medium. This strategy can be employed for mass production of these compounds and others for future biotechnological applications.

  9. Membrane development in the cyanobacterium, Anacystis nidulans, during recovery from iron starvation

    SciTech Connect

    Pakrasi, H.B.; Goldenberg, A.; Sherman, L.A.

    1985-09-01

    Deprivation of iron from the growth medium results in physiological as well as structural changes in the unicellular cyanobacterium Anacystis nidulans R2. Important among these changes are alterations in the composition and function of the photosynthetic membranes. Room-temperature absorption spectra of iron-starved cyanobacterial cells show a chlorophyll absorption peak at 672 nanometers, 7 nanometers blue-shifted from its normal position at 679 nanometers. Iron-starved cells have decreased amounts of chlorophyll and phycobilins. Their fluorescence spectra (77K) have one prominent chlorophyll emission peak at 684 nanometers as compared to three peaks at 687, 696, and 717 nanometers from normal cells. Chlorophyll-protein analysis of iron-deprived cells indicated the absence of high molecular weight bands. Addition of iron to iron-starved cells induced a restoration process in which new components were initially synthesized and integrated into preexisting membranes; at later times, new membranes were assembled and cell division commenced. Synthesis of chlorophyll and phycocyanins started almost immediately after the addition of iron. The origin of the fluorescence emission at 687 and 696 nanometers is discussed in relation to the specific chlorophyll-protein complexes formed during iron reconstitution. 26 references, 2 figures, 1 table.

  10. Type II Toxin-Antitoxin Systems in the Unicellular Cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Kopfmann, Stefan; Roesch, Stefanie K; Hess, Wolfgang R

    2016-01-01

    Bacterial toxin-antitoxin (TA) systems are genetic elements, which are encoded by plasmid as well as chromosomal loci. They mediate plasmid and genomic island maintenance through post-segregational killing mechanisms but may also have milder effects, acting as mobile stress response systems that help certain cells of a population in persisting adverse growth conditions. Very few cyanobacterial TA system have been characterized thus far. In this work, we focus on the cyanobacterium Synechocystis 6803, a widely used model organism. We expand the number of putative Type II TA systems from 36 to 69 plus seven stand-alone components. Forty-seven TA pairs are located on the chromosome and 22 are plasmid-located. Different types of toxins are associated with various antitoxins in a mix and match principle. According to protein domains and experimental data, 81% of all toxins in Synechocystis 6803 likely exhibit RNase activity, suggesting extensive potential for toxicity-related RNA degradation and toxin-mediated transcriptome remodeling. Of particular interest is the Ssr8013-Slr8014 system encoded on plasmid pSYSG, which is part of a larger defense island or the pSYSX system Slr6056-Slr6057, which is linked to a bacterial ubiquitin-like system. Consequently, Synechocystis 6803 is one of the most prolific sources of new information about these genetic elements. PMID:27455323

  11. Composition of the carbohydrate granules of the cyanobacterium, Cyanothece sp. strain ATCC 51142

    NASA Technical Reports Server (NTRS)

    Schneegurt, M. A.; Sherman, D. M.; Sherman, L. A.; Mitchell, C. A. (Principal Investigator)

    1997-01-01

    Cyanothece sp. strain ATCC 51142 is an aerobic, unicellular, diazotrophic cyanobacterium that temporally separates O2-sensitive N2 fixation from oxygenic photosynthesis. The energy and reducing power needed for N2 fixation appears to be generated by an active respiratory apparatus that utilizes the contents of large interthylakoidal carbohydrate granules. We report here on the carbohydrate and protein composition of the granules of Cyanothece sp. strain ATCC 51142. The carbohydrate component is a glucose homopolymer with branches every nine residues and is chemically identical to glycogen. Granule-associated protein fractions showed temporal changes in the number of proteins and their abundance during the metabolic oscillations observed under diazotrophic conditions. There also were temporal changes in the protein pattern of the granule-depleted supernatant fractions from diazotrophic cultures. None of the granule-associated proteins crossreacted with antisera directed against several glycogen-metabolizing enzymes or nitrogenase, although these proteins were tentatively identified in supernatant fractions. It is suggested that the granule-associated proteins are structural proteins required to maintain a complex granule architecture.

  12. Cylindrofridins A-C, Linear Cylindrocyclophane-Related Alkylresorcinols from the Cyanobacterium Cylindrospermum stagnale.

    PubMed

    Preisitsch, Michael; Niedermeyer, Timo H J; Heiden, Stefan E; Neidhardt, Inga; Kumpfmüller, Jana; Wurster, Martina; Harmrolfs, Kirsten; Wiesner, Christoph; Enke, Heike; Müller, Rolf; Mundt, Sabine

    2016-01-22

    A rapid and exhaustive one-step biomass extraction as well as an enrichment and cleanup procedure has been developed for HPLC-UV detection and quantification of closely related [7.7]paracyclophanes and structural derivatives based on a two-phase solvent system. The procedure has been validated using the biomass of the carbamidocyclophane- and cylindrocyclophane-producing cyanobacterium Nostoc sp. CAVN2 and was utilized to perform a screening comprising 102 cyanobacterial strains. As a result, three new cylindrocyclophane-related alkylresorcinols, cylindrofridins A-C (1-3), and known cylindrocyclophanes (4-6) were detected and isolated from Cylindrospermum stagnale PCC 7417. Structures of 1-3 were elucidated by a combination of 1D and 2D NMR experiments, HRMS, and ECD spectroscopy. Cylindrofridin A (1) is the first naturally occurring [7.7]paracyclophane-related monomeric derivative. In contrast, cylindrofridins B (2) and C (3) represent dimers related to 1. Due to chlorination at the alkyl carbon atom in 1-3, the site of [7.7]paracyclophane macrocycle formation, the cylindrofridins represent linearized congeners of the cylindrocyclophanes. Compounds 1-3 were not toxic against nontumorigenic HaCaT cells (IC50 values >25 μM) compared to the respective cylindrocyclophanes, but 1 was the only cylindrofridin showing moderate activity against methicillin-resistant Staphylococcus aureus (MRSA) and Streptococcus pneumoniae with MIC values of 9 and 17 μM, respectively.

  13. Proteomic study of the peripheral proteins from thylakoid membranes of the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Wang, Y; Sun, J; Chitnis, P R

    2000-05-01

    Thylakoid membranes of cyanobacteria and plants contain enzymes that function in diverse metabolic reactions. Many of these enzymes and regulatory proteins are associated with the membranes as peripheral proteins. To identify these proteins, we separated and identified the peripheral proteins of thylakoid membranes of the cyanobacterium Synechocystis sp. PCC 6803. Trichloroacetic acid (TCA)-acetone extraction was used to enrich samples with peripheral proteins and to remove integral membrane proteins. The proteins were separated by two-dimensional electrophoresis (2-DE) and identified by peptide mass fingerprinting. More than 200 proteins were detected on the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gel that was stained with colloidal Coomassie blue. We analyzed 116 spots by peptide mass fingerprinting and identified 78 spots that were derived from 51 genes. Some proteins were found in multiple spots, indicating differential modifications resulting in charge differences. Therefore, a significant fraction of the peripheral proteins in thylakoid membranes is modified post-translationally. In our analysis, products of 17 hypothetical genes could be identified in the peripheral protein fraction. Therefore, proteomic analysis is a powerful tool to identify location of the products of hypothetical genes and to characterize complexity in gene expression due to post-translational modifications.

  14. Molecular weight determination of an active photosystem I preparation from a thermophilic cyanobacterium, Synechococcus elongatus.

    PubMed

    Schafheutle, M E; Setliková, E; Timmins, P A; Johner, H; Gutgesell, P; Setlik, I; Welte, W

    1990-02-01

    An active photosystem I (PSI) complex was isolated from the thermophilic cyanobacterium Synechococcus elongatus by a procedure consisting of three steps: First, extraction of photosystem II from the thylakoids by a sulfobetaine detergent yields PSI-enriched membranes. Second, the latter are treated with Triton X-100 to extract PSI particles, which are further purified by preparative isoelectric focusing. Third, anion-exchange chromatography is used to remove contaminating phycobilisome polypeptides. The purified particles show three major bands in sodium dodecyl sulfate gel electrophoresis of apparent molecular mass of 110, 15, and 10 kDa. Charge separation was monitored by the kinetics of flash-induced absorption changes at 820 nm. A chlorophyll/P700 ratio of 60 was found. When the particles are stored at 4 degrees C, charge separation was stable for weeks. The molecular mass of the PSI particles, determined by measurement of zero-angle neutron scattering intensity, was 217,000 Da. The PSI particles thus consist of one heterodimer of the 60-80-kDa polypeptides and presumably one copy of the 15- and 10-kDa polypeptides, respectively.

  15. Hydrogen sulfide can inhibit and enhance oxygenic photosynthesis in a cyanobacterium from sulfidic springs.

    PubMed

    Klatt, Judith M; Haas, Sebastian; Yilmaz, Pelin; de Beer, Dirk; Polerecky, Lubos

    2015-09-01

    We used microsensors to investigate the combinatory effect of hydrogen sulfide (H2 S) and light on oxygenic photosynthesis in biofilms formed by a cyanobacterium from sulfidic springs. We found that photosynthesis was both positively and negatively affected by H2 S: (i) H2 S accelerated the recovery of photosynthesis after prolonged exposure to darkness and anoxia. We suggest that this is possibly due to regulatory effects of H2 S on photosystem I components and/or on the Calvin cycle. (ii) H2 S concentrations of up to 210 μM temporarily enhanced the photosynthetic rates at low irradiance. Modelling showed that this enhancement is plausibly based on changes in the light-harvesting efficiency. (iii) Above a certain light-dependent concentration threshold H2 S also acted as an inhibitor. Intriguingly, this inhibition was not instant but occurred only after a specific time interval that decreased with increasing light intensity. That photosynthesis is most sensitive to inhibition at high light intensities suggests that H2 S inactivates an intermediate of the oxygen evolving complex that accumulates with increasing light intensity. We discuss the implications of these three effects of H2 S in the context of cyanobacterial photosynthesis under conditions with diurnally fluctuating light and H2 S concentrations, such as those occurring in microbial mats and biofilms.

  16. Anoxygenic photosynthesis controls oxygenic photosynthesis in a cyanobacterium from a sulfidic spring.

    PubMed

    Klatt, Judith M; Al-Najjar, Mohammad A A; Yilmaz, Pelin; Lavik, Gaute; de Beer, Dirk; Polerecky, Lubos

    2015-03-01

    Before the Earth's complete oxygenation (0.58 to 0.55 billion years [Ga] ago), the photic zone of the Proterozoic oceans was probably redox stratified, with a slightly aerobic, nutrient-limited upper layer above a light-limited layer that tended toward euxinia. In such oceans, cyanobacteria capable of both oxygenic and sulfide-driven anoxygenic photosynthesis played a fundamental role in the global carbon, oxygen, and sulfur cycle. We have isolated a cyanobacterium, Pseudanabaena strain FS39, in which this versatility is still conserved, and we show that the transition between the two photosynthetic modes follows a surprisingly simple kinetic regulation controlled by this organism's affinity for H2S. Specifically, oxygenic photosynthesis is performed in addition to anoxygenic photosynthesis only when H2S becomes limiting and its concentration decreases below a threshold that increases predictably with the available ambient light. The carbon-based growth rates during oxygenic and anoxygenic photosynthesis were similar. However, Pseudanabaena FS39 additionally assimilated NO3 (-) during anoxygenic photosynthesis. Thus, the transition between anoxygenic and oxygenic photosynthesis was accompanied by a shift of the C/N ratio of the total bulk biomass. These mechanisms offer new insights into the way in which, despite nutrient limitation in the oxic photic zone in the mid-Proterozoic oceans, versatile cyanobacteria might have promoted oxygenic photosynthesis and total primary productivity, a key step that enabled the complete oxygenation of our planet and the subsequent diversification of life.

  17. Interplay between gold nanoparticle biosynthesis and metabolic activity of cyanobacterium Synechocystis sp. PCC 6803

    NASA Astrophysics Data System (ADS)

    Focsan, Monica; Ardelean, Ioan I.; Craciun, Constantin; Astilean, Simion

    2011-12-01

    Many microorganisms have long been known to be able to synthesize nanoparticles either in extracellular media or inside cells but the biochemical mechanisms involved in biomineralization are still poorly understood. In this paper we report the intracellular synthesis of gold nanoparticles (GNPs) by the cyanobacterium Synechocystis sp. PCC 6803 exposed to an aqueous solution of chloroauric acid. We assess the interplay between the biomineralization process and the metabolic activities (i.e. photosynthesis and respiration) of cyanobacteria cells by correlating the GNP synthesis yield with the amount of respiratory and photosynthetic oxygen exchange. The biogenic GNPs are compared in terms of their internalization and biological effects to GNPs synthesized by a standard citrate reduction procedure (cGNPs). The TEM analysis, in conjunction with spectroscopic measurements (i.e. surface plasmon resonance, fluorescence quenching and surface-enhanced Raman scattering, SERS), reveals the localization of biogenic GNPs at the level of intracytoplasmic membranes whereas the pre-formed cGNPs are located at the level of external cellular membrane. Our findings have implications for better understanding the process of biomineralization and assessing the potential risks associated with the accumulation of nanomaterials by various biological systems.

  18. Intercellular transfer along the trichomes of the invasive terminal heterocyst forming cyanobacterium Cylindrospermopsis raciborskii CS-505.

    PubMed

    Plominsky, Álvaro M; Delherbe, Nathalie; Mandakovic, Dinka; Riquelme, Brenda; González, Karen; Bergman, Birgitta; Mariscal, Vicente; Vásquez, Mónica

    2015-03-01

    Cylindrospermopsis raciborskii CS-505 is an invasive freshwater filamentous cyanobacterium that when grown diazotrophically may develop trichomes of up to 100 vegetative cells while differentiating only two end heterocysts, the sole sites for their N2-fixation process. We examined the diazotrophic growth and intercellular transfer mechanisms in C. raciborskii CS-505. Subjecting cultures to a combined-nitrogen-free medium to elicit N2 fixation, the trichome length remained unaffected while growth rates decreased. The structures and proteins for intercellular communication showed that while a continuous periplasmic space was apparent along the trichomes, the putative septal junction sepJ gene is divided into two open reading frames and lacks several transmembrane domains unlike the situation in Anabaena, differentiating a 5-fold higher frequency of heterocysts. FRAP analyses also showed that the dyes calcein and 5-CFDA were taken up by heterocysts and vegetative cells, and that the transfer from heterocysts and 'terminal' vegetative cells showed considerably higher transfer rates than that from vegetative cells located in the middle of the trichomes. The data suggest that C. raciborskii CS-505 compensates its low-frequency heterocyst phenotype by a highly efficient transfer of the fixed nitrogen towards cells in distal parts of the trichomes (growing rapidly) while cells in central parts suffers (slow growth). PMID:25757729

  19. Nostopeptolide plays a governing role during cellular differentiation of the symbiotic cyanobacterium Nostoc punctiforme

    PubMed Central

    Liaimer, Anton; Helfrich, Eric J. N.; Hinrichs, Katrin; Guljamow, Arthur; Ishida, Keishi; Hertweck, Christian; Dittmann, Elke

    2015-01-01

    Nostoc punctiforme is a versatile cyanobacterium that can live either independently or in symbiosis with plants from distinct taxa. Chemical cues from plants and N. punctiforme were shown to stimulate or repress, respectively, the differentiation of infectious motile filaments known as hormogonia. We have used a polyketide synthase mutant that accumulates an elevated amount of hormogonia as a tool to understand the effect of secondary metabolites on cellular differentiation of N. punctiforme. Applying MALDI imaging to illustrate the reprogramming of the secondary metabolome, nostopeptolides were identified as the predominant difference in the pks2− mutant secretome. Subsequent differentiation assays and visualization of cell-type-specific expression of nostopeptolides via a transcriptional reporter strain provided evidence for a multifaceted role of nostopeptolides, either as an autogenic hormogonium-repressing factor or as a chemoattractant, depending on its extracellular concentration. Although nostopeptolide is constitutively expressed in the free-living state, secreted levels dynamically change before, during, and after the hormogonium differentiation phase. The metabolite was found to be strictly down-regulated in symbiosis with Gunnera manicata and Blasia pusilla, whereas other metabolites are up-regulated, as demonstrated via MALDI imaging, suggesting plants modulate the fine-balanced cross-talk network of secondary metabolites within N. punctiforme. PMID:25624477

  20. An integrative approach to energy, carbon, and redox metabolism in the cyanobacterium Synechocystis sp. PCC 6803

    SciTech Connect

    Vermaas, Willem F.J.

    2006-03-14

    The broader goal of this project was to merge knowledge from genomic, metabolic, ultrastructural and other perspectives to understand how cyanobacteria live, adapt and are regulated. This understanding aids in metabolic engineering and synthetic biology efforts using this group of organisms that contribute greatly to global photosynthetic CO2 fixation and that are closely related to the ancestors of chloroplasts. This project focused on photosynthesis and respiration in the cyanobacterium Synechocystis sp. PCC 6803, which is spontaneously transformable and has a known genome sequence. Modification of these fundamental processes in this organism can lead to improved carbon sequestration and hydrogen production, as well as to generation of high-quality biomass. In our GTL-supported studies at Arizona State University we focus on cell structure and cell physiology in Synechocystis, with particular emphasis on thylakoid membrane formation and on metabolism related to photosynthesis and respiration. Results on (a) thylakoid membrane biogenesis, (b) fluxes through central carbon utilization pathways, and (c) distribution mechanisms between carbon storage compounds are presented. Together, these results help pave the way for metabolic engineering efforts that are likely to result in improved solar-powered carbon sequestration and bioenergy conversion. Fueled by the very encouraging results obtained in this project, we already have attracted interest from major companies in the use of cyanobacteria for biofuel production.

  1. Cytoplasmic membrane changes during adaptation of the fresh water cyanobacterium Synechococcus 6311 to salinity

    NASA Technical Reports Server (NTRS)

    Lefort-Tran, M.; Pouphile, M.; Spath, S.; Packer, L.

    1988-01-01

    In this investigation, changes were characterized in cell structure and cytoplasmic membrane organization that occur when the freshwater cyanobacterium Synechococcus 6311 is transferred from 'low salt' (0.03 molar NaCl) to 'high salt' (0.5 molar NaCl) media (i.e. sea water concentration). Cells were examined at several time points after the imposition of the salt stress and compared to control cells, in thin sections and freeze fracture electron microscopy, and by flow cytometry. One minute after exposure to high salt, i.e. 'salt shock', virtually all intracellular granules disappeared, the density of the cytoplasm decreased, and the appearance of DNA material was changed. Glycogen and other granules, however, reappeared by 4 hours after salt exposure. The organization of the cytoplasmic membrane undergoes major reorganization following salt shock. Freeze-fracture electron microscopy showed that small intramembrane particles (diameter 7.5 and 8.5 nanometers) are reduced in number by two- to fivefold, whereas large particles, (diameters 14.5 and 17.5 nanometers) increase two- to fourfold in frequency, compared to control cells grown in low salt medium. The changes in particle size distribution suggest synthesis of new membrane proteins, in agreement with the known increases in respiration, cytochrome oxidase, and sodium proton exchange activity of the cytoplasmic membrane.

  2. Anoxygenic photosynthesis controls oxygenic photosynthesis in a cyanobacterium from a sulfidic spring.

    PubMed

    Klatt, Judith M; Al-Najjar, Mohammad A A; Yilmaz, Pelin; Lavik, Gaute; de Beer, Dirk; Polerecky, Lubos

    2015-03-01

    Before the Earth's complete oxygenation (0.58 to 0.55 billion years [Ga] ago), the photic zone of the Proterozoic oceans was probably redox stratified, with a slightly aerobic, nutrient-limited upper layer above a light-limited layer that tended toward euxinia. In such oceans, cyanobacteria capable of both oxygenic and sulfide-driven anoxygenic photosynthesis played a fundamental role in the global carbon, oxygen, and sulfur cycle. We have isolated a cyanobacterium, Pseudanabaena strain FS39, in which this versatility is still conserved, and we show that the transition between the two photosynthetic modes follows a surprisingly simple kinetic regulation controlled by this organism's affinity for H2S. Specifically, oxygenic photosynthesis is performed in addition to anoxygenic photosynthesis only when H2S becomes limiting and its concentration decreases below a threshold that increases predictably with the available ambient light. The carbon-based growth rates during oxygenic and anoxygenic photosynthesis were similar. However, Pseudanabaena FS39 additionally assimilated NO3 (-) during anoxygenic photosynthesis. Thus, the transition between anoxygenic and oxygenic photosynthesis was accompanied by a shift of the C/N ratio of the total bulk biomass. These mechanisms offer new insights into the way in which, despite nutrient limitation in the oxic photic zone in the mid-Proterozoic oceans, versatile cyanobacteria might have promoted oxygenic photosynthesis and total primary productivity, a key step that enabled the complete oxygenation of our planet and the subsequent diversification of life. PMID:25576611

  3. Advances in the Function and Regulation of Hydrogenase in the Cyanobacterium Synechocystis PCC6803

    PubMed Central

    Cassier-Chauvat, Corinne; Veaudor, Théo; Chauvat, Franck

    2014-01-01

    In order to use cyanobacteria for the biological production of hydrogen, it is important to thoroughly study the function and the regulation of the hydrogen-production machine in order to better understand its role in the global cell metabolism and identify bottlenecks limiting H2 production. Most of the recent advances in our understanding of the bidirectional [Ni-Fe] hydrogenase (Hox) came from investigations performed in the widely-used model cyanobacterium Synechocystis PCC6803 where Hox is the sole enzyme capable of combining electrons with protons to produce H2 under specific conditions. Recent findings suggested that the Hox enzyme can receive electrons from not only NAD(P)H as usually shown, but also, or even preferentially, from ferredoxin. Furthermore, plasmid-encoded functions and glutathionylation (the formation of a mixed-disulfide between the cysteines residues of a protein and the cysteine residue of glutathione) are proposed as possible new players in the function and regulation of hydrogen production. PMID:25365180

  4. Diurnal Regulation of Cellular Processes in the Cyanobacterium Synechocystis sp. Strain PCC 6803: Insights from Transcriptomic, Fluxomic, and Physiological Analyses

    PubMed Central

    Saha, Rajib; Liu, Deng; Hoynes-O’Connor, Allison; Liberton, Michelle; Yu, Jingjie; Bhattacharyya-Pakrasi, Maitrayee; Balassy, Andrea; Zhang, Fuzhong; Maranas, Costas D.

    2016-01-01

    ABSTRACT Synechocystis sp. strain PCC 6803 is the most widely studied model cyanobacterium, with a well-developed omics level knowledgebase. Like the lifestyles of other cyanobacteria, that of Synechocystis PCC 6803 is tuned to diurnal changes in light intensity. In this study, we analyzed the expression patterns of all of the genes of this cyanobacterium over two consecutive diurnal periods. Using stringent criteria, we determined that the transcript levels of nearly 40% of the genes in Synechocystis PCC 6803 show robust diurnal oscillating behavior, with a majority of the transcripts being upregulated during the early light period. Such transcripts corresponded to a wide array of cellular processes, such as light harvesting, photosynthetic light and dark reactions, and central carbon metabolism. In contrast, transcripts of membrane transporters for transition metals involved in the photosynthetic electron transport chain (e.g., iron, manganese, and copper) were significantly upregulated during the late dark period. Thus, the pattern of global gene expression led to the development of two distinct transcriptional networks of coregulated oscillatory genes. These networks help describe how Synechocystis PCC 6803 regulates its metabolism toward the end of the dark period in anticipation of efficient photosynthesis during the early light period. Furthermore, in silico flux prediction of important cellular processes and experimental measurements of cellular ATP, NADP(H), and glycogen levels showed how this diurnal behavior influences its metabolic characteristics. In particular, NADPH/NADP+ showed a strong correlation with the majority of the genes whose expression peaks in the light. We conclude that this ratio is a key endogenous determinant of the diurnal behavior of this cyanobacterium. PMID:27143387

  5. Using recombinant cyanobacterium (Synechococcus elongatus) with increased carbohydrate productivity as feedstock for bioethanol production via separate hydrolysis and fermentation process.

    PubMed

    Chow, Te-Jin; Su, Hsiang-Yen; Tsai, Tsung-Yu; Chou, Hsiang-Hui; Lee, Tse-Min; Chang, Jo-Shu

    2015-05-01

    In this work, a recombinant cyanobacterium strain with increased photosynthesis rate, cell growth and carbohydrate production efficiency was genetically engineered by co-expressing ictB, ecaA, and acsAB (encoded for bacterial cellulose) in Synechococcus elongatus PCC7942. The resulting cyanobacterial biomass could be effectively hydrolyzed with dilute acid (2% sulfuric acid), achieving a nearly 90% glucose recovery at a biomass concentration of 80 g/L. Bioethanol can be produced from fermenting the acidic hydrolysate of S. elongatus PCC7942 via separate hydrolysis and fermentation (SHF) process at a concentration of 7.2 g/L and with a 91% theoretical yield.

  6. Characterization of three putative xylulose 5-phosphate/fructose 6-phosphate phosphoketolases in the cyanobacterium Anabaena sp. PCC 7120.

    PubMed

    Moriyama, Takashi; Tajima, Naoyuki; Sekine, Kohsuke; Sato, Naoki

    2015-01-01

    Xylulose 5-phosphate/fructose 6-phosphate phosphoketolase (Xfp) is a key enzyme in the central carbohydrate metabolism in heterofermentative bacteria, in which enzymatic property of Xfps is well characterized. This is not the case in other microbes. The cyanobacterium Anabaena sp. PCC 7120 possesses three putative genes encoding Xfp, all1483, all2567, and alr1850. We purified three putative Xfps as recombinant proteins. The results of gel filtration indicated that these proteins form homomultimer complex. All1483 and All2567 showed phosphoketolase activity, whereas Alr1850 did not show the activity. Kinetic analyses demonstrated that substrates, fructose 6-phosphate and inorganic phosphate, are cooperatively bound to enzymes positively and negatively, respectively.

  7. Ultrastructure of the fresh water cyanobacterium Anabaena variabilis SPU 003 and its application for oxygen-free hydrogen production.

    PubMed

    Shah, V; Garg, N; Madamwar, D

    2001-01-01

    Photoproduction of hydrogen has been studied as one of the ways to produce a clean, renewable energy source. Ultrastructure of the selected strain Anabaena variabilis SPU 003, a heterocystous cyanobacterium, has been done to understand the cell structure. The organism was found to be essentially a dark hydrogen producer. While pH had no significant effect on hydrogen production, optimum temperature was found to be 30 degrees C. Various sugars increased the production of hydrogen while the presence of various nitrogen sources inhibits the production. The production of hydrogen is highly sensitive to salinity and micronutrients.

  8. Isolation and structure of the cytotoxin lyngbyabellin B and absolute configuration of lyngbyapeptin A from the marine cyanobacterium Lyngbya majuscula.

    PubMed

    Luesch, H; Yoshida, W Y; Moore, R E; Paul, V J

    2000-10-01

    An analogue of the potent microfilament-disrupter lyngbyabellin A (1) has been isolated as a minor metabolite from the marine cyanobacterium Lyngbya majuscula collected at Apra Harbor, Guam. It possesses slightly weaker cytotoxicity than 1 and has been named lyngbyabellin B (2). Primarily NMR spectroscopy was used to determine its structure. The absolute configuration of 2 has been ascertained by chiral HPLC analysis of degradation products and by comparison with lyngbyabellin A (1). The known modified tetrapeptide lyngbyapeptin A (3) has also been found in the same extract, and its absolute stereochemistry could be determined for the first time.

  9. [Methods for prevention of mass development of the cyanobacterium Microcystis aeruginosa Kutz emend. Elenk. in aquatic ecosystems].

    PubMed

    Kolmakov, V I

    2006-01-01

    Methods for prevention of mass development of the cyanobacterium Microcystis aeruginosa Kutz emend. Elenk. in continental water bodies and industrial water supply systems are reviewed. The physicochemical, chemical, and biological methods for prevention of M. aeruginosa development in water bodies and water supply systems are considered; examples of successful inhibition of M. aeruginosa growth in laboratory experiments are demonstrated. The scientific problems are outlined that are to be solved for perfecting techniques for prevention of M. aeruginosa mass development in open water bodies and in closed water supply systems. PMID:16758860

  10. A requirement for EDTA in the separation of Photosystems 1 and 2 from the cyanobacterium Chlorogloea fritschii.

    PubMed

    Evans, E H; Pullin, C A

    1981-05-15

    Fractions enriched in Photosystem 1 or Photosystem 2 activity have been isolated from the cyanobacterium Chlorogloea fritschii after extraction of the membranes with digitonin and Triton X-100. Separation of the extract into the two components was achieved by using a Sepharose 6B column, calibration of which gave Kd values of 0.3 for the Photosystem 1 fraction and 0.53 for Photosystem 2. These values corresponded to molecular weights of approx. 500000 and 90000 respectively. The Photosystem 1 particle was shown to aggregate on storage and EDTA was shown to be necessary to separate the Photosystem 1 and 2 fractions.

  11. Highly plastic genome of Microcystis aeruginosa PCC 7806, a ubiquitous toxic freshwater cyanobacterium

    PubMed Central

    Frangeul, Lionel; Quillardet, Philippe; Castets, Anne-Marie; Humbert, Jean-François; Matthijs, Hans CP; Cortez, Diego; Tolonen, Andrew; Zhang, Cheng-Cai; Gribaldo, Simonetta; Kehr, Jan-Christoph; Zilliges, Yvonne; Ziemert, Nadine; Becker, Sven; Talla, Emmanuel; Latifi, Amel; Billault, Alain; Lepelletier, Anthony; Dittmann, Elke; Bouchier, Christiane; Tandeau de Marsac, Nicole

    2008-01-01

    Background The colonial cyanobacterium Microcystis proliferates in a wide range of freshwater ecosystems and is exposed to changing environmental factors during its life cycle. Microcystis blooms are often toxic, potentially fatal to animals and humans, and may cause environmental problems. There has been little investigation of the genomics of these cyanobacteria. Results Deciphering the 5,172,804 bp sequence of Microcystis aeruginosa PCC 7806 has revealed the high plasticity of its genome: 11.7% DNA repeats containing more than 1,000 bases, 6.8% putative transposases and 21 putative restriction enzymes. Compared to the genomes of other cyanobacterial lineages, strain PCC 7806 contains a large number of atypical genes that may have been acquired by lateral transfers. Metabolic pathways, such as fermentation and a methionine salvage pathway, have been identified, as have genes for programmed cell death that may be related to the rapid disappearance of Microcystis blooms in nature. Analysis of the PCC 7806 genome also reveals striking novel biosynthetic features that might help to elucidate the ecological impact of secondary metabolites and lead to the discovery of novel metabolites for new biotechnological applications. M. aeruginosa and other large cyanobacterial genomes exhibit a rapid loss of synteny in contrast to other microbial genomes. Conclusion Microcystis aeruginosa PCC 7806 appears to have adopted an evolutionary strategy relying on unusual genome plasticity to adapt to eutrophic freshwater ecosystems, a property shared by another strain of M. aeruginosa (NIES-843). Comparisons of the genomes of PCC 7806 and other cyanobacterial strains indicate that a similar strategy may have also been used by the marine strain Crocosphaera watsonii WH8501 to adapt to other ecological niches, such as oligotrophic open oceans. PMID:18534010

  12. Characteristic oxidation behavior of β-cyclocitral from the cyanobacterium Microcystis.

    PubMed

    Tomita, Koji; Hasegawa, Masateru; Arii, Suzue; Tsuji, Kiyomi; Bober, Beata; Harada, Ken-Ichi

    2016-06-01

    The cyanobacterium Microcystis produces volatile organic compounds such as β-cyclocitral and 3-methyl-1-butanol. The lysis of cyanobacteria involving the blue color formation has been occasionally observed in a natural environment. In this study, we focused on the oxidation behavior of β-cyclocitral that contributed to the blue color formation in a natural environment and compared β-cyclocitral with a structurally related compound concerning its oxidation, acidification, and lytic behavior. The oxidation products of β-cyclocitral were identified by the addition of β-cyclocitral in water, in which 2,2,6-trimethylcyclohex-1-ene-1-yl formate and 2,2,6-trimethylcyclohexanone were structurally characterized. That is, β-cyclocitral was easily oxidized to produce the corresponding carboxylic acid and the enol ester in water without an oxidizing reagent, suggesting that this oxidation proceeded according to the Baeyer-Villiger oxidation. The oxidation behavior of β-cyclocitral in a laboratory was different from that in the natural environment, in which 2,2,6- trimethylcyclohexanone was detected at the highest amount in the natural environment, whereas the highest amount in the laboratory was β-cyclocitric acid. A comparison of β-cyclocitral with structurally similar aldehydes concerning the lytic behavior of a Microcystis strain and the acidification process indicated that only β-cyclocitral was easily oxidized. Furthermore, it was found that a blue color formation occurred between pH 5.5 and 6.5, suggesting that chlorophyll a and β-carotene are unstable and decomposed, whereas phycocyanin was stable to some extent in this range. The obtained results of the characteristic oxidation behavior of β-cyclocitral would contribute to a better understanding of the cyanobacterial life cycle.

  13. Efficient Gene Induction and Endogenous Gene Repression Systems for the Filamentous Cyanobacterium Anabaena sp. PCC 7120.

    PubMed

    Higo, Akiyoshi; Isu, Atsuko; Fukaya, Yuki; Hisabori, Toru

    2016-02-01

    In the last decade, many studies have been conducted to employ genetically engineered cyanobacteria in the production of various metabolites. However, the lack of a strict gene regulation system in cyanobacteria has hampered these attempts. The filamentous cyanobacterium Anabaena sp. PCC 7120 performs both nitrogen and carbon fixation and is, therefore, a good candidate organism for such production. To employ Anabaena cells for this purpose, we intended to develop artificial gene regulation systems to alter the cell metabolic pathways efficiently. We introduced into Anabaena a transcriptional repressor TetR, widely used in diverse organisms, and green fluorescent protein (GFP) as a reporter. We found that anhydrotetracycline (aTc) substantially induced GFP fluorescence in a concentration-dependent manner. By expressing tetR under the nitrate-specific promoter nirA, we successfully reduced the concentration of aTc required for the induction of gfp under nitrogen fixation conditions (to 10% of the concentration needed under nitrate-replete conditions). Further, we succeeded in the overexpression of GFP by depletion of nitrate without the inducer by means of promoter engineering of the nirA promoter. Moreover, we applied these gene regulation systems to a metabolic enzyme in Anabaena and successfully repressed glnA, the gene encoding glutamine synthetase that is essential for nitrogen assimilation in cyanobacteria, by expressing the small antisense RNA for glnA. Consequently, the ammonium production of an ammonium-excreting Anabaena mutant was significantly enhanced. We therefore conclude that the gene regulation systems developed in this study are useful tools for the regulation of metabolic enzymes and will help to increase the production of desired substances in Anabaena. PMID:26684202

  14. Radiation characteristics and effective optical properties of dumbbell-shaped cyanobacterium Synechocystis sp.

    NASA Astrophysics Data System (ADS)

    Heng, Ri-Liang; Pilon, Laurent

    2016-05-01

    This study presents experimental measurements of the radiation characteristics of unicellular freshwater cyanobacterium Synechocystis sp. during their exponential growth in F medium. Their scattering phase function at 633 nm average spectral absorption and scattering cross-sections between 400 and 750 nm were measured. In addition, an inverse method was used for retrieving the spectral effective complex index of refraction of overlapping or touching bispheres and quadspheres from their absorption and scattering cross-sections. The inverse method combines a genetic algorithm and a forward model based on Lorenz-Mie theory, treating bispheres and quadspheres as projected area and volume-equivalent coated spheres. The inverse method was successfully validated with numerically predicted average absorption and scattering cross-sections of suspensions consisting of bispheres and quadspheres, with realistic size distributions, using the T-matrix method. It was able to retrieve the monomers' complex index of refraction with size parameter up to 11, relative refraction index less than 1.3, and absorption index less than 0.1. Then, the inverse method was applied to retrieve the effective spectral complex index of refraction of Synechocystis sp. approximated as randomly oriented aggregates consisting of two overlapping homogeneous spheres. Both the measured absorption cross-section and the retrieved absorption index featured peaks at 435 and 676 nm corresponding to chlorophyll a, a peak at 625 nm corresponding to phycocyanin, and a shoulder around 485 nm corresponding to carotenoids. These results can be used to optimize and control light transfer in photobioreactors. The inverse method and the equivalent coated sphere model could be applied to other optically soft particles of similar morphologies.

  15. Triton X-114 phase fractionation of membrane proteins of the cyanobacterium Anacystis nidulans R2.

    PubMed

    Bricker, T M; Sherman, L A

    1984-11-15

    The thylakoid polypeptides of the cyanobacterium Anacystis nidulans R2 were analyzed by Triton X-114 phase fractionation [C. Bordier (1981) J. Biol. Chem. 256, 1604-1607, as adapted for photosynthetic membranes by T.M. Bricker and L.A. Sherman (1982) FEBS Lett. 149, 197-202]. In this procedure, polypeptides with extensive hydrophobic regions (i.e., intrinsic proteins) form mixed micelles with Triton X-114, and are separated from extrinsic proteins by temperature-mediated precipitation of the mixed Triton X-114-intrinsic protein micelles. The polypeptide pattern after phase fractionation was highly complementary, with 62 of the observed 110 polypeptide components partitioning into the Triton X-114-enriched fraction. Identified polypeptides fractionating into the Triton X-114 phase included the apoproteins for Photosystems I and II, cytochromes f and b6, and the herbicide-binding protein. Identified polypeptides fractioning into the Triton X-114-depleted (aqueous) phase included the large and small subunits of RuBp carboxylase, cytochromes c550 and c554, and ferredoxin. Enzymatic radioiodination of the photosynthetic membranes followed by Triton X-114 phase fractionation allowed direct identification of intrinsic polypeptide components which possess surface-exposed regions susceptible to radioiodination. The most prominent of these polypeptides was a 34-kDa component which was associated with photosystem II. This phase partitioning procedure has been particularly helpful in the clarification of the identity of the membrane-associated cytochromes, and of photosystem II components. When coupled with surface-probing techniques, this procedure is very useful in identifying intrinsic proteins which possess surface-exposed domains. Phase fractionation, in conjunction with the isolation of specific membrane components and complexes, has allowed the identification of many of the important intrinsic thylakoid membrane proteins of A. nidulans R2.

  16. Physical and chemical processes promoting dominance of the toxic cyanobacterium Cylindrospermopsis raciborskii

    NASA Astrophysics Data System (ADS)

    Burford, Michele A.; Davis, Timothy W.

    2011-07-01

    The freshwater cyanobacterium, Cylindrospermopsis raciborskii (Wo'oszyńska) Seenayya and Subba Raju is a common species in lakes and reservoirs globally. In some areas of the world it can produce cyto- and hepatotoxins (cylindrospermopsins, saxitoxins), making blooms of this species a serious health concern for humans. In the last 10-15 years, there has been a considerable body of research conducted on the ecology, physiology and toxin production of this species and this paper reviews these studies with a focus on the cylindrospermopsin (CYN)-producing strains. C. raciborskii has low light requirements, close to neutral buoyancy, and a wide temperature tolerance, giving it the capacity to grow in many lentic waterbodies. It also has a flexible strategy with respect to nitrogen (N) utilisation; being able to switch between utilising fixed and atmospheric N as sources of N fluctuate. Additionally this species has a high phosphate (DIP) affinity and storage capacity. Like many cyanobacteria, it also has the capacity to use dissolved organic phosphorus (DOP). Changes in nutrient concentrations, light levels and temperature have also been found to affect production of the toxin CYN by this species. However, optimal toxin production does not necessarily occur when growth rates are optimal. Additionally, different strains of C. raciborskii vary in their cell quota of CYN, making it difficult to predict toxin concentrations, based on C. raciborskii cell densities. In summary, the ecological flexibility of this organism means that controlling blooms of C. raciborskii is a difficult undertaking. However, improved understanding of factors promoting the species and toxin production by genetically capable strains will lead to improved predictive models of blooms.

  17. Efficient Gene Induction and Endogenous Gene Repression Systems for the Filamentous Cyanobacterium Anabaena sp. PCC 7120.

    PubMed

    Higo, Akiyoshi; Isu, Atsuko; Fukaya, Yuki; Hisabori, Toru

    2016-02-01

    In the last decade, many studies have been conducted to employ genetically engineered cyanobacteria in the production of various metabolites. However, the lack of a strict gene regulation system in cyanobacteria has hampered these attempts. The filamentous cyanobacterium Anabaena sp. PCC 7120 performs both nitrogen and carbon fixation and is, therefore, a good candidate organism for such production. To employ Anabaena cells for this purpose, we intended to develop artificial gene regulation systems to alter the cell metabolic pathways efficiently. We introduced into Anabaena a transcriptional repressor TetR, widely used in diverse organisms, and green fluorescent protein (GFP) as a reporter. We found that anhydrotetracycline (aTc) substantially induced GFP fluorescence in a concentration-dependent manner. By expressing tetR under the nitrate-specific promoter nirA, we successfully reduced the concentration of aTc required for the induction of gfp under nitrogen fixation conditions (to 10% of the concentration needed under nitrate-replete conditions). Further, we succeeded in the overexpression of GFP by depletion of nitrate without the inducer by means of promoter engineering of the nirA promoter. Moreover, we applied these gene regulation systems to a metabolic enzyme in Anabaena and successfully repressed glnA, the gene encoding glutamine synthetase that is essential for nitrogen assimilation in cyanobacteria, by expressing the small antisense RNA for glnA. Consequently, the ammonium production of an ammonium-excreting Anabaena mutant was significantly enhanced. We therefore conclude that the gene regulation systems developed in this study are useful tools for the regulation of metabolic enzymes and will help to increase the production of desired substances in Anabaena.

  18. Structural insight into photoactivation of an adenylate cyclase from a photosynthetic cyanobacterium

    PubMed Central

    Ohki, Mio; Sugiyama, Kanako; Kawai, Fumihiro; Tanaka, Hitomi; Nihei, Yuuki; Unzai, Satoru; Takebe, Masumi; Matsunaga, Shigeru; Adachi, Shin-ichi; Shibayama, Naoya; Zhou, Zhiwen; Koyama, Ryuta; Takahashi, Tetsuo; Tame, Jeremy R. H.; Iseki, Mineo; Park, Sam-Yong

    2016-01-01

    Cyclic-AMP is one of the most important second messengers, regulating many crucial cellular events in both prokaryotes and eukaryotes, and precise spatial and temporal control of cAMP levels by light shows great promise as a simple means of manipulating and studying numerous cell pathways and processes. The photoactivated adenylate cyclase (PAC) from the photosynthetic cyanobacterium Oscillatoria acuminata (OaPAC) is a small homodimer eminently suitable for this task, requiring only a simple flavin chromophore within a blue light using flavin (BLUF) domain. These domains, one of the most studied types of biological photoreceptor, respond to blue light and either regulate the activity of an attached enzyme domain or change its affinity for a repressor protein. BLUF domains were discovered through studies of photo-induced movements of Euglena gracilis, a unicellular flagellate, and gene expression in the purple bacterium Rhodobacter sphaeroides, but the precise details of light activation remain unknown. Here, we describe crystal structures and the light regulation mechanism of the previously undescribed OaPAC, showing a central coiled coil transmits changes from the light-sensing domains to the active sites with minimal structural rearrangement. Site-directed mutants show residues essential for signal transduction over 45 Å across the protein. The use of the protein in living human cells is demonstrated with cAMP-dependent luciferase, showing a rapid and stable response to light over many hours and activation cycles. The structures determined in this study will assist future efforts to create artificial light-regulated control modules as part of a general optogenetic toolkit. PMID:27247413

  19. Effects of a simulated martian UV flux on the cyanobacterium, Chroococcidiopsis sp. 029.

    PubMed

    Cockell, Charles S; Schuerger, Andrew C; Billi, Daniela; Friedmann, E Imre; Panitz, Corinna

    2005-04-01

    Dried monolayers of Chroococcidiopsis sp. 029, a desiccation-tolerant, endolithic cyanobacterium, were exposed to a simulated martian-surface UV and visible light flux, which may also approximate to the worst-case scenario for the Archean Earth. After 5 min, there was a 99% loss of cell viability, and there were no survivors after 30 min. However, this survival was approximately 10 times higher than that previously reported for Bacillus subtilis. We show that under 1 mm of rock, Chroococcidiopsis sp. could survive (and potentially grow) under the high martian UV flux if water and nutrient requirements for growth were met. In isolated cells, phycobilisomes and esterases remained intact hours after viability was lost. Esterase activity was reduced by 99% after a 1-h exposure, while 99% loss of autofluorescence required a 4-h exposure. However, cell morphology was not changed, and DNA was still detectable by 4',6-diamidino-2-phenylindole staining after an 8-h exposure (equivalent to approximately 1 day on Mars at the equator). Under 1 mm of simulant martian soil or gneiss, the effect of UV radiation could not be detected on esterase activity or autofluorescence after 4 h. These results show that under the intense martian UV flux the morphological signatures of life can persist even after viability, enzymatic activity, and pigmentation have been destroyed. Finally, the global dispersal of viable, isolated cells of even this desiccation-tolerant, ionizing-radiation-resistant microorganism on Mars is unlikely as they are killed quickly by unattenuated UV radiation when in a desiccated state. These findings have implications for the survival of diverse microbial contaminants dispersed during the course of human exploratory class missions on the surface of Mars. PMID:15815164

  20. Characterization of the response to zinc deficiency in the cyanobacterium Anabaena sp. strain PCC 7120.

    PubMed

    Napolitano, Mauro; Rubio, Miguel Ángel; Santamaría-Gómez, Javier; Olmedo-Verd, Elvira; Robinson, Nigel J; Luque, Ignacio

    2012-05-01

    Zur regulators control zinc homeostasis by repressing target genes under zinc-sufficient conditions in a wide variety of bacteria. This paper describes how part of a survey of duplicated genes led to the identification of the open reading frame all2473 as the gene encoding the Zur regulator of the cyanobacterium Anabaena sp. strain PCC 7120. All2473 binds to DNA in a zinc-dependent manner, and its DNA-binding sequence was characterized, which allowed us to determine the relative contribution of particular nucleotides to Zur binding. A zur mutant was found to be impaired in the regulation of zinc homeostasis, showing sensitivity to elevated concentrations of zinc but not other metals. In an effort to characterize the Zur regulon in Anabaena, 23 genes containing upstream putative Zur-binding sequences were identified and found to be regulated by Zur. These genes are organized in six single transcriptional units and six operons, some of them containing multiple Zur-regulated promoters. The identities of genes of the Zur regulon indicate that Anabaena adapts to conditions of zinc deficiency by replacing zinc metalloproteins with paralogues that fulfill the same function but presumably with a lower zinc demand, and with inducing putative metallochaperones and membrane transport systems likely being involved in the scavenging of extracellular zinc, including plasma membrane ABC transport systems and outer membrane TonB-dependent receptors. Among the Zur-regulated genes, the ones showing the highest induction level encode proteins of the outer membrane, suggesting a primary role for components of this cell compartment in the capture of zinc cations from the extracellular medium. PMID:22389488

  1. Isolation and characterization of nitrogenase-derepressed mutant strains of cyanobacterium Anabaena variabilis.

    PubMed Central

    Spiller, H; Latorre, C; Hassan, M E; Shanmugam, K T

    1986-01-01

    A positive selection method for isolation of nitrogenase-derepressed mutant strains of a filamentous cyanobacterium, Anabaena variabilis, is described. Mutant strains that are resistant to a glutamate analog, L-methionine-D,L-sulfoximine, were screened for their ability to produce and excrete NH4+ into medium. Mutant strains capable of producing nitrogenase in the presence of NH4+ were selected from a population of NH4+-excreting mutants. One of the mutant strains (SA-1) studied in detail was found to be a conditional glutamine auxotroph requiring glutamine for growth in media containing N2, NO3-, or low concentrations of NH4+ (less than 0.5 mM). This glutamine requirement is a consequence of a block in the assimilation of NH4+ produced by an enzyme system like nitrogenase. Glutamate and aspartate failed to substitute for glutamine because of a defect in the transport and utilization of these amino acids. Strain SA-1 assimilated NH4+ when the concentration in the medium reached about 0.5 mM, and under these conditions the growth rate was similar to that of the parent. Mutant strain SA-1 produced L-methionine-D,L-sulfoximine-resistant glutamine synthetase activity. Kinetic properties of the enzyme from the parent and mutant were similar. Mutant strain SA-1 can potentially serve as a source of fertilizer nitrogen to support growth of crop plants, since the NH4+ produced by nitrogenase, utilizing sunlight and water as sources of energy and reductant, respectively, is excreted into the environment. PMID:2867990

  2. Ionic Osmoregulation during Salt Adaptation of the Cyanobacterium Synechococcus 6311 1

    PubMed Central

    Blumwald, Eduardo; Mehlhorn, Rolf J.; Packer, Lester

    1983-01-01

    The mechanisms of salt adaptation were studied in the cyanobacterium Synechococcus 6311. Intracellular volumes and ion concentrations were measured before and after abrupt increases of external NaCl concentrations up to 0.6 molar NaCl. Equilibrium volumes, measured with a rapid and accurate electron spin resonance spin probe method, showed that at low NaCl concentrations the cells did not shrink as expected for an impermeable solute. However, when the NaCl concentration exceeded a critical value, volume losses occurred. These losses were not fully reversed by hypoosmotic treatment, suggesting membrane damage. The critical value of irreversible volume loss paralleled the increase in salinity during cell growth. Rapid mixing experiments showed that exposure of Synechococcus 6311 to non-damaging NaCl concentrations caused water extrusion from the cells; the volume decreases were time resolved to about 200 milliseconds. Subsequently, volumes increased rapidly as NaCl moved into the cells. Controls recovered their volumes within 15 seconds, while salt-adapted cells grown at 0.6 molar NaCl required 1 minute for volume equilibration. This decrease in the rate of cell volume recovery indicates that salt adaptation is accompanied by changes in cell membrane properties. Subsequent to these initial rapid volume changes, a more gradual sequence of ion movement and sugar accumulation was observed. Under conditions for photoautotrophic growth, significant Na+ extrusion was observed 30 min after salt shock. Sucrose accumulation reached a maximum value after 16 hours and K+ accumulation reached equilibrium after 40 hours. The final concentrations of K+ and Na+ and sucrose and glucose inside the 0.6 molar NaCl-grown cells indicate that the inorganic ions and organic `compatible' solutes are the major osmotic species which account for the adaptation of Synechococcus 6311 to salt. PMID:16663223

  3. Compartmentalized cyanophycin metabolism in the diazotrophic filaments of a heterocyst-forming cyanobacterium.

    PubMed

    Burnat, Mireia; Herrero, Antonia; Flores, Enrique

    2014-03-11

    Heterocyst-forming cyanobacteria are multicellular organisms in which growth requires the activity of two metabolically interdependent cell types, the vegetative cells that perform oxygenic photosynthesis and the dinitrogen-fixing heterocysts. Vegetative cells provide the heterocysts with reduced carbon, and heterocysts provide the vegetative cells with fixed nitrogen. Heterocysts conspicuously accumulate polar granules made of cyanophycin [multi-L-arginyl-poly (L-aspartic acid)], which is synthesized by cyanophycin synthetase and degraded by the concerted action of cyanophycinase (that releases β-aspartyl-arginine) and isoaspartyl dipeptidase (that produces aspartate and arginine). Cyanophycin synthetase and cyanophycinase are present at high levels in the heterocysts. Here we created a deletion mutant of gene all3922 encoding isoaspartyl dipeptidase in the model heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120. The mutant accumulated cyanophycin and β-aspartyl-arginine, and was impaired specifically in diazotrophic growth. Analysis of an Anabaena strain bearing an All3922-GFP (green fluorescent protein) fusion and determination of the enzyme activity in specific cell types showed that isoaspartyl dipeptidase is present at significantly lower levels in heterocysts than in vegetative cells. Consistently, isolated heterocysts released substantial amounts of β-aspartyl-arginine. These observations imply that β-aspartyl-arginine produced from cyanophycin in the heterocysts is transferred intercellularly to be hydrolyzed, producing aspartate and arginine in the vegetative cells. Our results showing compartmentalized metabolism of cyanophycin identify the nitrogen-rich molecule β-aspartyl-arginine as a nitrogen vehicle in the unique multicellular system represented by the heterocyst-forming cyanobacteria.

  4. Regulation of Three Nitrogenase Gene Clusters in the Cyanobacterium Anabaena variabilis ATCC 29413

    PubMed Central

    Thiel, Teresa; Pratte, Brenda S.

    2014-01-01

    The filamentous cyanobacterium Anabaena variabilis ATCC 29413 fixes nitrogen under aerobic conditions in specialized cells called heterocysts that form in response to an environmental deficiency in combined nitrogen. Nitrogen fixation is mediated by the enzyme nitrogenase, which is very sensitive to oxygen. Heterocysts are microxic cells that allow nitrogenase to function in a filament comprised primarily of vegetative cells that produce oxygen by photosynthesis. A. variabilis is unique among well-characterized cyanobacteria in that it has three nitrogenase gene clusters that encode different nitrogenases, which function under different environmental conditions. The nif1 genes encode a Mo-nitrogenase that functions only in heterocysts, even in filaments grown anaerobically. The nif2 genes encode a different Mo-nitrogenase that functions in vegetative cells, but only in filaments grown under anoxic conditions. An alternative V-nitrogenase is encoded by vnf genes that are expressed only in heterocysts in an environment that is deficient in Mo. Thus, these three nitrogenases are expressed differentially in response to environmental conditions. The entire nif1 gene cluster, comprising at least 15 genes, is primarily under the control of the promoter for the first gene, nifB1. Transcriptional control of many of the downstream nif1 genes occurs by a combination of weak promoters within the coding regions of some downstream genes and by RNA processing, which is associated with increased transcript stability. The vnf genes show a similar pattern of transcriptional and post-transcriptional control of expression suggesting that the complex pattern of regulation of the nif1 cluster is conserved in other cyanobacterial nitrogenase gene clusters. PMID:25513762

  5. Global transcriptional profiles of the copper responses in the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Giner-Lamia, Joaquin; López-Maury, Luis; Florencio, Francisco J

    2014-01-01

    Copper is an essential element involved in fundamental processes like respiration and photosynthesis. However, it becomes toxic at high concentration, which has forced organisms to control its cellular concentration. We have recently described a copper resistance system in the cyanobacterium Synechocystis sp. PCC 6803, which is mediated by the two-component system, CopRS, a RND metal transport system, CopBAC and a protein of unknown function, CopM. Here, we report the transcriptional responses to copper additions at non-toxic (0.3 µM) and toxic concentrations (3 µM) in the wild type and in the copper sensitive copR mutant strain. While 0.3 µM copper slightly stimulated metabolism and promoted the exchange between cytochrome c6 and plastocyanin as soluble electron carriers, the addition of 3 µM copper catalyzed the formation of ROS, led to a general stress response and induced expression of Fe-S cluster biogenesis genes. According to this, a double mutant strain copRsufR, which expresses constitutively the sufBCDS operon, tolerated higher copper concentration than the copR mutant strain, suggesting that Fe-S clusters are direct targets of copper toxicity in Synechocystis. In addition we have also demonstrated that InrS, a nickel binding transcriptional repressor that belong to the CsoR family of transcriptional factor, was involved in heavy metal homeostasis, including copper, in Synechocystis. Finally, global gene expression analysis of the copR mutant strain suggested that CopRS only controls the expression of copMRS and copBAC operons in response to copper.

  6. Global Transcriptional Profiles of the Copper Responses in the Cyanobacterium Synechocystis sp. PCC 6803

    PubMed Central

    Giner-Lamia, Joaquin; López-Maury, Luis; Florencio, Francisco J.

    2014-01-01

    Copper is an essential element involved in fundamental processes like respiration and photosynthesis. However, it becomes toxic at high concentration, which has forced organisms to control its cellular concentration. We have recently described a copper resistance system in the cyanobacterium Synechocystis sp. PCC 6803, which is mediated by the two-component system, CopRS, a RND metal transport system, CopBAC and a protein of unknown function, CopM. Here, we report the transcriptional responses to copper additions at non-toxic (0.3 µM) and toxic concentrations (3 µM) in the wild type and in the copper sensitive copR mutant strain. While 0.3 µM copper slightly stimulated metabolism and promoted the exchange between cytochrome c6 and plastocyanin as soluble electron carriers, the addition of 3 µM copper catalyzed the formation of ROS, led to a general stress response and induced expression of Fe-S cluster biogenesis genes. According to this, a double mutant strain copRsufR, which expresses constitutively the sufBCDS operon, tolerated higher copper concentration than the copR mutant strain, suggesting that Fe-S clusters are direct targets of copper toxicity in Synechocystis. In addition we have also demonstrated that InrS, a nickel binding transcriptional repressor that belong to the CsoR family of transcriptional factor, was involved in heavy metal homeostasis, including copper, in Synechocystis. Finally, global gene expression analysis of the copR mutant strain suggested that CopRS only controls the expression of copMRS and copBAC operons in response to copper. PMID:25268225

  7. Compartmentalized cyanophycin metabolism in the diazotrophic filaments of a heterocyst-forming cyanobacterium

    PubMed Central

    Burnat, Mireia; Herrero, Antonia; Flores, Enrique

    2014-01-01

    Heterocyst-forming cyanobacteria are multicellular organisms in which growth requires the activity of two metabolically interdependent cell types, the vegetative cells that perform oxygenic photosynthesis and the dinitrogen-fixing heterocysts. Vegetative cells provide the heterocysts with reduced carbon, and heterocysts provide the vegetative cells with fixed nitrogen. Heterocysts conspicuously accumulate polar granules made of cyanophycin [multi-L-arginyl-poly (L-aspartic acid)], which is synthesized by cyanophycin synthetase and degraded by the concerted action of cyanophycinase (that releases β-aspartyl-arginine) and isoaspartyl dipeptidase (that produces aspartate and arginine). Cyanophycin synthetase and cyanophycinase are present at high levels in the heterocysts. Here we created a deletion mutant of gene all3922 encoding isoaspartyl dipeptidase in the model heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120. The mutant accumulated cyanophycin and β-aspartyl-arginine, and was impaired specifically in diazotrophic growth. Analysis of an Anabaena strain bearing an All3922-GFP (green fluorescent protein) fusion and determination of the enzyme activity in specific cell types showed that isoaspartyl dipeptidase is present at significantly lower levels in heterocysts than in vegetative cells. Consistently, isolated heterocysts released substantial amounts of β-aspartyl-arginine. These observations imply that β-aspartyl-arginine produced from cyanophycin in the heterocysts is transferred intercellularly to be hydrolyzed, producing aspartate and arginine in the vegetative cells. Our results showing compartmentalized metabolism of cyanophycin identify the nitrogen-rich molecule β-aspartyl-arginine as a nitrogen vehicle in the unique multicellular system represented by the heterocyst-forming cyanobacteria. PMID:24550502

  8. Phosphoproteome of the cyanobacterium Synechocystis sp. PCC 6803 and its dynamics during nitrogen starvation

    PubMed Central

    Spät, Philipp; Maček, Boris; Forchhammer, Karl

    2015-01-01

    Cyanobacteria have shaped the earth's biosphere as the first oxygenic photoautotrophs and still play an important role in many ecosystems. The ability to adapt to changing environmental conditions is an essential characteristic in order to ensure survival. To this end, numerous studies have shown that bacteria use protein post-translational modifications such as Ser/Thr/Tyr phosphorylation in cell signaling, adaptation, and regulation. Nevertheless, our knowledge of cyanobacterial phosphoproteomes and their dynamic response to environmental stimuli is relatively limited. In this study, we applied gel-free methods and high accuracy mass spectrometry toward the detection of Ser/Thr/Tyr phosphorylation events in the model cyanobacterium Synechocystis sp. PCC 6803. We could identify over 300 phosphorylation events in cultures grown on nitrate as exclusive nitrogen source. Chemical dimethylation labeling was applied to investigate proteome and phosphoproteome dynamics during nitrogen starvation. Our dataset describes the most comprehensive (phospho)proteome of Synechocystis to date, identifying 2382 proteins and 183 phosphorylation events and quantifying 2111 proteins and 148 phosphorylation events during nitrogen starvation. Global protein phosphorylation levels were increased in response to nitrogen depletion after 24 h. Among the proteins with increased phosphorylation, the PII signaling protein showed the highest fold-change, serving as positive control. Other proteins with increased phosphorylation levels comprised functions in photosynthesis and in carbon and nitrogen metabolism. This study reveals dynamics of Synechocystis phosphoproteome in response to environmental stimuli and suggests an important role of protein Ser/Thr/Tyr phosphorylation in fundamental mechanisms of homeostatic control in cyanobacteria. PMID:25873915

  9. Structural investigation of the antagonist LPS from the cyanobacterium Oscillatoria planktothrix FP1.

    PubMed

    Carillo, Sara; Pieretti, Giuseppina; Bedini, Emiliano; Parrilli, Michelangelo; Lanzetta, Rosa; Corsaro, Maria Michela

    2014-03-31

    Cyanobacteria are aquatic and photosynthetic microorganisms, which contribute up to 30% of the yearly oxygen production on the earth. They have the distinction of being the oldest known fossils, more than 3.5 billion years old, and are one of the largest and most important groups of bacteria on earth. Cyanobacteria are an emerging source of potentially pharmacologically active products and, among these, there are the lipopolysaccharides. Despite their significant and well documented activity, very little is known about the cyanobacteria lipopolysaccharides (LPS) structure. The aim of this work is to investigate the structure of the highly TLR4-antagonist lipopolysaccharide from the cyanobacterium Oscillatoria plankthotrix FP1. The LPS was purified and analysed by means of chemical analysis and 1H and 13C NMR spectroscopy. The LPS was then degraded by Smith degradation, HF and acetic acid hydrolyses. All the obtained products were investigated in detail by chemical analysis, NMR spectroscopy and by mass spectrometry. The LPS consists of a high molecular mass and very complex molecule lacking Kdo and heptose residues, where the polysaccharide chain is mainly constituted by a backbone of 3-substituted α-l-rhamnose units. The core region is rich in galacturonic acid and mannose residues. Moreover a glycolipid portion, similar to Gram-negative lipid A, was identified. This was built up of a non phosphorylated (1'→6) linked glucosamine disaccharide, acylated with 3-hydroxylated fatty acids. In particular 3-hydroxypentadecanoic and 3-hydroxyesadecanoic acids were found, together with esadecanoic and tetradecanoic ones. Finally the presence of a galacturonic acid residue at 6-position of the distal glucosamine in place of the Kdo residue is suggested.

  10. Preliminary evidence of toxicity associated with the benthic cyanobacterium Phormidium in South Australia.

    PubMed

    Baker, P D; Steffensen, D A; Humpage, A R; Nicholson, B C; Falconer, I R; Lanthois, B; Fergusson, K M; Saint, C P

    2001-01-01

    In April 2000, the water supply for Yorke Peninsula in South Australia was deemed non-potable when extracts from a proliferation of the benthic cyanobacterium Phormidium aff. formosum in Upper Paskeville Reservoir were found to be lethally toxic by intraperitoneal injection into mice (400 mg kg-1). Routine water quality monitoring had failed to detect the development of the Phormidium until complaints of musty taste and odour, attributable to the production of 2-methyl-isoborneol (MIB), were received from the consumers. The 185 ML open-balancing storage, receiving filtered and chloraminated water from the River Murray, was isolated from the drinking water supply and a health alert was issued to approximately 15,000 consumers. The identity of the toxin(s) is thus far unknown, but clinical symptoms of toxicity in mice and chemical characteristics are distinct from the known major cyanotoxins. Preliminary characterisation of this toxin indicates that it has low solubility in water and organic solvents and is strongly associated with the particulate cellular material of the filaments. Toxicity of extracts was diminished by boiling and by treatment with chlorine, but not by chloramines. Further testing of floating cyanobacterial mats in the Torrens Lake in the city of Adelaide (Phormidium aff. formosum) and Myponga Reservoir (Phormidium aff. amoenum) in 2000/2001 was also found to be toxic by mouse bioassay. Toxicity is yet to be confirmed in monospecific cultured strains and further studies are required to identify the toxin and assess its health significance. Genetic characterisation of isolates has commenced in an attempt to classify their relatedness and to assist in the rapid identification of potentially toxic strains. PMID:11769248

  11. Lack of Phylogeographic Structure in the Freshwater Cyanobacterium Microcystis aeruginosa Suggests Global Dispersal

    PubMed Central

    van Gremberghe, Ineke; Vanormelingen, Pieter; Van der Gucht, Katleen; Debeer, Ann-Eline; Lacerot, Gissell; De Meester, Luc; Vyverman, Wim

    2011-01-01

    Background Free-living microorganisms have long been assumed to have ubiquitous distributions with little biogeographic signature because they typically exhibit high dispersal potential and large population sizes. However, molecular data provide contrasting results and it is far from clear to what extent dispersal limitation determines geographic structuring of microbial populations. We aimed to determine biogeographical patterns of the bloom-forming freshwater cyanobacterium Microcystis aeruginosa. Being widely distributed on a global scale but patchily on a regional scale, this prokaryote is an ideal model organism to study microbial dispersal and biogeography. Methodology/Principal Findings The phylogeography of M. aeruginosa was studied based on a dataset of 311 rDNA internal transcribed spacer (ITS) sequences sampled from six continents. Richness of ITS sequences was high (239 ITS types were detected). Genetic divergence among ITS types averaged 4% (maximum pairwise divergence was 13%). Preliminary analyses revealed nearly completely unresolved phylogenetic relationships and a lack of genetic structure among all sequences due to extensive homoplasy at multiple hypervariable sites. After correcting for this, still no clear phylogeographic structure was detected, and no pattern of isolation by distance was found on a global scale. Concomitantly, genetic differentiation among continents was marginal, whereas variation within continents was high and was mostly shared with all other continents. Similarly, no genetic structure across climate zones was detected. Conclusions/Significance The high overall diversity and wide global distribution of common ITS types in combination with the lack of phylogeographic structure suggest that intercontinental dispersal of M. aeruginosa ITS types is not rare, and that this species might have a truly cosmopolitan distribution. PMID:21573169

  12. Phosphoproteome of the cyanobacterium Synechocystis sp. PCC 6803 and its dynamics during nitrogen starvation.

    PubMed

    Spät, Philipp; Maček, Boris; Forchhammer, Karl

    2015-01-01

    Cyanobacteria have shaped the earth's biosphere as the first oxygenic photoautotrophs and still play an important role in many ecosystems. The ability to adapt to changing environmental conditions is an essential characteristic in order to ensure survival. To this end, numerous studies have shown that bacteria use protein post-translational modifications such as Ser/Thr/Tyr phosphorylation in cell signaling, adaptation, and regulation. Nevertheless, our knowledge of cyanobacterial phosphoproteomes and their dynamic response to environmental stimuli is relatively limited. In this study, we applied gel-free methods and high accuracy mass spectrometry toward the detection of Ser/Thr/Tyr phosphorylation events in the model cyanobacterium Synechocystis sp. PCC 6803. We could identify over 300 phosphorylation events in cultures grown on nitrate as exclusive nitrogen source. Chemical dimethylation labeling was applied to investigate proteome and phosphoproteome dynamics during nitrogen starvation. Our dataset describes the most comprehensive (phospho)proteome of Synechocystis to date, identifying 2382 proteins and 183 phosphorylation events and quantifying 2111 proteins and 148 phosphorylation events during nitrogen starvation. Global protein phosphorylation levels were increased in response to nitrogen depletion after 24 h. Among the proteins with increased phosphorylation, the PII signaling protein showed the highest fold-change, serving as positive control. Other proteins with increased phosphorylation levels comprised functions in photosynthesis and in carbon and nitrogen metabolism. This study reveals dynamics of Synechocystis phosphoproteome in response to environmental stimuli and suggests an important role of protein Ser/Thr/Tyr phosphorylation in fundamental mechanisms of homeostatic control in cyanobacteria. PMID:25873915

  13. Feeding and filtration rates of zooplankton (rotifers and cladocerans) fed toxic cyanobacterium (Microcystis aeruginosa).

    PubMed

    Pérez-Morales, Alfredo; Sarma, S S S; Nandini, S

    2014-11-01

    Microcystis aeruginosa is generally dominant in many Mexican freshwater ecosystems interacting with zooplankton species. Hence, feeding and filtration rates were quantified for three cladoceran (Daphnia pulex, Moina micrura and Ceriodaphnia dubia) and three rotifer species (Brachionus calyciflorus, Brachionus rubens and Plationus patulus) using sonicated M. aeruginosa alone or mixed with Scenedesmus acutus in different proportions (25, 50 and 75%, based on cell density), offering a combined initial density of 100,000 cells·ml(-1). All the three cladoceran species ingested M. aeruginosa (100-300 cells ind(-1) min(-1)) when fed exclusively with cyanobacterium. When green alga offered as exclusive diet, the number of cells ingested by the tested cladocerans varied from 80 to 400 cells ind(-1) min(-1). Compared to cladocerans, rotifers in general consumed much lower quantity (< 200 cells ind(-1) min(-1)) of M. aeruginosa and S. acutus. The filtration rate for Daphnia pulex was inversely related to the proportion of green alga in the diet. For other tested cladocerans, no such clear trend was evident. In mixed treatments containing M. aeruginosa, the filtration rate of Daphnia was highest (about 220 μl ind(-1) min(-1)) when the medium contained 75% of S. acutus. Among the rotifer species, P. patulus filtered highest volume (100 μl ind(-1) min(-1) from mixed diets containing higher proportions (50 or 75%) of M. aeruginosa. Thus, there were species-specific differences in the filtration and feeding rates of zooplankton when offered mixed diets of green algae and toxic cyanobacteria. These probably explain the coexistence of different zooplankton species in Microcystis-dominant waterbodies. PMID:25522500

  14. Intercellular Diffusion of a Fluorescent Sucrose Analog via the Septal Junctions in a Filamentous Cyanobacterium

    PubMed Central

    Nürnberg, Dennis J.; Mariscal, Vicente; Bornikoel, Jan; Nieves-Morión, Mercedes; Krauß, Norbert; Herrero, Antonia

    2015-01-01

    ABSTRACT Many filamentous cyanobacteria produce specialized nitrogen-fixing cells called heterocysts, which are located at semiregular intervals along the filament with about 10 to 20 photosynthetic vegetative cells in between. Nitrogen fixation in these complex multicellular bacteria depends on metabolite exchange between the two cell types, with the heterocysts supplying combined-nitrogen compounds but dependent on the vegetative cells for photosynthetically produced carbon compounds. Here, we used a fluorescent tracer to probe intercellular metabolite exchange in the filamentous heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120. We show that esculin, a fluorescent sucrose analog, is incorporated by a sucrose import system into the cytoplasm of Anabaena cells. The cytoplasmic esculin is rapidly and reversibly exchanged across vegetative-vegetative and vegetative-heterocyst cell junctions. Our measurements reveal the kinetics of esculin exchange and also show that intercellular metabolic communication is lost in a significant fraction of older heterocysts. SepJ, FraC, and FraD are proteins located at the intercellular septa and are suggested to form structures analogous to gap junctions. We show that a ΔsepJ ΔfraC ΔfraD triple mutant shows an altered septum structure with thinner septa but a denser peptidoglycan layer. Intercellular diffusion of esculin and fluorescein derivatives is impaired in this mutant, which also shows a greatly reduced frequency of nanopores in the intercellular septal cross walls. These findings suggest that FraC, FraD, and SepJ are important for the formation of junctional structures that constitute the major pathway for feeding heterocysts with sucrose. PMID:25784700

  15. The genome of Cyanothece 51142, a unicellular diazotrophic cyanobacterium important in the marine nitrogen cycle

    SciTech Connect

    Welsh, Eric A.; Liberton, Michelle L.; Stockel, Jana; Loh, Thomas; Elvitigala, Thanura R.; Wang, Chunyan; Wollam, Aye; Fulton, Robert S.; Clifton, Sandra W.; Jacobs, Jon M.; Aurora, Rajeev; Ghosh, Bijoy K.; Sherman, Louis A.; Smith, Richard D.; Wilson, Richard K.; Pakrasi, Himadri B.

    2008-09-30

    Cyanobacteria are oxygenic photosynthetic bacteria that have significant roles in global biological carbon sequestration and oxygen production. They occupy a diverse range of habitats, from open ocean, to hot springs, deserts, and arctic waters. Cyanobacteria are known as the progenitors of the chloroplasts of plants and algae, and are the simplest known organisms to exhibit circadian behavior4. Cyanothece sp. ATCC 51142 is a unicellular marine cyanobacterium capable of N2-fixation, a process that is biochemically incompatible with oxygenic photosynthesis. To resolve this problem, Cyanothece performs photosynthesis during the day and nitrogen fixation at night, thus temporally separating these processes in the same cell. The genome of Cyanothece 51142 was completely sequenced and found to contain a unique arrangement of one large circular chromosome, four small plasmids, and one linear chromosome, the first report of such a linear element in a photosynthetic bacterium. Annotation of the Cyanothece genome was aided by the use of highthroughput proteomics data, enabling the reclassification of 25% of the proteins with no informative sequence homology. Phylogenetic analysis suggests that nitrogen fixation is an ancient process that arose early in evolution and has subsequently been lost in many cyanobacterial strains. In cyanobacterial cells, the circadian clock influences numerous processes, including carbohydrate synthesis, nitrogen fixation, photosynthesis, respiration, and the cell division cycle. During a diurnal period, Cyanothece cells actively accumulate and degrade different storage inclusion bodies for the products of photosynthesis and N2-fixation. This ability to utilize metabolic compartmentalization and energy storage makes Cyanothece an ideal system for bioenergy research, as well as studies of how a unicellular organism balances multiple, often incompatible, processes in the same cell.

  16. DL-7-azatryptophan and citrulline metabolism in the cyanobacterium Anabaena sp. strain 1F

    SciTech Connect

    Chen, C.H.; Van Baalen, C.; Tabita, F.R.

    1987-03-01

    An alternative route for the primary assimilation of ammonia proceeds via glutamine synthetase-carbamyl phosphate synthetase and its inherent glutaminase activity in Anabaena sp. strain 1F, a marine filamentous, heterocystous cyanobacterium. Evidence for the presence of this possible alternative route to glutamate was provided by the use of amino acid analogs as specific enzyme inhibitors, enzymological studies, and radioistopic labeling experiments. The amino acid pool patterns of continuous cultures of Anabaena sp. strain 1F were markedly influenced by the nitrogen source. A relatively high concentration of glutamate was maintained in the amino acid pools of all cultures irrespective of the nitrogen source, reflecting the central role of glutamate in nitrogen metabolism. The addition of 1.0 microM azaserine increased the intracellular pools of glutamate and glutamine. All attempts to detect any enzymatic activity for glutamate synthase by measuring the formation of L-(/sup 14/C)glutamate from 2-keto-(1-/sup 14/C)glutarate and glutamine failed. The addition of 10 microM DL-7-azatryptophan caused a transient accumulation of intracellular citrulline and alanine which was not affected by the presence of chloramphenicol. The in vitro activity of carbamyl phosphate synthetase and glutaminase increased severalfold in the presence of azatryptophan. Results from radioisotopic labeling experiments with (/sup 14/C)bicarbonate and L-(1-/sup 14/C)ornithine also indicated that citrulline was formed via carbamyl phosphate synthetase and ornithine transcarbamylase. In addition to its effects on nitrogen metabolism, azatryptophan also affected carbon metabolism by inhibiting photosynthetic carbon assimilation and photosynthetic oxygen evolution.

  17. Structural insight into photoactivation of an adenylate cyclase from a photosynthetic cyanobacterium.

    PubMed

    Ohki, Mio; Sugiyama, Kanako; Kawai, Fumihiro; Tanaka, Hitomi; Nihei, Yuuki; Unzai, Satoru; Takebe, Masumi; Matsunaga, Shigeru; Adachi, Shin-Ichi; Shibayama, Naoya; Zhou, Zhiwen; Koyama, Ryuta; Ikegaya, Yuji; Takahashi, Tetsuo; Tame, Jeremy R H; Iseki, Mineo; Park, Sam-Yong

    2016-06-14

    Cyclic-AMP is one of the most important second messengers, regulating many crucial cellular events in both prokaryotes and eukaryotes, and precise spatial and temporal control of cAMP levels by light shows great promise as a simple means of manipulating and studying numerous cell pathways and processes. The photoactivated adenylate cyclase (PAC) from the photosynthetic cyanobacterium Oscillatoria acuminata (OaPAC) is a small homodimer eminently suitable for this task, requiring only a simple flavin chromophore within a blue light using flavin (BLUF) domain. These domains, one of the most studied types of biological photoreceptor, respond to blue light and either regulate the activity of an attached enzyme domain or change its affinity for a repressor protein. BLUF domains were discovered through studies of photo-induced movements of Euglena gracilis, a unicellular flagellate, and gene expression in the purple bacterium Rhodobacter sphaeroides, but the precise details of light activation remain unknown. Here, we describe crystal structures and the light regulation mechanism of the previously undescribed OaPAC, showing a central coiled coil transmits changes from the light-sensing domains to the active sites with minimal structural rearrangement. Site-directed mutants show residues essential for signal transduction over 45 Å across the protein. The use of the protein in living human cells is demonstrated with cAMP-dependent luciferase, showing a rapid and stable response to light over many hours and activation cycles. The structures determined in this study will assist future efforts to create artificial light-regulated control modules as part of a general optogenetic toolkit. PMID:27247413

  18. Characterization of genes for an alternative nitrogenase in the cyanobacterium Anabaena variabilis.

    PubMed Central

    Thiel, T

    1993-01-01

    Anabaena variabilis ATCC 29413 is a heterotrophic, nitrogen-fixing cyanobacterium that has been reported to fix nitrogen and reduce acetylene to ethane in the absence of molybdenum. DNA from this strain hybridized well at low stringency to the nitrogenase 2 (vnfDGK) genes of Azotobacter vinelandii. The hybridizing region was cloned from a lambda EMBL3 genomic library of A. variabilis, mapped, and sequenced. The deduced amino acid sequences of the vnfD and vnfK genes of A. variabilis showed only about 56% similarity to the nifDK genes of Anabaena sp. strain PCC 7120 but were 76 to 86% similar to the anfDK or vnfDK genes of A. vinelandii. The organization of the vnf gene cluster in A. variabilis was similar to that of A. vinelandii. However, in A. variabilis, the vnfG gene was fused to vnfD; hence, this gene is designated vnfDG. A vnfH gene was not contiguous with the vnfDG gene and has not yet been identified. A mutant strain, in which a neomycin resistance cassette was inserted into the vnf cluster, grew well in a medium lacking a source of fixed nitrogen in the presence of molybdenum but grew poorly when vanadium replaced molybdenum. In contrast, the parent strain grew equally well in media containing either molybdenum or vanadium. The vnf genes were transcribed in the absence of molybdenum, with or without vanadium. The vnf gene cluster did not hybridize to chromosomal DNA from Anabaena sp. strain PCC 7120 or from the heterotrophic strains, Nostoc sp. strain Mac and Nostoc sp. strain ATCC 29150. A hybridizing ClaI fragment very similar in size to the A. variabilis ClaI fragment was present in DNA isolated from several independent, cultured isolates of Anabaena sp. from the Azolla symbiosis. Images PMID:8407800

  19. Compartmentalized cyanophycin metabolism in the diazotrophic filaments of a heterocyst-forming cyanobacterium.

    PubMed

    Burnat, Mireia; Herrero, Antonia; Flores, Enrique

    2014-03-11

    Heterocyst-forming cyanobacteria are multicellular organisms in which growth requires the activity of two metabolically interdependent cell types, the vegetative cells that perform oxygenic photosynthesis and the dinitrogen-fixing heterocysts. Vegetative cells provide the heterocysts with reduced carbon, and heterocysts provide the vegetative cells with fixed nitrogen. Heterocysts conspicuously accumulate polar granules made of cyanophycin [multi-L-arginyl-poly (L-aspartic acid)], which is synthesized by cyanophycin synthetase and degraded by the concerted action of cyanophycinase (that releases β-aspartyl-arginine) and isoaspartyl dipeptidase (that produces aspartate and arginine). Cyanophycin synthetase and cyanophycinase are present at high levels in the heterocysts. Here we created a deletion mutant of gene all3922 encoding isoaspartyl dipeptidase in the model heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120. The mutant accumulated cyanophycin and β-aspartyl-arginine, and was impaired specifically in diazotrophic growth. Analysis of an Anabaena strain bearing an All3922-GFP (green fluorescent protein) fusion and determination of the enzyme activity in specific cell types showed that isoaspartyl dipeptidase is present at significantly lower levels in heterocysts than in vegetative cells. Consistently, isolated heterocysts released substantial amounts of β-aspartyl-arginine. These observations imply that β-aspartyl-arginine produced from cyanophycin in the heterocysts is transferred intercellularly to be hydrolyzed, producing aspartate and arginine in the vegetative cells. Our results showing compartmentalized metabolism of cyanophycin identify the nitrogen-rich molecule β-aspartyl-arginine as a nitrogen vehicle in the unique multicellular system represented by the heterocyst-forming cyanobacteria. PMID:24550502

  20. Binding of ferric heme by the recombinant globin from the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Lecomte, J T; Scott, N L; Vu, B C; Falzone, C J

    2001-05-29

    The product of the cyanobacterium Synechocystis sp. PCC 6803 gene slr2097 is a 123 amino acid polypeptide chain belonging to the truncated hemoglobin family. Recombinant, ferric heme-reconstituted Synechocystis sp. PCC 6803 hemoglobin is a low-spin complex whose endogenous hexacoordination gives rise to optical and NMR characteristics reminiscent of cytochrome b(5) [Scott, N. L., and Lecomte, J. T. J. (2000) Protein Sci. 9, 587-597]. In this work, the sequential assignments using (15)N-(13)C-labeled protein, (1)H nuclear Overhauser effects, and longitudinal relaxation data identified His70 as the proximal histidine and His46 as the sixth ligand to the iron ion. It was also found that one of two possible heme orientations within the protein matrix is highly preferred (>90%) and that this orientation is the same as in vertebrate myoglobins. The rate constant for the 180 degrees rotation of the heme within a protein cage to produce the favored isomer was 0.5 h(-1) at 25 degrees C, approximately 35 times faster than in sperm whale myoglobin. Variable temperature studies revealed an activation energy of 132 +/- 4 kJ mol(-1), similar to the value in metaquomyoglobin at the same pH. The rate constant for heme loss from the major isomer was estimated to be 0.01 h(-1) by optical spectroscopy, close to the value for myoglobin and decades slower than in the related Nostoc commune cyanoglobin. The slow heme loss was attributed in part to the additional coordination bond to His46, whereas the relatively fast rate of heme reorientation suggested that this bond was weaker than the proximal His70-Fe bond. The standard reduction potential of the hexacoordinated protein was measured with and without poly-L-lysine as a mediator and found to be approximately -150 mV vs SHE, indicating a stabilization of the ferric state compared to most hemoglobins and b(5) cytochromes. PMID:11371218

  1. Molecular structure and enzymatic function of lycopene cyclase from the cyanobacterium Synechococcus sp strain PCC7942.

    PubMed Central

    Cunningham, F X; Sun, Z; Chamovitz, D; Hirschberg, J; Gantt, E

    1994-01-01

    A gene encoding the enzyme lycopene cyclase in the cyanobacterium Synechococcus sp strain PCC7942 was mapped by genetic complementation, cloned, and sequenced. This gene, which we have named crtL, was expressed in strains of Escherichia coli that were genetically engineered to accumulate the carotenoid precursors lycopene, neurosporene, and zeta-carotene. The crtL gene product converts the acyclic hydrocarbon lycopene into the bicyclic beta-carotene, an essential component of the photosynthetic apparatus in oxygen-evolving organisms and a source of vitamin A in human and animal nutrition. The enzyme also converts neurosporene to the monocyclic beta-zeacarotene but does not cyclize zeta-carotene, indicating that desaturation of the 7-8 or 7'-8' carbon-carbon bond is required for cyclization. The bleaching herbicide 2-(4-methylphenoxy)triethylamine hydrochloride (MPTA) effectively inhibits both cyclization reactions. A mutation that confers resistance to MPTA in Synechococcus sp PCC7942 was identified as a point mutation in the promoter region of crtL. The deduced amino acid sequence of lycopene cyclase specifies a polypeptide of 411 amino acids with a molecular weight of 46,125 and a pI of 6.0. An amino acid sequence motif indicative of FAD utilization is located at the N terminus of the polypeptide. DNA gel blot hybridization analysis indicated a single copy of crtL in Synechococcus sp PCC7942. Other than the FAD binding motif, the predicted amino acid sequence of the cyanobacterial lycopene cyclase bears little resemblance to the two known lycopene cyclase enzymes from nonphotosynthetic bacteria. Preliminary results from DNA gel blot hybridization experiments suggest that, like two earlier genes in the pathway, the Synechococcus gene encoding lycopene cyclase is homologous to plant and algal genes encoding this enzyme. PMID:7919981

  2. Dependence of the Cyanobacterium Prochlorococcus on Hydrogen Peroxide Scavenging Microbes for Growth at the Ocean's Surface

    PubMed Central

    Morris, J. Jeffrey; Johnson, Zackary I.; Szul, Martin J.; Keller, Martin; Zinser, Erik R.

    2011-01-01

    The phytoplankton community in the oligotrophic open ocean is numerically dominated by the cyanobacterium Prochlorococcus, accounting for approximately half of all photosynthesis. In the illuminated euphotic zone where Prochlorococcus grows, reactive oxygen species are continuously generated via photochemical reactions with dissolved organic matter. However, Prochlorococcus genomes lack catalase and additional protective mechanisms common in other aerobes, and this genus is highly susceptible to oxidative damage from hydrogen peroxide (HOOH). In this study we showed that the extant microbial community plays a vital, previously unrecognized role in cross-protecting Prochlorococcus from oxidative damage in the surface mixed layer of the oligotrophic ocean. Microbes are the primary HOOH sink in marine systems, and in the absence of the microbial community, surface waters in the Atlantic and Pacific Ocean accumulated HOOH to concentrations that were lethal for Prochlorococcus cultures. In laboratory experiments with the marine heterotroph Alteromonas sp., serving as a proxy for the natural community of HOOH-degrading microbes, bacterial depletion of HOOH from the extracellular milieu prevented oxidative damage to the cell envelope and photosystems of co-cultured Prochlorococcus, and facilitated the growth of Prochlorococcus at ecologically-relevant cell concentrations. Curiously, the more recently evolved lineages of Prochlorococcus that exploit the surface mixed layer niche were also the most sensitive to HOOH. The genomic streamlining of these evolved lineages during adaptation to the high-light exposed upper euphotic zone thus appears to be coincident with an acquired dependency on the extant HOOH-consuming community. These results underscore the importance of (indirect) biotic interactions in establishing niche boundaries, and highlight the impacts that community-level responses to stress may have in the ecological and evolutionary outcomes for co-existing species

  3. Selective and Reversible Inhibition of Active CO2 Transport by Hydrogen Sulfide in a Cyanobacterium 1

    PubMed Central

    Espie, George S.; Miller, Anthony G.; Canvin, David T.

    1989-01-01

    The active transport of CO2 in the cyanobacterium Synechococcus UTEX 625 was inhibited by H2S. Treatment of the cells with up to 150 micromolar H2S + HS− at pH 8.0 had little effect on Na+-dependent HCO3− transport or photosynthetic O2 evolution, but CO2 transport was inhibited by more than 90%. CO2 transport was restored when H2S was removed by flushing with N2. At constant total H2S + HS− concentrations, inhibition of CO2 transport increased as the ratio of H2S to HS− increased, suggesting a direct role for H2S in the inhibitory process. Hydrogen sulfide does not appear to serve as a substrate for transport. In the presence of H2S and Na+ -dependent HCO3− transport, the extracellular CO2 concentration rose considerably above its equilibrium level, but was maintained far below its equilibrium level in the absence of H2S. The inhibition of CO2 transport, therefore, revealed an ongoing leakage from the cells of CO2 which was derived from the intracellular dehydration of HCO3− which itself had been recently transported into the cells. Normally, leaked CO2 is efficiently transported back into the cell by the CO2 transport system, thus maintaining the extracellular CO2 concentration near zero. It is suggested that CO2 transport not only serves as a primary means of inorganic carbon acquisition for photosynthesis but also serves as a means of recovering CO2 lost from the cell. A schematic model describing the relationship between the CO2 and HCO3− transport systems is presented. Images Figure 7 PMID:16667030

  4. Arsenic Demethylation by a C·As Lyase in Cyanobacterium Nostoc sp. PCC 7120.

    PubMed

    Yan, Yu; Ye, Jun; Xue, Xi-Mei; Zhu, Yong-Guan

    2015-12-15

    Arsenic, a ubiquitous toxic substance, exists mainly as inorganic forms in the environment. It is perceived that organoarsenicals can be demethylated and degraded into inorganic arsenic by microorganisms. Few studies have focused on the mechanism of arsenic demethylation in bacteria. Here, we investigated arsenic demethylation in a typical freshwater cyanobacterium Nostoc sp. PCC 7120. This bacterium was able to demethylate monomethylarsenite [MAs(III)] rapidly to arsenite [As(III)] and also had the ability to demethylate monomethylarsenate [MAs(V)] to As(III). The NsarsI encoding a C·As lyase responsible for MAs(III) demethylation was cloned from Nostoc sp. PCC 7120 and heterologously expressed in an As-hypersensitive strain Escherichia coli AW3110 (ΔarsRBC). Expression of NsarsI was shown to confer MAs(III) resistance through arsenic demethylation. The purified NsArsI was further identified and functionally characterized in vitro. NsArsI existed mainly as the trimeric state, and the kinetic data were well-fit to the Hill equation with K0.5 = 7.55 ± 0.33 μM for MAs(III), Vmax = 0.79 ± 0.02 μM min(-1), and h = 2.7. Both of the NsArsI truncated derivatives lacking the C-terminal 10 residues (ArsI10) or 23 residues (ArsI23) had a reduced ability of MAs(III) demethylation. These results provide new insights for understanding the important role of cyanobacteria in arsenic biogeochemical cycling in the environment.

  5. Sustained H2 Production Driven by Photosynthetic Water Splitting in a Unicellular Cyanobacterium

    PubMed Central

    Melnicki, Matthew R.; Pinchuk, Grigoriy E.; Hill, Eric A.; Kucek, Leo A.; Fredrickson, Jim K.; Konopka, Allan; Beliaev, Alexander S.

    2012-01-01

    ABSTRACT The relationship between dinitrogenase-driven H2 production and oxygenic photosynthesis was investigated in a unicellular cyanobacterium, Cyanothece sp. ATCC 51142, using a novel custom-built photobioreactor equipped with advanced process control. Continuously illuminated nitrogen-deprived cells evolved H2 at rates up to 400 µmol ⋅ mg Chl−1 ⋅ h−1 in parallel with uninterrupted photosynthetic O2 production. Notably, sustained coproduction of H2 and O2 occurred over 100 h in the presence of CO2, with both gases displaying inverse oscillations which eventually dampened toward stable rates of 125 and 90 µmol ⋅ mg Chl−1 ⋅ h−1, respectively. Oscillations were not observed when CO2 was omitted, and instead H2 and O2 evolution rates were positively correlated. The sustainability of the process was further supported by stable chlorophyll content, maintenance of baseline protein and carbohydrate levels, and an enhanced capacity for linear electron transport as measured by chlorophyll fluorescence throughout the experiment. In situ light saturation analyses of H2 production displayed a strong dose dependence and lack of O2 inhibition. Inactivation of photosystem II had substantial long-term effects but did not affect short-term H2 production, indicating that the process is also supported by photosystem I activity and oxidation of endogenous glycogen. However, mass balance calculations suggest that carbohydrate consumption in the light may, at best, account for no more than 50% of the reductant required for the corresponding H2 production over that period. Collectively, our results demonstrate that uninterrupted H2 production in unicellular cyanobacteria can be fueled by water photolysis without the detrimental effects of O2 and have important implications for sustainable production of biofuels. PMID:22872781

  6. Buoyancy regulation and the potential for vertical migration in the oceanic cyanobacterium trichodesmium.

    PubMed

    Villareal, T A; Carpenter, E J

    2003-01-01

    Diel protein and carbohydrate content in Trichodesmium thiebautii was measured to evaluate the relationship to buoyancy status. Carbohydrate:protein ratio was the best predictor of buoyancy and fit a cosine curve with increasing values during the day and decreasing values at night in cycles that paralleled observed diel buoyancy patterns. This ratio also increased in short-term experiments as a function of light and increased in parallel with decreasing positive buoyancy. We used changes in this ratio to estimate the potential for vertical migration. Whereas limited vertical excursions in the upper 70 m are possible, deeper migrations appear unlikely unless respiration rates decrease significantly. N:P ratios in sinking and floating colonies were used to test for the P acquisition at depth (vertical migration). We noted that pooled N:P ratios were not significantly different between sinking and ascending colonies (N:P = 65.6 and 66.3, respectively) collected along the northern Australian coast, much like published results from north of Hawaii. Highly significant differences (p <0.0001) were observed in the western Gulf of Mexico between sinking and ascending colonies (N:P = 87.0 and 43.5, respectively) and provide the best direct evidence to date of vertical migration for P acquisition. Our physiological data on compositional changes during buoyancy reversals suggest a complex relationship between light and nutrients. It appears likely that light and P metabolism interact to regulate the vertical extent of migrations, with deep vertical migration regulated by P metabolism superimposed on a mixed-layer light-driven migration. The variability in N:P ratios suggests that care should be taken in assuming buoyancy reversals always result in P acquisition in this oceanic cyanobacterium.

  7. Using oxidized liquid and solid human waste as nutrients for Chlorella vulgaris and cyanobacterium Oscillatoria deflexa

    NASA Astrophysics Data System (ADS)

    Trifonov, Sergey V.; Kalacheva, Galina; Tirranen, Lyalya; Gribovskaya, Iliada

    At stationary terrestrial and space stations with closed and partially closed substance exchange not only plants, but also algae can regenerate atmosphere. Their biomass can be used for feeding Daphnia and Moina species, which, in their turn, serve as food for fish. In addition, it is possible to use algae for production of biological fuel. We suggested two methods of human waste mineralization: dry (evaporation with subsequent incineration in a muffle furnace) and wet (oxidation in a reactor using hydrogen peroxide). The research task was to prepare nutrient media for green alga Chlorella vulgaris and cyanobacterium Oscillatoria deflexa using liquid human waste mineralized by dry method, and to prepare media for chlorella on the basis of 1) liquid and 2) liquid and solid human waste mineralized by wet method. The algae were grown in batch culture in a climate chamber with the following parameters: illumination 7 klx, temperature 27-30 (°) C, culture density 1-2 g/l of dry weight. The control for chlorella was Tamiya medium, pH-5, and for oscillstoria — Zarrouk medium, pH-10. Maximum permissible concentrations of NaCl, Cl, urea (NH _{2}) _{2}CO, and native urine were established for algae. Missing ingredients (such as salts and acids) for experimental nutrient media were determined: their addition made it possible to obtain the biomass production not less than that in the control. The estimation was given of the mineral and biochemical composition of algae grown on experimental media. Microbiological test revealed absence of foreign microbial flora in experimental cultures.

  8. Rapid transient growth at low pH in the cyanobacterium Synechococcus sp.

    PubMed Central

    Kallas, T; Castenholz, R W

    1982-01-01

    The thermophilic cyanobacterium Synechococcus sp. strain Y-7c-s grows at its maximum rate at a high pH (pH 8 and above) the does not show sustained growth below pH 6.5. However, rapidly growing, exponential-phase cells from high-pH cultures continued to grow rapidly for several hours after transfer to pH 6.0 or 5.0. This transient growth represented increases in mass and protein, but cells failed to complete division. Viability loss commenced well before the cessation of growth, and cells at pH 5.0 showed no net DNA synthesis. When irradiated by visible light, cells at pH 6.0 and 5.0 maintained and internal pH of 6.9 to 7.1 (determined by 31P nuclear magnetic resonance spectroscopy) and an extremely high ATP/(ATP + ADP) ratio even after growth had ceased. Cells exposed to a low pH did not show an increase in the spontaneous mutation rate, as measured by mutation to streptomycin resistance. However, cells already resistant to streptomycin were more resistant to viability loss at a low pH than the parental type. Cultures that could grow transiently at a low pH had higher rates of viability loss than nongrowing cultures in light or darkness. The retention of a high internal pH by cells exposed to a low pH suggested that a low pH acted initially on the cell membrane, possibly on solute transport. PMID:6798020

  9. The biosynthetic pathway for myxol-2' fucoside (myxoxanthophyll) in the cyanobacterium Synechococcus sp. strain PCC 7002.

    PubMed

    Graham, Joel E; Bryant, Donald A

    2009-05-01

    Synechococcus sp. strain PCC 7002 produces a variety of carotenoids, which comprise predominantly dicylic beta-carotene and two dicyclic xanthophylls, zeaxanthin and synechoxanthin. However, this cyanobacterium also produces a monocyclic myxoxanthophyll, which was identified as myxol-2' fucoside. Compared to the carotenoid glycosides produced by diverse microorganisms, cyanobacterial myxoxanthophyll and closely related compounds are unusual because they are glycosylated on the 2'-OH rather than on the 1'-OH position of the psi end of the molecule. In this study, the genes encoding two enzymes that modify the psi end of myxoxanthophyll in Synechococcus sp. strain PCC 7002 were identified. Mutational and biochemical studies showed that open reading frame SynPCC7002_A2032, renamed cruF, encodes a 1',2'-hydroxylase [corrected] and that open reading frame SynPCC7002_A2031, renamed cruG, encodes a 2'-O-glycosyltransferase. The enzymatic activity of CruF was verified by chemical characterization of the carotenoid products synthesized when cruF was expressed in a lycopene-producing strain of Escherichia coli. Database searches showed that homologs of cruF and cruG occur in the genomes of all sequenced cyanobacterial strains that are known to produce myxol or the acylic xanthophyll oscillaxanthin. The genomes of many other bacteria that produce hydroxylated carotenoids but do not contain crtC homologs also contain cruF orthologs. Based upon observable intermediates, a complete biosynthetic pathway for myxoxanthophyll is proposed. This study expands the suite of enzymes available for metabolic engineering of carotenoid biosynthetic pathways for biotechnological applications.

  10. Multiplicity and specificity of siderophore uptake in the cyanobacterium Anabaena sp. PCC 7120.

    PubMed

    Rudolf, Mareike; Stevanovic, Mara; Kranzler, Chana; Pernil, Rafael; Keren, Nir; Schleiff, Enrico

    2016-09-01

    Many cyanobacteria secrete siderophores to sequester iron. Alternatively, mechanisms to utilize xenosiderophores have evolved. The overall uptake systems are comparable to that of other bacteria involving outer membrane transporters energized by TonB as well as plasma membrane-localized transporters. However, the function of the bioinformatically-inferred components is largely not established and recent studies showed a high diversity of the complexity of the uptake systems in different cyanobacteria. Thus, we approached the systems of the filamentous Anabaena sp. PCC 7120 as a model of a siderophore-secreting cyanobacterium. Anabaena sp. produces schizokinen and uptake of Fe-schizokinen involves the TonB-dependent transporter, schizokinen transporter (SchT), and the ABC-type transport system FhuBCD. We confirm that this system is also relevant for the uptake of structurally similar Fe-siderophore complexes like Fe-aerobactin. Moreover, we demonstrate a function of the TonB-dependent transporter IutA2 in Fe-schizokinen uptake in addition to SchT. The iutA2 mutant shows growth defects upon iron limitation, alterations in Fe-schizokinen uptake and in the transcription profile of the Fe-schizokinen uptake system. The physiological properties of the mutant confirm the importance of iron uptake for cellular function, e.g. for the Krebs cycle. Based on the relative relation of expression of schT and iutA2 as well as of the iron uptake rate to the degree of starvation, a model for the need of the co-existence of two different outer membrane transporters for the same substrate is discussed. PMID:27325117

  11. A Novel Nitrate/Nitrite Permease in the Marine Cyanobacterium Synechococcus sp. Strain PCC 7002

    PubMed Central

    Sakamoto, Toshio; Inoue-Sakamoto, Kaori; Bryant, Donald A.

    1999-01-01

    The nrtP and narB genes, encoding nitrate/nitrite permease and nitrate reductase, respectively, were isolated from the marine cyanobacterium Synechococcus sp. strain PCC 7002 and characterized. NrtP is a member of the major facilitator superfamily and is unrelated to the ATP-binding cassette-type nitrate transporters that previously have been described for freshwater strains of cyanobacteria. However, NrtP is similar to the NRT2-type nitrate transporters found in diverse organisms. An nrtP mutant strain consumes nitrate at a 4.5-fold-lower rate than the wild type, and this mutant grew exponentially on a medium containing 12 mM nitrate at a rate approximately 2-fold lower than that of the wild type. The nrtP mutant cells could not consume nitrite as rapidly as the wild type at pH 10, suggesting that NrtP also functions in nitrite uptake. A narB mutant was unable to grow on a medium containing nitrate as a nitrogen source, although this mutant could grow on media containing urea or nitrite with rates similar to those of the wild type. Exogenously added nitrite enhanced the in vivo activity of nitrite reductase in the narB mutant; this suggests that nitrite acts as a positive effector of nitrite reductase. Transcripts of the nrtP and narB genes were detected in cells grown on nitrate but were not detected in cells grown on urea or ammonia. Transcription of the nrtP and narB genes is probably controlled by the NtcA transcription factor for global nitrogen control. The discovery of a nitrate/nitrite permease in Synechococcus sp. strain PCC 7002 suggests that significant differences in nutrient transporters may occur in marine and freshwater cyanobacteria. PMID:10572142

  12. Molecular markers define progressing stages of phosphorus limitation in the nitrogen-fixing cyanobacterium, Crocosphaera.

    PubMed

    Pereira, Nicole; Shilova, Irina N; Zehr, Jonathan P

    2016-04-01

    Crocosphaera watsonii is a marine cyanobacterium that frequently inhabits low phosphate environments in oligotrophic oceans. While C. watsonii has the ability to fix atmospheric nitrogen, its growth may be limited by availability of phosphorus. Biomarkers that indicate cellular phosphorus status give insight into how P-limitation can affect the distribution of nitrogen-fixing cyanobacterial populations. However, adaptation to phosphorus stress is complex and one marker may not be sufficient to determine when an organism is P-limited. In this study, we characterized the transcription of key genes, activated during phosphorus stress in C. watsonii WH8501, to determine how transcription changed during the phosphorus stress response. Transcription of pstS, which encodes a high-affinity phosphate binding protein, was discovered to be quickly up-regulated in phosphorus-depleted cells as an immediate stress response; however, its transcription declined after a period of phosphorus starvation. In addition, diel regulation of pstS in C. watsonii WH8501 complicates the interpretation of this marker in field applications. Transcription of the gene coding for the arsenite efflux protein, arsB, was upregulated after pstS in phosphorus limited cells, but it remained upregulated at later stages of phosphorus limitation. These results demonstrate that a single molecular marker does not adequately represent the entire phosphorus stress response in C. watsonii WH8501. Using both markers, the variations in transcriptional response over a range of degrees of phosphorus limitation may be a better approach for defining cellular phosphorus status. PMID:27037592

  13. Global transcriptional profiles of the copper responses in the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Giner-Lamia, Joaquin; López-Maury, Luis; Florencio, Francisco J

    2014-01-01

    Copper is an essential element involved in fundamental processes like respiration and photosynthesis. However, it becomes toxic at high concentration, which has forced organisms to control its cellular concentration. We have recently described a copper resistance system in the cyanobacterium Synechocystis sp. PCC 6803, which is mediated by the two-component system, CopRS, a RND metal transport system, CopBAC and a protein of unknown function, CopM. Here, we report the transcriptional responses to copper additions at non-toxic (0.3 µM) and toxic concentrations (3 µM) in the wild type and in the copper sensitive copR mutant strain. While 0.3 µM copper slightly stimulated metabolism and promoted the exchange between cytochrome c6 and plastocyanin as soluble electron carriers, the addition of 3 µM copper catalyzed the formation of ROS, led to a general stress response and induced expression of Fe-S cluster biogenesis genes. According to this, a double mutant strain copRsufR, which expresses constitutively the sufBCDS operon, tolerated higher copper concentration than the copR mutant strain, suggesting that Fe-S clusters are direct targets of copper toxicity in Synechocystis. In addition we have also demonstrated that InrS, a nickel binding transcriptional repressor that belong to the CsoR family of transcriptional factor, was involved in heavy metal homeostasis, including copper, in Synechocystis. Finally, global gene expression analysis of the copR mutant strain suggested that CopRS only controls the expression of copMRS and copBAC operons in response to copper. PMID:25268225

  14. Structural and biochemical characterization of a cyanobacterium circadian clock-modifier protein.

    PubMed

    Arita, Kyouhei; Hashimoto, Hiroshi; Igari, Kumiko; Akaboshi, Mayuko; Kutsuna, Shinsuke; Sato, Mamoru; Shimizu, Toshiyuki

    2007-01-12

    Circadian clocks are self-sustained biochemical oscillators. The oscillator of cyanobacteria comprises the products of three kai genes (kaiA, kaiB, and kaiC). The autophosphorylation cycle of KaiC oscillates robustly in the cell with a 24-h period and is essential for the basic timing of the cyanobacterial circadian clock. Recently, period extender (pex), mutants of which show a short period phenotype, was classified as a resetting-related gene. In fact, pex mRNA and the pex protein (Pex) increase during the dark period, and a pex mutant subjected to diurnal light-dark cycles shows a 3-h advance in rhythm phase. Here, we report the x-ray crystallographic analysis and biochemical characterization of Pex from cyanobacterium Synechococcus elongatus PCC 7942. The molecule has an (alpha+beta) structure with a winged-helix motif and is indicated to function as a dimer. The subunit arrangement in the dimer is unique and has not been seen in other winged-helix proteins. Electrophoresis mobility shift assay using a 25-base pair complementary oligonucleotide incorporating the kaiA upstream sequence demonstrates that Pex has an affinity for the double-stranded DNA. Furthermore, mutation analysis shows that Pex uses the wing region to recognize the DNA. The in vivo rhythm assay of Pex shows that the constitutive expression of the pex gene harboring the mutation that fails to bind to DNA lacks the period-prolongation activity in the pex-deficient Synechococcus, suggesting that Pex is a DNA-binding transcription factor.

  15. Competition and facilitation between the marine nitrogen-fixing cyanobacterium Cyanothece and its associated bacterial community

    PubMed Central

    Brauer, Verena S.; Stomp, Maayke; Bouvier, Thierry; Fouilland, Eric; Leboulanger, Christophe; Confurius-Guns, Veronique; Weissing, Franz J.; Stal, LucasJ.; Huisman, Jef

    2014-01-01

    N2-fixing cyanobacteria represent a major source of new nitrogen and carbon for marine microbial communities, but little is known about their ecological interactions with associated microbiota. In this study we investigated the interactions between the unicellular N2-fixing cyanobacterium Cyanothece sp. Miami BG043511 and its associated free-living chemotrophic bacteria at different concentrations of nitrate and dissolved organic carbon and different temperatures. High temperature strongly stimulated the growth of Cyanothece, but had less effect on the growth and community composition of the chemotrophic bacteria. Conversely, nitrate and carbon addition did not significantly increase the abundance of Cyanothece, but strongly affected the abundance and species composition of the associated chemotrophic bacteria. In nitrate-free medium the associated bacterial community was co-dominated by the putative diazotroph Mesorhizobium and the putative aerobic anoxygenic phototroph Erythrobacter and after addition of organic carbon also by the Flavobacterium Muricauda. Addition of nitrate shifted the composition toward co-dominance by Erythrobacter and the Gammaproteobacterium Marinobacter. Our results indicate that Cyanothece modified the species composition of its associated bacteria through a combination of competition and facilitation. Furthermore, within the bacterial community, niche differentiation appeared to play an important role, contributing to the coexistence of a variety of different functional groups. An important implication of these findings is that changes in nitrogen and carbon availability due to, e.g., eutrophication and climate change are likely to have a major impact on the species composition of the bacterial community associated with N2-fixing cyanobacteria. PMID:25642224

  16. Isolation and in silico analysis of Fe-superoxide dismutase in the cyanobacterium Nostoc commune.

    PubMed

    Kesheri, Minu; Kanchan, Swarna; Richa; Sinha, Rajeshwar P

    2014-12-15

    Cyanobacteria are known to endure various stress conditions due to the inbuilt potential for oxidative stress alleviation owing to the presence of an array of antioxidants. The present study shows that Antarctic cyanobacterium Nostoc commune possesses two antioxidative enzymes viz., superoxide dismutase (SOD) and catalase that jointly cope with environmental stresses prevailing at its natural habitat. Native-PAGE analysis illustrates the presence of a single prominent isoform recognized as Fe-SOD and three distinct isoforms of catalase. The protein sequence of Fe-SOD in N. commune retrieved from NCBI protein sequence database was used for in silico analysis. 3D structure of N. commune was predicted by comparative modeling using MODELLER 9v11. Further, this model was validated for its quality by Ramachandran plot, ERRAT, Verify 3D and ProSA-web which revealed good structure quality of the model. Multiple sequence alignment showed high conservation in N and C-terminal domain regions along with all metal binding positions in Fe-SOD which were also found to be highly conserved in all 28 cyanobacterial species under study, including N. commune. In silico prediction of isoelectric point and molecular weight of Fe-SOD was found to be 5.48 and 22,342.98Da respectively. The phylogenetic tree revealed that among 28 cyanobacterial species, Fe-SOD in N. commune was the closest evolutionary homolog of Fe-SOD in Nostoc punctiforme as evident by strong bootstrap value. Thus, N. commune may serve as a good biological model for studies related to survival of life under extreme conditions prevailing at the Antarctic region. Moreover cyanobacteria may be exploited for biochemical and biotechnological applications of enzymatic antioxidants.

  17. Ultrafast dynamics of phytochrome from the cyanobacterium synechocystis, reconstituted with phycocyanobilin and phycoerythrobilin.

    PubMed Central

    Heyne, Karsten; Herbst, Johannes; Stehlik, Dietmar; Esteban, Berta; Lamparter, Tilman; Hughes, Jon; Diller, Rolf

    2002-01-01

    Femtosecond time-resolved transient absorption spectroscopy was employed to characterize for the first time the primary photoisomerization dynamics of a bacterial phytochrome system in the two thermally stable states of the photocycle. The 85-kDa phytochrome Cph1 from the cyanobacterium Synechocystis PCC 6803 expressed in Escherichia coli was reconstituted with phycocyanobilin (Cph1-PCB) and phycoerythrobilin (Cph1-PEB). The red-light-absorbing form Pr of Cph1-PCB shows an approximately 150 fs relaxation in the S(1) state after photoexcitation at 650 nm. The subsequent Z-E isomerization between rings C and D of the linear tetrapyrrole-chromophore is best described by a distribution of rate constants with the first moment at (16 ps)(-1). Excitation at 615 nm leads to a slightly broadened distribution. The reverse E-Z isomerization, starting from the far-red-absorbing form Pfr, is characterized by two shorter time constants of 0.54 and 3.2 ps. In the case of Cph1-PEB, double-bond isomerization does not take place, and the excited-state lifetime extends into the nanosecond regime. Besides a stimulated emission rise time between 40 and 150 fs, no fast relaxation processes are observed. This suggests that the chromophore-protein interaction along rings A, B, and C does not contribute much to the picosecond dynamics observed in Cph1-PCB but rather the region around ring D near the isomerizing C(15) [double bond] C(16) double bond. The primary reaction dynamics of Cph1-PCB at ambient temperature is found to exhibit very similar features as those described for plant type A phytochrome, i.e., a relatively slow Pr, and a fast Pfr, photoreaction. This suggests that the initial reactions were established already before evolution of plant phytochromes began. PMID:11806940

  18. Chemoheterotrophic Growth of the Cyanobacterium Anabaena sp. Strain PCC 7120 Dependent on a Functional Cytochrome c Oxidase

    PubMed Central

    Stebegg, Ronald; Wurzinger, Bernhard; Mikulic, Markus

    2012-01-01

    Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium commonly used as a model organism for studying cyanobacterial cell differentiation and nitrogen fixation. For many decades, this cyanobacterium was considered an obligate photo-lithoautotroph. We now discovered that this strain is also capable of mixotrophic, photo-organoheterotrophic, and chemo-organoheterotrophic growth if high concentrations of fructose (at least 50 mM and up to 200 mM) are supplied. Glucose, a substrate used by some facultatively organoheterotrophic cyanobacteria, is not effective in Anabaena sp. PCC 7120. The gtr gene from Synechocystis sp. PCC 6803 encoding a glucose carrier was introduced into Anabaena sp. PCC 7120. Surprisingly, the new strain containing the gtr gene did not grow on glucose but was very sensitive to glucose, with a 5 mM concentration being lethal, whereas the wild-type strain tolerated 200 mM glucose. The Anabaena sp. PCC 7120 strain containing gtr can grow mixotrophically and photo-organoheterotrophically, but not chemo-organoheterotrophically with fructose. Anabaena sp. PCC 7120 contains five respiratory chains ending in five different respiratory terminal oxidases. One of these enzymes is a mitochondrial-type cytochrome c oxidase. As in almost all cyanobacteria, this enzyme is encoded by three adjacent genes called coxBAC1. When this locus was disrupted, the cells lost the capability for chemo-organoheterotrophic growth. PMID:22730128

  19. Pathway-level acceleration of glycogen catabolism by a response regulator in the cyanobacterium Synechocystis species PCC 6803.

    PubMed

    Osanai, Takashi; Oikawa, Akira; Numata, Keiji; Kuwahara, Ayuko; Iijima, Hiroko; Doi, Yoshiharu; Saito, Kazuki; Hirai, Masami Yokota

    2014-04-01

    Response regulators of two-component systems play pivotal roles in the transcriptional regulation of responses to environmental signals in bacteria. Rre37, an OmpR-type response regulator, is induced by nitrogen depletion in the unicellular cyanobacterium Synechocystis species PCC 6803. Microarray and quantitative real-time polymerase chain reaction analyses revealed that genes related to sugar catabolism and nitrogen metabolism were up-regulated by rre37 overexpression. Protein levels of GlgP(slr1367), one of the two glycogen phosphorylases, in the rre37-overexpressing strain were higher than those of the parental wild-type strain under both nitrogen-replete and nitrogen-depleted conditions. Glycogen amounts decreased to less than one-tenth by rre37 overexpression under nitrogen-replete conditions. Metabolome analysis revealed that metabolites of the sugar catabolic pathway and amino acids were altered in the rre37-overexpressing strain after nitrogen depletion. These results demonstrate that Rre37 is a pathway-level regulator that activates the metabolic flow from glycogen to polyhydroxybutyrate and the hybrid tricarboxylic acid and ornithine cycle, unraveling the mechanism of the transcriptional regulation of primary metabolism in this unicellular cyanobacterium.

  20. Spectral properties of bacteriophytochrome AM1_5894 in the chlorophyll d-containing cyanobacterium Acaryochloris marina.

    PubMed

    Loughlin, Patrick C; Duxbury, Zane; Mugerwa, Tendo T Mukasa; Smith, Penelope M C; Willows, Robert D; Chen, Min

    2016-01-01

    Acaryochloris marina, a unicellular oxygenic photosynthetic cyanobacterium, has uniquely adapted to far-red light-enriched environments using red-shifted chlorophyll d. To understand red-light use in Acaryochloris, the genome of this cyanobacterium was searched for red/far-red light photoreceptors from the phytochrome family, resulting in identification of a putative bacteriophytochrome AM1_5894. AM1_5894 contains three standard domains of photosensory components as well as a putative C-terminal signal transduction component consisting of a histidine kinase and receiver domain. The photosensory domains of AM1_5894 autocatalytically assemble with biliverdin in a covalent fashion. This assembled AM1_5894 shows the typical photoreversible conversion of bacterial phytochromes with a ground-state red-light absorbing (Pr) form with λBV max[Pr] 705 nm, and a red-light inducible far-red light absorbing (Pfr) form with λBV max[Pfr] 758 nm. Surprisingly, AM1_5894 also autocatalytically assembles with phycocyanobilin, involving photoreversible conversion of λPCB max[Pr] 682 nm and λPCB max[Pfr] 734 nm, respectively. Our results suggest phycocyanobilin is also covalently bound to AM1_5894, while mutation of a cysteine residue (Cys11Ser) abolishes this covalent binding. The physiological function of AM1_5894 in cyanobacteria containing red-shifted chlorophylls is discussed. PMID:27282102

  1. A Nostoc punctiforme Sugar Transporter Necessary to Establish a Cyanobacterium-Plant Symbiosis1[C][W

    PubMed Central

    Ekman, Martin; Picossi, Silvia; Campbell, Elsie L.; Meeks, John C.; Flores, Enrique

    2013-01-01

    In cyanobacteria-plant symbioses, the symbiotic nitrogen-fixing cyanobacterium has low photosynthetic activity and is supplemented by sugars provided by the plant partner. Which sugars and cyanobacterial sugar uptake mechanism(s) are involved in the symbiosis, however, is unknown. Mutants of the symbiotically competent, facultatively heterotrophic cyanobacterium Nostoc punctiforme were constructed bearing a neomycin resistance gene cassette replacing genes in a putative sugar transport gene cluster. Results of transport activity assays using 14C-labeled fructose and glucose and tests of heterotrophic growth with these sugars enabled the identification of an ATP-binding cassette-type transporter for fructose (Frt), a major facilitator permease for glucose (GlcP), and a porin needed for the optimal uptake of both fructose and glucose. Analysis of green fluorescent protein fluorescence in strains of N. punctiforme bearing frt::gfp fusions showed high expression in vegetative cells and akinetes, variable expression in hormogonia, and no expression in heterocysts. The symbiotic efficiency of N. punctiforme sugar transport mutants was investigated by testing their ability to infect a nonvascular plant partner, the hornwort Anthoceros punctatus. Strains that were specifically unable to transport glucose did not infect the plant. These results imply a role for GlcP in establishing symbiosis under the conditions used in this work. PMID:23463784

  2. Spectral properties of bacteriophytochrome AM1_5894 in the chlorophyll d-containing cyanobacterium Acaryochloris marina

    PubMed Central

    Loughlin, Patrick C.; Duxbury, Zane; Mugerwa, Tendo T. Mukasa; Smith, Penelope M. C.; Willows, Robert D.; Chen, Min

    2016-01-01

    Acaryochloris marina, a unicellular oxygenic photosynthetic cyanobacterium, has uniquely adapted to far-red light-enriched environments using red-shifted chlorophyll d. To understand red-light use in Acaryochloris, the genome of this cyanobacterium was searched for red/far-red light photoreceptors from the phytochrome family, resulting in identification of a putative bacteriophytochrome AM1_5894. AM1_5894 contains three standard domains of photosensory components as well as a putative C-terminal signal transduction component consisting of a histidine kinase and receiver domain. The photosensory domains of AM1_5894 autocatalytically assemble with biliverdin in a covalent fashion. This assembled AM1_5894 shows the typical photoreversible conversion of bacterial phytochromes with a ground-state red-light absorbing (Pr) form with λBV max[Pr] 705 nm, and a red-light inducible far-red light absorbing (Pfr) form with λBV max[Pfr] 758 nm. Surprisingly, AM1_5894 also autocatalytically assembles with phycocyanobilin, involving photoreversible conversion of λPCB max[Pr] 682 nm and λPCB max[Pfr] 734 nm, respectively. Our results suggest phycocyanobilin is also covalently bound to AM1_5894, while mutation of a cysteine residue (Cys11Ser) abolishes this covalent binding. The physiological function of AM1_5894 in cyanobacteria containing red-shifted chlorophylls is discussed. PMID:27282102

  3. Chemoheterotrophic growth of the Cyanobacterium Anabaena sp. strain PCC 7120 dependent on a functional cytochrome c oxidase.

    PubMed

    Stebegg, Ronald; Wurzinger, Bernhard; Mikulic, Markus; Schmetterer, Georg

    2012-09-01

    Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium commonly used as a model organism for studying cyanobacterial cell differentiation and nitrogen fixation. For many decades, this cyanobacterium was considered an obligate photo-lithoautotroph. We now discovered that this strain is also capable of mixotrophic, photo-organoheterotrophic, and chemo-organoheterotrophic growth if high concentrations of fructose (at least 50 mM and up to 200 mM) are supplied. Glucose, a substrate used by some facultatively organoheterotrophic cyanobacteria, is not effective in Anabaena sp. PCC 7120. The gtr gene from Synechocystis sp. PCC 6803 encoding a glucose carrier was introduced into Anabaena sp. PCC 7120. Surprisingly, the new strain containing the gtr gene did not grow on glucose but was very sensitive to glucose, with a 5 mM concentration being lethal, whereas the wild-type strain tolerated 200 mM glucose. The Anabaena sp. PCC 7120 strain containing gtr can grow mixotrophically and photo-organoheterotrophically, but not chemo-organoheterotrophically with fructose. Anabaena sp. PCC 7120 contains five respiratory chains ending in five different respiratory terminal oxidases. One of these enzymes is a mitochondrial-type cytochrome c oxidase. As in almost all cyanobacteria, this enzyme is encoded by three adjacent genes called coxBAC1. When this locus was disrupted, the cells lost the capability for chemo-organoheterotrophic growth.

  4. Analysis of UV-absorbing photoprotectant mycosporine-like amino acid (MAA) in the cyanobacterium Arthrospira sp. CU2556.

    PubMed

    Rastogi, Rajesh P; Incharoensakdi, Aran

    2014-07-01

    Mycosporine-like amino acids (MAAs) are ecologically important biomolecules with great photoprotective potential. The present study aimed to investigate the biosynthesis of MAAs in the cyanobacterium Arthrospira sp. CU2556. High-performance liquid chromatography (HPLC) with photodiode-array detection studies revealed the presence of a UV-absorbing compound with an absorption maximum at 310 nm. Based on its UV absorption spectrum and ion trap liquid chromatography/mass spectrometry (LC/MS) analysis, the compound was identified as a primary MAA mycosporine-glycine (m/z: 246). To the best of our knowledge this is the first report on the occurrence of MAA mycosporine-glycine (M-Gly) in Arthrospira strains studied so far. In contrast to photosynthetic activity under UV-A radiation, the induction of the biosynthesis of M-Gly was significantly more prominent under UV-B radiation. The content of M-Gly was found to increase with the increase in exposure time under UV-B radiation. The MAA M-Gly was highly stable under UV radiation, heat, strongly acidic and alkaline conditions. It also exhibited good antioxidant activity and photoprotective ability by detoxifying the in vivo reactive oxygen species (ROS) generated by UV radiation. Our results indicate that the studied cyanobacterium may protect itself by synthesizing the UV-absorbing/screening compounds as important defense mechanisms, in their natural brightly-lit habitat with high solar UV-B fluxes.

  5. Alkane production by the marine cyanobacterium Synechococcus sp. NKBG15041c possessing the α-olefin biosynthesis pathway.

    PubMed

    Yoshino, Tomoko; Liang, Yue; Arai, Daichi; Maeda, Yoshiaki; Honda, Toru; Muto, Masaki; Kakunaka, Natsumi; Tanaka, Tsuyoshi

    2015-02-01

    The production of alkanes in a marine cyanobacterium possessing the α-olefin biosynthesis pathway was achieved by introducing an exogenous alkane biosynthesis pathway. Cyanobacterial hydrocarbons are synthesized via two separate pathways: the acyl-acyl carrier protein (ACP) reductase/aldehyde-deformylating oxygenase (AAR/ADO) pathway for the alkane biosynthesis and the α-olefin synthase (OLS) pathway for the α-olefin biosynthesis. Coexistence of these pathways has not yet been reported. In this study, the marine cyanobacterium Synechococcus sp. NKBG15041c was shown to produce α-olefins similar to those of Synechococcus sp. PCC7002 via the α-olefin biosynthesis pathway. The production of heptadecane in Synechococcus sp. NKBG15041c was achieved by expressing the AAR/ADO pathway genes from Synechococcus elongatus PCC 7942. The production yields of heptadecane in Synechococcus sp. NKBG15041c varied with the expression level of the aar and ado genes. The maximal yield of heptadecane was 4.2 ± 1.2 μg/g of dried cell weight in the transformant carrying a homologous promoter. Our results also suggested that the effective activation of ADO may be more important for the enhancement of alkane production by cyanobacteria.

  6. Complete Genome Sequence of a Cylindrospermopsin-Producing Cyanobacterium, Cylindrospermopsis raciborskii CS505, Containing a Circular Chromosome and a Single Extrachromosomal Element

    PubMed Central

    Fuentes-Valdés, Juan J.; Plominsky, Alvaro M.; Allen, Eric E.; Tamames, Javier

    2016-01-01

    Cylindrospermopsis raciborskii is a freshwater cyanobacterium producing bloom events and toxicity in drinking water source reservoirs. We present the first genome sequence for C. raciborskii CS505 (Australia), containing one 4.1-Mbp chromosome and one 110-Kbp plasmid having G+C contents of 40.3% (3933 genes) and 39.3% (111 genes), respectively. PMID:27563040

  7. Complete Genome Sequence of a Cylindrospermopsin-Producing Cyanobacterium, Cylindrospermopsis raciborskii CS505, Containing a Circular Chromosome and a Single Extrachromosomal Element.

    PubMed

    Fuentes-Valdés, Juan J; Plominsky, Alvaro M; Allen, Eric E; Tamames, Javier; Vásquez, Mónica

    2016-01-01

    Cylindrospermopsis raciborskii is a freshwater cyanobacterium producing bloom events and toxicity in drinking water source reservoirs. We present the first genome sequence for C. raciborskii CS505 (Australia), containing one 4.1-Mbp chromosome and one 110-Kbp plasmid having G+C contents of 40.3% (3933 genes) and 39.3% (111 genes), respectively. PMID:27563040

  8. Photoautotrophic production of D-lactic acid in an engineered cyanobacterium

    PubMed Central

    2013-01-01

    Background The world faces the challenge to develop sustainable technologies to replace thousands of products that have been generated from fossil fuels. Microbial cell factories serve as promising alternatives for the production of diverse commodity chemicals and biofuels from renewable resources. For example, polylactic acid (PLA) with its biodegradable properties is a sustainable, environmentally friendly alternative to polyethylene. At present, PLA microbial production is mainly dependent on food crops such as corn and sugarcane. Moreover, optically pure isomers of lactic acid are required for the production of PLA, where D-lactic acid controls the thermochemical and physical properties of PLA. Henceforth, production of D-lactic acid through a more sustainable source (CO2) is desirable. Results We have performed metabolic engineering on Synechocystis sp. PCC 6803 for the phototrophic synthesis of optically pure D-lactic acid from CO2. Synthesis of optically pure D-lactic acid was achieved by utilizing a recently discovered enzyme (i.e., a mutated glycerol dehydrogenase, GlyDH*). Significant improvements in D-lactic acid synthesis were achieved through codon optimization and by balancing the cofactor (NADH) availability through the heterologous expression of a soluble transhydrogenase. We have also discovered that addition of acetate to the cultures improved lactic acid production. More interestingly, 13C-pathway analysis revealed that acetate was not used for the synthesis of lactic acid, but was mainly used for synthesis of certain biomass building blocks (such as leucine and glutamate). Finally, the optimal strain was able to accumulate 1.14 g/L (photoautotrophic condition) and 2.17 g/L (phototrophic condition with acetate) of D-lactate in 24 days. Conclusions We have demonstrated the photoautotrophic production of D-lactic acid by engineering a cyanobacterium Synechocystis 6803. The engineered strain shows an excellent D-lactic acid productivity from CO2. In

  9. Temporal dynamics of ROS biogenesis under simulated solar radiation in the cyanobacterium Anabaena variabilis PCC 7937.

    PubMed

    Singh, Shailendra P; Rastogi, Rajesh P; Häder, Donat-P; Sinha, Rajeshwar P

    2014-09-01

    We studied the temporal generation of reactive oxygen species (ROS) in the cyanobacterium Anabaena variabilis PCC 7937 under simulated solar radiation using WG 280, WG 295, WG 305, WG 320, WG 335, WG 345, and GG 400 nm cut-off filters to find out the minimum exposure time and most effective region of the solar spectrum inducing highest level of ROS. There was no significant generation of ROS in all treatments in comparison to the samples kept in the dark during the first 8 h of exposure; however, after 12 h of exposure, ROS were significantly generated in samples covered with 305, 295, or 280 nm cut-off filters. In contrast with ROS, the fragmentation of filaments was predominantly seen in 280 nm cut-off filter covered samples after 12 h of exposure. After 24 h of exposure, ROS levels were significantly higher in all samples than in the dark; however, the ROS signals were more pronounced in 320, 305, 295, or 280 nm cut-off filter covered samples. In contrast, the length of filaments was reduced in 305, 295, or 280 nm cut-off filter covered samples after 24 h of exposure. Thus, fragmentation of the filament was induced by all wavelengths of the UV-B region contrary to the UV-A region where only shorter wavelengths were able to induce the fragmentation. In contrast, ROS were generated by all wavelengths of the solar spectrum after 24 h of exposure; however, shorter wavelengths of both the UV-A and the UV-B regions were more effective in generating ROS in comparison to their higher wavelengths and photosynthetic active radiation (PAR). Moreover, lower wavelengths of UV-B were more efficient than the lower wavelengths of the UV-A radiation. Findings from this study suggest that certain threshold levels of ROS are required to induce the fragmentation of filaments.

  10. Comparative genomic analyses of the cyanobacterium, Lyngbya aestuarii BL J, a powerful hydrogen producer

    PubMed Central

    Kothari, Ankita; Vaughn, Michael; Garcia-Pichel, Ferran

    2013-01-01

    The filamentous, non-heterocystous cyanobacterium Lyngbya aestuarii is an important contributor to marine intertidal microbial mats system worldwide. The recent isolate L. aestuarii BL J, is an unusually powerful hydrogen producer. Here we report a morphological, ultrastructural, and genomic characterization of this strain to set the basis for future systems studies and applications of this organism. The filaments contain circa 17 μm wide trichomes, composed of stacked disk-like short cells (2 μm long), encased in a prominent, laminated exopolysaccharide sheath. Cellular division occurs by transversal centripetal growth of cross-walls, where several rounds of division proceed simultaneously. Filament division occurs by cell self-immolation of one or groups of cells (necridial cells) at the breakage point. Short, sheath-less, motile filaments (hormogonia) are also formed. Morphologically and phylogenetically L. aestuarii belongs to a clade of important cyanobacteria that include members of the marine Trichodesmiun and Hydrocoleum genera, as well as terrestrial Microcoleus vaginatus strains, and alkalyphilic strains of Arthrospira. A draft genome of strain BL J was compared to those of other cyanobacteria in order to ascertain some of its ecological constraints and biotechnological potential. The genome had an average GC content of 41.1%. Of the 6.87 Mb sequenced, 6.44 Mb was present as large contigs (>10,000 bp). It contained 6515 putative protein-encoding genes, of which, 43% encode proteins of known functional role, 26% corresponded to proteins with domain or family assignments, 19.6% encode conserved hypothetical proteins, and 11.3% encode apparently unique hypothetical proteins. The strain's genome reveals its adaptations to a life of exposure to intense solar radiation and desiccation. It likely employs the storage compounds, glycogen, and cyanophycin but no polyhydroxyalkanoates, and can produce the osmolytes, trehalose, and glycine betaine. According to its

  11. The leaves of green plants as well as a cyanobacterium, a red alga, and fungi contain insulin-like antigens.

    PubMed

    Silva, L B; Santos, S S S; Azevedo, C R; Cruz, M A L; Venâncio, T M; Cavalcante, C P; Uchôa, A F; Astolfi Filho, S; Oliveira, A E A; Fernandes, K V S; Xavier-Filho, J

    2002-03-01

    We report the detection of insulin-like antigens in a large range of species utilizing a modified ELISA plate assay and Western blotting. We tested the leaves or aerial parts of species of Rhodophyta (red alga), Bryophyta (mosses), Psilophyta (whisk ferns), Lycopodophyta (club mosses), Sphenopsida (horsetails), gymnosperms, and angiosperms, including monocots and dicots. We also studied species of fungi and a cyanobacterium, Spirulina maxima. The wide distribution of insulin-like antigens, which in some cases present the same electrophoretic mobility as bovine insulin, together with results recently published by us on the amino acid sequence of an insulin isolated from the seed coat of jack bean (Canavalia ensiformis) and from the developing fruits of cowpea (Vigna unguiculata), suggests that pathways depending on this hormone have been conserved through evolution.

  12. The leaves of green plants as well as a cyanobacterium, a red alga, and fungi contain insulin-like antigens.

    PubMed

    Silva, L B; Santos, S S S; Azevedo, C R; Cruz, M A L; Venâncio, T M; Cavalcante, C P; Uchôa, A F; Astolfi Filho, S; Oliveira, A E A; Fernandes, K V S; Xavier-Filho, J

    2002-03-01

    We report the detection of insulin-like antigens in a large range of species utilizing a modified ELISA plate assay and Western blotting. We tested the leaves or aerial parts of species of Rhodophyta (red alga), Bryophyta (mosses), Psilophyta (whisk ferns), Lycopodophyta (club mosses), Sphenopsida (horsetails), gymnosperms, and angiosperms, including monocots and dicots. We also studied species of fungi and a cyanobacterium, Spirulina maxima. The wide distribution of insulin-like antigens, which in some cases present the same electrophoretic mobility as bovine insulin, together with results recently published by us on the amino acid sequence of an insulin isolated from the seed coat of jack bean (Canavalia ensiformis) and from the developing fruits of cowpea (Vigna unguiculata), suggests that pathways depending on this hormone have been conserved through evolution. PMID:11887207

  13. Morphology of a novel cyanobacterium and characterization of light-harvesting complexes from it: Implications for phycobiliprotein evolution

    PubMed Central

    Kursar, Thomas A.; Swift, Hewson; Alberte, Randall S.

    1981-01-01

    The morphology of the marine cyanobacterium DC-2 and two light-harvesting complexes from it have been characterized. DC-2 has an outer cell wall sheath not previously observed, the purified phycoerythrin shows many unusual properties that distinguish it from all phycoerythrins characterized to date, and isolated phycobilisomes have a single absorption band at 640 nm in the phycocyanin-allophycocyanin region of the spectrum. On the basis of these observations we suggest that DC-2, rather than being a member of the Synechococcus group, should be placed in its own taxonomic group. In addition, the particular properties of the isolated phycoerythrin suggest that it may be representative of an early stage in the evolution of the phycoerythrins. These observations are of special interest in light of the contribution DC-2 and related cyanobacteria may make to global primary productivity. Images PMID:16593122

  14. Phosphorus addition reverses the positive effect of zebra mussels (Dreissena polymorpha) on the toxic cyanobacterium, Microcystis aeruginosa.

    PubMed

    Sarnelle, Orlando; White, Jeffrey D; Horst, Geoffrey P; Hamilton, Stephen K

    2012-07-01

    We tested the hypothesis that zebra mussels (Dreissena polymorpha) have positive effects on the toxin-producing cyanobacterium, Microcystis aeruginosa, at low phosphorus (P) concentrations, but negative effects on M. aeruginosa at high P, with a large-scale enclosure experiment in an oligotrophic lake. After three weeks, mussels had a significantly positive effect on M. aeruginosa at ambient P (total phosphorus, TP ∼10 μg L⁻¹), and a significantly negative effect at high P (simulating a TP of ∼40 μg L⁻¹ in lakes). Positive and negative effects were strong and very similar in magnitude. Thus, we were able to ameliorate a negative effect of Dreissena invasion on water quality (i.e., promotion of Microcystis) by adding P to water from an oligotrophic lake. Our results are congruent with many field observations of Microcystis response to Dreissena invasion across ecosystems of varying P availability. PMID:22507249

  15. Trimeric forms of the photosystem I reaction center complex pre-exist in the membranes of the cyanobacterium Spirulina platensis.

    PubMed

    Shubin, V V; Tsuprun, V L; Bezsmertnaya, I N; Karapetyan, N V

    1993-11-01

    Oligomeric and monomeric forms of chlorophyll-protein complexes of photosystem I (PSI) have been isolated from the mesophilic cyanobacterium Spirulina [(1992) FEBS Lett. 309, 340-342]. Electron microscopic analysis of the complexes showed that the oligomeric form is a trimer of the shape and dimensions similar to those of the trimer from thermophilic cyanobacteria. The chlorophyl ratio in the isolated trimer and monomer was found to be 7:3. The trimeric form of PSI complex in contrast to the monomeric one contains the chlorophyll emitting at 760 nm (77K), which is also found in Spirulina membranes and therefore could be used as an intrinsic probe for the trimeric complex. The 77K circular dichroism spectrum of the trimeric form is much more similar to that of Spirulina membranes than the spectrum of the monomer. Thus, the trimeric PSI complexes exist and dominate in the Spirulina membranes. PMID:8224233

  16. Crystal structure at 1.5Å resolution of the PsbV2 cytochrome from the cyanobacterium Thermosynechococcus elongatus.

    PubMed

    Suga, Michihiro; Lai, Thanh-Lan; Sugiura, Miwa; Shen, Jian-Ren; Boussac, Alain

    2013-10-01

    PsbV2 is a c-type cytochrome present in a very low abundance in the thermophilic cyanobacterium Thermosynechococcus elongatus. We purified this cytochrome and solved its crystal structure at a resolution of 1.5Å. The protein existed as a dimer in the crystal, and has an overall structure similar to other c-type cytochromes like Cytc6 and Cytc550, for example. However, the 5th and 6th heme iron axial ligands were found to be His51 and Cys101, respectively, in contrast to the more common bis-His or His/Met ligands found in most cytochromes. Although a few other c-type cytochromes were suggested to have this axial coordination, this is the first crystal structure reported for a c-type heme with this unusual His/Cys axial coordination. Previous spectroscopic characterizations of PsbV2 are discussed in relation to its structural properties.

  17. A role for the diazotrophic cyanobacterium, Cyanothece sp. strain ATCC 51142, in nitrogen cycling for CELSS applications.

    PubMed

    Schneegurt, M A; Sherman, L A

    1996-01-01

    Simple calculations show that fixed nitrogen regeneration in a CELSS may not be as efficient as stowage and resupply of fixed nitrogen compounds. However, fixed nitrogen regeneration may be important for the sustainability and safety of a deployed CELSS. Cyanothece sp. strain ATCC 51142, a unicellular, aerobic, diazotrophic cyanobacterium, with high growth rates and a robust metabolism, is a reasonable candidate organism for a biological, fixed nitrogen regeneration system. In addition, Cyanothece sp. cultures may be used to balance gas exchange ratio imparities between plants and humans. The regeneration of fixed nitrogen compounds by cyanobacterial cultures was examined in the context of a broad computer model/simulation (called CELSS-3D). When cyanothece sp. cultures were used to balance gas exchange imparities, the biomass harvested could supply as much as half of the total fixed nitrogen needed for plant biomass production.

  18. Use of a transposon with luciferase as a reporter to identify environmentally responsive genes in a cyanobacterium

    SciTech Connect

    Wolk, C.P.; Yuping Cai; Panoff, J.M. )

    1991-06-15

    Anabaena, a filamentous cyanobacterium, is of developmental interest because, when deprived of fixed nitrogen, it shows patterned differentiation of N{sub 2}-fixing cells called heterocysts. To help elucidate its early responses to a decrease in nitrogen, the authors used a derivative of transposon Tn5 to generate transcriptional fusions of promoterless bacterial luciferase genes, luxAB, to the Anabaena genome. Genes that responded to removal of fixed nitrogen or to other environmental shifts by increased or decreased transcription were identified by monitoring the luminescence of colonies from transposon-generated libraries. The Tn5 derivative transposed in Anabaena at ca. 1-4 {times} 10{sup {minus}5} per cell and permitted high-resolution mapping of its position and orientation in the genome and facile cloning of contiguous genomic DNA.

  19. Requirement of Fra proteins for communication channels between cells in the filamentous nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120.

    PubMed

    Omairi-Nasser, Amin; Mariscal, Vicente; Austin, Jotham R; Haselkorn, Robert

    2015-08-11

    The filamentous nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120 differentiates specialized cells, heterocysts, that fix atmospheric nitrogen and transfer the fixed nitrogen to adjacent vegetative cells. Reciprocally, vegetative cells transfer fixed carbon to heterocysts. Several routes have been described for metabolite exchange within the filament, one of which involves communicating channels that penetrate the septum between adjacent cells. Several fra gene mutants were isolated 25 y ago on the basis of their phenotypes: inability to fix nitrogen and fragmentation of filaments upon transfer from N+ to N- media. Cryopreservation combined with electron tomography were used to investigate the role of three fra gene products in channel formation. FraC and FraG are clearly involved in channel formation, whereas FraD has a minor part. Additionally, FraG was located close to the cytoplasmic membrane and in the heterocyst neck, using immunogold labeling with antibody raised to the N-terminal domain of the FraG protein.

  20. Characterization of the IS895 family of insertion sequences from the cyanobacterium Anabaena sp. strain PCC 7120

    SciTech Connect

    Alam, J.; Vrba, J.M.; Martin, J.A.; Weislo, L.J.; Curtis, S.E. ); Yuping Cai )

    1991-09-01

    A family of repetitive elements from the cyanobacterium Anabaena sp. strain PCC 7120 was identified through the proximity of one element to the psbAI gene. Four members of this seven-member family were isolated and shown to have structures characteristic of bacterial insertion sequences. Each element is approximately 1,200 bp in length, is delimited by a 30-bp inverted repeat, and contains two open reading frames in tandem on the same DNA strand. The four copies differ from each other by small insertions or deletions, some of which alter the open reading frames. By using a system designed to trap insertion elements, one of the elements, denoted IS895, was shown to be mobile. The target site was not duplicated upon insertion of the element. Two other filamentous cyanobacterial strains were also found to contain sequences homologous to IS895.

  1. Direct measurement of excitation transfer dynamics between two trimers in C-phycocyanin hexamer from cyanobacterium Anabaena variabilis

    NASA Astrophysics Data System (ADS)

    Zhang, Jingmin; Zhao, Fuli; Zheng, Xiguang; Wang, Hezhou

    1999-05-01

    We provide the first experimental evidence for the excitation transfers between two trimers of an isolated C-phycocyanin hexamer (αβ) 6PCL RC27, at the end of the rod proximal to the core of PBS in cyanobacterium of Anabaena variabilis, with picosecond time-resolved fluorescence spectroscopy. Our results strongly suggest that the observed fluorescence decay constants around 20 and 10 ps time scales, shown in anisotropy decay, not in isotropic decay experiments arose from the excitation transfers between two trimers via two types of transfer pathways such as 1β 155↔6β 155 (2β 155↔5β 155 and 3β 155↔4β 155) and 2α 84↔5α 84 (3α 84↔6α 84 and 1α 84↔4α 84) channels and these could be described by Föster dipole-dipole resonance mechanism.

  2. High Titer Heterologous Production of Lyngbyatoxin in E. coli, a Protein Kinase C Activator from an Uncultured Marine Cyanobacterium

    PubMed Central

    Ongley, Sarah E.; Bian, Xiaoying; Zhang, Youming; Chau, Rocky; Gerwick, William H.; Müller, Rolf; Neilan, Brett A.

    2013-01-01

    Many chemically-complex cyanobacterial polyketides and nonribosomal peptides are of great pharmaceutical interest, but the levels required for exploitation are difficult to achieve from native sources. Here we develop a framework for the expression of these multifunctional cyanobacterial assembly lines in Escherichia coli using the lyngbyatoxin biosynthetic pathway, derived from a marine microbial assemblage dominated by the cyanobacterium Moorea producens. Heterologous expression of this pathway afforded high titers of both lyngbyatoxin A (25.6 mg L-1) and its precursor indolactam-V (150 mg L-1). Production, isolation and identification of all expected chemical intermediates of lyngbyatoxin biosynthesis in E. coli also confirmed the previously proposed biosynthetic route setting a solid chemical foundation for future pathway engineering. The successful production of the nonribosomal peptide lyngbyatoxin A in E. coli also opens the possibility for future heterologous expression, characterization and exploitation of other cyanobacterial natural product pathways. PMID:23751865

  3. Draft genome of Myxosarcina sp. strain GI1, a baeocytous cyanobacterium associated with the marine sponge Terpios hoshinota

    PubMed Central

    2015-01-01

    To date, genome sequences (complete or in draft form) from only six baeocytous cyanobacteria in four genera have been reported: Xenococcus, Chroococcidiopsis, Pleurocapsa, and Stanieria. To expand our knowledge on the diversity of baeocytous cyanobacteria, this study sequenced the genome of GI1, which is a Myxosarcina-like baeocytous cyanobacterium. GI1 is of interest not only because of its phylogenetic niche, but also because it is a cyanobiont isolated from the marine cyanobacteriosponge Terpios hoshinota, which has been shown to cause the death of corals. The ~7 Mb draft GI1 genome contains 6,891 protein-coding genes and 62 RNA genes. A comparison of genomes among the sequenced baeocytous cyanobacterial strains revealed the existence or absence of numerous discrete genes involved in nitrogen metabolism. It will be interesting to determine whether these genes are important for cyanobacterial adaptations and interactions between cyanobionts and their marine sponge hosts. PMID:26203339

  4. 2,3 Butanediol production in an obligate photoautotrophic cyanobacterium in dark conditions via diverse sugar consumption.

    PubMed

    McEwen, Jordan T; Kanno, Masahiro; Atsumi, Shota

    2016-07-01

    Cyanobacteria are under investigation as a means to utilize light energy to directly recycle CO2 into chemical compounds currently derived from petroleum. Any large-scale photosynthetic production scheme must rely on natural sunlight for energy, thereby limiting production time to only lighted hours during the day. Here, an obligate photoautotrophic cyanobacterium was engineered for enhanced production of 2,3-butanediol (23BD) in continuous light, 12h:12h light-dark diurnal, and continuous dark conditions via supplementation with glucose or xylose. This study achieved 23BD production under diurnal conditions comparable to production under continuous light conditions. The maximum 23BD titer was 3.0gL(-1) in 10d. Also achieving chemical production under dark conditions, this work enhances the feasibility of using cyanobacteria as industrial chemical-producing microbes. PMID:26979472

  5. Functional analysis of the phosphoprotein PII (glnB gene product) in the cyanobacterium Synechococcus sp. strain PCC 7942.

    PubMed Central

    Forchhammer, K; Tandeau de Marsac, N

    1995-01-01

    The PII protein (glnB gene product) in the cyanobacterium Synechococcus sp. strain PCC 7942 signals the cellular N status by being phosphorylated or dephosphorylated at a seryl residue. Here we show that the PII-modifying system responds to the activity of ammonium assimilation via the glutamine synthase-glutamate synthase pathway and to the state of CO2 fixation. To identify possible functions of PII in this microorganism, a PII-deficient mutant was created and its general phenotype was characterized. The analysis shows that the PII protein interferes with the regulation of enzymes required for nitrogen assimilation, although ammonium repression is still detectable in the PII-deficient mutant. We suggest that the phosphorylation and dephosphorylation of PII are part of a complex signal transduction network involved in global nitrogen control in cyanobacteria. In this regulatory process, PII might be involved in mediating the tight coordination between carbon and nitrogen assimilation. PMID:7721695

  6. Structure of Trichamide, a Cyclic Peptide from the Bloom-Forming Cyanobacterium Trichodesmium erythraeum, Predicted from the Genome Sequence†

    PubMed Central

    Sudek, Sebastian; Haygood, Margo G.; Youssef, Diaa T. A.; Schmidt, Eric W.

    2006-01-01

    A gene cluster for the biosynthesis of a new small cyclic peptide, dubbed trichamide, was discovered in the genome of the global, bloom-forming marine cyanobacterium Trichodesmium erythraeum ISM101 because of striking similarities to the previously characterized patellamide biosynthesis cluster. The tri cluster consists of a precursor peptide gene containing the amino acid sequence for mature trichamide, a putative heterocyclization gene, an oxidase, two proteases, and hypothetical genes. Based upon detailed sequence analysis, a structure was predicted for trichamide and confirmed by Fourier transform mass spectrometry. Trichamide consists of 11 amino acids, including two cysteine-derived thiazole groups, and is cyclized by an N—C terminal amide bond. As the first natural product reported from T. erythraeum, trichamide shows the power of genome mining in the prediction and discovery of new natural products. PMID:16751554

  7. Mutations that affect structure and assembly of light-harvesting proteins in the cyanobacterium Synechocystis sp. strain 6701

    SciTech Connect

    Anderson, L.K.; Rayner, M.C.; Eiserling, F.A.

    1987-01-01

    The unicellular cyanobacterium Synechocystis sp. strain 6701 was mutagenized with UV irradiation and screened for pigment changes that indicated genetic lesions involving the light-harvesting proteins of the phycobilisome. A previous examination of the pigment mutant UV16 showed an assembly defect in the phycocyanin component of the phycobilisome. Mutagenesis of UV16 produced an additional double mutant, UV16-40, with decreased phycoerythrin content. Phycocyanin and phycoerythrin were isolated from UV16-40 and compared with normal biliproteins. The results suggested that the UV16 mutation affected the alpha subunit of phycocyanin, while the phycoerythrin beta subunit from UV16-40 had lost one of its three chromophores. Characterization of the unassembled phycobilisome components in these mutants suggests that these strains will be useful for probing in vivo the regulated expression and assembly of phycobilisomes.

  8. Influence of mixotrophic growth on rhythmic oscillations in expression of metabolic pathways in diazotrophic cyanobacterium Cyanothece sp. ATCC 51142.

    PubMed

    Krishnakumar, S; Gaudana, Sandeep B; Digmurti, Madhuri G; Viswanathan, Ganesh A; Chetty, Madhu; Wangikar, Pramod P

    2015-01-01

    This study investigates the influence of mixotrophy on physiology and metabolism by analysis of global gene expression in unicellular diazotrophic cyanobacterium Cyanothece sp. ATCC 51142 (henceforth Cyanothece 51142). It was found that Cyanothece 51142 continues to oscillate between photosynthesis and respiration in continuous light under mixotrophy with cycle time of ∼ 13 h. Mixotrophy is marked by an extended respiratory phase compared with photoautotrophy. It can be argued that glycerol provides supplementary energy for nitrogen fixation, which is derived primarily from the glycogen reserves during photoautotrophy. The genes of NDH complex, cytochrome c oxidase and ATP synthase are significantly overexpressed in mixotrophy during the day compared to autotrophy with synchronous expression of the bidirectional hydrogenase genes possibly to maintain redox balance. However, nitrogenase complex remains exclusive to nighttime metabolism concomitantly with uptake hydrogenase. This study throws light on interrelations between metabolic pathways with implications in design of hydrogen producer strains.

  9. Phosphorus addition reverses the positive effect of zebra mussels (Dreissena polymorpha) on the toxic cyanobacterium, Microcystis aeruginosa.

    PubMed

    Sarnelle, Orlando; White, Jeffrey D; Horst, Geoffrey P; Hamilton, Stephen K

    2012-07-01

    We tested the hypothesis that zebra mussels (Dreissena polymorpha) have positive effects on the toxin-producing cyanobacterium, Microcystis aeruginosa, at low phosphorus (P) concentrations, but negative effects on M. aeruginosa at high P, with a large-scale enclosure experiment in an oligotrophic lake. After three weeks, mussels had a significantly positive effect on M. aeruginosa at ambient P (total phosphorus, TP ∼10 μg L⁻¹), and a significantly negative effect at high P (simulating a TP of ∼40 μg L⁻¹ in lakes). Positive and negative effects were strong and very similar in magnitude. Thus, we were able to ameliorate a negative effect of Dreissena invasion on water quality (i.e., promotion of Microcystis) by adding P to water from an oligotrophic lake. Our results are congruent with many field observations of Microcystis response to Dreissena invasion across ecosystems of varying P availability.

  10. Fabivirga thermotolerans gen. nov., sp. nov., a novel marine bacterium isolated from culture broth of a marine cyanobacterium.

    PubMed

    Tang, M; Chen, C; Li, J; Xiang, W; Wu, H; Wu, J; Dai, S; Wu, H; Li, T; Wang, G

    2016-02-01

    A Gram-stain-negative, red, non-spore-forming, strictly aerobic bacterium, designated strain A4T, was isolated from culture broth of a marine cyanobacterium. Cells were flexible rods with gliding motility. Phylogenetic analysis, based on 16S rRNA gene sequences, revealed that strain A4T formed a coherent cluster with members of the genera Roseivirga and Fabibacter, and represents a distinct lineage in the family Flammeovirgaceae. Thermotolerance and a distinctive cellular fatty acid profile could readily distinguish this isolate from any bacteria of the genera Roseivirga and Fabibacter with a validly published name. On the basis of the phenotypic, chemotaxonomic and phylogenetic characteristics, strain A4T is suggested to represent a novel species in a novel genus, for which the name Fabivirga thermotolerans gen. nov., sp. nov. is proposed. The type strain is A4T ( = KCTC 42507T = CGMCC 1.15111T).

  11. Microenvironmental Ecology of the Chlorophyll b-Containing Symbiotic Cyanobacterium Prochloron in the Didemnid Ascidian Lissoclinum patella

    PubMed Central

    Kühl, Michael; Behrendt, Lars; Trampe, Erik; Qvortrup, Klaus; Schreiber, Ulrich; Borisov, Sergey M.; Klimant, Ingo; Larkum, Anthony W. D.

    2012-01-01

    The discovery of the cyanobacterium Prochloron was the first finding of a bacterial oxyphototroph with chlorophyll (Chl) b, in addition to Chl a. It was first described as Prochloron didemni but a number of clades have since been described. Prochloron is a conspicuously large (7–25 μm) unicellular cyanobacterium living in a symbiotic relationship, primarily with (sub-) tropical didemnid ascidians; it has resisted numerous cultivation attempts and appears truly obligatory symbiotic. Recently, a Prochloron draft genome was published, revealing no lack of metabolic genes that could explain the apparent inability to reproduce and sustain photosynthesis in a free-living stage. Possibly, the unsuccessful cultivation is partly due to a lack of knowledge about the microenvironmental conditions and ecophysiology of Prochloron in its natural habitat. We used microsensors, variable chlorophyll fluorescence imaging and imaging of O2 and pH to obtain a detailed insight to the microenvironmental ecology and photobiology of Prochloron in hospite in the didemnid ascidian Lissoclinum patella. The microenvironment within ascidians is characterized by steep gradients of light and chemical parameters that change rapidly with varying irradiances. The interior zone of the ascidians harboring Prochloron thus became anoxic and acidic within a few minutes of darkness, while the same zone exhibited O2 super-saturation and strongly alkaline pH after a few minutes of illumination. Photosynthesis showed lack of photoinhibition even at high irradiances equivalent to full sunlight, and photosynthesis recovered rapidly after periods of anoxia. We discuss these new insights on the ecological niche of Prochloron and possible interactions with its host and other microbes in light of its recently published genome and a recent study of the overall microbial diversity and metagenome of L. patella. PMID:23226144

  12. Photosystem Trap Energies and Spectrally-Dependent Energy-Storage Efficiencies in the Chl d-Utilizing Cyanobacterium, Acaryochloris Marina

    NASA Technical Reports Server (NTRS)

    Mielke, Steven P.; Kiang, Nancy Y.; Blankenship, Robert E.; Mauzerall, David

    2012-01-01

    Acaryochloris marina is the only species known to utilize chlorophyll (Chl) d as a principal photopigment. The peak absorption wavelength of Chl d is redshifted approx. 40 nm in vivo relative to Chl a, enabling this cyanobacterium to perform oxygenic phototrophy in niche environments enhanced in far-red light. We present measurements of the in vivo energy-storage (E-S) efficiency of photosynthesis in A. marina, obtained using pulsed photoacoustics (PA) over a 90-nm range of excitation wavelengths in the red and far-red. Together with modeling results, these measurements provide the first direct observation of the trap energies of PSI and PSII, and also the photosystem-specific contributions to the total E-S efficiency. We find the maximum observed efficiency in A. marina (40+/-1% at 735 nm) is higher than in the Chl a cyanobacterium Synechococcus leopoliensis (35+/-1% at 690 nm). The efficiency at peak absorption wavelength is also higher in A. marina (36+/-1% at 710 nm vs. 31+/-1% at 670 nm). In both species, the trap efficiencies are approx. 40% (PSI) and approx. 30% (PSII). The PSI trap in A. marina is found to lie at 740+/-5 nm, in agreement with the value inferred from spectroscopic methods. The best fit of the model to the PA data identifies the PSII trap at 723+/-3 nm, supporting the view that the primary electron-donor is Chl d, probably at the accessory (ChlD1) site. A decrease in efficiency beyond the trap wavelength, consistent with uphill energy transfer, is clearly observed and fit by the model. These results demonstrate that the E-S efficiency in A. marina is not thermodynamically limited, suggesting that oxygenic photosynthesis is viable in even redder light environments.

  13. Changes in gene expression, cell physiology and toxicity of the harmful cyanobacterium Microcystis aeruginosa at elevated CO2

    PubMed Central

    Sandrini, Giovanni; Cunsolo, Serena; Schuurmans, J. Merijn; Matthijs, Hans C. P.; Huisman, Jef

    2015-01-01

    Rising CO2 concentrations may have large effects on aquatic microorganisms. In this study, we investigated how elevated pCO2 affects the harmful freshwater cyanobacterium Microcystis aeruginosa. This species is capable of producing dense blooms and hepatotoxins called microcystins. Strain PCC 7806 was cultured in chemostats that were shifted from low to high pCO2 conditions. This resulted in a transition from a C-limited to a light-limited steady state, with a ~2.7-fold increase of the cyanobacterial biomass and ~2.5-fold more microcystin per cell. Cells increased their chlorophyll a and phycocyanin content, and raised their PSI/PSII ratio at high pCO2. Surprisingly, cells had a lower dry weight and contained less carbohydrates, which might be an adaptation to improve the buoyancy of Microcystis when light becomes more limiting at high pCO2. Only 234 of the 4691 genes responded to elevated pCO2. For instance, expression of the carboxysome, RuBisCO, photosystem and C metabolism genes did not change significantly, and only a few N assimilation genes were expressed differently. The lack of large-scale changes in the transcriptome could suit a buoyant species that lives in eutrophic lakes with strong CO2 fluctuations very well. However, we found major responses in inorganic carbon uptake. At low pCO2, cells were mainly dependent on bicarbonate uptake, whereas at high pCO2 gene expression of the bicarbonate uptake systems was down-regulated and cells shifted to CO2 and low-affinity bicarbonate uptake. These results show that the need for high-affinity bicarbonate uptake systems ceases at elevated CO2. Moreover, the combination of an increased cyanobacterial abundance, improved buoyancy, and higher toxin content per cell indicates that rising atmospheric CO2 levels may increase the problems associated with the harmful cyanobacterium Microcystis in eutrophic lakes. PMID:25999931

  14. Proteomic strategy for the analysis of the polychlorobiphenyl-degrading cyanobacterium Anabaena PD-1 exposed to Aroclor 1254.

    PubMed

    Zhang, Hangjun; Jiang, Xiaojun; Xiao, Wenfeng; Lu, Liping

    2014-01-01

    The cyanobacterium Anabaena PD-1, which was originally isolated from polychlorobiphenyl (PCB)-contaminated paddy soils, has capabilities for dechlorinatin and for degrading the commercial PCB mixture Aroclor 1254. In this study, 25 upregulated proteins were identified using 2D electrophoresis (2-DE) coupled with matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). These proteins were involved in (i) PCB degradation (i.e., 3-chlorobenzoate-3,4-dioxygenase); (ii) transport processes [e.g., ATP-binding cassette (ABC) transporter substrate-binding protein, amino acid ABC transporter substrate-binding protein, peptide ABC transporter substrate-binding protein, putrescine-binding protein, periplasmic solute-binding protein, branched-chain amino acid uptake periplasmic solute-binding protein, periplasmic phosphate-binding protein, phosphonate ABC transporter substrate-binding protein, and xylose ABC transporter substrate-binding protein]; (iii) energetic metabolism (e.g., methanol/ethanol family pyrroloquinoline quinone (PQQ)-dependent dehydrogenase, malate-CoA ligase subunit beta, enolase, ATP synthase β subunit, FOF1 ATP synthase subunit beta, ATP synthase α subunit, and IMP cyclohydrolase); (iv) electron transport (cytochrome b6f complex Fe-S protein); (v) general stress response (e.g., molecular chaperone DnaK, elongation factor G, and translation elongation factor thermostable); (vi) carbon metabolism (methanol dehydrogenase and malate-CoA ligase subunit beta); and (vii) nitrogen reductase (nitrous oxide reductase). The results of real-time polymerase chain reaction showed that the genes encoding for dioxygenase, ABC transporters, transmembrane proteins, electron transporter, and energetic metabolism proteins were significantly upregulated during PCB degradation. These genes upregulated by 1.26- to 8.98-fold. These findings reveal the resistance and adaptation of cyanobacterium to the presence of PCBs, shedding light on the

  15. Potential effects of UV radiation on photosynthetic structures of the bloom-forming cyanobacterium Cylindrospermopsis raciborskii CYRF-01

    PubMed Central

    Noyma, Natália P.; Silva, Thiago P.; Chiarini-Garcia, Hélio; Amado, André M.; Roland, Fábio; Melo, Rossana C. N.

    2015-01-01

    Cyanobacteria are aquatic photosynthetic microorganisms. While of enormous ecological importance, they have also been linked to human and animal illnesses around the world as a consequence of toxin production by some species. Cylindrospermopsis raciborskii, a filamentous nitrogen-fixing cyanobacterium, has attracted considerable attention due to its potential toxicity and ecophysiological adaptability. We investigated whether C. raciborskii could be affected by ultraviolet (UV) radiation. Non-axenic cultures of C. raciborskii were exposed to three UV treatments (UVA, UVB, or UVA + UVB) over a 6 h period, during which cell concentration, viability and ultrastructure were analyzed. UVA and UVA + UVB treatments showed significant negative effects on cell concentration (decreases of 56.4 and 64.3%, respectively). This decrease was directly associated with cell death as revealed by a cell viability fluorescent probe. Over 90% of UVA + UVB- and UVA-treated cells died. UVB did not alter cell concentration, but reduced cell viability in almost 50% of organisms. Transmission electron microscopy (TEM) revealed a drastic loss of thylakoids, membranes in which cyanobacteria photosystems are localized, after all treatments. Moreover, other photosynthetic- and metabolic-related structures, such as accessory pigments and polyphosphate granules, were damaged. Quantitative TEM analyses revealed a 95.8% reduction in cell area occupied by thylakoids after UVA treatment, and reduction of 77.6 and 81.3% after UVB and UVA + UVB treatments, respectively. Results demonstrated clear alterations in viability and photosynthetic structures of C. raciborskii induced by various UV radiation fractions. This study facilitates our understanding of the subcellular organization of this cyanobacterium species, identifies specific intracellular targets of UVA and UVB radiation and reinforces the importance of UV radiation as an environmental stressor. PMID:26579108

  16. High iron requirement for growth, photosynthesis, and low-light acclimation in the coastal cyanobacterium Synechococcus bacillaris

    PubMed Central

    Sunda, William G.; Huntsman, Susan A.

    2015-01-01

    Iron limits carbon fixation in much of the modern ocean due to the very low solubility of ferric iron in oxygenated ocean waters. We examined iron-limitation of growth rate under varying light intensities in the coastal cyanobacterium Synechococcus bacillaris, a descendent of the oxygenic phototrophs that evolved ca. 3 billion years ago when the ocean was reducing and iron was present at much higher concentrations as soluble Fe(II). Decreasing light intensity increased the cellular iron:carbon (Fe:C) ratio needed to support a given growth rate, indicating that iron and light may co-limit the growth of Synechococcus in the ocean, as shown previously for eukaryotic phytoplankton. The cellular Fe:C ratios needed to support a given growth rate were 5- to 8-fold higher than ratios for coastal eukaryotic algae growing under the same light conditions. The higher iron requirements for growth in the coastal cyanobacterium may be largely caused by the high demand for iron in photosynthesis, and to higher ratios of iron-rich photosystem I to iron-poor photosystem II in Synechococcus than in eukaryotic algae. This high iron requirement may also be vestigial and represent an adaptation to the much higher iron levels in the ancient reducing ocean. Due to the high cellular iron requirement for photosynthesis and growth, and for low light acclimation, Synechococcus may be excluded from many low-iron and low-light environments. Indeed, it decreases rapidly with depth within the ocean’s deep chlorophyll maximum (DCM) where iron and light levels are low, and lower-iron requiring picoeukaryotes typically dominate the biomass of phytoplankton community within the mid to lower DCM. PMID:26150804

  17. High iron requirement for growth, photosynthesis, and low-light acclimation in the coastal cyanobacterium Synechococcus bacillaris.

    PubMed

    Sunda, William G; Huntsman, Susan A

    2015-01-01

    Iron limits carbon fixation in much of the modern ocean due to the very low solubility of ferric iron in oxygenated ocean waters. We examined iron-limitation of growth rate under varying light intensities in the coastal cyanobacterium Synechococcus bacillaris, a descendent of the oxygenic phototrophs that evolved ca. 3 billion years ago when the ocean was reducing and iron was present at much higher concentrations as soluble Fe(II). Decreasing light intensity increased the cellular iron:carbon (Fe:C) ratio needed to support a given growth rate, indicating that iron and light may co-limit the growth of Synechococcus in the ocean, as shown previously for eukaryotic phytoplankton. The cellular Fe:C ratios needed to support a given growth rate were 5- to 8-fold higher than ratios for coastal eukaryotic algae growing under the same light conditions. The higher iron requirements for growth in the coastal cyanobacterium may be largely caused by the high demand for iron in photosynthesis, and to higher ratios of iron-rich photosystem I to iron-poor photosystem II in Synechococcus than in eukaryotic algae. This high iron requirement may also be vestigial and represent an adaptation to the much higher iron levels in the ancient reducing ocean. Due to the high cellular iron requirement for photosynthesis and growth, and for low light acclimation, Synechococcus may be excluded from many low-iron and low-light environments. Indeed, it decreases rapidly with depth within the ocean's deep chlorophyll maximum (DCM) where iron and light levels are low, and lower-iron requiring picoeukaryotes typically dominate the biomass of phytoplankton community within the mid to lower DCM.

  18. Regulation by cyanate of the genes involved in carbon and nitrogen assimilation in the cyanobacterium Synechococcus sp. strain PCC 7942.

    PubMed Central

    Suzuki, I; Sugiyami, T; Omata, T

    1996-01-01

    A mutant (M45) of the cyanobacterium Synechococcus sp. strain PCC 7942, which is defective in active transport of nitrate, was used for the studies of the nitrogen regulation of the genes involved in nitrate and CO2 assimilation. In a medium containing 30 mM nitrate as the nitrogen source, M45 grew under constant stress of nitrogen deficiency and accumulated a five-times-larger amount of the transcript of nirA, the gene for nitrite reductase, compared with nitrate-grown wild-type cells. By contrast, the level of the transcript of rbcL, the gene for the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase, was 40% of the wild-type level. Addition of ammonium to the culture of M45 abolished the accumulation of the nirA transcript and stimulated the accumulation of the rbcL transcript, showing that ammonium repressed and activated the transcription of nirA and rbcL, respectively. Glutamine, the initial product of ammonium fixation, also showed negative and positive effects on nirA and rbcL, respectively. One of the metabolites of glutamine, carbamoylphosphate, and its decomposition product, cyanate, were found to repress nirA and also to markedly activate rbcL. Cyanate negatively regulated another ammonium-repressible gene, glnA, but had no effect on the psbAI and rps1 genes. The effects of cyanate were not ascribable to the ammonium and CO, resulting from its decomposition. These findings suggested that cyanate may act as a regulator of the ammonium-responsive genes involved in carbon and nitrogen assimilation in the cyanobacterium. PMID:8626339

  19. Different phycobilin antenna organisations affect the balance between light use and growth rate in the cyanobacterium Microcystis aeruginosa and in the cryptophyte Cryptomonas ovata.

    PubMed

    Kunath, Christfried; Jakob, Torsten; Wilhelm, Christian

    2012-03-01

    During the recent years, wide varieties of methodologies have been developed up to the level of commercial use to measure photosynthetic electron transport by modulated chlorophyll a-in vivo fluorescence. It is now widely accepted that the ratio between electron transport rates and new biomass (P (Fl)/B (C)) is not fixed and depends on many factors that are also taxonomically variable. In this study, the balance between photon absorption and biomass production has been measured in two phycobilin-containing phototrophs, namely, a cyanobacterium and a cryptophyte, which differ in their antenna organization. It is demonstrated that the different antenna organization exerts influence on the regulation of the primary photosynthetic reaction and the dissipation of excessively absorbed radiation. Although, growth rates and the quantum efficiency of biomass production of both phototrophs were comparable, the ratio P (Fl)/B (C) was twice as high in the cryptophyte in comparison to the cyanobacterium. It is assumed that this discrepancy is because of differences in the metabolic regulation of cell growth. In the cryptophyte, absorbed photosynthetic energy is used to convert assimilated carbon directly into proteins and lipids, whereas in the cyanobacterium, the photosynthetic energy is preferentially stored as carbohydrates.

  20. The freshwater cyanobacterium Anabaena doliolum transformed with ApGSMT-DMT exhibited enhanced salt tolerance and protection to nitrogenase activity, but became halophilic.

    PubMed

    Singh, Meenakshi; Sharma, Naveen K; Prasad, Shyam Babu; Yadav, Suresh Singh; Narayan, Gopeshwar; Rai, Ashwani K

    2013-03-01

    Glycine betaine (GB) is an important osmolyte synthesized in response to different abiotic stresses, including salinity. The two known pathways of GB synthesis involve: 1) two step oxidation of choline (choline → betaine aldehyde → GB), generally found in plants, microbes and animals; and 2) three step methylation of glycine (glycine → sarcosine → dimethylglycine → GB), mainly found in halophilic archaea, sulphur bacteria and the cyanobacterium Aphanothece (Ap.) halophytica. Here, we transformed a salt-sensitive freshwater diazotrophic filamentous cyanobacterium Anabaena (An.) doliolum with N-methyltransferase genes (ApGSMT-DMT) from Ap. halophytica using the triparental conjugation method. The transformed An. doliolum synthesized and accumulated GB in cells, and showed increased salt tolerance and protection to nitrogenase activity. The salt responsiveness of the transformant was also apparent as GB synthesis increased with increasing concentrations of NaCl in the nutrient solution, and maximal [12.92 µmol (g dry weight)(-1)] in cells growing at 0.5 M NaCl. Therefore, the transformed cyanobacterium has changed its behaviour from preferring freshwater to halophily. This study may have important biotechnological implications for the development of stress tolerant nitrogen-fixing cyanobacteria as biofertilizers for sustainable agriculture.

  1. Simultaneous production of homoanatoxin-a, anatoxin-a, and a new non-toxic 4-hydroxyhomoanatoxin-a by the cyanobacterium Raphidiopsis mediterranea Skuja.

    PubMed

    Namikoshi, Michio; Murakami, Tomokazu; Watanabe, Mariyo F; Oda, Taiko; Yamada, Junko; Tsujimura, Shigeo; Nagai, Hiroshi; Oishi, Shinshi

    2003-10-01

    A neurotoxin, homoanatoxin-a, was identified from a toxic strain of the cyanobacterium Raphidiopsis mediterranea Skuja (strain LBRI 48) isolated from Lake Biwa, Japan, as the major toxin component (0.57% of dry cell-weight). This cyanobacterium produced anatoxin-a and a new homoanatoxin-a derivative as minor components (0.04 and 0.06%, respectively). The structure of a new compound was assigned based on the spectral data as 4-hydroxyhomoanatoxin-a, which was not toxic to mice up to 2.0 mg/kg by intraperitoneal injection. The isolation of minor components was accomplished by improved extraction and separation procedures: (1) extraction with methanol-water (4:1) from dried cells, (2) adsorption of aqueous residue on ODS column (or cartridge) after evaporation of methanol, (3) cleaning up of the column by successive elution with water and 50% methanol/water, (4) elution of a toxic fraction by 20% methanol/water containing 0.1% TFA and (5) HPLC (ODS) purification with methanol/water containing 0.05% TFA. The procedures were effective in removing impurities and concentrating alkaloidal neurotoxins. It should be noted that this is the first report demonstrating the simultaneous production of anatoxin-a and homoanatoxin-a by the same strain of cyanobacterium.

  2. Theophylline-dependent riboswitch as a novel genetic tool for strict regulation of protein expression in Cyanobacterium Synechococcus elongatus PCC 7942.

    PubMed

    Nakahira, Yoichi; Ogawa, Atsushi; Asano, Hiroyuki; Oyama, Tokitaka; Tozawa, Yuzuru

    2013-10-01

    The cyanobacterium Synechococcus elongatus PCC 7942 is a major model species for studies of photosynthesis. It is are also a potential cell factory for the production of renewable biofuels and valuable chemicals. We employed engineered riboswitches to control translational initiation of target genes in this cyanobacterium. A firefly luciferase reporter assay revealed that three theophylline riboswitches performed as expected in the cyanobacterium. Riboswitch-E* exhibited very low leaky expression of luciferase and superior and dose-dependent on/off regulation of protein expression by theophylline. The maximum magnitude of the induction vs. basal level was ∼190-fold. Furthermore, the induction level was responsive to a wide range of theophylline concentrations in the medium, from 0 to 2 mM, facilitating the fine-tuning of luciferase expression. We adapted this riboswitch to another gene regulation system, in which expression of the circadian clock kaiC gene product is controlled by the theophylline concentration in the culture medium. The results demonstrated that the adequately adjusted expression level of KaiC restored complete circadian rhythm in the kaiC-deficient arrhythmic mutant. This theophylline-dependent riboswitch system has potential for various applications as a useful genetic tool in cyanobacteria. PMID:23969558

  3. Theophylline-dependent riboswitch as a novel genetic tool for strict regulation of protein expression in Cyanobacterium Synechococcus elongatus PCC 7942.

    PubMed

    Nakahira, Yoichi; Ogawa, Atsushi; Asano, Hiroyuki; Oyama, Tokitaka; Tozawa, Yuzuru

    2013-10-01

    The cyanobacterium Synechococcus elongatus PCC 7942 is a major model species for studies of photosynthesis. It is are also a potential cell factory for the production of renewable biofuels and valuable chemicals. We employed engineered riboswitches to control translational initiation of target genes in this cyanobacterium. A firefly luciferase reporter assay revealed that three theophylline riboswitches performed as expected in the cyanobacterium. Riboswitch-E* exhibited very low leaky expression of luciferase and superior and dose-dependent on/off regulation of protein expression by theophylline. The maximum magnitude of the induction vs. basal level was ∼190-fold. Furthermore, the induction level was responsive to a wide range of theophylline concentrations in the medium, from 0 to 2 mM, facilitating the fine-tuning of luciferase expression. We adapted this riboswitch to another gene regulation system, in which expression of the circadian clock kaiC gene product is controlled by the theophylline concentration in the culture medium. The results demonstrated that the adequately adjusted expression level of KaiC restored complete circadian rhythm in the kaiC-deficient arrhythmic mutant. This theophylline-dependent riboswitch system has potential for various applications as a useful genetic tool in cyanobacteria.

  4. Discovery of Rare and Highly Toxic Microcystins from Lichen-Associated Cyanobacterium Nostoc sp. Strain IO-102-I

    PubMed Central

    Oksanen, Ilona; Jokela, Jouni; Fewer, David P.; Wahlsten, Matti; Rikkinen, Jouko; Sivonen, Kaarina

    2004-01-01

    The production of hepatotoxic cyclic heptapeptides, microcystins, is almost exclusively reported from planktonic cyanobacteria. Here we show that a terrestrial cyanobacterium Nostoc sp. strain IO-102-I isolated from a lichen association produces six different microcystins. Microcystins were identified with liquid chromatography-UV mass spectrometry by their retention times, UV spectra, mass fragmentation, and comparison to microcystins from the aquatic Nostoc sp. strain 152. The dominant microcystin produced by Nostoc sp. strain IO-102-I was the highly toxic [ADMAdda5]microcystin-LR, which accounted for ca. 80% of the total microcystins. We assigned a structure of [DMAdda5]microcystin-LR and [d-Asp3,ADMAdda5]microcystin-LR and a partial structure of three new [ADMAdda5]-XR type of microcystin variants. Interestingly, Nostoc spp. strains IO-102-I and 152 synthesized only the rare ADMAdda and DMAdda subfamilies of microcystin variants. Phylogenetic analyses demonstrated congruence between genes involved directly in microcystin biosynthesis and the 16S rRNA and rpoC1 genes of Nostoc sp. strain IO-102-I. Nostoc sp. strain 152 and the Nostoc sp. strain IO-102-I are distantly related, revealing a sporadic distribution of toxin production in the genus Nostoc. Nostoc sp. strain IO-102-I is closely related to Nostoc punctiforme PCC 73102 and other symbiotic Nostoc strains and most likely belongs to this species. Together, this suggests that other terrestrial and aquatic strains of the genus Nostoc may have retained the genes necessary for microcystin biosynthesis. PMID:15466511

  5. Seawater cultivation of freshwater cyanobacterium Synechocystis sp. PCC 6803 drastically alters amino acid composition and glycogen metabolism

    PubMed Central

    Iijima, Hiroko; Nakaya, Yuka; Kuwahara, Ayuko; Hirai, Masami Yokota; Osanai, Takashi

    2015-01-01

    Water use assessment is important for bioproduction using cyanobacteria. For eco-friendly reasons, seawater should preferably be used for cyanobacteria cultivation instead of freshwater. In this study, we demonstrated that the freshwater unicellular cyanobacterium Synechocystis sp. PCC 6803 could be grown in a medium based on seawater. The Synechocystis wild-type strain grew well in an artificial seawater (ASW) medium supplemented with nitrogen and phosphorus sources. The addition of HEPES buffer improved cell growth overall, although the growth in ASW medium was inferior to that in the synthetic BG-11 medium. The levels of proteins involved in sugar metabolism changed depending on the culture conditions. The biosynthesis of several amino acids including aspartate, glutamine, glycine, proline, ornithine, and lysine, was highly up-regulated by cultivation in ASW. Two types of natural seawater (NSW) were also made available for the cultivation of Synechocystis cells, with supplementation of both nitrogen and phosphorus sources. These results revealed the potential use of seawater for the cultivation of freshwater cyanobacteria, which would help to reduce freshwater consumption during biorefinery using cyanobacteria. PMID:25954257

  6. Anti-inflammatory Effects of Novel Polysaccharide Sacran Extracted from Cyanobacterium Aphanothece sacrum in Various Inflammatory Animal Models.

    PubMed

    Motoyama, Keiichi; Tanida, Yuki; Hata, Kyona; Hayashi, Tomoya; Hashim, Irhan Ibrahim Abu; Higashi, Taishi; Ishitsuka, Yoichi; Kondo, Yuki; Irie, Tetsumi; Kaneko, Shinichiro; Arima, Hidetoshi

    2016-07-01

    The goal of this study was to investigate the topical anti-inflammatory effects of the megamolecular polysaccharide sacran extracted from cyanobacterium Aphanothece sacrum using various inflammatory animal models. Sacran showed potent anti-inflammatory effects with optimum effective concentrations at 0.01 and 0.05% (w/v). Sacran markedly inhibited paw swelling and neutrophil infiltration in carrageenan-induced rat paw edema. Additionally, 6,7-dimethoxy-1-methyl-2(1H)-quinoxalinone-3-propionyl-carboxylic acid (DMEQ)-labeled sacran had the ability to penetrate carrageenan-induced rat paw skin rather than normal skin. Also, sacran significantly suppressed kaolin-induced and dextran-induced rat paw edema throughout the duration of the study. Furthermore, sacran significantly suppressed 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced mouse ear edema and mRNA expression levels of cyclooxygenase (COX)-2 as well as pro-inflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6. Safety of sacran solution was verified by negligible cytotoxicity in HaCaT cells. These results suggest that sacran may be useful as a therapeutic agent against inflammatory skin diseases with no life-threatening adverse effects. PMID:27170516

  7. Viequeamide A, a cytotoxic member of the kulolide superfamily of cyclic depsipeptides from a marine button cyanobacterium.

    PubMed

    Boudreau, Paul D; Byrum, Tara; Liu, Wei-Ting; Dorrestein, Pieter C; Gerwick, William H

    2012-09-28

    The viequeamides, a family of 2,2-dimethyl-3-hydroxy-7-octynoic acid (Dhoya)-containing cyclic depsipeptides, were isolated from a shallow subtidal collection of a "button" cyanobacterium (Rivularia sp.) from near the island of Vieques, Puerto Rico. Planar structures of the two major compounds, viequeamide A (1) and viequeamide B (2), were elucidated by 2D-NMR spectroscopy and mass spectrometry, whereas absolute configurations were determined by traditional hydrolysis, derivative formation, and chromatography in comparison with standards. In addition, a series of related minor metabolites, viequeamides C-F (3-6), were characterized by HRMS fragmentation methods. Viequeamide A was found to be highly toxic to H460 human lung cancer cells (IC(50) = 60 ± 10 nM), whereas the mixture of B-F was inactive. From a broader perspective, the viequeamides help to define a "superfamily" of related cyanobacterial natural products, the first of which to be discovered was kulolide. Within the kulolide superfamily, a wide variation in biological properties is observed, and the reported producing strains are also highly divergent, giving rise to several intriguing questions about structure-activity relationships and the evolutionary origins of this metabolite class.

  8. Acute Exposure to Microcystin-Producing Cyanobacterium Microcystis aeruginosa Alters Adult Zebrafish (Danio rerio) Swimming Performance Parameters

    PubMed Central

    Kist, Luiza Wilges; Piato, Angelo Luis; da Rosa, João Gabriel Santos; Koakoski, Gessi; Barcellos, Leonardo José Gil; Yunes, João Sarkis; Bonan, Carla Denise; Bogo, Maurício Reis

    2011-01-01

    Microcystins (MCs) are toxins produced by cyanobacteria (blue-green algae), primarily Microcystis aeruginosa, forming water blooms worldwide. When an organism is exposed to environmental perturbations, alterations in normal behavioral patterns occur. Behavioral repertoire represents the consequence of a diversity of physiological and biochemical alterations. In this study, we assessed behavioral patterns and whole-body cortisol levels of adult zebrafish (Danio rerio) exposed to cell culture of the microcystin-producing cyanobacterium M. aeruginosa (MC-LR, strain RST9501). MC-LR exposure (100 μg/L) decreased by 63% the distance traveled and increased threefold the immobility time when compared to the control group. Interestingly, no significant alterations in the number of line crossings were found at the same MC-LR concentration and time of exposure. When animals were exposed to 50 and 100 μg/L, MC-LR promoted a significant increase (around 93%) in the time spent in the bottom portion of the tank, suggesting an anxiogenic effect. The results also showed that none of the MC-LR concentrations tested promoted significant alterations in absolute turn angle, path efficiency, social behavior, or whole-body cortisol level. These findings indicate that behavior is susceptible to MC-LR exposure and provide evidence for a better understanding of the ecological consequences of toxic algal blooms. PMID:22253623

  9. Consortium of the 'bichlorophyllous' cyanobacterium Prochlorothrix hollandica and chemoheterotrophic partner bacteria: culture and metagenome-based description.

    PubMed

    Velichko, Natalia; Chernyaeva, Ekaterina; Averina, Svetlana; Gavrilova, Olga; Lapidus, Alla; Pinevich, Alexander

    2015-08-01

    'Bacterial consortium' sensu lato applies to mutualism or syntrophy-based systems consisting of unrelated bacteria. Consortia of cyanobacteria have been preferentially studied on Anabaena epibioses; non-photosynthetic satellites of other filamentous or unicellular cyanobacteria were also considered although structure-functional data are few. At the same time, information about consortia of cyanobacteria which have light-harvesting antennae distinct from standard phycobilisome was missing. In this study, we characterized first, via a polyphasic approach, the cultivable consortium of Prochlorothrix hollandica CCAP 1490/1 (filamentous cyanobacterium which contains chlorophylls a, b/carotenoid/protein complex in the absence of phycobilisome) and non-photosynthetic heterotrophic bacteria. The strains of most abundant satellites were isolated and identified. Consortium metagenome reconstructed via 454-pyro and Illumina sequencing was shown to include, except for P. hollandica, several phylotypes of Proteobacteria and Bacteroidetes. The ratio of consortium members was essentially stable irrespective of culture age, and restored after artificially imposed imbalance. The consortium had a complex spatial arrangement as demonstrated by FISH and SEM images of the association, epibiosis, and biofilm type. Preliminary data of metagenome annotation agreed with the hypothesis that satellite bacteria contribute to P. hollandica protection from reactive oxygen species (ROS). PMID:25990300

  10. The non-metabolizable sucrose analog sucralose is a potent inhibitor of hormogonium differentiation in the filamentous cyanobacterium Nostoc punctiforme.

    PubMed

    Splitt, Samantha D; Risser, Douglas D

    2016-03-01

    Nostoc punctiforme is a filamentous cyanobacterium which forms nitrogen-fixing symbioses with several different plants and fungi. Establishment of these symbioses requires the formation of motile hormogonium filaments. Once infected, the plant partner is thought to supply a hormogonium-repressing factor (HRF) to maintain the cyanobacteria in a vegetative, nitrogen-fixing state. Evidence implies that sucrose may serve as a HRF. Here, we tested the effects of sucralose, a non-metabolizable sucrose analog, on hormogonium differentiation. Sucralose inhibited hormogonium differentiation at a concentration approximately one-tenth that of sucrose. This result implies that: (1) sucrose, not a sucrose catabolite, is perceived by the cell and (2) inhibition is not due to a more general osmolarity-dependent effect. Additionally, both sucrose and sucralose induced the accrual of a polysaccharide sheath which bound specifically to the lectin ConA, indicating the presence of α-D-mannose and/or α-D-glucose. A ConA-specific polysaccharide was also found to be expressed in N. punctiforme colonies from tissue sections of the symbiotically grown hornwort Anthoceros punctatus. These findings imply that plant-derived sucrose or sucrose analogs may have multiple effects on N. punctiforme, including both repression of hormogonia and the induction of a polysaccharide sheath that may be essential to establish and maintain the symbiotic state.

  11. The effect of temperature on growth and production of paralytic shellfish poisoning toxins by the cyanobacterium Cylindrospermopsis raciborskii C10.

    PubMed

    Castro, Daniela; Vera, Diana; Lagos, Néstor; García, Carlos; Vásquez, Mónica

    2004-10-01

    Cylindrospermopsis raciborskii is a cyanobacterium which produces either cylindrospermopsine or paralytic shellfish poisoning (PSP) toxins. We studied the effect of temperature on growth and production of PSP toxins by C. raciborskii C10, isolated from a freshwater reservoir in Brazil. We analyzed the extracellular and intracellular content of PSP toxins at two different temperatures: 19 and 25 degrees C. C. raciborskii C10 produces STX, GTX2, and GTX3 at both temperatures. dcSTX was also detected at 25 degrees C in the intracellular extracts obtained at the end of the stationary phase. The growth achieved at 25 degrees C and estimated by optical density at 700 nm was three times greater than at 19 degrees C. However, no significant differences were observed in the content of PSP toxins in either the cells or the extracellular media. The kinetics of accumulation of PSP toxins within the cells rather than in the media suggests an active PSP toxins-export process that is not related to cell lysis. The extracellular accumulation of PSP toxins at 19 degrees C suggested a biotransformation of STX to the epimers GTX2 and GTX3. The stability of the PSP toxins produced by C. raciborskii C10 was high enough for them to remain active in the media after 30 days (at 25 degrees C) or after 50 days (at 19 degrees C). PMID:15450922

  12. Functional characterization of a member of alanine or glycine: cation symporter family in halotolerant cyanobacterium Aphanothece halophytica.

    PubMed

    Bualuang, Aporn; Kageyama, Hakuto; Tanaka, Yoshito; Incharoensakdi, Aran; Takabe, Teruhiro

    2015-01-01

    Membrane proteins of amino acid-polyamine-organocation (APC) superfamily transport amino acids and amines across membranes and play important roles in the regulation of cellular processes. The alanine or glycine: cation symporter (AGCS) family belongs to APC superfamily and is found in prokaryotes, but its substrate specificity remains to be clarified. In this study, we found that a halotolerant cyanobacterium, Aphanothece halophytica has two putative ApagcS genes. The deduced amino acid sequence of one of genes, ApagcS1, exhibited high homology to Pseudomonas AgcS. The ApagcS1 gene was expressed in Escherichia coli JW4166 which is deficient in glycine uptake. Kinetics studies in JW4166 revealed that ApAgcS1 is a sodium-dependent glycine transporter. Competition experiments showed the significant inhibition by glutamine, asparagine, and glycine. The level of mRNA for ApagcS1 was induced by NaCl and nitrogen-deficient stresses. Uptake of glutamine by ApAgcS1 was also observed. Based on these data, the physiological role of ApAgcS1 was discussed.

  13. RNA-seq Profiling Reveals Novel Target Genes of LexA in the Cyanobacterium Synechocystis sp. PCC 6803

    PubMed Central

    Kizawa, Ayumi; Kawahara, Akihito; Takimura, Yasushi; Nishiyama, Yoshitaka; Hihara, Yukako

    2016-01-01

    LexA is a well-established transcriptional repressor of SOS genes induced by DNA damage in Escherichia coli and other bacterial species. However, LexA in the cyanobacterium Synechocystis sp. PCC 6803 has been suggested not to be involved in SOS response. In this study, we performed RNA-seq analysis of the wild-type strain and the lexA-disrupted mutant to obtain the comprehensive view of LexA-regulated genes in Synechocystis. Disruption of lexA positively or negatively affected expression of genes related to various cellular functions such as phototactic motility, accumulation of the major compatible solute glucosylglycerol and subunits of bidirectional hydrogenase, photosystem I, and phycobilisome complexes. We also observed increase in the expression level of genes related to iron and manganese uptake in the mutant at the later stage of cultivation. However, none of the genes related to DNA metabolism were affected by disruption of lexA. DNA gel mobility shift assay using the recombinant LexA protein suggested that LexA binds to the upstream region of pilA7, pilA9, ggpS, and slr1670 to directly regulate their expression, but changes in the expression level of photosystem I genes by disruption of lexA is likely a secondary effect. PMID:26925056

  14. Oscillating behavior of carbohydrate granule formation and dinitrogen fixation in the cyanobacterium Cyanothece sp. strain ATCC 51142.

    PubMed Central

    Schneegurt, M A; Sherman, D M; Nayar, S; Sherman, L A

    1994-01-01

    It has been shown that some aerobic, unicellular, diazotrophic cyanobacteria temporally separate photosynthetic O2 evolution and oxygen-sensitive N2 fixation. Cyanothece sp. ATCC strain 51142 is an aerobic, unicellular, diazotrophic cyanobacterium that fixes N2 during discrete periods of its cell cycle. When the bacteria are maintained under diurnal light-dark cycles, N2 fixation occurs in the dark. Similar cycling is observed in continuous light, implicating a circadian rhythm. Under N2-fixing conditions, large inclusion granules form between the thylakoid membranes. Maximum granulation, as observed by electron microscopy, occurs before the onset of N2 fixation, and the granules decrease in number during the period of N2 fixation. The granules can be purified from cell homogenates by differential centrifugation. Biochemical analyses of the granules indicate that these structures are primarily carbohydrate, with some protein. Further analyses of the carbohydrate have shown that it is a glucose polymer with some characteristics of glycogen. It is proposed that N2 fixation is driven by energy and reducing power stored in these inclusion granules. Cyanothece sp. strain ATCC 51142 represents an excellent experimental organism for the study of the protective mechanisms of nitrogenase, metabolic events in cyanobacteria under normal and stress conditions, the partitioning of resources between growth and storage, and biological rhythms. Images PMID:8132452

  15. Cytotoxic Halogenated Macrolides and Modified Peptides from the Apratoxin-Producing Marine Cyanobacterium Lyngbya bouillonii from Guam

    PubMed Central

    Matthew, Susan; Salvador, Lilibeth A.; Schupp, Peter J.; Paul, Valerie J.; Luesch, Hendrik

    2010-01-01

    Collections of the marine cyanobacterium Lyngbya bouillonii from shallow patch reefs in Apra Harbor, Guam, afforded three hitherto undescribed analogues of the glycosidic macrolide lyngbyaloside, namely 2-epi-lyngbyaloside (1) and the regioisomeric 18E- and 18Z–lyngbyalosides C (2 and 3). Concurrently we discovered two new analogues of the cytoskeletal actin-disrupting lyngbyabellins, 27-deoxylyngbyabellin A (4) and lyngbyabellin J (5), a novel macrolide of the laingolide family, laingolide B (6), and a linear modified peptide, lyngbyapeptin D (7), along with known lyngbyabellins A and B, lyngbyapeptin A, and lyngbyaloside. The structures of 1–7 were elucidated by a combination of NMR spectroscopic and mass spectrometric analysis. Compounds 1–6 were either brominated (1–3) or chlorinated (4–6), consistent with halogenation being a hallmark of many marine natural products. All extracts derived from these L. bouillonii collections were highly cytotoxic due to the presence of apratoxin A or also apratoxin C. Compounds 1–5 showed weak to moderate cytotoxicity to HT29 colorectal adenocarcinoma and HeLa cervical carcinoma cells. PMID:20704304

  16. Cytotoxic halogenated macrolides and modified peptides from the apratoxin-producing marine cyanobacterium Lyngbya bouillonii from Guam.

    PubMed

    Matthew, Susan; Salvador, Lilibeth A; Schupp, Peter J; Paul, Valerie J; Luesch, Hendrik

    2010-09-24

    Collections of the marine cyanobacterium Lyngbya bouillonii from shallow patch reefs in Apra Harbor, Guam, afforded three hitherto undescribed analogues of the glycosidic macrolide lyngbyaloside, namely, 2-epi-lyngbyaloside (1) and the regioisomeric 18E- and 18Z-lyngbyalosides C (2 and 3). Concurrently we discovered two new analogues of the cytoskeletal actin-disrupting lyngbyabellins, 27-deoxylyngbyabellin A (4) and lyngbyabellin J (5), a novel macrolide of the laingolide family, laingolide B (6), and a linear modified peptide, lyngbyapeptin D (7), along with known lyngbyabellins A and B, lyngbyapeptin A, and lyngbyaloside. The structures of 1-7 were elucidated by a combination of NMR spectroscopic and mass spectrometric analysis. Compounds 1-6 were either brominated (1-3) or chlorinated (4-6), consistent with halogenation being a hallmark of many marine natural products. All extracts derived from these L. bouillonii collections were highly cytotoxic due to the presence of apratoxin A or apratoxin C. Compounds 1-5 showed weak to moderate cytotoxicity to HT29 colorectal adenocarcinoma and HeLa cervical carcinoma cells.

  17. Heterocyst-specific flavodiiron protein Flv3B enables oxic diazotrophic growth of the filamentous cyanobacterium Anabaena sp. PCC 7120

    PubMed Central

    Ermakova, Maria; Battchikova, Natalia; Richaud, Pierre; Leino, Hannu; Kosourov, Sergey; Isojärvi, Janne; Peltier, Gilles; Flores, Enrique; Cournac, Laurent; Allahverdiyeva, Yagut; Aro, Eva-Mari

    2014-01-01

    Flavodiiron proteins are known to have crucial and specific roles in photoprotection of photosystems I and II in cyanobacteria. The filamentous, heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 contains, besides the four flavodiiron proteins Flv1A, Flv2, Flv3A, and Flv4 present in vegetative cells, two heterocyst-specific flavodiiron proteins, Flv1B and Flv3B. Here, we demonstrate that Flv3B is responsible for light-induced O2 uptake in heterocysts, and that the absence of the Flv3B protein severely compromises the growth of filaments in oxic, but not in microoxic, conditions. It is further demonstrated that Flv3B-mediated photosynthetic O2 uptake has a distinct role in heterocysts which cannot be substituted by respiratory O2 uptake in the protection of nitrogenase from oxidative damage and, thus, in an efficient provision of nitrogen to filaments. In line with this conclusion, the Δflv3B strain has reduced amounts of nitrogenase NifHDK subunits and shows multiple symptoms of nitrogen deficiency in the filaments. The apparent imbalance of cytosolic redox state in Δflv3B heterocysts also has a pronounced influence on the amounts of different transcripts and proteins. Therefore, an O2-related mechanism for control of gene expression is suggested to take place in heterocysts. PMID:25002499

  18. Amino Acid Transporters and Release of Hydrophobic Amino Acids in the Heterocyst-Forming Cyanobacterium Anabaena sp. Strain PCC 7120.

    PubMed

    Pernil, Rafael; Picossi, Silvia; Herrero, Antonia; Flores, Enrique; Mariscal, Vicente

    2015-04-23

    Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium that can use inorganic compounds such as nitrate or ammonium as nitrogen sources. In the absence of combined nitrogen, it can fix N2 in differentiated cells called heterocysts. Anabaena also shows substantial activities of amino acid uptake, and three ABC-type transporters for amino acids have been previously characterized. Seven new loci encoding predicted amino acid transporters were identified in the Anabaena genomic sequence and inactivated. Two of them were involved in amino acid uptake. Locus alr2535-alr2541 encodes the elements of a hydrophobic amino acid ABC-type transporter that is mainly involved in the uptake of glycine. ORF all0342 encodes a putative transporter from the dicarboxylate/amino acid:cation symporter (DAACS) family whose inactivation resulted in an increased uptake of a broad range of amino acids. An assay to study amino acid release from Anabaena filaments to the external medium was set up. Net release of the alanine analogue α-aminoisobutyric acid (AIB) was observed when transport system N-I (a hydrophobic amino acid ABC-type transporter) was engaged in the uptake of a specific substrate. The rate of AIB release was directly proportional to the intracellular AIB concentration, suggesting leakage from the cells by diffusion.

  19. Cell envelope components influencing filament length in the heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120.

    PubMed

    Burnat, Mireia; Schleiff, Enrico; Flores, Enrique

    2014-12-01

    Heterocyst-forming cyanobacteria grow as chains of cells (known as trichomes or filaments) that can be hundreds of cells long. The filament consists of individual cells surrounded by a cytoplasmic membrane and peptidoglycan layers. The cells, however, share a continuous outer membrane, and septal proteins, such as SepJ, are important for cell-cell contact and filament formation. Here, we addressed a possible role of cell envelope components in filamentation, the process of producing and maintaining filaments, in the model cyanobacterium Anabaena sp. strain PCC 7120. We studied filament length and the response of the filaments to mechanical fragmentation in a number of strains with mutations in genes encoding cell envelope components. Previously published peptidoglycan- and outer membrane-related gene mutants and strains with mutations in two genes (all5045 and alr0718) encoding class B penicillin-binding proteins isolated in this work were used. Our results show that filament length is affected in most cell envelope mutants, but the filaments of alr5045 and alr2270 gene mutants were particularly fragmented. All5045 is a dd-transpeptidase involved in peptidoglycan elongation during cell growth, and Alr2270 is an enzyme involved in the biosynthesis of lipid A, a key component of lipopolysaccharide. These results indicate that both components of the cell envelope, the murein sacculus and the outer membrane, influence filamentation. As deduced from the filament fragmentation phenotypes of their mutants, however, none of these elements is as important for filamentation as the septal protein SepJ.

  20. Heterocyst-specific flavodiiron protein Flv3B enables oxic diazotrophic growth of the filamentous cyanobacterium Anabaena sp. PCC 7120.

    PubMed

    Ermakova, Maria; Battchikova, Natalia; Richaud, Pierre; Leino, Hannu; Kosourov, Sergey; Isojärvi, Janne; Peltier, Gilles; Flores, Enrique; Cournac, Laurent; Allahverdiyeva, Yagut; Aro, Eva-Mari

    2014-07-29

    Flavodiiron proteins are known to have crucial and specific roles in photoprotection of photosystems I and II in cyanobacteria. The filamentous, heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 contains, besides the four flavodiiron proteins Flv1A, Flv2, Flv3A, and Flv4 present in vegetative cells, two heterocyst-specific flavodiiron proteins, Flv1B and Flv3B. Here, we demonstrate that Flv3B is responsible for light-induced O2 uptake in heterocysts, and that the absence of the Flv3B protein severely compromises the growth of filaments in oxic, but not in microoxic, conditions. It is further demonstrated that Flv3B-mediated photosynthetic O2 uptake has a distinct role in heterocysts which cannot be substituted by respiratory O2 uptake in the protection of nitrogenase from oxidative damage and, thus, in an efficient provision of nitrogen to filaments. In line with this conclusion, the Δflv3B strain has reduced amounts of nitrogenase NifHDK subunits and shows multiple symptoms of nitrogen deficiency in the filaments. The apparent imbalance of cytosolic redox state in Δflv3B heterocysts also has a pronounced influence on the amounts of different transcripts and proteins. Therefore, an O2-related mechanism for control of gene expression is suggested to take place in heterocysts.

  1. Ecological physiology of Synechococcus sp. strain SH-94-5, a naturally occurring cyanobacterium deficient in nitrate assimilation

    NASA Technical Reports Server (NTRS)

    Miller, S. R.; Castenholz, R. W.

    2001-01-01

    Synechococcus sp. strain SH-94-5 is a nitrate assimilation-deficient cyanobacterium which was isolated from an ammonium-replete hot spring in central Oregon. While this clone could grow on ammonium and some forms of organic nitrogen as sole nitrogen sources, it could not grow on either nitrate or nitrite, even under conditions favoring passive diffusion. It was determined that this clone does not express functional nitrate reductase or nitrite reductase and that the lack of activity of either enzyme is not due to inactivation of the cyanobacterial nitrogen control protein NtcA. A few other naturally occurring cyanobacterial strains are also nitrate assimilation deficient, and phylogenetic analyses indicated that the ability to utilize nitrate has been independently lost at least four times during the evolutionary history of the cyanobacteria. This phenotype is associated with the presence of environmental ammonium, a negative regulator of nitrate assimilation gene expression, which may indicate that natural selection to maintain functional copies of nitrate assimilation genes has been relaxed in these habitats. These results suggest how the evolutionary fates of conditionally expressed genes might differ between environments and thereby effect ecological divergence and biogeographical structure in the microbial world.

  2. Computational inference and experimental validation of the nitrogen assimilation regulatory network in cyanobacterium Synechococcus sp. WH 8102.

    PubMed

    Su, Zhengchang; Mao, Fenglou; Dam, Phuongan; Wu, Hongwei; Olman, Victor; Paulsen, Ian T; Palenik, Brian; Xu, Ying

    2006-01-01

    Deciphering the regulatory networks encoded in the genome of an organism represents one of the most interesting and challenging tasks in the post-genome sequencing era. As an example of this problem, we have predicted a detailed model for the nitrogen assimilation network in cyanobacterium Synechococcus sp. WH 8102 (WH8102) using a computational protocol based on comparative genomics analysis and mining experimental data from related organisms that are relatively well studied. This computational model is in excellent agreement with the microarray gene expression data collected under ammonium-rich versus nitrate-rich growth conditions, suggesting that our computational protocol is capable of predicting biological pathways/networks with high accuracy. We then refined the computational model using the microarray data, and proposed a new model for the nitrogen assimilation network in WH8102. An intriguing discovery from this study is that nitrogen assimilation affects the expression of many genes involved in photosynthesis, suggesting a tight coordination between nitrogen assimilation and photosynthesis processes. Moreover, for some of these genes, this coordination is probably mediated by NtcA through the canonical NtcA promoters in their regulatory regions.

  3. Photoinhibition induced alterations in energy transfer process in phycobilisomes of PS II in the cyanobacterium, Spirulina platensis.

    PubMed

    Kumar, Duvvuri Prasanna; Murthy, Sistla D S

    2007-09-30

    Exposure of algae or plants to irradiance from above the light saturation point of photosynthesis is known as high light stress. This high light stress induces various responses including photoinhibition of the photosynthetic apparatus. The degree of photoinhibition could be clearly determined by measuring the parameters such as absorption and fluorescence of chromoproteins. In cyanobacteria and red algae, most of the photosystem (PS) II associated light harvesting is performed by a membrane attached complex called the phycobilisome (PBS). The effects of high intensity light (1000-4000 micromol photons m(-2) s(-1)) on excitation energy transfer from PBSs to PS II in a cyanobacterium Spirulina platensis were studied by measuring room temperature PC fluorescence emission spectra. High light (3000 micromol photons m(-2) s(-1)) stress had a significant effect on PC fluorescence emission spectra. On the other hand, light stress induced an increase in the ratio of PC fluorescence intensity of PBS indicating that light stress inhibits excitation energy transfer from PBS to PS II. The high light treatment to 3000 micromol photons m(-2) s(-1) caused disappearance of 31.5 kDa linker polypeptide which is known to link PC discs together. In addition we observed the similar decrease in the other polypeptide contents. Our data concludes that the Spirulina cells upon light treatment causes alterations in the phycobiliproteins (PBPs) and affects the energy transfer process within the PBSs.

  4. Requirement of Fra proteins for communication channels between cells in the filamentous nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120

    PubMed Central

    Omairi-Nasser, Amin; Mariscal, Vicente; Austin, Jotham R.; Haselkorn, Robert

    2015-01-01

    The filamentous nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120 differentiates specialized cells, heterocysts, that fix atmospheric nitrogen and transfer the fixed nitrogen to adjacent vegetative cells. Reciprocally, vegetative cells transfer fixed carbon to heterocysts. Several routes have been described for metabolite exchange within the filament, one of which involves communicating channels that penetrate the septum between adjacent cells. Several fra gene mutants were isolated 25 y ago on the basis of their phenotypes: inability to fix nitrogen and fragmentation of filaments upon transfer from N+ to N− media. Cryopreservation combined with electron tomography were used to investigate the role of three fra gene products in channel formation. FraC and FraG are clearly involved in channel formation, whereas FraD has a minor part. Additionally, FraG was located close to the cytoplasmic membrane and in the heterocyst neck, using immunogold labeling with antibody raised to the N-terminal domain of the FraG protein. PMID:26216997

  5. Posttranscriptional regulation of glutamine synthetase in the filamentous Cyanobacterium Anabaena sp. PCC 7120: differential expression between vegetative cells and heterocysts.

    PubMed

    Galmozzi, Carla V; Saelices, Lorena; Florencio, Francisco J; Muro-Pastor, M Isabel

    2010-09-01

    Genes homologous to those implicated in glutamine synthetase (GS) regulation by protein-protein interaction in the cyanobacterium Synechocystis sp. strain PCC 6803 are conserved in several cyanobacterial sequenced genomes. We investigated this GS regulatory mechanism in Anabaena sp. strain PCC 7120. In this strain the system operates with only one GS inactivation factor (inactivation factor 7A [IF7A]), encoded by open reading frame (ORF) asl2329 (gifA). Following addition of ammonium, expression of gifA is derepressed, leading to the synthesis of IF7A, and consequently, GS is inactivated. Upon ammonium removal, the GS activity returns to the initial level and IF7A becomes undetectable. The global nitrogen control protein NtcA binds to the gifA promoter. Constitutive high expression levels of gifA were found in an Anabaena ntcA mutant (CSE2), indicating a repressor role for NtcA. In vitro studies demonstrate that Anabaena GS is not inactivated by Synechocystis IFs (IF7 and IF17), indicating the specificity of the system. We constructed an Anabaena strain expressing a second inactivating factor, containing the amino-terminal part of IF17 from Synechocystis fused to IF7A. GS inactivation in this strain is more effective than that in the wild type (WT) and resembles that observed in Synechocystis. Finally we found differential expression of the IF system between heterocysts and vegetative cells of Anabaena.

  6. Sustained photoproduction of ammonia from dinitrogen and water by the nitrogen-fixing cyanobacterium Anabaena sp. strain ATCC33047

    SciTech Connect

    Ramos, J.L.; Guerrero, M.G.; Losada, M.

    1984-07-01

    Conditions have been developed that lengthen the time during which photosynthetic dinitrogen fixation by filaments of the cyanobacterium Anabaena sp. strain ATCC 33047 proceeds freely, whereas the subsequent conversion of ammonia into organic nitrogen remains blocked, with the resulting ammonia released to the outer medium. When L-methionine-DL-sulfoximine was added every 20 h, maximal rates of ammonia production (25 to 30 ..mu..mol/mg of chlorophyll per h) were maintained for about 50 h. After this time, ammonia production ceased due to a deficiency of glutamine and other nitrogenous compounds in the filaments, conditions which finally led to cell lysis. The effective ammonia production period could be further extended to about 7 days by adding a small amount of glutamine at the end of a 40-h production period or by allowing the cells to recover for 8 h in the absence of L-methionine-DL-sulfoximine after every 40-h period in the presence of the inhibitor. A more prolonged steady production of ammonia, lasting for longer than 2 weeks, was achieved by alternating treatments with the glutamine synthetase inhibitors L-methionine-DL-sulfoximine and phosphinothricin, provided that 8-h recovery periods in the absence of either compound were also alternated throughout. The biochemically manipulated cyanobacterial filaments thus represent a system that is relatively stable with time for the conversion of light energy into chemical energy, with the net generation of a valuable fuel and fertilizer through the photoreduction of dinitrogen to ammonia.

  7. Effect of nitrogen on cellular production and release of the neurotoxin anatoxin-a in a nitrogen-fixing cyanobacterium.

    PubMed

    Gagnon, Alexis; Pick, Frances R

    2012-01-01

    Anatoxin-a (ANTX) is a neurotoxin produced by several freshwater cyanobacteria and implicated in lethal poisonings of domesticated animals and wildlife. The factors leading to its production in nature and in culture are not well understood. Resource availability may influence its cellular production as suggested by the carbon-nutrient hypothesis, which links the amount of secondary metabolites produced by plants or microbes to the relative abundance of nutrients. We tested the effects of nitrogen supply (as 1, 5, and 100% N of standard cyanobacterial medium corresponding to 15, 75, and 1500 mg L(-1) of NaNO(3) respectively) on ANTX production and release in a toxic strain of the planktonic cyanobacterium Aphanizomenon issatschenkoi (Nostocales). We hypothesized that nitrogen deficiency might constrain the production of ANTX. However, the total concentration and more significantly the cellular content of anatoxin-a peaked (max. 146 μg/L and 1683 μg g(-1) dry weight) at intermediate levels of nitrogen supply when N-deficiency was evident based on phycocyanin to chlorophyll a and carbon to nitrogen ratios. The results suggest that the cellular production of anatoxin-a may be stimulated by moderate nitrogen stress. Maximal cellular contents of other cyanotoxins have recently been reported under severe stress conditions in another Nostocales species.

  8. Acclimation of the Global Transcriptome of the Cyanobacterium Synechococcus sp. Strain PCC 7002 to Nutrient Limitations and Different Nitrogen Sources

    PubMed Central

    Ludwig, Marcus; Bryant, Donald A.

    2012-01-01

    The unicellular, euryhaline cyanobacterium Synechococcus sp. strain PCC 7002 is a model organism for laboratory-based studies of cyanobacterial metabolism and is a potential platform for biotechnological applications. Two of its most notable properties are its exceptional tolerance of high-light intensity and very rapid growth under optimal conditions. In this study, transcription profiling by RNAseq has been used to perform an integrated study of global changes in transcript levels in cells subjected to limitation for the major nutrients CO2, nitrogen, sulfate, phosphate, and iron. Transcriptional patterns for cells grown on nitrate, ammonia, and urea were also studied. Nutrient limitation caused strong decreases of transcript levels of the genes encoding major metabolic pathways, especially for components of the photosynthetic apparatus, CO2 fixation, and protein biosynthesis. Uptake mechanisms for the respective nutrients were strongly up-regulated. The transcription data further suggest that major changes in the composition of the NADH dehydrogenase complex occur upon nutrient limitation. Transcripts for flavoproteins increased strongly when CO2 was limiting. Genes involved in protection from oxidative stress generally showed high, constitutive transcript levels, which possibly explains the high-light tolerance of this organism. The transcriptomes of cells grown with ammonia or urea as nitrogen source showed increased transcript levels for components of the CO2 fixation machinery compared to cells grown with nitrate, but in general transcription differences in cells grown on different N-sources exhibited surprisingly minor differences. PMID:22514553

  9. Acrolein, an α,β-unsaturated carbonyl, inhibits both growth and PSII activity in the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Shimakawa, Ginga; Iwamoto, Tatsuya; Mabuchi, Tomohito; Saito, Ryota; Yamamoto, Hiroshi; Amako, Katsumi; Sugimoto, Toshio; Makino, Amane; Miyake, Chikahiro

    2013-01-01

    In this study, we sought to determine whether and how an α,β-unsaturated carbonyl, acrolein, can inhibit the growth of the cyanobacterium Synechocystis sp. PCC6803 (S. 6803). Treatment of S. 6803 with 200 µM acrolein for 3 d significantly and irreversibly inhibited its growth. To elucidate the inhibitory mechanism, we examined the effects of acrolein on photosynthesis. In contrast to dark conditions, the addition of acrolein to S. 6803 under conditions of illumination lowered the CO₂-dependent O₂ evolution rate (photosynthetic activity). Furthermore, treatment with acrolein lowered the activity reducing dimethyl benzoquinone in photosystem II (PSII). Acrolein also suppressed the reduction rate for the oxidized form of the reaction center chlorophyll of photosystem I (PSI), P700. These results indicate that acrolein inhibited PSII activity in thylakoid membranes. The addition of 200 µM acrolein to the illuminated S. 6803 cells gradually increased the steady-state level (Fs) of Chl fluorescence and decreased the quantum yield of PSII. These results suggested that acrolein damaged the acceptor side of PSII. On the other hand, acrolein did not inhibit respiration. From the above results, we gained insight into the metabolism of acrolein and its physiological effects in S. 6803.

  10. Purification and Biochemical Analysis of the Cytoplasmic Membrane from the Desiccation-Tolerant Cyanobacterium Nostoc commune UTEX 584

    PubMed Central

    Olie, Jaap J.; Potts, Malcolm

    1986-01-01

    The cytoplasmic membrane of the heterocystous cyanobacterium Nostoc commune UTEX 584 was isolated free of thylakoids and phycobiliprotein-membrane complexes by flotation centrifugation. Purified membranes had a buoyant density of 1.07 g cm−3 and were bright orange. Twelve major proteins were detected in the membrane, and of these, the most abundant had molecular masses of 83, 71, 68, 51, and 46 kilodaltons. The ester-linked fatty acids of the methanol fraction contained 16:0, 18:0, 18:1ω9c, 20:0, and 20:3ω3 with no traces of hydroxy fatty acids. Compound 20:3ω3 represented 56.8% of the total fatty acid methyl esters, a feature which distinguishes the cell membrane of N. commune UTEX 584 from those of all other cyanobacteria which have been characterized to date. Fatty acid 18:3 was not detected. Carotenoids were analyzed by highperformance liquid chromatography. The cytoplasmic membrane contained β-carotene and echinenone as the dominant carotenoids and lacked chlorophyll a and pheophytin a. Whole cells contained β-carotene and echinenone, and lesser amounts of zeaxanthin and (3R)-cryptoxanthin. Images PMID:16347165

  11. Characterization of the chemical diversity of glycosylated mycosporine-like amino acids in the terrestrial cyanobacterium Nostoc commune.

    PubMed

    Nazifi, Ehsan; Wada, Naoki; Asano, Tomoya; Nishiuchi, Takumi; Iwamuro, Yoshiaki; Chinaka, Satoshi; Matsugo, Seiichi; Sakamoto, Toshio

    2015-01-01

    Mycosporine-like amino acids (MAAs) are UV-absorbing pigments, and structurally unique glycosylated MAAs are found in the terrestrial cyanobacterium Nostoc commune. In this study, we examined two genotypes of N.commune colonies with different water extract UV-absorption spectra. We found structurally distinct MAAs in each genotype. The water extract from genotype A showed a UV-absorbing spectrum with an absorption maximum at 335nm. The extract contained the following compounds: 7-O-(β-arabinopyranosyl)-porphyra-334 (478Da), pentose-bound shinorine (464Da), hexose-bound porphyra-334 (508Da) and porphyra-334 (346Da). The water extract from genotype B showed a characteristic UV-absorbing spectrum with double absorption maxima at 312 and 340nm. The extract contained hybrid MAAs (1050Da and 880Da) with two distinct chromophores of 3-aminocyclohexen-1-one and 1,3-diaminocyclohexen linked to 2-O-(β-xylopyranosyl)-β-galactopyranoside. A novel 273-Da MAA with an absorption maximum at 310nm was also identified in genotype B. The MAA consisted of a 3-aminocyclohexen-1-one linked to a γ-aminobutyric acid chain. These MAAs had potent radical scavenging activities in vitro and the results confirmed that the MAAs have multiple roles as a UV protectant and an antioxidant relevant to anhydrobiosis in N. commune. The two genotypes of N. commune exclusively produced their own characteristic glycosylated MAAs, which supports that MAA composition could be a chemotaxonomic marker for the classification of N. commune.

  12. Evidence regarding the UV sunscreen role of a mycosporine-like compound in the cyanobacterium Gloeocapsa sp

    SciTech Connect

    Garcia-Pichel, F.; Wingard, C.E.; Castenholz, R.W. )

    1993-01-01

    The mycosporine-like amino acids (MAAs) have been thought to serve a UV sunscreen role in organisms that produce or contain them because MAAs present strong absorbance in the UV region and because there is no other apparent biological function. The researchers used the cyanobacterium Gloeocapsa sp. to assess the possible sunscreen role of MAAs. Five conditions are evaluated: (1) absorption of radiation high enough to provide benefit to the organisms; (2) correlation of presence of the compound with enhansed fitness under UV; (3) concentration of the compound and resistance to UV still present under physiological inactivity; (4) effect maximal at wavelengths of maximal absorption; (5) loss of protection after artificial removal of compound. The results indicate that only a small sunscreen effect can be ascribed to the MAA in the Gloecapsa sp. under these experimental conditions. It is possible however, that in the typical undisturbed colonial growth form, MAAs and their screening action may become major factors in resistance to UV radiation. 25 refs., 7 figs., 1 tab.

  13. Effect of Nitrogen on Cellular Production and Release of the Neurotoxin Anatoxin-A in a Nitrogen-Fixing Cyanobacterium

    PubMed Central

    Gagnon, Alexis; Pick, Frances R.

    2012-01-01

    Anatoxin-a (ANTX) is a neurotoxin produced by several freshwater cyanobacteria and implicated in lethal poisonings of domesticated animals and wildlife. The factors leading to its production in nature and in culture are not well understood. Resource availability may influence its cellular production as suggested by the carbon-nutrient hypothesis, which links the amount of secondary metabolites produced by plants or microbes to the relative abundance of nutrients. We tested the effects of nitrogen supply (as 1, 5, and 100% N of standard cyanobacterial medium corresponding to 15, 75, and 1500 mg L−1 of NaNO3 respectively) on ANTX production and release in a toxic strain of the planktonic cyanobacterium Aphanizomenon issatschenkoi (Nostocales). We hypothesized that nitrogen deficiency might constrain the production of ANTX. However, the total concentration and more significantly the cellular content of anatoxin-a peaked (max. 146 μg/L and 1683 μg g−1 dry weight) at intermediate levels of nitrogen supply when N-deficiency was evident based on phycocyanin to chlorophyll a and carbon to nitrogen ratios. The results suggest that the cellular production of anatoxin-a may be stimulated by moderate nitrogen stress. Maximal cellular contents of other cyanotoxins have recently been reported under severe stress conditions in another Nostocales species. PMID:22701451

  14. Growth inhibition and possible mechanism of oleamide against the toxin-producing cyanobacterium Microcystis aeruginosa NIES-843.

    PubMed

    Shao, Jihai; He, Yaxian; Li, Fan; Zhang, Huiling; Chen, Anwei; Luo, Si; Gu, Ji-Dong

    2016-01-01

    Oleamide, a fatty acid derivative, shows inhibitory effect against the bloom-forming cyanobacterium Microcystis aeruginosa. The EC50 of oleamide on the growth of M. aeruginosa NIES-843 was 8.60 ± 1.20 mg/L. In order to elucidate the possible mechanism of toxicity of oleamide against M. aeruginosa, chlorophyll fluorescence transient, cellular ultrastructure, fatty acids composition and the transcription of the mcyB gene involved in microcystins synthesis were studied. The results of chlorophyll fluorescence transient showed that oleamide could destruct the electron accepting side of the photosystem II of M. aeruginosa NIES-843. Cellular ultrastructure examination indicated that the destruction of fatty acid constituents, the distortion of thylakoid membrane and the loss of integrity of cell membrane were associated with oleamide treatment and concentration. The damage of cellular membrane increased the release of microcystins from intact cells into the medium. Results presented in this study provide new information on the possible mechanisms involved and potential utilization of oleamide as an algicide in cyanobacterial bloom control. PMID:26547872

  15. Hydrogen Generation through Indirect Biophotolysis in Batch Cultures of the Non-Heterocystous Nitrogen-Fixing Cyanobacterium Plectonema boryanum

    SciTech Connect

    Huesemann, Michael H.; Hausmann, Tom S.; Carter, Blaine M.; Gerschler, Jared J.; Benemann, John R.

    2010-09-01

    The nitrogen-fixing non-heterocystous cyanobacterium Plectonema boryanum was used as a model organism to study hydrogen generation by indirect biophotolysis in nitrogen-limited batch cultures that were continuously illuminated and sparged with argon/CO2 to maintain anaerobiosis. The highest hydrogen production rate (i.e., 0.18 mL/mg∙day or 7.3 μmol/mg∙day) ) was observed in cultures with an initial medium nitrate concentration of 1 mM at a light intensity of 100 μmol/m2∙sec. The addition of photosystem II inhibitor DCMU did not reduce hydrogen production rates relative to unchallenged controls for 50 to 150 hours, and intracellular glycogen concentrations decreased significantly during the hydrogen generation period. The insensitivity of the hydrogen production process to DCMU is indicative of the fact that hydrogen was not derived from water splitting at photosystem II (i.e., direct biophotolysis) but rather from electrons provided by intracellular glycogen reserves (i.e., indirect biophotolysis). It was shown that hydrogen generation could be sustained for long time periods by subjecting the cultures to alternating cycles of aerobic, nitrogen-limited growth and anaerobic hydrogen production.

  16. Redox regulation of glycogen biosynthesis in the cyanobacterium Synechocystis sp. PCC 6803: analysis of the AGP and glycogen synthases.

    PubMed

    Díaz-Troya, Sandra; López-Maury, Luis; Sánchez-Riego, Ana María; Roldán, Miguel; Florencio, Francisco J

    2014-01-01

    Glycogen constitutes the major carbon storage source in cyanobacteria, as starch in algae and higher plants. Glycogen and starch synthesis is linked to active photosynthesis and both of them are degraded to glucose in the dark to maintain cell metabolism. Control of glycogen biosynthesis in cyanobacteria could be mediated by the regulation of the enzymes involved in this process, ADP-glucose pyrophosphorylase (AGP) and glycogen synthase, which were identified as putative thioredoxin targets. We have analyzed whether both enzymes were subjected to redox modification using purified recombinant enzymes or cell extracts in the model cyanobacterium Synechocystis sp. PCC 6803. Our results indicate that both AGP and glycogen synthases are sensitive to copper oxidation. However, only AGP exhibits a decrease in its enzymatic activity, which is recovered after reduction by DTT or reduced thioredoxin (TrxA), suggesting a redox control of AGP. In order to elucidate the role in redox control of the cysteine residues present on the AGP sequence (C45, C185, C320, and C337), they were replaced with serine. All AGP mutant proteins remained active when expressed in Synechocystis, although they showed different electrophoretic mobility profiles after copper oxidation, reflecting a complex pattern of cysteines interaction.

  17. Excitation energy transfer in intact cells and in the phycobiliprotein antennae of the chlorophyll d containing cyanobacterium Acaryochloris marina.

    PubMed

    Theiss, Christoph; Schmitt, Franz-Josef; Pieper, Jörg; Nganou, Collins; Grehn, Moritz; Vitali, Marco; Olliges, Rachel; Eichler, Hans Joachim; Eckert, Hann-Jörg

    2011-08-15

    The cyanobacterium Acaryochloris marina is unique because it mainly contains Chlorophyll d (Chl d) in the core complexes of PS I and PS II instead of the usually dominant Chl a. Furthermore, its light harvesting system has a structure also different from other cyanobacteria. It has both, a membrane-internal chlorophyll containing antenna and a membrane-external phycobiliprotein (PBP) complex. The first one binds Chl d and is structurally analogous to CP43. The latter one has a rod-like structure consisting of three phycocyanin (PC) homohexamers and one heterohexamer containing PC and allophycocyanin (APC). In this paper, we give an overview on the investigations of excitation energy transfer (EET) in this PBP-light-harvesting system and of charge separation in the photosystem II (PS II) reaction center of A. marina performed at the Technische Universität Berlin. Due to the unique structure of the PBP antenna in A. marina, this EET occurs on a much shorter overall time scale than in other cyanobacteria. We also briefly discuss the question of the pigment composition in the reaction center (RC) of PS II and the nature of the primary donor of the PS II RC.

  18. Short-term light adaptation of a cyanobacterium, Synechocystis sp. PCC 6803, probed by time-resolved fluorescence spectroscopy.

    PubMed

    Akimoto, Seiji; Yokono, Makio; Yokono, Erina; Aikawa, Shimpei; Kondo, Akihiko

    2014-08-01

    In photosynthetic organisms, the interactions among pigment-protein complexes change in response to light conditions. In the present study, we analyzed the transfer of excitation energy from the phycobilisome (PBS) and photosystem (PS) II to PSI in the cyanobacterium Synechocystis sp. PCC 6803. After 20 min of dark adaptation, Synechocystis cells were illuminated for 5 min with strong light with different spectral profiles, blue, green, two kinds of red, and white light. After illumination, the energy-transfer characteristics were evaluated using steady-state fluorescence and picosecond time-resolved fluorescence spectroscopy techniques. The fluorescence rise and decay curves were analyzed by global analysis to obtain fluorescence decay-associated spectra, followed by spectral component analysis. Under illumination with strong light, the contribution of the energy transfer from the PSII to PSI (spillover) became greater, and that of the energy transfer from the PBS to PSI decreased; the former change was larger than the latter. The energy transfer pathway to PSI was sensitive to red light. We discuss the short-term adaptation of energy-transfer processes in Synechocystis under strong-light conditions.

  19. Effects of Hydrogen Peroxide and Ultrasound on Biomass Reduction and Toxin Release in the Cyanobacterium, Microcystis aeruginosa

    PubMed Central

    Lürling, Miquel; Meng, Debin; Faassen, Elisabeth J.

    2014-01-01

    Cyanobacterial blooms are expected to increase, and the toxins they produce threaten human health and impair ecosystem services. The reduction of the nutrient load of surface waters is the preferred way to prevent these blooms; however, this is not always feasible. Quick curative measures are therefore preferred in some cases. Two of these proposed measures, peroxide and ultrasound, were tested for their efficiency in reducing cyanobacterial biomass and potential release of cyanotoxins. Hereto, laboratory assays with a microcystin (MC)-producing cyanobacterium (Microcystis aeruginosa) were conducted. Peroxide effectively reduced M. aeruginosa biomass when dosed at 4 or 8 mg L−1, but not at 1 and 2 mg L−1. Peroxide dosed at 4 or 8 mg L−1 lowered total MC concentrations by 23%, yet led to a significant release of MCs into the water. Dissolved MC concentrations were nine-times (4 mg L−1) and 12-times (8 mg L−1 H2O2) higher than in the control. Cell lysis moreover increased the proportion of the dissolved hydrophobic variants, MC-LW and MC-LF (where L = Leucine, W = tryptophan, F = phenylalanine). Ultrasound treatment with commercial transducers sold for clearing ponds and lakes only caused minimal growth inhibition and some release of MCs into the water. Commercial ultrasound transducers are therefore ineffective at controlling cyanobacteria. PMID:25513892

  20. Potassium sensitivity differs among strains of the harmful cyanobacterium Microcystis and correlates with the presence of salt tolerance genes.

    PubMed

    Sandrini, Giovanni; Huisman, Jef; Matthijs, Hans C P

    2015-08-01

    Microcystis aeruginosa is a ubiquitous harmful cyanobacterium that causes problems in eutrophic lakes. Potassium ion (K(+)) addition is one of the suggested methods to combat harmful cyanobacterial blooms. To investigate the effectiveness of this method, we compared the potassium ion sensitivity of four Microcystis strains. Microcystis strains PCC 7005 and NIES-843 were very susceptible to potassium ion concentrations of ∼ 12 mmol L(-1), whereas strain PCC 7806 and its non-toxic mutant PCC 7806 ΔmcyB were not affected by added potassium ions. The origin of the strain appears to be of importance. Strain PCC 7806 originates from brackish water and possesses genes for the synthesis of the compatible solute sucrose, the water channel protein gene aqpZ and the sodium influx gene nhaS2, whereas strains PCC 7005 and NIES-843 have a freshwater origin and lack these genes. We conclude that potassium ion addition will not be a successful mitigation strategy in brackish waters, but may temporarily suppress Microcystis blooms in freshwater lakes. However, in the long run other Microcystis strains or other cyanobacteria with a higher salt tolerance will likely take over. In addition, our results also have implications for the potassium ion concentrations of mineral media used in laboratory studies with cyanobacteria.

  1. Metabolic adaptations in a H2 producing heterocyst-forming cyanobacterium: potentials and implications for biological engineering.

    PubMed

    Ekman, Martin; Ow, Saw Yen; Holmqvist, Marie; Zhang, Xiaohui; van Wagenen, Jon; Wright, Phillip C; Stensjö, Karin

    2011-04-01

    Nostoc punctiforme ATCC 29133 is a photoautotrophic cyanobacterium with the ability to fix atmospheric nitrogen and photoproduce hydrogen through the enzyme nitrogenase. The H(2) produced is reoxidized by an uptake hydrogenase. Inactivation of the uptake hydrogenase in N. punctiforme leads to increased H(2) release but unchanged rates of N(2) fixation, indicating redirected metabolism. System-wide understanding of the mechanisms of this metabolic redirection was obtained using complementary quantitative proteomic approaches, at both the filament and the heterocyst level. Of the total 1070 identified and quantified proteins, 239 were differentially expressed in the uptake hydrogenase mutant (NHM5) as compared to wild type. Our results indicate that the inactivation of uptake hydrogenase in N. punctiforme changes the overall metabolic equilibrium, affecting both oxygen reduction mechanisms in heterocysts as well as processes providing reducing equivalents for metabolic functions such as N(2) fixation. We identify specific metabolic processes used by NHM5 to maintain a high rate of N(2) fixation, and thereby potential targets for further improvement of nitrogenase based H(2) photogeneration. These targets include, but are not limited to, components of the oxygen scavenging capacity and cell envelope of heterocysts and proteins directly or indirectly involved in reduced carbon transport from vegetative cells to heterocysts.

  2. Gene expression of a two-component regulatory system associated with sunscreen biosynthesis in the cyanobacterium Nostoc punctiforme ATCC 29133.

    PubMed

    Janssen, Jacob; Soule, Tanya

    2016-01-01

    Long-wavelength ultraviolet radiation (UVA) can damage cells through photooxidative stress, leading to harmful photosensitized proteins and pigments in cyanobacteria. To mitigate damage, some cyanobacteria secrete the UVA-absorbing pigment scytonemin into their extracellular sheath. Comparative genomic analyses suggest that scytonemin biosynthesis is regulated by the two-component regulatory system (TCRS) proteins encoded by Npun_F1277 and Npun_F1278 in the cyanobacterium Nostoc punctiforme ATCC 29133. To understand the dynamics of these genes, their expression was measured following exposure to UVA, UVB, high visible (VIS) irradiance and oxidative stress for 20, 40 and 60 min. Overall, both genes had statistically similar patterns of expression for all four conditions and were generally upregulated, except for those exposed to UVB by 60 min and for the cells under oxidative stress. The greatest UVA response was an upregulation by 20 min, while the response to UVB was the most dramatic and persisted through 40 min. High VIS irradiance resulted in a modest upregulation, while oxidative stress caused a slight downregulation. Both genes were also found to occur on the same transcript. These results demonstrate that these genes are positively responding to several light-associated conditions, which suggests that this TCRS may regulate more than just scytonemin biosynthesis under UVA stress.

  3. Amino Acid Transporters and Release of Hydrophobic Amino Acids in the Heterocyst-Forming Cyanobacterium Anabaena sp. Strain PCC 7120

    PubMed Central

    Pernil, Rafael; Picossi, Silvia; Herrero, Antonia; Flores, Enrique; Mariscal, Vicente

    2015-01-01

    Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium that can use inorganic compounds such as nitrate or ammonium as nitrogen sources. In the absence of combined nitrogen, it can fix N2 in differentiated cells called heterocysts. Anabaena also shows substantial activities of amino acid uptake, and three ABC-type transporters for amino acids have been previously characterized. Seven new loci encoding predicted amino acid transporters were identified in the Anabaena genomic sequence and inactivated. Two of them were involved in amino acid uptake. Locus alr2535-alr2541 encodes the elements of a hydrophobic amino acid ABC-type transporter that is mainly involved in the uptake of glycine. ORF all0342 encodes a putative transporter from the dicarboxylate/amino acid:cation symporter (DAACS) family whose inactivation resulted in an increased uptake of a broad range of amino acids. An assay to study amino acid release from Anabaena filaments to the external medium was set up. Net release of the alanine analogue α-aminoisobutyric acid (AIB) was observed when transport system N-I (a hydrophobic amino acid ABC-type transporter) was engaged in the uptake of a specific substrate. The rate of AIB release was directly proportional to the intracellular AIB concentration, suggesting leakage from the cells by diffusion. PMID:25915115

  4. Effects of hydrogen peroxide and ultrasound on biomass reduction and toxin release in the cyanobacterium, Microcystis aeruginosa.

    PubMed

    Lürling, Miquel; Meng, Debin; Faassen, Elisabeth J

    2014-01-01

    Cyanobacterial blooms are expected to increase, and the toxins they produce threaten human health and impair ecosystem services. The reduction of the nutrient load of surface waters is the preferred way to prevent these blooms; however, this is not always feasible. Quick curative measures are therefore preferred in some cases. Two of these proposed measures, peroxide and ultrasound, were tested for their efficiency in reducing cyanobacterial biomass and potential release of cyanotoxins. Hereto, laboratory assays with a microcystin (MC)-producing cyanobacterium (Microcystis aeruginosa) were conducted. Peroxide effectively reduced M. aeruginosa biomass when dosed at 4 or 8 mg L-1, but not at 1 and 2 mg L-1. Peroxide dosed at 4 or 8 mg L-1 lowered total MC concentrations by 23%, yet led to a significant release of MCs into the water. Dissolved MC concentrations were nine-times (4 mg L-1) and 12-times (8 mg L-1 H2O2) higher than in the control. Cell lysis moreover increased the proportion of the dissolved hydrophobic variants, MC-LW and MC-LF (where L = Leucine, W = tryptophan, F = phenylalanine). Ultrasound treatment with commercial transducers sold for clearing ponds and lakes only caused minimal growth inhibition and some release of MCs into the water. Commercial ultrasound transducers are therefore ineffective at controlling cyanobacteria. PMID:25513892

  5. Constant phycobilisome size in chromatically adapted cells of the cyanobacterium Tolypothrix tenuis, and variation in Nostoc sp

    SciTech Connect

    Ohki, K.; Gantt, E.; Lipschultz, C.A.; Ernst, M.C.

    1985-12-01

    Phycobilisomes of Tolypothrix tenuis, a cyanobacterium capable of complete chromatic adaptation, were studied from cells grown in red and green light, and in darkness. The phycobilisome size remained constant irrespective of the light quality. The hemidiscoidal phycobilisomes had an average diameter of about 52 nanometers and height of about 33 nanometers, by negative staining. The thickness was equivalent to a physocyanin molecule (about 10 nanometers). The molar ratio of allophycocyanin, relative to other phycobiliproteins always remained at about 1:3. Phycobilisomes from red light grown cells and cells grown heterotrophically in darkness were indistinguishable in their pigment composition, polypeptide pattern, and size. Eight polypeptides were resolved in the phycobilin region (17.5 to 23.5 kilodaltons) by isoelectric focusing followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Half of these were invariable, while others were variable in green and red light. It is inferred that phycoerythrin synthesis in green light resulted in a one for one substitution of phycocyanin, thus retaining a constant phycobilisome size. Tolypothrix appears to be one of the best examples of phycobiliprotein regulation with wavelength. By contrast, in Nostoc sp., the decrease in phycoerythrin in red light cells was accompanied by a decrease in phycobilisome size but not a regulated substitution.

  6. Genomic DNA microarray analysis: identification of new genes regulated by light color in the cyanobacterium Fremyella diplosiphon.

    PubMed

    Stowe-Evans, Emily L; Ford, James; Kehoe, David M

    2004-07-01

    Many cyanobacteria use complementary chromatic adaptation to efficiently utilize energy from both green and red regions of the light spectrum during photosynthesis. Although previous studies have shown that acclimation to changing light wavelengths involves many physiological responses, research to date has focused primarily on the expression and regulation of genes that encode proteins of the major photosynthetic light-harvesting antennae, the phycobilisomes. We have used two-dimensional gel electrophoresis and genomic DNA microarrays to expand our understanding of the physiology of acclimation to light color in the cyanobacterium Fremyella diplosiphon. We found that the levels of nearly 80 proteins are altered in cells growing in green versus red light and have cloned and positively identified 17 genes not previously known to be regulated by light color in any species. Among these are homologs of genes present in many bacteria that encode well-studied proteins lacking clearly defined functions, such as tspO, which encodes a tryptophan-rich sensory protein, and homologs of genes encoding proteins of clearly defined function in many species, such as nblA and chlL, encoding phycobilisome degradation and chlorophyll biosynthesis proteins, respectively. Our results suggest novel roles for several of these gene products and highly specialized, unique uses for others.

  7. Discovery of rare and highly toxic microcystins from lichen-associated cyanobacterium Nostoc sp. strain IO-102-I.

    PubMed

    Oksanen, Ilona; Jokela, Jouni; Fewer, David P; Wahlsten, Matti; Rikkinen, Jouko; Sivonen, Kaarina

    2004-10-01

    The production of hepatotoxic cyclic heptapeptides, microcystins, is almost exclusively reported from planktonic cyanobacteria. Here we show that a terrestrial cyanobacterium Nostoc sp. strain IO-102-I isolated from a lichen association produces six different microcystins. Microcystins were identified with liquid chromatography-UV mass spectrometry by their retention times, UV spectra, mass fragmentation, and comparison to microcystins from the aquatic Nostoc sp. strain 152. The dominant microcystin produced by Nostoc sp. strain IO-102-I was the highly toxic [ADMAdda(5)]microcystin-LR, which accounted for ca. 80% of the total microcystins. We assigned a structure of [DMAdda(5)]microcystin-LR and [d-Asp(3),ADMAdda(5)]microcystin-LR and a partial structure of three new [ADMAdda(5)]-XR type of microcystin variants. Interestingly, Nostoc spp. strains IO-102-I and 152 synthesized only the rare ADMAdda and DMAdda subfamilies of microcystin variants. Phylogenetic analyses demonstrated congruence between genes involved directly in microcystin biosynthesis and the 16S rRNA and rpoC1 genes of Nostoc sp. strain IO-102-I. Nostoc sp. strain 152 and the Nostoc sp. strain IO-102-I are distantly related, revealing a sporadic distribution of toxin production in the genus Nostoc. Nostoc sp. strain IO-102-I is closely related to Nostoc punctiforme PCC 73102 and other symbiotic Nostoc strains and most likely belongs to this species. Together, this suggests that other terrestrial and aquatic strains of the genus Nostoc may have retained the genes necessary for microcystin biosynthesis.

  8. [NiFe]-hydrogenase is essential for cyanobacterium Synechocystis sp. PCC 6803 aerobic growth in the dark

    PubMed Central

    De Rosa, Edith; Checchetto, Vanessa; Franchin, Cinzia; Bergantino, Elisabetta; Berto, Paola; Szabò, Ildikò; Giacometti, Giorgio M.; Arrigoni, Giorgio; Costantini, Paola

    2015-01-01

    The cyanobacterium Synechocystis sp. PCC 6803 has a bidirectional [NiFe]-hydrogenase (Hox hydrogenase) which reversibly reduces protons to H2. This enzyme is composed of a hydrogenase domain and a diaphorase moiety, which is distinctly homologous to the NADH input module of mitochondrial respiratory Complex I. Hox hydrogenase physiological function is still unclear, since it is not required for Synechocystis fitness under standard growth conditions. We analyzed the phenotype under prolonged darkness of three Synechocystis knock-out strains, lacking either Hox hydrogenase (ΔHoxE-H) or one of the proteins responsible for the assembly of its NiFe active site (ΔHypA1 and ΔHypB1). We found that Hox hydrogenase is required for Synechocystis growth under this condition, regardless of the functional status of its catalytic site, suggesting an additional role beside hydrogen metabolism. Moreover, quantitative proteomic analyses revealed that the expression levels of several subunits of the respiratory NADPH/plastoquinone oxidoreductase (NDH-1) are reduced when Synechocystis is grown in the dark. Our findings suggest that the Hox hydrogenase could contribute to electron transport regulation when both photosynthetic and respiratory pathways are down-regulated, and provide a possible explanation for the close evolutionary relationship between mitochondrial respiratory Complex I and cyanobacterial [NiFe]-hydrogenases. PMID:26215212

  9. Oscillating behavior of carbohydrate granule formation and dinitrogen fixation in the cyanobacterium Cyanothece sp. strain ATCC 51142

    NASA Technical Reports Server (NTRS)

    Schneegurt, M. A.; Sherman, D. M.; Nayar, S.; Sherman, L. A.; Mitchell, C. A. (Principal Investigator)

    1994-01-01

    It has been shown that some aerobic, unicellular, diazotrophic cyanobacteria temporally separate photosynthetic O2 evolution and oxygen-sensitive N2 fixation. Cyanothece sp. ATCC strain 51142 is an aerobic, unicellular, diazotrophic cyanobacterium that fixes N2 during discrete periods of its cell cycle. When the bacteria are maintained under diurnal light-dark cycles, N2 fixation occurs in the dark. Similar cycling is observed in continuous light, implicating a circadian rhythm. Under N2-fixing conditions, large inclusion granules form between the thylakoid membranes. Maximum granulation, as observed by electron microscopy, occurs before the onset of N2 fixation, and the granules decrease in number during the period of N2 fixation. The granules can be purified from cell homogenates by differential centrifugation. Biochemical analyses of the granules indicate that these structures are primarily carbohydrate, with some protein. Further analyses of the carbohydrate have shown that it is a glucose polymer with some characteristics of glycogen. It is proposed that N2 fixation is driven by energy and reducing power stored in these inclusion granules. Cyanothece sp. strain ATCC 51142 represents an excellent experimental organism for the study of the protective mechanisms of nitrogenase, metabolic events in cyanobacteria under normal and stress conditions, the partitioning of resources between growth and storage, and biological rhythms.

  10. Computational inference and experimental validation of the nitrogen assimilation regulatory network in cyanobacterium Synechococcus sp. WH 8102

    PubMed Central

    Su, Zhengchang; Mao, Fenglou; Dam, Phuongan; Wu, Hongwei; Olman, Victor; Paulsen, Ian T.; Palenik, Brian; Xu, Ying

    2006-01-01

    Deciphering the regulatory networks encoded in the genome of an organism represents one of the most interesting and challenging tasks in the post-genome sequencing era. As an example of this problem, we have predicted a detailed model for the nitrogen assimilation network in cyanobacterium Synechococcus sp. WH 8102 (WH8102) using a computational protocol based on comparative genomics analysis and mining experimental data from related organisms that are relatively well studied. This computational model is in excellent agreement with the microarray gene expression data collected under ammonium-rich versus nitrate-rich growth conditions, suggesting that our computational protocol is capable of predicting biological pathways/networks with high accuracy. We then refined the computational model using the microarray data, and proposed a new model for the nitrogen assimilation network in WH8102. An intriguing discovery from this study is that nitrogen assimilation affects the expression of many genes involved in photosynthesis, suggesting a tight coordination between nitrogen assimilation and photosynthesis processes. Moreover, for some of these genes, this coordination is probably mediated by NtcA through the canonical NtcA promoters in their regulatory regions. PMID:16473855

  11. Construction of new synthetic biology tools for the control of gene expression in the cyanobacterium Synechococcus sp. strain PCC 7002.

    PubMed

    Zess, Erin K; Begemann, Matthew B; Pfleger, Brian F

    2016-02-01

    Predictive control of gene expression is an essential tool for developing synthetic biological systems. The current toolbox for controlling gene expression in cyanobacteria is a barrier to more in-depth genetic analysis and manipulation. Towards relieving this bottleneck, this work describes the use of synthetic biology to construct an anhydrotetracycline-based induction system and adapt a trans-acting small RNA (sRNA) system for use in the cyanobacterium Synechococcus sp. strain PCC 7002. An anhydrotetracycline-inducible promoter was developed to maximize intrinsic strength and dynamic range. The resulting construct, PEZtet , exhibited tight repression and a maximum 32-fold induction upon addition of anhydrotetracycline. Additionally, a sRNA system based on the Escherichia coli IS10 RNA-IN/OUT regulator was adapted for use in Synechococcus sp. strain PCC 7002. This system exhibited 70% attenuation of target gene expression, providing a demonstration of the use of sRNAs for differential gene expression in cyanobacteria. These systems were combined to produce an inducible sRNA system, which demonstrated 59% attenuation of target gene expression. Lastly, the role of Hfq, a critical component of sRNA systems in E. coli, was investigated. Genetic studies showed that the Hfq homolog in Synechococcus sp. strain PCC 7002 did not impact repression by the engineered sRNA system. In summary, this work describes new synthetic biology tools that can be applied to physiological studies, metabolic engineering, or sRNA platforms in Synechococcus sp. strain PCC 7002.

  12. Soft x-ray imaging of intracellular granules of filamentous cyanobacterium generating musty smell in Lake Biwa

    NASA Astrophysics Data System (ADS)

    Takemoto, K.; Mizuta, G.; Yamamoto, A.; Yoshimura, M.; Ichise, S.; Namba, H.; Kihara, H.

    2013-10-01

    A planktonic blue-green algae, which are currently identified as Phormidium tenue, was observed by a soft x-ray microscopy (XM) for comparing a musty smell generating green strain (PTG) and a non-smell brown strain (PTB). By XM, cells were clearly imaged, and several intracellular granules which could not be observed under a light microscope were visualized. The diameter of granules was about 0.5-1 μm, and one or a few granules were seen in a cell. XM analyses showed that width of cells and sizes of intracellular granules were quite different between PTG and PTB strains. To study the granules observed by XM, transmission in more detail, transmission electron microscopy (TEM) and indirect fluorescent-antibody technique (IFA) were applied. By TEM, carboxysomes, thylakoids and polyphosphate granules were observed. IFA showed the presence of carboxysomes. Results lead to the conclusion that intracellular granules observed under XM are carboxysomes or polyphosphate granules. These results demonstrate that soft XM is effective for analyzing fine structures of small organisms such as cyanobacterium, and for discriminating the strains which generates musty smells from others.

  13. Heterocyst-specific flavodiiron protein Flv3B enables oxic diazotrophic growth of the filamentous cyanobacterium Anabaena sp. PCC 7120.

    PubMed

    Ermakova, Maria; Battchikova, Natalia; Richaud, Pierre; Leino, Hannu; Kosourov, Sergey; Isojärvi, Janne; Peltier, Gilles; Flores, Enrique; Cournac, Laurent; Allahverdiyeva, Yagut; Aro, Eva-Mari

    2014-07-29

    Flavodiiron proteins are known to have crucial and specific roles in photoprotection of photosystems I and II in cyanobacteria. The filamentous, heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 contains, besides the four flavodiiron proteins Flv1A, Flv2, Flv3A, and Flv4 present in vegetative cells, two heterocyst-specific flavodiiron proteins, Flv1B and Flv3B. Here, we demonstrate that Flv3B is responsible for light-induced O2 uptake in heterocysts, and that the absence of the Flv3B protein severely compromises the growth of filaments in oxic, but not in microoxic, conditions. It is further demonstrated that Flv3B-mediated photosynthetic O2 uptake has a distinct role in heterocysts which cannot be substituted by respiratory O2 uptake in the protection of nitrogenase from oxidative damage and, thus, in an efficient provision of nitrogen to filaments. In line with this conclusion, the Δflv3B strain has reduced amounts of nitrogenase NifHDK subunits and shows multiple symptoms of nitrogen deficiency in the filaments. The apparent imbalance of cytosolic redox state in Δflv3B heterocysts also has a pronounced influence on the amounts of different transcripts and proteins. Therefore, an O2-related mechanism for control of gene expression is suggested to take place in heterocysts. PMID:25002499

  14. Requirement of Fra proteins for communication channels between cells in the filamentous nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120.

    PubMed

    Omairi-Nasser, Amin; Mariscal, Vicente; Austin, Jotham R; Haselkorn, Robert

    2015-08-11

    The filamentous nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120 differentiates specialized cells, heterocysts, that fix atmospheric nitrogen and transfer the fixed nitrogen to adjacent vegetative cells. Reciprocally, vegetative cells transfer fixed carbon to heterocysts. Several routes have been described for metabolite exchange within the filament, one of which involves communicating channels that penetrate the septum between adjacent cells. Several fra gene mutants were isolated 25 y ago on the basis of their phenotypes: inability to fix nitrogen and fragmentation of filaments upon transfer from N+ to N- media. Cryopreservation combined with electron tomography were used to investigate the role of three fra gene products in channel formation. FraC and FraG are clearly involved in channel formation, whereas FraD has a minor part. Additionally, FraG was located close to the cytoplasmic membrane and in the heterocyst neck, using immunogold labeling with antibody raised to the N-terminal domain of the FraG protein. PMID:26216997

  15. Amino Acid Transporters and Release of Hydrophobic Amino Acids in the Heterocyst-Forming Cyanobacterium Anabaena sp. Strain PCC 7120.

    PubMed

    Pernil, Rafael; Picossi, Silvia; Herrero, Antonia; Flores, Enrique; Mariscal, Vicente

    2015-01-01

    Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium that can use inorganic compounds such as nitrate or ammonium as nitrogen sources. In the absence of combined nitrogen, it can fix N2 in differentiated cells called heterocysts. Anabaena also shows substantial activities of amino acid uptake, and three ABC-type transporters for amino acids have been previously characterized. Seven new loci encoding predicted amino acid transporters were identified in the Anabaena genomic sequence and inactivated. Two of them were involved in amino acid uptake. Locus alr2535-alr2541 encodes the elements of a hydrophobic amino acid ABC-type transporter that is mainly involved in the uptake of glycine. ORF all0342 encodes a putative transporter from the dicarboxylate/amino acid:cation symporter (DAACS) family whose inactivation resulted in an increased uptake of a broad range of amino acids. An assay to study amino acid release from Anabaena filaments to the external medium was set up. Net release of the alanine analogue α-aminoisobutyric acid (AIB) was observed when transport system N-I (a hydrophobic amino acid ABC-type transporter) was engaged in the uptake of a specific substrate. The rate of AIB release was directly proportional to the intracellular AIB concentration, suggesting leakage from the cells by diffusion. PMID:25915115

  16. The first evidence of paralytic shellfish toxins in the fresh water cyanobacterium Cylindrospermopsis raciborskii, isolated from Brazil.

    PubMed

    Lagos, N; Onodera, H; Zagatto, P A; Andrinolo, D; Azevedo, S M; Oshima, Y

    1999-10-01

    The blooms of toxic cyanobacteria (blue-green algae) are causing problems in many countries. During a screening of toxic freshwater cyanobacteria in Brazil, three strains isolated from the State of Sao Paulo were found toxic by the mouse bioassay. They all were identified as Cylindrospermopsis raciborskii by a close morphological examination. Extracts of cultured cells caused acute death to mice when injected intraperitoneally after developing neurotoxic symptoms which resembled to those caused by paralytic shellfish toxins. The analysis of the sample by HPLC-FLD postcolumn derivatization method for paralytic shellfish toxins resulted in the detection of several saxitoxin analogs. To avoid being misled by false peaks, the sample was reanalyzed after purification and also under the different postcolumn derivatizing conditions. Finally, the newly developed LC-MS method for paralytic shellfish toxins was applied to unambiguously identify the toxins. One isolate produced neosaxitoxin predominantly with saxitoxin as a minor component. The other two showed identical toxin profiles containing saxitoxin and gonyautoxins 2/3 isomers in the ratio of 1:9. This is the first evidence of paralytic shellfish toxins in this species and also the occurrence of the toxin producing cyanobacterium in South American countries. PMID:10414862

  17. Acute Exposure to Microcystin-Producing Cyanobacterium Microcystis aeruginosa Alters Adult Zebrafish (Danio rerio) Swimming Performance Parameters.

    PubMed

    Kist, Luiza Wilges; Piato, Angelo Luis; da Rosa, João Gabriel Santos; Koakoski, Gessi; Barcellos, Leonardo José Gil; Yunes, João Sarkis; Bonan, Carla Denise; Bogo, Maurício Reis

    2011-01-01

    Microcystins (MCs) are toxins produced by cyanobacteria (blue-green algae), primarily Microcystis aeruginosa, forming water blooms worldwide. When an organism is exposed to environmental perturbations, alterations in normal behavioral patterns occur. Behavioral repertoire represents the consequence of a diversity of physiological and biochemical alterations. In this study, we assessed behavioral patterns and whole-body cortisol levels of adult zebrafish (Danio rerio) exposed to cell culture of the microcystin-producing cyanobacterium M. aeruginosa (MC-LR, strain RST9501). MC-LR exposure (100 μg/L) decreased by 63% the distance traveled and increased threefold the immobility time when compared to the control group. Interestingly, no significant alterations in the number of line crossings were found at the same MC-LR concentration and time of exposure. When animals were exposed to 50 and 100 μg/L, MC-LR promoted a significant increase (around 93%) in the time spent in the bottom portion of the tank, suggesting an anxiogenic effect. The results also showed that none of the MC-LR concentrations tested promoted significant alterations in absolute turn angle, path efficiency, social behavior, or whole-body cortisol level. These findings indicate that behavior is susceptible to MC-LR exposure and provide evidence for a better understanding of the ecological consequences of toxic algal blooms. PMID:22253623

  18. Chlorophyll f and chlorophyll d are produced in the cyanobacterium Chlorogloeopsis fritschii when cultured under natural light and near-infrared radiation.

    PubMed

    Airs, R L; Temperton, B; Sambles, C; Farnham, G; Skill, S C; Llewellyn, C A

    2014-10-16

    We report production of chlorophyll f and chlorophyll d in the cyanobacterium Chlorogloeopsis fritschii cultured under near-infrared and natural light conditions. C. fritschii produced chlorophyll f and chlorophyll d when cultured under natural light to a high culture density in a 20 L bubble column photobioreactor. In the laboratory, the ratio of chlorophyll f to chlorophyll a changed from 1:15 under near-infrared, to an undetectable level of chlorophyll f under artificial white light. The results provide support that chlorophylls f and d are both red-light inducible chlorophylls in C. fritschii.

  19. High radiation and desiccation tolerance of nitrogen-fixing cultures of the cyanobacterium Anabaena sp. strain PCC 7120 emanates from genome/proteome repair capabilities.

    PubMed

    Singh, Harinder; Anurag, Kirti; Apte, Shree Kumar

    2013-10-12

    The filamentous nitrogen-fixing cyanobacterium, Anabaena sp. strain PCC 7120 was found to tolerate very high doses of (60)Co-gamma radiation or prolonged desiccation. Post-stress, cells remained intact and revived all the vital functions. A remarkable capacity to repair highly disintegrated genome and recycle the damaged proteome appeared to underlie such high radioresistance and desiccation tolerance. The close similarity observed between the cellular response to irradiation or desiccation stress lends strong support to the notion that tolerance to these stresses may involve similar mechanisms.

  20. Global Proteomics Reveal An Atypical Strategy for Carbon/Nitrogen Assimilation by a Cyanobacterium Under Diverse Environmental Perturbations

    SciTech Connect

    Wegener, Kimberly M.; Singh, Abhay K.; Jacobs, Jon M.; Elvitigala, Thanura R.; Welsh, Eric A.; Keren, Nir S.; Gritsenko, Marina A.; Ghosh, Bijoy K.; Camp, David G.; Smith, Richard D.; Pakrasi, Himadri B.

    2010-12-01

    Cyanobacteria, the only prokaryotes capable of oxygenic photosynthesis, are present in diverse ecological niches and play crucial roles in global carbon and nitrogen cycles. To proliferate in nature, cyanobacteria utilize a host of stress responses to accommodate periodic changes in environmental conditions. A detailed knowledge of the composition of, as well as the dynamic changes in, the proteome is necessary to gain fundamental insights into such stress responses. Toward this goal, we have performed a largescale proteomic analysis of the widely studied model cyanobacterium Synechocystis sp. PCC 6803 under 33 different environmental conditions. The resulting high-quality dataset consists of 22,318 unique peptides corresponding to 1,955 proteins, a coverage of 53% of the predicted proteome. Quantitative determination of protein abundances has led to the identification of 1,198 differentially regulated proteins. Notably, our analysis revealed that a common stress response under various environmental perturbations, irrespective of amplitude and duration, is the activation of atypical pathways for the acquisition of carbon and nitrogen from urea and arginine. In particular, arginine is catabolized via putrescine to produce succinate and glutamate, sources of carbon and nitrogen, respectively. This study provides the most comprehensive functional and quantitative analysis of the Synechocystis proteome to date, and shows that a significant stress response of cyanobacteria involves an uncommon mode of acquisition of carbon and nitrogen. Oxygenic phototrophic prokaryotes, the progenitors of the chloroplast, are crucial to global oxygen production and worldwide carbon and nitrogen cycles. These microalgae are robust organisms capable carbon neutral biofuel production. Synechocystis sp. PCC 6803 has historically been a model cyanobacterium for photosynthetic research and is emerging as a promising biofuel platform. Cellular responses are severely modified by environmental

  1. Elevated growth temperature can enhance photosystem I trimer formation and affects xanthophyll biosynthesis in Cyanobacterium Synechocystis sp. PCC6803 cells.

    PubMed

    Kłodawska, Kinga; Kovács, László; Várkonyi, Zsuzsanna; Kis, Mihály; Sozer, Özge; Laczkó-Dobos, Hajnalka; Kóbori, Ottilia; Domonkos, Ildikó; Strzałka, Kazimierz; Gombos, Zoltán; Malec, Przemysław

    2015-03-01

    In the thylakoid membranes of the mesophilic cyanobacterium Synechocystis PCC6803, PSI reaction centers (RCs) are organized as monomers and trimers. PsaL, a 16 kDa hydrophobic protein, a subunit of the PSI RC, was previously identified as crucial for the formation of PSI trimers. In this work, the physiological effects accompanied by PSI oligomerization were studied using a PsaL-deficient mutant (ΔpsaL), not able to form PSI trimers, grown at various temperatures. We demonstrate that in wild-type Synechocystis, the monomer to trimer ratio depends on the growth temperature. The inactivation of the psaL gene in Synechocystis grown phototropically at 30°C induces profound morphological changes, including the accumulation of glycogen granules localized in the cytoplasm, resulting in the separation of particular thylakoid layers. The carotenoid composition in ΔpsaL shows that PSI monomerization leads to an increased accumulation of myxoxantophyll, zeaxanthin and echinenone irrespective of the temperature conditions. These xanthophylls are formed at the expense of β-carotene. The measured H2O→CO2 oxygen evolution rates in the ΔpsaL mutant are higher than those observed in the wild type, irrespective of the growth temperature. Moreover, circular dichroism spectroscopy in the visible range reveals that a peak attributable to long-wavelength-absorbing carotenoids is apparently enhanced in the trimer-accumulating wild-type cells. These results suggest that specific carotenoids are accompanied by the accumulation of PSI oligomers and play a role in the formation of PSI oligomer structure. PMID:25520404

  2. Physiology, Fe(II) oxidation, and Fe mineral formation by a marine planktonic cyanobacterium grown under ferruginous conditions

    NASA Astrophysics Data System (ADS)

    Swanner, Elizabeth; Wu, Wenfang; Hao, Likai; Wuestner, Marina; Obst, Martin; Moran, Dawn; McIlvin, Matthew; Saito, Mak; Kappler, Andreas

    2015-10-01

    Evidence for Fe(II) oxidation and deposition of Fe(III)-bearing minerals from anoxic or redox-stratified Precambrian oceans has received support from decades of sedimentological and geochemical investigation of Banded Iron Formations (BIF). While the exact mechanisms of Fe(II) oxidation remains equivocal, reaction with O2 in the marine water column, produced by cyanobacteria or early oxygenic phototrophs, was likely. In order to understand the role of cyanobacteria in the deposition of Fe(III) minerals to BIF, we must first know how planktonic marine cyanobacteria respond to ferruginous (anoxic and Fe(II)-rich) waters in terms of growth, Fe uptake and homeostasis, and Fe mineral formation. We therefore grew the common marine cyanobacterium Synechococcus PCC 7002 in closed bottles that began anoxic, and contained Fe(II) concentrations that span the range of possible concentrations in Precambrian seawater. These results, along with cell suspension experiments, indicate that Fe(II) is likely oxidized by this strain via chemical oxidation with oxygen produced during photosynthesis, and not via any direct enzymatic or photosynthetic pathway. Imaging of the cell-mineral aggregates with scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) are consistent with extracellular precipitation of Fe(III) (oxyhydr)oxide minerals, but that >10% of Fe(III) sorbs to cell surfaces rather than precipitating. Proteomic experiments support the role of reactive oxygen species (ROS) in Fe(II) toxicity to Synechococcus PCC 7002. The proteome expressed under low Fe conditions included multiple siderophore biosynthesis and siderophore and Fe transporter proteins, but most siderophores are not expressed during growth with Fe(II). These results provide a mechanistic and quantitative framework for evaluating the geochemical consequences of perhaps life’s greatest metabolic innovation, i.e. the evolution and activity of oxygenic photosynthesis, in ferruginous

  3. Net light-induced oxygen evolution in photosystem I deletion mutants of the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Wang, Qing Jun; Singh, Abhay; Li, Hong; Nedbal, Ladislav; Sherman, Louis A; Govindjee; Whitmarsh, John

    2012-05-01

    Oxygenic photosynthesis in cyanobacteria, algae, and plants requires photosystem II (PSII) to extract electrons from H(2)O and depends on photosystem I (PSI) to reduce NADP(+). Here we demonstrate that mixotrophically-grown mutants of the cyanobacterium Synechocystis sp. PCC 6803 that lack PSI (ΔPSI) are capable of net light-induced O(2) evolution in vivo. The net light-induced O(2) evolution requires glucose and can be sustained for more than 30 min. Utilizing electron transport inhibitors and chlorophyll a fluorescence measurements, we show that in these mutants PSII is the source of the light-induced O(2) evolution, and that the plastoquinone pool is reduced by PSII and subsequently oxidized by an unidentified electron acceptor that does not involve the plastoquinol oxidase site of the cytochrome b(6)f complex. Moreover, both O(2) evolution and chlorophyll a fluorescence kinetics of the ΔPSI mutants are highly sensitive to KCN, indicating the involvement of a KCN-sensitive enzyme(s). Experiments using (14)C-labeled bicarbonate show that the ΔPSI mutants assimilate more CO(2) in the light compared to the dark. However, the rate of the light-minus-dark CO(2) assimilation accounts for just over half of the net light-induced O(2) evolution rate, indicating the involvement of unidentified terminal electron acceptors. Based on these results we suggest that O(2) evolution in ΔPSI cells can be sustained by an alternative electron transport pathway that results in CO(2) assimilation and that includes PSII, the platoquinone pool, and a KCN-sensitive enzyme.

  4. Identification of OmpR-family response regulators interacting with thioredoxin in the Cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Kadowaki, Taro; Nishiyama, Yoshitaka; Hisabori, Toru; Hihara, Yukako

    2015-01-01

    The redox state of the photosynthetic electron transport chain is known to act as a signal to regulate the transcription of key genes involved in the acclimation responses to environmental changes. We hypothesized that the protein thioredoxin (Trx) acts as a mediator connecting the redox state of the photosynthetic electron transport chain and transcriptional regulation, and established a screening system to identify transcription factors (TFs) that interact with Trx. His-tagged TFs and S-tagged mutated form of Trx, TrxMC35S, whose active site cysteine 35 was substituted with serine to trap the target interacting protein, were co-expressed in E. coli cells and Trx-TF complexes were detected by immuno-blotting analysis. We examined the interaction between Trx and ten OmpR family TFs encoded in the chromosome of the cyanobacterium Synechocystis sp. PCC 6803 (S.6803). Although there is a highly conserved cysteine residue in the receiver domain of all OmpR family TFs, only three, RpaA (Slr0115), RpaB (Slr0947) and ManR (Slr1837), were identified as putative Trx targets [corrected].The recombinant forms of wild-type TrxM, RpaA, RpaB and ManR proteins from S.6803 were purified following over-expression in E. coli and their interaction was further assessed by monitoring changes in the number of cysteine residues with free thiol groups. An increase in the number of free thiols was observed after incubation of the oxidized TFs with Trx, indicating the reduction of cysteine residues as a consequence of interaction with Trx. Our results suggest, for the first time, the possible regulation of OmpR family TFs through the supply of reducing equivalents from Trx, as well as through the phospho-transfer from its cognate sensor histidine kinase. PMID:25774906

  5. Salinity tolerance of Picochlorum atomus and the use of salinity for contamination control by the freshwater cyanobacterium Pseudanabaena limnetica.

    PubMed

    von Alvensleben, Nicolas; Stookey, Katherine; Magnusson, Marie; Heimann, Kirsten

    2013-01-01

    Microalgae are ideal candidates for waste-gas and -water remediation. However, salinity often varies between different sites. A cosmopolitan microalga with large salinity tolerance and consistent biochemical profiles would be ideal for standardised cultivation across various remediation sites. The aims of this study were to determine the effects of salinity on Picochlorum atomus growth, biomass productivity, nutrient uptake and biochemical profiles. To determine if target end-products could be manipulated, the effects of 4-day nutrient limitation were also determined. Culture salinity had no effect on growth, biomass productivity, phosphate, nitrate and total nitrogen uptake at 2, 8, 18, 28 and 36 ppt. 11 ppt, however, initiated a significantly higher total nitrogen uptake. While salinity had only minor effects on biochemical composition, nutrient depletion was a major driver for changes in biomass quality, leading to significant increases in total lipid, fatty acid and carbohydrate quantities. Fatty acid composition was also significantly affected by nutrient depletion, with an increased proportion of saturated and mono-unsaturated fatty acids. Having established that P. atomus is a euryhaline microalga, the effects of culture salinity on the development of the freshwater cyanobacterial contaminant Pseudanabaena limnetica were determined. Salinity at 28 and 36 ppt significantly inhibited establishment of P. limnetica in P. atomus cultures. In conclusion, P. atomus can be deployed for bioremediation at sites with highly variable salinities without effects on end-product potential. Nutrient status critically affected biochemical profiles--an important consideration for end-product development by microalgal industries. 28 and 36 ppt slow the establishment of the freshwater cyanobacterium P. limnetica, allowing for harvest of low contaminant containing biomass. PMID:23667639

  6. Expression of Human Carbonic Anhydrase in the Cyanobacterium Synechococcus PCC7942 Creates a High CO2-Requiring Phenotype 1

    PubMed Central

    Price, G. D.; Badger, M. R.

    1989-01-01

    Active human carbonic anhydrase II (HCAII) protein was expressed in the cyanobacterium Synechococcus PCC7942 by means of transformation with the bidirectional expression vector, pCA. This expression was driven by the bacterial Tac promoter and was regulated by the IacIQ repressor protein, which was expressed from the same plasmid. Expression levels reached values of around 0.3% of total cell protein and this protein appeared to be entirely soluble in nature and located within the cytosol of the cell. The expression of this protein has dramatic effects on the photosynthetic physiology of the cell. Induction of expression of carbonic anhydrase (CA) activity in both high dissolved inorganic carbon (Ci) and low Ci grown cells leads the creation of a high Ci requiring phenotype causing: (a) a dramatic increase in the K0.5 (Ci) for photosynthesis, (b) a loss of the ability to accumulate internal Ci, and (c) a decrease in the lag between the initial Ci accumulation following illumination and the efflux of CO2 from the cells. In addition, the effects of the expressed CA can largely be reversed by the carbonic anhydrase inhibitor ethoxyzolamide. As a result of the above findings, it is concluded that the CO2 concentrating mechanism in Synechococcus PCC7942 is largely dependent on (a) the absence of CA activity from the cytosol, and (b) the specific localization of CA activity in the carboxysome. A theoretical model of photosynthesis and Ci accumulation is developed in which the carboxysome plays a central role as both the site of CO2 generation from HCO3− and a resistance barrier to CO2 efflux from the cell. There is good qualitative agreement between this model and the measured physiological effects of expressed cytosolic CA in Synechococcus cells. Images Figure 7 PMID:16667062

  7. Ammonium Excretion by an l-Methionine-dl-Sulfoximine-Resistant Mutant of the Rice Field Cyanobacterium Anabaena siamensis

    PubMed Central

    Thomas, Selwin P.; Zaritsky, Arieh; Boussiba, Sammy

    1990-01-01

    An ammonium-excreting mutant (SS1) of the rice field nitrogen-fixing cyanobacterium Anabaena siamensis was isolated after ethyl methanesulfonate mutagenesis by selection on 500 μM l-methionine-dl-sulfoximine. SS1 grew in the presence and absence of l-methionine-dl-sulfoximine at a rate comparable to that of the wild-type strain, with a doubling time of 5.6 h. The rate of ammonium release by SS1 depended on cell density; it peaked at the 12th hour of growth with 8.7 μmol mg of chlorophyll−1 h−1 (at a chlorophyll concentration of 5 μg ml−1) and slowed down to almost nil at the fourth day of growth. A similar pattern of release by immobilized SS1 was observed between 12 to 20 h after loading alginate beads in packed-bed reactors at the rate of 11.6 μmol mg of chlorophyll−1 h−1. The rate was later reduced significantly due to the fast growth of SS1 on the substrate. Prolonged release of ammonium at the peak level was achieved only by maintaining SS1 under continuous cultivation at low chlorophyll levels (5 to 7 μg ml−1). Under these conditions, nitrogen fixation in the mutant was 30% higher than that in its parent and glutamine synthetase activity was less by 50%. Immunoblot analysis revealed that SS1 and its parent have similar quantities of glutamine synthetase protein under ammonium excretion conditions. In addition, a protein with a molecular weight of about 30,000 seems to have been lost, as seen by electrophoretic separation of total proteins from SS1. Images PMID:16348353

  8. Hydrogen production by the unicellular, diazotrophic cyanobacterium Cyanothece sp. strain ATCC 51142 under conditions of continuous light.

    PubMed

    Min, Hongtao; Sherman, Louis A

    2010-07-01

    We report on the hydrogen production properties of the unicellular, diazotrophic cyanobacterium Cyanothece sp. strain ATCC 51142. This organism has a versatile metabolism and can grow in the presence or absence of combined nitrogen and can grow photosynthetically or mixotrophically and heterotrophically in the presence of glycerol. The strain produces a bidirectional hydrogenase (encoded by the hox genes), an uptake hydrogenase (hupLS), and nitrogenase (nifHDK). We demonstrated hydrogen production by both the hydrogenase and the nitrogenase under appropriate metabolic conditions. The highest rates of hydrogen production were produced under nitrogen-fixing conditions when cells were grown and incubated under continuous light conditions, in either the presence or absence of glycerol. Under such nitrogen-fixing conditions, we have achieved rates of 300 micromol H(2)/mg chloramphenicol (Chl)/hr during the first 24 h of incubation. The levels of H(2) measured were dependent upon the incubation conditions, such as sparging with argon, which generated anaerobic conditions. We demonstrated that the same conditions led to high levels of H(2) production and N(2) fixation, indicating that low-oxygen conditions favor nitrogenase activity for both processes. The levels of hydrogen produced by the hydrogenase are much lower, typically 5 to 10 micromol H(2)/mg Chl/hr. Hydrogenase activity was dependent upon electron transport through photosystem II (PS II), whereas nitrogenase activity was more dependent on PS I, as well as on respiration. Although cells do not double under the incubation conditions when sparged with argon to provide a low-oxygen environment, the cells are metabolically active, and hydrogen production can be inhibited by the addition of chloramphenicol to inhibit protein synthesis.

  9. Cryo-electron tomography reveals the comparative three-dimensional architecture of Prochlorococcus, a globally important marine cyanobacterium.

    PubMed

    Ting, Claire S; Hsieh, Chyongere; Sundararaman, Sesh; Mannella, Carmen; Marko, Michael

    2007-06-01

    In an age of comparative microbial genomics, knowledge of the near-native architecture of microorganisms is essential for achieving an integrative understanding of physiology and function. We characterized and compared the three-dimensional architecture of the ecologically important cyanobacterium Prochlorococcus in a near-native state using cryo-electron tomography and found that closely related strains have diverged substantially in cellular organization and structure. By visualizing native, hydrated structures within cells, we discovered that the MED4 strain, which possesses one of the smallest genomes (1.66 Mbp) of any known photosynthetic organism, has evolved a comparatively streamlined cellular architecture. This strain possesses a smaller cell volume, an attenuated cell wall, and less extensive intracytoplasmic (photosynthetic) membrane system compared to the more deeply branched MIT9313 strain. Comparative genomic analyses indicate that differences have evolved in key structural genes, including those encoding enzymes involved in cell wall peptidoglycan biosynthesis. Although both strains possess carboxysomes that are polygonal and cluster in the central cytoplasm, the carboxysomes of MED4 are smaller. A streamlined cellular structure could be advantageous to microorganisms thriving in the low-nutrient conditions characteristic of large regions of the open ocean and thus have consequences for ecological niche differentiation. Through cryo-electron tomography we visualized, for the first time, the three-dimensional structure of the extensive network of photosynthetic lamellae within Prochlorococcus and the potential pathways for intracellular and intermembrane movement of molecules. Comparative information on the near-native structure of microorganisms is an important and necessary component of exploring microbial diversity and understanding its consequences for function and ecology. PMID:17449628

  10. Redox-dependent Ligand Switching in a Sensory Heme-binding GAF Domain of the Cyanobacterium Nostoc sp. PCC7120*

    PubMed Central

    Tang, Kun; Knipp, Markus; Liu, Bing-Bing; Cox, Nicholas; Stabel, Robert; He, Qi; Zhou, Ming; Scheer, Hugo; Zhao, Kai-Hong; Gärtner, Wolfgang

    2015-01-01

    The genome of the cyanobacterium Nostoc sp. PCC7120 carries three genes (all4978, all7016, and alr7522) encoding putative heme-binding GAF (cGMP-specific phosphodiesterases, adenylyl cyclases, and FhlA) proteins that were annotated as transcriptional regulators. They are composed of an N-terminal cofactor domain and a C-terminal helix-turn-helix motif. All4978 showed the highest affinity for protoheme binding. The heme binding capability of All7016 was moderate, and Alr7522 did not bind heme at all. The “as isolated” form of All4978, identified by Soret band (λmax = 427 nm), was assigned by electronic absorption, EPR, and resonance Raman spectroscopy as a hexa-coordinated low spin FeIII heme with a distal cysteine ligand (absorption of δ-band around 360 nm). The protoheme cofactor is noncovalently incorporated. Reduction of the heme could be accomplished by chemically using sodium dithionite and electrospectrochemically; this latter method yielded remarkably low midpoint potentials of −445 and −453 mV (following Soret and α-band absorption changes, respectively). The reduced form of the heme (FeII state) binds both NO and CO. Cysteine coordination of the as isolated FeIII protein is unambiguous, but interestingly, the reduced heme instead displays spectral features indicative of histidine coordination. Cys-His ligand switches have been reported as putative signaling mechanisms in other heme-binding proteins; however, these novel cyanobacterial proteins are the first where such a ligand-switch mechanism has been observed in a GAF domain. DNA binding of the helix-turn-helix domain was investigated using a DNA sequence motif from its own promoter region. Formation of a protein-DNA complex preferentially formed in ferric state of the protein. PMID:26063806

  11. Effects of UV-B radiation and periodic desiccation on the morphogenesis of the edible terrestrial cyanobacterium Nostoc flagelliforme.

    PubMed

    Feng, Yan-Na; Zhang, Zhong-Chun; Feng, Jun-Li; Qiu, Bao-Sheng

    2012-10-01

    The terrestrial cyanobacterium Nostoc flagelliforme Berk. et M. A. Curtis has been a popular food and herbal ingredient for hundreds of years. To meet great market demand and protect the local ecosystem, for decades researchers have tried to cultivate N. flagelliforme but have failed to get macroscopic filamentous thalli. In this study, single trichomes with 50 to 200 vegetative cells were induced from free-living cells by low light and used to investigate the morphogenesis of N. flagelliforme under low UV-B radiation and periodic desiccation. Low-fluence-rate UV-B (0.1 W m(-2)) did not inhibit trichome growth; however, it significantly increased the synthesis of extracellular polysaccharides and mycosporine-like amino acids and promoted sheath formation outside the trichomes. Under low UV-B radiation, single trichomes developed into filamentous thalli more than 1 cm long after 28 days of cultivation, most of which grew separately in liquid BG11 medium. With periodic desiccation treatment, the single trichomes formed flat or banded thalli that grew up to 2 cm long after 3 months on solid BG11 medium. When trichomes were cultivated on solid BG11 medium with alternate treatments of low UV-B and periodic desiccation, dark and scraggly filamentous thalli that grew up to about 3 cm in length after 40 days were obtained. In addition, the cultivation of trichomes on nitrogen-deficient solid BG11 medium (BG11(0)) suggested that nitrogen availability could affect the color and lubricity of newly developed thalli. This study provides promising techniques for artificial cultivation of N. flagelliforme in the future.

  12. Influence of Various Levels of Iron and Other Abiotic Factors on Siderophorogenesis in Paddy Field Cyanobacterium Anabaena oryzae.

    PubMed

    Singh, Anumeha; Mishra, Arun Kumar

    2015-05-01

    Siderophore production in Anabaena oryzae was investigated under the influence of various levels of iron and other abiotic factors such as pH, temperature, light and different nitrogen sources. Optimization of culture conditions under controlled mechanisms of these abiotic factors lead to the siderophore production in significant amount. Under iron-starved condition, A. oryzae extracellularly releases 89.17% hydroxymate-type siderophore. Slightly alkaline pH and 30 °C temperature was found stimulatory for the cyanobacterial growth and siderophorogenesis (88.52% SU and 83.87% SU, respectively). Excess iron loading had a negative impact on siderophore production along with the alterations in the morphology and growth. Further, scanning electron microphotographs signified that higher concentrations of iron lead to complete damage of the cells and alterations in membrane proteins possibly transporters responsible for exchange of siderophore complex from environment to the cell. SDS-PAGE analysis of whole cell proteins showed overexpression of low molecular weight proteins ranges between 20.1 to 29.0 kDa up to 100-μM iron concentrations. These polypeptides/proteins might be involved in maintaining iron homeostasis by regulating siderophore production. Results suggest that lower concentrations of iron ≤ 50 μM along with other abiotic factors are stimulatory, whereas higher concentrations (>50 μM) are toxic. Data further suggested that cyanobacterium A. oryzae can serve as a potential biofertilizer especially in iron-rich soil through sequestration by the power of natural Fe(III)-siderophore complex formation.

  13. Characterization of five putative aspartate aminotransferase genes in the N2-fixing heterocystous cyanobacterium Anabaena sp. strain PCC 7120.

    PubMed

    Xu, Xinyi; Gu, Liping; He, Ping; Zhou, Ruanbao

    2015-06-01

    Aspartate and glutamate are two key amino acids used in biosynthesis of many amino acids that play vital role in cellular metabolism. Aspartate aminotransferases (AspATs) are required for channelling nitrogen (N(2)) between Glu and Asp in all life forms. Biochemical and genetic characterization of AspATs have been lacking in N(2)-fixing cyanobacteria. In this report, five putative AspAT genes (alr1039, all2340, alr2765, all4327 and alr4853) were identified in the N(2)-fixing heterocystous cyanobacterium Anabaena sp. PCC 7120. Five recombinant C-terminal hexahistidine-tagged AspATs (AspAT-H(6)) were overexpressed in Escherichia coli and purified to homogeneity. Biochemical analysis demonstrated that these five putative AspATs have authentic AspAT activity in vitro using aspartate as an amino donor. However, the enzymic activities of the five AspATs differed in vitro. Alr4853-H(6) showed the highest AspAT activity, while the enzymic activity for the other four AspATs ranged from 6.5 to 53.7 % activity compared to Alr4853 (100 %). Genetic characterization of the five AspAT genes was also performed by inactivating each individual gene. All of the five AspAT knockout mutants exhibited reduced diazotrophic growth, and alr4853 was further identified to be a Fox gene (requiring fixed N(2) for growth in the presence of oxygen). Four out of five P(aspAT)-gfp transcriptional fusions were constitutively expressed in both diazotrophic and nitrate-dependent growth conditions. Quantitative reverse transcriptase PCR showed that alr4853 expression was increased by 2.3-fold after 24 h of N(2) deprivation. Taken together, these findings add to our understanding of the role of AspATs in N(2)-fixing within heterocystous cyanobacteria.

  14. Functional characterization of three (GH13) branching enzymes involved in cyanobacterial starch biosynthesis from Cyanobacterium sp. NBRC 102756.

    PubMed

    Suzuki, Ryuichiro; Koide, Keiichi; Hayashi, Mari; Suzuki, Tomoko; Sawada, Takayuki; Ohdan, Takashi; Takahashi, Hidekazu; Nakamura, Yasunori; Fujita, Naoko; Suzuki, Eiji

    2015-05-01

    Starch and glycogen are widespread storage polysaccharides in bacteria, plants, and animals. Recently, some cyanobacteria were found to accumulate water-insoluble α-glucan similar to amylopectin rather than glycogen, the latter of which is more commonly produced in these organisms. The amylopectin-producing species including Cyanobacterium sp. NBRC 102756 invariably have three branching enzyme (BE) homologs, BE1, BE2, and BE3, all belonging to the glycoside hydrolase family 13. Multiple BE isoforms in prokaryotes have not been previously studied. In the present work, we carried out functional characterization of these enzymes expressed in Escherichia coli. The recombinant enzymes were all active, although the specific activity of BE3 was much lower than those of BE1 and BE2. After the incubation of the enzymes with amylopectin or amylose, the reaction products were analyzed by fluorophore-assisted carbohydrate capillary electrophoresis method. BE1 and BE2 showed similar chain-length preference to BEIIb isoform of rice (Oryza sativa L.), while the catalytic specificity of BE3 was similar to that of rice BEI. These results indicate that starch-producing cyanobacteria have both type-I BE (BE3) and type-II BEs (BE1 and BE2) in terms of chain-length preferences, as is the case of plants. All BE isoforms were active against phosphorylase limit dextrin, in which outer branches had been uniformly diminished to 4 glucose residues. Based on its catalytic properties, BE3 was assumed to have a role to transfer the glucan chain bearing branch(es) to give rise to a newly growing unit, or cluster as observed in amylopectin molecule.

  15. Cloning, expression, purification, and preliminary characterization of a putative hemoglobin from the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed Central

    Scott, N. L.; Lecomte, J. T.

    2000-01-01

    The genome of the unicellular cyanobacterium Synechocystis sp. PCC 6803 contains a gene (slr2097, glbN) encoding a 123 amino-acid product with sequence similarity to globins. Related proteins from cyanobacteria, ciliates, and green algae bind oxygen and have a pronounced tendency to coordinate the heme iron with two protein ligands. To study the structural and functional properties of Synechocystis sp. PCC 6803 hemoglobin, slr2097 was cloned and overexpressed in Escherichia coli. Purification of the hemoglobin was performed after addition of hemin to the clarified cell lysate. Recombinant, heme-reconstituted ferric Synechocystis sp. PCC 6803 hemoglobin was found to be a stable helical protein, soluble to concentrations higher than 500 microM. At neutral pH, it yielded an electronic absorption spectrum typical of a low-spin ferric species, with maxima at 410 and 546 nm. The proton NMR spectrum revealed sharp lines spread over a chemical shift window narrower than 40 ppm, in support of low-spin hexacoordination of the heme iron. Nuclear Overhauser effects demonstrated that the heme is inserted in the protein matrix to produce one major equilibrium form. Addition of dithionite resulted in an absorption spectrum with maxima at 426, 528, and 560 nm. This reduced form appeared capable of carbon monoxide binding. Optical data also suggested that cyanide ions could bind to the heme in the ferric state. The spectral properties of the putative Synechocystis sp. PCC 6803 hemoglobin confirmed that it can be used for further studies of an ancient hemoprotein structure. PMID:10752621

  16. Ethylene Regulates the Physiology of the Cyanobacterium Synechocystis sp. PCC 6803 via an Ethylene Receptor1[OPEN

    PubMed Central

    2016-01-01

    Ethylene is a plant hormone that plays a crucial role in the growth and development of plants. The ethylene receptors in plants are well studied, and it is generally assumed that they are found only in plants. In a search of sequenced genomes, we found that many bacterial species contain putative ethylene receptors. Plants acquired many proteins from cyanobacteria as a result of the endosymbiotic event that led to chloroplasts. We provide data that the cyanobacterium Synechocystis (Synechocystis sp. PCC 6803) has a functional receptor for ethylene, Synechocystis Ethylene Response1 (SynEtr1). We first show that SynEtr1 directly binds ethylene. Second, we demonstrate that application of ethylene to Synechocystis cells or disruption of the SynEtr1 gene affects several processes, including phototaxis, type IV pilus biosynthesis, photosystem II levels, biofilm formation, and spontaneous cell sedimentation. Our data suggest a model where SynEtr1 inhibits downstream signaling and ethylene inhibits SynEtr1. This is similar to the inverse-agonist model of ethylene receptor signaling proposed for plants and suggests a conservation of structure and function that possibly originated over 1 billion years ago. Prior research showed that SynEtr1 also contains a light-responsive phytochrome-like domain. Thus, SynEtr1 is a bifunctional receptor that mediates responses to both light and ethylene. To our knowledge, this is the first demonstration of a functional ethylene receptor in a nonplant species and suggests that that the perception of ethylene is more widespread than previously thought. PMID:27246094

  17. Site of non-photochemical quenching of the phycobilisome by orange carotenoid protein in the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Stadnichuk, Igor N; Yanyushin, Mikhail F; Maksimov, Evgeni G; Lukashev, Evgeni P; Zharmukhamedov, Sergei K; Elanskaya, Irina V; Paschenko, Vladimir Z

    2012-08-01

    In cyanobacteria, the thermal dissipation of excess absorbed energy at the level of the phycobilisome (PBS)-antenna is triggered by absorption of strong blue-green light by the photoactive orange carotenoid protein (OCP). This process known as non-photochemical quenching, whose molecular mechanism remains in many respects unclear, is revealed in vivo as a decrease in phycobilisome fluorescence. In vitro reconstituted system on the interaction of the OCP and the PBS isolated from the cyanobacterium Synechocystis sp. PCC 6803 presents evidence that the OCP is not only a photosensor, but also an effecter that makes direct contacts with the PBS and causes dissipation of absorbed energy. To localize the site(s) of quenching, we have analyzed the role of chromophorylated polypeptides of the PBS using PBS-deficient mutants in conjunction with in vitro systems of assembled PBS and of isolated components of the PBS core. The results demonstrated that L(CM), the core-membrane linker protein and terminal emitter of the PBS, could act as the docking site for OCP in vitro. The ApcD and ApcF terminal emitters of the PBS core are not directly subjected to quenching. The data suggests that there could be close contact between the phycocyanobilin chromophore of L(CM) and the 3'-hydroxyechinenone chromophore present in OCP and that L(CM) could be involved in OCP-induced quenching. According to the reduced average life-time of the PBS-fluorescence and linear dependence of fluorescence intensity of the PBS on OCP concentration, the quenching has mostly dynamic character. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial. PMID:22483736

  18. Gene Transfer in Leptolyngbya sp. Strain BL0902, a Cyanobacterium Suitable for Production of Biomass and Bioproducts

    PubMed Central

    Taton, Arnaud; Lis, Ewa; Adin, Dawn M.; Dong, Guogang; Cookson, Scott; Kay, Steve A.; Golden, Susan S.; Golden, James W.

    2012-01-01

    Current cyanobacterial model organisms were not selected for their growth traits or potential for the production of renewable biomass, biofuels, or other products. The cyanobacterium strain BL0902 emerged from a search for strains with superior growth traits. Morphology and 16S rRNA sequence placed strain BL0902 in the genus Leptolyngbya. Leptolyngbya sp. strain BL0902 (hereafter Leptolyngbya BL0902) showed robust growth at temperatures from 22°C to 40°C and tolerated up to 0.5 M NaCl, 32 mM urea, high pH, and high solar irradiance. Its growth rate under outdoor conditions rivaled Arthrospira (“pirulina” strains. Leptolyngbya BL0902 accumulated higher lipid content and a higher proportion of monounsaturated fatty acids than Arthrospira strains. In addition to these desirable qualities, Leptolyngbya BL0902 is amenable to genetic engineering that is reliable, efficient, and stable. We demonstrated conjugal transfer from Escherichia coli of a plasmid based on RSF1010 and expression of spectinomycin/streptomycin resistance and yemGFP reporter transgenes. Conjugation efficiency was investigated in biparental and triparental matings with and without a “elper”plasmid that carries DNA methyltransferase genes, and with two different conjugal plasmids. We also showed that Leptolyngbya BL0902 is amenable to transposon mutagenesis with a Tn5 derivative. To facilitate genetic manipulation of Leptolyngbya BL0902, a conjugal plasmid vector was engineered to carry a trc promoter upstream of a Gateway recombination cassette. These growth properties and genetic tools position Leptolyngbya BL0902 as a model cyanobacterial production strain. PMID:22292073

  19. Lyngbyoic acid, a “tagged” fatty acid from a marine cyanobacterium, disrupts quorum sensing in Pseudomonas aeruginosa†

    PubMed Central

    Kwan, Jason Christopher; Meickle, Theresa; Ladwa, Dheran; Teplitski, Max; Paul, Valerie; Luesch, Hendrik

    2013-01-01

    Quorum sensing (QS) is a mechanism of bacterial gene regulation in response to increases in population density. Perhaps most studied are QS pathways mediated by acylhomoserine lactones (AHLs) in Gram-negative bacteria. Production of small molecule QS signals, their accumulation within a diffusion-limited environment and their binding to a LuxR-type receptor trigger QS-controlled gene regulatory cascades. In Pseudomonas aeruginosa, for example, binding of AHLs to their cognate receptors (LasR, RhlR) controls production of virulence factors, pigments, antibiotics and other behaviors important for its interactions with eukaryotic hosts and other bacteria. We have previously shown that marine cyanobacteria produce QS-inhibitory molecules, including 8-epi-malyngamide C (1), malyngamide C (2) and malyngolide (3). Here we isolated a new small cyclopropane-containing fatty acid, lyngbyoic acid (4), as a major metabolite of the marine cyanobacterium, Lyngbya cf. majuscula, collected at various sites in Florida. We screened 4 against four reporters based on different AHL receptors (LuxR, AhyR, TraR and LasR) and found that 4 most strongly affected LasR. We also show that 4 reduces pyocyanin and elastase (LasB) both on the protein and transcript level in wild-type P. aeruginosa, and that 4 directly inhibits LasB enzymatic activity. Conversely, dodecanoic acid (9) increased pyocyanin and LasB, demonstrating that the fused cyclopropane “tag” is functionally relevant and potentially confers resistance to β-oxidation. Global transcriptional effects of 4 in some ways replicate the gene expression changes of P. aeruginosa during chronic lung infections of cystic fibrosis patients, with reduced lasR signaling, increased biofilm and expression of the virulence locus HSI-I. Compound 4 may therefore prove to be a useful tool in the study of P. aeruginosa adaption during such chronic infections. PMID:21258753

  20. Hydrogen Production by the Unicellular, Diazotrophic Cyanobacterium Cyanothece sp. Strain ATCC 51142 under Conditions of Continuous Light▿

    PubMed Central

    Min, Hongtao; Sherman, Louis A.

    2010-01-01

    We report on the hydrogen production properties of the unicellular, diazotrophic cyanobacterium Cyanothece sp. strain ATCC 51142. This organism has a versatile metabolism and can grow in the presence or absence of combined nitrogen and can grow photosynthetically or mixotrophically and heterotrophically in the presence of glycerol. The strain produces a bidirectional hydrogenase (encoded by the hox genes), an uptake hydrogenase (hupLS), and nitrogenase (nifHDK). We demonstrated hydrogen production by both the hydrogenase and the nitrogenase under appropriate metabolic conditions. The highest rates of hydrogen production were produced under nitrogen-fixing conditions when cells were grown and incubated under continuous light conditions, in either the presence or absence of glycerol. Under such nitrogen-fixing conditions, we have achieved rates of 300 μmol H2/mg chloramphenicol (Chl)/hr during the first 24 h of incubation. The levels of H2 measured were dependent upon the incubation conditions, such as sparging with argon, which generated anaerobic conditions. We demonstrated that the same conditions led to high levels of H2 production and N2 fixation, indicating that low-oxygen conditions favor nitrogenase activity for both processes. The levels of hydrogen produced by the hydrogenase are much lower, typically 5 to 10 μmol H2/mg Chl/hr. Hydrogenase activity was dependent upon electron transport through photosystem II (PS II), whereas nitrogenase activity was more dependent on PS I, as well as on respiration. Although cells do not double under the incubation conditions when sparged with argon to provide a low-oxygen environment, the cells are metabolically active, and hydrogen production can be inhibited by the addition of chloramphenicol to inhibit protein synthesis. PMID:20453150

  1. The Uptake Hydrogenase in the Unicellular Diazotrophic Cyanobacterium Cyanothece sp. Strain PCC 7822 Protects Nitrogenase from Oxygen Toxicity

    PubMed Central

    Zhang, Xiaohui; Sherman, Debra M.

    2014-01-01

    Cyanothece sp. strain PCC 7822 is a unicellular, diazotrophic cyanobacterium that can produce large quantities of H2 when grown diazotrophically. This strain is also capable of genetic manipulations and can represent a good model for improving H2 production from cyanobacteria. To this end, a knockout mutation was made in the hupL gene (ΔhupL), and we determined how this would affect the amount of H2 produced. The ΔhupL mutant demonstrated virtually no nitrogenase activity or H2 production when grown under N2-fixing conditions. To ensure that this mutation only affected the hupL gene, a complementation strain was constructed readily with wild-type properties; this indicated that the original insertion was only in hupL. The mutant had no uptake hydrogenase activity but had increased bidirectional hydrogenase (Hox) activity. Western blotting and immunocytochemistry under the electron microscope indicated that the mutant had neither HupL nor NifHDK, although the nif genes were transcribed. Interestingly, biochemical analysis demonstrated that both HupL and NifH could be membrane associated. The results indicated that the nif genes were transcribed but that NifHDK was either not translated or was translated but rapidly degraded. We hypothesized that the Nif proteins were made but were unusually susceptible to O2 damage. Thus, we grew the mutant cells under anaerobic conditions and found that they grew well under N2-fixing conditions. We conclude that in unicellular diazotrophs, like Cyanothece sp. strain PCC 7822, the HupLS complex helps remove oxygen from the nitrogenase, and that this is a more important function than merely oxidizing the H2 produced by the nitrogenase. PMID:24317398

  2. Harvesting Far-Red Light by Chlorophyll f in Photosystems I and II of Unicellular Cyanobacterium strain KC1.

    PubMed

    Itoh, Shigeru; Ohno, Tomoki; Noji, Tomoyasu; Yamakawa, Hisanori; Komatsu, Hirohisa; Wada, Katsuhiro; Kobayashi, Masami; Miyashita, Hideaki

    2015-10-01

    Cells of a unicellular cyanobacterium strain KC1, which were collected from Japanese fresh water Lake Biwa, formed chlorophyll (Chl) f at 6.7%, Chl a' at 2.0% and pheophytin a at 0.96% with respect to Chl a after growth under 740 nm light. The far-red-acclimated cells (Fr cells) formed extra absorption bands of Chl f at 715 nm in addition to the major Chl a band. Fluorescence lifetimes were measured. The 405-nm laser flash, which excites mainly Chl a in photosystem I (PSI), induced a fast energy transfer to multiple fluorescence bands at 720-760 and 805 nm of Chl f at 77 K in Fr cells with almost no PSI-red-Chl a band. The 630-nm laser flash, which mainly excited photosystem II (PSII) through phycocyanin, revealed fast energy transfer to another set of Chl f bands at 720-770 and 810 nm as well as to the 694-nm Chl a fluorescence band. The 694-nm band did not transfer excitation energy to Chl f. Therefore, Chl a in PSI, and phycocyanin in PSII of Fr cells transferred excitation energy to different sets of Chl f molecules. Multiple Chl f forms, thus, seem to work as the far-red antenna both in PSI and PSII. A variety of cyanobacterial species, phylogenically distant from each other, seems to use a Chl f antenna in far-red environments, such as under dense biomats, in colonies, or under far-red LED light.

  3. Consequences of ccmR deletion on respiration, fermentation and H2 metabolism in cyanobacterium Synechococcus sp. PCC 7002.

    PubMed

    Krishnan, Anagha; Zhang, Shuyi; Liu, Yang; Tadmori, Kinan A; Bryant, Donald A; Dismukes, Charles G

    2016-07-01

    CcmR, a LysR-type transcriptional regulator, represses the genes encoding components of the high-affinity carbon concentration mechanism in cyanobacteria. Unexpectedly, deletion of the ccmR gene was found to alter the expression of the terminal oxidase and fermentative genes, especially the hydrogenase operon in the cyanobacterium Synechococcus sp. PCC 7002. Consistent with the transcriptomic data, the deletion strain exhibits flux increases (30-50%) in both aerobic O2 respiration and anaerobic H2 evolution. To understand how CcmR influences anaerobic metabolism, the kinetics of autofermentation were investigated following photoautotrophic growth. The autofermentative H2 yield increased by 50% in the CcmR deletion strain compared to the wild-type strain, and increased to 160% (within 20 h) upon continuous removal of H2 from the medium ("milking") to suppress H2 uptake. Consistent with this greater reductant flux to H2 , the mutant excreted less lactate during autofermentation (NAD(P)H consuming pathway). To enhance the rate of NADH production during anaerobic metabolism, the ccmR mutant was engineered to introduce GAPDH overexpression (more NADH production) and LDH deletion (less NADH consumption). The triple mutant (ccmR deletion + GAPDH overexpression + LDH deletion) showed 6-8-fold greater H2 yield than the WT strain, achieving conversion rates of 17 nmol 10(8)  cells(-1)  h(-1) and yield of 0.87 H2 per glucose equivalent (8.9% theoretical maximum). Simultaneous monitoring of the intracellular NAD(P)H concentration and H2 production rate by these mutants reveals an inverse correspondence between these variables indicating hydrogenase-dependent H2 production as a major sink for consuming NAD(P)H in preference to excretion of reduced carbon as lactate during fermentation. Biotechnol. Bioeng. 2016;113: 1448-1459. © 2015 Wiley Periodicals, Inc. PMID:26704377

  4. Elucidation of insertion elements carried on plasmids and in vitro construction of shuttle vectors from the toxic cyanobacterium Planktothrix.

    PubMed

    Christiansen, Guntram; Goesmann, Alexander; Kurmayer, Rainer

    2014-08-01

    Several gene clusters that are responsible for toxin synthesis in bloom-forming cyanobacteria have been found to be associated with transposable elements (TEs). In particular, insertion sequence (IS) elements were shown to play a role in the inactivation or recombination of the genes responsible for cyanotoxin synthesis. Plasmids have been considered important vectors of IS element distribution to the host. In this study, we aimed to elucidate the IS elements propagated on the plasmids and the chromosome of the toxic cyanobacterium Planktothrix agardhii NIVA-CYA126/8 by means of high-throughput sequencing. In total, five plasmids (pPA5.5, pPA14, pPA50, pPA79, and pPA115, of 5, 6, 50, 79, and 120 kbp, respectively) were elucidated, and two plasmids (pPA5.5, pPA115) were found to propagate full IS element copies. Large stretches of shared DNA information between plasmids were constituted of TEs. Two plasmids (pPA5.5, pPA14) were used as candidates to engineer shuttle vectors (named pPA5.5SV and pPA14SV, respectively) in vitro by PCR amplification and the subsequent transposition of the Tn5 cat transposon containing the R6Kγ origin of replication of Escherichia coli. While pPA5.5SV was found to be fully segregated, pPA14SV consistently co-occurred with its wild-type plasmid even under the highest selective pressure. Interestingly, the Tn5 cat transposon became transferred by homologous recombination into another plasmid, pPA50. The availability of shuttle vectors is considered to be of relevance in investigating genome plasticity as a consequence of homologous recombination events. Combining the potential of high-throughput sequencing and in vitro production of shuttle vectors makes it simple to produce species-specific shuttle vectors for many cultivable prokaryotes.

  5. Characterization of two naturally truncated, Ssb-like proteins from the nitrogen-fixing cyanobacterium, Anabaena sp. PCC7120.

    PubMed

    Kirti, Anurag; Rajaram, Hema; Apte, Shree Kumar

    2013-11-01

    Single-stranded (ss) DNA-binding (Ssb) proteins are vital for all DNA metabolic processes and are characterized by an N-terminal OB-fold followed by P/G-rich spacer region and a C-terminal tail. In the genome of the heterocystous, nitrogen-fixing cyanobacterium, Anabaena sp. strain PCC 7120, two genes alr0088 and alr7579 are annotated as ssb, but the corresponding proteins have only the N-terminal OB-fold and no P/G-rich region or acidic tail, thereby rendering them unable to interact with genome maintenance proteins. Both the proteins were expressed under normal growth conditions in Anabaena PCC7120 and regulated differentially under abiotic stresses which induce DNA damage, indicating that these are functional genes. Constitutive overexpression of Alr0088 in Anabaena enhanced the tolerance to DNA-damaging stresses which caused formation of DNA adducts such as UV and MitomycinC, but significantly decreased the tolerance to γ-irradiation, which causes single- and double-stranded DNA breaks. On the other hand, overexpression of Alr7579 had no significant effect on normal growth or stress tolerance of Anabaena. Thus, of the two truncated Ssb-like proteins, Alr0088 may be involved in protection of ssDNA from damage, but due to the absence of acidic tail, it may not aid in repair of damaged DNA. These two proteins are present across cyanobacterial genera and unique to them. These initial studies pave the way to the understanding of DNA repair in cyanobacteria, which is not very well documented.

  6. ppGpp metabolism is involved in heterocyst development in the cyanobacterium Anabaena sp. strain PCC 7120.

    PubMed

    Zhang, Shao-Ran; Lin, Gui-Ming; Chen, Wen-Li; Wang, Li; Zhang, Cheng-Cai

    2013-10-01

    When deprived of a combined-nitrogen source in the growth medium, the filamentous cyanobacterium Anabaena sp. PCC 7120 (Anabaena) can form heterocysts capable of nitrogen fixation. The process of heterocyst differentiation takes about 20 to 24 h, during which extensive metabolic and morphological changes take place. Guanosine tetraphosphate (ppGpp) is the signal of the stringent response that ensures cell survival by adjusting major cellular activities in response to nutrient starvation in bacteria, and ppGpp accumulates at the early stage of heterocyst differentiation (J. Akinyanju, R. J. Smith, FEBS Lett. 107:173-176, 1979; J Akinyanju, R. J. Smith, New Phytol. 105:117-122, 1987). Here we show that all1549 (here designated relana) in Anabaena, homologous to relA/spoT, is upregulated in response to nitrogen deprivation and predominantly localized in vegetative cells. The disruption of relana strongly affects the synthesis of ppGpp, and the resulting mutant, all1549Ωsp/sm, fails to form heterocysts and to grow in the absence of a combined-nitrogen source. This phenotype can be complemented by a wild-type copy of relana. Although the upregulation of hetR is affected in the mutant, ectopic overexpression of hetR cannot rescue the phenotype. However, we found that the mutant rapidly loses its viability, within a time window of 3 to 6 h, following the deprivation of combined nitrogen. We propose that ppGpp plays a major role in rebalancing the metabolic activities of the cells in the absence of the nitrogen source supply and that this regulation is necessary for filament survival and consequently for the success of heterocyst differentiation.

  7. Influence of Various Levels of Iron and Other Abiotic Factors on Siderophorogenesis in Paddy Field Cyanobacterium Anabaena oryzae.

    PubMed

    Singh, Anumeha; Mishra, Arun Kumar

    2015-05-01

    Siderophore production in Anabaena oryzae was investigated under the influence of various levels of iron and other abiotic factors such as pH, temperature, light and different nitrogen sources. Optimization of culture conditions under controlled mechanisms of these abiotic factors lead to the siderophore production in significant amount. Under iron-starved condition, A. oryzae extracellularly releases 89.17% hydroxymate-type siderophore. Slightly alkaline pH and 30 °C temperature was found stimulatory for the cyanobacterial growth and siderophorogenesis (88.52% SU and 83.87% SU, respectively). Excess iron loading had a negative impact on siderophore production along with the alterations in the morphology and growth. Further, scanning electron microphotographs signified that higher concentrations of iron lead to complete damage of the cells and alterations in membrane proteins possibly transporters responsible for exchange of siderophore complex from environment to the cell. SDS-PAGE analysis of whole cell proteins showed overexpression of low molecular weight proteins ranges between 20.1 to 29.0 kDa up to 100-μM iron concentrations. These polypeptides/proteins might be involved in maintaining iron homeostasis by regulating siderophore production. Results suggest that lower concentrations of iron ≤ 50 μM along with other abiotic factors are stimulatory, whereas higher concentrations (>50 μM) are toxic. Data further suggested that cyanobacterium A. oryzae can serve as a potential biofertilizer especially in iron-rich soil through sequestration by the power of natural Fe(III)-siderophore complex formation. PMID:25805017

  8. ppGpp metabolism is involved in heterocyst development in the cyanobacterium Anabaena sp. strain PCC 7120.

    PubMed

    Zhang, Shao-Ran; Lin, Gui-Ming; Chen, Wen-Li; Wang, Li; Zhang, Cheng-Cai

    2013-10-01

    When deprived of a combined-nitrogen source in the growth medium, the filamentous cyanobacterium Anabaena sp. PCC 7120 (Anabaena) can form heterocysts capable of nitrogen fixation. The process of heterocyst differentiation takes about 20 to 24 h, during which extensive metabolic and morphological changes take place. Guanosine tetraphosphate (ppGpp) is the signal of the stringent response that ensures cell survival by adjusting major cellular activities in response to nutrient starvation in bacteria, and ppGpp accumulates at the early stage of heterocyst differentiation (J. Akinyanju, R. J. Smith, FEBS Lett. 107:173-176, 1979; J Akinyanju, R. J. Smith, New Phytol. 105:117-122, 1987). Here we show that all1549 (here designated relana) in Anabaena, homologous to relA/spoT, is upregulated in response to nitrogen deprivation and predominantly localized in vegetative cells. The disruption of relana strongly affects the synthesis of ppGpp, and the resulting mutant, all1549Ωsp/sm, fails to form heterocysts and to grow in the absence of a combined-nitrogen source. This phenotype can be complemented by a wild-type copy of relana. Although the upregulation of hetR is affected in the mutant, ectopic overexpression of hetR cannot rescue the phenotype. However, we found that the mutant rapidly loses its viability, within a time window of 3 to 6 h, following the deprivation of combined nitrogen. We propose that ppGpp plays a major role in rebalancing the metabolic activities of the cells in the absence of the nitrogen source supply and that this regulation is necessary for filament survival and consequently for the success of heterocyst differentiation. PMID:23935047

  9. Cluster of genes that encode positive and negative elements influencing filament length in a heterocyst-forming cyanobacterium.

    PubMed

    Merino-Puerto, Victoria; Herrero, Antonia; Flores, Enrique

    2013-09-01

    The filamentous, heterocyst-forming cyanobacteria perform oxygenic photosynthesis in vegetative cells and nitrogen fixation in heterocysts, and their filaments can be hundreds of cells long. In the model heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120, the genes in the fraC-fraD-fraE operon are required for filament integrity mainly under conditions of nitrogen deprivation. The fraC operon transcript partially overlaps gene all2395, which lies in the opposite DNA strand and ends 1 bp beyond fraE. Gene all2395 produces transcripts of 1.35 kb (major transcript) and 2.2 kb (minor transcript) that overlap fraE and whose expression is dependent on the N-control transcription factor NtcA. Insertion of a gene cassette containing transcriptional terminators between fraE and all2395 prevented production of the antisense RNAs and resulted in an increased length of the cyanobacterial filaments. Deletion of all2395 resulted in a larger increase of filament length and in impaired growth, mainly under N2-fixing conditions and specifically on solid medium. We denote all2395 the fraF gene, which encodes a protein restricting filament length. A FraF-green fluorescent protein (GFP) fusion protein accumulated significantly in heterocysts. Similar to some heterocyst differentiation-related proteins such as HglK, HetL, and PatL, FraF is a pentapeptide repeat protein. We conclude that the fraC-fraD-fraE←fraF gene cluster (where the arrow indicates a change in orientation), in which cis antisense RNAs are produced, regulates morphology by encoding proteins that influence positively (FraC, FraD, FraE) or negatively (FraF) the length of the filament mainly under conditions of nitrogen deprivation. This gene cluster is often conserved in heterocyst-forming cyanobacteria. PMID:23813733

  10. Novel Derivatives of 9,10-Anthraquinone Are Selective Algicides against the Musty-Odor Cyanobacterium Oscillatoria perornata

    PubMed Central

    Schrader, Kevin K.; Dhammika Nanayakkara, N. P.; Tucker, Craig S.; Rimando, Agnes M.; Ganzera, Markus; Schaneberg, Brian T.

    2003-01-01

    Musty “off-flavor” in pond-cultured channel catfish (Ictalurus punctatus) costs the catfish production industry in the United States at least $30 million annually. The cyanobacterium Oscillatoria perornata (Skuja) is credited with being the major cause of musty off-flavor in farm-raised catfish in Mississippi. The herbicides diuron and copper sulfate, currently used by catfish producers as algicides to help mitigate musty off-flavor problems, have several drawbacks, including broad-spectrum toxicity towards the entire phytoplankton community that can lead to water quality deterioration and subsequent fish death. By use of microtiter plate bioassays, a novel group of compounds derived from the natural compound 9,10-anthraquinone have been found to be much more selectively toxic towards O. perornata than diuron and copper sulfate. In efficacy studies using limnocorrals placed in catfish production ponds, application rates of 0.3 μM (125 μg/liter) of the most promising anthraquinone derivative, 2-[methylamino-N-(1′-methylethyl)]-9,10-anthraquinone monophosphate (anthraquinone-59), dramatically reduced the abundance of O. perornata and levels of 2-methylisoborneol, the musty compound produced by O. perornata. The abundance of green algae and diatoms increased dramatically 2 days after application of a 0.3 μM concentration of anthraquinone-59 to pond water within the limnocorrals. The half-life of anthraquinone-59 in pond water was determined to be 19 h, making it much less persistent than diuron. Anthraquinone-59 appears to be promising for use as a selective algicide in catfish aquaculture. PMID:12957919

  11. Transcriptional analysis of the unicellular, diazotrophic cyanobacterium Cyanothece sp. ATCC 51142 grown under short day/night cycles

    SciTech Connect

    Toepel, Jorg; McDermott, Jason E.; Summerfield, Tina; Sherman, Louis A.

    2009-06-01

    Cyanothece sp. strain ATCC 51142 is a unicellular, diazotrophic cyanobacterium that demonstrates extensive metabolic periodicities of photosynthesis, respiration and nitrogen fixation when grown under N2-fixing conditions. We have performed a global transcription analysis of this organism using 6 h light/dark cycles in order to determine the response of the cell to these conditions and to differentiate between diurnal and circadian regulated genes. In addition, we used a context-likelihood of relatedness (CLR) analysis with this data and those from two-day light/dark and light-dark plus continuous light experiments to better differentiate between diurnal and circadian regulated genes. Cyanothece sp. adapted in several ways to growth under short light/dark conditions. Nitrogen was fixed in every second dark period and only once in each 24 h period. Nitrogen fixation was strongly correlated to the energy status of the cells and glycogen breakdown and high respiration rates were necessary to provide appropriate energy and anoxic conditions for this process. We conclude that glycogen breakdown is a key regulatory step within these complex processes. Our results demonstrated that the main metabolic genes involved in photosynthesis, respiration, nitrogen fixation and central carbohydrate metabolism have strong (or total) circadian-regulated components. The short light/dark cycles enable us to identify transcriptional differences among the family of psbA genes, as well as the differing patterns of the hup genes, which follow the same pattern as nitrogenase genes, relative to the hox genes which displayed a diurnal, dark-dependent gene expression.

  12. Differential Transcriptional Analysis of the Cyanobacterium Cyanothece sp. Strain ATCC 51142 during Light-Dark and Continuous-Light Growth

    SciTech Connect

    Toepel, Jorg; Welsh, Eric A.; Summerfield, Tina; Pakrasi, Himadri B.; Sherman, Louis A.

    2008-06-01

    We analyzed the metabolic rhythms and differential gene transcription in the unicellular, diazotrophic cyanobacterium Cyanothece sp. ATCC51142 under N₂-fixing conditions with 12h light-12h dark cycles followed by 36 h continuous light. Cultures were grown in a 6-L bioreactor that was specially designed for photosynthetic microorganisms and that permitted continuous monitoring of parameters such as pH and dissolved oxygen. Our main objective was to determine the strategies used by these cells to perform N₂ fixation under normal day-night conditions, as well as under greater stress caused by continuous light. Our results strongly suggested that the level of N₂ fixation is dependent upon respiration for energy production and for removal of intracellular O₂. We determined that N₂ fixation cycled in continuous light, but that the N₂ fixation peak was lower and that glycogen degradation and respiration were also lower under these conditions. We also demonstrated that nifH (the gene encoding the Fe protein) and nifB and nifX were strongly induced in the continuous light; this is consistent with the mode of operation of these proteins relative to the MoFe protein and suggested that any regulation of N₂ fixation was at a posttranscriptional level. Also, many soluble electron carriers (e.g., ferredoxins), as well as redox carriers (e.g., thioredoxin and glutathione) were strongly induced during N₂ fixation in continuous light. We suggest that these carriers were required to generate enhanced cyclic electron transport and phosphorylation for energy production and to maintain appropriate redox levels in the presence of enhanced O₂, respectively.

  13. A Redox-Responsive Regulator of Photosynthesis Gene Expression in the Cyanobacterium Synechocystis sp. Strain PCC 6803

    PubMed Central

    Li, Hong; Sherman, Louis A.

    2000-01-01

    We have identified genes in the unicellular cyanobacterium Synechocystis sp. strain PCC 6803 that are involved with redox control of photosynthesis and pigment-related genes. The genes, rppA (sll0797) and rppB (sll0798), represent a two-component regulatory system that controls the synthesis of photosystem II (PSII) and PSI genes, in addition to photopigment-related genes. rppA (regulator of photosynthesis- and photopigment-related gene expression) and rppB exhibit strong sequence similarity to prokaryotic response regulators and histidine kinases, respectively. In the wild type, the steady-state mRNA levels of PSII reaction center genes increased when the plastoquinone (PQ) pool was oxidized and decreased when the PQ pool was reduced, whereas transcription of the PSI reaction center genes was affected in an opposite fashion. Such results suggested that the redox poise of the PQ pool is critical for regulation of the photosystem reaction center genes. In ΔrppA, an insertion mutation of rppA, the PSII gene transcripts were highly up-regulated relative to the wild type under all redox conditions, whereas transcription of phycobilisome-related genes and PSI genes was decreased. The higher transcription of the psbA gene in ΔrppA was manifest by higher translation of the D1 protein and a concomitant increase in O2 evolution. The results demonstrated that RppA is a regulator of photosynthesis- and photopigment-related gene expression, is involved in the establishment of the appropriate stoichiometry between the photosystems, and can sense changes in the PQ redox poise. PMID:10894737

  14. Cell Envelope Components Influencing Filament Length in the Heterocyst-Forming Cyanobacterium Anabaena sp. Strain PCC 7120

    PubMed Central

    Burnat, Mireia; Schleiff, Enrico

    2014-01-01

    Heterocyst-forming cyanobacteria grow as chains of cells (known as trichomes or filaments) that can be hundreds of cells long. The filament consists of individual cells surrounded by a cytoplasmic membrane and peptidoglycan layers. The cells, however, share a continuous outer membrane, and septal proteins, such as SepJ, are important for cell-cell contact and filament formation. Here, we addressed a possible role of cell envelope components in filamentation, the process of producing and maintaining filaments, in the model cyanobacterium Anabaena sp. strain PCC 7120. We studied filament length and the response of the filaments to mechanical fragmentation in a number of strains with mutations in genes encoding cell envelope components. Previously published peptidoglycan- and outer membrane-related gene mutants and strains with mutations in two genes (all5045 and alr0718) encoding class B penicillin-binding proteins isolated in this work were used. Our results show that filament length is affected in most cell envelope mutants, but the filaments of alr5045 and alr2270 gene mutants were particularly fragmented. All5045 is a dd-transpeptidase involved in peptidoglycan elongation during cell growth, and Alr2270 is an enzyme involved in the biosynthesis of lipid A, a key component of lipopolysaccharide. These results indicate that both components of the cell envelope, the murein sacculus and the outer membrane, influence filamentation. As deduced from the filament fragmentation phenotypes of their mutants, however, none of these elements is as important for filamentation as the septal protein SepJ. PMID:25201945

  15. Cluster of Genes That Encode Positive and Negative Elements Influencing Filament Length in a Heterocyst-Forming Cyanobacterium

    PubMed Central

    Merino-Puerto, Victoria; Herrero, Antonia

    2013-01-01

    The filamentous, heterocyst-forming cyanobacteria perform oxygenic photosynthesis in vegetative cells and nitrogen fixation in heterocysts, and their filaments can be hundreds of cells long. In the model heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120, the genes in the fraC-fraD-fraE operon are required for filament integrity mainly under conditions of nitrogen deprivation. The fraC operon transcript partially overlaps gene all2395, which lies in the opposite DNA strand and ends 1 bp beyond fraE. Gene all2395 produces transcripts of 1.35 kb (major transcript) and 2.2 kb (minor transcript) that overlap fraE and whose expression is dependent on the N-control transcription factor NtcA. Insertion of a gene cassette containing transcriptional terminators between fraE and all2395 prevented production of the antisense RNAs and resulted in an increased length of the cyanobacterial filaments. Deletion of all2395 resulted in a larger increase of filament length and in impaired growth, mainly under N2-fixing conditions and specifically on solid medium. We denote all2395 the fraF gene, which encodes a protein restricting filament length. A FraF-green fluorescent protein (GFP) fusion protein accumulated significantly in heterocysts. Similar to some heterocyst differentiation-related proteins such as HglK, HetL, and PatL, FraF is a pentapeptide repeat protein. We conclude that the fraC-fraD-fraE←fraF gene cluster (where the arrow indicates a change in orientation), in which cis antisense RNAs are produced, regulates morphology by encoding proteins that influence positively (FraC, FraD, FraE) or negatively (FraF) the length of the filament mainly under conditions of nitrogen deprivation. This gene cluster is often conserved in heterocyst-forming cyanobacteria. PMID:23813733

  16. Biofilm Growth and Near-Infrared Radiation-Driven Photosynthesis of the Chlorophyll d-Containing Cyanobacterium Acaryochloris marina

    PubMed Central

    Behrendt, Lars; Schrameyer, Verena; Qvortrup, Klaus; Lundin, Luisa; Sørensen, Søren J.; Larkum, Anthony W. D.

    2012-01-01

    The cyanobacterium Acaryochloris marina is the only known phototroph harboring chlorophyll (Chl) d. It is easy to cultivate it in a planktonic growth mode, and A. marina cultures have been subject to detailed biochemical and biophysical characterization. In natural situations, A. marina is mainly found associated with surfaces, but this growth mode has not been studied yet. Here, we show that the A. marina type strain MBIC11017 inoculated into alginate beads forms dense biofilm-like cell clusters, as in natural A. marina biofilms, characterized by strong O2 concentration gradients that change with irradiance. Biofilm growth under both visible radiation (VIS, 400 to 700 nm) and near-infrared radiation (NIR, ∼700 to 730 nm) yielded maximal cell-specific growth rates of 0.38 per day and 0.64 per day, respectively. The population doubling times were 1.09 and 1.82 days for NIR and visible light, respectively. The photosynthesis versus irradiance curves showed saturation at a photon irradiance of Ek (saturating irradiance) >250 μmol photons m−2 s−1 for blue light but no clear saturation at 365 μmol photons m−2 s−1 for NIR. The maximal gross photosynthesis rates in the aggregates were ∼1,272 μmol O2 mg Chl d−1 h−1 (NIR) and ∼1,128 μmol O2 mg Chl d−1 h−1 (VIS). The photosynthetic efficiency (α) values were higher in NIR-irradiated cells [(268 ± 0.29) × 10−6 m2 mg Chl d−1 (mean ± standard deviation)] than under blue light [(231 ± 0.22) × 10−6 m2 mg Chl d−1]. A. marina is well adapted to a biofilm growth mode under both visible and NIR irradiance and under O2 conditions ranging from anoxia to hyperoxia, explaining its presence in natural niches with similar environmental conditions. PMID:22467501

  17. The response regulator Npun_F1278 is essential for scytonemin biosynthesis in the cyanobacterium Nostoc punctiforme ATCC 29133.

    PubMed

    Naurin, Sejuti; Bennett, Janine; Videau, Patrick; Philmus, Benjamin; Soule, Tanya

    2016-08-01

    Following exposure to long-wavelength ultraviolet radiation (UVA), some cyanobacteria produce the indole-alkaloid sunscreen scytonemin. The genomic region associated with scytonemin biosynthesis in the cyanobacterium Nostoc punctiforme includes 18 cotranscribed genes. A two-component regulatory system (Npun_F1277/Npun_F1278) directly upstream from the biosynthetic genes was identified through comparative genomics and is likely involved in scytonemin regulation. In this study, the response regulator (RR), Npun_F1278, was evaluated for its ability to regulate scytonemin biosynthesis using a mutant strain of N. punctiforme deficient in this gene, hereafter strain Δ1278. Following UVA radiation, the typical stimulus to initiate scytonemin biosynthesis, Δ1278 was incapable of producing scytonemin. A phenotypic characterization of Δ1278 suggests that aside from the ability to produce scytonemin, the deletion of the Npun_F1278 gene does not affect the cellular morphology, cellular differentiation capability, or lipid-soluble pigment complement of Δ1278 compared to the wildtype. The mutant, however, had a slower specific growth rate under white light and produced ~2.5-fold more phycocyanin per cell under UVA than the wildtype. Since Δ1278 does not produce scytonemin, this study demonstrates that the RR gene, Npun_F1278, is essential for scytonemin biosynthesis in N. punctiforme. While most of the evaluated effects of this gene appear to be specific for scytonemin, this regulator may also influence the overall health of the cell and phycobiliprotein synthesis, directly or indirectly. This is the first study to identify a regulatory gene involved in the biosynthesis of the sunscreen scytonemin and posits a link between cell growth, pigment synthesis, and sunscreen production. PMID:27020740

  18. Effects of Phosphorylation of β Subunits of Phycocyanins on State Transition in the Model Cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Chen, Zhuo; Zhan, Jiao; Chen, Ying; Yang, Mingkun; He, Chenliu; Ge, Feng; Wang, Qiang

    2015-10-01

    Synechocystis sp. PCC 6803 (hereafter Synechocystis) is a model cyanobacterium and has been used extensively for studies concerned with photosynthesis and environmental adaptation. Although dozens of protein kinases and phosphatases with specificity for Ser/Thr/Tyr residues have been predicted, only a few substrate proteins are known in Synechocystis. In this study, we report 194 in vivo phosphorylation sites from 149 proteins in Synechocystis, which were identified using a combination of peptide pre-fractionation, TiO(2) enrichment and liquid chromatograpy-tandem mass spectrometry (LC-MS/MS) analysis. These phosphorylated proteins are implicated in diverse biological processes, such as photosynthesis. Among all identified phosphoproteins involved in photosynthesis, the β subunits of phycocyanins (CpcBs) were found to be phosphorylated on Ser22, Ser49, Thr94 and Ser154. Four non-phosphorylated mutants were constructed by using site-directed mutagenesis. The in vivo characterization of the cpcB mutants showed a slower growth under high light irradiance and displayed fluorescence quenching to a lower level and less efficient energy transfer inside the phycobilisome (PBS). Notably, the non-phosphorylated mutants exhibited a slower state transition than the wild type. The current results demonstrated that the phosphorylation status of CpcBs affects the energy transfer and state transition of photosynthesis in Synechocystis. This study provides novel insights into the molecular mechanisms of protein phosphorylation in the regulation of photosynthesis in cyanobacteria and may facilitate the elucidation of the entire regulatory network by linking kinases to their physiological substrates. PMID:26315596

  19. Primary structure and carbohydrate binding specificity of a potent anti-HIV lectin isolated from the filamentous cyanobacterium Oscillatoria agardhii.

    PubMed

    Sato, Yuichiro; Okuyama, Satomi; Hori, Kanji

    2007-04-13

    The primary structure of a lectin, designated Oscillatoria agardhii agglutinin (OAA), isolated from the freshwater cyanobacterium O. agardhii NIES-204 was determined by the combination of Edman degradation and electron spray ionization-mass spectrometry. OAA is a polypeptide (Mr 13,925) consisting of two tandem repeats. Interestingly, each repeat sequence of OAA showed a high degree of similarity to those of a myxobacterium, Myxococcus xanthus hemagglutinin, and a marine red alga Eucheuma serra lectin. A systematic binding assay with pyridylaminated oligosaccharides revealed that OAA exclusively binds to high mannose (HM)-type N-glycans but not to other N-glycans, including complex types, hybrid types, and the pentasaccharide core or oligosaccharides from glycolipids. OAA did not interact with any of free mono- and oligomannoses that are constituents of the branched oligomannosides. These results suggest that the core disaccharide, GlcNAc-GlcNAc, is also essential for binding to OAA. The binding activity of OAA to HM type N-glycans was dramatically decreased when alpha1-2 Man was attached to alpha1-3 Man branched from the alpha1-6 Man of the pentasaccharide core. This specificity of OAA for HM-type oligosaccharides is distinct from other HM-binding lectins. Kinetic analysis with an HM heptasaccharide revealed that OAA possesses two carbohydrate binding sites per molecule, with an association constant of 2.41x10(8) m-1. Furthermore, OAA potently inhibits human immunodeficiency virus replication in MT-4 cells (EC50=44.5 nm). Thus, we have found a novel lectin family sharing similar structure and carbohydrate binding specificity among bacteria, cyanobacteria, and marine algae. PMID:17314091

  20. Hydrogen production from organic substrates in an aerobic nitrogen-fixing marine unicellular cyanobacterium Synechococcus sp. strain Miami BG 043511

    SciTech Connect

    Luo, Y.H.; Mitsui, A. )

    1994-11-20

    Synechococcus sp. strain Miami BG 043511 exhibits very high H[sub 2] photoproduction from water, but the H[sub 2] photo-production capability is lost rapidly with the age of the batch culture. The decrease of the capability coincides with the decrease of cellular glucose content. However, H[sub 2] photoproduction capability can be restored by the addition of organic substrates. Among 40 organic compounds tested, carbohydrates such as glucose, fructose, maltose, and sucrose were effective electron donors. Among organic acids tested, only pyruvate was an effective electron donor. Among alcohols tested, glycerol was a good electron donor, whereas ethanol was a poor but positive electron donor. These results demonstrate that this unicellular cyanobacterium exhibits a wide substrate specificity for H[sub 2] photoproduction but has a different substrate specificity compared to photosynthetic bacteria. The maximum rates of H[sub 2] photoproduction from a 6-day-old batch culture with 25 mmol of pyruvate, glucose, maltose, sucrose, fructose, and glycerol were 1.11, 0.62, 0.05, 0.47, 0.30, and 0.39 [mu]moles per mg cell dry weight per hour respectively. Therefore, this cyanobacterial strain may have a potential significance in removing organic materials from the wastewater and simultaneously transforming them to H[sub 2] gas, a pollution-free energy. The activity of nitrogenase, which catalyzes hydrogen production, completely disappeared when intracellular glucose was used up, but it could be restored by the addition of organic substrates such as glucose and pyruvate.

  1. Cell envelope components influencing filament length in the heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120.

    PubMed

    Burnat, Mireia; Schleiff, Enrico; Flores, Enrique

    2014-12-01

    Heterocyst-forming cyanobacteria grow as chains of cells (known as trichomes or filaments) that can be hundreds of cells long. The filament consists of individual cells surrounded by a cytoplasmic membrane and peptidoglycan layers. The cells, however, share a continuous outer membrane, and septal proteins, such as SepJ, are important for cell-cell contact and filament formation. Here, we addressed a possible role of cell envelope components in filamentation, the process of producing and maintaining filaments, in the model cyanobacterium Anabaena sp. strain PCC 7120. We studied filament length and the response of the filaments to mechanical fragmentation in a number of strains with mutations in genes encoding cell envelope components. Previously published peptidoglycan- and outer membrane-related gene mutants and strains with mutations in two genes (all5045 and alr0718) encoding class B penicillin-binding proteins isolated in this work were used. Our results show that filament length is affected in most cell envelope mutants, but the filaments of alr5045 and alr2270 gene mutants were particularly fragmented. All5045 is a dd-transpeptidase involved in peptidoglycan elongation during cell growth, and Alr2270 is an enzyme involved in the biosynthesis of lipid A, a key component of lipopolysaccharide. These results indicate that both components of the cell envelope, the murein sacculus and the outer membrane, influence filamentation. As deduced from the filament fragmentation phenotypes of their mutants, however, none of these elements is as important for filamentation as the septal protein SepJ. PMID:25201945

  2. Reversal in competitive dominance of a toxic versus non-toxic cyanobacterium in response to rising CO2.

    PubMed

    Van de Waal, Dedmer B; Verspagen, Jolanda M H; Finke, Jan F; Vournazou, Vasiliki; Immers, Anne K; Kardinaal, W Edwin A; Tonk, Linda; Becker, Sven; Van Donk, Ellen; Visser, Petra M; Huisman, Jef

    2011-09-01

    Climate change scenarios predict a doubling of the atmospheric CO(2) concentration by the end of this century. Yet, how rising CO(2) will affect the species composition of aquatic microbial communities is still largely an open question. In this study, we develop a resource competition model to investigate competition for dissolved inorganic carbon in dense algal blooms. The model predicts how dynamic changes in carbon chemistry, pH and light conditions during bloom development feed back on competing phytoplankton species. We test the model predictions in chemostat experiments with monocultures and mixtures of a toxic and non-toxic strain of the freshwater cyanobacterium Microcystis aeruginosa. The toxic strain was able to reduce dissolved CO(2) to lower concentrations than the non-toxic strain, and became dominant in competition at low CO(2) levels. Conversely, the non-toxic strain could grow at lower light levels, and became dominant in competition at high CO(2) levels but low light availability. The model captured the observed reversal in competitive dominance, and was quantitatively in good agreement with the results of the competition experiments. To assess whether microcystins might have a role in this reversal of competitive dominance, we performed further competition experiments with the wild-type strain M. aeruginosa PCC 7806 and its mcyB mutant impaired in microcystin production. The microcystin-producing wild type had a strong selective advantage at low CO(2) levels but not at high CO(2) levels. Our results thus demonstrate both in theory and experiment that rising CO(2) levels can alter the community composition and toxicity of harmful algal blooms. PMID:21390081

  3. The purine degradation pathway: possible role in paralytic shellfish toxin metabolism in the cyanobacterium Planktothrix sp. FP1.

    PubMed

    Pomati, F; Manarolla, G; Rossi, O; Vigetti, D; Rossetti, C

    2001-12-01

    The paralytic shellfish toxins (PSTs) are potent neurotoxic alkaloids and their major biological effect is due to the blockage of voltage-gated sodium channels in excitable cells. They have been recognised as an important health risk for humans, animals, and ecosystems worldwide. The metabolic pathways that lead to the production and the degradation of these toxic metabolites are still unknown. In this study, we investigated the possible link between PST accumulation and the activation of the metabolism that leads to purine degradation in the filamentous freshwater cyanobacterium Planktothrix sp. FP1. The purine catabolic pathway is related to the nitrogen microcycle in water environments, in which cyanobacteria use traces of purines and ureides as a nitrogen source for growth. Thus, the activity of allantoicase, a key inducible enzyme of this metabolism, was used as tool for assaying the activation of the purine degradation pathway. The enzyme and the pathway were induced by allantoic acid, the direct substrate of allantoicase, as well as by adenine and, to a lower degree, by urea, one of the main products of purine catabolism. Crude cell extract of Escherichia coli was also employed and showed the best induction of allantoicase activity. In culture, Planktothrix sp. FP1 showed a differential accumulation of PST in consequence of the induction with different substrates. The cyanobacterial culture induced with allantoic acid accumulated 61.7% more toxins in comparison with the control. On the other hand, the cultures induced with adenine, urea, and the E. coli extract showed low PST accumulation, respectively, 1%, 38%, and 5% of the total toxins content detected in the noninduced culture. A degradation pathway for the PSTs can be hypothesised: as suggested for purine alkaloids in higher plants, saxitoxin (STX) and derivatives may also be converted into xanthine, urea, and further to CO2 and NH4+ or recycled in the primary metabolism through the purine degradation

  4. THE TOXIC CYANOBACTERIUM NOSTOC SP. STRAIN 152 PRODUCES HIGHEST AMOUNTS OF MICROCYSTIN AND NOSTOPHYCIN UNDER STRESS CONDITIONS

    PubMed Central

    Kurmayer, Rainer

    2012-01-01

    The understanding of how environmental factors regulate toxic secondary metabolite production in cyanobacteria is important to guarantee water quality. Very little is known on the regulation of toxic secondary metabolite production in benthic cyanobacteria. In this study the physiological regulation of the production of the toxic heptapeptide microcystin (MC) and the non-toxic related peptide nostophycin (NP) in the benthic cyanobacterium Nostoc sp. strain 152 was studied under contrasting environmental conditions. I used a 2k levels factorial design, where k is the number of four factors that have been tested: Reduction in temperature (20 vs. 12°C), irradiance (50 vs. 1 μmol · m−2 · s−1), P-PO4 (144 vs. 0.14 μM P-PO4), N-NO3 (5.88 mM vs. N-NO3 free). While the growth rate was reduced more than hundred fold under most severe conditions of temperature, irradiance, and phosphate reduction the production of MC and NP never ceased. The MC and NP contents per cell varied at maximum 5- and 10.6-fold each, however the physiological variation did not outweigh the highly significant linear relationship between the daily cell division rate and the MC and NP net production rates. Surprisingly the MC and NP contents per cell showed a maximum under P-PO4 reduced and irradiance reduced conditions. Both intra- and extracellular MC and NP concentrations were negatively related to P-PO4 and irradiance. It is concluded that the proximate factor behind maximal cellular MC and NP contents is physiological stress. PMID:22723716

  5. Effects of UV-B radiation and periodic desiccation on the morphogenesis of the edible terrestrial cyanobacterium Nostoc flagelliforme.

    PubMed

    Feng, Yan-Na; Zhang, Zhong-Chun; Feng, Jun-Li; Qiu, Bao-Sheng

    2012-10-01

    The terrestrial cyanobacterium Nostoc flagelliforme Berk. et M. A. Curtis has been a popular food and herbal ingredient for hundreds of years. To meet great market demand and protect the local ecosystem, for decades researchers have tried to cultivate N. flagelliforme but have failed to get macroscopic filamentous thalli. In this study, single trichomes with 50 to 200 vegetative cells were induced from free-living cells by low light and used to investigate the morphogenesis of N. flagelliforme under low UV-B radiation and periodic desiccation. Low-fluence-rate UV-B (0.1 W m(-2)) did not inhibit trichome growth; however, it significantly increased the synthesis of extracellular polysaccharides and mycosporine-like amino acids and promoted sheath formation outside the trichomes. Under low UV-B radiation, single trichomes developed into filamentous thalli more than 1 cm long after 28 days of cultivation, most of which grew separately in liquid BG11 medium. With periodic desiccation treatment, the single trichomes formed flat or banded thalli that grew up to 2 cm long after 3 months on solid BG11 medium. When trichomes were cultivated on solid BG11 medium with alternate treatments of low UV-B and periodic desiccation, dark and scraggly filamentous thalli that grew up to about 3 cm in length after 40 days were obtained. In addition, the cultivation of trichomes on nitrogen-deficient solid BG11 medium (BG11(0)) suggested that nitrogen availability could affect the color and lubricity of newly developed thalli. This study provides promising techniques for artificial cultivation of N. flagelliforme in the future. PMID:22865081

  6. Insights into the Physiology and Ecology of the Brackish-Water-Adapted Cyanobacterium Nodularia spumigena CCY9414 Based on a Genome-Transcriptome Analysis

    PubMed Central

    Voß, Björn; Bolhuis, Henk; Fewer, David P.; Kopf, Matthias; Möke, Fred; Haas, Fabian; El-Shehawy, Rehab; Hayes, Paul; Bergman, Birgitta; Sivonen, Kaarina; Dittmann, Elke; Scanlan, Dave J.; Hagemann, Martin; Stal, Lucas J.; Hess, Wolfgang R.

    2013-01-01

    Nodularia spumigena is a filamentous diazotrophic cyanobacterium that dominates the annual late summer cyanobacterial blooms in the Baltic Sea. But N. spumigena also is common in brackish water bodies worldwide, suggesting special adaptation allowing it to thrive at moderate salinities. A draft genome analysis of N. spumigena sp. CCY9414 yielded a single scaffold of 5,462,271 nucleotides in length on which genes for 5,294 proteins were annotated. A subsequent strand-specific transcriptome analysis identified more than 6,000 putative transcriptional start sites (TSS). Orphan TSSs located in intergenic regions led us to predict 764 non-coding RNAs, among them 70 copies of a possible retrotransposon and several potential RNA regulators, some of which are also present in other N2-fixing cyanobacteria. Approximately 4% of the total coding capacity is devoted to the production of secondary metabolites, among them the potent hepatotoxin nodularin, the linear spumigin and the cyclic nodulapeptin. The transcriptional complexity associated with genes involved in nitrogen fixation and heterocyst differentiation is considerably smaller compared to other Nostocales. In contrast, sophisticated systems exist for the uptake and assimilation of iron and phosphorus compounds, for the synthesis of compatible solutes, and for the formation of gas vesicles, required for the active control of buoyancy. Hence, the annotation and interpretation of this sequence provides a vast array of clues into the genomic underpinnings of the physiology of this cyanobacterium and indicates in particular a competitive edge of N. spumigena in nutrient-limited brackish water ecosystems. PMID:23555932

  7. Identification of a cis-acting element in nitrogen fixation genes recognized by CnfR in the nonheterocystous nitrogen-fixing cyanobacterium Leptolyngbya boryana.

    PubMed

    Tsujimoto, Ryoma; Kamiya, Narumi; Fujita, Yuichi

    2016-08-01

    The filamentous cyanobacterium Leptolyngbya boryana has the ability to fix nitrogen without any heterocysts under microoxic conditions. Previously, we identified the cnfR gene for a master transcriptional activator for nitrogen fixation (nif) genes in a 50-kb gene cluster containing nif and nif-related genes in L. boryana. We showed that CnfR activates the transcription of nif genes in response to low oxygen conditions, which allows the oxygen-vulnerable enzyme nitrogenase to function. However, the regulatory mechanism that underlies regulation by CnfR remains unknown. In this study, we identified a conserved cis-acting element that is recognized by CnfR. We established a reporter system in the non-diazotrophic cyanobacterium Synechocystis sp. PCC 6803 using luciferase genes (luxAB). Reporter analysis was performed with a series of truncated and modified upstream regulatory regions of nifB and nifP. The cis-element can be divided into nine motifs I-IX, and it is located 76 bp upstream of the transcriptional start sites of nifB and nifP. Six motifs of them are essential for transcriptional activation by CnfR. This cis-acting element is conserved in the upstream regions of nif genes in all diazotrophic cyanobacteria, including Anabaena and Cyanothece, thereby suggesting that the transcriptional regulation by CnfR is widespread in nitrogen-fixing cyanobacteria.

  8. Oligonucleotide-directed mutagenesis of psbB, the gene encoding CP47, employing a deletion mutant strain of the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Eaton-Rye, J J; Vermaas, W F

    1991-12-01

    A mutant strain of the cyanobacterium Synechocystis sp. PCC (Pasteur Culture Collection) 6803 has been developed in which psbB, the gene coding for the chlorophyl alpha-binding protein CP47 in Photosystem II (PSII), has been deleted. This deletion mutant can be used for the reintroduction of modified psbB into the cyanobacterium. To study the role of a large hydrophilic region in CP47, presumably located on the lumenal side of the thylakoid membrane between the fifth and sixth membrane-spanning regions, specific deletions have been introduced in psbB coding for regions within this domain. One psbB mutation leads to deletion of Gly-351 to Thr-365 in CP47, another psbB mutation was targeted towards deletion of Arg-384 to Val-392 in this protein. The deletion from Gly-351 to Thr-365 results in a loss of PSII activity and of photoautotrophic growth of the mutant, but the deletion between Arg-384 and Val-392 retains PSII activity and the ability to grow photoautotrophically. The mutant strain with the deletion from Gly-351 to Thr-365 does not assemble a stable PSII reaction center complex in its thylakoid membranes, and exhibits diminished levels of CP47 and of the reaction center proteins D1 and D2. In contrast to the Arg-384 to Val-392 portion of this domain, the region between Gly-351 and Thr-365 appears essential for the normal structure and function of photosystem II. PMID:1932693

  9. Red-shifted red/green-type cyanobacteriochrome AM1_1870g3 from the chlorophyll d-bearing cyanobacterium Acaryochloris marina.

    PubMed

    Narikawa, Rei; Fushimi, Keiji; Ni-Ni-Win; Ikeuchi, Masahiko

    2015-05-29

    Cyanobacteriochromes (CBCRs) are diverse photoreceptors that are found only from cyanobacteria and cover wide range of light qualities. CBCRs are divided into two types regarding the chromophore species they contain: phycocyanobilin (PCB) and phycoviolobilin. Red/green-type CBCRs are widely distributed subfamily among the PCB-binding CBCRs and photoconvert between a red-absorbing thermostable form and a green-absorbing metastable form. Our recent study discovered that a red/green-type CBCR, AM1_1557g2, from a cyanobacterium Acaryochloris marina covalently binds not only PCB but also biliverdin (BV). BV-binding AM1_1557g2 photoconverts between a far-red absorbing form and an orange-absorbing form. We report, herein, that another red/green-type CBCR, AM1_1870g3, from the cyanobacterium A. marina also bound both PCB and BV. PCB- and BV-binding ones showed red/green and far-red/orange reversible photoconversions, respectively. Unexpectedly, absorbing wavelengths are 10-20 nm red-shifted compared with those of AM1_1557g2. These red-shifted characteristics may be useful for optogenetic light switches that work in various organisms. PMID:25892514

  10. Persistent phytoplankton bloom in Lake St. Lucia (iSimangaliso Wetland Park, South Africa) caused by a cyanobacterium closely associated with the genus Cyanothece (Synechococcaceae, Chroococcales).

    PubMed

    Muir, David G; Perissinotto, Renzo

    2011-09-01

    Lake St. Lucia, iSimangaliso Wetland Park, South Africa, is the largest estuarine lake in Africa. Extensive use and manipulation of the rivers flowing into it have reduced freshwater inflow, and the lake has also been subject to a drought of 10 years. For much of this time, the estuary has been closed to the Indian Ocean, and salinities have progressively risen throughout the system, impacting the biotic components of the ecosystem, reducing zooplankton and macrobenthic biomass and diversity in particular. In June 2009, a bloom of a red/orange planktonic microorganism was noted throughout the upper reaches of Lake St. Lucia. The bloom persisted for at least 18 months, making it the longest such bloom on record. The causative organism was characterized by light and electron microscopy and by 16S rRNA sequencing and was shown to be a large, unicellular cyanobacterium most strongly associated with the genus Cyanothece. The extent and persistence of the bloom appears to be unique to Lake St. Lucia, and it is suggested that the organism's resistance to high temperatures, to intense insolation, and to hypersalinity as well as the absence of grazing pressure by salinity-sensitive zooplankton all contributed to its persistence as a bloom organism until a freshwater influx, due to exceptionally heavy summer rains in 2011, reduced the salinity for a sufficient length of time to produce a crash in the cyanobacterium population as a complex, low-salinity biota redeveloped.

  11. Nitrate and amino acid availability affects glycine betaine and mycosporine-2-glycine in response to changes of salinity in a halotolerant cyanobacterium Aphanothece halophytica.

    PubMed

    Waditee-Sirisattha, Rungaroon; Kageyama, Hakuto; Fukaya, Minoru; Rai, Vandna; Takabe, Teruhiro

    2015-12-01

    A halotolerant cyanobacterium Aphanothece halophytica thrives in extreme salinity with accumulation of a potent osmoprotectant glycine betaine. Recently, this cyanobacterium was shown to accumulate sunscreen molecule mycosporine-2-glycine significantly at high salinity. In this study, we investigated effects of nitrate and amino acid provision on the accumulation of glycine betaine and mycosporine-2-glycine. With elevated nitrate concentrations at high salinity, intracellular levels of both metabolites were enhanced. Six-fold high nitrate concentration increased the relative amounts of glycine betaine and mycosporine-2-glycine to be 1.5 and 2.0 folds compared with control condition : Increased levels were time- and dose-dependent manner. Exogenous supply of glycine/serine at high salinity resulted in the similar trends as observed in excess nitrate experiment. Intracellular level of glycine betaine increased ∼1.6 folds with glycine/serine supplementation. These supplementations also caused the increased level of mycosporine-2-glycine, namely 1.4 and 2 folds by glycine and serine, respectively. The transcription of glycine betaine and mycosporine-2-glycine biosynthetic genes was strongly induced under high-nitrate-salt condition. These results suggest the dependence of glycine betaine and mycosporine-2-glycine productions on substrate availability, and the effect of nitrate was possibly associated with stimulation of osmoprotectant increment in this extremophile. PMID:26474598

  12. Antagonism at combined effects of chemical fertilizers and carbamate insecticides on the rice-field N2-fixing cyanobacterium Cylindrospermum sp. in vitro

    PubMed Central

    Nayak, Nabakishore; Rath, Shakti

    2014-01-01

    Effects of chemical fertilizers (urea, super phosphate and potash) on toxicities of two carbamate insecticides, carbaryl and carbofuran, individually to the N2-fixing cyanobacterium, Cylindrospermum sp. were studied in vitro at partially lethal levels (below highest permissive concentrations) of each insecticide. The average number of vegetative cells between two polar heterocysts was 16.3 in control cultures, while the mean value of filament length increased in the presence of chemical fertilizers, individually. Urea at the 10 ppm level was growth stimulatory and at the 50 ppm level it was growth inhibitory in control cultures, while at 100 ppm it was antagonistic, i.e. toxicity-enhancing along with carbaryl, individually to the cyanobacterium, antagonism was recorded. Urea at 50 ppm had toxicity reducing effect with carbaryl or carbofuran. At 100 and 250 ppm carbofuran levels, 50 ppm urea only had a progressive growth enhancing effect, which was marked well at 250 ppm carbofuran level, a situation of synergism. Super phosphate at the 10 ppm level only was growth promoting in control cultures, but it was antagonistic at its higher levels (50 and 100 ppm) along with both insecticides, individually. Potash (100, 200, 300 and 400 ppm) reduced toxicity due to carbaryl 20 and carbofuran 250 ppm levels, but potash was antagonistic at the other insecticide levels. The data clearly showed that the chemical fertilizers used were antagonistic with both the insecticides during toxicity to Cylindrospermum sp. PMID:26038669

  13. Identification of the oriC region and its influence on heterocyst development in the filamentous cyanobacterium Anabaena sp. strain PCC 7120.

    PubMed

    Zhou, Yin; Chen, Wen-Li; Wang, Li; Zhang, Cheng-Cai

    2011-07-01

    Anabaena sp. strain PCC 7120 (Anabaena PCC 7120) is a filamentous, nitrogen-fixing cyanobacterium. Upon deprivation of combined nitrogen, about 5-10 % of the cells become heterocysts, i.e. cells devoted to N(2) fixation. Heterocysts are intercalated among vegetative cells and distributed in a semi-regular pattern, and adjacent heterocysts are rarely observed. Previously, we showed that the cell cycle could play a regulatory function during heterocyst development, although the mechanism involved remains unknown. As a further step to understand this phenomenon, we identified the oriC region for chromosomal DNA replication, located between dnaA and dnaN. The oriC region of Anabaena PCC 7120 was able to support the self-replication of a plasmid in the unicellular cyanobacterium Synechocystis sp. PCC 6803. Surprisingly, integration of the oriC region into the chromosome of Anabaena PCC 7120 through homologous recombination led to much slower cell growth in the absence of a combined-nitrogen source and to multiple contiguous proheterocysts after prolonged incubation. Real-time RT-PCR showed that expression of two heterocyst-related genes, hetR and hetN, was altered in these strains: hetR expression remained high 48 h after induction, and hetN increased to high levels after induction for 12 h. These results suggest that the balance between oriC and DnaA could be important for heterocyst development.

  14. Nitrate and amino acid availability affects glycine betaine and mycosporine-2-glycine in response to changes of salinity in a halotolerant cyanobacterium Aphanothece halophytica.

    PubMed

    Waditee-Sirisattha, Rungaroon; Kageyama, Hakuto; Fukaya, Minoru; Rai, Vandna; Takabe, Teruhiro

    2015-12-01

    A halotolerant cyanobacterium Aphanothece halophytica thrives in extreme salinity with accumulation of a potent osmoprotectant glycine betaine. Recently, this cyanobacterium was shown to accumulate sunscreen molecule mycosporine-2-glycine significantly at high salinity. In this study, we investigated effects of nitrate and amino acid provision on the accumulation of glycine betaine and mycosporine-2-glycine. With elevated nitrate concentrations at high salinity, intracellular levels of both metabolites were enhanced. Six-fold high nitrate concentration increased the relative amounts of glycine betaine and mycosporine-2-glycine to be 1.5 and 2.0 folds compared with control condition : Increased levels were time- and dose-dependent manner. Exogenous supply of glycine/serine at high salinity resulted in the similar trends as observed in excess nitrate experiment. Intracellular level of glycine betaine increased ∼1.6 folds with glycine/serine supplementation. These supplementations also caused the increased level of mycosporine-2-glycine, namely 1.4 and 2 folds by glycine and serine, respectively. The transcription of glycine betaine and mycosporine-2-glycine biosynthetic genes was strongly induced under high-nitrate-salt condition. These results suggest the dependence of glycine betaine and mycosporine-2-glycine productions on substrate availability, and the effect of nitrate was possibly associated with stimulation of osmoprotectant increment in this extremophile.

  15. Polychromatic action spectrum for the induction of a mycosporine-like amino acid in a rice-field cyanobacterium, Anabaena sp.

    PubMed

    Sinha, R P; Sinha, J P; Gröniger, A; Häder, D-P

    2002-02-01

    A polychromatic action spectrum for the induction of an ultraviolet-absorbing/screening mycosporine-like amino acid (MAA) has been determined in a filamentous and heterocystous nitrogen-fixing rice-field cyanobacterium, Anabaena sp. High-performance liquid chromatographic (HPLC) studies revealed the presence of only one type of MAA, which was identified as shinorine, a bisubstituted MAA containing both glycine and serine groups having a retention time at 2.8 min and an absorption maximum at 334 nm. Exposure of cultures to simulated solar radiation in combination with various cut-off filters (WG 280, 295, 305, 320, 335, 345, GG 400, 420, 455, 475, OG 515, 530, 570, RG 645, 665 and a broad-band filter, UG 11) clearly revealed that the induction of the MAA takes place only in the UV range. Photosynthetic active radiation (PAR) had no significant impact on MAA induction. The ratio of the absorption at 334 nm (shinorine) to 665 nm (chlorophyll a) and the action spectrum also showed the induction of MAA to be UV dependent peaking in the UV-B range at around 290 nm. The results indicate that the studied cyanobacterium, Anabaena sp. may protect itself from deleterious short wavelength solar radiation by its ability to synthesize a mycosporine-like amino acid in response to UV-B radiation and thereby screen the negative effects of UV-B.

  16. Characterization of Function of the GlgA2 Glycogen/Starch Synthase in Cyanobacterium sp. Clg1 Highlights Convergent Evolution of Glycogen Metabolism into Starch Granule Aggregation.

    PubMed

    Kadouche, Derifa; Ducatez, Mathieu; Cenci, Ugo; Tirtiaux, Catherine; Suzuki, Eiji; Nakamura, Yasunori; Putaux, Jean-Luc; Terrasson, Amandine Durand; Diaz-Troya, Sandra; Florencio, Francisco Javier; Arias, Maria Cecilia; Striebeck, Alexander; Palcic, Monica; Ball, Steven G; Colleoni, Christophe

    2016-07-01

    At variance with the starch-accumulating plants and most of the glycogen-accumulating cyanobacteria, Cyanobacterium sp. CLg1 synthesizes both glycogen and starch. We now report the selection of a starchless mutant of this cyanobacterium that retains wild-type amounts of glycogen. Unlike other mutants of this type found in plants and cyanobacteria, this mutant proved to be selectively defective for one of the two types of glycogen/starch synthase: GlgA2. This enzyme is phylogenetically related to the previously reported SSIII/SSIV starch synthase that is thought to be involved in starch granule seeding in plants. This suggests that, in addition to the selective polysaccharide debranching demonstrated to be responsible for starch rather than glycogen synthesis, the nature and properties of the elongation enzyme define a novel determinant of starch versus glycogen accumulation. We show that the phylogenies of GlgA2 and of 16S ribosomal RNA display significant congruence. This suggests that this enzyme evolved together with cyanobacteria when they diversified over 2 billion years ago. However, cyanobacteria can be ruled out as direct progenitors of the SSIII/SSIV ancestral gene found in Archaeplastida. Hence, both cyanobacteria and plants recruited similar enzymes independently to perform analogous tasks, further emphasizing the importance of convergent evolution in the appearance of starch from a preexisting glycogen metabolism network.

  17. Characterization of Function of the GlgA2 Glycogen/Starch Synthase in Cyanobacterium sp. Clg1 Highlights Convergent Evolution of Glycogen Metabolism into Starch Granule Aggregation.

    PubMed

    Kadouche, Derifa; Ducatez, Mathieu; Cenci, Ugo; Tirtiaux, Catherine; Suzuki, Eiji; Nakamura, Yasunori; Putaux, Jean-Luc; Terrasson, Amandine Durand; Diaz-Troya, Sandra; Florencio, Francisco Javier; Arias, Maria Cecilia; Striebeck, Alexander; Palcic, Monica; Ball, Steven G; Colleoni, Christophe

    2016-07-01

    At variance with the starch-accumulating plants and most of the glycogen-accumulating cyanobacteria, Cyanobacterium sp. CLg1 synthesizes both glycogen and starch. We now report the selection of a starchless mutant of this cyanobacterium that retains wild-type amounts of glycogen. Unlike other mutants of this type found in plants and cyanobacteria, this mutant proved to be selectively defective for one of the two types of glycogen/starch synthase: GlgA2. This enzyme is phylogenetically related to the previously reported SSIII/SSIV starch synthase that is thought to be involved in starch granule seeding in plants. This suggests that, in addition to the selective polysaccharide debranching demonstrated to be responsible for starch rather than glycogen synthesis, the nature and properties of the elongation enzyme define a novel determinant of starch versus glycogen accumulation. We show that the phylogenies of GlgA2 and of 16S ribosomal RNA display significant congruence. This suggests that this enzyme evolved together with cyanobacteria when they diversified over 2 billion years ago. However, cyanobacteria can be ruled out as direct progenitors of the SSIII/SSIV ancestral gene found in Archaeplastida. Hence, both cyanobacteria and plants recruited similar enzymes independently to perform analogous tasks, further emphasizing the importance of convergent evolution in the appearance of starch from a preexisting glycogen metabolism network. PMID:27208262

  18. Changes in primary metabolism under light and dark conditions in response to overproduction of a response regulator RpaA in the unicellular cyanobacterium Synechocystis sp. PCC 6803

    PubMed Central

    Iijima, Hiroko; Shirai, Tomokazu; Okamoto, Mami; Kondo, Akihiko; Hirai, Masami Yokota; Osanai, Takashi

    2015-01-01

    The study of the primary metabolism of cyanobacteria in response to light conditions is important for environmental biology because cyanobacteria are widely distributed among various ecological niches. Cyanobacteria uniquely possess circadian rhythms, with central oscillators consisting from three proteins, KaiA, KaiB, and KaiC. The two-component histidine kinase SasA/Hik8 and response regulator RpaA transduce the circadian signal from KaiABC to control gene expression. Here, we generated a strain overexpressing rpaA in a unicellular cyanobacterium Synechocystis sp. PCC 6803. The rpaA-overexpressing strain showed pleiotropic phenotypes, including slower growth, aberrant degradation of an RNA polymerase sigma factor SigE after the light-to-dark transition, and higher accumulation of sugar catabolic enzyme transcripts under dark conditions. Metabolome analysis revealed delayed glycogen degradation, decreased sugar phosphates and organic acids in the tricarboxylic acid cycle, and increased amino acids under dark conditions. The current results demonstrate that in this cyanobacterium, RpaA is a regulator of primary metabolism and involved in adaptation to changes in light conditions. PMID:26379657

  19. Elucidation of Insertion Elements Carried on Plasmids and In Vitro Construction of Shuttle Vectors from the Toxic Cyanobacterium Planktothrix

    PubMed Central

    Christiansen, Guntram; Goesmann, Alexander

    2014-01-01

    Several gene clusters that are responsible for toxin synthesis in bloom-forming cyanobacteria have been found to be associated with transposable elements (TEs). In particular, insertion sequence (IS) elements were shown to play a role in the inactivation or recombination of the genes responsible for cyanotoxin synthesis. Plasmids have been considered important vectors of IS element distribution to the host. In this study, we aimed to elucidate the IS elements propagated on the plasmids and the chromosome of the toxic cyanobacterium Planktothrix agardhii NIVA-CYA126/8 by means of high-throughput sequencing. In total, five plasmids (pPA5.5, pPA14, pPA50, pPA79, and pPA115, of 5, 6, 50, 79, and 120 kbp, respectively) were elucidated, and two plasmids (pPA5.5, pPA115) were found to propagate full IS element copies. Large stretches of shared DNA information between plasmids were constituted of TEs. Two plasmids (pPA5.5, pPA14) were used as candidates to engineer shuttle vectors (named pPA5.5SV and pPA14SV, respectively) in vitro by PCR amplification and the subsequent transposition of the Tn5 cat transposon containing the R6Kγ origin of replication of Escherichia coli. While pPA5.5SV was found to be fully segregated, pPA14SV consistently co-occurred with its wild-type plasmid even under the highest selective pressure. Interestingly, the Tn5 cat transposon became transferred by homologous recombination into another plasmid, pPA50. The availability of shuttle vectors is considered to be of relevance in investigating genome plasticity as a consequence of homologous recombination events. Combining the potential of high-throughput sequencing and in vitro production of shuttle vectors makes it simple to produce species-specific shuttle vectors for many cultivable prokaryotes. PMID:24907328

  20. PSP toxin release from the cyanobacterium Raphidiopsis brookii D9 (Nostocales) can be induced by sodium and potassium ions.

    PubMed

    Soto-Liebe, Katia; Méndez, Marco A; Fuenzalida, Loreto; Krock, Bernd; Cembella, Allan; Vásquez, Mónica

    2012-12-01

    Paralytic shellfish poisoning (PSP) toxins are a group of naturally occurring neurotoxic alkaloids produced among several genera of primarily freshwater cyanobacteria and marine dinoflagellates. Although saxitoxin (STX) and analogs are all potent Na(+) channel blockers in vertebrate cells, the functional role of these compounds for the toxigenic microorganisms is unknown. Based upon the known importance of monovalent cations (such as sodium) in the maintenance of cellular homeostasis and ion channel function, we examined the effect of high extracellular concentrations of these ions on growth, cellular integrity, toxin production and release to the external medium in the filamentous freshwater cyanobacterium, Raphidiopsis brookii D9; a gonyautoxins (GTX2/3) and STX producing toxigenic strain. We observed a toxin export in response to high (17 mM) NaCl and KCl concentrations in the growth medium that was not primarily related to osmotic stress effects, compared to the osmolyte mannitol. Addition of exogenous PSP toxins with the same compositional profile as the one produced by R. brookii D9 was able to partially mitigate this effect of high Na⁺ (17 mM). The PSP toxin biosynthetic gene cluster (sxt) in D9 has two genes (sxtF and sxtM) that encode for a MATE (multidrug and toxic compound extrusion) transporter. This protein family, represented by NorM in the bacterium Vibrio parahaemolyticus, confers resistance to multiple cationic toxic agents through Na⁺/drug antiporters. Conserved domains for Na⁺ and drug recognition have been described in NorM. For the D9 sxt cluster, the Na⁺ recognition domain is conserved in both SxtF and SxtM, but the drug recognition domain differs between them. These results suggest that PSP toxins are exported directly in response to the presence of monovalent cations (Na⁺, K⁺) at least at elevated concentrations. Thus, the presence of both genes in the sxt cluster from strain D9 can be explained as a selective recognition

  1. Proteomic Analysis of the Marine Cyanobacterium Synechococcus WH8102 and Implications for Estimates of the Cellular Iron Content

    NASA Astrophysics Data System (ADS)

    Saito, M. A.; Bertrand, E. M.; Bulygin, V.; Moran, D.; Waterbury, J. B.

    2008-12-01

    The proteome of the marine cyanobacterium Synechococcus WH8102 was analyzed by nanospray liquid chromatography mass spectrometry (nLC-MS) with two major goals: to provide a first examination of the relative abundance of the most abundant proteins in this important microbe and to provide the necessary mass spectra for future quantification of biogeochemically significant proteins. Analyses of 37 nLC-MS runs of whole cell tryptic digestions and SDS-PAGE gel separated tryptic digestions resulted in a total of 636 proteins identified, 376 identified with two or more tryptic peptides. The identifications used the Sequest algorithm with stringent data filters on 54003 observed peptides, 3066 of which were unique, with a false positive rate of 2.2%. These measured proteins represent ~ 25.2% (14.8% with >= 2 peptides) of the open reading frames (ORFs) in the genome, similar to or higher than the percentage found in other cyanobacterial proteome studies thus far. The relative abundance of the more abundant proteins in the proteome was examined using the exponentially modified protein abundance index from a single nLC-MS run that identified 372 proteins (14.7% of the ORFs) from 7743 observed peptides (1224 unique peptides). Estimates of the relative abundance showed the photosynthesis and respiration category contributing approximately 32% of the total detected protein, hypothetical proteins contributing about 16%, and translation about 12%. Of biogeochemical interest, multiple types of nitrogen assimilation systems were observed to be simultaneously expressed as proteins, only 5 of the 21 B12 biosynthesis proteins were identified likely due to low abundance, and the metalloproteins metallothionein and nickel superoxide dismutase were relatively abundant. In contrast to previous predictions of a high photosystem I: photosystem II ratio of approximately 3 in the cyanobacteria and a resultant high cellular iron content, the ratio of the average relative abundances of all

  2. Combined effects of CO2 and light on the N2-fixing cyanobacterium Trichodesmium IMS101: physiological responses.

    PubMed

    Kranz, Sven A; Levitan, Orly; Richter, Klaus-Uwe; Prásil, Ondrej; Berman-Frank, Ilana; Rost, Björn

    2010-09-01

    Recent studies on the diazotrophic cyanobacterium Trichodesmium erythraeum (IMS101) showed that increasing CO(2) partial pressure (pCO(2)) enhances N(2) fixation and growth. Significant uncertainties remain as to the degree of the sensitivity to pCO(2), its modification by other environmental factors, and underlying processes causing these responses. To address these questions, we examined the responses of Trichodesmium IMS101 grown under a matrix of low and high levels of pCO(2) (150 and 900 microatm) and irradiance (50 and 200 micromol photons m(-2) s(-1)). Growth rates as well as cellular carbon and nitrogen contents increased with increasing pCO(2) and light levels in the cultures. The pCO(2)-dependent stimulation in organic carbon and nitrogen production was highest under low light. High pCO(2) stimulated rates of N(2) fixation and prolonged the duration, while high light affected maximum rates only. Gross photosynthesis increased with light but did not change with pCO(2). HCO(3)(-) was identified as the predominant carbon source taken up in all treatments. Inorganic carbon uptake increased with light, but only gross CO(2) uptake was enhanced under high pCO(2). A comparison between carbon fluxes in vivo and those derived from (13)C fractionation indicates high internal carbon cycling, especially in the low-pCO(2) treatment under high light. Light-dependent oxygen uptake was only detected under low pCO(2) combined with high light or when low-light-acclimated cells were exposed to high light, indicating that the Mehler reaction functions also as a photoprotective mechanism in Trichodesmium. Our data confirm the pronounced pCO(2) effect on N(2) fixation and growth in Trichodesmium and further show a strong modulation of these effects by light intensity. We attribute these responses to changes in the allocation of photosynthetic energy between carbon acquisition and the assimilation of carbon and nitrogen under elevated pCO(2). These findings are supported by a

  3. Rapid turnover of a component required for photosynthesis explains temperature dependence and kinetics of photoinhibition in a cyanobacterium, Synechococcus 6301.

    PubMed

    Wünschmann, G; Brand, J J

    1992-02-01

    Illumination of a liquid culture of Synechococcus 6301 at high photon flux density (PFD) elicits a time-dependent first-order exponential decline in relative quantum yield of photosynthetic O2 evolution to some steady-state value. Full photosynthetic activity is restored, also as a time-dependent first-order process, when the photoinhibited culture is transferred to lower PFD. Temperature and irradiation dependence of photoinhibition were measured under conditions which precluded simultaneous recovery from photoinhibition. Also the temperature and irradiation dependence of recovery from photoinhibition were determined under conditions which precluded simultaneous photoinhibition. Kinetics of photoinhibition were sensitive to PFD but relatively independent of temperature. Kinetics of recovery saturated at low PFD but were very temperature dependent at all PFDs. A general equation can be written to predict the change in photosynthetic activity versus time when a cell culture is placed at photoinhibitory PFD, assuming that first-order exponential photoinhibition and first-order exponential recovery from photoinhibition occur simultaneously. The equation can be made specific if the values of the kinetic constant for photoinhibition and for recovery from photoinhibition are known for the particular environmental conditions to which the cells are exposed. These values can be obtained by independently measuring the kinetics of photoinhibition without simultaneous recovery and the kinetics of recovery without simultaneous photoinhibition. The curve of photosynthetic activity versus time for cells placed at high PFD, which is predicted by this equation, precisely fits the experimentally determined kinetics of photoinhibition. This correlation remains valid over a wide range of temperatures and PFDs. Identical results were obtained with the marine cyanobacterium Synechococcus 7002. We conclude that the extent of net photoinhibition over a broad range of conditions represents

  4. Biochemical and spectroscopic characterization of a new oxygen-evolving photosystem II core complex from the cyanobacterium Synechocystis PCC 6803.

    PubMed

    Tang, X S; Diner, B A

    1994-04-19

    We describe here a new procedure permitting rapid (12-13 h) isolation of a pure oxygen-evolving photosystem II (PSII) core complex from the cyanobacterium Synechocystis PCC 6803. This procedure involves dodecyl maltoside extraction of thylakoid membranes followed by single-step column chromatography using a weak anion-exchanger. SDS-PAGE and immunoblotting show that the complex consists of five intrinsic membrane proteins (CP47, CP43, D1, D1, and cyt b559), one extrinsic protein (MSP), and one unknown protein with a molecular mass of approximately 26 kDa. A chemical and functional analysis, normalized to 2 molecules of pheophytin a, indicates that this PSII core complex contains 1 photoactive plastoquinone, QA, 4 manganese atoms, 38 chlorophyll a molecules, 1 cytochrome b559, 2 plastoquinone-9, and 9-10 beta-carotenes. The complex exhibits high rates of oxygen evolution, typically 2400-2600 mumol of O2 (mg of Chl)-1 h-1 in the presence of 2,5-dichlorobenzoquinone as an artificial electron acceptor with a pH optimum of 6.5. A strong light minus dark multiline EPR signal, arising from the S2 state of the oxygen-evolving complex (OEC), is observed at 10 K following illumination at 198 K. The determination of the absolute oxygen yield per saturating microsecond flash indicates that essentially all of the PSII centers contain functional oxygen-evolving complexes. This point is further supported by the absence of photoaccumulation, upon room temperature illumination, of the immediate oxidant of the OEC, redox-active tyrosine, YZ.. On the basis of EPR spectra, oxidized minus reduced difference spectra, and SDS-PAGE, the preparation contains on a per mole basis with PSII only trace amounts of PSI (approximately 0.04), cytochrome b6/f complex (< or = 0.01), and ATPase (< or = 0.05). All of these results indicate that this PSII preparation is to date the most highly purified oxygen-evolving core complex from Synechocystis 6803 that retains all of the reaction centers active

  5. Na/sup +/ requirement for growth, photosynthesis, and pH regulation of the alkalotolerant cyanobacterium Synechococcus leopoliensis

    SciTech Connect

    Miller, A.G.; Turpin, D.H.; Canvin, D.T.

    1984-07-01

    It was found that Na/sup +/ is required for all the alkalotolerance of the cyanobacterium Synechococcus leopoliensis. Cell division did not occur at any pH in the absence of Na/sup +/, but cells inoculated into Na/sup +/-free growth medium at pH 6.8 did continue metabolic activity, and over a period of 48 h, the cells became twice their normal size. Many of these cells remained viable for at least 59 h and formed colonies on Na/sup +/-containing medium. Cells grown in the presence of Na/sup +/ and inoculated into Na/sup +/-free growth medium at pH 9.6 rapidly lost viability. An Na/sup +/ concentration of ca. 0.5 milliequivalents x liter/sup -1/ was required for sustained growth above pH 9.0. The Na/sup +/ requirement could be only partially met by Li/sup +/ and not at all by K/sup +/ or Rb/sup +/. Cells incubated in darkness in growth medium at pH 6.8 had an intracellular pH near neutrality in the presence or absence of Na/sup +/. When the external pH was shifted to 9.6, only cells in the presence of Na/sup +/ were able to maintain an intracellular pH near 7.0. The membrane potential, however, remained high (-120mV) in the absence or presence of Na/sup +/ unless collapsed by the addition of gramicidin. Thus, the inability to maintain a neutral intracellular pH at pH 9.6 in the absence of Na/sup +/ was not due to a generalized disruption of membrane integrity. Even cells containing Na/sup +/ still required added Na/sup +/ to restore photosynthetic rates to normal after the cells had been washed in Na/sup +/-free buffer at pH 9.6. This requirement was only partially met by Li/sup +/ and was not met at all by K/sup +/, Rb/sup +/, Cs/sup +/, Mg/sup 2 +/, or Ca/sup 2 +/. The restoration of photosynthesis by added Na/sup +/ occurred within 30 s and suggests a role for extracellular Na/sup +/. Part of our results can be explained in terms of the operation of an Na/sup +//H/sup +/ antiporter activity in the plasma membrane, but some results would seem to require other

  6. Kinetic Modeling of Arsenic Cycling by a Freshwater Cyanobacterium as Influenced by N:P Ratios: A Potential Biologic Control in an Iron-Limited Drainage Basin

    NASA Astrophysics Data System (ADS)

    Markley, C. T.; Herbert, B. E.

    2004-12-01

    Elevated As levels are common in South Texas surface waters, where As is derived from the natural weathering of geogenic sources and a byproduct of historical uranium mining. The impacted surface waters of the Nueces River drainage basin supply Lake Corpus Christi (LCC), a major drinking water reservoir for the Corpus Christi area. The soils and sediments of the Nueces River drainage basin generally have low levels of reactive iron (average concentration of 2780 mg/kg), limiting the control of iron oxyhydroxides on As geochemistry and bioavailability. Given these conditions, biologic cycling of As may have a large influence on As fate and transport in LCC. Sediment cores from LCC show evidence for cyanobacterial blooms after reservoir formation based upon stable isotopes, total organic matter and specific elemental correlations. While algae have been shown to accumulate and reduce inorganic As(V), few studies have reported biologic cycling of As by cyanobacteria. Therefore, As(V) uptake, accumulation, reduction, and excretion in a 1.0 μ M As(V) solution by the freshwater cyanobacterium, Anabaena sp. Strain PCC 7120, was measured over time as a function of low, middle and high N:P ratios (1.2, 12, 120) to determine nutrient effects on As cycling by the cyanobacterium. Total As(V) reduction was observed in all three conditions upon completion of the ten-day experiment. Maximum As(V) reduction rates ranged from (0.013 mmol g C-1 day-1) in the low N:P solution to (0.398 mmol g C-1 day-1) in the high N:P solution. Increased cell biomass in the low N:P ratio solution compensated for the low maximum reduction rate to allow total As(V) reduction. Kinetic equations commonly used to model algal-nutrient interactions were utilized in modeling the current data. The Michaelis-Menten enzyme saturation equation modified with a competitive inhibition term adequately modeled As(III) excretion in the high and middle N:P ratio test conditions. The low N:P test condition further

  7. Looking at the stability of life-support microorganisms in space : the MELGEN activity highlights the cyanobacterium Arthrospira sp. PCC8005

    NASA Astrophysics Data System (ADS)

    Morin, Nicolas

    The MELGEN activity (MELiSSA Genetic Stability Study) mainly covers the molecular aspects of the regenerative life-support system MELiSSA (Micro-Ecological Life Support System Alternative) of the European Space Agency (ESA). The general objective of MELGEN is to establish and validate methods and the related hardware in order to detect genetic instability and microbial contaminants in the MELISSA compartments. This includes (1) a genetic description of the MELISSA strains, (2) studies of microbial behavior and genetic stability in bioreactors and (3) the detection of chemical, genetical and biological contamination and their effect on microbial metabolism. Selected as oxygen producer and complementary food source, the cyanobacterium Arthrospira sp. PCC8005 plays a major role within the MELiSSA loop. As the genomic information on this organism was insufficient, sequencing of its genome was proposed at the French National Sequencing Center, Genoscope, as a joint effort between ESA and different laboratories. So far, a preliminary assembly of 16 contigs representing circa 6.3 million basepairs was obtained. Even though the finishing of the genome is on its way, automatic annotation of the contigs has already been performed on the MaGe annotation platform, and curation of the sequence is currently being carried out, with a special focus on biosynthesis pathways, photosynthesis, and maintenance processes of the cell. According to the index of repetitiveness described by Haubold and Wiehe (2006), we discovered that the genome of Arthrospira sp. is among the 50 most repeated bacterial genomes sequenced to date. Thanks to the sequencing project, we have identified and catalogued mobile genetics elements (MGEs) dispersed throughout the unique chromosome of this cyanobacterium. They represent a quite large proportion of the genome, as genes identified as putative transposases are indeed found in circa 5 Results : We currently have a first draft of the complete genome of

  8. Investigation and modeling of biomass decay rate in the dark and its potential influence on net productivity of solar photobioreactors for microalga Chlamydomonas reinhardtii and cyanobacterium Arthrospira platensis.

    PubMed

    Le Borgne, François; Pruvost, Jérémy

    2013-06-01

    Biomass decay rate (BDR) in the dark was investigated for Chlamydomonas reinhardtii (microalga) and Arthrospira platensis (cyanobacterium). A specific setup based on a torus photobioreactor with online gas analysis was validated, enabling us to follow the time course of the specific BDR using oxygen monitoring and mass balance. Various operating parameters that could limit respiration rates, such as culture temperature and oxygen deprivation, were then investigated. C. reinhardtii was found to present a higher BDR in the dark than A. platensis, illustrating here the difference between eukaryotic and prokaryotic cells. In both cases, temperature proved an influential parameter, and the Arrhenius law was found to efficiently relate specific BDR to culture temperature. The utility of decreasing temperature at night to increase biomass productivity in a solar photobioreactor is also illustrated.

  9. Genetic Manipulation of the Cyanobacterium Synechocystis sp. PCC 6803 (Development of Strains Lacking Photosystem I for the Analysis of Mutations in Photosystem II).

    PubMed Central

    Smart, L. B.; Bowlby, N. R.; Anderson, S. L.; Sithole, I.; McIntosh, L.

    1994-01-01

    We have taken a genetic approach to eliminating the presence of photosystem I (PSI) in site-directed mutants of photosystem II (PSII) in the cyanobacterium Synechocystis sp. PCC 6803. By selecting under light-activated heterotrophic conditions, we have inactivated the psaA-psaB operon encoding the PSI reaction center proteins in cells containing deletions of the three psbA genes. We have also introduced deletions into both copies of psbD in a strain containing a mutation that inactivates psaA (ADK9). These strains, designated D1-/PSI- and D2-/PSI-, may serve as recipient strains for the incorporation of site-directed mutations in either psbA2 or psbD1. The characterization of these cells, which lack both PSI and PSII, is described. PMID:12232086

  10. Role of the all1549 (ana-rsh) gene, a relA/spoT homolog, of the Cyanobacterium Anabaena sp. PCC7120.

    PubMed

    Ning, Degang; Qian, Yaru; Miao, Xiaogang; Wen, Chongwei

    2011-06-01

    The role of a single relA/spoT homolog all1549 (designated hereafter as ana-rsh) of the cyanobacterium Anabaena sp. PCC7120 was investigated. The complementation test in Escherichia coli showed that the protein encoded by ana-rsh possesses guanosine tetraphosphate (p)ppGpp-synthase/hydrolase activity. Under laboratory growth conditions, a low level of ppGpp was detected in Anabaena sp. PCC7120 and the loss of ana-rsh was lethal. Amino acid starvation induced ppGpp accumulation to an appropriate level, and nitrogen deficiency did not alter the ppGpp concentration in Anabaena cells. These data suggest that ana-rsh is required for cell viability under normal growth conditions and involved in the (p)ppGpp-related stringent response to amino acid deprivation, but not related to heterocyst formation and nitrogen fixation of Anabaena sp. PCC7120.

  11. Involvement of thioredoxin on the scaffold activity of NifU in heterocyst cells of the diazotrophic cyanobacterium Anabaena sp. strain PCC 7120.

    PubMed

    Nomata, Jiro; Maeda, Maki; Isu, Atsuko; Inoue, Kazuhito; Hisabori, Toru

    2015-09-01

    The diazotrophic cyanobacterium Anabaena sp. strain PCC 7120 (A.7120) differentiates into specialized heterocyst cells that fix nitrogen under nitrogen starvation conditions. Although reducing equivalents are essential for nitrogen fixation, little is known about redox systems in heterocyst cells. In this study, we investigated thioredoxin (Trx) networks in Anabaena using TrxM, and identified 16 and 38 candidate target proteins in heterocysts and vegetative cells, respectively, by Trx affinity chromatography (Motohashi et al. (Comprehensive survey of proteins targeted by chloroplast thioredoxin. Proc Natl Acad Sci USA, 2001; 98: , 11224-11229)). Among these, the Fe-S cluster scaffold protein NifU that facilitates functional expression of nitrogenase in heterocysts was found to be a potential TrxM target. Subsequently, we observed that the scaffold activity of N-terminal catalytic domain of NifU is enhanced in the presence of Trx-system, suggesting that TrxM is involved in the Fe-S cluster biogenesis.

  12. A quantitative evaluation of ethylene production in the recombinant cyanobacterium Synechocystis sp. PCC 6803 harboring the ethylene-forming enzyme by membrane inlet mass spectrometry.

    PubMed

    Zavřel, Tomáš; Knoop, Henning; Steuer, Ralf; Jones, Patrik R; Červený, Jan; Trtílek, Martin

    2016-02-01

    The prediction of the world's future energy consumption and global climate change makes it desirable to identify new technologies to replace or augment fossil fuels by environmentally sustainable alternatives. One appealing sustainable energy concept is harvesting solar energy via photosynthesis coupled to conversion of CO2 into chemical feedstock and fuel. In this work, the production of ethylene, the most widely used petrochemical produced exclusively from fossil fuels, in the model cyanobacterium Synechocystis sp. PCC 6803 is studied. A novel instrumentation setup for quantitative monitoring of ethylene production using a combination of flat-panel photobioreactor coupled to a membrane-inlet mass spectrometer is introduced. Carbon partitioning is estimated using a quantitative model of cyanobacterial metabolism. The results show that ethylene is produced under a wide range of light intensities with an optimum at modest irradiances. The results allow production conditions to be optimized in a highly controlled setup. PMID:26708481

  13. Isolation and purification of an axenic diazotrophic drought-tolerant cyanobacterium, Nostoc commune, from natural cyanobacterial crusts and its utilization for field research on soils polluted with radioisotopes.

    PubMed

    Katoh, Hiroshi; Furukawa, Jun; Tomita-Yokotani, Kaori; Nishi, Yasuaki

    2012-08-01

    Nitrogen fixation and drought tolerance confer the ability to grow on dry land, and some terrestrial cyanobacteria exhibit these properties. These cyanobacteria were isolated in an axenic form from Nostoc commune clusters and other sources by modifying the method used to isolate the nitrogen-fixing and drought-tolerant cyanobacterium Nostoc sp. HK-01. Of these cyanobacteria, N. commune, which is difficult to isolate and purify, uses polysaccharides to maintain water, nitrogen fertilizers for nitrogen fixation, and can live in extreme environments because of desiccation tolerance. In this study, we examined the use of N. commune as biosoil for space agriculture and possible absorption of radioisotopes ((134)Cs, (137)Cs). This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial.

  14. Regulation of Genes Involved in Heterocyst Differentiation in the Cyanobacterium Anabaena sp. Strain PCC 7120 by a Group 2 Sigma Factor SigC.

    PubMed

    Ehira, Shigeki; Miyazaki, Shogo

    2015-01-01

    The filamentous cyanobacterium Anabaena sp. strain PCC 7120 differentiates specialized cells for nitrogen fixation called heterocysts upon limitation of combined nitrogen in the medium. During heterocyst differentiation, expression of approximately 500 genes is upregulated with spatiotemporal regulation. In the present study, we investigated the functions of sigma factors of RNA polymerase in the regulation of heterocyst differentiation. The transcript levels of sigC, sigE, and sigG were increased during heterocyst differentiation, while expression of sigJ was downregulated. We carried out DNA microarray analysis to identify genes regulated by SigC, SigE, and SigG. It was indicated that SigC regulated the expression of genes involved in heterocyst differentiation and functions. Moreover, genes regulated by SigC partially overlapped with those regulated by SigE, and deficiency of SigC was likely to be compensated by SigE. PMID:25692906

  15. Efficiency of photosynthesis in a Chl d-utilizing cyanobacterium is comparable to or higher than that in Chl a-utilizing oxygenic species.

    PubMed

    Mielke, S P; Kiang, N Y; Blankenship, R E; Gunner, M R; Mauzerall, D

    2011-09-01

    The cyanobacterium Acaryochloris marina uses chlorophyll d to carry out oxygenic photosynthesis in environments depleted in visible and enhanced in lower-energy, far-red light. However, the extent to which low photon energies limit the efficiency of oxygenic photochemistry in A. marina is not known. Here, we report the first direct measurements of the energy-storage efficiency of the photosynthetic light reactions in A. marina whole cells, and find it is comparable to or higher than that in typical, chlorophyll a-utilizing oxygenic species. This finding indicates that oxygenic photosynthesis is not fundamentally limited at the photon energies employed by A. marina, and therefore is potentially viable in even longer-wavelength light environments.

  16. Efficiency of Photosynthesis in a Chl d-Utilizing Cyanobacterium is Comparable to or Higher than that in Chl a-Utilizing Oxygenic Species

    NASA Technical Reports Server (NTRS)

    Mielke, S. P.; Kiang, N. Y.; Blankenship, R. E.; Gunner, M. R.; Mauzerall, D.

    2011-01-01

    The cyanobacterium Acaryochloris marina uses chlorophyll d to carry out oxygenic photosynthesis in environments depleted in visible and enhanced in lower-energy, far-red light. However, the extent to which low photon energies limit the efficiency of oxygenic photochemistry in A. marina is not known. Here, we report the first direct measurements of the energy-storage efficiency of the photosynthetic light reactions in A. marina whole cells,and find it is comparable to or higher than that in typical, chlorophyll a-utilizing oxygenic species. This finding indicates that oxygenic photosynthesis is not fundamentally limited at the photon energies employed by A. marina, and therefore is potentially viable in even longer-wavelength light environments.

  17. A quantitative evaluation of ethylene production in the recombinant cyanobacterium Synechocystis sp. PCC 6803 harboring the ethylene-forming enzyme by membrane inlet mass spectrometry.

    PubMed

    Zavřel, Tomáš; Knoop, Henning; Steuer, Ralf; Jones, Patrik R; Červený, Jan; Trtílek, Martin

    2016-02-01

    The prediction of the world's future energy consumption and global climate change makes it desirable to identify new technologies to replace or augment fossil fuels by environmentally sustainable alternatives. One appealing sustainable energy concept is harvesting solar energy via photosynthesis coupled to conversion of CO2 into chemical feedstock and fuel. In this work, the production of ethylene, the most widely used petrochemical produced exclusively from fossil fuels, in the model cyanobacterium Synechocystis sp. PCC 6803 is studied. A novel instrumentation setup for quantitative monitoring of ethylene production using a combination of flat-panel photobioreactor coupled to a membrane-inlet mass spectrometer is introduced. Carbon partitioning is estimated using a quantitative model of cyanobacterial metabolism. The results show that ethylene is produced under a wide range of light intensities with an optimum at modest irradiances. The results allow production conditions to be optimized in a highly controlled setup.

  18. Adaptation of a Cyanobacterium to a Biochemically Rich Environment in Experimental Evolution as an Initial Step toward a Chloroplast-Like State

    PubMed Central

    Suzuki, Shingo; Miyazaki, Mikako; Takikawa, Go; Sakurai, Takahiro; Kashiwagi, Akiko; Sueyoshi, Makoto; Matsumoto, Yusuke; Kiuchi, Ayako; Mori, Kotaro; Yomo, Tetsuya

    2014-01-01

    Chloroplasts originated from cyanobacteria through endosymbiosis. The original cyanobacterial endosymbiont evolved to adapt to the biochemically rich intracellular environment of the host cell while maintaining its photosynthetic function; however, no such process has been experimentally demonstrated. Here, we show the adaptation of a model cyanobacterium, Synechocystis sp. PCC 6803, to a biochemically rich environment by experimental evolution. Synechocystis sp. PCC 6803 does not grow in a biochemically rich, chemically defined medium because several amino acids are toxic to the cells at approximately 1 mM. We cultured the cyanobacteria in media with the toxic amino acids at 0.1 mM, then serially transferred the culture, gradually increasing the concentration of the toxic amino acids. The cells evolved to show approximately the same specific growth rate in media with 0 and 1 mM of the toxic amino acid in approximately 84 generations and evolved to grow faster in the media with 1 mM than in the media with 0 mM in approximately 181 generations. We did not detect a statistically significant decrease in the autotrophic growth of the evolved strain in an inorganic medium, indicating the maintenance of the photosynthetic function. Whole-genome resequencing revealed changes in the genes related to the cell membrane and the carboxysome. Moreover, we quantitatively analyzed the evolutionary changes by using simple mathematical models, which evaluated the evolution as an increase in the half-maximal inhibitory concentration (IC50) and estimated quantitative characteristics of the evolutionary process. Our results clearly demonstrate not only the potential of a model cyanobacterium to adapt to a biochemically rich environment without a significant decrease in photosynthetic function but also the properties of its evolutionary process, which sheds light of the evolution of chloroplasts at the initial stage. PMID:24874568

  19. Inactivation of agmatinase expressed in vegetative cells alters arginine catabolism and prevents diazotrophic growth in the heterocyst-forming cyanobacterium Anabaena.

    PubMed

    Burnat, Mireia; Flores, Enrique

    2014-10-01

    Arginine decarboxylase produces agmatine, and arginase and agmatinase are ureohydrolases that catalyze the production of ornithine and putrescine from arginine and agmatine, respectively, releasing urea. In the genome of the filamentous, heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120, ORF alr2310 putatively encodes an ureohydrolase. Cells of Anabaena supplemented with [(14) C]arginine took up and catabolized this amino acid generating a set of labeled amino acids that included ornithine, proline, and glutamate. In an alr2310 deletion mutant, an agmatine spot appeared and labeled glutamate increased with respect to the wild type, suggesting that Alr2310 is an agmatinase rather than an arginase. As determined in cell-free extracts, agmatinase activity could be detected in the wild type but not in the mutant. Thus, alr2310 is the Anabaena speB gene encoding agmatinase. The ∆alr2310 mutant accumulated large amounts of cyanophycin granule polypeptide, lacked nitrogenase activity, and did not grow diazotrophically. Growth tests in solid media showed that agmatine is inhibitory for Anabaena, especially under diazotrophic conditions, suggesting that growth of the mutant is inhibited by non-metabolized agmatine. Measurements of incorporation of radioactivity from [(14) C]leucine into macromolecules showed, however, a limited inhibition of protein synthesis in the ∆alr2310 mutant. Analysis of an Anabaena strain producing an Alr2310-GFP (green fluorescent protein) fusion showed expression in vegetative cells but much less in heterocysts, implying compartmentalization of the arginine decarboxylation pathway in the diazotrophic filaments of this heterocyst-forming cyanobacterium.

  20. Detection of reactive oxygen species (ROS) by the oxidant-sensing probe 2',7'-dichlorodihydrofluorescein diacetate in the cyanobacterium Anabaena variabilis PCC 7937

    SciTech Connect

    Rastogi, Rajesh P.; Singh, Shailendra P.; Haeder, Donat-P.; Sinha, Rajeshwar P.

    2010-07-02

    The generation of reactive oxygen species (ROS) under simulated solar radiation (UV-B: 0.30 Wm{sup -2}, UV-A: 25.70 Wm{sup -2} and PAR: 118.06 Wm{sup -2}) was studied in the cyanobacterium Anabaena variabilis PCC 7937 using the oxidant-sensing fluorescent probe 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA). DCFH-DA is a nonpolar dye, converted into the polar derivative DCFH by cellular esterases that are nonfluorescent but switched to highly fluorescent DCF when oxidized by intracellular ROS and other peroxides. The images obtained from the fluorescence microscope after 12 h of irradiation showed green fluorescence from cells covered with 295, 320 or 395 nm cut-off filters, indicating the generation of ROS in all treatments. However, the green/red fluorescence ratio obtained from fluorescence microscopic analysis showed the highest generation of ROS after UV-B radiation in comparison to PAR or UV-A radiation. Production of ROS was also measured by a spectrofluorophotometer and results obtained supported the results of fluorescence microscopy. Low levels of ROS were detected at the start (0 h) of the experiment showing that they are generated even during normal metabolism. This study also showed that UV-B radiation causes the fragmentation of the cyanobacterial filaments which could be due to the observed oxidative stress. This is the first report for the detection of intracellular ROS in a cyanobacterium by fluorescence microscopy using DCFH-DA and thereby suggesting the applicability of this method in the study of in vivo generation of ROS.

  1. Adaptation of a cyanobacterium to a biochemically rich environment in experimental evolution as an initial step toward a chloroplast-like state.

    PubMed

    Hosoda, Kazufumi; Habuchi, Masumi; Suzuki, Shingo; Miyazaki, Mikako; Takikawa, Go; Sakurai, Takahiro; Kashiwagi, Akiko; Sueyoshi, Makoto; Matsumoto, Yusuke; Kiuchi, Ayako; Mori, Kotaro; Yomo, Tetsuya

    2014-01-01

    Chloroplasts originated from cyanobacteria through endosymbiosis. The original cyanobacterial endosymbiont evolved to adapt to the biochemically rich intracellular environment of the host cell while maintaining its photosynthetic function; however, no such process has been experimentally demonstrated. Here, we show the adaptation of a model cyanobacterium, Synechocystis sp. PCC 6803, to a biochemically rich environment by experimental evolution. Synechocystis sp. PCC 6803 does not grow in a biochemically rich, chemically defined medium because several amino acids are toxic to the cells at approximately 1 mM. We cultured the cyanobacteria in media with the toxic amino acids at 0.1 mM, then serially transferred the culture, gradually increasing the concentration of the toxic amino acids. The cells evolved to show approximately the same specific growth rate in media with 0 and 1 mM of the toxic amino acid in approximately 84 generations and evolved to grow faster in the media with 1 mM than in the media with 0 mM in approximately 181 generations. We did not detect a statistically significant decrease in the autotrophic growth of the evolved strain in an inorganic medium, indicating the maintenance of the photosynthetic function. Whole-genome resequencing revealed changes in the genes related to the cell membrane and the carboxysome. Moreover, we quantitatively analyzed the evolutionary changes by using simple mathematical models, which evaluated the evolution as an increase in the half-maximal inhibitory concentration (IC50) and estimated quantitative characteristics of the evolutionary process. Our results clearly demonstrate not only the potential of a model cyanobacterium to adapt to a biochemically rich environment without a significant decrease in photosynthetic function but also the properties of its evolutionary process, which sheds light of the evolution of chloroplasts at the initial stage.

  2. Homologous regulators, CnfR1 and CnfR2, activate expression of two distinct nitrogenase gene clusters in the filamentous cyanobacterium Anabaena variabilis ATCC 29413.

    PubMed

    Pratte, Brenda S; Thiel, Teresa

    2016-06-01

    The cyanobacterium Anabaena variabilis has two Mo-nitrogenases that function under different environmental conditions in different cell types. The heterocyst-specific nitrogenase encoded by the large nif1 gene cluster and the similar nif2 gene cluster that functions under anaerobic conditions in vegetative cells are under the control of the promoter for the first gene of each cluster, nifB1 or nifB2 respectively. Associated with each of these clusters is a putative regulatory gene called cnfR (patB) whose product has a C-terminal HTH domain and an N-terminal ferredoxin-like domain. CnfR1 activates nifB1 expression in heterocysts, while CnfR2 activates nifB2 expression. A cnfR1 mutant was unable to make nitrogenase under aerobic conditions in heterocysts while the cnfR2 mutant was unable to make nitrogenase under anaerobic conditions. Mutations in cnfR1 and cnfR2 reduced transcripts for the nif1 and nif2 genes respectively. The closely related cyanobacterium, Anabaena sp. PCC 7120 has the nif1 system but lacks nif2. Expression of nifB2:lacZ from A. variabilis in anaerobic vegetative cells of Anabaena sp. PCC 7120 depended on the presence of cnfR2. This suggests that CnfR2 is necessary and sufficient for activation of the nifB2 promoter and that the CnfR1/CnfR2 family of proteins are the primary activators of nitrogenase gene expression in cyanobacteria. PMID:26950042

  3. Inactivation of agmatinase expressed in vegetative cells alters arginine catabolism and prevents diazotrophic growth in the heterocyst-forming cyanobacterium Anabaena

    PubMed Central

    Burnat, Mireia; Flores, Enrique

    2014-01-01

    Arginine decarboxylase produces agmatine, and arginase and agmatinase are ureohydrolases that catalyze the production of ornithine and putrescine from arginine and agmatine, respectively, releasing urea. In the genome of the filamentous, heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120, ORF alr2310 putatively encodes an ureohydrolase. Cells of Anabaena supplemented with [14C]arginine took up and catabolized this amino acid generating a set of labeled amino acids that included ornithine, proline, and glutamate. In an alr2310 deletion mutant, an agmatine spot appeared and labeled glutamate increased with respect to the wild type, suggesting that Alr2310 is an agmatinase rather than an arginase. As determined in cell-free extracts, agmatinase activity could be detected in the wild type but not in the mutant. Thus, alr2310 is the Anabaena speB gene encoding agmatinase. The Δalr2310 mutant accumulated large amounts of cyanophycin granule polypeptide, lacked nitrogenase activity, and did not grow diazotrophically. Growth tests in solid media showed that agmatine is inhibitory for Anabaena, especially under diazotrophic conditions, suggesting that growth of the mutant is inhibited by non-metabolized agmatine. Measurements of incorporation of radioactivity from [14C]leucine into macromolecules showed, however, a limited inhibition of protein synthesis in the Δalr2310 mutant. Analysis of an Anabaena strain producing an Alr2310-GFP (green fluorescent protein) fusion showed expression in vegetative cells but much less in heterocysts, implying compartmentalization of the arginine decarboxylation pathway in the diazotrophic filaments of this heterocyst-forming cyanobacterium. PMID:25209059

  4. Acetylome analysis reveals the involvement of lysine acetylation in photosynthesis and carbon metabolism in the model cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Mo, Ran; Yang, Mingkun; Chen, Zhuo; Cheng, Zhongyi; Yi, Xingling; Li, Chongyang; He, Chenliu; Xiong, Qian; Chen, Hui; Wang, Qiang; Ge, Feng

    2015-02-01

    Cyanobacteria are the oldest known life form inhabiting Earth and the only prokaryotes capable of performing oxygenic photosynthesis. Synechocystis sp. PCC 6803 (Synechocystis) is a model cyanobacterium used extensively in research on photosynthesis and environmental adaptation. Posttranslational protein modification by lysine acetylation plays a critical regulatory role in both eukaryotes and prokaryotes; however, its extent and function in cyanobacteria remain unexplored. Herein, we performed a global acetylome analysis on Synechocystis through peptide prefractionation, antibody enrichment, and high accuracy LC-MS/MS analysis; identified 776 acetylation sites on 513 acetylated proteins; and functionally categorized them into an interaction map showing their involvement in various biological processes. Consistent with previous reports, a large fraction of the acetylation sites are present on proteins involved in cellular metabolism. Interestingly, for the first time, many proteins involved in photosynthesis, including the subunits of phycocyanin (CpcA, CpcB, CpcC, and CpcG) and allophycocyanin (ApcA, ApcB, ApcD, ApcE, and ApcF), were found to be lysine acetylated, suggesting that lysine acetylation may play regulatory roles in the photosynthesis process. Six identified acetylated proteins associated with photosynthesis and carbon metabolism were further validated by immunoprecipitation and Western blotting. Our data provide the first global survey of lysine acetylation in cyanobacteria and reveal previously unappreciated roles of lysine acetylation in the regulation of photosynthesis. The provided data set may serve as an important resource for the functional analysis of lysine acetylation in cyanobacteria and facilitate the elucidation of the entire metabolic networks and photosynthesis process in this model cyanobacterium.

  5. Inactivation of agmatinase expressed in vegetative cells alters arginine catabolism and prevents diazotrophic growth in the heterocyst-forming cyanobacterium Anabaena.

    PubMed

    Burnat, Mireia; Flores, Enrique

    2014-10-01

    Arginine decarboxylase produces agmatine, and arginase and agmatinase are ureohydrolases that catalyze the production of ornithine and putrescine from arginine and agmatine, respectively, releasing urea. In the genome of the filamentous, heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120, ORF alr2310 putatively encodes an ureohydrolase. Cells of Anabaena supplemented with [(14) C]arginine took up and catabolized this amino acid generating a set of labeled amino acids that included ornithine, proline, and glutamate. In an alr2310 deletion mutant, an agmatine spot appeared and labeled glutamate increased with respect to the wild type, suggesting that Alr2310 is an agmatinase rather than an arginase. As determined in cell-free extracts, agmatinase activity could be detected in the wild type but not in the mutant. Thus, alr2310 is the Anabaena speB gene encoding agmatinase. The ∆alr2310 mutant accumulated large amounts of cyanophycin granule polypeptide, lacked nitrogenase activity, and did not grow diazotrophically. Growth tests in solid media showed that agmatine is inhibitory for Anabaena, especially under diazotrophic conditions, suggesting that growth of the mutant is inhibited by non-metabolized agmatine. Measurements of incorporation of radioactivity from [(14) C]leucine into macromolecules showed, however, a limited inhibition of protein synthesis in the ∆alr2310 mutant. Analysis of an Anabaena strain producing an Alr2310-GFP (green fluorescent protein) fusion showed expression in vegetative cells but much less in heterocysts, implying compartmentalization of the arginine decarboxylation pathway in the diazotrophic filaments of this heterocyst-forming cyanobacterium. PMID:25209059

  6. Optical characterization of the oceanic unicellular cyanobacterium Synechococcus grown under a day-night cycle in natural irradiance

    NASA Technical Reports Server (NTRS)

    Stramski, Dariusz; Shalapyonok, Alexi; Reynolds, Rick A.

    1995-01-01

    The optical properties of the ocenanic cyanobacterium Synechococcus (clone WH8103) were examined in a nutrient-replete laboratory culture grown under a day-night cycle in natural irradiance. Measurements of the spectral absorption and beam attenuation coefficients, the size distribution of cells in suspension, and microscopic analysis of samples were made at intervals of 2-4 hours for 2 days. These measurements were used to calculate the optical properties at the level of a single 'mean' cell representative of the acutal population, specifically, the optical cross sections for spectral absorption bar-(sigma(sub a)), scattering bar-sigma(sub b))(lambda), and attentuation bar-(sigma(sub c))(lambda). In addition, concurrent determinations of chlorophyll a and particulate organic carbon allowed calculation of the Chl a- and C-specific optical coefficients. The refractive index of cells was derived from the observed data using a theory of light absorption and scattering by homogeneous spheres. Low irradiance because of cloudy skies resulted in slow division rates of cells in the culture. The percentage of dividing cells was unusually high (greater than 30%) throughout the experiment. The optical cross sections varied greatly over a day-night cycle, with a minimum near dawn or midmorning and maximum near dusk. During daylight hours, bar-(sigma(sub b)) and bar-(sigma(sub c)) can increase more than twofold and bar-(sigma(sub a) by as much as 45%. The real part of the refractive index n increaed during the day; changes in n had equal or greater effect than the varying size distribution on changes in bar-(sigma(sub c)) and bar-(sigma(sub b)). The contribution of changes in n to the increase of bar-(sigma(sub c))(660) during daylight hours was 65.7% and 45.1% on day 1 and 2, respectively. During the dark period, when bar-(sigma(sub c))(660) decreased by a factor of 2.9, the effect of decreasing n was dominant (86.3%). With the exception of a few hours during the second light

  7. Sucrose Synthesis in the Nitrogen-Fixing Cyanobacterium Anabaena sp. Strain PCC 7120 Is Controlled by the Two-Component Response Regulator OrrA

    PubMed Central

    Kimura, Satoshi; Miyazaki, Shogo; Ohmori, Masayuki

    2014-01-01

    The filamentous, nitrogen-fixing cyanobacterium Anabaena sp. strain PCC 7120 accumulates sucrose as a compatible solute against salt stress. Sucrose-phosphate synthase activity, which is responsible for the sucrose synthesis, is increased by salt stress, but the mechanism underlying the regulation of sucrose synthesis remains unknown. In the present study, a response regulator, OrrA, was shown to control sucrose synthesis. Expression of spsA, which encodes a sucrose-phosphate synthase, and susA and susB, which encode sucrose synthases, was induced by salt stress. In the orrA disruptant, salt induction of these genes was completely abolished. The cellular sucrose level of the orrA disruptant was reduced to 40% of that in the wild type under salt stress conditions. Moreover, overexpression of orrA resulted in enhanced expression of spsA, susA, and susB, followed by accumulation of sucrose, without the addition of NaCl. We also found that SigB2, a group 2 sigma factor of RNA polymerase, regulated the early response to salt stress under the control of OrrA. It is concluded that OrrA controls sucrose synthesis in collaboration with SigB2. PMID:25002430

  8. The AplI restriction-modification system in an edible cyanobacterium, Arthrospira (Spirulina) platensis NIES-39, recognizes the nucleotide sequence 5'-CTGCAG-3'.

    PubMed

    Shiraishi, Hideaki; Tabuse, Yosuke

    2013-01-01

    The degradation of foreign DNAs by restriction enzymes in an edible cyanobacterium, Arthrospira platensis, is a potential barrier for gene-transfer experiments in this economically valuable organism. We overproduced in Escherichia coli the proteins involved in a putative restriction-modification system of A. platensis NIES-39. The protein produced from the putative type II restriction enzyme gene NIES39_K04640 exhibited an endonuclease activity that cleaved DNA within the sequence 5'-CTGCAG-3' between the A at the fifth position and the G at the sixth position. We designated this enzyme AplI. The protein from the adjacent gene NIES39_K04650, which encodes a putative DNA (cytosine-5-)-methyltransferase, rendered DNA molecules resistant to AplI by modifying the C at the fourth position (but not the C at the first position) in the recognition sequence. This modification enzyme, M.AplI, should be useful for converting DNA molecules into AplI-resistant forms for use in gene-transfer experiments. A summary of restriction enzymes in various Arthrospira strains is also presented in this paper.

  9. Genome-scale modeling of light-driven reductant partitioning and carbon fluxes in diazotrophic unicellular cyanobacterium Cyanothece sp. ATCC 51142

    SciTech Connect

    Vu, Trang; Stolyar, Sergey; Pinchuk, Grigoriy E.; Hill, Eric A.; Kucek, Leo A.; Brown, Roslyn N.; Lipton, Mary S.; Osterman, Andrei L.; Fredrickson, Jim K.; Konopka, Allan; Beliaev, Alex S.; Reed, Jennifer L.

    2012-04-05

    Genome-scale metabolic models have proven useful for answering fundamental questions about metabolic capabilities of a variety of microorganisms, as well as informing their metabolic engineering. However, only a few models are available for oxygenic photosynthetic microorganisms, particularly in cyanobacteria in which photosynthetic and respiratory electron transport chains (ETC) share components. We addressed the complexity of cyanobacterial ETC by developing a genome-scale model for the diazotrophic cyanobacterium, Cyanothece sp. ATCC 51142. The resulting metabolic reconstruction, iCce806, consists of 806 genes associated with 667 metabolic reactions and includes a detailed representation of the ETC and a biomass equation based on experimental measurements. Both computational and experimental approaches were used to investigate light-driven metabolism in Cyanothece sp. ATCC 51142, with a particular focus on reductant production and partitioning within the ETC. The simulation results suggest that growth and metabolic flux distributions are substantially impacted by the relative amounts of light going into the individual photosystems. When photosystem II flux is high, terminal oxidases of respiratory electron transport are predicted to be an important mechanism for removing excess electrons. When photosystem I flux is high cyclic electron transport becomes important. Model predictions of growth rates were in good quantitative agreement with measured growth rates, and predictions of reaction usage were qualitatively consistent with protein and mRNA expression data, when these latter datasets were used to constrain the model.

  10. The outer membrane of a heterocyst-forming cyanobacterium is a permeability barrier for uptake of metabolites that are exchanged between cells.

    PubMed

    Nicolaisen, Kerstin; Mariscal, Vicente; Bredemeier, Rolf; Pernil, Rafael; Moslavac, Suncana; López-Igual, Rocío; Maldener, Iris; Herrero, Antonia; Schleiff, Enrico; Flores, Enrique

    2009-10-01

    The multicellular Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium that can fix N(2) in differentiated cells called heterocysts, which exchange nutritional and regulatory compounds with the neighbour photosynthetic vegetative cells. The outer membrane of this bacterium is continuous along the filament defining a continuous periplasmic space. The Anabaena alr0075, alr2269 and alr4893 gene products were characterized as Omp85-like proteins, which are generally involved in outer membrane protein biogenesis. Open reading frame alr2269 is the first gene of an operon that also carries genes for lipopolysaccharide lipid A biosynthesis including alr2270 (an lpxC homologue). Strains carrying inactivating alr2269 or alr2270 constructs showed enhanced sensitivity to erythromycin, SDS, lysozyme and proteinase K suggesting that they produce an outer membrane with increased permeability. These strains further exhibited increased uptake of sucrose, glutamate and, to a lesser extent, a few other amino acids. Increased uptake of the same metabolites was obtained by mechanical fragmentation of wild-type Anabaena filaments. These results document that the outer membrane is a permeability barrier for metabolites such as sucrose and glutamate, which are subjected to intercellular exchange in the diazotrophic filament of heterocyst-forming cyanobacteria.

  11. The Biosynthetic Pathway for Synechoxanthin, an Aromatic Carotenoid Synthesized by the Euryhaline, Unicellular Cyanobacterium Synechococcus sp. Strain PCC 7002▿ †

    PubMed Central

    Graham, Joel E.; Bryant, Donald A.

    2008-01-01

    The euryhaline, unicellular cyanobacterium Synechococcus sp. strain PCC 7002 produces the dicyclic aromatic carotenoid synechoxanthin (χ,χ-caroten-18,18′-dioic acid) as a major pigment (>15% of total carotenoid) and when grown to stationary phase also accumulates small amounts of renierapurpurin (χ,χ-carotene) (J. E. Graham, J. T. J. Lecomte, and D. A. Bryant, J. Nat. Prod. 71:1647-1650, 2008). Two genes that were predicted to encode enzymes involved in the biosynthesis of synechoxanthin were identified by comparative genomics, and these genes were insertionally inactivated in Synechococcus sp. strain PCC 7002 to verify their function. The cruE gene (SYNPCC7002_A1248) encodes β-carotene desaturase/methyltransferase, which converts β-carotene to renierapurpurin. The cruH gene (SYNPCC7002_A2246) encodes an enzyme that is minimally responsible for the hydroxylation/oxidation of the C-18 and C-18′ methyl groups of renierapurpurin. Based on observed and biochemically characterized intermediates, a complete pathway for synechoxanthin biosynthesis is proposed. PMID:18849428

  12. Sub‐cellular location of FtsH proteases in the cyanobacterium S ynechocystis sp. PCC 6803 suggests localised PSII repair zones in the thylakoid membranes

    PubMed Central

    Sacharz, Joanna; Bryan, Samantha J.; Yu, Jianfeng; Burroughs, Nigel J.; Spence, Edward M.; Nixon, Peter J.

    2015-01-01

    Summary In cyanobacteria and chloroplasts, exposure to HL damages the photosynthetic apparatus, especially the D1 subunit of Photosystem II. To avoid chronic photoinhibition, a PSII repair cycle operates to replace damaged PSII subunits with newly synthesised versions. To determine the sub‐cellular location of this process, we examined the localisation of FtsH metalloproteases, some of which are directly involved in degrading damaged D1. We generated transformants of the cyanobacterium S ynechocystis sp. PCC6803 expressing GFP‐tagged versions of its four FtsH proteases. The ftsH2–gfp strain was functional for PSII repair under our conditions. Confocal microscopy shows that FtsH1 is mainly in the cytoplasmic membrane, while the remaining FtsH proteins are in patches either in the thylakoid or at the interface between the thylakoid and cytoplasmic membranes. HL exposure which increases the activity of the Photosystem II repair cycle led to no detectable changes in FtsH distribution, with the FtsH2 protease involved in D1 degradation retaining its patchy distribution in the thylakoid membrane. We discuss the possibility that the FtsH2–GFP patches represent Photosystem II ‘repair zones’ within the thylakoid membranes, and the possible advantages of such functionally specialised membrane zones. Anti‐GFP affinity pull‐downs provide the first indication of the composition of the putative repair zones. PMID:25601560

  13. NdhV subunit regulates the activity of type-1 NAD(P)H dehydrogenase under high light conditions in cyanobacterium Synechocystis sp. PCC 6803

    PubMed Central

    Chen, Xin; He, Zhihui; Xu, Min; Peng, Lianwei; Mi, Hualing

    2016-01-01

    The cyanobacterial NAD(P)H dehydrogenase (NDH-1) complexes play crucial roles in variety of bioenergetic reactions. However, the regulative mechanism of NDH-1 under stressed conditions is still unclear. In this study, we detected that the NDH-1 activity is partially impaired, but the accumulation of NDH-1 complexes was little affected in the NdhV deleted mutant (ΔndhV) at low light in cyanobacterium Synechocystis sp. PCC 6803. ΔndhV grew normally at low light but slowly at high light under inorganic carbon limitation conditions (low pH or low CO2), meanwhile the activity of CO2 uptake was evidently lowered than wild type even at pH 8.0. The accumulation of NdhV in thylakoids strictly relies on the presence of the hydrophilic subcomplex of NDH-1. Furthermore, NdhV was co-located with hydrophilic subunits of NDH-1 loosely associated with the NDH-1L, NDH-1MS′ and NDH-1M complexes. The level of the NdhV was significantly increased at high light and deletion of NdhV suppressed the up-regulation of NDH-1 activity, causing the lowered the photosynthetic oxygen evolution at pH 6.5 and high light. These data indicate that NdhV is an intrinsic subunit of hydrophilic subcomplex of NDH-1, required for efficient operation of cyclic electron transport around photosystem I and CO2 uptake at high lights. PMID:27329499

  14. Novel photosensory two-component system (PixA-NixB-NixC) involved in the regulation of positive and negative phototaxis of cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Narikawa, Rei; Suzuki, Fumiko; Yoshihara, Shizue; Higashi, Sho-ichi; Watanabe, Masakatsu; Ikeuchi, Masahiko

    2011-12-01

    Two wild-type substrains of a motile cyanobacterium Synechocystis sp. PCC 6803 show positive phototaxis toward a light source (PCC-P) and negative phototaxis away from light (PCC-N). In this study, we found that a novel two-component system of photoresponse is involved in the phototactic regulation. Inactivation of slr1212 (pixA), which encodes a photoreceptor histidine kinase, reverted the positive phototaxis of PCC-P to negative phototaxis, and inactivation of the downstream slr1213 (nixB) and slr1214 (nixC), which encode AraC-like transcription factor-type and PatA-type response regulators, respectively, reverted the negative phototaxis of PCC-N to positive phototaxis. Opposite effects of pixA and nixBC disruption implies an unexpected signal transduction pathway in the switching of positive and negative phototaxis. The blue/green-