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Sample records for cyanobacterium synechococcus sp

  1. Complete Genome Sequence of a Coastal Cyanobacterium, Synechococcus sp. Strain NIES-970

    PubMed Central

    Hirose, Yuu; Misawa, Naomi; Wakazuki, Sachiko; Fujisawa, Takatomo; Nakamura, Yasukazu; Kanesaki, Yu; Yamaguchi, Haruyo; Kawachi, Masanobu

    2017-01-01

    ABSTRACT Members of the cyanobacterial genus Synechococcus are abundant in marine environments. To better understand the genomic diversity of marine Synechococcus spp., we determined the complete genome sequence of a coastal cyanobacterium, Synechococcus sp. NIES-970. The genome had a size of 3.1 Mb, consisting of one chromosome and four plasmids. PMID:28385852

  2. 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.

  3. Identification and Regulation of Genes for Cobalamin Transport in the Cyanobacterium Synechococcus sp. Strain PCC 7002

    PubMed Central

    Pérez, Adam A.; Rodionov, Dmitry A.

    2016-01-01

    ABSTRACT The cyanobacterium Synechococcus sp. strain PCC 7002 is a cobalamin auxotroph and utilizes this coenzyme solely for the synthesis of l-methionine by methionine synthase (MetH). Synechococcus sp. strain PCC 7002 is unable to synthesize cobalamin de novo, and because of the large size of this tetrapyrrole, an active-transport system must exist for cobalamin uptake. Surprisingly, no cobalamin transport system was identified in the initial annotation of the genome of this organism. With more sophisticated in silico prediction tools, a btuB-cpdA-btuC-btuF operon encoding components putatively required for a B12 uptake (btu) system was identified. The expression of these genes was predicted to be controlled by a cobalamin riboswitch. Global transcriptional profiling by high-throughput RNA sequencing of a cobalamin-independent form of Synechococcus sp. strain PCC 7002 grown in the absence or presence of cobalamin confirmed regulation of the btu operon by cobalamin. Pérez et al. (A. A. Pérez, Z. Liu, D. A. Rodionov, Z. Li, and D. A. Bryant, J Bacteriol 198:2743–2752, 2016, http://dx.doi.org/10.1128/JB.00475-16) developed a cobalamin-dependent yellow fluorescent protein reporter system in a Synechococcus sp. strain PCC 7002 variant that had been genetically modified to allow cobalamin-independent growth. This reporter system was exploited to validate components of the btu uptake system by assessing the ability of targeted mutants to transport cobalamin. The btuB promoter and a variant counterpart mutated in an essential element of the predicted cobalamin riboswitch were fused to a yfp reporter. The combined data indicate that the btuB-cpdA-btuF-btuC operon in this cyanobacterium is transcriptionally regulated by a cobalamin riboswitch. IMPORTANCE With a cobalamin-regulated reporter system for expression of yellow fluorescent protein, genes previously misidentified as encoding subunits of a siderophore transporter were shown to encode components of cobalamin

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

    PubMed Central

    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 PMID:25632108

  5. Physiological conditions for nitrogen fixation in a unicellular marine cyanobacterium, Synechococcus sp. strain SF1.

    PubMed Central

    Spiller, H; Shanmugam, K T

    1987-01-01

    A marine, unicellular, nitrogen-fixing cyanobacterium was isolated from the blades of a brown alga, Sargassum fluitans. This unicellular cyanobacterium, identified as Synechococcus sp. strain SF1, is capable of photoautotrophic growth with bicarbonate as the sole carbon source and dinitrogen as the sole nitrogen source. Among the organic carbon compounds tested, glucose and sucrose supported growth. Of the nitrogen compounds tested, with bicarbonate serving as the carbon source, both ammonia and nitrate produced the highest growth rates. Most amino acids failed to support growth when present as sole sources of nitrogen. Nitrogenase activity in Synechococcus sp. strain SF1 was induced after depletion of ammonia from the medium. This activity required the photosynthetic utilization of bicarbonate, but pyruvate and hydrogen gas were also effective sources of reductant for nitrogenase activity. Glucose, fructose, and sucrose also supported nitrogenase activity but to a lesser extent. Optimum light intensity for nitrogenase activity was found to be 70 microE/m2 per s, while the optimum oxygen concentration in the gas phase for nitrogenase activity was about 1%. A hydrogenase activity was coinduced with nitrogenase activity. It is proposed that this light- and oxygen-insensitive hydrogenase functions in recycling the hydrogen produced by nitrogenase under microaerobic conditions. PMID:3119563

  6. Synthetic Biology Toolbox for Controlling Gene Expression in the Cyanobacterium Synechococcus sp. strain PCC 7002

    PubMed Central

    2015-01-01

    The application of synthetic biology requires characterized tools to precisely control gene expression. This toolbox of genetic parts previously did not exist for the industrially promising cyanobacterium, Synechococcus sp. strain PCC 7002. To address this gap, two orthogonal constitutive promoter libraries, one based on a cyanobacterial promoter and the other ported from Escherichia coli, were built and tested in PCC 7002. The libraries demonstrated 3 and 2.5 log dynamic ranges, respectively, but correlated poorly with E. coli expression levels. These promoter libraries were then combined to create and optimize a series of IPTG inducible cassettes. The resultant induction system had a 48-fold dynamic range and was shown to out-perform Ptrc constructs. Finally, a RBS library was designed and tested in PCC 7002. The presented synthetic biology toolbox will enable accelerated engineering of PCC 7002. PMID:25216157

  7. 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.

  8. 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

  9. 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.

  10. [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.

  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. Localization of Membrane Proteins in the Cyanobacterium Synechococcus sp. PCC7942 (Radial Asymmetry in the Photosynthetic Complexes).

    PubMed

    Sherman, D. M.; Troyan, T. A.; Sherman, L. A.

    1994-09-01

    Localization of membrane proteins in the cyanobacterium Synechococcus sp. PCC7942 was determined by transmission electron microscopy utilizing immunocytochemistry with cells prepared by freeze-substitution. This preparation procedure maintained cellular morphology and permitted detection of cellular antigens with high sensitivity and low background. Synechococcus sp. PCC7942 is a unicellular cyanobacterium with thylakoids organized in concentric layers toward the periphery of the cell. Cytochrome oxidase was localized almost entirely in the cytoplasmic membrane, whereas a carotenoprotein (P35) was shown to be a cell wall component. The major photosystem II (PSII) proteins (D1, D2 CP43, and CP47) were localized throughout the thylakoids. Proteins of the Cyt b6/f complex were found to have a similar distribution. Thylakoid luminal proteins, such as the Mn-stabilizing protein, were located primarily in the thylakoid, but a small, reproducible fraction was found in the outer compartment. The photosystem I (PSI) reaction center proteins and the ATP synthase proteins were found associated mostly with the outermost thylakoid and with the cytoplasmic membrane. These results indicated that the photosynthetic apparatus is not evenly distributed throughout the thylakoids. Rather, there is a radial asymmetry such that much of the PSI and the ATPase synthase is located in the outermost thylakoid. The relationship of this structure to the photosynthetic mechanism is discussed. It is suggested that the photosystems are separated because of kinetic differences between PSII and PSI, as hypothesized by H.-W. Trissl and C. Wilhelm (Trends Biochem Sci [1993] 18:415-419).

  13. Expression of glnA in the cyanobacterium Synechococcus sp. strain PCC 7942 is initiated from a single nif-like promoter under various nitrogen conditions.

    PubMed Central

    Cohen-Kupiec, R; Gurevitz, M; Zilberstein, A

    1993-01-01

    The glnA mRNA, encoding glutamine synthetase, is differentially accumulated in the cyanobacterium Synechococcus sp. strain PCC 7942 in media containing different nitrogen sources. With the different nitrogen compounds, transcription of glnA initiated at a single site located -146 nucleotides upstream of the translation start site of the gene. A similarity of the nif-like promoter of the glnA gene of Anabaena sp. strain PCC 7120 and a binding-site sequence for the Synechococcus sp. strain PCC 7942 transcription regulator, NtcA, were found upstream of the transcription initiation site. Images PMID:7902350

  14. Localization of Membrane Proteins in the Cyanobacterium Synechococcus sp. PCC7942 (Radial Asymmetry in the Photosynthetic Complexes).

    PubMed Central

    Sherman, D. M.; Troyan, T. A.; Sherman, L. A.

    1994-01-01

    Localization of membrane proteins in the cyanobacterium Synechococcus sp. PCC7942 was determined by transmission electron microscopy utilizing immunocytochemistry with cells prepared by freeze-substitution. This preparation procedure maintained cellular morphology and permitted detection of cellular antigens with high sensitivity and low background. Synechococcus sp. PCC7942 is a unicellular cyanobacterium with thylakoids organized in concentric layers toward the periphery of the cell. Cytochrome oxidase was localized almost entirely in the cytoplasmic membrane, whereas a carotenoprotein (P35) was shown to be a cell wall component. The major photosystem II (PSII) proteins (D1, D2 CP43, and CP47) were localized throughout the thylakoids. Proteins of the Cyt b6/f complex were found to have a similar distribution. Thylakoid luminal proteins, such as the Mn-stabilizing protein, were located primarily in the thylakoid, but a small, reproducible fraction was found in the outer compartment. The photosystem I (PSI) reaction center proteins and the ATP synthase proteins were found associated mostly with the outermost thylakoid and with the cytoplasmic membrane. These results indicated that the photosynthetic apparatus is not evenly distributed throughout the thylakoids. Rather, there is a radial asymmetry such that much of the PSI and the ATPase synthase is located in the outermost thylakoid. The relationship of this structure to the photosynthetic mechanism is discussed. It is suggested that the photosystems are separated because of kinetic differences between PSII and PSI, as hypothesized by H.-W. Trissl and C. Wilhelm (Trends Biochem Sci [1993] 18:415-419). PMID:12232325

  15. Two novel phycoerythrin-associated linker proteins in the marine cyanobacterium Synechococcus sp. strain WH8102.

    PubMed

    Six, Christophe; Thomas, Jean-Claude; Thion, Laurent; Lemoine, Yves; Zal, Frank; Partensky, Frédéric

    2005-03-01

    The recent availability of the whole genome of Synechococcus sp. strain WH8102 allows us to have a global view of the complex structure of the phycobilisomes of this marine picocyanobacterium. Genomic analyses revealed several new characteristics of these phycobilisomes, consisting of an allophycocyanin core and rods made of one type of phycocyanin and two types of phycoerythrins (I and II). Although the allophycocyanin appears to be similar to that found commonly in freshwater cyanobacteria, the phycocyanin is simpler since it possesses only one complete set of alpha and beta subunits and two rod-core linkers (CpcG1 and CpcG2). It is therefore probably made of a single hexameric disk per rod. In contrast, we have found two novel putative phycoerythrin-associated linker polypeptides that appear to be specific for marine Synechococcus spp. The first one (SYNW2000) is unusually long (548 residues) and apparently results from the fusion of a paralog of MpeC, a phycoerythrin II linker, and of CpeD, a phycoerythrin-I linker. The second one (SYNW1989) has a more classical size (300 residues) and is also an MpeC paralog. A biochemical analysis revealed that, like MpeC, these two novel linkers were both chromophorylated with phycourobilin. Our data suggest that they are both associated (partly or totally) with phycoerythrin II, and we propose to name SYNW2000 and SYNW1989 MpeD and MpeE, respectively. We further show that acclimation of phycobilisomes to high light leads to a dramatic reduction of MpeC, whereas the two novel linkers are not significantly affected. Models for the organization of the rods are proposed.

  16. Two Novel Phycoerythrin-Associated Linker Proteins in the Marine Cyanobacterium Synechococcus sp. Strain WH8102

    PubMed Central

    Six, Christophe; Thomas, Jean-Claude; Thion, Laurent; Lemoine, Yves; Zal, Frank; Partensky, Frédéric

    2005-01-01

    The recent availability of the whole genome of Synechococcus sp. strain WH8102 allows us to have a global view of the complex structure of the phycobilisomes of this marine picocyanobacterium. Genomic analyses revealed several new characteristics of these phycobilisomes, consisting of an allophycocyanin core and rods made of one type of phycocyanin and two types of phycoerythrins (I and II). Although the allophycocyanin appears to be similar to that found commonly in freshwater cyanobacteria, the phycocyanin is simpler since it possesses only one complete set of α and β subunits and two rod-core linkers (CpcG1 and CpcG2). It is therefore probably made of a single hexameric disk per rod. In contrast, we have found two novel putative phycoerythrin-associated linker polypeptides that appear to be specific for marine Synechococcus spp. The first one (SYNW2000) is unusually long (548 residues) and apparently results from the fusion of a paralog of MpeC, a phycoerythrin II linker, and of CpeD, a phycoerythrin-I linker. The second one (SYNW1989) has a more classical size (300 residues) and is also an MpeC paralog. A biochemical analysis revealed that, like MpeC, these two novel linkers were both chromophorylated with phycourobilin. Our data suggest that they are both associated (partly or totally) with phycoerythrin II, and we propose to name SYNW2000 and SYNW1989 MpeD and MpeE, respectively. We further show that acclimation of phycobilisomes to high light leads to a dramatic reduction of MpeC, whereas the two novel linkers are not significantly affected. Models for the organization of the rods are proposed. PMID:15716439

  17. Regulation by cyanate of the genes involved in carbon and nitrogen assimilation in the cyanobacterium Synechococcus sp. strain PCC 7942.

    PubMed

    Suzuki, I; Sugiyami, T; Omata, T

    1996-05-01

    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.

  18. 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.

  19. 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.

  20. Characterization of zinc stress response in Cyanobacterium Synechococcus sp. IU 625.

    PubMed

    Newby, Robert; Lee, Lee H; Perez, Jose L; Tao, Xin; Chu, Tinchun

    2017-05-01

    The ability of cyanobacteria to survive many environmental stress factors is a testament to their resilience in nature. Of these environmental stress factors, overexposure to zinc is important to study since excessive zinc intake can be a severe hazard. Zinc toxicity in freshwater has been demonstrated to affects organisms such as invertebrates, algae and cyanobacteria. Cyanobacteria which possess increased resistance to zinc have been isolated. It is therefore important to elucidate the mechanism of survival and response to determine what factors allow their survival; as well as any remediation implications they may have. To characterize the effects of zinc in freshwater cyanobacteria, we investigated the response of Synechococcus sp. IU 625 (S. IU 625) over 29days to various concentrations (10, 25, and 50mg/L) of ZnCl2. S. IU 625 was shown to be tolerant up to 25mg/L ZnCl2 exposure, with 10mg/L ZnCl2 having no outward physiological change and 50mg/L ZnCl2 proving lethal to the cells. To determine a potential mechanism Inductive Coupled Plasma-Mass Spectrometry (ICP-MS) and RNA-seq analysis were performed on zinc exposed cells. Analysis performed on days 4 and 7 indicated that response is dose-dependent, with 10mg/L ZnCl2 exhibiting nearly all zinc extracellular, corresponding with upregulation of cation transport response. Whereas the 25mg/L ZnCl2 exhibited half of total zinc sequestered by the cells, which corresponds with the upregulation of sequestering proteins such as metallothionein and the downregulation of genes involved with ATP synthesis and phycobilisome assembly. These analyses were combined with growth monitoring, microscopy, quantitative polymerase chain reaction (qPCR) and flow cytometry to present a full spectrum of mechanisms behind zinc response in S. IU 625. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. 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.

  2. Identification and cloning of a regulatory gene for nitrogen assimilation in the cyanobacterium Synechococcus sp. strain PCC 7942.

    PubMed Central

    Vega-Palas, M A; Madueño, F; Herrero, A; Flores, E

    1990-01-01

    Twenty-seven mutants that were unable to assimilate nitrate were isolated from Synechococcus sp. strain PCC 7942. In addition to mutants that lacked nitrate reductase or nitrite reductase, seven pleiotropic mutants impaired in both reductases, glutamine synthetase, and methylammonium transport were also isolated. One of the pleiotropic mutants was complemented by transformation with a cosmid gene bank from wild-type strain PCC 7942. Three complementing cosmids were isolated, and a 3.1-kilobase-pair DNA fragment that was still able to complement the mutant was identified. The regulatory gene that was cloned (ntcA) appeared to be required for full expression of proteins subject to ammonium repression in Synechococcus sp. PMID:1967601

  3. MapA, an iron-regulated, cytoplasmic membrane protein in the cyanobacterium Synechococcus sp. strain PCC7942.

    PubMed Central

    Webb, R; Troyan, T; Sherman, D; Sherman, L A

    1994-01-01

    Growth of Synechococcus sp. strain PCC 7942 in iron-deficient media leads to the accumulation of an approximately 34-kDa protein. The gene encoding this protein, mapA (membrane-associated protein A), has been cloned and sequenced (GenBank accession number, L01621). The mapA transcript is not detectable in normally grown cultures but is stably accumulated by cells grown in iron-deficient media. However, the promoter sequence for this gene does not resemble other bacterial iron-regulated promoters described to date. The carboxyl-terminal region of the derived amino acid sequence of MapA resembles bacterial proteins involved in iron acquisition, whereas the amino-terminal end of MapA has a high degree of amino acid identity with the abundant, chloroplast envelope protein E37. An approach employing improved cellular fractionation techniques as well as electron microscopy and immunocytochemistry was essential in localizing MapA protein to the cytoplasmic membrane of Synechococcus sp. strain PCC 7942. When these cells were grown under iron-deficient conditions, a significant fraction of MapA could also be localized to the thylakoid membranes. Images PMID:8051004

  4. MapA, an iron-regulated, cytoplasmic membrane protein in the cyanobacterium Synechococcus sp. strain PCC7942.

    PubMed

    Webb, R; Troyan, T; Sherman, D; Sherman, L A

    1994-08-01

    Growth of Synechococcus sp. strain PCC 7942 in iron-deficient media leads to the accumulation of an approximately 34-kDa protein. The gene encoding this protein, mapA (membrane-associated protein A), has been cloned and sequenced (GenBank accession number, L01621). The mapA transcript is not detectable in normally grown cultures but is stably accumulated by cells grown in iron-deficient media. However, the promoter sequence for this gene does not resemble other bacterial iron-regulated promoters described to date. The carboxyl-terminal region of the derived amino acid sequence of MapA resembles bacterial proteins involved in iron acquisition, whereas the amino-terminal end of MapA has a high degree of amino acid identity with the abundant, chloroplast envelope protein E37. An approach employing improved cellular fractionation techniques as well as electron microscopy and immunocytochemistry was essential in localizing MapA protein to the cytoplasmic membrane of Synechococcus sp. strain PCC 7942. When these cells were grown under iron-deficient conditions, a significant fraction of MapA could also be localized to the thylakoid membranes.

  5. A period-extender gene, pex, that extends the period of the circadian clock in the cyanobacterium Synechococcus sp. strain PCC 7942.

    PubMed

    Kutsuna, S; Kondo, T; Aoki, S; Ishiura, M

    1998-04-01

    We cloned the pS1K1 plasmid in the process of apparently "complementing" a circadian clock mutant of cyanobacterium Synechococcus sp. strain PCC 7942, SP22, which has a 22-h period (T. Kondo, N. F. Tsinoremas, S. S. Golden, C. H. Johnson, S. Kutsuna, and M. Ishiura, Science 266:1233-1236, 1994). Sequence analysis revealed that SP22 did not have a mutation in the genomic DNA segment carried on pS1K1, and the sp22 mutation was later found in a recently cloned new clock gene, kaiC. Therefore, the period-extender gene pex that was carried on pS1K1 was a suppressor gene for the sp22 mutation. The pex gene encoded a protein of 148 amino acid residues. No meaningful homologs were found in DNA or protein databases including the Synechocystis genome database. The pex gene was transcribed from 129 and 164 bp upstream of the translation initiation codon as 0.6-kb transcripts. The Pex protein was detected as a fusion protein with a molecular mass of 15 kDa by the epitope tag fusion method using a c-Myc epitope tag. Disruption of the pex gene in wild-type cells shortened the period of the rhythms by 1 h, although it did not affect other properties of the rhythms, whereas its overexpression extended the period by 3 h with a concomitant reduction in the amplitude of the rhythms. In various clock mutants examined, overexpression caused arrhythmicity. Thus, Pex is likely to function as a modifier of the circadian clock in Synechococcus.

  6. Nitrate/Nitrite Assimilation System of the Marine Picoplanktonic Cyanobacterium Synechococcus sp. Strain WH 8103: Effect of Nitrogen Source and Availability on Gene Expression

    PubMed Central

    Bird, Clare; Wyman, Michael

    2003-01-01

    The genes encoding the structural components of the nitrate/nitrite assimilation system of the oceanic cyanobacterium Synechococcus sp. strain WH 8103 were cloned and characterized. The genes encoding nitrate reductase (narB) and nitrite reductase (nirA) are clustered on the chromosome but are organized in separate transcriptional units. Upstream of narB is a homologue of nrtP that encodes a nitrate/nitrite-bispecific permease rather than the components of an ABC-type nitrate transporter found in freshwater cyanobacteria. Unusually, neither nirA nor ntcA (encoding a positive transcription factor of genes subject to nitrogen control) were found to be tightly regulated by ammonium. Furthermore, transcription of glnA (encoding glutamine synthetase) is up-regulated in ammonium-grown cells, highlighting significant differences in nitrogen control in this cyanobacterium. Nitrogen depletion led to the transient up-regulation of ntcA, nirA, nrtP, narB, and glnA in what appears to be an NtcA-dependent manner. The NtcA-like promoters found upstream of nirA, nrtP, and narB all differ in sequence from the canonical NtcA promoter established for other cyanobacteria, and in the case of nirA, the NtcA-like promoter was functional only in cells deprived of combined nitrogen. The ecological implications of these findings are discussed in the context of the oligotrophic nature of oceanic surface waters in which Synechococcus spp. thrive. PMID:14660343

  7. Light History Influences the Response of the Marine Cyanobacterium Synechococcus sp. WH7803 to Oxidative Stress1[W][OA

    PubMed Central

    Blot, Nicolas; Mella-Flores, Daniella; Six, Christophe; Le Corguillé, Gildas; Boutte, Christophe; Peyrat, Anne; Monnier, Annabelle; Ratin, Morgane; Gourvil, Priscillia; Campbell, Douglas A.; Garczarek, Laurence

    2011-01-01

    Marine Synechococcus undergo a wide range of environmental stressors, especially high and variable irradiance, which may induce oxidative stress through the generation of reactive oxygen species (ROS). While light and ROS could act synergistically on the impairment of photosynthesis, inducing photodamage and inhibiting photosystem II repair, acclimation to high irradiance is also thought to confer resistance to other stressors. To identify the respective roles of light and ROS in the photoinhibition process and detect a possible light-driven tolerance to oxidative stress, we compared the photophysiological and transcriptomic responses of Synechococcus sp. WH7803 acclimated to low light (LL) or high light (HL) to oxidative stress, induced by hydrogen peroxide (H2O2) or methylviologen. While photosynthetic activity was much more affected in HL than in LL cells, only HL cells were able to recover growth and photosynthesis after the addition of 25 μm H2O2. Depending upon light conditions and H2O2 concentration, the latter oxidizing agent induced photosystem II inactivation through both direct damage to the reaction centers and inhibition of its repair cycle. Although the global transcriptome response appeared similar in LL and HL cells, some processes were specifically induced in HL cells that seemingly helped them withstand oxidative stress, including enhancement of photoprotection and ROS detoxification, repair of ROS-driven damage, and regulation of redox state. Detection of putative LexA binding sites allowed the identification of the putative LexA regulon, which was down-regulated in HL compared with LL cells but up-regulated by oxidative stress under both growth irradiances. PMID:21670225

  8. Expression of the ggpS Gene, Involved in Osmolyte Synthesis in the Marine Cyanobacterium Synechococcus sp. Strain PCC 7002, Revealed Regulatory Differences between This Strain and the Freshwater Strain Synechocystis sp. Strain PCC 6803

    PubMed Central

    Engelbrecht, Friederike; Marin, Kay; Hagemann, Martin

    1999-01-01

    Synthesis of the osmolyte glucosylglycerol (GG) in the marine cyanobacterium Synechococcus sp. strain PCC 7002 was characterized. The ggpS gene, which encodes the key enzyme (GG-phosphate synthase [GgpS]) in GG biosynthesis, was cloned by using PCR. A 2,030-bp DNA sequence which contained one open reading frame (ORF) was obtained. The protein deduced from this ORF exhibited 85% similarity to the GgpS of the freshwater cyanobacterium Synechocystis sp. strain PCC 6803. The function of the protein was confirmed by generating a ggpS null mutant, which was not able to synthesize GG and thus exhibited a salt-sensitive phenotype. Expression of the ggpS gene was analyzed in salt-shocked cells by performing Northern blot and immunoblot experiments. While almost no expression was detected in cells grown in low-salt medium, immediately after a salt shock the amounts of ggpS mRNA and GgpS protein increased up to 100-fold. The finding that salt-induced expression occurred was confirmed by measuring enzyme activities, which were negligible in control cells but clearly higher in salt-treated Synechococcus sp. cells. The salt-induced increase in GgpS activity could be inhibited by adding chloramphenicol, while in protein extracts of the freshwater cyanobacterium Synechocystis sp. strain PCC 6803 a constitutive, high level of enzyme activity that was not affected by chloramphenicol was found. A comparison of GG accumulation in the two cyanobacteria revealed that in the marine strain osmolyte synthesis seemed to be regulated mainly by transcriptional control, whereas in the freshwater strain control seemed to be predominantly posttranslational. PMID:10543792

  9. Natural osmolytes are much less effective substrates than glycogen for catabolic energy production in the marine cyanobacterium Synechococcus sp. strain PCC 7002.

    PubMed

    Guerra, L Tiago; Xu, Yu; Bennette, Nicholas; McNeely, Kelsey; Bryant, Donald A; Dismukes, G Charles

    2013-07-10

    ADP-glucose pyrophosphorylase, encoded by glgC, catalyzes the first step of glycogen and glucosylglycer(ol/ate) biosynthesis. Here we report the construction of the first glgC null mutant of a marine cyanobacterium (Synechococcus sp. PCC 7002) and investigate its impact on dark anoxic metabolism (autofermentation). The glgC mutant had 98% lower ADP-glucose, synthesized no glycogen and produced appreciably more soluble sugars (mainly sucrose) than wild type (WT). Some glucosylglycerol was still observed, which suggests that the mutant has another, inefficient ADP-glucose synthesis pathway. In contrast, hypersaline conditions (1M NaCl) were lethal to the mutant strain, indicating that, unlike other strains, the elevated sucrose does not compensate for the reduced GG as osmolyte. In contrast to WT, nitrate limitation did not cause bleaching of N-containing pigments or carbohydrate accumulation in the glgC mutant, indicating impaired recycling of nitrogen stores. Despite the 2-fold increase in osmolytes, both the respiration and autofermentation rates of the glgC mutant were appreciably slower (2-4-fold) and correlated quantitatively with the lower fraction of insoluble carbohydrates relative to WT (85% vs. 12%). However, the remaining insoluble carbohydrates still accounted for a high fraction of the carbohydrate catabolized (38%), indicating that insoluble carbohydrates rather than osmolytes were the preferred substrate for autofermentation.

  10. Characterization of processes responsible for the distinct effect of herbicides DCMU and BNT on Photosystem II photoinactivation in cells of the cyanobacterium Synechococcus sp. PCC 7942.

    PubMed

    Komenda, J; Koblízek, M; Prásil, O

    2000-01-01

    Light-induced modification of Photosystem II (PS II) complex was characterized in the cyanobacterium Synechococcus sp. PCC 7942 treated with either DCMU (a phenylurea PS II inhibitor) or BNT (a phenolic PS II inhibitor). The irradiance response of photoinactivation of PS II oxygen evolution indicated a BNT-specific photoinhibition that saturated at relatively low intensity of light. This BNT-specific process was slowed down under anaerobiosis, was accompanied by the oxygen-dependent formation of a 39 kDa D1 protein adduct, and was not related to stable Q(A) reduction or the ADRY effect. In the BNT-treated cells, the light-induced, oxygen-independent initial drop of PS II electron flow was not affected by formate, an anion modifying properties of the PS II non-heme iron. For DCMU-treated cells, anaerobiosis did not significantly affect PS II photoinactivation, the D1 adduct was not observed and addition of formate induced similar initial decrease of PS II electron flow as in the BNT-treated cells. Our results indicate that reactive oxygen species (most likely singlet oxygen) and modification of the PS II acceptor side are responsible for the fast BNT-induced photoinactivation of PS II.

  11. Inactivation of nitrate reductase alters metabolic branching of carbohydrate fermentation in the cyanobacterium Synechococcus sp. strain PCC 7002.

    PubMed

    Qian, Xiao; Kumaraswamy, G Kenchappa; Zhang, Shuyi; Gates, Colin; Ananyev, Gennady M; Bryant, Donald A; Dismukes, G Charles

    2016-05-01

    To produce cellular energy, cyanobacteria reduce nitrate as the preferred pathway over proton reduction (H2 evolution) by catabolizing glycogen under dark anaerobic conditions. This competition lowers H2 production by consuming a large fraction of the reducing equivalents (NADPH and NADH). To eliminate this competition, we constructed a knockout mutant of nitrate reductase, encoded by narB, in Synechococcus sp. PCC 7002. As expected, ΔnarB was able to take up intracellular nitrate but was unable to reduce it to nitrite or ammonia, and was unable to grow photoautotrophically on nitrate. During photoautotrophic growth on urea, ΔnarB significantly redirects biomass accumulation into glycogen at the expense of protein accumulation. During subsequent dark fermentation, metabolite concentrations--both the adenylate cellular energy charge (∼ATP) and the redox poise (NAD(P)H/NAD(P))--were independent of nitrate availability in ΔnarB, in contrast to the wild type (WT) control. The ΔnarB strain diverted more reducing equivalents from glycogen catabolism into reduced products, mainly H2 and d-lactate, by 6-fold (2.8% yield) and 2-fold (82.3% yield), respectively, than WT. Continuous removal of H2 from the fermentation medium (milking) further boosted net H2 production by 7-fold in ΔnarB, at the expense of less excreted lactate, resulting in a 49-fold combined increase in the net H2 evolution rate during 2 days of fermentation compared to the WT. The absence of nitrate reductase eliminated the inductive effect of nitrate addition on rerouting carbohydrate catabolism from glycolysis to the oxidative pentose phosphate (OPP) pathway, indicating that intracellular redox poise and not nitrate itself acts as the control switch for carbon flux branching between pathways.

  12. Transcription Profiling of the Model Cyanobacterium Synechococcus sp. Strain PCC 7002 by Next-Gen (SOLiD™) Sequencing of cDNA

    PubMed Central

    Ludwig, Marcus; Bryant, Donald A.

    2011-01-01

    The genome of the unicellular, euryhaline cyanobacterium Synechococcus sp. PCC 7002 encodes about 3200 proteins. Transcripts were detected for nearly all annotated open reading frames by a global transcriptomic analysis by Next-Generation (SOLiD™) sequencing of cDNA. In the cDNA samples sequenced, ∼90% of the mapped sequences were derived from the 16S and 23S ribosomal RNAs and ∼10% of the sequences were derived from mRNAs. In cells grown photoautotrophically under standard conditions [38°C, 1% (v/v) CO2 in air, 250 μmol photons m−2 s−1], the highest transcript levels (up to 2% of the total mRNA for the most abundantly transcribed genes; e.g., cpcAB, psbA, psaA) were generally derived from genes encoding structural components of the photosynthetic apparatus. High-light exposure for 1 h caused changes in transcript levels for genes encoding proteins of the photosynthetic apparatus, Type-1 NADH dehydrogenase complex and ATP synthase, whereas dark incubation for 1 h resulted in a global decrease in transcript levels for photosynthesis-related genes and an increase in transcript levels for genes involved in carbohydrate degradation. Transcript levels for pyruvate kinase and the pyruvate dehydrogenase complex decreased sharply in cells incubated in the dark. Under dark anoxic (fermentative) conditions, transcript changes indicated a global decrease in transcripts for respiratory proteins and suggested that cells employ an alternative phosphoenolpyruvate degradation pathway via phosphoenolpyruvate synthase (ppsA) and the pyruvate:ferredoxin oxidoreductase (nifJ). Finally, the data suggested that an apparent operon involved in tetrapyrrole biosynthesis and fatty acid desaturation, acsF2–ho2–hemN2–desF, may be regulated by oxygen concentration. PMID:21779275

  13. CRISPR interference as a titratable, trans-acting regulatory tool for metabolic engineering in the cyanobacterium Synechococcus sp. strain PCC 7002.

    PubMed

    Gordon, Gina C; Korosh, Travis C; Cameron, Jeffrey C; Markley, Andrew L; Begemann, Matthew B; Pfleger, Brian F

    2016-11-01

    Trans-acting regulators provide novel opportunities to study essential genes and regulate metabolic pathways. We have adapted the clustered regularly interspersed palindromic repeats (CRISPR) system from Streptococcus pyogenes to repress genes in trans in the cyanobacterium Synechococcus sp. strain PCC 7002 (hereafter PCC 7002). With this approach, termed CRISPR interference (CRISPRi), transcription of a specific target sequence is repressed by a catalytically inactive Cas9 protein recruited to the target DNA by base-pair interactions with a single guide RNA that is complementary to the target sequence. We adapted this system for PCC 7002 and achieved conditional and titratable repression of a heterologous reporter gene, yellow fluorescent protein. Next, we demonstrated the utility of finely tuning native gene expression by downregulating the abundance of phycobillisomes. In addition, we created a conditional auxotroph by repressing synthesis of the carboxysome, an essential component of the carbon concentrating mechanism cyanobacteria use to fix atmospheric CO2. Lastly, we demonstrated a novel strategy for increasing central carbon flux by conditionally downregulating a key node in nitrogen assimilation. The resulting cells produced 2-fold more lactate than a baseline engineered cell line, representing the highest photosynthetically generated productivity to date. This work is the first example of titratable repression in cyanobacteria using CRISPRi, enabling dynamic regulation of essential processes and manipulation of flux through central carbon metabolism. This tool facilitates the study of essential genes of unknown function and enables groundbreaking metabolic engineering capability, by providing a straightforward approach to redirect metabolism and carbon flux in the production of high-value chemicals. Copyright © 2016 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  14. Effects of exogenous β-carotene, a chemical scavenger of singlet oxygen, on the millisecond rise of chlorophyll a fluorescence of cyanobacterium Synechococcus sp. PCC 7942.

    PubMed

    Stamatakis, Kostas; Papageorgiou, George C; Govindjee

    2016-12-01

    Singlet-excited oxygen ((1)O 2(*) ) has been recognized as the most destructive member of the reactive oxygen species (ROS) which are formed during oxygenic photosynthesis by plants, algae, and cyanobacteria. ROS and (1)O 2(*) are known to damage protein and phospholipid structures and to impair photosynthetic electron transport and de novo protein synthesis. Partial protection is afforded to photosynthetic organism by the β-carotene (β-Car) molecules which accompany chlorophyll (Chl) a in the pigment-protein complexes of Photosystem II (PS II). In this paper, we studied the effects of exogenously added β-Car on the initial kinetic rise of Chl a fluorescence (10-1000 μs, the OJ segment) from the unicellular cyanobacterium Synechococcus sp. PCC7942. We show that the added β-Car enhances Chl a fluorescence when it is excited at an intensity of 3000 μmol photons m(-2) s(-1) but not when excited at 1000 μmol photons m(-2) s(-1). Since β-Car is an efficient scavenger of (1)O 2(*) , as well as a quencher of (3)Chl a (*) (precursor of (1)O 2(*) ), both of which are more abundant at higher excitations, we assume that the higher Chl a fluorescence in its presence signifies a protective effect against photo-oxidative damages of Chl proteins. The protective effect of added β-Car is not observed in O2-depleted cell suspensions. Lastly, in contrast to β-Car, a water-insoluble molecule, a water-soluble scavenger of (1)O 2(*) , histidine, provides no protection to Chl proteins during the same time period (10-1000 μs).

  15. Genetic tools for advancement of Synechococcus sp. PCC 7002 as a cyanobacterial chassis

    DOE PAGES

    Ruffing, Anne M.; Jensen, Travis J.; Strickland, Lucas M.

    2016-11-10

    Successful implementation of modified cyanobacteria as hosts for industrial applications requires the development of a cyanobacterial chassis. The cyanobacterium Synechococcus sp. PCC 7002 embodies key attributes for an industrial host, including a fast growth rate and high salt, light, and temperature tolerances. Here, this study addresses key limitations in the advancement of Synechococcus sp. PCC 7002 as an industrial chassis.

  16. O2-dependent large electron flow functioned as an electron sink, replacing the steady-state electron flux in photosynthesis in the cyanobacterium Synechocystis sp. PCC 6803, but not in the cyanobacterium Synechococcus sp. PCC 7942.

    PubMed

    Hayashi, Ryosuke; Shimakawa, Ginga; Shaku, Keiichiro; Shimizu, Satoko; Akimoto, Seiji; Yamamoto, Hiroshi; Amako, Katsumi; Sugimoto, Toshio; Tamoi, Masahiro; Makino, Amane; Miyake, Chikahiro

    2014-01-01

    To determine whether alternative electron flow (AEF) can replace the photosynthetic electron flow in cyanobacteria, we used an open O2-electrode system to monitor O2-exchange over a long period. In air-grown Synechocystis sp. PCC 6803 (S. 6803(WT)), the quantum yield of PSII, Y(II), held even after photosynthesis was suppressed by CO2 shortage. The S. 6803 mutant, deficient in flavodiiron (FLV) proteins 1 and 3, showed the same phenotype as S. 6803(WT). In contrast, Y(II) decreased in Synechococcus sp. PCC 7942 (S. 7942). These results suggest that AEF functioned as the Y(II) in S. 6803 and replaced the photosynthetic electron flux. In contrast, the activity of AEF in S. 7942 was lower. The affinity of AEF for O2 in S. 6803 did not correspond to those of FLVs in bacteria or terminal oxidases in respiration. AEF might be driven by photorespiration.

  17. ΔpH-dependent non-photochemical quenching (qE) of excited chlorophylls in the photosystem II core complex of the freshwater cyanobacterium Synechococcus sp PCC 7942.

    PubMed

    Stamatakis, Kostas; Papageorgiou, George C

    2014-08-01

    Light-induced and lumen acidity-dependent quenching (qE) of excited chlorophylls (Chl) in vivo has been amply documented in plants and algae, but not in cyanobacteria, using primarily the saturation pulse method of quenching analysis which is applied to continuously illuminated samples. This method is unsuitable for cyanobacteria because the background illumination elicits in them a very large Chl a fluorescence signal, due to a state 2 to state 1 transition, which masks fluorescence changes due to other causes. We investigated the qE problem in the cyanobacterium Synechococcus sp. PCC 7942 using a kinetic method (Chl a fluorescence induction) with which qE can be examined before the onset of the state 2 to state 1 transition and the attendant rise of Chl a fluorescence. Our results confirm the existence of a qE mechanism that operates on excited Chls a in Photosystem II core complexes of cyanobacteria.

  18. Under light limiting growth, CpcB lyase null mutants of the Cyanobacterium Synechococcus sp. PCC 7002 are capable of producing pigmented beta phycocyanin but with altered chromophore function.

    PubMed

    Derks, Allen K; Vasiliev, Serguei; Bruce, Doug

    2008-11-11

    Phycobilisomes are the major light-harvesting complexes for cyanobacteria, and phycocyanin is the primary phycobiliprotein of the phycobilisome rod. Phycocyanobilin chromophores are covalently bonded to the phycocyanin beta subunit (CpcB) by specific lyases which have been recently identified in the cyanobacterium Synechococcus sp. PCC 7002. Surprisingly, we found that mutants missing the CpcB lyases were nevertheless capable of producing pigmented phycocyanin when grown under low-light conditions. Absorbance measurements at 10 K revealed the energy states of the beta phycocyanin chromophores to be slightly shifted, and 77 K steady state fluorescence emission spectroscopy showed that excitation energy transfer involving the targeted chromophores was disrupted. This evidence indicates that the position of the phycocyanobilin chromophore within the binding domain of the phycocyanin beta subunit had been modified. We hypothesize that alternate, less specific lyases are able to add chromophores, with varying effectiveness, to the beta binding sites.

  19. The use of NH4(+) rather than NO3(-) affects cell stoichiometry, C allocation, photosynthesis and growth in the cyanobacterium Synechococcus sp. UTEX LB 2380, only when energy is limiting.

    PubMed

    Ruan, Zuoxi; Giordano, Mario

    2017-02-01

    The assimilation of N-NO3(-) requires more energy than that of N-NH4(+) . This becomes relevant when energy is limiting and may impinge differently on cell energy budget depending on depth, time of the day and season. We hypothesize that N-limited and energy-limited cells of the oceanic cyanobacterium Synechococcus sp. differ in their response to the N source with respect to growth, elemental stoichiometry and carbon allocation. Under N limitation, cells retained almost absolute homeostasis of elemental and organic composition, and the use of NH4(+) did not stimulate growth. When energy was limiting, however, Synechococcus grew faster in NH4(+) than in NO3(-) and had higher C (20%), N (38%) and S (30%) cell quotas. Furthermore, more C was allocated to protein, whereas the carbohydrate and lipid pool size did not change appreciably. Energy limitation also led to a higher photosynthetic rate relative to N limitation. We interpret these results as an indication that, under energy limitation, the use of the least expensive N source allowed a spillover of the energy saved from N assimilation to the assimilation of other nutrients. The change in elemental stoichiometry influenced C allocation, inducing an increase in cell protein, which resulted in a stimulation of photosynthesis and growth.

  20. Genetic tools for advancement of Synechococcus sp. PCC 7002 as a cyanobacterial chassis

    SciTech Connect

    Ruffing, Anne M.; Jensen, Travis J.; Strickland, Lucas M.

    2016-11-10

    Successful implementation of modified cyanobacteria as hosts for industrial applications requires the development of a cyanobacterial chassis. The cyanobacterium Synechococcus sp. PCC 7002 embodies key attributes for an industrial host, including a fast growth rate and high salt, light, and temperature tolerances. Here, this study addresses key limitations in the advancement of Synechococcus sp. PCC 7002 as an industrial chassis.

  1. 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

  2. Effect of Different Broad Waveband Lights on Membrane Lipids of a Cyanobacterium, Synechococcus sp., as Determined by UPLC-QToF-MS and Vibrational Spectroscopy.

    PubMed

    Montero, Olimpio; Velasco, Marta; Sanz-Arranz, Aurelio; Rull, Fernando

    2016-05-23

    Differential profile of membrane lipids and pigments of a Synechococcus sp. cyanobacterial strain cells exposed to blue, green, red and white light are determined by means of liquid chromatography and mass spectrometry or diode array detection. Raman and ATR-IR spectra of intact cells under the diverse light wavebands are also reported. Blue light cells exhibited an increased content of photosynthetic pigments as well as specific species of membrane glycerolipids as compared to cells exposed to other wavebands. The A630/A680 ratio indicated an increased content of phycobilisomes (PBS) in the blue light-exposed cells. Some differences in the protein conformation between the four light waveband-exposed cells were deduced from the variable absorbance at specific wavenumbers in the FT-Raman and ATR-FTIR spectra, in particular bands assigned to amide I and amide II. Bands from 1180 to 950 cm(-1) in the ATR-FTIR spectrum suggest degraded outer membrane polysaccharide in the blue light-exposed cells.

  3. Independence of carbon and nitrogen control in the posttranslational regulation of nitrate transport in the cyanobacterium Synechococcus sp. strain PCC 7942.

    PubMed

    Rodríguez, R; Kobayashi, M; Omata, T; Lara, C

    1998-08-07

    Nitrate transport by Synechococcus sp. strain PCC 7942 cells was inhibited by ammonium and by inhibitors of CO2 fixation. Ammonium assimilation inhibitors, such as L-methionine D,L-sulfoximine, were known to prevent the negative effects of ammonium and of inhibitors of CO2 fixation on nitrate uptake, leading to propose that CO2 fixation was required to counteract the feed-back inhibition of nitrate assimilation. In NR-less mutants, L-methionine D,L-sulfoximine prevented the negative effects of ammonium on nitrate transport, but not always prevented those of inhibiting CO2 fixation. The carboxy-terminal domain of the NrtC subunit of the nitrate transporter has recently been identified as a regulatory domain involved in N-control. The mutant strain NC2, constructed by deleting the 3' portion of nrtC, showed high nitrate transport activity insensitive to ammonium but sensitive to inhibitors of CO2 fixation. These findings indicate that the C-control and the N-control of nitrate transport are independent at both the physiological and the molecular level.

  4. Effect of Different Broad Waveband Lights on Membrane Lipids of a Cyanobacterium, Synechococcus sp., as Determined by UPLC-QToF-MS and Vibrational Spectroscopy

    PubMed Central

    Montero, Olimpio; Velasco, Marta; Sanz-Arranz, Aurelio; Rull, Fernando

    2016-01-01

    Differential profile of membrane lipids and pigments of a Synechococcus sp. cyanobacterial strain cells exposed to blue, green, red and white light are determined by means of liquid chromatography and mass spectrometry or diode array detection. Raman and ATR-IR spectra of intact cells under the diverse light wavebands are also reported. Blue light cells exhibited an increased content of photosynthetic pigments as well as specific species of membrane glycerolipids as compared to cells exposed to other wavebands. The A630/A680 ratio indicated an increased content of phycobilisomes (PBS) in the blue light-exposed cells. Some differences in the protein conformation between the four light waveband-exposed cells were deduced from the variable absorbance at specific wavenumbers in the FT-Raman and ATR-FTIR spectra, in particular bands assigned to amide I and amide II. Bands from 1180 to 950 cm−1 in the ATR-FTIR spectrum suggest degraded outer membrane polysaccharide in the blue light-exposed cells. PMID:27223306

  5. Functional analysis of the iron-stress induced CP 43' polypeptide of PS II in the cyanobacterium Synechococcus sp. PCC 7942.

    PubMed

    Falk, S; Samson, G; Bruce, D; Huner, N P; Laudenbach, D E

    1995-07-01

    Under conditions of iron-stress, the Photosystem II associated chlorophyll a protein complex designated CP 43', which is encoded by the isiA gene, becomes the major pigment-protein complex in Synechococcus sp. PCC 7942. The isiB gene, which is located immediately downstream of isiA, encodes the protein flavodoxin, which can functionally replace ferredoxin under conditions of iron stress. We have constructed two cyanobacterial insertion mutants which are lacking (i) the CP 43' apoprotein (designated isiA (-)) and (ii) flavodoxin (designated isiB (-)). The function of CP 43' was studied by comparing the cell characteristics, PS II functional absorption cross-sections and Chl a fluorescence parameters from the wild-type, isiA (-) and isiB (-) strains grown under iron-stressed conditions. In all strains grown under iron deprivation, the cell number doubling time was maintained despite marked changes in pigment composition and other cell characteristics. This indicates that iron-starved cells remained viable and that their altered phenotype suggests an adequate acclimation to low iron even in absence of CP 43' and/or flavodoxin. Under both iron conditions, no differences were detected between the three strains in the functional absorption crossection of PS II determined from single turnover flash saturation curves of Chl a fluorescence. This demonstrates that CP 43' is not part of the functional light-harvesting antenna for PS II. In the wild-type and the isiB (-) strain grown under iron-deficient conditions, CP 43' was present in the thylakoid membrane as an uncoupled Chl-protein complex. This was indicated by (1) an increase of the yield of prompt Chl a fluorescence (Fo) and (2) the persistence after PS II trap closure of a fast fluorescence decay component showing a maximum at 685 nm.

  6. Calcium Carbonate Formation by Synechococcus sp. Strain PCC 8806 and Synechococcus sp. Strain PCC 8807

    SciTech Connect

    Lee, Brady D.; William A. Apel; Michelle R. Walton

    2006-12-01

    Precipitation of CaCO3 catalyzed by the growth and physiology of cyanobacteria in the Genus Synechococcus represents a potential mechanism for sequestration of CO2 produced during the burning of coal for power generation. Microcosm experiments were performed in which Synechococcus sp. strain PCC 8806 and Synechococcus sp. strain PCC 8807 were tested for their ability to calcify when exposed to a fixed calcium concentration of 3.4 mM and bicarbonate concentrations of 0.5, 1.25 and 2.5 mM. Disappearance of soluble calcium was used as an indicator of CaCO3 formation; results from metabolically active microcosms were compared to controls with no cells or no carbonate added. Synechococcus sp. strain PCC 8806 removed calcium continuously over the duration of the experiment with approximately 18.6 mg of calcium in the solid phase. Calcium removal occurred over a two-day time period when Synechococcus sp. strain PCC 8807 was tested and only 8.9 mg of calcium was removed in the solid phase. The ability of the cyanobacteria to create an alkaline growth environment appeared to be the primary factor responsible for CaCO3 precipitation in these experiments. Removal of inorganic carbon by fixation into biomass was insignificant compared to the mass of inorganic carbon removed by incorporation into the growing CaCO3 solid.

  7. Modular synthase-encoding gene involved in α-olefin biosynthesis in Synechococcus sp. strain PCC 7002.

    PubMed

    Mendez-Perez, Daniel; Begemann, Matthew B; Pfleger, Brian F

    2011-06-01

    A gene involved in the production of medium-chain α-olefins was identified in the cyanobacterium Synechococcus sp. strain PCC 7002. The gene encodes a large multidomain protein with homology to type I polyketide synthases, suggesting a route for hydrocarbon biosynthesis from fatty acids via an elongation decarboxylation mechanism.

  8. Diversity in photosynthetic electron transport under [CO2]-limitation: the cyanobacterium Synechococcus sp. PCC 7002 and green alga Chlamydomonas reinhardtii drive an O2-dependent alternative electron flow and non-photochemical quenching of chlorophyll fluorescence during CO2-limited photosynthesis.

    PubMed

    Shimakawa, Ginga; Akimoto, Seiji; Ueno, Yoshifumi; Wada, Ayumi; Shaku, Keiichiro; Takahashi, Yuichiro; Miyake, Chikahiro

    2016-12-01

    Some cyanobacteria, but not all, experience an induction of alternative electron flow (AEF) during CO2-limited photosynthesis. For example, Synechocystis sp. PCC 6803 (S. 6803) exhibits AEF, but Synechococcus elongatus sp. PCC 7942 does not. This difference is due to the presence of flavodiiron 2 and 4 proteins (FLV2/4) in S. 6803, which catalyze electron donation to O2. In this study, we observed a low-[CO2] induced AEF in the marine cyanobacterium Synechococcus sp. PCC 7002 that lacks FLV2/4. The AEF shows high affinity for O2, compared with AEF mediated by FLV2/4 in S. 6803, and can proceed under extreme low [O2] (about a few µM O2). Further, the transition from CO2-saturated to CO2-limited photosynthesis leads a preferential excitation of PSI to PSII and increased non-photochemical quenching of chlorophyll fluorescence. We found that the model green alga Chlamydomonas reinhardtii also has an O2-dependent AEF showing the same affinity for O2 as that in S. 7002. These data represent the diverse molecular mechanisms to drive AEF in cyanobacteria and green algae. In this paper, we further discuss the diversity, the evolution, and the physiological function of strategy to CO2-limitation in cyanobacterial and green algal photosynthesis.

  9. Complementation of Cobalamin Auxotrophy in Synechococcus sp. Strain PCC 7002 and Validation of a Putative Cobalamin Riboswitch In Vivo

    PubMed Central

    Pérez, Adam A.; Liu, Zhenfeng; Rodionov, Dmitry A.; Li, Zhongkui

    2016-01-01

    ABSTRACT The euryhaline cyanobacterium Synechococcus sp. strain PCC 7002 has an obligate requirement for exogenous vitamin B12 (cobalamin), but little is known about the roles of this compound in cyanobacteria. Bioinformatic analyses suggest that only the terminal enzyme in methionine biosynthesis, methionine synthase, requires cobalamin as a coenzyme in Synechococcus sp. strain PCC 7002. Methionine synthase (MetH) catalyzes the transfer of a methyl group from N5-methyl-5,6,7,8-tetrahydrofolate to l-homocysteine during l-methionine synthesis and uses methylcobalamin as an intermediate methyl donor. Numerous bacteria and plants alternatively employ a cobalamin-independent methionine synthase isozyme, MetE, that catalyzes the same methyl transfer reaction as MetH but uses N5-methyl-5,6,7,8-tetrahydrofolate directly as the methyl donor. The cobalamin auxotrophy of Synechococcus sp. strain PCC 7002 was complemented by using the metE gene from the closely related cyanobacterium Synechococcus sp. strain PCC 73109, which possesses genes for both methionine synthases. This result suggests that methionine biosynthesis is probably the sole use of cobalamin in Synechococcus sp. strain PCC 7002. Furthermore, a cobalamin-repressible gene expression system was developed in Synechococcus sp. strain PCC 7002 that was used to validate the presence of a cobalamin riboswitch in the promoter region of metE from Synechococcus sp. strain PCC 73109. This riboswitch acts as a cobalamin-dependent transcriptional attenuator for metE in that organism. IMPORTANCE Synechococcus sp. strain PCC 7002 is a cobalamin auxotroph because, like eukaryotic marine algae, it uses a cobalamin-dependent methionine synthase (MetH) for the final step of l-methionine biosynthesis but cannot synthesize cobalamin de novo. Heterologous expression of metE, encoding cobalamin-independent methionine synthase, from Synechococcus sp. strain PCC 73109, relieved this auxotrophy and enabled the construction of a truly

  10. Growth of Chlamydomonas reinhardtii in acetate-free medium when co-cultured with alginate-encapsulated, acetate-producing strains of Synechococcus sp. PCC 7002

    DOE PAGES

    Therien, Jesse B.; Zadvornyy, Oleg A.; Posewitz, Matthew C.; ...

    2014-10-18

    The model alga Chlamydomonas reinhardtii requires acetate as a co-substrate for optimal production of lipids, and the addition of acetate to culture media has practical and economic implications for algal biofuel production. We demonstrate the growth of C. reinhardtii on acetate provided by mutant strains of the cyanobacterium Synechococcus sp. PCC7002.

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

    PubMed Central

    Hood, Rachel D.; Higgins, Sean A.; Flamholz, Avi; Nichols, Robert J.

    2016-01-01

    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

  12. Network analysis of transcriptomics expands regulatory landscapes in Synechococcus sp. PCC 7002

    PubMed Central

    McClure, Ryan S.; Overall, Christopher C.; McDermott, Jason E.; Hill, Eric A.; Markillie, Lye Meng; McCue, Lee Ann; Taylor, Ronald C.; Ludwig, Marcus; Bryant, Donald A.; Beliaev, Alexander S.

    2016-01-01

    Cyanobacterial regulation of gene expression must contend with a genome organization that lacks apparent functional context, as the majority of cellular processes and metabolic pathways are encoded by genes found at disparate locations across the genome and relatively few transcription factors exist. In this study, global transcript abundance data from the model cyanobacterium Synechococcus sp. PCC 7002 grown under 42 different conditions was analyzed using Context-Likelihood of Relatedness (CLR). The resulting network, organized into 11 modules, provided insight into transcriptional network topology as well as grouping genes by function and linking their response to specific environmental variables. When used in conjunction with genome sequences, the network allowed identification and expansion of novel potential targets of both DNA binding proteins and sRNA regulators. These results offer a new perspective into the multi-level regulation that governs cellular adaptations of the fast-growing physiologically robust cyanobacterium Synechococcus sp. PCC 7002 to changing environmental variables. It also provides a methodological high-throughput approach to studying multi-scale regulatory mechanisms that operate in cyanobacteria. Finally, it provides valuable context for integrating systems-level data to enhance gene grouping based on annotated function, especially in organisms where traditional context analyses cannot be implemented due to lack of operon-based functional organization. PMID:27568004

  13. Growth of Chlamydomonas reinhardtii in acetate-free medium when co-cultured with alginate-encapsulated, acetate-producing strains of Synechococcus sp. PCC 7002.

    PubMed

    Therien, Jesse B; Zadvornyy, Oleg A; Posewitz, Matthew C; Bryant, Donald A; Peters, John W

    2014-01-01

    The model alga Chlamydomonas reinhardtii requires acetate as a co-substrate for optimal production of lipids, and the addition of acetate to culture media has practical and economic implications for algal biofuel production. Here we demonstrate the growth of C. reinhardtii on acetate provided by mutant strains of the cyanobacterium Synechococcus sp. PCC 7002. Optimal growth conditions for co-cultivation of C. reinhardtii with wild-type and mutant strains of Synechococcus sp. 7002 were established. In co-culture, acetate produced by a glycogen synthase knockout mutant of Synechococcus sp. PCC 7002 was able to support the growth of a lipid-accumulating mutant strain of C. reinhardtii defective in starch production. Encapsulation of Synechococcus sp. PCC 7002 using an alginate matrix was successfully employed in co-cultures to limit growth and maintain the stability. The ability of immobilized strains of the cyanobacterium Synechococcus sp. PCC 7002 to produce acetate at a level adequate to support the growth of lipid-accumulating strains of C. reinhartdii offers a potentially practical, photosynthetic alternative to providing exogenous acetate into growth media.

  14. CRISPR/Cas9 mediated targeted mutagenesis of the fast growing cyanobacterium Synechococcus elongatus UTEX 2973

    DOE PAGES

    Wendt, Kristen E.; Ungerer, Justin; Cobb, Ryan E.; ...

    2016-06-23

    As autotrophic prokaryotes, cyanobacteria are ideal chassis organisms for sustainable production of various useful compounds. The newly characterized cyanobacterium Synechococcus elongatus UTEX 2973 is a promising candidate for serving as a microbial cell factory because of its unusually rapid growth rate. Here, we seek to develop a genetic toolkit that enables extensive genomic engineering of Synechococcus 2973 by implementing a CRISPR/Cas9 editing system. We targeted the nblA gene because of its important role in biological response to nitrogen deprivation conditions. First, we determined that the Streptococcus pyogenes Cas9 enzyme is toxic in cyanobacteria, and conjugational transfer of stable, replicating constructsmore » containing the cas9 gene resulted in lethality. However, after switching to a vector that permitted transient expression of the cas9 gene, we achieved markerless editing in 100 % of cyanobacterial exconjugants after the first patch. Moreover, we could readily cure the organisms of antibiotic resistance, resulting in a markerless deletion strain. In conclusion, high expression levels of the Cas9 protein in Synechococcus 2973 appear to be toxic and result in cell death. However, introduction of a CRISPR/Cas9 genome editing system on a plasmid backbone that leads to transient cas9 expression allowed for efficient markerless genome editing in a wild type genetic background.« less

  15. Production of volatile organic compounds by cyanobacteria Synechococcus sp.

    NASA Astrophysics Data System (ADS)

    Hiraiwa, M.; Abe, M.; Hashimoto, S.

    2014-12-01

    Phytoplankton are known to produce volatile organic compounds (VOCs), which contribute to environmental problems such as global warming and decomposition of stratospheric ozone. For example, picophytoplankton, such as Prochlorococcus and Synechococcus, are distributed in freshwater and oceans worldwide, accounting for a large proportion of biomass and primary production in the open ocean. However, to date, little is known about the production of VOCs by picophytoplankton. In this study, VOCs production by cyanobacteria Synechococcus sp. (NIES-981) was investigated. Synechococcus sp. was obtained from the National Institute for Environmental Studies (NIES), Japan, and cultured at 24°C in autoclaved f/2-Si medium under 54 ± 3 µE m-2 s-1 (1 E = 1 mol of photons) with a 12-h light and 12-h dark cycle. VOCs concentrations were determined using a purge-and-trap gas chromatograph-mass spectrometer (Agilent 5973). The concentrations of chlorophyll a (Chl a) were also determined using a fluorometer (Turner TD-700). Bromomethane (CH3Br) and isoprene were produced by Synechococcus sp. Isoprene production was similar to those of other phytoplankton species reported earlier. Isoprene was produced when Chl a was increasing in the early stage of the incubation period (5-15 days of incubation time, exponential phase), but CH3Br was produced when Chl a was reduced in the late stage of the incubation period (30-40 days of incubation time, death phase).

  16. Computational evaluation of Synechococcus sp. PCC 7002 metabolism for chemical production

    SciTech Connect

    Vu, Trang; Hill, Eric A.; Kucek, Leo A.; Konopka, Allan; Beliaev, Alex S.; Reed, Jennifer L.

    2013-05-24

    Cyanobacteria are ideal metabolic engineering platforms for carbon-neutral biotechnology because they directly convert CO2 to a range of valuable products. In this study, we present a computational assessment of biochemical production in Synechococcus sp. PCC 7002 (Synechococcus 7002), a fast growing cyanobacterium whose genome has been sequenced, and for which genetic modification methods have been developed. We evaluated the maximum theoretical yields (mol product per mol CO2 or mol photon) of producing various chemicals under photoautotrophic and dark conditions using a genome-scale metabolic model of Synechococcus 7002. We found that the yields were lower under dark conditions, compared to photoautotrophic conditions, due to the limited amount of energy and reductant generated from glycogen. We also examined the effects of photon and CO2 limitations on chemical production under photoautotrophic conditions. In addition, using various computational methods such as MOMA, RELATCH, and OptORF, we identified gene-knockout mutants that are predicted to improve chemical production under photoautotrophic and/or dark anoxic conditions. These computational results are useful for metabolic engineering of cyanobacteria to synthesize valueadded products.

  17. 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.

  18. Collapsing aged culture of the cyanobacterium Synechococcus elongatus produces compound(s) toxic to photosynthetic organisms.

    PubMed

    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.

  19. 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

  20. Network analysis of transcriptomics expands regulatory landscapes in Synechococcus sp. PCC 7002

    SciTech Connect

    McClure, Ryan S.; Overall, Christopher C.; McDermott, Jason E.; Hill, Eric A.; Markillie, Lye Meng; McCue, Lee Ann; Taylor, Ronald C.; Ludwig, Marcus; Bryant, Donald A.; Beliaev, Alexander S.

    2016-08-27

    Cyanobacterial regulation of gene expression must contend with a genome organization that lacks apparent functional context, as the majority of cellular processes and metabolic pathways are encoded by genes found at disparate locations across the genome. In addition, the fact that coordinated regulation of cyanobacterial cellular machinery takes place with significantly fewer transcription factors, compared to other Eubacteria, suggests the involvement of post-transcriptional mechanisms and regulatory adaptations which are not fully understood. Global transcript abundance from model cyanobacterium Synechococcus sp. PCC 7002 grown under 42 different conditions was analyzed using context-likelihood of relatedness. The resulting 903-gene network, which was organized into 11 modules, not only allowed classification of cyanobacterial responses to specific environmental variables but provided insight into the transcriptional network topology and led to the expansion of predicted regulons. When used in conjunction with genome sequence, the global transcript abundance allowed identification of putative post-transcriptional changes in expression as well as novel potential targets of both DNA binding proteins and asRNA regulators. The results offer a new perspective into the multi-level regulation that governs cellular adaptations of fast-growing physiologically robust cyanobacterium Synechococcus sp. PCC 7002 to changing environmental variables. It also extends a methodological knowledge-based framework for studying multi-scale regulatory mechanisms that operate in cyanobacteria. Finally, it provides valuable context for integrating systems-level data to enhance evidence-driven genomic annotation, especially in organisms where traditional context analyses cannot be implemented due to lack of operon-based functional organization.

  1. Role of Polyphosphate in Thermophilic Synechococcus sp. from Microbial Mats

    PubMed Central

    Fazeli, Fariba; Grote, Alexandra; Grossman, Arthur R.; Bhaya, Devaki

    2013-01-01

    Synechococcus OS-B′, a thermophilic unicellular cyanobacterium, recently isolated from the microbial mats in Octopus Spring (Yellowstone National Park), induces a suite of genes, including phosphatases and transporters, in response to phosphorus (P) starvation. Here we describe two different approaches to examine the ability of Synechococcus OS-B′ to synthesize and break down polyphosphate (poly P), a key storage compound in many prokaryotes. First, we developed a transformation protocol to create mutants in the polyphosphate kinase (ppk), the major enzyme responsible for the synthesis of poly P. The ppk mutant exhibited a pleiotropic phenotype with defects in poly P accumulation, aberrant levels of Pho regulon transcripts, growth defects, and changes in cell size and exopolysaccharide levels, among others. Second, we measured transcripts of ppk and ppx (encoding the polyphosphatase) directly from mat samples and found that the levels varied dramatically over a diel cycle. We also used Western blot analysis to quantify levels of PPK and PPX and found that these enzymes differentially accumulated during the diel cycle. Levels of polyphosphate kinase peaked at night, while polyphosphatase levels were highest during the early morning hours. We hypothesize that the opposing activities of these two enzymes allow cells to store and utilize poly P to optimize growth over a diel cycle. PMID:23687278

  2. Zn2+-Inducible Expression Platform for Synechococcus sp. Strain PCC 7002 Based on the smtA Promoter/Operator and smtB Repressor.

    PubMed

    Pérez, Adam A; Gajewski, John P; Ferlez, Bryan H; Ludwig, Marcus; Baker, Carol S; Golbeck, John H; Bryant, Donald A

    2017-02-01

    Synechococcus sp. strain PCC 7002 has been gaining significance as both a model system for photosynthesis research and for industrial applications. Until recently, the genetic toolbox for this model cyanobacterium was rather limited and relied primarily on tools that only allowed constitutive gene expression. This work describes a two-plasmid, Zn(2+)-inducible expression platform that is coupled with a zurA mutation, providing enhanced Zn(2+) uptake. The control elements are based on the metal homeostasis system of a class II metallothionein gene (smtA7942) and its cognate SmtB7942 repressor from Synechococcus elongatus strain PCC 7942. Under optimal induction conditions, yellow fluorescent protein (YFP) levels were about half of those obtained with the strong, constitutive phycocyanin (cpcBA6803) promoter of Synechocystis sp. strain PCC 6803. This metal-inducible expression system in Synechococcus sp. strain PCC 7002 allowed the titratable gene expression of YFP that was up to 19-fold greater than the background level. This system was utilized successfully to control the expression of the Drosophila melanogaster β-carotene 15,15'-dioxygenase, NinaB, which is toxic when constitutively expressed from a strong promoter in Synechococcus sp. strain PCC 7002. Together, these properties establish this metal-inducible system as an additional useful tool that is capable of controlling gene expression for applications ranging from basic research to synthetic biology in Synechococcus sp. strain PCC 7002.

  3. Posttranslational Regulation of Nitrate Assimilation in the Cyanobacterium Synechocystis sp. Strain PCC 6803

    PubMed Central

    Kobayashi, Masaki; Takatani, Nobuyuki; Tanigawa, Mari; Omata, Tatsuo

    2005-01-01

    Posttranslational regulation of nitrate assimilation was studied in the cyanobacterium Synechocystis sp. strain PCC 6803. The ABC-type nitrate and nitrite bispecific transporter encoded by the nrtABCD genes was completely inhibited by ammonium as in Synechococcus elongatus strain PCC 7942. Nitrate reductase was insensitive to ammonium, while it is inhibited in the Synechococcus strain. Nitrite reductase was also insensitive to ammonium. The inhibition of nitrate and nitrite transport required the PII protein (glnB gene product) and the C-terminal domain of NrtC, one of the two ATP-binding subunits of the transporter, as in the Synechococcus strain. Mutants expressing the PII derivatives in which Ala or Glu is substituted for the conserved Ser49, which has been shown to be the phosphorylation site in the Synechococcus strain, showed ammonium-promoted inhibition of nitrate uptake like that of the wild-type strain. The S49A and S49E substitutions in GlnB did not affect the regulation of the nitrate and nitrite transporter in Synechococcus either. These results indicated that the presence or absence of negative electric charge at the 49th position does not affect the activity of the PII protein to regulate the cyanobacterial ABC-type nitrate and nitrite transporter according to the cellular nitrogen status. This finding suggested that the permanent inhibition of nitrate assimilation by an S49A derivative of PII, as was previously reported for Synechococcus elongatus strain PCC 7942, is likely to have resulted from inhibition of nitrate reductase rather than the nitrate and nitrite transporter. PMID:15629921

  4. Posttranslational regulation of nitrate assimilation in the cyanobacterium Synechocystis sp. strain PCC 6803.

    PubMed

    Kobayashi, Masaki; Takatani, Nobuyuki; Tanigawa, Mari; Omata, Tatsuo

    2005-01-01

    Posttranslational regulation of nitrate assimilation was studied in the cyanobacterium Synechocystis sp. strain PCC 6803. The ABC-type nitrate and nitrite bispecific transporter encoded by the nrtABCD genes was completely inhibited by ammonium as in Synechococcus elongatus strain PCC 7942. Nitrate reductase was insensitive to ammonium, while it is inhibited in the Synechococcus strain. Nitrite reductase was also insensitive to ammonium. The inhibition of nitrate and nitrite transport required the PII protein (glnB gene product) and the C-terminal domain of NrtC, one of the two ATP-binding subunits of the transporter, as in the Synechococcus strain. Mutants expressing the PII derivatives in which Ala or Glu is substituted for the conserved Ser49, which has been shown to be the phosphorylation site in the Synechococcus strain, showed ammonium-promoted inhibition of nitrate uptake like that of the wild-type strain. The S49A and S49E substitutions in GlnB did not affect the regulation of the nitrate and nitrite transporter in Synechococcus either. These results indicated that the presence or absence of negative electric charge at the 49th position does not affect the activity of the PII protein to regulate the cyanobacterial ABC-type nitrate and nitrite transporter according to the cellular nitrogen status. This finding suggested that the permanent inhibition of nitrate assimilation by an S49A derivative of PII, as was previously reported for Synechococcus elongatus strain PCC 7942, is likely to have resulted from inhibition of nitrate reductase rather than the nitrate and nitrite transporter.

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

    SciTech Connect

    Schafheutle, M.E.; Setlikova, E.; Timmins, P.A.; Johner, H.; Gutgesell, P.; Setlik, I.; Welte, W. )

    1990-02-06

    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.

  6. 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.

  7. 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.

  8. Production of γ-linolenic acid and stearidonic acid by Synechococcus sp. PCC7002 containing cyanobacterial fatty acid desaturase genes

    NASA Astrophysics Data System (ADS)

    Dong, Xuewei; He, Qingfang; Peng, Zhenying; Yu, Jinhui; Bian, Fei; Li, Youzhi; Bi, Yuping

    2016-07-01

    Genetic modification is useful for improving the nutritional qualities of cyanobacteria. To increase the total unsaturated fatty acid content, along with the ratio of ω-3/ω-6 fatty acids, genetic engineering can be used to modify fatty acid metabolism. Synechococcus sp. PCC7002, a fast-growing cyanobacterium, does not contain a Δ6 desaturase gene and is therefore unable to synthesize γ-linolenic acid (GLA) and stearidonic acid (SDA), which are important in human health. In this work, we constructed recombinant vectors Syd6D, Syd15D and Syd6Dd15D to express the Δ15 desaturase and Δ6 desaturase genes from Synechocystis PCC6803 in Synechococcus sp. PCC7002, with the aim of expressing polyunsaturated fatty acids. Overexpression of the Δ15 desaturase gene in Synechococcus resulted in 5.4 times greater accumulation of α-linolenic acid compared with the wild-type while Δ6 desaturase gene expression produced both GLA and SDA. Co-expression of the two genes resulted in low-level accumulation of GLA but much larger amounts of SDA, accounting for as much to 11.64% of the total fatty acid content.

  9. 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

  10. 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.

  11. Draft Genome Sequence of Synechococcus sp. Strain CB0101, Isolated From the Chesapeake Bay Estuary.

    PubMed

    Marsan, David; Wommack, K Eric; Ravel, Jacques; Chen, Feng

    2014-01-09

    Here, we report the draft genome sequence of the estuarine Synechococcus sp. strain CB0101. The genomics information of this strain will facilitate the study of the poorly understood Synechococcus subcluster 5.2 and how this strain is capable of thriving in a dynamic estuarine system, such as the Chesapeake Bay.

  12. Cell surface reactivity of Synechococcus sp. PCC 7002: Implications for metal sorption from seawater

    NASA Astrophysics Data System (ADS)

    Liu, Yuxia; Alessi, D. S.; Owttrim, G. W.; Petrash, D. A.; Mloszewska, A. M.; Lalonde, S. V.; Martinez, R. E.; Zhou, Qixing; Konhauser, K. O.

    2015-11-01

    The past two decades have seen a significant advancement in our understanding of bacterial surface chemistry and the ability of microbes to bind metals from aqueous solutions. Much of this work has been aimed at benthic, mat-forming species in an effort to model the mechanisms by which microbes may exert control over metal contaminant transport in soils and groundwater. However, there is a distinct paucity of information pertaining to the surface chemistry of marine planktonic species, and their ability to bind trace metals from the ocean's photic zone. To this end, the surface properties of the cyanobacterium Synechococcus sp. PCC 7002 were studied as this genus is one of the dominant marine phytoplankton, and as such, contributes significantly to metal cycling in the ocean's photic zone. Zeta potential measurement indicates that the cell surfaces display a net negative charge. This was supported by potentiometric titration and Fourier transform infrared spectroscopy analyses demonstrating that the cells are dominated by surface proton releasing ligands, including carboxyl, phosphoryl and amino functional groups, with a total ligand density of 34.18 ± 1.62 mmol/g (dry biomass). Cd adsorption experiments further reveal that carboxyl groups play a primary role in metal adsorption, with 1.0 g of dry biomass binding an equivalent of 7.05 × 10-5 M of Cd from solution at pH = 8. To put this value into context, in 1 L of seawater, and with an open-ocean population of Synechococcus of 105 cells/mL in the photic zone, approximately 10 nmol of Cd could potentially be adsorbed by the cyanobacteria; an amount equivalent to seawater Cd concentrations. Although we have only focused on one microbial species and one metal cation, and we have not considered trace element assimilation, our results highlight the potential role of surface sorption by phytoplankton in the cycling of metals in the ocean.

  13. High Iron Requirement for Growth, Photosynthesis, and Low-light Acclimation in the Marine Cyanobacterium Synechococcus bacillaris

    NASA Astrophysics Data System (ADS)

    Sunda, W. G.; Huntsman, S. A.

    2016-02-01

    Iron is a critical nutrient in photosynthesis and limits phytoplankton growth in large regions of the ocean. Most of the iron in phytoplankton occurs in iron-containing proteins in the photosynthetic apparatus, and thus interactions among cellular iron, light, and growth rate are predicted. In agreement with this prediction, decreasing light intensity increased the cellular iron:carbon (Fe:C) ratio needed to support a given growth rate by 2- to 3-fold in both a coastal diatom Thalassiosira pseudonana, and a coastal cyanobacterium Synechococcus bacillaris due to an increase in iron-containing photosynthetic units. However, although the light responses were similar, the cellular Fe:C ratios needed to support a given growth rate were 5- to 8-fold higher in the cyanobacterium than in the diatom, a pattern seen in other Syechococcus isolates and eukaryotic phytoplankton. Due to the high iron requirement for growth and low light acclimation, we might expect Synechococcus to be at a competitive disadvantage in 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 eukaryotic algae typically dominate the phytoplankton biomass in the mid to lower DCM.

  14. CRISPR/Cas9 mediated targeted mutagenesis of the fast growing cyanobacterium Synechococcus elongatus UTEX 2973

    SciTech Connect

    Wendt, Kristen E.; Ungerer, Justin; Cobb, Ryan E.; Zhao, Huimin; Pakrasi, Himadri B.

    2016-06-23

    As autotrophic prokaryotes, cyanobacteria are ideal chassis organisms for sustainable production of various useful compounds. The newly characterized cyanobacterium Synechococcus elongatus UTEX 2973 is a promising candidate for serving as a microbial cell factory because of its unusually rapid growth rate. Here, we seek to develop a genetic toolkit that enables extensive genomic engineering of Synechococcus 2973 by implementing a CRISPR/Cas9 editing system. We targeted the nblA gene because of its important role in biological response to nitrogen deprivation conditions. First, we determined that the Streptococcus pyogenes Cas9 enzyme is toxic in cyanobacteria, and conjugational transfer of stable, replicating constructs containing the cas9 gene resulted in lethality. However, after switching to a vector that permitted transient expression of the cas9 gene, we achieved markerless editing in 100 % of cyanobacterial exconjugants after the first patch. Moreover, we could readily cure the organisms of antibiotic resistance, resulting in a markerless deletion strain. In conclusion, high expression levels of the Cas9 protein in Synechococcus 2973 appear to be toxic and result in cell death. However, introduction of a CRISPR/Cas9 genome editing system on a plasmid backbone that leads to transient cas9 expression allowed for efficient markerless genome editing in a wild type genetic background.

  15. Engineering limonene and bisabolene production in wild type and a glycogen-deficient mutant of Synechococcus sp. PCC 7002

    SciTech Connect

    Davies, Fiona K.; Work, Victoria H.; Beliaev, Alex S.; Posewitz, Matthew C.

    2014-06-19

    The plant terpenoids limonene (C10H16) and α-bisabolene (C15H24) are hydrocarbon precursors to a range of industrially-relevant chemicals. High-titer microbial synthesis of limonene and α- bisabolene could pave the way for advances in in vivo engineering of tailor-made hydrocarbons, and production at commercial scale. We have engineered the fast-growing unicellular euryhaline cyanobacterium Synechococcus sp. PCC 7002 to produce yields of 4 mg L-1 limonene and 0.6 mg L-1 α-bisabolene through heterologous expression of the Mentha spicata L-limonene synthase or the Abies grandis (E)-α-bisabolene synthase genes, respectively. Titers were significantly higher when a dodecane overlay was applied during culturing, suggesting either that dodecane traps large quantities of volatile limonene and α-bisabolene that would otherwise be lost to evaporation, and/or that continuous product removal in dodecane alleviates product feedback inhibition to promote higher rates of synthesis. We also investigate limonene and bisabolene production in the ΔglgC genetic background, where carbon partitioning is redirected at the expense of glycogen biosynthesis. The Synechococcus sp. PCC 7002 ΔglgC mutant excreted a suite of overflow metabolites (α-ketoisocaproate, pyruvate, α-ketoglutarate, succinate and acetate) during nitrogen deprivation, and also at the onset of stationary growth in nutrient-replete media. None of the excreted metabolites, however, appeared to be effectively utilized for terpenoid metabolism. Interestingly, we observed a 1.6 to 2.5-fold increase in the extracellular concentration of most excreted organic acids when the ΔglgC mutant was conferred with the ability to produce limonene. Overall, Synechococcus sp. PCC 7002 provides a highly promising platform for terpenoid biosynthetic and metabolic engineering efforts.

  16. Engineering Limonene and Bisabolene Production in Wild Type and a Glycogen-Deficient Mutant of Synechococcus sp. PCC 7002.

    PubMed

    Davies, Fiona K; Work, Victoria H; Beliaev, Alexander S; Posewitz, Matthew C

    2014-01-01

    The plant terpenoids limonene (C10H16) and α-bisabolene (C15H24) are hydrocarbon precursors to a range of industrially relevant chemicals. High-titer microbial synthesis of limonene and α-bisabolene could pave the way for advances in in vivo engineering of tailor-made hydrocarbons, and production at commercial scale. We have engineered the fast-growing unicellular euryhaline cyanobacterium Synechococcus sp. PCC 7002 to produce yields of 4 mg L(-1) limonene and 0.6 mg L(-1) α-bisabolene through heterologous expression of the Mentha spicatal-limonene synthase or the Abies grandis (E)-α-bisabolene synthase genes, respectively. Titers were significantly higher when a dodecane overlay was applied during culturing, suggesting either that dodecane traps large quantities of volatile limonene or α-bisabolene that would otherwise be lost to evaporation, and/or that continuous product removal in dodecane alleviates product feedback inhibition to promote higher rates of synthesis. We also investigate limonene and bisabolene production in the ΔglgC genetic background, where carbon partitioning is redirected at the expense of glycogen biosynthesis. The Synechococcus sp. PCC 7002 ΔglgC mutant excreted a suite of overflow metabolites (α-ketoisocaproate, pyruvate, α-ketoglutarate, succinate, and acetate) during nitrogen-deprivation, and also at the onset of stationary growth in nutrient-replete media. None of the excreted metabolites, however, appeared to be effectively utilized for terpenoid metabolism. Interestingly, we observed a 1.6- to 2.5-fold increase in the extracellular concentration of most excreted organic acids when the ΔglgC mutant was conferred with the ability to produce limonene. Overall, Synechococcus sp. PCC 7002 provides a highly promising platform for terpenoid biosynthetic and metabolic engineering efforts.

  17. Engineering Limonene and Bisabolene Production in Wild Type and a Glycogen-Deficient Mutant of Synechococcus sp. PCC 7002

    PubMed Central

    Davies, Fiona K.; Work, Victoria H.; Beliaev, Alexander S.; Posewitz, Matthew C.

    2014-01-01

    The plant terpenoids limonene (C10H16) and α-bisabolene (C15H24) are hydrocarbon precursors to a range of industrially relevant chemicals. High-titer microbial synthesis of limonene and α-bisabolene could pave the way for advances in in vivo engineering of tailor-made hydrocarbons, and production at commercial scale. We have engineered the fast-growing unicellular euryhaline cyanobacterium Synechococcus sp. PCC 7002 to produce yields of 4 mg L−1 limonene and 0.6 mg L−1 α-bisabolene through heterologous expression of the Mentha spicata l-limonene synthase or the Abies grandis (E)-α-bisabolene synthase genes, respectively. Titers were significantly higher when a dodecane overlay was applied during culturing, suggesting either that dodecane traps large quantities of volatile limonene or α-bisabolene that would otherwise be lost to evaporation, and/or that continuous product removal in dodecane alleviates product feedback inhibition to promote higher rates of synthesis. We also investigate limonene and bisabolene production in the ΔglgC genetic background, where carbon partitioning is redirected at the expense of glycogen biosynthesis. The Synechococcus sp. PCC 7002 ΔglgC mutant excreted a suite of overflow metabolites (α-ketoisocaproate, pyruvate, α-ketoglutarate, succinate, and acetate) during nitrogen-deprivation, and also at the onset of stationary growth in nutrient-replete media. None of the excreted metabolites, however, appeared to be effectively utilized for terpenoid metabolism. Interestingly, we observed a 1.6- to 2.5-fold increase in the extracellular concentration of most excreted organic acids when the ΔglgC mutant was conferred with the ability to produce limonene. Overall, Synechococcus sp. PCC 7002 provides a highly promising platform for terpenoid biosynthetic and metabolic engineering efforts. PMID:25152894

  18. A Desaturase Gene Involved in the Formation of 1,14-Nonadecadiene in Synechococcus sp. Strain PCC 7002

    PubMed Central

    Mendez-Perez, Daniel; Herman, Nicolaus A.

    2014-01-01

    The marine cyanobacterium Synechococcus sp. strain PCC 7002 synthesizes two alkenes, 1-nonadecene and 1,14-nonadecadiene. Whereas the genetic basis for the biosynthesis of the terminal double bond in both alkenes has been characterized, the origin of the internal double bond in 1,14-nonadecadiene has not. In this study, we demonstrate that a gene encoding an uncharacterized desaturase is involved in the formation of the internal double bond of 1,14-nonadecadiene. Further, at low temperatures, the desaturase gene is essential for growth, and in wild-type cells the levels of 1,14-nonadecadiene increase relative to that of cells grown at 38°C. These data suggest that 1,14-nonadecadiene plays a role in responding to cold stress. PMID:25063658

  19. Lysogeny and lytic viral production during a bloom of the cyanobacterium Synechococcus spp.

    PubMed

    Ortmann, A C; Lawrence, J E; Suttle, C A

    2002-03-01

    Lytic viral production and lysogeny were investigated in cyanobacteria and heterotrophic bacteria during a bloom of Synechococcus spp. in a pristine fjord in British Columbia, Canada. Triplicate seawater samples were incubated with and without mitomycin C and the abundances of heterotrophic bacteria, cyanobacteria, total viruses and infectious cyanophage were followed over 24 h. Addition of mitomycin C led to increases in total viral abundance as well as the abundance of cyanophages infecting Synechococcus strain DC2. Given typical estimates of burst size, these increases were consistent with 80% of the heterotrophic bacteria and 0.6% of Synechococcus cells being inducible by the addition of mitomycin C. This is the highest percentage of lysogens reported for a natural microbial community and demonstrates induction in a marine Synechococcus population. It is likely that the cyanophage production following the addition of mitomycin C was much higher than that titered against a single strain of Synechococcus; hence this estimate is a minimum. In untreated seawater samples, lytic viral production was estimated to remove ca. 27% of the gross heterotrophic bacterial production, and a minimum of 1.0% of the gross cyanobacterial production. Our results demonstrate very high levels of lysogeny in the heterotrophic bacterial community, outside of an oligotrophic environment, and the presence of inducible lysogens in Synechococcus spp. during a naturally occurring bloom. These data emphasize the need for further examination of the factors influencing lytic and lysogenic viral infection in natural microbial communities.

  20. Growth of the cyanobacterium Synechococcus leopoliensis CCAP1405/1 on agar media in the presence of heterotrophic bacteria.

    PubMed

    Hayashi, Shohei; Itoh, Kazuhito; Suyama, Kousuke

    2011-01-01

    The cyanobacterium Synechococcus leopoliensis CCAP1405/1 does not grow on common solid media made of agar, agarose HT, noble agar, gelrite and gelatin, although it grows in liquid media with the same components. The inoculation of S. leopoliensis CCAP1405/1 at a high initial cell density allowed it to grow on the agar media, and co-inoculation with one of the heterotrophic bacterial strains belonging to a wide range of phylogeny, showed the same effects even at a low initial cell density of S. leopoliensis CCAP1405/1. The addition of thiosulfate and high concentrations of vitamin B(12), biotin and thiamine also supported growth on solid media, but catalase had no effect. On inorganic solid media, the autotrophic cyanobacterial strain supported the growth of heterotrophic bacteria, suggesting mutual interaction.

  1. Growth of Chlamydomonas reinhardtii in acetate-free medium when co-cultured with alginate-encapsulated, acetate-producing strains of Synechococcus sp. PCC 7002

    SciTech Connect

    Therien, Jesse B.; Zadvornyy, Oleg A.; Posewitz, Matthew C.; Bryant, Donald A.; Peters, John W.

    2014-10-18

    The model alga Chlamydomonas reinhardtii requires acetate as a co-substrate for optimal production of lipids, and the addition of acetate to culture media has practical and economic implications for algal biofuel production. We demonstrate the growth of C. reinhardtii on acetate provided by mutant strains of the cyanobacterium Synechococcus sp. PCC7002.

  2. 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

  3. Lauric Acid Production in a Glycogen-Less Strain of Synechococcus sp. PCC 7002

    PubMed Central

    Work, Victoria H.; Melnicki, Matthew R.; Hill, Eric A.; Davies, Fiona K.; Kucek, Leo A.; Beliaev, Alexander S.; Posewitz, Matthew C.

    2015-01-01

    The cyanobacterium Synechococcus sp. Pasteur culture collection 7002 was genetically engineered to synthesize biofuel-compatible medium-chain fatty acids (FAs) during photoautotrophic growth. Expression of a heterologous lauroyl-acyl carrier protein (C12:0-ACP) thioesterase with concurrent deletion of the endogenous putative acyl-ACP synthetase led to secretion of transesterifiable C12:0 FA in CO2-supplemented batch cultures. When grown at steady state over a range of light intensities in a light-emitting diode turbidostat photobioreactor, the C12-secreting mutant exhibited a modest reduction in growth rate and increased O2 evolution relative to the wild-type (WT). Inhibition of (i) glycogen synthesis by deletion of the glgC-encoded ADP-glucose pyrophosphorylase (AGPase) and (ii) protein synthesis by nitrogen deprivation were investigated as potential mechanisms for metabolite redistribution to increase FA synthesis. Deletion of AGPase led to a 10-fold decrease in reducing carbohydrates and secretion of organic acids during nitrogen deprivation consistent with an energy spilling phenotype. When the carbohydrate-deficient background (ΔglgC) was modified for C12 secretion, no increase in C12 was achieved during nutrient replete growth, and no C12 was recovered from any strain upon nitrogen deprivation under the conditions used. At steady state, the growth rate of the ΔglgC strain saturated at a lower light intensity than the WT, but O2 evolution was not compromised and became increasingly decoupled from growth rate with rising irradiance. Photophysiological properties of the ΔglgC strain suggest energy dissipation from photosystem II and reconfiguration of electron flow at the level of the plastoquinone pool. PMID:25964950

  4. Functional and structural characterization of the 2/2 hemoglobin from Synechococcus sp. PCC 7002.

    PubMed

    Scott, Nancy L; Xu, Yu; Shen, Gaozhong; Vuletich, David A; Falzone, Christopher J; Li, Zhongkui; Ludwig, Marcus; Pond, Matthew P; Preimesberger, Matthew R; Bryant, Donald A; Lecomte, Juliette T J

    2010-08-24

    Cyanobacterium Synechococcus sp. PCC 7002 contains a single gene (glbN) coding for GlbN, a protein of the 2/2 hemoglobin lineage. The precise function of GlbN is not known, but comparison to similar 2/2 hemoglobins suggests that reversible dioxygen binding is not its main activity. In this report, the results of in vitro and in vivo experiments probing the role of GlbN are presented. Transcription profiling indicated that glbN is not strongly regulated under any of a large number of growth conditions and that the gene is probably constitutively expressed. High levels of nitrate, used as the sole source of nitrogen, and exposure to nitric oxide were tolerated better by the wild-type strain than a glbN null mutant, whereas overproduction of GlbN in the null mutant background restored the wild-type growth. The cellular contents of reactive oxygen/nitrogen species were elevated in the null mutant under all conditions and were highest under NO challenge or in the presence of high nitrate concentrations. GlbN overproduction attenuated these contents significantly under the latter conditions. The analysis of cell extracts revealed that the heme of GlbN was covalently bound to overproduced GlbN apoprotein in cells grown under microoxic conditions. A peroxidase assay showed that purified GlbN does not possess significant hydrogen peroxidase activity. It was concluded that GlbN protects cells from reactive nitrogen species that could be encountered naturally during growth on nitrate or under denitrifying conditions. The solution structure of covalently modified GlbN was determined and used to rationalize some of its chemical properties.

  5. Metabolic and transcriptomic phenotyping of inorganic carbon acclimation in the Cyanobacterium Synechococcus elongatus PCC 7942.

    PubMed

    Schwarz, Doreen; Nodop, Anke; Hüge, Jan; Purfürst, Stephanie; Forchhammer, Karl; Michel, Klaus-Peter; Bauwe, Hermann; Kopka, Joachim; Hagemann, Martin

    2011-04-01

    The amount of inorganic carbon is one of the main limiting environmental factors for photosynthetic organisms such as cyanobacteria. Using Synechococcus elongatus PCC 7942, we characterized metabolic and transcriptomic changes in cells that had been shifted from high to low CO(2) levels. Metabolic phenotyping indicated an activation of glycolysis, the oxidative pentose phosphate cycle, and glycolate metabolism at lowered CO(2) levels. The metabolic changes coincided with a general reprogramming of gene expression, which included not only increased transcription of inorganic carbon transporter genes but also genes for enzymes involved in glycolytic and photorespiratory metabolism. In contrast, the mRNA content for genes from nitrogen assimilatory pathways decreased. These observations indicated that cyanobacteria control the homeostasis of the carbon-nitrogen ratio. Therefore, results obtained from the wild type were compared with the MP2 mutant of Synechococcus 7942, which is defective for the carbon-nitrogen ratio-regulating PII protein. Metabolites and genes linked to nitrogen assimilation were differentially regulated, whereas the changes in metabolite concentrations and gene expression for processes related to central carbon metabolism were mostly similar in mutant and wild-type cells after shifts to low-CO(2) conditions. The PII signaling appears to down-regulate the nitrogen metabolism at lowered CO(2), whereas the specific shortage of inorganic carbon is recognized by different mechanisms.

  6. Metabolic and Transcriptomic Phenotyping of Inorganic Carbon Acclimation in the Cyanobacterium Synechococcus elongatus PCC 79421[W

    PubMed Central

    Schwarz, Doreen; Nodop, Anke; Hüge, Jan; Purfürst, Stephanie; Forchhammer, Karl; Michel, Klaus-Peter; Bauwe, Hermann; Kopka, Joachim; Hagemann, Martin

    2011-01-01

    The amount of inorganic carbon is one of the main limiting environmental factors for photosynthetic organisms such as cyanobacteria. Using Synechococcus elongatus PCC 7942, we characterized metabolic and transcriptomic changes in cells that had been shifted from high to low CO2 levels. Metabolic phenotyping indicated an activation of glycolysis, the oxidative pentose phosphate cycle, and glycolate metabolism at lowered CO2 levels. The metabolic changes coincided with a general reprogramming of gene expression, which included not only increased transcription of inorganic carbon transporter genes but also genes for enzymes involved in glycolytic and photorespiratory metabolism. In contrast, the mRNA content for genes from nitrogen assimilatory pathways decreased. These observations indicated that cyanobacteria control the homeostasis of the carbon-nitrogen ratio. Therefore, results obtained from the wild type were compared with the MP2 mutant of Synechococcus 7942, which is defective for the carbon-nitrogen ratio-regulating PII protein. Metabolites and genes linked to nitrogen assimilation were differentially regulated, whereas the changes in metabolite concentrations and gene expression for processes related to central carbon metabolism were mostly similar in mutant and wild-type cells after shifts to low-CO2 conditions. The PII signaling appears to down-regulate the nitrogen metabolism at lowered CO2, whereas the specific shortage of inorganic carbon is recognized by different mechanisms. PMID:21282404

  7. Construction of a new gene integration platform system for the Synechococcus sp. PCC7942

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Wu, Qiao-Juan; Lou, Shi-Lin

    1998-03-01

    According to the known sequence of iron stress-induced gene ( isiAB operon), we cloned its 1.5 kb fragment by PCR, and used this fragment as integration homologous fragment. After several steps of subcloning donor DNA into the isiAB fragment, a donor plasmid pZL which could be integrated into the chromosomal DNA of Synechococcus sp. PCC7942 was constructed. In order to express the heterologous gene at a high level through the integration platform system, we constructed the donor DNA by the following steps. We cloned the strong promoter (240 bp) of heat shock gene groESL operon from Synechococcus sp. PCC7942 by PCR. Then subcloned the multiple cloning sites (MCS), rbcS polyA into the downstream of the groESL promoter. The kanamycin resistance gene, as the marker gene, was also subcloned into the donor DNA. Thus, in the donor plasmid pZL, the integration homologous fragment and several expression elements, such as groESL promoter, MCS, rbcS polyA terminator and kanamycin resistance gene, were all included. After naturally transformed and introduced the donor plasmid pZL into Synechococcus sp. PCC7942, as in the pZL, the donor DNA sequence is flanked by two DNA fragments (0.4 kb and 0.7 kb) homologous to the isiAB fragment of Synechococcus sp. PCC7942, the homologous DNA can recombine with the chromosomal DNA. After screening by kanamycin, the transformants which integrated the heterologous DNA were selected. The efficiency of transformation is about 1×10-6. By southern blot analysis, it was confirmed that the donor DNA had been integrated into the chromosomal DNA of Synechococcus sp. PCC7942, located on the site of the isiAB gene, and can be replicated with the chromosomal DNA.

  8. Siderophore mediated uranium sequestration by marine cyanobacterium Synechococcus elongatus BDU 130911.

    PubMed

    Rashmi, Vijayaraghavan; Shylajanaciyar, Mohandass; Rajalakshmi, Ramamoorthy; D'Souza, Stanley F; Prabaharan, Dharmar; Uma, Lakshmanan

    2013-02-01

    Four different marine cyanobacterial morphotypes were tested for their efficacy to produce siderophores in Fe minus [Fe(-)], Fe minus Uranium dosed [Fe(-)U(+)], and Fe dosed Uranium dosed [Fe(-)U(+)] media. Of the four organisms tested, Synechococcus elongatus BDU 130911 produced the highest amount of siderophore of 58μgmg(-1) dryweight. The results clearly indicate that uranium induces siderophore production in marine cyanobacteria even in the presence of iron [Fe(-)U(+)] condition. The type of siderophore revealed by FeCl(3), Tetrazolium and Atkin's tests is a hydroxamate; and thin layer chromatogram also authenticates our finding. Uranium siderophore complexation was confirmed through modified Chrome Azurol S (CAS) assay as well as based on residual uranium presence. In silico docking studies further validate siderophore complexation with uranium.

  9. Self-replicating shuttle vectors based on pANS, a small endogenous plasmid of the unicellular cyanobacterium Synechococcus elongatus PCC 7942.

    PubMed

    Chen, You; Taton, Arnaud; Go, Michaela; London, Ross E; Pieper, Lindsey M; Golden, Susan S; Golden, James W

    2016-12-01

    To facilitate development of synthetic biology tools for genetic engineering of cyanobacterial strains, we constructed pANS-derived self-replicating shuttle vectors that are based on the minimal replication element of the Synechococcus elongatus strain PCC 7942 plasmid pANS. To remove the possibility of homologous recombination events between the shuttle plasmids and the native pANS plasmid, the endogenous pANS was cured through plasmid incompatibility-mediated spontaneous loss. A heterologous toxin-antitoxin cassette was incorporated into the shuttle vectors for stable plasmid maintenance in the absence of antibiotic selection. The pANS-based shuttle vectors were shown to be able to carry a large 20 kb DNA fragment containing a gene cluster for biosynthesis of the omega-3 fatty acid eicosapentaenoic acid. Based on quantitative PCR analysis, there are about 10 copies of pANS and 3 copies of the large native plasmid pANL per chromosome in S. elongatus. Fluorescence levels of GFP reporter genes in a pANS-based vector were about 2.5-fold higher than when in pANL or integrated into the chromosome. In addition to its native host, pANS-based shuttle vectors were also found to replicate stably in the filamentous cyanobacterium Anabaena sp. strain PCC 7120. There were about 27 copies of a pANS-based shuttle vector, 9 copies of a pDU1-based shuttle vector and 3 copies of an RSF1010-based shuttle vector per genome when these three plasmids co-existed in Anabaena cells. The endogenous pANS from our S. elongatus laboratory strain was cloned in Escherichia coli, re-sequenced and re-annotated to update previously published sequencing data.

  10. Modulation of medium-chain fatty acid synthesis in Synechococcus sp. PCC 7002 by replacing FabH with a Chaetoceros Ketoacyl-ACP synthase

    DOE PAGES

    Gu, Huiya; Jinkerson, Robert E.; Davies, Fiona K.; ...

    2016-05-26

    The isolation or engineering of algal cells synthesizing high levels of medium-chain fatty acids (MCFAs) is attractive to mitigate the high clouding point of longer chain fatty acids in algal based biodiesel. To develop a more informed understanding of MCFA synthesis in photosynthetic microorganisms, we isolated several algae from Great Salt Lake and screened this collection for MCFA accumulation to identify strains naturally accumulating high levels of MCFA. A diatom, Chaetoceros sp. GSL56, accumulated particularly high levels of C14 (up to 40%), with the majority of C14 fatty acids allocated in triacylglycerols. Using whole cell transcriptome sequencing and de novomore » assembly, putative genes encoding fatty acid synthesis enzymes were identified. Enzymes from this Chaetoceros sp. were expressed in the cyanobacterium Synechococcus sp. PCC 7002 to validate gene function and to determine whether eukaryotic enzymes putatively lacking bacterial evolutionary control mechanisms could be used to improve MCFA production in this promising production strain. Replacement of the Synechococcus 7002 native FabH with a Chaetoceros ketoacyl-ACP synthase Ill increased MCFA synthesis up to fivefold. In conclusion, the level of increase is dependent on promoter strength and culturing conditions.« less

  11. Modulation of Medium-Chain Fatty Acid Synthesis in Synechococcus sp. PCC 7002 by Replacing FabH with a Chaetoceros Ketoacyl-ACP Synthase

    PubMed Central

    Gu, Huiya; Jinkerson, Robert E.; Davies, Fiona K.; Sisson, Lyle A.; Schneider, Philip E.; Posewitz, Matthew C.

    2016-01-01

    The isolation or engineering of algal cells synthesizing high levels of medium-chain fatty acids (MCFAs) is attractive to mitigate the high clouding point of longer chain fatty acids in algal based biodiesel. To develop a more informed understanding of MCFA synthesis in photosynthetic microorganisms, we isolated several algae from Great Salt Lake and screened this collection for MCFA accumulation to identify strains naturally accumulating high levels of MCFA. A diatom, Chaetoceros sp. GSL56, accumulated particularly high levels of C14 (up to 40%), with the majority of C14 fatty acids allocated in triacylglycerols. Using whole cell transcriptome sequencing and de novo assembly, putative genes encoding fatty acid synthesis enzymes were identified. Enzymes from this Chaetoceros sp. were expressed in the cyanobacterium Synechococcus sp. PCC 7002 to validate gene function and to determine whether eukaryotic enzymes putatively lacking bacterial evolutionary control mechanisms could be used to improve MCFA production in this promising production strain. Replacement of the Synechococcus 7002 native FabH with a Chaetoceros ketoacyl-ACP synthase III increased MCFA synthesis up to fivefold. The level of increase is dependent on promoter strength and culturing conditions. PMID:27303412

  12. 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

  13. Supercritical CO2 extraction of beta-carotene from a marine strain of the cyanobacterium Synechococcus species.

    PubMed

    Montero, Olimpio; Macías-Sánchez, Maria Dolores; Lama, Carmen M; Lubián, Luis M; Mantell, Casimiro; Rodríguez, Miguel; de la Ossa, Enrique M

    2005-12-14

    Dynamic extraction of carotenoids from a marine strain of Synechococcus sp. (Cyanophyceae) with supercritical CO2 (SC-CO2) was investigated with regard to operation pressure and temperature effects on extraction efficiency. Extraction yield (milligrams of pigment per gram of dry weight) for SC-CO2) was compared with the extraction yield for dimethylformamide (DMF). Carotenoids extracted with SC-CO2 were beta-carotene (Ct), zeaxanthin (Z), beta-cryptoxanthin (Cr), and equinenone; chlorophyll a was poorly extracted, whereas myxoxanthophyll, another major carotenoid, was not extracted under any experimental condition. The highest relative yield, which is defined here as y(r) = [(mg of pigment(SC-CO2)/mg of pigment(DMF))] x 100, was 76.1 +/- 8.6% for Ct, but it rose to 87.0 +/- 3.4% when 15% ethanol was used as cosolvent. The pressure effect on y(r) was found to be significant (p < 0.05) for both Cr and Z, along with total carotenoids, whereas the effect of square T (TT) was significant for only Ct. From empirical correlations, pairwise pressure (bar) and temperature (degrees C), respectively, for optimal extraction were determined to be (358, 50) for Ct, (454, 59) for Cr, and (500, 60) for Z. Cell disruption by sonication or detergent treatment of the biomass did not improve the extraction efficiency. Matrix structure together with material state could explain the low carotenoid extraction yield obtained with SC-CO2 as compared to DMF in Synechococcus sp. However, the process can be applied to selective extraction of different carotenoids.

  14. Identification of Xenologs and Their Characteristic Low Expression Levels in the Cyanobacterium Synechococcus elongatus.

    PubMed

    Álvarez-Canales, Gilberto; Arellano-Álvarez, Guadalupe; González-Domenech, Carmen M; de la Cruz, Fernando; Moya, Andrés; Delaye, Luis

    2015-06-01

    Horizontal gene transfer (HGT) is a central process in prokaryotic evolution. Once a gene is introduced into a genome by HGT, its contribution to the fitness of the recipient cell depends in part on its expression level. Here we show that in Synechococcus elongatus PCC 7942, xenologs derived from non-cyanobacterial sources exhibited lower expression levels than native genes in the genome. In accord with our observation, xenolog codon adaptation indexes also displayed relatively low expression values. These results are in agreement with previous reports that suggested the relative neutrality of most xenologs. However, we also demonstrated that some of the xenologs detected participated in cellular functions, including iron starvation acclimation and nitrate reduction, which corroborate the role of HGT in bacterial adaptation. For example, the expression levels of some of the xenologs detected are known to increase under iron-limiting conditions. We interpreted the overall pattern as an indication that there is a selection pressure against high expression levels of xenologs. However, when a xenolog protein product confers a selective advantage, natural selection can further modulate its expression level to meet the requirements of the recipient cell. In addition, we show that ORFans did not exhibit significantly lower expression levels than native genes in the genome, which suggested an origin other than xenology.

  15. Small secreted proteins enable biofilm development in the cyanobacterium Synechococcus elongatus

    PubMed Central

    Parnasa, Rami; Nagar, Elad; Sendersky, Eleonora; Reich, Ziv; Simkovsky, Ryan; Golden, Susan; Schwarz, Rakefet

    2016-01-01

    Small proteins characterized by a double-glycine (GG) secretion motif, typical of secreted bacterial antibiotics, are encoded by the genomes of diverse cyanobacteria, but their functions have not been investigated to date. Using a biofilm-forming mutant of Synechococcus elongatus PCC 7942 and a mutational approach, we demonstrate the involvement of four small secreted proteins and their GG-secretion motifs in biofilm development. These proteins are denoted EbfG1-4 (enable biofilm formation with a GG-motif). Furthermore, the conserved cysteine of the peptidase domain of the Synpcc7942_1133 gene product (dubbed PteB for peptidase transporter essential for biofilm) is crucial for biofilm development and is required for efficient secretion of the GG-motif containing proteins. Transcriptional profiling of ebfG1-4 indicated elevated transcript levels in the biofilm-forming mutant compared to wild type (WT). However, these transcripts decreased, acutely but transiently, when the mutant was cultured in extracellular fluids from a WT culture, and biofilm formation was inhibited. We propose that WT cells secrete inhibitor(s) that suppress transcription of ebfG1-4, whereas secretion of the inhibitor(s) is impaired in the biofilm-forming mutant, leading to synthesis and secretion of EbfG1-4 and supporting the formation of biofilms. PMID:27558743

  16. Metabolic engineering for isopropanol production by an engineered cyanobacterium, Synechococcus elongatus PCC 7942, under photosynthetic conditions.

    PubMed

    Hirokawa, Yasutaka; Dempo, Yudai; Fukusaki, Eiichiro; Hanai, Taizo

    2017-01-01

    Cyanobacteria engineered for production of biofuels and biochemicals from carbon dioxide represent a promising area of research in relation to a sustainable economy. Previously, we have succeeded in producing isopropanol from cellular acetyl-CoA by means of Synechococcus elongatus PCC 7942 into which a synthetic metabolic pathway was introduced. The isopropanol production by this synthetic metabolic pathway requires acetate; therefore, the cells grown under photosynthetic conditions have to be transferred to a dark and anaerobic conditions to produce acetate. In this study, we achieved acetate production under photosynthetic conditions by S. elongatus PCC 7942 into which we introduced the pta gene encoding phosphate acetyltransferase from Escherichia coli. The metabolic modification (via pta introduction) of the isopropanol-producing strain enabled production of isopropanol under photosynthetic conditions. During 14 days of production, the titer of isopropanol reached 0.55 mM (33.1 mg/l) with an intermediate product, acetone, at 0.21 mM (12.2 mg/l). Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  17. Disturbance of cell-size determination by forced overproduction of sulfoquinovosyl diacylglycerol in the cyanobacterium Synechococcus elongatus PCC 7942.

    PubMed

    Sato, Norihiro; Ebiya, Yuki; Kobayashi, Ryutaro; Nishiyama, Yoshitaka; Tsuzuki, Mikio

    2017-06-03

    Sulfoquinovosyl diacylglycerol (SQDG) is present in the membranes of cyanobacteria or their descendants, plastids at species-dependent levels. We investigated the physiological significance of the intrinsic SQDG content in the cyanobacterium Synechococcus elongatus PCC 7942, with the use of its mutant, in which the genes for SQDG synthesis, sqdB and sqdX, were overexpressed. The mutant showed a 1.3-fold higher content of SQDG (23.6 mol% relative to total cellular lipids, cf., 17.1 mol% in the control strain) with much less remarkable effects on the other lipid classes. Simultaneously observed were 1.6- to 1.9-fold enhanced mRNA levels for the genes responsible for the synthesis of the lipids other than SQDG, as if to compensate for the SQDG overproduction. Meanwhile, the mutant showed no injury to cell growth, however, cell length was increased (6.1 ± 2.3, cf., 3.8 ± 0.8 μm in the control strain). Accordingly with this, a wide range of genes responsible for cell division were 1.6-2.4-fold more highly expressed in the mutant. These results suggested that a regulatory mechanism for lipid homeostasis functions in the mutant, and that SQDG has to be kept from surpassing the intrinsic content in S. elongatus for repression of the abnormal expression of cell division-related genes and, inevitably, for normal cell division. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Overexpression of halophilic serine hydroxymethyltransferase in fresh water cyanobacterium Synechococcus elongatus PCC7942 results in increased enzyme activities of serine biosynthetic pathways and enhanced salinity tolerance.

    PubMed

    Waditee-Sirisattha, Rungaroon; Kageyama, Hakuto; Tanaka, Yoshito; Fukaya, Minoru; Takabe, Teruhiro

    2017-01-01

    Serine hydroxymethyltransferase (SHMT) catalyzes the conversion of serine to glycine and provides activated one-carbon units required for synthesis of nucleic acids, proteins and numerous biological compounds. SHMT is involved in photorespiratory pathway of oxygenic photosynthetic organisms. Accumulating evidence revealed that SHMT plays vital role for abiotic stresses such as low CO2 and high salinity in plants, but its role in cyanobacteria remains to be clarified. In this study, we examined to overexpress the SHMT from halotolerant cyanobacterium Aphanothece halophytica in freshwater cyanobacterium, Synechococcus elongatus PCC7942. The transformed cells did not show an obvious phenotype under non-stress condition, but exhibited more tolerance to salinity than the control cells harboring vector only under high salinity. Elevated levels of enzymes in phosphorylated serine biosynthetic pathway and photorespiration pathway were observed in the transformed cells. Glycine level was also increased in the transformed cells. Physiological roles of SHMT for salt tolerance were discussed.

  19. Purification and antioxidant activity of phycocyanin from Synechococcus sp. R42DM isolated from industrially polluted site.

    PubMed

    Sonani, Ravi R; Patel, Stuti; Bhastana, Bela; Jakharia, Kinnari; Chaubey, Mukesh G; Singh, Niraj K; Madamwar, Datta

    2017-08-31

    The cyanobacterium Synechococcus sp. R42DM, isolated from an industrially polluted site Vatva, Gujarat, India was recognized to produce phycocyanin (PC) as major phycobiliprotein. In present study, the combinatorial approach of chemical and physical methods i.e. Triton-X 100 treatment and ultra-sonication was designed for extraction of PC. From cell extract, the intact and functional-PC was purified up to purity 4.03 by ammonium sulphate fractionation and ion-exchange chromatography. The PC displayed considerable in vitro antioxidant and radical-scavenging activity. This PC was further noticed to scavenge intracellular-ROS and to increase tolerance against thermal and oxidative stress in Caenorhabditis elegans. Moreover, the PC was noticed to improve the physiological behaviour and longevity of C. elegans. In addition, the PC showed remarkable stability under physico-chemical stressors, which is desirable for their use in biomedical applications. In conclusion, present paper added up evidence in support of the prospective use of PC as an antioxidant nutraceutical. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Factors Altering Pyruvate Excretion in a Glycogen Storage Mutant of the Cyanobacterium, Synechococcus PCC7942

    PubMed Central

    Benson, Phoebe J.; Purcell-Meyerink, Diane; Hocart, Charles H.; Truong, Thy T.; James, Gabriel O.; Rourke, Loraine; Djordjevic, Michael A.; Blackburn, Susan I.; Price, G. D.

    2016-01-01

    Interest in the production of carbon commodities from photosynthetically fixed CO2 has focused attention on cyanobacteria as a target for metabolic engineering and pathway investigation. We investigated the redirection of carbon flux in the model cyanobacterial species, Synechococcus elongatus PCC 7942, under nitrogen deprivation, for optimized production of the industrially desirable compound, pyruvate. Under nitrogen limited conditions, excess carbon is naturally stored as the multi-branched polysaccharide, glycogen, but a block in glycogen synthesis, via knockout mutation in the gene encoding ADP-glucose pyrophosphorylase (glgC), results in the accumulation of the organic acids, pyruvate and 2-oxoglutarate, as overflow excretions into the extracellular media. The ΔglgC strain, under 48 h of N-deprivation was shown to excrete pyruvate for the first time in this strain. Additionally, by increasing culture pH, to pH 10, it was possible to substantially elevate excretion of pyruvate, suggesting the involvement of an unknown substrate/proton symporter for export. The ΔglgC mutant was also engineered to express foreign transporters for glucose and sucrose, and then grown photomixotrophically with exogenous organic carbon supply, as added 5 mM glucose or sucrose during N- deprivation. Under these conditions we observed a fourfold increase in extracellular pyruvate excretion when glucose was added, and a smaller increase with added sucrose. Although the magnitude of pyruvate excretion did not correlate with the capacity of the ΔglgC strain for bicarbonate-dependent photosynthetic O2 evolution, or with light intensity, there was, however, a positive correlation observed between the density of the starter culture prior to N-deprivation and the final extracellular pyruvate concentration. The factors that contribute to enhancement of pyruvate excretion are discussed, as well as consideration of whether the source of carbon for pyruvate excretion might be derived from

  1. Active Transport of CO2 by the Cyanobacterium Synechococcus UTEX 625 1

    PubMed Central

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

    1988-01-01

    Mass spectrometry has been used to confirm the presence of an active transport system for CO2 in Synechococcus UTEX 625. Cells were incubated at pH 8.0 in 100 micromolar KHCO3 in the absence of Na+ (to prevent HCO3− transport). Upon illumination the cells rapidly removed almost all the free CO2 from the medium. Addition of carbonic anhydrase revealed that the CO2 depletion resulted from a selective uptake of CO2, rather than a total uptake of all inorganic carbon species. CO2 transport stopped rapidly (<3 seconds) when the light was turned off. Iodoacetamide (3.3 millimolar) completely inhibited CO2 fixation but had little effect on CO2 transport. In iodoacetamide poisoned cells, transport of CO2 occurred against a concentration gradient of about 18,000 to 1. Transport of CO2 was completely inhibited by 10 micromolar diethylstilbestrol, a membrane-bound ATPase inhibitor. Studies with DCMU and PSI light indicated that CO2 transport was driven by ATP produced by cyclic or pseudocyclic photophosphorylation. Low concentrations of Na+ (<100 microequivalents per liter), but not of K+, stimulated CO2 transport as much as 2.4-fold. Unlike Na+-dependent HCO3− transport, the transport of CO2 was not inhibited by high concentrations (30 milliequivalents per liter) of Li+. During illumination, the CO2 concentration in the medium remained far below its equilibrium value for periods up to 15 minutes. This could only happen if CO2 transport was continuously occurring at a rapid rate, since the continuing dehydration of HCO3− to CO2 would rapidly raise the CO2 concentration to its equilibrium value if transport ceased. Measurement of the rate of dissolved inorganic carbon accumulation under these conditions indicated that at least part of the continuing CO2 transport was balanced by HCO3− efflux. PMID:16665969

  2. High Affinity Transport of CO2 in the Cyanobacterium Synechococcus UTEX 625 1

    PubMed Central

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

    1991-01-01

    The active transport of CO2 in Synechococcus UTEX 625 was measured by mass spectrometry under conditions that preclude HCO3− transport. The substrate concentration required to give one half the maximum rate for whole cell CO2 transport was determined to be 0.4 ± 0.2 micromolar (mean ± standard deviation; n = 7) with a range between 0.2 and 0.66 micromolar. The maximum rates of CO2 transport ranged between 400 and 735 micromoles per milligram of chlorophyll per hour with an average rate of 522 for seven experiments. This rate of transport was about three times greater than the dissolved inorganic carbon saturated rate of photosynthetic O2 evolution observed under these conditions. The initial rate of chlorophyll a fluorescence quenching was highly correlated with the initial rate of CO2 transport (correlation coefficient = 0.98) and could be used as an indirect method to detect CO2 transport and calculate the substrate concentration required to give one half the maximum rate of transport. Little, if any, inhibition of CO2 transport was caused by HCO3− or by Na+-dependent HCO3− transport. However, 12CO2 readily interfered with 13CO2 transport. CO2 transport and Na+-dependent HCO3− transport are separate, independent processes and the high affinity CO2 transporter is not only responsible for the initial transport of CO2 into the cell but also for scavenging any CO2 that may leak from the cell during ongoing photosynthesis. PMID:16668535

  3. Integrated in silico analyses of regulatory and metabolic networks of Synechococcus sp. PCC 7002 reveal relationships between gene centrality and essentiality

    SciTech Connect

    Song, Hyun-Seob; McClure, Ryan S.; Bernstein, Hans C.; Overall, Christopher C.; Hill, Eric A.; Beliaev, Alex S.

    2015-03-27

    Cyanobacteria dynamically relay environmental inputs to intracellular adaptations through a coordinated adjustment of photosynthetic efficiency and carbon processing rates. The output of such adaptations is reflected through changes in transcriptional patterns and metabolic flux distributions that ultimately define growth strategy. To address interrelationships between metabolism and regulation, we performed integrative analyses of metabolic and gene co-expression networks in a model cyanobacterium, Synechococcus sp. PCC 7002. Centrality analyses using the gene co-expression network identified a set of key genes, which were defined here as ‘topologically important.’ Parallel in silico gene knock-out simulations, using the genome-scale metabolic network, classified what we termed as ‘functionally important’ genes, deletion of which affected growth or metabolism. A strong positive correlation was observed between topologically and functionally important genes. Functionally important genes exhibited variable levels of topological centrality; however, the majority of topologically central genes were found to be functionally essential for growth. Subsequent functional enrichment analysis revealed that both functionally and topologically important genes in Synechococcus sp. PCC 7002 are predominantly associated with translation and energy metabolism, two cellular processes critical for growth. This research demonstrates how synergistic network-level analyses can be used for reconciliation of metabolic and gene expression data to uncover fundamental biological principles.

  4. Integrated in silico analyses of regulatory and metabolic networks of Synechococcus sp. PCC 7002 reveal relationships between gene centrality and essentiality

    DOE PAGES

    Song, Hyun-Seob; McClure, Ryan S.; Bernstein, Hans C.; ...

    2015-03-27

    Cyanobacteria dynamically relay environmental inputs to intracellular adaptations through a coordinated adjustment of photosynthetic efficiency and carbon processing rates. The output of such adaptations is reflected through changes in transcriptional patterns and metabolic flux distributions that ultimately define growth strategy. To address interrelationships between metabolism and regulation, we performed integrative analyses of metabolic and gene co-expression networks in a model cyanobacterium, Synechococcus sp. PCC 7002. Centrality analyses using the gene co-expression network identified a set of key genes, which were defined here as ‘topologically important.’ Parallel in silico gene knock-out simulations, using the genome-scale metabolic network, classified what we termedmore » as ‘functionally important’ genes, deletion of which affected growth or metabolism. A strong positive correlation was observed between topologically and functionally important genes. Functionally important genes exhibited variable levels of topological centrality; however, the majority of topologically central genes were found to be functionally essential for growth. Subsequent functional enrichment analysis revealed that both functionally and topologically important genes in Synechococcus sp. PCC 7002 are predominantly associated with translation and energy metabolism, two cellular processes critical for growth. This research demonstrates how synergistic network-level analyses can be used for reconciliation of metabolic and gene expression data to uncover fundamental biological principles.« less

  5. Integrated in silico Analyses of Regulatory and Metabolic Networks of Synechococcus sp. PCC 7002 Reveal Relationships between Gene Centrality and Essentiality

    PubMed Central

    Song, Hyun-Seob; McClure, Ryan S.; Bernstein, Hans C.; Overall, Christopher C.; Hill, Eric A.; Beliaev, Alexander S.

    2015-01-01

    Cyanobacteria dynamically relay environmental inputs to intracellular adaptations through a coordinated adjustment of photosynthetic efficiency and carbon processing rates. The output of such adaptations is reflected through changes in transcriptional patterns and metabolic flux distributions that ultimately define growth strategy. To address interrelationships between metabolism and regulation, we performed integrative analyses of metabolic and gene co-expression networks in a model cyanobacterium, Synechococcus sp. PCC 7002. Centrality analyses using the gene co-expression network identified a set of key genes, which were defined here as “topologically important.” Parallel in silico gene knock-out simulations, using the genome-scale metabolic network, classified what we termed as “functionally important” genes, deletion of which affected growth or metabolism. A strong positive correlation was observed between topologically and functionally important genes. Functionally important genes exhibited variable levels of topological centrality; however, the majority of topologically central genes were found to be functionally essential for growth. Subsequent functional enrichment analysis revealed that both functionally and topologically important genes in Synechococcus sp. PCC 7002 are predominantly associated with translation and energy metabolism, two cellular processes critical for growth. This research demonstrates how synergistic network-level analyses can be used for reconciliation of metabolic and gene expression data to uncover fundamental biological principles. PMID:25826650

  6. Physiological Studies of Glutamine Synthetases I and III from Synechococcus sp. WH7803 Reveal Differential Regulation

    PubMed Central

    Domínguez-Martín, María Agustina; Díez, Jesús; García-Fernández, José M.

    2016-01-01

    The marine picocyanobacterium Synechococcus sp. WH7803 possesses two glutamine synthetases (GSs; EC 6.3.1.2), GSI encoded by glnA and GSIII encoded by glnN. This is the first work addressing the physiological regulation of both enzymes in a marine cyanobacterial strain. The increase of GS activity upon nitrogen starvation was similar to that found in other model cyanobacteria. However, an unusual response was found when cells were grown under darkness: the GS activity was unaffected, reflecting adaptation to the environment where they thrive. On the other hand, we found that GSIII did not respond to nitrogen availability, in sharp contrast with the results observed for this enzyme in other cyanobacteria thus far studied. These features suggest that GS activities in Synechococcus sp. WH7803 represent an intermediate step in the evolution of cyanobacteria, in a process of regulatory streamlining where GSI lost the regulation by light, while GSIII lost its responsiveness to nitrogen. This is in good agreement with the phylogeny of Synechococcus sp. WH7803 in the context of the marine cyanobacterial radiation. PMID:27446010

  7. Changes in Membrane Lipid Composition during Saline Growth of the Fresh Water Cyanobacterium Synechococcus 6311 1

    PubMed Central

    Huflejt, Margaret E.; Tremolieres, Antoine; Pineau, Bernard; Lang, Johanna K.; Hatheway, John; Packer, Lester

    1990-01-01

    Growth of Synechococcus 6311 in the presence of 0.5 molar NaCl is accompanied by significant changes in membrane lipid composition. Upon transfer of the cells from a `low salt' (0.015 molar NaCl) to `high salt' (0.5 molar NaCl) growth medium at different stages of growth, a rapid decrease in palmitoleic acid (C16:1Δ9) content was accompanied by a concomitant increase in the amount of the two C18:1 acids (C18:1Δ9, C18:1Δ11), with the higher increase in oleic acid C18:1Δ9 content. These changes began to occur within the first hour after the sudden elevation of NaCl and progressed for about 72 hours. The percentage of palmitic acid (C16:0) and stearic acid (C18:0) remained almost unchanged in the same conditions. High salt-dependent changes within ratios of polar lipid classes also occurred within the first 72 hours of growth. The amount of monogalactosyl diacylglycerol (bilayer-destabilizing lipid) decreased and that of the digalactosyl diacylglycerol (bilayer-stabilizing lipid) increased. Consequently, in the three day old cells, the ratio of monogalactosyl diacylglycerol to digalactosyl diacylglycerol in the membranes of high salt-grown cells was about half of that in the membranes of low salt-grown cells. The total content of anionic lipids (phosphatidylglycerol and sulfoquinovosyl diacylglycerol) was always higher in the isolated membranes and the whole cells from high salt-grown cultures compared to that in the cells and membranes from low salt-grown cultures. All the observed rearrangements in the lipid environment occurred in both thylakoid and cytoplasmic membranes. Similar lipid composition changes, however, to a much lesser extent, were also observed in the aging, low salt-grown cultures. The observed changes in membrane fatty acids and lipids composition correlate with the alterations in electron and ion transport activities, and it is concluded that the rearrangement of the membrane lipid environment is an essential part of the process by which cells

  8. Changes in membrane lipid composition during saline growth of the fresh water cyanobacterium Synechococcus 6311

    NASA Technical Reports Server (NTRS)

    Huflejt, M. E.; Tremolieres, A.; Pineau, B.; Lang, J. K.; Hatheway, J.; Packer, L.

    1990-01-01

    Growth of Synechococcus 6311 in the presence of 0.5 molar NaCl is accompanied by significant changes in membrane lipid composition. Upon transfer of the cells from a low salt' (0.015 molar NaCl) to high salt' (0.5 molar NaCl) growth medium at different stages of growth, a rapid decrease in palmitoleic acid (C16:1 delta 9) content was accompanied by a concomitant increase in the amount of the two C18:1 acids (C18:1 delta 9, C18:1 delta 11), with the higher increase in oleic acid C18:1 delta 9 content. These changes began to occur within the first hour after the sudden elevation of NaCl and progressed for about 72 hours. The percentage of palmitic acid (C16:0) and stearic acid (C18:0) remained almost unchanged in the same conditions. High salt-dependent changes within ratios of polar lipid classes also occurred within the first 72 hours of growth. The amount of monogalactosyl diacylglycerol (bilayer-destabilizing lipid) decreased and that of the digalactosyl diacylglycerol (bilayer-stabilizing lipid) increased. Consequently, in the three day old cells, the ratio of monogalactosyl diacylglycerol to digalactosyl diacylglycerol in the membranes of high salt-grown cells was about half of that in the membranes of low salt-grown cells. The total content of anionic lipids (phosphatidylglycerol and sulfoquinovosyl diacylglycerol) was always higher in the isolated membranes and the whole cells from high salt-grown cultures compared to that in the cells and membranes from low salt-grown cultures. All the observed rearrangements in the lipid environment occurred in both thylakoid and cytoplasmic membranes. Similar lipid composition changes, however, to a much lesser extent, were also observed in the aging, low salt-grown cultures. The observed changes in membrane fatty acids and lipids composition correlate with the alterations in electron and ion transport activities, and it is concluded that the rearrangement of the membrane lipid environment is an essential part of the

  9. Spectroscopic studies of Synechococcus sp PCC 7002 phycobilisome core mutants

    SciTech Connect

    Gindt, Y.M.

    1993-04-01

    The role of the L{sub cm} (I), {beta}{sup 18} (II), and {alpha}{sup AP-B} (III) chromoproteins in the phycobilisome (PBS) core was investigated using genetically engineered strains of Synechococcus missing different polypeptides. Intact cells, isolated PBS, and subcore preparations for each mutant were studied to determine the effect of that mutation on energy transfer within the PBS core and to the reaction centers. Three mutants lacked the II and/or III polypeptides, while the I chromophore was altered in others. A lower energy absorbing chromophore, A{sub max} = 695 nm, was substituted for the I chromophore. The deletion of the II and III subunits had no discernible effect on energy transfer from the PBS to PSII. In cells and isolated PBS, the altered I chromophore acts to quench the PBS complex and to redirect the energy which would be transferred to PSII. In the PBS and subcore preparations, deletion of the III subunit did not alter energy transfer within the core. The deletion of the II subunit from the PBS caused a small decrease in the excited state lifetimes of the final emitters indicating more disorder within the core. The I chromophore was found to absorb at 670nm and to emit at 683nm within the intact PBS. The II chromophore emits at 679nm while the III chromophore emits at 682nm. A strong interaction exists between the I chromophore and the II subunit. Upon deletion of the II subunit from the PBS core, the I chromophore emits at a higher energy. The II subunit could act to stabilize the I chromophore-binding pocket, or exciton coupling could be occurring between the two. The role of the III chromophore is still unclear at this time. The III chromophore does contribute to the RT emission of the isolated PBS, but it transfers energy to I at 77 K. One can conclude that the III subunit is adjacent to the trimer containing the I polypeptide.

  10. Spectroscopic studies of Synechococcus sp PCC 7002 phycobilisome core mutants

    SciTech Connect

    Gindt, Y.M.

    1993-04-01

    The role of the L[sub cm] (I), [beta][sup 18] (II), and [alpha][sup AP-B] (III) chromoproteins in the phycobilisome (PBS) core was investigated using genetically engineered strains of Synechococcus missing different polypeptides. Intact cells, isolated PBS, and subcore preparations for each mutant were studied to determine the effect of that mutation on energy transfer within the PBS core and to the reaction centers. Three mutants lacked the II and/or III polypeptides, while the I chromophore was altered in others. A lower energy absorbing chromophore, A[sub max] = 695 nm, was substituted for the I chromophore. The deletion of the II and III subunits had no discernible effect on energy transfer from the PBS to PSII. In cells and isolated PBS, the altered I chromophore acts to quench the PBS complex and to redirect the energy which would be transferred to PSII. In the PBS and subcore preparations, deletion of the III subunit did not alter energy transfer within the core. The deletion of the II subunit from the PBS caused a small decrease in the excited state lifetimes of the final emitters indicating more disorder within the core. The I chromophore was found to absorb at 670nm and to emit at 683nm within the intact PBS. The II chromophore emits at 679nm while the III chromophore emits at 682nm. A strong interaction exists between the I chromophore and the II subunit. Upon deletion of the II subunit from the PBS core, the I chromophore emits at a higher energy. The II subunit could act to stabilize the I chromophore-binding pocket, or exciton coupling could be occurring between the two. The role of the III chromophore is still unclear at this time. The III chromophore does contribute to the RT emission of the isolated PBS, but it transfers energy to I at 77 K. One can conclude that the III subunit is adjacent to the trimer containing the I polypeptide.

  11. 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.

  12. Characterization of corrinoid compounds from edible cyanobacterium Nostochopsis sp.

    PubMed

    Hashimoto, Eri; Yabuta, Yukinori; Takenaka, Shigeo; Yamaguchi, Yuji; Takenaka, Hiroyuki; Watanabe, Fumio

    2012-01-01

    Vitamin B₁₂ content of an edible cyanobacterium, Nostochopsis sp. was determined to be 140.6±16.2 μg/100 g dry weight by a microbiological method. To evaluate whether the Nostochopsis cells contain vitamin B₁₂ or inactive corrinoid compounds, corrinoid compounds were purified from the cells and then identified as pseudovitamin B₁₂ (97.4±11.8 μg/100 g dry weight) and vitamin B₁₂ (43.2±6.0 μg/100 g dry weight) on the basis of silica gel 60 TLC bioautograms and LC/ESI-MS/MS chromatograms. Vitamin B₁₂ content was significantly increased in the Nostochopsis cells (254.8±17.6 μg/100 g dry weight) grown in the vitamin B₁₂-supplemented medium.

  13. An unusual gene arrangement for the putative chromosome replication origin and circadian expression of dnaN in Synechococcus sp. strain PCC 7942.

    PubMed

    Liu, Y; Tsinoremas, N F

    1996-06-12

    In eubacteria, the clustering of DnaA boxes around the dnaN (beta subunit of DNA polymerase III) and dnaA genes usually defines the chromosome replication origin (oriC). In this study, the dnaN locus from the cyanobacterium Synechococcus sp. strain PCC 7942 was sequenced. The gene order in this region is cbbZp-dnaN-orf288-purL-purF which contrasts with other eubacteria. A cluster of eleven DnaA boxes (consensus sequence: TTTTCCACA) was found in the intergenic region between dnaN and cbbZp. We also found a 41-bp sequence within this region that is 80% identical to the proposed oriC of Streptomyces coelicolor. Therefore, we propose that this intergenic region may serve as an oriC in Synechococcus. Using bacterial luciferase as a reporter, we also showed that dnaN is rhythmically expressed, suggesting that DNA replication could be under circadian control in this organism.

  14. Glycogen production for biofuels by the euryhaline cyanobacteria Synechococcus sp. strain PCC 7002 from an oceanic environment.

    PubMed

    Aikawa, Shimpei; Nishida, Atsumi; Ho, Shih-Hsin; Chang, Jo-Shu; Hasunuma, Tomohisa; Kondo, Akihiko

    2014-01-01

    Oxygenic photosynthetic microorganisms such as cyanobacteria and microalgae have attracted attention as an alternative carbon source for the next generation of biofuels. Glycogen abundantly accumulated in cyanobacteria is a promising feedstock which can be converted to ethanol through saccharification and fermentation processes. In addition, the utilization of marine cyanobacteria as a glycogen producer can eliminate the need for a freshwater supply. Synechococcus sp. strain PCC 7002 is a fast-growing marine coastal euryhaline cyanobacteria, however, the glycogen yield has not yet been determined. In the present study, the effects of light intensity, CO2 concentration, and salinity on the cell growth and glycogen content were investigated in order to maximize glycogen production in Synechococcus sp. strain PCC 7002. The optimal culture conditions for glycogen production in Synechococcus sp. strain PCC 7002 were investigated. The maximum glycogen production of 3.5 g L(-1) for 7 days (a glycogen productivity of 0.5 g L(-1) d(-1)) was obtained under a high light intensity, a high CO2 level, and a nitrogen-depleted condition in brackish water. The glycogen production performance in Synechococcus sp. strain PCC 7002 was the best ever reported in the α-polyglucan (glycogen or starch) production of cyanobacteria and microalgae. In addition, the robustness of glycogen production in Synechococcus sp. strain PCC 7002 to salinity was evaluated in seawater and freshwater. The peak of glycogen production of Synechococcus sp. strain PCC 7002 in seawater and freshwater were 3.0 and 1.8 g L(-1) in 7 days, respectively. Glycogen production in Synechococcus sp. strain PCC 7002 maintained the same level in seawater and half of the level in freshwater compared with the optimal result obtained in brackish water. We conclude that Synechococcus sp. strain PCC 7002 has high glycogen production activity and glycogen can be provided from coastal water accompanied by a fluctuation

  15. Molecular characterization and homology modeling of spermidine synthase from Synechococcus sp. PCC 7942.

    PubMed

    Pothipongsa, Apiradee; Jantaro, Saowarath; Salminen, Tiina A; Incharoensakdi, Aran

    2017-04-01

    Spermidine synthase (Spds) catalyzes the formation of spermidine by transferring the aminopropyl group from decarboxylated S-adenosylmethionine (dcSAM) to putrescine. The Synechococcus spds gene encoding Spds was expressed in Escherichia coli. The purified recombinant enzyme had a molecular mass of 33 kDa and showed optimal activity at pH 7.5, 37 °C. The enzyme had higher affinity for dcSAM (K m, 20 µM) than for putrescine (K m, 111 µM) and was highly specific towards the diamine putrescine with no activity observed towards longer chain diamines. The three-dimensional structural model for Synechococcus Spds revealed that most of the ligand binding residues in Spds from Synechococcus sp. PCC 7942 are identical to those of human and parasite Spds. Based on the model, the highly conserved acidic residues, Asp89, Asp159 and Asp162, are involved in the binding of substrates putrescine and dcSAM and Pro166 seems to confer substrate specificity towards putrescine.

  16. 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

    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.

  17. 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

    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.

  18. Role of Photosynthetic Reactions in the Activity of Carbonic Anhydrase in Synechococcus sp. (UTEX 2380) in the Light 1

    PubMed Central

    Spiller, Hart; Wynns, George Clifford; Tu, Chingkuang

    1988-01-01

    The role of the photosystems in the exchange of 18O between species of inorganic carbon and water was studied in suspensions of the cyanobacterium Synechococcus sp. (UTEX 2380) using membrane-inlet mass spectrometry. This 18O exchange is caused by the hydration-dehydration cycle of CO2 and is catalyzed by carbonic anhydrase. We observed the complex 18O exchange kinetics including dark-light-dark transients in suspensions of whole cells and found these to be identical to the 18O exchange kinetics of physiologically fully active spheroplast preparations. There was no enhancement effect of inorganic nitrogen on inorganic carbon accumulation. Membrane preparations exhibited no uptake of inorganic carbon and very little carbonic anhydrase activity, although these membranes were photosynthetically fully competent. DCMU, the inhibitor of photosystem II, eliminated almost entirely the 18O exchange activity of whole cells in the light. But this effect of DCMU could be reversed by addition of the electron donor couple 3,6-diaminodurene/ascorbate, suggesting the involvement of photosystem I in the events leading to 18O exchange. Iodoacetamide, an inhibitor of CO2 fixation, enhanced the 18O exchange in whole cell suspensions and inhibited neither the uptake of inorganic carbon nor the dehydration of bicarbonate in the light. The proton carrier carbonylcyanide m-chlorophenylhydrazone and the inhibitors diethylstilbestrol and N,N′ -dicyclohexyl carbodiimide affecting the membrane potential, totally abolished 18O exchange in the light. From 18 O-labeled inorganic carbon experiments we conclude that one of the roles of photosystem I is to provide the active uptake of inorganic carbon into the cells, where carbonic anhydrase catalyzes the interconversion between CO2 and HCO3− resulting in the 18O exchange from inorganic carbon to water. PMID:16666052

  19. 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

  20. 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

  1. Proteomic Analyses of Changes in Synechococcus sp. PCC7942 Following UV-C Stress.

    PubMed

    Peng, Xi; Yang, Jie; Gao, Yang

    2017-01-25

    UV-C's effects on the physiological and biochemical processes of cyanobacteria have been well characterized. However, the molecular mechanisms of cyanobacteria's tolerance to UV-C still needs further investigation. This research attempts to decode the variation in protein abundances in cyanobacteria after UV-C stress. Different expression levels of proteins in the cytoplasm of Synechococcus sp. PCC7942 under UV-C stress were investigated by using a comparative proteomic approach. Forty-seven UV-C-regulated proteins were identified by MALDI-TOF analysis and classified by Gene Ontology (GO). After studying their pathways, the proteins were mainly enriched in the groups of protein folding, inorganic ion transport, and energy production. By focusing on these areas, this study reveals the correlation between UV-C stress-responsive proteins and the physiological changes of Synechococcus sp. PCC7942 under UV-C radiation. These findings may open up new areas for further exploration in the homeostatic mechanisms associated with cyanobacteria responses to UV-C radiation. This article is protected by copyright. All rights reserved.

  2. Cell surface acid-base properties of the cyanobacterium Synechococcus: Influences of nitrogen source, growth phase and N:P ratios

    NASA Astrophysics Data System (ADS)

    Liu, Yuxia; Alessi, D. S.; Owttrim, G. W.; Kenney, J. P. L.; Zhou, Qixing; Lalonde, S. V.; Konhauser, K. O.

    2016-08-01

    The distribution of many trace metals in the oceans is controlled by biological uptake. Recently, Liu et al. (2015) demonstrated the propensity for a marine cyanobacterium to adsorb cadmium from seawater, suggesting that cell surface reactivity might also play an important role in the cycling of metals in the oceans. However, it remains unclear how variations in cyanobacterial growth rates and nutrient supply might affect the chemical properties of their cellular surfaces. In this study we used potentiometric titrations and Fourier Transform Infrared (FT-IR) spectrometry to profile the key metabolic changes and surface chemical responses of a Synechococcus strain, PCC 7002, during different growth regimes. This included testing various nitrogen (N) to phosphorous (P) ratios (both nitrogen and phosphorous dependent), nitrogen sources (nitrate, ammonium and urea) and growth stages (exponential, stationary, and death phase). FT-IR spectroscopy showed that varying the growth substrates on which Synechococcus cells were cultured resulted in differences in either the type or abundance of cellular exudates produced or a change in the cell wall components. Potentiometric titration data were modeled using three distinct proton binding sites, with resulting pKa values for cells of the various growth conditions in the ranges of 4.96-5.51 (pKa1), 6.67-7.42 (pKa2) and 8.13-9.95 (pKa3). According to previous spectroscopic studies, these pKa ranges are consistent with carboxyl, phosphoryl, and amine groups, respectively. Comparisons between the titration data (for the cell surface) and FT-IR spectra (for the average cellular changes) generally indicate (1) that the nitrogen source is a greater determinant of ligand concentration than growth phase, and (2) that phosphorus limitation has a greater impact on Synechococcus cellular and extracellular properties than does nitrogen limitation. Taken together, these techniques indicate that nutritional quality during cell growth can

  3. Computational prediction of the osmoregulation network in Synechococcus sp. WH8102

    PubMed Central

    2010-01-01

    Background Osmotic stress is caused by sudden changes in the impermeable solute concentration around a cell, which induces instantaneous water flow in or out of the cell to balance the concentration. Very little is known about the detailed response mechanism to osmotic stress in marine Synechococcus, one of the major oxygenic phototrophic cyanobacterial genera that contribute greatly to the global CO2 fixation. Results We present here a computational study of the osmoregulation network in response to hyperosmotic stress of Synechococcus sp strain WH8102 using comparative genome analyses and computational prediction. In this study, we identified the key transporters, synthetases, signal sensor proteins and transcriptional regulator proteins, and found experimentally that of these proteins, 15 genes showed significantly changed expression levels under a mild hyperosmotic stress. Conclusions From the predicted network model, we have made a number of interesting observations about WH8102. Specifically, we found that (i) the organism likely uses glycine betaine as the major osmolyte, and others such as glucosylglycerol, glucosylglycerate, trehalose, sucrose and arginine as the minor osmolytes, making it efficient and adaptable to its changing environment; and (ii) σ38, one of the seven types of σ factors, probably serves as a global regulator coordinating the osmoregulation network and the other relevant networks. PMID:20459751

  4. Finished Genome Sequence of the Unicellular Cyanobacterium Synechocystis sp. Strain PCC 6714.

    PubMed

    Kopf, Matthias; Klähn, Stephan; Voss, Björn; Stüber, Kurt; Huettel, Bruno; Reinhardt, Richard; Hess, Wolfgang R

    2014-07-31

    Synechocystis sp. strain PCC 6714 is a unicellular cyanobacterium closely related to the popular model organism Synechocystis sp. strain PCC 6803. A combination of PacBio SMRT and Illumina GAIIx data results in a highly accurate finished genome sequence that provides a reliable resource for further comparative analyses.

  5. Carbon sequestration in Synechococcus Sp.: from molecular machines to hierarchical modeling.

    SciTech Connect

    Martino, Anthony A. (Sandia National Laboratories, Livermore, CA); Heffelfinger, Grant S.; Frink, Laura J. Douglas; Davidson, George S.; Haaland, David Michael; Timlin, Jerilyn Ann; Plimpton, Steven James; Lane, Todd W.; Thomas, Edward Victor; Rintoul, Mark Daniel; Roe, Diana C. (Sandia National Laboratories, Livermore, CA); Faulon, Jean-Loup Michel; Hart, William Eugene

    2003-02-01

    The U.S. Department of Energy recently announced the first five grants for the Genomes to Life (GTL) Program. The goal of this program is to ''achieve the most far-reaching of all biological goals: a fundamental, comprehensive, and systematic understanding of life.'' While more information about the program can be found at the GTL website (www.doegenomestolife.org), this paper provides an overview of one of the five GTL projects funded, ''Carbon Sequestration in Synechococcus Sp.: From Molecular Machines to Hierarchical Modeling.'' This project is a combined experimental and computational effort emphasizing developing, prototyping, and applying new computational tools and methods to elucidate the biochemical mechanisms of the carbon sequestration of Synechococcus Sp., an abundant marine cyanobacteria known to play an important role in the global carbon cycle. Understanding, predicting, and perhaps manipulating carbon fixation in the oceans has long been a major focus of biological oceanography and has more recently been of interest to a broader audience of scientists and policy makers. It is clear that the oceanic sinks and sources of CO(2) are important terms in the global environmental response to anthropogenic atmospheric inputs of CO(2) and that oceanic microorganisms play a key role in this response. However, the relationship between this global phenomenon and the biochemical mechanisms of carbon fixation in these microorganisms is poorly understood. The project includes five subprojects: an experimental investigation, three computational biology efforts, and a fifth which deals with addressing computational infrastructure challenges of relevance to this project and the Genomes to Life program as a whole. Our experimental effort is designed to provide biology and data to drive the computational efforts and includes significant investment in developing new experimental methods for uncovering protein partners, characterizing protein complexes, identifying new

  6. Carbon sequestration in Synechococcus Sp.: from molecular machines to hierarchical modeling.

    PubMed

    Heffelfinger, Grant S; Martino, Anthony; Gorin, Andrey; Xu, Ying; Rintoul, Mark D; Geist, Al; Al-Hashimi, Hashim M; Davidson, George S; Faulon, Jean Loup; Frink, Laurie J; Haaland, David M; Hart, William E; Jakobsson, Erik; Lane, Todd; Li, Ming; Locascio, Phil; Olken, Frank; Olman, Victor; Palenik, Brian; Plimpton, Steven J; Roe, Diana C; Samatova, Nagiza F; Shah, Manesh; Shoshoni, Arie; Strauss, Charlie E M; Thomas, Edward V; Timlin, Jerilyn A; Xu, Dong

    2002-01-01

    The U.S. Department of Energy recently announced the first five grants for the Genomes to Life (GTL) Program. The goal of this program is to "achieve the most far-reaching of all biological goals: a fundamental, comprehensive, and systematic understanding of life." While more information about the program can be found at the GTL website (www.doegenomestolife.org), this paper provides an overview of one of the five GTL projects funded, "Carbon Sequestration in Synechococcus Sp.: From Molecular Machines to Hierarchical Modeling." This project is a combined experimental and computational effort emphasizing developing, prototyping, and applying new computational tools and methods to elucidate the biochemical mechanisms of the carbon sequestration of Synechococcus Sp., an abundant marine cyanobacteria known to play an important role in the global carbon cycle. Understanding, predicting, and perhaps manipulating carbon fixation in the oceans has long been a major focus of biological oceanography and has more recently been of interest to a broader audience of scientists and policy makers. It is clear that the oceanic sinks and sources of CO(2) are important terms in the global environmental response to anthropogenic atmospheric inputs of CO(2) and that oceanic microorganisms play a key role in this response. However, the relationship between this global phenomenon and the biochemical mechanisms of carbon fixation in these microorganisms is poorly understood. The project includes five subprojects: an experimental investigation, three computational biology efforts, and a fifth which deals with addressing computational infrastructure challenges of relevance to this project and the Genomes to Life program as a whole. Our experimental effort is designed to provide biology and data to drive the computational efforts and includes significant investment in developing new experimental methods for uncovering protein partners, characterizing protein complexes, identifying new

  7. An extended siderophore suite from Synechococcus sp. PCC 7002 revealed by LC-ICPMS-ESIMS.

    PubMed

    Boiteau, Rene M; Repeta, Daniel J

    2015-05-01

    Siderophores are thought to play an important role in iron cycling in the ocean, but relatively few marine siderophores have been identified. Sensitive, high throughput methods hold promise for expediting the discovery and characterization of new siderophores produced by marine microbes. We developed a methodology for siderophore characterization that combines liquid chromatography (LC) inductively coupled plasma mass spectrometry (ICPMS) with high resolution electrospray ionization mass spectrometry (ESIMS). To demonstrate this approach, we investigated siderophore production by the marine cyanobacteria Synechococcus sp. PCC 7002. Three hydroxamate siderophores, synechobactin A-C, have been previously isolated and characterized from this strain. These compounds consist of an iron binding head group attached to a fatty acid side chain of variable length (C12, C10, and C8 respectively). In this study, we detected six iron-containing compounds in Synechococcus sp. PCC 7002 media by LC-ICPMS. To identify the molecular ions of these siderophores, we aligned the chromatographic retention times of peaks from the LC-ICPMS chromatogram with features detected from LC-ESIMS spectra using an algorithm designed to recognize metal isotope patterns. Three of these compounds corresponded to synechobactins A (614 m/z), B (586 m/z), and C (558 m/z). The MS2 spectra of these compounds revealed diagnostic synechobactin fragmentation patterns which were used to confirm the identity of the three unknown compounds (600, 628, and 642 m/z) as new members of the synechobactin suite with side chain lengths of 11, 13, and 14 carbons. These results demonstrate the potential of combined LCMS techniques for the identification of novel iron-organic complexes.

  8. Arsenic biotransformation by a cyanobacterium Nostoc sp. PCC 7120.

    PubMed

    Xue, Xi-Mei; Yan, Yu; Xiong, Chan; Raber, Georg; Francesconi, Kevin; Pan, Ting; Ye, Jun; Zhu, Yong-Guan

    2017-09-01

    Nostoc sp. PCC 7120 (Nostoc), a typical filamentous cyanobacterium ubiquitous in aquatic system, is recognized as a model organism to study prokaryotic cell differentiation and nitrogen fixation. In this study, Nostoc cells incubated with arsenite (As(III)) for two weeks were extracted with dichloromethane/methanol (DCM/MeOH) and the extract was partitioned between water and DCM. Arsenic species in aqueous and DCM layers were determined using high performance liquid chromatography - inductively coupled plasma mass spectrometer/electrospray tandem mass spectrometry (HPLC-ICPMS/ESIMSMS). In addition to inorganic arsenic (iAs), the aqueous layer also contained monomethylarsonate (MAs(V)), dimethylarsinate (DMAs(V)), and the two arsenosugars, namely a glycerol arsenosugar (Oxo-Gly) and a phosphate arsenosugar (Oxo-PO4). Two major arsenosugar phospholipids (AsSugPL982 and AsSugPL984) were detected in DCM fraction. Arsenic in the growth medium was also investigated by HPLC/ICPMS and shown to be present mainly as the inorganic forms As(III) and As(V) accounting for 29%-38% and 29%-57% of the total arsenic respectively. The total arsenic of methylated arsenic, arsenosugars, and arsenosugar phospholipids in Nostoc cells with increasing As(III) exposure were not markedly different, indicating that the transformation to organoarsenic in Nostoc was not dependent on As(III) concentration in the medium. Our results provide new insights into the role of cyanobacteria in the biogeochemical cycling of arsenic. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Ferredoxin and flavodoxin from the cyanobacterium Synechocystis sp PCC 6803.

    PubMed

    Bottin, H; Lagoutte, B

    1992-07-06

    The unicellular cyanobacterium Synechocystis sp PCC 6803 is capable of synthesizing two different Photosystem-I electron acceptors, ferredoxin and flavodoxin. Under normal growth conditions a [2Fe-2S] ferredoxin was recovered and purified to homogeneity. The complete amino-acid sequence of this protein was established. The isoelectric point (pI = 3.48), midpoint redox potential (Em = -0.412 V) and stability under denaturing conditions were also determined. This ferredoxin exhibits an unusual electrophoretic behavior, resulting in a very low apparent molecular mass between 2 and 3.5 kDa, even in the presence of high concentrations of urea. However, a molecular mass of 10,232 Da (apo-ferredoxin) is calculated from the sequence. Free thiol assays indicate the presence of a disulfide bridge in this protein. A small amount of ferredoxin was also found in another fraction during the purification procedure. The amino-acid sequence and properties of this minor ferredoxin were similar to those of the major ferredoxin. However, its solubility in ammonium sulfate and its reactivity with antibodies directed against spinach ferredoxin were different. Traces of flavodoxin were also recovered from the same fraction. The amount of flavodoxin was dramatically increased under iron-deficient growth conditions. An acidic isoelectric point was measured (pI = 3.76), close to that of ferredoxin. The midpoint redox potentials of flavodoxin are Em1 = -0.433 V and Em2 = -0.238 V at pH 7.8. Sequence comparison based on the 42 N-terminal amino acids indicates that Synechocystis 6803 flavodoxin most likely belongs to the long-chain class, despite an apparent molecular mass of 15 kDa determined by SDS-PAGE.

  10. Dried Colony in Cyanobacterium, Nostoc sp. HK-01 — Several high Space Environment Tolerances for ``Tanpopo'' Mission

    NASA Astrophysics Data System (ADS)

    Tomita-Yokotani, K.; Kimura, S.; Kimura, Y.; Igarashi, Y.; Ajioka, R.; Sato, S.; Katoh, H.; Baba, K.

    2013-11-01

    A cyanobacterium, Nostoc sp. HK-01, has high several space environmental tolerance. Nostoc sp HK-01 would have high contribution for the “Tanpopo” mission in Japan Experimental Module of the International Space Station.

  11. Construction of a novel d-lactate producing pathway from dihydroxyacetone phosphate of the Calvin cycle in cyanobacterium, Synechococcus elongatus PCC 7942.

    PubMed

    Hirokawa, Yasutaka; Goto, Ryota; Umetani, Yoshitaka; Hanai, Taizo

    2017-07-01

    Using engineered cyanobacteria to produce various chemicals from carbon dioxide is a promising technology for a sustainable future. Lactate is a valuable commodity that can be used for the biodegradable plastic, polylactic acid. Typically, lactate production using engineered cyanobacteria was via the conversion of pyruvate in glycolysis by lactate dehydrogenase. In cyanobacteria, the metabolic flux in the Calvin cycle is higher than that in glycolysis under photoautotrophic conditions. The construction of a novel lactate producing pathway that uses metabolites from the Calvin cycle could potentially increase lactate productivity in cyanobacteria. In order to develop such a novel lactate production pathway, we engineered a cyanobacterium Synechococcus elongatus PCC 7942 strain that produced lactate directly from carbon dioxide using dihydroxyacetone phosphate (DHAP) via methylglyoxal. We confirmed that wild-type strain of S. elongatus PCC 7942 could produce lactate using exogenous methylglyoxal. A methylglyoxal synthase gene, mgsA, from Escherichia coli was introduced into Synechococcus elongates PCC 7942 for conversion of DHAP to methylglyoxal. This engineered strain produced lactate directly from carbon dioxide. Genes encoding intrinsic putative glyoxalase I, II (Synpcc7942_0638, 1403) and the lactate/H(+) symporter from E. coli (lldP) were additionally introduced to enhance the production. For higher lactate production, it was important to maintain elevated extracellular pH due to the characteristics of lactate exporting system. In this study, the highest lactate titer of 13.7 mM (1.23 g/l) was achieved during a 24-day incubation with the engineered S. elongatus PCC 7942 strain possessing the novel lactate producing pathway. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  12. Modulation of medium-chain fatty acid synthesis in Synechococcus sp. PCC 7002 by replacing FabH with a Chaetoceros Ketoacyl-ACP synthase

    SciTech Connect

    Gu, Huiya; Jinkerson, Robert E.; Davies, Fiona K.; Sisson, Lyle A.; Schneider, Philip E.; Posewitz, Matthew C.

    2016-05-26

    The isolation or engineering of algal cells synthesizing high levels of medium-chain fatty acids (MCFAs) is attractive to mitigate the high clouding point of longer chain fatty acids in algal based biodiesel. To develop a more informed understanding of MCFA synthesis in photosynthetic microorganisms, we isolated several algae from Great Salt Lake and screened this collection for MCFA accumulation to identify strains naturally accumulating high levels of MCFA. A diatom, Chaetoceros sp. GSL56, accumulated particularly high levels of C14 (up to 40%), with the majority of C14 fatty acids allocated in triacylglycerols. Using whole cell transcriptome sequencing and de novo assembly, putative genes encoding fatty acid synthesis enzymes were identified. Enzymes from this Chaetoceros sp. were expressed in the cyanobacterium Synechococcus sp. PCC 7002 to validate gene function and to determine whether eukaryotic enzymes putatively lacking bacterial evolutionary control mechanisms could be used to improve MCFA production in this promising production strain. Replacement of the Synechococcus 7002 native FabH with a Chaetoceros ketoacyl-ACP synthase Ill increased MCFA synthesis up to fivefold. In conclusion, the level of increase is dependent on promoter strength and culturing conditions.

  13. Purification, crystallization and preliminary X-ray diffraction studies of UDP-glucose:tetrahydrobiopterin α-glucosyltransferase (BGluT) from Synechococcus sp. PCC 7942.

    PubMed

    Killivalavan, Asaithambi; Zhuang, Ningning; Park, Young Shik; Lee, Kon Ho

    2014-02-01

    A UDP-glucose:tetrahydrobiopterin α-glucosyltransferase (BGluT) enzyme was discovered in the cyanobacterium Synechococcus sp. PCC 7942 which transfers a glucose moiety from UDP-glucose to tetrahydrobiopterin (BH4). BGluT protein was overexpressed with selenomethionine labelling for structure determination by the multi-wavelength anomalous dispersion method. The BGluT protein was purified by nickel-affinity and size-exclusion chromatography. It was then crystallized by the hanging-drop vapour-diffusion method using a well solution consisting of 0.1 M bis-tris pH 5.5, 19%(w/v) polyethylene glycol 3350 with 4%(w/v) D(+)-galactose as an additive. X-ray diffraction data were collected to 1.99 Å resolution using a synchrotron-radiation source. The crystals belonged to the monoclinic space group C2, with unit-cell parameters a = 171.35, b = 77.99, c = 53.77 Å, β = 90.27°.

  14. Specific binding of Synechococcus sp. strain PCC 7942 proteins to the enhancer element of psbAII required for high-light-induced expression.

    PubMed Central

    Li, R; Dickerson, N S; Mueller, U W; Golden, S S

    1995-01-01

    The psbAII gene of the cyanobacterium Synechococcus sp. strain PCC 7942 is a member of a three-gene family that encodes the D1 protein of the photosystem II reaction center. Transcription of psbAII is rapidly induced when the light intensity reaching the culture increases from 125 microE.m-2.s-1 (low light) to 750 microE.m-2.s-1 (high light). The DNA segment upstream of psbAII that corresponds to the untranslated leader of its major transcript has enhancer activity and confers high-light induction. We show that one or more soluble proteins from PCC 7942 specifically bind to this region of psbAII (designated the enhancer element). In vivo footprinting showed protein binding to the enhancer element in high-light-exposed cell samples but not in those maintained at low light, even though in vitro mobility shifts were detectable with extracts from low- or high-light-grown cells. When 12 bp were deleted from the psbAII enhancer element, protein binding was impaired and high-light induction of both transcriptional and translational psbAII-lacZ reporters was significantly reduced. This finding indicates that protein binding to this region is required for high-light induction of psbAII. The mutant element also showed impaired enhancer activity when combined with a heterologous promoter. PMID:7836280

  15. Anchoring a plant cytochrome P450 via PsaM to the thylakoids in Synechococcus sp. PCC 7002: evidence for light-driven biosynthesis.

    PubMed

    Lassen, Lærke Münter; Nielsen, Agnieszka Zygadlo; Olsen, Carl Erik; Bialek, Wojciech; Jensen, Kenneth; Møller, Birger Lindberg; Jensen, Poul Erik

    2014-01-01

    Plants produce an immense variety of specialized metabolites, many of which are of high value as their bioactive properties make them useful as for instance pharmaceuticals. The compounds are often produced at low levels in the plant, and due to their complex structures, chemical synthesis may not be feasible. Here, we take advantage of the reducing equivalents generated in photosynthesis in developing an approach for producing plant bioactive natural compounds in a photosynthetic microorganism by functionally coupling a biosynthetic enzyme to photosystem I. This enables driving of the enzymatic reactions with electrons extracted from the photosynthetic electron transport chain. As a proof of concept, we have genetically fused the soluble catalytic domain of the cytochrome P450 CYP79A1, originating from the endoplasmic reticulum membranes of Sorghum bicolor, to a photosystem I subunit in the cyanobacterium Synechococcus sp. PCC 7002, thereby targeting it to the thylakoids. The engineered enzyme showed light-driven activity both in vivo and in vitro, demonstrating the possibility to achieve light-driven biosynthesis of high-value plant specialized metabolites in cyanobacteria.

  16. Anchoring a Plant Cytochrome P450 via PsaM to the Thylakoids in Synechococcus sp. PCC 7002: Evidence for Light-Driven Biosynthesis

    PubMed Central

    Lassen, Lærke Münter; Nielsen, Agnieszka Zygadlo; Olsen, Carl Erik; Bialek, Wojciech; Jensen, Kenneth; Møller, Birger Lindberg; Jensen, Poul Erik

    2014-01-01

    Plants produce an immense variety of specialized metabolites, many of which are of high value as their bioactive properties make them useful as for instance pharmaceuticals. The compounds are often produced at low levels in the plant, and due to their complex structures, chemical synthesis may not be feasible. Here, we take advantage of the reducing equivalents generated in photosynthesis in developing an approach for producing plant bioactive natural compounds in a photosynthetic microorganism by functionally coupling a biosynthetic enzyme to photosystem I. This enables driving of the enzymatic reactions with electrons extracted from the photosynthetic electron transport chain. As a proof of concept, we have genetically fused the soluble catalytic domain of the cytochrome P450 CYP79A1, originating from the endoplasmic reticulum membranes of Sorghum bicolor, to a photosystem I subunit in the cyanobacterium Synechococcus sp. PCC 7002, thereby targeting it to the thylakoids. The engineered enzyme showed light-driven activity both in vivo and in vitro, demonstrating the possibility to achieve light-driven biosynthesis of high-value plant specialized metabolites in cyanobacteria. PMID:25025215

  17. Comparison of the manganese oxygen-evolving complex in photosystem II of spinach and Synechococcus sp. with multinuclear manganese model compounds by X-ray absorption spectroscopy

    SciTech Connect

    DeRose, V.J.; Mukerji, I.; Latimer, M.J. ); Yachandra, V.K.; Klein, M.P. ); Sauer, K. Lawrence Berkeley Lab., CA )

    1994-06-15

    The evaluation of Mn X-ray absorption fine structure (EXAFS) studies on the oxygen-evolving complex (OEC) from photosystem II is described for preparations from both spinach and the cyanobacterium Synechococcus sp. poised in the S[sub 1] and S[sub 2] states. In addition to reproducing previous results suggesting the presence of bis([mu]-oxo)-bridged Mn centers in the OEC, a Fourier transform peak due to scatterers at an average distance of > 3 [angstrom] is detected in both types of preparation. In addition, subtle but reproducible changes are found in the relative amplitudes of the Fourier transform peaks due to mainly O ([approximately]1.8 [angstrom]) and Mn ([approximately] 2.7 [angstrom]) neighbors upon cryogenic advance from the S[sub 1] to the S[sub 2] state. Analysis of the peak due to scatterers at [approximately] 3 [angstrom] favors assignment to (per 4 Mn in the OEC) 1-2 heavy atom (Mn, Ca) scatterers at an average distance of 3.3-3.4 [angstrom]. The EXAFS data of several multinuclear Mn model compounds containing such scattering interactions are analyzed and compared with the data for the OEC. Structural models for the OEC are evaluated on the basis of these results. 40 refs., 9 figs., 5 tabs.

  18. Two members of a network of putative Na+/H+ antiporters are involved in salt and pH tolerance of the freshwater cyanobacterium Synechococcus elongatus.

    PubMed

    Billini, Maria; Stamatakis, Kostas; Sophianopoulou, Vicky

    2008-10-01

    Synechococcus elongatus strain PCC 7942 is an alkaliphilic cyanobacterium that tolerates a relatively high salt concentration as a freshwater microorganism. Its genome sequence revealed seven genes, nha1 to nha7 (syn_pcc79420811, syn_pcc79421264, syn_pcc7942359, syn_pcc79420546, syn_pcc79420307, syn_pcc79422394, and syn_pcc79422186), and the deduced amino acid sequences encoded by these genes are similar to those of Na(+)/H(+) antiporters. The present work focused on molecular and functional characterization of these nha genes encoding Na(+)/H(+) antiporters. Our results show that of the nha genes expressed in Escherichia coli, only nha3 complemented the deficient Na(+)/H(+) antiporter activity of the Na(+)-sensitive TO114 recipient strain. Moreover, two of the cyanobacterial strains with separate disruptions in the nha genes (Deltanha1, Deltanha2, Deltanha3, Deltanha4, Deltanha5, and Deltanha7) had a phenotype different from that of the wild type. In particular, DeltanhA3 cells showed a high-salt- and alkaline-pH-sensitive phenotype, while Deltanha2 cells showed low salt and alkaline pH sensitivity. Finally, the transcriptional profile of the nha1 to nha7 genes, monitored using the real-time PCR technique, revealed that the nha6 gene is upregulated and the nha1 gene is downregulated under certain environmental conditions.

  19. The 5' untranslated region of the rbp1 mRNA is required for translation of its mRNA under low temperatures in the cyanobacterium Synechococcus elongatus.

    PubMed

    Hayashi, Rie; Sugita, Chieko; Sugita, Mamoru

    2017-01-01

    The unicellular cyanobacterium Synechococcus elongatus has three RNA-binding protein (Rbp) genes, rbp1, rbp2 and rbp3. The rbp1 gene was upregulated by cold treatment while rbp2 and rbp3 expression decreased remarkably after exposure to cold temperatures. To investigate the mechanism underlying cold-induced rbp1 expression, a series of rbp1-luxAB transcriptional fusion constructs were expressed in S. elongatus PCC 7942 under cold conditions. The results showed that the region from -33 to -3 of the transcription initiation site contains an essential sequence for basal transcription of the rbp1 gene and that the 120-bp region (-34 to -153) does not contain critical cis-elements required for cold-shock induction. In contrast, mutational analysis carrying the 5'-untranslated region (UTR) of rbp1-luxAB translational fusions indicated that the 5'-UTR of rbp1 plays an important role in cold induction of the rbp1 gene product. Taken together, we conclude that the cold induction of rbp1 may be regulated at a posttranscriptional level rather than at the transcriptional level.

  20. Expression of a highly active catalase VktA in the cyanobacterium Synechococcus elongatus PCC 7942 alleviates the photoinhibition of photosystem II.

    PubMed

    Jimbo, Haruhiko; Noda, Akiko; Hayashi, Hidenori; Nagano, Takanori; Yumoto, Isao; Orikasa, Yoshitake; Okuyama, Hidetoshi; Nishiyama, Yoshitaka

    2013-11-01

    The repair of photosystem II (PSII) after photodamage is particularly sensitive to reactive oxygen species-such as H2O2, which is abundantly produced during the photoinhibition of PSII. In the present study, we generated a transformant of the cyanobacterium Synechococcus elongatus PCC 7942 that expressed a highly active catalase, VktA, which is derived from a facultatively psychrophilic bacterium Vibrio rumoiensis, and examined the effect of expression of VktA on the photoinhibition of PSII. The activity of PSII in transformed cells declined much more slowly than in wild-type cells when cells were exposed to strong light in the presence of H2O2. However, the rate of photodamage to PSII, as monitored in the presence of chloramphenicol, was the same in the two lines of cells, suggesting that the repair of PSII was protected by the expression of VktA. The de novo synthesis of the D1 protein, which is required for the repair of PSII, was activated in transformed cells under the same stress conditions. Similar protection of the repair of PSII in transformed cells was also observed under strong light at a relatively low temperature. Thus, the expression of the highly active catalase mitigates photoinhibition of PSII by protecting protein synthesis against damage by H2O2 with subsequent enhancement of the repair of PSII.

  1. Biosynthesis of platform chemical 3-hydroxypropionic acid (3-HP) directly from CO2 in cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Wang, Yunpeng; Sun, Tao; Gao, Xingyan; Shi, Mengliang; Wu, Lina; Chen, Lei; Zhang, Weiwen

    2016-03-01

    3-hydroxypropionic acid (3-HP) is an important platform chemical with a wide range of applications. So far large-scale production of 3-HP has been mainly through petroleum-based chemical processes, whose sustainability and environmental issues have attracted widespread attention. With the ability to fix CO2 directly, cyanobacteria have been engineered as an autotrophic microbial cell factory to produce fuels and chemicals. In this study, we constructed the biosynthetic pathway of 3-HP in cyanobacterium Synechocystis sp. PCC 6803, and then optimized the system through the following approaches: i) increasing expression of malonyl-CoA reductase (MCR) gene using different promoters and cultivation conditions; ii) enhancing supply of the precursor malonyl-CoA by overexpressing acetyl-CoA carboxylase and biotinilase; iii) improving NADPH supply by overexpressing the NAD(P) transhydrogenase gene; iv) directing more carbon flux into 3-HP by inactivating the competing pathways of PHA and acetate biosynthesis. Together, the efforts led to a production of 837.18 mg L(-1) (348.8 mg/g dry cell weight) 3-HP directly from CO2 in Synechocystis after 6 days cultivation, demonstrating the feasibility photosynthetic production of 3-HP directly from sunlight and CO2 in cyanobacteria. In addition, the results showed that overexpression of the ribulose-1, 5-bisphosphate carboxylase/oxygenase (Rubisco) gene from Anabaena sp. PCC 7120 and Synechococcus sp. PCC 7942 led to no increase of 3-HP production, suggesting CO2 fixation may not be a rate-limiting step for 3-HP biosynthesis in Synechocystis.

  2. Functional characterization of the gene encoding UDP-glucose: tetrahydrobiopterin alpha-glucosyltransferase in Synechococcus sp. PCC 7942.

    PubMed

    Cha, En-Young; Park, Jeong Soon; Jeon, Sireong; Kong, Jin Seon; Choi, Yong Kee; Ryu, Jee-Youn; Park, Youn-Il; Park, Young Shik

    2005-04-01

    In this study, we attempted to characterize the Synechococcus sp. PCC 7942 mutant resultant from a disruption in the gene encoding UDP-glucose: tetrahydrobiopterin alpha-glucosyltransferase (BGluT). 2D-PAGE followed by MALDI-TOF mass spectrometry revealed that phycocyanin rod linker protein 33K was one of the proteins expressed at lower level in the BGluT mutant. BGluT mutant cells were also determined to be more sensitive to high light stress. This is because photosynthetic O2 exchange rates were significantly decreased, due to the reduced number of functional PSIs relative to the wild type cells. These results suggested that, in Synechococcus sp. PCC 7942, BH4-glucoside might be involved in photosynthetic photoprotection.

  3. 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.

  4. Draft Genome Sequence of Cyanobacterium sp. Strain IPPAS B-1200 with a Unique Fatty Acid Composition

    PubMed Central

    Starikov, Alexander Y.; Usserbaeva, Aizhan A.; Sinetova, Maria A.; Sarsekeyeva, Fariza K.; Zayadan, Bolatkhan K.; Ustinova, Vera V.; Kupriyanova, Elena V.; Los, Dmitry A.

    2016-01-01

    Here, we report the draft genome of Cyanobacterium sp. IPPAS strain B-1200, isolated from Lake Balkhash, Kazakhstan, and characterized by the unique fatty acid composition of its membrane lipids, which are enriched with myristic and myristoleic acids. The approximate genome size is 3.4 Mb, and the predicted number of coding sequences is 3,119. PMID:27856596

  5. Draft Genome Sequence of the Thermotolerant Cyanobacterium Desertifilum sp. IPPAS B-1220

    PubMed Central

    Sinetova, Maria A.; Bolatkhan, Kenzhegul; Zayadan, Bolatkhan K.; Ustinova, Vera V.; Kupriyanova, Elena V.; Skrypnik, Alexandra N.; Gogoleva, Natalya E.; Gogolev, Yuriy V.; Los, Dmitry A.

    2016-01-01

    Here, we report the draft genome of the filamentous cyanobacterium Desertifilum sp. strain IPPAS B-1220, isolated from Lake Shar-Nuur, Mongolia. The genome of 6.1 Mb codes for 5,113 genes. Genome mining revealed 10 clusters for the synthesis of bioactive compounds (nonribosomal peptides, polyketides, bacteriocins, and lantipeptides) with potential biotechnological or medical importance. PMID:27856594

  6. Alcohol-tolerant mutants of cyanobacterium Synechococcus elongatus PCC 7942 obtained by single-cell mutant screening system.

    PubMed

    Arai, Sayuri; Hayashihara, Kayoko; Kanamoto, Yuki; Shimizu, Kazunori; Hirokawa, Yasutaka; Hanai, Taizo; Murakami, Akio; Honda, Hiroyuki

    2017-04-12

    Enhancement of alcohol tolerance in microorganisms is an important strategy for improving bioalcohol productivity. Although cyanobacteria can be used as a promising biocatalyst to produce various alcohols directly from CO2 , low productivity and low tolerance against alcohols are the main issues to be resolved. Nevertheless, to date, a mutant with increasing alcohol tolerance has rarely been reported.n this study, we attempted to select isopropanol (IPA)-tolerant mutants of Synechococcus elongatus PCC 7942 using UV-C-induced random mutagenesis, followed by enrichment of the tolerant candidates in medium containing 10 g/L IPA and screening of the cells with a high growth rate in the single cell culture system in liquid medium containing 10 g/L IPA. We successfully acquired the most tolerant strain, SY1043, which maintains the ability to grow in medium containing 30 g/L IPA. The photosynthetic oxygen-evolving activities of SY1043 were almost same in cells after 72-h incubation under light with or without 10 g/L IPA, while the activity of the wild-type was remarkably decreased after the incubation with IPA. SY1043 also showed higher tolerance to ethanol, 1-butanol, isobutanol, and 1-pentanol than the wild type. These results suggest that SY1043 would be a promising candidate to improve alcohol production using cyanobacteria. This article is protected by copyright. All rights reserved.

  7. Growth on Urea Can Trigger Death and Peroxidation of the Cyanobacterium Synechococcus sp. Strain PCC 7002

    PubMed Central

    Sakamoto, Toshio; Delgaizo, Victoria B.; Bryant, Donald A.

    1998-01-01

    Laboratory conditions have been identified that cause the rapid death of cultures of cyanobacteria producing urease. Once the death phase had initiated in the stationary growth phase, cells were rapidly bleached of all pigmentation. Null mutations in the ureC gene, encoding the alpha subunit of urease, were constructed, and these mutants were no longer sensitive to growth in the presence of urea. High levels of peroxides, including lipid peroxides, were detected in the bleaching cells. Exogenously added polyunsaturated fatty acids triggered a similar death response. Vitamin E suppressed the formation of peroxides and delayed the onset of cell bleaching. The results suggest that these cyanobacterial cells undergo a metabolic imbalance that ultimately leads to oxidative stress and lipid peroxide formation. These observations may provide insights into the mechanism of sudden cyanobacterial bloom disappearance in nature. PMID:9647800

  8. Improvement of 1,3-propanediol production using an engineered cyanobacterium, Synechococcus elongatus by optimization of the gene expression level of a synthetic metabolic pathway and production conditions.

    PubMed

    Hirokawa, Yasutaka; Maki, Yuki; Hanai, Taizo

    2017-01-01

    The introduction of a synthetic metabolic pathway consisting of multiple genes derived from various organisms enables cyanobacteria to directly produce valuable chemicals from carbon dioxide. We previously constructed a synthetic metabolic pathway composed of genes from Escherichia coli, Saccharomyces cerevisiae, and Klebsiella pneumoniae. This pathway enabled 1,3-propanediol (1,3-PDO) production from cellular DHAP via glycerol in the cyanobacterium, Synechococcus elongatus PCC 7942. The production of 1,3-PDO (3.79mM, 0.29g/l) directly from carbon dioxide by engineered S. elongatus PCC 7942 was successfully accomplished. However, the constructed strain accumulated a remarkable amount of glycerol (12.6mM, 1.16g/l), an intermediate metabolite in 1,3-PDO production. Notably, enhancement of latter reactions of synthetic metabolic pathway for conversion of glycerol to 1,3-PDO increases 1,3-PDO production. In this study, we aimed to increase the observed 1,3-PDO production titer. First, the weaker S. elongatus PCC 7942 promoter, PLlacO1, was replaced with a stronger promoter (Ptrc) to regulate genes involved in the conversion of glycerol to 1,3-PDO. Second, the induction timing for gene expression and medium composition were optimized. Promoter replacement resulted in higher 1,3-PDO production than glycerol accumulation, and the amount of products (1,3-PDO and glycerol) generated via the synthetic metabolic pathway increased with optimization of medium composition. Accordingly, we achieved the highest titer of 1,3-PDO (16.1mM, 1.22g/l) and this was higher than glycerol accumulation (9.46mM, 0.87g/l). The improved titer was over 4-fold higher than that of our previous study.

  9. Light control of hliA transcription and transcript stability in the cyanobacterium Synechococcus elongatus strain PCC 7942.

    PubMed

    Salem, Kavitha; van Waasbergen, Lorraine G

    2004-03-01

    The high-light-inducible proteins (HLIPs) of cyanobacteria are polypeptides involved in protecting the cells from high-intensity light (HL). The hliA gene encoding the HLIP from Synechococcus elongatus strain PCC 7942 is expressed in response to HL or low-intensity blue or UV-A light. In this study, we explore via Northern analysis details of the transcriptional regulation and transcript stability of the hliA gene under various light conditions. Transcript levels of the hliA gene increased dramatically upon a shift to HL or UV-A light to similar levels, followed by a rapid decrease in UV-A light, but not in HL, consistent with blue/UV-A light involvement in early stages of HL-mediated expression. A 3-min pulse of low-intensity UV-A light was enough to trigger hliA mRNA accumulation, indicating that a blue/UV-A photoreceptor is involved in upregulation of the gene. Low-intensity red light was found to cause a slight, transient increase in transcript levels (raising the possibility of red-light photoreceptor involvement), while light of other qualities had no apparent effect. No evidence was found for wavelength-specific attenuation of hliA transcript levels induced by HL or UV-A light. Transcript decay was slowed somewhat in darkness, and when photosynthetic electron transport was inhibited by darkness or treatment with DCMU, there appeared a smaller mRNA species that may represent a decay intermediate that accumulates when mRNA decay is slowed. Evidence suggests that upregulation of hliA by light is primarily a transcriptional response but conditions that cause ribosomes to stall on the transcript (e.g., a shift to darkness) can help stabilize hliA mRNA and affect expression levels.

  10. 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

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

    PubMed

    Raveh, Avi; Carmeli, Shmuel

    2010-08-06

    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.

  12. Rubidibacter lacunae gen. nov., sp. nov., a unicellular, phycoerythrin-containing cyanobacterium isolated from seawater of Chuuk lagoon, Micronesia.

    PubMed

    Choi, Dong Han; Noh, Jae Hoon; Lee, Charity M; Rho, Seungmok

    2008-12-01

    A unicellular cyanobacterium, designated KORDI 51-2(T), was isolated from surface seawater of Chuuk lagoon, Micronesia. The cells were wine-coloured rods and emitted red fluorescence under green excitation of an epifluorescence microscope. Thus, morphologically, the strain resembled Synechococcus species. However, based on 16S rRNA gene sequence similarities between strain KORDI 51-2(T) and related strains belonging to cyanobacteria, the novel strain was distantly related to members of the 'Halothece' cluster. However, sequence similarities between strain KORDI 51-2(T) and members of the 'Halothece' cluster were very low, ranging from 90.7 to 92.1 %, and phylogenetic analyses showed that the strain formed a distinct branch. Therefore, a polyphasic characterization including morphology, physiology and pigment composition was conducted to elucidate the taxonomic position of strain KORDI 51-2(T). The strain grew within a temperature range of 25-35 degrees C and a salinity range of 2-7 %. The optimal temperature and salinity were about 30 degrees C and 5 %, respectively. Strain KORDI 51-2(T) contained phycoerythrin, and the dominant carotenoid pigments were zeaxanthin, beta-carotene and echinenone. The DNA G+C content was 60.5 mol%. Based on phylogenetic analysis of the 16S rRNA gene sequence, and the physiological data and pigment compositions, strain KORDI 51-2(T) is considered to represent a new genus and novel species of cyanobacteria for which the name Rubidibacter lacunae gen. nov., sp. nov. is proposed. The type strain is KORDI 51-2(T) (=KCTC 40015(T)=UTEX L2944(T)).

  13. Effect of mono- and dichromatic light quality on growth rates and photosynthetic performance of Synechococcus sp. PCC 7002

    SciTech Connect

    Bernstein, Hans C.; Konopka, Allan; Melnicki, Matthew R.; Hill, Eric A.; Kucek, Leo A.; Zhang, Shuyi; Shen, Gaozhong; Bryant, Donald A.; Beliaev, Alex S.

    2014-09-19

    Synechococcus sp. PCC 7002 was grown to steady state in optically thin turbidostat cultures under conditions for which light quantity and quality was systematically varied by modulating the output of narrow-band LEDs. Cells were provided photons absorbed primarily by chlorophyll (680 nm) or phycocyanin (630 nm) as the organism was subjected to four distinct mono- and dichromatic regimes. During cultivation with dichromatic light, growth rates displayed by Synechococcus sp. PCC 7002 were generally proportional to the total incident irradiance at values < 275 µmol photons m-2 s-1 and were not affected by the ratio of 630:680 nm wavelengths. Notably, under monochromatic light conditions, cultures exhibited similar growth rates only when they were irradiated with 630 nm light; cultures irradiated with only 680 nm light grew at rates that were 60 – 70% of those under other light quality regimes at equivalent irradiances. The functionality of photosystem II and associated processes such as maximum rate of photosynthetic electron transport, rate of cyclic electron flow, and rate of dark respiration generally increased as a function of growth rate. Nonetheless, some of the photophysiological parameters measured here displayed distinct patterns with respect to growth rate of cultures adapted to a single wavelength including phycobiliprotein content, which increased under severely light-limited growth conditions. Additionally, the ratio of photosystem II to photosystem I increased approximately 40% over the range of growth rates, although cells grown with 680 nm light only had the highest ratios. These results suggest the presence of effective mechanisms which allow acclimation of Synechococcus sp. PCC 7002 acclimation to different irradiance conditions.

  14. Development of a high-frequency in vivo transposon mutagenesis system for Synechocystis sp. PCC 6803 and Synechococcus elongatus PCC 7942.

    PubMed

    Watabe, Kazuyuki; Mimuro, Mamoru; Tsuchiya, Tohru

    2014-11-01

    Synechocystis sp. PCC 6803 (Synechocystis) is the first sequenced photosynthetic organism and has two advantages: natural transformation and light-activated heterotrophic growth. Such characteristics have mainly promoted reverse genetic analysis in this organism, however, to date approximately 50% of genes are still annotated as 'unknown protein' or 'hypothetical protein'. Therefore, forward genetic analysis is required for the identification of significant genes responsible for photosynthesis and other physiological phenomena among the genes of unknown function. The in vivo transposon mutagenesis system is one of the major methods for random mutagenesis. However, present in vivo transposon mutagenesis systems for cyanobacteria face problems such as relatively low frequency of transposition and repeated transposition in the host cells. In this study, we constructed vectors based on a mini-Tn5-derived vector that was designed to prevent repeated transposition. Our vectors carry a hyperactive transposase and optimized recognition sequence of transposase, which were reported to enhance frequency of transposition. Using the vector, we succeeded in highly frequent transposition (9×10(-3) per recipient cell) in Synechocystis. Transposon insertion sites of 10 randomly selected mutants indicated that the insertion sites spread throughout the genome with low sequence dependency. Furthermore, one of the 10 mutants exhibited the slow-growing phenotype, and the mutant was functionally complemented by using our expression vector. Our system also worked with another model cyanobacterium, Synechococcus elongatus PCC 7942, with high frequency. These results indicate that the developed system can be applied to the forward genetic analysis of a broad range of cyanobacteria. © The Author 2014. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  15. ChlR Protein of Synechococcus sp. PCC 7002 Is a Transcription Activator That Uses an Oxygen-sensitive [4Fe-4S] Cluster to Control Genes involved in Pigment Biosynthesis*

    PubMed Central

    Ludwig, Marcus; Pandelia, Maria-Eirini; Chew, Chyue Yie; Zhang, Bo; Golbeck, John H.; Krebs, Carsten; Bryant, Donald A.

    2014-01-01

    Synechococcus sp. PCC 7002 and many other cyanobacteria have two genes that encode key enzymes involved in chlorophyll a, biliverdin, and heme biosynthesis: acsFI/acsFII, ho1/ho2, and hemF/hemN. Under atmospheric O2 levels, AcsFI synthesizes 3,8-divinyl protochlorophyllide from Mg-protoporphyrin IX monomethyl ester, Ho1 oxidatively cleaves heme to form biliverdin, and HemF oxidizes coproporphyrinogen III to protoporphyrinogen IX. Under microoxic conditions, another set of genes directs the synthesis of alternative enzymes AcsFII, Ho2, and HemN. In Synechococcus sp. PCC 7002, open reading frame SynPCC7002_A1993 encodes a MarR family transcriptional regulator, which is located immediately upstream from the operon comprising acsFII, ho2, hemN, and desF (the latter encodes a putative fatty acid desaturase). Deletion and complementation analyses showed that this gene, denoted chlR, is a transcriptional activator that is essential for transcription of the acsFII-ho2-hemN-desF operon under microoxic conditions. Global transcriptome analyses showed that ChlR controls the expression of only these four genes. Co-expression of chlR with a yfp reporter gene under the control of the acsFII promoter from Synechocystis sp. PCC 6803 in Escherichia coli demonstrated that no other cyanobacterium-specific components are required for proper functioning of this regulatory circuit. A combination of analytical methods and Mössbauer and EPR spectroscopies showed that reconstituted, recombinant ChlR forms homodimers that harbor one oxygen-sensitive [4Fe-4S] cluster. We conclude that ChlR is a transcriptional activator that uses a [4Fe-4S] cluster to sense O2 levels and thereby control the expression of the acsFII-ho2-hemN-desF operon. PMID:24782315

  16. Spatially-Resolved Analysis of Glycolipids and Metabolites in Living Synechococcus sp. PCC7002 Using Nanospray Desorption Electrospray Ionization

    SciTech Connect

    Lanekoff, Ingela T.; Geydebrekht, Oleg V.; Pinchuk, Grigoriy E.; Konopka, Allan; Laskin, Julia

    2013-04-07

    Microorganisms release a diversity of organic compounds that couple interspecies metabolism, enable communication, or provide benefits to other microbes. Increased knowledge of microbial metabolite production will contribute to understanding of the dynamic microbial world and can potentially lead to new developments in drug discovery, biofuel production, and clinical research. Nanospray desorption electrospray ionization (nano-DESI) is an ambient ionization technique that enables detailed chemical characterization of molecules from a specific location on a surface without special sample pretreatment. Due to its ambient nature, living bacterial colonies growing on agar plates can be rapidly and non-destructively analyzed. We performed spatially resolved nano-DESI analysis of living Synechococcus sp. PCC 7002 colonies on agar plates. We use high resolution mass spectrometry and MS/MS analysis of the living Synechococcus sp. PCC 7002 colonies to detect metabolites and lipids, and confirm their identities. We found that despite the high salt content of the agar (osmolarity ca. 700 mM), nano-DESI analysis enables detailed characterization of metabolites produced by the colony. Using this technique, we identified several glycolipids found on the living colonies and examined the effect of the age of the colony on the chemical gradient of glucosylglycerol secreted onto agar.

  17. Thin films of silk fibroin and its blend with chitosan strongly promote biofilm growth of Synechococcus sp. BDU 140432.

    PubMed

    Kaushik, Sharbani; Sarma, Mrinal K; Thungon, Phurpa Dema; Santhosh, Mallesh; Goswami, Pranab

    2016-10-01

    The activating role of different polymer thin films coated over polystyrene support on the Synechococcus sp. biofilm growth was examined concurrently by measuring biofilm florescence using a dye and by measuring cell density in the isolated biofilm. Compared to blank (no coating), the increase in biofilm formation (%) on silk, chitosan, silk-chitosan (3:2) blend, polyaniline, osmium, and Nafion films were 27.73 (31.16), 21.55 (23.74), 37.21 (38.34), 5.35 (8.96), 6.70 (6.55) and (nil), respectively with corresponding cell density (%) shown in the parentheses. This trend of biofilm formation on the films did not significantly vary for Escherichia coli and Lactobacillus plantarum strains. The films of 20 residues long each of glycine-alanine repeat peptide, which mimics a silk fibroin motif, and a hydrophobic glycine-valine repeat peptide, increased the biofilm growth by 13.53 % and 26.08 %, respectively. Silk and blend films showed highest adhesion unit (0.48-0.49), adhesion rate ((4.2-4.8)×10(-6), m/s) and Gibbs energy of adhesion (-8.5 to -8.6kT) with Synechococcus sp. The results confirmed interplay of electrostatic and hydrophobic interaction between cell-surface and polymer films for promoting rapid biofilm growth. This study established that the thin films of silk and the blend (3:2) promote rapid biofilm growth for all the tested microorganisms.

  18. Vipp1 Is Essential for the Biogenesis of Photosystem I but Not Thylakoid Membranes in Synechococcus sp. PCC 7002*

    PubMed Central

    Zhang, Shuyi; Shen, Gaozhong; Li, Zhongkui; Golbeck, John H.; Bryant, Donald A.

    2014-01-01

    The biogenesis of thylakoid membranes in cyanobacteria is presently not well understood, but the vipp1 gene product has been suggested to play an important role in this process. Previous studies in Synechocystis sp. PCC 6803 reported that vipp1 (sll0617) was essential. By constructing a fully segregated null mutant in vipp1 (SynPCC7002_A0294) in Synechococcus sp. PCC 7002, we show that Vipp1 is not essential. Spectroscopic studies revealed that Photosystem I (PS I) was below detection limits in the vipp1 mutant, but Photosystem II (PS II) was still assembled and was active. Thylakoid membranes were still observed in vipp1 mutant cells and resembled those in a psaAB mutant that completely lacks PS I. When the vipp1 mutation was complemented with the orthologous vipp1 gene from Synechocystis sp. PCC 6803 that was expressed from the strong PcpcBA promoter, PS I content and activities were restored to normal levels, and cells again produced thylakoids that were indistinguishable from those of wild type. Transcription profiling showed that psaAB transcripts were lower in abundance in the vipp1 mutant. However, when the yfp gene was expressed from the PpsaAB promoter in the presence and the absence of Vipp1, no difference in YFP expression was observed, which shows that Vipp1 is not a transcription factor for the psaAB genes. This study shows that thylakoids are still produced in the absence of Vipp1 and that normal thylakoid biogenesis in Synechococcus sp. PCC 7002 requires expression and biogenesis of PS I, which in turn requires Vipp1. PMID:24764304

  19. The amt gene cluster of the heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120.

    PubMed

    Paz-Yepes, Javier; Merino-Puerto, Victoria; Herrero, Antonia; Flores, Enrique

    2008-10-01

    The genome of the heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 bears a gene cluster including three amt genes that, based on homology of their protein products, we designate amt4, amt1, and amtB. Expression of the three genes took place upon ammonium withdrawal in combined nitrogen-free medium and was NtcA dependent. The genes were transcribed independently, but an amt4-amt1 dicistronic transcript was also produced, and expression was highest for the amt1 gene. A mutant with the whole amt region removed could grow under laboratory conditions using ammonium, nitrate, or dinitrogen as the nitrogen source.

  20. The amt Gene Cluster of the Heterocyst-Forming Cyanobacterium Anabaena sp. Strain PCC 7120 ▿

    PubMed Central

    Paz-Yepes, Javier; Merino-Puerto, Victoria; Herrero, Antonia; Flores, Enrique

    2008-01-01

    The genome of the heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 bears a gene cluster including three amt genes that, based on homology of their protein products, we designate amt4, amt1, and amtB. Expression of the three genes took place upon ammonium withdrawal in combined nitrogen-free medium and was NtcA dependent. The genes were transcribed independently, but an amt4-amt1 dicistronic transcript was also produced, and expression was highest for the amt1 gene. A mutant with the whole amt region removed could grow under laboratory conditions using ammonium, nitrate, or dinitrogen as the nitrogen source. PMID:18689479

  1. Marine Synechococcus Aggregation

    NASA Astrophysics Data System (ADS)

    Neuer, S.; Deng, W.; Cruz, B. N.; Monks, L.

    2016-02-01

    Cyanobacteria are considered to play an important role in the oceanic biological carbon pump, especially in oligotrophic regions. But as single cells are too small to sink, their carbon export has to be mediated by aggregate formation and possible consumption by zooplankton producing sinking fecal pellets. Here we report results on the aggregation of the ubiquitous marine pico-cyanobacterium Synechococcus as a model organism. We first investigated the mechanism behind such aggregation by studying the potential role of transparent exopolymeric particles (TEP) and the effects of nutrient (nitrogen or phosphorus) limitation on the TEP production and aggregate formation of these pico-cyanobacteria. We further studied the aggregation and subsequent settling in roller tanks and investigated the effects of the clays kaolinite and bentonite in a series of concentrations. Our results show that despite of the lowered growth rates, Synechococcus in nutrient limited cultures had larger cell-normalized TEP production, formed a greater volume of aggregates, and resulted in higher settling velocities compared to results from replete cultures. In addition, we found that despite their small size and lack of natural ballasting minerals, Synechococcus cells could still form aggregates and sink at measureable velocities in seawater. Clay minerals increased the number and reduced the size of aggregates, and their ballasting effects increased the sinking velocity and carbon export potential of aggregates. In comparison with the Synechococcus, we will also present results of the aggregation of the pico-cyanobacterium Prochlorococcus in roller tanks. These results contribute to our understanding in the physiology of marine Synechococcus as well as their role in the ecology and biogeochemistry in oligotrophic oceans.

  2. Overexpression of lalA, a paralog of labA, is capable of affecting both circadian gene expression and cell growth in the cyanobacterium Synechococcus elongatus PCC 7942.

    PubMed

    Taniguchi, Yasuhito; Nishikawa, Tomoe; Kondo, Takao; Oyama, Tokitaka

    2012-03-23

    In the cyanobacterium Synechococcus elongatus, LabA negatively regulates circadian gene expression under the control of Kai-protein-based clock. Here we conducted a molecular genetic analysis of lalA, a paralog of labA. Although a lalA loss of function mutant did not exhibit any apparent phenotype under our experimental conditions, lalA overexpression inhibited cell growth and decreased cell viability. Moderate lalA overexpression brought about abnormalities in circadian gene expression: reduced amplitude of kaiBC expression rhythm, and altered peak and trough timing of psbAI and kaiA expression rhythms. These results imply that lalA is capable of affecting circadian gene expression and cell growth. Copyright © 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  3. Spatially resolved analysis of glycolipids and metabolites in living Synechococcus sp. PCC 7002 using nanospray desorption electrospray ionization.

    PubMed

    Lanekoff, Ingela; Geydebrekht, Oleg; Pinchuk, Grigoriy E; Konopka, Allan E; Laskin, Julia

    2013-04-07

    Microorganisms release a diversity of organic compounds that couple interspecies metabolism, enable communication, or provide benefits to other microbes. Increased knowledge of microbial metabolite production will contribute to understanding of the dynamic microbial world and can potentially lead to new developments in drug discovery, biofuel production, and clinical research. Nanospray desorption electrospray ionization (nano-DESI) is an ambient ionization technique that enables detailed chemical characterization of molecules from a specific location on a surface without special sample pretreatment. Due to its ambient nature, living bacterial colonies growing on agar plates can be rapidly analyzed without affecting the viability of the colony. In this study we demonstrate for the first time the utility of nano-DESI for spatial profiling of chemical gradients generated by microbial communities on agar plates. We found that despite the high salt content of the agar used in this study (~350 mM), nano-DESI analysis enables detailed characterization of metabolites produced by the Synechococcus sp. PCC 7002 colonies. High resolution mass spectrometry and MS/MS analysis of the living Synechococcus sp. PCC 7002 colonies allowed us to detect metabolites and lipids on the colony and on the surrounding agar, and confirm their identities. High sensitivity of nano-DESI enabled identification of several glycolipids that have not been previously reported by extracting the cells using conventional methods. Spatial profiling demonstrated that a majority of lipids and metabolites were localized on the colony while sucrose and glucosylglycerol, an osmoprotective compound produced by cyanobacteria, were secreted onto agar. Furthermore, we demonstrated that the chemical gradients of sucrose and glucosylglycerol on agar depend on the age of the colony. The methodology presented in this study will facilitate future studies focused on molecular-level characterization of interactions

  4. Effect of mono- and dichromatic light quality on growth rates and photosynthetic performance of Synechococcus sp. PCC 7002

    PubMed Central

    Bernstein, Hans C.; Konopka, Allan; Melnicki, Matthew R.; Hill, Eric A.; Kucek, Leo A.; Zhang, Shuyi; Shen, Gaozhong; Bryant, Donald A.; Beliaev, Alexander S.

    2014-01-01

    Synechococcus sp. PCC 7002 was grown to steady state in optically thin turbidostat cultures under conditions for which light quantity and quality was systematically varied by modulating the output of narrow-band LEDs. Cells were provided photons absorbed primarily by chlorophyll (680 nm) or phycocyanin (630 nm) as the organism was subjected to four distinct mono- and dichromatic regimes. During cultivation with dichromatic light, growth rates were generally proportional to the total incident irradiance at values <275 μmol photons m−2 · s−1 and were not affected by the ratio of 630:680 nm wavelengths. Notably, under monochromatic light conditions, cultures exhibited similar growth rates only when they were irradiated with 630 nm light; cultures irradiated with only 680 nm light grew at rates that were 60–70% of those under other light quality regimes at equivalent irradiances. The functionality of photosystem II and associated processes such as maximum rate of photosynthetic electron transport, rate of cyclic electron flow, and rate of dark respiration generally increased as a function of growth rate. Nonetheless, some of the photophysiological parameters measured here displayed distinct patterns with respect to growth rate of cultures adapted to a single wavelength including phycobiliprotein content, which increased under severely light-limited growth conditions. Additionally, the ratio of photosystem II to photosystem I increased ~40% over the range of growth rates, although cells grown with 680 nm light only had the highest ratios. These results suggest the presence of effective mechanisms which allow acclimation of Synechococcus sp. PCC 7002 acclimation to different irradiance conditions. PMID:25285095

  5. Growth of Synechococcus sp. immobilized in chitosan with different times of contact with NaOH

    PubMed Central

    Aguilar-May, Bily; Lizardi, Jaime; Voltolina, Domenico

    2006-01-01

    The thickness of the walls of the capsules of chitosan-immobilized Synechococcus cultures was dependent on the time of contact with NaOH and was directly related to culture growth. After an initial lag phase, probably caused by cell damage, the capsules obtained after 80 s in a 0.1 N NaOH solution showed better growth than that of free cell cultures (6.9 and 5.2 divisions in 10 days, respectively). PMID:19396351

  6. Integrated Transcriptomic and Proteomic Analysis of the Global Response of Synechococcus to High Light Stress*

    PubMed Central

    Xiong, Qian; Feng, Jie; Li, Si-ting; Zhang, Gui-ying; Qiao, Zhi-xian; Chen, Zhuo; Wu, Ying; Lin, Yan; Li, Tao; Ge, Feng; Zhao, Jin-dong

    2015-01-01

    Sufficient light is essential for the growth and physiological functions of photosynthetic organisms, but prolonged exposure to high light (HL) stress can cause cellular damage and ultimately result in the death of these organisms. Synechococcus sp. PCC 7002 (hereafter Synechococcus 7002) is a unicellular cyanobacterium with exceptional tolerance to HL intensities. However, the molecular mechanisms involved in HL response by Synechococcus 7002 are not well understood. Here, an integrated RNA sequencing transcriptomic and quantitative proteomic analysis was performed to investigate the cellular response to HL in Synechococcus 7002. A total of 526 transcripts and 233 proteins were identified to be differentially regulated under HL stress. Data analysis revealed major changes in mRNAs and proteins involved in the photosynthesis pathways, resistance to light-induced damage, DNA replication and repair, and energy metabolism. A set of differentially expressed mRNAs and proteins were validated by quantitative RT-PCR and Western blot, respectively. Twelve genes differentially regulated under HL stress were selected for knockout generation and growth analysis of these mutants led to the identification of key genes involved in the response of HL in Synechococcus 7002. Taken altogether, this study established a model for global response mechanisms to HL in Synechococcus 7002 and may be valuable for further studies addressing HL resistance in photosynthetic organisms. PMID:25681118

  7. Draft Genome Sequence of Limnobacter sp. Strain CACIAM 66H1, a Heterotrophic Bacterium Associated with Cyanobacteria.

    PubMed

    da Silva, Fábio Daniel Florêncio; Lima, Alex Ranieri Jerônimo; Moraes, Pablo Henrique Gonçalves; Siqueira, Andrei Santos; Dall'Agnol, Leonardo Teixeira; Baraúna, Anna Rafaella Ferreira; Martins, Luisa Carício; Oliveira, Karol Guimarães; de Lima, Clayton Pereira Silva; Nunes, Márcio Roberto Teixeira; Vianez-Júnior, João Lídio Silva Gonçalves; Gonçalves, Evonnildo Costa

    2016-05-19

    Ecological interactions between cyanobacteria and heterotrophic prokaryotes are poorly known. To improve the genomic studies of heterotrophic bacterium-cyanobacterium associations, the draft genome sequence (3.2 Mbp) of Limnobacter sp. strain CACIAM 66H1, found in a nonaxenic culture of Synechococcus sp. (cyanobacteria), is presented here.

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

    PubMed

    Kim, Ji Hyung; Kang, Do-Hyung

    2016-09-15

    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.

  9. Insights into the relationship between the haem-binding pocket and the redox potential of c6 cytochromes: four atomic resolution structures of c6 and c6-like proteins from Synechococcus sp. PCC 7002.

    PubMed

    Bialek, Wojciech; Krzywda, Szymon; Zatwarnicki, Pawel; Jaskolski, Mariusz; Kolesinski, Piotr; Szczepaniak, Andrzej

    2014-11-01

    The structure of cytochrome c6C from the mesophilic cyanobacterium Synechococcus sp. PCC 7002 has been determined at 1.03 Å resolution. This is the first structural report on the recently discovered cyanobacterial cytochrome c6-like proteins found in marine and nitrogen-fixing cyanobacteria. Despite high similarity in the overall three-dimensional fold between cytochromes c6 and c6C, the latter shows saliently different electrostatic properties in terms of surface charge distribution and dipole moments. Its midpoint redox potential is less than half of the value for typical c6 cytochromes and results mainly from the substitution of one residue in the haem pocket. Here, high-resolution crystal structures of mutants of both cytochromes c6 and c6C are presented, and the impact of the mutation of specific residues in the haem-binding pocket on the redox potential is discussed. These findings contribute to the elucidation of the structure-function relationship of c6-like cytochromes.

  10. 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.

  11. Unique modification of adenine in genomic DNA of the marine cyanobacterium Trichodesmium sp. strain NIBB 1067.

    PubMed Central

    Zehr, J P; Ohki, K; Fujita, Y; Landry, D

    1991-01-01

    The genomic DNA of the marine nonheterocystous nitrogen-fixing cyanobacterium Trichodesmium sp. strain NIBB 1067 was found to be highly resistant to DNA restriction endonucleases. The DNA was digested extensively by the restriction enzyme DpnI, which requires adenine methylation for activity. The DNA composition, determined by high-performance liquid chromatography (HPLC), was found to be 69% AT. Surprisingly, it was found that a modified adenine which was not methylated at the usual N6 position was present and made up 4.7 mol% of the nucleosides in Trichodesmium DNA (15 mol% of deoxyadenosine). In order for adenine residues to be modified at this many positions, there must be many modifying enzymes or at least one of the modifying enzymes must have a degenerate recognition site. The reason(s) for this extensive methylation has not yet been determined but may have implications for the ecological success of this microorganism in nature. Images FIG. 1 FIG. 2 PMID:1657876

  12. BMAA inhibits nitrogen fixation in the cyanobacterium Nostoc sp. PCC 7120.

    PubMed

    Berntzon, Lotta; Erasmie, Sven; Celepli, Narin; Eriksson, Johan; Rasmussen, Ulla; Bergman, Birgitta

    2013-08-21

    Cyanobacteria produce a range of secondary metabolites, one being the neurotoxic non-protein amino acid β-N-methylamino-L-alanine (BMAA), proposed to be a causative agent of human neurodegeneration. As for most cyanotoxins, the function of BMAA in cyanobacteria is unknown. Here, we examined the effects of BMAA on the physiology of the filamentous nitrogen-fixing cyanobacterium Nostoc sp. PCC 7120. Our data show that exogenously applied BMAA rapidly inhibits nitrogenase activity (acetylene reduction assay), even at micromolar concentrations, and that the inhibition was considerably more severe than that induced by combined nitrogen sources and most other amino acids. BMAA also caused growth arrest and massive cellular glycogen accumulation, as observed by electron microscopy. With nitrogen fixation being a process highly sensitive to oxygen species we propose that the BMAA effects found here may be related to the production of reactive oxygen species, as reported for other organisms.

  13. 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.

  14. BMAA Inhibits Nitrogen Fixation in the Cyanobacterium Nostoc sp. PCC 7120

    PubMed Central

    Berntzon, Lotta; Erasmie, Sven; Celepli, Narin; Eriksson, Johan; Rasmussen, Ulla; Bergman, Birgitta

    2013-01-01

    Cyanobacteria produce a range of secondary metabolites, one being the neurotoxic non-protein amino acid β-N-methylamino-L-alanine (BMAA), proposed to be a causative agent of human neurodegeneration. As for most cyanotoxins, the function of BMAA in cyanobacteria is unknown. Here, we examined the effects of BMAA on the physiology of the filamentous nitrogen-fixing cyanobacterium Nostoc sp. PCC 7120. Our data show that exogenously applied BMAA rapidly inhibits nitrogenase activity (acetylene reduction assay), even at micromolar concentrations, and that the inhibition was considerably more severe than that induced by combined nitrogen sources and most other amino acids. BMAA also caused growth arrest and massive cellular glycogen accumulation, as observed by electron microscopy. With nitrogen fixation being a process highly sensitive to oxygen species we propose that the BMAA effects found here may be related to the production of reactive oxygen species, as reported for other organisms. PMID:23966039

  15. 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.

  16. Metabolomic analysis of NAD kinase-deficient mutants of the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Ishikawa, Yuuma; Miyagi, Atsuko; Haishima, Yuto; Ishikawa, Toshiki; Nagano, Minoru; Yamaguchi, Masatoshi; Hihara, Yukako; Kawai-Yamada, Maki

    2016-10-20

    NAD kinase (NADK) phosphorylates NAD(H) to NADP(H). The enzyme has a crucial role in the regulation of the NADP(H)/NAD(H) ratio in various organisms. The unicellular cyanobacterium Synechocystis sp. PCC 6803 possesses two NADK-encoding genes, sll1415 and slr0400. To elucidate the metabolic change in NADK-deficient mutants growing under photoautotrophic conditions, we conducted metabolomic analysis using capillary electrophoresis mass spectrometry (CE-MS). The growth curves of the wild-type parent (WT) and NADK-deficient mutants (Δ1415 and Δ0400) did not show any differences under photoautotrophic conditions. The NAD(P)(H) balance showed abnormality in both mutants. However, only the metabolite pattern of Δ0400 showed differences compared to WT. These results indicated that the two NADK isoforms have distinct functions in cyanobacterial metabolism. Copyright © 2016 Elsevier GmbH. All rights reserved.

  17. ADP-ribosylation of glutamine synthetase in the cyanobacterium Synechocystis sp. strain PCC 6803.

    PubMed Central

    Silman, N J; Carr, N G; Mann, N H

    1995-01-01

    Glutamine synthetase (GS) inactivation was observed in crude cell extracts and in the high-speed supernatant fraction from the cyanobacterium Synechocystis sp. strain PCC 6803 following the addition of ammonium ions, glutamine, or glutamate. Dialysis of the high-speed supernatant resulted in loss of inactivation activity, but this could be restored by the addition of NADH, NADPH, or NADP+ and, to a lesser extent, NAD+, suggesting that inactivation of GS involved ADP-ribosylation. This form of modification was confirmed both by labelling experiments using [32P]NAD+ and by chemical analysis of the hydrolyzed enzyme. Three different forms of GS, exhibiting no activity, biosynthetic activity only, or transferase activity only, could be resolved by chromatography, and the differences in activity were correlated with the extent of the modification. Both biosynthetic and transferase activities were restored to the completely inactive form of GS by treatment with phosphodiesterase. PMID:7768863

  18. Ammonia triggers photodamage of photosystem II in the cyanobacterium Synechocystis sp. strain PCC 6803.

    PubMed

    Drath, Miriam; Kloft, Nicole; Batschauer, Alfred; Marin, Kay; Novak, Jens; Forchhammer, Karl

    2008-05-01

    Ammonia has long been known to be toxic for many photosynthetic organisms; however, the target for its toxicity remains elusive. Here, we show that in the cyanobacterium Synechocystis sp. strain PCC 6803, ammonia triggers a rapid photodamage of photosystem II (PSII). Whereas wild-type cells can cope with this damage by turning on the FtsH2-dependent PSII repair cycle, the FtsH2-deficient mutant is highly sensitive and loses PSII activity at millimolar concentration of ammonia. Ammonia-triggered PSII destruction is light dependent and occurs already at low photon fluence rates. Experiments with monochromatic light showed that ammonia-promoted PSII photoinhibition is executed by wavebands known to directly destroy the manganese cluster in the PSII oxygen-evolving complex, suggesting that the oxygen-evolving complex may be a direct target for ammonia toxicity.

  19. ADP-ribosylation of glutamine synthetase in the cyanobacterium Synechocystis sp. strain PCC 6803.

    PubMed

    Silman, N J; Carr, N G; Mann, N H

    1995-06-01

    Glutamine synthetase (GS) inactivation was observed in crude cell extracts and in the high-speed supernatant fraction from the cyanobacterium Synechocystis sp. strain PCC 6803 following the addition of ammonium ions, glutamine, or glutamate. Dialysis of the high-speed supernatant resulted in loss of inactivation activity, but this could be restored by the addition of NADH, NADPH, or NADP+ and, to a lesser extent, NAD+, suggesting that inactivation of GS involved ADP-ribosylation. This form of modification was confirmed both by labelling experiments using [32P]NAD+ and by chemical analysis of the hydrolyzed enzyme. Three different forms of GS, exhibiting no activity, biosynthetic activity only, or transferase activity only, could be resolved by chromatography, and the differences in activity were correlated with the extent of the modification. Both biosynthetic and transferase activities were restored to the completely inactive form of GS by treatment with phosphodiesterase.

  20. Ammonia Triggers Photodamage of Photosystem II in the Cyanobacterium Synechocystis sp. Strain PCC 68031[OA

    PubMed Central

    Drath, Miriam; Kloft, Nicole; Batschauer, Alfred; Marin, Kay; Novak, Jens; Forchhammer, Karl

    2008-01-01

    Ammonia has long been known to be toxic for many photosynthetic organisms; however, the target for its toxicity remains elusive. Here, we show that in the cyanobacterium Synechocystis sp. strain PCC 6803, ammonia triggers a rapid photodamage of photosystem II (PSII). Whereas wild-type cells can cope with this damage by turning on the FtsH2-dependent PSII repair cycle, the FtsH2-deficient mutant is highly sensitive and loses PSII activity at millimolar concentration of ammonia. Ammonia-triggered PSII destruction is light dependent and occurs already at low photon fluence rates. Experiments with monochromatic light showed that ammonia-promoted PSII photoinhibition is executed by wavebands known to directly destroy the manganese cluster in the PSII oxygen-evolving complex, suggesting that the oxygen-evolving complex may be a direct target for ammonia toxicity. PMID:18322144

  1. 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

  2. Regulation and sequence of the Synechococcus sp. strain PCC 7942 groESL operon, encoding a cyanobacterial chaperonin.

    PubMed Central

    Webb, R; Reddy, K J; Sherman, L A

    1990-01-01

    The molecular chaperonins such as GroEL are now widely regarded as essential components for the stabilization of integral membrane or secretory proteins before membrane insertion or translocation, as well as for the assembly of macromolecular complexes such as ribulose bisphosphate carboxylase-oxygenase. The groESL operon of Synechococcus sp. strain PCC 7942 was cloned as two independent lacZ-groEL translational fusions by immunoscreening a lambda ZAP genomic expression library and then sequenced. The derived amino acid sequences of the GroES and GroEL proteins demonstrated very high levels of amino acid identity with cognate chaperonins from bacteria and chloroplasts. The bicistronic 2.4-kilobase transcript from this operon, barely detectable in RNA preparations from cells grown at 30 degrees C, accumulated approximately 120-fold in preparations from cells grown for 20 min at 45 degrees C. Under these conditions, GroEL protein accumulated to 10-fold-higher levels. Primer extension analysis was used to identify a cyanobacterial heat shock promoter located at -81 base pairs from the groES initiation codon. The transcriptional -10 and -35 sequences differ slightly from Escherichia coli consensus heat shock promoter sequences. Images PMID:1975581

  3. Transcriptional activation of NtcA-dependent promoters of Synechococcus sp. PCC 7942 by 2-oxoglutarate in vitro

    PubMed Central

    Tanigawa, Ryohei; Shirokane, Masao; Maeda, Shin-ichi; Omata, Tatsuo; Tanaka, Kan; Takahashi, Hideo

    2002-01-01

    The transcription factor NtcA is a global regulator of nitrogen homeostasis in cyanobacteria. It thus positively regulates the expression of genes related to nitrogen assimilation such as glnA (which encodes glutamine synthetase) and ntcA itself in response to nitrogen shortage or depletion. The binding of NtcA to the glnA and ntcA promoters of Synechococcus sp. PCC 7942 in vitro now has been shown to be enhanced by 2-oxoglutarate. In vitro analysis of gene transcription also revealed that the interaction of NtcA with its promoter element was not sufficient for activation of transcription, and 2-oxoglutarate was required for transcriptional initiation by NtcA. Given that the intracellular concentration of 2-oxoglutarate is inversely related to nitrogen availability, it is proposed that this metabolite functions as a signaling molecule that transmits information on cellular nitrogen status to NtcA and thereby regulates the transcription of genes related to nitrogen assimilation in cyanobacteria. PMID:11917135

  4. Dynamics of Photosynthesis in a Glycogen-Deficient glgC Mutant of Synechococcus sp. Strain PCC 7002

    PubMed Central

    Jackson, Simon A.; Eaton-Rye, Julian J.; Bryant, Donald A.; Posewitz, Matthew C.

    2015-01-01

    Cyanobacterial glycogen-deficient mutants display impaired degradation of light-harvesting phycobilisomes under nitrogen-limiting growth conditions and secrete a suite of organic acids as a putative reductant-spilling mechanism. This genetic background, therefore, represents an important platform to better understand the complex relationships between light harvesting, photosynthetic electron transport, carbon fixation, and carbon/nitrogen metabolisms. In this study, we conducted a comprehensive analysis of the dynamics of photosynthesis as a function of reductant sink manipulation in a glycogen-deficient glgC mutant of Synechococcus sp. strain PCC 7002. The glgC mutant showed increased susceptibility to photoinhibition during the initial phase of nitrogen deprivation. However, after extended periods of nitrogen deprivation, glgC mutant cells maintained higher levels of photosynthetic activity than the wild type, supporting continuous organic acid secretion in the absence of biomass accumulation. In contrast to the wild type, the glgC mutant maintained efficient energy transfer from phycobilisomes to photosystem II (PSII) reaction centers, had an elevated PSII/PSI ratio as a result of reduced PSII degradation, and retained a nitrogen-replete-type ultrastructure, including an extensive thylakoid membrane network, after prolonged nitrogen deprivation. Together, these results suggest that multiple global signals for nitrogen deprivation are not activated in the glgC mutant, allowing the maintenance of active photosynthetic complexes under conditions where photosynthesis would normally be abolished. PMID:26150450

  5. Role of NtcB in activation of nitrate assimilation genes in the cyanobacterium Synechocystis sp. strain PCC 6803.

    PubMed

    Aichi, M; Takatani, N; Omata, T

    2001-10-01

    In Synechocystis sp. strain PCC 6803, the genes encoding the proteins involved in nitrate assimilation are organized into two transcription units, nrtABCD-narB and nirA, the expression of which was repressed by ammonium and induced by inhibition of ammonium assimilation, suggesting involvement of NtcA in the transcriptional regulation. Under inducing conditions, expression of the two transcription units was enhanced by nitrite, suggesting regulation by NtcB, the nitrite-responsive transcriptional enhancer we previously identified in Synechococcus sp. strain PCC 7942. The slr0395 gene, which encodes a protein 47% identical to Synechococcus NtcB, was identified as the Synechocystis ntcB gene, on the basis of the inability of an slr0395 mutant to rapidly accumulate the transcripts of the nitrate assimilation genes upon induction and to respond to nitrite. While Synechococcus NtcB strictly requires nitrite for its action, Synechocystis NtcB enhanced transcription significantly even in the absence of nitrite. Whereas the Synechococcus ntcB mutant expresses the nitrate assimilation genes to a significant level in an NtcA-dependent manner, the Synechocystis ntcB mutant showed only low-level expression of the nitrate assimilation genes, indicating that NtcA by itself cannot efficiently promote expression of these genes in Synechocystis. Activities of the nitrate assimilation enzymes in the Synechocystis ntcB mutant were consequently low, being 40 to 50% of the wild-type level, and the cells grew on nitrate at a rate approximately threefold lower than that of the wild-type strain. These results showed that the contribution of NtcB to the expression of nitrate assimilation capability varies considerably among different strains of cyanobacteria.

  6. Role of NtcB in Activation of Nitrate Assimilation Genes in the Cyanobacterium Synechocystis sp. Strain PCC 6803

    PubMed Central

    Aichi, Makiko; Takatani, Nobuyuki; Omata, Tatsuo

    2001-01-01

    In Synechocystis sp. strain PCC 6803, the genes encoding the proteins involved in nitrate assimilation are organized into two transcription units, nrtABCD-narB and nirA, the expression of which was repressed by ammonium and induced by inhibition of ammonium assimilation, suggesting involvement of NtcA in the transcriptional regulation. Under inducing conditions, expression of the two transcription units was enhanced by nitrite, suggesting regulation by NtcB, the nitrite-responsive transcriptional enhancer we previously identified in Synechococcus sp. strain PCC 7942. The slr0395 gene, which encodes a protein 47% identical to Synechococcus NtcB, was identified as the Synechocystis ntcB gene, on the basis of the inability of an slr0395 mutant to rapidly accumulate the transcripts of the nitrate assimilation genes upon induction and to respond to nitrite. While Synechococcus NtcB strictly requires nitrite for its action, Synechocystis NtcB enhanced transcription significantly even in the absence of nitrite. Whereas the Synechococcus ntcB mutant expresses the nitrate assimilation genes to a significant level in an NtcA-dependent manner, the Synechocystis ntcB mutant showed only low-level expression of the nitrate assimilation genes, indicating that NtcA by itself cannot efficiently promote expression of these genes in Synechocystis. Activities of the nitrate assimilation enzymes in the Synechocystis ntcB mutant were consequently low, being 40 to 50% of the wild-type level, and the cells grew on nitrate at a rate approximately threefold lower than that of the wild-type strain. These results showed that the contribution of NtcB to the expression of nitrate assimilation capability varies considerably among different strains of cyanobacteria. PMID:11566981

  7. Ultrafast primary processes in photosystem I of the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed Central

    Savikhin, S; Xu, W; Soukoulis, V; Chitnis, P R; Struve, W S

    1999-01-01

    Ultrafast primary processes in the trimeric photosystem I core antenna-reaction center complex of the cyanobacterium Synechocystis sp. PCC 6803 have been examined in pump-probe experiments with approximately 100 fs resolution. A global analysis of two-color profiles, excited at 660 nm and probed at 5 nm intervals from 650 to 730 nm, reveals 430 fs kinetics for spectral equilibration among bulk antenna chlorophylls. At least two lifetime components (2.0 and 6.5 ps in our analysis) are required to describe equilibration of bulk chlorophylls with far red-absorbing chlorophylls (>700 nm). Trapping at P700 occurs with 24-ps kinetics. The multiphasic bulk left arrow over right arrow red equilibration kinetics are intriguing, because prior steady-state spectral studies have suggested that the core antenna in Synechocystis sp. contains only one red-absorbing chlorophyll species (C708). The disperse kinetics may arise from inhomogeneous broadening in C708. The one-color optical anisotropy at 680 nm (near the red edge of the bulk antenna) decays with 590 fs kinetics; the corresponding anisotropy at 710 nm shows approximately 3.1 ps kinetics. The latter may signal equilibration among symmetry-equivalent red chlorophylls, bound to different monomers within trimeric photosystem I. PMID:10354453

  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. 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.

  10. Ultradian metabolic rhythm in the diazotrophic cyanobacterium Cyanothece sp. ATCC 51142.

    PubMed

    Červený, Jan; Sinetova, Maria A; Valledor, Luis; Sherman, Louis A; Nedbal, Ladislav

    2013-08-06

    The unicellular cyanobacterium Cyanothece sp. American Type Culture Collection (ATCC) 51142 is capable of performing oxygenic photosynthesis during the day and microoxic nitrogen fixation at night. These mutually exclusive processes are possible only by temporal separation by circadian clock or another cellular program. We report identification of a temperature-dependent ultradian metabolic rhythm that controls the alternating oxygenic and microoxic processes of Cyanothece sp. ATCC 51142 under continuous high irradiance and in high CO2 concentration. During the oxygenic photosynthesis phase, nitrate deficiency limited protein synthesis and CO2 assimilation was directed toward glycogen synthesis. The carbohydrate accumulation reduced overexcitation of the photosynthetic reactions until a respiration burst initiated a transition to microoxic N2 fixation. In contrast to the circadian clock, this ultradian period is strongly temperature-dependent: 17 h at 27 °C, which continuously decreased to 10 h at 39 °C. The cycle was expressed by an oscillatory modulation of net O2 evolution, CO2 uptake, pH, fluorescence emission, glycogen content, cell division, and culture optical density. The corresponding ultradian modulation was also observed in the transcription of nitrogenase-related nifB and nifH genes and in nitrogenase activities. We propose that the control by the newly identified metabolic cycle adds another rhythmic component to the circadian clock that reflects the true metabolic state depending on the actual temperature, irradiance, and CO2 availability.

  11. An experimentally anchored map of transcriptional start sites in the model cyanobacterium Synechocystis sp. PCC6803

    PubMed Central

    Mitschke, Jan; Georg, Jens; Scholz, Ingeborg; Sharma, Cynthia M.; Dienst, Dennis; Bantscheff, Jens; Voß, Björn; Steglich, Claudia; Wilde, Annegret; Vogel, Jörg; Hess, Wolfgang R.

    2011-01-01

    There has been an increasing interest in cyanobacteria because these photosynthetic organisms convert solar energy into biomass and because of their potential for the production of biofuels. However, the exploitation of cyanobacteria for bioengineering requires knowledge of their transcriptional organization. Using differential RNA sequencing, we have established a genome-wide map of 3,527 transcriptional start sites (TSS) of the model organism Synechocystis sp. PCC6803. One-third of all TSS were located upstream of an annotated gene; another third were on the reverse complementary strand of 866 genes, suggesting massive antisense transcription. Orphan TSS located in intergenic regions led us to predict 314 noncoding RNAs (ncRNAs). Complementary microarray-based RNA profiling verified a high number of noncoding transcripts and identified strong ncRNA regulations. Thus, ∼64% of all TSS give rise to antisense or ncRNAs in a genome that is to 87% protein coding. Our data enhance the information on promoters by a factor of 40, suggest the existence of additional small peptide-encoding mRNAs, and provide corrected 5′ annotations for many genes of this cyanobacterium. The global TSS map will facilitate the use of Synechocystis sp. PCC6803 as a model organism for further research on photosynthesis and energy research. PMID:21245330

  12. Merocyclophanes C and D from the Cultured Freshwater Cyanobacterium Nostoc sp. (UIC 10110).

    PubMed

    May, Daniel S; Chen, Wei-Lun; Lantvit, Daniel D; Zhang, Xiaoli; Krunic, Aleksej; Burdette, Joanna E; Eustaquio, Alessandra; Orjala, Jimmy

    2017-04-28

    Merocyclophanes C and D (1 and 2) were isolated from the cell extract of the cultured cyanobacterium UIC 10110. The structures were determined by one-dimensional nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectrometry and confirmed by 2D NMR techniques. The absolute configurations were determined using electronic circular dichroism spectroscopy. Merocyclophanes C and D represent the first known analogues of the merocyclophane core structure, a recently discovered scaffold of [7,7] paracyclophanes characterized by an α-branched methyl at C-1/C-14; 1 and 2 showed antiproliferative activity against the MDA-MB-435 cell line with IC50 values of 1.6 and 0.9 μM, respectively. Partial 16S analysis determined UIC 10110 to be a Nostoc sp., and it was found to clade with UIC 10062 Nostoc sp., the only other strain known to produce merocyclophanes. The genome of UIC 10110 was sequenced, and a biosynthetic gene cluster was identified that is proposed to encode type I and type III polyketide synthases that are potentially responsible for production of the merocyclophanes; however, further experiments will be required to verify the true function of the gene cluster. The gene cluster provides a genetic basis for the observed structural differences of the [7,7] paracyclophane core structures.

  13. 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.

  14. Transcription and Regulation of the Bidirectional Hydrogenase in the Cyanobacterium Nostoc sp. Strain PCC 7120▿

    PubMed Central

    Sjöholm, Johannes; Oliveira, Paulo; Lindblad, Peter

    2007-01-01

    The filamentous, heterocystous cyanobacterium Nostoc sp. strain PCC 7120 (Anabaena sp. strain PCC 7120) possesses an uptake hydrogenase and a bidirectional enzyme, the latter being capable of catalyzing both H2 production and evolution. The completely sequenced genome of Nostoc sp. strain PCC 7120 reveals that the five structural genes encoding the bidirectional hydrogenase (hoxEFUYH) are separated in two clusters at a distance of approximately 8.8 kb. The transcription of the hox genes was examined under nitrogen-fixing conditions, and the results demonstrate that the cluster containing hoxE and hoxF can be transcribed as one polycistronic unit together with the open reading frame alr0750. The second cluster, containing hoxU, hoxY, and hoxH, is transcribed together with alr0763 and alr0765, located between the hox genes. Moreover, alr0760 and alr0761 form an additional larger operon. Nevertheless, Northern blot hybridizations revealed a rather complex transcription pattern in which the different hox genes are expressed differently. Transcriptional start points (TSPs) were identified 66 and 57 bp upstream from the start codon of alr0750 and hoxU, respectively. The transcriptions of the two clusters containing the hox genes are both induced under anaerobic conditions concomitantly with the induction of a higher level of hydrogenase activity. An additional TSP, within the annotated alr0760, 244 bp downstream from the suggested translation start codon, was identified. Electrophoretic mobility shift assays with purified LexA from Nostoc sp. strain PCC 7120 demonstrated specific interactions between the transcriptional regulator and both hox promoter regions. However, when LexA from Synechocystis sp. strain PCC 6803 was used, the purified protein interacted only with the promoter region of the alr0750-hoxE-hoxF operon. A search of the whole Nostoc sp. strain PCC 7120 genome demonstrated the presence of 216 putative LexA binding sites in total, including recA and rec

  15. The Putative Eukaryote-Like O-GlcNAc Transferase of the Cyanobacterium Synechococcus elongatus PCC 7942 Hydrolyzes UDP-GlcNAc and Is Involved in Multiple Cellular Processes

    PubMed Central

    Sokol, Kerry A.

    2014-01-01

    The posttranslational addition of a single O-linked β-N-acetylglucosamine (O-GlcNAc) to serine or threonine residues regulates numerous metazoan cellular processes. The enzyme responsible for this modification, O-GlcNAc transferase (OGT), is conserved among a wide variety of organisms and is critical for the viability of many eukaryotes. Although OGTs with domain structures similar to those of eukaryotic OGTs are predicted for many bacterial species, the cellular roles of these OGTs are unknown. We have identified a putative OGT in the cyanobacterium Synechococcus elongatus PCC 7942 that shows active-site homology and similar domain structure to eukaryotic OGTs. An OGT deletion mutant was created and found to exhibit several phenotypes. Without agitation, mutant cells aggregate and settle out of the medium. The mutant cells have higher free inorganic phosphate levels, wider thylakoid lumen, and differential accumulation of electron-dense inclusion bodies. These phenotypes are rescued by reintroduction of the wild-type OGT but are not fully rescued by OGTs with single amino acid substitutions corresponding to mutations that reduce eukaryotic OGT activity. S. elongatus OGT purified from Escherichia coli hydrolyzed the sugar donor, UDP-GlcNAc, while the mutant OGTs that did not fully rescue the deletion mutant phenotypes had reduced or no activity. These results suggest that bacterial eukaryote-like OGTs, like their eukaryotic counterparts, influence multiple processes. PMID:25384478

  16. Natural and Synthetic Variants of the Tricarboxylic Acid Cycle in Cyanobacteria: Introduction of the GABA Shunt into Synechococcus sp. PCC 7002

    PubMed Central

    Zhang, Shuyi; Qian, Xiao; Chang, Shannon; Dismukes, G. C.; Bryant, Donald A.

    2016-01-01

    For nearly half a century, it was believed that cyanobacteria had an incomplete tricarboxylic acid (TCA) cycle, because 2-oxoglutarate dehydrogenase (2-OGDH) was missing. Recently, a bypass route via succinic semialdehyde (SSA), which utilizes 2-oxoglutarate decarboxylase (OgdA) and succinic semialdehyde dehydrogenase (SsaD) to convert 2-oxoglutarate (2-OG) into succinate, was identified, thus completing the TCA cycle in most cyanobacteria. In addition to the recently characterized glyoxylate shunt that occurs in a few of cyanobacteria, the existence of a third variant of the TCA cycle connecting these metabolites, the γ-aminobutyric acid (GABA) shunt, was considered to be ambiguous because the GABA aminotransferase is missing in many cyanobacteria. In this study we isolated and biochemically characterized the enzymes of the GABA shunt. We show that N-acetylornithine aminotransferase (ArgD) can function as a GABA aminotransferase and that, together with glutamate decarboxylase (GadA), it can complete a functional GABA shunt. To prove the connectivity between the OgdA/SsaD bypass and the GABA shunt, the gadA gene from Synechocystis sp. PCC 6803 was heterologously expressed in Synechococcus sp. PCC 7002, which naturally lacks this enzyme. Metabolite profiling of seven Synechococcus sp. PCC 7002 mutant strains related to these two routes to succinate were investigated and proved the functional connectivity. Metabolite profiling also indicated that, compared to the OgdA/SsaD shunt, the GABA shunt was less efficient in converting 2-OG to SSA in Synechococcus sp. PCC 7002. The metabolic profiling study of these two TCA cycle variants provides new insights into carbon metabolism as well as evolution of the TCA cycle in cyanobacteria. PMID:28018308

  17. Metabolic engineering of Synechococcus sp. PCC 7002 to produce poly-3-hydroxybutyrate and poly-3-hydroxybutyrate-co-4-hydroxybutyrate.

    PubMed

    Zhang, Shuyi; Liu, Yang; Bryant, Donald A

    2015-11-01

    Cyanobacteria are an important group of photoautotrophic bacteria that have been engineered and used to produce a wide range of biomaterials and biofuels, which are usually derived from important intermediates of the central metabolic pathways. In this study, the production of poly-3-hydroxybutyrate and poly-3-hydroxybutyrate-co-4-hydroxybutyrate in cyanobacteria was studied, and metabolic engineering strategies to improve the yields were also investigated. The genes involved in the biosynthetic pathway for poly-3-hydroxybutyrate from Chlorogloeopsis fritschii PCC 9212 were introduced into Synechococcus sp. PCC 7002, and the resulting strain was able to accumulate 2.77% of total cell dry weight as poly-3-hydroxybutyrate. When the ccmR gene was deleted in this strain, the yield of poly-3-hydroxybutyrate increased to 3.97% of total cell dry weight. A biosynthetic pathway for the production of 4-hydroxybutyryl-CoA was also constructed and introduced into the poly-3-hydroxybutyrate-producing strain. The resulting strain was able to produce ~4.5% of total cell dry weight as poly-3-hydroxybutyrate-co-4-hydroxybutyrate, in which 4-hydroxybutyrate accounted for ~12% of the co-polymer. These results demonstrate that poly-3-hydroxybutyrate-co-4-hydroxybutyrate can be produced in cyanobacteria and confirm that succinic semialdehyde is an important TCA cycle metabolite in cyanobacteria. This study also demonstrates the potential for future metabolic engineering in cyanobacteria that is based on recently discovered metabolites. Copyright © 2015 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  18. Regulation of ntcA Expression and Nitrite Uptake in the Marine Synechococcus sp. Strain WH 7803

    PubMed Central

    Lindell, Debbie; Padan, Etana; Post, Anton F.

    1998-01-01

    NtcA is a transcriptional activator involved in global nitrogen control in cyanobacteria. In the absence of ammonium it regulates the transcription of a series of genes encoding proteins required for the uptake and assimilation of alternative nitrogen sources (I. Luque, E. Flores, and A. Herrero, EMBO J. 13:2862–2869, 1994). ntcA, present in a single copy in the marine Synechococcus sp. strain WH 7803, was cloned and sequenced. The putative amino acid sequence shows a high degree of identity to NtcA from freshwater cyanobacteria in two functional domains. The expression of ntcA was negatively regulated by ammonium from a putative transcription start point located downstream of an NtcA consensus recognition sequence. Addition of either rifampin or ammonium led to a rapid decline in ntcA transcript levels with half-lives of less than 2 min in both cases. Nitrate-grown cells showed high ntcA transcript levels, as well as the capacity for active nitrite uptake. However, ammonium-grown cells showed low levels of the ntcA transcript and did not utilize nitrite. The addition of ammonium to nitrite uptake-active cells resulted in a gradual decline in the rate of uptake over a 24-h period. Active nitrite uptake was not induced in cells transferred to medium lacking a nitrogen source despite evidence of elevated expression of ntcA, indicating that ntcA expression is not sufficient for uptake capacity to develop. Nitrate and nitrite addition led to the development of nitrite uptake, whereas the addition of leucine did not. Furthermore, nitrite addition triggered the de novo protein synthesis required for uptake capacity to develop. These data suggest that nitrite and nitrate act as specific inducers for the synthesis of proteins required for nitrite uptake. PMID:9537388

  19. Structural Elucidation and Molecular Docking of a Novel Antibiotic Compound from Cyanobacterium Nostoc sp. MGL001.

    PubMed

    Niveshika; Verma, Ekta; Mishra, Arun K; Singh, Angad K; Singh, Vinay K

    2016-01-01

    Cyanobacteria are rich source of array of bioactive compounds. The present study reports a novel antibacterial bioactive compound purified from cyanobacterium Nostoc sp. MGL001 using various chromatographic techniques viz. thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). Further characterization was done using electrospray ionization mass spectroscopy (ESIMS) and nuclear magnetic resonance (NMR) and predicted structure of bioactive compound was 9-Ethyliminomethyl-12-(morpholin - 4 - ylmethoxy) -5, 8, 13, 16-tetraaza-hexacene - 2, 3 dicarboxylic acid (EMTAHDCA). Structure of EMTAHDCA clearly indicated that it is a novel compound that was not reported in literature or natural product database. The compound exhibited growth inhibiting effects mainly against the gram negative bacterial strains and produced maximum zone of inhibition at 150 μg/mL concentration. The compound was evaluated through in silico studies for its ability to bind 30S ribosomal fragment (PDB ID: 1YRJ, 1MWL, 1J7T, and 1LC4) and OmpF porin protein (4GCP, 4GCQ, and 4GCS) which are the common targets of various antibiotic drugs. Comparative molecular docking study revealed that EMTAHDCA has strong binding affinity for these selected targets in comparison to a number of most commonly used antibiotics. The ability of EMTAHDCA to bind the active sites on the proteins and 30S ribosomal fragments where the antibiotic drugs generally bind indicated that it is functionally similar to the commercially available drugs.

  20. 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

  1. Silanimonas algicola sp. nov., isolated from laboratory culture of a bloom-forming cyanobacterium, Microcystis.

    PubMed

    Chun, Seong-Jun; Cui, Yingshun; Ko, So-Ra; Lee, Hyung-Gwan; Oh, Hee-Mock; Ahn, Chi-Yong

    2017-09-01

    A Gram-stain-negative, aerobic, rod-shaped and motile bacterium, designated M23T, was isolated from a laboratory culture of a bloom-forming cyanobacterium, Microcystis, which was isolated from a eutrophic lake in Korea. The strain grew optimally without NaCl and at 25-30 °C on R2A agar medium. Phylogenetic analysis based on 16S rRNA gene sequences positioned the novel strain among the genus Silanimonas, with the highest similarity to Silanimonas lenta DSM 16282T (98.5 %). DNA-DNA relatedness between strain M23T and the closely related species in the genus Silanimonas was <30 %. Strain M23T contained iso-C15 : 0, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and iso-C16 : 0 as major fatty acids and ubiquinone-8 (Q-8) as the major quinone. Strain M23T contained diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylmethylethanolamine as major polar lipids. The DNA G+C content of strain M23T was 69.6 mol%. On the basis of the genotypic, chemotaxonomic and phenotypic data, strain M23T represents a novel species in the genus Silanimonas, for which the name Silanimonas algicola sp. nov. is proposed. The type strain is M23T (=KCTC 52219T=JCM 31889T).

  2. Changes in photosynthesis and pigmentation in an agp deletion mutant of the cyanobacterium Synechocystis sp.

    PubMed

    Miao, Xiaoling; Wu, Qingyu; Wu, Guifang; Zhao, Nanming

    2003-03-01

    The agp gene encoding ADP-glucose pyrophosphorylase is involved in cyanobacterial glycogen synthesis. By in vitro DNA recombination technology, agp deletion mutant (agp-) of cyanobacterium Synechocystis sp. PCC 6803 was constructed. This mutation led to a complete absence of glycogen biosynthesis. As compared with WT (wild type), a 60% decrease in ratio of the c-phycocyanine/chlorophyll a and no significant change in the carotenoid/chlorophyll a were observed in agp- cells. The agp- mutant had 38% less photosynthetic capacity when grown in light over 600 micromol m(-2) s(-1). Under lower light intensity, the final biomass of the mutant strain was only 1.1 times of that of the WT strain under mixotrophic condition after 6 d culture. Under higher light intensity, however, the final biomass of the WT strain under mixotrophic conditions was 3 times that of the mutant strain after 6 d culture and 1.5 times under photoautotrophic conditions. The results indicate that there is a minimum requirement for glycogen synthesis for normal growth and development in cyanobacteria.

  3. Structural Elucidation and Molecular Docking of a Novel Antibiotic Compound from Cyanobacterium Nostoc sp. MGL001

    PubMed Central

    Niveshika; Verma, Ekta; Mishra, Arun K.; Singh, Angad K.; Singh, Vinay K.

    2016-01-01

    Cyanobacteria are rich source of array of bioactive compounds. The present study reports a novel antibacterial bioactive compound purified from cyanobacterium Nostoc sp. MGL001 using various chromatographic techniques viz. thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). Further characterization was done using electrospray ionization mass spectroscopy (ESIMS) and nuclear magnetic resonance (NMR) and predicted structure of bioactive compound was 9-Ethyliminomethyl-12-(morpholin - 4 - ylmethoxy) -5, 8, 13, 16–tetraaza–hexacene - 2, 3 dicarboxylic acid (EMTAHDCA). Structure of EMTAHDCA clearly indicated that it is a novel compound that was not reported in literature or natural product database. The compound exhibited growth inhibiting effects mainly against the gram negative bacterial strains and produced maximum zone of inhibition at 150 μg/mL concentration. The compound was evaluated through in silico studies for its ability to bind 30S ribosomal fragment (PDB ID: 1YRJ, 1MWL, 1J7T, and 1LC4) and OmpF porin protein (4GCP, 4GCQ, and 4GCS) which are the common targets of various antibiotic drugs. Comparative molecular docking study revealed that EMTAHDCA has strong binding affinity for these selected targets in comparison to a number of most commonly used antibiotics. The ability of EMTAHDCA to bind the active sites on the proteins and 30S ribosomal fragments where the antibiotic drugs generally bind indicated that it is functionally similar to the commercially available drugs. PMID:27965634

  4. 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

  5. Near-UV cyanobacteriochrome signaling system elicits negative phototaxis in the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Song, Ji-Young; Cho, Hye Sun; Cho, Jung-Il; Jeon, Jong-Seong; Lagarias, J Clark; Park, Youn-Il

    2011-06-28

    Positive phototaxis systems have been well studied in bacteria; however, the photoreceptor(s) and their downstream signaling components that are responsible for negative phototaxis are poorly understood. Negative phototaxis sensory systems are important for cyanobacteria, oxygenic photosynthetic organisms that must contend with reactive oxygen species generated by an abundance of pigment photosensitizers. The unicellular cyanobacterium Synechocystis sp. PCC6803 exhibits type IV pilus-dependent negative phototaxis in response to unidirectional UV-A illumination. Using a reverse genetic approach, together with biochemical, molecular genetic, and RNA expression profiling analyses, we show that the cyanobacteriochrome locus (slr1212/uirS) of Synechocystis and two adjacent response regulator loci (slr1213/uirR and the PatA-type regulator slr1214/lsiR) encode a UV-A-activated signaling system that is required for negative phototaxis. We propose that UirS, which is membrane-associated via its ETR1 domain, functions as a UV-A photosensor directing expression of lsiR via release of bound UirR, which targets the lsiR promoter. Constitutive expression of LsiR induces negative phototaxis under conditions that normally promote positive phototaxis. Also induced by other stresses, LsiR thus integrates light inputs from multiple photosensors to determine the direction of movement.

  6. Near-UV cyanobacteriochrome signaling system elicits negative phototaxis in the cyanobacterium Synechocystis sp. PCC 6803

    PubMed Central

    Song, Ji-Young; Cho, Hye Sun; Cho, Jung-Il; Jeon, Jong-Seong; Lagarias, J. Clark; Park, Youn-Il

    2011-01-01

    Positive phototaxis systems have been well studied in bacteria; however, the photoreceptor(s) and their downstream signaling components that are responsible for negative phototaxis are poorly understood. Negative phototaxis sensory systems are important for cyanobacteria, oxygenic photosynthetic organisms that must contend with reactive oxygen species generated by an abundance of pigment photosensitizers. The unicellular cyanobacterium Synechocystis sp. PCC6803 exhibits type IV pilus-dependent negative phototaxis in response to unidirectional UV-A illumination. Using a reverse genetic approach, together with biochemical, molecular genetic, and RNA expression profiling analyses, we show that the cyanobacteriochrome locus (slr1212/uirS) of Synechocystis and two adjacent response regulator loci (slr1213/uirR and the PatA-type regulator slr1214/lsiR) encode a UV-A–activated signaling system that is required for negative phototaxis. We propose that UirS, which is membrane-associated via its ETR1 domain, functions as a UV-A photosensor directing expression of lsiR via release of bound UirR, which targets the lsiR promoter. Constitutive expression of LsiR induces negative phototaxis under conditions that normally promote positive phototaxis. Also induced by other stresses, LsiR thus integrates light inputs from multiple photosensors to determine the direction of movement. PMID:21670284

  7. 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.

  8. Functional Diversity of Transcriptional Regulators in the Cyanobacterium Synechocystis sp. PCC 6803

    PubMed Central

    Shi, Mengliang; Zhang, Xiaoqing; Pei, Guangsheng; Chen, Lei; Zhang, Weiwen

    2017-01-01

    Functions of transcriptional regulators (TRs) are still poorly understood in the model cyanobacterium Synechocystis sp. PCC 6803. To address the issue, we constructed knockout mutants for 32 putative TR-encoding genes of Synechocystis, and comparatively analyzed their phenotypes under autotrophic growth condition and metabolic profiles using liquid chromatography-mass spectrometry-based metabolomics. The results showed that only four mutants of TR genes, sll1872 (lytR), slr0741 (phoU), slr0395 (ntcB), and slr1871 (pirR), showed differential growth patterns in BG11 medium when compared with the wild type; however, in spite of no growth difference observed for the remaining TR mutants, metabolomic profiling showed that they were different at the metabolite level, suggesting significant functional diversity of TRs in Synechocystis. In addition, an integrative metabolomic and gene families’ analysis of all TR mutants led to the identification of five pairs of TR genes that each shared close relationship in both gene families and metabolomic clustering trees, suggesting possible conserved functions of these TRs during evolution. Moreover, more than a dozen pairs of TR genes with different origin and evolution were found with similar metabolomic profiles, suggesting a possible functional convergence of the TRs during genome evolution. Finally, a protein–protein network analysis was performed to predict regulatory targets of TRs, allowing inference of possible regulatory gene targets for 4 out of five pairs of TRs. This study provided new insights into the regulatory functions and evolution of TR genes in Synechocystis. PMID:28270809

  9. 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

  10. A model of cyclic transcriptomic behavior in the cyanobacterium Cyanothece sp. ATCC 51142.

    PubMed

    McDermott, Jason E; Oehmen, Christopher S; McCue, Lee Ann; Hill, Eric; Choi, Daniel M; Stöckel, Jana; Liberton, Michelle; Pakrasi, Himadri B; Sherman, Louis A

    2011-08-01

    Systems biology attempts to reconcile large amounts of disparate data with existing knowledge to provide models of functioning biological systems. The cyanobacterium Cyanothece sp. ATCC 51142 is an excellent candidate for such systems biology studies because: (i) it displays tight functional regulation between photosynthesis and nitrogen fixation; (ii) it has robust cyclic patterns at the genetic, protein and metabolomic levels; and (iii) it has potential applications for bioenergy production and carbon sequestration. We have represented the transcriptomic data from Cyanothece 51142 under diurnal light/dark cycles as a high-level functional abstraction and describe development of a predictive in silico model of diurnal and circadian behavior in terms of regulatory and metabolic processes in this organism. We show that incorporating network topology into the model improves performance in terms of our ability to explain the behavior of the system under new conditions. The model presented robustly describes transcriptomic behavior of Cyanothece 51142 under different cyclic and non-cyclic growth conditions, and represents a significant advance in the understanding of gene regulation in this important organism.

  11. Refolding and enzyme kinetic studies on the ferrochelatase of the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Storm, Patrik; Tibiletti, Tania; Hall, Michael; Funk, Christiane

    2013-01-01

    Heme is a cofactor for proteins participating in many important cellular processes, including respiration, oxygen metabolism and oxygen binding. The key enzyme in the heme biosynthesis pathway is ferrochelatase (protohaem ferrolyase, EC 4.99.1.1), which catalyzes the insertion of ferrous iron into protoporphyrin IX. In higher plants, the ferrochelatase enzyme is localized not only in mitochondria, but also in chloroplasts. The plastidic type II ferrochelatase contains a C-terminal chlorophyll a/b (CAB) motif, a conserved hydrophobic stretch homologous to the CAB domain of plant light harvesting proteins and light-harvesting like proteins. This type II ferrochelatase, found in all photosynthetic organisms, is presumed to have evolved from the cyanobacterial ferrochelatase. Here we describe a detailed enzymological study on recombinant, refolded and functionally active type II ferrochelatase (FeCh) from the cyanobacterium Synechocystis sp. PCC 6803. A protocol was developed for the functional refolding and purification of the recombinant enzyme from inclusion bodies, without truncation products or soluble aggregates. The refolded FeCh is active in its monomeric form, however, addition of an N-terminal His(6)-tag has significant effects on its enzyme kinetics. Strikingly, removal of the C-terminal CAB-domain led to a greatly increased turnover number, k(cat), compared to the full length protein. While pigments isolated from photosynthetic membranes decrease the activity of FeCh, direct pigment binding to the CAB domain of FeCh was not evident.

  12. Anti-MRSA-acting carbamidocyclophanes H-L from the Vietnamese cyanobacterium Nostoc sp. CAVN2.

    PubMed

    Preisitsch, Michael; Harmrolfs, Kirsten; Pham, Hang T L; Heiden, Stefan E; Füssel, Anna; Wiesner, Christoph; Pretsch, Alexander; Swiatecka-Hagenbruch, Monika; Niedermeyer, Timo H J; Müller, Rolf; Mundt, Sabine

    2015-03-01

    The methanol extract of the Vietnamese freshwater cyanobacterium Nostoc sp. CAVN2 exhibited cytotoxic effects against MCF-7 and 5637 cancer cell lines as well as against nontumorigenic FL and HaCaT cells and was active against methicillin-resistant Staphylococcus aureus (MRSA) and Streptococcus pneumoniae. High-resolution mass spectrometric analysis indicated the presence of over 60 putative cyclophane-like compounds in an antimicrobially active methanol extract fraction. A paracyclophanes-focusing extraction and separation methodology led to the isolation of 5 new carbamidocyclophanes (1-5) and 11 known paracyclophanes (6-16). The structures and their stereochemical configurations were elucidated by a combination of spectrometric and spectroscopic methods including HRMS, 1D and 2D NMR analyses and detailed comparative CD analysis. The newly described monocarbamoylated [7.7]paracyclophanes (1, 2, 4 and 5) differ by a varying degree of chlorination in the side chains. Carbamidocyclophane J (3) is the very first reported carbamidocyclophane bearing a single halogenation in both butyl residues. Based on previous studies a detailed phylogenetic examination of cyclophane-producing cyanobacteria was carried out. The biological evaluation of 1-16 against various clinical pathogens highlighted a remarkable antimicrobial activity against MRSA with MICs of 0.1-1.0 μM, and indicated that the level of antibacterial activity is related to the presence of carbamoyl moieties.

  13. A novel alpha-amylase from the cyanobacterium Nostoc sp. PCC 7119.

    PubMed

    Reyes-Sosa, Francisco M; Molina-Heredia, Fernando P; De la Rosa, Miguel A

    2010-03-01

    Little information is yet available on the alpha-amylases of cyanobacteria. Here, the presence of an alpha-amylase in the cyanobacterium Nostoc sp. PCC 7119 is first demonstrated. A gene (amy1) encoding a cytoplasmic alpha-amylase (Amy1) protein has been identified, cloned, and overexpressed in Escherichia coli cells. The recombinant protein is a 56.7-kDa monomer, which has been purified to electrophoretic homogeneity by affinity chromatography. The substrate specificity and end product analyses confirm that it is a calcium-dependent alpha-amylase enzyme, which exhibits its maximum activity at 31 degrees C and at pH between 6.5 and 7.5. The Amy1 protein breaks down mainly starch, is also able to cleave glycogen and dextrin, and exhibits no activity against xylan or pullulan. So the enzyme cannot efficiently attack the maltodextrins with degrees of polymerization below that of maltooctaose. Maltotriose, maltose, and maltotetraose are the major products of the enzymatic reaction with starch as substrate. The enzyme shows a very high turnover number against soluble potato starch (3,420 +/- 270 s(-1)), as compared with other alpha-amylases reported in the literature. The high catalytic efficiency and relatively low optimum temperature of the Nostoc Amy1 protein make this previously unexplored group of cyanobacterial enzymes of great interest for further physiological studies and industrial applications.

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

    PubMed Central

    Serrano, A; Rivas, J; Losada, M

    1984-01-01

    An NADPH-glutathione reductase (EC 1.6.4.2) has been purified 6,000-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 features with respect to that isolated from non-photosynthetic organisms: (i) absolute specificity for NADPH, (ii) an alkaline optimum pH value of ca. 9.0, and (iii) strong acidic character of the protein, as estimated by column chromatofocusing. The kinetic parameters are very similar to those found for the chloroplast enzyme, but the molecular weight is lower, being comparable to that of non-photosynthetic microorganisms. A protective function, analogous to that assigned to the chloroplast enzyme, is suggested. Images PMID:6425264

  15. Refolding and Enzyme Kinetic Studies on the Ferrochelatase of the Cyanobacterium Synechocystis sp. PCC 6803

    PubMed Central

    Storm, Patrik; Tibiletti, Tania; Hall, Michael; Funk, Christiane

    2013-01-01

    Heme is a cofactor for proteins participating in many important cellular processes, including respiration, oxygen metabolism and oxygen binding. The key enzyme in the heme biosynthesis pathway is ferrochelatase (protohaem ferrolyase, EC 4.99.1.1), which catalyzes the insertion of ferrous iron into protoporphyrin IX. In higher plants, the ferrochelatase enzyme is localized not only in mitochondria, but also in chloroplasts. The plastidic type II ferrochelatase contains a C-terminal chlorophyll a/b (CAB) motif, a conserved hydrophobic stretch homologous to the CAB domain of plant light harvesting proteins and light-harvesting like proteins. This type II ferrochelatase, found in all photosynthetic organisms, is presumed to have evolved from the cyanobacterial ferrochelatase. Here we describe a detailed enzymological study on recombinant, refolded and functionally active type II ferrochelatase (FeCh) from the cyanobacterium Synechocystis sp. PCC 6803. A protocol was developed for the functional refolding and purification of the recombinant enzyme from inclusion bodies, without truncation products or soluble aggregates. The refolded FeCh is active in its monomeric form, however, addition of an N-terminal His6-tag has significant effects on its enzyme kinetics. Strikingly, removal of the C-terminal CAB-domain led to a greatly increased turnover number, kcat, compared to the full length protein. While pigments isolated from photosynthetic membranes decrease the activity of FeCh, direct pigment binding to the CAB domain of FeCh was not evident. PMID:23390541

  16. 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.

  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. 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.

  19. GABA accumulation in response to different nitrogenous compounds in unicellular cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Kanwal, Simab; Khetkorn, Wanthanee; Incharoensakdi, Aran

    2015-01-01

    GABA accumulation and glutamate decarboxylase (GAD) activity, the principal enzyme involved in GABA formation, was investigated in cyanobacterium Synechocystis sp. PCC 6803 wild-type (WT) and gad knockout mutant strains grown in medium containing different nitrogenous compounds. Nitrate was the best nitrogen source for GAD activity and GABA accumulation followed by nitrite, ammonium, and urea. An increase in the accumulation of GABA was observed in WT and mutant cells grown for 24 h in medium supplemented with 0.5 mM putrescine or spermidine with a parallel increase in GAD activity. The mutant could not accumulate GABA at all the conditions tested except when supplemented with putrescine or spermidine, where high GABA levels were observed in both WT and mutant strains. Glutamate supplementation up to 10 mM for 24 h resulted in a significant increase in both GAD activity and GABA content. Overall results suggested that optimization of nitrogen source and nitrogenous compounds supplementation was effective for the enhancement of GABA accumulation in Synechocystis.

  20. Co-production of carbonic anhydrase and phycobiliproteins by Spirulina sp. and Synechococcus nidulans.

    PubMed

    Ores, Joana da Costa; Amarante, Marina Campos Assumpção de; Kalil, Susana Juliano

    2016-11-01

    The aim of this work was to study the co-production of the carbonic anhydrase, C-phycocyanin and allophycocyanin during cyanobacteria growth. Spirulina sp. LEB 18 demonstrated a high potential for simultaneously obtaining the three products, achieving a carbonic anhydrase (CA) productivity of 0.97U/L/d and the highest C-phycocyanin (PC, 5.9μg/mL/d) and allophycocyanin (APC, 4.3μg/mL/d) productivities. In the extraction study, high extraction yields were obtained from Spirulina using an ultrasonic homogenizer (CA: 25.5U/g; PC: 90mg/g; APC: 70mg/g). From the same biomass, it was possible to obtain three biomolecules that present high industrial value.

  1. Far-red light photoacclimation (FaRLiP) in Synechococcus sp. PCC 7335: I. Regulation of FaRLiP gene expression.

    PubMed

    Ho, Ming-Yang; Gan, Fei; Shen, Gaozhong; Zhao, Chi; Bryant, Donald A

    2017-02-01

    Far-red light photoacclimation (FaRLiP) is a mechanism that allows some cyanobacteria to utilize far-red light (FRL) for oxygenic photosynthesis. During FaRLiP, cyanobacteria remodel photosystem (PS) I, PS II, and phycobilisomes while synthesizing Chl d, Chl f, and far-red-absorbing phycobiliproteins, and these changes enable these organisms to use FRL for growth. In this study, a conjugation-based genetic system was developed for Synechococcus sp. PCC 7335. Three antibiotic cassettes were successfully used to generate knockout mutations in genes in Synechococcus sp. PCC 7335, which should allow up to three gene loci to be modified in one strain. This system was used to delete the rfpA, rfpB, and rfpC genes individually, and characterization of the mutants demonstrated that these genes control the expression of the FaRLiP gene cluster in Synechococcus sp. PCC 7335. The mutant strains exhibited some surprising differences from similar mutants in other FaRLiP strains. Notably, mutations in any of the three master transcription regulatory genes led to enhanced synthesis of phycocyanin and PS II. A time-course study showed that acclimation of the photosynthetic apparatus from that produced in white light to that produced in FRL occurs very slowly over a period 12-14 days in this strain and that it is associated with a substantial reduction (~34 %) in the chlorophyll a content of the cells. This study shows that there are differences in the detailed responses of cyanobacteria to growth in FRL in spite of the obvious similarities in the organization and regulation of the FaRLiP gene cluster.

  2. Effects of a Simulated Martian UV Flux on the Cyanobacterium, Chroococcidiopsis sp. 029

    NASA Astrophysics Data System (ADS)

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

    2005-06-01

    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.

  3. 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.

  4. 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.

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

    PubMed Central

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

    1987-01-01

    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-[14C]glutamate from 2-keto-[1-14C]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 [14C]bicarbonate and L-[1-14C]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. Images PMID:2880834

  6. 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.

  7. 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.

  8. Comparative study of the different mechanisms for zinc ion stress sensing in two cyanobacterial strains, Synechococcus sp. PCC 7942 and Synechocystis sp. PCC 6803

    PubMed Central

    Morita, Eugene Hayato; Kawamoto, Satsuki; Abe, Shunnosuke; Nishiyama, Yoshitaka; Ikegami, Takahisa; Hayashi, Hidenori

    2012-01-01

    In response to an increased level of Zn2+, Synechococcus sp. PCC 7942 expresses SmtA, a metallothionein-like metal-chelating protein, while Synechocystis sp. PCC 6803 expresses ZiaA, a transporter of Zn2+. The gene expression of these proteins is regulated by repressor protein, SmtB and ZiaR, respectively. In spite of contributing to different response systems, both repressor proteins belong to the ArsR family and are highly homologous to each other. To understand the different systems responsible for dealing with excess Zn2+, we examined the cis-elements in the promoter regions of smtA and ziaA, as well as the binding affinities of recombinant SmtB and ZiaR proteins. The operator/promoter region of smtA included two palindromic sequences and that of ziaA included one. Electrophoretic mobility shift assay revealed that SmtB formed four different complexes with the operator/promoter region of smtA, whereas it formed only two different complexes with the corresponding region of ziaA. For ZiaR, the corresponding results were quite the same as those for SmtB. Furthermore, the complex formation between SmtB and operator/promoter regions is inhibited in the presence of Zn2+ at higher concentrations than 16 μM. On the other hand, the corresponding Zn2+ concentration is 128 μM. These results demonstrate that the degrees of protein-DNA complex formation between repressor proteins and the operator/promoter regions of regulated genes depend on the structures of the operator/promoter regions, and the effects of Zn2+ on the dissociation of these complexes are mainly associated with the structures of the repressors. PMID:27493526

  9. Identification and nitrogen regulation of the cyanase gene from the cyanobacteria Synechocystis sp. strain PCC 6803 and Synechococcus sp. strain PCC 7942.

    PubMed

    Harano, Y; Suzuki, I; Maeda, S; Kaneko, T; Tabata, S; Omata, T

    1997-09-01

    An open reading frame (slr0899) on the genome of Synechocystis sp. strain PCC 6803 encodes a polypeptide of 149 amino acid residues, the sequence of which is 40% identical to that of cyanase from Escherichia coli. Introduction into a cyanase-deficient E. coli strain of a plasmid-borne slr0899 resulted in expression of low but significant activity of cyanase. Targeted interruption of a homolog of slr0899 from Synechococcus sp. strain PCC 7942, encoding a protein 77% identical to that encoded by slr0899, resulted in loss of cellular cyanase activity. These results indicated that slr0899 and its homolog in the strain PCC 7942 represent the cyanobacterial cyanase gene (designated cynS). While cynS of strain PCC 6803 is tightly clustered with the four putative molybdenum cofactor biosynthesis genes located downstream, cynS of strain PCC 7942 was found to be tightly clustered with the two genes located upstream, which encode proteins similar to the subunits of the cyanobacterial nitrate-nitrite transporter. In both strains, cynS was transcribed as a part of a large transcription unit and the transcription was negatively regulated by ammonium. Cyanase activity was low in ammonium-grown cells and was induced 7- to 13-fold by inhibition of ammonium fixation or by transfer of the cells to ammonium-free media. These findings indicated that cyanase is an ammonium-repressible enzyme in cyanobacteria, the expression of which is regulated at the level of transcription. Similar to other ammonium-repressible genes in cyanobacteria, expression of cynS required NtcA, a global nitrogen regulator of cyanobacteria.

  10. The complete sequence and functional analysis of pANL, the large plasmid of the unicellular freshwater cyanobacterium Synechococcus elongatus PCC 7942.

    PubMed

    Chen, You; Holtman, C Kay; Magnuson, Roy D; Youderian, Philip A; Golden, Susan S

    2008-05-01

    Two endogenous plasmids are present in Synechococcus elongatus PCC 7942, a model organism for studying photosynthesis and circadian rhythms in cyanobacteria. The large plasmid, pANL, was shown previously to be involved in adaptation of S. elongatus cells to sulfur starvation, which provided the first evidence of cellular function of a cyanobacterial plasmid. Here, we report the complete sequence of pANL, which is 46,366 bp in length with 53% GC content and encodes 58 putative ORFs. The pANL plasmid can be divided into four structural and functional regions: the replication origin region, a signal transduction region, a plasmid maintenance region, and a sulfur-regulated region. Cosmid-based deletion analysis suggested that the plasmid maintenance and replication origin regions are required for persistence of pANL in the cells. Transposon-mediated mutagenesis and complementation-based pANL segregation assays confirmed that two predicted toxin-antitoxin cassettes encoded in the plasmid maintenance region, belonging to PemK and VapC families, respectively, are necessary for plasmid exclusion. The compact and efficient organization of sulfur-related genes on pANL may provide selective advantages in environments with limited sulfur.

  11. 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.

  12. 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

  13. 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

  14. Arsenic Sensing and Resistance System in the Cyanobacterium Synechocystis sp. Strain PCC 6803

    PubMed Central

    López-Maury, Luis; Florencio, Francisco J.; Reyes, José C.

    2003-01-01

    Arsenic is one of the most important global environmental pollutants. Here we show that the cyanobacterium Synechocystis sp. strain PCC 6803 contains an arsenic and antimony resistance operon consisting of three genes: arsB, encoding a putative arsenite and antimonite carrier, arsH, encoding a protein of unknown function, and arsC, encoding a putative arsenate reductase. While arsB mutant strains were sensitive to arsenite, arsenate, and antimonite, arsC mutants were sensitive only to arsenate. The arsH mutant strain showed no obvious phenotype under the conditions tested. In vivo the arsBHC operon was derepressed by oxyanions of arsenic and antimony (oxidation state, +3) and, to a lesser extent, by bismuth (oxidation state, +3) and arsenate (oxidation state, +5). In the absence of these effectors, the operon was repressed by a transcription repressor of the ArsR/SmtB family, encoded by an unlinked gene termed arsR. Thus, arsR null mutants showed constitutive derepression of the arsBHC operon. Expression of the arsR gene was not altered by the presence of arsenic or antimony compounds. Purified recombinant ArsR protein binds to the arsBHC promoter-operator region in the absence of metals and dissociates from the DNA in the presence of Sb(III) or As(III) but not in the presence of As(V), suggesting that trivalent metalloids are the true inducers of the system. DNase I footprinting experiments indicate that ArsR binds to two 17-bp direct repeats, with each one consisting of two inverted repeats, in the region from nucleotides −34 to + 17 of the arsBHC promoter-operator. PMID:12949088

  15. Ethylene Regulates the Physiology of the Cyanobacterium Synechocystis sp. PCC 6803 via an Ethylene Receptor.

    PubMed

    Lacey, Randy F; Binder, Brad M

    2016-08-01

    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. © 2016 American Society of Plant Biologists. All Rights Reserved.

  16. Oxidative stress and photoinhibition can be separated in the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Hakkila, Kaisa; Antal, Taras; Rehman, Ateeq Ur; Kurkela, Juha; Wada, Hajime; Vass, Imre; Tyystjärvi, Esa; Tyystjärvi, Taina

    2014-02-01

    Roles of oxidative stress and photoinhibition in high light acclimation were studied using a regulatory mutant of the cyanobacterium Synechocystis sp. PCC 6803. The mutant strain ΔsigCDE contains the stress responsive SigB as the only functional group 2 σ factor. The ∆sigCDE strain grew more slowly than the control strain in methyl-viologen-induced oxidative stress. Furthermore, a fluorescence dye detecting H2O2, hydroxyl and peroxyl radicals and peroxynitrite, produced a stronger signal in ∆sigCDE than in the control strain, and immunological detection of carbonylated residues showed more protein oxidation in ∆sigCDE than in the control strain. These results indicate that ∆sigCDE suffers from oxidative stress in standard conditions. The oxidative stress may be explained by the findings that ∆sigCDE had a low content of glutathione and low amount of Flv3 protein functioning in the Mehler-like reaction. Although ∆sigCDE suffers from oxidative stress, up-regulation of photoprotective carotenoids and Flv4, Sll2018, Flv2 proteins protected PSII against light induced damage by quenching singlet oxygen more efficiently in ∆sigCDE than in the control strain in visible and in UV-A/B light. However, in UV-C light singlet oxygen is not produced and PSII damage occurred similarly in the ∆sigCDE and control strains. According to our results, resistance against the light-induced damage of PSII alone does not lead to high light tolerance of the cells, but in addition efficient protection against oxidative stress would be required. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Purification and properties of NADP-isocitrate dehydrogenase from the unicellular cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Muro-Pastor, M I; Florencio, F J

    1992-01-15

    NADP-dependent isocitrate dehydrogenase activity has been screened in several cyanobacteria grown on different nitrogen sources; in all the strains tested isocitrate dehydrogenase activity levels were similar in cells grown either on ammonium or nitrate. The enzyme from the unicellular cyanobacterium Synechocystis sp. PCC 6803 has been purified to electrophoretic homogeneity by a procedure that includes Reactive-Red-120-agarose affinity chromatography and phenyl-Sepharose chromatography as main steps. The enzyme was purified about 600-fold, with a yield of 38% and a specific activity of 15.7 U/mg protein. The native enzyme (108 kDa) is composed of two identical subunits with an apparent molecular mass of 57 kDa. Synechocystis isocitrate dehydrogenase was absolutely specific for NADP as electron acceptor. Apparent Km values were 125, 59 and 12 microM for Mg2+, D,L-isocitrate and NADP, respectively, using Mg2+ as divalent cation and 4, 5.7 and 6 microM for Mn2+, D,L-isocitrate and NADP, respectively, using Mn2+ as a cofactor. The enzyme was inhibited non-competitively by ADP (Ki, 6.4 mM) and 2-oxoglutarate, (Ki, 6 mM) with respect to isocitrate and in a competitive manner by NADPH (Ki, 0.6 mM). The circular-dichroism spectrum showed a protein with a secondary structure consisting of about 30% alpha-helix and 36% beta-pleated sheet. The enzyme is an acidic protein with an isoelectric point of 4.4 and analysis of the NH2-terminal sequence revealed 45% identity with the same region of Escherichia coli isocitrate dehydrogenase. The aforementioned data indicate that NADP isocitrate dehydrogenase from Synechocystis resembles isocitrate dehydrogenase from prokaryotes and shows similar molecular and structural properties to the well-known E. coli enzyme.

  18. The highly abundant chlorophyll-protein complex of iron-deficient Synechococcus sp. PCC7942 (CP43') is encoded by the isiA gene.

    PubMed Central

    Burnap, R L; Troyan, T; Sherman, L A

    1993-01-01

    A chlorophyll (Chl)-protein complex designated CPVI-4 becomes the major pigment-protein complex in Synechococcus sp. PCC7942 cells grown under conditions of iron limitation. Work by Laudenbach et al. (J Bacteriol [1988] 170: 5018-5026) has identified an iron-repressible operon, designated isiAB, containing the flavodoxin gene and a gene predicted to encode a Chl-binding protein resembling CP43 of photosystem II. To test the hypothesis that the CP43-like protein is a component of the CPVI-4 complex, we have inactivated the isiAB operon in Synechococcus sp. PCC7942 using directed insertional mutagenesis. Mutant cells grown under conditions of iron limitation exhibit pronounced changes in their spectroscopic and photosynthetic properties relative to similarly grown wild-type cells. Notably, the strong 77 K fluorescence emission at 685 nm, which dominates the spectrum of iron-deficient wild-type cells, is dramatically reduced in the mutant. The loss of this emission appears to unmask the otherwise obscured photosystem II emissions at 685 and 695 nm. Most importantly, mildly denaturing gel electrophoresis shows that mutant cells no longer express the CPVI-4 complex, indicating that the isiA gene encodes a component of this abundant Chl-protein complex. PMID:8022940

  19. The highly abundant chlorophyll-protein complex of iron-deficient Synechococcus sp. PCC7942 (CP43') is encoded by the isiA gene.

    PubMed

    Burnap, R L; Troyan, T; Sherman, L A

    1993-11-01

    A chlorophyll (Chl)-protein complex designated CPVI-4 becomes the major pigment-protein complex in Synechococcus sp. PCC7942 cells grown under conditions of iron limitation. Work by Laudenbach et al. (J Bacteriol [1988] 170: 5018-5026) has identified an iron-repressible operon, designated isiAB, containing the flavodoxin gene and a gene predicted to encode a Chl-binding protein resembling CP43 of photosystem II. To test the hypothesis that the CP43-like protein is a component of the CPVI-4 complex, we have inactivated the isiAB operon in Synechococcus sp. PCC7942 using directed insertional mutagenesis. Mutant cells grown under conditions of iron limitation exhibit pronounced changes in their spectroscopic and photosynthetic properties relative to similarly grown wild-type cells. Notably, the strong 77 K fluorescence emission at 685 nm, which dominates the spectrum of iron-deficient wild-type cells, is dramatically reduced in the mutant. The loss of this emission appears to unmask the otherwise obscured photosystem II emissions at 685 and 695 nm. Most importantly, mildly denaturing gel electrophoresis shows that mutant cells no longer express the CPVI-4 complex, indicating that the isiA gene encodes a component of this abundant Chl-protein complex.

  20. Evidence for an NIH shift in oxidation of naphthalene by the marine cyanobacterium Oscillatoria sp. strain JCM.

    PubMed Central

    Narro, M L; Cerniglia, C E; Van Baalen, C; Gibson, D T

    1992-01-01

    The marine cyanobacterium Oscillatoria sp. strain JCM oxidized naphthalene predominantly to 1-naphthol. Experiments with [1-2H]naphthalene and [2-2H]naphthalene indicated that 1-naphthol was formed with 68 and 74% retention of deuterium, respectively. No significant isotope effect was observed when the organism was incubated with a 1:1 mixture of naphthalene and [2H8]naphthalene. The results indicate that 1-naphthol is formed through a naphthalene 1,2-oxide intermediate, which rearranges spontaneously via an NIH shift mechanism. PMID:1599253

  1. 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.

  2. 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

  3. Novel Insights into the Regulation of LexA in the Cyanobacterium Synechocystis sp. Strain PCC 6803 ▿ †

    PubMed Central

    Oliveira, Paulo; Lindblad, Peter

    2011-01-01

    The transcription factor LexA in the cyanobacterium Synechocystis sp. strain PCC 6803 has been shown to regulate genes that are not directly involved in DNA repair but instead in several different metabolic pathways. However, the signal transduction pathways remain largely uncharacterized. The present work gives novel insights into the regulation of LexA in this unicellular cyanobacterium. A combination of Northern and Western blotting, using specific antibodies against the cyanobacterial LexA, was employed to show that this transcription regulator is under posttranscriptional control, in addition to the classical and already-described transcriptional regulation. Moreover, detailed two-dimensional (2D) electrophoresis analyses of the protein revealed that LexA undergoes posttranslational modifications. Finally, a fully segregated LexA::GFP (green fluorescent protein) fusion-modified strain was produced to image LexA's spatial distribution in live cells. The fusion protein retains DNA binding capabilities, and the GFP fluorescence indicates that LexA is localized in the innermost region of the cytoplasm, decorating the DNA in an evenly distributed pattern. The implications of these findings for the overall role of LexA in Synechocystis sp. strain PCC 6803 are further discussed. PMID:21642463

  4. Photophysiological and photosynthetic complex changes during iron starvation in Synechocystis sp. PCC 6803 and Synechococcus elongatus PCC 7942.

    PubMed

    Fraser, Jared M; Tulk, Sarah E; Jeans, Jennifer A; Campbell, Douglas A; Bibby, Thomas S; Cockshutt, Amanda M

    2013-01-01

    Iron is an essential component in many protein complexes involved in photosynthesis, but environmental iron availability is often low as oxidized forms of iron are insoluble in water. To adjust to low environmental iron levels, cyanobacteria undergo numerous changes to balance their iron budget and mitigate the physiological effects of iron depletion. We investigated changes in key protein abundances and photophysiological parameters in the model cyanobacteria Synechococcus PCC 7942 and Synechocystis PCC 6803 over a 120 hour time course of iron deprivation. The iron stress induced protein (IsiA) accumulated to high levels within 48 h of the onset of iron deprivation, reaching a molar ratio of ~42 IsiA : Photosystem I in Synechococcus PCC 7942 and ~12 IsiA : Photosystem I in Synechocystis PCC 6803. Concomitantly the iron-rich complexes Cytochrome b6f and Photosystem I declined in abundance, leading to a decrease in the Photosystem I : Photosystem II ratio. Chlorophyll fluorescence analyses showed a drop in electron transport per Photosystem II in Synechococcus, but not in Synechocystis after iron depletion. We found no evidence that the accumulated IsiA contributes to light capture by Photosystem II complexes.

  5. Photophysiological and Photosynthetic Complex Changes during Iron Starvation in Synechocystis sp. PCC 6803 and Synechococcus elongatus PCC 7942

    PubMed Central

    Fraser, Jared M.; Tulk, Sarah E.; Jeans, Jennifer A.; Campbell, Douglas A.; Bibby, Thomas S.; Cockshutt, Amanda M.

    2013-01-01

    Iron is an essential component in many protein complexes involved in photosynthesis, but environmental iron availability is often low as oxidized forms of iron are insoluble in water. To adjust to low environmental iron levels, cyanobacteria undergo numerous changes to balance their iron budget and mitigate the physiological effects of iron depletion. We investigated changes in key protein abundances and photophysiological parameters in the model cyanobacteria Synechococcus PCC 7942 and Synechocystis PCC 6803 over a 120 hour time course of iron deprivation. The iron stress induced protein (IsiA) accumulated to high levels within 48 h of the onset of iron deprivation, reaching a molar ratio of ∼42 IsiA : Photosystem I in Synechococcus PCC 7942 and ∼12 IsiA : Photosystem I in Synechocystis PCC 6803. Concomitantly the iron-rich complexes Cytochrome b6f and Photosystem I declined in abundance, leading to a decrease in the Photosystem I : Photosystem II ratio. Chlorophyll fluorescence analyses showed a drop in electron transport per Photosystem II in Synechococcus, but not in Synechocystis after iron depletion. We found no evidence that the accumulated IsiA contributes to light capture by Photosystem II complexes. PMID:23527279

  6. Expression of the psbDII gene in Synechococcus sp. strain PCC 7942 requires sequences downstream of the transcription start site.

    PubMed Central

    Bustos, S A; Golden, S S

    1991-01-01

    The psbDI and psbDII genes in Synechococcus sp. strain PCC 7942 encode the D2 polypeptide, an essential component of the photosystem II reaction center. Previous studies have demonstrated that transcripts from psbDII, but not psbDI, increase in response to high light intensity. Soluble proteins from Synechococcus cells shifted to high light were found to have affinity for DNA sequences upstream from the psbDII coding region. DNA mobility-shift and copper-phenanthroline footprinting assays of a 258-bp fragment revealed three distinct DNA-protein complexes that mapped to the untranslated leader region between +11 and +84. Deletion of the upstream flanking region to -42 had no effect on the expression of a psbDII-lacZ reporter gene or its induction by light, whereas a promoterless construct supported only minimal background levels of beta-galactosidase. A 4-bp deletion within the first protected region of the footprint decreased the beta-galactosidase activity to approximately 2% of that of the undeleted control, but gene expression remained responsive to light. Deletion of the three protected regions completely abolished both gene expression and light induction. These results suggest that the psbDII gene requires elements within the untranslated leader region for efficient gene expression, one of which may be involved in regulation by light. Images FIG. 2 FIG. 3 FIG. 5 PMID:1938947

  7. The Genome Sequence of the Cyanobacterium Oscillatoria sp. PCC 6506 Reveals Several Gene Clusters Responsible for the Biosynthesis of Toxins and Secondary Metabolites▿

    PubMed Central

    Méjean, Annick; Mazmouz, Rabia; Mann, Stéphane; Calteau, Alexandra; Médigue, Claudine; Ploux, Olivier

    2010-01-01

    We report a draft sequence of the genome of Oscillatoria sp. PCC 6506, a cyanobacterium that produces anatoxin-a and homoanatoxin-a, two neurotoxins, and cylindrospermopsin, a cytotoxin. Beside the clusters of genes responsible for the biosynthesis of these toxins, we have found other clusters of genes likely involved in the biosynthesis of not-yet-identified secondary metabolites. PMID:20675499

  8. Setting of the Circadian N2-Fixing Rhythm of the Prokaryotic Synechococcus sp. RF-1 while Its nif Gene Is Repressed 1

    PubMed Central

    Huang, Tan-Chi; Chou, Wing-Ming

    1991-01-01

    The N2-fixing activity of the prokaryotic Synechococcus sp. RF-1 was repressed in the presence of nitrate. When the cultures in nitrate-containing medium were exposed to diurnal light-dark cycles, an endogenous circadian N2-fixing rhythm developed after the cells were transferred to nitrate-free medium and incubated in continuous light. The N2-fixing phase of the rhythm coincided with the dark phase of the light-dark cycles that were imposed when the cells were in nitrate-containing medium. The results indicate that after the endogenous N2-fixing rhythm has been set, it can be kept latent for at least 38 hours before first manifesting itself. ImagesFigure 1Figure 2 PMID:16668175

  9. 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

  10. Characterization of UV-screening compounds, mycosporine-like amino acids, and scytonemin in the cyanobacterium Lyngbya sp. CU2555.

    PubMed

    Rastogi, Rajesh P; Incharoensakdi, Aran

    2014-01-01

    Ultraviolet-screening compounds from the cyanobacterium Lyngbya sp. CU2555 were partially characterized and investigated for their induction by UV radiation, stability under different abiotic factors, and free radical scavenging activity. Based on the high-performance liquid chromatography coupled with diode array detector and ion trap liquid chromatography/mass spectrometry analysis, the compounds were identified as palythine (UVλ max: 319 nm; m/z: 245), asterina (UVλ max: 330 nm; m/z: 289), scytonemin (UVλ max: 384 nm; mw: 544), and reduced scytonemin (UVλ max: 384 nm; m/z: 547). This is the first report for the occurrence of palythine, asterina, and an unknown mycosporine-like amino acids (MAA), M-312 (UVλ max: 312 ± 1 nm), in addition to scytonemin and reduced scytonemin in Lyngbya strains studied so far. Induction of MAAs and scytonemin was significantly more prominent upon exposure to UV-A + UV-B radiation. Both MAAs and scytonemin were highly resistant to some physicochemical factors such as UV-B, heat, and a strong oxidizing agent and exhibited strong antioxidant activity. These results indicate that the studied cyanobacterium may protect itself from deleterious short-wavelength radiation by synthesizing photoprotective compounds in response to harmful UV radiation. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  11. Insights into the complex 3-D architecture of thylakoid membranes in unicellular cyanobacterium Cyanothece sp. ATCC 51142.

    PubMed

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

    2011-04-01

    In cyanobacteria and chloroplasts, thylakoids are the complex internal membrane system where the light reactions of oxygenic photosynthesis occur. In plant chloroplasts, thylakoids are differentiated into a highly interconnected system of stacked grana and unstacked stroma membranes. In contrast, in cyanobacteria, the evolutionary progenitors of chloroplasts, thylakoids do not routinely form stacked and unstacked regions, and the architecture of the thylakoid membrane systems is only now being described in detail in these organisms. We used electron tomography to examine the thylakoid membrane systems in one cyanobacterium, Cyanothece sp. ATCC 51142. Our data showed that thylakoids form a complicated branched network with a rudimentary quasi-helical architecture in this organism. A well accepted helical model of grana-stroma architecture of plant thylakoids describes an organization in which stroma thylakoids wind around stacked granum in right-handed spirals. Here we present data showing that the simplified helical architecture in Cyanothece 51142 is left-handed in nature. We propose a model comparing the thylakoid membranes in plants and this cyanobacterium in which the system in Cyanothece 51142 is composed of non-stacked membranes linked by fret-like connections to other membrane components of the system in a limited left-handed arrangement.

  12. Characterization of the coccoid cyanobacterium Myxosarcina sp. KIOST-1 isolated from mangrove forest in Chuuk State, Federated States of Micronesia

    NASA Astrophysics Data System (ADS)

    Kim, Ji Hyung; Lee, JunMo; Affan, Md-Abu; Lee, Dae-Won; Kang, Do-Hyung

    2017-05-01

    Mangrove forests are known to be inhabited by diverse symbiotic cyanobacterial communities that are capable of N2 fixation. To investigate its biodiversity, root sediments were collected from a mangrove forest in Chuuk State, Federated States of Micronesia (FSM), and an entangled yellow-brown coccoid cyanobacterium was isolated. The isolated cyanobacterium was reproduced by multiple fission and eventually produced baeocytes. Phylogenetic analysis revealed that the isolate was most similar to the genera Myxosarcina and Chroococcidiopsis in the order Pleurocapsales. Compositions of protein, lipid and carbohydrate in the cyanobacterial cells were estimated to be 19.4 ± 0.1%, 18.8 ± 0.4% and 31.5 ± 0.1%, respectively. Interestingly, total fatty acids in the isolate were mainly composed of saturated fatty acids and monounsaturated fatty acids, whereas polyunsaturated fatty acids were not detected. Based on the molecular and biochemical characteristics, the isolate was finally classified in the genus Myxosarcina, and designated as Myxosarcina sp. KIOST-1. These results will contribute to better understanding of cyanobacterial biodiversity in the mangrove forest in FSM as well as the genus Myxosarcina, and also will allow further exploitation of its biotechnological potential on the basis of its cellular characteristics.

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

    PubMed

    Saha, Rajib; Liu, Deng; Hoynes-O'Connor, Allison; Liberton, Michelle; Yu, Jingjie; Bhattacharyya-Pakrasi, Maitrayee; Balassy, Andrea; Zhang, Fuzhong; Moon, Tae Seok; Maranas, Costas D; Pakrasi, Himadri B

    2016-05-03

    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. Cyanobacteria are photosynthetic microbes that use energy from sunlight and CO2 as feedstock. Certain cyanobacterial strains are amenable to facile genetic manipulation, thus enabling

  14. Identification of a new-to-science cyanobacterium, Toxifilum mysidocida gen. nov. & sp. nov. (Cyanobacteria, Cyanophyceae).

    PubMed

    Zimba, Paul V; Huang, I-Shuo; Foley, Jennifer E; Linton, Eric W

    2017-02-01

    Cyanobacteria occupy many niches within terrestrial, planktonic, and benthic habitats. The diversity of habitats colonized, similarity of morphology, and phenotypic plasticity all contribute to the difficulty of cyanobacterial identification. An unknown marine filamentous cyanobacterium was isolated from an aquatic animal rearing facility having mysid mortality events. The cyanobacterium originated from Corpus Christi Bay, TX. Filaments are rarely solitary, benthic mat forming, unbranched, and narrowing at the ends. Cells are 2.1 × 3.1 μm (width × length). Thylakoids are peripherally arranged on the outer third of the cell; cyanophycin granules and polyphosphate bodies are present. Molecular phylogenetic analysis in addition to morphology (transmission electron microscopy and scanning electron microscopy) and chemical composition all confirm it as a new genus and species we name Toxifilum mysidocida. At least one identified Leptolyngbya appears (based on genetic evidence and TEM) to belong to this new genus.

  15. Purification, characterization and function of dihydrolipoamide dehydrogenase from the cyanobacterium Anabaena sp. strain P.C.C. 7119.

    PubMed Central

    Serrano, A

    1992-01-01

    A dihydrolipoamide dehydrogenase (dihydrolipoamide: NAD+ oxidoreductase, EC 1.8.1.4) (DLD) has been found in the soluble fraction of cells of both unicellular (Synechococcus sp. strain P.C.C. 6301) and filamentous (Calothrix sp. strain P.C.C. 7601 and Anabaena sp. strain P.C.C. 7119) cyanobacteria. DLD from Anabaena sp. was purified 3000-fold to electrophoretic homogeneity. The purified enzyme exhibited a specific activity of 190 units/mg and was characterized as a dimeric FAD-containing protein with a native molecular mass of 104 kDa, a Stokes' radius of 4.28 nm and a very acidic pI value of about 3.7. As is the case with the same enzyme from other sources, cyanobacterial DLD showed specificity for NADH and lipoamide, or lipoic acid, as substrates. Nevertheless, the strong acidic character of the Anabaena DLD is a distinctive feature with respect to the same enzyme from other organisms. The presence of essential thiol groups was suggested by the inactivation produced by thiol-group-reactive reagents and heavy-metal ions, with lipoamide, but not NAD+, behaving as a protective agent. The function and physiological significance of Anabaena DLD are discussed in relation to the fact that 2-oxoacid dehydrogenase complexes have not been detected so far in filamentous cyanobacteria. Glycine decarboxylase activity, which might be involved in photorespiratory metabolism, has been found, however, in cell extracts of Anabaena sp. strain P.C.C. 7119 as the present study demonstrates. Images Fig. 2. PMID:1471997

  16. Novel Synechococcus Genomes Reconstructed from Freshwater Reservoirs

    PubMed Central

    Cabello-Yeves, Pedro J.; Haro-Moreno, Jose M.; Martin-Cuadrado, Ana-Belen; Ghai, Rohit; Picazo, Antonio; Camacho, Antonio; Rodriguez-Valera, Francisco

    2017-01-01

    Freshwater picocyanobacteria including Synechococcus remain poorly studied at the genomic level, compared to their marine representatives. Here, using a metagenomic assembly approach we discovered two novel Synechococcus sp. genomes from two freshwater reservoirs Tous and Lake Lanier, both sharing 96% average nucleotide identity and displaying high abundance levels in these two lakes located at similar altitudes and temperate latitudes. These new genomes have the smallest estimated size (2.2 Mb) and average intergenic spacer length (20 bp) of any previously sequenced freshwater Synechococcus, which may contribute to their success in oligotrophic freshwater systems. Fluorescent in situ hybridization confirmed that Synechococcus sp. Tous comprises small cells (0.987 ± 0.139 μm length, 0.723 ± 0.119 μm width) that amount to 90% of the picocyanobacteria in Tous. They appear together in a phylogenomic tree with Synechococcus sp. RCC307 strain, the main representative of sub-cluster 5.3 that has itself one of the smallest marine Synechococcus genomes. We detected a type II phycobilisome (PBS) gene cluster in both genomes, which suggests that they belong to a phycoerythrin-rich pink low-light ecotype. The decrease of acidic proteins and the higher content of basic transporters and membrane proteins in the novel Synechococcus genomes, compared to marine representatives, support their freshwater specialization. A sulfate Cys transporter which is absent in marine but has been identified in many freshwater cyanobacteria was also detected in Synechococcus sp. Tous. The RuBisCo subunits from this microbe are phylogenetically close to the freshwater amoeba Paulinella chromatophora symbiont, hinting to a freshwater origin of the carboxysome operon of this protist. The novel genomes enlarge the known diversity of freshwater Synechococcus and improve the overall knowledge of the relationships among members of this genus at large. PMID:28680419

  17. 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.

  18. 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.

  19. 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.

  20. NMR study of the metabolic 15N isotopic enrichment of cyanophycin synthesized by the cyanobacterium Synechocystis sp. strain PCC 6308.

    PubMed

    Suarez, C; Kohler, S J; Allen, M M; Kolodny, N H

    1999-02-02

    1H, 13C and 15N nuclear magnetic resonance (NMR) spectroscopy has been used to characterize cyanophycin, a multi-l-arginyl-poly-[l-aspartic acid] polypeptide from the cyanobacterium Synechocystis sp. strain PCC 6308. 1H, 13C and 15N chemical shifts and 1JHN and 1JCN coupling constants were measured in isolated 15N-labeled cyanophycin, and showed chemical shift values and J-couplings consistent with the reported polypeptide structure. 15N enrichment levels were determined from the extent of 1H-15N J-coupling in 1H NMR spectra of cyanophycin. Similar experiments using 13C-15N coupling in 13C NMR spectra were not useful in determining enrichment levels.

  1. Uptake and use of the osmoprotective compounds trehalose, glucosylglycerol, and sucrose by the cyanobacterium Synechocystis sp. PCC6803.

    PubMed

    Mikkat, S; Effmert, U; Hagemann, M

    1997-01-01

    Accumulation of exogenously supplied osmoprotective compounds was analyzed in the cyanobacterium Synechocystis sp. PCC6803, which synthesizes glucosylglycerol as the principal osmoprotective compound. Glucosylglycerol and trehalose were accumulated to high levels and protected cells of a mutant unable to synthesize glucosylglycerol against the deleterious effects of salt stress. In the wild-type, uptake of trehalose repressed the synthesis of glucosylglycerol and caused metabolic conversion of originally accumulated glucosylglycerol. Trehalose cannot be synthesized by Synechocystis and was not or only insignificantly metabolized. Sucrose, which can be synthesized in low quantities by Synechocystis, was also taken up, as indicated by its disappearance from the medium. Sucrose was not accumulated to high levels, probably due to a sucrose-degrading activity found in cells adapted to both low- and high-salt conditions. Despite its low intracellular concentration, sucrose showed a weak osmoprotective effect in salt-shocked cells of a mutant unable to synthesize glucosylglycerol.

  2. Stigonemapeptin, an Ahp-containing Depsipeptide with Elastase Inhibitory Activity from the Bloom-Forming Freshwater Cyanobacterium Stigonema sp

    PubMed Central

    Kang, Hahk-Soo; Krunic, Aleksej; Orjala, Jimmy

    2012-01-01

    Stigonemapeptin (1), a depsipeptide containing an Ahp (3-amino-6-hydroxy-2-piperidone) residue, was isolated from a bloom sample of the freshwater cyanobacterium Stigonema sp. collected from North Nokomis Lake in the Highland Lake District of northern Wisconsin. The planar structure was determined by 1D and 2D NMR experiments as well as HRESIMS analysis. The absolute configurations of the amino acids were determined using the advanced Marfey’s method after acid hydrolysis. Stigonemapeptin (1), characterized by the presence of the Ahp residue, also contained the modified amino acids Abu (2-amino-2-butenoic acid) and N-formylated Pro. Stigonemapeptin (1) showed in vitro elastase and chymotrypsin inhibitory activity with IC50 values of 0.26 and 2.93 μM, respectively. PMID:22483033

  3. PilB localization correlates with the direction of twitching motility in the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Schuergers, Nils; Nürnberg, Dennis J; Wallner, Thomas; Mullineaux, Conrad W; Wilde, Annegret

    2015-05-01

    Twitching motility depends on the adhesion of type IV pili (T4P) to a substrate, with cell movement driven by extension and retraction of the pili. The mechanism of twitching motility, and the events that lead to a reversal of direction, are best understood in rod-shaped bacteria such as Myxococcus xanthus. In M. xanthus, the direction of movement depends on the unipolar localization of the pilus extension and retraction motors PilB and PilT to opposite cell poles. Reversal of direction results from relocalization of PilB and PilT. Some cyanobacteria utilize twitching motility for phototaxis. Here, we examine twitching motility in the cyanobacterium Synechocystis sp. PCC 6803, which has a spherical cell shape without obvious polarity. We use a motile Synechocystis sp. PCC 6803 strain expressing a functional GFP-tagged PilB1 protein to show that PilB1 tends to localize in 'crescents' adjacent to a specific region of the cytoplasmic membrane. Crescents are more prevalent under the low-light conditions that favour phototactic motility, and the direction of motility strongly correlates with the orientation of the crescent. We conclude that the direction of twitching motility in Synechocystis sp. PCC 6803 is controlled by the localization of the T4P apparatus, as it is in M. xanthus. The PilB1 crescents in the spherical cells of Synechocystis can be regarded as being equivalent to the leading pole in the rod-shaped cells. © 2015 The Authors.

  4. Inactivation of the Deg protease family in the cyanobacterium Synechocystis sp. PCC 6803 has impact on the outer cell layers.

    PubMed

    Cheregi, Otilia; Miranda, Hélder; Gröbner, Gerhard; Funk, Christiane

    2015-11-01

    The serine type Deg/HtrA proteases are distributed in a wide range of organisms from Escherichia coli to humans. The cyanobacterium Synechocystis sp. PCC 6803 possesses three Deg protease orthologues: HtrA, HhoA and HhoB. Previously we compared Synechocystis 6803 wild type cells exposed to mild or severe stress conditions with a mutant lacking all three Deg proteases and demonstrated that stress had strong impact on the proteomes and metabolomes. To identify the biochemical processes, which this protease family is involved in, here we compared Synechocystis sp. PCC 6803 wild type cells with a mutant lacking all three Deg proteases grown under normal growth conditions (30°C and 40 μmol photons m(-2) s(-1)). Deletion of the Deg proteases lead to the down-regulation of proteins related to the biosynthesis of outer cell layers (e.g. the GDP mannose 4,6-dehydratase) and affected protein secretion. During the late growth phase of the culture Deg proteases were found to be secreted to the extracellular medium of the Synechocystis sp. PCC 6803 wild type strain. While cyanobacterial Deg proteases seem to act mainly in the periplasmic space, deletion of the three proteases influences the proteome and metabolome of the whole cell. Impairments in the outer cell layers of the triple mutant might explain the higher sensitivity toward light and oxidative stress, which was observed earlier by Barker and coworkers. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Cytochrome c{sub 6B} of Synechococcus sp. WH 8102 – Crystal structure and basic properties of novel c{sub 6}-like family representative

    SciTech Connect

    Zatwarnicki, Pawel; Barciszewski, Jakub; Krzywda, Szymon; Jaskolski, Mariusz; Kolesinski, Piotr; Szczepaniak, Andrzej

    2014-01-24

    Highlights: • Crystal structure of cytochrome c{sub 6B} from Synechococcus sp. WH 8102 was solved. • Basic biophysical properties of cytochrome c{sub 6B} were determined. • Cytochrome c{sub 6B} exhibits similar architecture to cytochrome c{sub 6}. • Organization of heme binding pocket of cytochrome c{sub 6B} differs from that of c{sub 6}. • Midpoint potential of cytochrome c{sub 6B} is significantly lower than of cytochrome c{sub 6}. - Abstract: Cytochromes c are soluble electron carriers of relatively low molecular weight, containing single heme moiety. In cyanobacteria cytochrome c{sub 6} participates in electron transfer from cytochrome b{sub 6}f complex to photosystem I. Recent phylogenetic analysis revealed the existence of a few families of proteins homologous to the previously mentioned. Cytochrome c{sub 6A} from Arabidopsis thaliana was identified as a protein responsible for disulfide bond formation in response to intracellular redox state changes and c{sub 550} is well known element of photosystem II. However, function of cytochromes marked as c{sub 6B}, c{sub 6C} and c{sub M} as well as the physiological process in which they take a part still remain unidentified. Here we present the first structural and biophysical analysis of cytochrome from the c{sub 6B} family from mesophilic cyanobacteria Synechococcus sp. WH 8102. Purified protein was crystallized and its structure was refined at 1.4 Å resolution. Overall architecture of this polypeptide resembles typical I-class cytochromes c. The main features, that distinguish described protein from cytochrome c{sub 6}, are slightly red-shifted α band of UV–Vis spectrum as well as relatively low midpoint potential (113.2 ± 2.2 mV). Although, physiological function of cytochrome c{sub 6B} has yet to be determined its properties probably exclude the participation of this protein in electron trafficking between b{sub 6}f complex and photosystem I.

  6. 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

  7. A Comprehensively Curated Genome-Scale Two-Cell Model for the Heterocystous Cyanobacterium Anabaena sp. PCC 7120.

    PubMed

    Malatinszky, David; Steuer, Ralf; Jones, Patrik R

    2017-01-01

    Anabaena sp. PCC 7120 is a nitrogen-fixing filamentous cyanobacterium. Under nitrogen-limiting conditions, a fraction of the vegetative cells in each filament terminally differentiate to nongrowing heterocysts. Heterocysts are metabolically and structurally specialized to enable O2-sensitive nitrogen fixation. The functionality of the filament, as an association of vegetative cells and heterocysts, is postulated to depend on metabolic exchange of electrons, carbon, and fixed nitrogen. In this study, we compile and evaluate a comprehensive curated stoichiometric model of this two-cell system, with the objective function based on the growth of the filament under diazotrophic conditions. The predicted growth rate under nitrogen-replete and -deplete conditions, as well as the effect of external carbon and nitrogen sources, was thereafter verified. Furthermore, the model was utilized to comprehensively evaluate the optimality of putative metabolic exchange reactions between heterocysts and vegetative cells. The model suggested that optimal growth requires at least four exchange metabolites. Several combinations of exchange metabolites resulted in predicted growth rates that are higher than growth rates achieved by only considering exchange of metabolites previously suggested in the literature. The curated model of the metabolic network of Anabaena sp. PCC 7120 enhances our ability to understand the metabolic organization of multicellular cyanobacteria and provides a platform for further study and engineering of their metabolism.

  8. 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.

  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. 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.

  11. 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.

  12. Determination of carbon-to-nitrogen ratio in the filamentous and heterocystous cyanobacterium Anabaena sp. PCC 7120 with single-cell soft X-ray imaging

    NASA Astrophysics Data System (ADS)

    Teramoto, T.; Yoshimura, M.; Azai, C.; Terauchi, K.; Ohta, T.

    2017-06-01

    Vegetative cells and heterocysts in the filamentous cyanobacterium Anabaena sp. PCC 7120 were observed by soft X-ray microscopy. Carbon-to-nitrogen (C/N) ratio of each cell was estimated by the difference of the absorbance of the images below and above the nitrogen K-edge absorption. It was revealed that the C/N ratios in vegetative cells and heterocysts are 4.54 and 2.46, respectively.

  13. Coupling of Cellular Processes and Their Coordinated Oscillations under Continuous Light in Cyanothece sp. ATCC 51142, a Diazotrophic Unicellular Cyanobacterium.

    PubMed

    Krishnakumar, S; Gaudana, Sandeep B; Vinh, Nguyen X; Viswanathan, Ganesh A; Chetty, Madhu; Wangikar, Pramod P

    2015-01-01

    Unicellular diazotrophic cyanobacteria such as Cyanothece sp. ATCC 51142 (henceforth Cyanothece), temporally separate the oxygen sensitive nitrogen fixation from oxygen evolving photosynthesis not only under diurnal cycles (LD) but also in continuous light (LL). However, recent reports demonstrate that the oscillations in LL occur with a shorter cycle time of ~11 h. We find that indeed, majority of the genes oscillate in LL with this cycle time. Genes that are upregulated at a particular time of day under diurnal cycle also get upregulated at an equivalent metabolic phase under LL suggesting tight coupling of various cellular events with each other and with the cell's metabolic status. A number of metabolic processes get upregulated in a coordinated fashion during the respiratory phase under LL including glycogen degradation, glycolysis, oxidative pentose phosphate pathway, and tricarboxylic acid cycle. These precede nitrogen fixation apparently to ensure sufficient energy and anoxic environment needed for the nitrogenase enzyme. Photosynthetic phase sees upregulation of photosystem II, carbonate transport, carbon concentrating mechanism, RuBisCO, glycogen synthesis and light harvesting antenna pigment biosynthesis. In Synechococcus elongates PCC 7942, a non-nitrogen fixing cyanobacteria, expression of a relatively smaller fraction of genes oscillates under LL condition with the major periodicity being 24 h. In contrast, the entire cellular machinery of Cyanothece orchestrates coordinated oscillation in anticipation of the ensuing metabolic phase in both LD and LL. These results may have important implications in understanding the timing of various cellular events and in engineering cyanobacteria for biofuel production.

  14. In Synechococcus sp. competition for energy between assimilation and acquisition of C and those of N only occurs when growth is light limited.

    PubMed

    Ruan, Zuoxi; Raven, John A; Giordano, Mario

    2017-03-28

    The carbon-concentrating mechanisms (CCMs) of cyanobacteria counteract the low CO2 affinity and CO2:O2 selectivities of the Rubisco of these photolithotrophs and the relatively low oceanic CO2 availability. CCMs have a significant energy cost; if light is limiting, the use of N sources whose assimilation demands less energy could permit a greater investment of energy into CCMs and inorganic C (Ci) assimilation. To test this, we cultured Synechococcus sp. UTEX LB 2380 under either N or energy limitation, in the presence of NO3- or NH4+. When growth was energy-limited, NH4+-grown cells had a 1.2-fold higher growth rate, 1.3-fold higher dissolved inorganic carbon (DIC)-saturated photosynthetic rate, 19% higher linear electron transfer, 80% higher photosynthetic 1/K1/2(DIC), 2.0-fold greater slope of the linear part of the photosynthesis versus DIC curve, 3.5-fold larger intracellular Ci pool, and 2.3-fold higher Zn quota than NO3--grown cells. When energy was not limiting growth, there were not differences between NH4+- and NO3--grown cells, except for higher linear electron transfer and larger intracellular Ci pool.We conclude that, when energy limits growth, cells that use the cheaper N source divert energy from N assimilation to C acquisition and assimilation; this does not happen when energy is not limiting.

  15. Reciprocal light-dark transcriptional control of nif and rbc expression and light-dependent posttranslational control of nitrogenase activity in Synechococcus sp. strain RF-1.

    PubMed

    Chow, T J; Tabita, F R

    1994-10-01

    Synechococcus sp. strain RF-1 exhibits a circadian rhythm of N2 fixation when cells are grown under a light-dark cycle, with nitrogenase activity observed only during the dark period. This dark-dependent activity correlated with nif gene transcription in strain RF-1. By using antibodies against dinitrogenase reductase (the Fe protein of the nitrogenase complex), it was found that there was a distinct shift in the mobility of this protein on sodium dodecyl sulfate gels during the light-dark cycle. The Fe protein was present only when cells were incubated in the dark. Upon illumination, there was a conversion of all Fe protein to a modified form, after which it rapidly disappeared from extracts. These studies indicated that all nitrogenase activity present during the dark cycle resulted from de novo synthesis of nitrogenase. Upon entering the light phase, cells appeared to quickly degrade the modified form of Fe protein, perhaps as a result of activating or inducing a protease. By contrast, transcription of the rbcL gene, which encodes the catalytic subunit of the key enzyme of CO2 fixation (a light-dependent process), was enhanced in the light.

  16. Proteomic pattern alterations of the cyanobacterium Synechocystis sp. PCC 6803 in response to cadmium, nickel and cobalt.

    PubMed

    Mehta, Angela; López-Maury, Luis; Florencio, Francisco J

    2014-05-06

    Cyanobacteria represent the largest and most diverse group of prokaryotes capable of performing oxygenic photosynthesis and are frequently found in environments contaminated with heavy metals. Several studies have been performed in these organisms in order to better understand the effects of metals such as Zn, Cd, Cu, Ni and Co. In Synechocystis sp. PCC 6803, genes involved in Ni, Co, Cu and Zn resistance have been reported. However, proteomic studies for the identification of proteins modulated by heavy metals have not been carried out. In the present work, we have analyzed the proteomic pattern alterations of the cyanobacterium Synechocystis sp. PCC 6803 in response to Ni, Co and Cd in order to identify the metabolic processes affected by these metals. We show that some proteins are commonly regulated in response to the different metal ions, including ribulose1,5-bisphosphate carboxylase and the periplasmic iron-binding protein FutA2, while others, such as chaperones, were specifically induced by each metal. We also show that the main processes affected by the metals are carbon metabolism and photosynthesis, since heavy metals affect proteins required for the correct functioning of these activities. This is the first report on the proteomic profile of Synechocystis sp. PCC 6803 wild type and mutant strains for the identification of proteins affected by the heavy metals Ni, Co and Cd. We have identified proteins commonly responsive to all three metals and also chaperones specifically modulated by each metal. Our data also supports previous studies that suggest the existence of additional sensor systems for Co. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Identification of two genes, sll0804 and slr1306, as putative components of the CO2-concentrating mechanism in the cyanobacterium Synechocystis sp. strain PCC 6803.

    PubMed

    Zhang, Shulu; Spann, Kevin W; Frankel, Laurie K; Moroney, James V; Bricker, Terry M

    2008-12-01

    Insertional transposon mutations in the sll0804 and slr1306 genes were found to lead to a loss of optimal photoautotrophy in the cyanobacterium Synechocystis sp. strain PCC 6803 grown under ambient CO(2) concentrations (350 ppm). Mutants containing these insertions (4BA2 and 3ZA12, respectively) could grow photoheterotrophically on glucose or photoautotrophically at elevated CO(2) concentrations (50,000 ppm). Both of these mutants exhibited an impaired affinity for inorganic carbon. Consequently, the Sll0804 and Slr1306 proteins appear to be putative components of the carbon-concentrating mechanism in Synechocystis sp. strain PCC 6803.

  18. Far-red light photoacclimation (FaRLiP) in Synechococcus sp. PCC 7335. II.Characterization of phycobiliproteins produced during acclimation to far-red light.

    PubMed

    Ho, Ming-Yang; Gan, Fei; Shen, Gaozhong; Bryant, Donald A

    2017-02-01

    Phycobilisomes (PBS) are antenna complexes that harvest light for photosystem (PS) I and PS II in cyanobacteria and some algae. A process known as far-red light photoacclimation (FaRLiP) occurs when some cyanobacteria are grown in far-red light (FRL). They synthesize chlorophylls d and f and remodel PS I, PS II, and PBS using subunits paralogous to those produced in white light. The FaRLiP strain, Leptolyngbya sp. JSC-1, replaces hemidiscoidal PBS with pentacylindrical cores, which are produced when cells are grown in red or white light, with PBS with bicylindrical cores when cells are grown in FRL. This study shows that the PBS of another FaRLiP strain, Synechococcus sp. PCC 7335, are not remodeled in cells grown in FRL. Instead, cells grown in FRL produce bicylindrical cores that uniquely contain the paralogous allophycocyanin subunits encoded in the FaRLiP cluster, and these bicylindrical cores coexist with red-light-type PBS with tricylindrical cores. The bicylindrical cores have absorption maxima at 650 and 711 nm and a low-temperature fluorescence emission maximum at 730 nm. They contain ApcE2:ApcF:ApcD3:ApcD2:ApcD5:ApcB2 in the approximate ratio 2:2:4:6:12:22, and a structural model is proposed. Time course experiments showed that bicylindrical cores were detectable about 48 h after cells were transferred from RL to FRL and that synthesis of red-light-type PBS continued throughout a 21-day growth period. When considered in comparison with results for other FaRLiP cyanobacteria, the results here show that acclimation responses to FRL can differ considerably among FaRLiP cyanobacteria.

  19. 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

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

    PubMed

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

    2016-07-21

    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.

  1. 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

    2015-06-12

    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.

  2. 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.

  3. 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.

  4. 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.

  5. The role of an alternative sigma factor in motility and pilus formation in the cyanobacterium Synechocystis sp. strain PCC6803

    PubMed Central

    Bhaya, Devaki; Watanabe, Natsu; Ogawa, Teruo; Grossman, Arthur R.

    1999-01-01

    Disruption of a gene for an alternative sigma factor, designated sigF, in the freshwater, unicellular cyanobacterium Synechocystis sp. strain PCC6803 resulted in a pleiotropic phenotype. Most notably, this mutant lost phototactic movement with a concomitant loss of pili, which are abundant on the surface of wild-type cells. The sigF mutant also secreted both high levels of yellow–brown and UV-absorbing pigments and a polypeptide that is similar to a large family of extracellular proteins that includes the hemolysins. Furthermore, the sigF mutant had a dramatically reduced level of the transcript from two tandemly arranged pilA genes (sll1694 and sll1695), which encode major structural components of type IV pili. Inactivation of these pilA genes eliminated phototactic movement, though some pili were still present in this strain. Together, these results demonstrate that SigF plays a critical role in motility via the control of pili formation and is also likely to regulate other features of the cell surface. Furthermore, the data provide evidence that type IV pili are required for phototactic movement in certain cyanobacteria and suggest that different populations of pili present on the Synechocystis cell surface may perform different functions. PMID:10077659

  6. Evidence Regarding the UV Sunscreen Role of a Mycosporine-Like Compound in the Cyanobacterium Gloeocapsa sp

    PubMed Central

    Garcia-Pichel, Ferran; Wingard, Christopher E.; Castenholz, Richard W.

    1993-01-01

    The UV sunscreen role commonly ascribed to mycosporine-like amino acids (MAAs) was investigated with an isolate of the terrestrial cyanobacterium Gloeocapsa sp. strain C-90-Cal-G.(2), which accumulates intracellularly an MAA with absorbance maximum at 326 nm but produces no extracellular sunscreen compound (i.e., scytonemin). The intracellular concentrations of MAA achieved were directly related to the intensity of the UV radiation (maximum at 320 nm) received by the cells. However, the presence of high concentrations of MAA was not necessary for the physiological acclimation of the cultures to UV radiation. The measured sunscreen factor due to MAA in single cells was 0.3 (the MAA prevented 3 out of 10 photons from hitting potential cytoplasmic targets). High contents of MAA in the cells correlated with increased resistance to UV radiation. However, when resistance was gauged under conditions of desiccation, with inoperative physiological photoprotective and repair mechanisms, cells with high MAA specific contents were only 20 to 25% more resistant. Although UV radiation centered around both 320 and 365 nm resulted in chlorophyll a photobleaching and photoinhibition of photosynthesis, the difference in sensitivity correlated with MAA accumulation occurred only at 320 nm (absorbed by MAA) and not at 365 nm (not absorbed by MAA). This difference represents the maximal protection ascribable to the presence of MAA for single cells, i.e., if one does not consider the enhancing effects of colony formation on protection by sunscreens. PMID:16348840

  7. 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

  8. Alcohol dehydrogenase AdhA plays a role in ethanol tolerance in model cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Vidal, Rebeca

    2017-02-03

    The protein AdhA from the cyanobacterium Synechocystis sp. PCC 6803 (hereafter Synechocystis) has been previously reported to show alcohol dehydrogenase activity towards ethanol and both NAD and NADP. This protein is currently being used in genetically modified strains of Synechocystis capable of synthesizing ethanol showing the highest ethanol productivities. In the present work, mutant strains of Synechocystis lacking AdhA have been constructed and tested for tolerance to ethanol. The lack of AdhA in the wild-type strain reduces survival to externally added ethanol at lethal concentration of 4% (v/v). On the other hand, the lack of AdhA in an ethanologenic strain diminishes tolerance of cells to internally produced ethanol. It is also shown that light-activated heterotrophic growth (LAHG) of the wild-type strain is impaired in the mutant strain lacking AdhA (∆adhA strain). Photoautotrophic, mixotrophic, and photoheterotrophic growth are not affected in the mutant strain. Based on phenotypic characterization of ∆adhA mutants, the possible physiological function of AdhA in Synechocystis is discussed.

  9. ArsH from the cyanobacterium Synechocystis sp. PCC 6803 is an efficient NADPH-dependent quinone reductase.

    PubMed

    Hervás, Manuel; López-Maury, Luis; León, Pilar; Sánchez-Riego, Ana M; Florencio, Francisco J; Navarro, José A

    2012-02-14

    The cyanobacterium Synechocystis sp. PCC 6803 possesses an arsenic resistance operon that encodes, among others, an ArsH protein. ArsH is a flavin mononucleotide (FMN)-containing protein of unknown function and a member of the family of NADPH-dependent FMN reductases. The nature of its final electron acceptor and the role of ArsH in the resistance to arsenic remained to be clarified. Here we have expressed and purified Synechocystis ArsH and conducted an intensive biochemical study. We present kinetic evidence supporting a quinone reductase activity for ArsH, with a preference for quinones with hydrophobic substituents. By using steady-state activity measurements, as well as stopped-flow and laser-flash photolysis kinetic analyses, it has been possible to establish the mechanism of the process and estimate the values of the kinetic constants. Although the enzyme is able to stabilize the anionic semiquinone form of the FMN, reduction of quinones involves the hydroquinone form of the flavin cofactor, and the enzymatic reaction occurs through a ping-pong-type mechanism. ArsH is able to catalyze one-electron reactions (oxygen and cytocrome c reduction), involving the FMN semiquinone form, but with lower efficiency. In addition, arsH mutants are sensitive to the oxidizing agent menadione, suggesting that ArsH plays a role in the response to oxidative stress caused by arsenite.

  10. 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.

  11. 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.

  12. Evaluation of promoters and ribosome binding sites for biotechnological applications in the unicellular cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Englund, Elias; Liang, Feiyan; Lindberg, Pia

    2016-11-18

    For effective metabolic engineering, a toolbox of genetic components that enables predictable control of gene expression is needed. Here we present a systematic study of promoters and ribosome binding sites in the unicellular cyanobacterium Synechocystis sp. PCC 6803. A set of metal ion inducible promoters from Synechocystis were compared to commonly used constitutive promoters, by measuring fluorescence of a reporter protein in a standardized setting to allow for accurate comparisons of promoter activity. The most versatile and useful promoter was found to be PnrsB, which from a relatively silent expression could be induced almost 40-fold, nearly up to the activity of the strong psbA2 promoter. By varying the concentrations of the two metal ion inducers Ni(2+) and Co(2+), expression from the promoter was highly tunable, results that were reproduced with PnrsB driving ethanol production. The activities of several ribosomal binding sites were also measured, and tested in parallel in Synechocystis and Escherichia coli. The results of the study add useful information to the Synechocystis genetic toolbox for biotechnological applications.

  13. Carbamidocyclophanes F and G with Anti-Mycobacterium tuberculosis Activity from the Cultured Freshwater Cyanobacterium Nostoc sp.

    PubMed

    Luo, Shangwen; Kang, Hahk-Soo; Krunic, Aleksej; Chlipala, George E; Cai, Geping; Chen, Wei-Lun; Franzblau, Scott G; Swanson, Steven M; Orjala, Jimmy

    2014-01-15

    Two new (1 and 2) and three known (3-5) carbamidocyclophanes were isolated from a cultured freshwater cyanobacterium Nostoc sp. (UIC 10274) obtained from a sample collected at Des Plaines, Illinois. Their planar structures and stereoconfigurations were determined by extensive spectroscopic analysis including 1D/2D NMR experiments, HRESIMS as well as CD spectroscopy. Carbamidocyclophane F (1) showed potent anti-Mycobacterium tuberculosis activity in the microplate Alamar blue assay and low-oxygen-recovery assay with MIC values of 0.8 and 5.4 µM, respectively. Carbamidocyclophane F (1) also displayed antimicrobial activities against the gram positive bacteria Staphylococcus aureus and Enterococcus faecalis with MIC values of 0.1 and 0.2 µM, respectively. Carbamidocyclophane F (1) and Carbamidocyclophane G (2) both showed antiproliferative activity against MDA-MB-435 and HT-29 human cancer cell lines with IC50 values in the range from 0.5 to 0.7 µM.

  14. Evaluation of promoters and ribosome binding sites for biotechnological applications in the unicellular cyanobacterium Synechocystis sp. PCC 6803

    PubMed Central

    Englund, Elias; Liang, Feiyan; Lindberg, Pia

    2016-01-01

    For effective metabolic engineering, a toolbox of genetic components that enables predictable control of gene expression is needed. Here we present a systematic study of promoters and ribosome binding sites in the unicellular cyanobacterium Synechocystis sp. PCC 6803. A set of metal ion inducible promoters from Synechocystis were compared to commonly used constitutive promoters, by measuring fluorescence of a reporter protein in a standardized setting to allow for accurate comparisons of promoter activity. The most versatile and useful promoter was found to be PnrsB, which from a relatively silent expression could be induced almost 40-fold, nearly up to the activity of the strong psbA2 promoter. By varying the concentrations of the two metal ion inducers Ni2+ and Co2+, expression from the promoter was highly tunable, results that were reproduced with PnrsB driving ethanol production. The activities of several ribosomal binding sites were also measured, and tested in parallel in Synechocystis and Escherichia coli. The results of the study add useful information to the Synechocystis genetic toolbox for biotechnological applications. PMID:27857166

  15. 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

  16. 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. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  17. SynechoNET: integrated protein-protein interaction database of a model cyanobacterium Synechocystis sp. PCC 6803

    PubMed Central

    Kim, Woo-Yeon; Kang, Sungsoo; Kim, Byoung-Chul; Oh, Jeehyun; Cho, Seongwoong; Bhak, Jong; Choi, Jong-Soon

    2008-01-01

    Background Cyanobacteria are model organisms for studying photosynthesis, carbon and nitrogen assimilation, evolution of plant plastids, and adaptability to environmental stresses. Despite many studies on cyanobacteria, there is no web-based database of their regulatory and signaling protein-protein interaction networks to date. Description We report a database and website SynechoNET that provides predicted protein-protein interactions. SynechoNET shows cyanobacterial domain-domain interactions as well as their protein-level interactions using the model cyanobacterium, Synechocystis sp. PCC 6803. It predicts the protein-protein interactions using public interaction databases that contain mutually complementary and redundant data. Furthermore, SynechoNET provides information on transmembrane topology, signal peptide, and domain structure in order to support the analysis of regulatory membrane proteins. Such biological information can be queried and visualized in user-friendly web interfaces that include the interactive network viewer and search pages by keyword and functional category. Conclusion SynechoNET is an integrated protein-protein interaction database designed to analyze regulatory membrane proteins in cyanobacteria. It provides a platform for biologists to extend the genomic data of cyanobacteria by predicting interaction partners, membrane association, and membrane topology of Synechocystis proteins. SynechoNET is freely available at or directly at . PMID:18315852

  18. 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

  19. 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.

  20. 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

  1. Constant Phycobilisome Size in Chromatically Adapted Cells of the Cyanobacterium Tolypothrix tenuis, and Variation in Nostoc sp. 1

    PubMed Central

    Ohki, Kaori; Gantt, Elisabeth; Lipschultz, Claudia A.; Ernst, Marjorie C.

    1985-01-01

    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 phycocyanin 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. Images Fig. 1 Fig. 2 Fig. 4 PMID:16664550

  2. Desiccation induced changes in osmolytes production and the antioxidative defence in the cyanobacterium Anabaena sp. PCC 7120.

    PubMed

    Singh, Priyanka; Tiwari, Anupam; Singh, Sureshwar Prasad; Asthana, Ravi Kumar

    2013-01-01

    Cells of Anabaena sp. PCC 7120, a low desiccation tolerant cyanobacterium, was subjected to prolonged desiccation and effect of loss of water was examined on production of osmolytes, and antioxidant response as well as on overall viability in terms of photosynthetic activity. During dehydration (22 h), the organism maintained about 98.5 % loss of cellular water, yet cells remained viable as about 30 % of photosynthetic O2-evolution activity resumed upon hydrating (1 h) such cells. In desiccated state, cyanobacterial cells accumulated osmolytes within 1 h though their contents decreased thereafter. The highest levels of trehalose (179 nmol mg(-1) protein), sucrose (805 nmol mg(-1) protein) and proline (23.2 nmol mg(-1) protein) were attained within 1 h. Chlorophyll a and carotenoid contents also increased within 1 h but phycocyanin level showed opposite trend. The oxygen-evolving activity declined in desiccated cyanobacterial biomass while rehydration led to instant recovery, indicating that cells protect the photosynthetic machinery against desiccation. Notwithstanding, activities of antioxidant enzymes (catalase, peroxidase and superoxide dismutase) attained their peaks after 3 h of desiccation, though within 10 min of rehydration, their levels returned back close to basal activities of the cultured cells. We propose that onset of osmolyte production in conjunction with upshift of antioxidant enzymes apparently protects the cyanobacterial cells from desiccation stress.

  3. TRANSCRIPTIONAL ANALYSIS OF THE UNICELLULAR, DIAZOTROPHIC CYANOBACTERIUM CYANOTHECE SP. ATCC 51142 GROWN UNDER SHORT DAY/NIGHT CYCLES(1).

    PubMed

    Toepel, Jo Rg; McDermott, Jason E; Summerfield, Tina C; 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 (L:D) 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 these data and those from 2 d L:D and L:D plus continuous light experiments to better differentiate between diurnal and circadian-regulated genes. Cyanothece sp. acclimated in several ways to growth under short L:D 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 L:D 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.

  4. The uptake hydrogenase in the unicellular diazotrophic cyanobacterium Cyanothece sp. strain PCC 7822 protects nitrogenase from oxygen toxicity.

    PubMed

    Zhang, Xiaohui; Sherman, Debra M; Sherman, Louis A

    2014-02-01

    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.

  5. 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.

  6. 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

  7. [Mutation in the glmS gene responsible for the cell wall synthesis increases resistance to the herbicide amitrole in the cyanobacterium Synechocystis sp. PCC6803].

    PubMed

    Babykin, M M; Kovach, A; Cerff, R; Shestakov, S V

    2000-10-01

    A DNA fragment transforming the cells of the cyanobacterium Synechocystis sp. PCC 6803 to amitrole (3-amino-1,2,4-triazole) resistance was cloned from the Atr2 mutant resistant to this herbicide. The transforming activity of the cloned fragment was shown to be related to the missence-mutation "Val250-->Leu250" in the glmS gene encoding glucosamine-6-phosphate synthase, a key enzyme of cell wall synthesis. The amino acid substitution is localized in the central nonconservative part of the GlmS protein, far from two reaction centers positioned at the ends of a polypeptide. It is suggested that the mutant protein has lost sensitivity to amitrole. In the wild type strain, this herbicide causes conditional glucosamine auxotrophy (exogenous glucosamine restores ability of the cells to row in the presence of the lethal amitrole concentrations). Val250 is proposed to be allosteric binding site of AM in the GlmS protein of cyanobacterium.

  8. The siderophilic cyanobacterium Leptolyngbya sp. strain JSC-1 acclimates to iron starvation by expressing multiple isiA-family genes.

    PubMed

    Shen, Gaozhong; Gan, Fei; Bryant, Donald A

    2016-06-01

    In the evolution of different cyanobacteria performing oxygenic photosynthesis, the core complexes of the two photosystems were highly conserved. However, cyanobacteria exhibit significant diversification in their light-harvesting complexes and have flexible regulatory mechanisms to acclimate to changes in their growth environments. In the siderophilic, filamentous cyanobacterium, Leptolyngbya sp. strain JSC-1, five different isiA-family genes occur in two gene clusters. During acclimation to Fe limitation, relative transcript levels for more than 600 genes increased more than twofold. Relative transcript levels were ~250 to 300 times higher for the isiA1 gene cluster (isiA1-isiB-isiC), and ~440- to 540-fold for the isiA2-isiA3-isiA4-cpcG2-isiA5 gene cluster after 48 h of iron starvation. Chl-protein complexes were isolated and further purified from cells grown under Fe-replete and Fe-depleted conditions. A single class of particles, trimeric PSI, was identified by image analysis of electron micrographs of negatively stained PSI complexes from Fe-replete cells. However, three major classes of particles were observed for the Chl-protein supercomplexes from cells grown under iron starvation conditions. Based on LC-MS-MS analyses, the five IsiA-family proteins were found in the largest supercomplexes together with core components of the two photosystems; however, IsiA5 was not present in complexes in which only the core subunits of PSI were detected. IsiA5 belongs to the same clade as PcbC proteins in a phylogenetic classification, and it is proposed that IsiA5 is most likely involved in supercomplexes containing PSII dimers. IsiA4, which is a fusion of an IsiA domain and a C-terminal PsaL domain, was found together with IsiA1, IsiA2, and IsiA3 in complexes with monomeric PSI. The data indicate that horizontal gene transfer, gene duplication, and divergence have played important roles in the adaptive evolution of this cyanobacterium to iron starvation conditions.

  9. The 2.15 A crystal structure of a triple mutant plastocyanin from the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Romero, A; De la Cerda, B; Varela, P F; Navarro, J A; Hervás, M; De la Rosa, M A

    1998-01-16

    The crystal structure of the triple mutant A42D/D47P/A63L plastocyanin from the cyanobacterium Synechocystis sp. PCC 6803 has been determined by Patterson search methods using the known structure of the poplar protein. Crystals of the triple mutant A42D/D47P/A63L, which are stable for days in its oxidized form, were grown from ammonium sulfate, with the cell constants a = b = 34.3 A and c = 111.8 A belonging to space group P3(2)21. The structure was refined using restrained crystallographic refinement to an R-factor of 16.7% for 4070 independent reflections between 8.0 and 2.15 A with intensities greater than 2 sigma (I), with root mean square deviations of 0.013 A and 1.63 degrees from ideal bond lengths and bond angles, respectively. The final model comprises 727 non-hydrogen protein atoms within 98 residues, 75 water molecules and a single copper ion. The overall tertiary fold of Synechocystis plastocyanin consists of a compact ellipsoidal beta-sandwich structure made up of two beta-sheets embracing a hydrophobic core. Each sheet contains parallel and antiparallel beta-strands. In addition to the beta-sheets, the structure contains an alpha-helix from Pro47 to Lys54 that follows beta-strand 4. The three-dimensional structure of Synechocystis plastocyanin is thus similar to those reported for the copper protein isolated from eukaryotic organisms and, in particular, from the cyanobacterium Anabaena variabilis, the only cyanobacterial plastocyanin structure available so far. The molecule holds an hydrophobic region surrounding His87, as do other plastocyanins, but the lack of negatively charged residues at the putative distant remote site surrounding Tyr83 could explain why the Synechocystis protein exhibits a collisional reaction mechanism for electron transfer to photosystem I (PSI), which involves no formation of the transient plastocyanin-PSI complex kinetically observed in green algae and higher plants.

  10. Draft Genome Sequence of a Tropical Freshwater Cyanobacterium, Limnothrix sp. Strain P13C2

    PubMed Central

    Tan, Boon Fei; Gin, Karina Yew-Hoong

    2016-01-01

    A nonaxenic unialgal culture of Limnothrix sp. strain P13C2 was obtained through multiple subculturing of an inoculum obtained from a tropical freshwater lake. Here, we report the genome of P13C2 of 4.6 Mbp, extracted from the metagenome of this coculture. PMID:27795269

  11. Functional characterization of Synechococcus amylosucrase and fructokinase encoding genes discovers two novel actors on the stage of cyanobacterial sucrose metabolism.

    PubMed

    Perez-Cenci, Macarena; Salerno, Graciela L

    2014-07-01

    Plants and most cyanobacteria metabolize sucrose (Suc) with a similar set of enzymes. In Synechococcus sp. PCC 7002, a marine cyanobacterium strain, genes involved in Suc synthesis (spsA and sppA) have been characterized; however, its breakdown was still unknown. Indeed, neither invertase nor sucrose synthase genes, usually found in plants and cyanobacteria, were found in that Synechococcus genome. In the present study, we functionally characterized the amsA gene that codes for an amylosucrase (AMS), a glycoside-hydrolase family 13 enzyme described in bacteria, which may catabolyze Suc in Synechococcus. Additionally, we identified and characterized the frkA gene that codes for a fructokinase (FRK), enzyme that yields fructose-6P, one of the substrates for Suc synthesis. Interestingly, we demonstrate that spsA, sppA, frkA and amsA are grouped in a transcriptional unit that were named Suc cluster, whose expression is increased in response to a salt treatment. This is the first report on the characterization of an AMS and FRK in an oxygenic photosynthetic microorganism, which could be associated with Suc metabolism.

  12. Isolation of Regulated Genes of the Cyanobacterium Synechocystis sp. Strain PCC 6803 by Differential Display†

    PubMed Central

    Bhaya, Devaki; Vaulot, Daniel; Amin, Pinky; Takahashi, Akiko Watanabe; Grossman, Arthur R.

    2000-01-01

    Global identification of differentially regulated genes in prokaryotes is constrained because the mRNA does not have a 3′ polyadenylation extension; this precludes specific separation of mRNA from rRNA and tRNA and synthesis of cDNAs from the entire mRNA population. Knowledge of the entire genome sequence of Synechocystis sp. strain PCC 6803 has enabled us to develop a differential display procedure that takes advantage of a short palindromic sequence that is dispersed throughout the Synechocystis sp. strain PCC 6803 genome. This sequence, designated the HIP (highly iterated palindrome) element, occurs in approximately half of the Synechocystis sp. strain PCC 6803 genes but is absent in rRNA and tRNA genes. To determine the feasibility of exploiting the HIP element, alone or in combination with specific primer subsets, for analyzing differential gene expression, we used HIP-based primers to identify light intensity-regulated genes. Several gene fragments, including those encoding ribosomal proteins and phycobiliprotein subunits, were differentially amplified from RNA templates derived from cells grown in low light or exposed to high light for 3 h. One novel finding was that expression of certain genes of the pho regulon, which are under the control of environmental phosphate levels, were markedly elevated in high light. High-light activation of pho regulon genes correlated with elevated growth rates that occur when the cells are transferred from low to high light. These results suggest that in high light, the rate of growth of Synechocystis sp. strain PCC 6803 exceeds its capacity to assimilate phosphate, which, in turn, may trigger a phosphate starvation response and activation of the pho regulon. PMID:11004166

  13. Complete genome sequence of cyanobacterium Fischerella sp. NIES-3754, providing thermoresistant optogenetic tools.

    PubMed

    Hirose, Yuu; Fujisawa, Takatomo; Ohtsubo, Yoshiyuki; Katayama, Mitsunori; Misawa, Naomi; Wakazuki, Sachiko; Shimura, Yohei; Nakamura, Yasukazu; Kawachi, Masanobu; Yoshikawa, Hirofumi; Eki, Toshihiko; Kanesaki, Yu

    2016-02-20

    Cyanobacterial phytochrome-class photosensors are recently emerging optogenetic tools. We isolated Fischerella sp. strain NIES-3754 from hotspring at Suwa-shrine, Suwa, Nagano, Japan. We determined complete genome sequence of the NIES-3754 strain, which is composed of one chromosome and two putative replicons (total 5,826,863bp containing no gaps). We identified photosensor genes of 5 phytochromes and 9 cyanobacteriochromes, which will facilitate optogenetics of thermophile.

  14. 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.

  15. 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

  16. Sheathless Mutant of Cyanobacterium Gloeothece sp. Strain PCC 6909 with Increased Capacity To Remove Copper Ions from Aqueous Solutions▿

    PubMed Central

    Micheletti, Ernesto; Pereira, Sara; Mannelli, Francesca; Moradas-Ferreira, Pedro; Tamagnini, Paula; De Philippis, Roberto

    2008-01-01

    The cyanobacterium Gloeothece sp. strain PCC 6909 and its sheathless mutant were tested for their abilities to remove copper ions from aqueous solutions, with the aim of defining the role of the various outermost polysaccharidic investments in the removal of the metal ions. Microscopy studies and chemical analyses revealed that, although the mutant does not possess a sheath, it releases large amounts of polysaccharidic material (released exocellular polysaccharides [RPS]) into the culture medium. The RPS of the wild type and the mutant are composed of the same 11 sugars, although they are present in different amounts, and the RPS of the mutant possesses a larger amount of acidic sugars and a smaller amount of deoxysugars than the wild type. Unexpectedly, whole cultures of the mutant were more effective in the removal of the heavy metal than the wild type (46.3 ± 3.1 and 26.7 ± 1.5 mg of Cu2+ removed per g of dry weight, respectively). Moreover, we demonstrated that the contribution of the sheath to the metal-removal capacity of the wild type is scarce and that the RPS of the mutant is more efficient in removing copper. This suggests that the metal ions are preferably bound to the cell wall and to RPS functional groups rather than to the sheath. Therefore, the increased copper binding efficiency observed with the sheathless mutant can be attributed to the release of a polysaccharide containing larger amounts and/or more accessible functional groups (e.g., carboxyl and amide groups). PMID:18326679

  17. 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

  18. Redox-dependent Ligand Switching in a Sensory Heme-binding GAF Domain of the Cyanobacterium Nostoc sp. PCC7120.

    PubMed

    Tang, Kun; Knipp, Markus; Liu, Bing-Bing; Cox, Nicholas; Stabel, Robert; He, Qi; Zhou, Ming; Scheer, Hugo; Zhao, Kai-Hong; Gärtner, Wolfgang

    2015-07-31

    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 Fe(III) 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 (Fe(II) state) binds both NO and CO. Cysteine coordination of the as isolated Fe(III) 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.

  19. 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.

  20. The Sll0606 protein is required for photosystem II assembly/stability in the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Zhang, Shulu; Frankel, Laurie K; Bricker, Terry M

    2010-10-15

    An insertional transposon mutation in the sll0606 gene was found to lead to a loss of photoautotrophy but not photoheterotrophy in the cyanobacterium Synechocystis sp. PCC 6803. Complementation analysis of this mutant (Tsll0606) indicated that an intact sll0606 gene could fully restore photoautotrophic growth. Gene organization in the vicinity of sll0606 indicates that it is not contained in an operon. No electron transport activity was detected in Tsll0606 using water as an electron donor and 2,6-dichlorobenzoquinone as an electron acceptor, indicating that Photosystem II (PS II) was defective. Electron transport activity using dichlorophenol indolephenol plus ascorbate as an electron donor to methyl viologen, however, was the same as observed in the control strain. This indicated that electron flow through Photosystem I was normal. Fluorescence induction and decay parameters verified that Photosystem II was highly compromised. The quantum yield for energy trapping by Photosystem II (F(V)/F(M)) in the mutant was less than 10% of that observed in the control strain. The small variable fluorescence yield observed after a single saturating flash exhibited aberrant Q(A)(-) reoxidation kinetics that were insensitive to dichloromethylurea. Immunological analysis indicated that whereas the D2 and CP47 proteins were modestly affected, the D1 and CP43 components were dramatically reduced. Analysis of two-dimensional blue native/lithium dodecyl sulfate-polyacrylamide gels indicated that no intact PS II monomer or dimers were observed in the mutant. The CP43-less PS II monomer did accumulate to detectable levels. Our results indicate that the Sll0606 protein is required for the assembly/stability of a functionally competent Photosystem II.

  1. 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

  2. The role of cyanopterin in UV/blue light signal transduction of cyanobacterium Synechocystis sp. PCC 6803 phototaxis.

    PubMed

    Moon, Yoon-Jung; Lee, Eun-Mi; Park, Young Mok; Park, Young Shik; Chung, Won-Il; Chung, Young-Ho

    2010-06-01

    We analyzed the effects of inactivating the pteridine glycosyltransferase gene (pgtA) on the photomovement of the cyanobacterium Synechocystis sp. PCC 6803 under different light conditions. The pgtA mutant displayed abnormal photomovement under UV-A/blue light. In particular, the pgtA mutant showed a negative phototactic response under UV-A (315-400 nm), whereas the wild-type did not show any photomovement. Inhibition of pterin biosynthesis by N-acetylserotonin (NAS), an inhibitor of sepiapterin reductase, also inhibited a positive phototactic response of the wild-type under white and blue light. In addition, negative phototaxis of the pgtA mutant was observed under UV-A/blue light in the presence of NAS. These results indicated that the product of the PgtA enzyme, cyanopterin, is involved in the inhibition of the negative phototaxis of the wild-type by sensing the UV-A. However, 2,4-diamino-6-hydroxypyrimidine-mediated inhibition of GTP cyclohydrolase I, the rate-limiting enzyme for pterin biosynthesis, significantly increased the positive phototaxis toward UV-A in the wild-type and the pgtA mutant. Furthermore, we measured the action spectrum of phototaxis in vivo for the wild-type and pgtA mutant. Maximal activity of the wild-type was at 300, 380 and 440 nm, indicating absorption by pterins and flavin. In particular, the UV-A/ blue peak at 380 and 440 nm obtained from the action spectrum of phototaxis was found to be closely correlated with the in vitro absorption spectrum previously reported for the cyanobacterial cryptochrome DASH. By investigating the photomovement of the wild-type and pgtA mutant to UV and blue light, we suggest that pterin can function as the chromophore of putative UV/blue photoreceptor(s) in cyanobacterial phototaxis.

  3. A redox-responsive regulator of photosynthesis gene expression in the cyanobacterium Synechocystis sp. Strain PCC 6803.

    PubMed

    Li, H; Sherman, L A

    2000-08-01

    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 Delta rppA, 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 Delta rppA was manifest by higher translation of the D1 protein and a concomitant increase in O(2) 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.

  4. 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.

  5. 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. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Terminal oxidase mutants of the cyanobacterium Synechocystis sp. PCC 6803 show increased electrogenic activity in biological photo-voltaic systems.

    PubMed

    Bradley, Robert W; Bombelli, Paolo; Lea-Smith, David J; Howe, Christopher J

    2013-08-28

    Biological photo-voltaic systems are a type of microbial fuel cell employing photosynthetic microbes at the anode, enabling the direct transduction of light energy to electrical power. Unlike the anaerobic bacteria found in conventional microbial fuel cells that use metals in the environment as terminal electron acceptors, oxygenic photosynthetic organisms are poorly adapted for electron transfer out of the cell. Mutant strains of the cyanobacterium Synechocystis sp. PCC 6803 were created in which all combinations of the three respiratory terminal oxidase complexes had been inactivated. These strains were screened for the ability to reduce the membrane-impermeable soluble electron acceptor ferricyanide, and the results were compared to the performance of the mutants in a biological photo-voltaic system. Deletion of the two thylakoid-localised terminal oxidases, the bd-quinol oxidase and cytochrome c oxidase resulted in a 16-fold increase in ferricyanide reduction rate in the dark compared to the wild-type. A further improvement to a 24-fold increase was seen upon deletion of the remaining "alternative respiratory terminal oxidase". These increases were reflected in the peak power generated in the biological photo-voltaic systems. Inactivation of all three terminal oxidase complexes resulted in a substantial redirection of reducing power; in the dark the equivalent of 10% of the respiratory electron flux was channelled to ferricyanide, compared to less than 0.2% in the wild-type. Only minor improvements in ferricyanide reduction rates over the wild-type were seen in illuminated conditions, where carbon dioxide is preferentially used as an electron sink. This study demonstrates the potential for optimising photosynthetic microbes for direct electrical current production.

  7. The LexA transcription factor regulates fatty acid biosynthetic genes in the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Kizawa, Ayumi; Kawahara, Akihito; Takashima, Kosuke; Takimura, Yasushi; Nishiyama, Yoshitaka; Hihara, Yukako

    2017-07-26

    Specific transcription factors have been identified in various heterotrophic bacterial species that regulate the sets of genes required for fatty acid metabolism. Here, we report that expression of the fab genes, encoding fatty acid biosynthetic enzymes, is regulated by the global regulator LexA in the photoautotrophic cyanobacterium Synechocystis sp. PCC 6803. Sll1626, an ortholog of the well-known LexA repressor involved in the SOS response in heterotrophic bacteria, was isolated from crude extracts of Synechocystis by DNA affinity chromatography, reflecting its binding to the upstream region of the acpP-fabF and fabI genes. An electrophoresis mobility shift assay revealed that the recombinant LexA protein can bind to the upstream region of each fab gene tested (fabD, fabH, fabF, fabG, fabZ and fabI). Quantitative RT-PCR analysis of the wild type and a lexA-disrupted mutant strain suggested that LexA acts as a repressor of the fab genes involved in initiation of fatty acid biosynthesis (fabD, fabH and fabF) and the first reductive step in the subsequent elongation cycle (fabG) under normal growth conditions. Under nitrogen-depleted conditions, downregulation of fab gene expression is partly achieved through an increase in LexA-repressing activity. In contrast, under phosphate-depleted conditions, fab gene expression is upregulated, probably due to the loss of repression by LexA. We further demonstrate that elimination of LexA largely increases the production of fatty acids in strains modified to secrete free fatty acids. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

  8. 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. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  9. Proteomic approaches to identify substrates of the three Deg/HtrA proteases of the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Tam, Lam X; Aigner, Harald; Timmerman, Evy; Gevaert, Kris; Funk, Christiane

    2015-06-15

    The family of Deg/HtrA proteases plays an important role in quality control of cellular proteins in a wide range of organisms. In the genome of the cyanobacterium Synechocystis sp. PCC 6803, a model organism for photosynthetic research and renewable energy products, three Deg proteases are encoded, termed HhoA, HhoB and HtrA. In the present study, we compared wild-type (WT) Synechocystis cells with the single insertion mutants ΔhhoA, ΔhhoB and ΔhtrA. Protein expression of the remaining Deg/HtrA proteases was strongly affected in the single insertion mutants. Detailed proteomic studies using DIGE (difference gel electrophoresis) and N-terminal COFRADIC (N-terminal combined fractional diagonal chromatography) revealed that inactivation of a single Deg protease has similar impact on the proteomes of the three mutants; differences to WT were observed in enzymes involved in the major metabolic pathways. Changes in the amount of phosphate permease system Pst-1 were observed only in the insertion mutant ΔhhoB. N-terminal COFRADIC analyses on cell lysates of ΔhhoB confirmed changed amounts of many cell envelope proteins, including the phosphate permease systems, compared with WT. In vitro COFRADIC studies were performed to identify the specificity profiles of the recombinant proteases rHhoA, rHhoB or rHtrA added to the Synechocystis WT proteome. The combined in vivo and in vitro N-terminal COFRADIC datasets propose RbcS as a natural substrate for HhoA, PsbO for HhoB and HtrA and Pbp8 for HtrA. We therefore suggest that each Synechocystis Deg protease protects the cell through different, but connected mechanisms. © The Authors Journal compilation © 2015 Biochemical Society.

  10. Identification of OmpR-Family Response Regulators Interacting with Thioredoxin in the Cyanobacterium Synechocystis sp. PCC 6803

    PubMed Central

    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 (Slr0946) and ManR (Slr1837), were identified as putative Trx targets. 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

  11. 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.

  12. 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

  13. Synechococcus elongatus UTEX 2973, a fast growing cyanobacterial chassis for biosynthesis using light and CO₂.

    PubMed

    Yu, Jingjie; Liberton, Michelle; Cliften, Paul F; Head, Richard D; Jacobs, Jon M; Smith, Richard D; Koppenaal, David W; Brand, Jerry J; Pakrasi, Himadri B

    2015-01-30

    Photosynthetic microbes are of emerging interest as production organisms in biotechnology because they can grow autotrophically using sunlight, an abundant energy source, and CO₂, a greenhouse gas. Important traits for such microbes are fast growth and amenability to genetic manipulation. Here we describe Synechococcus elongatus UTEX 2973, a unicellular cyanobacterium capable of rapid autotrophic growth, comparable to heterotrophic industrial hosts such as yeast. Synechococcus UTEX 2973 can be readily transformed for facile generation of desired knockout and knock-in mutations. Genome sequencing coupled with global proteomics studies revealed that Synechococcus UTEX 2973 is a close relative of the widely studied cyanobacterium Synechococcus elongatus PCC 7942, an organism that grows more than two times slower. A small number of nucleotide changes are the only significant differences between the genomes of these two cyanobacterial strains. Thus, our study has unraveled genetic determinants necessary for rapid growth of cyanobacterial strains of significant industrial potential.

  14. Synechococcus elongatus UTEX 2973, a fast growing cyanobacterial chassis for biosynthesis using light and CO2

    SciTech Connect

    Yu, Jingjie; Liberton, Michelle; Cliften, Paul F.; Head, Richard D.; Jacobs, Jon M.; Smith, Richard D.; Koppenaal, David W.; Brand, Jerry J.; Pakrasi, Himadri B.

    2015-01-30

    Photosynthetic microbes are of emerging interest as production organisms in biotechnology because they can grow autotrophically using sunlight, an abundant energy source, and CO2, a greenhouse gas. Important traits for such microbes are fast growth and amenability to genetic manipulation. Here we describe Synechococcus elongatus UTEX 2973, a unicellular cyanobacterium capable of rapid autotrophic growth, comparable to heterotrophic industrial hosts such as yeast. Synechococcus 2973 can be readily transformed for facile generation of desired knockout and knock-in mutations. Genome sequencing coupled with global proteomics studies revealed that Synechococcus 2973 is a close relative of the widely studied cyanobacterium Synechococcus elongatus PCC 7942, an organism that grows more than two times slower. A small number of nucleotide changes are the only significant differences between the genomes of these two cyanobacterial strains. Thus, our study has unraveled genetic determinants necessary for rapid growth of cyanobacterial strains of significant industrial potential.

  15. Synechococcus elongatus UTEX 2973, a fast growing cyanobacterial chassis for biosynthesis using light and CO2

    DOE PAGES

    Yu, Jingjie; Liberton, Michelle; Cliften, Paul F.; ...

    2015-01-30

    Photosynthetic microbes are of emerging interest as production organisms in biotechnology because they can grow autotrophically using sunlight, an abundant energy source, and CO2, a greenhouse gas. Important traits for such microbes are fast growth and amenability to genetic manipulation. Here we describe Synechococcus elongatus UTEX 2973, a unicellular cyanobacterium capable of rapid autotrophic growth, comparable to heterotrophic industrial hosts such as yeast. Synechococcus 2973 can be readily transformed for facile generation of desired knockout and knock-in mutations. Genome sequencing coupled with global proteomics studies revealed that Synechococcus 2973 is a close relative of the widely studied cyanobacterium Synechococcus elongatusmore » PCC 7942, an organism that grows more than two times slower. A small number of nucleotide changes are the only significant differences between the genomes of these two cyanobacterial strains. Thus, our study has unraveled genetic determinants necessary for rapid growth of cyanobacterial strains of significant industrial potential.« less

  16. 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.

  17. Growth, N2 fixation and photosynthesis in a cyanobacterium, Trichodesmium sp., under Fe stress.

    PubMed

    Fu, Fei-xue; Bell, P R

    2003-04-01

    Trichodesmium sp., isolated from the Great Barrier Reef lagoon, was cultured in artificial seawater media containing a range of Fe concentration. Fe additions stimulated growth, N2 fixation, cellular chlorophyll a content, light-saturated chlorophyll a-specific gross photosynthetic capacity (Pmchl a) and the dark respiration rate (Rdchl a). Cell yields only doubled for 9 nM Fe relative to zero added Fe, whereas N2 fixation increased 11-fold considerably for 450 nM Fe. The results suggest that N2 fixation of Trichodesmium is more sensitive to Fe limitation than are the cell yields.

  18. NADP(+)-isocitrate dehydrogenase from the cyanobacterium Anabaena sp. strain PCC 7120: purification and characterization of the enzyme and cloning, sequencing, and disruption of the icd gene.

    PubMed Central

    Muro-Pastor, M I; Florencio, F J

    1994-01-01

    NADP(+)-isocitrate dehydrogenase (NADP(+)-IDH) from the dinitrogen-fixing filamentous cyanobacterium Anabaena sp. strain PCC 7120 was purified to homogeneity. The native enzyme is composed of two identical subunits (M(r), 57,000) and cross-reacts with antibodies obtained against the previously purified NADP(+)-IDH from the unicellular cyanobacterium Synechocystis sp. strain PCC 6803. Anabaena NADP(+)-IDH resembles in its physicochemical and kinetic parameters the typical dimeric IDHs from prokaryotes. The gene encoding Anabaena NADP(+)-IDH was cloned by complementation of an Escherichia coli icd mutant with an Anabaena genomic library. The complementing DNA was located on a 6-kb fragment. It encodes an NADP(+)-IDH that has the same mobility as that of Anabaena NADP(+)-IDH on nondenaturing polyacrylamide gels. The icd gene was subcloned and sequenced. Translation of the nucleotide sequence gave a polypeptide of 473 amino acids that showed high sequence similarity to the E. coli enzyme (59% identity) and with IDH1 and IDH2, the two subunits of the heteromultimeric NAD(+)-IDH from Saccharomyces cerevisiae (30 to 35% identity); however, a low level of similarity to NADP(+)-IDHs of eukaryotic origin was found (23% identity). Furthermore, Anabaena NADP(+)-IDH contains a 44-residue amino acid sequence in its central region that is absent in the other IDHs so far sequenced. Attempts to generate icd mutants by insertional mutagenesis were unsuccessful, suggesting an essential role of IDH in Anabaena sp. strain PCC 7120. Images PMID:8169222

  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. Control of Nitrogenase mRNA Levels by Products of Nitrate Assimilation in the Cyanobacterium Anabaena sp. Strain PCC 7120 1

    PubMed Central

    Martín-Nieto, José; Herrero, Antonia; Flores, Enrique

    1991-01-01

    Nitrate inhibited nitrogenase synthesis and heterocyst development in the cyanobacterium Anabaena sp. strain PCC 7120. Inhibition of dinitrogen fixation by nitrate did not take place, however, in nitrate reductase-deficient derivatives of this strain. Hybridization of total RNA isolated from cells grown on different nitrogen sources with an internal fragment of the nifD gene showed that regulation of nitrogenase activity by nitrate is exerted through a negative control of the nitrogenase mRNA levels. ImagesFigure 1Figure 2 PMID:16668475

  1. Sigma factor genes sigC, sigE, and sigG are upregulated in heterocysts of the cyanobacterium Anabaena sp. strain PCC 7120.

    PubMed

    Aldea, M Ramona; Mella-Herrera, Rodrigo A; Golden, James W

    2007-11-01

    We used gfp transcriptional fusions to investigate the regulation of eight sigma factor genes during heterocyst development in the cyanobacterium Anabaena sp. strain PCC 7120. Reporter strains containing gfp fusions with the upstream regions of sigB2, sigD, sigI, and sigJ did not show developmental regulation. Time-lapse microscopy of sigC, sigE, and sigG reporter strains showed increased green fluorescent protein fluorescence in differentiating cells at 4 h, 16 h, and 9 h, respectively, after nitrogen step down.

  2. Compositional and toxicological evaluation of the diazotrophic cyanobacterium, Cyanothece sp. strain ATCC 51142

    NASA Technical Reports Server (NTRS)

    Schneegurt, M. A.; Arieli, B.; McKeehen, J. D.; Stephens, S. D.; Nielsen, S. S.; Saha, P. R.; Trumbo, P. R.; Sherman, L. A.; Mitchell, C. A. (Principal Investigator)

    1995-01-01

    Compositional analyses of Cyanothece sp. strain ATCC 51142 showed high protein (50-60%) and low fat (0.4-1%) content, and the ability to synthesize vitamin B12. The amino acid profile indicated that Cyanothece sp. was a balanced protein source. Fatty acids of the 18:3n-3 type were also present. Mineral analyses indicated that the cellular biomass may be a good source of Fe, Zn and Na. Caloric content was 4.5 to 5.1 kcal g dry weight-1 and the carbon content was approximately 40% on a dry weight basis. Nitrogen content was 8 to 9% on a dry weight basis and total nucleic acids were 1.3% on a dry weight basis. Short-term feeding studies in rats followed by histopathology found no toxicity or dietary incompatibility problems. The level of uric acid and allantoin in urine and tissues was low, suggesting no excess of nucleic acids, as sometimes reported in the past for a cyanobacteria-containing diet. The current work discusses the potential implications of these results for human nutrition applications.

  3. Molecular investigation of the radiation resistance of edible cyanobacterium Arthrospira sp. PCC 8005

    PubMed Central

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

    2015-01-01

    The aim of this work was to characterize in detail the response of Arthrospira to ionizing radiation, to better understand its radiation resistance capacity. Live cells of Arthrospira sp. PCC 8005 were irradiated with 60Co gamma rays. This study is the first, showing that Arthrospira is highly tolerant to gamma rays, and can survive at least 6400 Gy (dose rate of 527 Gy h−1), which identified Arthrospira sp. PCC 8005 as a radiation resistant bacterium. Biochemical, including proteomic and transcriptomic, analysis after irradiation with 3200 or 5000 Gy showed a decline in photosystem II quantum yield, reduced carbon fixation, and reduced pigment, lipid, and secondary metabolite synthesis. Transcription of photo-sensing and signaling pathways, and thiol-based antioxidant systems was induced. Transcriptomics did show significant activation of ssDNA repair systems and mobile genetic elements (MGEs) at the RNA level. Surprisingly, the cells did not induce the classical antioxidant or DNA repair systems, such superoxide dismutase (SOD) enzyme and the RecA protein. Arthrospira cells lack the catalase gene and the LexA repressor. Irradiated Arthrospira cells did induce strongly a group of conserved proteins, of which the function in radiation resistance remains to be elucidated, but which are a promising novel routes to be explored. This study revealed the radiation resistance of Arthrospira, and the molecular systems involved, paving the way for its further and better exploitation. PMID:25678338

  4. Phototaxis in the cyanobacterium Synechocystis sp. PCC 6803: role of different photoreceptors.

    PubMed

    Fiedler, Brita; Börner, Thomas; Wilde, Annegret

    2005-01-01

    The second cyanobacterial phytochrome Cph2 from Synechocystis sp. PCC 6803 was suggested as a part of a light-stimulated signal transduction chain inhibiting movement toward blue light. Cph2 has the two bilin binding sites, cysteine-129 and cysteine-1022, that might be involved in sensing of red/far-red and blue light, respectively. Here, we present data on wavelength dependence of the phototaxis inhibition under blue light, indicating that Cph2 itself is the photoreceptor for this blue light response. We found that inhibition of blue-light phototaxis in wild-type cells occurred below the transition point of about 470 nm. Substitution of cysteine-1022 with valine led to photomovement of the cells toward blue light (cph2(-) mutant phenotype). Analysis of mutants lacking cysteine-129 in the N-terminal chromophore binding domain indicated that this domain is also important for Cph2 function or folding of the protein. Furthermore, putative blue-light and phytochrome-like photoreceptors encoded by the Synechocystis sp. PCC 6803 genome were inactivated in wild-type and cph2 knockout mutant background. Our results suggest that none of these potential photoreceptors interfere with Cph2 function, although inactivation of taxD1 as well as slr1694 encoding a BLUF protein led to cells that reversed the direction of movement under blue light illumination in mutant strains of cph2.

  5. Feeding characteristics of a golden alga (Poterioochromonas sp.) grazing on toxic cyanobacterium Microcystis aeruginosa.

    PubMed

    Zhang, Xue; Hu, Hong-Ying; Men, Yu-Jie; Yang, Jia; Christoffersen, Kirsten

    2009-07-01

    Microcystis aeruginosa has quickly risen in infamy as one of the most universal and toxic bloom-forming cyanobacteria. Here we presented a species of golden alga (Poterioochromonas sp. strain ZX1), which can feed on toxic M. aeruginosa without any adverse effects from the cyanotoxins. Using flow cytometry, the ingestion and maximal digestion rates were estimated to be 0.2 approximately 1.2 and 0.2 M. aeruginosa cells (ZX1 cell)(-1)h(-1), respectively. M. aeruginosa in densities below 10(7)cells mL(-1) could be grazed down by ZX1, but no significant decrease was observed when the initial density was 3.2 x 10(7)cells mL(-1). ZX1 grazing was a little influenced by the light intensity (0.5 approximately 2500l x) and initial pH of the medium (pH=5.0 approximately 9.5). ZX1 could not survive in continuous darkness for longer than 10 days. The pH value was adjusted to 8 by ZX1 while to 10 by M. aeruginosa. This study may shed light on understanding the ecological interactions between M. aeruginosa and mixotrophic Poterioochromonas sp. in aquatic ecosystems.

  6. Compositional and toxicological evaluation of the diazotrophic cyanobacterium, Cyanothece sp. strain ATCC 51142

    NASA Technical Reports Server (NTRS)

    Schneegurt, M. A.; Arieli, B.; McKeehen, J. D.; Stephens, S. D.; Nielsen, S. S.; Saha, P. R.; Trumbo, P. R.; Sherman, L. A.; Mitchell, C. A. (Principal Investigator)

    1995-01-01

    Compositional analyses of Cyanothece sp. strain ATCC 51142 showed high protein (50-60%) and low fat (0.4-1%) content, and the ability to synthesize vitamin B12. The amino acid profile indicated that Cyanothece sp. was a balanced protein source. Fatty acids of the 18:3n-3 type were also present. Mineral analyses indicated that the cellular biomass may be a good source of Fe, Zn and Na. Caloric content was 4.5 to 5.1 kcal g dry weight-1 and the carbon content was approximately 40% on a dry weight basis. Nitrogen content was 8 to 9% on a dry weight basis and total nucleic acids were 1.3% on a dry weight basis. Short-term feeding studies in rats followed by histopathology found no toxicity or dietary incompatibility problems. The level of uric acid and allantoin in urine and tissues was low, suggesting no excess of nucleic acids, as sometimes reported in the past for a cyanobacteria-containing diet. The current work discusses the potential implications of these results for human nutrition applications.

  7. The versatile TolC-like Slr1270 in the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Oliveira, Paulo; Martins, Nuno M; Santos, Marina; Pinto, Filipe; Büttel, Zsófia; Couto, Narciso A S; Wright, Phillip C; Tamagnini, Paula

    2016-02-01

    Here we report on the functional characterization of the hypothetical protein Slr1270, a TolC homologue in Synechocystis sp. PCC 6803. Analysis of a slr1270 insertion deletion mutant and respective wild-type revealed that the mutant presents increased susceptibility to antibiotics. In addition, a detailed study of the exoproteome showed that Slr1270 mediates protein secretion. Among the protein substrates dependent on Slr1270 function, we found the S-layer structural component. Electron microscopy studies of the slr1270 mutant showed that the S-layer is indeed absent. The requirement of functional Slr1270 for protein secretion and drug resistance mechanisms suggests that Slr1270 plays a role similar to that described for TolC in other bacteria. Additional phenotypic traits could also be observed, including slower growth rates at low temperature, impairment in biofilm formation and increased activity of enzymes detoxifying reactive oxygen species. Furthermore, an increased capacity of outer membrane vesicles (OMVs) formation and release was also found in the slr1270 mutant, a feature that has not yet been observed in bacteria lacking TolC. This work highlights the marked physiological fitness that the TolC-like Slr1270 bestows to the photosynthetic model Synechocystis sp. PCC 6803 and presents a valuable model for studying OMVs formation and release. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  8. A novel periplasmic protein (Slr0280) tunes photomixotrophic growth of the cyanobacterium, Synechocystis sp. PCC 6803.

    PubMed

    Dong, Liang-Liang; Li, Qing-Dong; Wu, Dong; Sun, Ya-Fang; Zhou, Ming; Zhao, Kai-Hong

    2016-01-10

    Cyanobacteria are among the main contributors to global photosynthesis and show a high degree of metabolic plasticity. Synechocystis sp. PCC 6803 can grow under photoautotrophic, photomixotrophic or photoheterotrophic conditions. We have characterized a novel periplasmic protein (Slr0280) that tunes the photomixotrophic growth of Synechocystis sp. PCC 6803. Slr0280 is a multi-domain protein consisting mainly of β-sheets. Several proteins that interact with Slr0280 were identified via bacterial two-hybrid screening. Slr0280 may interact through its DUF2233 domain with partners that participate in sugar metabolism, thereby coordinating the respective regulations. When slr0280 was deleted, the mutant grew more slowly than wild-type in the presence of glucose, which is ascribed to the down-regulation of glycolysis, glycogen catabolism, oxidative pentose phosphate pathway, Calvin cycle and glucose utilization. A positive regulation of Slr0280 on these sugar catabolic enzymes was confirmed by transcript (qPCR) analyses. Based on these findings, we proposed a speculative model that Slr0280 plays a coordinating regulatory role in sugar metabolism. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Photosynthetic Versatility in the Genome of Geitlerinema sp. PCC 9228 (Formerly Oscillatoria limnetica 'Solar Lake'), a Model Anoxygenic Photosynthetic Cyanobacterium.

    PubMed

    Grim, Sharon L; Dick, Gregory J

    2016-01-01

    Anoxygenic cyanobacteria that use sulfide as the electron donor for photosynthesis are a potentially influential but poorly constrained force on Earth's biogeochemistry. Their versatile metabolism may have boosted primary production and nitrogen cycling in euxinic coastal margins in the Proterozoic. In addition, they represent a biological mechanism for limiting the accumulation of atmospheric oxygen, especially before the Great Oxidation Event and in the low-oxygen conditions of the Proterozoic. In this study, we describe the draft genome sequence of Geitlerinema sp. PCC 9228, formerly Oscillatoria limnetica 'Solar Lake', a mat-forming diazotrophic cyanobacterium that can switch between oxygenic photosynthesis and sulfide-based anoxygenic photosynthesis (AP). Geitlerinema possesses three variants of psbA, which encodes protein D1, a core component of the photosystem II reaction center. Phylogenetic analyses indicate that one variant is closely affiliated with cyanobacterial psbA genes that code for a D1 protein used for oxygen-sensitive processes. Another version is phylogenetically similar to cyanobacterial psbA genes that encode D1 proteins used under microaerobic conditions, and the third variant may be cued to high light and/or elevated oxygen concentrations. Geitlerinema has the canonical gene for sulfide quinone reductase (SQR) used in cyanobacterial AP and a putative transcriptional regulatory gene in the same operon. Another operon with a second, distinct sqr and regulatory gene is present, and is phylogenetically related to sqr genes used for high sulfide concentrations. The genome has a comprehensive nif gene suite for nitrogen fixation, supporting previous observations of nitrogenase activity. Geitlerinema possesses a bidirectional hydrogenase rather than the uptake hydrogenase typically used by cyanobacteria in diazotrophy. Overall, the genome sequence of Geitlerinema sp. PCC 9228 highlights potential cyanobacterial strategies to cope with fluctuating

  10. Identification and characterization of a carboxysomal γ-carbonic anhydrase from the cyanobacterium Nostoc sp. PCC 7120.

    PubMed

    de Araujo, Charlotte; Arefeen, Dewan; Tadesse, Yohannes; Long, Benedict M; Price, G Dean; Rowlett, Roger S; Kimber, Matthew S; Espie, George S

    2014-09-01

    Carboxysomes are proteinaceous microcompartments that encapsulate carbonic anhydrase (CA) and ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco); carboxysomes, therefore, catalyze reversible HCO3 (-) dehydration and the subsequent fixation of CO2. The N- and C-terminal domains of the β-carboxysome scaffold protein CcmM participate in a network of protein-protein interactions that are essential for carboxysome biogenesis, organization, and function. The N-terminal domain of CcmM in the thermophile Thermosynechococcus elongatus BP-1 is also a catalytically active, redox regulated γ-CA. To experimentally determine if CcmM from a mesophilic cyanobacterium is active, we cloned, expressed and purified recombinant, full-length CcmM from Nostoc sp. PCC 7120 as well as the N-terminal 209 amino acid γ-CA-like domain. Both recombinant proteins displayed ethoxyzolamide-sensitive CA activity in mass spectrometric assays, as did the carboxysome-enriched TP fraction. NstCcmM209 was characterized as a moderately active and efficient γ-CA with a k cat of 2.0 × 10(4) s(-1) and k cat/K m of 4.1 × 10(6) M(-1) s(-1) at 25 °C and pH 8, a pH optimum between 8 and 9.5 and a temperature optimum spanning 25-35 °C. NstCcmM209 also catalyzed the hydrolysis of the CO2 analog carbonyl sulfide. Circular dichroism and intrinsic tryptophan fluorescence analysis demonstrated that NstCcmM209 was progressively and irreversibly denatured above 50 °C. NstCcmM209 activity was inhibited by the reducing agent tris(hydroxymethyl)phosphine, an effect that was fully reversed by a molar excess of diamide, a thiol oxidizing agent, consistent with oxidative activation being a universal regulatory mechanism of CcmM orthologs. Immunogold electron microscopy and Western blot analysis of TP pellets indicated that Rubisco and CcmM co-localize and are concentrated in Nostoc sp. PCC 7120 carboxysomes.

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

    SciTech Connect

    Overbeek, Ross; Fonstein, Veronika; Osterman, Andrei; Gerdes, Svetlana; Vassieva, Olga; Zagnitko, Olga; Rodionov, Dmitry

    2005-02-15

    The team of the Fellowship for Interpretation of Genomes (FIG) under the leadership of Ross Overbeek, began working on this Project in November 2003. During the previous year, the Project was performed at Integrated Genomics Inc. A transition from the industrial environment to the public domain prompted us to adjust some aspects of the Project. Notwithstanding the challenges, we believe that these adjustments had a strong positive impact on our deliverables. Most importantly, the work of the research team led by R. Overbeek resulted in the deployment of a new open source genomic platform, the SEED (Specific Aim 1). This platform provided a foundation for the development of CyanoSEED a specialized portal to comparative analysis and metabolic reconstruction of all available cyanobacterial genomes (Specific Aim 3). The SEED represents a new generation of software for genome analysis. Briefly, it is a portable and extendable system, containing one of the largest and permanently growing collections of complete and partial genomes. The complete system with annotations and tools is freely available via browsing or via installation on a user's Mac or Linux computer. One of the important unique features of the SEED is the support of metabolic reconstruction and comparative genome analysis via encoding and projection of functional subsystems. During the project period, the FIG research team has validated the new software by developing a significant number of core subsystems, covering many aspects of central metabolism (Specific Aim 2), as well as metabolic areas specific for cyanobacteria and other photoautotrophic organisms (Specific Aim 3). In addition to providing a proof of technology and a starting point for further community-based efforts, these subsystems represent a valuable asset. An extensive coverage of central metabolism provides the bulk of information required for metabolic modeling in Synechocystis sp.PCC 6803. Detailed analysis of several subsystems covering

  12. Transcriptomic response to prolonged ethanol production in the cyanobacterium Synechocystis sp. PCC6803

    PubMed Central

    2014-01-01

    Background The production of biofuels in photosynthetic microalgae and cyanobacteria is a promising alternative to the generation of fuels from fossil resources. To be economically competitive, producer strains need to be established that synthesize the targeted product at high yield and over a long time. Engineering cyanobacteria into forced fuel producers should considerably interfere with overall cell homeostasis, which in turn might counteract productivity and sustainability of the process. Therefore, in-depth characterization of the cellular response upon long-term production is of high interest for the targeted improvement of a desired strain. Results The transcriptome-wide response to continuous ethanol production was examined in Synechocystis sp. PCC6803 using high resolution microarrays. In two independent experiments, ethanol production rates of 0.0338% (v/v) ethanol d-1 and 0.0303% (v/v) ethanol d-1 were obtained over 18 consecutive days, measuring two sets of biological triplicates in fully automated photobioreactors. Ethanol production caused a significant (~40%) delay in biomass accumulation, the development of a bleaching phenotype and a down-regulation of light harvesting capacity. However, microarray analyses performed at day 4, 7, 11 and 18 of the experiment revealed only three mRNAs with a strongly modified accumulation level throughout the course of the experiment. In addition to the overexpressed adhA (slr1192) gene, this was an approximately 4 fold reduction in cpcB (sll1577) and 3 to 6 fold increase in rps8 (sll1809) mRNA levels. Much weaker modifications of expression level or modifications restricted to day 18 of the experiment were observed for genes involved in carbon assimilation (Ribulose bisphosphate carboxylase and Glutamate decarboxylase). Molecular analysis of the reduced cpcB levels revealed a post-transcriptional processing of the cpcBA operon mRNA leaving a truncated mRNA cpcA* likely not competent for translation. Moreover

  13. Transcriptomic response to prolonged ethanol production in the cyanobacterium Synechocystis sp. PCC6803.

    PubMed

    Dienst, Dennis; Georg, Jens; Abts, Thomas; Jakorew, Lew; Kuchmina, Ekaterina; Börner, Thomas; Wilde, Annegret; Dühring, Ulf; Enke, Heike; Hess, Wolfgang R

    2014-02-06

    The production of biofuels in photosynthetic microalgae and cyanobacteria is a promising alternative to the generation of fuels from fossil resources. To be economically competitive, producer strains need to be established that synthesize the targeted product at high yield and over a long time. Engineering cyanobacteria into forced fuel producers should considerably interfere with overall cell homeostasis, which in turn might counteract productivity and sustainability of the process. Therefore, in-depth characterization of the cellular response upon long-term production is of high interest for the targeted improvement of a desired strain. The transcriptome-wide response to continuous ethanol production was examined in Synechocystis sp. PCC6803 using high resolution microarrays. In two independent experiments, ethanol production rates of 0.0338% (v/v) ethanol d-1 and 0.0303% (v/v) ethanol d-1 were obtained over 18 consecutive days, measuring two sets of biological triplicates in fully automated photobioreactors. Ethanol production caused a significant (~40%) delay in biomass accumulation, the development of a bleaching phenotype and a down-regulation of light harvesting capacity. However, microarray analyses performed at day 4, 7, 11 and 18 of the experiment revealed only three mRNAs with a strongly modified accumulation level throughout the course of the experiment. In addition to the overexpressed adhA (slr1192) gene, this was an approximately 4 fold reduction in cpcB (sll1577) and 3 to 6 fold increase in rps8 (sll1809) mRNA levels. Much weaker modifications of expression level or modifications restricted to day 18 of the experiment were observed for genes involved in carbon assimilation (Ribulose bisphosphate carboxylase and Glutamate decarboxylase). Molecular analysis of the reduced cpcB levels revealed a post-transcriptional processing of the cpcBA operon mRNA leaving a truncated mRNA cpcA* likely not competent for translation. Moreover, western blots and zinc

  14. Genomic Responses to Arsenic in the Cyanobacterium Synechocystis sp. PCC 6803

    PubMed Central

    Sánchez-Riego, Ana María; López-Maury, Luis; Florencio, Francisco Javier

    2014-01-01

    Arsenic is a ubiquitous contaminant and a toxic metalloid which presents two main redox states in nature: arsenite [AsIII] and arsenate [AsV]. Arsenic resistance in Synechocystis sp. strain PCC 6803 is mediated by the arsBHC operon and two additional arsenate reductases encoded by the arsI1 and arsI2 genes. Here we describe the genome-wide responses to the presence of arsenate and arsenite in wild type and mutants in the arsenic resistance system. Both forms of arsenic produced similar responses in the wild type strain, including induction of several stress related genes and repression of energy generation processes. These responses were transient in the wild type strain but maintained in time in an arsB mutant strain, which lacks the arsenite transporter. In contrast, the responses observed in a strain lacking all arsenate reductases were somewhat different and included lower induction of genes involved in metal homeostasis and Fe-S cluster biogenesis, suggesting that these two processes are targeted by arsenite in the wild type strain. Finally, analysis of the arsR mutant strain revealed that ArsR seems to only control 5 genes in the genome. Furthermore, the arsR mutant strain exhibited hypersentivity to nickel, copper and cadmium and this phenotype was suppressed by mutation in arsB but not in arsC gene suggesting that overexpression of arsB is detrimental in the presence of these metals in the media. PMID:24797411

  15. Electron Transport Controls Glutamine Synthetase Activity in the Facultative Heterotrophic Cyanobacterium Synechocystis sp. PCC 6803.

    PubMed Central

    Reyes, J. C.; Crespo, J. L.; Garcia-Dominguez, M.; Florencio, F. J.

    1995-01-01

    Glutamine synthetase (GS) from Synechocystis sp. PCC 6803 was inactivated in vivo by transferring cells from light to darkness or by incubation with the photosynthetic inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea but not with 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone. Addition of glucose prevented both dark and 3-(3,4-dichlorophenyl)-1,1-dimethylurea GS inactivation. In a Synechocystis psbE-psbF mutant (T1297) lacking photosystem II, glucose was required to maintain active GS, even in the light. However, in nitrogen-starved T1297 cells the removal of glucose did not affect GS activity. The fact that dark-inactivated GS was reactivated in vitro by the same treatments that reactivate the ammonium-inactivated GS points out that both nitrogen metabolism and redox state of the cells lead to the same molecular regulatory mechanism in the control of GS activity. Using GS antibodies we detected that dark-inactivated GS displayed a different electrophoretic migration with respect to the active form in nondenaturing polyacrylamide gel electrophoresis but not in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The possible pathway to modulate GS activity by the electron transport flow in Synechocystis cells is discussed. PMID:12228640

  16. Minutissamides E - L, antiproliferative cyclic lipodecapeptides from the cultured freshwater cyanobacterium cf. Anabaena sp

    PubMed Central

    Kang, Hahk-Soo; Sturdy, Megan; Krunic, Aleksej; Kim, Hyunjung; Shen, Qi; Swanson, Steven M.; Orjala, Jimmy

    2012-01-01

    The extract of UIC 10035, a strain obtained from a sample collected near the town of Homestead, south Florida, showed antiproliferative activity against MDA-MB-435 cells. Bioassay-guided fractionation led to the isolation of a series of cyclic lipodecapeptides, named minutissamides E - L (1 – 8). The planar structures were determined by analysis of HRESIMS, tandem MS, and 1D and 2D NMR data, and the stereoconfigurations were assigned by LC-MS analysis of the Marfey's derivatives after acid hydrolysis. Minutissamides E - L (1 – 8) exhibited antiproliferative activity against MDA-MB-435 cells with IC50 values ranging between 1 and 10 μM. The structures of minutissamides E - L (1 – 8) were closely related with those of the previously reported lipopeptides, puwainaphycins A - E and minutissamides A - D, characterized by the presence of a lipophilic -amino acid and three non-standard amino acids NMeAsn, OMeThr and Dhb (, -dehydro- -aminobutyric acid). The strain UIC 10035 was designated as cf. Anabaena sp. on the basis of morphological and 16S rRNA gene sequence analyses. PMID:22980217

  17. Homology modeling and functional sites prediction of azoreductase enzyme from the cyanobacterium Nostoc sp. PCC7120.

    PubMed

    Devi, Philem Priyadarshini; Adhikari, Samrat

    2012-12-01

    Industrial dyes such as azodyes are potential environmental pollutants causing deleterious health hazards complications. These dyes are potentially degraded by azoreductase enzyme which is widely distributed in bacteria and also cyanobacteria. The azoreductase enzymes from cyanobacteria have not been explored in detail. Hence this enzyme from Nostoc sp. PCC 7120 has been addressed in detail in the present study considering to explore the physico-chemical properties, evolutionary relationships, functional sites and structural properties using various bioinformatics tools. Four conserved regions were obtained from the multiple sequence analysis. The multiple sequence alignment showed conserved regions at different stretches from 1-11, 40-57, 82-120 and 161-177 amino acid residues. These regions could be used for designing degenerate primers or probes for PCR-based amplification or hybridization-based detection of azoreductase sequences from different source organisms. Domain analysis and functional site prediction showed the presence of functional sites and domain such as flavodoxin like fold responsible for enzyme activity. 3D model was constructed and the best model was selected and validated. Superimposition of the final structure and the template showed variations in certain regions which might be involved in the accommodation of various dyes. Our results may be helpful for further investigations like docking studies as well as in vivo and in vitro conditions although these predictions still need to be studied.

  18. Raman spectroscopic analysis of the responds of desert cyanobacterium Nostoc sp under UV-B radiation

    NASA Astrophysics Data System (ADS)

    Wang, Gaohong; Hao, Zongjie; Hu, Chunxiang; Liu, Yongding

    Cyanobacteria are renowned for tolerating extremes of desiccation, UV radiation, freezethaw cycles, hypersalinity and oligotrophy, which make them as candidate par excellence for terraforming in extraterrestrial planet. Recently Raman spectrum was applied to study the biochemical information changes in different field of life science. In this study, we investigated the respond of desert cyanobactreium Nostoc sp under UV-B radiation via FT-Raman spectra. It was found that the spectral biomarkers of protectant molecular of UV radiation such as β-carotene and scytonemin were induced by UV-B radiation, but Chlorophyll a content was decreased, and also the photosynthesis activity was inhibited significantly. After light adaptation without UV-B radiation, the Chlorophyll a content and photosynthesis activity returned to high level, butβ-carotene and scytonemin content remained in the cells. Those results indicated that desert Cyanobacteria have good adaptation ability for UV-B radiation and synthesis of protectant molecular may be an effective strategy for its adaptation in evolution.

  19. Cellular Dynamics Drives the Emergence of Supracellular Structure in the Cyanobacterium, Phormidium sp. KS

    PubMed Central

    Sato, Naoki; Katsumata, Yutaro; Sato, Kaoru; Tajima, Naoyuki

    2014-01-01

    Motile filamentous cyanobacteria, such as Oscillatoria, Phormidium and Arthrospira, are ubiquitous in terrestrial and aquatic environments. As noted by Nägeli in 1860, many of them form complex three-dimensional or two-dimensional structures, such as biofilm, weed-like thalli, bundles of filaments and spirals, which we call supracellular structures. In all of these structures, individual filaments incessantly move back and forth. The structures are, therefore, macroscopic, dynamic structures that are continuously changing their microscopic arrangement of filaments. In the present study, we analyzed quantitatively the movement of individual filaments of Phormidium sp. KS grown on agar plates. Junctional pores, which have been proposed to drive cell movement by mucilage/slime secretion, were found to align on both sides of each septum. The velocity of movement was highest just after the reversal of direction and, then, attenuated exponentially to a final value before the next reversal of direction. This kinetics is compatible with the “slime gun” model. A higher agar concentration restricts the movement more severely and, thus, resulted in more spiral formation. The spiral is a robust form compatible with non-homogeneous movements of different parts of a long filament. We propose a model of spiral formation based on the microscopic movement of filaments. PMID:25460162

  20. Genomic analysis of parallel-evolved cyanobacterium Synechocystis sp. PCC 6803 under acid stress.

    PubMed

    Uchiyama, Junji; Kanesaki, Yu; Iwata, Naoya; Asakura, Ryousuke; Funamizu, Kento; Tasaki, Rizumu; Agatsuma, Mina; Tahara, Hiroko; Matsuhashi, Ayumi; Yoshikawa, Hirofumi; Ogawa, Satoru; Ohta, Hisataka

    2015-08-01

    Experimental evolution is a powerful tool for clarifying phenotypic and genotypic changes responsible for adaptive evolution. In this study, we isolated acid-adapted Synechocystis sp. PCC 6803 (Synechocystis 6803) strains to identify genes involved in acid tolerance. Synechocystis 6803 is rarely found in habitants with pH < 5.75. The parent (P) strain was cultured in BG-11 at pH 6.0. We gradually lowered the pH of the medium from pH 6.0 to pH 5.5 over 3 months. Our adapted cells could grow in acid stress conditions at pH 5.5, whereas the parent cells could not. We performed whole-genome sequencing and compared the acid-adapted and P strains, thereby identifying 11 SNPs in the acid-adapted strains, including in Fo F1-ATPase. To determine whether the SNP genes responded to acid stress, we examined gene expression in the adapted strains using quantitative reverse-transcription polymerase chain reaction. sll0914, sll1496, sll0528, and sll1144 expressions increased under acid stress in the P strain, whereas sll0162, sll0163, slr0623, and slr0529 expressions decreased. There were no differences in the SNP genes expression levels between the P strain and two adapted strains, except for sll0528. These results suggest that SNPs in certain genes are involved in acid stress tolerance in Synechocystis 6803.

  1. Electron Transport Controls Glutamine Synthetase Activity in the Facultative Heterotrophic Cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Reyes, J. C.; Crespo, J. L.; Garcia-Dominguez, M.; Florencio, F. J.

    1995-11-01

    Glutamine synthetase (GS) from Synechocystis sp. PCC 6803 was inactivated in vivo by transferring cells from light to darkness or by incubation with the photosynthetic inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea but not with 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone. Addition of glucose prevented both dark and 3-(3,4-dichlorophenyl)-1,1-dimethylurea GS inactivation. In a Synechocystis psbE-psbF mutant (T1297) lacking photosystem II, glucose was required to maintain active GS, even in the light. However, in nitrogen-starved T1297 cells the removal of glucose did not affect GS activity. The fact that dark-inactivated GS was reactivated in vitro by the same treatments that reactivate the ammonium-inactivated GS points out that both nitrogen metabolism and redox state of the cells lead to the same molecular regulatory mechanism in the control of GS activity. Using GS antibodies we detected that dark-inactivated GS displayed a different electrophoretic migration with respect to the active form in nondenaturing polyacrylamide gel electrophoresis but not in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The possible pathway to modulate GS activity by the electron transport flow in Synechocystis cells is discussed.

  2. Impacts of diurnal variation of ultraviolet-B and photosynthetically active radiation on phycobiliproteins of the hot-spring cyanobacterium Nostoc sp. strain HKAR-2.

    PubMed

    Kannaujiya, Vinod K; Sinha, Rajeshwar P

    2017-01-01

    The effects of diurnal variation of photosynthetically active radiation (PAR; 400-700 nm) and ultraviolet-B (UV-B; 280-315 nm) radiation on phycobiliproteins (PBPs) and photosynthetic pigments (PP) have been studied in the hot-spring cyanobacterium Nostoc sp. strain HKAR-2. The variations in PBPs and PP were monitored by alternating light and dark under PAR, UV-B, and PAR + UV-B radiations over a period of 25 h. There was a decline in the amount of Chl a and PBPs during light periods of UV-B and PAR + UV-B and an increase during dark periods showing a circadian rhythm by destruction and resynthesis of pigment-protein complex. However, a marked induction in carotenoids was recorded during light periods of the same radiations. Moreover, the ratio of Chl a/PE and Chl a/PC was increased in dark periods showing the resynthesis of bleached Chl a. The wavelength shift in emission fluorescence of PBPs toward shorter wavelengths further indicated the bleaching and destruction of PBPs during light periods. Oxidative damage upon exposure to PAR, UV-B, and PAR + UV-B was alleviated by induction of antioxidative enzymes such as superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX). The studied cyanobacterium exhibits a significant increase in the activities of SOD, CAT, and APX upon exposure to UV-B and PAR + UV-B radiations. The results indicate that pigment-protein composition of Nostoc sp. stain HKAR-2 was significantly altered during diurnal variation of light/radiation, which might play an important role in optimization for their productivity in a particular cyanobacterium.

  3. Dimeric chlorite dismutase from the nitrogen-fixing cyanobacterium Cyanothece sp. PCC7425.

    PubMed

    Schaffner, Irene; Hofbauer, Stefan; Krutzler, Michael; Pirker, Katharina F; Bellei, Marzia; Stadlmayr, Gerhard; Mlynek, Georg; Djinovic-Carugo, Kristina; Battistuzzi, Gianantonio; Furtmüller, Paul G; Daims, Holger; Obinger, Christian

    2015-06-01

    It is demonstrated that cyanobacteria (both azotrophic and non-azotrophic) contain heme b oxidoreductases that can convert chlorite to chloride and molecular oxygen (incorrectly denominated chlorite 'dismutase', Cld). Beside the water-splitting manganese complex of photosystem II, this metalloenzyme is the second known enzyme that catalyses the formation of a covalent oxygen-oxygen bond. All cyanobacterial Clds have a truncated N-terminus and are dimeric (i.e. clade 2) proteins. As model protein, Cld from Cyanothece sp. PCC7425 (CCld) was recombinantly produced in Escherichia coli and shown to efficiently degrade chlorite with an activity optimum at pH 5.0 [kcat 1144 ± 23.8 s(-1), KM 162 ± 10.0 μM, catalytic efficiency (7.1 ± 0.6) × 10(6) M(-1) s(-1)]. The resting ferric high-spin axially symmetric heme enzyme has a standard reduction potential of the Fe(III)/Fe(II) couple of -126 ± 1.9 mV at pH 7.0. Cyanide mediates the formation of a low-spin complex with k(on)  = (1.6 ± 0.1) × 10(5) M(-1) s(-1) and k(off) = 1.4 ± 2.9 s(-1) (KD ∼ 8.6 μM). Both, thermal and chemical unfolding follows a non-two-state unfolding pathway with the first transition being related to the release of the prosthetic group. The obtained data are discussed with respect to known structure-function relationships of Clds. We ask for the physiological substrate and putative function of these O2 -producing proteins in (nitrogen-fixing) cyanobacteria. © 2015 The Authors. Molecular Microbiology published by John Wiley & Sons Ltd.

  4. Molecular characterization of a novel peroxidase from the cyanobacterium Anabaena sp. strain PCC 7120.

    PubMed

    Ogola, Henry Joseph Oduor; Kamiike, Takaaki; Hashimoto, Naoya; Ashida, Hiroyuki; Ishikawa, Takahiro; Shibata, Hitoshi; Sawa, Yoshihiro

    2009-12-01

    The open reading frame alr1585 of Anabaena sp. strain PCC 7120 encodes a heme-dependent peroxidase (Anabaena peroxidase [AnaPX]) belonging to the novel DyP-type peroxidase family (EC 1.11.1.X). We cloned and heterologously expressed the active form of the enzyme in Escherichia coli. The purified enzyme was a 53-kDa tetrameric protein with a pI of 3.68, a low pH optima (pH 4.0), and an optimum reaction temperature of 35 degrees C. Biochemical characterization revealed an iron protoporphyrin-containing heme peroxidase with a broad specificity for aromatic substrates such as guaiacol, 4-aminoantipyrine and pyrogallol. The enzyme efficiently catalyzed the decolorization of anthraquinone dyes like Reactive Blue 5, Reactive Blue 4, Reactive Blue 114, Reactive Blue 119, and Acid Blue 45 with decolorization rates of 262, 167, 491, 401, and 256 muM.min(-1), respectively. The apparent K(m) and k(cat)/K(m) values for Reactive Blue 5 were 3.6 muM and 1.2 x 10(7) M(-1) s(-1), respectively, while the apparent K(m) and k(cat)/K(m) values for H(2)O(2) were 5.8 muM and 6.6 x 10(6) M(-1) s(-1), respectively. In contrast, the decolorization activity of AnaPX toward azo dyes was relatively low but was significantly enhanced 2- to approximately 50-fold in the presence of the natural redox mediator syringaldehyde. The specificity and catalytic efficiency for hydrogen donors and synthetic dyes show the potential application of AnaPX as a useful alternative of horseradish peroxidase or fungal DyPs. To our knowledge, this study represents the only extensive report in which a bacterial DyP has been tested in the biotransformation of synthetic dyes.

  5. Analysis of carbohydrate storage granules in the diazotrophic cyanobacterium Cyanothece sp. PCC 7822

    SciTech Connect

    Welkie, David G.; Sherman, Debra M.; Chrisler, William B.; Orr, Galya; Sherman, Louis A.

    2013-10-19

    The unicellular diazotrophic cyanobacteria of the genus Cyanothece demonstrate oscillations in nitrogenase activity and H2 production when grown under 12h light-12h dark cycles. We established that Cyanothece sp. PCC 7822 allows for the construction of knock-out mutants and our objective was to improve the growth characteristics of this strain and to identify the nature of the intracellular storage granules. We report the physiological and morphological effects of reduction in nitrate and phosphate concentrations in BG-11 media on this strain. We developed a series of BG-11-derived growth media and monitored batch culture growth, nitrogenase activity and nitrogenase-mediated hydrogen production, culture synchronicity, and intracellular storage content. Reduction in NaNO3 and K2HPO4 concentrations from 17.6 and 0.23 mM to 4.41 and 0.06 mM, respectively, improved growth characteristics such as cell size and uniformity, and enhanced the rate of cell division. Cells grown in this low NP BG-11 were less complex, a parameter that related to the composition of the intracellular storage granules. Cells grown in low NP BG-11 had less polyphosphate, fewer polyhydroxybutyrate granules and many smaller granules became evident. Biochemical analysis and transmission electron microscopy using the histocytochemical PATO technique demonstrated that these small granules contained glycogen. The glycogen levels and the number of granules per cell correlated nicely with a 2.3 to 3.3-fold change from the minimum at L0 to the maximum at D0. The differences in granule morphology and enzymes between Cyanothece ATCC 51142 and Cyanothece PCC 7822 provide insights into the formation of large starch-like granules in some cyanobacteria.

  6. Identification of a transporter Slr0982 involved in ethanol tolerance in cyanobacterium Synechocystis sp. PCC 6803

    PubMed Central

    Zhang, Yanan; Niu, Xiangfeng; Shi, Mengliang; Pei, Guangsheng; Zhang, Xiaoqing; Chen, Lei; Zhang, Weiwen

    2015-01-01

    Cyanobacteria have been engineered to produce ethanol through recent synthetic biology efforts. However, one major challenge to the cyanobacterial systems for high-efficiency ethanol production is their low tolerance to the ethanol toxicity. With a major goal to identify novel transporters involved in ethanol tolerance, we constructed gene knockout mutants for 58 transporter-encoding genes of Synechocystis sp. PCC 6803 and screened their tolerance change under ethanol stress. The efforts allowed discovery of a mutant of slr0982 gene encoding an ATP-binding cassette transporter which grew poorly in BG11 medium supplemented with 1.5% (v/v) ethanol when compared with the wild type, and the growth loss could be recovered by complementing slr0982 in the Δslr0982 mutant, suggesting that slr0982 is involved in ethanol tolerance in Synechocystis. To decipher the tolerance mechanism involved, a comparative metabolomic and network-based analysis of the wild type and the ethanol-sensitive Δslr0982 mutant was performed. The analysis allowed the identification of four metabolic modules related to slr0982 deletion in the Δslr0982 mutant, among which metabolites like sucrose and L-pyroglutamic acid which might be involved in ethanol tolerance, were found important for slr0982 deletion in the Δslr0982 mutant. This study reports on the first transporter related to ethanol tolerance in Synechocystis, which could be a useful target for further tolerance engineering. In addition, metabolomic and network analysis provides important findings for better understanding of the tolerance mechanism to ethanol stress in Synechocystis. PMID:26052317

  7. Distinguishing the Roles of Thylakoid Respiratory Terminal Oxidases in the Cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Ermakova, Maria; Huokko, Tuomas; Richaud, Pierre; Bersanini, Luca; Howe, Christopher J; Lea-Smith, David J; Peltier, Gilles; Allahverdiyeva, Yagut

    2016-06-01

    Various oxygen-utilizing electron sinks, including the soluble flavodiiron proteins (Flv1/3), and the membrane-localized respiratory terminal oxidases (RTOs), cytochrome c oxidase (Cox) and cytochrome bd quinol oxidase (Cyd), are present in the photosynthetic electron transfer chain of Synechocystis sp. PCC 6803. However, the role of individual RTOs and their relative importance compared with other electron sinks are poorly understood, particularly under light. Via membrane inlet mass spectrometry gas exchange, chlorophyll a fluorescence, P700 analysis, and inhibitor treatment of the wild type and various mutants deficient in RTOs, Flv1/3, and photosystem I, we investigated the contribution of these complexes to the alleviation of excess electrons in the photosynthetic chain. To our knowledge, for the first time, we demonstrated the activity of Cyd in oxygen uptake under light, although it was detected only upon inhibition of electron transfer at the cytochrome b6f site and in ∆flv1/3 under fluctuating light conditions, where linear electron transfer was drastically inhibited due to impaired photosystem I activity. Cox is mostly responsible for dark respiration and competes with P700 for electrons under high light. Only the ∆cox/cyd double mutant, but not single mutants, demonstrated a highly reduced plastoquinone pool in darkness and impaired gross oxygen evolution under light, indicating that thylakoid-based RTOs are able to compensate partially for each other. Thus, both electron sinks contribute to the alleviation of excess electrons under illumination: RTOs continue to function under light, operating on slower time ranges and on a limited scale, whereas Flv1/3 responds rapidly as a light-induced component and has greater capacity. © 2016 American Society of Plant Biologists. All Rights Reserved.

  8. Distinguishing the Roles of Thylakoid Respiratory Terminal Oxidases in the Cyanobacterium Synechocystis sp. PCC 68031[OPEN

    PubMed Central

    Ermakova, Maria; Huokko, Tuomas; Richaud, Pierre; Bersanini, Luca; Howe, Christopher J.; Lea-Smith, David J.; Peltier, Gilles

    2016-01-01

    Various oxygen-utilizing electron sinks, including the soluble flavodiiron proteins (Flv1/3), and the membrane-localized respiratory terminal oxidases (RTOs), cytochrome c oxidase (Cox) and cytochrome bd quinol oxidase (Cyd), are present in the photosynthetic electron transfer chain of Synechocystis sp. PCC 6803. However, the role of individual RTOs and their relative importance compared with other electron sinks are poorly understood, particularly under light. Via membrane inlet mass spectrometry gas exchange, chlorophyll a fluorescence, P700 analysis, and inhibitor treatment of the wild type and various mutants deficient in RTOs, Flv1/3, and photosystem I, we investigated the contribution of these complexes to the alleviation of excess electrons in the photosynthetic chain. To our knowledge, for the first time, we demonstrated the activity of Cyd in oxygen uptake under light, although it was detected only upon inhibition of electron transfer at the cytochrome b6f site and in ∆flv1/3 under fluctuating light conditions, where linear electron transfer was drastically inhibited due to impaired photosystem I activity. Cox is mostly responsible for dark respiration and competes with P700 for electrons under high light. Only the ∆cox/cyd double mutant, but not single mutants, demonstrated a highly reduced plastoquinone pool in darkness and impaired gross oxygen evolution under light, indicating that thylakoid-based RTOs are able to compensate partially for each other. Thus, both electron sinks contribute to the alleviation of excess electrons under illumination: RTOs continue to function under light, operating on slower time ranges and on a limited scale, whereas Flv1/3 responds rapidly as a light-induced component and has greater capacity. PMID:27208274

  9. UV radiation-induced biosynthesis, stability and antioxidant activity of mycosporine-like amino acids (MAAs) in a unicellular cyanobacterium Gloeocapsa sp. CU2556.

    PubMed

    Rastogi, Rajesh P; Incharoensakdi, Aran

    2014-01-05

    The biosynthesis of natural sunscreening compounds as influenced by ultraviolet radiation, their stability and antioxidant activity were studied in the cyanobacterium Gloeocapsa sp. CU-2556. An analysis by high-performance liquid chromatography (HPLC) with photodiode-array (PDA) detection revealed the biosynthesis of two MAAs, shinorine (UVλmax 333nm) and an unknown MAA designated as M-307 (UVλmax 307nm) with retention times of 5.9 and 6.4min, respectively. Induction of the synthesis of MAAs was studied under 395 (PAR), 320 (PAR+UV-A) and 295 (PAR+UV-A+UV-B) nm cut-off filters. MAAs induction was significantly increased with an increase in exposure time up to 72h in the samples covered with 295nm cut-off filters. Contrary to shinorine, the biosynthesis of M-307 was more dominant in this unicellular cyanobacterium. Both MAAs were highly stable to some physico-chemical stressors such as UV radiation, heat and a strong oxidizing agent. The MAA M-307 was more stable under strong oxidative stress than shinorine. Moreover, UV-C radiation drastically decreased the stability of both MAAs. The MAAs (shinorine+M-307) also exhibited efficient antioxidant activity which was dose-dependent. The results indicate that MAAs may perform a vital role in survival and sustainability of Gloeocapsa sp. CU-2556 in harsh environmental conditions by its ability to absorb/screen short wavelength UV radiation and antioxidant function.

  10. 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

  11. Increased H2 production in the cyanobacterium Synechocystis sp. strain PCC 6803 by redirecting the electron supply via genetic engineering of the nitrate assimilation pathway.

    PubMed

    Baebprasert, Wipawee; Jantaro, Saowarath; Khetkorn, Wanthanee; Lindblad, Peter; Incharoensakdi, Aran

    2011-09-01

    The unicellular cyanobacterium Synechocystis sp. strain PCC 6803 contains a single bidirectional NiFe-Hox-hydrogenase, which evolves hydrogen under certain environmental conditions. The nitrate assimilation pathway is a potential competing pathway that may reduce the electron flow to the hydrogenase and thereby limit hydrogen production. To improve H(2) production, the nitrate assimilation pathway was disrupted by genetic engineering to redirect the electron flow towards the Hox-hydrogenase. Mutant strains disrupted in either nitrate reductase (ΔnarB) or nitrite reductase (ΔnirA) or both nitrate reductase and nitrite reductase (ΔnarB:ΔnirA) were constructed and tested for their ability to produce hydrogen. H(2) production and Hox-hydrogenase activities in all the mutant strains were higher than those in wild-type. Highest H(2) production was observed in the ΔnarB:ΔnirA strain. Small changes were observed for Hox-hydrogenase enzyme activities and only minor changes in transcript levels of hoxH and hoxY were not correlated with H(2) production. The results suggest that the high rate of H(2) production observed in the ΔnarB:ΔnirA strain of the cyanobacterium Synechocystis sp. strain PCC 6803 is the result of redirecting the electron supply from the nitrate assimilation pathway, through genetic engineering, towards the Hox-hydrogenase.

  12. Nitrogen control of the glnN gene that codes for GS type III, the only glutamine synthetase in the cyanobacterium Pseudanabaena sp. PCC 6903.

    PubMed

    Crespo, J L; García-Domínguez, M; Florencio, F J

    1998-12-01

    Pseudanabaena sp. strain PCC 6903 is the first cyanobacteria lacking the typical prokaryotic glutamine synthetase type I encoded by the glnA gene. The glnN gene product, glutamine synthetase type III, is the only glutamine synthetase activity present in this cyanobacterium. Analysis of glnN expression clearly indicated a nitrogen-dependent regulation. Pseudanabaena glnN gene expression and GSIII activity were upregulated under nitrogen starvation or using nitrate as a nitrogen source, while low levels of transcript and activity were found in ammonium-containing medium. Primer extension analysis showed that the glnN gene promoter structure resembled that of the NtcA-related promoters. Mobility shift assays demonstrated that Synechocystis sp. PCC 6803 NtcA protein, expressed and purified from Escherichia coli, bound to the promoter of the Pseudanabaena 6903 glnN gene. The NtcA control of the glnN gene in this cyanobacterium suggested that, in the absence of a glnA gene, NtcA took control of the only glutamine synthetase gene in a fashion similar to the way the glnA gene is governed in those cyanobacteria harbouring a glnA gene.

  13. Dimeric chlorite dismutase from the nitrogen‐fixing cyanobacterium C yanothece sp. PCC7425

    PubMed Central

    Schaffner, Irene; Hofbauer, Stefan; Krutzler, Michael; Pirker, Katharina F.; Bellei, Marzia; Stadlmayr, Gerhard; Mlynek, Georg; Djinovic‐Carugo, Kristina; Battistuzzi, Gianantonio; Furtmüller, Paul G.; Daims, Holger

    2015-01-01

    Summary It is demonstrated that cyanobacteria (both azotrophic and non‐azotrophic) contain heme b oxidoreductases that can convert chlorite to chloride and molecular oxygen (incorrectly denominated chlorite ‘dismutase’, Cld). Beside the water‐splitting manganese complex of photosystem II, this metalloenzyme is the second known enzyme that catalyses the formation of a covalent oxygen–oxygen bond. All cyanobacterial Clds have a truncated N‐terminus and are dimeric (i.e. clade 2) proteins. As model protein, Cld from C yanothece sp. PCC7425 (CCld) was recombinantly produced in E scherichia coli and shown to efficiently degrade chlorite with an activity optimum at pH 5.0 [k cat 1144 ± 23.8 s−1, KM 162 ± 10.0 μM, catalytic efficiency (7.1 ± 0.6) × 106 M−1 s−1]. The resting ferric high‐spin axially symmetric heme enzyme has a standard reduction potential of the Fe(III)/Fe(II) couple of −126 ± 1.9 mV at pH 7.0. Cyanide mediates the formation of a low‐spin complex with k on = (1.6 ± 0.1) × 105 M−1 s−1 and k off = 1.4 ± 2.9 s−1 (KD ∼ 8.6 μM). Both, thermal and chemical unfolding follows a non‐two‐state unfolding pathway with the first transition being related to the release of the prosthetic group. The obtained data are discussed with respect to known structure–function relationships of Clds. We ask for the physiological substrate and putative function of these O2‐producing proteins in (nitrogen‐fixing) cyanobacteria. PMID:25732258

  14. Glutaredoxins are essential for stress adaptation in the cyanobacterium Synechocystis sp. PCC 6803

    PubMed Central

    Sánchez-Riego, Ana M.; López-Maury, Luis; Florencio, Francisco J.

    2013-01-01

    Glutaredoxins are small redox proteins able to reduce disulfides and mixed disulfides between GSH and proteins. Synechocystis sp. PCC 6803 contains three genes coding for glutaredoxins: ssr2061 (grxA) and slr1562 (grxB) code for dithiolic glutaredoxins while slr1846 (grxC) codes for a monothiolic glutaredoxin. We have analyzed the expression of these glutaredoxins in response to different stresses, such as high light, H2O2 and heat shock. Analysis of the mRNA levels showed that grxA is only induced by heat while grxC is repressed by heat shock and is induced by high light and H2O2. In contrast, grxB expression was maintained almost constant under all conditions. Analysis of GrxA and GrxC protein levels by western blot showed that GrxA increases in response to high light, heat or H2O2 while GrxC is only induced by high light and H2O2, in accordance with its mRNA levels. In addition, we have also generated mutants that have interrupted one, two, or three glutaredoxin genes. These mutants were viable and did not show any different phenotype from the WT under standard growth conditions. Nevertheless, analysis of these mutants under several stress conditions revealed that single grxA mutants grow slower after H2O2, heat and high light treatments, while mutants in grxB are indistinguishable from WT. grxC mutants were hypersensitive to treatments with H2O2, heat, high light and metals. A double grxAgrxC mutant was found to be even more sensitive to H2O2 than each corresponding single mutants. Surprisingly a mutation in grxB suppressed totally or partially the phenotypes of grxA and grxC mutants except the H2O2 sensitivity of the grxC mutant. This suggests that grxA and grxC participate in independent pathways while grxA and grxB participate in a common pathway for H2O2 resistance. The data presented here show that glutaredoxins are essential for stress adaptation in cyanobacteria, although their targets and mechanism of action remain unidentified. PMID:24204369

  15. Characterization of a sodium-regulated glutaminase from cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Zhou, Jie; Zhou, JunXia; Yang, HaoMeng; Yan, ChengShi; Huang, Fang

    2008-12-01

    Glutaminase is widely distributed among microorganisms and mammals with important functions. Little is known regarding the biochemical properties and functions of the deamidating enzyme glutaminase in cyanobacteria. In this study a putative glutaminase encoded by gene slr2079 in Synechocystis sp. PCC 6803 was investigated. The slr2079 was expressed as histidine-tagged fusion protein in Escherichia coli. The purified protein possessed glutaminase activity, validating the functional assignment of the genomic annotation. The apparent K (m) value of the recombinant protein for glutamine was 26.6 +/- 0.9 mmol/L, which was comparable to that for some of other microbial glutaminases. Analysis of the purified protein revealed a two-fold increase in catalytic activity in the presence of 1 mol/L Na(+). Moreover, the K (m) value was decreased to 12.2 +/- 1.9 mmol/L in the presence of Na(+). These data demonstrate that the recombinant protein Slr2079 is a glutaminase which is regulated by Na(+) through increasing its affinity for substrate glutamine. The slr2079 gene was successfully disrupted in Synechocystis by targeted mutagenesis and the Deltaslr2079 mutant strain was analyzed. No differences in cell growth and oxygen evolution rate were observed between Deltaslr2079 and the wild type under standard growth conditions, demonstrating slr2079 is not essential in Synechocystis. Under high salt stress condition, however, Deltaslr2079 cells grew 1.25-fold faster than wild-type cells. Moreover, the photosynthetic oxygen evolution rate of Deltaslr2079 cells was higher than that of the wild-type. To further characterize this phenotype, a number of salt stress-related genes were analyzed by semi-quantitative RT-PCR. Expression of gdhB and prc was enhanced and expression of desD and guaA was repressed in Deltaslr2079 compared to the wild type. In addition, expression of two key enzymes of ammonium assimilation in cyanobacteria, glutamine synthetase (GS) and glutamate synthase (GOGAT

  16. Specific Glucoside Transporters Influence Septal Structure and Function in the Filamentous, Heterocyst-Forming Cyanobacterium Anabaena sp. Strain PCC 7120.

    PubMed

    Nieves-Morión, Mercedes; Lechno-Yossef, Sigal; López-Igual, Rocío; Frías, José E; Mariscal, Vicente; Nürnberg, Dennis J; Mullineaux, Conrad W; Wolk, C Peter; Flores, Enrique

    2017-04-01

    When deprived of combined nitrogen, some filamentous cyanobacteria contain two cell types: vegetative cells that fix CO2 through oxygenic photosynthesis and heterocysts that are specialized in N2 fixation. In the diazotrophic filament, the vegetative cells provide the heterocysts with reduced carbon (mainly in the form of sucrose) and heterocysts provide the vegetative cells with combined nitrogen. Septal junctions traverse peptidoglycan through structures known as nanopores and appear to mediate intercellular molecular transfer that can be traced with fluorescent markers, including the sucrose analog esculin (a coumarin glucoside) that is incorporated into the cells. Uptake of esculin by the model heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 was inhibited by the α-glucosides sucrose and maltose. Analysis of Anabaena mutants identified components of three glucoside transporters that move esculin into the cells: GlsC (Alr4781) and GlsP (All0261) are an ATP-binding subunit and a permease subunit of two different ABC transporters, respectively, and HepP (All1711) is a major facilitator superfamily (MFS) protein that was shown previously to be involved in formation of the heterocyst envelope. Transfer of fluorescent markers (especially calcein) between vegetative cells of Anabaena was impaired by mutation of glucoside transporter genes. GlsP and HepP interact in bacterial two-hybrid assays with the septal junction-related protein SepJ, and GlsC was found to be necessary for the formation of a normal number of septal peptidoglycan nanopores and for normal subcellular localization of SepJ. Therefore, beyond their possible role in nutrient uptake in Anabaena, glucoside transporters influence the structure and function of septal junctions.IMPORTANCE Heterocyst-forming cyanobacteria have the ability to perform oxygenic photosynthesis and to assimilate atmospheric CO2 and N2 These organisms grow as filaments that fix these gases specifically in vegetative

  17. Proteomic and metabolomic analyses reveal metabolic responses to 3-hydroxypropionic acid synthesized internally in cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Wang, Yunpeng; Chen, Lei; Zhang, Weiwen

    2016-01-01

    3-hydroxypropionic acid (3-HP) is an important platform chemical with a wide range of applications. In our previous study, the biosynthetic pathway of 3-HP was constructed and optimized in cyanobacterium Synechocystis sp. PCC 6803, which led to 3-HP production directly from CO2 at a level of 837.18 mg L(-1) (348.8 mg/g dry cell weight). As the production and accumulation of 3-HP in cells affect cellular metabolism, a better understanding of cellular responses to 3-HP synthesized internally in Synechocystis will be important for further increasing 3-HP productivity in cyanobacterial chassis. Using a engineered 3-HP-producing SM strain, in this study, the cellular responses to 3-HP internally produced were first determined using a quantitative iTRAQ-LC-MS/MS proteomics approach and a LC-MS-based targeted metabolomics. A total of 2264 unique proteins were identified, which represented about 63 % of all predicted protein in Synechocystis in the proteomic analysis; meanwhile intracellular abundance of 24 key metabolites was determined by a comparative metabolomic analysis of the 3-HP-producing strain SM and wild type. Among all identified proteins, 204 proteins were found up-regulated and 123 proteins were found down-regulated, respectively. The proteins related to oxidative phosphorylation, photosynthesis, ribosome, central carbon metabolism, two-component systems and ABC-type transporters were up-regulated, along with the abundance of 14 metabolites related to central metabolism. The results suggested that the supply of ATP and NADPH was increased significantly, and the precursor malonyl-CoA and acetyl-CoA may also be supplemented when 3-HP was produced at a high level in Synechocystis. Confirmation of proteomic and metabolomic results with RT-qPCR and gene-overexpression strains of selected genes was also conducted, and the overexpression of three transporter genes putatively involved in cobalt/nickel, manganese and phosphate transporting (i.e., sll0385, sll1598

  18. Roles of Group 2 Sigma Factors in Acclimation of the Cyanobacterium Synechocystis sp. PCC 6803 to Nitrogen Deficiency.

    PubMed

    Antal, Taras; Kurkela, Juha; Parikainen, Marjaana; Kårlund, Anna; Hakkila, Kaisa; Tyystjärvi, Esa; Tyystjärvi, Taina

    2016-06-01

    Acclimation of cyanobacteria to environmental conditions is mainly controlled at the transcriptional level, and σ factors of the RNA polymerase have a central role in this process. The model cyanobacterium Synechocystis sp. PCC 6803 has four non-essential group 2 σ factors (SigB, SigC, SigD and SigE) that regulate global metabolic responses to various adverse environmental conditions. Here we show that although none of the group 2 σ factors is essential for the major metabolic realignments induced by a short period of nitrogen starvation, the quadruple mutant without any group 2 σ factors and triple mutants missing both SigB and SigD grow slowly in BG-11 medium containing only 5% of the nitrate present in standard BG-11. These ΔsigBCDE, ΔsigBCD and ΔsigBDE strains lost PSII activity rapidly in low nitrogen and accumulated less glycogen than the control strain. An abnormally high glycogen content was detected in ΔsigBCE (SigD is active), while the carotenoid content became high in ΔsigCDE (SigB is active), indicating that SigB and SigD regulate the partitioning of carbon skeletons in low nitrogen. Long-term survival and recovery of the cells after nitrogen deficiency was strongly dependent on group 2 σ factors. The quadruple mutant and the ΔsigBDE strain (only SigC is active) recovered more slowly from nitrogen deficiency than the control strain, and ΔsigBCDE in particular lost viability during nitrogen starvation. Nitrogen deficiency-induced changes in the pigment content of the control strain recovered essentially in 1 d in nitrogen-replete medium, but little recovery occurred in ΔsigBCDE and ΔsigBDE. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  19. Specific Glucoside Transporters Influence Septal Structure and Function in the Filamentous, Heterocyst-Forming Cyanobacterium Anabaena sp. Strain PCC 7120

    PubMed Central

    Nieves-Morión, Mercedes; Lechno-Yossef, Sigal; López-Igual, Rocío; Frías, José E.; Mariscal, Vicente; Nürnberg, Dennis J.; Mullineaux, Conrad W.; Wolk, C. Peter

    2017-01-01

    ABSTRACT When deprived of combined nitrogen, some filamentous cyanobacteria contain two cell types: vegetative cells that fix CO2 through oxygenic photosynthesis and heterocysts that are specialized in N2 fixation. In the diazotrophic filament, the vegetative cells provide the heterocysts with reduced carbon (mainly in the form of sucrose) and heterocysts provide the vegetative cells with combined nitrogen. Septal junctions traverse peptidoglycan through structures known as nanopores and appear to mediate intercellular molecular transfer that can be traced with fluorescent markers, including the sucrose analog esculin (a coumarin glucoside) that is incorporated into the cells. Uptake of esculin by the model heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 was inhibited by the α-glucosides sucrose and maltose. Analysis of Anabaena mutants identified components of three glucoside transporters that move esculin into the cells: GlsC (Alr4781) and GlsP (All0261) are an ATP-binding subunit and a permease subunit of two different ABC transporters, respectively, and HepP (All1711) is a major facilitator superfamily (MFS) protein that was shown previously to be involved in formation of the heterocyst envelope. Transfer of fluorescent markers (especially calcein) between vegetative cells of Anabaena was impaired by mutation of glucoside transporter genes. GlsP and HepP interact in bacterial two-hybrid assays with the septal junction-related protein SepJ, and GlsC was found to be necessary for the formation of a normal number of septal peptidoglycan nanopores and for normal subcellular localization of SepJ. Therefore, beyond their possible role in nutrient uptake in Anabaena, glucoside transporters influence the structure and function of septal junctions. IMPORTANCE Heterocyst-forming cyanobacteria have the ability to perform oxygenic photosynthesis and to assimilate atmospheric CO2 and N2. These organisms grow as filaments that fix these gases specifically in

  20. Interrelation between cyanophycin synthesis, L-arginine catabolism and photosynthesis in the cyanobacterium Synechocystis sp. strain PCC 6803.

    PubMed

    Stephan, D P; Ruppel, H G; Pistorius, E K

    2000-01-01

    Ultrastructural and immunocytochemical investigations gave evidence that cyanophycin (multi-L-arginyl-poly-L-aspartate) granules accumulate in the cyanobacterium Synechocystis sp. strain PCC 6803 under nutrient deficient growth conditions, especially under phosphate limitation. Besides nutrient deficiency, growth of Synechocystis PCC 6803 on L-arginine or L-asparagine as sole N-source also led to high increase of cyanophycin synthesis, while growth on the combination of L-arginine or L-asparagine with nitrate only caused minor cyanophycin accumulation. Growth of Synechocystis PCC 6803 on L-arginine as sole N-source caused substantial morphological and physiological changes, such as severe thylakoid membrane degradation with partial loss of pigments and photosynthetic activity leading to a phenotype almost like that seen under nutrient deficiency. In contrast to the wild type, the PsbO-free Synechocystis PCC 6803 mutant could grow on L-arginine as sole N-source with only minor morphological and physiological changes. Due to its fairly balanced growth, the mutant accumulated only few cyanophycin granules. L-arginine degrading activity (measured as ornithine and ammonium formation) was high in the PsbO-free mutant but not in the wild type when cells were grown on L-arginine as sole N-source. In both cells types the L-arginine degrading activity was high (although in the PsbO-free mutant about twice as high as in wild type), when cells were grown on L-arginine in combination with nitrate, and as expected very low when cells were grown on nitrate as sole N-source. Thus, net cyanophycin accumulation in Synechocystis PCC 6803 is regulated by the relative concentration of L-arginine to the total nitrogen pool, and the intracellular L-arginine concentration is greatly influenced by the activity of the L-arginine degrading enzyme system which in part is regulated by the activity status of photosystem II. These results suggest a complex interrelation between cyanophycin

  1. 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

  2. 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.

  3. 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

    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.

  4. 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.

  5. In Vitro Structural and Functional Characterization of the Small Heat Shock Proteins (sHSP) of the Cyanophage S-ShM2 and Its Host, Synechococcus sp. WH7803

    PubMed Central

    Bourrelle-Langlois, Maxime; Morrow, Geneviève; Finet, Stéphanie; Tanguay, Robert M.

    2016-01-01

    We previously reported the in silico characterization of Synechococcus sp. phage 18 kDa small heat shock protein (HspSP-ShM2). This small heat shock protein (sHSP) contains a highly conserved core alpha crystalline domain of 92 amino acids and relatively short N- and C-terminal arms, the later containing the classical C-terminal anchoring module motif (L-X-I/L/V). Here we establish the oligomeric profile of HspSP-ShM2 and its structural dynamics under in vitro experimental conditions using size exclusion chromatography (SEC/FPLC), gradient native gels electrophoresis and dynamic light scattering (DLS). Under native conditions, HspSP-ShM2 displays the ability to form large oligomers and shows a polydisperse profile. At higher temperatures, it shows extensive structural dynamics and undergoes conformational changes through an increased of subunit rearrangement and formation of sub-oligomeric species. We also demonstrate its capacity to prevent the aggregation of citrate synthase, malate dehydrogenase and luciferase under heat shock conditions through the formation of stable and soluble hetero-oligomeric complexes (sHSP:substrate). In contrast, the host cyanobacteria Synechococcus sp. WH7803 15 kDa sHSP (HspS-WH7803) aggregates when in the same conditions as HspSP-ShM2. However, its solubility can be maintained in the presence of non-ionic detergent Triton™X-100 and forms an oligomeric structure estimated to be between dimer and tetramer but exhibits no apparent inducible structural dynamics neither chaperon-like activity in all the assays and molar ratios tested. SEC/FPLC and thermal aggregation prevention assays results indicate no formation of hetero-oligomeric complex or functional interactions between both sHSPs. Taken together these in vitro results portray the phage HspSP-ShM2 as a classical sHSP and suggest that it may be functional at the in vivo level while behaving differently than its host amphitropic sHSP. PMID:27643500

  6. In Vitro Structural and Functional Characterization of the Small Heat Shock Proteins (sHSP) of the Cyanophage S-ShM2 and Its Host, Synechococcus sp. WH7803.

    PubMed

    Bourrelle-Langlois, Maxime; Morrow, Geneviève; Finet, Stéphanie; Tanguay, Robert M

    2016-01-01

    We previously reported the in silico characterization of Synechococcus sp. phage 18 kDa small heat shock protein (HspSP-ShM2). This small heat shock protein (sHSP) contains a highly conserved core alpha crystalline domain of 92 amino acids and relatively short N- and C-terminal arms, the later containing the classical C-terminal anchoring module motif (L-X-I/L/V). Here we establish the oligomeric profile of HspSP-ShM2 and its structural dynamics under in vitro experimental conditions using size exclusion chromatography (SEC/FPLC), gradient native gels electrophoresis and dynamic light scattering (DLS). Under native conditions, HspSP-ShM2 displays the ability to form large oligomers and shows a polydisperse profile. At higher temperatures, it shows extensive structural dynamics and undergoes conformational changes through an increased of subunit rearrangement and formation of sub-oligomeric species. We also demonstrate its capacity to prevent the aggregation of citrate synthase, malate dehydrogenase and luciferase under heat shock conditions through the formation of stable and soluble hetero-oligomeric complexes (sHSP:substrate). In contrast, the host cyanobacteria Synechococcus sp. WH7803 15 kDa sHSP (HspS-WH7803) aggregates when in the same conditions as HspSP-ShM2. However, its solubility can be maintained in the presence of non-ionic detergent Triton™X-100 and forms an oligomeric structure estimated to be between dimer and tetramer but exhibits no apparent inducible structural dynamics neither chaperon-like activity in all the assays and molar ratios tested. SEC/FPLC and thermal aggregation prevention assays results indicate no formation of hetero-oligomeric complex or functional interactions between both sHSPs. Taken together these in vitro results portray the phage HspSP-ShM2 as a classical sHSP and suggest that it may be functional at the in vivo level while behaving differently than its host amphitropic sHSP.

  7. Biochemical analysis of three putative KaiC clock proteins from Synechocystis sp. PCC 6803 suggests their functional divergence.

    PubMed

    Wiegard, Anika; Dörrich, Anja K; Deinzer, Hans-Tobias; Beck, Christian; Wilde, Annegret; Holtzendorff, Julia; Axmann, Ilka M

    2013-05-01

    Cyanobacteria have been shown to have a circadian clock system that consists mainly of three protein components: KaiA, KaiB and KaiC. This system is well understood in the cyanobacterium Synechococcus elongatus PCC 7942, for which robust circadian oscillations have been shown. Like many other cyanobacteria, the chromosome of the model cyanobacterium Synechocystis sp. PCC 6803 contains additional kaiC and kaiB gene copies besides the standard kaiABC gene cluster. The respective gene products differ significantly in their amino acid sequences, especially in their C-terminal regions, suggesting different functional characteristics. Here, phosphorylation assays of the three Synechocystis sp. PCC 6803 KaiC proteins revealed that KaiC1 phosphorylation depends on KaiA, as is well documented for the Synechococcus elongatus PCC 7942 KaiC protein, whereas KaiC2 and KaiC3 autophosphorylate independently of KaiA. This was confirmed by in vivo protein-protein interaction studies, which demonstrate that only KaiC1 interacts with KaiA. Furthermore, we demonstrate that the three different Kai proteins form only homomeric complexes in vivo. As only KaiC1 phosphorylation depends on KaiA, a prerequisite for robust oscillations, we suggest that the kaiAB1C1 gene cluster in Synechocystis sp. PCC 6803 controls circadian timing in a manner similar to the clock described in Synechococcus elongatus PCC 7942.

  8. 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.

  9. Identification of Specific Variations in a Non-Motile Strain of Cyanobacterium Synechocystis sp. PCC 6803 Originated from ATCC 27184 by Whole Genome Resequencing.

    PubMed

    Ding, Qinglong; Chen, Gu; Wang, Yuling; Wei, Dong

    2015-10-12

    Cyanobacterium Synechocystis sp. PCC 6803 is a widely used model organism in basic research and biofuel biotechnology application. Here, we report the genomic sequence of chromosome and seven plasmids of a glucose-tolerant, non-motile strain originated from ATCC 27184, GT-G, in use at Guangzhou. Through high-throughput genome re-sequencing and verification by Sanger sequencing, eight novel variants were identified in its chromosome and plasmids. The eight novel variants, especially the five non-silent mutations might have interesting effects on the phenotype of GT-G strains, for example the truncated Sll1895 and Slr0322 protein. These resequencing data provide background information for further research and application based on the GT-G strain and also provide evidence to study the evolution and divergence of Synechocystis 6803 globally.

  10. A novel mechanism of glutamine synthetase inactivation by ammonium in the cyanobacterium Synechocystis sp. PCC 6803. Involvement of an inactivating protein.

    PubMed

    Reyes, J C; Florencio, F J

    1995-06-19

    The glutamine synthetase of the cyanobacterium Synechocystis sp. PCC 6803 can be inactivated in vivo by ammonium addition by a new mechanism that involves the binding to the enzyme of an inactivating factor. This binding provokes a different mobility of the inactive enzyme with respect to the active form in non-denaturing PAGE, but not in SDS-PAGE. This modification of glutamine synthetase is for the first time visualized by Western blot analysis of the active and inactive forms. Cross-linking experiments using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) demonstrate the existence of two main complexes of 56 kDa and 67 kDa between the inactivating factor and the glutamine synthetase subunit (53 kDa) in the inactive but not in the active form of glutamine synthetase.

  11. Identification of the light-independent phosphoserine pathway as an additional source of serine in the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Klemke, Friederike; Baier, Antje; Knoop, Henning; Kern, Ramona; Jablonsky, Jiri; Beyer, Gabriele; Volkmer, Thomas; Steuer, Ralf; Lockau, Wolfgang; Hagemann, Martin

    2015-05-01

    L-serine is one of the proteinogenic amino acids and participates in several essential processes in all organisms. In plants, the light-dependent photorespiratory and the light-independent phosphoserine pathways contribute to serine biosynthesis. In cyanobacteria, the light-dependent photorespiratory pathway for serine synthesis is well characterized, but the phosphoserine pathway has not been identified. Here, we investigated three candidate genes for enzymes of the phosphoserine pathway in Synechocystis sp. PCC 6803. Only the gene for the D-3-phosphoglycerate dehydrogenase is correctly annotated in the genome database, whereas the 3-phosphoserine transaminase and 3-phosphoserine phosphatase (PSP) proteins are incorrectly annotated and were identified here. All enzymes were obtained as recombinant proteins and showed the activities necessary to catalyse the three-step phosphoserine pathway. The genes coding for the phosphoserine pathway were found in most cyanobacterial genomes listed in CyanoBase. The pathway seems to be essential for cyanobacteria, because it was impossible to mutate the gene coding for PSP in Synechocystis sp. PCC 6803 or in Synechococcus elongatus PCC 7942. A model approach indicates a 30-60% contribution of the phosphoserine pathway to the overall serine pool. Hence, this study verified that cyanobacteria, similar to plants, use the phosphoserine pathway in addition to photorespiration for serine biosynthesis. © 2015 The Authors.

  12. Nitrogen availability and electron transport control the expression of glnB gene (encoding PII protein) in the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    García-Domínguez, M; Florencio, F J

    1997-12-01

    The glnB gene from Synechocystis sp. PCC 6803 that encodes the PII protein has been cloned by heterologous hybridization using the corresponding glnB gene from Synechococcus sp. PCC 7942. An ORF of 336 nucleotides appeared that potentially coded for a protein of 112 amino acid residues (M(r) 12,397). The deduced amino acid sequence revealed a high identity (higher than 80%) with its cyanobacterial counterparts and a basal level of identity (close to 60%) with other PII proteins. A single mRNA of about 680 nucleotides was found under all growth conditions studied. glnB gene expression was specifically activated under nitrogen deprivation (a 10-fold increase respect to nitrogen-replete conditions). No differences in glnB mRNA levels were observed when using nitrate or ammonium as nitrogen sources. Amount of glnB mRNA decreased to undetectable levels when transferring cells to the dark, but effect was avoided by adding glucose to the culture medium. Primer extension analysis and band-shift assays indicated that expression of the glnB gene, elevated under nitrogen deprivation, might lie under the control of the nitrogen transcriptional regulator NtcA, although constitutive levels of expression were also detected from a sigma 70-dependent Escherichia coli-like promoter.

  13. Adapting photosynthesis to the near-infrared: non-covalent binding of phycocyanobilin provides an extreme spectral red-shift to phycobilisome core-membrane linker from Synechococcus sp. PCC7335.

    PubMed

    Miao, Dan; Ding, Wen-Long; Zhao, Bao-Qing; Lu, Lu; Xu, Qian-Zhao; Scheer, Hugo; Zhao, Kai-Hong

    2016-06-01

    Phycobiliproteins that bind bilins are organized as light-harvesting complexes, phycobilisomes, in cyanobacteria and red algae. The harvested light energy is funneled to reaction centers via two energy traps, allophycocyanin B and the core-membrane linker, ApcE1 (conventional ApcE). The covalently bound phycocyanobilin (PCB) of ApcE1 absorbs near 660 nm and fluoresces near 675 nm. In cyanobacteria capable of near infrared photoacclimation, such as Synechococcus sp. PCC7335, there exist even further spectrally red shifted components absorbing >700 nm and fluorescing >710 nm. We expressed the chromophore domain of the extra core-membrane linker from Synechococcus sp. PCC7335, ApcE2, in E. coli together with enzymes generating the chromophore, PCB. The resulting chromoproteins, PCB-ApcE2(1-273) and the more truncated PCB-ApcE2(24-245), absorb at 700 nm and fluoresce at 714 nm. The red shift of ~40 nm compared with canonical ApcE1 results from non-covalent binding of the chromophore by which its full conjugation length including the Δ3,3(1) double bond is preserved. The extreme spectral red-shift could not be ascribed to exciton coupling: dimeric PCB-ApcE2(1-273) and monomeric-ApcE2(24-245) absorbed and fluoresced similarly. Chromophorylation of ApcE2 with phycoerythrobilin- or phytochromobilin resulted in similar red shifts (absorption at 615 and 711 nm, fluorescence at 628 or 726 nm, respectively), compared to the covalently bound chromophores. The self-assembled non-covalent chromophorylation demonstrates a novel access to red and near-infrared emitting fluorophores. Brightly fluorescent biomarking was exemplified in E. coli by single-plasmid transformation. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. 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.

  15. Preparation of RNA from bacteria infected with bacteriophages: a case study from the marine unicellular Synechococcus sp. WH7803 infected by phage S-PM2.

    PubMed

    Shan, Jinyu; Clokie, Martha

    2009-01-01

    Bacteriophages manipulate bacterial gene expression in order to express their own genes or influence bacterial metabolism. Gene expression can be studied using real-time PCR or microarrays. Either technique requires the prior isolation of high quality RNA uncontaminated by the presence of genomic DNA. We outline the considerations necessary when working with bacteriophage infected bacterial cells. We also give an example of a protocol for extraction and quantification of high quality RNA from infected bacterial cells, using the marine cyanobacterium WH7803 and the phage S-PM2 as a case study. This protocol can be modified to extract RNA from the host/bacteriophage of interest.

  16. 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

    2015-02-06

    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.

  17. Therapeutic properties in Tunisian hot springs: first evidence of phenolic compounds in the cyanobacterium Leptolyngbya sp. biomass, capsular polysaccharides and releasing polysaccharides.

    PubMed

    Trabelsi, Lamia; Mnari, Amira; Abdel-Daim, Mohamed M; Abid-Essafi, Salwa; Aleya, Lotfi

    2016-12-13

    In Tunisia, the use of hot spring waters for both health and recreation is a tradition dating back to Roman times. In fact, thermal baths, usually called "Hammam" are recommended as a therapeutic and prophylactic measure against many types of illness and toxicity. While the chemical concentration of thermal water is admittedly associated with its therapeutic effects, the inclusion in spa waters of efficient bioproduct additives produced by photosynthetic microorganisms and that act against oxidative stress may comprise a significant supplementary value for thermal centers. The aim of this study was to investigate the antioxidant potential of the Tunisian thermophilic cyanobacterium Leptolyngbya sp. and to determine its phytochemical constituents and phenolic profile. BME (Biomass Methanolic Extract), CME (Capsular polysaccharides Methanolic Extract) and RME (Releasing polysaccharides Methanolic Extract) of Leptolyngbya sp. were examined for their antioxidant activities by means of DPPH, hydroxyl radical scavenging and ferrous ion chelating assays. Their total phenols, flavonoids, carotenoids, Mycosporine-like amino acids (MAAs) and vitamin C contents, as well as their phenolic profiles were also determined. BME has the highest content of phenols (139 ± 1.2 mg/g), flavonoids (34.9 ± 0.32 mg CEQ/g), carotenoids (2.03 ± 0.56 mg/g) and vitamin C (15.7 ± 1.55 mg/g), while the highest MAAs content (0.42 ± 0.03 mg/g) was observed in CME. BME presented both the highest DPPH and hydroxyl radical scavenging ability with an IC50 of 0.07 and 0.38 mg/ml, respectively. The highest ferrous chelating capacity was detected in CME with an IC50 = 0.59 mg/ml. Phenolic profiles revealed the presence of 25 phenolic compounds with the existence of hydroxytyrosol, oleuropein, resveratrol and pinoresinol. The study demonstrated that the cyanobacterium Leptolyngbya sp. possesses abundant natural antioxidant products which may have prophylactic and

  18. A mutant lacking the glutamine synthetase gene (glnA) is impaired in the regulation of the nitrate assimilation system in the cyanobacterium Synechocystis sp. strain PCC 6803.

    PubMed Central

    Reyes, J C; Florencio, F J

    1994-01-01

    The existence in the unicellular cyanobacterium Synechocystis sp. strain PCC 6803 of two genes (glnA and glnN) coding for glutamine synthetase (GS) has been recently reported (J.C. Reyes and F.J. Florencio, J. Bacteriol. 176:1260-1267, 1994). In the current work, the regulation of the nitrate assimilation system was studied with a glnA-disrupted Synechocystis mutant (strain SJCR3) in which the only GS activity is that corresponding to the glnN product. This mutant was unable to grow in ammonium-containing medium because of its very low levels of GS activity. In the SJCR3 strain, nitrate and nitrite reductases were not repressed by ammonium, and short-term ammonium-promoted inhibition of nitrate uptake was impaired. In Synechocystis sp. strain PCC 6803, nitrate seems to act as a true inducer of its assimilation system, in a way similar to that proposed for the dinitrogen-fixing cyanobacteria. A spontaneous derivative strain from SJCR3 (SJCR3.1), was able to grow in ammonium-containing medium and exhibited a fourfold-higher level of GS activity than but the same amount of glnN transcript as its parental strain (SJCR3). Taken together, these finding suggest that SJCR3.1 is a mutant affected in the posttranscriptional regulation of the GS encoded by glnN. This strain recovered regulation by ammonium of nitrate assimilation. SJCR3 cells were completely depleted of intracellular glutamine shortly after addition of ammonium to cells growing with nitrate, while SJCR3.1 cells maintained glutamine levels similar to that reached in the wild-type Synechocystis sp. strain PCC 6803. Our results indicate that metabolic signals that control the nitrate assimilation system in Synechocystis sp. strain PCC 6803 require ammonium metabolism through GS. Images PMID:8002575

  19. A mutant lacking the glutamine synthetase gene (glnA) is impaired in the regulation of the nitrate assimilation system in the cyanobacterium Synechocystis sp. strain PCC 6803.

    PubMed

    Reyes, J C; Florencio, F J

    1994-12-01

    The existence in the unicellular cyanobacterium Synechocystis sp. strain PCC 6803 of two genes (glnA and glnN) coding for glutamine synthetase (GS) has been recently reported (J.C. Reyes and F.J. Florencio, J. Bacteriol. 176:1260-1267, 1994). In the current work, the regulation of the nitrate assimilation system was studied with a glnA-disrupted Synechocystis mutant (strain SJCR3) in which the only GS activity is that corresponding to the glnN product. This mutant was unable to grow in ammonium-containing medium because of its very low levels of GS activity. In the SJCR3 strain, nitrate and nitrite reductases were not repressed by ammonium, and short-term ammonium-promoted inhibition of nitrate uptake was impaired. In Synechocystis sp. strain PCC 6803, nitrate seems to act as a true inducer of its assimilation system, in a way similar to that proposed for the dinitrogen-fixing cyanobacteria. A spontaneous derivative strain from SJCR3 (SJCR3.1), was able to grow in ammonium-containing medium and exhibited a fourfold-higher level of GS activity than but the same amount of glnN transcript as its parental strain (SJCR3). Taken together, these finding suggest that SJCR3.1 is a mutant affected in the posttranscriptional regulation of the GS encoded by glnN. This strain recovered regulation by ammonium of nitrate assimilation. SJCR3 cells were completely depleted of intracellular glutamine shortly after addition of ammonium to cells growing with nitrate, while SJCR3.1 cells maintained glutamine levels similar to that reached in the wild-type Synechocystis sp. strain PCC 6803. Our results indicate that metabolic signals that control the nitrate assimilation system in Synechocystis sp. strain PCC 6803 require ammonium metabolism through GS.

  20. An alternative methionine aminopeptidase, MAP-A, is required for nitrogen starvation and high-light acclimation in the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Drath, Miriam; Baier, Kerstin; Forchhammer, Karl

    2009-05-01

    Methionine aminopeptidases (MetAPs or MAPs, encoded by map genes) are ubiquitous and pivotal enzymes for protein maturation in all living organisms. Whereas most bacteria harbour only one map gene, many cyanobacterial genomes contain two map paralogues, the genome of Synechocystis sp. PCC 6803 even three. The physiological function of multiple map paralogues remains elusive so far. This communication reports for the first time differential MetAP function in a cyanobacterium. In Synechocystis sp. PCC 6803, the universally conserved mapC gene (sll0555) is predominantly expressed in exponentially growing cells and appears to be a housekeeping gene. By contrast, expression of mapA (slr0918) and mapB (slr0786) genes increases during stress conditions. The mapB paralogue is only transiently expressed, whereas the widely distributed mapA gene appears to be the major MetAP during stress conditions. A mapA-deficient Synechocystis mutant shows a subtle impairment of photosystem II properties even under non-stressed conditions. In particular, the binding site for the quinone Q(B) is affected, indicating specific N-terminal methionine processing requirements of photosystem II components. MAP-A-specific processing becomes essential under certain stress conditions, since the mapA-deficient mutant is severely impaired in surviving conditions of prolonged nitrogen starvation and high light exposure.

  1. 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.

  2. Sll0939 is induced by Slr0967 in the cyanobacterium Synechocystis sp. PCC6803 and is essential for growth under various stress conditions.

    PubMed

    Uchiyama, Junji; Asakura, Ryosuke; Moriyama, Atsushi; Kubo, Yuko; Shibata, Yousuke; Yoshino, Yuka; Tahara, Hiroko; Matsuhashi, Ayumi; Sato, Shusei; Nakamura, Yasukazu; Tabata, Satoshi; Ohta, Hisataka

    2014-08-01

    In this study, the genes expressed in response to low pH stress were identified in the unicellular cyanobacterium Synechocystis sp. PCC 6803 using DNA microarrays. The expression of slr0967 and sll0939 constantly increased throughout 4-h acid stress conditions. Overexpression of these two genes under the control of the trc promoter induced the cells to become tolerant to acid stress. The Δslr0967 and Δsll0939 mutant cells exhibited sensitivity to osmotic and salt stress, whereas the trc mutants of these genes exhibited tolerance to these types of stress. Microarray analysis of the Δslr0967 mutant under acid stress conditions showed that expression of the high light-inducible protein ssr2595 (HliB) and the two-component response regulator slr1214 (rre15) were out of regulation due to gene inactivation, whereas they were upregulated by acid stress in the wild-type cells. Microarray analysis and real-time quantitative reverse transcription-polymerase chain reaction analysis showed that the expression of sll0939 was significantly repressed in the slr0967 deletion mutant. These results suggest that sll0939 is directly involved in the low pH tolerance of Synechocystis sp. PCC 6803 and that slr0967 may be essential for the induction of acid stress-responsive genes.

  3. Regulation of glutamine synthetase activity in the unicellular cyanobacterium Synechocystis sp. strain PCC 6803 by the nitrogen source: effect of ammonium.

    PubMed Central

    Mérida, A; Candau, P; Florencio, F J

    1991-01-01

    Glutamine synthetase activity from Synechocystis sp. strain PCC 6803 is regulated as a function of the nitrogen source available in the medium. Addition of 0.25 mM NH4Cl to nitrate-grown cells promotes a clear short-term inactivation of glutamine synthetase, whose enzyme activity decreases to 5 to 10% of the initial value in 25 min. The intracellular levels of glutamine, determined under various conditions, taken together with the results obtained with azaserine (an inhibitor of transamidases), rule out the possibility that glutamine per se is responsible for glutamine synthetase inactivation. Nitrogen starvation attenuates the ammonium-mediated glutamine synthetase inactivation, indicating that glutamine synthetase regulation is modulated through the internal balance between carbon-nitrogen compounds and carbon compounds. The parallelism observed between the glutamine synthetase activity and the internal concentration of alpha-ketoglutarate suggests that this metabolite could play a role as a positive effector of glutamine synthetase activity in Synechocystis sp. Despite the similarities of this physiological system to that described for enterobacteria, the lack of in vivo 32P labeling of glutamine synthetase during the inactivation process excludes the existence of an adenylylation-deadenylylation system in this cyanobacterium. Images PMID:1676397

  4. Genome-Scale Modeling of Light-Driven Reductant Partitioning and Carbon Fluxes in Diazotrophic Unicellular Cyanobacterium Cyanothece sp. ATCC 51142

    PubMed Central

    Pinchuk, Grigoriy E.; Hill, Eric A.; Kucek, Leo A.; Brown, Roslyn N.; Lipton, Mary S.; Osterman, Andrei; Fredrickson, Jim K.; Konopka, Allan E.; Beliaev, Alexander S.; Reed, Jennifer L.

    2012-01-01

    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 growth is limited by the flux through photosystem I, terminal respiratory oxidases are predicted to be an important mechanism for removing excess reductant. Similarly, under photosystem II flux limitation, excess electron carriers must be removed via cyclic electron transport. Furthermore, in silico calculations were in good quantitative agreement with the measured growth rates whereas predictions of reaction usage were qualitatively consistent with protein and mRNA expression data, which we used to further improve the resolution of intracellular flux values. PMID:22529767

  5. 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 ualitatively consistent with protein and mRNA expression data, when these latter datasets were used to constrain the model.

  6. The Presence of Glutamate Dehydrogenase Is a Selective Advantage for the Cyanobacterium Synechocystis sp. Strain PCC 6803 under Nonexponential Growth Conditions

    PubMed Central

    Chávez, S.; Lucena, J. M.; Reyes, J. C.; Florencio, F. J.; Candau, P.

    1999-01-01

    The unicellular cyanobacterium Synechocystis sp. strain PCC 6803 has two putative pathways for ammonium assimilation: the glutamine synthetase-glutamate synthase cycle, which is the main one and is finely regulated by the nitrogen source; and a high NADP-dependent glutamate dehydrogenase activity (NADP-GDH) whose contribution to glutamate synthesis is uncertain. To investigate the role of the latter, we used two engineered mutants, one lacking and another overproducing NADP-GDH. No major disturbances in the regulation of nitrogen-assimilating enzymes or in amino acids pools were detected in the null mutant, but phycobiline content, a sensitive indicator of the nutritional state of cyanobacterial cells, was significantly reduced, indicating that NADP-GDH plays an auxiliary role in ammonium assimilation. This effect was already prominent in the initial phase of growth, although differences in growth rate between the wild type and the mutants were observed at this stage only at low light intensities. However, the null mutant was unable to sustain growth at the late stage of the culture at the point when the wild type showed the maximum NADP-GDH activity, and died faster in ammonium-containing medium. Overexpression of NADP-GDH improved culture proliferation under moderate ammonium concentrations. Competition experiments between the wild type and the null mutant confirmed that the presence of NADP-GDH confers a selective advantage to Synechocystis sp. strain PCC 6803 in late stages of growth. PMID:9922243

  7. Regulation of glutamine synthetase activity in the unicellular cyanobacterium Synechocystis sp. strain PCC 6803 by the nitrogen source: effect of ammonium.

    PubMed

    Mérida, A; Candau, P; Florencio, F J

    1991-07-01

    Glutamine synthetase activity from Synechocystis sp. strain PCC 6803 is regulated as a function of the nitrogen source available in the medium. Addition of 0.25 mM NH4Cl to nitrate-grown cells promotes a clear short-term inactivation of glutamine synthetase, whose enzyme activity decreases to 5 to 10% of the initial value in 25 min. The intracellular levels of glutamine, determined under various conditions, taken together with the results obtained with azaserine (an inhibitor of transamidases), rule out the possibility that glutamine per se is responsible for glutamine synthetase inactivation. Nitrogen starvation attenuates the ammonium-mediated glutamine synthetase inactivation, indicating that glutamine synthetase regulation is modulated through the internal balance between carbon-nitrogen compounds and carbon compounds. The parallelism observed between the glutamine synthetase activity and the internal concentration of alpha-ketoglutarate suggests that this metabolite could play a role as a positive effector of glutamine synthetase activity in Synechocystis sp. Despite the similarities of this physiological system to that described for enterobacteria, the lack of in vivo 32P labeling of glutamine synthetase during the inactivation process excludes the existence of an adenylylation-deadenylylation system in this cyanobacterium.

  8. The presence of glutamate dehydrogenase is a selective advantage for the Cyanobacterium synechocystis sp. strain PCC 6803 under nonexponential growth conditions.

    PubMed

    Chávez, S; Lucena, J M; Reyes, J C; Florencio, F J; Candau, P

    1999-02-01

    The unicellular cyanobacterium Synechocystis sp. strain PCC 6803 has two putative pathways for ammonium assimilation: the glutamine synthetase-glutamate synthase cycle, which is the main one and is finely regulated by the nitrogen source; and a high NADP-dependent glutamate dehydrogenase activity (NADP-GDH) whose contribution to glutamate synthesis is uncertain. To investigate the role of the latter, we used two engineered mutants, one lacking and another overproducing NADP-GDH. No major disturbances in the regulation of nitrogen-assimilating enzymes or in amino acids pools were detected in the null mutant, but phycobiline content, a sensitive indicator of the nutritional state of cyanobacterial cells, was significantly reduced, indicating that NADP-GDH plays an auxiliary role in ammonium assimilation. This effect was already prominent in the initial phase of growth, although differences in growth rate between the wild type and the mutants were observed at this stage only at low light intensities. However, the null mutant was unable to sustain growth at the late stage of the culture at the point when the wild type showed the maximum NADP-GDH activity, and died faster in ammonium-containing medium. Overexpression of NADP-GDH improved culture proliferation under moderate ammonium concentrations. Competition experiments between the wild type and the null mutant confirmed that the presence of NADP-GDH confers a selective advantage to Synechocystis sp. strain PCC 6803 in late stages of growth.

  9. Effects of PII deficiency on expression of the genes involved in ammonium utilization in the cyanobacterium Synechocystis sp. Strain PCC 6803.

    PubMed

    Takatani, Nobuyuki; Omata, Tatsuo

    2006-06-01

    The Synechocystis sp. strain PCC 6803 mutant deficient in PII protein (the glnB gene product) was found to express glutamine synthetase activity at levels several times higher than the wild-type strain. There was no significant difference in nitrate reductase activity levels between the two strains, and the nitrite reductase levels were somewhat lower in the mutant than in the wild-type strain. The higher glutamine synthetase activity in the mutant was ascribed to higher expression levels of the glutamine synthetase genes (glnA and glnN), which belong to the regulon controlled by NtcA, a Crp-family transcription regulator. Examination of the effects of PII deficiency on other NtcA-regulated genes revealed that the transcript levels of amt1 (encoding an ammonium permease) and gifB (encoding an inhibitor of glutamine synthetase) were increased, whereas that of gifA (a homolog of gifB, encoding another glutamine synthetase inhibitor) was decreased, with those of nirA, nrtC, icd, sigE (rpoD2-V), nblA and ntcA being unaffected. Unlike the Synechococcus elongatus strain PCC 7942, induction or repression of the NtcA-regulated genes proceeded normally in the PII-deficient mutant upon nitrogen depletion. The altered steady-state expression levels of glnA, glnN, amt1, gifA and gifB in the PII-deficient mutant suggested that Synechocystis sp. strain PCC 6803 has a mechanism for regulation of the subset of the NtcA-regulated genes related directly to ammonium assimilation.

  10. Effects of heavy metals (Pb2+ and Cd2+) on the ultrastructure, growth and pigment contents of the unicellular cyanobacterium Synechocystis sp. PCC 6803

    NASA Astrophysics Data System (ADS)

    Arunakumara, K. K. I. U.; Zhang, Xuecheng

    2009-05-01

    The unicellular cyanobacterium Synechocystis sp. PCC 6803, a model organism known for its unique combination of highly desirable molecular genetic, physiological and morphological characteristics, was employed in the present study. The species was cultured in BG11 liquid medium contained various initial concentrations of Pb2+ and Cd2+ (0, 0.5, 1, 2, 4, 6 and 8 mg/L). The experiment was conducted for six days and the metal induced alterations in the ultrastructure, growth and pigment contents were assessed. Alterations in the ultrastructure of the Synechocystis sp. PCC 6803 cells became evident with the increased (>4 mg/L Pb2+) metal concentration. The photosynthetic apparatus (thylakoid membranes) were found to be the worst affected. Deteriorated or completely destroyed thylakoid membranes have made large empty spaces in the cell interior. In addition, at the highest concentration (8 mg/L Pb2+), the polyphosphate granules became more prominent both in size and number. Despite the initial slight stimulations (0.2, 3.8 and 6.5% respectively at 0.5, 1 and 2 mg/L Pb2+), both metals inhibited the growth in a dose-dependent manner as incubation progressed. Pigment contents (chlorophyll α, β carotene and phycocyanin) were also decreased with increasing metal concentration. Cells exposed to 6 mg/L Pb2+, resulted in 36.56, 37.39 and 29.34% reductions of chlorophyll α, β carotene and phycocyanin respectively over the control. Corresponding reductions for the same Cd2+concentrations were 57.83, 48.94 and 56.90%. Lethal concentration (96 h LC50) values (3.47 mg/L Cd2+ and 12.11 mg/L Pb2+) indicated that Synechocystis sp. PCC 6803 is more vulnerable to Cd2+ than Pb2+.

  11. Dynamics and Cell-Type Specificity of the DNA Double-Strand Break Repair Protein RecN in the Developmental Cyanobacterium Anabaena sp. Strain PCC 7120.

    PubMed

    Hu, Sheng; Wang, Jinglan; Wang, Li; Zhang, Cheng-Cai; Chen, Wen-Li

    2015-01-01

    DNA replication and repair are two fundamental processes required in life proliferation and cellular defense and some common proteins are involved in both processes. The filamentous cyanobacterium Anabaena sp. strain PCC 7120 is capable of forming heterocysts for N2 fixation in the absence of a combined-nitrogen source. This developmental process is intimately linked to cell cycle control. In this study, we investigated the localization of the DNA double-strand break repair protein RecN during key cellular events, such as chromosome damaging, cell division, and heterocyst differentiation. Treatment by a drug causing DNA double-strand breaks (DSBs) induced reorganization of the RecN focus preferentially towards the mid-cell position. RecN-GFP was absent in most mature heterocysts. Furthermore, our results showed that HetR, a central player in heterocyst development, was involved in the proper positioning and distribution of RecN-GFP. These results showed the dynamics of RecN in DSB repair and suggested a differential regulation of DNA DSB repair in vegetative cell and heterocysts. The absence of RecN in mature heterocysts is compatible with the terminal nature of these cells.

  12. 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

  13. Enhancing photo-catalytic production of organic acids in the cyanobacterium S ynechocystis sp. PCC 6803 Δ glg C , a strain incapable of glycogen storage

    DOE PAGES

    Carrieri, Damian; Broadbent, Charlie; Carruth, David; ...

    2015-01-23

    We describe how a key objective in microbial biofuels strain development is to maximize carbon flux to target products while minimizing cell biomass accumulation, such that ideally the algae and bacteria would operate in a photo-catalytic state. A brief period of such a physiological state has recently been demonstrated in the cyanobacterium Synechocystis sp. PCC 6803 ΔglgC strain incapable of glycogen storage. When deprived of nitrogen, the ΔglgC excretes the organic acids alpha-ketoglutarate and pyruvate for a number of days without increasing cell biomass. This study examines the relationship between the growth state and the photo-catalytic state, and characterizes themore » metabolic adaptability of the photo-catalytic state to increasing light intensity. It is found that the culture can transition naturally from the growth state into the photo-catalytic state when provided with limited nitrogen supply during the growth phase. Photosynthetic capacity and pigments are lost over time in the photo-catalytic state. Reversal to growth state is observed with re-addition of nitrogen nutrient, accompanied by restoration of photosynthetic capacity and pigment levels in the cells. While the overall productivity increased under high light conditions, the ratio of alpha-ketoglutarate/pyruvate is altered, suggesting that carbon partition between the two products is adaptable to environmental conditions.« less

  14. Mutation of a Gene Encoding a Putative Glycoprotease Leads to Reduced Salt Tolerance, Altered Pigmentation, and Cyanophycin Accumulation in the Cyanobacterium Synechocystis sp. Strain PCC 6803

    PubMed Central

    Zuther, Ellen; Schubert, Hendrik; Hagemann, Martin

    1998-01-01

    The salt-sensitive mutant 549 of the cyanobacterium Synechocystis sp. strain PCC 6803 was genetically and physiologically characterized. The mutated site and corresponding wild-type site were cloned and partially sequenced. The genetic analysis revealed that during the mutation about 1.8 kb was deleted from the chromosome of mutant 549. This deletion affected four open reading frames: a gcp gene homolog, the psaFJ genes, and an unknown gene. After construction of mutants with single mutations, only the gcp mutant showed a reduction in salt tolerance comparable to that of the initial mutant, indicating that the deletion of this gene was responsible for the salt sensitivity and that the other genes were of minor importance. Besides the reduced salt tolerance, a remarkable change in pigmentation was observed that became more pronounced in salt-stressed cells. The phycobilipigment content decreased, and that of carotenoids increased. Investigations of changes in the ultrastructure revealed an increase in the amount of characteristic inclusion bodies containing the high-molecular-weight nitrogen storage polymer cyanophycin (polyaspartate and arginine). The salt-induced accumulation of cyanophycin was confirmed by chemical estimations. The putative glycoprotease encoded by the gcp gene might be responsible for the degradation of cyanophycin in Synechocystis. Mutation of this gene leads to nitrogen starvation of the cells, accompanied by characteristic changes in pigmentation, ultrastructure, and salt tolerance level. PMID:9537367

  15. Physiological and gene expression responses to nitrogen regimes and temperatures in Mastigocladus sp. strain CHP1, a predominant thermotolerant cyanobacterium of hot springs.

    PubMed

    Alcamán, M Estrella; Alcorta, Jaime; Bergman, Birgitta; Vásquez, Mónica; Polz, Martin; Díez, Beatriz

    2017-03-01

    Cyanobacteria are widely distributed primary producers with significant implications for the global biogeochemical cycles of carbon and nitrogen. Diazotrophic cyanobacteria of subsection V (Order Stigonematales) are particularly ubiquitous in photoautotrophic microbial mats of hot springs. The Stigonematal cyanobacterium strain CHP1 isolated from the Porcelana hot spring (Chile) was one of the major contributors of the new nitrogen through nitrogen fixation. Further morphological and genetic characterization verified that the strain CHP1 belongs to Stigonematales, and it formed a separate clade together with other thermophiles of the genera Fischerella and Mastigocladus. Strain CHP1 fixed maximum N2 in the light, independent of the temperature range. At 50°C nifH gene transcripts showed high expression during the light period, whereas the nifH gene expression at 45°C was arrhythmic. The strain displayed a high affinity for nitrate and a low tolerance for high ammonium concentrations, whereas the narB and glnA genes showed higher expression in light and at the beginning of the dark phase. It is proposed that Mastigocladus sp. strain CHP1 would represent a good model for the study of subsection V thermophilic cyanobacteria, and for understanding the adaptations of these photoautotrophic organisms inhabiting microbial mats in hot springs globally.

  16. Enhancing photo-catalytic production of organic acids in the cyanobacterium S ynechocystis sp. PCC 6803 Δ glg C , a strain incapable of glycogen storage

    DOE PAGES

    Carrieri, Damian; Broadbent, Charlie; Carruth, David; ...

    2015-01-23

    We describe how a key objective in microbial biofuels strain development is to maximize carbon flux to target products while minimizing cell biomass accumulation, such that ideally the algae and bacteria would operate in a photo-catalytic state. A brief period of such a physiological state has recently been demonstrated in the cyanobacterium Synechocystis sp. PCC 6803 ΔglgC strain incapable of glycogen storage. When deprived of nitrogen, the ΔglgC excretes the organic acids alpha-ketoglutarate and pyruvate for a number of days without increasing cell biomass. This study examines the relationship between the growth state and the photo-catalytic state, and characterizes themore » metabolic adaptability of the photo-catalytic state to increasing light intensity. It is found that the culture can transition naturally from the growth state into the photo-catalytic state when provided with limited nitrogen supply during the growth phase. Photosynthetic capacity and pigments are lost over time in the photo-catalytic state. Reversal to growth state is observed with re-addition of nitrogen nutrient, accompanied by restoration of photosynthetic capacity and pigment levels in the cells. While the overall productivity increased under high light conditions, the ratio of alpha-ketoglutarate/pyruvate is altered, suggesting that carbon partition between the two products is adaptable to environmental conditions.« less

  17. Functional and Structural Characterization of a Cation-dependent O-Methyltransferase from the Cyanobacterium Synechocystis sp. Strain PCC 6803*S⃞

    PubMed Central

    Kopycki, Jakub Grzegorz; Stubbs, Milton T.; Brandt, Wolfgang; Hagemann, Martin; Porzel, Andrea; Schmidt, Jürgen; Schliemann, Willibald; Zenk, Meinhart H.; Vogt, Thomas

    2008-01-01

    The coding sequence of the cyanobacterium Synechocystis sp. strain PCC 6803 slr0095 gene was cloned and functionally expressed in Escherichia coli. The corresponding enzyme was classified as a cation- and S-adenosyl-l-methionine-dependent O-methyltransferase (SynOMT), consistent with considerable amino acid sequence identities to eukaryotic O-methyltransferases (OMTs). The substrate specificity of SynOMT was similar with those of plant and mammalian CCoAOMT-like proteins accepting a variety of hydroxycinnamic acids and flavonoids as substrates. In contrast to the known mammalian and plant enzymes, which exclusively methylate the meta-hydroxyl position of aromatic di- and trihydroxy systems, Syn-OMT also methylates the para-position of hydroxycinnamic acids like 5-hydroxyferulic and 3,4,5-trihydroxycinnamic acid, resulting in the formation of novel compounds. The x-ray structure of SynOMT indicates that the active site allows for two alternative orientations of the hydroxylated substrates in comparison to the active sites of animal and plant enzymes, consistent with the observed preferred para-methylation and position promiscuity. Lys3 close to the N terminus of the recombinant protein appears to play a key role in the activity of the enzyme. The possible implications of these results with respect to modifications of precursors of polymers like lignin are discussed. PMID:18502765

  18. Localization and Quantitative Determination of Ferredoxin-NADP+ Oxidoreductase, a Thylakoid-Bound Enzyme in the Cyanobacterium Anabaena sp. Strain 7119 12

    PubMed Central

    Serrano, Aurelio; Soncini, Fernando C.; Vallejos, Rubén H.

    1986-01-01

    Thylakoid membrane preparations obtained from mechanically disrupted (sonicated) cells of the cyanobacterium Anabaena sp. strain 7119 show a membrane-bound ferredoxin-NADP+ oxidoreductase (EC 1.18.1.2) as determined either by specific antibodies or by using the ferredoxin-dependent NADPH-cytochrome c reductase activity, which is a specific test for this enzyme. However, in contrast with higher plant thylakoids, a low yield of the cyanobacterial reductase—only about 20% of the total amount of this protein estimated in whole cell homogenates—was obtained as a membrane-bound form when Mg2+ was present during the disruption treatment. It is noteworthy that the addition of water-soluble nonionic polymers, namely polyethylene glycol and polyyinylpyrrolidone, dramatically increased the yield of the thylakoid-bound reductase, reaching values up to 80 to 85% of the total enzyme. Using these thylakoid membrane preparations, a quantitative determination of the reductase has been performed for the first time for cyanobacterial thylakoids. The value determined by immunoelectrophoresis—from 8 to 10 nanomoles per micromole of chlorophyll—is clearly higher than those reported for chloroplast thylakoids. PMID:16665058

  19. Role of Light Intensity and Temperature in the Regulation of Hydrogen Photoproduction by the Marine Cyanobacterium Oscillatoria sp. Strain Miami BG7.

    PubMed

    Phlips, E J; Mitsui, A

    1983-04-01

    The effects of several key environmental factors on the development and control of hydrogen production in the marine blue-green alga (cyanobacterium) Oscillatoria sp. strain Miami BG7 were studied in relation to the potential application of this strain to a bio-solar energy technology. The production of cellular biomass capable of evolving hydrogen gas was strongly affected by light intensity, temperature, and the input of ammonia as a nutrient. Depletion of combined nitrogen from the growth media was a prerequisite for the initiation of hydrogen production. Maximum hydrogen-producing capability coincided with the end of the linear phase of growth. Hydrogen production exhibited considerable flexibility to environmental extremes. The rate of production saturated at low light intensities (i.e., 15 to 30 muEinsteins/m per s), and no photoinhibition was observed at high light intensity (i.e., 1,000 muEinsteins/m per s). The upper temperature limit for production was 46 degrees C. Above the light compensation point for O(2) evolution H(2) production was inhibited. However, this problem was alleviated by two related phenomena. (i) The capacity of cells to evolve oxygen deteriorated with increasing culture age and nitrogen depletion, and (ii) the ability of these cells to produce oxygen in closed anaerobic hydrogen production systems was temporally limited.

  20. 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-type cyanobacteriochrome GAF domain of PixA was expressed in Synechocystis and phycocyanobilin-producing Escherichia coli. The holoprotein covalently bound a chromophore phycoviolobilin and showed reversible photoconversion between the violet- (Pv, λ(peak) = 396 nm) and green-absorbing (Pg, λ(peak) = 533 nm) forms, although the protein from E. coli partially bound a precursor phycocyanobilin. These results were discussed with regard to an idea that PixA serves as a violet light receptor for switching of positive and negative phototaxis by transcriptional and functional regulation.

  1. [The sll0886 gene, controlling light-activated heterotrophic growth, is involved in regulating phototaxis in cyanobacterium Synechocystis sp. PCC 6893].

    PubMed

    Kirik, I A; Babykin, M M

    2008-05-01

    The sll0886 gene, controlling light-activated heterotrophic growth (LAHG), was tested for the role in regulating phototaxis in cyanobacterium Synechocystis sp. PCC 6803. Insertional inactivation of the gene in the genome of a wildtype strain did not affect positive (toward light) or negative (away from high light) phototaxis. However, cells lost motility when sll0886 inactivation was combined with the prqRL17Q mutation, which determined negative phototaxis at low light. Immotile cells with the prqRL17Q mutation and the inactivated sll0886 gene did not display any defect in the formation of type IV pili, essential for phototaxis. Hence, the function, rather than biogenesis, of pili was affected. It was concluded that the sll0886 gene, coding for a TPR family protein, is involved in controlling negative phototaxis of cyanobacteria at the level of photoreception and signal transduction and that its role is mediated by the unidentified redundant gene whose function is suppressed by the prqRL17Q mutation.

  2. Role of Light Intensity and Temperature in the Regulation of Hydrogen Photoproduction by the Marine Cyanobacterium Oscillatoria sp. Strain Miami BG7

    PubMed Central

    Phlips, E. J.; Mitsui, A.

    1983-01-01

    The effects of several key environmental factors on the development and control of hydrogen production in the marine blue-green alga (cyanobacterium) Oscillatoria sp. strain Miami BG7 were studied in relation to the potential application of this strain to a bio-solar energy technology. The production of cellular biomass capable of evolving hydrogen gas was strongly affected by light intensity, temperature, and the input of ammonia as a nutrient. Depletion of combined nitrogen from the growth media was a prerequisite for the initiation of hydrogen production. Maximum hydrogen-producing capability coincided with the end of the linear phase of growth. Hydrogen production exhibited considerable flexibility to environmental extremes. The rate of production saturated at low light intensities (i.e., 15 to 30 μEinsteins/m2 per s), and no photoinhibition was observed at high light intensity (i.e., 1,000 μEinsteins/m2 per s). The upper temperature limit for production was 46°C. Above the light compensation point for O2 evolution H2 production was inhibited. However, this problem was alleviated by two related phenomena. (i) The capacity of cells to evolve oxygen deteriorated with increasing culture age and nitrogen depletion, and (ii) the ability of these cells to produce oxygen in closed anaerobic hydrogen production systems was temporally limited. PMID:16346266

  3. Polar-biased localization of the cold stress-induced RNA helicase, CrhC, in the Cyanobacterium Anabaena sp. strain PCC 7120.

    PubMed

    El-Fahmawi, Bassam; Owttrim, George W

    2003-11-01

    Shift of the filamentous cyanobacterium, Anabaena sp. strain PCC 7120, from 30 degrees C to 20 degrees C induces expression of a cold shock response gene encoding the RNA helicase CrhC. Subcellular localization using cellular fractionation and membrane purification indicated that CrhC is localized to the plasma membrane with no evidence of a soluble-cytoplasmic form. Treatment of spheroplasts with trypsin and membrane fractions with various denaturing agents identified CrhC as an integral membrane protein associated with the cytoplasmic face of the plasma membrane. Immunoelectron microscopy confirmed the plasma membrane association of CrhC. Interestingly, a higher specific labelling was observed at the cell poles on the septa between adjacent cells within cell filaments. On a per cell area basis, CrhC localization to the cell pole was 3.5- and >1000-fold higher than to the lateral portion of the plasma membrane or cytoplasm respectively. In addition, CrhC also localizes to new cell poles forming within a dividing cell. Polar-biased localization of the CrhC RNA helicase implies a role in RNA metabolism that is plasma membrane associated and preferentially occurs at the cell poles during cyanobacterial response to cold stress.

  4. Histidine kinases play important roles in the perception and signal transduction of hydrogen peroxide in the cyanobacterium, Synechocystis sp. PCC 6803.

    PubMed

    Kanesaki, Yu; Yamamoto, Hiroshi; Paithoonrangsarid, Kalyanee; Shoumskaya, Maria; Suzuki, Iwane; Hayashi, Hidenori; Murata, Norio

    2007-01-01

    Oxidative stress caused by reactive oxygen species and, in particular, to hydrogen peroxide (H(2)O(2)) has a major impact on all biological systems, including plants and microorganisms. We investigated the H(2)O(2)-inducible expression of genes in the cyanobacterium Synechocystis sp. PCC 6803 using genome-wide DNA microarrays. Our systematic screening of a library of mutant lines with defects in histidine kinases (Hiks) by RNA slot-blot hybridization and DNA-microarray analysis suggested that four Hiks, namely, Hik33, Hik34, Hik16 and Hik41, are involved in the perception and transduction of H(2)O(2) signals that regulate the gene expression of 26 of the 77 H(2)O(2)-inducible genes with induction factors higher than 4.0. Among the four Hiks, Hik33 was the main contributor and was responsible for 22 of the 26 H(2)O(2)-inducible genes under the control of the Hiks. By contrast to Hik33, PerR encoding putative peroxide-sensing protein is involved in the regulation of only nine H(2)O(2)-inducible genes.

  5. Enhancing photo-catalytic production of organic acids in the cyanobacterium Synechocystis sp. PCC 6803 ΔglgC, a strain incapable of glycogen storage

    PubMed Central

    Carrieri, Damian; Broadbent, Charlie; Carruth, David; Paddock, Troy; Ungerer, Justin; Maness, Pin-Ching; Ghirardi, Maria; Yu, Jianping

    2015-01-01

    A key objective in microbial biofuels strain development is to maximize carbon flux to target products while minimizing cell biomass accumulation, such that ideally the algae and bacteria would operate in a photo-catalytic state. A brief period of such a physiological state has recently been demonstrated in the cyanobacterium Synechocystis sp. PCC 6803 ΔglgC strain incapable of glycogen storage. When deprived of nitrogen, the ΔglgC excretes the organic acids alpha-ketoglutarate and pyruvate for a number of days without increasing cell biomass. This study examines the relationship between the growth state and the photo-catalytic state, and characterizes the metabolic adaptability of the photo-catalytic state to increasing light intensity. It is found that the culture can transition naturally from the growth state into the photo-catalytic state when provided with limited nitrogen supply during the growth phase. Photosynthetic capacity and pigments are lost over time in the photo-catalytic state. Reversal to growth state is observed with re-addition of nitrogen nutrient, accompanied by restoration of photosynthetic capacity and pigment levels in the cells. While the overall productivity increased under high light conditions, the ratio of alpha-ketoglutarate/pyruvate is altered, suggesting that carbon partition between the two products is adaptable to environmental conditions. PMID:25616027

  6. Construction of a stepwise gene integration system by transient expression of actinophage R4 integrase in cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Miura, Takamasa; Nishizawa, Akito; Nishizawa, Tomoyasu; Asayama, Munehiko; Takahashi, Hideo; Shirai, Makoto

    2014-08-01

    The integrase of actinophage R4, which belongs to the large serine-recombinase family, catalyzes site-specific recombination between two distinct attachment site sequences of the phage (attP) and actinomycete Streptomyces parvulus 2297 chromosome (attB). We previously reported that R4 integrase (Sre) catalyzed site-specific recombination both in vivo and in vitro. In the present study, a Sre-based system was developed for the stepwise site-specific integration of multiple genes into the chromosome of cyanobacterium Synechocystis sp. PCC 6803 (hereafter PCC 6803). A transgene-integrated plasmid with two attP sites and a non-replicative sre-containing plasmid were co-introduced into attB-inserted PCC 6803 cells. The transiently expressed Sre catalyzed highly efficient site-specific integration between one of the two attP sites on the integration plasmid and the attB site on the chromosome of PCC 6803. A second transgene-integrated plasmid with an attB site was integrated into the residual attP site on the chromosome by repeating site-specific recombination. The transformation frequencies (%) of the first and second integrations were approximately 5.1 × 10(-5) and 8.2 × 10(-5), respectively. Furthermore, the expression of two transgenes was detected. This study is the first to apply the multiple gene site-specific integration system based on R4 integrase to cyanobacteria.

  7. Fine-Tuning of Photoautotrophic Protein Production by Combining Promoters and Neutral Sites in the Cyanobacterium Synechocystis sp. Strain PCC 6803

    PubMed Central

    Berla, Bertram M.

    2015-01-01

    Cyanobacteria are photosynthetic cell factories that use solar energy to convert CO2 into useful products. Despite this attractive feature, the development of tools for engineering cyanobacterial chassis has lagged behind that for heterotrophs such as Escherichia coli or Saccharomyces cerevisiae. Heterologous genes in cyanobacteria are often integrated at presumptively “neutral” chromosomal sites, with unknown effects. We used transcriptome sequencing (RNA-seq) data for the model cyanobacterium Synechocystis sp. strain PCC 6803 to identify neutral sites from which no transcripts are expressed. We characterized the two largest such sites on the chromosome, a site on an endogenous plasmid, and a shuttle vector by integrating an enhanced yellow fluorescent protein (EYFP) expression cassette expressed from either the Pcpc560 or the Ptrc1O promoter into each locus. Expression from the endogenous plasmid was as much as 14-fold higher than that from the chromosome, with intermediate expression from the shuttle vector. The expression characteristics of each locus correlated predictably with the promoters used. These findings provide novel, characterized tools for synthetic biology and metabolic engineering in cyanobacteria. PMID:26209663

  8. Ammonium/methylammonium permeases of a Cyanobacterium. Identification and analysis of three nitrogen-regulated amt genes in synechocystis sp. PCC 6803.

    PubMed

    Montesinos, M L; Muro-Pastor, A M; Herrero, A; Flores, E

    1998-11-20

    Ammonium is an important nitrogen source for many microorganisms and plants. Ammonium transporters whose activity can be probed with [14C]methylammonium have been described in several organisms including some cyanobacteria, and amt genes encoding ammonium/methylammonium permeases have been recently identified in yeast, Arabidopsis thaliana, and some bacteria. The unicellular cyanobacterium Synechocystis sp. PCC 6803 exhibited a [14C]methylammonium uptake activity that was inhibited by externally added ammonium. Three putative amt genes that are found in the recently published complete sequence of the chromosome of strain PCC 6803 were inactivated by insertion of antibiotic resistance-encoding gene-cassettes. The corresponding mutant strains were impaired in uptake of [14C]methylammonium. Open reading frame sll0108 (amt1) was responsible for a high affinity uptake activity (Ks for methylammonium, 2.7 microM), whereas open reading frames sll1017 (amt2) and sll0537 (amt3) made minor contributions to uptake at low substrate concentrations. Expression of the three amt genes was higher in nitrogen-starved cells than in cells incubated in the presence of a source of nitrogen (either ammonium or nitrate), but amt1 was expressed at higher levels than the other two amt genes. Transcription of amt1 was found to take place from a promoter bearing the structure of the cyanobacterial promoters activated by the nitrogen control transcription factor, NtcA.

  9. Impact of Different Group 2 Sigma Factors on Light Use Efficiency and High Salt Stress in the Cyanobacterium Synechocystis sp. PCC 6803

    PubMed Central

    Tyystjärvi, Taina; Huokko, Tuomas; Rantamäki, Susanne; Tyystjärvi, Esa

    2013-01-01

    Sigma factors of RNA polymerase recognize promoters and have a central role in controlling transcription initiation and acclimation to changing environmental conditions. The cyanobacterium Synechocystis sp. PCC 6803 encodes four non-essential group 2 sigma factors, SigB, SigC, SigD and SigE that closely resemble the essential SigA factor. Three out of four group 2 sigma factors were simultaneously inactivated and acclimation responses of the triple inactivation strains were studied. All triple inactivation strains grew slowly in low light, and our analysis suggests that the reason is a reduced capacity to adjust the perception of light. Simultaneous inactivation of SigB and SigD hampered growth also in high light. SigB is the most important group 2 sigma factor for salt acclimation, and elimination of all the other group 2 sigma factors slightly improved the salt tolerance of Synechocystis. Presence of only SigE allowed full salt acclimation including up-regulation of hspA and ggpS genes, but more slowly than SigB. Cells with only SigD acclimated to high salt but the acclimation processes differed from those of the control strain. Presence of only SigC prevented salt acclimation. PMID:23638176

  10. Reduction-Induced Suppression of Electron Flow (RISE) in the Photosynthetic Electron Transport System of Synechococcus elongatus PCC 7942.

    PubMed

    Shaku, Keiichiro; Shimakawa, Ginga; Hashiguchi, Masaki; Miyake, Chikahiro

    2016-07-01

    Accumulation of electrons under conditions of environmental stress produces a reduced state in the photosynthetic electron transport (PET) system and causes the reduction of O2 by PSI in the thylakoid membranes to produce the reactive oxygen species superoxide radical, which irreversibly inactivates PSI. This study aims to elucidate the molecular mechanism for the oxidation of reaction center Chl of PSI, P700, after saturated pulse (SP) light illumination of the cyanobacterium Synechococcus elongatus PCC 7942 under steady-state photosynthetic conditions. Both P700 and NADPH were transiently oxidized after SP light illumination under CO2-depleted photosynthesis conditions. In contrast, the Chl fluorescence intensity transiently increased. Compared with the wild type, the increase in Chl fluorescence and the oxidations of P700 and NADPH were greatly enhanced in a mutant (Δflv1/3) deficient in the genes encoding FLAVODIIRON 1 (FLV1) and FLV3 proteins even under high photosynthetic conditions. Furthermore, oxidation of Cyt f was also observed in the mutant. After SP light illumination, a transient suppression of O2 evolution was also observed in Δflv1/3. From these observations, we propose that the reduction in the plastquinone (PQ) pool suppresses linear electron flow at the Cyt b6/f complex, which we call the reduction-induced suppression of electron flow (RISE) in the PET system. The accumulation of the reduced form of PQ probably suppresses turnover of the Q cycle in the Cyt b6/f complex.

  11. Transcriptional and translational regulation of nitrogenase in light-dark- and continuous-light-grown cultures of the unicellular cyanobacterium Cyanothece sp. strain ATCC 51142.

    PubMed Central

    Colón-López, M S; Sherman, D M; Sherman, L A

    1997-01-01

    Cyanothece sp. strain ATCC 51142 is a unicellular, diazotrophic cyanobacterium which demonstrated extensive metabolic periodicities of photosynthesis, respiration, and nitrogen fixation when grown under N2-fixing conditions. N2 fixation and respiration peaked at 24-h intervals early in the dark or subjective-dark period, whereas photosynthesis was approximately 12 h out of phase and peaked toward the end of the light or subjective-light phase. Gene regulation studies demonstrated that nitrogenase is carefully controlled at the transcriptional and posttranslational levels. Indeed, Cyanothece sp. strain ATCC 51142 has developed an expensive mode of regulation, such that nitrogenase was synthesized and degraded each day. These patterns were seen when cells were grown under either light-dark or continuous-light conditions. Nitrogenase mRNA was synthesized from the nifHDK operon during the first 4 h of the dark period under light-dark conditions or during the first 6 h of the subjective-dark period when grown in continuous light. The nitrogenase NifH and NifDK subunits reached a maximum level at 4 to 10 h in the dark or subjective-dark periods and were shown by Western blotting and electron microscopy immunocytochemistry to be thoroughly degraded toward the end of the dark periods. An exception is the NifDK protein (MoFe-protein), which appeared not to be completely degraded under continuous-light conditions. We hypothesize that cellular O2 levels were kept low by decreasing photosynthesis and by increasing respiration in the early dark or subjective-dark periods to permit nitrogenase activity. The subsequent increase in O2 levels resulted in nitrogenase damage and eventual degradation. PMID:9209050

  12. Unraveling the Physiological Roles of the Cyanobacterium Geitlerinema sp. BBD and Other Black Band Disease Community Members through Genomic Analysis of a Mixed Culture

    PubMed Central

    Den Uyl, Paul A.; Richardson, Laurie L.; Jain, Sunit

    2016-01-01

    Black band disease (BBD) is a cyanobacterial-dominated polymicrobial mat that propagates on and migrates across coral surfaces, necrotizing coral tissue. Culture-based laboratory studies have investigated cyanobacteria and heterotrophic bacteria isolated from BBD, but the metabolic potential of various BBD microbial community members and interactions between them remain poorly understood. Here we report genomic insights into the physiological and metabolic potential of the BBD-associated cyanobacterium Geitlerinema sp. BBD 1991 and six associated bacteria that were also present in the non-axenic culture. The essentially complete genome of Geitlerinema sp. BBD 1991 contains a sulfide quinone oxidoreductase gene for oxidation of sulfide, suggesting a mechanism for tolerating the sulfidic conditions of BBD mats. Although the operon for biosynthesis of the cyanotoxin microcystin was surprisingly absent, potential relics were identified. Genomic evidence for mixed-acid fermentation indicates a strategy for energy metabolism under the anaerobic conditions present in BBD during darkness. Fermentation products may supply carbon to BBD heterotrophic bacteria. Among the six associated bacteria in the culture, two are closely related to organisms found in culture-independent studies of diseased corals. Their metabolic pathways for carbon and sulfur cycling, energy metabolism, and mechanisms for resisting coral defenses suggest adaptations to the coral surface environment and biogeochemical roles within the BBD mat. Polysulfide reductases were identified in a Flammeovirgaceae genome (Bacteroidetes) and the sox pathway for sulfur oxidation was found in the genome of a Rhodospirillales bacterium (Alphaproteobacteria), revealing mechanisms for sulfur cycling, which influences virulence of BBD. Each genomic bin possessed a pathway for conserving energy from glycerol degradation, reflecting adaptations to the glycerol-rich coral environment. The presence of genes for detoxification

  13. Mutagenesis of hetR reveals amino acids necessary for HetR function in the heterocystous cyanobacterium Anabaena sp. strain PCC 7120.

    PubMed

    Risser, Douglas D; Callahan, Sean M

    2007-03-01

    HetR is the master regulator of heterocyst differentiation in the filamentous cyanobacterium Anabaena sp. strain PCC 7120. Genetic selection was used to identify 33 amino acid substitutions in HetR that reduced the proportion of cells undergoing heterocyst differentiation to less than 2%. Conservative substitutions in the wild-type HetR protein revealed three mutations that dramatically reduced the amount of heterocyst differentiation when the mutant allele was present in place of the wild-type allele on a replicating plasmid in a mutant lacking hetR on the chromosome. An H69Y substitution resulted in heterocyst formation among less than 0.1% of cells, and D17E and G36A substitutions resulted in a Het- phenotype, compared to heterocyst formation among approximately 25% of cells with the wild-type hetR under the same conditions. The D17E substitution prevented DNA binding activity exhibited by wild-type HetR in mobility shift assays, whereas G36A and H69Y substitutions had no affect on DNA binding. D17E, G36A, and H69Y substitutions also resulted in higher levels of the corresponding HetR protein than of the wild-type protein when each was expressed from an inducible promoter in a hetR deletion strain, suggesting an effect on HetR protein turnover. Surprisingly, C48A and S152A substitutions, which were previously reported to result in a Het- phenotype, were found to have no effect on heterocyst differentiation or patterning when the corresponding mutations were introduced into an otherwise wild-type genetic background in Anabaena sp. strain PCC 7120. The clustering of mutations that satisfied the positive selection near the amino terminus suggests an important role for this part of the protein in HetR function.

  14. Dark-to-light transition in Synechococcus sp. PCC 7942 cells studied by fluorescence kinetics assesses plastoquinone redox poise in the dark and photosystem II fluorescence component and dynamics during state 2 to state 1 transition.

    PubMed

    Tsimilli-Michael, Merope; Stamatakis, Kostas; Papageorgiou, George C

    2009-03-01

    We investigated the dark-to-light transition in Synechococcus sp. PCC 7942 cells by a detailed analysis of fluorescence transients induced by strong red light. The transients, recorded with high data-acquisition, revealed all the steps of the fast (OJIP; 10(-5)-1 s) and slow phase (PSM(T); 1-10(3) s), kinetically distinguished with precision. Focusing on the OJIP-rise, we show, for the first time, how the variable to initial fluorescence ratio and the relative height of J-level can serve as indexes of the plastoquinone redox poise and the established state in the dark; hence, differences among cyanobacteria can be recognised in a simple way. Applying intermittent illumination (20-s light pulses separated by 10-s dark intervals) to induce dark-to-light transition and analysing the individual transients, we establish a method by which we determine the fluorescence component not originating from photosystem (PS) II and we assess PSII dynamics during state 2 to state 1 transition. The development of photochemical and non-photochemical quenching is also discussed, as well as evidences favouring the mobile antenna model.

  15. Draft Genome Sequence of Alkalinema sp. Strain CACIAM 70d, a Cyanobacterium Isolated from an Amazonian Freshwater Environment

    PubMed Central

    Lima, Alex Ranieri Jerônimo; Castro, Wendel de Oliveira; Moraes, Pablo Henrique Gonçalves; Siqueira, Andrei Santos; Aguiar, Délia Cristina Figueira; de Lima, Clayton Pereira Silva; Vianez-Júnior, João Lídio Silva Gonçalves; Nunes, Márcio Roberto Teixeira; Dall’Agnol, Leonardo Teixeira

    2017-01-01

    ABSTRACT In order to increase the genomic data of cyanobacterial strains isolated in Brazil, we hereby present the draft genome sequence of the Alkalinema sp. strain CACIAM 70d, isolated from an Amazonian freshwater environment. This report describes the first genome available for this genus. PMID:28705982

  16. Viruses Infecting a Freshwater Filamentous Cyanobacterium (Nostoc sp.) Encode a Functional CRISPR Array and a Proteobacterial DNA Polymerase B

    PubMed Central

    Chénard, Caroline; Wirth, Jennifer F.

    2016-01-01

    ABSTRACT   Here we present the first genomic characterization of viruses infecting Nostoc, a genus of ecologically important cyanobacteria that are widespread in freshwater. Cyanophages A-1 and N-1 were isolated in the 1970s and infect Nostoc sp. strain PCC 7210 but remained genomically uncharacterized. Their 68,304- and 64,960-bp genomes are strikingly different from those of other sequenced cyanophages. Many putative genes that code for proteins with known functions are similar to those found in filamentous cyanobacteria, showing a long evolutionary history in their host. Cyanophage N-1 encodes a CRISPR array that is transcribed during infection and is similar to the DR5 family of CRISPRs commonly found in cyanobacteria. The presence of a host-related CRISPR array in a cyanophage suggests that the phage can transfer the CRISPR among related cyanobacteria and thereby provide resistance to infection with competing phages. Both viruses also encode a distinct DNA polymerase B that is closely related to those found in plasmids of Cyanothece sp. strain PCC 7424, Nostoc sp. strain PCC 7120, and Anabaena variabilis ATCC 29413. These polymerases form a distinct evolutionary group that is more closely related to DNA polymerases of proteobacteria than to those of other viruses. This suggests that the polymerase was acquired from a proteobacterium by an ancestral virus and transferred to the cyanobacterial plasmid. Many other open reading frames are similar to a prophage-like element in the genome of Nostoc sp. strain PCC 7524. The Nostoc cyanophages reveal a history of gene transfers between filamentous cyanobacteria and their viruses that have helped to forge the evolutionary trajectory of this previously unrecognized group of phages. PMID:27302758

  17. An Integrative Approach to Energy, Carbon, and Redox Metabolism in the Cyanobacterium Synechocystis sp. PCC 6803. Special Report

    SciTech Connect

    Overbeek, R.

    2003-06-30

    The main objectives for the first year were to produce a detailed metabolic reconstruction of synechocystis sp. PCC 6803 especially in interrelated areas of photosynthesis, respiration, and central carbon metabolism to support a more complete understanding and modeling of this organism. Additionally, Integrated Genomics, Inc., provided detailed bioinformatic analysis of selected functional systems related to carbon and energy generation and utilization, and of the corresponding pathways, functional roles and individual genes to support wet lab experiments by collaborators.

  18. Complete genome sequence of cyanobacterium Nostoc sp. NIES-3756, a potentially useful strain for phytochrome-based bioengineering.

    PubMed

    Hirose, Yuu; Fujisawa, Takatomo; Ohtsubo, Yoshiyuki; Katayama, Mitsunori; Misawa, Naomi; Wakazuki, Sachiko; Shimura, Yohei; Nakamura, Yasukazu; Kawachi, Masanobu; Yoshikawa, Hirofumi; Eki, Toshihiko; Kanesaki, Yu

    2016-01-20

    To explore the diverse photoreceptors of cyanobacteria, we isolated Nostoc sp. strain NIES-3756 from soil at Mimomi-Park, Chiba, Japan, and determined its complete genome sequence. The Genome consists of one chromosome and two plasmids (total 6,987,571 bp containing no gaps). The NIES-3756 strain carries 7 phytochrome and 12 cyanobacteriochrome genes, which will facilitate the studies of phytochrome-based bioengineering. Copyright © 2015. Published by Elsevier B.V.

  19. CO2 capture using limestone for cultivation of the freshwater microalga Chlorella sorokiniana PAZ and the cyanobacterium Arthrospira sp. VSJ.

    PubMed

    Zawar, Prachi; Javalkote, Vivek; Burnap, Robert; Mahulikar, Pramod; Puranik, Pravin

    2016-12-01

    The present study reports a process wherein CO2 is captured in the form of bicarbonates using calcium oxide and photosynthetically fixed into biomass. Microalgal cultures viz. Chlorella sorokiniana PAZ and Arthrospira sp. VSJ were grown in the medium containing bicarbonates. The rate of bicarbonate utilization by C. sorokiniana PAZ was higher when CO2 trapped in the presence of 2.67mM calcium oxide than in the presence of 10mM sodium hydroxide and with direct addition of 10mM sodium bicarbonate. For Arthrospira sp. VSJ the bicarbonate utilization was 92.37%, 88.34% and 59.23% for the medium containing CaO, NaOH and NaHCO3, respectively. Illumination of photosynthetically active radiation (PAR)+ultraviolet A radiation (UVA) enhanced the yield of C. sorokiniana PAZ and Arthrospira sp. VSJ by 1.3 and 1.8 folds, respectively. FTIR analysis revealed elevation in the biosynthesis of specific metabolites in response to the UVA exposure.

  20. Overexpression of flv3 improves photosynthesis in the cyanobacterium Synechocystis sp. PCC6803 by enhancement of alternative electron flow.

    PubMed

    Hasunuma, Tomohisa; Matsuda, Mami; Senga, Youhei; Aikawa, Shimpei; Toyoshima, Masakazu; Shimakawa, Ginga; Miyake, Chikahiro; Kondo, Akihiko

    2014-01-01

    To ensure reliable sources of energy and raw materials, the utilization of sustainable biomass has considerable advantages over petroleum-based energy sources. Photosynthetic algae have attracted attention as a third-generation feedstock for biofuel production, because algae cultivation does not directly compete with agricultural resources, including the requirement for productive land and fresh water. In particular, cyanobacteria are a promising biomass feedstock because of their high photosynthetic capability. In the present study, the expression of the flv3 gene, which encodes a flavodiiron protein involved in alternative electron flow (AEF) associated with NADPH-coupled O2 photoreduction in photosystem I, was enhanced in Synechocystis sp. PCC6803. Overexpression of flv3 improved cell growth with corresponding increases in O2 evolution, intracellular ATP level, and turnover of the Calvin cycle. The combination of in vivo (13)C-labeling of metabolites and metabolomic analysis confirmed that the photosynthetic carbon flow was enhanced in the flv3-overexpressing strain. Overexpression of flv3 improved cell growth and glycogen production in the recombinant Synechocystis sp. PCC6803. Direct measurement of metabolic turnover provided conclusive evidence that CO2 incorporation is enhanced by the flv3 overexpression. Increase in O2 evolution and ATP accumulation indicates enhancement of the AEF. Overexpression of flv3 improves photosynthesis in the Synechocystis sp. PCC6803 by enhancement of the AEF.

  1. Regulation of the carbon-concentrating mechanism in the cyanobacterium Synechocystis sp. PCC6803 in response to changing light intensity and inorganic carbon availability.

    PubMed

    Burnap, Robert L; Nambudiri, Rehka; Holland, Steven

    2013-11-01

    Photosynthetic organisms possess regulatory mechanisms to balance the various inputs of photosynthesis in a manner that minimizes over-excitation of the light-driven electron transfer apparatus, while maximizing the reductive assimilation of inorganic nutrients, most importantly inorganic carbon (Ci). Accordingly, the regulatory interactions coordinating responses to fluctuating light and responses to Ci availability are of fundamental significance. The inducible high affinity carbon-concentrating mechanism (CCM) in the cyanobacterium Synechocystis sp. PCC6803 has been studied in order to understand how it is integrated with the light and dark reactions of photosynthesis. To probe genetic regulatory mechanisms, genomic DNA microarrays were used to survey for differences in the expression of genes in response to a shift to high light conditions under conditions of either high or low Ci availability. Discrepancies in published experiments exist regarding the extent to which genes for the CCM are upregulated in response to high light treatment. These discrepancies may be due to critical differences in Ci availability existing during the different high light experiments. The present microarray experiments reexamine this by comparing high light treatment under two different Ci regimes: bubbling with air and bubbling with air enriched with CO2. While some transcriptional responses such as the downregulation of antenna proteins are quite similar, pronounced differences exist with respect to the differential expression of CCM and affiliated genes. The results are discussed in the context of a recent analysis revealing that small molecules that are intermediates of the light and dark reaction photosynthetic metabolism act as allosteric effectors of the DNA-binding proteins which modulate the expression of the CCM genes.

  2. Independent regulation of nifHDK operon transcription and DNA rearrangement during heterocyst differentiation in the cyanobacterium Anabaena sp. strain PCC 7120.

    PubMed Central

    Golden, J W; Whorff, L L; Wiest, D R

    1991-01-01

    The filamentous cyanobacterium Anabaena sp. strain PCC 7120 expresses the genes required for nitrogen fixation in terminally differentiated cells called heterocysts. The nifHDK operon encodes the nitrogenase polypeptides and is expressed at high levels in heterocysts. During heterocyst differentiation, an 11-kb DNA element is excised from the nifD gene by site-specific recombination. The xisA gene, located on the 11-kb element, is required for the excision of the element. Transcription and DNA rearrangement of the nifHDK operon both occur late during heterocyst differentiation, about 18 to 24 h after induction, suggesting that the regulation of these events might be coupled. We show that heterocyst-specific transcription and DNA rearrangement of the nifHDK operon are independent of one another. Northern (RNA) analysis of the xisA mutant strain DW12-2.2, which cannot excise the nifD 11-kb element or fix nitrogen, showed that the nifH and nifD genes are transcribed on unrearranged chromosomes. The nifK gene was not transcribed in DW12-2.2, indicating that its expression is dependent on the nifH promoter and excision of the 11-kb element from the operon. A 1.68-kb DNA fragment containing the nifH promoter was deleted from the chromosome to produce the mutant strain LW1. LW1 formed heterocysts but did not grow on nitrogen-free medium and showed no transcription through nifD. Southern analysis of LW1 showed normal excision of the 11-kb element from the nifHDK operon, indicating that transcription from the nifH promoter is not required for the developmentally regulated DNA rearrangement. Images FIG. 2 FIG. 3 FIG. 5 FIG. 6 FIG. 7 PMID:1938911

  3. Spectral inhomogeneity of photosystem I and its influence on excitation equilibration and trapping in the cyanobacterium Synechocystis sp. PCC6803 at 77 K.

    PubMed

    Melkozernov, A N; Lin, S; Blankenship, R E; Valkunas, L

    2001-08-01

    Ultrafast transient absorption spectroscopy was used to probe excitation energy transfer and trapping at 77 K in the photosystem I (PSI) core antenna from the cyanobacterium Synechocystis sp. PCC 6803. Excitation of the bulk antenna at 670 and 680 nm induces a subpicosecond energy transfer process that populates the Chl a spectral form at 685--687 nm within few transfer steps (300--400 fs). On a picosecond time scale equilibration with the longest-wavelength absorbing pigments occurs within 4-6 ps, slightly slower than at room temperature. At low temperatures in the absence of uphill energy transfer the energy equilibration processes involve low-energy shifted chlorophyll spectral forms of the bulk antenna participating in a 30--50-ps process of photochemical trapping of the excitation by P(700). These spectral forms might originate from clustered pigments in the core antenna and coupled chlorophylls of the reaction center. Part of the excitation is trapped on a pool of the longest-wavelength absorbing pigments serving as deep traps at 77 K. Transient hole burning of the ground-state absorption of the PSI with excitation at 710 and 720 nm indicates heterogeneity of the red pigment absorption band with two broad homogeneous transitions at 708 nm and 714 nm (full-width at half-maximum (fwhm) approximately 200--300 cm(-1)). The origin of these two bands is attributed to the presence of two chlorophyll dimers, while the appearance of the early time bleaching bands at 683 nm and 678 nm under excitation into the red side of the absorption spectrum (>690 nm) can be explained by borrowing of the dipole strength by the ground-state absorption of the chlorophyll a monomers from the excited-state absorption of the dimeric red pigments.

  4. Two essential FtsH proteases control the level of the Fur repressor during iron deficiency in the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Krynická, Vendula; Tichý, Martin; Krafl, Jaroslav; Yu, Jianfeng; Kaňa, Radek; Boehm, Marko; Nixon, Peter J; Komenda, Josef

    2014-11-01

    The cyanobacterium Synechocystis sp. PCC 6803 expresses four different FtsH protease subunits (FtsH1-4) that assemble into specific homo- and heterocomplexes. The FtsH2/FtsH3 complex is involved in photoprotection but the physiological roles of the other complexes, notably the essential FtsH1/FtsH3 complex, remain unclear. Here we show that the FtsH1 and FtsH3 proteases are involved in the acclimation of cells to iron deficiency. A mutant conditionally depleted in FtsH3 was unable to induce normal expression of the IsiA chlorophyll-protein and FutA1 iron transporter upon iron deficiency due to a block in transcription, which is regulated by the Fur transcriptional repressor. Levels of Fur declined in the WT and the FtsH2 null mutant upon iron depletion but not in the FtsH3 downregulated strain. A similar stabilizing effect on Fur was also observed in a mutant conditionally depleted in the FtsH1 subunit. Moreover, a mutant overexpressing FtsH1 showed reduced levels of Fur and enhanced accumulation of both IsiA and FutA1 even under iron sufficiency. Analysis of GFP-tagged derivatives and biochemical fractionation supported a common location for FtsH1 and FtsH3 in the cytoplasmic membrane. Overall we propose that degradation of the Fur repressor mediated by the FtsH1/FtsH3 heterocomplex is critical for acclimation to iron depletion.

  5. Oxidation of a Cysteine Residue in Elongation Factor EF-Tu Reversibly Inhibits Translation in the Cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Yutthanasirikul, Rayakorn; Nagano, Takanori; Jimbo, Haruhiko; Hihara, Yukako; Kanamori, Takashi; Ueda, Takuya; Haruyama, Takamitsu; Konno, Hiroki; Yoshida, Keisuke; Hisabori, Toru; Nishiyama, Yoshitaka

    2016-03-11

    Translational elongation is susceptible to inactivation by reactive oxygen species (ROS) in the cyanobacterium Synechocystis sp. PCC 6803, and elongation factor G has been identified as a target of oxidation by ROS. In the present study we examined the sensitivity to oxidation by ROS of another elongation factor, EF-Tu. The structure of EF-Tu changes dramatically depending on the bound nucleotide. Therefore, we investigated the sensitivity to oxidation in vitro of GTP- and GDP-bound EF-Tu as well as that of nucleotide-free EF-Tu. Assays of translational activity with a reconstituted translation system from Escherichia coli revealed that GTP-bound and nucleotide-free EF-Tu were sensitive to oxidation by H2O2, whereas GDP-bound EF-Tu was resistant to H2O2. The inactivation of EF-Tu was the result of oxidation of Cys-82, a single cysteine residue, and subsequent formation of both an intermolecular disulfide bond and sulfenic acid. Replacement of Cys-82 with serine rendered EF-Tu resistant to inactivation by H2O2, confirming that Cys-82 was a target of oxidation. Furthermore, oxidized EF-Tu was reduced and reactivated by thioredoxin. Gel-filtration chromatography revealed that some of the oxidized nucleotide-free EF-Tu formed large complexes of >30 molecules. Atomic force microscopy revealed that such large complexes dissociated into several smaller aggregates upon the addition of dithiothreitol. Immunological analysis of the redox state of EF-Tu in vivo showed that levels of oxidized EF-Tu increased under strong light. Thus, resembling elongation factor G, EF-Tu appears to be sensitive to ROS via oxidation of a cysteine residue, and its inactivation might be reversed in a redox-dependent manner.

  6. Functional differentiation of two analogous coproporphyrinogen III oxidases for heme and chlorophyll biosynthesis pathways in the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Goto, Takeaki; Aoki, Rina; Minamizaki, Kei; Fujita, Yuichi

    2010-04-01

    Coproporphyrinogen III oxidase (CPO) catalyzes the oxidative decarboxylation of coproporphyrinogen III to form protoporphyrinogen IX in heme biosynthesis and is shared in chlorophyll biosynthesis in photosynthetic organisms. There are two analogous CPOs, oxygen-dependent (HemF) and oxygen-independent (HemN) CPOs, in various organisms. Little information on cyanobacterial CPOs has been available to date. In the genome of the cyanobacterium Synechocystis sp. PCC 6803 there is one hemF-like gene, sll1185, and two hemN-like genes, sll1876 and sll1917. The three genes were overexpressed in Escherichia coli and purified to homogeneity. Sll1185 showed CPO activity under both aerobic and anaerobic conditions. While Sll1876 and Sll1917 showed absorbance spectra indicative of Fe-S proteins, only Sll1876 showed CPO activity under anaerobic conditions. Three mutants lacking one of these genes were isolated. The Deltasll1185 mutant failed to grow under aerobic conditions, with accumulation of coproporphyrin III. This growth defect was restored by cultivation under micro-oxic conditions. The growth of the Deltasll1876 mutant was significantly slower than that of the wild type under micro-oxic conditions, while it grew normally under aerobic conditions. Coproporphyrin III was accumulated at a low but significant level in the Deltasll1876 mutant grown under micro-oxic conditions. There was no detectable phenotype in Deltasll1917 under the conditions we examined. These results suggested that sll1185 encodes HemF as the sole CPO under aerobic conditions and that sll1876 encodes HemN operating under micro-oxic conditions, together with HemF. Such a differential operation of CPOs would ensure the stable supply of tetrapyrrole pigments under environments where oxygen levels fluctuate greatly.

  7. Genetic Analysis of the Hox Hydrogenase in the Cyanobacterium Synechocystis sp. PCC 6803 Reveals Subunit Roles in Association, Ass