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Sample records for acetyltransferase hat complex

  1. Role of Jade-1 in the histone acetyltransferase (HAT) HBO1 complex.

    PubMed

    Foy, Rebecca L; Song, Ihn Young; Chitalia, Vipul C; Cohen, Herbert T; Saksouk, Nehme; Cayrou, Christelle; Vaziri, Cyrus; Côté, Jacques; Panchenko, Maria V

    2008-10-24

    Regulation of global chromatin acetylation is important for chromatin remodeling. A small family of Jade proteins includes Jade-1L, Jade-2, and Jade-3, each bearing two mid-molecule tandem plant homology domain (PHD) zinc fingers. We previously demonstrated that the short isoform of Jade-1L protein, Jade-1, is associated with endogenous histone acetyltransferase (HAT) activity. It has been found that Jade-1L/2/3 proteins co-purify with a novel HAT complex, consisting of HBO1, ING4/5, and Eaf6. We investigated a role for Jade-1/1L in the HBO1 complex. When overexpressed individually, neither Jade-1/1L nor HBO1 affected histone acetylation. However, co-expression of Jade-1/1L and HBO1 increased acetylation of the bulk of endogenous histone H4 in epithelial cells in a synergistic manner, suggesting that Jade1/1L positively regulates HBO1 HAT activity. Conversely, small interfering RNA-mediated depletion of endogenous Jade resulted in reduced levels of H4 acetylation. Moreover, HBO1-mediated H4 acetylation activity was enhanced severalfold by the presence of Jade-1/1L in vitro. The removal of PHD fingers affected neither binding nor mutual Jade-1-HBO1 stabilization but completely abrogated the synergistic Jade-1/1L- and HBO1-mediated histone H4 acetylation in live cells and in vitro with reconstituted oligonucleosome substrates. Therefore, PHDs are necessary for Jade-1/1L-induced acetylation of nucleosomal histones by HBO1. In contrast to Jade-1/1L, the PHD zinc finger protein ING4/5 failed to synergize with HBO1 to promote histone acetylation. The physical interaction of ING4/5 with HBO1 occurred in the presence of Jade-1L or Jade-3 but not with the Jade-1 short isoform. In summary, this study demonstrates that Jade-1/1L are crucial co-factors for HBO1-mediated histone H4 acetylation.

  2. Dissecting the Molecular Roles of Histone Chaperones in Histone Acetylation by Type B Histone Acetyltransferases (HAT-B).

    PubMed

    Haigney, Allison; Ricketts, M Daniel; Marmorstein, Ronen

    2015-12-18

    The HAT-B enzyme complex is responsible for acetylating newly synthesized histone H4 on lysines K5 and K12. HAT-B is a multisubunit complex composed of the histone acetyltransferase 1 (Hat1) catalytic subunit and the Hat2 (rbap46) histone chaperone. Hat1 is predominantly localized in the nucleus as a member of a trimeric NuB4 complex containing Hat1, Hat2, and a histone H3-H4 specific histone chaperone called Hif1 (NASP). In addition to Hif1 and Hat2, Hat1 interacts with Asf1 (anti-silencing function 1), a histone chaperone that has been reported to be involved in both replication-dependent and -independent chromatin assembly. To elucidate the molecular roles of the Hif1 and Asf1 histone chaperones in HAT-B histone binding and acetyltransferase activity, we have characterized the stoichiometry and binding mode of Hif1 and Asf1 to HAT-B and the effect of this binding on the enzymatic activity of HAT-B. We find that Hif1 and Asf1 bind through different modes and independently to HAT-B, whereby Hif1 binds directly to Hat2, and Asf1 is only capable of interactions with HAT-B through contacts with histones H3-H4. We also demonstrate that HAT-B is significantly more active against an intact H3-H4 heterodimer over a histone H4 peptide, independent of either Hif1 or Asf1 binding. Mutational studies further demonstrate that HAT-B binding to the histone tail regions is not sufficient for this enhanced activity. Based on these data, we propose a model for HAT-B/histone chaperone assembly and acetylation of H3-H4 complexes.

  3. A novel role for the histone acetyltransferase Hat1 in the CENP-A/CID assembly pathway in Drosophila melanogaster

    PubMed Central

    Boltengagen, Mark; Huang, Anming; Boltengagen, Anastasiya; Trixl, Lukas; Lindner, Herbert; Kremser, Leopold; Offterdinger, Martin; Lusser, Alexandra

    2016-01-01

    The incorporation of CENP-A into centromeric chromatin is an essential prerequisite for kinetochore formation. Yet, the molecular mechanisms governing this process are surprisingly divergent in different organisms. While CENP-A loading mechanisms have been studied in some detail in mammals, there are still large gaps to our understanding of CENP-A/Cid loading pathways in Drosophila. Here, we report on the characterization and delineation of at least three different CENP-A preloading complexes in Drosophila. Two complexes contain the CENP-A chaperones CAL1, FACT and/or Caf1/Rbap48. Notably, we identified a novel complex consisting of the histone acetyltransferase Hat1, Caf1 and CENP-A/H4. We show that Hat1 is required for proper CENP-A loading into chromatin, since knock-down in S2 cells leads to reduced incorporation of newly synthesized CENP-A. In addition, we demonstrate that CENP-A/Cid interacts with the HAT1 complex via an N-terminal region, which is acetylated in cytoplasmic but not in nuclear CENP-A. Since Hat1 is not responsible for acetylation of CENP-A/Cid, these results suggest a histone acetyltransferase activity-independent escort function for Hat1. Thus, our results point toward intriguing analogies between the complex processing pathways of newly synthesized CENP-A and canonical histones. PMID:26586808

  4. Comparison of Protein Acetyltransferase Action of CRTAase with the Prototypes of HAT

    PubMed Central

    Ponnan, Prija; Kumar, Ajit; Singh, Prabhjot; Gupta, Prachi; Joshi, Rini; Saso, Luciano; Prasad, Ashok K.; Rastogi, Ramesh C.; Parmar, Virinder S.; Raj, Hanumantharao G.

    2014-01-01

    Our laboratory is credited for the discovery of enzymatic acetylation of protein, a phenomenon unknown till we identified an enzyme termed acetoxy drug: protein transacetylase (TAase), catalyzing the transfer of acetyl group from polyphenolic acetates to receptor proteins (RP). Later, TAase was identified as calreticulin (CR), an endoplasmic reticulum luminal protein. CR was termed calreticulin transacetylase (CRTAase). Our persistent study revealed that CR like other families of histone acetyltransferases (HATs) such as p300, Rtt109, PCAF, and ESA1, undergoes autoacetylation. The autoacetylated CR was characterized as a stable intermediate in CRTAase catalyzed protein acetylation, and similar was the case with ESA1. The autoacetylation of CR like that of HATs was found to enhance protein-protein interaction. CR like HAT-1, CBP, and p300 mediated the acylation of RP utilizing acetyl CoA and propionyl CoA as the substrates. The similarities between CRTAase and HATs in mediating protein acylation are highlighted in this review. PMID:24688408

  5. The Candida albicans Histone Acetyltransferase Hat1 Regulates Stress Resistance and Virulence via Distinct Chromatin Assembly Pathways

    PubMed Central

    Tscherner, Michael; Zwolanek, Florian; Jenull, Sabrina; Sedlazeck, Fritz J.; Petryshyn, Andriy; Frohner, Ingrid E.; Mavrianos, John; Chauhan, Neeraj; von Haeseler, Arndt; Kuchler, Karl

    2015-01-01

    Human fungal pathogens like Candida albicans respond to host immune surveillance by rapidly adapting their transcriptional programs. Chromatin assembly factors are involved in the regulation of stress genes by modulating the histone density at these loci. Here, we report a novel role for the chromatin assembly-associated histone acetyltransferase complex NuB4 in regulating oxidative stress resistance, antifungal drug tolerance and virulence in C. albicans. Strikingly, depletion of the NuB4 catalytic subunit, the histone acetyltransferase Hat1, markedly increases resistance to oxidative stress and tolerance to azole antifungals. Hydrogen peroxide resistance in cells lacking Hat1 results from higher induction rates of oxidative stress gene expression, accompanied by reduced histone density as well as subsequent increased RNA polymerase recruitment. Furthermore, hat1Δ/Δ cells, despite showing growth defects in vitro, display reduced susceptibility to reactive oxygen-mediated killing by innate immune cells. Thus, clearance from infected mice is delayed although cells lacking Hat1 are severely compromised in killing the host. Interestingly, increased oxidative stress resistance and azole tolerance are phenocopied by the loss of histone chaperone complexes CAF-1 and HIR, respectively, suggesting a central role for NuB4 in the delivery of histones destined for chromatin assembly via distinct pathways. Remarkably, the oxidative stress phenotype of hat1Δ/Δ cells is a species-specific trait only found in C. albicans and members of the CTG clade. The reduced azole susceptibility appears to be conserved in a wider range of fungi. Thus, our work demonstrates how highly conserved chromatin assembly pathways can acquire new functions in pathogenic fungi during coevolution with the host. PMID:26473952

  6. Histone acetyltransferase HAT4 modulates navigation across G2/M and re-entry into G1 in Leishmania donovani

    PubMed Central

    Yadav, Aarti; Chandra, Udita; Saha, Swati

    2016-01-01

    Histone acetyltransferases impact multiple processes. This study investigates the role of histone acetyltransferase HAT4 in Leishmania donovani. Though HAT4 was dispensable for survival, its elimination decreased cell viability and caused cell cycle defects, with HAT4-nulls experiencing an unusually long G2/M. Survival of HAT4-nulls in macrophages was also substantially compromised. DNA microarray analysis revealed that HAT4 modestly regulated the expression of only a select number of genes, thus not being a major modulator of global gene expression. Significantly, cdc20 was among the downregulated genes. To ascertain if decreased expression of cdc20 was responsible for HAT4-null growth and cell cycle defects we expressed LdCdc20 ectopically in HAT4-nulls. We found this to alleviate the aberrant growth and cell cycle progression patterns displayed by HAT4-nulls, with cells navigating G2/M phase and re-entering G1 phase smoothly. HAT4-nulls expressing LdCdc20 ectopically showed survival rates comparable to wild type within macrophages, suggesting that G2/M defects were responsible for poor survival of HAT4-nulls within host cells also. These are the first data analyzing the in vivo functional role of HAT4 in any trypanosomatid. Our results directly demonstrate for the first time a role for Cdc20 in regulating trypanosomatid G2/M events, opening avenues for further research in this area. PMID:27272906

  7. The acetyltransferase HAT1 moderates the NF-κB response by regulating the transcription factor PLZF.

    PubMed

    Sadler, Anthony J; Suliman, Bandar A; Yu, Liang; Yuan, Xiangliang; Wang, Die; Irving, Aaron T; Sarvestani, Soroush T; Banerjee, Ashish; Mansell, Ashley S; Liu, Jun-Ping; Gerondakis, Steve; Williams, Bryan R G; Xu, Dakang

    2015-04-13

    To date, the activities of protein kinases have formed the core of our understanding of cell signal transduction. Comprehension of the extent of protein acetylation has raised expectations that this alternate post-transcriptional modification will be shown to rival phosphorylation in its importance in mediating cellular responses. However, limited instances have been identified. Here we show that signalling from Toll-like or TNF-α receptors triggers the calcium/calmodulin-dependent protein kinase (CaMK2) to activate histone acetyltransferase-1 (HAT1), which then acetylates the transcriptional regulator PLZF. Acetylation of PLZF promotes the assembly of a repressor complex incorporating HDAC3 and the NF-κB p50 subunit that limits the NF-κB response. Accordingly, diminishing the activity of CaMK2, the expression levels of PLZF or HAT1, or mutating key residues that are covalently modified in PLZF and HAT1, curtails control of the production of inflammatory cytokines. These results identify a central role for acetylation in controlling the inflammatory NF-κB transcriptional programme.

  8. The acetyltransferase HAT1 moderates the NF-κB response by regulating the transcription factor PLZF.

    PubMed

    Sadler, Anthony J; Suliman, Bandar A; Yu, Liang; Yuan, Xiangliang; Wang, Die; Irving, Aaron T; Sarvestani, Soroush T; Banerjee, Ashish; Mansell, Ashley S; Liu, Jun-Ping; Gerondakis, Steve; Williams, Bryan R G; Xu, Dakang

    2015-01-01

    To date, the activities of protein kinases have formed the core of our understanding of cell signal transduction. Comprehension of the extent of protein acetylation has raised expectations that this alternate post-transcriptional modification will be shown to rival phosphorylation in its importance in mediating cellular responses. However, limited instances have been identified. Here we show that signalling from Toll-like or TNF-α receptors triggers the calcium/calmodulin-dependent protein kinase (CaMK2) to activate histone acetyltransferase-1 (HAT1), which then acetylates the transcriptional regulator PLZF. Acetylation of PLZF promotes the assembly of a repressor complex incorporating HDAC3 and the NF-κB p50 subunit that limits the NF-κB response. Accordingly, diminishing the activity of CaMK2, the expression levels of PLZF or HAT1, or mutating key residues that are covalently modified in PLZF and HAT1, curtails control of the production of inflammatory cytokines. These results identify a central role for acetylation in controlling the inflammatory NF-κB transcriptional programme. PMID:25865065

  9. Heparanase-mediated Loss of Nuclear Syndecan-1 Enhances Histone Acetyltransferase (HAT) Activity to Promote Expression of Genes That Drive an Aggressive Tumor Phenotype*

    PubMed Central

    Purushothaman, Anurag; Hurst, Douglas R.; Pisano, Claudio; Mizumoto, Shuji; Sugahara, Kazuyuki; Sanderson, Ralph D.

    2011-01-01

    Heparanase acts as a master regulator of the aggressive tumor phenotype in part by enhancing expression of proteins known to drive tumor progression (e.g. VEGF, MMP-9, hepatocyte growth factor (HGF), and RANKL). However, the mechanism whereby this enzyme regulates gene expression remains unknown. We previously reported that elevation of heparanase levels in myeloma cells causes a dramatic reduction in the amount of syndecan-1 in the nucleus. Because syndecan-1 has heparan sulfate chains and because exogenous heparan sulfate has been shown to inhibit the activity of histone acetyltransferase (HAT) enzymes in vitro, we hypothesized that the reduction in nuclear syndecan-1 in cells expressing high levels of heparanase would result in increased HAT activity leading to stimulation of protein transcription. We found that myeloma cells or tumors expressing high levels of heparanase and low levels of nuclear syndecan-1 had significantly higher levels of HAT activity when compared with cells or tumors expressing low levels of heparanase. High levels of HAT activity in heparanase-high cells were blocked by SST0001, an inhibitor of heparanase. Restoration of high syndecan-1 levels in heparanase-high cells diminished nuclear HAT activity, establishing syndecan-1 as a potent inhibitor of HAT. Exposure of heparanase-high cells to anacardic acid, an inhibitor of HAT activity, significantly suppressed their expression of VEGF and MMP-9, two genes known to be up-regulated following elevation of heparanase. These results reveal a novel mechanistic pathway driven by heparanase expression, which leads to decreased nuclear syndecan-1, increased HAT activity, and up-regulation of transcription of multiple genes that drive an aggressive tumor phenotype. PMID:21757697

  10. Molecular functions of the histone acetyltransferase chaperone complex Rtt109-Vps75

    SciTech Connect

    Berndsen, Christopher E; Tsubota, Toshiaki; Lindner, Scott E; Lee, Susan; Holton, James M; Kaufman, Paul D; Keck, James L; Denu, John M

    2010-01-12

    Histone acetylation and nucleosome remodeling regulate DNA damage repair, replication and transcription. Rtt109, a recently discovered histone acetyltransferase (HAT) from Saccharomyces cerevisiae, functions with the histone chaperone Asf1 to acetylate lysine K56 on histone H3 (H3K56), a modification associated with newly synthesized histones. In vitro analysis of Rtt109 revealed that Vps75, a Nap1 family histone chaperone, could also stimulate Rtt109-dependent acetylation of H3K56. However, the molecular function of the Rtt109-Vps75 complex remains elusive. Here we have probed the molecular functions of Vps75 and the Rtt109-Vps75 complex through biochemical, structural and genetic means. We find that Vps75 stimulates the kcat of histone acetylation by {approx}100-fold relative to Rtt109 alone and enhances acetylation of K9 in the H3 histone tail. Consistent with the in vitro evidence, cells lacking Vps75 showed a substantial reduction (60%) in H3K9 acetylation during S phase. X-ray structural, biochemical and genetic analyses of Vps75 indicate a unique, structurally dynamic Nap1-like fold that suggests a potential mechanism of Vps75-dependent activation of Rtt109. Together, these data provide evidence for a multifunctional HAT-chaperone complex that acetylates histone H3 and deposits H3-H4 onto DNA, linking histone modification and nucleosome assembly.

  11. The Set3 Complex Antagonizes the MYST Acetyltransferase Esa1 in the DNA Damage Response

    PubMed Central

    Torres-Machorro, Ana Lilia; Clark, Lauren G.; Chang, Christie S.

    2015-01-01

    Acetylation is a dynamic posttranslational modification that contributes to chromatin-regulated processes, including DNA replication, repair, recombination, and gene expression. Acetylation is controlled by complexes containing opposing lysine and histone acetyltransferase (KAT and HAT) and deacetylase (KDAC and HDAC) activities. The essential MYST family Esa1 KAT acetylates core histones and many nonhistone substrates. Phenotypes of esa1 mutants include transcriptional silencing and activation defects, impaired growth at high temperatures, and sensitivity to DNA damage. The KDAC Rpd3 was previously identified as an activity opposing Esa1, as its deletion suppresses growth and silencing defects of esa1 mutants. However, loss of Rpd3 does not suppress esa1 DNA damage sensitivity. In this work, we identified Hos2 as a KDAC counteracting ESA1 in the damage response. Deletion of HOS2 resulted in changes of esa1's transcriptional response upon damage. Further, loss of HOS2 or components of the Set3 complex (Set3C) in which it acts specifically suppressed damage sensitivity and restored esa1 histone H4 acetylation. This rescue was mediated via loss of either Set3C integrity or of its binding to dimethylated histone H3K4. Our results thus add new insight into the interactions of an essential MYST acetyltransferase with diverse deacetylases to respond specifically to environmental and physiological challenges. PMID:26303527

  12. Subunits of ADA-two-A-containing (ATAC) or Spt-Ada-Gcn5-acetyltrasferase (SAGA) Coactivator Complexes Enhance the Acetyltransferase Activity of GCN5.

    PubMed

    Riss, Anne; Scheer, Elisabeth; Joint, Mathilde; Trowitzsch, Simon; Berger, Imre; Tora, László

    2015-11-27

    Histone acetyl transferases (HATs) play a crucial role in eukaryotes by regulating chromatin architecture and locus specific transcription. GCN5 (KAT2A) is a member of the GNAT (Gcn5-related N-acetyltransferase) family of HATs. In metazoans this enzyme is found in two functionally distinct coactivator complexes, SAGA (Spt Ada Gcn5 acetyltransferase) and ATAC (Ada Two A-containing). These two multiprotein complexes comprise complex-specific and shared subunits, which are organized in functional modules. The HAT module of ATAC is composed of GCN5, ADA2a, ADA3, and SGF29, whereas in the SAGA HAT module ADA2b is present instead of ADA2a. To better understand how the activity of human (h) hGCN5 is regulated in the two related, but different, HAT complexes we carried out in vitro HAT assays. We compared the activity of hGCN5 alone with its activity when it was part of purified recombinant hATAC or hSAGA HAT modules or endogenous hATAC or hSAGA complexes using histone tail peptides and full-length histones as substrates. We demonstrated that the subunit environment of the HAT complexes into which GCN5 incorporates determines the enhancement of GCN5 activity. On histone peptides we show that all the tested GCN5-containing complexes acetylate mainly histone H3K14. Our results suggest a stronger influence of ADA2b as compared with ADA2a on the activity of GCN5. However, the lysine acetylation specificity of GCN5 on histone tails or full-length histones was not changed when incorporated in the HAT modules of ATAC or SAGA complexes. Our results thus demonstrate that the catalytic activity of GCN5 is stimulated by subunits of the ADA2a- or ADA2b-containing HAT modules and is further increased by incorporation of the distinct HAT modules in the ATAC or SAGA holo-complexes.

  13. Structural and Functional Conservation of the NuA4 Histone Acetyltransferase Complex from Yeast to Humans

    PubMed Central

    Doyon, Yannick; Selleck, William; Lane, William S.; Tan, Song; Côté, Jacques

    2004-01-01

    The NuA4 histone acetyltransferase (HAT) multisubunit complex is responsible for acetylation of histone H4 and H2A N-terminal tails in yeast. Its catalytic component, Esa1, is essential for cell cycle progression, gene-specific regulation and has been implicated in DNA repair. Almost all NuA4 subunits have clear homologues in higher eukaryotes, suggesting that the complex is conserved throughout evolution to metazoans. We demonstrate here that NuA4 complexes are indeed present in human cells. Tip60 and its splice variant Tip60b/PLIP were purified as stable HAT complexes associated with identical polypeptides, with 11 of the 12 proteins being homologs of yeast NuA4 subunits. This indicates a highly conserved subunit composition and the identified human proteins underline the role of NuA4 in the control of mammalian cell proliferation. ING3, a member of the ING family of growth regulators, links NuA4 to p53 function which we confirmed in vivo. Proteins specific to the human NuA4 complexes include ruvB-like helicases and a bromodomain-containing subunit linked to ligand-dependent transcription activation by the thyroid hormone receptor. We also demonstrate that subunits MRG15 and DMAP1 are present in distinct protein complexes harboring histone deacetylase and SWI2-related ATPase activities, respectively. Finally, analogous to yeast, a recombinant trimeric complex formed by Tip60, EPC1, and ING3 is sufficient to reconstitute robust nucleosomal HAT activity in vitro. In conclusion, the NuA4 HAT complex is highly conserved in eukaryotes, in which it plays primary roles in transcription, cellular response to DNA damage, and cell cycle control. PMID:14966270

  14. Inhibition of different histone acetyltransferases (HATs) uncovers transcription-dependent and -independent acetylation-mediated mechanisms in memory formation.

    PubMed

    Merschbaecher, Katja; Hatko, Lucyna; Folz, Jennifer; Mueller, Uli

    2016-02-01

    Acetylation of histones changes the efficiency of the transcription processes and thus contributes to the formation of long-term memory (LTM). In our comparative study, we used two inhibitors to characterize the contribution of different histone acetyl transferases (HATs) to appetitive associative learning in the honeybee. For one we applied garcinol, an inhibitor of the HATs of the p300 (EP300 binding protein)/CBP (CREB-binding protein) family, and the HATs of the PCAF (p300/CBP-associated factor) family. As comparative agent we applied C646, a specific inhibitor that selectively blocks HATS of the p300/CBP family. Immunochemical analysis reveals differences in histone H3 acetylation in the honeybee brain, in response to the injection of either C646 or garcinol. Behavioral assessment reveals that the two drugs cause memory impairment of different nature when injected after associative conditioning: processes disturbed by garcinol are annihilated by the established transcription blocker actinomycin D and thus seem to require transcription processes. Actions of C646 are unaltered by actinomycin D, and thus seem to be independent of transcription. The outcome of our different approaches as summarized suggests that distinct HATs contribute to different acetylation-mediated processes in memory formation. We further deduce that the acetylation-mediated processes in memory formation comprise transcription-dependent and transcription-independent mechanisms.

  15. Inhibition of Different Histone Acetyltransferases (HATs) Uncovers Transcription-Dependent and -Independent Acetylation-Mediated Mechanisms in Memory Formation

    ERIC Educational Resources Information Center

    Merschbaecher, Katja; Hatko, Lucyna; Folz, Jennifer; Mueller, Uli

    2016-01-01

    Acetylation of histones changes the efficiency of the transcription processes and thus contributes to the formation of long-term memory (LTM). In our comparative study, we used two inhibitors to characterize the contribution of different histone acetyl transferases (HATs) to appetitive associative learning in the honeybee. For one we applied…

  16. Structure of soybean serine acetyltransferase and formation of the cysteine regulatory complex as a molecular chaperone

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Serine acetyltransferase (SAT) catalyzes the limiting reaction in plant and microbial biosynthesis of cysteine. In addition to its enzymatic function, SAT forms a macromolecular complex with O-acetylserine sulfhydrylase (OASS). Formation of the cysteine regulatory complex (CRC) is a critical biochem...

  17. Subunit Composition and Substrate Specificity of a MOF-containing Histone Acetyltransferase Distinct from the Male-specific Lethal (MSL) Complex*

    PubMed Central

    Cai, Yong; Jin, Jingji; Swanson, Selene K.; Cole, Michael D.; Choi, Seung Hyuk; Florens, Laurence; Washburn, Michael P.; Conaway, Joan W.; Conaway, Ronald C.

    2010-01-01

    Human MOF (MYST1), a member of the MYST (Moz-Ybf2/Sas3-Sas2-Tip60) family of histone acetyltransferases (HATs), is the human ortholog of the Drosophila males absent on the first (MOF) protein. MOF is the catalytic subunit of the male-specific lethal (MSL) HAT complex, which plays a key role in dosage compensation in the fly and is responsible for a large fraction of histone H4 lysine 16 (H4K16) acetylation in vivo. MOF was recently reported to be a component of a second HAT complex, designated the non-specific lethal (NSL) complex (Mendjan, S., Taipale, M., Kind, J., Holz, H., Gebhardt, P., Schelder, M., Vermeulen, M., Buscaino, A., Duncan, K., Mueller, J., Wilm, M., Stunnenberg, H. G., Saumweber, H., and Akhtar, A. (2006) Mol. Cell 21, 811–823). Here we report an analysis of the subunit composition and substrate specificity of the NSL complex. Proteomic analyses of complexes purified through multiple candidate subunits reveal that NSL is composed of nine subunits. Two of its subunits, WD repeat domain 5 (WDR5) and host cell factor 1 (HCF1), are shared with members of the MLL/SET family of histone H3 lysine 4 (H3K4) methyltransferase complexes, and a third subunit, MCRS1, is shared with the human INO80 chromatin-remodeling complex. In addition, we show that assembly of the MOF HAT into MSL or NSL complexes controls its substrate specificity. Although MSL-associated MOF acetylates nucleosomal histone H4 almost exclusively on lysine 16, NSL-associated MOF exhibits a relaxed specificity and also acetylates nucleosomal histone H4 on lysines 5 and 8. PMID:20018852

  18. Structure and nucleosome interaction of the yeast NuA4 and Piccolo-NuA4 histone acetyltransferase complexes.

    PubMed

    Chittuluru, Johnathan R; Chaban, Yuriy; Monnet-Saksouk, Julie; Carrozza, Michael J; Sapountzi, Vasileia; Selleck, William; Huang, Jiehuan; Utley, Rhea T; Cramet, Myriam; Allard, Stephane; Cai, Gang; Workman, Jerry L; Fried, Michael G; Tan, Song; Côté, Jacques; Asturias, Francisco J

    2011-10-09

    We have used EM and biochemistry to characterize the structure of NuA4, an essential yeast histone acetyltransferase (HAT) complex conserved throughout eukaryotes, and we have determined the interaction of NuA4 with the nucleosome core particle (NCP). The ATM-related Tra1 subunit, which is shared with the SAGA coactivator complex, forms a large domain joined to a second region that accommodates the catalytic subcomplex Piccolo and other NuA4 subunits. EM analysis of a NuA4-NCP complex shows the NCP bound at the periphery of NuA4. EM characterization of Piccolo and Piccolo-NCP provided further information about subunit organization and confirmed that histone acetylation requires minimal contact with the NCP. A small conserved region at the N terminus of Piccolo subunit enhancer of Polycomb-like 1 (Epl1) is essential for NCP interaction, whereas the subunit yeast homolog of mammalian Ing1 2 (Yng2) apparently positions Piccolo for efficient acetylation of histone H4 or histone H2A tails. Taken together, these results provide an understanding of the NuA4 subunit organization and the NuA4-NCP interactions.

  19. Structure and nucleosome interaction of the yeast NuA4 and Piccolo-NuA4 histone acetyltransferase complexes

    PubMed Central

    Chittuluru, Johnathan R.; Chaban, Yuriy; Monnet-Saksouk, Julie; Carrozza, Michael J.; Sapountzi, Vasileia; Selleck, William; Huang, Jiehuan; Utley, Rhea T.; Cramet, Myriam; Allard, Stephane; Cai, Gang; Workman, Jerry L.; Fried, Michael G.; Tan, Song; Côté, Jacques; Asturias, Francisco J.

    2011-01-01

    We have used electron microscopy (EM) and biochemistry to characterize the structure and nucleosome core particle (NCP) interaction of NuA4, an essential yeast histone acetyltransferase (HAT) complex conserved throughout eukaryotes. The ATM-related Tra1 subunit, shared with the SAGA coactivator, forms a large domain joined to a second portion that accommodates the Piccolo catalytic subcomplex and other NuA4 subunits. EM analysis of an NuA4–NCP complex shows the NCP bound at NuA4's periphery. EM characterization of Piccolo and Piccolo–NCP provided further information about subunit organization and confirmed that histone acetylation requires minimal contact with the NCP. A small conserved region at the N-terminus of Piccolo subunit Epl1 is essential for NCP interaction, whereas subunit Yng2 apparently positions Piccolo for efficient acetylation of H4 or H2A tails. Taken together, these results provide an understanding of NuA4 subunit organization and NCP interactions. PMID:21984211

  20. G9a-mediated methylation of ERα links the PHF20/MOF histone acetyltransferase complex to hormonal gene expression

    PubMed Central

    Zhang, Xi; Peng, Danni; Xi, Yuanxin; Yuan, Chao; Sagum, Cari A.; Klein, Brianna J.; Tanaka, Kaori; Wen, Hong; Kutateladze, Tatiana G.; Li, Wei; Bedford, Mark T.; Shi, Xiaobing

    2016-01-01

    The euchromatin histone methyltransferase 2 (also known as G9a) methylates histone H3K9 to repress gene expression, but it also acts as a coactivator for some nuclear receptors. The molecular mechanisms underlying this activation remain elusive. Here we show that G9a functions as a coactivator of the endogenous oestrogen receptor α (ERα) in breast cancer cells in a histone methylation-independent manner. G9a dimethylates ERα at K235 both in vitro and in cells. Dimethylation of ERαK235 is recognized by the Tudor domain of PHF20, which recruits the MOF histone acetyltransferase (HAT) complex to ERα target gene promoters to deposit histone H4K16 acetylation promoting active transcription. Together, our data suggest the molecular mechanism by which G9a functions as an ERα coactivator. Along with the PHF20/MOF complex, G9a links the crosstalk between ERα methylation and histone acetylation that governs the epigenetic regulation of hormonal gene expression. PMID:26960573

  1. Expression profiling of S. pombe acetyltransferase mutants identifies redundant pathways of gene regulation

    PubMed Central

    2010-01-01

    Background Histone acetyltransferase enzymes (HATs) are implicated in regulation of transcription. HATs from different families may overlap in target and substrate specificity. Results We isolated the elp3+ gene encoding the histone acetyltransferase subunit of the Elongator complex in fission yeast and characterized the phenotype of an Δelp3 mutant. We examined genetic interactions between Δelp3 and two other HAT mutants, Δmst2 and Δgcn5 and used whole genome microarray analysis to analyze their effects on gene expression. Conclusions Comparison of phenotypes and expression profiles in single, double and triple mutants indicate that these HAT enzymes have overlapping functions. Consistent with this, overlapping specificity in histone H3 acetylation is observed. However, there is no evidence for overlap with another HAT enzyme, encoded by the essential mst1+ gene. PMID:20096118

  2. The Transcriptional Histone Acetyltransferase Cofactor TRRAP Associates with the MRN Repair Complex and Plays a Role in DNA Double-Strand Break Repair†

    PubMed Central

    Robert, Flavie; Hardy, Sara; Nagy, Zita; Baldeyron, Céline; Murr, Rabih; Déry, Ugo; Masson, Jean-Yves; Papadopoulo, Dora; Herceg, Zdenko; Tora, Làszlò

    2006-01-01

    Transactivation-transformation domain-associated protein (TRRAP) is a component of several multiprotein histone acetyltransferase (HAT) complexes implicated in transcriptional regulation. TRRAP was shown to be required for the mitotic checkpoint and normal cell cycle progression. MRE11, RAD50, and NBS1 (product of the Nijmegan breakage syndrome gene) form the MRN complex that is involved in the detection, signaling, and repair of DNA double-strand breaks (DSBs). By using double immunopurification, mass spectrometry, and gel filtration, we describe the stable association of TRRAP with the MRN complex. The TRRAP-MRN complex is not associated with any detectable HAT activity, while the isolated other TRRAP complexes, containing either GCN5 or TIP60, are. TRRAP-depleted extracts show a reduced nonhomologous DNA end-joining activity in vitro. Importantly, small interfering RNA knockdown of TRRAP in HeLa cells or TRRAP knockout in mouse embryonic stem cells inhibit the DSB end-joining efficiency and the precise nonhomologous end-joining process, further suggesting a functional involvement of TRRAP in the DSB repair processes. Thus, TRRAP may function as a molecular link between DSB signaling, repair, and chromatin remodeling. PMID:16382133

  3. Conformational flexibility and subunit arrangement of the modular yeast Spt-Ada-Gcn5 acetyltransferase complex.

    PubMed

    Setiaputra, Dheva; Ross, James D; Lu, Shan; Cheng, Derrick T; Dong, Meng-Qiu; Yip, Calvin K

    2015-04-17

    The Spt-Ada-Gcn5 acetyltransferase (SAGA) complex is a highly conserved, 19-subunit histone acetyltransferase complex that activates transcription through acetylation and deubiquitination of nucleosomal histones in Saccharomyces cerevisiae. Because SAGA has been shown to display conformational variability, we applied gradient fixation to stabilize purified SAGA and systematically analyzed this flexibility using single-particle EM. Our two- and three-dimensional studies show that SAGA adopts three major conformations, and mutations of specific subunits affect the distribution among these. We also located the four functional modules of SAGA using electron microscopy-based labeling and transcriptional activator binding analyses and show that the acetyltransferase module is localized in the most mobile region of the complex. We further comprehensively mapped the subunit interconnectivity of SAGA using cross-linking mass spectrometry, revealing that the Spt and Taf subunits form the structural core of the complex. These results provide the necessary restraints for us to generate a model of the spatial arrangement of all SAGA subunits. According to this model, the chromatin-binding domains of SAGA are all clustered in one face of the complex that is highly flexible. Our results relate information of overall SAGA structure with detailed subunit level interactions, improving our understanding of its architecture and flexibility.

  4. Pygo2 associates with MLL2 histone methyltransferase and GCN5 histone acetyltransferase complexes to augment Wnt target gene expression and breast cancer stem-like cell expansion.

    PubMed

    Chen, Jiakun; Luo, Qicong; Yuan, Yuanyang; Huang, Xiaoli; Cai, Wangyu; Li, Chao; Wei, Tongzhen; Zhang, Ludi; Yang, Meng; Liu, Qingfeng; Ye, Guodong; Dai, Xing; Li, Boan

    2010-12-01

    Resent studies have identified Pygopus as a core component of the β-catenin/T-cell factor (TCF)/lymphoid-enhancing factor 1 (LEF) transcriptional activation complex required for the expression of canonical Wg/Wnt target genes in Drosophila. However, the biochemical involvement of mammalian Pygopus proteins in β-catenin/TCF/LEF gene activation remains controversial. In this study, we perform a series of molecular/biochemical experiments to demonstrate that Pygo2 associates with histone-modifying enzymatic complexes, specifically the MLL2 histone methyltransferase (HMT) and STAGA histone acetyltransferase (HAT) complexes, to facilitate their interaction with β-catenin and to augment Wnt1-induced, TCF/LEF-dependent transcriptional activation in breast cancer cells. We identify a critical domain in Pygo2 encompassing the first 47 amino acids that mediates its HMT/HAT interaction. We further demonstrate the importance of this domain in Pygo2's ability to transcriptionally activate both artificial and endogenous Wnt target genes and to expand breast cancer stem-like cells in culture. This work now links mechanistically Pygo2's role in histone modification to its enhancement of the Wnt-dependent transcriptional program and cancer stem-like cell expansion.

  5. The Something About Silencing protein, Sas3, is the catalytic subunit of NuA3, a yTAFII30-containing HAT complex that interacts with the Spt16 subunit of the yeast CP (Cdc68/Pob3)–FACT complex

    PubMed Central

    John, Sam; Howe, LeAnn; Tafrov, Stefan T.; Grant, Patrick A.; Sternglanz, Rolf; Workman, Jerry L.

    2000-01-01

    We have purified and characterized a Gcn5-independent nucleosomal histone H3 HAT complex, NuA3 (Nucleosomal Acetyltransferase of histone H3). Peptide sequencing of proteins from the purified NuA3 complex identified Sas3 as the catalytic HAT subunit of the complex. Sas3 is the yeast homolog of the human MOZ oncogene. Sas3 is required for both the HAT activity and the integrity of the NuA3 complex. In addition, NuA3 contains the TBP- associated factor, yTAFII30, which is also a component of the TFIID, TFIIF, and SWI/SNF complexes. Sas3 mediates interaction of the NuA3 complex with Spt16 both in vivo and in vitro. Spt16 functions as a component of the yeast CP (Cdc68/Pob3) and mammalian FACT (facilitates chromatin transcription) complexes, which are involved in transcription elongation and DNA replication. This interaction suggests that the NuA3 complex might function in concert with FACT–CP to stimulate transcription or replication elongation through nucleosomes by providing a coupled acetyltransferase activity. PMID:10817755

  6. Conserved Molecular Interactions within the HBO1 Acetyltransferase Complexes Regulate Cell Proliferation

    PubMed Central

    Avvakumov, Nikita; Lalonde, Marie-Eve; Saksouk, Nehmé; Paquet, Eric; Glass, Karen C.; Landry, Anne-Julie; Doyon, Yannick; Cayrou, Christelle; Robitaille, Geneviève A.; Richard, Darren E.; Yang, Xiang-Jiao; Kutateladze, Tatiana G.

    2012-01-01

    Acetyltransferase complexes of the MYST family with distinct substrate specificities and functions maintain a conserved association with different ING tumor suppressor proteins. ING complexes containing the HBO1 acetylase are a major source of histone H3 and H4 acetylation in vivo and play critical roles in gene regulation and DNA replication. Here, our molecular dissection of HBO1/ING complexes unravels the protein domains required for their assembly and function. Multiple PHD finger domains present in different subunits bind the histone H3 N-terminal tail with a distinct specificity toward lysine 4 methylation status. We show that natively regulated association of the ING4/5 PHD domain with HBO1-JADE determines the growth inhibitory function of the complex, linked to its tumor suppressor activity. Functional genomic analyses indicate that the p53 pathway is a main target of the complex, at least in part through direct transcription regulation at the initiation site of p21/CDKN1A. These results demonstrate the importance of ING association with MYST acetyltransferases in controlling cell proliferation, a regulated link that accounts for the reported tumor suppressor activities of these complexes. PMID:22144582

  7. Structure and Biochemical Characterization of Protein Acetyltransferase from Sulfolobus solfataricus

    SciTech Connect

    Brent, Michael M.; Iwata, Ayaka; Carten, Juliana; Zhao, Kehao; Marmorstein, Ronen

    2009-09-02

    The Sulfolobus solfataricus protein acetyltransferase (PAT) acetylates ALBA, an abundant nonspecific DNA-binding protein, on Lys{sup 16} to reduce its DNA affinity, and the Sir2 deacetylase reverses the modification to cause transcriptional repression. This represents a 'primitive' model for chromatin regulation analogous to histone modification in eukaryotes. We report the 1.84-{angstrom} crystal structure of PAT in complex with coenzyme A. The structure reveals homology to both prokaryotic GNAT acetyltransferases and eukaryotic histone acetyltransferases (HATs), with an additional 'bent helix' proximal to the substrate binding site that might play an autoregulatory function. Investigation of active site mutants suggests that PAT does not use a single general base or acid residue for substrate deprotonation and product reprotonation, respectively, and that a diffusional step, such as substrate binding, may be rate-limiting. The catalytic efficiency of PAT toward ALBA is low relative to other acetyltransferases, suggesting that there may be better, unidentified substrates for PAT. The structural similarity of PAT to eukaryotic HATs combined with its conserved role in chromatin regulation suggests that PAT is evolutionarily related to the eukaryotic HATs.

  8. Effects of humic acid-metal complexes on hepatic carnitine palmitoyltransferase, carnitine acetyltransferase and catalase activities

    SciTech Connect

    Fungjou Lu; Youngshin Chen . Dept. of Biochemistry); Tienshang Huang . Dept. of Medicine)

    1994-03-01

    A significant increase in activities of hepatic carnitine palmitoyltransferase and carnitine acetyltransferase was observed in male Balb/c mice intraperitoneally injected for 40 d with 0.125 mg/0.1 ml/d humic acid-metal complexes. Among these complexes, the humic acid-As complex was relatively effective, whereas humic acid-25 metal complex was more effective, and humic acid-26 metal complex was most effective. However, humic acid or metal mixtures, or metal such as As alone, was not effective. Humic acid-metal complexes also significantly decreased hepatic catalase activity. A marked decrease of 60-kDa polypeptide in liver cytoplasm was also observed on SDS-polyacrylamide gel electrophoresis after the mice had been injected with the complexes. Morphological analysis of a histopathological biopsy of such treated mice revealed several changes in hepatocytes, including focal necrosis and cell infiltration, mild fatty changes, reactive nuclei, and hypertrophy. Humic acid-metal complexes affect activities of metabolic enzymes of fatty acids, and this results in accumulation of hydrogen peroxide and increase of the lipid peroxidation. The products of lipid peroxidation may be responsible for liver damage and possible carcinogenesis. Previous studies in this laboratory had shown that humic acid-metal complex altered the coagulation system and that humic acid, per se, caused vasculopathy. Therefore, humic acid-metal complexes may be main causal factors of not only so-called blackfoot disease, but also the liver cancer prevailing on the southwestern coast of Taiwan.

  9. Acetylation of retinal histones in diabetes increases inflammatory proteins: effects of minocycline and manipulation of histone acetyltransferase (HAT) and histone deacetylase (HDAC).

    PubMed

    Kadiyala, Chandra Sekhar Rao; Zheng, Ling; Du, Yunpeng; Yohannes, Elizabeth; Kao, Hung-Ying; Miyagi, Masaru; Kern, Timothy S

    2012-07-27

    Histone acetylation was significantly increased in retinas from diabetic rats, and this acetylation was inhibited in diabetics treated with minocycline, a drug known to inhibit early diabetic retinopathy in animals. Histone acetylation and expression of inflammatory proteins that have been implicated in the pathogenesis of diabetic retinopathy were increased likewise in cultured retinal Müller glia grown in a diabetes-like concentration of glucose. Both the acetylation and induction of the inflammatory proteins in elevated glucose levels were significantly inhibited by inhibitors of histone acetyltransferase (garcinol and antisense against the histone acetylase, p300) or activators of histone deacetylase (theophylline and resveratrol) and were increased by the histone deacetylase inhibitor, suberolylanilide hydroxamic acid. We conclude that hyperglycemia causes acetylation of retinal histones (and probably other proteins) and that the acetylation contributes to the hyperglycemia-induced up-regulation of proinflammatory proteins and thereby to the development of diabetic retinopathy.

  10. The Spt-Ada-Gcn5 Acetyltransferase (SAGA) complex in Aspergillus nidulans.

    PubMed

    Georgakopoulos, Paraskevi; Lockington, Robin A; Kelly, Joan M

    2013-01-01

    A mutation screen in Aspergillus nidulans uncovered mutations in the acdX gene that led to altered repression by acetate, but not by glucose. AcdX of A. nidulans is highly conserved with Spt8p of Saccharomyces cerevisiae, and since Spt8p is a component of the Spt-Ada-Gcn5 Acetyltransferase (SAGA) complex, the SAGA complex may have a role in acetate repression in A. nidulans. We used a bioinformatic approach to identify genes encoding most members of the SAGA complex in A. nidulans, and a proteomic analysis to confirm that most protein components identified indeed exist as a complex in A. nidulans. No apparent compositional differences were detected in mycelia cultured in acetate compared to glucose medium. The methods used revealed apparent differences between Yeast and A. nidulans in the deubiquitination (DUB) module of the complex, which in S. cerevisiae consists of Sgf11p, Sus1p, and Ubp8p. Although a convincing homologue of S. cerevisiae Ubp8p was identified in the A. nidulans genome, there were no apparent homologues for Sus1p and Sgf11p. In addition, when the SAGA complex was purified from A. nidulans, members of the DUB module were not co-purified with the complex, indicating that functional homologues of Sus1p and Sgf11p were not part of the complex. Thus, deubiquitination of H2B-Ub in stress conditions is likely to be regulated differently in A. nidulans compared to S. cerevisiae.

  11. The MOZ Histone Acetyltransferase in Epigenetic Signaling and Disease

    PubMed Central

    Carlson, Samuel; Glass, Karen C.

    2016-01-01

    The monocytic leukemic zinc finger (MOZ) histone acetyltransferase (HAT) plays a role in acute myeloid leukemia (AML). It functions as a quaternary complex with the bromodomain PHD finger protein 1 (BRPF1), the human Esa1-associated factor 6 homolog (hEAF6), and the inhibitor of growth 5 (ING5). Each of these subunits contain chromatin reader domains that recognize specific post-translational modifications (PTMs) on histone tails, and this recognition directs the MOZ HAT complex to specific chromatin substrates. The structure and function of these epigenetic reader modules has now been elucidated, and a model describing how the cooperative activity of these domains regulates HAT activity in response to the epigenetic landscape is proposed. The emerging role of epigenetic reader domains in disease, and their therapeutic potential for many types of cancer is also highlighted. PMID:24633655

  12. The SAGA histone acetyltransferase complex regulates leucine uptake through the Agp3 permease in fission yeast.

    PubMed

    Takahashi, Hidekazu; Sun, Xiaoying; Hamamoto, Makiko; Yashiroda, Yoko; Yoshida, Minoru

    2012-11-01

    Metabolic responses of unicellular organisms are mostly acute, transient, and cell-autonomous. Regulation of nutrient uptake in yeast is one such rapid response. High quality nitrogen sources such as NH(4)(+) inhibit uptake of poor nitrogen sources, such as amino acids. Both transcriptional and posttranscriptional mechanisms operate in nutrient uptake regulation; however, many components of this system remain uncharacterized in the fission yeast, Schizosaccharomyces pombe. Here, we demonstrate that the Spt-Ada-Gcn acetyltransferase (SAGA) complex modulates leucine uptake. Initially, we noticed that a branched-chain amino acid auxotroph exhibits a peculiar adaptive growth phenotype on solid minimal media containing certain nitrogen sources. In fact, the growth of many auxotrophic strains is inhibited by excess NH(4)Cl, possibly through nitrogen-mediated uptake inhibition of the corresponding nutrients. Surprisingly, DNA microarray analysis revealed that the transcriptional reprogramming during the adaptation of the branched-chain amino acid auxotroph was highly correlated with reprogramming observed in deletions of the SAGA histone acetyltransferase module genes. Deletion of gcn5(+) increased leucine uptake in the prototrophic background and rendered the leucine auxotroph resistant to NH(4)Cl. Deletion of tra1(+) caused the opposite phenotypes. The increase in leucine uptake in the gcn5Δ mutant was dependent on an amino acid permease gene, SPCC965.11c(+). The closest budding yeast homolog of this permease is a relatively nonspecific amino acid permease AGP3, which functions in poor nutrient conditions. Our analysis identified the regulation of nutrient uptake as a physiological function for the SAGA complex, providing a potential link between cellular metabolism and chromatin regulation.

  13. Crystal Structures of Murine Carnitine Acetyltransferase in Ternary Complexes with Its Substrates

    SciTech Connect

    Hsiao,Y.; Jogl, G.; Tong, L.

    2006-01-01

    Carnitine acyltransferases catalyze the reversible exchange of acyl groups between coenzyme A (CoA) and carnitine. They have important roles in many cellular processes, especially the oxidation of long-chain fatty acids in the mitochondria for energy production, and are attractive targets for drug discovery against diabetes and obesity. To help define in molecular detail the catalytic mechanism of these enzymes, we report here the high resolution crystal structure of wild-type murine carnitine acetyltransferase (CrAT) in a ternary complex with its substrates acetyl-CoA and carnitine, and the structure of the S554A/M564G double mutant in a ternary complex with the substrates CoA and hexanoylcarnitine. Detailed analyses suggest that these structures may be good mimics for the Michaelis complexes for the forward and reverse reactions of the enzyme, representing the first time that such complexes of CrAT have been studied in molecular detail. The structural information provides significant new insights into the catalytic mechanism of CrAT and possibly carnitine acyltransferases in general.

  14. The NatA Acetyltransferase Couples Sup35 Prion Complexes to the [PSI+] Phenotype

    PubMed Central

    Pezza, John A.; Langseth, Sara X.; Raupp Yamamoto, Rochele; Doris, Stephen M.; Ulin, Samuel P.; Salomon, Arthur R.

    2009-01-01

    Protein-only (prion) epigenetic elements confer unique phenotypes by adopting alternate conformations that specify new traits. Given the conformational flexibility of prion proteins, protein-only inheritance requires efficient self-replication of the underlying conformation. To explore the cellular regulation of conformational self-replication and its phenotypic effects, we analyzed genetic interactions between [PSI+], a prion form of the S. cerevisiae Sup35 protein (Sup35[PSI+]), and the three Nα-acetyltransferases, NatA, NatB, and NatC, which collectively modify ∼50% of yeast proteins. Although prion propagation proceeds normally in the absence of NatB or NatC, the [PSI+] phenotype is reversed in strains lacking NatA. Despite this change in phenotype, [PSI+] NatA mutants continue to propagate heritable Sup35[PSI+]. This uncoupling of protein state and phenotype does not arise through a decrease in the number or activity of prion templates (propagons) or through an increase in soluble Sup35. Rather, NatA null strains are specifically impaired in establishing the translation termination defect that normally accompanies Sup35 incorporation into prion complexes. The NatA effect cannot be explained by the modification of known components of the [PSI+] prion cycle including Sup35; thus, novel acetylated cellular factors must act to establish and maintain the tight link between Sup35[PSI+] complexes and their phenotypic effects. PMID:19073888

  15. Exchange of associated factors directs a switch in HBO1 acetyltransferase histone tail specificity

    PubMed Central

    Lalonde, Marie-Eve; Avvakumov, Nikita; Glass, Karen C.; Joncas, France-Hélène; Saksouk, Nehmé; Holliday, Michael; Paquet, Eric; Yan, Kezhi; Tong, Qiong; Klein, Brianna J.; Tan, Song; Yang, Xiang-Jiao; Kutateladze, Tatiana G.; Côté, Jacques

    2013-01-01

    Histone acetyltransferases (HATs) assemble into multisubunit complexes in order to target distinct lysine residues on nucleosomal histones. Here, we characterize native HAT complexes assembled by the BRPF family of scaffold proteins. Their plant homeodomain (PHD)–Zn knuckle–PHD domain is essential for binding chromatin and is restricted to unmethylated H3K4, a specificity that is reversed by the associated ING subunit. Native BRPF1 complexes can contain either MOZ/MORF or HBO1 as catalytic acetyltransferase subunit. Interestingly, while the previously reported HBO1 complexes containing JADE scaffold proteins target histone H4, the HBO1–BRPF1 complex acetylates only H3 in chromatin. We mapped a small region to the N terminus of scaffold proteins responsible for histone tail selection on chromatin. Thus, alternate choice of subunits associated with HBO1 can switch its specificity between H4 and H3 tails. These results uncover a crucial new role for associated proteins within HAT complexes, previously thought to be intrinsic to the catalytic subunit. PMID:24065767

  16. Exchange of associated factors directs a switch in HBO1 acetyltransferase histone tail specificity.

    PubMed

    Lalonde, Marie-Eve; Avvakumov, Nikita; Glass, Karen C; Joncas, France-Hélène; Saksouk, Nehmé; Holliday, Michael; Paquet, Eric; Yan, Kezhi; Tong, Qiong; Klein, Brianna J; Tan, Song; Yang, Xiang-Jiao; Kutateladze, Tatiana G; Côté, Jacques

    2013-09-15

    Histone acetyltransferases (HATs) assemble into multisubunit complexes in order to target distinct lysine residues on nucleosomal histones. Here, we characterize native HAT complexes assembled by the BRPF family of scaffold proteins. Their plant homeodomain (PHD)-Zn knuckle-PHD domain is essential for binding chromatin and is restricted to unmethylated H3K4, a specificity that is reversed by the associated ING subunit. Native BRPF1 complexes can contain either MOZ/MORF or HBO1 as catalytic acetyltransferase subunit. Interestingly, while the previously reported HBO1 complexes containing JADE scaffold proteins target histone H4, the HBO1-BRPF1 complex acetylates only H3 in chromatin. We mapped a small region to the N terminus of scaffold proteins responsible for histone tail selection on chromatin. Thus, alternate choice of subunits associated with HBO1 can switch its specificity between H4 and H3 tails. These results uncover a crucial new role for associated proteins within HAT complexes, previously thought to be intrinsic to the catalytic subunit.

  17. Histone acetyltransferases and histone deacetylases in B- and T-cell development, physiology and malignancy

    PubMed Central

    Haery, Leila; Thompson, Ryan C.; Gilmore, Thomas D.

    2015-01-01

    The development of B and T cells from hematopoietic precursors and the regulation of the functions of these immune cells are complex processes that involve highly regulated signaling pathways and transcriptional control. The signaling pathways and gene expression patterns that give rise to these developmental processes are coordinated, in part, by two opposing classes of broad-based enzymatic regulators: histone acetyltransferases (HATs) and histone deacetylases (HDACs). HATs and HDACs can modulate gene transcription by altering histone acetylation to modify chromatin structure, and by regulating the activity of non-histone substrates, including an array of immune-cell transcription factors. In addition to their role in normal B and T cells, dysregulation of HAT and HDAC activity is associated with a variety of B- and T-cell malignancies. In this review, we describe the roles of HATs and HDACs in normal B- and T-cell physiology, describe mutations and dysregulation of HATs and HDACs that are implicated lymphoma and leukemia, and discuss HAT and HDAC inhibitors that have been explored as treatment options for leukemias and lymphomas. PMID:26124919

  18. The ATM-related domain of TRRAP is required for histone acetyltransferase recruitment and Myc-dependent oncogenesis

    PubMed Central

    Park, Jeonghyeon; Kunjibettu, Sudeesha; McMahon, Steven B.; Cole, Michael D.

    2001-01-01

    The ATM-related TRRAP protein is a component of several different histone acetyltransferase (HAT) complexes but lacks the kinase activity characteristic of other ATM family members. We identified a novel function for this evolutionarily conserved domain in its requirement for the assembly of a functional HAT complex. Ectopic expression of TRRAP protein with a mutation in the ATM-related domain inhibits Myc-mediated oncogenic transformation. The Myc-binding region of TRRAP maps to a separable domain, and ectopic expression of this domain inhibits cell growth. These findings demonstrate that the ATM-related domain of TRRAP forms a structural core for the assembly and recruitment of HAT complexes by transcriptional activators. PMID:11445536

  19. The histone acetyltransferase domains of CREB-binding protein (CBP) and p300/CBP-associated factor are not necessary for cooperativity with the class II transactivator.

    PubMed

    Harton, J A; Zika, E; Ting, J P

    2001-10-19

    The class II transactivator (CIITA) is a transcriptional co-activator regulating the constitutive and interferon-gamma-inducible expression of class II major histocompatibility complex (MHC) and related genes. Promoter remodeling occurs following CIITA induction, suggesting the involvement of chromatin remodeling factors. Transcription of numerous genes requires the histone acetyltransferase (HAT) activities of CREB-binding protein (CBP), p300, and/or p300/CBP-associated factor (pCAF). These co-activators cooperate with CIITA and are hypothesized to promote class II major histocompatibility complex transcription through their HAT activity. To directly test this, we used HAT-defective CBP and pCAF. We demonstrate that cooperation between CIITA and CBP is independent of CBP HAT activity. Further, although pCAF enhances CIITA-mediated transcription, pCAF HAT domain dependence appears contingent upon the concentration of available CIITA. When HAT-defective CBP and pCAF are both present, cooperativity with CIITA is maintained. Consistent with a recent report, we show that nuclear localization of CIITA is enhanced by lysine 144, an in vitro target of pCAF-mediated HAT. Yet we find that neither mutation of lysine 144 nor deletion of residues 132-209 affects transcriptional cooperation with CBP or pCAF. Thus, acetylation of this residue may not be the primary mechanism for pCAF/CBP cooperation with CIITA. In conclusion, the HAT activities of the co-activators are not necessary for cooperation with CIITA.

  20. Spt-Ada-Gcn5-Acetyltransferase (SAGA) Complex in Plants: Genome Wide Identification, Evolutionary Conservation and Functional Determination.

    PubMed

    Srivastava, Rakesh; Rai, Krishan Mohan; Pandey, Bindu; Singh, Sudhir P; Sawant, Samir V

    2015-01-01

    The recruitment of RNA polymerase II on a promoter is assisted by the assembly of basal transcriptional machinery in eukaryotes. The Spt-Ada-Gcn5-Acetyltransferase (SAGA) complex plays an important role in transcription regulation in eukaryotes. However, even in the advent of genome sequencing of various plants, SAGA complex has been poorly defined for their components and roles in plant development and physiological functions. Computational analysis of Arabidopsis thaliana and Oryza sativa genomes for SAGA complex resulted in the identification of 17 to 18 potential candidates for SAGA subunits. We have further classified the SAGA complex based on the conserved domains. Phylogenetic analysis revealed that the SAGA complex proteins are evolutionary conserved between plants, yeast and mammals. Functional annotation showed that they participate not only in chromatin remodeling and gene regulation, but also in different biological processes, which could be indirect and possibly mediated via the regulation of gene expression. The in silico expression analysis of the SAGA components in Arabidopsis and O. sativa clearly indicates that its components have a distinct expression profile at different developmental stages. The co-expression analysis of the SAGA components suggests that many of these subunits co-express at different developmental stages, during hormonal interaction and in response to stress conditions. Quantitative real-time PCR analysis of SAGA component genes further confirmed their expression in different plant tissues and stresses. The expression of representative salt, heat and light inducible genes were affected in mutant lines of SAGA subunits in Arabidopsis. Altogether, the present study reveals expedient evidences of involvement of the SAGA complex in plant gene regulation and stress responses.

  1. Hats Off.

    ERIC Educational Resources Information Center

    Department of the Navy, Washington, DC.

    The materials in this lesson plan introduces students to the U.S. Navy by exploring the hats officers and enlisted personnel wear to work. The lesson is appropriate for students in grades 1-3 and was designed in accordance with local and national social studies standards. The lesson plan cites educational objectives and lists materials provided.…

  2. Helper Hats

    ERIC Educational Resources Information Center

    Ashbrook, Peggy

    2010-01-01

    Special clothing is worn by "community helpers" such as police officers, nurses, firefighters, cafeteria workers, dentists, and waste management workers as they do their jobs. The special clothing allows workers to be safe. Therefore, exploring how hats help community workers do their jobs can be a way to introduce the idea of how the shape or…

  3. LHX3 Interacts with Inhibitor of Histone Acetyltransferase Complex Subunits LANP and TAF-1β to Modulate Pituitary Gene Regulation

    PubMed Central

    Witzmann, Frank A.; Rhodes, Simon J.

    2013-01-01

    LIM-homeodomain 3 (LHX3) is a transcription factor required for mammalian pituitary gland and nervous system development. Human patients and animal models with LHX3 gene mutations present with severe pediatric syndromes that feature hormone deficiencies and symptoms associated with nervous system dysfunction. The carboxyl terminus of the LHX3 protein is required for pituitary gene regulation, but the mechanism by which this domain operates is unknown. In order to better understand LHX3-dependent pituitary hormone gene transcription, we used biochemical and mass spectrometry approaches to identify and characterize proteins that interact with the LHX3 carboxyl terminus. This approach identified the LANP/pp32 and TAF-1β/SET proteins, which are components of the inhibitor of histone acetyltransferase (INHAT) multi-subunit complex that serves as a multifunctional repressor to inhibit histone acetylation and modulate chromatin structure. The protein domains of LANP and TAF-1β that interact with LHX3 were mapped using biochemical techniques. Chromatin immunoprecipitation experiments demonstrated that LANP and TAF-1β are associated with LHX3 target genes in pituitary cells, and experimental alterations of LANP and TAF-1β levels affected LHX3-mediated pituitary gene regulation. Together, these data suggest that transcriptional regulation of pituitary genes by LHX3 involves regulated interactions with the INHAT complex. PMID:23861948

  4. Program Transformation in HATS

    SciTech Connect

    Winter, V.L.

    1999-02-24

    HATS is a general purpose syntax derivation tree based transformation system in which transformation sequences are described in special purpose language. A powerful feature of this language is that unification is an explicit operation. By making unification explicit, an elegant framework arises in which to express complex application conditions which in turn enables refined control strategies to be realized. This paper gives an overview of HATS, focusing especially on the framework provided by the transformation language and its potential with respect to control and general purpose transformation.

  5. Phosphorylation of Tip60 Tyrosine 327 by Abl Kinase Inhibits HAT Activity through Association with FE65

    PubMed Central

    Shin, Sung Hwa; Kang, Sang Sun

    2013-01-01

    The transfer of acetyl groups from acetyl coenzyme A to the ε amino group of internal lysine residues is catalyzed by Tip60, which is in the MYST family of nuclear histone acetyltransferases (HATs). The tyrosine phosphorylation of Tip60 seems to be a unique modification. We present evidence that Tip60 is modified on tyrosine 327 by Abl kinase. We show that this causes functional changes in HAT activity and the subcellular localization of TIP60, which forms a complex with Abl kinase. The Tip60 mutation Y327F abolished tyrosine phosphorylation, reduced the inhibition of Tip60 HAT activity, and caused G0-G1 arrest and association with FE65. Thus, our findings for the first time suggested a novel regulation mechanism of Tip60. Regulation was through phosphorylation of tyrosine 327 by Abl tyrosine kinase and depended on environmental conditions, suggesting that the tyrosine residue of Tip60 is important for the activation process. PMID:24044023

  6. Molecular basis for histone acetyltransferase regulation by binding partners, associated domains, and autoacetylation

    PubMed Central

    McCullough, Cheryl E.; Marmorstein, Ronen

    2016-01-01

    Acetylation is a post-translational modification (PTM) that regulates chromatin dynamics and function. Dysregulation of acetylation or acetyltransferase activity has been correlated with several human diseases. Many, if not all histone acetyltransferases (HATs) are regulated in part through tethered domains, association with binding partners or post-translational modification, including predominantly acetylation. This review focuses on what is currently understood at the molecular level of HAT regulation as it occurs via binding partners, associated domains, and autoacetylation. PMID:26555232

  7. The HAT-P-7 and HAT-P-11 Star-Planet Systems

    NASA Astrophysics Data System (ADS)

    Medina, Jennifer; Manrique, Maria; van Hamme, Walter

    2016-03-01

    Radial velocities and KEPLER light curves of the transiting exoplanets HAT-P-7b and HAT-P-11b are analyzed using a general binary star model. The HAT-P-7 system has been a subject of interest due to the irregular orbit of the HAT-P-7b exoplanet with respect to its parent star. HAT-P-7b's orbit has shed light on the diversity of systems that exist in our observable Universe. HAT-P-11 hosts a K type variable star which we were able to analyze with a fourier fit on the light curve data. It is also a host to exoplanet HAT-P-11b which has a slightly inclined orbit. Using our own software, we have calculated the parameters for star-planet pair of HAT-P-7 and HAT-P-11. This presents another way for astronomers to study these complex systems.

  8. Fungal Rtt109 Histone Acetyltransferase is an Unexpected Structural Homolog of Metazoan p300/CBP

    SciTech Connect

    Tang,Y.; Holbert, M.; Wurtele, H.; Meeth, K.; Rocha, W.; Gharib, M.; Jiang, E.; Thibault, P.; Verreault, A.; et al

    2008-01-01

    Rtt109, also known as KAT11, is a recently characterized fungal-specific histone acetyltransferase (HAT) that modifies histone H3 lysine 56 (H3K56) to promote genome stability. Rtt109 does not show sequence conservation with other known HATs and depends on association with either of two histone chaperones, Asf1 or Vps75, for HAT activity. Here we report the X-ray crystal structure of an Rtt109-acetyl coenzyme A complex and carry out structure-based mutagenesis, combined with in vitro biochemical studies of the Rtt109-Vps75 complex and studies of Rtt109 function in vivo. The Rtt109 structure reveals noteworthy homology to the metazoan p300/CBP HAT domain but exhibits functional divergence, including atypical catalytic properties and mode of cofactor regulation. The structure reveals a buried autoacetylated lysine residue that we show is also acetylated in the Rtt109 protein purified from yeast cells. Implications for understanding histone substrate and chaperone binding by Rtt109 are discussed.

  9. Crosstalk between epigenetic readers regulates the MOZ/MORF HAT complexes

    PubMed Central

    Klein, Brianna J; Lalonde, Marie-Eve; Côté, Jacques; Yang, Xiang-Jiao; Kutateladze, Tatiana G

    2014-01-01

    The MOZ/MORF complexes represent an example of a chromatin-binding assembly whose recruitment to specific genomic regions and activity can be fine-tuned by posttranslational modifications of histones. Here we detail the structures and biological functions of epigenetic readers present in the four core subunits of the MOZ/MORF complexes, highlight the imperative role of combinatorial readout by the multiple readers, and discuss new research directions to advance our understanding of histone acetylation. PMID:24169304

  10. The Saccharomyces cerevisiae Piccolo NuA4 histone acetyltransferase complex requires the Enhancer of Polycomb A domain and chromodomain to acetylate nucleosomes.

    PubMed

    Selleck, William; Fortin, Israël; Sermwittayawong, Decha; Côté, Jacques; Tan, Song

    2005-07-01

    Chromatin modification complexes are key gene regulatory factors which posttranslationally modify the histone component of chromatin with epigenetic marks. To address what features of chromatin modification complexes are responsible for the specific recognition of nucleosomes compared to naked histones, we have performed a functional dissection of the Esa1-containing Saccharomyces cerevisiae Piccolo NuA4 histone acetyltransferase complex. Our studies define the Piccolo determinants sufficient to assemble its three subunits into a complex as well as Piccolo determinants sufficient to specifically acetylate a chromatin template. We find that the conserved Enhancer of Polycomb A (EPcA) homology region of the Epl1 component and the N-terminal 165 amino acids of the Yng2 component of Piccolo are sufficient with Esa1 to specifically act on nucleosomes. We also find that the Esa1 chromodomain plays a critical role in Piccolo's ability to distinguish between histones and nucleosomes. In particular, specific point mutations in the chromodomain putative hydrophobic cage which strongly hinder growth in yeast greatly reduce histone acetyltransferase activity on nucleosome substrates, independent of histone methylation or other modifications. However, the chromodomain is not required for Piccolo to bind to nucleosomes, suggesting a role for the chromodomain in a catalysis step after nucleosome binding.

  11. The Saccharomyces cerevisiae Piccolo NuA4 Histone Acetyltransferase Complex Requires the Enhancer of Polycomb A Domain and Chromodomain To Acetylate Nucleosomes

    PubMed Central

    Selleck, William; Fortin, Israël; Sermwittayawong, Decha; Côté, Jacques; Tan, Song

    2005-01-01

    Chromatin modification complexes are key gene regulatory factors which posttranslationally modify the histone component of chromatin with epigenetic marks. To address what features of chromatin modification complexes are responsible for the specific recognition of nucleosomes compared to naked histones, we have performed a functional dissection of the Esa1-containing Saccharomyces cerevisiae Piccolo NuA4 histone acetyltransferase complex. Our studies define the Piccolo determinants sufficient to assemble its three subunits into a complex as well as Piccolo determinants sufficient to specifically acetylate a chromatin template. We find that the conserved Enhancer of Polycomb A (EPcA) homology region of the Epl1 component and the N-terminal 165 amino acids of the Yng2 component of Piccolo are sufficient with Esa1 to specifically act on nucleosomes. We also find that the Esa1 chromodomain plays a critical role in Piccolo's ability to distinguish between histones and nucleosomes. In particular, specific point mutations in the chromodomain putative hydrophobic cage which strongly hinder growth in yeast greatly reduce histone acetyltransferase activity on nucleosome substrates, independent of histone methylation or other modifications. However, the chromodomain is not required for Piccolo to bind to nucleosomes, suggesting a role for the chromodomain in a catalysis step after nucleosome binding. PMID:15964809

  12. Function and subcellular localization of Gcn5, a histone acetyltransferase in Candida albicans.

    PubMed

    Chang, Peng; Fan, Xueyi; Chen, Jiangye

    2015-08-01

    Candida albicans is an opportunistic fungal pathogen commonly found in humans. It has the ability to switch reversibly between three growth forms: budding yeast, pseudohypha, and hypha. The transition between yeast and hyphal growth forms is critical for the pathogenesis of C. albicans. During the yeast-to-hypha morphologic transition, gene expression is regulated by transcriptional regulators including histone modifying complexes and chromatin remodeling complexes. We previously reported that Esa1, a catalytic subunit in the histone acetyltransferase complex NuA4, is essential for the hyphal development of C. albicans. In this study, we analyzed the functional roles of Gcn5, a catalytic subunit in the histone acetyltransferase complex SAGA, in C. albicans. Gcn5 is required for the invasive and filamentous growth of C. albicans. Deletion of GCN5 impaired hyphal elongation in sensing serum and attenuated the virulence of C. albicans in a mouse systemic infection model. The C. albicans gcn5/gcn5 mutant cells also exhibited sensitivity to cell wall stress. Functional analysis showed that the HAT domain and Bromodomain in Gcn5 play distinct roles in morphogenesis and cell wall stress response of C. albicans. Our results show that the conserved residue Glu188 is crucial for the Gcn5 HAT activity and for Gcn5 function during filamentous growth. In addition, the subcellular distribution of ectopically expressed GFP-Gcn5 correlates with the different growth states of C. albicans. In stationary phase, Gcn5 accumulated in the nucleus, while during vegetative growth it localized in the cytoplasm in a morpha-independent manner. Our results suggest that the nuclear localization of Gcn5 depends on the existence of its N-terminal NLS and HAT domains.

  13. Functional Dissection of the NuA4 Histone Acetyltransferase Reveals Its Role as a Genetic Hub and that Eaf1 Is Essential for Complex Integrity▿

    PubMed Central

    Mitchell, Leslie; Lambert, Jean-Philippe; Gerdes, Maria; Al-Madhoun, Ashraf S.; Skerjanc, Ilona S.; Figeys, Daniel; Baetz, Kristin

    2008-01-01

    The Saccharomyces cerevisiae NuA4 histone acetyltransferase complex catalyzes the acetylation of histone H4 and the histone variant Htz1 to regulate key cellular events, including transcription, DNA repair, and faithful chromosome segregation. To further investigate the cellular processes impacted by NuA4, we exploited the nonessential subunits of the complex to build an extensive NuA4 genetic-interaction network map. The map reveals that NuA4 is a genetic hub whose function buffers a diverse range of cellular processes, many not previously linked to the complex, including Golgi complex-to-vacuole vesicle-mediated transport. Further, we probe the role that nonessential subunits play in NuA4 complex integrity. We find that most nonessential subunits have little impact on NuA4 complex integrity and display between 12 and 42 genetic interactions. In contrast, the deletion of EAF1 causes the collapse of the NuA4 complex and displays 148 genetic interactions. Our study indicates that Eaf1 plays a crucial function in NuA4 complex integrity. Further, we determine that Eaf5 and Eaf7 form a subcomplex, which reflects their similar genetic interaction profiles and phenotypes. Our integrative study demonstrates that genetic interaction maps are valuable in dissecting complex structure and provides insight into why the human NuA4 complex, Tip60, has been associated with a diverse range of pathologies. PMID:18212056

  14. The dietary compound curcumin inhibits p300 histone acetyltransferase activity and prevents heart failure in rats

    PubMed Central

    Morimoto, Tatsuya; Sunagawa, Yoichi; Kawamura, Teruhisa; Takaya, Tomohide; Wada, Hiromichi; Nagasawa, Atsushi; Komeda, Masashi; Fujita, Masatoshi; Shimatsu, Akira; Kita, Toru; Hasegawa, Koji

    2008-01-01

    Hemodynamic overload in the heart can trigger maladaptive hypertrophy of cardiomyocytes. A key signaling event in this process is nuclear acetylation by histone deacetylases and p300, an intrinsic histone acetyltransferase (HAT). It has been previously shown that curcumin, a polyphenol responsible for the yellow color of the spice turmeric, possesses HAT inhibitory activity with specificity for the p300/CREB-binding protein. We found that curcumin inhibited the hypertrophy-induced acetylation and DNA-binding abilities of GATA4, a hypertrophy-responsive transcription factor, in rat cardiomyocytes. Curcumin also disrupted the p300/GATA4 complex and repressed agonist- and p300-induced hypertrophic responses in these cells. Both the acetylated form of GATA4 and the relative levels of the p300/GATA4 complex markedly increased in rat hypertensive hearts in vivo. The effects of curcumin were examined in vivo in 2 different heart failure models: hypertensive heart disease in salt-sensitive Dahl rats and surgically induced myocardial infarction in rats. In both models, curcumin prevented deterioration of systolic function and heart failure–induced increases in both myocardial wall thickness and diameter. From these results, we conclude that inhibition of p300 HAT activity by the nontoxic dietary compound curcumin may provide a novel therapeutic strategy for heart failure in humans. PMID:18292809

  15. The nucleosome remodeling complex, Snf/Swi, is required for the maintenance of transcription in vivo and is partially redundant with the histone acetyltransferase, Gcn5.

    PubMed Central

    Sudarsanam, P; Cao, Y; Wu, L; Laurent, B C; Winston, F

    1999-01-01

    Snf/Swi, a nucleosome remodeling complex, is important for overcoming nucleosome-mediated repression of transcription in Saccharomyces cerevisiae. We have addressed the mechanism by which Snf/Swi controls transcription in vivo of an Snf/Swi-dependent promoter, that of the SUC2 gene. By single-cell analysis, our results show that Snf/Swi is required for activated levels of SUC2 expression in every cell of a population. In addition, Snf/Swi is required for maintenance of SUC2 transcription, suggesting that continuous chromatin remodeling is necessary to maintain an active transcriptional state. Finally, Snf/Swi and Gcn5, a histone acetyltransferase, have partially redundant roles in the control of SUC2 transcription, suggesting a functional overlap between two different mechanisms believed to overcome repression by nucleosomes, nucleosome remodeling and histone acetylation. PMID:10357821

  16. The Functional Analysis of Histone Acetyltransferase MOF in Tumorigenesis

    PubMed Central

    Su, Jiaming; Wang, Fei; Cai, Yong; Jin, Jingji

    2016-01-01

    Changes in chromatin structure and heritably regulating the gene expression by epigenetic mechanisms, such as histone post-translational modification, are involved in most cellular biological processes. Thus, abnormal regulation of epigenetics is implicated in the occurrence of various diseases, including cancer. Human MOF (males absent on the first) is a member of the MYST (Moz-Ybf2/Sas3-Sas2-Tip60) family of histone acetyltransferases (HATs). As a catalytic subunit, MOF can form at least two distinct multiprotein complexes (MSL and NSL) in human cells. Both complexes can acetylate histone H4 at lysine 16 (H4K16); however, the NSL complex possesses broader substrate specificity and can also acetylate histone H4 at lysines 5 and 8 (H4K5 and H4K8), suggesting the complexity of the intracellular functions of MOF. Silencing of MOF in cells leads to genomic instability, inactivation of gene transcription, defective DNA damage repair and early embryonic lethality. Unbalanced MOF expression and its corresponding acetylation of H4K16 have been found in certain primary cancer tissues, including breast cancer, medulloblastoma, ovarian cancer, renal cell carcinoma, colorectal carcinoma, gastric cancer, as well as non-small cell lung cancer. In this review, we provide a brief overview of MOF and its corresponding histone acetylation, introduce recent research findings that link MOF functions to tumorigenesis and speculate on the potential role that may be relevant to tumorigenic pathways. PMID:26784169

  17. leptin-induced growth stimulation of breast cancer cells involves recruitment of histone acetyltransferases and mediator complex to CYCLIN D1 promoter via activation of Stat3.

    PubMed

    Saxena, Neeraj K; Vertino, Paula M; Anania, Frank A; Sharma, Dipali

    2007-05-01

    Numerous epidemiological studies documented that obesity is a risk factor for breast cancer development in postmenopausal women. Leptin, the key player in the regulation of energy balance and body weight control also acts as a growth factor on certain organs in both normal and disease state. In this study, we analyzed the role of leptin and the molecular mechanism(s) underlying its action in breast cancer cells that express both short and long isoforms of leptin receptor. Leptin increased MCF7 cell population in the S-phase of the cell cycle along with a robust increase in CYCLIN D1 expression. Also, leptin induced Stat3-phosphorylation-dependent proliferation of MCF7 cells as blocking Stat3 phosphorylation with a specific inhibitor, AG490, abolished leptin-induced proliferation. Using deletion constructs of CYCLIN D1 promoter and chromatin immunoprecipitation assay, we show that leptin induced increase in CYCLIN D1 promoter activity is mediated through binding of activated Stat3 at the Stat binding sites and changes in histone acetylation and methylation. We also show specific involvement of coactivator molecules, histone acetyltransferase SRC1, and mediator complex in leptin-mediated regulation of CYCLIN D1 promoter. Importantly, silencing of SRC1 and Med1 abolished the leptin induced increase in CYCLIN D1 expression and MCF7 cell proliferation. Intriguingly, recruitment of both SRC1 and Med1 was dependent on phosphorylated Stat3 as AG490 treatment inhibited leptin-induced recruitment of these coactivators to CYCLIN D1 promoter. Our data suggest that CYCLIN D1 may be a target gene for leptin mediated growth stimulation of breast cancer cells and molecular mechanisms involve activated Stat3-mediated recruitment of distinct coactivator complexes.

  18. Sun protection with hats.

    PubMed

    Diffey, B L; Cheeseman, J

    1992-07-01

    The degree of sun protection provided by various styles of hat at different anatomical sites on the head was measured using model headforms and ultraviolet-sensitive film badges. It was found that hats with a small brim, such as the flat cap favoured by elderly male photosensitive patients, provided negligible protection at all sites apart from the vertex and forehead. Peaked baseball-style caps offer good protection to the nose but are relatively ineffective at other sites on the face. Hats with a wide (greater than 7.5 cm) brim are necessary in order to provide reasonable protection factors (greater than 3) around the nose and cheeks.

  19. Virtual Ligand Screening of the p300/CBP Histone Acetyltransferase: Identification of a Selective Small Molecule Inhibitor

    PubMed Central

    Bowers, Erin M.; Yan, Gai; Mukherjee, Chandrani; Orry, Andrew; Wang, Ling; Holbert, Marc A.; Crump, Nicholas T.; Hazzalin, Catherine A.; Liszczak, Glen; Yuan, Hua; Larocca, Cecilia; Saldanha, S. Adrian; Abagyan, Ruben; Sun, Yan; Meyers, David J.; Marmorstein, Ronen; Mahadevan, Louis C.; Alani, Rhoda M.; Cole, Philip A.

    2010-01-01

    Summary The histone acetyltransferase (HAT) p300/CBP is a transcriptional coactivator implicated in many gene regulatory pathways and protein acetylation events. While p300 inhibitors have been reported, a potent, selective, and readily available active-site directed small molecule inhibitor is not yet known. Here we use a structure-based, in silico screening approach to identify a commercially available pyrazolone-containing small molecule p300 HAT inhibitor, C646. C646 is a competitive p300 inhibitor with a Ki of 400 nM and is selective versus other acetyltransferases. Studies on site-directed p300 HAT mutants and synthetic modifications of C646 confirm the importance of predicted interactions in conferring potency. Inhibition of histone acetylation and cell growth by C646 in cells validate its utility as a pharmacologic probe and suggest that p300/CBP HAT is a worthy anti-cancer target. PMID:20534345

  20. Enzyme kinetics and inhibition of histone acetyltransferase KAT8

    PubMed Central

    Wapenaar, Hannah; van der Wouden, Petra E.; Groves, Matthew R.; Rotili, Dante; Mai, Antonello; Dekker, Frank J.

    2016-01-01

    Lysine acetyltransferase 8 (KAT8) is a histone acetyltransferase (HAT) responsible for acetylating lysine 16 on histone H4 (H4K16) and plays a role in cell cycle progression as well as acetylation of the tumor suppressor protein p53. Further studies on its biological function and drug discovery initiatives will benefit from the development of small molecule inhibitors for this enzyme. As a first step towards this aim we investigated the enzyme kinetics of this bi-substrate enzyme. The kinetic experiments indicate a ping-pong mechanism in which the enzyme binds Ac-CoA first, followed by binding of the histone substrate. This mechanism is supported by affinity measurements of both substrates using isothermal titration calorimetry (ITC). Using this information, the KAT8 inhibition of a focused compound collection around the non-selective HAT inhibitor anacardic acid has been investigated. Kinetic studies with anacardic acid were performed, based on which a model for the catalytic activity of KAT8 and the inhibitory action of AA was proposed. This enabled the calculation of the inhibition constant Ki of anacardic acid derivatives using an adaptation of the Cheng-Prusoff equation. The results described in this study give insight into the catalytic mechanism of KAT8 and present the first well-characterized small-molecule inhibitors for this HAT. PMID:26505788

  1. Eaf1 Links the NuA4 Histone Acetyltransferase Complex to Htz1 Incorporation and Regulation of Purine Biosynthesis

    PubMed Central

    Cheng, Xue; Auger, Andréanne; Altaf, Mohammed; Drouin, Simon; Paquet, Eric; Utley, Rhea T.; Robert, François

    2015-01-01

    Proper modulation of promoter chromatin architecture is crucial for gene regulation in order to precisely and efficiently orchestrate various cellular activities. Previous studies have identified the stimulatory effect of the histone-modifying complex NuA4 on the incorporation of the histone variant H2A.Z (Htz1) at the PHO5 promoter (A. Auger, L. Galarneau, M. Altaf, A. Nourani, Y. Doyon, R. T. Utley, D. Cronier, S. Allard, and J. Côté, Mol Cell Biol 28:2257–2270, 2008, http://dx.doi.org/10.1128/MCB.01755-07). In vitro studies with a reconstituted system also indicated an intriguing cross talk between NuA4 and the H2A.Z-loading complex, SWR-C (M. Altaf, A. Auger, J. Monnet-Saksouk, J. Brodeur, S. Piquet, M. Cramet, N. Bouchard, N. Lacoste, R. T. Utley, L. Gaudreau, J. Côté, J Biol Chem 285:15966–15977, 2010, http://dx.doi.org/10.1074/jbc.M110.117069). In this work, we investigated the role of the NuA4 scaffold subunit Eaf1 in global gene expression and genome-wide incorporation of Htz1. We found that loss of Eaf1 affects Htz1 levels mostly at the promoters that are normally highly enriched in the histone variant. Analysis of eaf1 mutant cells by expression array unveiled a relationship between NuA4 and the gene network implicated in the purine biosynthesis pathway, as EAF1 deletion cripples induction of several ADE genes. NuA4 directly interacts with Bas1 activation domain, a key transcription factor of adenine genes. Chromatin immunoprecipitation (ChIP) experiments demonstrate that nucleosomes on the inactive ADE17 promoter are acetylated already by NuA4 and enriched in Htz1. Upon derepression, these poised nucleosomes respond rapidly to activate ADE gene expression in a mechanism likely reminiscent of the PHO5 promoter, leading to nucleosome disassembly. These detailed molecular events depict a specific case of cross talk between NuA4-dependent acetylation and incorporation of histone variant Htz1, presetting the chromatin structure over ADE promoters for

  2. Structure and function of the catalytic domain of the dihydrolipoyl acetyltransferase component in Escherichia coli pyruvate dehydrogenase complex.

    PubMed

    Wang, Junjie; Nemeria, Natalia S; Chandrasekhar, Krishnamoorthy; Kumaran, Sowmini; Arjunan, Palaniappa; Reynolds, Shelley; Calero, Guillermo; Brukh, Roman; Kakalis, Lazaros; Furey, William; Jordan, Frank

    2014-05-30

    The Escherichia coli pyruvate dehydrogenase complex (PDHc) catalyzing conversion of pyruvate to acetyl-CoA comprises three components: E1p, E2p, and E3. The E2p is the five-domain core component, consisting of three tandem lipoyl domains (LDs), a peripheral subunit binding domain (PSBD), and a catalytic domain (E2pCD). Herein are reported the following. 1) The x-ray structure of E2pCD revealed both intra- and intertrimer interactions, similar to those reported for other E2pCDs. 2) Reconstitution of recombinant LD and E2pCD with E1p and E3p into PDHc could maintain at least 6.4% activity (NADH production), confirming the functional competence of the E2pCD and active center coupling among E1p, LD, E2pCD, and E3 even in the absence of PSBD and of a covalent link between domains within E2p. 3) Direct acetyl transfer between LD and coenzyme A catalyzed by E2pCD was observed with a rate constant of 199 s(-1), comparable with the rate of NADH production in the PDHc reaction. Hence, neither reductive acetylation of E2p nor acetyl transfer within E2p is rate-limiting. 4) An unprecedented finding is that although no interaction could be detected between E1p and E2pCD by itself, a domain-induced interaction was identified on E1p active centers upon assembly with E2p and C-terminally truncated E2p proteins by hydrogen/deuterium exchange mass spectrometry. The inclusion of each additional domain of E2p strengthened the interaction with E1p, and the interaction was strongest with intact E2p. E2p domain-induced changes at the E1p active site were also manifested by the appearance of a circular dichroism band characteristic of the canonical 4'-aminopyrimidine tautomer of bound thiamin diphosphate (AP). PMID:24742683

  3. Crystal structure of tabtoxin resistance protein complexed with acetyl coenzyme A reveals the mechanism for {beta}-lactam acetylation.

    SciTech Connect

    He, H.; Ding, Y.; Bartlam, M.; Sun, F.; Le, Y.; Qin, X.; Tang, H.; Zhang, R.; Joachimiak, A.; Liu, J.; Zhao, N.; Rao, Z.; Biosciences Division; Tsinghua Univ.; Chinese Academy of Science

    2003-01-31

    Tabtoxin resistance protein (TTR) is an enzyme that renders tabtoxin-producing pathogens, such as Pseudomonas syringae, tolerant to their own phytotoxins. Here, we report the crystal structure of TTR complexed with its natural cofactor, acetyl coenzyme A (AcCoA), to 1.55 {angstrom} resolution. The binary complex forms a characteristic 'V' shape for substrate binding and contains the four motifs conserved in the GCN5-related N-acetyltransferase (GNAT) superfamily, which also includes the histone acetyltransferases (HATs). A single-step mechanism is proposed to explain the function of three conserved residues, Glu92, Asp130 and Tyr141, in catalyzing the acetyl group transfer to its substrate. We also report that TTR possesses HAT activity and suggest an evolutionary relationship between TTR and other GNAT members.

  4. Tip60 HAT Action Mediates Environmental Enrichment Induced Cognitive Restoration

    PubMed Central

    Xu, Songjun; Panikker, Priyalakshmi; Iqbal, Sahira; Elefant, Felice

    2016-01-01

    Environmental enrichment (EE) conditions have beneficial effects for reinstating cognitive ability in neuropathological disorders like Alzheimer’s disease (AD). While EE benefits involve epigenetic gene control mechanisms that comprise histone acetylation, the histone acetyltransferases (HATs) involved remain largely unknown. Here, we examine a role for Tip60 HAT action in mediating activity- dependent beneficial neuroadaptations to EE using the Drosophila CNS mushroom body (MB) as a well-characterized cognition model. We show that flies raised under EE conditions display enhanced MB axonal outgrowth, synaptic marker protein production, histone acetylation induction and transcriptional activation of cognition linked genes when compared to their genotypically identical siblings raised under isolated conditions. Further, these beneficial changes are impaired in both Tip60 HAT mutant flies and APP neurodegenerative flies. While EE conditions provide some beneficial neuroadaptive changes in the APP neurodegenerative fly MB, such positive changes are significantly enhanced by increasing MB Tip60 HAT levels. Our results implicate Tip60 as a critical mediator of EE-induced benefits, and provide broad insights into synergistic behavioral and epigenetic based therapeutic approaches for treatment of cognitive disorder. PMID:27454757

  5. Irradiation with heavy-ion particles changes the cellular distribution of human histone acetyltranferase HAT1

    SciTech Connect

    Lebel, E.A.; Tafrov, S.; Boukamp, P.

    2010-06-01

    Hat1 was the first histone acetyltransferase identified, however its biological function is still unclear. In this report, we show that the human Hat1 has two isoforms. Isoform a has 418 amino acids (aa) and is localized exclusively in the nuclear matrix of normal human keratinocytes (NHKs). Isoform b has 334 aa and is located in thecytoplasm, the nucleoplasm, attached to the chromatin and to the nuclear matrix. Immunohistochemical analyses revealed that the bulk of Hat1 is confined to the nucleus, with much lesser amounts in the cytoplasm. Cells undergoing mitotic division have an elevated amount of Hat1 compared to non-mitotic ones. NHKs exposed to hydrogen peroxide (H2O2) or to a beam of high mass and energy (HZE) ion particles expressed bright nuclear staining for Hat1, a phenotype that was not observed in NHKs exposed to &947;-rays. We established that the enhanced nuclear staining for Hat1 in response to these treatments is regulated by the PI3K and the MAPK signaling pathways. Our observations clearly implicate Hat1 in the cellular response assuring the survival of the treated cells.

  6. Aggregation of Polyglutamine-expanded Ataxin 7 Protein Specifically Sequesters Ubiquitin-specific Protease 22 and Deteriorates Its Deubiquitinating Function in the Spt-Ada-Gcn5-Acetyltransferase (SAGA) Complex.

    PubMed

    Yang, Hui; Liu, Shuai; He, Wen-Tian; Zhao, Jian; Jiang, Lei-Lei; Hu, Hong-Yu

    2015-09-01

    Human ataxin 7 (Atx7) is a component of the deubiquitination module (DUBm) in the Spt-Ada-Gcn5-acetyltransferase (SAGA) complex for transcriptional regulation, and expansion of its polyglutamine (polyQ) tract leads to spinocerebellar ataxia type 7. However, how polyQ expansion of Atx7 affects DUBm function remains elusive. We investigated the effects of polyQ-expanded Atx7 on ubiquitin-specific protease (USP22), an interacting partner of Atx7 functioning in deubiquitination of histone H2B. The results showed that the inclusions or aggregates formed by polyQ-expanded Atx7 specifically sequester USP22 through their interactions mediated by the N-terminal zinc finger domain of Atx7. The mutation of the zinc finger domain in Atx7 that disrupts its interaction with USP22 dramatically abolishes sequestration of USP22. Moreover, polyQ expansion of Atx7 decreases the deubiquitinating activity of USP22 and, consequently, increases the level of monoubiquitinated H2B. Therefore, we propose that polyQ-expanded Atx7 forms insoluble aggregates that sequester USP22 into a catalytically inactive state, and then the impaired DUBm loses the function to deubiquitinate monoubiquitinated histone H2B or H2A. This may result in dysfunction of the SAGA complex and transcriptional dysregulation in spinocerebellar ataxia type 7 disease.

  7. Targeting specific HATs for neurodegenerative disease treatment: translating basic biology to therapeutic possibilities

    PubMed Central

    Pirooznia, Sheila K.; Elefant, Felice

    2013-01-01

    Dynamic epigenetic regulation of neurons is emerging as a fundamental mechanism by which neurons adapt their transcriptional responses to specific developmental and environmental cues. While defects within the neural epigenome have traditionally been studied in the context of early developmental and heritable cognitive disorders, recent studies point to aberrant histone acetylation status as a key mechanism underlying acquired inappropriate alterations of genome structure and function in post-mitotic neurons during the aging process. Indeed, it is becoming increasingly evident that chromatin acetylation status can be impaired during the lifetime of neurons through mechanisms related to loss of function of histone acetyltransferase (HAT) activity. Several HATs have been shown to participate in vital neuronal functions such as regulation of neuronal plasticity and memory formation. As such, dysregulation of such HATs has been implicated in the pathogenesis associated with age-associated neurodegenerative diseases and cognitive decline. In order to counteract the loss of HAT function in neurodegenerative diseases, the current therapeutic strategies involve the use of small molecules called histone deacetylase (HDAC) inhibitors that antagonize HDAC activity and thus enhance acetylation levels. Although this strategy has displayed promising therapeutic effects, currently used HDAC inhibitors lack target specificity, raising concerns about their applicability. With rapidly evolving literature on HATs and their respective functions in mediating neuronal survival and higher order brain function such as learning and memory, modulating the function of specific HATs holds new promises as a therapeutic tool in neurodegenerative diseases. In this review, we focus on the recent progress in research regarding epigenetic histone acetylation mechanisms underlying neuronal activity and cognitive function. We discuss the current understanding of specific HDACs and HATs in

  8. Targeting of a histone acetyltransferase domain to a promoter enhances protein expression levels in mammalian cells.

    PubMed

    Kwaks, T H J; Sewalt, R G A B; van Blokland, R; Siersma, T J; Kasiem, M; Kelder, A; Otte, A P

    2005-01-12

    Silencing of transfected genes in mammalian cells is a fundamental problem that probably involves the (in)accessibility status of chromatin. A potential solution to this problem is to provide a cell with protein factors that make the chromatin of a promoter more open or accessible for transcription. We tested this by targeting such proteins to different promoters. We found that targeting the p300 histone acetyltransferase (HAT) domain to strong viral or cellular promoters is sufficient to result in higher expression levels of a reporter protein. In contrast, targeting the chromatin-remodeling factor Brahma does not result in stable, higher protein expression levels. The long-term effects of the targeted p300HAT domain on protein expression levels are positively reinforced, when also anti-repressor elements are applied to flank the reporter construct. These elements were previously shown to be potent blockers of chromatin-associated repressors. The simultaneous application of the targeted p300HAT domain and anti-repressor elements conveys long-term stability to protein expression. Whereas no copy number dependency is achieved by targeting of the p300HAT domain alone, copy number dependency is improved when anti-repressor elements are included. We conclude that targeting of protein domains such as HAT domains helps to facilitate expression of transfected genes in mammalian cells. However, the simultaneous application of other genomic elements such as the anti-repressor elements prevents silencing more efficiently.

  9. Nuclear Rho kinase, ROCK2, targets p300 acetyltransferase.

    PubMed

    Tanaka, Toru; Nishimura, Dai; Wu, Ray-Chang; Amano, Mutsuki; Iso, Tatsuya; Kedes, Larry; Nishida, Hiroshi; Kaibuchi, Kozo; Hamamori, Yasuo

    2006-06-01

    Rho-associated coiled-coil protein kinase (ROCK) is an effector for the small GTPase Rho and plays a pivotal role in diverse cellular activities, including cell adhesion, cytokinesis, and gene expression, primarily through an alteration of actin cytoskeleton dynamics. Here, we show that ROCK2 is localized in the nucleus and associates with p300 acetyltransferase both in vitro and in cells. Nuclear ROCK2 is present in a large protein complex and partially cofractionates with p300 by gel filtration analysis. By immunofluorescence, ROCK2 partially colocalizes with p300 in distinct insoluble nuclear structures. ROCK2 phosphorylates p300 in vitro, and nuclear-restricted expression of constitutively active ROCK2 induces p300 phosphorylation in cells. p300 acetyltransferase activity is dependent on its phosphorylation status in cells, and p300 phosphorylation by ROCK2 results in an increase in its acetyltransferase activity in vitro. These observations suggest that nucleus-localized ROCK2 targets p300 for phosphorylation to regulate its acetyltransferase activity.

  10. Structural basis for the interaction between yeast Spt-Ada-Gcn5 acetyltransferase (SAGA) complex components Sgf11 and Sus1.

    PubMed

    Ellisdon, Andrew M; Jani, Divyang; Köhler, Alwin; Hurt, Ed; Stewart, Murray

    2010-02-01

    Sus1 is a central component of the yeast gene gating machinery, the process by which actively transcribing genes such as GAL1 become associated with nuclear pore complexes. Sus1 is a component of both the SAGA transcriptional co-activator complex and the TREX-2 complex that binds to nuclear pore complexes. TREX-2 contains two Sus1 chains that have an articulated helical hairpin fold, enabling them to wrap around an extended alpha-helix in Sac3, following a helical hydrophobic stripe. In SAGA, Sus1 binds to Sgf11 and has been proposed to provide a link between SAGA and TREX-2. We present here the crystal structure of the complex between Sus1 and the N-terminal region of Sgf11 that forms an extended alpha-helix around which Sus1 wraps in a manner that shares some similarities with the Sus1-Sac3 interface in TREX-2. However, the Sus1-binding site on Sgf11 is somewhat shorter than on Sac3 and is based on a narrower hydrophobic stripe. Engineered mutants that disrupt the Sgf11-Sus1 interaction in vitro confirm the importance of the hydrophobic helical stripe in molecular recognition. Helix alpha1 of the Sus1-articulated hairpin does not bind directly to Sgf11 and adopts a wide range of conformations within and between crystal forms, consistent with the presence of a flexible hinge and also with results from previous extensive mutagenesis studies (Klöckner, C., Schneider, M., Lutz, S., Jani, D., Kressler, D., Stewart, M., Hurt, E., and Köhler, A. (2009) J. Biol. Chem. 284, 12049-12056). A single Sus1 molecule cannot bind Sgf11 and Sac3 simultaneously and this, combined with the structure of the Sus1-Sgf11 complex, indicates that Sus1 forms separate subcomplexes within SAGA and TREX-2.

  11. Novel binding motif and new flexibility revealed by structural analyses of a pyruvate dehydrogenase-dihydrolipoyl acetyltransferase subcomplex from the Escherichia coli pyruvate dehydrogenase multienzyme complex.

    PubMed

    Arjunan, Palaniappa; Wang, Junjie; Nemeria, Natalia S; Reynolds, Shelley; Brown, Ian; Chandrasekhar, Krishnamoorthy; Calero, Guillermo; Jordan, Frank; Furey, William

    2014-10-24

    The Escherichia coli pyruvate dehydrogenase multienzyme complex contains multiple copies of three enzymatic components, E1p, E2p, and E3, that sequentially carry out distinct steps in the overall reaction converting pyruvate to acetyl-CoA. Efficient functioning requires the enzymatic components to assemble into a large complex, the integrity of which is maintained by tethering of the displaced, peripheral E1p and E3 components to the E2p core through non-covalent binding. We here report the crystal structure of a subcomplex between E1p and an E2p didomain containing a hybrid lipoyl domain along with the peripheral subunit-binding domain responsible for tethering to the core. In the structure, a region at the N terminus of each subunit in the E1p homodimer previously unseen due to crystallographic disorder was observed, revealing a new folding motif involved in E1p-E2p didomain interactions, and an additional, unexpected, flexibility was discovered in the E1p-E2p didomain subcomplex, both of which probably have consequences in the overall multienzyme complex assembly. This represents the first structure of an E1p-E2p didomain subcomplex involving a homodimeric E1p, and the results may be applicable to a large range of complexes with homodimeric E1 components. Results of HD exchange mass spectrometric experiments using the intact, wild type 3-lipoyl E2p and E1p are consistent with the crystallographic data obtained from the E1p-E2p didomain subcomplex as well as with other biochemical and NMR data reported from our groups, confirming that our findings are applicable to the entire E1p-E2p assembly. PMID:25210042

  12. 30 CFR 56.15002 - Hard hats.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Hard hats. 56.15002 Section 56.15002 Mineral... HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Personal Protection § 56.15002 Hard hats. All persons shall wear suitable hard hats when in or around a mine or plant where falling...

  13. 30 CFR 57.15002 - Hard hats.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Hard hats. 57.15002 Section 57.15002 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... Underground § 57.15002 Hard hats. All persons shall wear suitable hard hats when in or around a mine or...

  14. Rational design and validation of a Tip60 histone acetyltransferase inhibitor

    NASA Astrophysics Data System (ADS)

    Gao, Chunxia; Bourke, Emer; Scobie, Martin; Famme, Melina Arcos; Koolmeister, Tobias; Helleday, Thomas; Eriksson, Leif A.; Lowndes, Noel F.; Brown, James A. L.

    2014-06-01

    Histone acetylation is required for many aspects of gene regulation, genome maintenance and metabolism and dysfunctional acetylation is implicated in numerous diseases, including cancer. Acetylation is regulated by histone acetyltransferases (HATs) and histone deacetylases and currently, few general HAT inhibitors have been described. We identified the HAT Tip60 as an excellent candidate for targeted drug development, as Tip60 is a key mediator of the DNA damage response and transcriptional co-activator. Our modeling of Tip60 indicated that the active binding pocket possesses opposite charges at each end, with the positive charges attributed to two specific side chains. We used structure based drug design to develop a novel Tip60 inhibitor, TH1834, to fit this specific pocket. We demonstrate that TH1834 significantly inhibits Tip60 activity in vitro and treating cells with TH1834 results in apoptosis and increased unrepaired DNA damage (following ionizing radiation treatment) in breast cancer but not control cell lines. Furthermore, TH1834 did not affect the activity of related HAT MOF, as indicated by H4K16Ac, demonstrating specificity. The modeling and validation of the small molecule inhibitor TH1834 represents a first step towards developing additional specific, targeted inhibitors of Tip60 that may lead to further improvements in the treatment of breast cancer.

  15. Perturbation of Mitosis through Inhibition of Histone Acetyltransferases: The Key to Ochratoxin A Toxicity and Carcinogenicity?

    PubMed Central

    Czakai, Kristin; Müller, Katja; Mosesso, Pasquale; Pepe, Gaetano; Schulze, Markus; Gohla, Antje; Patnaik, Debasis; Dekant, Wolfgang; Higgins, Jonathan M.G.; Mally, Angela

    2011-01-01

    Ochratoxin A (OTA) is one of the most potent rodent renal carcinogens studied to date. Although controversial results regarding OTA genotoxicity have been published, it is now widely accepted that OTA is not a mutagenic, DNA-reactive carcinogen. Instead, increasing evidence from both in vivo and in vitro studies suggests that OTA may promote genomic instability and tumorigenesis through interference with cell division. The aim of the present study was to provide further support for disruption of mitosis as a key event in OTA toxicity and to understand how OTA mediates these effects. Immortalized human kidney epithelial cells (IHKE) were treated with OTA and monitored by differential interference contrast microscopy for 15 h. Image analysis confirmed that OTA at concentrations ≥ 5μM, which correlate with plasma concentrations in rats under conditions of carcinogenesis, causes sustained mitotic arrest and exit from mitosis without nuclear or cellular division. Mitotic chromosomes were characterized by aberrant condensation and premature sister chromatid separation associated with altered phosphorylation and acetylation of core histones. To test if OTA directly interferes with histone acetyltransferases (HATs) which regulate lysine acetylation of histones and nonhistone proteins, a cell-free HAT activity assay was conducted using total nuclear extracts of IHKE cells. In this assay, OTA significantly blocked HAT activity in a concentration-dependent manner Overall, results from this study provide further support for a mechanism of OTA carcinogenicity involving interference with the mitotic machinery and suggest HATs as a primary cellular target of OTA. PMID:21551354

  16. Interaction with the histone chaperone Vps75 promotes nuclear localization and HAT activity of Rtt109 in vivo

    PubMed Central

    Keck, Kristin M.; Pemberton, Lucy F.

    2011-01-01

    Modification of histones is critical for the regulation of all chromatin-templated processes. Yeast Rtt109 is a histone acetyltransferase (HAT) that acetylates H3 lysines 9, 27 and 56. Rtt109 associates with and is stabilized by Nap1 family histone chaperone Vps75. Our data suggest Vps75 and Nap1 have some overlapping functions despite their different cellular localization and histone binding specificity. We determined that Vps75 contains a classical nuclear localization signal and is imported by Kap60–Kap95. Rtt109 nuclear localization depends on Vps75, and nuclear localization of the Vps75-Rtt109 complex is not critical for Rtt109-dependent functions, suggesting Rtt109 may be able to acetylate nascent histones before nuclear import. To date, the effects of VPS75 deletion on Rtt109 function had not been separated from the resulting Rtt109 degradation; thus, we used an Rtt109 mutant lacking the Vps75-interaction domain that is stable without Vps75. Our data show that in addition to promoting Rtt109 stability, Vps75 binding is necessary for Rtt109 acetylation of the H3 tail. Direct interaction of Vps75 with H3 likely allows Rtt109 access to the histone tail. Furthermore, our genetic interaction data support the idea of Rtt109-independent functions of Vps75. In summary, our data suggest that Vps75 influences chromatin structure by regulating histone modification and through its histone chaperone functions. PMID:21463458

  17. C646, a Novel p300/CREB-Binding Protein-Specific Inhibitor of Histone Acetyltransferase, Attenuates Influenza A Virus Infection

    PubMed Central

    Zhao, Dongming; Fukuyama, Satoshi; Sakai-Tagawa, Yuko; Takashita, Emi; Shoemaker, Jason E.

    2015-01-01

    New strategies to develop novel broad-spectrum antiviral drugs against influenza virus infections are needed due to the emergence of antigenic variants and drug-resistant viruses. Here, we evaluated C646, a novel p300/CREB-binding protein-specific inhibitor of histone acetyltransferase (HAT), as an anti-influenza virus agent in vitro and in vivo and explored how C646 affects the viral life cycle and host response. Our studies highlight the value of targeting HAT activity for anti-influenza drug development. PMID:26711748

  18. Rare allele of a previously unidentified histone H4 acetyltransferase enhances grain weight, yield, and plant biomass in rice

    PubMed Central

    Song, Xian Jun; Kuroha, Takeshi; Ayano, Madoka; Furuta, Tomoyuki; Nagai, Keisuke; Komeda, Norio; Segami, Shuhei; Miura, Kotaro; Ogawa, Daisuke; Kamura, Takumi; Suzuki, Takamasa; Higashiyama, Tetsuya; Yamasaki, Masanori; Mori, Hitoshi; Inukai, Yoshiaki; Wu, Jianzhong; Kitano, Hidemi; Sakakibara, Hitoshi; Jacobsen, Steven E.; Ashikari, Motoyuki

    2015-01-01

    Grain weight is an important crop yield component; however, its underlying regulatory mechanisms are largely unknown. Here, we identify a grain-weight quantitative trait locus (QTL) encoding a new-type GNAT-like protein that harbors intrinsic histone acetyltransferase activity (OsglHAT1). Our genetic and molecular evidences pinpointed the QTL-OsglHAT1’s allelic variations to a 1.2-kb region upstream of the gene body, which is consistent with its function as a positive regulator of the traits. Elevated OsglHAT1 expression enhances grain weight and yield by enlarging spikelet hulls via increasing cell number and accelerating grain filling, and increases global acetylation levels of histone H4. OsglHAT1 localizes to the nucleus, where it likely functions through the regulation of transcription. Despite its positive agronomical effects on grain weight, yield, and plant biomass, the rare allele elevating OsglHAT1 expression has so far escaped human selection. Our findings reveal the first example, to our knowledge, of a QTL for a yield component trait being due to a chromatin modifier that has the potential to improve crop high-yield breeding. PMID:25535376

  19. Cloning and analysis of a Toxoplasma gondii histone acetyltransferase: a novel chromatin remodelling factor in Apicomplexan parasites.

    PubMed

    Hettmann, C; Soldati, D

    1999-11-15

    The yeast transcriptional adaptor GCN5 functions as a histone acetyltransferase, directly linking chromatin modification to transcriptional regulation. Homologues of yeast GCN5 have been found in Tetrahymena, Drosophila, Arabidopsis and human, suggesting that this pathway of chromatin remodelling is evolutionarily conserved. Consistent with this view, we have identified the Toxoplasma gondii homologue, referred to here as TgGCN5. The gene codes for a protein of 474 amino acids with an estimated molecular mass of 53 kDa. The protein reveals two regions of close similarity with the GCN5 family members, the HAT domain and the bromodomain. Tg GCN5 occurs in a single copy in the T.gondii genome. The introduction of a second copy of TgGCN5 in T.gondii tachyzoites is toxic unless the HAT activity is disrupted by a single point mutation. Full TgGCN5 does not complement the growth defect in a yeast gcn5 (-)mutant strain, but a chimera comprising the T.gondii HAT domain fused to the remainder of yGCN5 does. These data show that T.gondii GNC5 is a histone acetyltransferase attesting to the significance of chromatin remodelling in gene regulation of Apicomplexa.

  20. von Hippel-Lindau partner Jade-1 is a transcriptional co-activator associated with histone acetyltransferase activity.

    PubMed

    Panchenko, Maria V; Zhou, Mina I; Cohen, Herbert T

    2004-12-31

    Jade-1 was identified as a protein partner of the von Hippel-Lindau tumor suppressor pVHL. The interaction of Jade-1 and pVHL correlates with renal cancer risk. We have investigated the molecular function of Jade-1. Jade-1 has two zinc finger motifs called plant homeodomains (PHD). A line of evidence suggests that the PHD finger functions in chromatin remodeling and protein-protein interactions. We determined the cellular localization of Jade-1 and examined whether Jade-1 might have transcriptional and histone acetyltransferase (HAT) functions. Biochemical cell fractionation studies as well as confocal images of cells immunostained with a specific Jade-1 antibody revealed that endogenous Jade-1 is localized predominantly in the cell nucleus. Tethering of Gal4-Jade-1 fusion protein to Gal4-responsive promoters in co-transfection experiments activated transcription 5-6-fold, indicating that Jade-1 is a possible transcriptional activator. It was remarkable that overexpression of Jade-1 in cultured cells specifically increased levels of endogenous acetylated histone H4, but not histone H3, strongly suggesting that Jade-1 associates with HAT activity specific for histone H4. Deletion of the two PHD fingers completely abolished Jade-1 transcriptional and HAT activities, indicating that these domains are indispensable for Jade-1 nuclear functions. In addition, we demonstrated that TIP60, a known HAT with histone H4/H2A specificity, physically associates with Jade-1 and is able to augment Jade-1 HAT function in live cells, strongly suggesting that TIP60 might mediate Jade-1 HAT activity. Thus, Jade-1 is a novel candidate transcriptional co-activator associated with HAT activity and may play a key role in the pathogenesis of renal cancer and von Hippel-Lindau disease.

  1. Distinct and Redundant Roles of the Two MYST Histone Acetyltransferases Esa1 and Sas2 in Cell Growth and Morphogenesis of Candida albicans

    PubMed Central

    Wang, Xiongjun; Chang, Peng; Ding, Jianping

    2013-01-01

    Candida albicans is associated with humans, as both a harmless commensal organism and a pathogen. Adaption to human body temperature is extremely important for its growth and morphogenesis. Saccharomyces cerevisiae Esa1, a member of the MYST family HATs (histone acetyltransferases) and the catalytic subunit of the NuA4 complex, and its homologues in other eukaryotes have been shown to be essential for cell growth. To investigate the functional roles of two MYST family HATs, Esa1 and Sas2 in C. albicans, we deleted ESA1 and SAS2 in the C. albicans genome and performed cell growth analyses. Our results demonstrated that C. albicans Esa1 is not essential for general growth but is essential for filamentous growth. The esa1/esa1 mutant cells exhibited sensitivity to thermal, genotoxic, and oxidative stresses but tolerance to cold, osmotic, and cell wall stresses. In contrast, the sas2/sas2 mutant adapted to growth at higher temperatures and promoted filament formation at lower temperatures, resembling the phenotype of a C. albicans strain overexpressing ESA1. Cells with deletions of both ESA1 and SAS2 were inviable, reflecting the functional redundancy in cell growth. C. albicans Esa1 and Sas2 have distinct and synergistic effects on histone acetylation at H4K5, H4K12, and H4K16. Esa1 contributes mainly to acetylation of H4K5 and H4K12, whereas Sas2 contributes to acetylation of H4K16. Our findings suggest that C. albicans Esa1 and Sas2 play opposite roles in cell growth and morphogenesis and contribute coordinately to histone acetylation and gene regulation. PMID:23355007

  2. Top-hat random fiber Bragg grating.

    PubMed

    Yin, Hongwei; Gbadebo, Adenowo; Turitsyna, Elena G

    2015-08-01

    We examined the possibility of using noise or pseudo-random variations of the refractive index in the design of fiber Bragg gratings (FBGs). We demonstrated theoretically and experimentally that top-hat FBGs may be designed and fabricated using this approach. The reflectivity of the fabricated top-hat FBG matches quite well with that of the designed one. PMID:26258365

  3. Neisseria meningitidis serogroup A capsular polysaccharide acetyltransferase, methods and compositions

    DOEpatents

    Stephens, David S.; Gudlavalleti, Seshu K.; Tzeng, Yih-Ling; Datta, Anup K.; Carlson, Russell W.

    2011-02-08

    Provided are methods for recombinant production of an O-acetyltransferase and methods for acetylating capsular polysaccharides, especially those of a Serogroup A Neisseria meningitidis using the recombinant O-acetyltransferase, and immunogenic compositions comprising the acetylated capsular polysaccharide.

  4. Physical association of the WC-1 photoreceptor and the histone acetyltransferase NGF-1 is required for blue light signal transduction in Neurospora crassa.

    PubMed

    Brenna, Andrea; Grimaldi, Benedetto; Filetici, Patrizia; Ballario, Paola

    2012-10-01

    In Neurospora crassa and other filamentous fungi, light-dependent-specific phenomena are regulated by transcription factors WC-1 and WC-2. In addition to its transcriptional activity, WC-1 is able to directly sense light stimuli through a LOV sensor domain. Its location in the nucleus and heterodimerization with WC-2, together with the presence of a zinc-finger DNA-binding domain and an environmental sensor domain, all resemble the functional evolutionary architecture adopted by vertebrate nuclear receptors (NRs). Here we describe a scenario in which WC-1 represents a functional orthologue of NRs and acts through association with the chromatin-modifying coactivator NGF-1, which encodes a homologue of the yeast Gcn5p acetyltransferase. To support this view, we show a direct association between WC-1 and NGF-1 that depends on a WC-1 region containing a conserved functional LXXLL motif, a signature previously described as being an exclusive feature of NR/coactivator interaction. Our data suggest that a WC-1/NGF-1 complex is preassembled in the dark on light-inducible promoters and that, after exposure to light stimulation, NGF-1-associated HAT activity leads to histone H3 acetylation and transcriptional activation. Finally, we provide evidence for a NGF-1-independent acetylated form of WC-1. Overall our data indicate that Neurospora and higher eukaryotes share a common mechanism for the signal transduction of environmental stimuli.

  5. Anti-histone acetyltransferase activity from allspice extracts inhibits androgen receptor-dependent prostate cancer cell growth.

    PubMed

    Lee, Yoo-Hyun; Hong, Soon Won; Jun, Woojin; Cho, Hong Yon; Kim, Han-Cheon; Jung, Myung Gu; Wong, Jiemin; Kim, Ha-Il; Kim, Chang-Hoon; Yoon, Ho-Geun

    2007-11-01

    Histone acetylation depends on the activity of two enzyme families, histone acetyltransferase (HAT) and deacetylase (HDAC). In this study, we screened various plant extracts to find potent HAT inhibitors. Hot water extracts of allspice inhibited HAT activity, especially p300 and CBP (40% at 100 microg/ml). The mRNA levels of two androgen receptor (AR) regulated genes, PSA and TSC22, decreased with allspice treatment (100 microg/ml). Importantly, in IP western analysis, AR acetylation was dramatically decreased by allspice treatment.Furthermore, chromatin immunoprecipitation indicated that the acetylation of histone H3 in the PSA and B2M promoter regions was also repressed. Finally, allspice treatment reduced the growth of human prostate cancer cells, LNCaP (50% growth inhibition at 200 microg/ml). Taken together, our data indicate that the potent HAT inhibitory activity of allspice reduced AR and histone acetylation and led to decreased transcription of AR target genes, resulting in inhibition of prostate cancer cell growth.

  6. 15-Deoxy-{Delta}{sup 12,14}-prostaglandin J{sub 2} impairs the functions of histone acetyltransferases through their insolubilization in cells

    SciTech Connect

    Hironaka, Asako; Morisugi, Toshiaki; Kawakami, Tetsuji; Miyagi, Ikuko; Tanaka, Yasuharu

    2009-12-11

    The cyclopentenonic prostaglandin 15-deoxy-{Delta}{sup 12,14}-PG J{sub 2} (15d-PGJ{sub 2}) is a metabolite derived from PGD{sub 2}. Although 15d-PGJ{sub 2} has been demonstrated to be a potent ligand for peroxisome proliferator activated receptor {gamma} (PPAR{gamma}), the functions are not fully understood. In order to examine the effect of 15d-PGJ{sub 2} on histone acetyltransferases (HATs), several lines of cell including mouse embryonic fibroblast (MEF) cells were exposed to 15d-PGJ{sub 2}. Three types of HAT, p300, CREB-binding protein (CBP), and p300/CBP-associated factor (PCAF), selectively disappeared from the soluble fraction in time- and dose-dependent manners. Inversely, HATs in the insoluble fraction increased, suggesting their conformational changes. The decrease in the soluble form of HATs resulted in the attenuation of NF-{kappa}B-, p53-, and heat shock factor-dependent reporter gene expressions, implying that the insoluble HATs are inactive. The resultant insoluble PCAF and p300 seemed to be digested by proteasome, because proteasome inhibitors caused the accumulation of insoluble HATs. Taken together, these results indicate that 15d-PGJ{sub 2} attenuates some gene expressions that require HATs. This inhibitory action of 15d-PGJ{sub 2} on the function of HATs was independent of PPAR{gamma}, because PPAR{gamma} agonists could not mimick 15d-PGJ{sub 2} and PPAR{gamma} antagonists did not inhibit 15d-PGJ{sub 2}.

  7. Histone acetyltransferase inhibitor CPTH6 preferentially targets lung cancer stem-like cells

    PubMed Central

    Di Martile, Marta; Desideri, Marianna; De Luca, Teresa; Gabellini, Chiara; Buglioni, Simonetta; Eramo, Adriana; Sette, Giovanni; Milella, Michele; Rotili, Dante; Mai, Antonello; Carradori, Simone; Secci, Daniela; De Maria, Ruggero; Del Bufalo, Donatella; Trisciuoglio, Daniela

    2016-01-01

    Cancer stem cells (CSCs) play an important role in tumor initiation, progression, therapeutic failure and tumor relapse. In this study, we evaluated the efficacy of the thiazole derivative 3-methylcyclopentylidene-[4-(4′-chlorophenyl)thiazol-2-yl]hydrazone (CPTH6), a novel pCAF and Gcn5 histone acetyltransferase inhibitor, as a small molecule that preferentially targets lung cancer stem-like cells (LCSCs) derived from non-small cell lung cancer (NSCLC) patients. Notably, although CPTH6 inhibits the growth of both LCSC and NSCLC cell lines, LCSCs exhibit greater growth inhibition than established NSCLC cells. Growth inhibitory effect of CPTH6 in LCSC lines is primarily due to apoptosis induction. Of note, differentiated progeny of LCSC lines is more resistant to CPTH6 in terms of loss of cell viability and reduction of protein acetylation, when compared to their undifferentiated counterparts. Interestingly, in LCSC lines CPTH6 treatment is also associated with a reduction of stemness markers. By using different HAT inhibitors we provide clear evidence that inhibition of HAT confers a strong preferential inhibitory effect on cell viability of undifferentiated LCSC lines when compared to their differentiated progeny. In vivo, CPTH6 is able to inhibit the growth of LCSC-derived xenografts and to reduce cancer stem cell content in treated tumors, as evidenced by marked reduction of tumor-initiating capacity in limiting dilution assays. Strikingly, the ability of CPTH6 to inhibit tubulin acetylation is also confirmed in vivo. Overall, our studies propose histone acetyltransferase inhibition as an attractive target for cancer therapy of NSCLC. PMID:26870991

  8. Molecular mechanism underlying promiscuous polyamine recognition by spermidine acetyltransferase.

    PubMed

    Sugiyama, Shigeru; Ishikawa, Sae; Tomitori, Hideyuki; Niiyama, Mayumi; Hirose, Mika; Miyazaki, Yuma; Higashi, Kyohei; Murata, Michio; Adachi, Hiroaki; Takano, Kazufumi; Murakami, Satoshi; Inoue, Tsuyoshi; Mori, Yusuke; Kashiwagi, Keiko; Igarashi, Kazuei; Matsumura, Hiroyoshi

    2016-07-01

    Spermidine acetyltransferase (SAT) from Escherichia coli, which catalyses the transfer of acetyl groups from acetyl-CoA to spermidine, is a key enzyme in controlling polyamine levels in prokaryotic cells. In this study, we determined the crystal structure of SAT in complex with spermidine (SPD) and CoA at 2.5Å resolution. SAT is a dodecamer organized as a hexamer of dimers. The secondary structural element and folding topology of the SAT dimer resemble those of spermidine/spermine N(1)-acetyltransferase (SSAT), suggesting an evolutionary link between SAT and SSAT. However, the polyamine specificity of SAT is distinct from that of SSAT and is promiscuous. The SPD molecule is also located at the inter-dimer interface. The distance between SPD and CoA molecules is 13Å. A deep, highly acidic, water-filled cavity encompasses the SPD and CoA binding sites. Structure-based mutagenesis and in-vitro assays identified SPD-bound residues, and the acidic residues lining the walls of the cavity are mostly essential for enzymatic activities. Based on mutagenesis and structural data, we propose an acetylation mechanism underlying promiscuous polyamine recognition for SAT. PMID:27163532

  9. Delphinidin, a specific inhibitor of histone acetyltransferase, suppresses inflammatory signaling via prevention of NF-{kappa}B acetylation in fibroblast-like synoviocyte MH7A cells

    SciTech Connect

    Seong, Ah-Reum; Yoo, Jung-Yoon; Choi, KyungChul; Lee, Mee-Hee; Lee, Yoo-Hyun; Lee, Jeongmin; Jun, Woojin; Kim, Sunoh; Yoon, Ho-Geun

    2011-07-08

    Highlights: {yields} Delphinidin is a novel inhibitor of p300/CBP histone acetyltransferase. {yields} Delphinidin prevents the hyperacetylation of p65 by inhibiting the HAT activity of p300/CBP. {yields} Delphinidin efficiently suppresses the expression of inflammatory cytokines in MH7A cells via hypoacetylation of NF-{kappa}B. {yields} Delphinidin inhibits cytokine release in the Jurkat T lymphocyte cell line. -- Abstract: Histone acetyltransferase (HAT) inhibitors (HATi) isolated from dietary compounds have been shown to suppress inflammatory signaling, which contributes to rheumatoid arthritis. Here, we identified a novel HATi in Punica granatum L. known as delphinidin (DP). DP did not affect the activity of other epigenetic enzymes (histone deacetylase, histone methyltransferase, or sirtuin1). DP specifically inhibited the HAT activities of p300/CBP. It also inhibited p65 acetylation in MH7A cells, a human rheumatoid arthritis synovial cell line. DP-induced hypoacetylation was accompanied by cytosolic accumulation of p65 and nuclear localization of IKB{alpha}. Accordingly, DP treatment inhibited TNF{alpha}-stimulated increases in NF-{kappa}B function and expression of NF-{kappa}B target genes in these cells. Importantly, DP suppressed lipopolysaccharide-induced pro-inflammatory cytokine expression in Jurkat T lymphocytes, demonstrating that HATi efficiently suppresses cytokine-mediated immune responses. Together, these results show that the HATi activity of DP counters anti-inflammatory signaling by blocking p65 acetylation and that this compound may be useful in preventing inflammatory arthritis.

  10. N-hydroxyarylamine O-acetyltransferase of Salmonella typhimurium: proposal for a common catalytic mechanism of arylamine acetyltransferase enzymes.

    PubMed Central

    Watanabe, M; Igarashi, T; Kaminuma, T; Sofuni, T; Nohmi, T

    1994-01-01

    Acetyl-CoA:N-hydroxyarylamine O-acetyltransferase is an enzyme involved in the metabolic activation of N-hydroxyarylamines derived from mutagenic and carcinogenic aromatic amines and nitroarenes. The O-acetyltransferase gene of Salmonella typhimurium has been cloned, and new Ames tester substrains highly sensitive to mutagenic aromatic amines and nitroarenes have been established in our laboratory. The nucleotide sequence of the O-acetyltransferase gene was determined. There was an open reading frame of 843 nucleotides coding for a protein with a calculated molecular weight of 32,177, which was close to the molecular weight of the O-acetyltransferase protein determined by using the maxicell technique. Only the residue of Cys69 in O-acetyltransferase of S. typhimurium and its corresponding residue (Cys68) in N-acetyltransferase of higher organisms were conserved in all acetyltransferase enzymes sequenced so far. The amino acid sequence Arg-Gly-Gly-X-Cys, including the Cys69, was highly conserved. A mutant O-acetyltransferase of S. typhimurium, which contained Ala69 instead of Cys69, no longer showed the activities of O- and N-acetyltransferase. These results suggest that the Cys69 of S. typhimurium and the corresponding cysteine residues of the higher organisms are essential for the enzyme activities as an acetyl-CoA binding site. We propose a new catalytic model of acetyltransferase for S. typhimurium and the higher organisms. PMID:7889864

  11. The Aspergillus flavus Histone Acetyltransferase AflGcnE Regulates Morphogenesis, Aflatoxin Biosynthesis, and Pathogenicity.

    PubMed

    Lan, Huahui; Sun, Ruilin; Fan, Kun; Yang, Kunlong; Zhang, Feng; Nie, Xin Y; Wang, Xiunai; Zhuang, Zhenhong; Wang, Shihua

    2016-01-01

    Histone acetyltransferases (HATs) help regulate fungal development and the production of secondary metabolites. In this study, we determined that the HAT AflGcnE influenced morphogenesis and aflatoxin biosynthesis in Aspergillus flavus. We observed that AflGcnE localized to the nucleus and cytoplasm during the conidial production and germination stages, while it was located mainly in the nucleus during the hyphal development stage. Deletion of AflgcnE inhibited the growth of A. flavus and decreased the hydrophobicity of the cell surface. The ΔAflgcnE mutant exhibited a lack of asexual sporulation and was unable to generate sclerotia. Additionally, AflgcnE was required to maintain cell wall integrity and genotoxic stress responses. Importantly, the ΔAflgcnE mutant did not produce aflatoxins, which was consistent with a significant down-regulation of aflatoxin gene expression levels. Furthermore, our data revealed that AflgcnE is a pathogenicity factor required for colonizing maize seeds. In summary, we revealed that A. flavus AflGcnE is crucial for morphological development, aflatoxin biosynthesis, stress responses, and pathogenicity. Our findings help clarify the functional divergence of GcnE orthologs, and may provide a possible target for controlling A. flavus infections of agriculturally important crops. PMID:27625637

  12. The Aspergillus flavus Histone Acetyltransferase AflGcnE Regulates Morphogenesis, Aflatoxin Biosynthesis, and Pathogenicity

    PubMed Central

    Lan, Huahui; Sun, Ruilin; Fan, Kun; Yang, Kunlong; Zhang, Feng; Nie, Xin Y.; Wang, Xiunai; Zhuang, Zhenhong; Wang, Shihua

    2016-01-01

    Histone acetyltransferases (HATs) help regulate fungal development and the production of secondary metabolites. In this study, we determined that the HAT AflGcnE influenced morphogenesis and aflatoxin biosynthesis in Aspergillus flavus. We observed that AflGcnE localized to the nucleus and cytoplasm during the conidial production and germination stages, while it was located mainly in the nucleus during the hyphal development stage. Deletion of AflgcnE inhibited the growth of A. flavus and decreased the hydrophobicity of the cell surface. The ΔAflgcnE mutant exhibited a lack of asexual sporulation and was unable to generate sclerotia. Additionally, AflgcnE was required to maintain cell wall integrity and genotoxic stress responses. Importantly, the ΔAflgcnE mutant did not produce aflatoxins, which was consistent with a significant down-regulation of aflatoxin gene expression levels. Furthermore, our data revealed that AflgcnE is a pathogenicity factor required for colonizing maize seeds. In summary, we revealed that A. flavus AflGcnE is crucial for morphological development, aflatoxin biosynthesis, stress responses, and pathogenicity. Our findings help clarify the functional divergence of GcnE orthologs, and may provide a possible target for controlling A. flavus infections of agriculturally important crops. PMID:27625637

  13. The Aspergillus flavus Histone Acetyltransferase AflGcnE Regulates Morphogenesis, Aflatoxin Biosynthesis, and Pathogenicity

    PubMed Central

    Lan, Huahui; Sun, Ruilin; Fan, Kun; Yang, Kunlong; Zhang, Feng; Nie, Xin Y.; Wang, Xiunai; Zhuang, Zhenhong; Wang, Shihua

    2016-01-01

    Histone acetyltransferases (HATs) help regulate fungal development and the production of secondary metabolites. In this study, we determined that the HAT AflGcnE influenced morphogenesis and aflatoxin biosynthesis in Aspergillus flavus. We observed that AflGcnE localized to the nucleus and cytoplasm during the conidial production and germination stages, while it was located mainly in the nucleus during the hyphal development stage. Deletion of AflgcnE inhibited the growth of A. flavus and decreased the hydrophobicity of the cell surface. The ΔAflgcnE mutant exhibited a lack of asexual sporulation and was unable to generate sclerotia. Additionally, AflgcnE was required to maintain cell wall integrity and genotoxic stress responses. Importantly, the ΔAflgcnE mutant did not produce aflatoxins, which was consistent with a significant down-regulation of aflatoxin gene expression levels. Furthermore, our data revealed that AflgcnE is a pathogenicity factor required for colonizing maize seeds. In summary, we revealed that A. flavus AflGcnE is crucial for morphological development, aflatoxin biosynthesis, stress responses, and pathogenicity. Our findings help clarify the functional divergence of GcnE orthologs, and may provide a possible target for controlling A. flavus infections of agriculturally important crops.

  14. Garcinol, a Histone Acetyltransferase Inhibitor, Radiosensitizes Cancer Cells by Inhibiting Non-Homologous End Joining

    SciTech Connect

    Oike, Takahiro; Ogiwara, Hideaki; Torikai, Kohta; Nakano, Takashi; Yokota, Jun; Kohno, Takashi

    2012-11-01

    Purpose: Non-homologous end joining (NHEJ), a major pathway used to repair DNA double-strand breaks (DSBs) generated by ionizing radiation (IR), requires chromatin remodeling at DSB sites through the acetylation of histones by histone acetyltransferases (HATs). However, the effect of compounds with HAT inhibitory activities on the DNA damage response (DDR), including the NHEJ and cell cycle checkpoint, as well as on the radiosensitivity of cancer cells, remains largely unclear. Here, we investigated whether garcinol, a HAT inhibitor found in the rinds of Garcinia indica fruit (called mangosteens), has effects on DDR, and whether it can be used for radiosensitization. Methods and Materials: The following assays were used to examine the effect of garcinol on the inhibition of DSB repair, including the following: a conventional neutral comet assay; a cell-based assay recently developed by us, in which NHEJ repair of DSBs on chromosomal DNA was evaluated; the micrococcal nuclease sensitivity assay; and immunoblotting for autophosphorylation of DNA-dependent protein kinase catalytic subunit (DNA-PKcs). We assessed the effect of garcinol on the cell cycle checkpoint after IR treatment by analyzing the phosphorylation levels of checkpoint kinases CHK1 and CHK2 and histone H3, and by cell cycle profile analysis using flow cytometry. The radiosensitizing effect of garcinol was assessed by a clonogenic survival assay, whereas its effects on apoptosis and senescence were examined by annexin V and senescence-associated {beta}-galactosidase (SA-{beta}-Gal) staining, respectively. Results: We found that garcinol inhibits DSB repair, including NHEJ, without affecting cell cycle checkpoint. Garcinol radiosensitized A549 lung and HeLa cervical carcinoma cells with dose enhancement ratios (at 10% surviving fraction) of 1.6 and 1.5, respectively. Cellular senescence induced by IR was enhanced by garcinol. Conclusion: These results suggest that garcinol is a radiosensitizer that

  15. Nonperiodic echoes from mushroom billiard hats

    NASA Astrophysics Data System (ADS)

    Dietz, B.; Friedrich, T.; Miski-Oglu, M.; Richter, A.; Seligman, T. H.; Zapfe, K.

    2006-11-01

    Mushroom billiards have the remarkable property to show one or more clear cut integrable islands in one or several chaotic seas, without any fractal boundaries. The islands correspond to orbits confined to the hats of the mushrooms, which they share with the chaotic orbits. It is thus interesting to ask how long a chaotic orbit will remain in the hat before returning to the stem. This question is equivalent to the inquiry about delay times for scattering from the hat of the mushroom into an opening where the stem should be. For fixed angular momentum we find that no more than three different delay times are possible. This induces striking nonperiodic structures in the delay times that may be of importance for mesoscopic devices and should be accessible to microwave experiments.

  16. Error bars for three-cornered hats.

    PubMed

    Ekstrom, Christopher R; Koppang, Paul A

    2006-05-01

    Abstract-The three-cornered hat is a procedure for extracting the stabilities of three clocks when the only available data is the time or frequency differences between the clocks. To our knowledge, there has been no method of determining a confidence interval for such a stability estimate. In this paper, we present a method for determining the number of degrees of freedom of the estimate, which allows the assignment of a confidence interval to a three-cornered hat stability estimate. We also investigate using the total variance and biases involved.

  17. Structural insights into yeast histone chaperone Hif1: a scaffold protein recruiting protein complexes to core histones.

    PubMed

    Liu, Hejun; Zhang, Mengying; He, Wei; Zhu, Zhongliang; Teng, Maikun; Gao, Yongxiang; Niu, Liwen

    2014-09-15

    Yeast Hif1 [Hat1 (histone acetyltransferase 1)-interacting factor], a homologue of human NASP (nuclear autoantigenic sperm protein), is a histone chaperone that is involved in various protein complexes which modify histones during telomeric silencing and chromatin reassembly. For elucidating the structural basis of Hif1, in the present paper we demonstrate the crystal structure of Hif1 consisting of a superhelixed TPR (tetratricopeptide repeat) domain and an extended acid loop covering the rear of TPR domain, which represent typical characteristics of SHNi-TPR [Sim3 (start independent of mitosis 3)-Hif1-NASP interrupted TPR] proteins. Our binding assay indicates that Hif1 could bind to the histone octamer via histones H3 and H4. The acid loop is shown to be crucial for the binding of histones and may also change the conformation of the TPR groove. By binding to the core histone complex Hif1 may recruit functional protein complexes to modify histones during chromatin reassembly.

  18. New N-Acetyltransferase Fold in the Structure and Mechanism of the Phosphonate Biosynthetic Enzyme FrbF

    SciTech Connect

    Bae, Brian; Cobb, Ryan E.; DeSieno, Matthew A.; Zhao, Huimin; Nair, Satish K.

    2015-10-15

    The enzyme FrbF from Streptomyces rubellomurinus has attracted significant attention due to its role in the biosynthesis of the antimalarial phosphonate FR-900098. The enzyme catalyzes acetyl transfer onto the hydroxamate of the FR-900098 precursors cytidine 5'-monophosphate-3-aminopropylphosphonate and cytidine 5'-monophosphate-N-hydroxy-3-aminopropylphosphonate. Despite the established function as a bona fide N-acetyltransferase, FrbF shows no sequence similarity to any member of the GCN5-like N-acetyltransferase (GNAT) superfamily. Here, we present the 2.0 {angstrom} resolution crystal structure of FrbF in complex with acetyl-CoA, which demonstrates a unique architecture that is distinct from those of canonical GNAT-like acetyltransferases. We also utilized the co-crystal structure to guide structure-function studies that identified the roles of putative active site residues in the acetyltransferase mechanism. The combined biochemical and structural analyses of FrbF provide insights into this previously uncharacterized family of N-acetyltransferases and also provide a molecular framework toward the production of novel N-acyl derivatives of FR-900098.

  19. James J. Gallagher: Man in the White Hat

    ERIC Educational Resources Information Center

    Jolly, Jennifer L.; Robinson, Ann

    2014-01-01

    In classic Western movies, the good guy could be frequently identified by his trademark white Stetson hat, whereas the bad guy always wore black. James J. Gallagher wore many hats during his career that spanned over six decades; he too would be known as the "man in the white hat,"--trusted to do the right thing. From 1967 to 1970,…

  20. Role of Transcription Factor HAT1 in Modulating Arabidopsis thaliana Response to Cucumber mosaic virus.

    PubMed

    Zou, Li-Juan; Deng, Xing-Guang; Han, Xue-Ying; Tan, Wen-Rong; Zhu, Li-Jun; Xi, De-Hui; Zhang, Da-Wei; Lin, Hong-Hui

    2016-09-01

    Arabidopsis thaliana homeodomain-leucine zipper protein 1 (HAT1) belongs to the homeodomain-leucine zipper (HD-Zip) family class II that plays important roles in plant growth and development as a transcription factor. To elucidate further the role of HD-Zip II transcription factors in plant defense, the A. thaliana hat1, hat1hat3 and hat1hat2hat3 mutants and HAT1 overexpression plants (HAT1OX) were challenged with Cucumber mosaic virus (CMV). HAT1OX displayed more susceptibility, while loss-of-function mutants of HAT1 exhibited less susceptibility to CMV infection. HAT1 and its close homologs HAT2 and HAT3 function redundantly, as the triple mutant hat1hat2hat3 displayed increased virus resistance compared with the hat1 and hat1hat3 mutants. Furthermore, the induction of the antioxidant system (the activities and expression of enzymatic antioxidants) and the expression of defense-associated genes were down-regulated in HAT1OX but up-regulated in hat1hat2hat3 when compared with Col-0 after CMV infection. Further evidence showed that the involvement of HAT1 in the anti-CMV defense response might be dependent on salicylic acid (SA) but not jasmonic acid (JA). The SA level or expression of SA synthesis-related genes was decreased in HAT1OX but increased in hat1hat2hat3 compared with Col-0 after CMV infection, but there were little difference in JA level or JA synthesis-related gene expression among HAT1OX or defective plants. In addition, HAT1 expression is dependent on SA accumulation. Taken together, our study indicated that HAT1 negatively regulates plant defense responses to CMV. PMID:27328697

  1. TATA-binding protein-free TAF-containing complex (TFTC) and p300 are both required for efficient transcriptional activation.

    PubMed

    Hardy, Sara; Brand, Marjorie; Mittler, Gerhard; Yanagisawa, Jun; Kato, Shigeaki; Meisterernst, Michael; Tora, Làszlò

    2002-09-01

    Initiation of transcription of protein-encoding genes by RNA polymerase II was thought to require transcription factor TFIID, a complex comprising the TATA-binding protein (TBP) and TBP-associated factors (TAFs). In the presence of TBP-free TAF complex (TFTC), initiation of polymerase II transcription can occur in the absence of TFIID. TFTC contains several subunits that have been shown to play the role of transcriptional coactivators, including the GCN5 histone acetyltransferase (HAT), which acetylates histone H3 in a nucleosomal context. Here we analyze the coactivator function of TFTC. We show direct physical interactions between TFTC and the two distinct activation regions (H1 and H2) of the VP16 activation domain, whereas the HAT-containing coactivators, p300/CBP (CREB-binding protein), interact only with the H2 subdomain of VP16. Accordingly, cell transfection experiments demonstrate the requirement of both p300 and TFTC for maximal transcriptional activation by GAL-VP16. In agreement with this finding, we show that in vitro on a chromatinized template human TFTC mediates the transcriptional activity of the VP16 activation domain in concert with p300 and in an acetyl-CoA-dependent manner. Thus, our results suggest that these two HAT-containing co-activators, p300 and TFTC, have complementary rather than redundant roles during the transcriptional activation process. PMID:12107188

  2. FOXP3 interactions with histone acetyltransferase and class II histone deacetylases are required for repression.

    PubMed

    Li, Bin; Samanta, Arabinda; Song, Xiaomin; Iacono, Kathryn T; Bembas, Kathryn; Tao, Ran; Basu, Samik; Riley, James L; Hancock, Wayne W; Shen, Yuan; Saouaf, Sandra J; Greene, Mark I

    2007-03-13

    The forkhead family protein FOXP3 acts as a repressor of transcription and is both an essential and sufficient regulator of the development and function of regulatory T cells. The molecular mechanism by which FOXP3-mediated transcriptional repression occurs remains unclear. Here, we report that transcriptional repression by FOXP3 involves a histone acetyltransferase-deacetylase complex that includes histone acetyltransferase TIP60 (Tat-interactive protein, 60 kDa) and class II histone deacetylases HDAC7 and HDAC9. The N-terminal 106-190 aa of FOXP3 are required for TIP60-FOXP3, HDAC7-FOXP3 association, as well as for the transcriptional repression of FOXP3 via its forkhead domain. FOXP3 can be acetylated in primary human regulatory T cells, and TIP60 promotes FOXP3 acetylation in vivo. Overexpression of TIP60 but not its histone acetyltransferase-deficient mutant promotes, whereas knockdown of endogenous TIP60 relieved, FOXP3-mediated transcriptional repression. A minimum FOXP3 ensemble containing native TIP60 and HDAC7 is necessary for IL-2 production regulation in T cells. Moreover, FOXP3 association with HDAC9 is antagonized by T cell stimulation and can be restored by the protein deacetylation inhibitor trichostatin A, indicating a complex dynamic aspect of T suppressor cell regulation. These findings identify a previously uncharacterized complex-based mechanism by which FOXP3 actively mediates transcriptional repression. PMID:17360565

  3. Targeting of histone acetyltransferase p300 by cyclopentenone prostaglandin Δ(12)-PGJ(2) through covalent binding to Cys(1438).

    PubMed

    Ravindra, Kodihalli C; Narayan, Vivek; Lushington, Gerald H; Peterson, Blake R; Prabhu, K Sandeep

    2012-02-20

    Inhibitors of histone acetyltransferases (HATs) are perceived to treat diseases like cancer, neurodegeneration, and AIDS. On the basis of previous studies, we hypothesized that Cys(1438) in the substrate binding site could be targeted by Δ(12)-prostaglandin J(2) (Δ(12)-PGJ(2)), a cyclopentenone prostaglandin (CyPG) derived from PGD(2). We demonstrate here the ability of CyPGs to inhibit p300 HAT-dependent acetylation of histone H3. A cell-based assay system clearly showed that the α,β-unsaturation in the cyclopentenone ring of Δ(12)-PGJ(2) was crucial for the inhibitory activity, while the 9,10-dihydro-15-deoxy-Δ(12,14)-PGJ(2), which lacks the electrophilic carbon (at carbon 9), was ineffective. Molecular docking studies suggested that Δ(12)-PGJ(2) places the electrophilic carbon in the cyclopentenone ring well within the vicinity of Cys(1438) of p300 to form a covalent Michael adduct. Site-directed mutagenesis of the p300 HAT domain, peptide competition assay involving p300 wild type and mutant peptides, followed by mass spectrometric analysis confirmed the covalent interaction of Δ(12)-PGJ(2) with Cys(1438). Using biotinylated derivatives of Δ(12)-PGJ(2) and 9,10-dihydro-15-deoxy-Δ(12,14)-PGJ(2), we demonstrate the covalent interaction of Δ(12)-PGJ(2) with the p300 HAT domain, but not the latter. In agreement with the in vitro filter binding assay, CyPGs were also found to inhibit H3 histone acetylation in cell-based assays. In addition, Δ(12)-PGJ(2) also inhibited the acetylation of the HIV-1 Tat by recombinant p300 in in vitro assays. This study demonstrates, for the first time, that Δ(12)-PGJ(2) inhibits p300 through Michael addition, where α,β-unsaturated carbonyl function is absolutely required for the inhibitory activity.

  4. Yng1 PHD Finger Binding to H3 Trimethylated at K4 Promotes NuA3 HAT Activity at K14 of H3 and Transcription at a Subset of Targeted ORFs

    PubMed Central

    Taverna, Sean D.; Ilin, Serge; Rogers, Richard S.; Tanny, Jason C.; Lavender, Heather; Li, Haitao; Baker, Lindsey; Boyle, John; Blair, Lauren P.; Chait, Brian T.; Patel, Dinshaw J.; Aitchison, John D.; Tackett, Alan J.; Allis, C. David

    2015-01-01

    Summary Posttranslational histone modifications participate in modulating the structure and function of chromatin. Promoters of transcribed genes are enriched with K4 trimethylation and hyperacetylation on the N-terminal tail of histone H3. Recently, PHD finger proteins, like Yng1 in the NuA3 HAT complex, were shown to interact with H3K4me3, indicating a biochemical link between K4 methylation and hyperacetylation. By using a combination of mass spectrometry, biochemistry, and NMR, we detail the Yng1 PHD-H3K4me3 interaction and the importance of NuA3-dependent acetylation at K14. Furthermore, genome-wide ChIP-Chip analysis demonstrates colocalization of Yng1 and H3K4me3 in vivo. Disrupting the K4me3 binding of Yng1 altered K14ac and transcription at certain genes, thereby demonstrating direct in vivo evidence of sequential trimethyl binding, acetyltransferase activity, and gene regulation by NuA3. Our data support a general mechanism of transcriptional control through which histone acetylation upstream of gene activation is promoted partially through availability of H3K4me3, “read” by binding modules in select subunits. PMID:17157260

  5. Epigenetic change in kidney tumor: downregulation of histone acetyltransferase MYST1 in human renal cell carcinoma

    PubMed Central

    2013-01-01

    Background MYST1 (also known as hMOF), a member of the MYST family of histone acetyltransferases (HATs) as an epigenetic mark of active genes, is mainly responsible for histone H4K16 acetylation in the cells. Recent studies have shown that the abnormal gene expression of hMOF is involved in certain primary cancers. Here we examined the involvement of hMOF expression and histone H4K16 acetylation in primary renal cell carcinoma (RCC). Simultaneously, we investigated the correlation between the expression of hMOF and clear cell RCC (ccRCC) biomarker carbohydrase IX (CA9) in RCC. Materials and methods The frozen RCC tissues and RCC cell lines as materials, the reverse transcription polymerase chain reaction (RT-PCR), western blotting and immunohistochemical staining approaches were used. Results RT-PCR results indicate that hMOF gene expression levels frequently downregulated in 90.5% of patients (19/21) with RCC. The reduction of hMOF protein in both RCC tissues and RCC cell lines is tightly correlated with acetylation of histone H4K16. In addition, overexpression of CA9 was detected in 100% of ccRCC patients (21/21). However, transient transfection of hMOF in ccRCC 786–0 cells did not affect both the gene and protein expression of CA9. Conclusion hMOF as an acetyltransferase of H4K16 might be involved in the pathogenesis of kidney cancer, and this epigenetic changes might be a new CA9-independent RCC diagnostic maker. PMID:23394073

  6. S2HAT: Scalable Spherical Harmonic Transform Library

    NASA Astrophysics Data System (ADS)

    Stompor, Radek

    2011-10-01

    Many problems in astronomy and astrophysics require a computation of the spherical harmonic transforms. This is in particular the case whenever data to be analyzed are distributed over the sphere or a set of corresponding mock data sets has to be generated. In many of those contexts, rapidly improving resolutions of both the data and simulations puts increasingly bigger emphasis on our ability to calculate the transforms quickly and reliably. The scalable spherical harmonic transform library S2HAT consists of a set of flexible, massively parallel, and scalable routines for calculating diverse (scalar, spin-weighted, etc) spherical harmonic transforms for a class of isolatitude sky grids or pixelizations. The library routines implement the standard algorithm with the complexity of O(n^3/2), where n is a number of pixels/grid points on the sphere, however, owing to their efficient parallelization and advanced numerical implementation, they achieve very competitive performance and near perfect scalability. S2HAT is written in Fortran 90 with a C interface. This software is a derivative of the spherical harmonic transforms included in the HEALPix package and is based on both serial and MPI routines of its version 2.01, however, since version 2.5 this software is fully autonomous of HEALPix and can be compiled and run without the HEALPix library.

  7. Biochemical analysis and structure determination of bacterial acetyltransferases responsible for the biosynthesis of UDP-N,N'-diacetylbacillosamine.

    PubMed

    Morrison, Michael J; Imperiali, Barbara

    2013-11-01

    UDP-N,N'-diacetylbacillosamine (UDP-diNAcBac) is a unique carbohydrate produced by a number of bacterial species and has been implicated in pathogenesis. The terminal step in the formation of this important bacterial sugar is catalyzed by an acetyl-CoA (AcCoA)-dependent acetyltransferase in both N- and O-linked protein glycosylation pathways. This bacterial acetyltransferase is a member of the left-handed β-helix family and forms a homotrimer as the functional unit. Whereas previous endeavors have focused on the Campylobacter jejuni acetyltransferase (PglD) from the N-linked glycosylation pathway, structural characterization of the homologous enzymes in the O-linked glycosylation pathways is lacking. Herein, we present the apo-crystal structures of the acetyltransferase domain (ATD) from the bifunctional enzyme PglB (Neisseria gonorrhoeae) and the full-length acetyltransferase WeeI (Acinetobacter baumannii). Additionally, a PglB-ATD structure was solved in complex with AcCoA. Surprisingly, this structure reveals a contrasting binding mechanism for this substrate when compared with the AcCoA-bound PglD structure. A comparison between these findings and the previously solved PglD crystal structures illustrates a dichotomy among N- and O-linked glycosylation pathway enzymes. Based upon these structures, key residues in the UDP-4-amino and AcCoA binding pockets were mutated to determine their effect on binding and catalysis in PglD, PglB-ATD, and WeeI. Last, a phylogenetic analysis of the aforementioned acetyltransferases was employed to illuminate the diversity among N- and O-linked glycosylation pathway enzymes. PMID:24064219

  8. Arylamine N-acetyltransferases: a structural perspective

    PubMed Central

    Zhou, Xiaotong; Ma, Zhiguo; Dong, Dong; Wu, Baojian

    2013-01-01

    Arylamine N-acetyltransferase (NAT) plays an important role in metabolism and detoxification of many compounds including drugs and environmental carcinogens through chemical modification of the amine group with an acetyl group. Recent studies have suggested that NATs are also involved in cancer cell growth and inhibition of the enzymes may be a potential target for cancer chemotherapy. Three-dimensional (3D) structures are available for NATs from both prokaryotes and eukaryotes. These structures provide valuable insights into the acetylation mechanism, features of the active site and the structural determinants that govern substrate/inhibitor-binding specificity. Such insights allow a more precise understanding of the structure–activity relationships for NAT substrates and inhibitors. Furthermore, the structural elucidation of NATs has generated powerful tools in the design of small molecule inhibitors that should alleviate cancer, based on the important role of the enzyme in cancer biology. PMID:23517104

  9. Choline Acetyltransferase-Deficient Mutants of the Nematode CAENORHABDITIS ELEGANS

    PubMed Central

    Rand, James B.; Russell, Richard L.

    1984-01-01

    We have identified five independent allelic mutations, defining the gene cha-1, that result in decreased choline acetyltransferase (ChAT) activity in Caenorhabditis elegans. Four of the mutant alleles, when homozygous, lead to ChAT reductions of>98%, as well as recessive phenotypes of uncoordinated behavior, small size, slow growth and resistance to cholinesterase inhibitors. Animals homozygous for the fifth allele retain approximately 10% of the wild-type enzyme level; purified enzyme from this mutant has altered Km values for both choline and acetyl-CoA and is more thermolabile than the wild-type enzyme. These qualitative alterations, together with gene dosage data, argue that cha-1 is the structural gene for ChAT. cha-1 has been mapped to the left arm of linkage group IV and is within 0.02 map unit of the gene unc-17, mutant alleles of which lead to all of the phenotypes of cha-1 mutants except for the ChAT deficiency. Extensive complementation studies of cha-1 and unc-17 alleles reveal a complex complementation pattern, suggesting that both loci may be part of a single complex gene. PMID:6698395

  10. Long-term surveillance plan for the Mexican Hat disposal site Mexican Hat, Utah

    SciTech Connect

    1997-06-01

    This long-term surveillance plan (LTSP) describes the U.S. Department of Energy`s (DOE) long-term care program for the Uranium Mill Tailings Remedial Action (UMTRA) Project Mexican Hat, Utah, disposal site. This LSTP describes the long-term surveillance program the DOE will implement to ensure the Mexican Hat disposal site performs as designed and is cared for in a manner that protects the public health and safety and the environment. Before each disposal site is licensed for custody and long-term care, the Nuclear Regulatory Commission (NRC) requires the DOE to submit such a site-specific LTSP.

  11. HIV-1 Tat transactivator recruits p300 and CREB-binding protein histone acetyltransferases to the viral promoter

    PubMed Central

    Marzio, Giuseppe; Tyagi, Mudit; Gutierrez, Maria Ines; Giacca, Mauro

    1998-01-01

    In cells infected with HIV type 1 (HIV-1), the integrated viral promoter is present in a chromatin-bound conformation and is transcriptionally silent in the absence of stimulation. The HIV-1 Tat protein binds to a stem-loop structure at the 5′ end of viral mRNA and relieves this inhibition by inducing a remodeling of the nucleosome arrangement downstream of the transcription-initiation site. Here we show that Tat performs this activity by recruiting to the viral long terminal repeat (LTR) the transcriptional coactivator p300 and the closely related CREB-binding protein (CBP), having histone acetyltransferase (HAT) activity. Tat associates with HAT activity in human nuclear extracts and binds to p300 and CBP both in vitro and in vivo. Integrity of the basic domain of Tat is essential for this interaction. By a quantitative chromatin immunoprecipitation assay we show that the delivery of recombinant Tat induces the association of p300 and CBP with the chromosomally integrated LTR promoter. Expression of human p300 in both human and rodent cells increases the levels of Tat transactivation of the integrated LTR. These results reinforce the evidence that p300 and CBP have a pivotal function at both cellular and viral promoters and demonstrate that they also can be recruited by an RNA-targeted activator. Additionally, these findings have important implications for the understanding of the mechanisms of HIV-1 latency and reactivation. PMID:9811832

  12. Histone Acetyltransferase GCN5 Regulates Osteogenic Differentiation of Mesenchymal Stem Cells by Inhibiting NF-κB.

    PubMed

    Zhang, Ping; Liu, Yunsong; Jin, Chanyuan; Zhang, Min; Tang, Fuchou; Zhou, Yongsheng

    2016-02-01

    As the most well-studied histone acetyltransferase (HAT) in yeast and mammals, general control nonderepressible 5 (GCN5) was documented to play essential roles in various developmental processes. However, little is known about its role in osteogenic differentiation of mesenchymal stem cells (MSCs). Here, we detected the critical function of GCN5 in osteogenic commitment of MSCs. In this role, the HAT activity of GCN5 was not required. Mechanistically, GCN5 repressed nuclear factor kappa B (NF-κB)-dependent transcription and inhibited the NF-κB signaling pathway. The impaired osteogenic differentiation by GCN5 knockdown was blocked by inhibition of NF-κB. Most importantly, the expression of GCN5 was decreased significantly in the bone tissue sections of ovariectomized mice or aged mice. Collectively, these results may point to the GCN5-NF-κB pathway as a novel potential molecular target for stem cell mediated regenerative medicine and the treatment of metabolic bone diseases such as osteoporosis.

  13. VizieR Online Data Catalog: Spectroscopy and photometry for HAT-P-50--HAT-P-53 (Hartman+, 2015)

    NASA Astrophysics Data System (ADS)

    Hartman, J. D.; Bhatti, W.; Bakos, G. A.; Bieryla, A.; Kovacs, G.; Latham, D. W.; Csubry, Z.; de Val-Borro, M.; Penev, K.; Buchhave, L. A.; Torres, G.; Howard, A. W.; Marcy, G. W.; Johnson, J. A.; Isaacson, H.; Sato, B.; Boisse, I.; Falco, E.; Everett, M. E.; Szklenar, T.; Fulton, B. J.; Shporer, A.; Kovacs, T.; Hansen, T.; Beky, B.; Noyes, R. W.; Lazar, J.; Papp, I.; Sari, P.

    2016-04-01

    The HATNet network consists of six identical fully automated instruments, with four at Fred Lawrence Whipple Observatory (FLWO) in AZ, and two on the roof of the Submillimeter Array Hangar Building at Mauna Kea Observatory (MKO) in HI. The light-gathering elements of each instrument include an 11cm diameter telephoto lens, a Sloan r filter, and a 4K*4K front-side-illuminated CCD camera. Observations made in 2007 and early 2008 were carried out using a Cousins R filter. The instruments have a field of view of 10.6°*10.6° and a pixel scale of 9"/pixel at the center of an image. Additional time-series photometric measurements were obtained for all four of the systems using Keplercam on the FLWO 1.2m telescope. For HAT-P-50 we also obtained follow-up photometry with the CCD imager on the Byrne Observatory at Sedgwick (BOS) 0.8m telescope, located at Sedgwick Reserve in Santa Ynez Valley, CA, and operated by the Las Cumbres Observatory Global Telescope institute (LCOGT). HAT-P-50 was observed with HAT-10/G316 on 2008 Nov-2009 May, with HAT-5/G364 on 2009 May, with HAT-9/G364 on 2008 Dec-2009 May, with BOS on 2012 Feb 15, on 2012 Feb 21 and on 2012 Apr 08, and with Keplercam on 2012 Feb 18, on 2012 Nov 28, on 2012 Dec 23, on 2013 Jan 14, and on 2013 Jan 17. HAT-P-51 was observed with HAT-6/G164 on 2007 Sep-2008 Feb, with HAT-9/G164 on 2007 Sep-2008 Feb, with HAT-10/G165 on 2010 Sep-2011 Jan, with HAT-5/G165 on 2010 Nov-2011 Feb, with HAT-8/G165 on 2010 Nov-2011 Feb, with HAT-6/G209 on 2010 Nov-2011 Feb, with HAT-9/G209 on 2010 Nov-2011 Feb, with HAT-7/G210 on 2010 Nov-2011 Jan, and with Keplercam on 2011 Oct 21, on 2012 Jan 05, on 2012 Oct 05, on 2012 Oct 26, and on 2012 Nov 12. HAT-P-52 was observed with HAT-5/G212 on 2010 Sep-Nov, with HAT-8/G212 on 2010 Aug-Nov, and with Keplercam on 2010 Dec 23, on 2011 Sep 05, on 2011 Sep 27, on 2011 Nov 21, and on 2012 Jan 07. HAT-P-53 was observed with HAT-6/G164 on 2007 Sep-2008 Feb, with HAT-9/G164 on 2007 Sep-2008 Feb, with

  14. Histone acetyltransferase mediated regulation of FOXP3 acetylation and Treg function

    PubMed Central

    Xiao, Yan; Li, Bin; Zhou, Zhaocai; Hancock, Wayne W.; Zhang, Hongtao; Greene, Mark I.

    2010-01-01

    Regulatory T cells (Tregs) are required for the maintenance of immune homeostasis as first clearly described by Herman Waldmann’s laboratory. Dysfunction of Treg cells also leads to fatal autoimmunity in humans and mice. Conversely, the activation of different classes of Tregs operative systemically and within the cancer microenvironment can suppress host anti-tumor immune responses and promote tumor progression. Therefore, the development of new therapeutic approaches to regulate the activity of Treg cells may have considerable clinical potential. FOXP3 is the key transcriptional regulator of Treg development and function. The activity of FOXP3 is regulated by acetylation, a process catalyzed by distinct types of histone/protein acetyltransferases (HATs) that regulate the functions of many transcription factors, independently of FOXP3, as well as non-histone proteins, in addition to their effects on chromatin accessibility. Interactions between FOXP3 and these enzymes determine the suppressive function of FOXP3. Clearly, small molecules targeting these enzymes are candidates for the regulation of Treg function in vaccines and tumor therapies. PMID:20869864

  15. Engineering assessment of inactive uranium mill tailings: Mexican Hat Site, Mexican Hat, Utah

    SciTech Connect

    1981-09-01

    Ford, Bacon and Davis Utah Inc. has reevaluated the Mexican Hat site in order to revise the March 1977 engineering assessment of the problems resulting from the existence of radioactive uranium mill tailings at Mexican Hat, Utah. This engineering assessment has included the preparation of topographic maps, the performance of core drillings and radiometric measurements sufficient to determine areas and volumes of tailings and radiation exposures of individuals and nearby populations, the investigations of site hydrology and meteorology, and the evaluation and costing of alternative corrective actions. Radon gas released from the 2.2 million tons of tailings at the Mexican Hat site constitutes the most significant environmental impact, although windblown tailings and external gamma radiation also are factors. The four alternative actions presented in this engineering assessment range from millsite decontamination with the addition of 3 m of stabilization cover material to removal of the tailings to remote disposal sites and decontamination of the tailings site. Cost estimates for the four options range from about $15,200,000 for stabilization in place, to about $45,500,000 for disposal at a distance of about 16 mi. Three principal alternatives for the reprocessing of the Mexican Hat tailings were examined: heap leaching; treatment at an existing mill; and reprocessing at a new conventional mill constructed for tailings reprocessing. The cost of the uranium recovered would be about $115/lb of U/sub 3/O/sub 8/ whether by heap leach or conventional plant processes. The spot market price for uranium was $25/lb early in 1981. Reprocessing the Mexican Hat tailings for uranium recovery is not economically attractive under present conditions.

  16. Inhibition of aminoglycoside acetyltransferase resistance enzymes by metal salts.

    PubMed

    Li, Yijia; Green, Keith D; Johnson, Brooke R; Garneau-Tsodikova, Sylvie

    2015-07-01

    Aminoglycosides (AGs) are clinically relevant antibiotics used to treat infections caused by both Gram-negative and Gram-positive bacteria, as well as Mycobacteria. As with all current antibacterial agents, resistance to AGs is an increasing problem. The most common mechanism of resistance to AGs is the presence of AG-modifying enzymes (AMEs) in bacterial cells, with AG acetyltransferases (AACs) being the most prevalent. Recently, it was discovered that Zn(2+) metal ions displayed an inhibitory effect on the resistance enzyme AAC(6')-Ib in Acinetobacter baumannii and Escherichia coli. In this study, we explore a wide array of metal salts (Mg(2+), Cr(3+), Cr(6+), Mn(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), and Au(3+) with different counter ions) and their inhibitory effect on a large repertoire of AACs [AAC(2')-Ic, AAC(3)-Ia, AAC(3)-Ib, AAC(3)-IV, AAC(6')-Ib', AAC(6')-Ie, AAC(6')-IId, and Eis]. In addition, we determine the MIC values for amikacin and tobramycin in combination with a zinc pyrithione complex in clinical isolates of various bacterial strains (two strains of A. baumannii, three of Enterobacter cloacae, and four of Klebsiella pneumoniae) and one representative of each species purchased from the American Type Culture Collection. PMID:25941215

  17. Inhibition of Aminoglycoside Acetyltransferase Resistance Enzymes by Metal Salts

    PubMed Central

    Li, Yijia; Green, Keith D.; Johnson, Brooke R.

    2015-01-01

    Aminoglycosides (AGs) are clinically relevant antibiotics used to treat infections caused by both Gram-negative and Gram-positive bacteria, as well as Mycobacteria. As with all current antibacterial agents, resistance to AGs is an increasing problem. The most common mechanism of resistance to AGs is the presence of AG-modifying enzymes (AMEs) in bacterial cells, with AG acetyltransferases (AACs) being the most prevalent. Recently, it was discovered that Zn2+ metal ions displayed an inhibitory effect on the resistance enzyme AAC(6′)-Ib in Acinetobacter baumannii and Escherichia coli. In this study, we explore a wide array of metal salts (Mg2+, Cr3+, Cr6+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, and Au3+ with different counter ions) and their inhibitory effect on a large repertoire of AACs [AAC(2′)-Ic, AAC(3)-Ia, AAC(3)-Ib, AAC(3)-IV, AAC(6′)-Ib′, AAC(6′)-Ie, AAC(6′)-IId, and Eis]. In addition, we determine the MIC values for amikacin and tobramycin in combination with a zinc pyrithione complex in clinical isolates of various bacterial strains (two strains of A. baumannii, three of Enterobacter cloacae, and four of Klebsiella pneumoniae) and one representative of each species purchased from the American Type Culture Collection. PMID:25941215

  18. Obesity and lipid stress inhibit carnitine acetyltransferase activity[S

    PubMed Central

    Seiler, Sarah E.; Martin, Ola J.; Noland, Robert C.; Slentz, Dorothy H.; DeBalsi, Karen L.; Ilkayeva, Olga R.; An, Jie; Newgard, Christopher B.; Koves, Timothy R.; Muoio, Deborah M.

    2014-01-01

    Carnitine acetyltransferase (CrAT) is a mitochondrial matrix enzyme that catalyzes the interconversion of acetyl-CoA and acetylcarnitine. Emerging evidence suggests that this enzyme functions as a positive regulator of total body glucose tolerance and muscle activity of pyruvate dehydrogenase (PDH), a mitochondrial enzyme complex that promotes glucose oxidation and is feedback inhibited by acetyl-CoA. Here, we used tandem mass spectrometry-based metabolic profiling to identify a negative relationship between CrAT activity and muscle content of lipid intermediates. CrAT specific activity was diminished in muscles from obese and diabetic rodents despite increased protein abundance. This reduction in enzyme activity was accompanied by muscle accumulation of long-chain acylcarnitines (LCACs) and acyl-CoAs and a decline in the acetylcarnitine/acetyl-CoA ratio. In vitro assays demonstrated that palmitoyl-CoA acts as a direct mixed-model inhibitor of CrAT. Similarly, in primary human myocytes grown in culture, nutritional and genetic manipulations that promoted mitochondrial influx of fatty acids resulted in accumulation of LCACs but a pronounced decrease of CrAT-derived short-chain acylcarnitines. These results suggest that lipid-induced antagonism of CrAT might contribute to decreased PDH activity and glucose disposal in the context of obesity and diabetes. PMID:24395925

  19. The phylogenetic utility of acetyltransferase (ARD1) and glutaminyl tRNA synthetase (QtRNA) for reconstructing Cenozoic relationships as exemplified by the large Australian cicada Pauropsalta generic complex.

    PubMed

    Owen, Christopher L; Marshall, David C; Hill, Kathy B R; Simon, Chris

    2015-02-01

    The Pauropsalta generic complex is a large group of cicadas (72 described spp.; >82 undescribed spp.) endemic to Australia. No previous molecular work on deep level relationships within this complex has been conducted, but a recent morphological revision and phylogenetic analysis proposed relationships among the 11 genera. We present here the first comprehensive molecular phylogeny of the complex using five loci (1 mtDNA, 4 nDNA), two of which are from nuclear genes new to cicada systematics. We compare the molecular phylogeny to the morphological phylogeny. We evaluate the phylogenetic informativeness of the new loci to traditional cicada systematics loci to generate a baseline of performance and behavior to aid in gene choice decisions in future systematic and phylogenomic studies. Our maximum likelihood and Bayesian inference phylogenies strongly support the monophyly of most of the newly described genera; however, relationships among genera differ from the morphological phylogeny. A comparison of phylogenetic informativeness among all loci revealed that COI 3rd positions dominate the informativeness profiles relative to all other loci but exhibit some among taxon nucleotide bias. After removing COI 3rd positions, COI 1st positions dominate near the terminals, while the period intron has the most phylogenetic informativeness near the root. Among the nuclear loci, ARD1 and QtRNA have lower phylogenetic informativeness than period intron and elongation factor 1 alpha intron, but the informativeness increases at you move from the tips to the root. The increase in phylogenetic informativeness deeper in the tree suggests these loci may be useful for resolving older relationships.

  20. Epigenetic regulation of proliferation and invasion in hepatocellular carcinoma cells by CBP/p300 histone acetyltransferase activity.

    PubMed

    Inagaki, Yuji; Shiraki, Katsuya; Sugimoto, Kazushi; Yada, Takazumi; Tameda, Masahiko; Ogura, Suguru; Yamamoto, Norihiko; Takei, Yoshiyuki; Ito, Masaaki

    2016-02-01

    Altered epigenetic control of gene expression plays a substantial role in tumor development and progression. Accumulating studies suggest that somatic mutations of CREB binding proteins (CBP)/p300 occur in some cancer cells. CBP/p300 possess histone acetyltransferase (HAT) activity, and are involved in many cellular processes. In this study, we investigated the expression and functional role of CBP/p300 in hepatocellular carcinoma (HCC) using the specific inhibitor C646 of CBP/p300 HAT activity. We examined its effect on several apoptosis-related proteins and invasion-related genes. The results showed that CBP/p300 were highly expressed in HCC tissues and that expression of p300, but not of CBP, was strongly correlated with the malignant character of HCC. C646 inhibited proliferation of HCC cell lines in a dose dependent manner. C646 significantly augmented TRAIL-induced apoptotic sensitivity, which was accompanied by reduced levels of survivin, in HepG2, HLE and SK-HEP1 cells. C646 significantly inhibited invasion of Huh7, HLE and SK-HEP1 cells. The level of matrix metallopeptidase 15 (MMP15) mRNA expression was significantly reduced, whereas the level of laminin alpha 3 (LAMA3) and secreted phosphoprotein 1 (SPP1) mRNA expression was significantly increased in Huh7 cells following exposure to C646. In conclusion, our results suggest that CBP/p300 HAT activity has an important role in malignant transformation, proliferation, apoptotic sensitivity and invasion in HCC. CBP/p300 could be a promising therapeutic target in HCC. PMID:26676548

  1. WASP-12b AND HAT-P-8b are members of triple star systems

    SciTech Connect

    Bechter, Eric B.; Crepp, Justin R.; Matthews, Christopher T.; Ngo, Henry; Knutson, Heather A.; Batygin, Konstantin; Johnson, John Asher; Hinkley, Sasha; Muirhead, Philip S.; Montet, Benjamin T.; Morton, Timothy D.; Howard, Andrew W.

    2014-06-10

    We present high spatial resolution images that demonstrate that WASP-12b and HAT-P-8b orbit the primary stars of hierarchical triple star systems. In each case, two distant companions with colors and brightnesses consistent with M dwarfs co-orbit the hot Jupiter planet host as well as one another. Our adaptive optics images spatially resolve the secondary around WASP-12, previously identified by Bergfors et al. and Crossfield et al. into two distinct sources separated by 84.3 ± 0.6 mas (21 ± 3 AU). We find that the secondary to HAT-P-8, also identified by Bergfors et al., is in fact composed of two stars separated by 65.3 ± 0.5 mas (15 ± 1 AU). Our follow-up observations demonstrate physical association through common proper motion. HAT-P-8 C has a particularly low mass, which we estimate to be 0.18 ± 0.02 M {sub ☉} using photometry. Due to their hierarchy, WASP-12 BC and HAT-P-8 BC will enable the first dynamical mass determination for hot Jupiter stellar companions. These previously well studied planet hosts now represent higher-order multi-star systems with potentially complex dynamics, underscoring the importance of diffraction-limited imaging and providing additional context for understanding the migrant population of transiting hot Jupiters.

  2. WASP-12b and HAT-P-8b are Members of Triple Star Systems

    NASA Astrophysics Data System (ADS)

    Bechter, Eric B.; Crepp, Justin R.; Ngo, Henry; Knutson, Heather A.; Batygin, Konstantin; Hinkley, Sasha; Muirhead, Philip S.; Johnson, John Asher; Howard, Andrew W.; Montet, Benjamin T.; Matthews, Christopher T.; Morton, Timothy D.

    2014-06-01

    We present high spatial resolution images that demonstrate that WASP-12b and HAT-P-8b orbit the primary stars of hierarchical triple star systems. In each case, two distant companions with colors and brightnesses consistent with M dwarfs co-orbit the hot Jupiter planet host as well as one another. Our adaptive optics images spatially resolve the secondary around WASP-12, previously identified by Bergfors et al. and Crossfield et al. into two distinct sources separated by 84.3 ± 0.6 mas (21 ± 3 AU). We find that the secondary to HAT-P-8, also identified by Bergfors et al., is in fact composed of two stars separated by 65.3 ± 0.5 mas (15 ± 1 AU). Our follow-up observations demonstrate physical association through common proper motion. HAT-P-8 C has a particularly low mass, which we estimate to be 0.18 ± 0.02 M ⊙ using photometry. Due to their hierarchy, WASP-12 BC and HAT-P-8 BC will enable the first dynamical mass determination for hot Jupiter stellar companions. These previously well studied planet hosts now represent higher-order multi-star systems with potentially complex dynamics, underscoring the importance of diffraction-limited imaging and providing additional context for understanding the migrant population of transiting hot Jupiters.

  3. WARM SPITZER PHOTOMETRY OF THREE HOT JUPITERS: HAT-P-3b, HAT-P-4b AND HAT-P-12b

    SciTech Connect

    Todorov, Kamen O.; Deming, Drake; Knutson, Heather A.; Burrows, Adam; Fortney, Jonathan J.; Laughlin, Gregory; Lewis, Nikole K.; Cowan, Nicolas B.; Agol, Eric; Desert, Jean-Michel; Sada, Pedro V.; Charbonneau, David; Langton, Jonathan; Showman, Adam P.

    2013-06-20

    We present Warm Spitzer/IRAC secondary eclipse time series photometry of three short-period transiting exoplanets, HAT-P-3b, HAT-P-4b and HAT-P-12b, in both the available 3.6 and 4.5 {mu}m bands. HAT-P-3b and HAT-P-4b are Jupiter-mass objects orbiting an early K and an early G dwarf star, respectively. For HAT-P-3b we find eclipse depths of 0.112%+0.015%-0.030% (3.6 micron) and 0.094%+0.016%-0.009% (4.5 {mu}m). The HAT-P-4b values are 0.142%+0.014%-0.016% (3.6 micron) and 0.122%+0.012%-0.014% 4.5 {mu}m). The two planets' photometry is consistent with inefficient heat redistribution from their day to night sides (and low albedos), but it is inconclusive about possible temperature inversions in their atmospheres. HAT-P-12b is a Saturn-mass planet and is one of the coolest planets ever observed during secondary eclipse, along with the hot Neptune GJ 436b and the hot Saturn WASP-29b. We are able to place 3{sigma} upper limits on the secondary eclipse depth of HAT-P-12b in both wavelengths: <0.042% (3.6 {mu}m) and <0.085% (4.5 {mu}m). We discuss these results in the context of the Spitzer secondary eclipse measurements of GJ 436b and WASP-29b. It is possible that we do not detect the eclipses of HAT-P-12b due to high eccentricity, but find that weak planetary emission in these wavelengths is a more likely explanation. We place 3{sigma} upper limits on the |e cos {omega}| quantity (where e is eccentricity and {omega} is the argument of periapsis) for HAT-P-3b (<0.0081) and HAT-P-4b (<0.0042), based on the secondary eclipse timings.

  4. Warm Spitzer Photometry of Three Hot Jupiters: HAT-P-3b, HAT-P-4b and HAT-P-12b

    NASA Astrophysics Data System (ADS)

    Todorov, Kamen O.; Deming, Drake; Knutson, Heather A.; Burrows, Adam; Fortney, Jonathan J.; Lewis, Nikole K.; Cowan, Nicolas B.; Agol, Eric; Desert, Jean-Michel; Sada, Pedro V.; Charbonneau, David; Laughlin, Gregory; Langton, Jonathan; Showman, Adam P.

    2013-06-01

    We present Warm Spitzer/IRAC secondary eclipse time series photometry of three short-period transiting exoplanets, HAT-P-3b, HAT-P-4b and HAT-P-12b, in both the available 3.6 and 4.5 μm bands. HAT-P-3b and HAT-P-4b are Jupiter-mass objects orbiting an early K and an early G dwarf star, respectively. For HAT-P-3b we find eclipse depths of 0.112%^{+0.015%}_{-0.030%} (3.6 μm) and 0.094%^{+0.016%}_{-0.009%} (4.5 μm). The HAT-P-4b values are 0.142%^{+0.014%}_{-0.016%} (3.6 μm) and 0.122%^{+0.012%}_{-0.014%}(4.5 μm). The two planets' photometry is consistent with inefficient heat redistribution from their day to night sides (and low albedos), but it is inconclusive about possible temperature inversions in their atmospheres. HAT-P-12b is a Saturn-mass planet and is one of the coolest planets ever observed during secondary eclipse, along with the hot Neptune GJ 436b and the hot Saturn WASP-29b. We are able to place 3σ upper limits on the secondary eclipse depth of HAT-P-12b in both wavelengths: <0.042% (3.6 μm) and <0.085% (4.5 μm). We discuss these results in the context of the Spitzer secondary eclipse measurements of GJ 436b and WASP-29b. It is possible that we do not detect the eclipses of HAT-P-12b due to high eccentricity, but find that weak planetary emission in these wavelengths is a more likely explanation. We place 3σ upper limits on the |e cos ω| quantity (where e is eccentricity and ω is the argument of periapsis) for HAT-P-3b (<0.0081) and HAT-P-4b (<0.0042), based on the secondary eclipse timings.

  5. N-Alpha-Acetyltransferases and Regulation of CFTR Expression.

    PubMed

    Vetter, Ali J; Karamyshev, Andrey L; Patrick, Anna E; Hudson, Henry; Thomas, Philip J

    2016-01-01

    The majority of cystic fibrosis (CF)-causing mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) lead to the misfolding, mistrafficking, and degradation of the mutant protein. Inhibition of degradation does not effectively increase the amount of trafficking competent CFTR, but typically leads to increased ER retention of misfolded forms. Thus, the initial off pathway steps occur early in the processing of the protein. To identify proteins that interact with these early forms of CFTR, in vitro crosslink experiments identified cotranslational partners of the nascent chain of the severe misfolded mutant, G85E CFTR. The mutant preferentially interacts with a subunit of an N-alpha-acetyltransferase A. Based on recent reports that acetylation of the N-termini of some N-end rule substrates control their ubiquitination and subsequent degradation, a potential role for this modification in regulation of CFTR expression was assessed. Knockdown experiments identified two complexes, which affect G85E CFTR proteins levels, NatA and NatB. Effects of the knockdowns on mRNA levels, translation rates, and degradation rates established that the two complexes regulate G85E CFTR through two separate mechanisms. NatA acts indirectly by regulating transcription levels and NatB acts through a previously identified, but incompletely understood posttranslational mechanism. This regulation did not effect trafficking of G85E CFTR, which remains retained in the ER, nor did it alter the degradation rate of CFTR. A mutation predicted to inhibit N-terminal acetylation of CFTR, Q2P, was without effect, suggesting neither system acts directly on CFTR. These results contradict the prediction that N-terminal acetylation of CFTR determines its fitness as a proteasome substrate, but rather NatB plays a role in the conformational maturation of CFTR in the ER through actions on an unidentified protein. PMID:27182737

  6. N-Alpha-Acetyltransferases and Regulation of CFTR Expression.

    PubMed

    Vetter, Ali J; Karamyshev, Andrey L; Patrick, Anna E; Hudson, Henry; Thomas, Philip J

    2016-01-01

    The majority of cystic fibrosis (CF)-causing mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) lead to the misfolding, mistrafficking, and degradation of the mutant protein. Inhibition of degradation does not effectively increase the amount of trafficking competent CFTR, but typically leads to increased ER retention of misfolded forms. Thus, the initial off pathway steps occur early in the processing of the protein. To identify proteins that interact with these early forms of CFTR, in vitro crosslink experiments identified cotranslational partners of the nascent chain of the severe misfolded mutant, G85E CFTR. The mutant preferentially interacts with a subunit of an N-alpha-acetyltransferase A. Based on recent reports that acetylation of the N-termini of some N-end rule substrates control their ubiquitination and subsequent degradation, a potential role for this modification in regulation of CFTR expression was assessed. Knockdown experiments identified two complexes, which affect G85E CFTR proteins levels, NatA and NatB. Effects of the knockdowns on mRNA levels, translation rates, and degradation rates established that the two complexes regulate G85E CFTR through two separate mechanisms. NatA acts indirectly by regulating transcription levels and NatB acts through a previously identified, but incompletely understood posttranslational mechanism. This regulation did not effect trafficking of G85E CFTR, which remains retained in the ER, nor did it alter the degradation rate of CFTR. A mutation predicted to inhibit N-terminal acetylation of CFTR, Q2P, was without effect, suggesting neither system acts directly on CFTR. These results contradict the prediction that N-terminal acetylation of CFTR determines its fitness as a proteasome substrate, but rather NatB plays a role in the conformational maturation of CFTR in the ER through actions on an unidentified protein.

  7. HATS-15b and HATS-16b: Two Massive Planets Transiting Old G Dwarf Stars

    NASA Astrophysics Data System (ADS)

    Ciceri, S.; Mancini, L.; Henning, T.; Bakos, G.; Penev, K.; Brahm, R.; Zhou, G.; Hartman, J. D.; Bayliss, D.; Jordán, A.; Csubry, Z.; de Val-Borro, M.; Bhatti, W.; Rabus, M.; Espinoza, N.; Suc, V.; Schmidt, B.; Noyes, R.; Howard, A. W.; Fulton, B. J.; Isaacson, H.; Marcy, G. W.; Butler, R. P.; Arriagada, P.; Crane, J. D.; Shectman, S.; Thompson, I.; Tan, T. G.; Lázár, J.; Papp, I.; Sari, P.

    2016-07-01

    We report the discovery of HATS-15 b and HATS-16 b, two massive transiting extrasolar planets orbiting evolved (∼10 Gyr) main-sequence stars. The planet HATS-15 b, which is hosted by a G9 V star (V=14.8 mag), is a hot Jupiter with mass of 2.17\\quad +/- \\quad 0.15 {M}{{J}} and radius of 1.105\\quad +/- \\quad 0.040 {R}{{J}}, and it completes its orbit in about 1.7 days. HATS-16 b is a very massive hot Jupiter with mass of 3.27\\quad +/- \\quad 0.19 {M}{{J}} and radius of 1.30\\quad +/- \\quad 0.15 {R}{{J}}; it orbits around its G3 V parent star (V=13.8 mag) in ∼2.7 days. HATS-16 is slightly active and shows a periodic photometric modulation, implying a rotational period of 12 days, which is unexpectedly short given its isochronal age. This fast rotation might be the result of the tidal interaction between the star and its planet. The HATSouth network is operated by a collaboration consisting of Princeton University (PU), the Max Planck Institute für Astronomie (MPIA), the Australian National University (ANU), and the Pontificia Universidad Católica de Chile (PUC). The station at Las Campanas Observatory (LCO) of the Carnegie Institute is operated by PU in conjunction with PUC, the station at the High Energy Spectroscopic Survey (H.E.S.S.) site is operated in conjunction with MPIA, and the station at Siding Spring Observatory (SSO) is operated jointly with ANU. Based in part on observations performed at the ESO La Silla Observatory in Chile, with the Coralie and FEROS spectrographs mounted on the Euler-Swiss and MPG 2.2 m telescopes, respectively. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. Based in part on data collected at Keck Telescope. Observations obtained with facilities of the Las Cumbres Observatory Global Telescope are used in this paper.

  8. FOXP3 interactions with histone acetyltransferase and class II histone deacetylases are required for repression

    PubMed Central

    Li, Bin; Samanta, Arabinda; Song, Xiaomin; Iacono, Kathryn T.; Bembas, Kathryn; Tao, Ran; Basu, Samik; Riley, James L.; Hancock, Wayne W.; Shen, Yuan; Saouaf, Sandra J.; Greene, Mark I.

    2007-01-01

    The forkhead family protein FOXP3 acts as a repressor of transcription and is both an essential and sufficient regulator of the development and function of regulatory T cells. The molecular mechanism by which FOXP3-mediated transcriptional repression occurs remains unclear. Here, we report that transcriptional repression by FOXP3 involves a histone acetyltransferase–deacetylase complex that includes histone acetyltransferase TIP60 (Tat-interactive protein, 60 kDa) and class II histone deacetylases HDAC7 and HDAC9. The N-terminal 106–190 aa of FOXP3 are required for TIP60–FOXP3, HDAC7–FOXP3 association, as well as for the transcriptional repression of FOXP3 via its forkhead domain. FOXP3 can be acetylated in primary human regulatory T cells, and TIP60 promotes FOXP3 acetylation in vivo. Overexpression of TIP60 but not its histone acetyltransferase-deficient mutant promotes, whereas knockdown of endogenous TIP60 relieved, FOXP3-mediated transcriptional repression. A minimum FOXP3 ensemble containing native TIP60 and HDAC7 is necessary for IL-2 production regulation in T cells. Moreover, FOXP3 association with HDAC9 is antagonized by T cell stimulation and can be restored by the protein deacetylation inhibitor trichostatin A, indicating a complex dynamic aspect of T suppressor cell regulation. These findings identify a previously uncharacterized complex-based mechanism by which FOXP3 actively mediates transcriptional repression. PMID:17360565

  9. Spitzer Secondary Eclipses of HAT-P-13b

    NASA Astrophysics Data System (ADS)

    Hardy, Ryan A.; Harrington, J.; Hardin, M. R.; Madhusudhan, N.; Cubillos, P.; Blecic, J.; Bakos, G.; Hartman, J. D.

    2013-10-01

    HAT-P-13 b is a transiting hot Jupiter with a slightly eccentric orbit (e = 0.010) inhabiting a two-planet system. The two-planet arrangement provides an opportunity to probe the interior structure of HAT-P-13b. Under equilibrium-tide theory and confirmation that the apsides of planets b and c are in alignment, a measurement of the planet's eccentricity can be related to the planet's tidal Love number k2, which describes the central condensation of the planet's mass and its deformation under tidal effects. A measurement of k2 could constrain interior models of HAT-P-13b. HAT-P-13b's orbit is configured favorably for refinement of the eccentricity by secondary eclipse timing observations, which provide direct measurements of ecosω. In 2010, Spitzer observed two secondary eclipses of HAT-P-13b in the 3.6- and 4.5-μm IRAC bandpasses. We present secondary eclipse times and depths; joint models of the HAT-P-13 system that incorporate transit photometry and radial velocity data; and constraints on the atmospheric chemistry of HAT-P-13b that suggest solar-abundance composition without a thermal inversion. Spitzer is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA, which provided support for this work. This work was supported in part by NASA Planetary Atmospheres Grant NNX13AF38G.

  10. Two N-Terminal Acetyltransferases Antagonistically Regulate the Stability of a Nod-Like Receptor in Arabidopsis

    PubMed Central

    Li, Lin; Gannon, Patrick; Linster, Eric; Huber, Monika; Kapos, Paul; Bienvenut, Willy; Giglione, Carmela; Zhang, Yuelin; Chen, She

    2015-01-01

    Nod-like receptors (NLRs) serve as immune receptors in plants and animals. The stability of NLRs is tightly regulated, though its mechanism is not well understood. Here, we show the crucial impact of N-terminal acetylation on the turnover of one plant NLR, Suppressor of NPR1, Constitutive 1 (SNC1), in Arabidopsis thaliana. Genetic and biochemical analyses of SNC1 uncovered its multilayered regulation by different N-terminal acetyltransferase (Nat) complexes. SNC1 exhibits a few distinct N-terminal isoforms generated through alternative initiation and N-terminal acetylation. Its first Met is acetylated by N-terminal acetyltransferase complex A (NatA), while the second Met is acetylated by N-terminal acetyltransferase complex B (NatB). Unexpectedly, the NatA-mediated acetylation serves as a degradation signal, while NatB-mediated acetylation stabilizes the NLR protein, thus revealing antagonistic N-terminal acetylation of a single protein substrate. Moreover, NatA also contributes to the turnover of another NLR, RESISTANCE TO P. syringae pv maculicola 1. The intricate regulation of protein stability by Nats is speculated to provide flexibility for the target protein in maintaining its homeostasis. PMID:25966763

  11. Chemoproteomic Profiling of Lysine Acetyltransferases Highlights an Expanded Landscape of Catalytic Acetylation

    PubMed Central

    2015-01-01

    Lysine acetyltransferases (KATs) play a critical role in the regulation of gene expression, metabolism, and other key cellular functions. One shortcoming of traditional KAT assays is their inability to study KAT activity in complex settings, a limitation that hinders efforts at KAT discovery, characterization, and inhibitor development. To address this challenge, here we describe a suite of cofactor-based affinity probes capable of profiling KAT activity in biological contexts. Conversion of KAT bisubstrate inhibitors to clickable photoaffinity probes enables the selective covalent labeling of three phylogenetically distinct families of KAT enzymes. Cofactor-based affinity probes report on KAT activity in cell lysates, where KATs exist as multiprotein complexes. Chemical affinity purification and unbiased LC–MS/MS profiling highlights an expanded landscape of orphan lysine acetyltransferases present in the human genome and provides insight into the global selectivity and sensitivity of CoA-based proteomic probes that will guide future applications. Chemoproteomic profiling provides a powerful method to study the molecular interactions of KATs in native contexts and will aid investigations into the role of KATs in cell state and disease. PMID:24836640

  12. Erythromycin induces expression of the chloramphenicol acetyltransferase gene cat-86.

    PubMed Central

    Rogers, E J; Lovett, P S

    1990-01-01

    The plasmid gene cat-86 specifies chloramphenicol-inducible chloramphenicol acetyltransferase in Bacillus subtilis. This gene, like the erythromycin-inducible erm genes, is regulated by translational attenuation. Here we show that cat-86 is also inducibly regulated by erythromycin. cat-86 does not confer resistance to erythromycin. PMID:2115875

  13. Long-term surveillance plan for the Mexican Hat disposal site Mexican Hat, Utah

    SciTech Connect

    1997-05-01

    This long-term surveillance plan (LTSP) describes the U.S. Department of Energy`s (DOE) long-term care program for the Uranium Mill Tailings Remedial Action (UMTRA) Project Mexican Hat, Utah, disposal site. The U.S. Nuclear Regulatory Commission (NRC) has developed regulations for the issuance of a general license for the custody and long-term care of UMTRA Project disposal sites in 10 CFR Part 40. The purpose of this general license is to ensure that the UMTRA Project disposal sites will be cared for in a manner that protects the public health and safety and the environment. Before each disposal site is licensed, the NRC requires the DOE to submit a site-specific LTSP. The DOE prepared this LTSP to meet this requirement for the Mexican Hat disposal site. The general license becomes effective when the NRC concurs with the DOE`s determination of completion of remedial action for the disposal site and the NRC formally accepts this LTSP. This LTSP describes the long-term surveillance program the DOE will implement to ensure that the Mexican Hat disposal site performs as designed. The program is based on two distinct types of activities: (1) site inspections to identify potential threats to disposal cell integrity, and (2) monitoring of selected seeps to observe changes in flow rates and water quality. The LTSP is based on the UMTRA Project long-term surveillance program guidance and meets the requirements of 10 CFR {section}40.27(b) and 40 CFR {section}192.03. 18 refs., 6 figs., 1 tab.

  14. Long-term surveillance plan for the Mexican Hat disposal site, Mexican Hat, Utah

    SciTech Connect

    1996-01-01

    This plan describes the long-term surveillance activities for the Uranium Mill Tailings Remedial Action (UMTRA) Project disposal site at Mexican Hat, Utah. The US Department of Energy (DOE) will carry out these activities to ensure that the disposal site continues to function as designed. This long-term surveillance plan (LTSP) was prepared as a requirement for acceptance under the US Nuclear Regulatory Commission (NRC) general license for custody and long-term care of residual radioactive material (RRM). This LTSPC documents the land ownership interests and details how the long-term care of the disposal site will be accomplished.

  15. The histone acetyltransferase PsGcn5 mediates oxidative stress responses and is required for full virulence of Phytophthora sojae.

    PubMed

    Zhao, Wei; Wang, Tao; Liu, Shusen; Chen, Qingqing; Qi, Rende

    2015-10-01

    In eukaryotic organisms, histone acetyltransferase complexes are coactivators that are important for transcriptional activation by modifying chromatin. In this study, a gene (PsGcn5) from Phytophthora sojae encoding a histone acetyltransferase was identified as a homolog of one component of the histone acetyltransferase complex from yeasts to mammals. PsGcn5 was constitutively expressed in each stage tested, but had a slightly higher expression in sporulating hyphae and 3 h after infection. PsGcn5-silenced mutants were generated using polyethylene glycol-mediated protoplast stable transformation. These mutants had normal development, but compared to wild type strains they had higher sensitivity to hydrogen peroxide (H2O2) and significantly reduced virulence in soybean. Diaminobenzidine staining revealed an accumulation of H2O2 around the infection sites of PsGcn5-silenced mutants but not for wild type strains. Inhibition of the plant NADPH oxidase by diphenyleneiodonium prevented host-derived H2O2 accumulation in soybean cells and restored infectious hyphal growth of the mutants. Thus, we concluded that PsGcn5 is important for growth under conditions of oxidative stress and contributes to the full virulence of P. sojae by suppressing the host-derived reactive oxygen species.

  16. Absence of N-terminal acetyltransferase diversification during evolution of eukaryotic organisms.

    PubMed

    Rathore, Om Singh; Faustino, Alexandra; Prudêncio, Pedro; Van Damme, Petra; Cox, Cymon J; Martinho, Rui Gonçalo

    2016-02-10

    Protein N-terminal acetylation is an ancient and ubiquitous co-translational modification catalyzed by a highly conserved family of N-terminal acetyltransferases (NATs). Prokaryotes have at least 3 NATs, whereas humans have six distinct but highly conserved NATs, suggesting an increase in regulatory complexity of this modification during eukaryotic evolution. Despite this, and against our initial expectations, we determined that NAT diversification did not occur in the eukaryotes, as all six major human NATs were most likely present in the Last Eukaryotic Common Ancestor (LECA). Furthermore, we also observed that some NATs were actually secondarily lost during evolution of major eukaryotic lineages; therefore, the increased complexity of the higher eukaryotic proteome occurred without a concomitant diversification of NAT complexes.

  17. Absence of N-terminal acetyltransferase diversification during evolution of eukaryotic organisms

    PubMed Central

    Rathore, Om Singh; Faustino, Alexandra; Prudêncio, Pedro; Van Damme, Petra; Cox, Cymon J.; Martinho, Rui Gonçalo

    2016-01-01

    Protein N-terminal acetylation is an ancient and ubiquitous co-translational modification catalyzed by a highly conserved family of N-terminal acetyltransferases (NATs). Prokaryotes have at least 3 NATs, whereas humans have six distinct but highly conserved NATs, suggesting an increase in regulatory complexity of this modification during eukaryotic evolution. Despite this, and against our initial expectations, we determined that NAT diversification did not occur in the eukaryotes, as all six major human NATs were most likely present in the Last Eukaryotic Common Ancestor (LECA). Furthermore, we also observed that some NATs were actually secondarily lost during evolution of major eukaryotic lineages; therefore, the increased complexity of the higher eukaryotic proteome occurred without a concomitant diversification of NAT complexes. PMID:26861501

  18. High Hats, Swiss Cheese, and Fluorescent Lighting?

    SciTech Connect

    McCullough, Jeffrey J.; Gordon, Kelly L.

    2002-08-30

    For DOE, PNNL is conducting a competitive procurement to promote market introduction of new residential recessed downlights (also known as ''recessed cans'' or ''high hats'') that are airtight, rated for insulated ceilings, and hard-wired for CFLs. This paper discusses the potential energy savings of new high-efficiency downlights, and the results of product testing to date. Recessed downlights are the most popular residential lighting fixtures in the United States, with 21.7 million fixtures sold in 2000. An estimated 350 million are currently installed in American homes. Recessed cans are relatively inexpensive, and provide an unobtrusive, directed source of light for kitchens, hallways, and living rooms. Recessed cans are energy-intensive in three ways. First, virtually all recessed cans currently installed in the residential sector use incandescent light sources, typically reflector-type lamps drawing 65-150 watts. Second, heat from incandescent lamps adds to air-conditioning loads. Third, most installed recessed cans are not airtight, so they allow conditioned air to escape from the living area into unconditioned spaces such as attics. Addressing both lighting energy use and air leakage in recessed cans has proven challenging. Lighting energy efficiency is greatly improved by using CFLs. Air leakage can be addressed by making fixtures airtight. But when CFLs are used in an airtight recessed can, heat generated by the lamp and ballast is trapped within the fixture. Excessive heat causes reduced light output and shorter lifespan of the CFL. The procurement was designed to overcome these technical challenges and make new products available in the marketplace.

  19. Histone-modifying enzymes, histone modifications and histone chaperones in nucleosome assembly: Lessons learned from Rtt109 histone acetyltransferases.

    PubMed

    Dahlin, Jayme L; Chen, Xiaoyue; Walters, Michael A; Zhang, Zhiguo

    2015-01-01

    During DNA replication, nucleosomes ahead of replication forks are disassembled to accommodate replication machinery. Following DNA replication, nucleosomes are then reassembled onto replicated DNA using both parental and newly synthesized histones. This process, termed DNA replication-coupled nucleosome assembly (RCNA), is critical for maintaining genome integrity and for the propagation of epigenetic information, dysfunctions of which have been implicated in cancers and aging. In recent years, it has been shown that RCNA is carefully orchestrated by a series of histone modifications, histone chaperones and histone-modifying enzymes. Interestingly, many features of RCNA are also found in processes involving DNA replication-independent nucleosome assembly like histone exchange and gene transcription. In yeast, histone H3 lysine K56 acetylation (H3K56ac) is found in newly synthesized histone H3 and is critical for proper nucleosome assembly and for maintaining genomic stability. The histone acetyltransferase (HAT) regulator of Ty1 transposition 109 (Rtt109) is the sole enzyme responsible for H3K56ac in yeast. Much research has centered on this particular histone modification and histone-modifying enzyme. This Critical Review summarizes much of our current understanding of nucleosome assembly and highlights many important insights learned from studying Rtt109 HATs in fungi. We highlight some seminal features in nucleosome assembly conserved in mammalian systems and describe some of the lingering questions in the field. Further studying fungal and mammalian chromatin assembly may have important public health implications, including deeper understandings of human cancers and aging as well as the pursuit of novel anti-fungal therapies.

  20. Epigenetic chromatin modifiers in barley: III. Isolation and characterization of the barley GNAT-MYST family of histone acetyltransferases and responses to exogenous ABA.

    PubMed

    Papaefthimiou, Dimitra; Likotrafiti, Eleni; Kapazoglou, Aliki; Bladenopoulos, Konstantinos; Tsaftaris, Athanasios

    2010-01-01

    Histone acetylation is a vital mechanism for the activation of chromatin and the corresponding expression of genes competing the action of histone deacetylation and leading to chromatin inactivation. Histone acetyltransferases (HATs) comprise a superfamily including the GNAT/MYST, CBP and TF(II)250 families. Histone acetyltransferases have been well studied in Arabidopsis but information from agronomically important crops is limited. In the present work three full-length sequences encoding members of the GNAT/MYST family, namely HvMYST, HvELP3 and HvGCN5, respectively, were isolated and characterized from barley (Hordeum vulgare L.), a crop of high economic value. Expression analysis of the barley GNAT/MYST genes revealed significant quantitative differences in different seed developmental stages and between cultivars with varying seed size and weight, suggesting an association of these genes with barley seed development. Furthermore, all three HvGNAT/MYST genes were inducible by the stress-related phytohormone abscisic acid (ABA) involved in seed maturation, dormancy and germination, implying a possible regulation of these genes by ABA, during barley seed development, germination and stress response. PMID:20117010

  1. Structure and Functional Diversity of GCN5-Related N-Acetyltransferases (GNAT)

    PubMed Central

    Salah Ud-Din, Abu Iftiaf Md; Tikhomirova, Alexandra; Roujeinikova, Anna

    2016-01-01

    General control non-repressible 5 (GCN5)-related N-acetyltransferases (GNAT) catalyze the transfer of an acyl moiety from acyl coenzyme A (acyl-CoA) to a diverse group of substrates and are widely distributed in all domains of life. This review of the currently available data acquired on GNAT enzymes by a combination of structural, mutagenesis and kinetic methods summarizes the key similarities and differences between several distinctly different families within the GNAT superfamily, with an emphasis on the mechanistic insights obtained from the analysis of the complexes with substrates or inhibitors. It discusses the structural basis for the common acetyltransferase mechanism, outlines the factors important for the substrate recognition, and describes the mechanism of action of inhibitors of these enzymes. It is anticipated that understanding of the structural basis behind the reaction and substrate specificity of the enzymes from this superfamily can be exploited in the development of novel therapeutics to treat human diseases and combat emerging multidrug-resistant microbial infections. PMID:27367672

  2. RNA helicase module in an acetyltransferase that modifies a specific tRNA anticodon

    PubMed Central

    Chimnaronk, Sarin; Suzuki, Tateki; Manita, Tetsuhiro; Ikeuchi, Yoshiho; Yao, Min; Suzuki, Tsutomu; Tanaka, Isao

    2009-01-01

    Post-transcriptional RNA modifications in the anticodon of transfer RNAs frequently contribute to the high fidelity of protein synthesis. In eubacteria, two genome-encoded transfer RNA (tRNA) species bear the same CAU sequence as the anticodons, which are differentiated by modified cytidines at the wobble positions. The elongator tRNAMet accepts an acetyl moiety at the wobble base to form N4-acetylcytidine (ac4C): an inherent modification ensures precise decoding of the AUG codon by strengthening C−G base-pair interaction and concurrently preventing misreading of the near cognate AUA codon. We have determined the crystal structure of tRNAMet cytidine acetyltransferase (TmcA) from Escherichia coli complexed with two natural ligands, acetyl-CoA and ADP, at 2.35 Å resolution. The structure unexpectedly reveals an idiosyncratic RNA helicase module fused with a GCN5-related N-acetyltransferase (GNAT) fold, which intimately cross-interact. Taken together with the biochemical evidence, we further unravelled the function of acetyl-CoA as an enzyme-activating switch, and propose that an RNA helicase motor driven by ATP hydrolysis is used to deliver the wobble base to the active centre of the GNAT domain. PMID:19322199

  3. Structure of a pathogen effector reveals the enzymatic mechanism of a novel acetyltransferase family.

    PubMed

    Zhang, Zhi-Min; Ma, Ka-Wai; Yuan, Shuguang; Luo, Youfu; Jiang, Shushu; Hawara, Eva; Pan, Songqin; Ma, Wenbo; Song, Jikui

    2016-09-01

    Effectors secreted by the type III secretion system are essential for bacterial pathogenesis. Members of the Yersinia outer-protein J (YopJ) family of effectors found in diverse plant and animal pathogens depend on a protease-like catalytic triad to acetylate host proteins and produce virulence. However, the structural basis for this noncanonical acetyltransferase activity remains unknown. Here, we report the crystal structures of the YopJ effector HopZ1a, produced by the phytopathogen Pseudomonas syringae, in complex with the eukaryote-specific cofactor inositol hexakisphosphate (IP6) and/or coenzyme A (CoA). Structural, computational and functional characterizations reveal a catalytic core with a fold resembling that of ubiquitin-like cysteine proteases and an acetyl-CoA-binding pocket formed after IP6-induced structural rearrangements. Modeling-guided mutagenesis further identified key IP6-interacting residues of Salmonella effector AvrA that are required for acetylating its substrate. Our study reveals the structural basis of a novel class of acetyltransferases and the conserved allosteric regulation of YopJ effectors by IP6. PMID:27525589

  4. Biophysical analysis of the putative acetyltransferase SACOL2570 from methicillin-resistant Staphylococcus aureus

    PubMed Central

    Luo, Hai-Bin; Knapik, Aleksandra A.; Petkowski, Janusz J.; Demas, Matthew; Shumilin, Igor A.; Zheng, Heping; Chruszcz, Maksymilian

    2013-01-01

    Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of a myriad of insidious and intractable infections in humans, especially in patients with compromised immune systems and children. Here, we report the apo- and CoA-bound crystal structures of a member of the galactoside acetyltransferase superfamily from methicillin-resistant S. aureus SACOL2570 which was recently shown to be down regulated in S. aureus grown in the presence of fusidic acid, an antibiotic used to treat MRSA infections. SACOL2570 forms a homotrimerin solution, as confirmed by small-angle X-ray scattering and dynamic light scattering. The protein subunit consists of an N-terminal alpha-helical domain connected to a C-terminal LβH domain. CoA binds in the active site formed by the residues from adjacent LβH domains. After determination of CoA-bound structure, molecular dynamics simulations were performed to model the binding of AcCoA. Binding of both AcCoA and CoA to SACOL2570 was verified by isothermal titration calorimetry. SACOL2570 most likely acts as an acetyltransferase, using AcCoA as an acetyl group donor and an as-yet-undetermined chemical moiety as an acceptor. SACOL2570 was recently used as a scaffold for mutations that lead the generation of cage-like assemblies, and has the potential to be used for the generation of more complex nanostructures. PMID:23963951

  5. Development of a helmet/helmet-display-unit alignment tool (HAT) for the Apache helmet and display unit

    NASA Astrophysics Data System (ADS)

    McLean, William; Statz, Jonathan; Estes, Victor; Booms, Shawn; Martin, John S.; Harding, Thomas

    2015-05-01

    Project Manager (PM) Apache Block III contacted the U.S. Army Aeromedical Research Laboratory (USAARL), Fort Rucker, Alabama, requesting assistance to evaluate and find solutions to a government-developed Helmet Display Unit (HDU) device called the Mock HDU for helmet alignment of the Apache Advanced Integrated Helmet (AAIH). The AAIH is a modified Head Gear Unit No. 56 for Personnel (HGU-56/P) to replace the current Integrated Helmet and Sighting System (IHADSS). The current flashlight-based HDU simulator for helmet/HDU alignment was no longer in production or available. Proper helmet/HDU alignment is critical to position the right eye in the small HDU eye box to obtain image alignment and full field of view (FOV). The initial approach of the PM to developing a helmet/HDU fitting device (Mock HDU) was to duplicate the optical characteristics of the current tactical HDU using less complex optics. However, the results produced questionable alignment, FOV, and distortion issues, with cost and development time overruns. After evaluating the Mock HDU, USAARL proposed a cost effective, less complex optical design called the Helmet/HDU Alignment Tool (HAT). This paper will show the development, components, and evaluations of the HAT compared to the current flashlight HDU simulator device. The laboratory evaluations included FOV measurements and alignment accuracies compared to tactical HDUs. The Apache helmet fitter technicians and Apache pilots compared the HAT to the current flashlight based HDU and ranked the HAT superior.

  6. Structure of Arabidopsis thaliana At1g77540 Protein, a Minimal Acetyltransferase from the COG2388 Family †,‡

    PubMed Central

    Tyler, Robert C.; Bitto, Eduard; Berndsen, Christopher E.; Bingman, Craig A.; Singh, Shanteri; Lee, Min S.; Wesenberg, Gary E.; Denu, John M.; Phillips, George N.; Markley, John L.

    2008-01-01

    We describe X-ray crystal and NMR solution structures of the protein coded for by Arabidopsis thaliana gene At1g77540.1 (At1g77540). The crystal structure was determined to 1.15 Å with an R factor of 14.9% (Rfree = 17.0%) by multiple-wavelength anomalous diffraction using sodium bromide derivatized crystals. The ensemble of NMR conformers was determined with protein samples labeled with 15N and 13C+15N. The X-ray structure and NMR ensemble were closely similar with r.m.s.d 1.4 Å for residues 8–93. At1g77540 was found to adopt a fold similar to that of GCN5-related N-acetyltransferases. Enzymatic activity assays established that At1g77540 possesses weak acetyltransferase activity against histones H3 and H4. Chemical shift perturbations observed in 15N-HSQC spectra upon the addition of CoA indicated that the cofactor binds and identified its binding site. The molecular details of this interaction were further elucidated by solving the X-ray structure of the At1g77540–CoA complex. This work establishes that the domain family COG2388 represents a novel class of acetyltransferase and provides insight into possible mechanistic roles of the conserved Cys76 and His41 residues of this family. PMID:17128971

  7. HATS-25b through HATS-30b: A Half–dozen New Inflated Transiting Hot Jupiters from the HATSouth Survey

    NASA Astrophysics Data System (ADS)

    Espinoza, N.; Bayliss, D.; Hartman, J. D.; Bakos, G. Á.; Jordán, A.; Zhou, G.; Mancini, L.; Brahm, R.; Ciceri, S.; Bhatti, W.; Csubry, Z.; Rabus, M.; Penev, K.; Bento, J.; de Val-Borro, M.; Henning, T.; Schmidt, B.; Suc, V.; Wright, D. J.; Tinney, C. G.; Tan, T. G.; Noyes, R.

    2016-10-01

    We report six new inflated hot Jupiters (HATS-25b through HATS-30b) discovered using the HATSouth global network of automated telescopes. The planets orbit stars with V magnitudes in the range of ∼12–14 and have masses in the largely populated 0.5{M}J{--}0.7{M}J region of parameter space but span a wide variety of radii, from 1.17{R}J to 1.75{R}J. HATS-25b, HATS-28b, HATS-29b, and HATS-30b are typical inflated hot Jupiters ({R}p=1.17{--}1.26{R}J) orbiting G–type stars in short period (P = 3.2-4.6 days) orbits. However, HATS-26b ({R}p=1.75{R}J, P=3.3024 days) and HATS-27b ({R}p=1.50{R}J, P=4.6370 days) stand out as highly inflated planets orbiting slightly evolved F stars just after and in the turn–off points, respectively, which are among the least dense hot Jupiters, with densities of 0.153 {{g}} {{cm}}-3 and 0.180 {{g}} {{cm}}-3, respectively. All the presented exoplanets but HATS-27b are good targets for future atmospheric characterization studies, while HATS-27b is a prime target for Rossiter—McLaughlin monitoring in order to determine its spin–orbit alignment given the brightness (V = 12.8) and stellar rotational velocity (v\\sin i≈ 9.3 km s‑1) of the host star. These discoveries significantly increase the number of inflated hot Jupiters known, contributing to our understanding of the mechanism(s) responsible for hot Jupiter inflation. The HATSouth network is operated by a collaboration consisting of Princeton University (PU), the Max Planck Institute für Astronomie (MPIA), the Australian National University (ANU), and the Pontificia Universidad Católica de Chile (PUC). The station at Las Campanas Observatory (LCO) of the Carnegie Institute is operated by PU in conjunction with PUC, the station at the High Energy Spectroscopic Survey (H.E.S.S.) site is operated in conjunction with MPIA, and the station at Siding Spring Observatory (SSO) is operated jointly with ANU. Based in part on observations made with the MPG 2.2 m Telescope at the ESO

  8. Primary structure of the human M2 mitochondrial autoantigen of primary biliary cirrhosis: Dihydrolipoamide acetyltransferase

    SciTech Connect

    Coppel, R.L.; McNeilage, L.J.; Surh, C.D.; Van De Water, J.; Spithill, T.W.; Whittingham, S.; Gershwin, M.E. )

    1988-10-01

    Primary biliary cirrhosis is a chronic, destructive autoimmune liver disease of humans. Patient sera are characterized by a high frequency of autoantibodies to a M{sub r} 70,000 mitochondrial antigen a component of the M2 antigen complex. The authors have identified a human cDNA clone encoding the complete amino acid sequence of this autoantigen. The predicted structure has significant similarity with the dihydrolipoamide acetyltransferase of the Escherichia coli pyruvate dehydrogenase multienzyme complex. The human sequence preserves the Glu-Thr-Asp-Lys-Ala motif of the lipoyl-binding site and has two potential binding sites. Expressed fragments of the cDNA react strongly with sera from patients with primary biliary cirrhosis but not with sera from patients with autoimmune chronic active hepatitis or sera from healthy subjects.

  9. Mapping Lysine Acetyltransferase-Ligand Interactions by Activity-Based Capture.

    PubMed

    Montgomery, D C; Meier, J L

    2016-01-01

    Changes in reversible protein acetylation mediate many key aspects of genomic regulation and enzyme function. The catalysts for this posttranslational modification, lysine acetyltransferases (KATs), have been difficult targets for characterization due to their complex architecture and challenging reconstitution. To address this challenge, here we describe methods to profile endogenous KAT activities using activity-based probes. This method facilitates the targeted analysis of several cellular KATs and can be used to study their interactions with many different types of ligands, including acyl-CoA metabolites. This competitive activity-based capture approach provides a method to assess the selectivity of ligands for different KAT families in complex proteomic settings, and thus has the potential to offer substantial insights into the regulation of cellular KAT function. PMID:27423859

  10. Long-term surveillance plan for the Mexican Hat Disposal Site, Mexican Hat, Utah

    SciTech Connect

    1996-02-01

    This plan describes the long-term surveillance activities for the Uranium Mill Tailings Remedial Action (UMTRA) Project disposal site at Mexican Hat, Utah. The U.S. Department of Energy (DOE) will carry out these activities to ensure that the disposal site continues to function as designed. This long-term surveillance plan (LTSP) was prepared as a requirement for acceptance under the U.S. Nuclear Regulatory Commission (NRC) general license for custody and long-term care of residual radioactive material (RRM). This LTSP (based on the DOE`s Guidance for Implementing the UMTRA Project Long-term Surveillance Program), documents the land ownership interests and details how the long-term care of the disposal site will be accomplished.

  11. HAT-P-20b-HAT-P-23b: FOUR MASSIVE TRANSITING EXTRASOLAR PLANETS

    SciTech Connect

    Bakos, G. A.; Hartman, J.; Torres, G.; Latham, D. W.; Noyes, R. W.; Kipping, D.; Esquerdo, G. A.; Beky, B.; Perumpilly, G.; Everett, M.; Sasselov, D. D.; Stefanik, R. P.; Kovacs, Geza; Fischer, D. A.; Johnson, J. A.; Marcy, G. W.; Howard, A. W.; Shporer, A.; Buchhave, L. A.; Lazar, J.; and others

    2011-12-01

    We report the discovery of four relatively massive (2-7 M{sub J}) transiting extrasolar planets. HAT-P-20b orbits the moderately bright V = 11.339 K3 dwarf star GSC 1910-00239 on a circular orbit, with a period P = 2.875317 {+-} 0.000004 days, transit epoch T{sub c} = 2455080.92661 {+-} 0.00021 (BJD{sub UTC}), and transit duration 0.0770 {+-} 0.0008 days. The host star has a mass of 0.76 {+-} 0.03 M{sub Sun }, radius of 0.69 {+-} 0.02 R{sub Sun }, effective temperature 4595 {+-} 80 K, and metallicity [Fe/H] = +0.35 {+-} 0.08. The planetary companion has a mass of 7.246 {+-} 0.187 M{sub J} and a radius of 0.867 {+-} 0.033 R{sub J} yielding a mean density of 13.78 {+-} 1.50 g cm{sup -3}. HAT-P-21b orbits the V = 11.685 G3 dwarf star GSC 3013-01229 on an eccentric (e = 0.228 {+-} 0.016) orbit, with a period P = 4.124481 {+-} 0.000007 days, transit epoch T{sub c} = 2454996.41312 {+-} 0.00069, and transit duration 0.1530 {+-} 0.0027 days. The host star has a mass of 0.95 {+-} 0.04 M{sub Sun }, radius of 1.10 {+-} 0.08 R{sub Sun }, effective temperature 5588 {+-} 80 K, and metallicity [Fe/H] = +0.01 {+-} 0.08. The planetary companion has a mass of 4.063 {+-} 0.161 M{sub J} and a radius of 1.024 {+-} 0.092 R{sub J} yielding a mean density of 4.68{sup +1.59}{sub -0.99} g cm{sup -3}. HAT-P-21b is a borderline object between the pM and pL class planets, and the transits occur near apastron. HAT-P-22b orbits the bright V = 9.732 G5 dwarf star HD 233731 on a circular orbit, with a period P = 3.212220 {+-} 0.000009 days, transit epoch T{sub c} = 2454930.22001 {+-} 0.00025, and transit duration 0.1196 {+-} 0.0014 days. The host star has a mass of 0.92 {+-} 0.03 M{sub Sun }, radius of 1.04 {+-} 0.04 R{sub Sun }, effective temperature 5302 {+-} 80 K, and metallicity [Fe/H] = +0.24 {+-} 0.08. The planet has a mass of 2.147 {+-} 0.061 M{sub J} and a compact radius of 1.080 {+-} 0.058 R{sub J} yielding a mean density of 2.11{sup +0.40}{sub -0.29} g cm{sup -3}. The host star also

  12. Human STAGA complex is a chromatin-acetylating transcription coactivator that interacts with pre-mRNA splicing and DNA damage-binding factors in vivo.

    PubMed

    Martinez, E; Palhan, V B; Tjernberg, A; Lymar, E S; Gamper, A M; Kundu, T K; Chait, B T; Roeder, R G

    2001-10-01

    GCN5 is a histone acetyltransferase (HAT) originally identified in Saccharomyces cerevisiae and required for transcription of specific genes within chromatin as part of the SAGA (SPT-ADA-GCN5 acetylase) coactivator complex. Mammalian cells have two distinct GCN5 homologs (PCAF and GCN5L) that have been found in three different SAGA-like complexes (PCAF complex, TFTC [TATA-binding-protein-free TAF(II)-containing complex], and STAGA [SPT3-TAF(II)31-GCN5L acetylase]). The composition and roles of these mammalian HAT complexes are still poorly characterized. Here, we present the purification and characterization of the human STAGA complex. We show that STAGA contains homologs of most yeast SAGA components, including two novel human proteins with histone-like folds and sequence relationships to yeast SPT7 and ADA1. Furthermore, we demonstrate that STAGA has acetyl coenzyme A-dependent transcriptional coactivator functions from a chromatin-assembled template in vitro and associates in HeLa cells with spliceosome-associated protein 130 (SAP130) and DDB1, two structurally related proteins. SAP130 is a component of the splicing factor SF3b that associates with U2 snRNP and is recruited to prespliceosomal complexes. DDB1 (p127) is a UV-damaged-DNA-binding protein that is involved, as part of a complex with DDB2 (p48), in nucleotide excision repair and the hereditary disease xeroderma pigmentosum. Our results thus suggest cellular roles of STAGA in chromatin modification, transcription, and transcription-coupled processes through direct physical interactions with sequence-specific transcription activators and with components of the splicing and DNA repair machineries. PMID:11564863

  13. Gallic Acid Decreases Inflammatory Cytokine Secretion Through Histone Acetyltransferase/Histone Deacetylase Regulation in High Glucose-Induced Human Monocytes.

    PubMed

    Lee, Wooje; Lee, Sang Yeol; Son, Young-Jin; Yun, Jung-Mi

    2015-07-01

    Hyperglycemia contributes to diabetes and several diabetes-related complications. Gallic acid is a polyhydroxy phenolic compound found in various natural products. In this study, we investigated the effects and mechanism of gallic acid on proinflammatory cytokine secretion in high glucose-induced human monocytes (THP-1 cells). THP-1 cells were cultured under normoglycemic or hyperglycemic conditions, in the absence or presence of gallic acid. Hyperglycemic conditions significantly induced histone acetylation, nuclear factor-κB (NF-κB) activation, and proinflammatory cytokine release from THP-1 cells, whereas gallic acid suppressed NF-κB activity and cytokine release. It also significantly reduced CREB-binding protein/p300 (CBP/p300, a NF-κB coactivator) gene expression, acetylation levels, and CBP/p300 histone acetyltransferase (HAT) activity. In addition, histone deacetylase 2 (HDAC2) expression was significantly induced. These results suggest that gallic acid inhibits hyperglycemic-induced cytokine production in monocytes through epigenetic changes involving NF-κB. Therefore, gallic acid may have potential for the treatment and prevention of diabetes and its complications.

  14. Vector Boson Jets with BlackHat and Sherpa

    SciTech Connect

    Berger, C.F.; Bern, Z.; Dixon, Lance J.; Cordero, F.Febres; Forde, D.; Gleisberg, T.; Ita, H.; Kosower, D.A.; Maitre, D.; /Durham U.

    2010-08-25

    We review recent NLO QCD results for W, Z + 3-jet production at hadron colliders, computing using BlackHat and SHERPA, and including also some new results for Z + 3-jet production for the LHC at 7 TeV. We report new progress towards the NLO cross section for W + 4-jet production. In particular, we show that the virtual matrix elements produced by BlackHat are numerically stable. We also show that with an improved integrator and tree-level matrix elements from BlackHat, SHERPA produces well-behaved real-emission contributions. As an illustration, we present the real-emission contributions - including dipole-subtraction terms - to the p{sub T} distribution of the fourth jet, for a single subprocess with the maximum number of gluons.

  15. Design and evaluation of a bolted joint for a discrete carbon-epoxy rod-reinforced hat section

    NASA Technical Reports Server (NTRS)

    Rousseau, Carl Q.; Baker, Donald J.

    1996-01-01

    The use of prefabricated pultruded carbon-epoxy rods has reduced the manufacturing complexity and costs of stiffened composite panels while increasing the damage tolerance of the panels. However, repairability of these highly efficient discrete stiffeners has been a concern. Design, analysis, and test results are presented in this paper for a bolted-joint repair for the pultruded rod concept that is capable of efficiently transferring axial loads in a hat-section stiffener on the upper skin segment of a heavily loaded aircraft wing component. A tension and a compression joint design were evaluated. The tension joint design achieved approximately 1.0% strain in the carbon-epoxy rod-reinforced hat-section and failed in a metal fitting at 166% of the design ultimate load. The compression joint design failed in the carbon-epoxy rod-reinforced hat-section test specimen area at approximately 0.7% strain and at 110% of the design ultimate load. This strain level of 0.7% in compression is similar to the failure strain observed in previously reported carbon-epoxy rod-reinforced hat-section column tests.

  16. Design and Evaluation of a Bolted Joint for a Discrete Carbon-Epoxy Rod-Reinforced Hat Section

    NASA Technical Reports Server (NTRS)

    Baker, Donald J.; Rousseau, Carl Q.

    1996-01-01

    The use of pre-fabricated pultruded carbon-epoxy rods has reduced the manufacturing complexity and costs of stiffened composite panels while increasing the damage tolerance of the panels. However, repairability of these highly efficient discrete stiffeners has been a concern. Design, analysis, and test results are presented in this paper for a bolted-joint repair for the pultruded rod concept that is capable of efficiently transferring axial loads in a hat-section stiffener on the upper skin segment of a heavily loaded aircraft wing component. A tension and a compression joint design were evaluated. The tension joint design achieved approximately 1.0 percent strain in the carbon-epoxy rod-reinforced hat-section and failed in a metal fitting at 166 percent of the design ultimate load. The compression joint design failed in the carbon-epoxy rod-reinforced hat-section test specimen area at approximately 0.7 percent strain and at 110 percent of the design ultimate load. This strain level of 0.7 percent in compression is similar to the failure strain observed in previously reported carbon-epoxy rod-reinforced hat-section column tests.

  17. Arsenic Trioxide Reduces Global Histone H4 Acetylation at Lysine 16 through Direct Binding to Histone Acetyltransferase hMOF in Human Cells

    PubMed Central

    Liu, Da; Wu, Donglu; Zhao, Linhong; Yang, Yang; Ding, Jian; Dong, Liguo; Hu, Lianghai; Wang, Fei; Zhao, Xiaoming; Cai, Yong; Jin, Jingji

    2015-01-01

    Histone post-translational modification heritably regulates gene expression involved in most cellular biological processes. Experimental studies suggest that alteration of histone modifications affects gene expression by changing chromatin structure, causing various cellular responses to environmental influences. Arsenic (As), a naturally occurring element and environmental pollutant, is an established human carcinogen. Recently, increasing evidence suggests that As-mediated epigenetic mechanisms may be involved in its toxicity and carcinogenicity, but how this occurs is still unclear. Here we present evidence that suggests As-induced global histone H4K16 acetylation (H4K16ac) partly due to the direct physical interaction between As and histone acetyltransferase (HAT) hMOF (human male absent on first) protein, leading to the loss of hMOF HAT activity. Our data show that decreased global H4K16ac and increased deacetyltransferase HDAC4 expression occurred in arsenic trioxide (As2O3)-exposed HeLa or HEK293T cells. However, depletion of HDAC4 did not affect global H4K16ac, and it could not raise H4K16ac in cells exposed to As2O3, suggesting that HDAC4 might not directly be involved in histone H4K16 de-acetylation. Using As-immobilized agarose, we confirmed that As binds directly to hMOF, and that this interaction was competitively inhibited by free As2O3. Also, the direct interaction of As and C2CH zinc finger peptide was verified by MAIDI-TOF mass and UV absorption. In an in vitro HAT assay, As2O3 directly inhibited hMOF activity. hMOF over-expression not only increased resistance to As and caused less toxicity, but also effectively reversed reduced H4K16ac caused by As exposure. These data suggest a theoretical basis for elucidating the mechanism of As toxicity. PMID:26473953

  18. Social factors in occupational health: a history of hard hats.

    PubMed

    Rosenberg, Beth; Levenstein, Charles

    2010-01-01

    Personal protective equipment (PPE) is the least desirable way to ensure workplace safety, and it is difficult to use consistently. Hard hats are different; they have cachet and are often worn even when they are not required. We investigated the history of this personal protective equipment to see if there were any lessons that could be applied to other forms of PPE. We learned that what makes hard hats special are social factors that are specific to a certain time and place. The importance of social factors illuminates the requirement that cultural and social norms of workers be included in any kind of worker safety and health training.

  19. Shear buckling analysis of a hat-stiffened panel

    NASA Technical Reports Server (NTRS)

    Ko, William L.; Jackson, Raymond H.

    1994-01-01

    A buckling analysis was performed on a hat-stiffened panel subjected to shear loading. Both local buckling and global buckling were analyzed. The global shear buckling load was found to be several times higher than the local shear buckling load. The classical shear buckling theory for a flat plate was found to be useful in predicting the local shear buckling load of the hat-stiffened panel, and the predicted local shear buckling loads thus obtained compare favorably with the results of finite element analysis.

  20. Unusual regioversatility of acetyltransferase Eis, a cause of drug resistance in XDR-TB

    SciTech Connect

    Chen, Wenjing; Biswas, Tapan; Porter, Vanessa R.; Tsodikov, Oleg V.; Garneau-Tsodikova, Sylvie

    2011-09-06

    The emergence of multidrug-resistant and extensively drug-resistant (XDR) tuberculosis (TB) is a serious global threat. Aminoglycoside antibiotics are used as a last resort to treat XDR-TB. Resistance to the aminoglycoside kanamycin is a hallmark of XDR-TB. Here, we reveal the function and structure of the mycobacterial protein Eis responsible for resistance to kanamycin in a significant fraction of kanamycin-resistant Mycobacterium tuberculosis clinical isolates. We demonstrate that Eis has an unprecedented ability to acetylate multiple amines of many aminoglycosides. Structural and mutagenesis studies of Eis indicate that its acetylation mechanism is enabled by a complex tripartite fold that includes two general control non-derepressible 5 (GCN5)-related N-acetyltransferase regions. An intricate negatively charged substrate-binding pocket of Eis is a potential target of new antitubercular drugs expected to overcome aminoglycoside resistance.

  1. Coenzyme A Binding to the Aminoglycoside Acetyltransferase (3)-IIIb Increases Conformational Sampling of Antibiotic Binding Site

    SciTech Connect

    Hu, Xiaohu; Norris, Adrianne; Baudry, Jerome Y; Serpersu, Engin H

    2011-01-01

    NMR spectroscopy experiments and molecular dynamics simulations were performed to describe the dynamic properties of the aminoglycoside acetyltransferase (3)-IIIb (AAC) in its apo and coenzyme A (CoASH) bound forms. The {sup 15}N-{sup 1}H HSQC spectra indicate a partial structural change and coupling of the CoASH binding site with another region in the protein upon the CoASH titration into the apo enzyme. Molecular dynamics simulations indicate a significant structural and dynamic variation of the long loop in the antibiotic binding domain in the form of a relatively slow (250 ns), concerted opening motion in the CoASH enzyme complex and that binding of the CoASH increases the structural flexibility of the loop, leading to an interchange between several similar equally populated conformations.

  2. Dr. Edward de Bono's Six Thinking Hats and Numeracy

    ERIC Educational Resources Information Center

    Paterson, Anne

    2006-01-01

    In education, the term "metacognition" describes thinking about thinking. Within mathematics, the term "metacomputation" describes thinking about computational methods and tools. This article shows how Dr. Edward de Bono's Six Thinking Hats can be used to demonstrate metacognition and metacomputation in the primary classroom. The article suggests…

  3. Hats off to Problem-Solving with Couples

    ERIC Educational Resources Information Center

    Li, Chi-Sing; Lin, Yu-Fen; Nelson, Judy; Eckstein, Daniel

    2008-01-01

    The purpose of this article is to demonstrate how counselors can use de Bono's Six Thinking Hats problem-solving technique in their work with couples. Part 1 of the article focuses on an introduction to the technique, including a theoretical rationale and supporting research. Following a detailed description of the process of using the model as a…

  4. "The Cat in the Hat." A Literature Unit.

    ERIC Educational Resources Information Center

    Williams, Susan

    Intended as an aid to primary school teachers, this handbook presents a literature unit based on the children's book, "The Cat in the Hat" (Dr. Seuss). It begins with sample lesson plans, a unit planner, getting to know the book and author, and suggestions for using the unit activities. Next, a section offers unit activities focusing on unit…

  5. Compressive buckling analysis of hat-stiffened panel

    NASA Technical Reports Server (NTRS)

    Ko, William L.; Jackson, Raymond H.

    1991-01-01

    Buckling analysis was performed on a hat-stiffened panel subjected to uniaxial compression. Both local buckling and global buckling were analyzed. It was found that the global buckling load was several times higher than the buckling load. The predicted local buckling loads compared favorably with both experimental data and finite-element analysis.

  6. Exoplanet Transits Registered at the Universidad de Monterrey Observatory. I. HAT-P-12b, HAT-P-13b, HAT-P-16b, HAT-P-23b, and WASP-10b

    NASA Astrophysics Data System (ADS)

    Sada, Pedro V.; Ramón-Fox, Felipe G.

    2016-02-01

    Forty transits of the exoplanets HAT-P-12b, HAT-P-13b, HAT-P-16b, HAT-P-23b, and WASP-10b were recorded with the 0.36 m telescope at the Universidad de Monterrey Observatory. The images were captured with a standard Johnson-Cousins Rc and Ic and Sloan z’ filters and processed to obtain individual light curves of the events. These light curves were successfully combined for each system to obtain a resulting one of higher quality, but with a slightly larger time sampling rate. A reduction by a factor of about four in per-point scatter was typically achieved, resulting in combined light curves with a scatter of ∼1 mmag. The noise characteristics of the combined light curves were verified by comparing Allan variance plots of the residuals. The combined light curves for each system, along with radial velocity measurements from the literature when available, were modeled using a Monte Carlo method to obtain the essential parameters that characterize the systems. Our results for all these systems confirm the derived transit parameters (the planet-to-star radius ratio, {R}{{p}}/{R}*; the scaled semimajor axis, a/{R}*; the orbital inclination, i; in some cases the eccentricity, e; and argument of periastron of the orbit, ω), validating the methodology. This technique can be used by small college observatories equipped with modest-sized telescopes to help characterize known extrasolar planet systems. In some instances, the uncertainties of the essential transit parameters are also reduced. For HAT-P-23b, in particular, we derive a planet size 4.5 ± 1.0% smaller. We also derive improved linear periods for each system, useful for scheduling observations.

  7. Hats for Sale: A Salute to Directors.

    ERIC Educational Resources Information Center

    Ferguson, Sue

    Experiences related to pursuing excellence and a positive attitude as a campus childcare director are presented. The paper describes the emotional quotient (EQ) as a complex, multifaceted quality incorporating self- and social-awareness, empathy, optimism, and persistence that may predict one's success in certain kinds of work. Optimism may be…

  8. 49. Taken from highline; "McKinley hat" remains on "B" furnace; ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    49. Taken from high-line; "McKinley hat" remains on "B" furnace; no longer used, "McKinley hat was open receptacle with bell below. Hat carried charge to furnace top, dumping it to bell; bell locked onto furnace top, dropping charge into furnace. Looking east - Rouge Steel Company, 3001 Miller Road, Dearborn, MI

  9. Measurements of the UVR protection provided by hats used at school.

    PubMed

    Gies, Peter; Javorniczky, John; Roy, Colin; Henderson, Stuart

    2006-01-01

    The importance of protection against solar ultraviolet radiation (UVR) in childhood has lead to SunSmart policies at Australian schools, in particular primary schools, where children are encouraged and in many cases required to wear hats at school. Hat styles change regularly and the UVR protection provided by some of the hat types currently used and recommended for sun protection by the various Australian state cancer councils had not been previously evaluated. The UVR protection of the hats was measured using UVR sensitive polysulphone film badges attached to different facial sites on rotating headforms. The sun protection type hats included in this study were broad-brimmed hats, "bucket hats" and legionnaires hats. Baseball caps, which are very popular, were also included. The broad-brimmed hats and bucket hats provided the most UVR protection for the six different sites about the face and head. Legionnaires hats also provided satisfactory UVR protection, but the caps did not provide UVR protection to many of the facial sites. The highest measured UVR protection factors for facial sites other than the forehead were 8 to 10, indicating that, while some hats can be effective, they need to be used in combination with other forms of UVR protection.

  10. White Hats Chasing Black Hats: Careers in IT and the Skills Required to Get There. Advisory from Professionals

    ERIC Educational Resources Information Center

    Fulton, Eric; Lawrence, Cameron; Clouse, Shawn

    2013-01-01

    The aim of this paper is to illuminate the exciting world in which "white hat crackers" operate and to suggest topics that can help prepare students to enter this high-demand field. While currently there is extraordinary demand for graduates to fill these positions that have relatively high starting salaries, employers find it difficult…

  11. A Novel Histone Deacetylase Complex in the Control of Transcription and Genome Stability

    PubMed Central

    Zilio, Nicola; Codlin, Sandra; Vashisht, Ajay A.; Bitton, Danny A.; Head, Steven R.; Wohlschlegel, James A.; Bähler, Jürg

    2014-01-01

    The acetylation state of histones, controlled by histone acetyltransferases (HATs) and deacetylases (HDACs), profoundly affects DNA transcription and repair by modulating chromatin accessibility to the cellular machinery. The Schizosaccharomyces pombe HDAC Clr6 (human HDAC1) binds to different sets of proteins that define functionally distinct complexes: I, I′, and II. Here, we determine the composition, architecture, and functions of a new Clr6 HDAC complex, I′′, delineated by the novel proteins Nts1, Mug165, and Png3. Deletion of nts1 causes increased sensitivity to genotoxins and deregulated expression of Tf2 elements, long noncoding RNA, and subtelomeric and stress-related genes. Similar, but more pervasive, phenotypes are observed upon Clr6 inactivation, supporting the designation of complex I′′ as a mediator of a key subset of Clr6 functions. We also reveal that with the exception of Tf2 elements, the genome-wide loading sites and loci regulated by Clr6 I″ do not correlate. Instead, Nts1 loads at genes that are expressed in midmeiosis, following oxidative stress, or are periodically expressed. Collective data suggest that Clr6 I′′ has (i) indirect effects on gene expression, conceivably by mediating higher-order chromatin organization of subtelomeres and Tf2 elements, and (ii) direct effects on the transcription of specific genes in response to certain cellular or environmental stimuli. PMID:25002536

  12. Structural, Functional, and Inhibition Studies of a Gcn5-related N-Acetyltransferase (GNAT) Superfamily Protein PA4794

    PubMed Central

    Majorek, Karolina A.; Kuhn, Misty L.; Chruszcz, Maksymilian; Anderson, Wayne F.; Minor, Wladek

    2013-01-01

    The Gcn5-related N-acetyltransferase (GNAT) superfamily is a large group of evolutionarily related acetyltransferases, with multiple paralogs in organisms from all kingdoms of life. The functionally characterized GNATs have been shown to catalyze the transfer of an acetyl group from acetyl-coenzyme A (Ac-CoA) to the amine of a wide range of substrates, including small molecules and proteins. GNATs are prevalent and implicated in a myriad of aspects of eukaryotic and prokaryotic physiology, but functions of many GNATs remain unknown. In this work, we used a multi-pronged approach of x-ray crystallography and biochemical characterization to elucidate the sequence-structure-function relationship of the GNAT superfamily member PA4794 from Pseudomonas aeruginosa. We determined that PA4794 acetylates the Nϵ amine of a C-terminal lysine residue of a peptide, suggesting it is a protein acetyltransferase specific for a C-terminal lysine of a substrate protein or proteins. Furthermore, we identified a number of molecules, including cephalosporin antibiotics, which are inhibitors of PA4794 and bind in its substrate-binding site. Often, these molecules mimic the conformation of the acetylated peptide product. We have determined structures of PA4794 in the apo-form, in complexes with Ac-CoA, CoA, several antibiotics and other small molecules, and a ternary complex with the products of the reaction: CoA and acetylated peptide. Also, we analyzed PA4794 mutants to identify residues important for substrate binding and catalysis. PMID:24003232

  13. Inhibition of aminoglycoside 6'-N-acetyltransferase type Ib by zinc: reversal of amikacin resistance in Acinetobacter baumannii and Escherichia coli by a zinc ionophore.

    PubMed

    Lin, David L; Tran, Tung; Alam, Jamal Y; Herron, Steven R; Ramirez, Maria Soledad; Tolmasky, Marcelo E

    2014-07-01

    In vitro activity of the aminoglycoside 6'-N-acetyltransferase type Ib [AAC(6')-Ib] was inhibited by ZnCl2 with a 50% inhibitory concentration (IC50) of 15 μM. Growth of Acinetobacter baumannii or Escherichia coli harboring aac(6')-Ib in cultures containing 8 μg/ml amikacin was significantly inhibited by the addition of 2 μM Zn(2+) in complex with the ionophore pyrithione (ZnPT). PMID:24820083

  14. Structural and functional characterization of TRI3 trichothecene 15-O-acetyltransferase from Fusarium sporotrichioides

    PubMed Central

    Garvey, Graeme S; McCormick, Susan P; Alexander, Nancy J; Rayment, Ivan

    2009-01-01

    Fusarium head blight is a devastating disease of cereal crops whose worldwide incidence is increasing and at present there is no satisfactory way of combating this pathogen or its associated toxins. There is a wide variety of trichothecene mycotoxins and they all contain a 12,13-epoxytrichothecene skeleton but differ in their substitutions. Indeed, there is considerable variation in the toxin profile across the numerous Fusarium species that has been ascribed to differences in the presence or absence of biosynthetic enzymes and their relative activity. This article addresses the source of differences in acetylation at the C15 position of the trichothecene molecule. Here, we present the in vitro structural and biochemical characterization of TRI3, a 15-O-trichothecene acetyltransferase isolated from F. sporotrichioides and the “in vivo” characterization of Δtri3 mutants of deoxynivalenol (DON) producing F. graminearum strains. A kinetic analysis shows that TRI3 is an efficient enzyme with the native substrate, 15-decalonectrin, but is inactive with either DON or nivalenol. The structure of TRI3 complexed with 15-decalonectrin provides an explanation for this specificity and shows that Tri3 and Tri101 (3-O-trichothecene acetyltransferase) are evolutionarily related. The active site residues are conserved across all sequences for TRI3 orthologs, suggesting that differences in acetylation at C15 are not due to differences in Tri3. The tri3 deletion mutant shows that acetylation at C15 is required for DON biosynthesis even though DON lacks a C15 acetyl group. The enzyme(s) responsible for deacetylation at the 15 position of the trichothecene mycotoxins have not been identified. PMID:19319932

  15. Structural and functional characterization of TRI3 trichothecene 15-O-acetyltransferase from Fusarium sporotrichioides

    SciTech Connect

    Garvey, Graeme S.; McCormick, Susan P.; Alexander, Nancy J.; Rayment, Ivan

    2009-08-14

    Fusarium head blight is a devastating disease of cereal crops whose worldwide incidence is increasing and at present there is no satisfactory way of combating this pathogen or its associated toxins. There is a wide variety of trichothecene mycotoxins and they all contain a 12,13-epoxytrichothecene skeleton but differ in their substitutions. Indeed, there is considerable variation in the toxin profile across the numerous Fusarium species that has been ascribed to differences in the presence or absence of biosynthetic enzymes and their relative activity. This article addresses the source of differences in acetylation at the C15 position of the trichothecene molecule. Here, we present the in vitro structural and biochemical characterization of TRI3, a 15-O-trichothecene acetyltransferase isolated from F. sporotrichioides and the 'in vivo' characterization of Deltatri3 mutants of deoxynivalenol (DON) producing F. graminearum strains. A kinetic analysis shows that TRI3 is an efficient enzyme with the native substrate, 15-decalonectrin, but is inactive with either DON or nivalenol. The structure of TRI3 complexed with 15-decalonectrin provides an explanation for this specificity and shows that Tri3 and Tri101 (3-O-trichothecene acetyltransferase) are evolutionarily related. The active site residues are conserved across all sequences for TRI3 orthologs, suggesting that differences in acetylation at C15 are not due to differences in Tri3. The tri3 deletion mutant shows that acetylation at C15 is required for DON biosynthesis even though DON lacks a C15 acetyl group. The enzyme(s) responsible for deacetylation at the 15 position of the trichothecene mycotoxins have not been identified.

  16. Cloning, purification, crystallization and preliminary crystallographic analysis of a hypothetical acetyltransferase from Pyrococcus furiosus

    PubMed Central

    Biarrotte-Sorin, Sabrina; Mayer, Claudine

    2005-01-01

    The GCN5-related N-acetyltransferase (GNAT) superfamily has a primordial role in cellular processes such as transcription initiation and regulation by histone acetylation, aminoglycoside resistance and melatonin metabolism. To date, no acetyltransferase from the archaeal domain of life has been studied. This paper describes the cloning, expression, purification and crystallization of a Pyrococcus furiosus hypothetical acetyltransferase PfGNAT (MW = 22 007 Da). The crystals belong to space group P622, with one molecule in the asymmetric unit and unit-cell parameters a = b = 82.6, c = 105.92 Å, α = β = 90, γ = 120°. Crystals diffract X-rays to 3.0 Å resolution on a synchrotron-radiation source. Determination of this structure will provide new insights into the substrate-specificity of this acetyltransferase and the thermal stability of the N-acetyltransferase domain. PMID:16511014

  17. Corner sharing tetrahedral network in Co(3)(HAT)[N(CN)(2)](6)(OH(2))(2) (HAT = 1,4,5,8,9,12-hexaazatriphenylene).

    PubMed

    Marshall, Shireen R; Rheingold, Arnold L; Dawe, Louise N; Shum, William W; Kitamura, Chitoshi; Miller, Joel S

    2002-07-15

    We report a trinuclear Co(II) complex containing bridging dicyanamides and a tris-chelated HAT, which possesses approximately 37% void space. The magnetic exchange pathways appear in the structure as a corner sharing tetrahedral network. The compound crystallizes in the monoclinic space group P2(1)/c [a = 13.655(3) A, b = 15.189(3) A, c = 22.367(4) A, beta = 114.100(2) degrees, V = 4234.5(14) A(3), Z = 4, R(F(o)) = 0.0823]. The magnetic data were fit to an S = 3/2 model for systems dominated by zero-field splitting effects with g = 2.01 and D = 38.9 cm(-1). PMID:12099860

  18. A Bacterial Acetyltransferase Destroys Plant Microtubule Networks and Blocks Secretion

    PubMed Central

    Lee, Amy Huei-Yi; Hurley, Brenden; Felsensteiner, Corinna; Yea, Carmen; Ckurshumova, Wenzislava; Bartetzko, Verena; Wang, Pauline W.; Quach, Van; Lewis, Jennifer D.; Liu, Yulu C.; Börnke, Frederik; Angers, Stephane; Wilde, Andrew

    2012-01-01

    The eukaryotic cytoskeleton is essential for structural support and intracellular transport, and is therefore a common target of animal pathogens. However, no phytopathogenic effector has yet been demonstrated to specifically target the plant cytoskeleton. Here we show that the Pseudomonas syringae type III secreted effector HopZ1a interacts with tubulin and polymerized microtubules. We demonstrate that HopZ1a is an acetyltransferase activated by the eukaryotic co-factor phytic acid. Activated HopZ1a acetylates itself and tubulin. The conserved autoacetylation site of the YopJ / HopZ superfamily, K289, plays a critical role in both the avirulence and virulence function of HopZ1a. Furthermore, HopZ1a requires its acetyltransferase activity to cause a dramatic decrease in Arabidopsis thaliana microtubule networks, disrupt the plant secretory pathway and suppress cell wall-mediated defense. Together, this study supports the hypothesis that HopZ1a promotes virulence through cytoskeletal and secretory disruption. PMID:22319451

  19. Primary structure of a chloramphenicol acetyltransferase specified by R plasmids.

    PubMed

    Shaw, W V; Packman, L C; Burleigh, B D; Dell, A; Morris, H R; Hartley, B S

    Naturally occurring isolates of chloramphenicol-resistant bacteria commonly synthesise chloramphenicol acetyltransferase (EC 2.3.28; CAT) in amounts which are sufficient to account for the resistance phenotype and often harbour plasmids which carry the structural gene for CAT. The findings of CAT in such diverse prokaryotes as Proteus mirabilis, Agrobacterium tumefaciens, Streptomyces sp., and a soil Flavobacterium has led to speculation concerning the origin and evolution of the more commonly observed CAT variants specified by plasmids in clinically important bacteria. To provide a more solid basis for studying the evolution and spread of CAT within prokaryotes we chose to determine the complete amino acid sequence of a type I variant of CAT, the variant known to be associated with most F-like plasmids conferring chloramphenicol resistance. The sequence has been determined by combining the results obtained from manual and automated sequential degradation with those obtained by mass spectrometry of peptides generated by enzymatic digestion. The directly determined primary structure is identical with that predicted by the DNA sequence analysis of the chloramphenicol resistance transponson Tn9 known to specify a type I variant of chloramphenicol acetyltransferase.

  20. Salt-induced changes in the subunit structure of the Bacillus stearothermophilus lipoate acetyltransferase.

    PubMed

    Shigeoka, Yuichi; Fujisawa, Tetsuro; Teshiba, Satoshi; Fukumori, Hisayoshi; Yamamoto, Kohji; Banno, Yutaka; Aso, Yoichi

    2013-01-01

    The Bacillus stearothermophilus lipoate acetyltransferase (E2), composed of sixty identical, subunits is the core component of the pyruvate dehydrogenase complex (PDC). E2 polypeptide is composed of LD, PSBD, and CD domains. Most studies had focused on a truncated E2 that is deficient in LD and PSBD, because CD mainly contributes to maintaining the multimeric structure. We examined salt-induced changes in E2 without truncation and constructed reaction models. We speculate that in the presence of KCl, E2 is dissociated into a monomer and then assembled into an aggregative complex (C(A)) and a quasi-stable complex (C(Q)). C(A) was larger than C(Q), but smaller than intact E2. C(A) and C(Q), were dominant complexes at about neutral pH and at basic pH respectively. PDC, in which PSBD is occupied by other components, and a truncated E2 undergo dissociation only. LD-PSBD region besides CD might then contribute to the partial association of dissociated E2. PMID:23924725

  1. Structural basis of hAT transposon end recognition by Hermes, an octameric DNA transposase from Musca domestica.

    PubMed

    Hickman, Alison B; Ewis, Hosam E; Li, Xianghong; Knapp, Joshua A; Laver, Thomas; Doss, Anna-Louise; Tolun, Gökhan; Steven, Alasdair C; Grishaev, Alexander; Bax, Ad; Atkinson, Peter W; Craig, Nancy L; Dyda, Fred

    2014-07-17

    Hermes is a member of the hAT transposon superfamily that has active representatives, including McClintock's archetypal Ac mobile genetic element, in many eukaryotic species. The crystal structure of the Hermes transposase-DNA complex reveals that Hermes forms an octameric ring organized as a tetramer of dimers. Although isolated dimers are active in vitro for all the chemical steps of transposition, only octamers are active in vivo. The octamer can provide not only multiple specific DNA-binding domains to recognize repeated subterminal sequences within the transposon ends, which are important for activity, but also multiple nonspecific DNA binding surfaces for target capture. The unusual assembly explains the basis of bipartite DNA recognition at hAT transposon ends, provides a rationale for transposon end asymmetry, and suggests how the avidity provided by multiple sites of interaction could allow a transposase to locate its transposon ends amidst a sea of chromosomal DNA.

  2. RELATIVE PHOTOMETRY OF HAT-P-1b OCCULTATIONS

    SciTech Connect

    Beky, Bence; Holman, Matthew J.; Noyes, Robert W.; Sasselov, Dimitar D.; Gilliland, Ronald L.; Bakos, Gaspar A.; Winn, Joshua N.

    2013-06-01

    We present Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph observations of two occultations of the transiting exoplanet HAT-P-1b. By measuring the planet to star flux ratio near opposition, we constrain the geometric albedo of the planet, which is strongly linked to its atmospheric temperature gradient. An advantage of HAT-P-1 as a target is its binary companion ADS 16402 A, which provides an excellent photometric reference, simplifying the usual steps in removing instrumental artifacts from HST time-series photometry. We find that without this reference star, we would need to detrend the lightcurve with the time of the exposures as well as the first three powers of HST orbital phase, and this would introduce a strong bias in the results for the albedo. However, with this reference star, we only need to detrend the data with the time of the exposures to achieve the same per-point scatter, therefore we can avoid most of the bias associated with detrending. Our final result is a 2{sigma} upper limit of 0.64 for the geometric albedo of HAT-P-1b between 577 and 947 nm.

  3. Exoplanet HAT-P-11b Secondary Transit Observations

    NASA Technical Reports Server (NTRS)

    Barry, Richard K., Jr.

    2010-01-01

    We have conducted secondary eclipse observations of exoplanet HAT--11b, recently discovered by proposal G. Bakos and his colleagues. HAT-P-11b is the smallest transiting extrasolar planet yet found and one of only two known exo-Neptunes. We have observed the system at 3.6 microns for a period of 22 hours centered on the anticipated secondary eclipse time, to detect the eclipse and determine its phase. Once the secondary eclipse is located through analysis of the data, we will make a more focused series of observations in both the 3.6 and 4.5 micron bands to fully characterize it. HAT-P-1lb has a period of 4.8878 days, radius of 0.422 RJ, mass of 0.081 MJ and semi major axis 0.053 AU. Measurements of the secondary eclipse will clarify two key issues; 1) the planetary brightness temperature and the nature of its atmosphere, and 2) the eccentricity of its orbit, with implications for its dynamical evolution. A precise determination of the orbit phase for the secondary eclipse will also be of great utility for Kepler observations of this system at visible wavelengths.

  4. The chloramphenicol acetyltransferase gene of Tn2424: a new breed of cat.

    PubMed

    Parent, R; Roy, P H

    1992-05-01

    We have sequenced the gene coding for the chloramphenicol acetyltransferase of Tn2424 of plasmid NR79. This gene codes for a protein of 23,500 Da, and the derived protein sequence is similar to those of the chromosomal chloramphenicol acetyltransferases of Agrobacterium tumefaciens and Pseudomonas aeruginosa and of unidentified open reading frames, which may encode chloramphenicol acetyltransferases, adjacent to the ermG macrolide-lincosamide-streptogramin resistance gene of Bacillus sphaericus and the vgb virginiamycin resistance gene of Staphylococcus aureus. Weaker similarity to the LacA (thiogalactoside acetyltransferase) and CysE (serine acetyltransferase) proteins of Escherichia coli and the NodL protein of Rhizobium leguminosarum is also observed. There is no significant similarity to any other chloramphenicol acetyltransferase genes, such as that of Tn9. The Tn2424 cat gene is part of a 4.5-kb region which also contains the aacA1a aminoglycoside-6'-N-acetyltransferase gene; Tn2424 is similar to Tn21 except for the presence of this region. Sequences flanking the cat gene are typical of those flanking other genes inserted into pVS1-derived "integrons" by a site-specific recombinational mechanism.

  5. Atomic resolution structure of human α-tubulin acetyltransferase bound to acetyl-CoA

    PubMed Central

    Taschner, Michael; Vetter, Melanie; Lorentzen, Esben

    2012-01-01

    Acetylation of lysine residues is an important posttranslational modification found in all domains of life. α-tubulin is specifically acetylated on lysine 40, a modification that serves to stabilize microtubules of axons and cilia. Whereas histone acetyltransferases have been extensively studied, there is no structural and mechanistic information available on α-tubulin acetyltransferases. Here, we present the structure of the human α-tubulin acetyltransferase catalytic domain bound to its cosubstrate acetyl-CoA at 1.05 Å resolution. Compared with other lysine acetyltransferases of known structure, α-tubulin acetyltransferase displays a relatively well-conserved cosubstrate binding pocket but is unique in its active site and putative α-tubulin binding site. Using acetylation assays with structure-guided mutants, we map residues important for acetyl-CoA binding, substrate binding, and catalysis. This analysis reveals a basic patch implicated in substrate binding and a conserved glutamine residue required for catalysis, demonstrating that the family of α-tubulin acetyltransferases uses a reaction mechanism different from other lysine acetyltransferases characterized to date. PMID:23071318

  6. Structure of the E. Coli Bifunctional GlmU Acetyltransferase Active Site with Substrates and Products

    SciTech Connect

    Olsen,L.; Vetting, M.; Roderick, S.

    2007-01-01

    The biosynthesis of UDP-GlcNAc in bacteria is carried out by GlmU, an essential bifunctional uridyltransferase that catalyzes the CoA-dependent acetylation of GlcN-1-PO{sub 4} to form GlcNAc-1-PO{sub 4} and its subsequent condensation with UTP to form pyrophosphate and UDP-GlcNAc. As a metabolite, UDP-GlcNAc is situated at a branch point leading to the biosynthesis of lipopolysaccharide and peptidoglycan. Consequently, GlmU is regarded as an important target for potential antibacterial agents. The crystal structure of the Escherichia coli GlmU acetyltransferase active site has been determined in complexes with acetyl-CoA, CoA/GlcN-1-PO{sub 4}, and desulpho-CoA/GlcNAc-1-PO{sub 4}. These structures reveal the enzyme groups responsible for binding the substrates. A superposition of these complex structures suggests that the 2-amino group of GlcN-1-PO{sub 4} is positioned in proximity to the acetyl-CoA to facilitate direct attack on its thioester by a ternary complex mechanism.

  7. Catalytic mechanism of bleomycin N-acetyltransferase proposed on the basis of its crystal structure.

    PubMed

    Oda, Kosuke; Matoba, Yasuyuki; Noda, Masafumi; Kumagai, Takanori; Sugiyama, Masanori

    2010-01-01

    Bleomycin (Bm) N-acetyltransferase, BAT, is a self-resistance determinant in Bm-producing Streptomyces verticillus ATCC15003. In our present study, we crystallized BAT under both a terrestrial and a microgravity environment in the International Space Station. In addition to substrate-free BAT, the crystal structures of BAT in a binary complex with CoA and in a ternary complex with Bm and CoA were determined. BAT forms a dimer structure via interaction of its C-terminal domains in the monomers. However, each N-terminal domain in the dimer is positioned without mutual interaction. The tunnel observed in the N-terminal domain of BAT has two entrances: one that adopts a wide funnel-like structure necessary to accommodate the metal-binding domain of Bm, and another narrow entrance that accommodates acetyl-CoA (AcCoA). A groove formed on the dimer interface of two BAT C-terminal domains accommodates the DNA-binding domain of Bm. In a ternary complex of BAT, BmA(2), and CoA, a thiol group of CoA is positioned near the primary amine of Bm at the midpoint of the tunnel. This proximity ensures efficient transfer of an acetyl group from AcCoA to the primary amine of Bm. Based on the BAT crystal structure and the enzymatic kinetic study, we propose that the catalytic mode of BAT takes an ordered-like mechanism. PMID:19889644

  8. Structure of the Hat Creek graben region: Implications for the structure of the Hat Creek graben and transfer of right-lateral shear from the Walker Lane north of Lassen Peak, northern California, from gravity and magnetic anomalies

    USGS Publications Warehouse

    Langenheim, Victoria; Jachens, Robert C.; Clynne, Michael A.; Muffler, L. J. Patrick

    2016-01-01

    Interpretation of magnetic and new gravity data provides constraints on the geometry of the Hat Creek Fault, the amount of right-lateral offset in the area between Mt. Shasta and Lassen Peak, and confirmation of the influence of pre-existing structure on Quaternary faulting. Neogene volcanic rocks coincide with short-wavelength magnetic anomalies of both normal and reversed polarity, whereas a markedly smoother magnetic field occurs over the Klamath Mountains and its Paleogene cover. Although the magnetic field over the Neogene volcanic rocks is complex, the Hat Creek Fault, which is one of the most prominent normal faults in the region and forms the eastern margin of the Hat Creek Valley, is marked by the eastern edge of a north-trending magnetic and gravity high 20-30 km long. Modeling of these anomalies indicates that the fault is a steeply dipping (~75-85°) structure. The spatial relationship of the fault as modeled by the potential-field data, the youngest strand of the fault, and relocated seismicity suggests that deformation continues to step westward across the valley, consistent with a component of right-lateral slip in an extensional environment. Filtered aeromagnetic data highlight a concealed magnetic body of Mesozoic or older age north of Hat Creek Valley. The body’s northwest margin strikes northeast and is linear over a distance of ~40 km. Within the resolution of the aeromagnetic data (1-2 km), we discern no right-lateral offset of this body. Furthermore, Quaternary faults change strike or appear to end, as if to avoid this concealed magnetic body and to pass along its southeast edge, suggesting that pre-existing crustal structure influenced younger faulting, as previously proposed based on gravity data.

  9. Structure of Mesorhizobium loti arylamine N-acetyltransferase 1

    SciTech Connect

    Holton, Simon J.; Dairou, Julien; Sandy, James; Rodrigues-Lima, Fernando; Dupret, Jean-Marie; Noble, Martin E. M.; Sim, Edith

    2005-01-01

    The crystal structure of a M. loti arylamine N-acetyltransferase 1 has been determined at 2.0 Å resolution. The arylamine N-acetyltransferase (NAT) enzymes have been found in a broad range of both eukaryotic and prokaryotic organisms. The NAT enzymes catalyse the transfer of an acetyl group from acetyl Co-enzyme A onto the terminal nitrogen of a range of arylamine, hydrazine and arylhydrazine compounds. Recently, several NAT structures have been reported from different prokaryotic sources including Salmonella typhimurium, Mycobacterium smegmatis and Pseudomonas aeruginosa. Bioinformatics analysis of the Mesorhizobium loti genome revealed two NAT paralogues, the first example of multiple NAT isoenzymes in a eubacterial organism. The M. loti NAT 1 enzyme was recombinantly expressed and purified for X-ray crystallographic studies. The purified enzyme was crystallized in 0.5 M Ca(OAc){sub 2}, 16% PEG 3350, 0.1 M Tris–HCl pH 8.5 using the sitting-drop vapour-diffusion method. A data set diffracting to 2.0 Å was collected from a single crystal at 100 K. The crystal belongs to the orthorhombic spacegroup P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 53.2, b = 97.3, c = 114.3 Å. The structure was refined to a final free-R factor of 24.8%. The structure reveals that despite low sequence homology, M. loti NAT1 shares the common fold as reported in previous NAT structures and exhibits the same catalytic triad of residues (Cys-His-Asp) in the active site.

  10. Fluctuations of hi-hat timing and dynamics in a virtuoso drum track of a popular music recording.

    PubMed

    Räsänen, Esa; Pulkkinen, Otto; Virtanen, Tuomas; Zollner, Manfred; Hennig, Holger

    2015-01-01

    Long-range correlated temporal fluctuations in the beats of musical rhythms are an inevitable consequence of human action. According to recent studies, such fluctuations also lead to a favored listening experience. The scaling laws of amplitude variations in rhythms, however, are widely unknown. Here we use highly sensitive onset detection and time series analysis to study the amplitude and temporal fluctuations of Jeff Porcaro's one-handed hi-hat pattern in "I Keep Forgettin'"-one of the most renowned 16th note patterns in modern drumming. We show that fluctuations of hi-hat amplitudes and interbeat intervals (times between hits) have clear long-range correlations and short-range anticorrelations separated by a characteristic time scale. In addition, we detect subtle features in Porcaro's drumming such as small drifts in the 16th note pulse and non-trivial periodic two-bar patterns in both hi-hat amplitudes and intervals. Through this investigation we introduce a step towards statistical studies of the 20th and 21st century music recordings in the framework of complex systems. Our analysis has direct applications to the development of drum machines and to drumming pedagogy. PMID:26039256

  11. Fluctuations of Hi-Hat Timing and Dynamics in a Virtuoso Drum Track of a Popular Music Recording

    PubMed Central

    Räsänen, Esa; Pulkkinen, Otto; Virtanen, Tuomas; Zollner, Manfred; Hennig, Holger

    2015-01-01

    Long-range correlated temporal fluctuations in the beats of musical rhythms are an inevitable consequence of human action. According to recent studies, such fluctuations also lead to a favored listening experience. The scaling laws of amplitude variations in rhythms, however, are widely unknown. Here we use highly sensitive onset detection and time series analysis to study the amplitude and temporal fluctuations of Jeff Porcaro’s one-handed hi-hat pattern in “I Keep Forgettin’”—one of the most renowned 16th note patterns in modern drumming. We show that fluctuations of hi-hat amplitudes and interbeat intervals (times between hits) have clear long-range correlations and short-range anticorrelations separated by a characteristic time scale. In addition, we detect subtle features in Porcaro’s drumming such as small drifts in the 16th note pulse and non-trivial periodic two-bar patterns in both hi-hat amplitudes and intervals. Through this investigation we introduce a step towards statistical studies of the 20th and 21st century music recordings in the framework of complex systems. Our analysis has direct applications to the development of drum machines and to drumming pedagogy. PMID:26039256

  12. HAT-P-44b, HAT-P-45b, AND HAT-P-46b: Three transiting hot Jupiters in possible multi-planet systems

    SciTech Connect

    Hartman, J. D.; Bakos, G. Á.; Bhatti, W.; Csubry, Z.; Penev, K.; De Val-Borro, M.; Torres, G.; Latham, D. W.; Bieryla, A.; Béky, B.; Noyes, R. W.; Esquerdo, G. A.; Kovács, G.; Johnson, J. A.; Howard, A. W.; Marcy, G. W.; Buchhave, L. A.; Fischer, D. A.; Everett, M.; Szklenár, T.; and others

    2014-06-01

    We report the discovery by the HATNet survey of three new transiting extrasolar planets orbiting moderately bright (V = 13.2, 12.8, and 11.9) stars. The planets have orbital periods of 4.3012, 3.1290, and 4.4631 days, masses of 0.35, 0.89, and 0.49 M {sub J}, and radii of 1.24, 1.43, and 1.28 R {sub J}. The stellar hosts have masses of 0.94, 1.26, and 1.28 M {sub ☉}. Each system shows significant systematic variations in its residual radial velocities, indicating the possible presence of additional components. Based on its Bayesian evidence, the preferred model for HAT-P-44 consists of two planets, including the transiting component, with the outer planet having a period of 872 days, eccentricity of 0.494 ± 0.081, and a minimum mass of 4.0 M {sub J}. Due to aliasing we cannot rule out alternative solutions for the outer planet having a period of 220 days or 438 days. For HAT-P-45, at present there is not enough data to justify the additional free parameters included in a multi-planet model; in this case a single-planet solution is preferred, but the required jitter of 22.5 ± 6.3 m s{sup –1} is relatively high for a star of this type. For HAT-P-46 the preferred solution includes a second planet having a period of 78 days and a minimum mass of 2.0 M {sub J}, however the preference for this model over a single-planet model is not very strong. While substantial uncertainties remain as to the presence and/or properties of the outer planetary companions in these systems, the inner transiting planets are well characterized with measured properties that are fairly robust against changes in the assumed models for the outer planets. Continued radial velocity monitoring is necessary to fully characterize these three planetary systems, the properties of which may have important implications for understanding the formation of hot Jupiters.

  13. mChIP-KAT-MS, a method to map protein interactions and acetylation sites for lysine acetyltransferases

    PubMed Central

    Mitchell, Leslie; Huard, Sylvain; Cotrut, Michael; Pourhanifeh-Lemeri, Roghayeh; Steunou, Anne-Lise; Hamza, Akil; Lambert, Jean-Philippe; Zhou, Hu; Ning, Zhibin; Basu, Amrita; Côté, Jacques; Figeys, Daniel A.; Baetz, Kristin

    2013-01-01

    Recent global proteomic and genomic studies have determined that lysine acetylation is a highly abundant posttranslational modification. The next challenge is connecting lysine acetyltransferases (KATs) to their cellular targets. We hypothesize that proteins that physically interact with KATs may not only predict the cellular function of the KATs but may be acetylation targets. We have developed a mass spectrometry-based method that generates a KAT protein interaction network from which we simultaneously identify both in vivo acetylation sites and in vitro acetylation sites. This modified chromatin-immunopurification coupled to an in vitro KAT assay with mass spectrometry (mChIP-KAT-MS) was applied to the Saccharomyces cerevisiae KAT nucleosome acetyltransferase of histone H4 (NuA4). Using mChIP-KAT-MS, we define the NuA4 interactome and in vitro-enriched acetylome, identifying over 70 previously undescribed physical interaction partners for the complex and over 150 acetyl lysine residues, of which 108 are NuA4-specific in vitro sites. Through this method we determine NuA4 acetylation of its own subunit Epl1 is a means of self-regulation and identify a unique link between NuA4 and the spindle pole body. Our work demonstrates that this methodology may serve as a valuable tool in connecting KATs with their cellular targets. PMID:23572591

  14. Structure and function of human Naa60 (NatF), a Golgi-localized bi-functional acetyltransferase.

    PubMed

    Chen, Ji-Yun; Liu, Liang; Cao, Chun-Ling; Li, Mei-Jun; Tan, Kemin; Yang, Xiaohan; Yun, Cai-Hong

    2016-01-01

    N-terminal acetylation (Nt-acetylation), carried out by N-terminal acetyltransferases (NATs), is a conserved and primary modification of nascent peptide chains. Naa60 (also named NatF) is a recently identified NAT found only in multicellular eukaryotes. This protein was shown to locate on the Golgi apparatus and mainly catalyze the Nt-acetylation of transmembrane proteins, and it also harbors lysine N(ε)-acetyltransferase (KAT) activity to catalyze the acetylation of lysine ε-amine. Here, we report the crystal structures of human Naa60 (hNaa60) in complex with Acetyl-Coenzyme A (Ac-CoA) or Coenzyme A (CoA). The hNaa60 protein contains an amphipathic helix following its GNAT domain that may contribute to Golgi localization of hNaa60, and the β7-β8 hairpin adopted different conformations in the hNaa60(1-242) and hNaa60(1-199) crystal structures. Remarkably, we found that the side-chain of Phe 34 can influence the position of the coenzyme, indicating a new regulatory mechanism involving enzyme, co-factor and substrates interactions. Moreover, structural comparison and biochemical studies indicated that Tyr 97 and His 138 are key residues for catalytic reaction and that a non-conserved β3-β4 long loop participates in the regulation of hNaa60 activity. PMID:27550639

  15. Structure and function of human Naa60 (NatF), a Golgi-localized bi-functional acetyltransferase

    PubMed Central

    Chen, Ji-Yun; Liu, Liang; Cao, Chun-Ling; Li, Mei-Jun; Tan, Kemin; Yang, Xiaohan; Yun, Cai-Hong

    2016-01-01

    N-terminal acetylation (Nt-acetylation), carried out by N-terminal acetyltransferases (NATs), is a conserved and primary modification of nascent peptide chains. Naa60 (also named NatF) is a recently identified NAT found only in multicellular eukaryotes. This protein was shown to locate on the Golgi apparatus and mainly catalyze the Nt-acetylation of transmembrane proteins, and it also harbors lysine Nε-acetyltransferase (KAT) activity to catalyze the acetylation of lysine ε-amine. Here, we report the crystal structures of human Naa60 (hNaa60) in complex with Acetyl-Coenzyme A (Ac-CoA) or Coenzyme A (CoA). The hNaa60 protein contains an amphipathic helix following its GNAT domain that may contribute to Golgi localization of hNaa60, and the β7-β8 hairpin adopted different conformations in the hNaa60(1-242) and hNaa60(1-199) crystal structures. Remarkably, we found that the side-chain of Phe 34 can influence the position of the coenzyme, indicating a new regulatory mechanism involving enzyme, co-factor and substrates interactions. Moreover, structural comparison and biochemical studies indicated that Tyr 97 and His 138 are key residues for catalytic reaction and that a non-conserved β3-β4 long loop participates in the regulation of hNaa60 activity. PMID:27550639

  16. Deletion of host histone acetyltransferases and deacetylases strongly affects Agrobacterium-mediated transformation of Saccharomyces cerevisiae.

    PubMed

    Soltani, Jalal; van Heusden, Gerard Paul H; Hooykaas, Paul J J

    2009-09-01

    Agrobacterium tumefaciens is a plant pathogen that genetically transforms plant cells by transferring a part of its Ti-plasmid, the T-strand, to the host cell. Under laboratory conditions, it can also transform cells from many different nonplant organisms, including the yeast Saccharomyces cerevisiae. Collections of S. cerevisiae strains have been developed with systematic deletion of all coding sequences. Here, we used these collections to identify genes involved in the Agrobacterium-mediated transformation (AMT) of S. cerevisiae. We found that deletion of genes (GCN5, NGG1, YAF9 and EAF7) encoding subunits of the SAGA, SLIK, ADA and NuA4 histone acetyltransferase complexes highly increased the efficiency of AMT, while deletion of genes (HDA2, HDA3 and HST4) encoding subunits of histone deacetylase complexes decreased AMT. These effects are specific for AMT as the efficiency of chemical (lithium acetate) transformation was not or only slightly affected by these deletions. Our data are consistent with a positive role of host histone deacetylation in AMT.

  17. Using Edward de Bono's six hats game to aid critical thinking and reflection in palliative care.

    PubMed

    Kenny, Lesley J

    2003-03-01

    This article describes the use of a creative thinking game to stimulate critical thinking and reflection with qualified health professionals undertaking palliative care education. The importance of reflective practice in nursing is well documented and numerous models are available. However, the author as a nurse teacher has found that many of these models are either too simple or too complex to be valuable in practice. The six hats game, devised by Edward de Bono, is a method that stimulates a variety of types of thinking and when used as a means of reflection helps students to become more critical about their practice. Using this game with a palliative care case study the author demonstrates how thinking more creatively about the patients' perceived needs and problems can assist in developing reflective skills. The article concludes with a discussion on some of the challenges of using this method and suggestions for future practical uses. PMID:12682572

  18. Using Edward de Bono's six hats game to aid critical thinking and reflection in palliative care.

    PubMed

    Kenny, Lesley J

    2003-03-01

    This article describes the use of a creative thinking game to stimulate critical thinking and reflection with qualified health professionals undertaking palliative care education. The importance of reflective practice in nursing is well documented and numerous models are available. However, the author as a nurse teacher has found that many of these models are either too simple or too complex to be valuable in practice. The six hats game, devised by Edward de Bono, is a method that stimulates a variety of types of thinking and when used as a means of reflection helps students to become more critical about their practice. Using this game with a palliative care case study the author demonstrates how thinking more creatively about the patients' perceived needs and problems can assist in developing reflective skills. The article concludes with a discussion on some of the challenges of using this method and suggestions for future practical uses.

  19. Preparation of Size-Controlled Hat-Stacked Carbon Nanofibers

    NASA Astrophysics Data System (ADS)

    Sato, Y.; Yokoyama, A.; Motomiya, K.; Jeyadevan, B.; Tohji, K.

    2007-03-01

    Hat-stacked carbon nanofibers (H-CNFs) were size-separated using a multi-step microfiltration process employing polycarbonate membrane filters with respective cylindrical pore diameters of 2.0, 1.2 and 0.4 μm after being cut and dispersed in distilled water using sonication in a mixture of concentrated H2SO4 and HNO3. The average length of separated H-CNFs was 2.4 μm, 1.2 μm and 0.6 μm, respectively.

  20. Application of Human-Autonomy Teaming (HAT) Patterns to Reduce Crew Operations (RCO)

    NASA Technical Reports Server (NTRS)

    Shively, R. Jay; Brandt, Summer L.; Lachter, Joel; Matessa, Mike; Sadler, Garrett; Battiste, Henri

    2011-01-01

    Unmanned aerial systems, advanced cockpits, and air traffic management are all seeing dramatic increases in automation. However, while automation may take on some tasks previously performed by humans, humans will still be required to remain in the system for the foreseeable future. The collaboration between humans and these increasingly autonomous systems will begin to resemble cooperation between teammates, rather than simple task allocation. It is critical to understand this human-autonomy teaming (HAT) to optimize these systems in the future. One methodology to understand HAT is by identifying recurring patterns of HAT that have similar characteristics and solutions. This paper applies a methodology for identifying HAT patterns to an advanced cockpit project.

  1. General survey of hAT transposon superfamily with highlight on hobo element in Drosophila.

    PubMed

    Ladevèze, Véronique; Chaminade, Nicole; Lemeunier, Françoise; Periquet, Georges; Aulard, Sylvie

    2012-09-01

    The hAT transposons, very abundant in all kingdoms, have a common evolutionary origin probably predating the plant-fungi-animal divergence. In this paper we present their general characteristics. Members of this superfamily belong to Class II transposable elements. hAT elements share transposase, short terminal inverted repeats and eight base-pairs duplication of genomic target. We focus on hAT elements in Drosophila, especially hobo. Its distribution, dynamics and impact on genome restructuring in laboratory strains as well as in natural populations are reported. Finally, the evolutionary history of hAT elements, their domestication and use as transgenic tools are discussed.

  2. Inhibition of aminoglycoside 6'-N-acetyltransferase type Ib-mediated amikacin resistance in Klebsiella pneumoniae by zinc and copper pyrithione.

    PubMed

    Chiem, Kevin; Fuentes, Brooke A; Lin, David L; Tran, Tung; Jackson, Alexis; Ramirez, Maria S; Tolmasky, Marcelo E

    2015-09-01

    The in vitro activity of the aminoglycoside 6'-N-acetyltransferase type Ib [AAC(6')-Ib] was inhibited by CuCl2 with a 50% inhibitory concentration (IC50) of 2.8 μM. The growth of an amikacin-resistant Klebsiella pneumoniae strain isolated from a neonate with meningitis was inhibited when amikacin was supplemented by the addition of Zn(2+) or Cu(2+) in complex with the ionophore pyrithione. Coordination complexes between cations and ionophores could be developed for their use, in combination with aminoglycosides, to treat resistant infections. PMID:26169410

  3. Inhibition of Aminoglycoside 6′-N-Acetyltransferase Type Ib-Mediated Amikacin Resistance in Klebsiella pneumoniae by Zinc and Copper Pyrithione

    PubMed Central

    Chiem, Kevin; Fuentes, Brooke A.; Lin, David L.; Tran, Tung; Jackson, Alexis; Ramirez, Maria S.

    2015-01-01

    The in vitro activity of the aminoglycoside 6′-N-acetyltransferase type Ib [AAC(6′)-Ib] was inhibited by CuCl2 with a 50% inhibitory concentration (IC50) of 2.8 μM. The growth of an amikacin-resistant Klebsiella pneumoniae strain isolated from a neonate with meningitis was inhibited when amikacin was supplemented by the addition of Zn2+ or Cu2+ in complex with the ionophore pyrithione. Coordination complexes between cations and ionophores could be developed for their use, in combination with aminoglycosides, to treat resistant infections. PMID:26169410

  4. The Role of Sas2, an Acetyltransferase Homologue of Saccharomyces Cerevisiae, in Silencing and Orc Function

    PubMed Central

    Ehrenhofer-Murray, A. E.; Rivier, D. H.; Rine, J.

    1997-01-01

    Silencing at the cryptic mating-type loci HML and HMR of Saccharomyces cerevisiae requires regulatory sites called silencers. Mutations in the Rap1 and Abf1 binding sites of the HMR-E silencer (HMRa-e**) cause the silencer to be nonfunctional, and hence, cause derepression of HMR. Here, we have isolated and characterized mutations in SAS2 as second-site suppressors of the silencing defect of HMRa-e**. Silencing conferred by the removal of SAS2 (sas2Δ) depended upon the integrity of the ARS consensus sequence of the HMR-E silencer, thus arguing for an involvement of the origin recognition complex (ORC). Restoration of silencing by sas2Δ required ORC2 and ORC5, but not SIR1 or RAP1. Furthermore, sas2Δ suppressed the temperature sensitivity, but not the silencing defect of orc2-1 and orc5-1. Moreover, sas2Δ had opposing effects on silencing of HML and HMR. The putative Sas2 protein bears similarities to known protein acetyltransferases. Several models for the role of Sas2 in silencing are discussed. PMID:9093847

  5. Structural Basis for Microcin C7 Inactivation by the MccE Acetyltransferase

    SciTech Connect

    Agarwal, Vinayak; Metlitskaya, Anastasiya; Severinov, Konstantin; Nair, Satish K.

    2015-10-15

    The antibiotic microcin C7 (McC) acts as a bacteriocide by inhibiting aspartyl-tRNA synthetase and stalling the protein translation machinery. McC is synthesized as a heptapeptide-nucleotide conjugate, which is processed by cellular peptidases within target strains to yield the biologically active compound. As unwanted processing of intact McC can result in self-toxicity, producing strains utilize multiple mechanisms for autoimmunity against processed McC. We have shown previously that the mccE gene within the biosynthetic cluster can inactivate processed McC by acetylating the antibiotic. Here, we present the characterization of this acetylation mechanism through biochemical and structural biological studies of the MccE acetyltransferase domain (MccE{sup AcTase}). We have also determined five crystal structures of the MccE-acetyl-CoA complex with bound substrates, inhibitor, and reaction product. The structural data reveal an unexpected mode of substrate recognition through p-stacking interactions similar to those found in cap-binding proteins and nucleotidyltransferases. These studies provide a rationale for the observation that MccE{sup AcTase} can detoxify a range of aminoacylnucleotides, including those that are structurally distinct from microcin C7.

  6. X-ray crystal structure of ornithine acetyltransferase from the clavulanic acid biosynthesis gene cluster.

    PubMed

    Elkins, Jonathan M; Kershaw, Nadia J; Schofield, Christopher J

    2005-01-15

    The orf6 gene from the clavulanic acid biosynthesis gene cluster encodes an OAT (ornithine acetyltransferase). Similar to other OATs the enzyme has been shown to catalyse the reversible transfer of an acetyl group from N-acetylornithine to glutamate. OATs are Ntn (N-terminal nucleophile) enzymes, but are distinct from the better-characterized Ntn hydrolase enzymes as they catalyse acetyl transfer rather than a hydrolysis reaction. In the present study, we describe the X-ray crystal structure of the OAT, corresponding to the orf6 gene product, to 2.8 A (1 A=0.1 nm) resolution. The larger domain of the structure consists of an alphabetabetaalpha sandwich as in the structures of Ntn hydrolase enzymes. However, differences in the connectivity reveal that OATs belong to a structural family different from that of other structurally characterized Ntn enzymes, with one exception: unexpectedly, the alphabetabetaalpha sandwich of ORF6 (where ORF stands for open reading frame) displays the same fold as an DmpA (L-aminopeptidase D-ala-esterase/amidase from Ochrobactrum anthropi), and so the OATs and DmpA form a new structural subfamily of Ntn enzymes. The structure reveals an alpha2beta2-heterotetrameric oligomerization state in which the intermolecular interface partly defines the active site. Models of the enzyme-substrate complexes suggest a probable oxyanion stabilization mechanism as well as providing insight into how the enzyme binds its two differently charged substrates. PMID:15352873

  7. Carnitine Acetyltransferase Mitigates Metabolic Inertia and Muscle Fatigue during Exercise.

    PubMed

    Seiler, Sarah E; Koves, Timothy R; Gooding, Jessica R; Wong, Kari E; Stevens, Robert D; Ilkayeva, Olga R; Wittmann, April H; DeBalsi, Karen L; Davies, Michael N; Lindeboom, Lucas; Schrauwen, Patrick; Schrauwen-Hinderling, Vera B; Muoio, Deborah M

    2015-07-01

    Acylcarnitine metabolites have gained attention as biomarkers of nutrient stress, but their physiological relevance and metabolic purpose remain poorly understood. Short-chain carnitine conjugates, including acetylcarnitine, derive from their corresponding acyl-CoA precursors via the action of carnitine acetyltransferase (CrAT), a bidirectional mitochondrial matrix enzyme. We show here that contractile activity reverses acetylcarnitine flux in muscle, from net production and efflux at rest to net uptake and consumption during exercise. Disruption of this switch in mice with muscle-specific CrAT deficiency resulted in acetyl-CoA deficit, perturbed energy charge, and diminished exercise tolerance, whereas acetylcarnitine supplementation produced opposite outcomes in a CrAT-dependent manner. Likewise, in exercise-trained compared to untrained humans, post-exercise phosphocreatine recovery rates were positively associated with CrAT activity and coincided with dramatic shifts in muscle acetylcarnitine dynamics. These findings show acetylcarnitine serves as a critical acetyl buffer for working muscles and provide insight into potential therapeutic strategies for combatting exercise intolerance. PMID:26154055

  8. Reconstruction of N-acetyltransferase 2 haplotypes using PHASE.

    PubMed

    Golka, Klaus; Blaszkewicz, Meinolf; Samimi, Mirabutaleb; Bolt, Hermann M; Selinski, Silvia

    2008-04-01

    The genotyping of N-acetyltransferase 2 (NAT2) by PCR/RFLP methods yields in a considerable percentage ambiguous results. To resolve this methodical problem a statistical approach was applied. PHASE v2.1.1, a statistical program for haplotype reconstruction was used to estimate haplotype pairs from NAT2 genotyping data, obtained by the analysis of seven single nucleotide polymorphisms relevant for Caucasians. In 1,011 out of 2,921 (35%) subjects the haplotype pairs were clearcut by the PCR/RFLP data only. For the majority of the data the applied method resulted in a multiplicity (2-4) of possible haplotype pairs. Haplotype reconstruction using PHASE v2.1.1 cleared this ambiguity in all cases but one, where an alternative haplotype pair was considered with a probability of 0.029. The estimation of the NAT2 haplotype is important because the assignment of the NAT2 alleles *12A, *12B, *12C or *13 to the rapid or slow NAT2 genotype has been discussed controversially. A clear assignment is indispensable in surveys of human bladder cancer caused by aromatic amine exposures. In conclusion, PHASE v2.1.1 software allowed an unambiguous haplotype reconstruction in 2,920 of 2,921 cases (>99.9%).

  9. A Bayesian Atmospheric Retrieval Performed on HAT-P-16b and WASP-11b/HAT-P-10b

    NASA Astrophysics Data System (ADS)

    McIntyre, Kathleen J.; Harrington, Joseph; Challener, Ryan C.; Hardin, Matthew Ryan; Bowman, Oliver Oliver; Foster, Andrew S. D.; Lenius, Maria; Hartman, Joel D.; Bakos, Gaspar; Blecic, Jasmina; Cubillos, Patricio; Ariston Hardy, Ryan; Cameron, Andrew

    2016-10-01

    HAT-P-16b is a hot (equilibrium temperature 1626 ± 40 K, assuming zero Bond albedo and efficient energy redistribution), 4.19 ± 0.09 Jupiter-mass exoplanet orbiting an F8 star every 2.775960 ± 0.000003 days (Buchhave et al 2010). WASP-11b/HAT-P-10b is a cooler (1020 ± 17 K), 0.487 ± 0.018 Jupiter-mass exoplanet orbiting a K3 star every 3.7224747 ± 0.0000065 days (Bakos et al. 2009, co-discovered by West et al. 2008). We observed secondary eclipses of both planets using the 3.6 μm and 4.5 μm channels of the Spitzer Space Telescope's Infrared Array Camera (program ID 60003). We applied our Bayesian Atmospheric Radiative Transfer (BART) code to constrain the temperature-pressure profiles and atmospheric molecular abundances of the two planets. Spitzer is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. This work was supported by NASA Planetary Atmospheres grant NNX12AI69G and NASA Astrophysics Data Analysis Program grant NNX13AF38G.

  10. HAT-P-18b AND HAT-P-19b: TWO LOW-DENSITY SATURN-MASS PLANETS TRANSITING METAL-RICH K STARS

    SciTech Connect

    Hartman, J. D.; Bakos, G. A.; Torres, G.; Noyes, R. W.; Latham, D. W.; Buchhave, L. A.; Fueresz, G.; Perumpilly, G.; Beky, B.; Stefanik, R. P.; Sasselov, D. D.; Esquerdo, G. A.; Everett, M.; Csubry, Z.; Sato, B.; Kovacs, G.; Fischer, D. A.; Howard, A. W.; Marcy, G. W.; Johnson, J. A.

    2011-01-01

    We report the discovery of two new transiting extrasolar planets. HAT-P-18b orbits the V = 12.759 K2 dwarf star GSC 2594-00646, with a period P = 5.508023 {+-} 0.000006 days, transit epoch T{sub c} = 2454715.02174 {+-} 0.00020 (BJD), and transit duration 0.1131 {+-} 0.0009 days. The host star has a mass of 0.77 {+-} 0.03 M{sub sun}, radius of 0.75 {+-} 0.04 R{sub sun}, effective temperature 4803 {+-} 80 K, and metallicity [Fe/H] = +0.10 {+-} 0.08. The planetary companion has a mass of 0.197 {+-} 0.013 M{sub J} and radius of 0.995 {+-} 0.052 R{sub J}, yielding a mean density of 0.25 {+-} 0.04 g cm{sup -3}. HAT-P-19b orbits the V = 12.901 K1 dwarf star GSC 2283-00589, with a period P = 4.008778 {+-} 0.000006 days, transit epoch T{sub c} = 2455091.53417 {+-} 0.00034 (BJD), and transit duration 0.1182 {+-} 0.0014 days. The host star has a mass of 0.84 {+-} 0.04 M{sub sun}, radius of 0.82 {+-} 0.05 R{sub sun}, effective temperature 4990 {+-} 130 K, and metallicity [Fe/H] = +0.23 {+-} 0.08. The planetary companion has a mass of 0.292 {+-} 0.018 M{sub J} and radius of 1.132 {+-} 0.072 R{sub J}, yielding a mean density of 0.25 {+-} 0.04 g cm{sup -3}. The radial velocity residuals for HAT-P-19 exhibit a linear trend in time, which indicates the presence of a third body in the system. Comparing these observations with theoretical models, we find that HAT-P-18b and HAT-P-19b are each consistent with a hydrogen-helium-dominated gas giant planet with negligible core mass. HAT-P-18b and HAT-P-19b join HAT-P-12b and WASP-21b in an emerging group of low-density Saturn-mass planets, with negligible inferred core masses. However, unlike HAT-P-12b and WASP-21b, both HAT-P-18b and HAT-P-19b orbit stars with super-solar metallicity. This calls into question the heretofore suggestive correlation between the inferred core mass and host star metallicity for Saturn-mass planets.

  11. Structural basis of cofactor-mediated stabilization and substrate recognition of the α-tubulin acetyltransferase αTAT1.

    PubMed

    Yuzawa, Satoru; Kamakura, Sachiko; Hayase, Junya; Sumimoto, Hideki

    2015-04-01

    The functions of microtubules are controlled in part by tubulin post-translational modification including acetylation of Lys⁴⁰ in α-tubulin. αTAT1 (α-tubulin acetyltransferase 1), an enzyme evolutionarily conserved among eukaryotes, has recently been identified as the major α-tubulin Lys⁴⁰ acetyltransferase, in which AcCoA (acetyl-CoA) serves as an acetyl group donor. The regulation and substrate recognition of this enzyme, however, have not been fully understood. In the present study, we show that AcCoA and CoA each form a stable complex with human αTAT1 to maintain the protein integrity both in vivo and in vitro. The invariant residues Arg¹³² and Ser¹⁶⁰ in αTAT1 participate in the stable interaction not only with AcCoA but also with CoA, which is supported by analysis of the present crystal structures of the αTAT1 catalytic domain in complex with CoA. Alanine substitution for Arg¹³² or Ser¹⁶⁰ leads to a drastic misfolding of the isolated αTAT1 catalytic domain in the absence of CoA and AcCoA but not in the presence of excess amounts of either cofactor. A mutant αTAT1 carrying the R132A or S160A substitution is degraded much faster than the wild-type protein when expressed in mammalian Madin-Darby canine kidney cells. Furthermore, alanine-scanning experiments using Lys⁴⁰-containing peptides reveal that α-tubulin Ser³⁸ is crucial for substrate recognition of αTAT1, whereas Asp³⁹, Ile⁴², the glycine stretch (amino acid residues 43-45) and Asp⁴⁶ are also involved. The requirement for substrate selection is totally different from that in various histone acetyltransferases, which appears to be consistent with the inability of αTAT1 to acetylate histones.

  12. Crystallization and preliminary X-ray diffraction analysis of the BRPF1 bromodomain in complex with its H2AK5ac and H4K12ac histone-peptide ligands

    PubMed Central

    Lubula, Mulu Y.; Poplawaski, Amanda; Glass, Karen C.

    2014-01-01

    The bromodomain-PHD finger protein 1 (BRPF1) is an essential subunit of the monocytic leukemia zinc (MOZ) histone acetyltransferase (HAT) complex and is required for complex formation and enzymatic activation. BRPF1 contains a structurally conserved bromodomain, which recognizes specific acetyllysine residues on histone proteins. The MOZ HAT plays a direct role in hematopoiesis, and deregulation of its activity is linked to the development of acute myeloid leukemia. However, the molecular mechanism of histone-ligand recognition by the BRPF1 bromodomain is currently unknown. The 117-amino-acid BRPF1 bromodomain was overexpressed in Escherichia coli and purified to homogeneity. Crystallization experiments of the BRPF1 bromodomain in complex with its H4K12ac and H2AK5ac histone ligands yielded crystals that were suitable for high-resolution X-ray diffraction analysis. The BRPF1 bromodomain–H4K12ac crystals belonged to the tetragonal space group P43212, with unit-cell parameters a = 75.1, b = 75.1, c = 86.3 Å, and diffracted to a resolution of 1.94 Å. The BRPF1 bromodomain–H2AK5ac crystals grew in the monoclinic space group P21, with unit-cell parameters a = 60.9, b = 55.6, c = 82.1 Å, β = 93.6°, and diffracted to a resolution of 1.80 Å. Complete data sets were collected from both crystal forms using synchrotron radiation on beamline X29 at Brookhaven National Laboratory (BNL). PMID:25286946

  13. Giant Paperclip Necklaces, Soup-Can Rings and Cherry-Pie Hats

    ERIC Educational Resources Information Center

    Winters, Laurel A.

    2011-01-01

    In this article, the author describes an art project inspired by the wearable sculpture art created by artist Marjorie Schick. Students used wallpaper paste and newspapers to create papier-mache for a mountain hat, a cherry-pie mask/hat, a "dress" shoe and a Cubistic mask. Cardboard was used in many of these things, in addition to being used as…

  14. Warm Spitzer Observations of Three Hot Exoplanets: XO-4b, HAT-P-6b, and HAT-P-8b

    NASA Astrophysics Data System (ADS)

    Todorov, Kamen O.; Deming, Drake; Knutson, Heather A.; Burrows, Adam; Sada, Pedro V.; Cowan, Nicolas B.; Agol, Eric; Desert, Jean-Michel; Fortney, Jonathan J.; Charbonneau, David; Laughlin, Gregory; Langton, Jonathan; Showman, Adam P.; Lewis, Nikole K.

    2012-02-01

    We analyze Warm Spitzer/Infrared Array Camera observations of the secondary eclipses of three planets, XO-4b, HAT-P-6b, and HAT-P-8b. We measure secondary eclipse amplitudes at 3.6 μm and 4.5 μm for each target. XO-4b exhibits a stronger eclipse depth at 4.5 μm than at 3.6 μm, which is consistent with the presence of a temperature inversion. HAT-P-8b shows a stronger eclipse amplitude at 3.6 μm and is best described by models without a temperature inversion. The eclipse depths of HAT-P-6b can be fitted with models with a small or no temperature inversion. We consider our results in the context of a postulated relationship between stellar activity and temperature inversion and a relationship between irradiation level and planet dayside temperature, as discussed by Knutson et al. and Cowan & Agol, respectively. Our results are consistent with these hypotheses, but do not significantly strengthen them. To measure accurate secondary eclipse central phases, we require accurate ephemerides. We obtain primary transit observations and supplement them with publicly available observations to update the orbital ephemerides of the three planets. Based on the secondary eclipse timing, we set upper boundaries for ecos (ω) for HAT-P-6b, HAT-P-8b, and XO-4b and find that the values are consistent with circular orbits.

  15. WARM SPITZER OBSERVATIONS OF THREE HOT EXOPLANETS: XO-4b, HAT-P-6b, AND HAT-P-8b

    SciTech Connect

    Todorov, Kamen O.; Deming, Drake; Knutson, Heather A.; Burrows, Adam; Sada, Pedro V.; Cowan, Nicolas B.; Agol, Eric; Desert, Jean-Michel; Charbonneau, David; Fortney, Jonathan J.; Laughlin, Gregory; Langton, Jonathan; Showman, Adam P.; Lewis, Nikole K.

    2012-02-10

    We analyze Warm Spitzer/Infrared Array Camera observations of the secondary eclipses of three planets, XO-4b, HAT-P-6b, and HAT-P-8b. We measure secondary eclipse amplitudes at 3.6 {mu}m and 4.5 {mu}m for each target. XO-4b exhibits a stronger eclipse depth at 4.5 {mu}m than at 3.6 {mu}m, which is consistent with the presence of a temperature inversion. HAT-P-8b shows a stronger eclipse amplitude at 3.6 {mu}m and is best described by models without a temperature inversion. The eclipse depths of HAT-P-6b can be fitted with models with a small or no temperature inversion. We consider our results in the context of a postulated relationship between stellar activity and temperature inversion and a relationship between irradiation level and planet dayside temperature, as discussed by Knutson et al. and Cowan and Agol, respectively. Our results are consistent with these hypotheses, but do not significantly strengthen them. To measure accurate secondary eclipse central phases, we require accurate ephemerides. We obtain primary transit observations and supplement them with publicly available observations to update the orbital ephemerides of the three planets. Based on the secondary eclipse timing, we set upper boundaries for ecos ({omega}) for HAT-P-6b, HAT-P-8b, and XO-4b and find that the values are consistent with circular orbits.

  16. Transit timing analysis in the HAT-P-32 system

    NASA Astrophysics Data System (ADS)

    Seeliger, M.; Dimitrov, D.; Kjurkchieva, D.; Mallonn, M.; Fernandez, M.; Kitze, M.; Casanova, V.; Maciejewski, G.; Ohlert, J. M.; Schmidt, J. G.; Pannicke, A.; Puchalski, D.; Göğüş, E.; Güver, T.; Bilir, S.; Ak, T.; Hohle, M. M.; Schmidt, T. O. B.; Errmann, R.; Jensen, E.; Cohen, D.; Marschall, L.; Saral, G.; Bernt, I.; Derman, E.; Gałan, C.; Neuhäuser, R.

    2014-06-01

    We present the results of 45 transit observations obtained for the transiting exoplanet HAT-P-32b. The transits have been observed using several telescopes mainly throughout the YETI (Young Exoplanet Transit Initiative) network. In 25 cases, complete transit light curves with a timing precision better than 1.4 min have been obtained. These light curves have been used to refine the system properties, namely inclination i, planet-to-star radius ratio Rp/Rs, and the ratio between the semimajor axis and the stellar radius a/Rs. First analyses by Hartman et al. suggests the existence of a second planet in the system, thus we tried to find an additional body using the transit timing variation (TTV) technique. Taking also the literature data points into account, we can explain all mid-transit times by refining the linear ephemeris by 21 ms. Thus, we can exclude TTV amplitudes of more than ˜1.5 min.

  17. One-Loop Calculations with BlackHat

    SciTech Connect

    Berger, C.F.; Bern, Z.; Dixon, L.J.; Cordero, F.Febres; Forde, D.; Ita, H.; Kosower, D.A.; Maitre, D.

    2008-08-01

    We describe BlackHat, an automated C++ program for calculating one-loop amplitudes, and the techniques used in its construction. These include the unitarity method and on-shell recursion. The other ingredients are compact analytic formulae for tree amplitudes for four-dimensional helicity states. The program computes amplitudes numerically, using analytic formula only for the tree amplitudes, the starting point for the recursion, and the loop integrals. We make use of recently developed on-shell methods for evaluating coefficients of loop integrals, in particular a discrete Fourier projection as a means of improving numerical stability. We illustrate the good numerical stability of this approach by computing six-, seven- and eight-gluon amplitudes in QCD and comparing against known analytic results.

  18. Friction pull plug welding: top hat plug design

    NASA Technical Reports Server (NTRS)

    Coletta, Edmond R. (Inventor); Cantrell, Mark A. (Inventor)

    2002-01-01

    Friction Pull Plug Welding is a solid state repair process for defects up to one inch in length, only requiring single sided tooling, or outside skin line (OSL), for preferred usage on flight hardware. The most prevalent defect associated with Friction Pull Plug Welding (FPPW) was a top side or inside skin line (ISL) lack of bonding. Bonding was not achieved at this location due to the reduction in both frictional heat and welding pressure between the plug and plate at the end of the weld. Thus, in order to eliminate the weld defects and increase the plug strength at the plug `top` a small `hat` section is added to the pull plug for added frictional heating and pressure.

  19. Friction pull plug welding: top hat plug design

    NASA Technical Reports Server (NTRS)

    Coletta, Edmond R. (Inventor); Cantrell, Mark A. (Inventor)

    2001-01-01

    Friction Pull Plug Welding is a solid state repair process for defects up to one inch in length, only requiring single sided tooling, or outside skin line (OSL), for preferred usage on flight hardware. The most prevalent defect associated with Friction Pull Plug Welding (FPPW) was a top side or inside skin line (ISL) lack of bonding. Bonding was not achieved at this location due to the reduction in both frictional heat and welding pressure between the plug and plate at the end of the weld. Thus, in order to eliminate the weld defects and increase the plug strength at the plug `top` a small `hat` section is added to the pull plug for added frictional heating and pressure.

  20. Supernova 1987 A - The nebular loops and 'Napoleon's Hat'

    NASA Astrophysics Data System (ADS)

    Wang, L.; Wampler, E. J.

    1992-08-01

    We discuss observations of the circumstellar environment of SN 1987A that were obtained between August 1989 and January 1992 at ESO's New Technology Telescope. We find that the angular dimensions of the two nebular loops (Wampler et al., 1990) have not changed during this period. Therefore these loops are confined to a small region. The expansion velocity of the loops is less than about 40 km/s if the loops expanded with a uniform velocity from a common origin. This structure and velocity is hard to reproduce with existing wind interaction models. Our observations further suggest that the Napoleon's Hat nebula does not originate from the general background LMC dust, but from a bow shock dust whose origins are closely related to the stellar winds from the progenitor star of SN 1987A.

  1. UMTRA Project Site Observational Work Plan, Mexican Hat, Utah

    SciTech Connect

    Not Available

    1994-09-01

    Surface cleanup activities at the Mexican Hat UMTRA processing site are nearing completion. Ground Water contamination at the Mexican Hat site is a result of uranium milling operations. The extent of residual process water has been identified, and it is limited to the uppermost aquifer in the vicinity of the site. Deeper aquifers are not affected because of an upward hydraulic gradient and the presence of a confining unit (the deeper aquifers are protected by hydrogeologic isolation). The uppermost unit is returning to its pre-milling, mainly unsaturated state. The unit that contains the contaminated water is not a ground water resource because it qualifies as Class III (limited use) based on limited yield. Ground water in the uppermost unit is currently not used and is not anticipated to be used as a ground water resource. The nearby San Juan River and a converted oil exploration well provide all of the water needs for the area. There are no current threats to human health or livestock; and, because the zone of contamination does not represent a ground water resource, none are anticipated in the future. There are, however, seeps where contaminated water is exposed at land surface. The seeps create potential exposure pathways for plants and wildlife. It is not known at this time if there is a risk to the environment. Additional investigations are needed and are described in this document to confirm the presence or absence of potential environmental risks. Additional hydrogeologic investigations are not required. The proposed ground water compliance strategy for the site is no remediation, because the ground water in the uppermost aquifer (which is also the zone of contamination) qualifies for supplemental standards based on Class III, limited yield, and because there are no threats to human health. Domestic and agricultural water is pumped from a deeper aquifer that is isolated from the contaminated zone.

  2. An Acetyltransferase Conferring Tolerance to Toxic Aromatic Amine Chemicals

    PubMed Central

    Martins, Marta; Rodrigues-Lima, Fernando; Dairou, Julien; Lamouri, Aazdine; Malagnac, Fabienne; Silar, Philippe; Dupret, Jean-Marie

    2009-01-01

    Aromatic amines (AA) are a major class of environmental pollutants that have been shown to have genotoxic and cytotoxic potentials toward most living organisms. Fungi are able to tolerate a diverse range of chemical compounds including certain AA and have long been used as models to understand general biological processes. Deciphering the mechanisms underlying this tolerance may improve our understanding of the adaptation of organisms to stressful environments and pave the way for novel pharmaceutical and/or biotechnological applications. We have identified and characterized two arylamine N-acetyltransferase (NAT) enzymes (PaNAT1 and PaNAT2) from the model fungus Podospora anserina that acetylate a wide range of AA. Targeted gene disruption experiments revealed that PaNAT2 was required for the growth and survival of the fungus in the presence of toxic AA. Functional studies using the knock-out strains and chemically acetylated AA indicated that tolerance of P. anserina to toxic AA was due to the N-acetylation of these chemicals by PaNAT2. Moreover, we provide proof-of-concept remediation experiments where P. anserina, through its PaNAT2 enzyme, is able to detoxify the highly toxic pesticide residue 3,4-dichloroaniline in experimentally contaminated soil samples. Overall, our data show that a single xenobiotic-metabolizing enzyme can mediate tolerance to a major class of pollutants in a eukaryotic species. These findings expand the understanding of the role of xenobiotic-metabolizing enzyme and in particular of NATs in the adaptation of organisms to their chemical environment and provide a basis for new systems for the bioremediation of contaminated soils. PMID:19416981

  3. Structural Studies on a Glucosamine/Glucosaminide N-Acetyltransferase.

    PubMed

    Dopkins, Brandon J; Tipton, Peter A; Thoden, James B; Holden, Hazel M

    2016-08-16

    Glucosamine/glucosaminide N-acetyltransferase or GlmA catalyzes the transfer of an acetyl group from acetyl CoA to the primary amino group of glucosamine. The enzyme from Clostridium acetobutylicum is thought to be involved in cell wall rescue. In addition to glucosamine, GlmA has been shown to function on di- and trisaccharides of glucosamine as well. Here we present a structural and kinetic analysis of the enzyme. For this investigation, eight structures were determined to resolutions of 2.0 Å or better. The overall three-dimensional fold of GlmA places it into the tandem GNAT superfamily. Each subunit of the dimer folds into two distinct domains which exhibit high three-dimensional structural similarity. Whereas both domains bind acetyl CoA, it is the C-terminal domain that is catalytically competent. On the basis of the various structures determined in this investigation, two amino acid residues were targeted for further study: Asp 287 and Tyr 297. Although their positions in the active site suggested that they may play key roles in catalysis by functioning as active site bases and acids, respectively, this was not borne out by characterization of the D287N and Y297F variants. The kinetic properties revealed that both residues were important for substrate binding but had no critical roles as acid/base catalysts. Kinetic analyses also indicated that GlmA follows an ordered mechanism with acetyl CoA binding first followed by glucosamine. The product N-acetylglucosamine is then released prior to CoA. The investigation described herein provides significantly new information on enzymes belonging to the tandem GNAT superfamily.

  4. Regulation of arylalkylamine N-acetyltransferase (AANAT) in the retina.

    PubMed

    Tosini, Gianluca; Chaurasia, Shyam S; Michael Iuvone, P

    2006-01-01

    Melatonin synthesis in retinal photoreceptors is under photic and circadian control and is regulated primarily by changes in the activity of arylalkylamine N-acetyltransferase (AANAT). Previous investigations demonstrated that Aanat transcripts are predominantly expressed in the photoreceptor cells. AANAT activity is high at night and low during the day, and illumination of the retina during the night induces rapid reduction in the activity of this enzyme. The enzyme is subject to both transcriptional and post-translational regulatory mechanisms. AANAT transcription is regulated directly by the circadian clock via the E-box present in the promoter region of the gene; the photic environment and circadian clock also influence AANAT transcription via cAMP-responsive elements. The stability of AANAT is regulated by cAMP, and light, which decreases cAMP levels in photoreceptor cells, results in rapid degradation of AANAT protein by proteasomal proteolysis. The circadian rhythm in the levels of Aanat mRNA in the rat retina persists after the suprachiasmatic nucleus (SCN) of the hypothalamus has been lesioned, indicative of its relative independence from the master clock in the brain. In non-mammalian vertebrates, the retinal clock controlling melatonin synthesis is in photoreceptor cells, but it has not been definitively localized in mammals. Several studies have also shown that dopamine plays an important role in the regulation of AANAT activity by acting via D2/D4-like receptors that are present on the photoreceptors. Finally, it is important to mention that AANAT, in addition to its role in melatonin synthesis, may play a detoxification role in the vertebrate retina by acetylating arylalkylamines that may react with retinaldehyde.

  5. Structural Studies on a Glucosamine/Glucosaminide N-Acetyltransferase.

    PubMed

    Dopkins, Brandon J; Tipton, Peter A; Thoden, James B; Holden, Hazel M

    2016-08-16

    Glucosamine/glucosaminide N-acetyltransferase or GlmA catalyzes the transfer of an acetyl group from acetyl CoA to the primary amino group of glucosamine. The enzyme from Clostridium acetobutylicum is thought to be involved in cell wall rescue. In addition to glucosamine, GlmA has been shown to function on di- and trisaccharides of glucosamine as well. Here we present a structural and kinetic analysis of the enzyme. For this investigation, eight structures were determined to resolutions of 2.0 Å or better. The overall three-dimensional fold of GlmA places it into the tandem GNAT superfamily. Each subunit of the dimer folds into two distinct domains which exhibit high three-dimensional structural similarity. Whereas both domains bind acetyl CoA, it is the C-terminal domain that is catalytically competent. On the basis of the various structures determined in this investigation, two amino acid residues were targeted for further study: Asp 287 and Tyr 297. Although their positions in the active site suggested that they may play key roles in catalysis by functioning as active site bases and acids, respectively, this was not borne out by characterization of the D287N and Y297F variants. The kinetic properties revealed that both residues were important for substrate binding but had no critical roles as acid/base catalysts. Kinetic analyses also indicated that GlmA follows an ordered mechanism with acetyl CoA binding first followed by glucosamine. The product N-acetylglucosamine is then released prior to CoA. The investigation described herein provides significantly new information on enzymes belonging to the tandem GNAT superfamily. PMID:27348258

  6. 30 CFR 75.1720-1 - Distinctively colored hard hats, or hard caps; identification for newly employed, inexperienced...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Distinctively colored hard hats, or hard caps... STANDARDS-UNDERGROUND COAL MINES Miscellaneous § 75.1720-1 Distinctively colored hard hats, or hard caps; identification for newly employed, inexperienced miners. Hard hats or hard caps distinctively different in...

  7. 30 CFR 77.1710-1 - Distinctively colored hard hats or hard caps; identification for newly employed, inexperienced...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Distinctively colored hard hats or hard caps... Distinctively colored hard hats or hard caps; identification for newly employed, inexperienced miners. Hard hats or hard caps distinctively different in color from those worn by experienced miners shall be worn...

  8. Environmental assessment of remedial action at the Mexican Hat uranium mill tailings site, Mexican Hat, Utah. [Contains glossary

    SciTech Connect

    Not Available

    1987-10-01

    This document assesses the environmental impacts of the proposed remedial action at the Mexican Hat uranium mill tailings site located on the Navajo Reservation in southern Utah. The site covers 235 acres and contains 69 acres of tailings and several of the original mill structures. Remedial action must be performed in accordance with standards and with the concurrence of the US Nuclear Regulatory Commission and the Navajo Nation. The proposed action is to stabilize the tailings within the present tailings site by consolidating the tailings and associated contaminated soils into a recontoured pile. A radon barrier of compacted earth would be constructed over the pile, and various erosion control measures would be taken to assure the long-term stability of the pile. The no action alternative is also assessed in this document. 240 refs., 12 figs., 20 tabs.

  9. In vitro activity assays for MYST histone acetyltransferases and adaptation for high-throughput inhibitor screening

    PubMed Central

    McCullough, Cheryl E.; Marmorstein, Ronen

    2016-01-01

    Lysine acetylation is a post-translational modification that is carried out by acetyltransferases. The MYST proteins form the largest and most diverse family of acetyltransferases, which regulate gene expression, DNA repair, and cell cycle homeostasis, among other activities, by acetylating both histone and non-histone proteins. This chapter will describe methods for the preparation and biochemical characterization of MYST family acetyltransferases, including protocols for the preparation of recombinant protein, enzyme assays for measuring steady state parameters and binding assays to measure cofactor and inhibitor binding. We also provide details on adapting these assays for high throughput screening for small molecule MYST inhibitors. This chapter seeks to prepare researchers for some hurdles that they may encounter when studying the MYST proteins so that there may be better opportunity to plan appropriate controls and obtain high quality data. PMID:27372752

  10. Chemical cross-linking and mass spectrometry to determine the subunit interaction network in a recombinant human SAGA HAT subcomplex.

    PubMed

    Nguyen-Huynh, Nha-Thi; Sharov, Grigory; Potel, Clément; Fichter, Pélagie; Trowitzsch, Simon; Berger, Imre; Lamour, Valérie; Schultz, Patrick; Potier, Noëlle; Leize-Wagner, Emmanuelle

    2015-08-01

    Understanding the way how proteins interact with each other to form transient or stable protein complexes is a key aspect in structural biology. In this study, we combined chemical cross-linking with mass spectrometry to determine the binding stoichiometry and map the protein-protein interaction network of a human SAGA HAT subcomplex. MALDI-MS equipped with high mass detection was used to follow the cross-linking reaction using bis[sulfosuccinimidyl] suberate (BS3) and confirm the heterotetrameric stoichiometry of the specific stabilized subcomplex. Cross-linking with isotopically labeled BS3 d0-d4 followed by trypsin digestion allowed the identification of intra- and intercross-linked peptides using two dedicated search engines: pLink and xQuest. The identified interlinked peptides suggest a strong network of interaction between GCN5, ADA2B and ADA3 subunits; SGF29 is interacting with GCN5 and ADA3 but not with ADA2B. These restraint data were combined to molecular modeling and a low-resolution interacting model for the human SAGA HAT subcomplex could be proposed, illustrating the potential of an integrative strategy using cross-linking and mass spectrometry for addressing the structural architecture of multiprotein complexes.

  11. Inhibition of lysine acetyltransferase KAT3B/p300 activity by a naturally occurring hydroxynaphthoquinone, plumbagin.

    PubMed

    Ravindra, Kodihalli C; Selvi, B Ruthrotha; Arif, Mohammed; Reddy, B A Ashok; Thanuja, Gali R; Agrawal, Shipra; Pradhan, Suman Kalyan; Nagashayana, Natesh; Dasgupta, Dipak; Kundu, Tapas K

    2009-09-01

    Lysine acetyltransferases (KATs), p300 (KAT3B), and its close homologue CREB-binding protein (KAT3A) are probably the most widely studied KATs with well documented roles in various cellular processes. Hence, the dysfunction of p300 may result in the dysregulation of gene expression leading to the manifestation of many disorders. The acetyltransferase activity of p300/CREB-binding protein is therefore considered as a target for new generation therapeutics. We describe here a natural compound, plumbagin (RTK1), isolated from Plumbago rosea root extract, that inhibits histone acetyltransferase activity potently in vivo. Interestingly, RTK1 specifically inhibits the p300-mediated acetylation of p53 but not the acetylation by another acetyltransferase, p300/CREB-binding protein -associated factor, PCAF, in vivo. RTK1 inhibits p300 histone acetyltransferase activity in a noncompetitive manner. Docking studies and site-directed mutagenesis of the p300 histone acetyltransferase domain suggest that a single hydroxyl group of RTK1 makes a hydrogen bond with the lysine 1358 residue of this domain. In agreement with this, we found that indeed the hydroxyl group-substituted plumbagin derivatives lost the acetyltransferase inhibitory activity. This study describes for the first time the chemical entity (hydroxyl group) required for the inhibition of acetyltransferase activity.

  12. Molecular Characterization of a Novel N-Acetyltransferase from Chryseobacterium sp.

    PubMed Central

    Yoshida, Kenji; Tanaka, Kosei; Yoshida, Ken-ichi

    2014-01-01

    N-Acetyltransferase from Chryseobacterium sp. strain 5-3B is an acetyl coenzyme A (acetyl-CoA)-dependent enzyme that catalyzes the enantioselective transfer of an acetyl group from acetyl-CoA to the amino group of l-2-phenylglycine to produce (2S)-2-acetylamino-2-phenylacetic acid. We purified the enzyme from strain 5-3B and deduced the N-terminal amino acid sequence. The gene, designated natA, was cloned with two other hypothetical protein genes; the three genes probably form a 2.5-kb operon. The deduced amino acid sequence of NatA showed high levels of identity to sequences of putative N-acetyltransferases of Chryseobacterium spp. but not to other known arylamine and arylalkylamine N-acetyltransferases. Phylogenetic analysis indicated that NatA forms a distinct lineage from known N-acetyltransferases. We heterologously expressed recombinant NatA (rNatA) in Escherichia coli and purified it. rNatA showed high activity for l-2-phenylglycine and its chloro- and hydroxyl-derivatives. The Km and Vmax values for l-2-phenylglycine were 0.145 ± 0.026 mM and 43.6 ± 2.39 μmol · min−1 · mg protein−1, respectively. The enzyme showed low activity for 5-aminosalicylic acid and 5-hydroxytryptamine, which are reported as good substrates of a known arylamine N-acetyltransferase and an arylalkylamine N-acetyltransferase. rNatA had a comparatively broad acyl donor specificity, transferring acyl groups to l-2-phenylglycine and producing the corresponding 2-acetylamino-2-phenylacetic acids (relative activity with acetyl donors acetyl-CoA, propanoyl-CoA, butanoyl-CoA, pentanoyl-CoA, and hexanoyl-CoA, 100:108:122:10:<1). PMID:24375143

  13. Dialing the Love Number of Hot Jupiter HAT-P-13b

    NASA Astrophysics Data System (ADS)

    Buhler, Peter

    2015-05-01

    HAT-P-13b is Jupiter-mass transiting planet in a 0.04 AU orbit around its host star. It has an outer companion, HAT-P-13c, with a minimum mass of 14.7 MJup in a highly eccentric 1.2 AU orbit. These two companions form an isolated dynamical system with their host star [1]. The nature of this system allows the two bodies to settle into a fixed eccentricity state where the eccentricity of HAT-P-13b is directly related to its oblateness as described by the Love number, k2 [2]. In order to constrain the eccentricity, and therefore k2, of HAT-P-13b, we use the Spitzer Space Telescope to measure the timing of its secondary eclipses at 3.6 and 4.5 μm. We then simultaneously fit our secondary eclipse data in conjunction with previously measured radial velocity and transit data. Finally, we apply the fact that, if the orbits of HAT-P-13b and HAT-P-13c are coplanar, then their apsides are aligned [3]. The apsidal orientation of HAT-P-13c is much better constrained because of its high eccentricity, which helps break the degeneracy between the eccentricity and apsidal orientation in interpreting the measured secondary eclipse time. Our analysis allows us to measure the eccentricity of HAT-P-13b’s orbit with a precision approximately ten times better than that of previously published values, in the coplanar case, and allows us to place the first meaningful constraints on the core mass of HAT-P-13b.[1] Becker & Batygin 2013, ApJ 778, 100 [2] Wu & Goldreich 2002, ApJ 564, 1024 [3] Batygin+ 2009, ApJ 704, L49

  14. HATS-11b AND HATS-12b: Two Transiting Hot Jupiters Orbiting Subsolar Metallicity Stars Selected for the K2 Campaign 7

    NASA Astrophysics Data System (ADS)

    Rabus, M.; Jordán, A.; Hartman, J. D.; Bakos, G. Á.; Espinoza, N.; Brahm, R.; Penev, K.; Ciceri, S.; Zhou, G.; Bayliss, D.; Mancini, L.; Bhatti, W.; de Val-Borro, M.; Csbury, Z.; Sato, B.; Tan, T.-G.; Henning, T.; Schmidt, B.; Bento, J.; Suc, V.; Noyes, R.; Lázár, J.; Papp, I.; Sári, P.

    2016-10-01

    We report the discovery of two transiting extrasolar planets from the HATSouth survey. HATS-11, a V = 14.1 G0-star shows a periodic 12.9 mmag dip in its light curve every 3.6192 days and a radial velocity variation consistent with a Keplerian orbit. HATS-11 has a mass of 1.000+/- 0.060 {M}⊙ , a radius of 1.444+/- 0.057 {R}⊙ and an effective temperature of 6060+/- 150 K, while its companion is a 0.85+/- 0.12 {M}{{J}}, 1.510+/- 0.078 {R}{{J}} planet in a circular orbit. HATS-12 shows a periodic 5.1 mmag flux decrease every 3.1428 days and Keplerian RV variations around a V = 12.8 F-star. HATS-12 has a mass of 1.489+/- 0.071 {M}⊙ , a radius of 2.21+/- 0.21 {R}⊙ , and an effective temperature of 6408+/- 75 K. For HATS-12b, our measurements indicate that this is a 2.38+/- 0.11 {M}{{J}}, 1.35+/- 0.17 {R}{{J}} planet in a circular orbit. Both host stars show subsolar metallicities of -0.390+/- 0.060 dex and -0.100+/- 0.040 dex, respectively, and are (slightly) evolved stars. In fact, HATS-11 is among the most metal-poor and, HATS-12, with a {log}{g}\\star of 3.923+/- 0.065, is among the most evolved stars hosting a hot-Jupiter planet. Importantly, HATS-11 and HATS-12 have been observed in long cadence by Kepler as part of K2 campaign 7 (EPIC216414930 and EPIC218131080 respectively). The HATSouth network is operated by a collaboration consisting of Princeton University (PU), the Max Planck Institute für Astronomie (MPIA), the Australian National University (ANU), and the Pontificia Universidad Católica de Chile (PUC). The station at Las Campanas Observatory (LCO) of the Carnegie Institute is operated by PU in conjunction with PUC, the station at the High Energy Spectroscopic Survey (H.E.S.S.) site is operated in conjunction with MPIA, and the station at Siding Spring Observatory (SSO) is operated jointly with ANU. Based in part on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. Based in part on

  15. Antioxidant Activity/Capacity Measurement. 2. Hydrogen Atom Transfer (HAT)-Based, Mixed-Mode (Electron Transfer (ET)/HAT), and Lipid Peroxidation Assays.

    PubMed

    Apak, Reşat; Özyürek, Mustafa; Güçlü, Kubilay; Çapanoğlu, Esra

    2016-02-10

    Measuring the antioxidant activity/capacity levels of food extracts and biological fluids is useful for determining the nutritional value of foodstuffs and for the diagnosis, treatment, and follow-up of numerous oxidative stress-related diseases. Biologically, antioxidants play their health-beneficial roles via transferring a hydrogen (H) atom or an electron (e(-)) to reactive species, thereby deactivating them. Antioxidant activity assays imitate this action; that is, antioxidants are measured by their H atom transfer (HAT) or e(-) transfer (ET) to probe molecules. Antioxidant activity/capacity can be monitored by a wide variety of assays with different mechanisms, including HAT, ET, and mixed-mode (ET/HAT) assays, generally without distinct boundaries between them. Understanding the principal mechanisms, advantages, and disadvantages of the measurement assays is important for proper selection of method for valid evaluation of antioxidant properties in desired applications. This work provides a general and up-to-date overview of HAT-based, mixed-mode (ET/HAT), and lipid peroxidation assays available for measuring antioxidant activity/capacity and the chemistry behind them, including a critical evaluation of their advantages and drawbacks.

  16. Functional Consequences and Structural Interpretation of Mutations of Human Choline Acetyltransferase

    PubMed Central

    Shen, Xin-Ming; Crawford, Thomas O.; Brengman, Joan; Acsadi, Gyula; Iannaconne, Susan; Karaca, Emin; Khoury, Chaouky; Mah, Jean K.; Edvardson, Shimon; Bajzer, Zeljko; Rodgers, David; Engel, Andrew G.

    2011-01-01

    Choline acetyltransferase (ChAT; EC 2.3.1.6) catalyzes synthesis of acetylcholine from acetyl-CoA and choline in cholinergic neurons. Mutations in CHAT (MIM # 118490) cause potentially lethal congenital myasthenic syndromes associated with episodic apnea (ChAT-CMS) (MIM # 254210). Here we analyze the functional consequences of 12 missense and 1 nonsense mutations of CHAT in 11 patients. Nine of the mutations are novel. We examine expression of the recombinant missense mutants in Bosc 23 cells, determine their kinetic properties and thermal stability, and interpret the functional effects of 11 mutations in the context of the atomic structural model of human ChAT. Five mutations (p.Trp421Ser, p.Ser498Pro, p.Thr553Asn, p.Ala557Thr, p.Ser572Trp) reduce enzyme expression to <50% of wild-type. Mutations with severe kinetic effects are located in the active-site tunnel (p.Met202Arg, p.Thr553Asn and p.Ala557Thr) or adjacent to the substrate binding site (p.Ser572Trp), or exert their effect allosterically (p.Trp421Ser and p.Ile689Ser). Two mutations with milder kinetic effects (p.Val136Met, p.Ala235Thr) are also predicted to act allosterically. One mutation (p.Thr608Asn) below the nucleotide binding site of CoA enhances dissociation of AcCoA from the enzyme-substrate complex. Two mutations introducing a proline residue into an α-helix (p.Ser498Pro and p.Ser704Pro) impair the thermal stability of ChAT. PMID:21786365

  17. X-ray crystal structure of ornithine acetyltransferase from the clavulanic acid biosynthesis gene cluster

    PubMed Central

    2004-01-01

    The orf6 gene from the clavulanic acid biosynthesis gene cluster encodes an OAT (ornithine acetyltransferase). Similar to other OATs the enzyme has been shown to catalyse the reversible transfer of an acetyl group from N-acetylornithine to glutamate. OATs are Ntn (N-terminal nucleophile) enzymes, but are distinct from the better-characterized Ntn hydrolase enzymes as they catalyse acetyl transfer rather than a hydrolysis reaction. In the present study, we describe the X-ray crystal structure of the OAT, corresponding to the orf6 gene product, to 2.8 Å (1 Å=0.1 nm) resolution. The larger domain of the structure consists of an αββα sandwich as in the structures of Ntn hydrolase enzymes. However, differences in the connectivity reveal that OATs belong to a structural family different from that of other structurally characterized Ntn enzymes, with one exception: unexpectedly, the αββα sandwich of ORF6 (where ORF stands for open reading frame) displays the same fold as an DmpA (L-aminopeptidase D-ala-esterase/amidase from Ochrobactrum anthropi), and so the OATs and DmpA form a new structural subfamily of Ntn enzymes. The structure reveals an α2β2-heterotetrameric oligomerization state in which the intermolecular interface partly defines the active site. Models of the enzyme–substrate complexes suggest a probable oxyanion stabilization mechanism as well as providing insight into how the enzyme binds its two differently charged substrates. PMID:15352873

  18. HAT-P-34b-HAT-P-37b: FOUR TRANSITING PLANETS MORE MASSIVE THAN JUPITER ORBITING MODERATELY BRIGHT STARS

    SciTech Connect

    Bakos, G. A.; Hartman, J. D.; Csubry, Z.; Penev, K.; Torres, G.; Beky, B.; Latham, D. W.; Bieryla, A.; Quinn, S.; Szklenar, T.; Esquerdo, G. A.; Noyes, R. W.; Buchhave, L. A.; Kovacs, G.; Shporer, A.; Fischer, D. A.; Johnson, J. A.; Howard, A. W.; Marcy, G. W.; Sato, B.; and others

    2012-07-15

    We report the discovery of four transiting extrasolar planets (HAT-P-34b-HAT-P-37b) with masses ranging from 1.05 to 3.33 M{sub J} and periods from 1.33 to 5.45 days. These planets orbit relatively bright F and G dwarf stars (from V = 10.16 to V = 13.2). Of particular interest is HAT-P-34b which is moderately massive (3.33 M{sub J}), has a high eccentricity of e = 0.441 {+-} 0.032 at a period of P = 5.452654 {+-} 0.000016 days, and shows hints of an outer component. The other three planets have properties that are typical of hot Jupiters.

  19. Two HAT-P-16b Spitzer Eclipse Observations

    NASA Astrophysics Data System (ADS)

    Hardin, Matthew R.; Harrington, J.; Fortney, J. J.; Foster, A. S.; Cubillos, P. E.; Hardy, R. A.; Bowman, O.; Blecic, J.; Hartman, J. D.; . Bakos, G.

    2013-10-01

    We report two Spitzer secondary eclipses of exoplanet HAT-P-16b. Discovered by Buchhave et al. (2010), this hot Jupiter is four times more massive than Jupiter and has a blackbody equilibrium temperature of 1626 K. We find a 3.6-micron eclipse depth of 0.129% ± 0.013% and a 4.5-micron eclipse depth of 0.210% ± 0.015%. These correspond to brightness temperatures of 1804 ± 71 K and 1946 ± 69 K respectively. We use the eclipse depths to constrain atmospheric models both with and without a thermal inversion, and find that those with a thermal inversion more closely match the data. We also refine the orbit of the planet, and confirm a small yet significant eccentricity of 0.0435 ± 0.0013. These observations are part of the Spitzer Exoplanet Target of Opportunity program. Spitzer is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA, which provided support for this work.

  20. Application of Human-Autonomy Teaming (HAT) Patterns to Reduce Crew Operations (RCO)

    NASA Technical Reports Server (NTRS)

    Shively, R. Jay; Brandt, Summer L.; Lachter, Joel; Matessa, Mike; Sadler, Garrett; Battiste, Henri

    2016-01-01

    Unmanned aerial systems, robotics, advanced cockpits, and air traffic management are all examples of domains that are seeing dramatic increases in automation. While automation may take on some tasks previously performed by humans, humans will still be required, for the foreseeable future, to remain in the system. The collaboration with humans and these increasingly autonomous systems will begin to resemble cooperation between teammates, rather than simple task allocation. It is critical to understand this human-autonomy teaming (HAT) to optimize these systems in the future. One methodology to understand HAT is by identifying recurring patterns of HAT that have similar characteristics and solutions. This paper applies a methodology for identifying HAT patterns to an advanced cockpit project.

  1. VizieR Online Data Catalog: HAT-P-36 and WASP-11/HAT-P-10 light curves (Mancini+, 2015)

    NASA Astrophysics Data System (ADS)

    Mancini, L.; Esposito, M.; Covino, E.; Raia, G.; Southworth, J.; Tregloan-Reed, J.; Biazzo, K.; Bonomo, A.; Desidera, S.; Lanza, A. F.; Maciejewski, G.; Poretti, E.; Sozzetti, A.; Borsa, F.; Bruni, I.; Ciceri, S.; Claudi, R.; Cosentino, R.; Gratton, R.; Martinez Fiorenzano, A. F.; Lodato, G.; Lorenzi, V.; Marzari, F.; Murabito, S.; Affer, L.; Bignamini, A.; Bedin, L. R.; Boccato, C.; Damasso, M.; Henning, T.; Maggio, A.; Micela, G.; Molinari, E.; Pagano, I.; Piotto, G.; Rainer, M.; Scandariato, G.; Smareglia, R.; Zanmar Sanchez; R.

    2015-06-01

    3 light curves of three transit events of the extrasolar planet HAT-P-36b and 3 light curves of two transit events of the extrasolar planet WASP-11b/HAT-P-10b. Three of the datasets were obtained using the Zeiss 1.23-m telescope (filter: Cousins I) at the Observatory of Calar Alto (Spain), two with the Cassini 1.52-m telescope (filter: Gunn r) at the Astronomical Observatory of Bologna in Loiano (Italy), and one with the IAC 80-cm telescope (filter: Cousins R) at the Teide Observatory on the island of Tenerife (Spain). (6 data files).

  2. Comparative investigation of the xenobiotic metabolizing arylamine N-acetyltransferase enzyme family among fungi

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Arylamine N-acetyltransferases (NATs) are xenobiotic metabolizing enzymes well-characterized in several bacteria and higher eukaryotes. The role of NATs in fungal biology has only recently been investigated. The NAT1 gene of Gibberella moniliformis was the first NAT cloned and characterized from fun...

  3. Genetic Variation at the N-acetyltransferase (NAT) Genes in Global Populations

    EPA Science Inventory

    Functional variability at the N-acetyltransferase (NAT) genes is associated with adverse drug reactions and cancer susceptibility in humans. Previous studies of small sets of ethnic groups have indicated that the NAT genes have high levels of amino acid variation that differ in f...

  4. The Atmospheric Circulation of Eccentric Hot Jupiter HAT-P-2b

    NASA Astrophysics Data System (ADS)

    Lewis, Nikole; Knutson, H.; Showman, A. P.; Fortney, J. J.; Agol, E.; Burrows, A.; Charbonneau, D.; Cowan, N. B.; Deming, D.; Desert, J.; Langton, J.; Laughlin, G.; Mighell, K.

    2011-09-01

    The Spitzer warm mission has already greatly expanded the field of exoplanet characterization with over 3000 hours of time dedicated to exoplanet observations. Observations of eclipsing systems with Spitzer are at the heart of these advances, as they allow us to move beyond simple mass and period estimates to determine planetary radius, dayside emission, and emission variations as a function of orbital phase. The eclipsing system HAT-P-2 is of special interest because the massive Jovian sized planet in this system is on a highly eccentric orbit (e=0.5171). Because HAT-P-2b's orbit is eccentric, the planet is subject to time variable heating and probable non-synchronous rotation. Circulation patterns that we expect to develop in HAT-P-2b's atmosphere will likely vary with both planetary local time and orbital phase. Here we present an analysis of two full-orbit light curves for the HAT-P-2 system obtained at 3.6 and 4.5 microns during the first two years of the Spitzer warm mission and discuss the observational constraints imposed on the atmospheric circulation of HAT-P-2b. Additionally, three-dimensional atmospheric models that incorporate realistic radiative transfer will be presented to further elucidate possible global scale circulations patterns present in the atmosphere of HAT-P-2b. Support for this work was provided by NASA.

  5. Supplement to the UMTRA Project water sampling and analysis plan, Mexican Hat, Utah

    SciTech Connect

    1995-09-01

    This water sampling and analysis plan (WSAP) supplement supports the regulatory and technical basis for water sampling at the Mexican Hat, Utah, Uranium Mill Tailings Remedial Action (UMTRA) Project site, as defined in the 1994 WSAP document for Mexican Hat (DOE, 1994). Further, the supplement serves to confirm our present understanding of the site relative to the hydrogeology and contaminant distribution as well as our intention to continue to use the sampling strategy as presented in the 1994 WSAP document for Mexican Hat. Ground water and surface water monitoring activities are derived from the US Environmental Protection Agency regulations in 40 CFR Part 192 (1991) and 60 FR 2854 (1995). Sampling procedures are guided by the UMTRA Project standard operating procedures (JEG, n.d.), the Technical Approach Document (DOE, 1989), and the most effective technical approach for the site. Additional site-specific documents relevant to the Mexican Hat site are the Mexican Hat Long-Term Surveillance Plan (currently in progress), and the Mexican Hat Site Observational Work Plan (currently in progress).

  6. Regulation of a Protein Acetyltransferase in Myxococcus xanthus by the Coenzyme NADP+

    PubMed Central

    Liu, Xin-Xin

    2015-01-01

    ABSTRACT NADP+ is a vital cofactor involved in a wide variety of activities, such as redox potential and cell death. Here, we show that NADP+ negatively regulates an acetyltransferase from Myxococcus xanthus, Mxan_3215 (MxKat), at physiologic concentrations. MxKat possesses an NAD(P)-binding domain fused to the Gcn5-type N-acetyltransferase (GNAT) domain. We used isothermal titration calorimetry (ITC) and a coupled enzyme assay to show that NADP+ bound to MxKat and that the binding had strong effects on enzyme activity. The Gly11 residue of MxKat was confirmed to play an important role in NADP+ binding using site-directed mutagenesis and circular dichroism spectrometry. In addition, using mass spectrometry, site-directed mutagenesis, and a coupling enzymatic assay, we demonstrated that MxKat acetylates acetyl coenzyme A (acetyl-CoA) synthetase (Mxan_2570) at Lys622 in response to changes in NADP+ concentration. Collectively, our results uncovered a mechanism of protein acetyltransferase regulation by the coenzyme NADP+ at physiological concentrations, suggesting a novel signaling pathway for the regulation of cellular protein acetylation. IMPORTANCE Microorganisms have developed various protein posttranslational modifications (PTMs), which enable cells to respond quickly to changes in the intracellular and extracellular milieus. This work provides the first biochemical characterization of a protein acetyltransferase (MxKat) that contains a fusion between a GNAT domain and NADP+-binding domain with Rossmann folds, and it demonstrates a novel signaling pathway for regulating cellular protein acetylation in M. xanthus. We found that NADP+ specifically binds to the Rossmann fold of MxKat and negatively regulates its acetyltransferase activity. This finding provides novel insight for connecting cellular metabolic status (NADP+ metabolism) with levels of protein acetylation, and it extends our understanding of the regulatory mechanisms underlying PTMs. PMID:26598367

  7. Warm Spitzer Secondary Transit Photometry of Hot Jupiters HAT-P-6b, HAT-P-8b and XO-4b

    NASA Astrophysics Data System (ADS)

    Todorov, Kamen 0.; Deming, D.; Knutson, H.; Burrows, A.; Sada, P.; Agol, E.; Desert, J.; Fortney, J. J.; Charbonneau, D.; Cowan, N. B.; Laughlin, G.; Langton, J.; Showman, A. P.; Lewis, N. K.

    2011-05-01

    An increasing number of transiting exoplanets have been observed at secondary eclipse. By measuring the depth of these eclipses at different wavelengths it is possible to distinguish between planets that have a temperature inversion in the upper layers of their atmospheres and ones that do not. We observed XO-4b, HAT-P-6b and HAT-P-8b during secondary eclipse with the IRAC instrument on Warm Spitzer at 3.6 and 4.5 microns. We compare the resulting eclipse depths to atmospheric models with and without temperature inversions, and thereby place constraints on the properties of their day-side atmospheres and heat redistribution efficiencies. The XO-4b and HAT-P-6b eclipse depths agree best with inverted models, while HAT-P-8b exhibits no temperature inversion. Knutson et al. (2010) hypothesized a correlation between lack of a temperature inversion and host star activity. Also, Cowan & Agol (2011), investigated the dependence between planetary effective temperatures, assuming no redistribution, and heat redistribution efficiency, finding that the hottest planets re-distribute heat inefficiently. We compare our planets with the Knutson and Cowan-Agol relations, and we find that they are consistent with the Knutson et al. activity hypothesis, but they are not hot enough to test the Cowan & Agol hypothesis.

  8. Remedial Action Plan for the codisposal and stabilization of the Monument Valley and Mexican Hat uranium mill tailings at Mexican Hat, Utah: Appendices C--E. Final report

    SciTech Connect

    1993-02-01

    This document provides appendices C, D, and E this Remedial Action Plan (RAP) which is a revision of the original Mexican Hat Remedial Action Plan and RAP Modification submitted in July 1988 and January 1989, respectively, along with updated design documents. Appendix C provide the Radiological Support Plan, Appendix D provides the Site Characterization, and Appendix E provides the Water Resources Protection Strategy.

  9. Dynamical Constraints on the Core Mass of Hot Jupiter HAT-P-13b

    NASA Astrophysics Data System (ADS)

    Buhler, Peter Benjamin; Knutson, Heather; Batygin, Konstantin; Fulton, Benjamin James; Burrows, Adam Seth; Fortney, Jonathan J.

    2016-01-01

    HAT-P-13b is a Jupiter-mass transiting exoplanet that has settled onto a stable, short-period, and mildly eccentric orbit due to the action of tidal dissipation and perturbations from a second, highly eccentric, outer companion. Due to the special orbital configuration of the HAT-P-13 system, the magnitude of HAT-P-13b's eccentricity is in part dictated by its Love number, i.e. the degree of central mass concentration in its interior. We can therefore directly constrain the fraction of HAT-P-13b's mass contained in its core by measuring its orbital eccentricity. This method offers considerable advantages over the standard approach of inferring core size based on mass and radius measurements alone. In this study we derive new constraints on the value of HAT-P-13b's eccentricity by observing two secondary eclipses of HAT-P-13b with the Infrared Array Camera on board the Spitzer Space Telescope. We fit the measured secondary eclipse times simultaneously with radial velocity measurements and find that the eccentricity of HAT-P-13b is 0.00696 ± 0.00096. We then use octupole-order secular perturbation theory to find that the corresponding Love number is 0.31 (+0.11, -0.05). Applying structural evolution models, we then find, with 68% confidence, that the core mass lies between 0-25 Earth masses, with a most likely value of the core mass of 11 Earth masses. This is the tightest constraint, to date, on the core mass of an exoplanet. We also compare the measured secondary eclipse depths, in the 3.6 and 4.5 micron bands, to the predictions of a suite of atmosphere models and find that the depths are best matched by models with a dayside temperature inversion and relatively efficient day-night circulation.

  10. Elongator subunit 3 positively regulates plant immunity through its histone acetyltransferase and radical S-adenosylmethionine domains

    PubMed Central

    2013-01-01

    Background Pathogen infection triggers a large-scale transcriptional reprogramming in plants, and the speed of this reprogramming affects the outcome of the infection. Our understanding of this process has significantly benefited from mutants that display either delayed or accelerated defense gene induction. In our previous work we demonstrated that the Arabidopsis Elongator complex subunit 2 (AtELP2) plays an important role in both basal immunity and effector-triggered immunity (ETI), and more recently showed that AtELP2 is involved in dynamic changes in histone acetylation and DNA methylation at several defense genes. However, the function of other Elongator subunits in plant immunity has not been characterized. Results In the same genetic screen used to identify Atelp2, we found another Elongator mutant, Atelp3-10, which mimics Atelp2 in that it exhibits a delay in defense gene induction following salicylic acid treatment or pathogen infection. Similarly to AtELP2, AtELP3 is required for basal immunity and ETI, but not for systemic acquired resistance (SAR). Furthermore, we demonstrate that both the histone acetyltransferase and radical S-adenosylmethionine domains of AtELP3 are essential for its function in plant immunity. Conclusion Our results indicate that the entire Elongator complex is involved in basal immunity and ETI, but not in SAR, and support that Elongator may play a role in facilitating the transcriptional induction of defense genes through alterations to their chromatin. PMID:23856002

  11. Nickel and cobalt resistance engineered in Escherichia coli by overexpression of serine acetyltransferase from the nickel hyperaccumulator plant Thlaspi goesingense.

    PubMed

    Freeman, John L; Persans, Michael W; Nieman, Ken; Salt, David E

    2005-12-01

    The overexpression of serine acetyltransferase from the Ni-hyperaccumulating plant Thlaspi goesingense causes enhanced nickel and cobalt resistance in Escherichia coli. Furthermore, overexpression of T. goesingense serine acetyltransferase results in enhanced sensitivity to cadmium and has no significant effect on resistance to zinc. Enhanced nickel resistance is directly related to the constitutive overactivation of sulfur assimilation and glutathione biosynthesis, driven by the overproduction of O-acetyl-L-serine, the product of serine acetyltransferase and a positive regulator of the cysteine regulon. Nickel in the serine acetyltransferase-overexpressing strains is not detoxified by coordination or precipitation with sulfur, suggesting that glutathione is involved in reducing the oxidative damage imposed by nickel. PMID:16332856

  12. Nickel and Cobalt Resistance Engineered in Escherichia coli by Overexpression of Serine Acetyltransferase from the Nickel Hyperaccumulator Plant Thlaspi goesingense

    PubMed Central

    Freeman, John L.; Persans, Michael W.; Nieman, Ken; Salt, David E.

    2005-01-01

    The overexpression of serine acetyltransferase from the Ni-hyperaccumulating plant Thlaspi goesingense causes enhanced nickel and cobalt resistance in Escherichia coli. Furthermore, overexpression of T. goesingense serine acetyltransferase results in enhanced sensitivity to cadmium and has no significant effect on resistance to zinc. Enhanced nickel resistance is directly related to the constitutive overactivation of sulfur assimilation and glutathione biosynthesis, driven by the overproduction of O-acetyl-l-serine, the product of serine acetyltransferase and a positive regulator of the cysteine regulon. Nickel in the serine acetyltransferase-overexpressing strains is not detoxified by coordination or precipitation with sulfur, suggesting that glutathione is involved in reducing the oxidative damage imposed by nickel. PMID:16332856

  13. System-wide Studies of N-Lysine Acetylation in Rhodopseudomonas palustris Reveals Substrate Specificity of Protein Acetyltransferases

    SciTech Connect

    Crosby, Heidi A; Pelletier, Dale A; Hurst, Gregory {Greg} B; Escalante-Semerena, Jorge C

    2012-01-01

    Background: Protein acetylation is widespread in prokaryotes. Results: Six new acyl-CoA synthetases whose activities are controlled by acetylation were identified, and their substrate preference established. A new protein acetyltransferase was also identified and its substrate specificity determined. Conclusion: Protein acetyltransferases acetylate a conserved lysine residue in protein substrates. Significance: The R. palustris Pat enzyme specifically acetylates AMP-forming acyl-CoA synthetases and regulates fatty acid metabolism.

  14. HAT3-mediated acetylation of PCNA precedes PCNA monoubiquitination following exposure to UV radiation in Leishmania donovani.

    PubMed

    Kumar, Devanand; Saha, Swati

    2015-06-23

    Histone modifications impact various processes. In examining histone acetyltranferase HAT3 of Leishmania donovani, we find elimination of HAT3 causes decreased cell viability due to defects in histone deposition, and aberrant cell cycle progression pattern. HAT3 associates with proliferating cell nuclear antigen (PCNA), helping load PCNA onto chromatin in proliferating cells. HAT3-nulls show heightened sensitivity to UV radiation. Following UV exposure, PCNA cycles off/on chromatin only in cells expressing HAT3. Inhibition of the ubiquitin-proteasome pathway prior to UV exposure allows accumulation of chromatin-bound PCNA, and reveals that HAT3-nulls are deficient in PCNA monoubiquitination as well as polyubiquitination. While poor monoubiquitination of PCNA may adversely affect translesion DNA synthesis-based repair processes, polyubiquitination deficiencies may result in continued retention of chromatin-bound PCNA, leading to genomic instability. On suppressing the proteasome pathway we also find that HAT3 mediates PCNA acetylation in response to UV. HAT3-mediated PCNA acetylation may serve as a flag for PCNA ubiquitination, thus aiding DNA repair. While PCNA acetylation has previously been linked to its degradation following UV exposure, this is the first report linking a HAT-mediated PCNA acetylation to PCNA monoubiquitination. These findings add a new dimension to our knowledge of the mechanisms regulating PCNA ubiquitination post-UV exposure in eukaryotes.

  15. HAT3-mediated acetylation of PCNA precedes PCNA monoubiquitination following exposure to UV radiation in Leishmania donovani

    PubMed Central

    Kumar, Devanand; Saha, Swati

    2015-01-01

    Histone modifications impact various processes. In examining histone acetyltranferase HAT3 of Leishmania donovani, we find elimination of HAT3 causes decreased cell viability due to defects in histone deposition, and aberrant cell cycle progression pattern. HAT3 associates with proliferating cell nuclear antigen (PCNA), helping load PCNA onto chromatin in proliferating cells. HAT3-nulls show heightened sensitivity to UV radiation. Following UV exposure, PCNA cycles off/on chromatin only in cells expressing HAT3. Inhibition of the ubiquitin-proteasome pathway prior to UV exposure allows accumulation of chromatin-bound PCNA, and reveals that HAT3-nulls are deficient in PCNA monoubiquitination as well as polyubiquitination. While poor monoubiquitination of PCNA may adversely affect translesion DNA synthesis-based repair processes, polyubiquitination deficiencies may result in continued retention of chromatin-bound PCNA, leading to genomic instability. On suppressing the proteasome pathway we also find that HAT3 mediates PCNA acetylation in response to UV. HAT3-mediated PCNA acetylation may serve as a flag for PCNA ubiquitination, thus aiding DNA repair. While PCNA acetylation has previously been linked to its degradation following UV exposure, this is the first report linking a HAT-mediated PCNA acetylation to PCNA monoubiquitination. These findings add a new dimension to our knowledge of the mechanisms regulating PCNA ubiquitination post-UV exposure in eukaryotes. PMID:25948582

  16. Phylogenetic and Functional Characterization of the hAT Transposon Superfamily

    PubMed Central

    Arensburger, Peter; Hice, Robert H.; Zhou, Liqin; Smith, Ryan C.; Tom, Ariane C.; Wright, Jennifer A.; Knapp, Joshua; O'Brochta, David A.; Craig, Nancy L.; Atkinson, Peter W.

    2011-01-01

    Transposons are found in virtually all organisms and play fundamental roles in genome evolution. They can also acquire new functions in the host organism and some have been developed as incisive genetic tools for transformation and mutagenesis. The hAT transposon superfamily contains members from the plant and animal kingdoms, some of which are active when introduced into new host organisms. We have identified two new active hAT transposons, AeBuster1, from the mosquito Aedes aegypti and TcBuster from the red flour beetle Tribolium castaneum. Activity of both transposons is illustrated by excision and transposition assays performed in Drosophila melanogaster and Ae. aegypti and by in vitro strand transfer assays. These two active insect transposons are more closely related to the Buster sequences identified in humans than they are to the previously identified active hAT transposons, Ac, Tam3, Tol2, hobo, and Hermes. We therefore reexamined the structural and functional relationships of hAT and hAT-like transposase sequences extracted from genome databases and found that the hAT superfamily is divided into at least two families. This division is supported by a difference in target-site selections generated by active transposons of each family. We name these families the Ac and Buster families after the first identified transposon or transposon-like sequence in each. We find that the recently discovered SPIN transposons of mammals are located within the family of Buster elements. PMID:21368277

  17. Analysis of HAT-P-2b Warm Spitzer Full Orbit Light Curve

    NASA Astrophysics Data System (ADS)

    Lewis, Nikole; Knuston, H.; Showman, A. P.; Fortney, J. J.; Agol, E.; Burrows, A.; Charbonneau, D.; Cowan, N. B.; Deming, D.; Desert, J.; Langton, J.; Laughlin, G.; Mighell, K. J.

    2011-05-01

    The Spitzer warm mission has already greatly expanded the field of exoplanet characterization with over 3000 hours of time dedicated to exoplanet observations. Observations of eclipsing systems with Spitzer are at the heart of these advances, as they allow us to move beyond simple mass and period estimates to determine planetary radius, dayside emission, and emission variations as a function of orbital phase. The eclipsing system HAT-P-2 is of special interest because the massive Jovian sized planet in this system is on a highly eccentric orbit (e=0.5171). Because HAT-P-2b's orbit is eccentric, the planet is subject to time variable heating and probable non-synchronous rotation. Circulation patterns that we expect to develop in HAT-P-2b's atmosphere will likely vary with both planetary local time and orbital phase. Here we present an analysis of a full orbit light curve from the HAT-P-2 system obtained during the most recent cycle of the Spitzer warm mission and discuss the constraints it imposes on the atmospheric circulation of HAT-P-2b. Support for this work was provided by NASA.

  18. Facilitated interaction between the pyruvate dehydrogenase kinase isoform 2 and the dihydrolipoyl acetyltransferase.

    PubMed

    Hiromasa, Yasuaki; Roche, Thomas E

    2003-09-01

    The dihydrolipoyl acetyltransferase (E2) has an enormous impact on pyruvate dehydrogenase kinase (PDK) phosphorylation of the pyruvate dehydrogenase (E1) component by acting as a mobile binding framework and in facilitating and mediating regulation of PDK activity. Analytical ultracentrifugation (AUC) studies established that the soluble PDK2 isoform is a stable dimer. The interaction of PDK2 with the lipoyl domains of E2 (L1, L2) and the E3-binding protein (L3) were characterized by AUC. PDK2 interacted very weakly with L2 (Kd approximately 175 microM for 2 L2/PDK2) but much tighter with dimeric glutathione S-transferase (GST)-L2 (Kd approximately 3 microM), supporting the importance of bifunctional binding. Reduction of lipoyl groups resulted in approximately 8-fold tighter binding of PDK2 to GST-L2red, which was approximately 300-fold tighter than binding of 2 L2red and also much tighter than binding by GST-L1red and GST-L3red. The E2 60-mer bound approximately 18 PDK2 dimers with a Kd similar to GST-L2. E2.E1 bound more PDK2 (approximately 27.6) than E2 with approximately 2-fold tighter affinity. Lipoate reduction fostered somewhat tighter binding at more sites by E2 and severalfold tighter binding at the majority of sites on E2.E1. ATP and ADP decreased the affinity of PDK2 for E2 by 3-5-fold and adenosine 5'-(beta,gamma-imino)triphosphate or phosphorylation of E1 similarly reduced PDK2 binding to E2.E1. Reversible bifunctional binding to L2 with the mandatory singly held transition fits the proposed "hand-over-hand" movement of a kinase dimer to access E1 without dissociating from the complex. The gain in binding interactions upon lipoate reduction likely aids reduction-engendered stimulation of PDK2 activity; loosening of binding as a result of adenine nucleotides and phosphorylation may instigate movement of lipoyl domain-held kinase to a new E1 substrate. PMID:12816949

  19. [Histochemistry and choline acetyltransferase in cat spinal cord and spinal ganglia].

    PubMed

    Motavkin, P A; Okhotin, V E

    1978-09-01

    Cytochemical activity of choline acetyltransferase has been studied in the pericaryon of motor neurons of the spinal enlargement and sensitive neurocytes of the intervertebral ganglia in the cat by means of Burt's method. It has been demonstrated that cytoplasm of all motor neurons positively reacts with acetyl KoA. According to the activity of choline acetyltransferase, four groups of neurons have been determined. In cerebrospinal ganglia, the enzyme is present in 58% of pseudounipolar cells, which seem to be cholinergic neurocytes. It has been stated that for all nonspecific reactions the presence of massive and dense residue in all the neurons, walls of small blood vessels and sometimes in astrocytes is a characteristic feature. PMID:718431

  20. Histone acetyltransferase Hbo1 destabilizes estrogen receptor α by ubiquitination and modulates proliferation of breast cancers.

    PubMed

    Iizuka, Masayoshi; Susa, Takao; Takahashi, Yoshihisa; Tamamori-Adachi, Mimi; Kajitani, Takashi; Okinaga, Hiroko; Fukusato, Toshio; Okazaki, Tomoki

    2013-12-01

    The estrogen receptor (ER) is a key molecule for growth of breast cancers. It has been a successful target for treatment of breast cancers. Elucidation of the ER expression mechanism is of importance for designing therapeutics for ER-positive breast cancers. However, the detailed mechanism of ER stability is still unclear. Here, we report that histone acetyltransferase Hbo1 promotes destabilization of estrogen receptor α (ERα) in breast cancers through lysine 48-linked ubiquitination. The acetyltransferase activity of Hbo1 is linked to its activity for ERα ubiquitination. Depletion of Hbo1 and anti-estrogen treatment displayed a potent growth suppression of breast cancer cell line. Hbo1 modulated transcription by ERα. Mutually exclusive expression of Hbo1 and ERα was observed in roughly half of the human breast tumors examined in the present study. Modulation of ER stability by Hbo1 in breast cancers may provide a novel therapeutic possibility.

  1. Mechanism of the lysosomal membrane enzyme acetyl coenzyme A: alpha-glucosaminide N-acetyltransferase

    SciTech Connect

    Bame, K.J.

    1986-01-01

    Acetyl-CoA:..cap alpha..-glucosaminide N-acetyltransferase is a lysosomal membrane enzyme, deficient in the genetic disease Sanfilippo C syndrome. The enzyme catalyzes the transfer of an acetyl group from cytoplasmic acetyl-CoA to terminal ..cap alpha..-glucosamine residues of heparan sulfate within the organelle. The reaction mechanism was examined using high purified lysosomal membranes from rat liver and human fibroblasts. The N-acetyltransferase reaction is optimal above pH 5.5 and a 2-3 fold stimulation of activity is observed in the presence of 0.1% taurodeoxycholate. Double reciprocal analysis and product inhibition studies indicate that the enzyme works by a Di-Iso Ping Pong Bi Bi mechanism. The binding of acetyl-CoA to the enzyme is measured by exchange label from (/sup 3/H)CoA to acetyl-CoA, and is optimal at pH's above 7.0. The acetyl-enzyme intermediate is formed by incubating membranes with (/sup 3/H)acetyl-CoA. The acetyl group can be transferred to glucosamine, forming (/sup 3/H)N-acetylglucosamine; the transfer is optimal between pH 4 and 5. Lysosomal membranes from Sanfilippo C fibroblasts confirm that these half reactions carried out by the N-acetyltransferase. The enzyme is inactivated by N-bromosuccinimide and diethylpyrocarbonate, indicating that a histidine is involved in the reaction. These results suggest that the histidine residue is at the active site of the enzyme. The properties of the N-acetyltransferase in the membrane, the characterization of the enzyme kinetics, the chemistry of a histidine mediated acetylation and the pH difference across the lysosomal membrane all support a transmembrane acetylation mechanism.

  2. Metabolism of triethylenetetramine and 1,12-diamino-3,6,9-triazadodecane by the spermidine/spermine-N(1)-acetyltransferase and thialysine acetyltransferase.

    PubMed

    Hyvönen, Mervi T; Weisell, Janne; Khomutov, Alex R; Alhonen, Leena; Vepsäläinen, Jouko; Keinänen, Tuomo A

    2013-01-01

    Triethylenetetramine (TETA; Syprine; Merck Rahway, NJ), a drug for Wilson's disease, is a copper chelator and a charge-deficient analog of polyamine spermidine. We recently showed that TETA is metabolized in vitro by polyamine catabolic enzyme spermidine/spermine-N(1)-acetyltransferase (SSAT1) and by thialysine acetyltransferase (SSAT2) to its monoacetylated derivative (MAT). The acetylation of TETA is increased in SSAT1-overexpressing mice compared with wild-type mice. However, SSAT1-deficient mice metabolize TETA at the same rate as the wild-type mice, indicating the existence of another N-acetylase respons 2ible for its metabolism in mice. Here, we show that siRNA-mediated knockdown of SSAT2 in HEPG2 cells and in primary hepatocytes from the SSAT1-deficient or wild-type mice reduced the metabolism of TETA to MAT. By contrast, 1,12-diamino-3,6,9-triazadodecane(SpmTrien), a charge-deficient spermine analog, was an extremely poor substrate of human recombinant SSAT2 and was metabolized by SSAT1 in HEPG2 cells and in wild-type primary hepatocytes. Thus, despite the similar structures of TETA and SpmTrien, SSAT2 is the main acetylator of TETA, whereas SpmTrien is primarily acetylated by SSAT1.

  3. Molecular cloning of rice serotonin N-acetyltransferase, the penultimate gene in plant melatonin biosynthesis.

    PubMed

    Kang, Kiyoon; Lee, Kyungjin; Park, Sangkyu; Byeon, Yeong; Back, Kyoungwhan

    2013-08-01

    Because of the absence of an arylalkylamine N-acetyltransferase (AANAT) homolog in the plant genome, the proposal was made that a GCN5-related N-acetyltransferase superfamily gene (GNAT) could be substituted for AANAT. To clone rice serotonin N-acetyltransferase (SNAT), we expressed 31 rice GNAT cDNAs in Escherichia coli and screened SNAT activity by measuring N-acetyltryptamine after application with 1 mm tryptamine. GNAT5 was shown to produce high levels of N-acetyltryptamine in E. coli, suggesting a possible rice SNAT. To confirm SNAT activity, the GNAT5 protein was purified through affinity purification from E. coli culture. The purified recombinant GNAT5 showed high SNAT enzyme activity catalyzing serotonin into N-acetylserotonin. The values for Km and Vmax were 385 μm and 282 pmol/min/mg protein, respectively. An in vitro enzyme assay of purified SNAT showed N-acetylserotonin formation to be proportional to enzyme concentration and time, with peak activity at pH 8.8. High substrate concentrations above 1 mm serotonin inhibited SNAT activity. Finally, the mRNA level of SNAT was higher in shoots than in roots, but it was expressed constitutively, unlike N-acetylserotonin methyltransferase (ASMT), the terminal enzyme in melatonin synthesis. These results suggest that ASMT rather than SNAT is the rate-limiting enzyme of melatonin biosynthesis in plants.

  4. Radiologic characterization of the Mexican Hat, Utah, uranium mill tailings remedial action site: Addendum D1

    SciTech Connect

    Ludlam, J.R.

    1985-01-01

    This radiologic characterization of the inactive uranium millsite at Mexican Hat, Utah, was conducted by Bendix Field Engineering Corporation for the US Department of Energy (DOE), Grand Junctions Project Office in response to and in accord with a Statement of Work prepared by the DOE Uranium Mill Tailings Remedial Action Project (UMTRAP) Technical Assistance Contractor, Jacobs Engineering Group, Inc. The objective of this project was to determine the horizontal and vertical extent of contamination that exceeds the US Environmental Protection Agency (EPA) standards at the Mexican Hat site. The data presented in this report are required for characterization of the areas adjacent to the Mexican Hat tailings piles and for the subsequent design of cleanup activities. Some on- pile sampling was required to determine the depth of the 15-pCi/g Ra- 226 interface in an area where wind and water erosion has taken place.

  5. [Usefulness of top-hat transform processing in whole body bone scintigraphy].

    PubMed

    Kita, Akinobu; Sugimoto, Katsuya; Tsuchida, Tatsurou; Kishimoto, Takahiro; Toi, Akiko; Shimada, Masato; Adachi, Toshiki

    2013-01-01

    To assess the usefulness of top-hat transform processing in whole body bone scintigraphy, five radiological technicians interpreted both original and top-hat processed images to determine the improvement of lesion detectability and interpretation time. For the evaluation of detectability, receiver operating characteristic (ROC) analysis was performed. The area under the curve (AUC) calculated from the ROC curve was improved in all observers (from 0.786 to 0.864 in average), although no significant difference was observed. However, the interpretation time was improved significantly (from 24.5 to 16.2 s in average). Top-hat transform processing in whole body bone scintigraphy is thought to be useful for the improvement of lesion detectability and interpretation time.

  6. HATS-1b: THE FIRST TRANSITING PLANET DISCOVERED BY THE HATSouth SURVEY

    SciTech Connect

    Penev, K.; Bakos, G. A.; Hartman, J. D.; Csubry, Z.; Bayliss, D.; Zhou, G.; Conroy, P.; Jordan, A.; Suc, V.; Rabus, M.; Brahm, R.; Espinoza, N.; Mohler, M.; Mancini, L.; Henning, T.; Nikolov, N.; Csak, B.; Beky, B.; Noyes, R. W.; Buchhave, L.; and others

    2013-01-01

    We report the discovery of HATS-1b, a transiting extrasolar planet orbiting the moderately bright V = 12.05 G dwarf star GSC 6652-00186, and the first planet discovered by HATSouth, a global network of autonomous wide-field telescopes. HATS-1b has a period of P Almost-Equal-To 3.4465 days, mass of M{sub p} Almost-Equal-To 1.86 M{sub J}, and radius of R{sub p} Almost-Equal-To 1.30 R{sub J}. The host star has a mass of 0.99 M{sub Sun} and radius of 1.04 R{sub Sun }. The discovery light curve of HATS-1b has near-continuous coverage over several multi-day timespans, demonstrating the power of using a global network of telescopes to discover transiting planets.

  7. Measurement of nonlinear index by a relay-imaged top-hat Z-scan technique

    SciTech Connect

    Shimada, T.; Kurnit, N.A.; Sheik-Bahae, M.

    1996-04-01

    Measurements of the nonlinear index of a number of optical materials of interest for the National Ignition Facility have been performed at 1,064 nm and 355 nm by a modified version of the ``top-hat`` technique and the results compared with the more standard gaussian-beam Z-scan technique. The top-hat technique has the advantages of higher sensitivity and smaller uncertainties introduced by beam-quality considerations. The authors have made what they feel to be an additional improvement by placing the defining aperture for the top hat at the front focal plane of the lens that focuses the beam into the sample and then reimaging the input aperture with a second lens onto a ccd camera. Reimaging eliminates diffraction fringes and provides a stationary image even for a wedged sample; recording the entire image permits minimization of spurious effects such as varying interference fringes.

  8. A Common Proper Motion Stellar Companion to HAT-P-7

    NASA Technical Reports Server (NTRS)

    Grady, Carol A.; McElwain, Michael W.; Narita, Norio; Takahashi, Yasuhiro H.; Kuzuhara, Masayuki; Hirano, Teruyuki; Suenaga, Takuya

    2012-01-01

    We report that HAT-P-7 has a common proper motion stellar companion. The companion is located at approx. 3.9 arcsec to the east and estimated as an M5.5V dwarf based on its colors. We also confirm the presence of the third companion, which was first reported by Winn et al. (2009), based on long-term radial velocity measurements. We revisit the migration mechanism of HAT-P-7b given the presence of those companions, and propose sequential Kozai migration as a likely scenario in this system. This scenario may explain the reason for an outlier in the discussion of the spin-orbit alignment timescale for HAT-P-7b by Albrecht et al. (2012).

  9. Structural analysis of PseH, the Campylobacter jejuni N-acetyltransferase involved in bacterial O-linked glycosylation

    SciTech Connect

    Song, Wan Seok; Nam, Mi Sun; Namgung, Byeol; Yoon, Sung-il

    2015-03-20

    Campylobacter jejuni is a bacterium that uses flagella for motility and causes worldwide acute gastroenteritis in humans. The C. jejuni N-acetyltransferase PseH (cjPseH) is responsible for the third step in flagellin O-linked glycosylation and plays a key role in flagellar formation and motility. cjPseH transfers an acetyl group from an acetyl donor, acetyl coenzyme A (AcCoA), to the amino group of UDP-4-amino-4,6-dideoxy-N-acetyl-β-L-altrosamine to produce UDP-2,4-diacetamido-2,4,6-trideoxy-β-L-altropyranose. To elucidate the catalytic mechanism of cjPseH, crystal structures of cjPseH alone and in complex with AcCoA were determined at 1.95 Å resolution. cjPseH folds into a single-domain structure of a central β-sheet decorated by four α-helices with two continuously connected grooves. A deep groove (groove-A) accommodates the AcCoA molecule. Interestingly, the acetyl end of AcCoA points toward an open space in a neighboring shallow groove (groove-S), which is occupied by extra electron density that potentially serves as a pseudosubstrate, suggesting that the groove-S may provide a substrate-binding site. Structure-based comparative analysis suggests that cjPseH utilizes a unique catalytic mechanism of acetylation that has not been observed in other glycosylation-associated acetyltransferases. Thus, our studies on cjPseH will provide valuable information for the design of new antibiotics to treat C. jejuni-induced gastroenteritis. - Highlights: • cjPseH adopts a single-domain structure of a central β-sheet decorated by α-helices. • cjPseH features two continuously connected grooves on the protein surface. • Acetyl coenzyme A (AcCoA) binds into a deep groove of cjPseH in an ‘L’ shape. • The acetyl end of AcCoA points to a wide groove, a potential substrate-binding site.

  10. Flexural fatigue life prediction of closed hat-section using materially nonlinear axial fatigue characteristics

    NASA Technical Reports Server (NTRS)

    Razzaq, Zia

    1989-01-01

    Straight or curved hat-section members are often used as structural stiffeners in aircraft. For instance, they are employed as stiffeners for the dorsal skin as well as in the aerial refueling adjacent area structure in F-106 aircraft. The flanges of the hat-section are connected to the aircraft skin. Thus, the portion of the skin closing the hat-section interacts with the section itself when resisting the stresses due to service loads. The flexural fatigue life of such a closed section is estimated using materially nonlinear axial fatigue characteristics. It should be recognized that when a structural shape is subjected to bending, the fatigue life at the neutral axis is infinity since the normal stresses are zero at that location. Conversely, the fatigue life at the extreme fibers where the normal bending stresses are maximum can be expected to be finite. Thus, different fatigue life estimates can be visualized at various distances from the neural axis. The problem becomes compounded further when significant portions away from the neutral axis are stressed into plastic range. A theoretical analysis of the closed hat-section subjected to flexural cyclic loading is first conducted. The axial fatigue characteristics together with the related axial fatigue life formula and its inverted form given by Manson and Muralidharan are adopted for an aluminum alloy used in aircraft construction. A closed-form expression for predicting the flexural fatigue life is then derived for the closed hat-section including materially nonlinear action. A computer program is written to conduct a study of the variables such as the thicknesses of the hat-section and the skin, and the type of alloy used. The study has provided a fundamental understanding of the flexural fatigue life characteristics of a practical structural component used in aircraft when materially nonlinear action is present.

  11. Cohesin recruits the Esco1 acetyltransferase genome wide to repress transcription and promote cohesion in somatic cells

    PubMed Central

    Rahman, Sadia; Jones, Mathew J. K.; Jallepalli, Prasad V.

    2015-01-01

    The cohesin complex links DNA molecules and plays key roles in the organization, expression, repair, and segregation of eukaryotic genomes. In vertebrates the Esco1 and Esco2 acetyltransferases both modify cohesin’s Smc3 subunit to establish sister chromatid cohesion during S phase, but differ in their N-terminal domains and expression during development and across the cell cycle. Here we show that Esco1 and Esco2 also differ dramatically in their interaction with chromatin, as Esco1 is recruited by cohesin to over 11,000 sites, whereas Esco2 is infrequently enriched at REST/NRSF target genes. Esco1’s colocalization with cohesin occurs throughout the cell cycle and depends on two short motifs (the A-box and B-box) present in and unique to all Esco1 orthologs. Deleting either motif led to the derepression of Esco1-proximal genes and functional uncoupling of cohesion from Smc3 acetylation. In contrast, other mutations that preserved Esco1’s recruitment separated its roles in cohesion establishment and gene silencing. We conclude that Esco1 uses cohesin as both a substrate and a scaffold for coordinating multiple chromatin-based transactions in somatic cells. PMID:26305936

  12. Cohesin recruits the Esco1 acetyltransferase genome wide to repress transcription and promote cohesion in somatic cells.

    PubMed

    Rahman, Sadia; Jones, Mathew J K; Jallepalli, Prasad V

    2015-09-01

    The cohesin complex links DNA molecules and plays key roles in the organization, expression, repair, and segregation of eukaryotic genomes. In vertebrates the Esco1 and Esco2 acetyltransferases both modify cohesin's Smc3 subunit to establish sister chromatid cohesion during S phase, but differ in their N-terminal domains and expression during development and across the cell cycle. Here we show that Esco1 and Esco2 also differ dramatically in their interaction with chromatin, as Esco1 is recruited by cohesin to over 11,000 sites, whereas Esco2 is infrequently enriched at REST/NRSF target genes. Esco1's colocalization with cohesin occurs throughout the cell cycle and depends on two short motifs (the A-box and B-box) present in and unique to all Esco1 orthologs. Deleting either motif led to the derepression of Esco1-proximal genes and functional uncoupling of cohesion from Smc3 acetylation. In contrast, other mutations that preserved Esco1's recruitment separated its roles in cohesion establishment and gene silencing. We conclude that Esco1 uses cohesin as both a substrate and a scaffold for coordinating multiple chromatin-based transactions in somatic cells. PMID:26305936

  13. Substrate-induced allosteric change in the quaternary structure of the spermidine N-acetyltransferase SpeG

    DOE PAGES

    Filippova, Ekaterina V.; Weigand, Steven J.; Osipiuk, Jerzy; Kiryukhina, Olga; Joachimiak, Andrzej; Anderson, Wayne F.

    2015-09-26

    The spermidine N-acetyltransferase SpeG is a dodecameric enzyme that catalyzes the transfer of an acetyl group from acetyl coenzyme A to polyamines such as spermidine and spermine. SpeG has an allosteric polyamine-binding site and acetylating polyamines regulate their intracellular concentrations. The structures of SpeG from Vibrio cholerae in complexes with polyamines and cofactor have been characterized earlier. Here, we present the dodecameric structure of SpeG from V. cholerae in a ligand-free form in three different conformational states: open, intermediate and closed. All structures were crystallized in C2 space group symmetry and contain six monomers in the asymmetric unit cell. Twomore » hexamers related by crystallographic 2-fold symmetry form the SpeG dodecamer. The open and intermediate states have a unique open dodecameric ring. This SpeG dodecamer is asymmetric except for the one 2-fold axis and is unlike any known dodecameric structure. Using a fluorescence thermal shift assay, size-exclusion chromatography with multi-angle light scattering, small-angle X-ray scattering analysis, negative-stain electron microscopy and structural analysis, we demonstrate that this unique open dodecameric state exists in solution. As a result, our combined results indicate that polyamines trigger conformational changes and induce the symmetric closed dodecameric state of the protein when they bind to their allosteric sites.« less

  14. Elongator Protein 3 (Elp3) Lysine Acetyltransferase Is a Tail-anchored Mitochondrial Protein in Toxoplasma gondii *

    PubMed Central

    Stilger, Krista L.; Sullivan, William J.

    2013-01-01

    Lysine acetylation has recently emerged as an important, widespread post-translational modification occurring on proteins that reside in multiple cellular compartments, including the mitochondria. However, no lysine acetyltransferase (KAT) has been definitively localized to this organelle to date. Here we describe the identification of an unusual homologue of Elp3 in early-branching protozoa in the phylum Apicomplexa. Elp3 is the catalytic subunit of the well-conserved transcription Elongator complex; however, Apicomplexa lack all other Elongator subunits, suggesting that the Elp3 in these organisms plays a role independent of transcription. Surprisingly, Elp3 in the parasites of this phylum, including Toxoplasma gondii (TgElp3), possesses a unique C-terminal transmembrane domain (TMD) that localizes the protein to the mitochondrion. As TgElp3 is devoid of known mitochondrial targeting signals, we used selective permeabilization studies to reveal that this KAT is oriented with its catalytic components facing the cytosol and its C-terminal TMD inserted into the outer mitochondrial membrane, consistent with a tail-anchored membrane protein. Elp3 trafficking to mitochondria is not exclusive to Toxoplasma as we also present evidence that a form of Elp3 localizes to these organelles in mammalian cells, supporting the idea that Elp3 performs novel functions across eukaryotes that are independent of transcriptional elongation. Importantly, we also present genetic studies that suggest TgElp3 is essential in Toxoplasma and must be positioned at the mitochondrial surface for parasite viability. PMID:23878194

  15. Substrate-induced allosteric change in the quaternary structure of the spermidine N-acetyltransferase SpeG

    SciTech Connect

    Filippova, Ekaterina V.; Weigand, Steven J.; Osipiuk, Jerzy; Kiryukhina, Olga; Joachimiak, Andrzej; Anderson, Wayne F.

    2015-09-26

    The spermidine N-acetyltransferase SpeG is a dodecameric enzyme that catalyzes the transfer of an acetyl group from acetyl coenzyme A to polyamines such as spermidine and spermine. SpeG has an allosteric polyamine-binding site and acetylating polyamines regulate their intracellular concentrations. The structures of SpeG from Vibrio cholerae in complexes with polyamines and cofactor have been characterized earlier. Here, we present the dodecameric structure of SpeG from V. cholerae in a ligand-free form in three different conformational states: open, intermediate and closed. All structures were crystallized in C2 space group symmetry and contain six monomers in the asymmetric unit cell. Two hexamers related by crystallographic 2-fold symmetry form the SpeG dodecamer. The open and intermediate states have a unique open dodecameric ring. This SpeG dodecamer is asymmetric except for the one 2-fold axis and is unlike any known dodecameric structure. Using a fluorescence thermal shift assay, size-exclusion chromatography with multi-angle light scattering, small-angle X-ray scattering analysis, negative-stain electron microscopy and structural analysis, we demonstrate that this unique open dodecameric state exists in solution. As a result, our combined results indicate that polyamines trigger conformational changes and induce the symmetric closed dodecameric state of the protein when they bind to their allosteric sites.

  16. Virtual Screening of Phytochemicals to Novel Target (HAT) Rtt109 in Pneumocystis Jirovecii using Bioinformatics Tools

    PubMed Central

    Adithavarman, Abhinand Ponneri; Dakshinamoorthi, Anusha; David, Darling Chellathai; Ragunath, Padmavathi Kannan

    2016-01-01

    Introduction Pneumocystis jirovecii is a fungus that causes Pneumocystis pneumonia in HIV and other immunosuppressed patients. Treatment of Pneumocystis pneumonia with the currently available antifungals is challenging and associated with considerable adverse effects. There is a need to develop drugs against novel targets with minimal human toxicities. Histone Acetyl Transferase (HAT) Rtt109 is a potential therapeutic target in Pneumocystis jirovecii species. HAT is linked to transcription and is required to acetylate conserved lysine residues on histone proteins by transferring an acetyl group from acetyl CoA to form e-N-acetyl lysine. Therefore, inhibitors of HAT can be useful therapeutic options in Pneumocystis pneumonia. Aim To screen phytochemicals against (HAT) Rtt109 using bioinformatics tool. Materials and Methods The tertiary structure of Pneumocystis jirovecii (HAT) Rtt109 was modeled by Homology Modeling. The ideal template for modeling was obtained by performing Psi BLAST of the protein sequence. Rtt109-AcCoA/Vps75 protein from Saccharomyces cerevisiae (PDB structure 3Q35) was chosen as the template. The target protein was modeled using Swiss Modeler and validated using Ramachandran plot and Errat 2. Comprehensive text mining was performed to identify phytochemical compounds with antipneumonia and fungicidal properties and these compounds were filtered based on Lipinski’s Rule of 5. The chosen compounds were subjected to virtual screening against the target protein (HAT) Rtt109 using Molegro Virtual Docker 4.5. Osiris Property Explorer and Open Tox Server were used to predict ADME-T properties of the chosen phytochemicals. Results Tertiary structure model of HAT Rtt 109 had a ProSA score of -6.57 and Errat 2 score of 87.34. Structure validation analysis by Ramachandran plot for the model revealed 97% of amino acids were in the favoured region. Of all the phytochemicals subjected to virtual screening against the target protein (HAT) Rtt109, baicalin

  17. VizieR Online Data Catalog: Transit of HAT-P-5 (Southworth+, 2012)

    NASA Astrophysics Data System (ADS)

    Southworth, J.; Mancini, L.; Maxted, P. F. L.; Bruni, I.; Tregloan-Reed, J.; Barbieri, M.; Ruocco, N.; Wheatley, P. J.

    2013-01-01

    We observed one full transit of HAT-P-5 on the night of 2010 August 23, using the 2.2-m telescope and BUSCA imager at Calar Alto Astronomical Observatory. BUSCA uses dichroics to split the incoming light into four wavelength intervals, which traverse different arms of the instrument and are incident on to four CCDs. We observed two transits of HAT-P-5 in 2011 May and July, using BFOSC mounted on the 1.52-m G.D. Cassini Telescope at Loiano Observatory, Italy. (2 data files).

  18. Red Hat Enterprise Virtualization - KVM-based infrastructure services at BNL

    SciTech Connect

    Cortijo, D.

    2011-06-14

    Over the past 18 months, BNL has moved a large percentage of its Linux-based servers and services into a Red Hat Enterprise Virtualization (RHEV) environment. This presentation will address our approach to virtualization, critical decision points, and a discussion of our implementation. Specific topics will include an overview of hardware and software requirements, networking, and storage; discussion of the decision of Red Hat solution over competing products (VMWare, Xen, etc); details on some of the features of RHEV - both current and on their roadmap; Review of performance and reliability gains since deployment completion; path forward for RHEV at BNL and caveats and potential problems.

  19. Mercury in Connecticut and Long Island Sound: Impact of Historic Hatting Industries

    NASA Astrophysics Data System (ADS)

    Bronsther, R.; Welsh, P.; Varekamp, J. C.

    2004-05-01

    Wetlands in the northeastern region of the U.S.A. are mildly contaminated with Hg as a result of atmospheric deposition, with modern soil concentrations of several 100 ppb Hg. Connecticut was once considered the hat manufacturing capital of the world. A solution of Hg-nitrate was used in the felting process, and old hat factory sites have become point sources of Hg contamination. Surface soils in the former hatting town of Danbury have Hg soil concentration levels that well exceed Connecticut's residential soil remediation standard of 20 ppm. Sediments from the Still River, a small waterway that runs through Danbury and discharges into the Housatonic River, show locally Hg concentrations of several tens of ppm, Cores taken from marsh islands in the Housatonic River show elevated Hg concentrations as well, up to 5 ppm Hg. Sites in Norwalk, another former hatting town, and along the Norwalk River also show values of more than 5 ppm Hg. The old hat factory sites in both towns clearly serve as point sources for Hg contamination downstream. Cores taken from marshes in the Connecticut River, which drains no former hatting towns, had much lower Hg concentrations (up to ~500 ppb Hg). The Five Mile River marsh near Darien, CT has lower peak values than found in the sediments of the Housatonic and Norwalk River cores, but still slightly elevated (800 ppb Hg). The Hg from the hat-site point sources is ultimately entering Long Island Sound. High Hg levels are found in western Long Island Sound compared to the eastern section (up to 800 ppb Hg), which is the result of fine-grained sediment transport westwards in the Sound, and the release of Hg-bearing effluent from waste water treatment plants of New York City. The contaminated sediment output from the Housatonic and Norwalk Rivers also contributes to the elevated Hg levels in the western Sound and possibly the Five Mile River marshes. Cores taken from the Housatonic River and western Long Island Sound show also peak Hg

  20. Remedial Action Plan for the codisposal and stabilization of the Monument Valley and Mexican Hat uranium mill tailings at Mexican Hat, Utah

    SciTech Connect

    1993-02-01

    This document is a revision of the original Mexiacan Hat Remedial Action Plan (RAP) and RAP Modification submitted in July 1988 and January 1989, respectively, along with updated design documents. This RAP has been developed to serve a two-fold purpose. It presents the activities proposed by the Department of Energy (DOE) to accomplish long-term stabilization and control of the residual radioactive materials (RRM) from Monument Valley, Arizona, and Mexican Hat, Utah, at the Mexican Hat disposal site. It also serves to document the concurrence of both the Navajo Nation and the Nuclear Regulatory Commission (NRC) in the remedial action. This agreement, upon execution by DOE and the Navajo Nation and concurrence by the NRC, becomes Appendix B of the Cooperative Agreement. This document has been structured to provide a comprehensive understanding of the remedial action proposed for the Monument Valley and Mexican Hat sites. It includes specific design and construction requirements for the remedial action. Pertinent information and data are included with reference given to the supporting documents. Section 2.0 presents the EPA standards, including a discussion of their objectives. Section 3. 0 summarizes the present site characteristics and provides a definition of site-specific problems. Section 4.0 is the site design for the proposed action. Section 5.0 presents the water resources protection strategy. Section 6.0 summarizes the plan for ensuring health and safety protection for the surrounding community and the on- site workers. Section 7.0 lists the responsibilities of the project participants. Section 8.0 describes the features of the long-term surveillance and maintenance plan.

  1. Effect of Increased Yeast Alcohol Acetyltransferase Activity on Flavor Profiles of Wine and Distillates

    PubMed Central

    Lilly, M.; Lambrechts, M. G.; Pretorius, I. S.

    2000-01-01

    The distinctive flavor of wine, brandy, and other grape-derived alcoholic beverages is affected by many compounds, including esters produced during alcoholic fermentation. The characteristic fruity odors of the fermentation bouquet are primarily due to a mixture of hexyl acetate, ethyl caproate (apple-like aroma), iso-amyl acetate (banana-like aroma), ethyl caprylate (apple-like aroma), and 2-phenylethyl acetate (fruity, flowery flavor with a honey note). The objective of this study was to investigate the feasibility of improving the aroma of wine and distillates by overexpressing one of the endogenous yeast genes that controls acetate ester production during fermentation. The synthesis of acetate esters by the wine yeast Saccharomyces cerevisiae during fermentation is ascribed to at least three acetyltransferase activities, namely, alcohol acetyltransferase (AAT), ethanol acetyltransferase, and iso-amyl AAT. To investigate the effect of increased AAT activity on the sensory quality of Chenin blanc wines and distillates from Colombar base wines, we have overexpressed the alcohol acetyltransferase gene (ATF1) of S. cerevisiae. The ATF1 gene, located on chromosome XV, was cloned from a widely used commercial wine yeast strain of S. cerevisiae, VIN13, and placed under the control of the constitutive yeast phosphoglycerate kinase gene (PGK1) promoter and terminator. Chromoblot analysis confirmed the integration of the modified copy of ATF1 into the genome of three commercial wine yeast strains (VIN7, VIN13, and WE228). Northern blot analysis indicated constitutive expression of ATF1 at high levels in these yeast transformants. The levels of ethyl acetate, iso-amyl acetate, and 2-phenylethyl acetate increased 3- to 10-fold, 3.8- to 12-fold, and 2- to 10-fold, respectively, depending on the fermentation temperature, cultivar, and yeast strain used. The concentrations of ethyl caprate, ethyl caprylate, and hexyl acetate only showed minor changes, whereas the acetic acid

  2. DNA binding by Sgf11 protein affects histone H2B deubiquitination by Spt-Ada-Gcn5-acetyltransferase (SAGA).

    PubMed

    Koehler, Christian; Bonnet, Jacques; Stierle, Matthieu; Romier, Christophe; Devys, Didier; Kieffer, Bruno

    2014-03-28

    The yeast Spt-Ada-Gcn5-acetyltransferase (SAGA) complex is a transcription coactivator that contains a histone H2B deubiquitination activity mediated by its Ubp8 subunit. Full enzymatic activity requires the formation of a quaternary complex, the deubiquitination module (DUBm) of SAGA, which is composed of Ubp8, Sus1, Sgf11, and Sgf73. The crystal structures of the DUBm have shed light on the structure/function relationship of this complex. Specifically, both Sgf11 and Sgf73 contain zinc finger domains (ZnF) that appear essential for the DUBm activity. Whereas Sgf73 N-terminal ZnF is important for DUBm stability, Sgf11 C-terminal ZnF appears to be involved in DUBm function. To further characterize the role of these two zinc fingers, we have solved their structure by NMR. We show that, contrary to the previously reported structures, Sgf73 ZnF adopts a C2H2 coordination with unusual tautomeric forms for the coordinating histidines. We further report that the Sgf11 ZnF, but not the Sgf73 ZnF, binds to nucleosomal DNA with a binding interface composed of arginine residues located within the ZnF α-helix. Mutational analyses both in vitro and in vivo provide evidence for the functional relevance of our structural observations. The combined interpretation of our results leads to an uncommon ZnF-DNA interaction between the SAGA DUBm and nucleosomes, thus providing further functional insights into SAGA's epigenetic modulation of the chromatin structure.

  3. Hexaazatriphenylene (HAT) derivatives: from synthesis to molecular design, self-organization and device applications.

    PubMed

    Segura, José L; Juárez, Rafael; Ramos, Mar; Seoane, Carlos

    2015-10-01

    Dipyrazino[2,3-f:2′,3′-h]quinoxaline also known as 1,4,5,8,9,12-hexaazatriphenylene (HAT) is an electron deficient, rigid, planar, aromatic discotic system with an excellent π–π stacking ability. Because it is one of the smallest two-dimensional N-containing polyheterocyclic aromatic systems, it has been used as the basic scaffold for larger 2D N-substituted polyheterocyclic aromatics. Furthermore, it is the building block of choice in a plethora of molecular, macromolecular and supramolecular systems for a variety of applications. This review is aimed to critically review the research performed during the almost three decades of research based on HAT from the synthetic, theoretical and application points of view. The design principles and synthetic strategies towards HAT derivatives will be established and their use in n-type semiconductors, sensors, nonlinear optical chromophores, liquid crystals, microporous polymers for energy storage and nano and microstructures will reveal the relevance of HAT as a basic scaffold in the areas of organic materials and nanoscience.

  4. Towards top-hat spatial shaping of ultrafast laser beam based on Zernike polynomials

    NASA Astrophysics Data System (ADS)

    Mauclair, Cyril; Faure, Nicolas; Houzet, Julien

    2016-04-01

    Femtosecond laser micro machining of surfaces knows a gain of interest as it demonstrates efficient and precise processing with reduced side effects around the irradiated zone, and also because of the remarkable costs reduction and reliability improvements of nowadays commercially available sources. Controlling the intensity distribution spatially can offer a supplementary degree of flexibility and precision in achieving user-defined ablation spatial profile, drilling, cutting of materials or in-volume laser-induced modifications. In this scope, the possibility to generate a top-hat intensity distribution by spatially shaping the beam wavefront is studied in this work. An optimization of Zernike polynomials coefficients is conducted to numerically determine an adequate phase mask that shapes the laser intensity distribution following a targeted top hat distribution in the processing plane, usually at the focal length of a converging lens. The efficiency of the method is numerically investigated in the optimization by evaluation of the root mean square error (RMS) between the top-hat target and the calculated laser distribution in the far field. We numerically verify that acceptable top-hat beam shaping of various size can be achieved with a sufficient number of Zernike polynomials, opening the way to phase mask calculations adapted to the wavefront modulator ability to reproduce Zernike polynomials.

  5. HATS-5b: A TRANSITING HOT SATURN FROM THE HATSouth SURVEY

    SciTech Connect

    Zhou, G.; Bayliss, D.; Schmidt, B.; Penev, K.; Bakos, G. Á.; Hartman, J. D.; Csubry, Z.; Jordán, A.; Brahm, R.; Rabus, M.; Suc, V.; Espinoza, N.; Mancini, L.; Mohler, M.; Ciceri, S.; Henning, T.; Buchhave, L.; Béky, B.; Noyes, R. W.; Butler, R. P.; and others

    2014-06-01

    We report the discovery of HATS-5b, a transiting hot Saturn orbiting a G-type star, by the HATSouth survey. HATS-5b has a mass of M{sub p} ≈ 0.24 M {sub J}, radius of R{sub p} ≈ 0.91 R {sub J}, and transits its host star with a period of P ≈ 4.7634 days. The radius of HATS-5b is consistent with both theoretical and empirical models. The host star has a V-band magnitude of 12.6, mass of 0.94 M {sub ☉}, and radius of 0.87 R {sub ☉}. The relatively high scale height of HATS-5b and the bright, photometrically quiet host star make this planet a favorable target for future transmission spectroscopy follow-up observations. We reexamine the correlations in radius, equilibrium temperature, and metallicity of the close-in gas giants and find hot Jupiter-mass planets to exhibit the strongest dependence between radius and equilibrium temperature. We find no significant dependence in radius and metallicity for the close-in gas giant population.

  6. Children's Conception of Thermal Conduction--Or the Story of a Woollen Hat.

    ERIC Educational Resources Information Center

    Newell, Andrew; Ross, Keith

    1996-01-01

    Reports on discussions with a year 10-group, following their first lesson on heat energy transfer, that revealed they still had not realized that insulation acted as a barrier; instead they saw it as an active warming agent. Describes a teaching method based on a woollen hat that challenges their naive ideas. (Author/JRH)

  7. Automatic Semantic Activation of Embedded Words: Is There a ''Hat'' in ''That''

    ERIC Educational Resources Information Center

    Bowers, J.S.; Davis, C.J.; Hanley, D.A.

    2005-01-01

    Participants semantically categorized target words that contain subsets (Experiment 1; e.g., target=hatch, subset=hat) or that are parts of supersets (Experiment 2; e.g., target=bee, superset=beer). In both experiments, the targets were categorized in a congruent condition (in which the subset-superset was associated with the same response, e.g.,…

  8. Six Thinking Hats and Social Workers' Innovative Competence: An Experimental Study

    ERIC Educational Resources Information Center

    Azeez, Razaq Olugbenga

    2016-01-01

    Employees, no doubt, are the main force in organizations, and their innovative behaviours are vital for outcome efficacy. Innovative organisations, therefore, need creative employees who generate new ideas for product or process of innovation. This study investigated the effect of six thinking hats creativity technique on innovative competence of…

  9. Beyond Pilgrim Hats and Turkey Hands: Using Thanksgiving to Promote Citizenship and Activism

    ERIC Educational Resources Information Center

    Christie, Erica M.; Montgomery, Sarah E.

    2010-01-01

    In many elementary classrooms, Thanksgiving is celebrated by donning homemade Pilgrim hats, grocery bag vests, and colorful construction-paper headdresses, as students join together to reenact the "first" Thanksgiving with a mock feast. Students compose journal entries on the topic, "what I am thankful for." These typical Thanksgiving activities,…

  10. The Mexican hat effect on the delamination buckling of a compressed thin film

    NASA Astrophysics Data System (ADS)

    Zhang, Yin; Liu, Yun

    2014-12-01

    Because of the interaction between film and substrate, the film buckling stress can vary significantly, depending on the delamination geometry, the film and substrate mechanical properties. The Mexican hat effect indicates such interaction. An analytical method is presented, and related dimensional analysis shows that a single dimensionless parameter can effectively evaluate the effect.

  11. Test and Analysis of Composite Hat Stringer Pull-off Test Specimens

    NASA Technical Reports Server (NTRS)

    Li, Jian; OBrien, T. Kevin; Rousseau, Carl Q.

    1996-01-01

    Hat stringer pull-off tests were performed to evaluate the delamination failure mechanisms in the flange region for a rod-reinforced hat stringer section. A special test fixture was used to pull the hat off the stringer while reacting the pull-off load through roller supports at both stringer flanges. Microscopic examinations of the failed specimens revealed that failure occurred at the ply termination in the flange area where the flange of the stiffener is built up by adding 45/-45 tape plies on the top surface. Test results indicated that the as-manufactured microstructure in the flange region has a strong influence on the delamination initiation and the associated pull-off loads. Finite element models were created for each specimen with a detailed mesh based on micrographs of the critical location. A fracture mechanics approach and a mixed mode delamination criterion were used to predict the onset of delamination and the pull-off load. By modeling the critical local details of each specimen from micrographs, the model was able to accurately predict the hat stringer pull-off loads and replicate the variability in the test results.

  12. Electronic and thermoelectric properties of Mexican hat bands in van-der-Waals materials

    NASA Astrophysics Data System (ADS)

    Wickramaratne, Darshana; Zahid, Ferdows; Lake, Roger

    2015-03-01

    Mexican hat dispersions are relatively common in few-layer two-dimensional materials. In one to four monolayers of the group-III chalcogenides (GaS, GaSe, InS, InSe) and Bi2Se3 the valence band undergoes a band inversion from a parabolic to an inverted Mexican hat dispersion as the film thickness is reduced from bulk to a single monolayer. The band inversion is robust against changes in stacking order, omission or inclusion of spin-orbit coupling and the choice of functional. The Mexican hat dispersion results in a 1/√{ E} singularity in the two-dimensional density of states and a step-function turn on in the density of modes. The largest radius of the ring of states occurs for a single monolayer of each material. The dispersion with the largest radius coincides with the maximum power factor and ZT for a material at room temperature. Ab-initio electronic structure calculations are used with a Landauer approach to calculate the thermoelectric transport coefficients. Analytical models of the Mexican hat and the parabolic dispersions are used for comparison and analysis. Vertically biased bilayer graphene could serve as an experimental test-bed for measuring this effect since the radius of the Mexican hat band edge increases linearly with vertical electric field. Support by the NSF and SRC-NRI Project 2204.001 (NSF-ECCS-1124733), FAME, one of six centers of STARnet, a SRC program sponsored by MARCO and DARPA and the use of XSEDE NSF Grant # OCI-1053575.

  13. Dynamical Constraints on the Core Mass of Hot Jupiter HAT-P-13b

    NASA Astrophysics Data System (ADS)

    Buhler, Peter B.; Knutson, Heather A.; Batygin, Konstantin; Fulton, Benjamin J.; Fortney, Jonathan J.; Burrows, Adam; Wong, Ian

    2016-04-01

    HAT-P-13b is a Jupiter-mass transiting exoplanet that has settled onto a stable, short-period, and mildly eccentric orbit as a consequence of the action of tidal dissipation and perturbations from a second, highly eccentric, outer companion. Owing to the special orbital configuration of the HAT-P-13 system, the magnitude of HAT-P-13b's eccentricity (eb) is in part dictated by its Love number ({k}{2b}), which is in turn a proxy for the degree of central mass concentration in its interior. Thus, the measurement of eb constrains {k}{2b} and allows us to place otherwise elusive constraints on the mass of HAT-P-13b's core (Mcore,b). In this study we derive new constraints on the value of eb by observing two secondary eclipses of HAT-P-13b with the Infrared Array Camera on board the Spitzer Space Telescope. We fit the measured secondary eclipse times simultaneously with radial velocity measurements and find that eb = 0.00700 ± 0.00100. We then use octupole-order secular perturbation theory to find the corresponding {k}{2b}={0.31}-0.05+0.08. Applying structural evolution models, we then find, with 68% confidence, that Mcore,b is less than 25 Earth masses (M⊕). The most likely value is Mcore,b = 11 M⊕, which is similar to the core mass theoretically required for runaway gas accretion. This is the tightest constraint to date on the core mass of a hot Jupiter. Additionally, we find that the measured secondary eclipse depths, which are in the 3.6 and 4.5 μm bands, best match atmospheric model predictions with a dayside temperature inversion and relatively efficient day-night circulation.

  14. Atmospheric circulation of eccentric hot Jupiter HAT-P-2B

    SciTech Connect

    Lewis, Nikole K.; Showman, Adam P.; Fortney, Jonathan J.; Knutson, Heather A.; Marley, Mark S.

    2014-11-10

    The hot Jupiter HAT-P-2b has become a prime target for Spitzer Space Telescope observations aimed at understanding the atmospheric response of exoplanets on highly eccentric orbits. Here we present a suite of three-dimensional atmospheric circulation models for HAT-P-2b that investigate the effects of assumed atmospheric composition and rotation rate on global scale winds and thermal patterns. We compare and contrast atmospheric models for HAT-P-2b, which assume one and five times solar metallicity, both with and without TiO/VO as atmospheric constituents. Additionally we compare models that assume a rotation period of half, one, and two times the nominal pseudo-synchronous rotation period. We find that changes in assumed atmospheric metallicity and rotation rate do not significantly affect model predictions of the planetary flux as a function of orbital phase. However, models in which TiO/VO are present in the atmosphere develop a transient temperature inversion between the transit and secondary eclipse events that results in significant variations in the timing and magnitude of the peak of the planetary flux compared with models in which TiO/VO are omitted from the opacity tables. We find that no one single atmospheric model can reproduce the recently observed full orbit phase curves at 3.6, 4.5 and 8.0 μm, which is likely due to a chemical process not captured by our current atmospheric models for HAT-P-2b. Further modeling and observational efforts focused on understanding the chemistry of HAT-P-2b's atmosphere are needed and could provide key insights into the interplay between radiative, dynamical, and chemical processes in a wide range of exoplanet atmospheres.

  15. Atmospheric Circulation of Eccentric Hot Jupiter HAT-P-2b

    NASA Astrophysics Data System (ADS)

    Lewis, Nikole K.; Showman, Adam P.; Fortney, Jonathan J.; Knutson, Heather A.; Marley, Mark S.

    2014-11-01

    The hot Jupiter HAT-P-2b has become a prime target for Spitzer Space Telescope observations aimed at understanding the atmospheric response of exoplanets on highly eccentric orbits. Here we present a suite of three-dimensional atmospheric circulation models for HAT-P-2b that investigate the effects of assumed atmospheric composition and rotation rate on global scale winds and thermal patterns. We compare and contrast atmospheric models for HAT-P-2b, which assume one and five times solar metallicity, both with and without TiO/VO as atmospheric constituents. Additionally we compare models that assume a rotation period of half, one, and two times the nominal pseudo-synchronous rotation period. We find that changes in assumed atmospheric metallicity and rotation rate do not significantly affect model predictions of the planetary flux as a function of orbital phase. However, models in which TiO/VO are present in the atmosphere develop a transient temperature inversion between the transit and secondary eclipse events that results in significant variations in the timing and magnitude of the peak of the planetary flux compared with models in which TiO/VO are omitted from the opacity tables. We find that no one single atmospheric model can reproduce the recently observed full orbit phase curves at 3.6, 4.5 and 8.0 μm, which is likely due to a chemical process not captured by our current atmospheric models for HAT-P-2b. Further modeling and observational efforts focused on understanding the chemistry of HAT-P-2b's atmosphere are needed and could provide key insights into the interplay between radiative, dynamical, and chemical processes in a wide range of exoplanet atmospheres.

  16. VizieR Online Data Catalog: Photometry and spectroscopy of HAT-P-57 (Hartman+, 2015)

    NASA Astrophysics Data System (ADS)

    Hartman, J. D.; Bakos, G. A.; Buchhave, L. A.; Torres, G.; Latham, D. W.; Kovacs, G.; Bhatti, W.; Csubry, Z.; de Val-Borro, M.; Penev, K.; Huang, C. X.; Beky, B.; Bieryla, A.; Quinn, S. N.; Howard, A. W.; Marcy, G. W.; Johnson, J. A.; Isaacson, H.; Fischer, D. A.; Noyes, R. W.; Falco, E.; Esquerdo, G. A.; Knox, R. P.; Hinz, P.; Lazar, J.; Papp, I.; Sari, P.

    2016-05-01

    The star HAT-P-57 was observed by the HATNet wide-field photometric instruments between the nights of UT 2009 May 12 and UT 2009 September 14. A total of 622 observations of a 10.6°*10.6° field centered at RA=06h24m, decl.=+30° were made with the HAT-5 telescope in Arizona, and 3202 observations of this same field were made with the HAT-9 telescope in Hawaii. We used a Sloan r filter. Photometric follow-up observations of HAT-P-57 were carried out with KeplerCam on the Fred Lawrence Whipple Observatory (FLWO) 1.2m telescope. We observed ingress events on the nights of 2010 April 3 and 2012 April 24, in i and g-bands respectively, and a full transit on the night of 2010 June 26 in z-band. Additional photometric follow-up observations were carried out with the FLWO 1.2m on the night of 2015 May 12. All time-series photometric data that we collected for HAT-P-57 are provided in Table1. Spectroscopic observations were obtained using the HIgh-Resolution Echelle Spectrometer (HIRES) on the Keck-I 10m telescope between UT 2010 June 27 and UT 2012 March 10. A total of 24 HIRES observations were collected during this time period, including 14 observations made through the I2 cell (e.g., Marcy & Butler, 1992PASP..104..270M), and 10 observations without the I2 cell. These latter observations were obtained on the night of UT 2010 June 27, primarily during a planetary transit (Section 3.3 discusses the analysis of these observations in more detail). Table2 gives the relative radial velocity measurements obtained with the I2 Doppler pipeline, the radial velocity measurements obtained from the CCFs, and the Bisector Spans for the HIRES observations. (2 data files).

  17. Dynamical Constraints on the Core Mass of Hot Jupiter HAT-P-13b

    NASA Astrophysics Data System (ADS)

    Buhler, Peter B.; Knutson, Heather A.; Batygin, Konstantin; Fulton, Benjamin J.; Fortney, Jonathan J.; Burrows, Adam; Wong, Ian

    2016-04-01

    HAT-P-13b is a Jupiter-mass transiting exoplanet that has settled onto a stable, short-period, and mildly eccentric orbit as a consequence of the action of tidal dissipation and perturbations from a second, highly eccentric, outer companion. Owing to the special orbital configuration of the HAT-P-13 system, the magnitude of HAT-P-13b's eccentricity (eb) is in part dictated by its Love number ({k}{2b}), which is in turn a proxy for the degree of central mass concentration in its interior. Thus, the measurement of eb constrains {k}{2b} and allows us to place otherwise elusive constraints on the mass of HAT-P-13b's core (Mcore,b). In this study we derive new constraints on the value of eb by observing two secondary eclipses of HAT-P-13b with the Infrared Array Camera on board the Spitzer Space Telescope. We fit the measured secondary eclipse times simultaneously with radial velocity measurements and find that eb = 0.00700 ± 0.00100. We then use octupole-order secular perturbation theory to find the corresponding {k}{2b}={0.31}-0.05+0.08. Applying structural evolution models, we then find, with 68% confidence, that Mcore,b is less than 25 Earth masses (M⊕). The most likely value is Mcore,b = 11 M⊕, which is similar to the core mass theoretically required for runaway gas accretion. This is the tightest constraint to date on the core mass of a hot Jupiter. Additionally, we find that the measured secondary eclipse depths, which are in the 3.6 and 4.5 μm bands, best match atmospheric model predictions with a dayside temperature inversion and relatively efficient day–night circulation.

  18. Histone acetyltransferases regulate HIV-1 enhancer activity in vitro

    PubMed Central

    Sheridan, Philip L.; Mayall, Timothy P.; Verdin, Eric; Jones, Katherine A.

    1997-01-01

    Specific inhibitors of histone deacetylase, such as trichostatin A (TSA) and trapoxin (TPX), are potent inducers of HIV-1 transcription in latently infected T-cell lines. Activation of the integrated HIV-1 promoter is accompanied by the loss or rearrangement of a positioned nucleosome (nuc-1) near the viral RNA start site. Here we show that TSA strongly induces HIV-1 transcription on chromatin in vitro, concomitant with an enhancer factor-assisted increase in the level of acetylated histone H4. TSA treatment, however, did not detectably alter enhancer factor binding or the positioning of nuc-1 on the majority of the chromatin templates indicating that protein acetylation and chromatin remodeling may be limiting steps that occur only on transcriptionally competent templates, or that remodeling of nuc-1 requires additional factors. To assess the number of active chromatin templates in vitro, transcription was limited to a single round with low levels of the detergent Sarkosyl. Remarkably, HIV-1 transcription on chromatin was found to arise from a small number of active templates that can each support nearly 100 rounds of transcription, and TSA increased the number of active templates in each round. In contrast, transcription on naked DNA was limited to only a few rounds and was not responsive to TSA. We conclude that HIV-1 enhancer complexes greatly facilitate transcription reinitiation on chromatin in vitro, and act at a limiting step to promote the acetylation of histones or other transcription factors required for HIV-1 enhancer activity. PMID:9407026

  19. Synthesis of 4′-aminopantetheine and derivatives to probe aminoglycoside N-6′-acetyltransferase

    PubMed Central

    Yan, Xuxu; Akinnusi, T. Olukayode; Larsen, Aaron T.; Auclair, Karine

    2011-01-01

    Summary A convenient synthesis of 4′-aminopantetheine from commercial D-pantethine is reported. The amino group was introduced by reductive amination in order to avoid substitution at a sterically congested position. Derivatives of 4′-aminopantetheine were also prepared to evaluate the effect of O-to-N substitution on inhibitors of the resistance-causing enzyme aminoglycoside N-6′-acetyltransferase. The biological results combined with docking studies indicate that in spite of its reported unusual flexibility and ability to adopt different folds, this enzyme is highly specific for AcCoA. PMID:21225062

  20. Transient expression of choline acetyltransferase-like immunoreactivity in Purkinje cells of the developing rat cerebellum.

    PubMed

    Gould, E; Butcher, L L

    1987-08-01

    The expression of choline acetyltransferase (ChAT)-like immunoreactivity was studied immunohistochemically in the cerebelli of developing rats. Brains were examined from the day of birth (postnatal day 1: P1) until adulthood. From P4 through P21, several Purkinje cells in the uvula, nodule, and flocculus of the cerebellum demonstrated ChAT-like immunoreactivity. After P23, no ChAT-positive neurons were observed in any region of the cerebellum. This finding paralleled the transient expression of acetylcholinesterase in Purkinje cells of these same cerebellar areas during development.

  1. Comparative genomic and phylogenetic investigation of the xenobiotic metabolizing arylamine N-acetyltransferase enzyme family.

    PubMed

    Glenn, Anthony E; Karagianni, Eleni P; Ulndreaj, Alphantigona; Boukouvala, Sotiria

    2010-07-16

    Arylamine N-acetyltransferases (NATs) are xenobiotic metabolizing enzymes characterized in several bacteria and eukaryotic organisms. We report a comprehensive phylogenetic analysis employing an exhaustive dataset of NAT-homologous sequences recovered through inspection of 2445 genomes. We describe the first NAT homologues in viruses, archaea, protists, many fungi and invertebrates, providing complete annotations in line with the consensus nomenclature. Contrary to the NAT genes of vertebrates, introns are commonly found within the homologous coding regions of lower eukaryotes. The NATs of fungi and higher animals are distinctly monophyletic, but evidence supports a mixed phylogeny of NATs among bacteria, protists and possibly some invertebrates.

  2. One-step purification of phosphinothricin acetyltransferase using reactive dye-affinity chromatography.

    PubMed

    Wang, Cunxi; Lee, Thomas C; Crowley, Kathleen S; Bell, Erin

    2015-01-01

    Reactive dye purification is an affinity purification technique offering unique selectivity and high purification potential. Historically, purification of phosphinothricin acetyltransferase (PAT) has involved several steps of precipitation and column chromatography. Here, we describe a novel purification method that is simple, time-saving, inexpensive, and reproducible. The novel method employs a single chromatography step using a reactive dye resin, Reactive brown 10-agarose. Reactive brown 10 preferentially binds the PAT protein, which can then be specifically released by one of its substrates, acetyl-CoA. Using Reactive brown 10-agarose, PAT protein can be purified to homogeneity from E. coli or plant tissue with high recovery efficiency. PMID:25749943

  3. Inhibitors of acetyltransferase domain of N-acetylglucosamine-1-phosphate-uridyltransferase/glucosamine-1-phosphate-acetyltransferase (GlmU). Part 1: Hit to lead evaluation of a novel arylsulfonamide series.

    PubMed

    Green, Oluyinka M; McKenzie, Andrew R; Shapiro, Adam B; Otterbein, Ludovic; Ni, Haihong; Patten, Arthur; Stokes, Suzanne; Albert, Robert; Kawatkar, Sameer; Breed, Jason

    2012-02-15

    A novel arylsulfonamide-containing series of compounds represented by 1, discovered by highthroughput screening, inhibit the acetyltransferase domain of N-acetylglucosamine-1-phosphate-uridyltransferase/glucosamine-1-phosphate-acetyltransferase (GlmU). X-ray structure determination confirmed that inhibitor binds at the site occupied by acetyl-CoA, indicating that series is competitive with this substrate. This letter documents our early hit-to-lead evaluation of the chemical series and some of the findings that led to improvement in in-vitro potency against Gram-negative and Gram-positive bacterial isozymes, exemplified by compound 40.

  4. Inhibition of p300 histone acetyltransferase activity in palate mesenchyme cells attenuates Wnt signaling via aberrant E-cadherin expression.

    PubMed

    Warner, Dennis R; Smith, Scott C; Smolenkova, Irina A; Pisano, M Michele; Greene, Robert M

    2016-03-01

    p300 is a multifunctional transcriptional coactivator that interacts with numerous transcription factors and exhibits protein/histone acetyltransferase activity. Loss of p300 function in humans and in mice leads to craniofacial defects. In this study, we demonstrated that inhibition of p300 histone acetyltransferase activity with the compound, C646, altered the expression of several genes, including Cdh1 (E-cadherin) in mouse maxillary mesenchyme cells, which are the cells that give rise to the secondary palate. The increased expression of plasma membrane-bound E-cadherin was associated with reduced cytosolic β-catenin, that led to attenuated signaling through the canonical Wnt pathway. Furthermore, C646 reduced both cell proliferation and the migratory ability of these cells. These results suggest that p300 histone acetyltransferase activity is critical for Wnt-dependent palate mesenchymal cell proliferation and migration, both processes that play a significant role in morphogenesis of the palate.

  5. Effect of SWI/SNF chromatin remodeling complex on HIV-1 Tat activated transcription

    PubMed Central

    Agbottah, Emmanuel; Deng, Longwen; Dannenberg, Luke O; Pumfery, Anne; Kashanchi, Fatah

    2006-01-01

    Background Human immunodeficiency virus type 1 (HIV-1) is the etiologic agent of acquired immunodeficiency virus (AIDS). Following entry into the host cell, the viral RNA is reverse transcribed into DNA and subsequently integrated into the host genome as a chromatin template. The integrated proviral DNA, along with the specific chromatinized environment in which integration takes place allows for the coordinated regulation of viral transcription and replication. While the specific roles of and interplay between viral and host proteins have not been fully elucidated, numerous reports indicate that HIV-1 retains the ability for self-regulation via the pleiotropic effects of its viral proteins. Though viral transcription is fully dependent upon host cellular factors and the state of host activation, recent findings indicate a complex interplay between viral proteins and host transcription regulatory machineries including histone deacetylases (HDACs), histone acetyltransferases (HATs), cyclin dependent kinases (CDKs), and histone methyltransferases (HMTs). Results Here, we describe the effect of Tat activated transcription at the G1/S border of the cell cycle and analyze the interaction of modified Tat with the chromatin remodeling complex, SWI/SNF. HIV-1 LTR DNA reconstituted into nucleosomes can be activated in vitro using various Tat expressing extracts. Optimally activated transcription was observed at the G1/S border of the cell cycle both in vitro and in vivo, where chromatin remodeling complex, SWI/SNF, was present on the immobilized LTR DNA. Using a number of in vitro binding as well as in vivo chromatin immunoprecipitation (ChIP) assays, we detected the presence of both BRG1 and acetylated Tat in the same complex. Finally, we demonstrate that activated transcription resulted in partial or complete removal of the nucleosome from the start site of the LTR as evidenced by a restriction enzyme accessibility assay. Conclusion We propose a model where unmodified Tat

  6. Snf1p-dependent Spt-Ada-Gcn5-acetyltransferase (SAGA) recruitment and chromatin remodeling activities on the HXT2 and HXT4 promoters.

    PubMed

    van Oevelen, Chris J C; van Teeffelen, Hetty A A M; van Werven, Folkert J; Timmers, H Th Marc

    2006-02-17

    We previously showed that the Spt-Ada-Gcn5-acetyltransferase (SAGA) complex is recruited to the activated HXT2 and HXT4 genes and plays a role in the association of TBP-associated factors. Using the HXT2 and HXT4 genes, we now present evidence for a functional link between Snf1p-dependent activation, recruitment of the SAGA complex, histone H3 removal, and H3 acetylation. Recruitment of the SAGA complex is dependent on the release of Ssn6p-Tup1p repression by Snf1p. In addition, we found that the Gcn5p subunit of the SAGA complex preferentially acetylates histone H3K18 on the HXT2 and HXT4 promoters and that Gcn5p activity is required for removal of histone H3 from the HXT4 promoter TATA region. In contrast, histone H3 removal from the HXT2 promoter does not require Gcn5p. In conclusion, although similar protein complexes are involved, induction of HXT2 and HXT4 displays important mechanistic differences.

  7. HAT-P-32b and HAT-P-33b: Two Highly Inflated Hot Jupiters Transiting High-jitter Stars

    NASA Astrophysics Data System (ADS)

    Hartman, J. D.; Bakos, G. Á.; Torres, G.; Latham, D. W.; Kovács, Géza; Béky, B.; Quinn, S. N.; Mazeh, T.; Shporer, A.; Marcy, G. W.; Howard, A. W.; Fischer, D. A.; Johnson, J. A.; Esquerdo, G. A.; Noyes, R. W.; Sasselov, D. D.; Stefanik, R. P.; Fernandez, J. M.; Szklenár, T.; Lázár, J.; Papp, I.; Sári, P.

    2011-11-01

    We report the discovery of two exoplanets transiting high-jitter stars. HAT-P-32b orbits the bright V = 11.289 late-F-early-G dwarf star GSC 3281-00800, with a period P = 2.150008 ± 0.000001 d. The stellar and planetary masses and radii depend on the eccentricity of the system, which is poorly constrained due to the high-velocity jitter (~80 m s-1). Assuming a circular orbit, the star has a mass of 1.16 ± 0.04 M ⊙ and radius of 1.22 ± 0.02 R ⊙, while the planet has a mass of 0.860 ± 0.164 M J and a radius of 1.789 ± 0.025 R J. The second planet, HAT-P-33b, orbits the bright V = 11.188 late-F dwarf star GSC 2461-00988, with a period P = 3.474474 ± 0.000001 d. As for HAT-P-32, the stellar and planetary masses and radii of HAT-P-33 depend on the eccentricity, which is poorly constrained due to the high jitter (~50 m s-1). In this case, spectral line bisector spans (BSs) are significantly anti-correlated with the radial velocity residuals, and we are able to use this correlation to reduce the residual rms to ~35 m s-1. We find that the star has a mass of 1.38 ± 0.04 M ⊙ and a radius of 1.64 ± 0.03 R ⊙ while the planet has a mass of 0.762 ± 0.101 M J and a radius of 1.686 ± 0.045 R J for an assumed circular orbit. Due to the large BS variations exhibited by both stars we rely on detailed modeling of the photometric light curves to rule out blend scenarios. Both planets are among the largest radii transiting planets discovered to date. Based in part on observations obtained at the W. M. Keck Observatory, which is operated by the University of California and the California Institute of Technology. Keck time has been granted by NOAO (A285Hr, A146Hr, A201Hr, A289Hr), NASA (N128Hr, N145Hr, N049Hr, N018Hr, N167Hr, N029Hr), and the NOAO Gemini/Keck time-exchange program (G329Hr).

  8. No association between apolipoprotein E or N‐Acetyltransferase 2 gene polymorphisms and age‐related hearing loss

    PubMed Central

    Dawes, Piers; Platt, Hazel; Horan, Michael; Ollier, William; Munro, Kevin; Pendleton, Neil

    2014-01-01

    Objectives/Hypothesis Age‐related hearing loss has a genetic component, but there have been limited genetic studies in this field. Both N‐acetyltransferase 2 and apolipoprotein E genes have previously been associated. However, these studies have either used small sample sizes, examined a limited number of polymorphisms, or have produced conflicting results. Here we use a haplotype tagging approach to determine association with age‐related hearing loss and investigate epistasis between these two genes. Study Design Candidate gene association study of a continuous phenotype. Methods We investigated haplotype tagging single nucleotide polymorphisms in the N‐acetyltransferase 2 gene and the presence/absence of the apolipoprotein E ε4 allele for association with age‐related hearing loss in a cohort of 265 Caucasian elderly volunteers from Greater Manchester, United Kingdom. Hearing phenotypes were generated using principal component analysis of the hearing threshold levels for the better ear (severity, slope, and concavity). Genotype data for the N‐acetyltransferase 2 gene was obtained from existing genome‐wide association study data from the Illumina 610‐Quadv1 chip. Apolipoprotein E genotyping was performed using Sequenom technology. Linear regression analysis was performed using Plink and Stata software. Results No significant associations (P value, > 0.05) were observed between the N‐acetyltransferase 2 or apolipoprotein E gene polymorphisms and any hearing factor. No significant association was observed for epistasis analysis of apolipoprotein E ε4 and the N‐acetyltransferase 2 single nucleotide polymorphism rs1799930 (NAT2*6A). Conclusion We found no evidence to support that either N‐acetyltransferase 2 or apolipoprotein E gene polymorphisms are associated with age‐related hearing loss in a cohort of 265 elderly volunteers. Level of Evidence N/A. Laryngoscope, 125:E33–E38, 2015 PMID:25155015

  9. How a hat may affect 3-month-olds' recognition of a face: an eye-tracking study.

    PubMed

    Bulf, Hermann; Valenza, Eloisa; Turati, Chiara

    2013-01-01

    Recent studies have shown that infants' face recognition rests on a robust face representation that is resilient to a variety of facial transformations such as rotations in depth, motion, occlusion or deprivation of inner/outer features. Here, we investigated whether 3-month-old infants' ability to represent the invariant aspects of a face is affected by the presence of an external add-on element, i.e. a hat. Using a visual habituation task, three experiments were carried out in which face recognition was investigated by manipulating the presence/absence of a hat during face encoding (i.e. habituation phase) and face recognition (i.e. test phase). An eye-tracker system was used to record the time infants spent looking at face-relevant information compared to the hat. The results showed that infants' face recognition was not affected by the presence of the external element when the type of the hat did not vary between the habituation and test phases, and when both the novel and the familiar face wore the same hat during the test phase (Experiment 1). Infants' ability to recognize the invariant aspects of a face was preserved also when the hat was absent in the habituation phase and the same hat was shown only during the test phase (Experiment 2). Conversely, when the novel face identity competed with a novel hat, the hat triggered the infants' attention, interfering with the recognition process and preventing the infants' preference for the novel face during the test phase (Experiment 3). Findings from the current study shed light on how faces and objects are processed when they are simultaneously presented in the same visual scene, contributing to an understanding of how infants respond to the multiple and composite information available in their surrounding environment.

  10. HATS-17b: A Transiting Compact Warm Jupiter in a 16.3 Day Circular Orbit

    NASA Astrophysics Data System (ADS)

    Brahm, R.; Jordán, A.; Bakos, G. Á.; Penev, K.; Espinoza, N.; Rabus, M.; Hartman, J. D.; Bayliss, D.; Ciceri, S.; Zhou, G.; Mancini, L.; Tan, T. G.; de Val-Borro, M.; Bhatti, W.; Csubry, Z.; Bento, J.; Henning, T.; Schmidt, B.; Rojas, F.; Suc, V.; Lázár, J.; Papp, I.; Sári, P.

    2016-04-01

    We report the discovery of HATS-17b, the first transiting warm Jupiter of the HATSouth network. HATS-17b transits its bright (V = 12.4) G-type ({M}\\star = 1.131+/- 0.030 {M}⊙ , {R}\\star = {1.091}-0.046+0.070 {R}⊙ ) metal-rich ([Fe/H] = +0.3 dex) host star in a circular orbit with a period of P = 16.2546 days. HATS-17b has a very compact radius of 0.777+/- 0.056 {R}{{J}} given its Jupiter-like mass of 1.338+/- 0.065 {M}{{J}}. Up to 50% of the mass of HATS-17b may be composed of heavy elements in order to explain its high density with current models of planetary structure. HATS-17b is the longest period transiting planet discovered to date by a ground-based photometric survey, and is one of the brightest transiting warm Jupiter systems known. The brightness of HATS-17 will allow detailed follow-up observations to characterize the orbital geometry of the system and the atmosphere of the planet. The HATSouth network is operated by a collaboration consisting of Princeton University (PU), the Max Planck Institute für Astronomie (MPIA), the Australian National University (ANU), and the Pontificia Universidad Católica de Chile (PUC). The station at Las Campanas Observatory (LCO) of the Carnegie Institute is operated by PU in conjunction with PUC, the station at the High Energy Spectroscopic Survey (H.E.S.S.) site is operated in conjunction with MPIA, and the station at Siding Spring Observatory (SSO) is operated jointly with ANU. This paper includes data gathered with the MPG 2.2 m telescope at the ESO Observatory in La Silla and with the 3.9 m AAT in Siding Spring Observatory. This paper uses observations obtained with facilities of the Las Cumbres Observatory Global Telescope. Based on observations taken with the HARPS spectrograph (ESO 3.6 m telescope at La Silla) under programme 097.C-0571.

  11. Immunolocalization of choline acetyltransferase of common type in the central brain mass of Octopus vulgaris

    PubMed Central

    Casini, A.; Vaccaro, R.; D'Este, L.; Sakaue, Y.; Bellier, J.P.; Kimura, H.; Renda, T.G.

    2012-01-01

    Acetylcholine, the first neurotransmitter to be identified in the vertebrate frog, is widely distributed among the animal kingdom. The presence of a large amount of acetylcholine in the nervous system of cephalopods is well known from several biochemical and physiological studies. However, little is known about the precise distribution of cholinergic structures due to a lack of a suitable histochemical technique for detecting acetylcholine. The most reliable method to visualize the cholinergic neurons is the immunohistochemical localization of the enzyme choline acetyltransferase, the synthetic enzyme of acetylcholine. Following our previous study on the distribution patterns of cholinergic neurons in the Octopus vulgaris visual system, using a novel antibody that recognizes choline acetyltransferase of the common type (cChAT), now we extend our investigation on the octopus central brain mass. When applied on sections of octopus central ganglia, immunoreactivity for cChAT was detected in cell bodies of all central brain mass lobes with the notable exception of the subfrontal and subvertical lobes. Positive varicosed nerves fibers where observed in the neuropil of all central brain mass lobes. PMID:23027350

  12. Photoaffinity labelling of carnitine acetyltransferase with S-(p-azidophenacyl)thiocarnitine.

    PubMed Central

    Mauro, J M; Lewis, R V; Barden, R E

    1986-01-01

    A photolabile reagent, p-azidophenacyl-DL-thiocarnitine, was synthesized and tested as a photoaffinity label for carnitine acetyltransferase (EC 2.3.1.7) from pigeon breast. p-Azidophenacyl-DL-thiocarnitine is an active-site-directed reagent for this acetyltransferase, since it is a competitive inhibitor (Ki 10 microM) versus carnitine. U.v. irradiation of a mixture of p-azidophenacyl-DL-thiocarnitine and enzyme produces irreversible inhibition. Acetyl-DL-carnitine protects the enzyme from inhibition by photoactivated p-azidophenacyl-DL-thiocarnitine. In the presence of 30 mM-2-mercaptoethanol as a scavenger, the relationship between loss of activity and photoincorporation of reagent suggests that one molecule of reagent is incorporated per molecule of inhibited enzyme. However, peptide maps of enzyme labelled with p-azidophenacyl[14C]thiocarnitine indicate that several (about six) tryptic peptides (of a possible 60-65) are modified. The presence of 5 mM-acetyl-DL-carnitine significantly decreases the incorporation of reagent in each labelled tryptic peptide. PMID:3800901

  13. Cysteine biosynthesis in Lactobacillus casei: identification and characterization of a serine acetyltransferase.

    PubMed

    Bogicevic, Biljana; Berthoud, Hélène; Portmann, Reto; Bavan, Tharmatha; Meile, Leo; Irmler, Stefan

    2016-02-01

    In bacteria, cysteine can be synthesized from serine by two steps involving an L-serine O-acetyltransferase (SAT) and a cysteine synthase (CysK). While CysK is found in the publicly available annotated genome from Lactobacillus casei ATCC 334, a gene encoding SAT (cysE) is missing. In this study, we found that various strains of L. casei grew in a chemically defined medium containing sulfide as the sole sulfur source, indicating the presence of a serine O-acetyltransferase. The gene lying upstream of cysK is predicted to encode a homoserine trans-succinylase (metA). To study the function of this gene, it was cloned from L. casei FAM18110. The purified, recombinant protein did not acylate L-homoserine in vitro. Instead, it catalyzed the formation of O-acetyl serine from L-serine and acetyl-CoA. Furthermore, the plasmid expressing the L. casei gene complemented an Escherichia coli cysE mutant strain but not an E. coli metA mutant. This clearly demonstrated that the gene annotated as metA in fact encodes the SAT function and should be annotated as cysE.

  14. Crystal structure of bacillus subtilis YdaF protein : a putative ribosomal N-acetyltransferase.

    SciTech Connect

    Brunzelle, J. S.; Wu, R.; Korolev, S. V.; Collart, F. R.; Joachimiak, A.; Anderson, W. F.; Biosciences Division; Northwestern Univ.; Saint Louis Univ. School of Medicine

    2004-12-01

    Comparative sequence analysis suggests that the ydaF gene encodes a protein (YdaF) that functions as an N-acetyltransferase, more specifically, a ribosomal N-acetyltransferase. Sequence analysis using basic local alignment search tool (BLAST) suggests that YdaF belongs to a large family of proteins (199 proteins found in 88 unique species of bacteria, archaea, and eukaryotes). YdaF also belongs to the COG1670, which includes the Escherichia coli RimL protein that is known to acetylate ribosomal protein L12. N-acetylation (NAT) has been found in all kingdoms. NAT enzymes catalyze the transfer of an acetyl group from acetyl-CoA (AcCoA) to a primary amino group. For example, NATs can acetylate the N-terminal {alpha}-amino group, the {epsilon}-amino group of lysine residues, aminoglycoside antibiotics, spermine/speridine, or arylalkylamines such as serotonin. The crystal structure of the alleged ribosomal NAT protein, YdaF, from Bacillus subtilis presented here was determined as a part of the Midwest Center for Structural Genomics. The structure maintains the conserved tertiary structure of other known NATs and a high sequence similarity in the presumed AcCoA binding pocket in spite of a very low overall level of sequence identity to other NATs of known structure.

  15. Crystal structure analysis of the polysialic acid specific O-acetyltransferase NeuO.

    PubMed

    Schulz, Eike C; Bergfeld, Anne K; Ficner, Ralf; Mühlenhoff, Martina

    2011-01-01

    The major virulence factor of the neuroinvasive pathogen Escherichia coli K1 is the K1 capsule composed of α2,8-linked polysialic acid (polySia). K1 strains harboring the CUS-3 prophage modify their capsular polysaccharide by phase-variable O-acetylation, a step that is associated with increased virulence. Here we present the crystal structure of the prophage-encoded polysialate O-acetyltransferase NeuO. The homotrimeric enzyme belongs to the left-handed β-helix (LβH) family of acyltransferases and is characterized by an unusual funnel-shaped outline. Comparison with other members of the LβH family allowed the identification of active site residues and proposal of a catalytic mechanism and highlighted structural characteristics of polySia specific O-acetyltransferases. As a unique feature of NeuO, the enzymatic activity linearly increases with the length of the N-terminal poly-ψ-domain which is composed of a variable number of tandem copies of an RLKTQDS heptad. Since the poly-ψ-domain was not resolved in the crystal structure it is assumed to be unfolded in the apo-enzyme.

  16. Crystal Structure Analysis of the Polysialic Acid Specific O-Acetyltransferase NeuO

    PubMed Central

    Schulz, Eike C.; Bergfeld, Anne K.; Ficner, Ralf; Mühlenhoff, Martina

    2011-01-01

    The major virulence factor of the neuroinvasive pathogen Escherichia coli K1 is the K1 capsule composed of α2,8-linked polysialic acid (polySia). K1 strains harboring the CUS-3 prophage modify their capsular polysaccharide by phase-variable O-acetlyation, a step that is associated with increased virulence. Here we present the crystal structure of the prophage-encoded polysialate O-acetyltransferase NeuO. The homotrimeric enzyme belongs to the left-handed β-helix (LβH) family of acyltransferases and is characterized by an unusual funnel-shaped outline. Comparison with other members of the LβH family allowed the identification of active site residues and proposal of a catalytic mechanism and highlighted structural characteristics of polySia specific O-acetyltransferases. As a unique feature of NeuO, the enzymatic activity linearly increases with the length of the N-terminal poly-ψ-domain which is composed of a variable number of tandem copies of an RLKTQDS heptad. Since the poly-ψ-domain was not resolved in the crystal structure it is assumed to be unfolded in the apo-enyzme. PMID:21390252

  17. Biochemical and structural analysis of an Eis family aminoglycoside acetyltransferase from bacillus anthracis.

    PubMed

    Green, Keith D; Biswas, Tapan; Chang, Changsoo; Wu, Ruiying; Chen, Wenjing; Janes, Brian K; Chalupska, Dominika; Gornicki, Piotr; Hanna, Philip C; Tsodikov, Oleg V; Joachimiak, Andrzej; Garneau-Tsodikova, Sylvie

    2015-05-26

    Proteins from the enhanced intracellular survival (Eis) family are versatile acetyltransferases that acetylate amines at multiple positions of several aminoglycosides (AGs). Their upregulation confers drug resistance. Homologues of Eis are present in diverse bacteria, including many pathogens. Eis from Mycobacterium tuberculosis (Eis_Mtb) has been well characterized. In this study, we explored the AG specificity and catalytic efficiency of the Eis family protein from Bacillus anthracis (Eis_Ban). Kinetic analysis of specificity and catalytic efficiency of acetylation of six AGs indicates that Eis_Ban displays significant differences from Eis_Mtb in both substrate binding and catalytic efficiency. The number of acetylated amines was also different for several AGs, indicating a distinct regiospecificity of Eis_Ban. Furthermore, most recently identified inhibitors of Eis_Mtb did not inhibit Eis_Ban, underscoring the differences between these two enzymes. To explain these differences, we determined an Eis_Ban crystal structure. The comparison of the crystal structures of Eis_Ban and Eis_Mtb demonstrates that critical residues lining their respective substrate binding pockets differ substantially, explaining their distinct specificities. Our results suggest that acetyltransferases of the Eis family evolved divergently to garner distinct specificities while conserving catalytic efficiency, possibly to counter distinct chemical challenges. The unique specificity features of these enzymes can be utilized as tools for developing AGs with novel modifications and help guide specific AG treatments to avoid Eis-mediated resistance. PMID:25928210

  18. Immunolocalization of choline acetyltransferase of common type in the central brain mass of Octopus vulgaris.

    PubMed

    Casini, A; Vaccaro, R; D'Este, L; Sakaue, Y; Bellier, J P; Kimura, H; Renda, T G

    2012-07-19

    Acetylcholine, the first neurotransmitter to be identified in the vertebrate frog, is widely distributed among the animal kingdom. The presence of a large amount of acetylcholine in the nervous system of cephalopods is well known from several biochemical and physiological studies. However, little is known about the precise distribution of cholinergic structures due to a lack of a suitable histochemical technique for detecting acetylcholine. The most reliable method to visualize the cholinergic neurons is the immunohistochemical localization of the enzyme choline acetyltransferase, the synthetic enzyme of acetylcholine. Following our previous study on the distribution patterns of cholinergic neurons in the Octopus vulgaris visual system, using a novel antibody that recognizes choline acetyltransferase of the common type (cChAT), now we extend our investigation on the octopus central brain mass. When applied on sections of octopus central ganglia, immunoreactivity for cChAT was detected in cell bodies of all central brain mass lobes with the notable exception of the subfrontal and subvertical lobes. Positive varicosed nerves fibers where observed in the neuropil of all central brain mass lobes.

  19. Intracellular localization of α-tubulin acetyltransferase ATAT1 in rat ciliated cells.

    PubMed

    Nakakura, Takashi; Suzuki, Takeshi; Nemoto, Takahiro; Tanaka, Hideyuki; Asano-Hoshino, Anshin; Arisawa, Kenjiro; Nishijima, Yoshimi; Kiuchi, Yoshiko; Hagiwara, Haruo

    2016-09-01

    Cilia are microtubule-based hair-like organelles on basal bodies located beneath the cell membrane in various tissues of multicellular animals, and are usually classified into motile cilia and primary cilia. Microtubules are assembled from the heterodimers of α- and β-tubulin. The lysine residue at position 40 (K40) of α-tubulin is an important site for acetylation, and this site is acetylated in the cilium. α-Tubulin N-acetyltransferase 1 (ATAT1) is an acetyltransferase specific to the K40 residue of α-tubulin; however, its intracellular distribution in mammalian tissues remains unclear. In this study, we analyzed ATAT1 localization in rat trachea, oviduct, kidney, retina, testis and the third ventricle of the brain by immunohistochemical techniques using a specific antibody against ATAT1. ATAT1 was distributed to the motile cilia of multiciliated cells of the trachea, third ventricle of the brain and oviduct, and in the primary cilia of the renal medullary collecting duct. ATAT1 also localized to the primary cilia, inner and outer segments of retinal photoreceptor cells, and at the Golgi apparatus of spermatocytes and spermatids of testis. These results indicated that α-tubulin acetylation by ATAT1 at distinct subcellular positions may influence the functional regulation of microtubules and cilia in a variety of ciliated cells. PMID:26700226

  20. The Protein Acetyltransferase PatZ from Escherichia coli Is Regulated by Autoacetylation-induced Oligomerization*

    PubMed Central

    de Diego Puente, Teresa; Gallego-Jara, Julia; Castaño-Cerezo, Sara; Bernal Sánchez, Vicente; Fernández Espín, Vanesa; García de la Torre, José; Manjón Rubio, Arturo; Cánovas Díaz, Manuel

    2015-01-01

    Lysine acetylation is an important post-translational modification in the metabolic regulation of both prokaryotes and eukaryotes. In Escherichia coli, PatZ (formerly YfiQ) is the only known acetyltransferase protein and is responsible for acetyl-CoA synthetase acetylation. In this study, we demonstrated PatZ-positive cooperativity in response to acetyl-CoA and the regulation of acetyl-CoA synthetase activity by the acetylation level. Furthermore, functional analysis of an E809A mutant showed that the conserved glutamate residue is not relevant for the PatZ catalytic mechanism. Biophysical studies demonstrated that PatZ is a stable tetramer in solution and is transformed to its octameric form by autoacetylation. Moreover, this modification is reversed by the sirtuin CobB. Finally, an in silico PatZ tetramerization model based on hydrophobic and electrostatic interactions is proposed and validated by three-dimensional hydrodynamic analysis. These data reveal, for the first time, the structural regulation of an acetyltransferase by autoacetylation in a prokaryotic organism. PMID:26251518

  1. Acetyltransferase SAS2 and sirtuin SIR2, respectively, control flocculation and biofilm formation in wine yeast.

    PubMed

    Rodriguez, María E; Orozco, Helena; Cantoral, Jesús M; Matallana, Emilia; Aranda, Agustín

    2014-09-01

    Cell-to-cell and cell-to-environment interactions of microorganisms are of substantial relevance for their biotechnological use. In the yeast Saccharomyces cerevisiae, flocculation can be an advantage to clarify final liquid products after fermentation, and biofilm formation may be relevant for the encapsulation of strains of interest. The adhesion properties of wine yeast strains can be modified by the genetic manipulation of transcriptional regulatory proteins, such as histone deacetylases, and acetylases. Sirtuin SIR2 is essential for the formation of mat structures, a kind of biofilm that requires the expression of cell-wall protein FLO11 as its deletion reduces FLO11 expression, and adhesion of cells to themselves and to agar in a commercial wine strain. Deletion of acetyltransferase GCN5 leads to a similar phenotype. A naturally flocculant wine yeast strain called P2 was characterized. Its flocculation happens only during grape juice fermentation and is due to the presence of a highly transcribed version of flocculin FLO5, linked to the presence of a δ sequence in the promoter. Deletion of acetyltransferase SAS2 enhances this phenotype and maltose fermentation even more. Therefore, the manipulation of acetylation/deacetylation machinery members is a valid way to alter the interaction of industrial yeast to their environment.

  2. The N-terminal acetyltransferase Naa10 is essential for zebrafish development

    PubMed Central

    Ree, Rasmus; Myklebust, Line M.; Thiel, Puja; Foyn, Håvard; Fladmark, Kari E.; Arnesen, Thomas

    2015-01-01

    N-terminal acetylation, catalysed by N-terminal acetyltransferases (NATs), is among the most common protein modifications in eukaryotes and involves the transfer of an acetyl group from acetyl-CoA to the α-amino group of the first amino acid. Functions of N-terminal acetylation include protein degradation and sub-cellular targeting. Recent findings in humans indicate that a dysfunctional Nα-acetyltransferase (Naa) 10, the catalytic subunit of NatA, the major NAT, is associated with lethality during infancy. In the present study, we identified the Danio rerio orthologue zebrafish Naa 10 (zNaa10). In vitro N-terminal acetylation assays revealed that zNaa10 has NAT activity with substrate specificity highly similar to that of human Naa10. Spatiotemporal expression pattern was determined by in situ hybridization, showing ubiquitous expression with especially strong staining in brain and eye. By morpholino-mediated knockdown, we demonstrated that naa10 morphants displayed increased lethality, growth retardation and developmental abnormalities like bent axis, abnormal eyes and bent tails. In conclusion, we identified the zebrafish Naa10 orthologue and revealed that it is essential for normal development and viability of zebrafish. PMID:26251455

  3. Cysteine biosynthesis in Lactobacillus casei: identification and characterization of a serine acetyltransferase.

    PubMed

    Bogicevic, Biljana; Berthoud, Hélène; Portmann, Reto; Bavan, Tharmatha; Meile, Leo; Irmler, Stefan

    2016-02-01

    In bacteria, cysteine can be synthesized from serine by two steps involving an L-serine O-acetyltransferase (SAT) and a cysteine synthase (CysK). While CysK is found in the publicly available annotated genome from Lactobacillus casei ATCC 334, a gene encoding SAT (cysE) is missing. In this study, we found that various strains of L. casei grew in a chemically defined medium containing sulfide as the sole sulfur source, indicating the presence of a serine O-acetyltransferase. The gene lying upstream of cysK is predicted to encode a homoserine trans-succinylase (metA). To study the function of this gene, it was cloned from L. casei FAM18110. The purified, recombinant protein did not acylate L-homoserine in vitro. Instead, it catalyzed the formation of O-acetyl serine from L-serine and acetyl-CoA. Furthermore, the plasmid expressing the L. casei gene complemented an Escherichia coli cysE mutant strain but not an E. coli metA mutant. This clearly demonstrated that the gene annotated as metA in fact encodes the SAT function and should be annotated as cysE. PMID:26790714

  4. The Protein Acetyltransferase PatZ from Escherichia coli Is Regulated by Autoacetylation-induced Oligomerization.

    PubMed

    de Diego Puente, Teresa; Gallego-Jara, Julia; Castaño-Cerezo, Sara; Bernal Sánchez, Vicente; Fernández Espín, Vanesa; García de la Torre, José; Manjón Rubio, Arturo; Cánovas Díaz, Manuel

    2015-09-18

    Lysine acetylation is an important post-translational modification in the metabolic regulation of both prokaryotes and eukaryotes. In Escherichia coli, PatZ (formerly YfiQ) is the only known acetyltransferase protein and is responsible for acetyl-CoA synthetase acetylation. In this study, we demonstrated PatZ-positive cooperativity in response to acetyl-CoA and the regulation of acetyl-CoA synthetase activity by the acetylation level. Furthermore, functional analysis of an E809A mutant showed that the conserved glutamate residue is not relevant for the PatZ catalytic mechanism. Biophysical studies demonstrated that PatZ is a stable tetramer in solution and is transformed to its octameric form by autoacetylation. Moreover, this modification is reversed by the sirtuin CobB. Finally, an in silico PatZ tetramerization model based on hydrophobic and electrostatic interactions is proposed and validated by three-dimensional hydrodynamic analysis. These data reveal, for the first time, the structural regulation of an acetyltransferase by autoacetylation in a prokaryotic organism.

  5. Determining the coordinate dependence of some components of the cubic susceptibility tensor {chi}-hat{sub yyyy}{sup (3)}(z, {omega}, -{omega}, {omega}, {omega}) of a one-dimensionally inhomogeneous absorbing plate at an arbitrary frequency dispersion

    SciTech Connect

    Golubkov, A A; Makarov, Vladimir A

    2010-12-29

    The possibility of unique reconstruction of the spatial profile of the cubic nonlinear susceptibility tensor component {chi}-hat{sub yyyy}{sup (3)}(z, {omega}, -{omega}, {omega}, {omega}) of a one-dimensionally inhomogeneous plate whose medium has a symmetry plane m{sub y} perpendicular to its surface is proved for the first time and the unique reconstruction algorithm is proposed. The amplitude complex coefficients of reflection and transmission (measured in some range of angles of incidence) as well as of conversion of an s-polarised plane signal monochromatic wave into two waves propagating on both sides of the plate make it possible to reconstruct the profile. These two waves result from nonlinear interaction of a signal wave with an intense plane wave incident normally on the plate. All the waves under consideration have the same frequency {omega}, and so its variation helps study the frequency dispersion of the cubic nonlinear susceptibility tensor component {chi}-hat{sub yyyy}{sup (3)}(z, {omega}, -{omega}, {omega}, {omega}). For media with additional symmetry axes 2{sub z}, 4{sub z}, 6{sub z}, or {infinity}{sub z} that are perpendicular to the plate surface, the proposed method can be used to reconstruct the profile and to examine the frequency dispersion of about one third of all independent complex components of the tensor {chi}-hat{sup (3)}. (nonlinear-optics phenomena)

  6. Catalytic Mechanism of Perosamine N-Acetyltransferase Revealed by High-Resolution X-ray Crystallographic Studies and Kinetic Analyses

    SciTech Connect

    Thoden, James B.; Reinhardt, Laurie A.; Cook, Paul D.; Menden, Patrick; Cleland, W.W.; Holden, Hazel M.

    2012-09-17

    N-Acetylperosamine is an unusual dideoxysugar found in the O-antigens of some Gram-negative bacteria, including the pathogenic Escherichia coli strain O157:H7. The last step in its biosynthesis is catalyzed by PerB, an N-acetyltransferase belonging to the left-handed {beta}-helix superfamily of proteins. Here we describe a combined structural and functional investigation of PerB from Caulobacter crescentus. For this study, three structures were determined to 1.0 {angstrom} resolution or better: the enzyme in complex with CoA and GDP-perosamine, the protein with bound CoA and GDP-N-acetylperosamine, and the enzyme containing a tetrahedral transition state mimic bound in the active site. Each subunit of the trimeric enzyme folds into two distinct regions. The N-terminal domain is globular and dominated by a six-stranded mainly parallel {beta}-sheet. It provides most of the interactions between the protein and GDP-perosamine. The C-terminal domain consists of a left-handed {beta}-helix, which has nearly seven turns. This region provides the scaffold for CoA binding. On the basis of these high-resolution structures, site-directed mutant proteins were constructed to test the roles of His 141 and Asp 142 in the catalytic mechanism. Kinetic data and pH-rate profiles are indicative of His 141 serving as a general base. In addition, the backbone amide group of Gly 159 provides an oxyanion hole for stabilization of the tetrahedral transition state. The pH-rate profiles are also consistent with the GDP-linked amino sugar substrate entering the active site in its unprotonated form. Finally, for this investigation, we show that PerB can accept GDP-3-deoxyperosamine as an alternative substrate, thus representing the production of a novel trideoxysugar.

  7. Microscopy-based Saccharomyces cerevisiae complementation model reveals functional conservation and redundancy of N-terminal acetyltransferases.

    PubMed

    Osberg, Camilla; Aksnes, Henriette; Ninzima, Sandra; Marie, Michaël; Arnesen, Thomas

    2016-01-01

    N-terminal acetylation is a highly abundant protein modification catalyzed by N-terminal acetyltransferases (NATs) NatA-NatG. The Saccharomyces cerevisiae protein Arl3 depends on interaction with Sys1 for its localization to the Golgi and this targeting strictly requires NatC-mediated N-terminal acetylation of Arl3. We utilized the Arl3 acetylation-dependent localization phenotype as a model system for assessing the functional conservation and in vivo redundancy of several human NATs. The catalytic subunit of human NatC, hNaa30 (Mak3), restored Arl3 localization in the absence of yNaa30, but only in the presence of either yeast or human Naa35 subunit (Mak10). In contrast, hNaa35 was not able to replace its yeast orthologue without the co-expression of hNaa30, suggesting co-evolution of the two NatC subunits. The most recently discovered and organellar human NAT, NatF/Naa60, restored the Golgi localization of Arl3 in the absence of yNaa30. Interestingly, this was also true for hNaa60 lacking its membrane-binding domain whereas hNaa50 did not complement NatC function. This in vivo redundancy reflects NatC and NatF´s overlapping in vitro substrate specificities. The yeast model presented here provides a robust and rapid readout of NatC and NatF activity in vivo, and revealed evolutionary conservation of the NatC complex and redundancy between NatC and NatF. PMID:27555049

  8. Microscopy-based Saccharomyces cerevisiae complementation model reveals functional conservation and redundancy of N-terminal acetyltransferases

    PubMed Central

    Osberg, Camilla; Aksnes, Henriette; Ninzima, Sandra; Marie, Michaël; Arnesen, Thomas

    2016-01-01

    N-terminal acetylation is a highly abundant protein modification catalyzed by N-terminal acetyltransferases (NATs) NatA-NatG. The Saccharomyces cerevisiae protein Arl3 depends on interaction with Sys1 for its localization to the Golgi and this targeting strictly requires NatC-mediated N-terminal acetylation of Arl3. We utilized the Arl3 acetylation-dependent localization phenotype as a model system for assessing the functional conservation and in vivo redundancy of several human NATs. The catalytic subunit of human NatC, hNaa30 (Mak3), restored Arl3 localization in the absence of yNaa30, but only in the presence of either yeast or human Naa35 subunit (Mak10). In contrast, hNaa35 was not able to replace its yeast orthologue without the co-expression of hNaa30, suggesting co-evolution of the two NatC subunits. The most recently discovered and organellar human NAT, NatF/Naa60, restored the Golgi localization of Arl3 in the absence of yNaa30. Interestingly, this was also true for hNaa60 lacking its membrane-binding domain whereas hNaa50 did not complement NatC function. This in vivo redundancy reflects NatC and NatF´s overlapping in vitro substrate specificities. The yeast model presented here provides a robust and rapid readout of NatC and NatF activity in vivo, and revealed evolutionary conservation of the NatC complex and redundancy between NatC and NatF. PMID:27555049

  9. Mechanism of action of peptidoglycan O-acetyltransferase B involves a Ser-His-Asp catalytic triad.

    PubMed

    Moynihan, Patrick J; Clarke, Anthony J

    2014-10-01

    The O-acetylation of the essential cell wall polymer peptidoglycan is essential in many bacteria for their integrity and survival, and it is catalyzed by peptidoglycan O-acetlytransferase B (PatB). Using PatB from Neisseria gonorrhoeae as the model, we have shown previously that the enzyme has specificity for polymeric muropeptides that possess tri- and tetrapeptide stems and that rates of reaction increase with increasing degrees of polymerization. Here, we present the catalytic mechanism of action of PatB, the first to be described for an O-acetyltransferase of any bacterial exopolysaccharide. The influence of pH on PatB activity was investigated, and pKa values of 6.4-6.45 and 6.25-6.35 for the enzyme-substrate complex (kcat vs pH) and the free enzyme (kcat·KM(-1) vs pH), respectively, were determined for the respective cosubstrates. The enzyme is partially inactivated by sulfonyl fluorides but not by EDTA, suggesting the participation of a serine residue in its catalytic mechanism. Alignment of the known and hypothetical PatB amino acid sequences identified Ser133, Asp302, and His305 as three invariant amino acid residues that could potentially serve as a catalytic triad. Replacement of Asp302 with Ala resulted in an enzyme with less than 20% residual activity, whereas activity was barely detectable with (His305 → Ala)PatB and (Ser133 → Ala)PatB was totally inactive. The reaction intermediate of the transferase reaction involving acetyl- and propionyl-acyl donors was trapped on both the wild-type and (Asp302 → Ala) enzymes and LC-MS/MS analysis of tryptic peptides identified Ser133 as the catalytic nucleophile. A transacetylase mechanism is proposed based on the mechanism of action of serine esterases. PMID:25215566

  10. Design and fabrication of hat-shaped stiffened panel by resin transfer molding method

    SciTech Connect

    Bell, R.; Ibekwe, S.I.; Mensah, P.F.; Chehl, S.S.

    1998-12-31

    Hat-shaped stiffened composite panels were fabricated by resin transfer molding (RTM) process. As application of these compression load bearing panels in aircraft wings and fuselage increases, this promising manufacturing technique would contribute towards the goal of attaining reduced part counts and cheaper manufacturing costs. Rigid foam which increases the structural efficiency of panels was utilized in this process. Also Balsa wood was considered as an alternative to the rigid foam and employed as a permanent mandrel in fabricating one of the panels. Buckling analysis result by finite element method and modified closed form solution suggested by Agarwal et al. (1974) agree. Once this process is fine-tuned, it would provide a cheaper method of fabricating composite hat-stiffened panels.

  11. Exploring the unlimited possibilities of modular aspheric Gauss to top-hat beam shaping

    NASA Astrophysics Data System (ADS)

    Möhl, Anna; Fuchs, Ulrike

    2016-06-01

    Beam shaping is a field of research with growing importance. Therefore, a new refractive beam shaping system is presented. The knowledge gained from analyzing patent systems was used to derive our own improved design. It is compared to a patent system, and some selected results are presented in this work. Furthermore, possibilities to scale the entrance and exit beam diameters with the help of SPA™ Beam Expander Kit and SPA™ AspheriColl (both from asphericon GmbH, Jena, Germany) are shown, so that a modular top-hat generation is achievable. Additionally, the large spectral range in which the beam shaping system is applicable is demonstrated, and it is demonstrated how the beam shaping system can be used to improve the performance of other optical elements that require a top-hat beam profile.

  12. High-power Er:YAG laser with quasi-top-hat output beam.

    PubMed

    Kim, J W; Mackenzie, J I; Hayes, J R; Clarkson, W A

    2012-05-01

    A simple method for simultaneously exciting the fundamental (TEM00) transverse mode and first order Laguerre-Gaussian (LG01) donut mode in an end-pumped solid-state laser to yield a quasi-top-hat output beam is reported. This approach has been applied to an Er:YAG laser, in-band pumped by an Er,Yb fiber laser, yielding 9.6 W of continuous-wave output at 1645 nm in a top-hat-like beam with beam propagation factor (M2)<2.1 for 24 W of incident pump power at 1532 nm. The corresponding slope efficiency with respect to incident pump power was 49%. The prospects of further scaling of output power and improved overall efficiency are considered.

  13. Kepler's optical phase curve of the exoplanet HAT-P-7b.

    PubMed

    Borucki, W J; Koch, D; Jenkins, J; Sasselov, D; Gilliland, R; Batalha, N; Latham, D W; Caldwell, D; Basri, G; Brown, T; Christensen-Dalsgaard, J; Cochran, W D; DeVore, E; Dunham, E; Dupree, A K; Gautier, T; Geary, J; Gould, A; Howell, S; Kjeldsen, H; Lissauer, J; Marcy, G; Meibom, S; Morrison, D; Tarter, J

    2009-08-01

    Ten days of photometric data were obtained during the commissioning phase of the Kepler mission, including data for the previously known giant transiting exoplanet HAT-P-7b. The data for HAT-P-7b show a smooth rise and fall of light from the planet as it orbits its star, punctuated by a drop of 130 +/- 11 parts per million in flux when the planet passes behind its star. We interpret this as the phase variation of the dayside thermal emission plus reflected light from the planet as it orbits its star and is occulted. The depth of the occultation is similar in photometric precision to the detection of a transiting Earth-size planet for which the mission was designed.

  14. Origin of the Napoleon's hat nebula around SN1987A and implications for the progenitor

    NASA Astrophysics Data System (ADS)

    Podsiadlowski, Ph.; Fabian, A. C.; Stevens, I. R.

    1991-11-01

    A simple geometrical model for the emission nebula around SN1987A, whose morphology has been likened to Napoleon's hat, is presented. The model consists of a ring and a truncated double cone. When the effects of light travel time are included, the model reproduces the important topological structures of the nebula and makes detailed quantitative predictions for its future appearance. In particular, the hat-shaped northern rim is simply explained as the interaction of the light front with the northern cone. To explain the origin of the double cone, it is argued that the progenitor of SN1987A was in a binary system: its strong wind, colliding with a weaker wind from the companion star, created an asymptotic shock surface that was spread out into the required geometry by the rotation of the binary.

  15. Kepler's optical phase curve of the exoplanet HAT-P-7b.

    PubMed

    Borucki, W J; Koch, D; Jenkins, J; Sasselov, D; Gilliland, R; Batalha, N; Latham, D W; Caldwell, D; Basri, G; Brown, T; Christensen-Dalsgaard, J; Cochran, W D; DeVore, E; Dunham, E; Dupree, A K; Gautier, T; Geary, J; Gould, A; Howell, S; Kjeldsen, H; Lissauer, J; Marcy, G; Meibom, S; Morrison, D; Tarter, J

    2009-08-01

    Ten days of photometric data were obtained during the commissioning phase of the Kepler mission, including data for the previously known giant transiting exoplanet HAT-P-7b. The data for HAT-P-7b show a smooth rise and fall of light from the planet as it orbits its star, punctuated by a drop of 130 +/- 11 parts per million in flux when the planet passes behind its star. We interpret this as the phase variation of the dayside thermal emission plus reflected light from the planet as it orbits its star and is occulted. The depth of the occultation is similar in photometric precision to the detection of a transiting Earth-size planet for which the mission was designed. PMID:19661420

  16. VizieR Online Data Catalog: Transmission spectroscopy of HAT-P-32b (Mallonn+, 2016)

    NASA Astrophysics Data System (ADS)

    Mallonn, M.; Strassmeier, K. G.

    2016-05-01

    A set of 62 simultaneous photometric light curves from 3300 to 10000Å of a transit event of HAT-P-32b. The wavelength range of each light curve is ~100Å in average. The light curves cover about one hour pre-transit, the transit event, and about 1 hour post-transit. Observations have been taken with MODS at LBT in multi-object mode. Light curves are given in differential magnitudes. (2 data files).

  17. HAT-P-26b: A Neptune-mass Exoplanet with Primordial Solar Heavy Element Abundance

    NASA Astrophysics Data System (ADS)

    Wakeford, Hannah; Sing, David; Deming, Drake; Kataria, Tiffany; Lopez, Eric

    2016-10-01

    A trend in giant planet mass and atmospheric heavy elemental abundance was first noted last century from observations of planets in our own solar system. These four data points from Jupiter, Saturn, Uranus, and Neptune have served as a corner stone of planet formation theory. Here we add another point in the mass-metallicity trend from a detailed observational study of the extrasolar planet HAT-P-26b, which inhabits the critical mass regime near Neptune and Uranus. Neptune-sized worlds are among the most common planets in our galaxy and frequently exist in orbital periods very different from that of our own solar system ice giants. Atmospheric studies are the principal window into these worlds, and thereby into their formation and evolution, beyond those of our own solar system. Using the Hubble Space Telescope and Spitzer, from the optical to the infrared, we conducted a detailed atmospheric study of the Neptune-mass exoplanet HAT-P-26b over 0.5 to 4.5 μm. We detect prominent H2O absorption at 1.4 μm to 525 ppm in the atmospheric transmission spectrum. We determine that HAT-P-26b's atmosphere is not rich in heavy elements (≈1.8×solar), which goes distinctly against the solar system mass-metallicity trend. This likely indicates that HAT-P-26b's atmosphere is primordial and obtained its gaseous envelope late in its disk lifetime with little contamination from metal-rich planetesimals.

  18. The diversification and activity of hAT transposons in Musa genomes.

    PubMed

    Menzel, Gerhard; Heitkam, Tony; Seibt, Kathrin M; Nouroz, Faisal; Müller-Stoermer, Manuela; Heslop-Harrison, John S; Schmidt, Thomas

    2014-12-01

    Sequencing of plant genomes often identified the hAT superfamily as the largest group of DNA transposons. Nevertheless, detailed information on the diversity, abundance and chromosomal localization of plant hAT families are rare. By in silico analyses of the reference genome assembly and bacterial artificial chromosome (BAC) sequences, respectively, we performed the classification and molecular characterization of hAT transposon families in Musa acuminata. Musa hAT transposons are organized in three families designated MuhAT I, MuhAT II and MuhAT III. In total, 70 complete autonomous elements of the MuhAT I and MuhAT II families were detected, while no autonomous MuhAT III transposons were found. Based on the terminal inverted repeat (TIR)-specific sequence information of the autonomous transposons, 1722 MuhAT I- and MuhAT II-specific miniature inverted-repeat transposable elements (MuhMITEs) were identified. Autonomous MuhAT I and MuhAT II elements are only moderately abundant in the sections of the genus Musa, while the corresponding MITEs exhibit an amplification in Musa genomes. By fluorescent in situ hybridization (FISH), autonomous MuhAT transposons as well as MuhMITEs were localized in subtelomeric, most likely gene-rich regions of M. acuminata chromosomes. A comparison of homoeologous regions of M. acuminata and Musa balbisiana BACs revealed the species-specific mobility of MuhMITEs. In particular, the activity of MuhMITEs II showing transduplications of genomic sequences might indicate the presence of active MuhAT transposons, thus suggesting a potential role of MuhMITEs as modulators of genome evolution of Musa.

  19. A lower radius and mass for the transiting extrasolar planet HAT-P-8 b

    NASA Astrophysics Data System (ADS)

    Mancini, L.; Southworth, J.; Ciceri, S.; Fortney, J. J.; Morley, C. V.; Dittmann, J. A.; Tregloan-Reed, J.; Bruni, I.; Barbieri, M.; Evans, D. F.; D'Ago, G.; Nikolov, N.; Henning, Th.

    2013-03-01

    Context. The extrasolar planet HAT-P-8 b was thought to be one of the more inflated transiting hot Jupiters. Aims: By using new and existing photometric data, we computed precise estimates of the physical properties of the system. Methods: We present photometric observations comprising eleven light curves covering six transit events, obtained using five medium-class telescopes and telescope-defocussing technique. One transit was simultaneously obtained through four optical filters, and two transits were followed contemporaneously from two observatories. We modelled these and seven published datasets using the jktebop code. The physical parameters of the system were obtained from these results and from published spectroscopic measurements. In addition, we investigated the theoretically-predicted variation of the apparent planetary radius as a function of wavelength, covering the range 330-960 nm. Results: We find that HAT-P-8 b has a significantly lower radius (1.321 ± 0.037 RJup) and mass (1.275 ± 0.053 MJup) compared to previous estimates (1.50-0.06+0.08 R_{Jup} and 1.52-0.16+0.18 M_{Jup} respectively). We also detect a radius variation in the optical bands that, when compared with synthetic spectra of the planet, may indicate the presence of a strong optical absorber, perhaps TiO and VO gases, near the terminator of HAT-P-8 b. Conclusions: These new results imply that HAT-P-8 b is not significantly inflated, and that its position in the planetary mass-radius diagram is congruent with those of many other transiting extrasolar planets. Full Table 2 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/551/A11

  20. RSRM top hat cover simulator lightning test, volume 2. Appendix A: Resistance measurements. Appendix B: Lightning test data plots

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Resistance measurements are given in graphical for when a simulated lightning discharge strikes on an exposed top hat cover simulator. The test sequence was to measure the electric and magnetic fields induced inside a redesigned solid rocket motor case.

  1. A spin-orbit alignment for the hot Jupiter HATS-3b

    SciTech Connect

    Addison, B. C.; Tinney, C. G.; Wright, D. J.; Bayliss, D.

    2014-09-10

    We have measured the alignment between the orbit of HATS-3b (a recently discovered, slightly inflated Hot Jupiter) and the spin axis of its host star. Data were obtained using the CYCLOPS2 optical-fiber bundle and its simultaneous calibration system feeding the UCLES spectrograph on the Anglo-Australian Telescope. The sky-projected spin-orbit angle of λ = 3° ± 25° was determined from spectroscopic measurements of the Rossiter-McLaughlin effect. This is the first exoplanet discovered through the HATSouth transit survey to have its spin-orbit angle measured. Our results indicate that the orbital plane of HATS-3b is consistent with being aligned to the spin axis of its host star. The low obliquity of the HATS-3 system, which has a relatively hot mid F-type host star, agrees with the general trend observed for Hot Jupiter host stars with effective temperatures >6250 K to have randomly distributed spin-orbit angles.

  2. HATS-4b: A dense hot Jupiter transiting a super metal-rich G star

    SciTech Connect

    Jordán, Andrés; Brahm, Rafael; Rabus, M.; Suc, V.; Espinoza, N.; Bakos, G. Á.; Penev, K.; Hartman, J. D.; Csubry, Z.; Bhatti, W.; De Val Borro, M.; Bayliss, D.; Zhou, G.; Mancini, L.; Mohler-Fischer, M.; Ciceri, S.; Csák, B.; Henning, T.; Sato, B.; Buchhave, L.; and others

    2014-08-01

    We report the discovery by the HATSouth survey of HATS-4b, an extrasolar planet transiting a V = 13.46 mag G star. HATS-4b has a period of P ≈ 2.5167 days, mass of M{sub p} ≈ 1.32 M {sub Jup}, radius of R{sub p} ≈ 1.02 R {sub Jup}, and density of ρ {sub p} = 1.55 ± 0.16 g cm{sup –3} ≈1.24 ρ{sub Jup}. The host star has a mass of 1.00 M {sub ☉}, a radius of 0.92 R {sub ☉}, and a very high metallicity [Fe/H]=0.43 ± 0.08. HATS-4b is among the densest known planets with masses between 1 and 2 M {sub J} and is thus likely to have a significant content of heavy elements of the order of 75 M {sub ⊕}. In this paper we present the data reduction, radial velocity measurements, and stellar classification techniques adopted by the HATSouth survey for the CORALIE spectrograph. We also detail a technique for simultaneously estimating vsin i and macroturbulence using high resolution spectra.

  3. iHAT: interactive hierarchical aggregation table for genetic association data.

    PubMed

    Heinrich, Julian; Vehlow, Corinna; Battke, Florian; Jäger, Günter; Weiskopf, Daniel; Nieselt, Kay

    2012-01-01

    In the search for single-nucleotide polymorphisms which influence the observable phenotype, genome wide association studies have become an important technique for the identification of associations between genotype and phenotype of a diverse set of sequence-based data. We present a methodology for the visual assessment of single-nucleotide polymorphisms using interactive hierarchical aggregation techniques combined with methods known from traditional sequence browsers and cluster heatmaps. Our tool, the interactive Hierarchical Aggregation Table (iHAT), facilitates the visualization of multiple sequence alignments, associated metadata, and hierarchical clusterings. Different color maps and aggregation strategies as well as filtering options support the user in finding correlations between sequences and metadata. Similar to other visualizations such as parallel coordinates or heatmaps, iHAT relies on the human pattern-recognition ability for spotting patterns that might indicate correlation or anticorrelation. We demonstrate iHAT using artificial and real-world datasets for DNA and protein association studies as well as expression Quantitative Trait Locus data.

  4. The refined physical parameters of transiting exoplanet system HAT-P-24

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Bin; Gu, Sheng-Hong; Collier Cameron, Andrew; Tan, Hong-Bo; Hui, Ho-Keung; Kwok, Chi-Tai; Yeung, Bill; Leung, Kam-Cheung

    2013-05-01

    The transiting exoplanet system HAT-P-24 was observed by using CCD cameras at Yunnan Observatory and Hokoon Astronomical Centre, China in 2010 and 2012. In order to enhance the signal to noise ratio of transit events, the observed data are corrected for systematic errors according to Collier Cameron et al.'s coarse de-correlation and Tamuz et al.'s SYSREM algorithms. Three new complete transit light curves are analyzed by means of the Markov chain Monte Carlo technique, and the new physical parameters of the system are derived. They are consistent with the old ones from the discovered paper except for a new larger radius Rp = 1.364 RJ of HAT-P-24b, which confirms its inflated nature. By combining the five available epochs of mid-transit derived from complete transit light curves, the orbital period of HAT-P-24b is refined to P = 3.3552479 d and no obvious transit timing variation signal can be found from these five transit events during 2010-2012.

  5. INDEPENDENT DISCOVERY OF THE TRANSITING EXOPLANET HAT-P-14b

    SciTech Connect

    Simpson, E. K.; Barros, S. C. C.; Pollacco, D.; Faedi, F.; McCormac, J.; Brown, D. J. A.; Collier Cameron, A.; Enoch, B.; Skillen, I.; Stempels, H. C.; Boisse, I.; Hebrard, G.; Bouchy, F.; Sorensen, P.; Street, R. A.; Anderson, D.; Bento, J.; Butters, O. W.; Haswell, C. A.; Hebb, L.

    2011-05-15

    We present SuperWASP observations of HAT-P-14b, a hot Jupiter discovered by Torres et al. The planet was found independently by the SuperWASP team and named WASP-27b after follow-up observations had secured the discovery, but prior to the publication by Torres et al. Our analysis of HAT-P-14/WASP-27 is in good agreement with the values found by Torres et al. and we provide additional evidence against astronomical false positives. Due to the brightness of the host star, V{sub mag} = 10, HAT-P-14b is an attractive candidate for further characterization observations. The planet has a high impact parameter and the primary transit is close to grazing. This could readily reveal small deviations in the orbital parameters indicating the presence of a third body in the system, which may be causing the small but significant orbital eccentricity. Our results suggest that the planet may undergo a grazing secondary eclipse. However, even a non-detection would tightly constrain the system parameters.

  6. Detection of the Secondary Eclipse of Exoplanet HAT P-11b

    NASA Technical Reports Server (NTRS)

    Barry, R. K.; Deming, L. D.; Bakos, G.; Harrington, J.; Madhusudhan, N.; Noyes, R.; Seager, S.

    2010-01-01

    We have successfully conducted secondary eclipse observations of exoplanet HAT-P-11b using the Spitzer Space Telescope. HAT-P-11b was, until very recently, the smallest transiting extrasolar planet yet found and one of only two known exo-Neptunes. We observed the system at 3.6 microns for a period of 22 hours centered on the anticipated secondary eclipse time, to detect the eclipse and determine its phase. Having detected the secondary eclipse, we are at present making a more focused series of observations in both the 3.6 and 4.5 micron bands to fully characterize it. HAT-P-11b has a period of 4.8878 days, radius of 0.422 RJ, mass of 0.081 MJ and semi-major axis 0.053 AU. Measurements of the secondary eclipse will serve to clarify two key issues; 1) the planetary brightness temperature and the nature of its atmosphere, and 2) the eccentricity of its orbit, with implications for its dynamical evolution. A precise determination of the orbit phase for the secondary eclipse will also be of great utility for Kepler observations of this system at visible wavelengths.

  7. Formulating robust linear regression estimation as a one-class LDA criterion: discriminative hat matrix.

    PubMed

    Dufrenois, F; Noyer, J C

    2013-02-01

    Linear discriminant analysis, such as Fisher's criterion, is a statistical learning tool traditionally devoted to separating a training dataset into two or even several classes by the way of linear decision boundaries. In this paper, we show that this tool can formalize the robust linear regression problem as a robust estimator will do. More precisely, we develop a one-class Fischer's criterion in which the maximization provides both the regression parameters and the separation of the data in two classes: typical data and atypical data or outliers. This new criterion is built on the statistical properties of the subspace decomposition of the hat matrix. From this angle, we improve the discriminative properties of the hat matrix which is traditionally used as outlier diagnostic measure in linear regression. Naturally, we call this new approach discriminative hat matrix. The proposed algorithm is fully nonsupervised and needs only the initialization of one parameter. Synthetic and real datasets are used to study the performance both in terms of regression and classification of the proposed approach. We also illustrate its potential application to image recognition and fundamental matrix estimation in computer vision.

  8. Image registration algorithm using Mexican hat function-based operator and grouped feature matching strategy.

    PubMed

    Jin, Feng; Feng, Dazheng

    2014-01-01

    Feature detection and matching are crucial for robust and reliable image registration. Although many methods have been developed, they commonly focus on only one class of image features. The methods that combine two or more classes of features are still novel and significant. In this work, methods for feature detection and matching are proposed. A Mexican hat function-based operator is used for image feature detection, including the local area detection and the feature point detection. For the local area detection, we use the Mexican hat operator for image filtering, and then the zero-crossing points are extracted and merged into the area borders. For the feature point detection, the Mexican hat operator is performed in scale space to get the key points. After the feature detection, an image registration is achieved by using the two classes of image features. The feature points are grouped according to a standardized region that contains correspondence to the local area, precise registration is achieved eventually by the grouped points. An image transformation matrix is estimated by the feature points in a region and then the best one is chosen through competition of a set of the transformation matrices. This strategy has been named the Grouped Sample Consensus (GCS). The GCS has also ability for removing the outliers effectively. The experimental results show that the proposed algorithm has high registration accuracy and small computational volume. PMID:24752223

  9. Reconstruction-by-Dilation and Top-Hat Algorithms for Contrast Enhancement and Segmentation of Microcalcifications in Digital Mammograms

    NASA Astrophysics Data System (ADS)

    Diaz, Claudia C.

    2007-11-01

    I present some results of contrast enhancement and segmentation of microcalcifications in digital mammograms. These mammograms were obtained from MIAS-minidatabase and using a CR to digitize images. White-top-hat and black-top-hat transformations were used to improve the contrast of images, while reconstruction-by-dilation algorithm was used to emphasize the microcalcifications over the tissues. Segmentation was done using different gradient matrices. These algorithms intended to show some details which were not evident in original images.

  10. High-throughput screening identifies novel inhibitors of the acetyltransferase activity of Escherichia coli GlmU.

    PubMed

    Pereira, Mark P; Blanchard, Jan E; Murphy, Cecilia; Roderick, Steven L; Brown, Eric D

    2009-06-01

    The bifunctional GlmU protein catalyzes the formation of UDP-N-acetylglucosamine in a two-step reaction using the substrates glucosamine-1-phosphate, acetyl coenzyme A, and UTP. This metabolite is a common precursor to the synthesis of bacterial cell surface carbohydrate polymers, such as peptidoglycan, lipopolysaccharide, and wall teichoic acid that are involved in the maintenance of cell shape, permeability, and virulence. The C-terminal acetyltransferase domain of GlmU exhibits structural and mechanistic features unique to bacterial UDP-N-acetylglucosamine synthases, making it an excellent target for antibacterial design. In the work described here, we have developed an absorbance-based assay to screen diverse chemical libraries in high throughput for inhibitors to the acetyltransferase reaction of Escherichia coli GlmU. The primary screen of 50,000 drug-like small molecules identified 63 hits, 37 of which were specific to acetyltransferase activity of GlmU. Secondary screening and mode-of-inhibition studies identified potent inhibitors where compound binding within the acetyltransferase active site was requisite on the presence of glucosamine-1-phosphate and were competitive with the substrate acetyl coenzyme A. These molecules may represent novel chemical scaffolds for future antimicrobial drug discovery. In addition, this work outlines the utility of catalytic variants in targeting specific activities of bifunctional enzymes in high-throughput screens.

  11. Molecular characterization of the salutaridinol 7-O-acetyltransferase involved in morphine biosynthesis in opium poppy Papaver somniferum.

    PubMed

    Grothe, T; Lenz, R; Kutchan, T M

    2001-08-17

    Salutaridinol 7-O-acetyltransferase (EC ) catalyzes the conversion of the phenanthrene alkaloid salutaridinol to salutaridinol-7-O-acetate, the immediate precursor of thebaine along the morphine biosynthetic pathway. We have isolated a cDNA clone that corresponds to the internal amino acid sequences of the native enzyme purified from a cell suspension culture of opium poppy Papaver somniferum. The recombinant enzyme acetylated the 7-hydroxyl moiety of salutaridinol in the presence of acetyl-CoA. The apparent K(m) value for salutaridinol was determined to be 9 microm and 54 microm for acetyl-CoA. The gene transcript was detected in extracts from Papaver orientale and Papaver bracteatum in addition to P. somniferum. Genomic DNA gel blot analysis indicated that there is likely a single copy of this gene in the P. somniferum genome. The amino acid sequence of salutaridinol 7-O-acetyltransferase is most similar (37% identity) to that of deacetylvindoline acetyltransferase of Catharanthus roseus. Salutaridinol 7-O-acetyltransferase is the second enzyme specific to morphine biosynthesis for which we have isolated a cDNA. Taken together with the other cDNAs cloned encoding norcoclaurine 6-O-methyltransferase, (S)-N-methylcoclaurine 3'-hydroxylase, the cytochrome P-450 reductase, and codeinone reductase, significant progress has been made toward accumulating genes of this pathway to enable the end goal of a biotechnological production of morphinan alkaloids.

  12. Construction and Use of a Replication-Competent Human Immunodeficiency Virus (HIV-1) that Expresses the Chloramphenicol Acetyltransferase Enzyme

    NASA Astrophysics Data System (ADS)

    Terwilliger, E. F.; Godin, B.; Sodroski, J. G.; Haseltine, W. A.

    1989-05-01

    The construction and properties of an infectious human immunodeficiency virus (HIV) that expresses the bacterial gene chloramphenicol acetyltransferase are described. This virus can be used in vitro to screen for drugs that inhibit HIV infection. The marked virus may also be used to trace the routes of infection from the site of inoculation in animal experiments.

  13. Spin-orbit alignment for KELT-7b and HAT-P-56b via Doppler tomography with TRES

    NASA Astrophysics Data System (ADS)

    Zhou, George; Latham, David W.; Bieryla, Allyson; Beatty, Thomas G.; Buchhave, Lars A.; Esquerdo, Gilbert A.; Berlind, Perry; Calkins, Michael L.

    2016-08-01

    We present Doppler tomographic analyses for the spectroscopic transits of KELT-7b and HAT-P-56b, two hot-Jupiters orbiting rapidly rotating F-dwarf host stars. These include analyses of archival Tillinghast Reflector Echelle Spectrograph (TRES) observations for KELT-7b, and a new TRES transit observation of HAT-P-56b. We report spin-orbit aligned geometries for KELT-7b (2.7° ± 0.6°) and HAT-P-56b (8° ± 2°). The host stars KELT-7 and HAT-P-56 are among some of the most rapidly rotating planet-hosting stars known. We examine the tidal re-alignment model for the evolution of the spin-orbit angle in the context of the spin rates of these stars. We find no evidence that the rotation rates of KELT-7 and HAT-P-56 have been modified by star-planet tidal interactions, suggesting that the spin-orbit angle of systems around these hot stars may represent their primordial configuration. In fact, KELT-7 and HAT-P-56 are two of three systems in supersynchronous, spin-orbit aligned states, where the rotation periods of the host stars are faster than the orbital periods of the planets.

  14. Thermal and Mechanical Buckling Analysis of Hypersonic Aircraft Hat-Stiffened Panels With Varying Face Sheet Geometry and Fiber Orientation

    NASA Technical Reports Server (NTRS)

    Ko, William L.

    1996-01-01

    Mechanical and thermal buckling behavior of monolithic and metal-matrix composite hat-stiffened panels were investigated. The panels have three types of face-sheet geometry: Flat face sheet, microdented face sheet, and microbulged face sheet. The metal-matrix composite panels have three types of face-sheet layups, each of which is combined with various types of hat composite layups. Finite-element method was used in the eigenvalue extractions for both mechanical and thermal buckling. The thermal buckling analysis required both eigenvalue and material property iterations. Graphical methods of the dual iterations are shown. The mechanical and thermal buckling strengths of the hat-stiffened panels with different face-sheet geometry are compared. It was found that by just microdenting or microbulging of the face sheet, the axial, shear, and thermal buckling strengths of both types of hat-stiffened panels could be enhanced considerably. This effect is more conspicuous for the monolithic panels. For the metal-matrix composite panels, the effect of fiber orientations on the panel buckling strengths was investigated in great detail, and various composite layup combinations offering, high panel buckling strengths are presented. The axial buckling strength of the metal-matrix panel was sensitive to the change of hat fiber orientation. However, the lateral, shear, and thermal buckling strengths were insensitive to the change of hat fiber orientation.

  15. Characterization of the atmosphere of the hot Jupiter HAT-P-32Ab and the M-dwarf companion HAT-P-32B

    SciTech Connect

    Zhao, Ming; Wright, Jason T.; Curtis, Jason; O'Rourke, Joseph G.; Knutson, Heather A.; Ngo, Henry; Burrows, Adam; Fortney, Johnathan; Fulton, Benjamin J.; Baranec, Christoph; Riddle, Reed; Hinkley, Sasha; Law, Nicholas M.; Muirhead, Philip S.; Showman, Adam P.; Burruss, Rick

    2014-12-01

    We report secondary eclipse photometry of the hot Jupiter HAT-P-32Ab, taken with Hale/Wide-field Infra-Red Camera (WIRC) in H and K{sub S} bands and with Spitzer/IRAC at 3.6 and 4.5 μm. We carried out adaptive optics imaging of the planet host star HAT-P-32A and its companion HAT-P-32B in the near-IR and the visible. We clearly resolve the two stars from each other and find a separation of 2.''923 ± 0.''004 and a position angle 110.°64 ± 0.°12. We measure the flux ratios of the binary in g'r'i'z' and H and K{sub S} bands, and determine T {sub eff}= 3565 ± 82 K for the companion star, corresponding to an M1.5 dwarf. We use PHOENIX stellar atmosphere models to correct the dilution of the secondary eclipse depths of the hot Jupiter due to the presence of the M1.5 companion. We also improve the secondary eclipse photometry by accounting for the non-classical, flux-dependent nonlinearity of the WIRC IR detector in the H band. We measure planet-to-star flux ratios of 0.090% ± 0.033%, 0.178% ± 0.057%, 0.364% ± 0.016%, and 0.438% ± 0.020% in the H, K{sub S} , 3.6 and 4.5 μm bands, respectively. We compare these with planetary atmospheric models, and find they prefer an atmosphere with a temperature inversion and inefficient heat redistribution. However, we also find that the data are equally well described by a blackbody model for the planet with T {sub p} = 2042 ± 50 K. Finally, we measure a secondary eclipse timing offset of 0.3 ± 1.3 minutes from the predicted mid-eclipse time, which constrains e = 0.0072{sub −0.0064}{sup +0.0700} when combined with radial velocity data and is more consistent with a circular orbit.

  16. Characterization of the Atmosphere of the Hot Jupiter HAT-P-32Ab and the M-dwarf Companion HAT-P-32B

    NASA Astrophysics Data System (ADS)

    Zhao, Ming; O'Rourke, Joseph G.; Wright, Jason T.; Knutson, Heather A.; Burrows, Adam; Fortney, Johnathan; Ngo, Henry; Fulton, Benjamin J.; Baranec, Christoph; Riddle, Reed; Law, Nicholas M.; Muirhead, Philip S.; Hinkley, Sasha; Showman, Adam P.; Curtis, Jason; Burruss, Rick

    2014-12-01

    We report secondary eclipse photometry of the hot Jupiter HAT-P-32Ab, taken with Hale/Wide-field Infra-Red Camera (WIRC) in H and KS bands and with Spitzer/IRAC at 3.6 and 4.5 μm. We carried out adaptive optics imaging of the planet host star HAT-P-32A and its companion HAT-P-32B in the near-IR and the visible. We clearly resolve the two stars from each other and find a separation of 2.''923 ± 0.''004 and a position angle 110.°64 ± 0.°12. We measure the flux ratios of the binary in g'r'i'z' and H and KS bands, and determine T eff= 3565 ± 82 K for the companion star, corresponding to an M1.5 dwarf. We use PHOENIX stellar atmosphere models to correct the dilution of the secondary eclipse depths of the hot Jupiter due to the presence of the M1.5 companion. We also improve the secondary eclipse photometry by accounting for the non-classical, flux-dependent nonlinearity of the WIRC IR detector in the H band. We measure planet-to-star flux ratios of 0.090% ± 0.033%, 0.178% ± 0.057%, 0.364% ± 0.016%, and 0.438% ± 0.020% in the H, KS , 3.6 and 4.5 μm bands, respectively. We compare these with planetary atmospheric models, and find they prefer an atmosphere with a temperature inversion and inefficient heat redistribution. However, we also find that the data are equally well described by a blackbody model for the planet with T p = 2042 ± 50 K. Finally, we measure a secondary eclipse timing offset of 0.3 ± 1.3 minutes from the predicted mid-eclipse time, which constrains e = 0.0072+0.0700-0.0064 when combined with radial velocity data and is more consistent with a circular orbit.

  17. Effects of acute ethanol administration on nocturnal pineal serotonin N-acetyltransferase activity

    SciTech Connect

    Creighton, J.A.; Rudeen, P.K.

    1988-01-01

    The effect of acute ethanol administration on pineal serotonin N-acetyltransferase (NAT) activity, norepinephrine and indoleamine content was examined in male rats. When ethanol was administered in two equal doses (2 g/kg body weight) over a 4 hour period during the light phase, the nocturnal rise in NAT activity was delayed by seven hours. The nocturnal pineal norepinephrine content was not altered by ethanol except for a delay in the reduction of NE with the onset of the following light phase. Although ethanol treatment led to a significant reduction in nocturnal levels of pineal serotonin content, there was no significant effect upon pineal content of 5-hydroxyindoleacetic acid (5-HIAA). The data indicate that ethanol delays the onset of the rise of nocturnal pineal NAT activity.

  18. Histone acetyltransferase p300 promotes MKL1-mediated transactivation of catechol-O-methyltransferase gene.

    PubMed

    Liu, Zhipeng; Luo, Xuegang; Liu, Lei; Zhao, Wenwen; Guo, Shu; Guo, Yu; Wang, Nan; He, Hongpeng; Liao, Xinghua; Ma, Wenjian; Zhou, Hao; Zhang, Tongcun

    2013-12-01

    Previous studies have revealed that histone acetyltransferase p300 is recruited to the promoters of certain cardiac and smooth muscle specific genes to enhance the transactivation activity of myocardin, which is a master regulator in cardiovascular differentiation and development. Here, we found that the gene encoding catechol-O-methyltransferase (COMT), an important metabolic enzyme catalyzing the conversion of estrogen, is also a target gene of myocardin-related transcription factors (MRTFs). Megakaryoblastic leukemia 1 (MKL1, also named MRTF-A) and p300 could synergistically augment the expression of COMT gene, increase the metabolic rate of estrogen, and thus reduce the proliferation of MCF-7 breast cancer cells stimulated by estrogen. PMID:24096006

  19. Structure of homoserine O-acetyltransferase from Staphylococcus aureus: the first Gram-positive ortholog structure

    PubMed Central

    Thangavelu, Bharani; Pavlovsky, Alexander G.; Viola, Ronald

    2014-01-01

    Homoserine O-acetyltransferase (HTA) catalyzes the formation of l-O-acetyl-homoserine from l-homoserine through the transfer of an acetyl group from acetyl-CoA. This is the first committed step required for the biosynthesis of methionine in many fungi, Gram-positive bacteria and some Gram-negative bacteria. The structure of HTA from Staphylococcus aureus (SaHTA) has been determined to a resolution of 2.45 Å. The structure belongs to the α/β-hydrolase superfamily, consisting of two distinct domains: a core α/β-domain containing the catalytic site and a lid domain assembled into a helical bundle. The active site consists of a classical catalytic triad located at the end of a deep tunnel. Structure analysis revealed some important differences for SaHTA compared with the few known structures of HTA. PMID:25286936

  20. Structure of homoserine O-acetyltransferase from Staphylococcus aureus: the first Gram-positive ortholog structure.

    PubMed

    Thangavelu, Bharani; Pavlovsky, Alexander G; Viola, Ronald

    2014-10-01

    Homoserine O-acetyltransferase (HTA) catalyzes the formation of L-O-acetyl-homoserine from L-homoserine through the transfer of an acetyl group from acetyl-CoA. This is the first committed step required for the biosynthesis of methionine in many fungi, Gram-positive bacteria and some Gram-negative bacteria. The structure of HTA from Staphylococcus aureus (SaHTA) has been determined to a resolution of 2.45 Å. The structure belongs to the α/β-hydrolase superfamily, consisting of two distinct domains: a core α/β-domain containing the catalytic site and a lid domain assembled into a helical bundle. The active site consists of a classical catalytic triad located at the end of a deep tunnel. Structure analysis revealed some important differences for SaHTA compared with the few known structures of HTA.

  1. Metabolic Regulation of Histone Acetyltransferases by Endogenous Acyl-CoA Cofactors

    PubMed Central

    Guasch, Laura; Nicklaus, Marc C.; Meier, Jordan L.

    2015-01-01

    SUMMARY The finding that chromatin modifications are sensitive to changes in cellular cofactor levels potentially links altered tumor cell metabolism and gene expression. However, the specific enzymes and metabolites that connect these two processes remain obscure. Characterizing these metabolic-epigenetic axes is critical to understanding how metabolism supports signaling in cancer, and developing therapeutic strategies to disrupt this process. Here, we describe a chemical approach to define the metabolic regulation of lysine acetyltransferase (KAT) enzymes. Using a novel chemoproteomic probe, we identify a previously unreported interaction between fatty acyl-CoAs and KAT enzymes. Further analysis reveals that palmitoyl-CoA is a potent inhibitor of KAT activity and that fatty acyl-CoA precursors reduce cellular acetylation levels. These studies implicate fatty acyl-CoAs as endogenous regulators of histone acetylation, and suggest novel strategies for the investigation and metabolic modulation of epigenetic signaling. PMID:26190825

  2. Interferon-Induced Spermidine-Spermine Acetyltransferase and Polyamine Depletion Restrict Zika and Chikungunya Viruses.

    PubMed

    Mounce, Bryan C; Poirier, Enzo Z; Passoni, Gabriella; Simon-Loriere, Etienne; Cesaro, Teresa; Prot, Matthieu; Stapleford, Kenneth A; Moratorio, Gonzalo; Sakuntabhai, Anavaj; Levraud, Jean-Pierre; Vignuzzi, Marco

    2016-08-10

    Polyamines are small, positively charged molecules derived from ornithine and synthesized through an intricately regulated enzymatic pathway. Within cells, they are abundant and play several roles in diverse processes. We find that polyamines are required for the life cycle of the RNA viruses chikungunya virus (CHIKV) and Zika virus (ZIKV). Depletion of spermidine and spermine via type I interferon signaling-mediated induction of spermidine/spermine N1-acetyltransferase (SAT1), a key catabolic enzyme in the polyamine pathway, restricts CHIKV and ZIKV replication. Polyamine depletion restricts these viruses in vitro and in vivo, due to impairment of viral translation and RNA replication. The restriction is released by exogenous replenishment of polyamines, further supporting a role for these molecules in virus replication. Thus, SAT1 and, more broadly, polyamine depletion restrict viral replication and suggest promising avenues for antiviral therapies.

  3. A new arylalkylamine N-acetyltransferase in silkworm (Bombyx mori) affects integument pigmentation.

    PubMed

    Long, Yaohang; Li, Jiaorong; Zhao, Tianfu; Li, Guannan; Zhu, Yong

    2015-04-01

    Dopamine is a precursor for melanin synthesis. Arylalkylamine N-acetyltransferase (AANAT) is involved in the melatonin formation in insects because it could catalyze the transformation from dopamine to dopamine-N-acetyldopamine. In this study, we identified a new AANAT gene in the silkworm (Bombyx mori) and assessed its role in the silkworm. The cDNA of this gene encodes 233 amino acids that shares 57 % amino acid identity with the Bm-iAANAT protein. We thus refer to this gene as Bm-iAANAT2. To investigate the role of Bm-iAANAT2, we constructed a transgenic interference system using a 3xp3 promoter to suppress the expression of Bm-iAANAT2 in the silkworm. We observed that melanin deposition occurs in the head and integument in transgenic lines. To verify the melanism pattern, dopamine content and the enzyme activity of AANAT were determined by high-performance liquid chromatography (HPLC). We found that an increase in dopamine levels affects melanism patterns on the heads of transgenic B. mori. A reduction in the enzyme activity of AANAT leads to changes in dopamine levels. We analyzed the expression of the Bm-iAANAT2 genes by qPCR and found that the expression of Bm-iAANAT2 gene is significantly lower in transgenic lines. Our results lead us to conclude that Bm-iAANAT2 is a new arylalkylamine N-acetyltransferase gene in the silkworm and is involved in the metabolism of the dopamine to avoid the generation of melanin.

  4. Structural and Functional Role of Acetyltransferase hMOF K274 Autoacetylation.

    PubMed

    McCullough, Cheryl E; Song, Shufei; Shin, Michael H; Johnson, F Brad; Marmorstein, Ronen

    2016-08-26

    Many histone acetyltransferases undergo autoacetylation, either through chemical or enzymatic means, to potentiate enzymatic cognate substrate lysine acetylation, although the mode and molecular role of such autoacetylation is poorly understood. The MYST family of histone acetyltransferases is autoacetylated at an active site lysine residue to facilitate cognate substrate lysine binding and acetylation. Here, we report on a detailed molecular investigation of Lys-274 autoacetylation of the human MYST protein Males Absent on the First (hMOF). A mutational scan of hMOF Lys-274 reveals that all amino acid substitutions of this residue are able to bind cofactor but are significantly destabilized, both in vitro and in cells, and are catalytically inactive for cognate histone H4 peptide lysine acetylation. The x-ray crystal structure of a hMOF K274P mutant suggests that the reduced stability and catalytic activity stems from a disordering of the residue 274-harboring a α2-β7 loop. We also provide structural evidence that a C316S/E350Q mutant, which is defective for cognate substrate lysine acetylation; and biochemical evidence that a K268M mutant, which is defective for Lys-274 chemical acetylation in the context of a K274-peptide, can still undergo quantitative K274 autoacetylation. Together, these studies point to the critical and specific role of hMOF Lys-274 autoacetylation in hMOF stability and cognate substrate acetylation and argues that binding of Ac-CoA to hMOF likely drives Lys-274 autoacetylation for subsequent cognate substrate acetylation. PMID:27382063

  5. Regulatory region in choline acetyltransferase gene directs developmental and tissue-specific expression in transgenic mice.

    PubMed Central

    Lönnerberg, P; Lendahl, U; Funakoshi, H; Arhlund-Richter, L; Persson, H; Ibáñez, C F

    1995-01-01

    Acetylcholine, one of the main neurotransmitters in the nervous system, is synthesized by the enzyme choline acetyltransferase (ChAT; acetyl-CoA:choline O-acetyltransferase, EC 2.3.1.6). The molecular mechanisms controlling the establishment, maintenance, and plasticity of the cholinergic phenotype in vivo are largely unknown. A previous report showed that a 3800-bp, but not a 1450-bp, 5' flanking segment from the rat ChAT gene promoter directed cell type-specific expression of a reporter gene in cholinergic cells in vitro. Now we have characterized a distal regulatory region of the ChAT gene that confers cholinergic specificity on a heterologous downstream promoter in a cholinergic cell line and in transgenic mice. A 2342-bp segment from the 5' flanking region of the ChAT gene behaved as an enhancer in cholinergic cells but as a repressor in noncholinergic cells in an orientation-independent manner. Combined with a heterologous basal promoter, this fragment targeted transgene expression to several cholinergic regions of the central nervous system of transgenic mice, including basal forebrain, cortex, pons, and spinal cord. In eight independent transgenic lines, the pattern of transgene expression paralleled qualitatively and quantitatively that displayed by endogenous ChAT mRNA in various regions of the rat central nervous system. In the lumbar enlargement of the spinal cord, 85-90% of the transgene expression was targeted to the ventral part of the cord, where cholinergic alpha-motor neurons are located. Transgene expression in the spinal cord was developmentally regulated and responded to nerve injury in a similar way as the endogenous ChAT gene, indicating that the 2342-bp regulatory sequence contains elements controlling the plasticity of the cholinergic phenotype in developing and injured neurons. Images Fig. 1 Fig. 2 PMID:7732028

  6. Relation of pontine choline acetyltransferase immunoreactive neurons with cells which increase discharge during REM sleep.

    PubMed

    Shiromani, P J; Armstrong, D M; Bruce, G; Hersh, L B; Groves, P M; Gillin, J C

    1987-03-01

    The purpose of this study was to determine whether neurons in the medial pontine reticular formation with high discharge rates during REM sleep could be localized in regions of the brainstem having neurons displaying choline acetyltransferase immunoreactivity. Six cats were implanted with sleep recording electrodes and microwires to record extracellular potentials of neurons in the pontine reticular formation. Single-units with a S:N ratio greater than 2:1 were recorded for at least two REM sleep cycles. A total of 49 units was recorded from the pontine reticular formation at medial-lateral planes ranging from 0.8 to 3.7 mm. The greatest proportion of the units (28.6%) showed highest discharge during active waking and phasic REM sleep compared to quiet waking, non-REM sleep, transition into REM sleep or quiet REM sleep periods. A percentage (20.4%) of the cells had high discharge associated with phasic REM sleep periods while 8.2% of the cells showed a progressive increase in discharge from waking to REM sleep. Subsequent examination of the distribution of choline acetyltransferase immunoreactive cells in the PRF revealed that cells showing high discharge during REM sleep were not localized near presumed cholinergic neurons. Indeed, we did not find any ChAT immunoreactive somata in the medial PRF, an area which has traditionally been implicated in the generation of REM sleep. These results suggest that while increased discharge of PRF cells may be instrumental to REM sleep generation, these cells are not cholinergic.

  7. Top-Hat Representation of Turbulence Statistics in Cloud-Topped Boundary Layers: A Large Eddy Simulation Study.

    NASA Astrophysics Data System (ADS)

    Wang, Shouping; Stevens, Bjorn

    2000-02-01

    Large eddy simulation is used to study top-hat parameterizations of second- and third-order scalar statistics in cumulus and stratocumulus cloud-topped boundary layers (CTBLs). Although the top-hat parameterizations based on commonly used conditional sampling methods are a useful approach to modeling the vertical fluxes in the simulated CTBLs, they fail to realistically represent the scalar variances. The reason is that the common sampling methods are based at least in part on the sign of vertical velocity, but not on the sign of the scalars whose variances are represented and that scalars and velocity are not perfectly correlated. Furthermore, the self-correlation nature for a variance means that all the fluctuations contribute to its value, while the top-hat models completely ignore the deviations from the top-hat means and thus considerably degrade the representation of the variance. For the fluxes, however, only the coherent convective elements make the most contribution. Analysis of analytic models and `toy' time series indicates in a more generic setting that the effect of poor correlations between the signal upon which the sampling is based and the signal whose variance is to be represented tends to degrade the ability of top-hat parameterizations to capture the variance. The analysis of toy time series also indicates that variability among individual events within a composite degrades the top-hat representation of the variance more than variability within events. For the vertical velocity-scalar-related third-order moments, the top-hat model gives reasonable estimates for the cumulus CTBL but not for the stratocumulus CTBL. These differences are explained by structural differences (tied to circulation differences in the two CTBLs) in their respective joint probability density functions of vertical velocity and various scalars.

  8. Orbital Phase Variations of the Eccentric Giant Planet HAT-P-2b

    NASA Astrophysics Data System (ADS)

    Lewis, Nikole K.; Knutson, Heather A.; Showman, Adam P.; Cowan, Nicolas B.; Laughlin, Gregory; Burrows, Adam; Deming, Drake; Crepp, Justin R.; Mighell, Kenneth J.; Agol, Eric; Bakos, Gáspár Á.; Charbonneau, David; Désert, Jean-Michel; Fischer, Debra A.; Fortney, Jonathan J.; Hartman, Joel D.; Hinkley, Sasha; Howard, Andrew W.; Johnson, John Asher; Kao, Melodie; Langton, Jonathan; Marcy, Geoffrey W.

    2013-04-01

    We present the first secondary eclipse and phase curve observations for the highly eccentric hot Jupiter HAT-P-2b in the 3.6, 4.5, 5.8, and 8.0 μm bands of the Spitzer Space Telescope. The 3.6 and 4.5 μm data sets span an entire orbital period of HAT-P-2b (P = 5.6334729 d), making them the longest continuous phase curve observations obtained to date and the first full-orbit observations of a planet with an eccentricity exceeding 0.2. We present an improved non-parametric method for removing the intrapixel sensitivity variations in Spitzer data at 3.6 and 4.5 μm that robustly maps position-dependent flux variations. We find that the peak in planetary flux occurs at 4.39 ± 0.28, 5.84 ± 0.39, and 4.68 ± 0.37 hr after periapse passage with corresponding maxima in the planet/star flux ratio of 0.1138% ± 0.0089%, 0.1162% ± 0.0080%, and 0.1888% ± 0.0072% in the 3.6, 4.5, and 8.0 μm bands, respectively. Our measured secondary eclipse depths of 0.0996% ± 0.0072%, 0.1031% ± 0.0061%, 0.071%^{+0.029%}_{-0.013%}, and 0.1392% ± 0.0095% in the 3.6, 4.5, 5.8, and 8.0 μm bands, respectively, indicate that the planet cools significantly from its peak temperature before we measure the dayside flux during secondary eclipse. We compare our measured secondary eclipse depths to the predictions from a one-dimensional radiative transfer model, which suggests the possible presence of a transient day side inversion in HAT-P-2b's atmosphere near periapse. We also derive improved estimates for the system parameters, including its mass, radius, and orbital ephemeris. Our simultaneous fit to the transit, secondary eclipse, and radial velocity data allows us to determine the eccentricity (e = 0.50910 ± 0.00048) and argument of periapse (ω = 188.°09 ± 0.°39) of HAT-P-2b's orbit with a greater precision than has been achieved for any other eccentric extrasolar planet. We also find evidence for a long-term linear trend in the radial velocity data. This trend suggests the presence

  9. ORBITAL PHASE VARIATIONS OF THE ECCENTRIC GIANT PLANET HAT-P-2b

    SciTech Connect

    Lewis, Nikole K.; Showman, Adam P.; Knutson, Heather A.; Desert, Jean-Michel; Kao, Melodie; Cowan, Nicolas B.; Laughlin, Gregory; Fortney, Jonathan J.; Burrows, Adam; Bakos, Gaspar A.; Hartman, Joel D.; Deming, Drake; Crepp, Justin R.; Mighell, Kenneth J.; Agol, Eric; Charbonneau, David; Fischer, Debra A.; Hinkley, Sasha; Johnson, John Asher; Howard, Andrew W.; and others

    2013-04-01

    We present the first secondary eclipse and phase curve observations for the highly eccentric hot Jupiter HAT-P-2b in the 3.6, 4.5, 5.8, and 8.0 {mu}m bands of the Spitzer Space Telescope. The 3.6 and 4.5 {mu}m data sets span an entire orbital period of HAT-P-2b (P = 5.6334729 d), making them the longest continuous phase curve observations obtained to date and the first full-orbit observations of a planet with an eccentricity exceeding 0.2. We present an improved non-parametric method for removing the intrapixel sensitivity variations in Spitzer data at 3.6 and 4.5 {mu}m that robustly maps position-dependent flux variations. We find that the peak in planetary flux occurs at 4.39 {+-} 0.28, 5.84 {+-} 0.39, and 4.68 {+-} 0.37 hr after periapse passage with corresponding maxima in the planet/star flux ratio of 0.1138% {+-} 0.0089%, 0.1162% {+-} 0.0080%, and 0.1888% {+-} 0.0072% in the 3.6, 4.5, and 8.0 {mu}m bands, respectively. Our measured secondary eclipse depths of 0.0996% {+-} 0.0072%, 0.1031% {+-} 0.0061%, 0.071%{sub -0.013%}{sup +0.029,} and 0.1392% {+-} 0.0095% in the 3.6, 4.5, 5.8, and 8.0 {mu}m bands, respectively, indicate that the planet cools significantly from its peak temperature before we measure the dayside flux during secondary eclipse. We compare our measured secondary eclipse depths to the predictions from a one-dimensional radiative transfer model, which suggests the possible presence of a transient day side inversion in HAT-P-2b's atmosphere near periapse. We also derive improved estimates for the system parameters, including its mass, radius, and orbital ephemeris. Our simultaneous fit to the transit, secondary eclipse, and radial velocity data allows us to determine the eccentricity (e = 0.50910 {+-} 0.00048) and argument of periapse ({omega} = 188. Degree-Sign 09 {+-} 0. Degree-Sign 39) of HAT-P-2b's orbit with a greater precision than has been achieved for any other eccentric extrasolar planet. We also find evidence for a long-term linear

  10. Promotion of Cell Viability and Histone Gene Expression by the Acetyltransferase Gcn5 and the Protein Phosphatase PP2A in Saccharomyces cerevisiae.

    PubMed

    Petty, Emily L; Lafon, Anne; Tomlinson, Shannon L; Mendelsohn, Bryce A; Pillus, Lorraine

    2016-08-01

    Histone modifications direct chromatin-templated events in the genome and regulate access to DNA sequence information. There are multiple types of modifications, and a common feature is their dynamic nature. An essential step for understanding their regulation, therefore, lies in characterizing the enzymes responsible for adding and removing histone modifications. Starting with a dosage-suppressor screen in Saccharomyces cerevisiae, we have discovered a functional interaction between the acetyltransferase Gcn5 and the protein phosphatase 2A (PP2A) complex, two factors that regulate post-translational modifications. We find that RTS1, one of two genes encoding PP2A regulatory subunits, is a robust and specific high-copy suppressor of temperature sensitivity of gcn5∆ and a subset of other gcn5∆ phenotypes. Conversely, loss of both PP2A(Rts1) and Gcn5 function in the SAGA and SLIK/SALSA complexes is lethal. RTS1 does not restore global transcriptional defects in gcn5∆; however, histone gene expression is restored, suggesting that the mechanism of RTS1 rescue includes restoration of specific cell cycle transcripts. Pointing to new mechanisms of acetylation-phosphorylation cross-talk, RTS1 high-copy rescue of gcn5∆ growth requires two residues of H2B that are phosphorylated in human cells. These data highlight the potential significance of dynamic phosphorylation and dephosphorylation of these deeply conserved histone residues for cell viability. PMID:27317677

  11. HATS-18b: An Extreme Short-period Massive Transiting Planet Spinning Up Its Star

    NASA Astrophysics Data System (ADS)

    Penev, K.; Hartman, J. D.; Bakos, G. Á.; Ciceri, S.; Brahm, R.; Bayliss, D.; Bento, J.; Jordán, A.; Csubry, Z.; Bhatti, W.; de Val-Borro, M.; Espinoza, N.; Zhou, G.; Mancini, L.; Rabus, M.; Suc, V.; Henning, T.; Schmidt, B.; Noyes, R. W.; Lázár, J.; Papp, I.; Sári, P.

    2016-11-01

    We report the discovery by the HATSouth network of HATS-18b: a 1.980+/- 0.077 {M}{{J}}, {1.337}-0.049+0.102 {R}{{J}} planet in a 0.8378 day orbit, around a solar analog star (mass 1.037+/- 0.047 {M}ȯ and radius {1.020}-0.031+0.057 {R}ȯ ) with V=14.067+/- 0.040 mag. The high planet mass, combined with its short orbital period, implies strong tidal coupling between the planetary orbit and the star. In fact, given its inferred age, HATS-18 shows evidence of significant tidal spin up, which together with WASP-19 (a very similar system) allows us to constrain the tidal quality factor for Sun-like stars to be in the range of 6.5≲ {{log}}10({Q}* /{k}2)≲ 7 even after allowing for extremely pessimistic model uncertainties. In addition, the HATS-18 system is among the best systems (and often the best system) for testing a multitude of star–planet interactions, be they gravitational, magnetic, or radiative, as well as planet formation and migration theories. The HATSouth network is operated by a collaboration consisting of Princeton University (PU), the Max Planck Institute für Astronomie (MPIA), the Australian National University (ANU), and the Pontificia Universidad Católica de Chile (PUC). The station at Las Campanas Observatory (LCO) of the Carnegie Institute is operated by PU in conjunction with PUC, the station at the High Energy Spectroscopic Survey (H.E.S.S.) site is operated in conjunction with MPIA, and the station at Siding Spring Observatory (SSO) is operated jointly with ANU. This paper includes data gathered with the MPG 2.2 m telescope at the ESO Observatory in La Silla. This paper uses observations obtained with facilities of the Las Cumbres Observatory Global Telescope.

  12. HATS-2b: A transiting extrasolar planet orbiting a K-type star showing starspot activity

    NASA Astrophysics Data System (ADS)

    Mohler-Fischer, M.; Mancini, L.; Hartman, J. D.; Bakos, G. Á.; Penev, K.; Bayliss, D.; Jordán, A.; Csubry, Z.; Zhou, G.; Rabus, M.; Nikolov, N.; Brahm, R.; Espinoza, N.; Buchhave, L. A.; Béky, B.; Suc, V.; Csák, B.; Henning, T.; Wright, D. J.; Tinney, C. G.; Addison, B. C.; Schmidt, B.; Noyes, R. W.; Papp, I.; Lázár, J.; Sári, P.; Conroy, P.

    2013-10-01

    We report the discovery of HATS-2b, the second transiting extrasolar planet detected by the HATSouth survey. HATS-2b is moving on a circular orbit around a V = 13.6 mag, K-type dwarf star (GSC 6665-00236), at a separation of 0.0230 ± 0.0003 AU and with a period of 1.3541 days. The planetary parameters have been robustly determined using a simultaneous fit of the HATSouth, MPG/ESO 2.2 m/GROND, Faulkes Telescope South/Spectral transit photometry, and MPG/ESO 2.2 m/FEROS, Euler 1.2 m/CORALIE, AAT 3.9 m/CYCLOPS radial-velocity measurements. HATS-2b has a mass of 1.37 ± 0.16 MJ, a radius of 1.14 ± 0.03 RJ, and an equilibrium temperature of 1567 ± 30 K. The host star has a mass of 0.88 ± 0.04 M⊙ and a radius of 0.89 ± 0.02 R⊙, and it shows starspot activity. We characterized the stellar activity by analyzing two photometric follow-up transit light curves taken with the GROND instrument, both obtained simultaneously in four optical bands (covering the wavelength range of 3860-9520 Å). The two light curves contain anomalies compatible with starspots on the photosphere of the host star along the same transit chord. Tables of the individual photometric measurements are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/558/A55

  13. On Application of the 3-Cornered Hat Technique to Radio Source Position Catalogs

    NASA Astrophysics Data System (ADS)

    Malkin, Z.

    2013-08-01

    So called ``3-cornered hat'' method (3CH) was originally developed for estimation of the stability of frequency standards (Gray1974). It was then applied for investigation of the noise level of various data, in particular, astronomical and geodetic time series and radio source position catalogs. However, despite this method is widely used, its application is not straightforward because it requires a reliable estimate of the correlations between series under investigation. Neglecting correlations often produces unacceptable results, like negative variances. In this work, we investigate a new possibility to estimate correlations between radio source position catalogs (RSC) obtained from VLBI observations.

  14. Multi-jet Cross Sections at NLO with BlackHat and Sherpa

    SciTech Connect

    Berger, C.F.; Bern, Z.; Dixon, L.J.; Cordero, F.Febres; Forde, D.; Gleisberg, T.; Ita, H.; Kosower, D.A.; Maitre, D.

    2009-05-20

    In this talk, we report on a recent next-to-leading order QCD calculation of the production of a W boson in association with three jets at hadron colliders. The computation is performed by combining two programs, BlackHat for the computation of the virtual one-loop matrix elements and Sherpa for the real emission part. The addition of NLO corrections greatly reduces the factorization and renormalization scale dependence of the theory prediction for this process. This result demonstrates the applicability of unitarity-based methods for hadron collider physics.

  15. Characterization of the serine acetyltransferase gene family of Vitis vinifera uncovers differences in regulation of OAS synthesis in woody plants

    PubMed Central

    Tavares, Sílvia; Wirtz, Markus; Beier, Marcel P.; Bogs, Jochen; Hell, Rüdiger; Amâncio, Sara

    2015-01-01

    In higher plants cysteine biosynthesis is catalyzed by O-acetylserine(thiol)lyase (OASTL) and represents the last step of the assimilatory sulfate reduction pathway. It is mainly regulated by provision of O-acetylserine (OAS), the nitrogen/carbon containing backbone for fixation of reduced sulfur. OAS is synthesized by Serine acetyltransferase (SERAT), which reversibly interacts with OASTL in the cysteine synthase complex (CSC). In this study we identify and characterize the SERAT gene family of the crop plant Vitis vinifera. The identified four members of the VvSERAT protein family are assigned to three distinct groups upon their sequence similarities to Arabidopsis SERATs. Expression of fluorescently labeled VvSERAT proteins uncover that the sub-cellular localization of VvSERAT1;1 and VvSERAT3;1 is the cytosol and that VvSERAT2;1 and VvSERAT2;2 localize in addition in plastids and mitochondria, respectively. The purified VvSERATs of group 1 and 2 have higher enzymatic activity than VvSERAT3;1, which display a characteristic C-terminal extension also present in AtSERAT3;1. VvSERAT1;1 and VvSERAT2;2 are evidenced to form the CSC. CSC formation activates VvSERAT2;2, by releasing CSC-associated VvSERAT2;2 from cysteine inhibition. Thus, subcellular distribution of SERAT isoforms and CSC formation in cytosol and mitochondria is conserved between Arabidopsis and grapevine. Surprisingly, VvSERAT2;1 lack the canonical C-terminal tail of plant SERATs, does not form the CSC and is almost insensitive to cysteine inhibition (IC50 = 1.9 mM cysteine). Upon sulfate depletion VvSERAT2;1 is strongly induced at the transcriptional level, while transcription of other VvSERATs is almost unaffected in sulfate deprived grapevine cell suspension cultures. Application of abiotic stresses to soil grown grapevine plants revealed isoform-specific induction of VvSERAT2;1 in leaves upon drought, whereas high light- or temperature- stress hardly trigger VvSERAT2;1 transcription. PMID:25741355

  16. Lysine Acetyltransferase GCN5b Interacts with AP2 Factors and Is Required for Toxoplasma gondii Proliferation

    PubMed Central

    Wang, Jiachen; Dixon, Stacy E.; Ting, Li-Min; Liu, Ting-Kai; Jeffers, Victoria; Croken, Matthew M.; Calloway, Myrasol; Cannella, Dominique; Ali Hakimi, Mohamed; Kim, Kami; Sullivan, William J.

    2014-01-01

    Histone acetylation has been linked to developmental changes in gene expression and is a validated drug target of apicomplexan parasites, but little is known about the roles of individual histone modifying enzymes and how they are recruited to target genes. The protozoan parasite Toxoplasma gondii (phylum Apicomplexa) is unusual among invertebrates in possessing two GCN5-family lysine acetyltransferases (KATs). While GCN5a is required for gene expression in response to alkaline stress, this KAT is dispensable for parasite proliferation in normal culture conditions. In contrast, GCN5b cannot be disrupted, suggesting it is essential for Toxoplasma viability. To further explore the function of GCN5b, we generated clonal parasites expressing an inducible HA-tagged dominant-negative form of GCN5b containing a point mutation that ablates enzymatic activity (E703G). Stabilization of this dominant-negative GCN5b was mediated through ligand-binding to a destabilization domain (dd) fused to the protein. Induced accumulation of the ddHAGCN5b(E703G) protein led to a rapid arrest in parasite replication. Growth arrest was accompanied by a decrease in histone H3 acetylation at specific lysine residues as well as reduced expression of GCN5b target genes in GCN5b(E703G) parasites, which were identified using chromatin immunoprecipitation coupled with microarray hybridization (ChIP-chip). Proteomics studies revealed that GCN5b interacts with AP2-domain proteins, apicomplexan plant-like transcription factors, as well as a “core complex” that includes the co-activator ADA2-A, TFIID subunits, LEO1 polymerase-associated factor (Paf1) subunit, and RRM proteins. The dominant-negative phenotype of ddHAGCN5b(E703G) parasites, considered with the proteomics and ChIP-chip data, indicate that GCN5b plays a central role in transcriptional and chromatin remodeling complexes. We conclude that GCN5b has a non-redundant and indispensable role in regulating gene expression required during the

  17. Recognition of Unmodified Histone H3 by the First PHD Finger of Bromodomain-PHD Finger Protein 2 Provides Insights into the Regulation of Histone Acetyltransferases Monocytic Leukemic Zinc-finger Protein (MOZ) and MOZ-related factor (MORF)*

    PubMed Central

    Qin, Su; Jin, Lei; Zhang, Jiahai; Liu, Lei; Ji, Peng; Wu, Mian; Wu, Jihui; Shi, Yunyu

    2011-01-01

    MOZ (monocytic leukemic zinc-finger protein) and MORF (MOZ-related factor) are histone acetyltransferases important for HOX gene expression as well as embryo and postnatal development. They form complexes with other regulatory subunits through the scaffold proteins BRPF1/2/3 (bromodomain-PHD (plant homeodomain) finger proteins 1, 2, or 3). BRPF proteins have multiple domains, including two PHD fingers, for potential interactions with histones. Here we show that the first PHD finger of BRPF2 specifically recognizes the N-terminal tail of unmodified histone H3 (unH3) and report the solution structures of this PHD finger both free and in complex with the unH3 peptide. Structural analysis revealed that the unH3 peptide forms a third antiparallel β-strand that pairs with the PHD1 two-stranded antiparallel β-sheet. The binding specificity was determined primarily through the recognition of arginine 2 and lysine 4 of the unH3 by conserved aspartic acids of PHD1 and of threonine 6 of the unH3 by a conserved asparagine. Isothermal titration calorimetry and NMR assays showed that post-translational modifications such as H3R2me2as, H3T3ph, H3K4me, H3K4ac, and H3T6ph antagonized the interaction between histone H3 and PHD1. Furthermore, histone binding by PHD1 was important for BRPF2 to localize to the HOXA9 locus in vivo. PHD1 is highly conserved in yeast NuA3 and other histone acetyltransferase complexes, so the results reported here also shed light on the function and regulation of these complexes. PMID:21880731

  18. Structural Performance of a Compressively Loaded Foam-Core Hat-Stiffened Textile Composite Panel

    NASA Technical Reports Server (NTRS)

    Ambur, Damodar R.; Dexter, Benson H.

    1996-01-01

    A structurally efficient hat-stiffened panel concept that utilizes a structural foam as a stiffener core material has been designed and developed for aircraft primary structural applications. This stiffener concept is fabricated from textile composite material forms with a resin transfer molding process. This foam-filled hat-stiffener concept is structurally more efficient than most other prismatically stiffened panel configurations in a load range that is typical for both fuselage and wing structures. The panel design is based on woven/stitched and braided graphite-fiber textile preforms, an epoxy resin system, and Rohacell foam core. The structural response of this panel design was evaluated for its buckling and postbuckling behavior with and without low-speed impact damage. The results from single-stiffener and multi-stiffener specimen tests suggest that this structural concept responds to loading as anticipated and has excellent damage tolerance characteristics compared to a similar panel design made from preimpregnated graphite-epoxy tape material.

  19. Analysis of RNA-Seq Data Using TopHat and Cufflinks.

    PubMed

    Ghosh, Sreya; Chan, Chon-Kit Kenneth

    2016-01-01

    The recent advances in high throughput RNA sequencing (RNA-Seq) have generated huge amounts of data in a very short span of time for a single sample. These data have required the parallel advancement of computing tools to organize and interpret them meaningfully in terms of biological implications, at the same time using minimum computing resources to reduce computation costs. Here we describe the method of analyzing RNA-seq data using the set of open source software programs of the Tuxedo suite: TopHat and Cufflinks. TopHat is designed to align RNA-seq reads to a reference genome, while Cufflinks assembles these mapped reads into possible transcripts and then generates a final transcriptome assembly. Cufflinks also includes Cuffdiff, which accepts the reads assembled from two or more biological conditions and analyzes their differential expression of genes and transcripts, thus aiding in the investigation of their transcriptional and post transcriptional regulation under different conditions. We also describe the use of an accessory tool called CummeRbund, which processes the output files of Cuffdiff and gives an output of publication quality plots and figures of the user's choice. We demonstrate the effectiveness of the Tuxedo suite by analyzing RNA-Seq datasets of Arabidopsis thaliana root subjected to two different conditions. PMID:26519415

  20. Analytical and experimental study of structurally efficient composite hat-stiffened panels loaded in axial compression

    NASA Technical Reports Server (NTRS)

    Williams, J. G.; Mikulas, M. M., Jr.

    1975-01-01

    Structural efficiency studies were made to determine the weight-saving potential of graphite/epoxy composite structures for compression panel applications. Minimum-weight hat-stiffened and open-corrugation configurations were synthesized using a nonlinear mathematical programing technique. Selected configurations were built and tested to study local and Euler buckling characteristics. Test results for 23 panels critical in local buckling and six panels critical in Euler buckling are compared with analytical results obtained using the BUCLASP-2 branched plate buckling program. A weight efficiency comparison is made between composite and aluminum compression panels using metal test data generated by the NACA. Theoretical studies indicate that potential weight savings of up to 50% are possible for composite hat-stiffened panels when compared with similar aluminum designs. Weight savings of 32% to 42% were experimentally achieved. Experience to date suggests that most of the theoretical weight-saving potential is available if design deficiencies are eliminated and strict fabrication control is exercised.

  1. The G-HAT Search for Advanced Extraterrestrial Civilizations: The Reddest Extended WISE Sources

    NASA Astrophysics Data System (ADS)

    Maldonado, Jessica; Povich, Matthew S.; Wright, Jason; Griffith, Roger; Sigurdsson, Steinn; Mullan, Brendan L.

    2015-01-01

    Freeman Dyson (1960) theorized how to identify possible signatures of advanced extra-terrestrial civilizations by their waste heat, an inevitable byproduct of a civilization using a significant fraction of the luminosity from their host star. If a civilizations could tap the starlight throughout their host galaxy their waste heat would be easily detectable by recent infrared surveys. The Glimpsing Heat from Alien Technologies (G-HAT) pilot project aims to place limits on the existence of extraterrestrial civilizations at pan-galactic scales. We present results from the G-HAT cleaned catalog of 563 extremely red, extended high Galactic latitude (|b| ≥ 10) sources from the WISE All-Sky Catalog. Our catalog includes sources new to the scientific literature along with well-studied objects (e.g. starburst galaxies, AGN, and planetary nebulae) that exemplify extreme WISE colors. Objects of particular interest include a supergiant Be star (48 Librae) surrounded by a resolved, mid-infrared nebula, possibly indicating dust in the stellar wind ejecta, and a curious cluster of seven extremely red WISE sources (associated with IRAS 04287+6444) that have no optical counterparts.

  2. HATS-3b: AN INFLATED HOT JUPITER TRANSITING AN F-TYPE STAR

    SciTech Connect

    Bayliss, D.; Zhou, G.; Schmidt, B.; Penev, K.; Bakos, G. Á.; Hartman, J. D.; Csubry, Z.; Jordán, A.; Suc, V.; Rabus, M.; Brahm, R.; Espinoza, N.; Mancini, L.; Mohler-Fischer, M.; Henning, T.; Nikolov, N.; Csák, B.; Béky, B.; Noyes, R. W.; Buchhave, L.; and others

    2013-11-01

    We report the discovery by the HATSouth survey of HATS-3b, a transiting extrasolar planet orbiting a V = 12.4 F dwarf star. HATS-3b has a period of P = 3.5479 days, mass of M{sub p} = 1.07 M {sub J}, and radius of R{sub p} = 1.38 R {sub J}. Given the radius of the planet, the brightness of the host star, and the stellar rotational velocity (vsin i = 9.0 km s{sup –1}), this system will make an interesting target for future observations to measure the Rossiter-McLaughlin effect and determine its spin-orbit alignment. We detail the low-/medium-resolution reconnaissance spectroscopy that we are now using to deal with large numbers of transiting planet candidates produced by the HATSouth survey. We show that this important step in discovering planets produces log g and T {sub eff} parameters at a precision suitable for efficient candidate vetting, as well as efficiently identifying stellar mass eclipsing binaries with radial velocity semi-amplitudes as low as 1 km s{sup –1}.

  3. THE OBLIQUE ORBIT OF THE SUPER-NEPTUNE HAT-P-11b

    SciTech Connect

    Winn, Joshua N.; Albrecht, Simon; Johnson, John Asher; Howard, Andrew W.; Marcy, Geoffrey W.; Isaacson, Howard; Shporer, Avi; Bakos, Gaspar A.; Hartman, Joel D.

    2010-11-10

    We find the orbit of the Neptune-sized exoplanet HAT-P-11b to be highly inclined relative to the equatorial plane of its host star. This conclusion is based on spectroscopic observations of two transits, which allowed the Rossiter-McLaughlin effect to be detected with an amplitude of 1.5 m s{sup -1}. The sky-projected obliquity is 103{sup +26} {sub -10} deg. This is the smallest exoplanet for which spin-orbit alignment has been measured. The result favors a migration scenario involving few-body interactions followed by tidal dissipation. This finding also conforms with the pattern that the systems with the weakest tidal interactions have the widest spread in obliquities. We predict that the high obliquity of HAT-P-11 will be manifest in transit light curves from the Kepler spacecraft: starspot-crossing anomalies will recur at most once per stellar rotation period, rather than once per orbital period as they would for a well-aligned system.

  4. FURTHER CONSTRAINTS ON THE OPTICAL TRANSMISSION SPECTRUM OF HAT-P-1b

    SciTech Connect

    Montalto, M.; Santos, N. C.; Martins, J. H. C.; Figueira, P.; Alonso, R.; Iro, N.; Desidera, S.

    2015-09-20

    We report on novel observations of HAT-P-1 aimed at constraining the optical transmission spectrum of the atmosphere of its transiting hot-Jupiter exoplanet. Ground-based differential spectrophotometry was performed over two transit windows using the DOLORES spectrograph at the Telescopio Nazionale Galileo. Our measurements imply an average planet to star radius ratio equal to R{sub p}/R{sub *} = (0.1159 ± 0.0005). This result is consistent with the value obtained from recent near-infrared measurements of this object, but differs from previously reported optical measurements, being lower by around 4.4 exoplanet scale heights. Analyzing the data over five different spectral bins of ∼600 Å wide, we observed a single peaked spectrum (3.7 σ level) with a blue cutoff corresponding to the blue edge of the broad absorption wing of sodium and an increased absorption in the region in-between 6180 and 7400 Å. We also infer that the width of the broad absorption wings due to alkali metals is likely narrower than the one implied by solar abundance clear atmospheric models. We interpret the result as evidence that HAT-P-1b has a partially clear atmosphere at optical wavelengths with a more modest contribution from an optical absorber than previously reported.

  5. Transmission Spectroscopy of HAT-P-32Ab with GTC/OSIRIS

    NASA Astrophysics Data System (ADS)

    Nortmann, Lisa; Pallé, Enric; Murgas, Felipe; Dreizler, Stefan; Iro, Nicolas; Cabrera-Lavers, Antonio

    2015-12-01

    I will present one of the latest results of our GTC exoplanet transit spectroscopy survey. Over the last years our group has obtained ground-based optical (538 nm - 918 nm) spectrophotometric transit observations for several hot Jupiters including HAT-P-32Ab using the OSIRIS (Optical System for Imaging and low Resolution Integrated Spectroscopy) instrument at the Spanish 10-meter telescope GTC.I will discuss the source, nature and proper correction of instrument specific systematic noise we found to affect our data. After its correction, we were able to yield high quality results with a precision between 482 and 1703 ppm depending on the wavelength channel. We measure a flat optical transmission spectrum for HAT-P-32Ab, consistent with the results of Gibson et al. (2013, MNRAS, 436, 2974) obtained with GMOS at Gemini-North. This independent reproduction of consistent results re-establishes faith in the reliability of ground-based transmission spectroscopy and emphasizes the high potential of OSIRIS at the GTC as a tool to complement current and future space-based observations.

  6. A Bayesian analysis of HAT-P-7b using the EXONEST algorithm

    SciTech Connect

    Placek, Ben; Knuth, Kevin H.

    2015-01-13

    The study of exoplanets (planets orbiting other stars) is revolutionizing the way we view our universe. High-precision photometric data provided by the Kepler Space Telescope (Kepler) enables not only the detection of such planets, but also their characterization. This presents a unique opportunity to apply Bayesian methods to better characterize the multitude of previously confirmed exoplanets. This paper focuses on applying the EXONEST algorithm to characterize the transiting short-period-hot-Jupiter, HAT-P-7b (also referred to as Kepler-2b). EXONEST evaluates a suite of exoplanet photometric models by applying Bayesian Model Selection, which is implemented with the MultiNest algorithm. These models take into account planetary effects, such as reflected light and thermal emissions, as well as the effect of the planetary motion on the host star, such as Doppler beaming, or boosting, of light from the reflex motion of the host star, and photometric variations due to the planet-induced ellipsoidal shape of the host star. By calculating model evidences, one can determine which model best describes the observed data, thus identifying which effects dominate the planetary system. Presented are parameter estimates and model evidences for HAT-P-7b.

  7. The nature of the Napoleon's Hat nebula of SN 1987A

    NASA Astrophysics Data System (ADS)

    Wang, L.; Dyson, J. E.; Kahn, F. D.

    1993-03-01

    The interstellar and circumstellar environment of SN 1987A is modeled. The geometries of Napoleon's Hat nebula and the dark bay suggest that there is relative motion between the SN progenitor and the surrounding ISM. Most of the dark bay can be identified with the bubble produced by the fast blue supergiant (BSG) wind before the red supergiant (RSG) stage. The relative motion between the star and the ISM is the primary reason for the star being at the edge of this bubble. After the first BSG stage, the star evolves to the RSG stage; the wind velocity is now typically 10 km/s and the mass loss rate is around 10 exp -5 solar mass/yr. The star eventually breaks through the bubble produced in the early BSG stage and starts to interact directly with the ISM outside, thus producing Napoleon's Hat. The success of this model is convincing proof of the BSG-RSG-BSG evolutionary model for the SN 1987A progenitors, and shows that is has moved from the site where it was formed.

  8. Free radical scavenger properties of α-mangostin: thermodynamics and kinetics of HAT and RAF mechanisms.

    PubMed

    Martínez, Ana; Galano, Annia; Vargas, Rubicelia

    2011-11-01

    Mangosteen is a tropical fruit that presents beneficial effects on human health since it is rich in anthocyanins and xanthones, which are considered bioactive compounds that have been described as good free radical scavengers. One of its most active compounds is α-mangostin. In this report, a theoretical study on the free radical scavenger capacity of α-mangostin and its monoanion is analyzed using the density functional theory approximation. Two well-known reaction mechanisms are investigated: the hydrogen atom transfer (HAT) and the radical adduct formation (RAF). Two other mechanisms are also considered: sequential electron proton Transfer (SEPT) and proton coupled electron transfer (PCET). According to thermodynamics and kinetics, α-mangostin and its deprotonated form are good free radical scavenger through the HAT mechanism, with the anionic (deprotonated) form being more reactive than the neutral one. Their capacity to scavenge OOH free radical is similar to that of carotenes, higher than that of allicin, much higher than that of melatonin and N-acetylcysteine amide, and about 15 times lower than that of 2-propenesulfenic acid.

  9. An investigation of higher-order effects in modeling exoplanet HAT-P-7b

    NASA Astrophysics Data System (ADS)

    Kurth, Susan Anne

    In its search for Earth-like planets, NASA's Kepler mission observed over 200,000 stars. Among these systems were the class of planets known as the "hot Jupiters." These are giant gaseous planets with periods less than 10 days. Here I present an analysis of the Kepler observations of the exoplanet HAT-P-7b, a hot Jupiter with an orbital period of 2.2 days, a mass of 1.8 MJ, and a radius of 1.5 RJ. Due to its very close proximity to its host star, the planet has a day-side temperature of 2800 K and a night-side temperature of 1950 K. The tight orbit also causes planetary reflection, as well as higher-order effects in the system such as ellipsoidal variations, Doppler beaming, and gravity darkening. My thesis explores these effects on the Kepler HAT-P-7 light curve using the state of the art Eclipsing Light Curve (ELC) code. The "short cadence" data from Kepler contain 2 million measurements, which I phase folded and binned to get robust uncertainties, resulting in a final data set with 2,704 points. Because of the exquisitely high precision of the data (few ppm level), the physical effects mentioned above need to be accounted for. Including these effects enables me to accurately solve for the system parameters.

  10. Implications of the Secondary Eclipse of Exoplanet HAT-P-11b

    NASA Technical Reports Server (NTRS)

    Barry, Richard K.; Deming, L. D.; Bakos, G.; Harrington, J.; Madhusudhan, N.; Noyes, R.; Seager, S.

    2010-01-01

    We observed exoplanet HAT-P-11b and have successfully detected its secondary eclipse. We conducted observations using the Spitzer Space Telescope in the post-cryo mission at 3.6 microns for a period of 22 hours centered on the anticipated secondary eclipse time, to detect the eclipse and determine its phase. Having detected the secondary eclipse, we are at present making a more focused series of observations in both the 3.6 and 4.5 micron bands to fully characterize it. HAT-P-11b is one of only two known exo-Neptunes and has a period of 4.8878 days, radius of 0.422 RJ, mass of 0.081 MJ and semi-major axis 0.053 AU. Measurements of the secondary eclipse will serve to clarify two key issues; 1) the planetary brightness temperature and the nature of its atmosphere, and 2) the eccentricity of its orbit, with implications for its dynamical evolution. We discuss implications of these observations.

  11. Top hat electrostatic analyzer for far-field electric propulsion plume diagnostics

    SciTech Connect

    Victor, Allen L.; Zurbuchen, Thomas H.; Gallimore, Alec D.

    2006-01-15

    The design, development, and testing of the top hat electric propulsion plume analyzer (TOPAZ) are presented for far-field electric propulsion plume diagnostics. The trend towards high-power thruster development will require plume diagnostic techniques capable of measuring high-energy particles as well as low-energy ions produced from charge-exchange collisions due to elevated facility background pressures. TOPAZ incorporates a 'top hat' design with a geometrical analyzer constant of 100 resulting in a wide energy range and a high-energy resolution. SIMION, an ion trajectory analysis program, was used to predict characteristics of the analyzer. An ion beam accelerator system confirms the computational results. TOPAZ provides an energy resolution of 2.7%, field of view of 112 deg. x 26 deg. (azimuthal by elevation) with an angular resolution in each direction of 2 deg., and a demonstrated energy-per-charge acceptance range of 5-15 keV. An energy profile measurement of the NASA-173Mv1 Hall thruster demonstrates instrument operation in a Hall thruster plume.

  12. Design and Optimization of a Compact Wideband Hat-Fed Reflector Antenna for Satellite Communications

    NASA Astrophysics Data System (ADS)

    Geterud, Erik G.; Yang, Jian; Ostling, Tomas; Bergmark, Pontus

    2013-01-01

    We present a new design of the hat-fed reflector antenna for satellite communications, where a low reflection coefficient, high gain, low sidelobes and low cross-polar level are required over a wide frequency band. The hat feed has been optimized by using the Genetic Algorithm through a commercial FDTD solver, QuickWave-V2D, together with an own developed optimization code. The Gaussian vertex plate has been applied at the center of the reflector in order to improve the reflection coefficient and reduce the far-out sidelobes. A parabolic reflector with a ring-shaped focus has been designed for obtaining nearly 100% phase efficiency. The antenna's reflection coefficient is below -17 dB and the radiation patterns satisfy the M-x standard co- and cross-polar sidelobe envelopes for satellite ground stations over a bandwidth of 30%. A low-cost monolayer radome has been designed for the antenna with satisfactory performance. The simulations have been verified by measurements; both of them are presented in the paper.

  13. The refined physical properties of transiting exoplanetary system WASP-11/HAT-P-10

    SciTech Connect

    Wang, Xiao-bin; Gu, Sheng-hong; Wang, Yi-bo; Cameron, Andrew Collier; Hui, Ho-Keung; Kwok, Chi-Tai; Yeung, Bill; Leung, Kam-Cheung

    2014-04-01

    The transiting exoplanetary system WASP-11/HAT-P-10 was observed using the CCD camera at Yunnan Observatories, China from 2008 to 2011, and four new transit light curves were obtained. Combined with published radial velocity measurements, the new transit light curves are analyzed along with available photometric data from the literature using the Markov Chain Monte Carlo technique, and the refined physical parameters of the system are derived, which are compatible with the results of two discovery groups, respectively. The planet mass is M{sub p} = 0.526 ± 0.019 M{sub J} , which is the same as West et al.'s value, and more accurately, the planet radius R{sub p} = 0.999{sub −0.018}{sup +0.029} R{sub J} is identical to the value of Bakos et al. The new result confirms that the planet orbit is circular. By collecting 19 available mid-transit epochs with higher precision, we make an orbital period analysis for WASP-11b/HAT-P-10b, and derive a new value for its orbital period, P = 3.72247669 days. Through an (O – C) study based on these mid-transit epochs, no obvious transit timing variation signal can be found for this system during 2008-2012.

  14. Is lightning a possible source of the radio emission on HAT-P-11b?

    NASA Astrophysics Data System (ADS)

    Hodosán, G.; Rimmer, P. B.; Helling, Ch.

    2016-09-01

    Lightning induced radio emission has been observed on Solar system planets. There have been many attempts to observe exoplanets in the radio wavelength, however, no unequivocal detection has been reported. Lecavelier des Etangs et al. carried out radio transit observations of the exoplanet HAT-P-11b, and suggested that a small part of the radio flux can be attributed to the planet. Here, we assume that this signal is real, and study if this radio emission could be caused by lightning with similar energetic properties like in the Solar system. We find that a lightning storm with 3.8 × 106 times larger flash densities than the Earth-storms with the largest lightning activity is needed to produce the observed signal from HAT-P-11b. The optical emission of such thunderstorm would be comparable to that of the host star. We show that HCN produced by lightning chemistry is observable 2-3 yr after the storm, which produces signatures in the L (3.0-4.0 μm) and N (7.5-14.5 μm) infrared bands. We conclude that it is unlikely that the observed radio signal was produced by lightning, however, future, combined radio and infrared observations may lead to lightning detection on planets outside the Solar system.

  15. The histone acetyltransferase p300 inhibitor C646 reduces pro-inflammatory gene expression and inhibits histone deacetylases

    PubMed Central

    van den Bosch, Thea; Boichenko, Alexander; Leus, Niek G. J.; Eleni Ourailidou, Maria; Wapenaar, Hannah; Rotili, Dante; Mai, Antonello; Imhof, Axel; Bischoff, Rainer; Haisma, Hidde J.; Dekker, Frank J.

    2016-01-01

    Lysine acetylations are reversible posttranslational modifications of histone and non-histone proteins that play important regulatory roles in signal transduction cascades and gene expression. Lysine acetylations are regulated by histone acetyltransferases as writers and histone deacetylases as erasers. Because of their role in signal transduction cascades, these enzymes are important players in inflammation. Therefore, applications of histone acetyltransferase inhibitors to reduce inflammatory responses are interesting. Among the few histone acetyltransferase inhibitors described, C646 is one of the most potent (Ki of 0.4 μM for histone acetyltransferase p300). C646 was described to regulate the NF-κB pathway; an important pathway in inflammatory responses, which is regulated by acetylation. Interestingly, this pathway has been implicated in asthma and COPD. Therefore we hypothesized that via regulation of the NF-κB signaling pathway, C646 can inhibit pro-inflammatory gene expression, and have potential for the treatment of inflammatory lung diseases. In line with this, here we demonstrate that C646 reduces pro-inflammatory gene expression in RAW264.7 murine macrophages and murine precision-cut lung slices. To unravel its effects on cellular substrates we applied mass spectrometry and found, counterintuitively, a slight increase in acetylation of histone H3. Based on this finding, and structural features of C646, we presumed inhibitory activity of C646 on histone deacetylases, and indeed found inhibition of histone deacetylases from 7 μM and higher concentrations. This indicates that C646 has potential for further development towards applications in the treatment of inflammation, however, its newly discovered lack of selectivity at higher concentrations needs to be taken into account. PMID:26718586

  16. Radiologic characterization of the Mexican Hat, Utah, uranium mill tailings remedial action site: Appendix D, Addenda D1--D7

    SciTech Connect

    Ludlam, J.R.

    1985-01-01

    This radiologic characterization of the inactive uranium millsite at Mexican Hat, Utah, was conducted by Bendix Field Engineering Corporation foe the US Department of Energy (DOE), Grand Junction Project Office, in response to and in accord with a Statement of Work prepared by the DOE Uranium Mill tailings Remedial Action Project (UMTRAP) Technical Assistance Contractor, Jacobs Engineering Group, Inc. the objective of this project was to determine the horizontal and vertical extent of contamination that exceeds the US Environmental Protection Agency (EPA) standards at the Mexican Hat site. The data presented in this report are required for characterization of the areas adjacent to the Mexican Hat tailings piles and for the subsequent design of cleanup activities. Some on-pile sampling was required to determine the depth of the 15-pCi/g Ra-226 interface in an area where wind and water erosion has taken place.

  17. HATS-7b: A Hot Super Neptune Transiting a Quiet K Dwarf Star

    NASA Astrophysics Data System (ADS)

    Bakos, G. Á.; Penev, K.; Bayliss, D.; Hartman, J. D.; Zhou, G.; Brahm, R.; Mancini, L.; de Val-Borro, M.; Bhatti, W.; Jordán, A.; Rabus, M.; Espinoza, N.; Csubry, Z.; Howard, A. W.; Fulton, B. J.; Buchhave, L. A.; Ciceri, S.; Henning, T.; Schmidt, B.; Isaacson, H.; Noyes, R. W.; Marcy, G. W.; Suc, V.; Howe, A. R.; Burrows, A. S.; Lázár, J.; Papp, I.; Sári, P.

    2015-11-01

    We report the discovery by the HATSouth network of HATS-7b, a transiting Super-Neptune with a mass of 0.120 ± 0.012 {M}{{J}}, a radius of {0.563}-0.034+0.046 {R}{{J}}, and an orbital period of 3.1853 days. The host star is a moderately bright (V=13.340\\+/- 0.010 mag, {K}S=10.976\\+/- 0.026 mag) K dwarf star with a mass of 0.849 ± 0.027 {M}ȯ , a radius of {0.815}-0.035+0.049 {R}ȯ , and a metallicity of [{Fe}/{{H}}] =+0.250\\+/- 0.080. The star is photometrically quiet to within the precision of the HATSouth measurements, has low RV jitter, and shows no evidence for chromospheric activity in its spectrum. HATS-7b is the second smallest radius planet discovered by a wide-field ground-based transit survey, and one of only a handful of Neptune-size planets with mass and radius determined to 10% precision. Theoretical modeling of HATS-7b yields a hydrogen–helium fraction of 18 ± 4% (rock-iron core and H2–He envelope), or 9 ± 4% (ice core and H2–He envelope), i.e., it has a composition broadly similar to that of Uranus and Neptune, and very different from that of Saturn, which has 75% of its mass in H2–He. Based on a sample of transiting exoplanets with accurately (<20%) determined parameters, we establish approximate power-law relations for the envelopes of the mass–density distribution of exoplanets. HATS-7b, which, together with the recently discovered HATS-8b, is one of the first two transiting super-Neptunes discovered in the Southern sky, is a prime target for additional follow-up observations with Southern hemisphere facilities to characterize the atmospheres of Super-Neptunes (which we define as objects with mass greater than that of Neptune, and smaller than halfway between that of Neptune and Saturn, i.e., 0.054 {M}{{J}}\\lt {M}{{p}}\\lt 0.18 {M}{{J}}). The HATSouth network is operated by a collaboration consisting of Princeton University (PU), the Max Planck Institute für Astronomie (MPIA), the Australian National University (ANU), and the

  18. HATS-7b: A Hot Super Neptune Transiting a Quiet K Dwarf Star

    NASA Astrophysics Data System (ADS)

    Bakos, G. Á.; Penev, K.; Bayliss, D.; Hartman, J. D.; Zhou, G.; Brahm, R.; Mancini, L.; de Val-Borro, M.; Bhatti, W.; Jordán, A.; Rabus, M.; Espinoza, N.; Csubry, Z.; Howard, A. W.; Fulton, B. J.; Buchhave, L. A.; Ciceri, S.; Henning, T.; Schmidt, B.; Isaacson, H.; Noyes, R. W.; Marcy, G. W.; Suc, V.; Howe, A. R.; Burrows, A. S.; Lázár, J.; Papp, I.; Sári, P.

    2015-11-01

    We report the discovery by the HATSouth network of HATS-7b, a transiting Super-Neptune with a mass of 0.120 ± 0.012 {M}{{J}}, a radius of {0.563}-0.034+0.046 {R}{{J}}, and an orbital period of 3.1853 days. The host star is a moderately bright (V=13.340\\+/- 0.010 mag, {K}S=10.976\\+/- 0.026 mag) K dwarf star with a mass of 0.849 ± 0.027 {M}⊙ , a radius of {0.815}-0.035+0.049 {R}⊙ , and a metallicity of [{Fe}/{{H}}] =+0.250\\+/- 0.080. The star is photometrically quiet to within the precision of the HATSouth measurements, has low RV jitter, and shows no evidence for chromospheric activity in its spectrum. HATS-7b is the second smallest radius planet discovered by a wide-field ground-based transit survey, and one of only a handful of Neptune-size planets with mass and radius determined to 10% precision. Theoretical modeling of HATS-7b yields a hydrogen-helium fraction of 18 ± 4% (rock-iron core and H2-He envelope), or 9 ± 4% (ice core and H2-He envelope), i.e., it has a composition broadly similar to that of Uranus and Neptune, and very different from that of Saturn, which has 75% of its mass in H2-He. Based on a sample of transiting exoplanets with accurately (<20%) determined parameters, we establish approximate power-law relations for the envelopes of the mass-density distribution of exoplanets. HATS-7b, which, together with the recently discovered HATS-8b, is one of the first two transiting super-Neptunes discovered in the Southern sky, is a prime target for additional follow-up observations with Southern hemisphere facilities to characterize the atmospheres of Super-Neptunes (which we define as objects with mass greater than that of Neptune, and smaller than halfway between that of Neptune and Saturn, i.e., 0.054 {M}{{J}}\\lt {M}{{p}}\\lt 0.18 {M}{{J}}). The HATSouth network is operated by a collaboration consisting of Princeton University (PU), the Max Planck Institute für Astronomie (MPIA), the Australian National University (ANU), and the Pontificia

  19. Acetyl Coenzyme A Acetyltransferase of Rhizobium sp. (Cicer) Strain CC 1192.

    PubMed

    Kim, S A; Copeland, L

    1997-09-01

    To investigate why Rhizobium sp. (Cicer) strain CC 1192 cells accumulate poly-R-3-hydroxybutyrate in the free-living state but not as bacteroids in nodules on chickpea (Cicer arietinum L.) plants, we have examined the kinetic properties of acetyl coenzyme A (acetyl-CoA) acetyltransferase (also known as acetoacetyl-CoA thiolase and 3-ketothiolase [EC 2.3.1.9]) from both types of cells. The enzyme had a native molecular mass of 180 (plusmn) 4 kDa, and the subunit molecular mass was 44 (plusmn) 1 kDa. The seven amino acids from the N terminus were Lys-Ala-Ser-Ile-Val-Ile-Ala. Thiolysis and condensation activity of the enzyme from free-living CC 1192 cells were optimal at pHs 7.8 and 8.1, respectively. The relationship between substrate concentrations and initial velocity for the thiolysis reaction were hyperbolic and gave K(infm) values for acetoacetyl-CoA and CoA of 42 and 56 (mu)M, respectively. The maximum velocity in the condensation direction was approximately 10% of that of the thiolysis reaction. With highly purified preparations of the enzyme, a value of approximately 1 mM was determined for the apparent K(infm) for acetyl-CoA. However, with partially purified enzyme preparations or when N-ethylmaleimide was included in reaction mixtures the apparent K(infm) for acetyl-CoA was close to 0.3 mM. In the condensation direction, CoA was a potent linear competitive inhibitor with an inhibition constant of 11 (mu)M. The much higher affinity of the enzyme for the product CoA than the substrate acetyl-CoA could have significance in view of metabolic differences between bacteroid and free-living cells of CC 1192. We propose that in free-living CC 1192 cells, the acetyl-CoA/CoA ratio reaches a value that allows condensation activity of acetyl-CoA acetyltransferase, but that in CC 1192 bacteroids, the ratio is poised so that the formation of acetoacetyl-CoA is not favored.

  20. New O-acetyltransferase-deficient Ames Salmonella strains generated by specific gene disruption.

    PubMed

    Espinosa-Aguirre, J J; Yamada, M; Matsui, K; Watanabe, M; Sofuni, T; Nohmi, T

    1999-02-19

    CoASAc-dependent N-hydroxyarylamine O-acetyltransferase (OAT) is an enzyme involved in the intracellular metabolic activation of N-hydroxyarylamines derived from mutagenic nitroarenes and aromatic amines. The oat gene encoding the enzyme of S. typhimurium TA98 and TA100 was specifically disrupted and the sensitivities of the resulting strains, i.e., YG7130 and YG7126, to mutagens were compared with those of the conventional oat-deficient strains, i.e., TA98/1,8DNP6 and TA100/1,8DNP, respectively. The new oat-deficient strains and the conventional strains exhibited similar sensitivity against most of the chemicals tested: both strains YG7130 and strain TA98/1,8-DNP6 were resistant to mutagenicity by 1,8-dinitropyrene (1, 8-DNP), 1-nitropyrene, 2-amino-6-methyldipyrido[1,2-alpha:3', 2'-d]imidazole (Glu-P-1) and 2-amino-3-methyl-3H-imidazo[4, 5-f]quinoline (IQ); neither strain YG7130 nor strain TA98/1,8-DNP6 was resistant to the mutagenicity of 3-amino-1-methyl-5H-pyrido[4, 3-b]indole (Trp-P-2); strain YG7126 and strain TA100/1,8-DNP were refractory to the mutagenicity of 1,8-DNP. However, the order of the sensitivity against 2-nitrofluorene (2-NF) was TA98>YG7130>TA98/1, 8-DNP6 and TA100>YG7126>TA100/1,8-DNP. Since the strains YG7130 and YG7126 have chloramphenicol resistance (Cmr) gene in place of the chromosomal oat gene for gene disruption, the possible involvement of chloramphenicol acetyltransferase (CAT) encoded by the Cmr gene in the activation of 2-NF was examined. Strikingly, introduction of plasmid pACYC184 carrying the Cmr gene alone substantially enhanced the sensitivity of the conventional oat-deficient strains to 2-NF. These results suggest that the new strains as well as the conventional strains are useful to assess the roles of OAT in the metabolic activation of nitroaromatics and aromatic amines in S. typhimurium, and also that CAT has the ability to activate N-hydroxy aromatic amines to mutagens. PMID:10023048

  1. HAT-P-17b,c: A TRANSITING, ECCENTRIC, HOT SATURN AND A LONG-PERIOD, COLD JUPITER

    SciTech Connect

    Howard, A. W.; Marcy, G. W.; Bakos, G. A.; Hartman, J.; Torres, G.; Latham, D. W.; Noyes, R. W.; Esquerdo, G. A.; Beky, B.; Sasselov, D. D.; Stefanik, R. P.; Perumpilly, G.; Shporer, A.; Mazeh, T.; Kovacs, Geza; Fischer, D. A.; Johnson, J. A.; Butler, R. P.; Lazar, J.; Papp, I. E-mail: gbakos@cfa.harvard.edu; and others

    2012-04-20

    We report the discovery of HAT-P-17b,c, a multi-planet system with an inner transiting planet in a short-period, eccentric orbit and an outer planet in a 4.4 yr, nearly circular orbit. The inner planet, HAT-P-17b, transits the bright V = 10.54 early K dwarf star GSC 2717-00417, with an orbital period P = 10.338523 {+-} 0.000009 days, orbital eccentricity e = 0.342 {+-} 0.006, transit epoch T{sub c} = 2454801.16943 {+-} 0.00020 (BJD: barycentric Julian dates throughout the paper are calculated from Coordinated Universal Time (UTC)), and transit duration 0.1690 {+-} 0.0009 days. HAT-P-17b has a mass of 0.534 {+-} 0.018 M{sub J} and radius of 1.010 {+-} 0.029 R{sub J} yielding a mean density of 0.64 {+-} 0.05 g cm{sup -3}. This planet has a relatively low equilibrium temperature in the range 780-927 K, making it an attractive target for follow-up spectroscopic studies. The outer planet, HAT-P-17c, has a significantly longer orbital period P{sub 2} = 1610 {+-} 20 days and a minimum mass m{sub 2}sin i{sub 2} = 1.31{sup +0.18}{sub -0.15} M{sub J}. The orbital inclination of HAT-P-17c is unknown as transits have not been observed and may not be present. The host star has a mass of 0.86 {+-} 0.04 M{sub Sun }, radius of 0.84 {+-} 0.02 R{sub Sun }, effective temperature 5246 {+-} 80 K, and metallicity [Fe/H] = 0.00 {+-} 0.08. HAT-P-17 is the second multi-planet system detected from ground-based transit surveys.

  2. Structures and functions of insect arylalkylamine N-acetyltransferase (iaaNAT); a key enzyme for physiological and behavioral switch in arthropods

    PubMed Central

    Hiragaki, Susumu; Suzuki, Takeshi; Mohamed, Ahmed A. M.; Takeda, Makio

    2015-01-01

    The evolution of N-acetyltransfeases (NATs) seems complex. Vertebrate arylalkylamine N-acetyltransferase (aaNAT) has been extensively studied since it leads to the synthesis of melatonin, a multifunctional neurohormone prevalent in photoreceptor cells, and is known as a chemical token of the night. Melatonin also serves as a scavenger for reactive oxygen species. This is also true with invertebrates. NAT therefore has distinct functional implications in circadian function, as timezymes (aaNAT), and also xenobiotic reactions (arylamine NAT or simply NAT). NATs belong to a broader enzyme group, the GCN5-related N-acetyltransferase superfamily. Due to low sequence homology and a seemingly fast rate of structural differentiation, the nomenclature for NATs can be confusing. The advent of bioinformatics, however, has helped to classify this group of enzymes; vertebrates have two distinct subgroups, the timezyme type and the xenobiotic type, which has a wider substrate range including imidazolamine, pharmacological drugs, environmental toxicants and even histone. Insect aaNAT (iaaNAT) form their own clade in the phylogeny, distinct from vertebrate aaNATs. Arthropods are unique, since the phylum has exoskeleton in which quinones derived from N-acetylated monoamines function in coupling chitin and arthropodins. Monoamine oxidase (MAO) activity is limited in insects, but NAT-mediated degradation prevails. However, unexpectedly iaaNAT occurs not only among arthropods but also among basal deuterostomia, and is therefore more apomorphic. Our analyses illustrate that iaaNATs has unique physiological roles but at the same time it plays a role in a timezyme function, at least in photoperiodism. Photoperiodism has been considered as a function of circadian system but the detailed molecular mechanism is not well understood. We propose a molecular hypothesis for photoperiodism in Antheraea pernyi based on the transcription regulation of NAT interlocked by the circadian system

  3. Wave-turbulence description of interacting particles: Klein-Gordon model with a Mexican-hat potential

    NASA Astrophysics Data System (ADS)

    Gallet, Basile; Nazarenko, Sergey; Dubrulle, Bérengère

    2015-07-01

    In field theory, particles are waves or excitations that propagate on the fundamental state. In experiments or cosmological models, one typically wants to compute the out-of-equilibrium evolution of a given initial distribution of such waves. Wave turbulence deals with out-of-equilibrium ensembles of weakly nonlinear waves, and is therefore well suited to address this problem. As an example, we consider the complex Klein-Gordon equation with a Mexican-hat potential. This simple equation displays two kinds of excitations around the fundamental state: massive particles and massless Goldstone bosons. The former are waves with a nonzero frequency for vanishing wave number, whereas the latter obey an acoustic dispersion relation. Using wave-turbulence theory, we derive wave kinetic equations that govern the coupled evolution of the spectra of massive and massless waves. We first consider the thermodynamic solutions to these equations and study the wave condensation transition, which is the classical equivalent of Bose-Einstein condensation. We then focus on nonlocal interactions in wave-number space: we study the decay of an ensemble of massive particles into massless ones. Under rather general conditions, these massless particles accumulate at low wave number. We study the dynamics of waves coexisting with such a strong condensate, and we compute rigorously a nonlocal Kolmogorov-Zakharov solution, where particles are transferred nonlocally to the condensate, while energy cascades towards large wave numbers through local interactions. This nonlocal cascading state constitutes the intermediate asymptotics between the initial distribution of waves and the thermodynamic state reached in the long-time limit.

  4. Wave-turbulence description of interacting particles: Klein-Gordon model with a Mexican-hat potential.

    PubMed

    Gallet, Basile; Nazarenko, Sergey; Dubrulle, Bérengère

    2015-07-01

    In field theory, particles are waves or excitations that propagate on the fundamental state. In experiments or cosmological models, one typically wants to compute the out-of-equilibrium evolution of a given initial distribution of such waves. Wave turbulence deals with out-of-equilibrium ensembles of weakly nonlinear waves, and is therefore well suited to address this problem. As an example, we consider the complex Klein-Gordon equation with a Mexican-hat potential. This simple equation displays two kinds of excitations around the fundamental state: massive particles and massless Goldstone bosons. The former are waves with a nonzero frequency for vanishing wave number, whereas the latter obey an acoustic dispersion relation. Using wave-turbulence theory, we derive wave kinetic equations that govern the coupled evolution of the spectra of massive and massless waves. We first consider the thermodynamic solutions to these equations and study the wave condensation transition, which is the classical equivalent of Bose-Einstein condensation. We then focus on nonlocal interactions in wave-number space: we study the decay of an ensemble of massive particles into massless ones. Under rather general conditions, these massless particles accumulate at low wave number. We study the dynamics of waves coexisting with such a strong condensate, and we compute rigorously a nonlocal Kolmogorov-Zakharov solution, where particles are transferred nonlocally to the condensate, while energy cascades towards large wave numbers through local interactions. This nonlocal cascading state constitutes the intermediate asymptotics between the initial distribution of waves and the thermodynamic state reached in the long-time limit.

  5. Final audit report of remedial action construction at the UMTRA Project Mexican Hat, Utah -- Monument Valley, Arizona, sites

    SciTech Connect

    1995-10-01

    The final audit report for remedial action at the Mexican Hat, Utah, Monument Valley, Arizona, Uranium Mill Tailings Remedial Action (UMTRA) Project sites consists of a summary of the radiological surveillances/audits, quality assurance (QA) in-process surveillances, and QA remedial action close-out inspections performed by the US Department of Energy (DOE) and the Technical Assistance Contractor (TAC); on-site construction reviews (OSCR) performed by the US Nuclear Regulatory Commission (NRC); and a surveillance performed by the Navajo Nation. This report refers to remedial action activities performed at the Mexican Hat, Utah--Monument Valley, Arizona, Uranium Mill Tailings Remedial Action (UMTRA) Project sites.

  6. Effect of maternal deprivation on N-acetyltransferase activity rhythm in blinded rat pups.

    PubMed

    Katoh, Y; Takeuchi, Y; Yamazaki, K; Takahashi, K

    1998-02-15

    It has been reported that the rhythms of infant rats synchronize with the mother's rhythm until the light-dark cycle comes and has strong effects on their endogenous clocks. We found that periodic maternal deprivation (PMD) was able to cause a phase shift of serotonin N-acetyltransferase (NAT) in neonatal blinded rat pups. PMD in which contact with the mother was allowed for only 4 h caused a phase shift of NAT rhythm, irrespective of the timing of contact with the mother in a day. Acute single mother deprivation caused an excess of NAT activity for more hours than usual and contact with the mother prevented such an excessive response. Mother deprivation may act as a cold stress, since artificial warming of pups gave the same results as contact with the mother. When the pups were artificially warmed by a heater during a 1-week deprivation period, a flat 24-h pattern of NAT was observed. The mechanism causing a phase shift of NAT activity rhythm of rat pups may be complicated. PMID:9523895

  7. Response of ATP sulfurylase and serine acetyltransferase towards cadmium in hyperaccumulator Sedum alfredii Hance*

    PubMed Central

    Guo, Wei-dong; Liang, Jun; Yang, Xiao-e; Chao, Yue-en; Feng, Ying

    2009-01-01

    We studied the responses of the activities of adenosine-triphosphate (ATP) sulfurylase (ATPS) and serine acetyltransferase (SAT) to cadmium (Cd) levels and treatment time in hyperaccumulating ecotype (HE) Sedum alfredii Hance, as compared with its non-hyperaccumulating ecotype (NHE). The results show that plant growth was inhibited in NHE but promoted in HE when exposed to high Cd level. Cd concentrations in leaves and shoots rapidly increased in HE rather than in NHE, and they became much higher in HE than in NHE along with increasing treatment time and Cd supply levels. ATPS activity was higher in HE than in NHE in all Cd treatments, and increased with increasing Cd supply levels in both HE and NHE when exposed to Cd treatment within 8 h. However, a marked difference of ATPS activity between HE and NHE was found with Cd treatment for 168 h, where ATPS activity increased in HE but decreased in NHE. Similarly, SAT activity was higher in HE than in NHE at all Cd treatments, but was more sensitive in NHE than in HE. Both ATPS and SAT activities in NHE leaves tended to decrease with increasing treatment time after 8 h at all Cd levels. The results reveal the different responses in sulfur assimilation enzymes and Cd accumulation between HE and NHE. With increasing Cd stress, the activities of sulfur assimilation enzymes (ATPS and SAT) were induced in HE, which may contribute to Cd accumulation in the hyperaccumulator Sedum alfredii Hance. PMID:19353742

  8. Response of ATP sulfurylase and serine acetyltransferase towards cadmium in hyperaccumulator Sedum alfredii Hance.

    PubMed

    Guo, Wei-dong; Liang, Jun; Yang, Xiao-e; Chao, Yue-en; Feng, Ying

    2009-04-01

    We studied the responses of the activities of adenosine-triphosphate (ATP) sulfurylase (ATPS) and serine acetyltransferase (SAT) to cadmium (Cd) levels and treatment time in hyperaccumulating ecotype (HE) Sedum alfredii Hance, as compared with its non-hyperaccumulating ecotype (NHE). The results show that plant growth was inhibited in NHE but promoted in HE when exposed to high Cd level. Cd concentrations in leaves and shoots rapidly increased in HE rather than in NHE, and they became much higher in HE than in NHE along with increasing treatment time and Cd supply levels. ATPS activity was higher in HE than in NHE in all Cd treatments, and increased with increasing Cd supply levels in both HE and NHE when exposed to Cd treatment within 8 h. However, a marked difference of ATPS activity between HE and NHE was found with Cd treatment for 168 h, where ATPS activity increased in HE but decreased in NHE. Similarly, SAT activity was higher in HE than in NHE at all Cd treatments, but was more sensitive in NHE than in HE. Both ATPS and SAT activities in NHE leaves tended to decrease with increasing treatment time after 8 h at all Cd levels. The results reveal the different responses in sulfur assimilation enzymes and Cd accumulation between HE and NHE. With increasing Cd stress, the activities of sulfur assimilation enzymes (ATPS and SAT) were induced in HE, which may contribute to Cd accumulation in the hyperaccumulator Sedum alfredii Hance. PMID:19353742

  9. A direct, ratiometric, and quantitative MALDI–MS assay for protein methyltransferases and acetyltransferases

    PubMed Central

    Richardson, Stacie L.; Hanjra, Pahul; Zhang, Gang; Mackie, Brianna D.; Peterson, Darrell L.; Huang, Rong

    2016-01-01

    Protein methylation and acetylation play important roles in biological processes, and misregulation of these modifications is involved in various diseases. Therefore, it is critical to understand the activities of the enzymes responsible for these modifications. Herein we describe a sensitive method for ratiometric quantification of methylated and acetylated peptides via MALDI-MS by direct spotting of enzymatic methylation and acetylation reaction mixtures without tedious purification procedures. The quantifiable detection limit for peptides with our method is approximately 10 fmol. This is achieved by increasing the signal-to-noise ratio through the addition of NH4H2PO4 to the matrix solution and reduction of the matrix α-cyanohydroxycinnamic acid concentration to 2 mg/ml. We have demonstrated the application of this method in enzyme kinetic analysis and inhibition studies. The unique feature of this method is the simultaneous quantification of multiple peptide species for investigation of processivity mechanisms. Its wide buffer compatibility makes it possible to be adapted to investigate the activity of any protein methyltransferase or acetyltransferase. PMID:25778392

  10. Novel ligands of Choline Acetyltransferase designed by in silico molecular docking, hologram QSAR and lead optimization.

    PubMed

    Kumar, Rajnish; Långström, Bengt; Darreh-Shori, Taher

    2016-01-01

    Recent reports have brought back the acetylcholine synthesizing enzyme, choline acetyltransferase in the mainstream research in dementia and the cholinergic anti-inflammatory pathway. Here we report, a specific strategy for the design of novel ChAT ligands based on molecular docking, Hologram Quantitative Structure Activity Relationship (HQSAR) and lead optimization. Molecular docking was performed on a series of ChAT inhibitors to decipher the molecular fingerprint of their interaction with the active site of ChAT. Then robust statistical fragment HQSAR models were developed. A library of novel ligands was generated based on the pharmacophoric and shape similarity scoring function, and evaluated in silico for their molecular interactions with ChAT. Ten of the top scoring invented compounds are reported here. We confirmed the activity of α-NETA, the only commercially available ChAT inhibitor, and one of the seed compounds in our model, using a new simple colorimetric ChAT assay (IC50 ~ 88 nM). In contrast, α-NETA exhibited an IC50 of ~30 μM for the ACh-degrading cholinesterases. In conclusion, the overall results may provide useful insight for discovering novel ChAT ligands and potential positron emission tomography tracers as in vivo functional biomarkers of the health of central cholinergic system in neurodegenerative disorders, such as Alzheimer's disease.

  11. Muscle-specific deletion of carnitine acetyltransferase compromises glucose tolerance and metabolic flexibility.

    PubMed

    Muoio, Deborah M; Noland, Robert C; Kovalik, Jean-Paul; Seiler, Sarah E; Davies, Michael N; DeBalsi, Karen L; Ilkayeva, Olga R; Stevens, Robert D; Kheterpal, Indu; Zhang, Jingying; Covington, Jeffrey D; Bajpeyi, Sudip; Ravussin, Eric; Kraus, William; Koves, Timothy R; Mynatt, Randall L

    2012-05-01

    The concept of "metabolic inflexibility" was first introduced to describe the failure of insulin-resistant human subjects to appropriately adjust mitochondrial fuel selection in response to nutritional cues. This phenomenon has since gained increasing recognition as a core component of the metabolic syndrome, but the underlying mechanisms have remained elusive. Here, we identify an essential role for the mitochondrial matrix enzyme, carnitine acetyltransferase (CrAT), in regulating substrate switching and glucose tolerance. By converting acetyl-CoA to its membrane permeant acetylcarnitine ester, CrAT regulates mitochondrial and intracellular carbon trafficking. Studies in muscle-specific Crat knockout mice, primary human skeletal myocytes, and human subjects undergoing L-carnitine supplementation support a model wherein CrAT combats nutrient stress, promotes metabolic flexibility, and enhances insulin action by permitting mitochondrial efflux of excess acetyl moieties that otherwise inhibit key regulatory enzymes such as pyruvate dehydrogenase. These findings offer therapeutically relevant insights into the molecular basis of metabolic inflexibility. PMID:22560225

  12. Novel ligands of Choline Acetyltransferase designed by in silico molecular docking, hologram QSAR and lead optimization

    PubMed Central

    Kumar, Rajnish; Långström, Bengt; Darreh-Shori, Taher

    2016-01-01

    Recent reports have brought back the acetylcholine synthesizing enzyme, choline acetyltransferase in the mainstream research in dementia and the cholinergic anti-inflammatory pathway. Here we report, a specific strategy for the design of novel ChAT ligands based on molecular docking, Hologram Quantitative Structure Activity Relationship (HQSAR) and lead optimization. Molecular docking was performed on a series of ChAT inhibitors to decipher the molecular fingerprint of their interaction with the active site of ChAT. Then robust statistical fragment HQSAR models were developed. A library of novel ligands was generated based on the pharmacophoric and shape similarity scoring function, and evaluated in silico for their molecular interactions with ChAT. Ten of the top scoring invented compounds are reported here. We confirmed the activity of α-NETA, the only commercially available ChAT inhibitor, and one of the seed compounds in our model, using a new simple colorimetric ChAT assay (IC50 ~ 88 nM). In contrast, α-NETA exhibited an IC50 of ~30 μM for the ACh-degrading cholinesterases. In conclusion, the overall results may provide useful insight for discovering novel ChAT ligands and potential positron emission tomography tracers as in vivo functional biomarkers of the health of central cholinergic system in neurodegenerative disorders, such as Alzheimer’s disease. PMID:27507101

  13. Human Neural Stem Cells Overexpressing Choline Acetyltransferase Restore Unconditioned Fear in Rats with Amygdala Injury

    PubMed Central

    Shin, Kyungha; Cha, Yeseul; Kim, Kwang Sei; Choi, Ehn-Kyoung; Choi, Youngjin; Guo, Haiyu; Ban, Young-Hwan; Kim, Jong-Choon; Park, Dongsun; Kim, Yun-Bae

    2016-01-01

    Amygdala is involved in the fear memory that recognizes certain environmental cues predicting threatening events. Manipulation of neurotransmission within the amygdala affects the expression of conditioned and unconditioned emotional memories such as fear freezing behaviour. We previously demonstrated that F3.ChAT human neural stem cells (NSCs) overexpressing choline acetyltransferase (ChAT) improve cognitive function of Alzheimer's disease model rats with hippocampal or cholinergic nerve injuries by increasing acetylcholine (ACh) level. In the present study, we examined the effect of F3.ChAT cells on the deficit of unconditioned fear freezing. Rats given N-methyl-d-aspartate (NMDA) in their amygdala 2 weeks prior to cat odor exposure displayed very short resting (freezing) time compared to normal animals. NMDA induced neuronal degeneration in the amygdala, leading to a decreased ACh concentration in cerebrospinal fluid. However, intracerebroventricular transplantation of F3.ChAT cells attenuated amygdala lesions 4 weeks after transplantation. The transplanted cells were found in the NMDA-injury sites and produced ChAT protein. In addition, F3.ChAT-receiving rats recuperated freezing time staying remote from the cat odor source, according to the recovery of brain ACh concentration. The results indicate that human NSCs overexpressing ChAT may facilitate retrieval of unconditioned fear memory by increasing ACh level. PMID:27087745

  14. Retinal, pineal and diencephalic expression of frog arylalkylamine N-acetyltransferase-1.

    PubMed

    Isorna, Esther; Besseau, Laurence; Boeuf, Gilles; Desdevises, Yves; Vuilleumier, Robin; Alonso-Gómez, Angel L; Delgado, María J; Falcón, Jack

    2006-06-27

    The arylalkylamine N-acetyltransferase (AANAT) is a key enzyme in the rhythmic production of melatonin. Two Aanats are expressed in Teleost fish (Aanat1 in the retina and Aanat2 in the pineal organ) but only Aanat1 is found in tetrapods. This study reports the cloning of Aanat1 from R. perezi. Transcripts were mainly expressed in the retina, diencephalon, intestine and testis. In the retina and pineal organ, Aanat1 expression was in the photoreceptor cells. Expression was also seen in ependymal cells of the 3rd ventricle and discrete cells of the suprachiasmatic area. The expression of Aanat1 in both the retina and pineal organ, and the absence of Aanat2 suggests that green frog resembles more to birds and mammals than to Teleost fish, as far as Aanat is concerned. The significance of Aanat1 in extra-pineal and extra-retinal tissues remains to be elucidated; in the diencephalon, it might be associated to the so-called deep brain photoreceptor cells.

  15. P300 acetyltransferase regulates fatty acid synthase expression, lipid metabolism and prostate cancer growth.

    PubMed

    Gang, Xiaokun; Yang, Yinhui; Zhong, Jian; Jiang, Kui; Pan, Yunqian; Karnes, R Jeffrey; Zhang, Jun; Xu, Wanhai; Wang, Guixia; Huang, Haojie

    2016-03-22

    De novo fatty acid (FA) synthesis is required for prostate cancer (PCa) survival and progression. As a key enzyme for FA synthesis fatty acid synthase (FASN) is often overexpressed in human prostate cancers and its expression correlates with worse prognosis and poor survival. P300 is an acetyltransferase that acts as a transcription co-activator. Increasing evidence suggests that P300 is a major PCa promoter, although the underlying mechanism remains poorly understood. Here, we demonstrated that P300 binds to and increases histone H3 lysine 27 acetylation (H3K27Ac) in the FASN gene promoter. We provided evidence that P300 transcriptionally upregulates FASN expression and promotes lipid accumulation in human PCa cells in culture and Pten knockout prostate tumors in mice. Pharmacological inhibition of P300 decreased FASN expression and lipid droplet accumulation in PCa cells. Immunohistochemistry analysis revealed that expression of P300 protein positively correlates with FASN protein levels in a cohort of human PCa specimens. We further showed that FASN is a key mediator of P300-induced growth of PCa cells in culture and in mice. Together, our findings demonstrate P300 as a key factor that regulates FASN expression, lipid accumulation and cell growth in PCa. They also suggest that this regulatory pathway can serve as a new therapeutic target for PCa treatment. PMID:26934656

  16. Effects of tubulin acetylation and tubulin acetyltransferase binding on microtubule structure

    PubMed Central

    Howes, Stuart C.; Alushin, Gregory M.; Shida, Toshinobu; Nachury, Maxence V.; Nogales, Eva

    2014-01-01

    Tubulin undergoes posttranslational modifications proposed to specify microtubule subpopulations for particular functions. Most of these modifications occur on the C-termini of tubulin and may directly affect the binding of microtubule-associated proteins (MAPs) or motors. Acetylation of Lys-40 on α-tubulin is unique in that it is located on the luminal surface of microtubules, away from the interaction sites of most MAPs and motors. We investigate whether acetylation alters the architecture of microtubules or the conformation of tubulin, using cryo–electron microscopy (cryo-EM). No significant changes are observed based on protofilament distributions or microtubule helical lattice parameters. Furthermore, no clear differences in tubulin structure are detected between cryo-EM reconstructions of maximally deacetylated or acetylated microtubules. Our results indicate that the effect of acetylation must be highly localized and affect interaction with proteins that bind directly to the lumen of the microtubule. We also investigate the interaction of the tubulin acetyltransferase, αTAT1, with microtubules and find that αTAT1 is able to interact with the outside of the microtubule, at least partly through the tubulin C-termini. Binding to the outside surface of the microtubule could facilitate access of αTAT1 to its luminal site of action if microtubules undergo lateral opening between protofilaments. PMID:24227885

  17. Environmental History Modulates Arabidopsis Pattern-Triggered Immunity in a HISTONE ACETYLTRANSFERASE1-Dependent Manner.

    PubMed

    Singh, Prashant; Yekondi, Shweta; Chen, Po-Wen; Tsai, Chia-Hong; Yu, Chun-Wei; Wu, Keqiang; Zimmerli, Laurent

    2014-06-24

    In nature, plants are exposed to a fluctuating environment, and individuals exposed to contrasting environmental factors develop different environmental histories. Whether different environmental histories alter plant responses to a current stress remains elusive. Here, we show that environmental history modulates the plant response to microbial pathogens. Arabidopsis thaliana plants exposed to repetitive heat, cold, or salt stress were more resistant to virulent bacteria than Arabidopsis grown in a more stable environment. By contrast, long-term exposure to heat, cold, or exposure to high concentrations of NaCl did not provide enhanced protection against bacteria. Enhanced resistance occurred with priming of Arabidopsis pattern-triggered immunity (PTI)-responsive genes and the potentiation of PTI-mediated callose deposition. In repetitively stress-challenged Arabidopsis, PTI-responsive genes showed enrichment for epigenetic marks associated with transcriptional activation. Upon bacterial infection, enrichment of RNA polymerase II at primed PTI marker genes was observed in environmentally challenged Arabidopsis. Finally, repetitively stress-challenged histone acetyltransferase1-1 (hac1-1) mutants failed to demonstrate enhanced resistance to bacteria, priming of PTI, and increased open chromatin states. These findings reveal that environmental history shapes the plant response to bacteria through the development of a HAC1-dependent epigenetic mark characteristic of a primed PTI response, demonstrating a mechanistic link between the primed state in plants and epigenetics.

  18. Human acetyl CoA:arylamine N-acetyltransferase variants generated by random mutagenesis.

    PubMed

    Summerscales, Joanna E; Josephy, P David

    2004-01-01

    Acetyl CoA:arylamine N-acetyltransferase (NAT) enzymes catalyze the N-acetylation of aromatic amines and the O-acetylation of aryl hydroxylamines, reactions that govern the disposition and toxicity of many drugs and carcinogens. The human NAT genes and enzymes NAT1 and NAT2 are highly polymorphic and constitute one of the best studied examples of the genetic control of drug metabolism. Naturally occurring human NAT variants provide limited insight into the relationship between NAT amino acid sequence and enzyme activity. We have shown previously that the expression of recombinant NAT2 in bacterial tester strains results in greatly enhanced sensitivity to mutagenic nitroaromatic compounds (which are reduced to aryl hydroxylamines by bacterial enzymes). We hypothesized that random mutagenesis combined with rapid screening could be used to identify functionally significant amino acid residues in NAT enzymes. Pools of NAT2 variants were generated by polymerase chain reaction-mediated random mutagenesis of the complete coding sequence. Reversion induced by a NAT-dependent mutagen, 3-methyl-2-nitroimidazo[4,5-f]quinoline, was used as the basis for screening these pools to identify variants with altered enzyme activity. Eighteen variants were characterized by quantitative mutagenicity assays and enzyme kinetic measurements. This approach can provide new insight into the biochemistry of enzymes involved in the metabolic activation of mutagens. PMID:14722254

  19. P300 acetyltransferase regulates fatty acid synthase expression, lipid metabolism and prostate cancer growth.

    PubMed

    Gang, Xiaokun; Yang, Yinhui; Zhong, Jian; Jiang, Kui; Pan, Yunqian; Karnes, R Jeffrey; Zhang, Jun; Xu, Wanhai; Wang, Guixia; Huang, Haojie

    2016-03-22

    De novo fatty acid (FA) synthesis is required for prostate cancer (PCa) survival and progression. As a key enzyme for FA synthesis fatty acid synthase (FASN) is often overexpressed in human prostate cancers and its expression correlates with worse prognosis and poor survival. P300 is an acetyltransferase that acts as a transcription co-activator. Increasing evidence suggests that P300 is a major PCa promoter, although the underlying mechanism remains poorly understood. Here, we demonstrated that P300 binds to and increases histone H3 lysine 27 acetylation (H3K27Ac) in the FASN gene promoter. We provided evidence that P300 transcriptionally upregulates FASN expression and promotes lipid accumulation in human PCa cells in culture and Pten knockout prostate tumors in mice. Pharmacological inhibition of P300 decreased FASN expression and lipid droplet accumulation in PCa cells. Immunohistochemistry analysis revealed that expression of P300 protein positively correlates with FASN protein levels in a cohort of human PCa specimens. We further showed that FASN is a key mediator of P300-induced growth of PCa cells in culture and in mice. Together, our findings demonstrate P300 as a key factor that regulates FASN expression, lipid accumulation and cell growth in PCa. They also suggest that this regulatory pathway can serve as a new therapeutic target for PCa treatment.

  20. Molecular Evolution of Aralkylamine N-Acetyltransferase in Fish: A Genomic Survey

    PubMed Central

    Li, Jia; You, Xinxin; Bian, Chao; Yu, Hui; Coon, Steven L.; Shi, Qiong

    2015-01-01

    All living organisms synchronize biological functions with environmental changes; melatonin plays a vital role in regulating daily and seasonal variations. Due to rhythmic activity of the timezyme aralkylamine N-acetyltransferase (AANAT), the blood level of melatonin increases at night and decreases during daytime. Whereas other vertebrates have a single form of AANAT, bony fishes possess various isoforms of aanat genes, though the reasons are still unclear. Here, we have taken advantage of multiple unpublished teleost aanat sequences to explore and expand our understanding of the molecular evolution of aanat in fish. Our results confirm that two rounds of whole-genome duplication (WGD) led to the existence of three fish isoforms of aanat, i.e., aanat1a, aanat1b, and aanat2; in addition, gene loss led to the absence of some forms from certain special fish species. Furthermore, we suggest the different roles of two aanat1s in amphibious mudskippers, and speculate that the loss of aanat1a, may be related to terrestrial vision change. Several important sites of AANAT proteins and regulatory elements of aanat genes were analyzed for structural comparison and functional forecasting, respectively, which provides insights into the molecular evolution of the differences between AANAT1 and AANAT2. PMID:26729109

  1. Structural Analysis of a Putative Aminoglycoside N-Acetyltransferase from Bacillus anthracis

    SciTech Connect

    Klimecka, Maria M.; Chruszcz, Maksymilian; Font, Jose; Skarina, Tatiana; Shumilin, Igor; Onopryienko, Olena; Porebski, Przemyslaw J.; Cymborowski, Marcin; Zimmerman, Matthew D.; Hasseman, Jeremy; Glomski, Ian J.; Lebioda, Lukasz; Savchenko, Alexei; Edwards, Aled; Minor, Wladek

    2012-02-15

    For the last decade, worldwide efforts for the treatment of anthrax infection have focused on developing effective vaccines. Patients that are already infected are still treated traditionally using different types of standard antimicrobial agents. The most popular are antibiotics such as tetracyclines and fluoroquinolones. While aminoglycosides appear to be less effective antimicrobial agents than other antibiotics, synthetic aminoglycosides have been shown to act as potent inhibitors of anthrax lethal factor and may have potential application as antitoxins. Here, we present a structural analysis of the BA2930 protein, a putative aminoglycoside acetyltransferase, which may be a component of the bacterium's aminoglycoside resistance mechanism. The determined structures revealed details of a fold characteristic only for one other protein structure in the Protein Data Bank, namely, YokD from Bacillus subtilis. Both BA2930 and YokD are members of the Antibiotic-NAT superfamily (PF02522). Sequential and structural analyses showed that residues conserved throughout the Antibiotic-NAT superfamily are responsible for the binding of the cofactor acetyl coenzyme A. The interaction of BA2930 with cofactors was characterized by both crystallographic and binding studies.

  2. Novel ligands of Choline Acetyltransferase designed by in silico molecular docking, hologram QSAR and lead optimization.

    PubMed

    Kumar, Rajnish; Långström, Bengt; Darreh-Shori, Taher

    2016-01-01

    Recent reports have brought back the acetylcholine synthesizing enzyme, choline acetyltransferase in the mainstream research in dementia and the cholinergic anti-inflammatory pathway. Here we report, a specific strategy for the design of novel ChAT ligands based on molecular docking, Hologram Quantitative Structure Activity Relationship (HQSAR) and lead optimization. Molecular docking was performed on a series of ChAT inhibitors to decipher the molecular fingerprint of their interaction with the active site of ChAT. Then robust statistical fragment HQSAR models were developed. A library of novel ligands was generated based on the pharmacophoric and shape similarity scoring function, and evaluated in silico for their molecular interactions with ChAT. Ten of the top scoring invented compounds are reported here. We confirmed the activity of α-NETA, the only commercially available ChAT inhibitor, and one of the seed compounds in our model, using a new simple colorimetric ChAT assay (IC50 ~ 88 nM). In contrast, α-NETA exhibited an IC50 of ~30 μM for the ACh-degrading cholinesterases. In conclusion, the overall results may provide useful insight for discovering novel ChAT ligands and potential positron emission tomography tracers as in vivo functional biomarkers of the health of central cholinergic system in neurodegenerative disorders, such as Alzheimer's disease. PMID:27507101

  3. Genetically based N-acetyltransferase metabolic polymorphism and low-level environmental exposure to carcinogens.

    PubMed

    Vineis, P; Bartsch, H; Caporaso, N; Harrington, A M; Kadlubar, F F; Landi, M T; Malaveille, C; Shields, P G; Skipper, P; Talaska, G

    1994-05-12

    The metabolic activation or inactivation of carcinogens varies considerably in human populations, and is partly genetically determined. Inter-individual variability in the susceptibility to carcinogens may be particularly important at low degrees of environmental exposure. Examples of probable human carcinogens that present widespread low-dose exposures are environmental tobacco smoke and diesel exhaust. We have determined levels of DNA adducts in bladder cells and of 4-aminobiphenyl-haemoglobin adducts in 97 volunteers, together with the N-acetylation non-inducible phenotype, the corresponding genotype, and the levels of nicotine-cotinine in the urine. We find that among the slow acetylators, 4-aminobiphenyl adducts were higher than in rapid acetylators at low or null nicotine-cotinine levels, whereas the difference between slow and rapid acetylators was less evident at increasing nicotine-cotinine levels. The N-acetyltransferase genotype is highly predictive of the acetylation phenotype. Our results indicate that the clearance of low-dose carcinogens is decreased in the genetically based slow-acetylator phenotype. Such genetic modulation of low-dose environmental risks is relevant to 'risk assessment' procedures. PMID:7909916

  4. Exogenous nerve growth factor stimulates choline acetyltransferase activity in aging Fischer 344 male rats.

    PubMed

    Williams, L R

    1991-01-01

    The effect of age and exogenous nerve growth factor (NGF) infusion on choline acetyltransferase (ChAT) specific activity is examined in microdissections of cerebral and hippocampal cortices, and the cholinergic nuclei of the medial septum and diagonal band of Broca (MS/DB), the nucleus basalis magnocellularis (NBM), and striatum of Fischer 344 male rats. Significant, 20% losses in ChAT activity are found in the MS/DB and striatum of 24-month-old rats (n = 21) compared to 4-month-old animals, but there is no apparent loss of enzyme activity in the NBM. Loss of ChAT activity in the MS/DB is only observed in animals older than 19 months of age, while a striatal deficit is found in animals older than 7 months. Treatment for 2 weeks with NGF at 1.2 micrograms/day results in significant 70% increases of ChAT activity in the MS/DB and striatum of 24-month-old rats compared to untreated and vehicle-treated 4-month-old rats, but does not stimulate activity in the NBM. Sensitivity of ChAT activity in the MS/DB and striatum to exogenous NGF increases with age. These experiments indicate that in the MS/DB, NBM, and striatum of Fischer 344 male rat there is an age-associated, differential regulation of ChAT enzyme activity and sensitivity to exogenous NGF.

  5. Effects of sex hormones, forskolin, and nicotine on choline acetyltransferase activity in human isolated placenta.

    PubMed

    Wessler, Ignaz; Schwarze, Sören; Brockerhoff, Peter; Bittinger, Fernando; Kirkpatrick, Charles James; Kilbinger, Heinz

    2003-04-01

    The activity of choline acetyltransferase (ChAT) was investigated in the human placenta before and after long-term incubation (24 h) to test the effects of sex hormones, nicotine and forskolin. ChAT activity differed considerably between the amnion (0.03 micromol/mg protein/h) and the villus (0.56). After long-term incubation, ChAT activity persisted in the latter but declined in the amnion. Neither sex hormones (beta-estradiol, testosterone, progesterone; 10 or 100 nM each) nor follicle stimulating hormone and luteinizing hormone (FSH/LH; 8.4 U/ml each) modified ChAT activity. Also nicotine (1 nM-100 microM) did not affect ChAT activity. Forskolin, an activitor of adenylyl cyclase, reduced ChAT activity in the villus but not in amnion. The present model offers the possibility to investigate ChAT regulation in intact tissue under long-term incubation. The risks of maternal smoking during pregnancy cannot be attributed to an effect of nicotine on placental ChAT activity. Differences in the regulation of ChAT appear to exist between neuronal and nonneuronal cells.

  6. Molecular Evolution of Aralkylamine N-Acetyltransferase in Fish: A Genomic Survey.

    PubMed

    Li, Jia; You, Xinxin; Bian, Chao; Yu, Hui; Coon, Steven L; Shi, Qiong

    2016-01-01

    All living organisms synchronize biological functions with environmental changes; melatonin plays a vital role in regulating daily and seasonal variations. Due to rhythmic activity of the timezyme aralkylamine N-acetyltransferase (AANAT), the blood level of melatonin increases at night and decreases during daytime. Whereas other vertebrates have a single form of AANAT, bony fishes possess various isoforms of aanat genes, though the reasons are still unclear. Here, we have taken advantage of multiple unpublished teleost aanat sequences to explore and expand our understanding of the molecular evolution of aanat in fish. Our results confirm that two rounds of whole-genome duplication (WGD) led to the existence of three fish isoforms of aanat, i.e., aanat1a, aanat1b, and aanat2; in addition, gene loss led to the absence of some forms from certain special fish species. Furthermore, we suggest the different roles of two aanat1s in amphibious mudskippers, and speculate that the loss of aanat1a, may be related to terrestrial vision change. Several important sites of AANAT proteins and regulatory elements of aanat genes were analyzed for structural comparison and functional forecasting, respectively, which provides insights into the molecular evolution of the differences between AANAT1 and AANAT2. PMID:26729109

  7. Human Neural Stem Cells Overexpressing Choline Acetyltransferase Restore Unconditioned Fear in Rats with Amygdala Injury.

    PubMed

    Shin, Kyungha; Cha, Yeseul; Kim, Kwang Sei; Choi, Ehn-Kyoung; Choi, Youngjin; Guo, Haiyu; Ban, Young-Hwan; Kim, Jong-Choon; Park, Dongsun; Kim, Yun-Bae

    2016-01-01

    Amygdala is involved in the fear memory that recognizes certain environmental cues predicting threatening events. Manipulation of neurotransmission within the amygdala affects the expression of conditioned and unconditioned emotional memories such as fear freezing behaviour. We previously demonstrated that F3.ChAT human neural stem cells (NSCs) overexpressing choline acetyltransferase (ChAT) improve cognitive function of Alzheimer's disease model rats with hippocampal or cholinergic nerve injuries by increasing acetylcholine (ACh) level. In the present study, we examined the effect of F3.ChAT cells on the deficit of unconditioned fear freezing. Rats given N-methyl-d-aspartate (NMDA) in their amygdala 2 weeks prior to cat odor exposure displayed very short resting (freezing) time compared to normal animals. NMDA induced neuronal degeneration in the amygdala, leading to a decreased ACh concentration in cerebrospinal fluid. However, intracerebroventricular transplantation of F3.ChAT cells attenuated amygdala lesions 4 weeks after transplantation. The transplanted cells were found in the NMDA-injury sites and produced ChAT protein. In addition, F3.ChAT-receiving rats recuperated freezing time staying remote from the cat odor source, according to the recovery of brain ACh concentration. The results indicate that human NSCs overexpressing ChAT may facilitate retrieval of unconditioned fear memory by increasing ACh level. PMID:27087745

  8. Molecular Evolution of Aralkylamine N-Acetyltransferase in Fish: A Genomic Survey.

    PubMed

    Li, Jia; You, Xinxin; Bian, Chao; Yu, Hui; Coon, Steven L; Shi, Qiong

    2015-12-31

    All living organisms synchronize biological functions with environmental changes; melatonin plays a vital role in regulating daily and seasonal variations. Due to rhythmic activity of the timezyme aralkylamine N-acetyltransferase (AANAT), the blood level of melatonin increases at night and decreases during daytime. Whereas other vertebrates have a single form of AANAT, bony fishes possess various isoforms of aanat genes, though the reasons are still unclear. Here, we have taken advantage of multiple unpublished teleost aanat sequences to explore and expand our understanding of the molecular evolution of aanat in fish. Our results confirm that two rounds of whole-genome duplication (WGD) led to the existence of three fish isoforms of aanat, i.e., aanat1a, aanat1b, and aanat2; in addition, gene loss led to the absence of some forms from certain special fish species. Furthermore, we suggest the different roles of two aanat1s in amphibious mudskippers, and speculate that the loss of aanat1a, may be related to terrestrial vision change. Several important sites of AANAT proteins and regulatory elements of aanat genes were analyzed for structural comparison and functional forecasting, respectively, which provides insights into the molecular evolution of the differences between AANAT1 and AANAT2.

  9. Mutant SOD1 impairs axonal transport of choline acetyltransferase and acetylcholine release by sequestering KAP3

    PubMed Central

    Tateno, Minako; Kato, Shinsuke; Sakurai, Takashi; Nukina, Nobuyuki; Takahashi, Ryosuke; Araki, Toshiyuki

    2009-01-01

    Mutations in the superoxide dismutase 1 (sod1) gene cause familial amyotrophic lateral sclerosis (FALS), likely due to the toxic properties of misfolded mutant SOD1 protein. Here we demonstrated that, starting from the pre-onset stage of FALS, misfolded SOD1 species associates specifically with kinesin-associated protein 3 (KAP3) in the ventral white matter of SOD1G93A-transgenic mouse spinal cord. KAP3 is a kinesin-2 subunit responsible for binding to cargos including choline acetyltransferase (ChAT). Motor axons in SOD1G93A-Tg mice also showed a reduction in ChAT transport from the pre-onset stage. By employing a novel FALS modeling system using NG108-15 cells, we showed that microtubule-dependent release of acetylcholine was significantly impaired by misfolded SOD1 species. Furthermore, such impairment was able to be normalized by KAP3 overexpression. KAP3 was incorporated into SOD1 aggregates in human FALS cases as well. These results suggest that KAP3 sequestration by misfolded SOD1 species and the resultant inhibition of ChAT transport play a role in the dysfunction of ALS. PMID:19088126

  10. Choline acetyltransferase in the hippocampus is associated with learning strategy preference in adult male rats.

    PubMed

    Hawley, Wayne R; Witty, Christine F; Daniel, Jill M; Dohanich, Gary P

    2015-08-01

    One principle of the multiple memory systems hypothesis posits that the hippocampus-based and striatum-based memory systems compete for control over learning. Consistent with this notion, previous research indicates that the cholinergic system of the hippocampus plays a role in modulating the preference for a hippocampus-based place learning strategy over a striatum-based stimulus--response learning strategy. Interestingly, in the hippocampus, greater activity and higher protein levels of choline acetyltransferase (ChAT), the enzyme that synthesizes acetylcholine, are associated with better performance on hippocampus-based learning and memory tasks. With this in mind, the primary aim of the current study was to determine if higher levels of ChAT and the high-affinity choline uptake transporter (CHT) in the hippocampus were associated with a preference for a hippocampus-based place learning strategy on a task that also could be solved by relying on a striatum-based stimulus--response learning strategy. Results confirmed that levels of ChAT in the dorsal region of the hippocampus were associated with a preference for a place learning strategy on a water maze task that could also be solved by adopting a stimulus-response learning strategy. Consistent with previous studies, the current results support the hypothesis that the cholinergic system of the hippocampus plays a role in balancing competition between memory systems that modulate learning strategy preference.

  11. Characterization of two metagenome-derived esterases that reactivate chloramphenicol by counteracting chloramphenicol acetyltransferase.

    PubMed

    Tao, Weixin; Lee, Myung Hwan; Yoon, Mi-Young; Kim, Jin-Cheol; Malhotra, Shweta; Wu, Jing; Hwang, Eul Chul; Lee, Seon-Woo

    2011-12-01

    Function-driven metagenomic analysis is a powerful approach to screening for novel biocatalysts. In this study, we investigated lipolytic enzymes selected from an alluvial soil metagenomic library, and identified two novel esterases, EstDL26 and EstDL136. EstDL26 and EstDL136 reactivated chloramphenicol from its acetyl derivates by counteracting the chloramphenicol acetyltransferase (CAT) activity in Escherichia coli. These two enzymes showed only 27% identity in amino acid sequence to each other; however both preferentially hydrolyzed short-chain p-nitrophenyl esters (< or =C5) and showed mesophilic properties. In vitro, EstDL136 catalyzed the deacetylation of 1- and 3- acetyl and 1,3-diacetyl derivates; in contrast, EstDL26 was not capable of the deacetylation at C1, indicating a potential regioselectivity. EstDL26 and EstDL136 were similar to microbial hormone-sensitive lipase (HSL), and since chloramphenicol acetate esterase (CAE) activity was detected from two other soil esterases in the HSL family, this suggests a distribution of CAE among the soil microorganisms. The isolation and characterization of EstDL26 and EstDL136 in this study may be helpful in understanding the diversity of CAE enzymes and their potential role in releasing active chloramphenicol in the producing bacteria. PMID:22210605

  12. Characterization of two acetyltransferase genes in the pyripyropene biosynthetic gene cluster from Penicillium coprobium

    PubMed Central

    Hu, Jie; Furutani, Ayako; Yamamoto, Kentaro; Oyama, Kazuhiko; Mitomi, Masaaki; Anzai, Hiroyuki

    2014-01-01

    Pyripyropenes potently and selectively inhibit acyl-CoA:cholesterol acyltransferase 2 (ACAT-2). Among multiple isomers of pyripyropene (A to R), pyripyropene A (PyA) has insecticidal properties in addition to its growth inhibition properties against human umbilical vein endothelial cells. Based on the predicted biosynthetic gene cluster of pyripyropene A, two genes (ppb8 and ppb9) encoding two acetyltransferases (ATs) were separately isolated and introduced into the model fungus Aspergillus oryzae, using the protoplast–polyethylene glycol method. The bioconversion of certain predicted intermediates in the transformants revealed the manner by which acetylation occurred in the biosynthetic pathway by the products expressed by these two genes (AT-1 and AT-2). The acetylated products detected by high-performance liquid chromatography (HPLC) in the extracts from AT-1 and AT-2 transformant clones were not present in the extract from the transformant clone with an empty vector. The HLPC charts of each bioconversion study exhibited high peaks at 12, 10.5 and 9 min, respectively. Further ultraviolet absorption and mass spectrometry analyses identified the products as PyE, PyO and PyA, respectively. AT-1 acetylated the C-1 of deacetyl-pyripyropene E (deAc-PyE), while AT-2 played an active role in acetylating the C-11 of 11-deAc-PyO and C-7 of deAc-PyA at two different steps of the biosynthetic pathway. PMID:26019565

  13. Purification of phosphinothricin acetyltransferase using Reactive brown 10 affinity in a single chromatography step.

    PubMed

    Wang, Cunxi; Lee, Thomas C; Crowley, Kathleen S; Bell, Erin

    2013-08-01

    The expression of phosphinothricin N-acetyltransferase (PAT) protein in transgenic plants confers tolerance to the herbicide glufosinate. To enable the characterization of PAT protein expressed in plants, it is necessary to obtain high purity PAT protein from the transgenic grain. Because transgenically expressed proteins are typical present at very low levels (i.e. 0.1-50 μg protein/g grain), a highly specific and efficient purification protocol is required to purify them. Based on the physicochemical properties of PAT, we developed a novel purification method that is simple, time-saving, inexpensive and reproducible. The novel method employs a single chromatography step using a reactive dye resin, Reactive brown 10-agarose. Reactive brown 10 preferentially binds the PAT protein, which can then be specifically released by one of its substrates, acetyl-CoA. Using Reactive brown 10-agarose, PAT protein was purified to homogeneity from cottonseed with high recovery efficiency. As expected, the Reactive brown 10-produced PAT was enzymatically active. Other applications of the method on protein expression and purification, and development of PAT enzymatic inhibitors were also discussed. PMID:23748142

  14. P300 acetyltransferase regulates fatty acid synthase expression, lipid metabolism and prostate cancer growth

    PubMed Central

    Zhong, Jian; Jiang, Kui; Pan, Yunqian; Karnes, R. Jeffrey; Zhang, Jun; Xu, Wanhai; Wang, Guixia; Huang, Haojie

    2016-01-01

    De novo fatty acid (FA) synthesis is required for prostate cancer (PCa) survival and progression. As a key enzyme for FA synthesis fatty acid synthase (FASN) is often overexpressed in human prostate cancers and its expression correlates with worse prognosis and poor survival. P300 is an acetyltransferase that acts as a transcription co-activator. Increasing evidence suggests that P300 is a major PCa promoter, although the underlying mechanism remains poorly understood. Here, we demonstrated that P300 binds to and increases histone H3 lysine 27 acetylation (H3K27Ac) in the FASN gene promoter. We provided evidence that P300 transcriptionally upregulates FASN expression and promotes lipid accumulation in human PCa cells in culture and Pten knockout prostate tumors in mice. Pharmacological inhibition of P300 decreased FASN expression and lipid droplet accumulation in PCa cells. Immunohistochemistry analysis revealed that expression of P300 protein positively correlates with FASN protein levels in a cohort of human PCa specimens. We further showed that FASN is a key mediator of P300-induced growth of PCa cells in culture and in mice. Together, our findings demonstrate P300 as a key factor that regulates FASN expression, lipid accumulation and cell growth in PCa. They also suggest that this regulatory pathway can serve as a new therapeutic target for PCa treatment. PMID:26934656

  15. Mechanistic and Structural Analysis of Drosophila melanogaster Arylalkylamine N-Acetyltransferases

    PubMed Central

    2015-01-01

    Arylalkylamine N-acetyltransferase (AANAT) catalyzes the penultimate step in the biosynthesis of melatonin and other N-acetylarylalkylamides from the corresponding arylalkylamine and acetyl-CoA. The N-acetylation of arylalkylamines is a critical step in Drosophila melanogaster for the inactivation of the bioactive amines and the sclerotization of the cuticle. Two AANAT variants (AANATA and AANATB) have been identified in D. melanogaster, in which AANATA differs from AANATB by the truncation of 35 amino acids from the N-terminus. We have expressed and purified both D. melanogaster AANAT variants (AANATA and AANATB) in Escherichia coli and used the purified enzymes to demonstrate that this N-terminal truncation does not affect the activity of the enzyme. Subsequent characterization of the kinetic and chemical mechanism of AANATA identified an ordered sequential mechanism, with acetyl-CoA binding first, followed by tyramine. We used a combination of pH–activity profiling and site-directed mutagenesis to study prospective residues believed to function in AANATA catalysis. These data led to an assignment of Glu-47 as the general base in catalysis with an apparent pKa of 7.0. Using the data generated for the kinetic mechanism, structure–function relationships, pH–rate profiles, and site-directed mutagenesis, we propose a chemical mechanism for AANATA. PMID:25406072

  16. Arylalkylamine N-acetyltransferase (AANAT) genotype as a personal trait in melatonin synthesis.

    PubMed

    Blomeke, Brunhilde; Golka, Klaus; Griefahn, Barbara; Roemer, Hermann C

    2008-01-01

    The melatonin rhythm is arguably the best marker for the phase of the endogenous "biological clock." Arylalkylamine N-acetyltransferase (AANAT) is known to catalyze the acetylation of serotonin, a rate-limiting process in melatonin synthesis. Different single-nucleotide polymorphisms (SNPs) in the AANAT gene were identified recently in the Japanese population, and one of the genes was significantly associated with the delayed sleep phase syndrome. Thus, 54 healthy Caucasian males were genotyped to investigate whether these SNPs in the AANAT gene affected melatonin levels. The endogenous melatonin levels were analyzed in saliva under standardized experimental conditions ("constant routines") by radioimmunoassay. Despite the broad temporal variation of the human nocturnal melatonin profiles, none of the investigated SNPs were found in the AANAT gene in this study. These findings point to ethnic differences with respect to these SNPs, rather than time of day termed "morningness." In summary, SNPs in the AANAT gene identified thus far cannot explain the observed interindividual differences for nocturnal melatonin profiles in the subjects investigated.

  17. Identification and validation of N-acetyltransferase 2 as an insulin sensitivity gene.

    PubMed

    Knowles, Joshua W; Xie, Weijia; Zhang, Zhongyang; Chennamsetty, Indumathi; Chennemsetty, Indumathi; Assimes, Themistocles L; Paananen, Jussi; Hansson, Ola; Pankow, James; Goodarzi, Mark O; Carcamo-Orive, Ivan; Morris, Andrew P; Chen, Yii-Der I; Mäkinen, Ville-Petteri; Ganna, Andrea; Mahajan, Anubha; Guo, Xiuqing; Abbasi, Fahim; Greenawalt, Danielle M; Lum, Pek; Molony, Cliona; Lind, Lars; Lindgren, Cecilia; Raffel, Leslie J; Tsao, Philip S; Schadt, Eric E; Rotter, Jerome I; Sinaiko, Alan; Reaven, Gerald; Yang, Xia; Hsiung, Chao A; Groop, Leif; Cordell, Heather J; Laakso, Markku; Hao, Ke; Ingelsson, Erik; Frayling, Timothy M; Weedon, Michael N; Walker, Mark; Quertermous, Thomas

    2015-04-01

    Decreased insulin sensitivity, also referred to as insulin resistance (IR), is a fundamental abnormality in patients with type 2 diabetes and a risk factor for cardiovascular disease. While IR predisposition is heritable, the genetic basis remains largely unknown. The GENEticS of Insulin Sensitivity consortium conducted a genome-wide association study (GWAS) for direct measures of insulin sensitivity, such as euglycemic clamp or insulin suppression test, in 2,764 European individuals, with replication in an additional 2,860 individuals. The presence of a nonsynonymous variant of N-acetyltransferase 2 (NAT2) [rs1208 (803A>G, K268R)] was strongly associated with decreased insulin sensitivity that was independent of BMI. The rs1208 "A" allele was nominally associated with IR-related traits, including increased fasting glucose, hemoglobin A1C, total and LDL cholesterol, triglycerides, and coronary artery disease. NAT2 acetylates arylamine and hydrazine drugs and carcinogens, but predicted acetylator NAT2 phenotypes were not associated with insulin sensitivity. In a murine adipocyte cell line, silencing of NAT2 ortholog Nat1 decreased insulin-mediated glucose uptake, increased basal and isoproterenol-stimulated lipolysis, and decreased adipocyte differentiation, while Nat1 overexpression produced opposite effects. Nat1-deficient mice had elevations in fasting blood glucose, insulin, and triglycerides and decreased insulin sensitivity, as measured by glucose and insulin tolerance tests, with intermediate effects in Nat1 heterozygote mice. Our results support a role for NAT2 in insulin sensitivity.

  18. Identification and validation of N-acetyltransferase 2 as an insulin sensitivity gene

    PubMed Central

    Knowles, Joshua W.; Xie, Weijia; Zhang, Zhongyang; Chennemsetty, Indumathi; Assimes, Themistocles L.; Paananen, Jussi; Hansson, Ola; Pankow, James; Goodarzi, Mark O.; Carcamo-Orive, Ivan; Morris, Andrew P.; Chen, Yii-Der I.; Mäkinen, Ville-Petteri; Ganna, Andrea; Mahajan, Anubha; Guo, Xiuqing; Abbasi, Fahim; Greenawalt, Danielle M.; Lum, Pek; Molony, Cliona; Lind, Lars; Lindgren, Cecilia; Raffel, Leslie J.; Tsao, Philip S.; Schadt, Eric E.; Rotter, Jerome I.; Sinaiko, Alan; Reaven, Gerald; Yang, Xia; Hsiung, Chao A.; Groop, Leif; Cordell, Heather J.; Laakso, Markku; Hao, Ke; Ingelsson, Erik; Frayling, Timothy M.; Weedon, Michael N.; Walker, Mark; Quertermous, Thomas

    2015-01-01

    Decreased insulin sensitivity, also referred to as insulin resistance (IR), is a fundamental abnormality in patients with type 2 diabetes and a risk factor for cardiovascular disease. While IR predisposition is heritable, the genetic basis remains largely unknown. The GENEticS of Insulin Sensitivity consortium conducted a genome-wide association study (GWAS) for direct measures of insulin sensitivity, such as euglycemic clamp or insulin suppression test, in 2,764 European individuals, with replication in an additional 2,860 individuals. The presence of a nonsynonymous variant of N-acetyltransferase 2 (NAT2) [rs1208 (803A>G, K268R)] was strongly associated with decreased insulin sensitivity that was independent of BMI. The rs1208 “A” allele was nominally associated with IR-related traits, including increased fasting glucose, hemoglobin A1C, total and LDL cholesterol, triglycerides, and coronary artery disease. NAT2 acetylates arylamine and hydrazine drugs and carcinogens, but predicted acetylator NAT2 phenotypes were not associated with insulin sensitivity. In a murine adipocyte cell line, silencing of NAT2 ortholog Nat1 decreased insulin-mediated glucose uptake, increased basal and isoproterenol-stimulated lipolysis, and decreased adipocyte differentiation, while Nat1 overexpression produced opposite effects. Nat1-deficient mice had elevations in fasting blood glucose, insulin, and triglycerides and decreased insulin sensitivity, as measured by glucose and insulin tolerance tests, with intermediate effects in Nat1 heterozygote mice. Our results support a role for NAT2 in insulin sensitivity. PMID:25798622

  19. N-acetyltransferase 2 genetic polymorphism: Effects of carcinogen and haplotype on urinary bladder cancer risk

    PubMed Central

    Hein, David W.

    2006-01-01

    A role for the N-acetyltransferase 2 (NAT2) genetic polymorphism in cancer risk has been the subject of numerous studies. Although comprehensive reviews of the NAT2 acetylation polymorphism have been published elsewhere, the objective of this paper is to briefly highlight some important features of the NAT2 acetylation polymorphism that are not universally accepted to better understand the role of NAT2 polymorphism in carcinogenic risk assessment. NAT2 slow acetylator phenotype(s) infer a consistent and robust increase in urinary bladder cancer risk following exposures to aromatic amine carcinogens. However, identification of specific carcinogens is important as the effect of NAT2 polymorphism on urinary bladder cancer differs dramatically between monoarylamines and aryldiamines. Misclassifications of carcinogen exposure and NAT2 genotype/phenotype confound evidence for a real biological effect. Functional understanding of the effects of NAT2 genetic polymorphisms on metabolism and genotoxicity, tissue-specific expression and the elucidation of the molecular mechanisms responsible are critical for interpretation of previous and future human molecular epidemiology investigations into the role of NAT2 polymorphism on cancer risk. Although associations have been reported for various cancers, this paper focuses on urinary bladder cancer, a cancer in which a role for NAT2 polymorphism was first proposed and for which evidence is accumulating that the effect is biologically significant with important public health implications. PMID:16550165

  20. N-Acetyltransferase 2 genotype, exfoliated urothelial cells and benzidine exposure.

    PubMed

    Ma, Qing-wen; Lin, Guo-fang; Chen, Ji-gang; Guo, Wei-Chao; Qin, Yi-qiu; Golka, Klaus; Shen, Jian-hua

    2012-01-01

    Most studies report an association of the slow N-acetyltransferase 2 (NAT2) status with elevated bladder cancer risk. In this study, NAT2 genotypes and the decades-long records of Papanicolaou's grading of exfoliated urothelial cells in a former benzidine-exposed cohort of the Shanghai dyestuff industry (29 bladder cancer patients; 307 non-cancer cohort members, some of them presenting different grades of pre-malignant alterations of exfoliated urothelial cells) were investigated. The cohort members had been enrolled in regular medical surveillance since mid-1980s. No overall increase of slow NAT2 genotypes in the former benzidine-exposed bladder cancer patients was found, compared with non-diseased members of the same cohort. A lower presentation of the homozygous wild genotype NAT2 4/4 was observed in bladder cancer patients, compared with non-diseased members with averaged Papanicolaou's grading (APG)3 II (OR=0.31, 95 percent CI 0.10-0.96, p=0.034) or with APG less than II (OR=0.36,95 percent CI 0.12-1.10, p=0.063). Nevertheless, neither a protective influence of rapid NAT2 genotypes on bladder cancer risk nor on pre-malignant cytological alterations could be confirmed by the present data.

  1. A chromosomal chloramphenicol acetyltransferase determinant from a probiotic strain of Bacillus clausii.

    PubMed

    Galopin, Sébastien; Cattoir, Vincent; Leclercq, Roland

    2009-06-01

    The mechanism of resistance to chloramphenicol was studied in four strains of Bacillus clausii included in a probiotic mixture, which is administered to humans for prevention of gastrointestinal side effects due to oral antibiotic therapy. By cloning experiments, a chloramphenicol acetyltransferase (CAT) gene, cat(Bcl), coding for a putative 228-amino acid CAT protein was identified in B. clausii SIN. The deduced amino acid sequence displayed from 31% to 85% identity with 56 CAT proteins from other Gram-positive bacterial strains. The cat(Bcl) gene was also detected by PCR in the three other B. clausii strains resistant to chloramphenicol, whereas it was absent in the three control strains susceptible to chloramphenicol. Pulse-field gel electrophoresis of total DNA digested by I-CeuI followed by hybridization with a cat-specific probe as well as unsuccessful repeated attempts of in vitro transfer of chloramphenicol resistance to various recipient cells indicated that cat(Bcl) was chromosomally located in all four resistant B. clausii strains. PMID:19459958

  2. A pentanuclear lead(II) complex based on a strapped porphyrin with three different coordination modes.

    PubMed

    Le Gac, Stéphane; Furet, Eric; Roisnel, Thierry; Hijazi, Ismail; Halet, Jean-François; Boitrel, Bernard

    2014-10-01

    We have previously described Pb(II) and Bi(III) bimetallic complexes with overhanging carboxylic acid strapped porphyrins in which one metal ion is bound to the N-core ("out-of-plane", OOP), whereas the second one is bound to the strap ("hanging-atop", HAT). In such complexes, the hemidirected coordination sphere of a HAT Pb(II) cation provides sufficient space for an additional binding of a neutral ligand (e.g., DMSO). Interestingly, investigations of the HAT metal coordination mode in a single strap porphyrin show that a HAT Pb(II) can also interact via intermolecular coordination bonds, allowing the self-assembly of two bimetallic complexes. In the pentanuclear Pb(II) complex we are describing in this Article, three different coordination modes were found. The OOP Pb(II) remains inert toward the supramolecular assembling process, whereas the HAT Pb(II) cation, in addition to its intramolecular carboxylate and regular exogenous acetate groups, coordinates an additional exogenous acetate. These two acetates are shared with a third lead(II) cation featuring a holo-directed coordination sphere, from which a centro-symmetric complex is assembled. Density functional theory calculations show some electron-density pockets in the vicinity of the hemidirected HAT Pb(II) atoms, which are associated with the presence of a stereochemically active lone pair of electrons. On the basis of the comparison with other HAT Pb(II) and Bi(III) systems, the "volume" of this lone pair correlates well with the bond distance distributions and the number of the proximal oxygen atoms tethered to the post-transition metal cation. It thus follows the order 6-coordinate Bi(III) > 6-coordinate Pb(II) > 5-coordinate Pb(II).

  3. A near-infrared transmission spectrum for the warm Saturn HAT-P-12b

    SciTech Connect

    Line, Michael R.; Knutson, Heather; Desert, Jean-Michel; Deming, Drake; Wilkins, Ashlee

    2013-12-01

    We present a Hubble Space Telescope Wide Field Camera-3 (WFC3) transmission spectrum for the transiting exoplanet HAT-P-12b. This warm (1000 K) sub-Saturn-mass planet has a smaller mass and a lower temperature than the hot Jupiters that have been studied so far. We find that the planet's measured transmission spectrum lacks the expected water absorption feature for a hydrogen-dominated atmosphere and is instead best described by a model with high-altitude clouds. Using a frequentist hypothesis testing procedure, we can rule out a hydrogen-dominated cloud-free atmosphere to 4.9σ. When combined with other recent WFC3 studies, our observations suggest that clouds may be common in exoplanetary atmospheres.

  4. Single-strain-gage force/stiffness buckling prediction techniques on a hat-stiffened panel

    NASA Technical Reports Server (NTRS)

    Hudson, Larry D.; Thompson, Randolph C.

    1991-01-01

    Predicting the buckling characteristics of a test panel is necessary to ensure panel integrity during a test program. A single-strain-gage buckling prediction method was developed on a hat-stiffened, monolithic titanium buckling panel. The method is an adaptation of the original force/stiffness method which requires back-to-back gages. The single-gage method was developed because the test panel did not have back-to-back gages. The method was used to predict buckling loads and temperatures under various heating and loading conditions. The results correlated well with a finite element buckling analysis. The single-gage force/stiffness method was a valid real-time and post-test buckling prediction technique.

  5. Viscous Chaplygin gas models as spherical top-hat collapsing fluids

    NASA Astrophysics Data System (ADS)

    Jawad, Abdul; Iqbal, Ayesha

    2016-05-01

    We study the spherical top-hat collapse in Einstein gravity and loop quantum cosmology (LQC) by taking the nonlinear evolution of viscous modified variable Chaplygin gas (CG) and viscous generalized cosmic chaplygin gas (GCCG). We calculate the equation of state (EoS) parameter, square speed of sound, perturbed (EoS) parameter, perturbed square speed of sound, density contrast and divergence of peculiar velocity in perturbed region and discussed their behavior. It is observed that both CG models support the spherical collapse (SC) in Einstein as well as LQC because density contrast remains positive in both cases and the perturbed EoS parameter remains positive at the present epoch as well as near future. It is remarked here that these parameters provide consistent results for both CG models in both gravities.

  6. Self-assembled ordered structures in thin films of HAT5 discotic liquid crystal

    PubMed Central

    Morales, Piero; Lagerwall, Jan; Vacca, Paolo; Laschat, Sabine

    2010-01-01

    Summary Thin films of the discotic liquid crystal hexapentyloxytriphenylene (HAT5), prepared from solution via casting or spin-coating, were investigated by atomic force microscopy and polarizing optical microscopy, revealing large-scale ordered structures substantially different from those typically observed in standard samples of the same material. Thin and very long fibrils of planar-aligned liquid crystal were found, possibly formed as a result of an intermediate lyotropic nematic state arising during the solvent evaporation process. Moreover, in sufficiently thin films the crystallization seems to be suppressed, extending the uniform order of the liquid crystal phase down to room temperature. This should be compared to the bulk situation, where the same material crystallizes into a polymorphic structure at 68 °C. PMID:20625522

  7. Simulated response of top-hat electrostatic analysers - importance of phase-space resolution

    NASA Astrophysics Data System (ADS)

    De Marco, Rossana; Bruno, Roberto; D'Amicis, Raffaella; Federica Marcucci, Maria; Servidio, Sergio; Valentini, Francesco

    2016-04-01

    We use a numerical code able to reproduce the angular/energy response of a typical electrostatic analyzer of top-hat type starting from velocity distribution functions (VDFs) generated by numerical imulations.The simulations are based on the Hybrid Vlasov-Maxwell (HVM) numerical algorithm which integrates the Vlasov equation for the ion distribution function in multi-dimensional geometry in phase space, while the electrons are treated as a fluid. Virtual satellites launched through the simulation box measure the particle VDFs. Such VDFs are interpolated into a spacecraft reference frame and moved from the simulation Cartesian grid to energy-angular coordinates to mimic the response of a real electrostatic sensor in the solar wind and in the magnetosheath for different conditions. We discuss the results of this study with respect to the importance of phase-space resolution for a space plasma experiment meant to investigate kinetic plasma regime.

  8. THE DISCOVERY OF ELLIPSOIDAL VARIATIONS IN THE KEPLER LIGHT CURVE OF HAT-P-7

    SciTech Connect

    Welsh, William F.; Orosz, Jerome A.; Seager, Sara; Fortney, Jonathan J.; Jenkins, Jon; Rowe, Jason F.; Koch, David; Borucki, William J.

    2010-04-20

    We present an analysis of the early Kepler observations of the previously discovered transiting planet HAT-P-7b. The light curve shows the transit of the star, the occultation of the planet, and the orbit phase-dependent light from the planet. In addition, phase-dependent light from the star is present, known as 'ellipsoidal variations'. The very nearby planet (only four stellar radii away) gravitationally distorts the star and results in a flux modulation twice per orbit. The ellipsoidal variations can confuse interpretation of the planetary phase curve if not self-consistently included in the modeling. We fit the light curve using the Roche potential approximation and derive improved planet and orbit parameters.

  9. An Overview of HATS: A Language Independent High Assurance Transformation System

    SciTech Connect

    Winter, V.L.

    1998-10-16

    Transformations that are based on syntax directed rewriting systems can have a significant impact on the construction of high assurance systems. However, in order for a transformational approach to be useful to a particular problem domain, a (general) transformation system must be adapted to the notation of that particular domain. A transformation system that can be easily adapted to various domain notations has the potential of having a wide range of applicability. In this paper we dissus why transforrmtion is attractive horn a high assurance perspective, as well as some issues surrounding automated transformation within specific problem domains. We then give an overview of a language independent High Assurance Transformation System (HATS) that is being developed at Sandia National Laboratories.

  10. Automatic nuclear bud detection using ellipse fitting, moving sticks or top-hat transformation.

    PubMed

    Zhang, C; Sun, C; Vallotton, P; Fenech, M; Pham, T D

    2013-11-01

    Micronucleus assays are extensively used by biologists to assess genotoxicity and to monitor human exposure to genotoxic materials. As recent studies suggested that nuclear buds can be a new source of micronuclei formed in interphase, the quantification of nuclear buds, which are micronucleus like objects that are attached to the nuclei in interphase, in normal and control group is needed. Three automatic nuclear bud detection algorithms fit for different situations are proposed in this paper. One is based on ellipse fitting, one is based on a stick model and the other is based on the top-hat transform. Comparison of the three methods is also given in this paper. Experimental results showed that the proposed algorithms are all effective and efficient for nuclear bud detection. PMID:23961938

  11. "It's your badge of inclusion": the Red Hat Society as a gendered subculture of aging.

    PubMed

    Barrett, Anne E; Pai, Manacy; Redmond, Rebecca

    2012-12-01

    Although studies document the health-enhancing effects of social engagement, they reveal little about the underlying mechanisms operating within specific organizational contexts. Limited attention is given to the role of inequality--particularly age and gender--in shaping either the organizations to which we belong or their consequences for our well-being. We address this issue by examining the Red Hat Society, a social organization for middle-aged and older women. Interviews with members (n=52) illustrate how age and gender inequality interact to shape the organization, which can be viewed as a gendered subculture of aging. Drawing on this framework, we discuss four processes through which participation generates benefits for older women involved in age- and gender-segregated organizations: enhancing social networks, countering invisibility, creating positive frames for aging experiences, and promoting youthful identities.

  12. All or nothing... or just a hat? Farmers' sun protection behaviors.

    PubMed

    Silk, Kami J; Parrott, Roxanne L

    2006-04-01

    Farmers have an increased risk for developing skin cancers and thus comprise an important audience for messages that address sun protection practices. This project examines sun protection behaviors of farmers from southeastern Georgia and uses those measured behaviors to conduct a cluster analysis. Farmers (N = 480) were clustered into three groups using six variables that measured their frequency of sun protective and purchasing behaviors. The three groups were characterized as either engaging heavily in sun protective behaviors, engaging in none of the recommended sun protective behaviors, or only wearing hats as a sun protective behavior. Practitioners seeking to develop health message interventions that target farming populations should consider the current behaviors of subgroups of farmers when developing audience segments to tailor messages aimed at increasing sun protective behaviors. Practical recommendations for message content targeted toward the subgroups of farmers are provided.

  13. The Effect of Six Thinking Hats on Student Success in Teaching Subjects Related to Sustainable Development in Geography Classes

    ERIC Educational Resources Information Center

    Kaya, Mehmet Fatih

    2013-01-01

    This study aimed to assess the effectiveness of six thinking hats technique in teaching subjects related to sustainable development in geography classes. The study was in both a quantitative and qualitative form. The quantitative part of the study was designed according to pre-test, post-test control group research model, and in the qualitative…

  14. Survey of sugar beet (Beta vulgaris L.) hAT transposons and MITE-like hATpin derivatives.

    PubMed

    Menzel, Gerhard; Krebs, Carmen; Diez, Mercedes; Holtgräwe, Daniela; Weisshaar, Bernd; Minoche, André E; Dohm, Juliane C; Himmelbauer, Heinz; Schmidt, Thomas

    2012-03-01

    Genome-wide analyses of repetitive DNA suggest a significant impact particularly of transposable elements on genome size and evolution of virtually all eukaryotic organisms. In this study, we analyzed the abundance and diversity of the hAT transposon superfamily of the sugar beet (B. vulgaris) genome, using molecular, bioinformatic and cytogenetic approaches. We identified 81 transposase-coding sequences, three of which are part of structurally intact but nonfunctional hAT transposons (BvhAT), in a B. vulgaris BAC library as well as in whole genome sequencing-derived data sets. Additionally, 116 complete and 497 truncated non-autonomous BvhAT derivatives lacking the transposase gene were in silico-detected. The 116 complete derivatives were subdivided into four BvhATpin groups each characterized by a distinct terminal inverted repeat motif. Both BvhAT and BvhATpin transposons are specific for species of the genus Beta and closely related species, showing a localization on B. vulgaris chromosomes predominantely in euchromatic regions. The lack of any BvhAT transposase function together with the high degree of degeneration observed for the BvhAT and the BvhATpin genomic fraction contrasts with the abundance and activity of autonomous and non-autonomous hAT transposons revealed in other plant species. This indicates a possible genus-specific structural and functional repression of the hAT transposon superfamily during Beta diversification and evolution.

  15. SPITZER IRAC SECONDARY ECLIPSE PHOTOMETRY OF THE TRANSITING EXTRASOLAR PLANET HAT-P-1b

    SciTech Connect

    Todorov, Kamen; Deming, Drake; Harrington, Jospeph; Stevenson, Kevin B.; Bowman, William C.; Nymeyer, Sarah; Fortney, Jonathan J.; Bakos, Gaspar A.

    2010-01-01

    We report Spitzer/IRAC photometry of the transiting giant exoplanet HAT-P-1b during its secondary eclipse. This planet lies near the postulated boundary between the pM and pL-class of hot Jupiters, and is important as a test of models for temperature inversions in hot Jupiter atmospheres. We derive eclipse depths for HAT-P-1b, in units of the stellar flux, that are: 0.080% +- 0.008% [3.6 mum], 0.135% +- 0.022% [4.5 mum], 0.203% +- 0.031% [5.8 mum], and 0.238% +- 0.040% [8.0 mum]. These values are best fit using an atmosphere with a modest temperature inversion, intermediate between the archetype inverted atmosphere (HD 209458b) and a model without an inversion. The observations also suggest that this planet is radiating a large fraction of the available stellar irradiance on its dayside, with little available for redistribution by circulation. This planet has sometimes been speculated to be inflated by tidal dissipation, based on its large radius in discovery observations, and on a non-zero orbital eccentricity allowed by the radial velocity data. The timing of the secondary eclipse is very sensitive to orbital eccentricity, and we find that the central phase of the eclipse is 0.4999 +- 0.0005. The difference between the expected and observed phase indicates that the orbit is close to circular, with a 3sigma limit of |e cos omega| < 0.002.

  16. Pharmacogenetic Association of Hypertension Candidate Genes with Fasting Glucose in the GenHAT Study

    PubMed Central

    Irvin, Marguerite R.; Lynch, Amy I.; Kabagambe, Edmond K.; Tiwari, Hemant K.; Barzilay, Joshua I.; Eckfeldt, John H.; Boerwinkle, Eric; Davis, Barry R.; Ford, Charles E.; Arnett, Donna K.

    2010-01-01

    Several clinical studies report increased risk of diabetes mellitus (DM) with pharmacologic treatment for hypertension (HTN). HTN genes may modify glycemic response to antihypertensive treatment. The current study examined the association of 24 single nucleotide polymorphisms (SNPs) in 11 HTN candidate genes with fasting glucose measured at 2, 4, and 6 years after treatment initiation. The study sample included participants free of diabetes at baseline in the Genetics of Hypertension Associated Treatment (GenHAT) study (N=9,309). GenHAT participants were randomized to receive treatment with a diuretic (chlorthalidone), calcium channel blocker (amlodipine), or ACE inhibitor (lisinopril). Mixed models for repeated measures were employed to test for gene and pharmacogenetic associations with fasting glucose during follow-up. Fasting glucose at year 2 increased on average 6.8 mg/dL, 4.8 mg/dL and 3.0 mg/dL from baseline in the chlorthalidone, amlodipine and lisinopril groups, respectively. Carrying the I allele (rs1799752) of the angiotensin-converting enzyme (ACE) I/D polymorphism was associated with lower fasting glucose levels (P=0.02). Additionally, an ACE promoter polymorphism (−262, rs4291) was associated with lower fasting glucose for the model AA/AT vs. TT which remained significant after correction for multiple testing (P=0.001). Finally, a SNP in the α-subunit of the amiloride-sensitive epithelial sodium channel (SCNN1A, rs2228576) modified the association of amlodipine versus chlorthalidone treatment with fasting glucose (P<0.001). Further examination of these genes and their relationships with cardiometabolic disease could foster development of pharmacogenetic guidelines aimed to prevent increases in fasting glucose during antihypertensive treatment. PMID:20577119

  17. Kepler and Ground-Based Transits of the exo-Neptune HAT-P-11b

    NASA Technical Reports Server (NTRS)

    Deming, Drake; Sada, Pedro V.; Jackson, Brian; Peterson, Steven W.; Agol, Eric; Knutson, Heather A.; Jennings, Donald E.; Haase, Plynn; Bays, Kevin

    2011-01-01

    We analyze 26 archival Kepler transits of the exo-Neptune HAT-P-11b, supplemented by ground-based transits observed in the blue (B band) and near-IR (J band). Both the planet and host star are smaller than previously believed; our analysis yields Rp = 4.31 R xor 0.06 R xor and Rs = 0.683 R solar mass 0.009 R solar mass, both about 3 sigma smaller than the discovery values. Our ground-based transit data at wavelengths bracketing the Kepler bandpass serve to check the wavelength dependence of stellar limb darkening, and the J-band transit provides a precise and independent constraint on the transit duration. Both the limb darkening and transit duration from our ground-based data are consistent with the new Kepler values for the system parameters. Our smaller radius for the planet implies that its gaseous envelope can be less extensive than previously believed, being very similar to the H-He envelope of GJ 436b and Kepler-4b. HAT-P-11 is an active star, and signatures of star spot crossings are ubiquitous in the Kepler transit data. We develop and apply a methodology to correct the planetary radius for the presence of both crossed and uncrossed star spots. Star spot crossings are concentrated at phases 0.002 and +0.006. This is consistent with inferences from Rossiter-McLaughlin measurements that the planet transits nearly perpendicular to the stellar equator. We identify the dominant phases of star spot crossings with active latitudes on the star, and infer that the stellar rotational pole is inclined at about 12 deg 5 deg to the plane of the sky. We point out that precise transit measurements over long durations could in principle allow us to construct a stellar Butterfly diagram to probe the cyclic evolution of magnetic activity on this active K-dwarf star.

  18. HATS-3b: An Inflated Hot Jupiter Transiting an F-type Star

    NASA Astrophysics Data System (ADS)

    Bayliss, D.; Zhou, G.; Penev, K.; Bakos, G. Á.; Hartman, J. D.; Jordán, A.; Mancini, L.; Mohler-Fischer, M.; Suc, V.; Rabus, M.; Béky, B.; Csubry, Z.; Buchhave, L.; Henning, T.; Nikolov, N.; Csák, B.; Brahm, R.; Espinoza, N.; Noyes, R. W.; Schmidt, B.; Conroy, P.; Wright, D. J.; Tinney, C. G.; Addison, B. C.; Sackett, P. D.; Sasselov, D. D.; Lázár, J.; Papp, I.; Sári, P.

    2013-11-01

    We report the discovery by the HATSouth survey of HATS-3b, a transiting extrasolar planet orbiting a V = 12.4 F dwarf star. HATS-3b has a period of P = 3.5479 days, mass of Mp = 1.07 M J, and radius of Rp = 1.38 R J. Given the radius of the planet, the brightness of the host star, and the stellar rotational velocity (vsin i = 9.0 km s-1), this system will make an interesting target for future observations to measure the Rossiter-McLaughlin effect and determine its spin-orbit alignment. We detail the low-/medium-resolution reconnaissance spectroscopy that we are now using to deal with large numbers of transiting planet candidates produced by the HATSouth survey. We show that this important step in discovering planets produces log g and T eff parameters at a precision suitable for efficient candidate vetting, as well as efficiently identifying stellar mass eclipsing binaries with radial velocity semi-amplitudes as low as 1 km s-1. The HATSouth network is operated by a collaboration consisting of Princeton University (PU), the Max Planck Institute für Astronomie (MPIA), and the Australian National University (ANU). The station at Las Campanas Observatory (LCO) of the Carnegie Institute is operated by PU in conjunction with collaborators at the Pontificia Universidad Católica de Chile (PUC), the station at the High Energy Spectroscopic Survey (HESS) site is operated in conjunction with MPIA, and the station at Siding Spring Observatory (SSO) is operated jointly with ANU.

  19. Random complex dynamics and devil's coliseums

    NASA Astrophysics Data System (ADS)

    Sumi, Hiroki

    2015-04-01

    We investigate the random dynamics of polynomial maps on the Riemann sphere \\hat{\\Bbb{C}} and the dynamics of semigroups of polynomial maps on \\hat{\\Bbb{C}} . In particular, the dynamics of a semigroup G of polynomials whose planar postcritical set is bounded and the associated random dynamics are studied. In general, the Julia set of such a G may be disconnected. We show that if G is such a semigroup, then regarding the associated random dynamics, the chaos of the averaged system disappears in the C0 sense, and the function T∞ of probability of tending to ∞ \\in \\hat{\\Bbb{C}} is Hölder continuous on \\hat{\\Bbb{C}} and varies only on the Julia set of G. Moreover, the function T∞ has a kind of monotonicity. It turns out that T∞ is a complex analogue of the devil's staircase, and we call T∞ a ‘devil’s coliseum'. We investigate the details of T∞ when G is generated by two polynomials. In this case, T∞ varies precisely on the Julia set of G, which is a thin fractal set. Moreover, under this condition, we investigate the pointwise Hölder exponents of T∞.

  20. Mechanistic and Structural Analysis of Aminoglycoside N-Acetyltransferase AAC(6′)-Ib and Its Bifunctional, Fluoroquinolone-Active AAC(6′)-Ib-cr Variant†,‡

    PubMed Central

    Vetting, Matthew W.; Park, Chi Hye; Hegde, Subray S.; Jacoby, George A.; Hooper, David C.; Blanchard, John S.

    2010-01-01

    Enzymatic modification of aminoglycoside antibiotics mediated by regioselective aminoglycoside N-acetyltransferases is the predominant cause of bacterial resistance to aminoglycosides. A recently discovered bifunctional aminoglycoside acetyltransferase (AAC(6′)-Ib variant, AAC(6′)-Ib-cr) has been shown to catalyze the acetylation of fluoroquinolones as well as aminoglycosides. We have expressed and purified AAC(6′)-Ib-wt and its bifunctional variant AAC(6′)-Ib-cr in Escherichia coli and characterized their kinetic and chemical mechanism. Initial velocity and dead-end inhibition studies support an ordered sequential mechanism for the enzyme(s). The three-dimensional structure of AAC(6′)-Ib-wt was determined in various complexes with donor and acceptor ligands to resolutions greater than 2.2 Å. Observation of the direct, and optimally positioned, interaction between the 6′-NH2 and Asp115 suggests that Asp115 acts as a general base to accept a proton in the reaction. The structure of AAC(6′)-Ib-wt permits the construction of a molecular model of the interactions of fluoroquinolones with the AAC(6′)-Ib-cr variant. The model suggests that a major contribution to the fluoroquinolone acetylation activity comes from the Asp179Tyr mutation, where Tyr179 makes π-stacking interactions with the quinolone ring facilitating quinolone binding. The model also suggests that fluoroquinolones and aminoglycosides have different binding modes. On the basis of kinetic properties, the pH dependence of the kinetic parameters, and structural information, we propose an acid/base-assisted reaction catalyzed by AAC(6′)-Ib-wt and the AAC(6′)-Ib-cr variant involving a ternary complex. PMID:18710261

  1. HAG3, a Histone Acetyltransferase, Affects UV-B Responses by Negatively Regulating the Expression of DNA Repair Enzymes and Sunscreen Content in Arabidopsis thaliana.

    PubMed

    Fina, Julieta P; Casati, Paula

    2015-07-01

    Histone acetylation is regulated by histone acetyltransferases and deacetylases. In Arabidopsis, there are 12 histone acetyltransferases and 18 deacetylases. Histone acetyltransferases are organized in four families: the GNAT/HAG, the MYST, the p300/CBP and the TAFII250 families. Previously, we demonstrated that Arabidopsis mutants in the two members of the MYST acetyltransferase family show increased DNA damage after UV-B irradiation. To investigate further the role of other histone acetyltransferases in UV-B responses, a putative role for enzymes of the GNAT family, HAG1, HAG2 and HAG3, was analyzed. HAG transcripts are not UV-B regulated; however, hag3 RNA interference (RNAi) transgenic plants show a lower inhibition of leaf and root growth by UV-B, higher levels of UV-B-absorbing compounds and less UV-B-induced DNA damage than Wassilewskija (Ws) plants, while hag1 RNAi transgenic plants and hag2 mutants do not show significant differences from wild-type plants. Transcripts for UV-B-regulated genes are highly expressed under control conditions in the absence of UV-B in hag3 RNAi transgenic plants, suggesting that the higher UV-B tolerance may be due to increased levels of proteins that participate in UV-B responses. Together, our data provide evidence that HAG3, directly or indirectly, participates in UV-B-induced DNA damage repair and signaling.

  2. Benzodiazepines: rat pinealocyte binding sites and augmentation of norepinephrine-stimulated N-acetyltransferase activity

    SciTech Connect

    Matthew, E.; Parfitt, A.G.; Sugden, D.; Engelhardt, D.L.; Zimmerman, E.A.; Klein, D.C.

    1984-02-01

    Studies of (/sup 3/H)diazepam binding to intact rat pineal cells were carried out in tissue culture preparations. The binding was saturable, reversible and proportional to the number of cells used. Scatchard analysis resulted in a linear plot (Kd . 23 nM, maximum binding sites (Bmax) . 1.56 pmol/mg of protein for cells in monolayer culture; Kd . 7 nM, Bmax . 1.3 pmol/mg of protein for cells in suspension culture). Inhibition constants (Ki) for clonazepam (500 nM), flunitrazepam (38 nM) and Ro-5-4864 (5 nM) indicated that the binding sites were probably of the ''peripheral'' type. In addition, the effects of diazepam on norepinephrine-stimulated N-acetyltransferase (NAT) activity were studied in organ culture and dissociated cell culture. Diazepam (10-50 microM) both prolonged and increased the magnitude of the norepinephrine-induced increase in NAT activity but did not affect the initial rate of rise of enzyme activity. The effect was dose-dependent and was also seen with clonazepam, flunitrazepam and Ro-5-4864, but not with Ro-15-1788. Diazepam, by itself, at these concentrations, had no effect on NAT, but enzyme activity was increased by higher concentrations (0.1-1 mM). Although a relationship between the (/sup 3/H)diazepam binding sites described here and the effect of benzodiazepines on NAT cannot be established from these studies, the data suggest that the benzodiazepines may alter melatonin levels through their action on NAT.

  3. Immunochemical detection of arylamine N-acetyltransferase during mouse embryonic development and in adult mouse brain.

    PubMed

    Stanley, L A; Copp, A J; Pope, J; Rolls, S; Smelt, V; Perry, V H; Sim, E

    1998-11-01

    Arylamine N-acetyltransferases (NATs) are important in susceptibility to xenobiotic-induced disorders (e.g., drug-induced autoimmune disease, bladder cancer), but their role in endogenous metabolism is yet to be elucidated. The discovery that human NAT1 acts upon p-aminobenzoylgluatamate (p-ABG) to generate p-acetamidobenzoylglutamate (p-AABG), a major urinary metabolite of folic acid, suggests that human NAT1 may play a role in folic acid metabolism and hence in the normal development of the neural tube. In this study we examined the distribution of NAT in neuronal tissue from adult mice and embryos. Immunohistochemical staining of the adult mouse cerebellum revealed NAT2 (the mouse homologue of human NAT1) expression in the cell bodies and dendrites of Purkinje cells and in the neuroglia of the molecular layer. In embryos, NAT2 was detected in developing neuronal tissue on days 9.5, 11.5, and 13.5. It was expressed intensely in the nerual tube around the time of closure. The level of expression subsequently declined in the neuroepithelium but increased in glial cells. In addition, NAT2 was detected in the developing heart and gut. These findings demonstrate that the embryo itself expresses an enzyme which is involved in the metabolism of folic acid, so that the role played by both mother and embryo must be considered when examining the role of folic acid in embryonic development. These findings imply that polymorphisms in NAT genes could play a role in determining susceptibility to neural tube defects (NTD) and orofacial clefting, developmental disorders which can be prevented by dietary administration of folic acid. PMID:9839355

  4. Functional properties of an alternative, tissue-specific promoter for human arylamine N-acetyltransferase 1

    PubMed Central

    Barker, David F.; Husain, Anwar; Neale, Jason R.; Martini, Benjamin D.; Zhang, Xiaoyan; Doll, Mark A.; Christopher States, J.; Hein, David W.

    2007-01-01

    Variable expression of human arylamine N-acetyltransferase 1 (NAT1) due to genetic polymorphism, gene regulation or environmental influences is associated with individual susceptibility to various cancers. Recent studies of NAT1 transcription showed that most mRNAs originate at a promoter, P1, located 11.8 kb upstream of the single open reading frame (ORF) exon. We have now characterized an alternative NAT1 promoter lying 51.5 kb upstream of the NAT1 ORF. In the present study, analysis of human RNAs representing 27 tissue types by RT-PCR and quantitative RT-PCR showed the upstream 51.5 kb promoter, designated P3, to be most active in specific tissues, including kidney, liver, lung, and trachea. All NAT1 P3 mRNAs included 5’-untranslated region (5’-UTR) internal exons of 61 and 175 nucleotides in addition to the 79 nucleotide 5’-UTR exon present in P1 mRNA. CAP-dependent amplification of 5’ P3 mRNA termini defined an 84 bp transcription start region in which most start sites are centrally clustered. The hepatoma-derived HepG2 cell line expressed a high level of P3 mRNA with the same spliced structure and start site pattern as found in normal tissues. A 435 bp minimal promoter was defined by transfection of HepG2 with luciferase expression constructs containing genomic fragments from the P3 start region. These findings imply a fundamental role for P3 in NAT1 regulation and define additional regions for genetic polymorphisms associated with enhanced cancer risk. PMID:16788383

  5. Choline acetyltransferase mutations causing congenital myasthenic syndrome: molecular findings and genotype-phenotype correlations

    PubMed Central

    Arredondo, Juan; Lara, Marian; Gospe, Sídney M.; Mazia, Claudio G.; Vaccarezza, Maria; Garcia-Erro, Marcela; Bowe, Constance; Chang, Celia; Mezei, Michelle; Maselli, Ricardo A.

    2015-01-01

    Choline acetyltransferase catalyzes the synthesis of acetylcholine at cholinergic nerves. Mutations in human CHAT cause a congenital myasthenic syndrome (CMS) due to impaired synthesis of ACh; this severe variant of the disease is frequently associated with unexpected episodes of potentially fatal apnea. The severity of this condition varies remarkably, and the molecular factors determining this variability are poorly understood. Furthermore, genotype–phenotype correlations have been difficult to establish in patients with biallelic mutations. We analyzed the protein expression of seven ChAT mutations, p.Val136Met, p.Arg207His, p.Arg186Trp, p.Val194Leu, p.Pro211Ala, p.Arg566Cys and p.Ser694Cys, in HEK-293 cells to phosphorylated ChAT, determined their enzyme kinetics and thermal instability, and examined their structural changes. Three mutations, p.Arg207His, p.Arg186Trp and p.Arg566Cys, are novel, and p.Val136Met and p.Arg207His are homozygous in three families and associated with severe disease. The characterization of mutants showed a decrease in the overall catalytic efficiency of ChAT; in particular, those located near the active-site tunnel produced the most seriously disruptive phenotypic effects. On the other hand, p.Val136Met is located far from both active and substrate-binding sites produced the most drastic reduction of ChAT expression. Overall, CHAT mutations producing low enzyme expression and severe kinetic effects are associated with the most severe phenotypes. PMID:26080897

  6. Origins of spinal cholinergic pathways in amphibians demonstrated by retrograde transport and choline acetyltransferase immunohistochemistry.

    PubMed

    López, Jesús M; Morona, Ruth; Moreno, Nerea; Domínguez, Laura; González, Agustín

    2007-09-25

    The existence of propriospinal cholinergic pathways and the origin of supraspinal cholinergic descending projections have been investigated in anuran and urodele amphibians. Retrograde tract tracing techniques with dextran amines injected in the spinal cord at different levels were combined with immunohistochemistry for choline acetyltransferase (ChAT). The analysis of the brachial, thoracic and lumbar spinal cord demonstrated that doubly labeled cells were present only close to the injection site. Thus, the participation of the spinal cholinergic cells in distant intersegmental connections is not present, or is very limited, in amphibians. In anurans, tracer applications to the brachial cord revealed cholinergic cells of origin of spinal projections located in four distinct brain nuclei. The most rostrally located cells were found bilaterally in the preoptic area, among the magnocellular cells. In the ipsilateral isthmic region, the laterodorsal tegmental nucleus also showed doubly labeled cells. Throughout the brainstem, abundant codistribution was observed but actual coexistence of the tracer and ChAT was only found in the nucleus of the solitary tract and the inferior reticular nucleus. In the case of the urodele, abundant codistribution between retrogradely labeled cells and ChAT-positive neurons in zones like the suprachiasmatic nucleus, the isthmic region and the rhombencephalic reticular formation was observed, but the only doubly labeled cells were the Mauthner neurons. The present results in amphibians contrast with previous data in mammals in which is striking the presence of a widespread intrinsic cholinergic innervation of the spinal cord and the virtual absence of cholinergic projections descending from the brainstem.

  7. Arylamine N-acetyltransferases: from drug metabolism and pharmacogenetics to drug discovery

    PubMed Central

    Sim, E; Abuhammad, A; Ryan, A

    2014-01-01

    Arylamine N-acetyltransferases (NATs) are polymorphic drug-metabolizing enzymes, acetylating arylamine carcinogens and drugs including hydralazine and sulphonamides. The slow NAT phenotype increases susceptibility to hydralazine and isoniazid toxicity and to occupational bladder cancer. The two polymorphic human NAT loci show linkage disequilibrium. All mammalian Nat genes have an intronless open reading frame and non-coding exons. The human gene products NAT1 and NAT2 have distinct substrate specificities: NAT2 acetylates hydralazine and human NAT1 acetylates p-aminosalicylate (p-AS) and the folate catabolite para-aminobenzoylglutamate (p-abaglu). Human NAT2 is mainly in liver and gut. Human NAT1 and its murine homologue are in many adult tissues and in early embryos. Human NAT1 is strongly expressed in oestrogen receptor-positive breast cancer and may contribute to folate and acetyl CoA homeostasis. NAT enzymes act through a catalytic triad of Cys, His and Asp with the architecture of the active site-modulating specificity. Polymorphisms may cause unfolded protein. The C-terminus helps bind acetyl CoA and differs among NATs including prokaryotic homologues. NAT in Salmonella typhimurium supports carcinogen activation and NAT in mycobacteria metabolizes isoniazid with polymorphism a minor factor in isoniazid resistance. Importantly, nat is in a gene cluster essential for Mycobacterium tuberculosis survival inside macrophages. NAT inhibitors are a starting point for novel anti-tuberculosis drugs. Human NAT1-specific inhibitors may act in biomarker detection in breast cancer and in cancer therapy. NAT inhibitors for co-administration with 5-aminosalicylate (5-AS) in inflammatory bowel disease has prompted ongoing investigations of azoreductases in gut bacteria which release 5-AS from prodrugs including balsalazide. PMID:24467436

  8. [Clinical relevance of N-acetyltransferase type 2 (NAT2) genetic polymorphism].

    PubMed

    Furet, Y; Bechtel, Y; Le Guellec, C; Bechtel, P R; Autret-Leca, E; Paintaud, G

    2002-01-01

    Polymorphic N-acetyltransferase (NAT2) is involved in the metabolism of several compounds relevant in pharmacology or toxicology, with diverse clinical consequences. Inter-ethnic variations in distribution of the acetylation phenotype are significant. The caffeine test is most often used to assess the acetylation phenotype and to identify rapid and slow acetylators. The NAT2 phenotype could account for the increased risk of certain side effects in slow acetylators treated with isoniazid (particularly peripheral neuropathies and lupus erythematosus), although therapeutic efficacy seems to be independent of the acetylation status. Hypersensibility reactions with sulfonamides (including Lyell and Stevens-Johnson syndromes) are more frequent in slow acetylators, who also show poor tolerance to sulfasalazine and dapsone. In contrast, myelotoxicity induced by amonafide is more frequent in rapid acetylators, probably because of increased production of a toxic metabolite of the drug. In carcinogenesis, NAT2 may play a protective role against bladder cancer, although studies have shown contradictory results. Slow acetylators may have a risk of developing primitive liver cancer. For lung cancer, data are not conclusive, but slow acetylation status may predispose to mesothelioma in subjects exposed to asbestos. No relation has been found between acetylation phenotype and breast cancer. Contradictory results were reported on its role in colorectal cancer. Non-smoking type 1 diabetics may be at increased risk of nephropathy if they are rapid acetylators. Parkinson's disease may be more frequent among slow acetylators, but again, data have shown contradictory results. Finally, a poor acetylator phenotype may predispose to atopic diseases. PMID:12611196

  9. Arylamine N-acetyltransferase 2 (NAT2) genetic diversity and traditional subsistence: a worldwide population survey.

    PubMed

    Sabbagh, Audrey; Darlu, Pierre; Crouau-Roy, Brigitte; Poloni, Estella S

    2011-01-01

    Arylamine N-acetyltransferase 2 (NAT2) is involved in human physiological responses to a variety of xenobiotic compounds, including common therapeutic drugs and exogenous chemicals present in the diet and the environment. Many questions remain about the evolutionary mechanisms that have led to the high prevalence of slow acetylators in the human species. Evidence from recent surveys of NAT2 gene variation suggests that NAT2 slow-causing variants might have become targets of positive selection as a consequence of the shift in modes of subsistence and lifestyle in human populations in the last 10,000 years. We aimed to test more extensively the hypothesis that slow acetylation prevalence in humans is related to the subsistence strategy adopted by the past populations. To this end, published frequency data on the most relevant genetic variants of NAT2 were collected from 128 population samples (14,679 individuals) representing different subsistence modes and dietary habits, allowing a thorough analysis at both a worldwide and continent scale. A significantly higher prevalence of the slow acetylation phenotype was observed in populations practicing farming (45.4%) and herding (48.2%) as compared to populations mostly relying on hunting and gathering (22.4%) (P = 0.0007). This was closely mirrored by the frequency of the slow 590A variant that was found to occur at a three-fold higher frequency in food producers (25%) as compared to hunter-gatherers (8%). These findings are consistent with the hypothesis that the Neolithic transition to subsistence economies based on agricultural and pastoral resources modified the selective regime affecting the NAT2 acetylation pathway. Furthermore, the vast amount of data collected enabled us to provide a comprehensive and up-to-date description of NAT2 worldwide genetic diversity, thus building up a useful resource of frequency data for further studies interested in epidemiological or anthropological research questions involving

  10. DNA hybridization and phosphinothricin acetyltransferase gene sequence detection based on zirconia/nanogold film modified electrode

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Yang, Tao; Jiang, Chen; Jiao, Kui

    2008-05-01

    This study reports a novel electrochemical DNA biosensor based on zirconia (ZrO 2) and gold nanoparticles (NG) film modified glassy carbon electrode (GCE). NG was electrodeposited onto the glassy carbon electrode at 1.5 V, and then zirconia thin film on the NG/GCE was fabricated by cyclic voltammetric method (CV) in an aqueous electrolyte of ZrOCl 2 and KCl at a scan rate of 20 mV/s. DNA probes were attached onto the ZrO 2/NG/GCE due to the strong binding of the phosphate group of DNA with the zirconia film and the excellent biocompatibility of nanogold with DNA. CV and electrochemical impedance spectroscopy (EIS) were used to characterize the modification of the electrode and the probe DNA immobilization. The electrochemical response of the DNA hybridization was measured by differential pulse voltammetry (DPV) using methylene blue (MB) as the electroactive indicator. After the hybridization of DNA probe (ssDNA) with the complementary DNA (cDNA), the cathodic peak current of MB decreased obviously. The difference of the cathodic peak currents of MB between before and after the hybridization of the probe DNA was used as the signal for the detection of the target DNA. The sequence-specific DNA of phosphinothricin acetyltransferase (PAT) gene in the transgenic plants was detected with a detection range from 1.0 × 10 -10 to 1.0 × 10 -6 mol/L, and a detection limit of 3.1 × 10 -11 mol/L.

  11. Effect of arylamine acetyltransferase Nat3 gene knockout on N-acetylation in the mouse.

    PubMed

    Sugamori, K S; Brenneman, D; Wong, S; Gaedigk, A; Yu, V; Abramovici, H; Rozmahel, R; Grant, D M

    2007-07-01

    Arylamine N-acetyltransferases (NAT) catalyze the biotransformation of many important arylamine drugs and procarcinogens. NAT can either detoxify or activate procarcinogens, complicating the manner in which these enzymes may participate in enhancing or preventing toxic responses to particular agents. Mice possess three NAT isoenzymes: Nat1, Nat2, and Nat3. Whereas Nat1 and Nat2 can efficiently acetylate many arylamines, few substrates appear to be appreciably metabolized by Nat3. We generated a Nat3 knockout mouse strain and used it along with our double Nat1/2(-/-) knockout strain to further investigate the functional role of Nat3. Nat3(-/-) mice showed normal viability and reproductive capacity. Nat3 expression was very low in wild-type animals and completely undetectable in Nat3(-/-) mice. In contrast, greatly elevated expression of Nat3 transcript was observed in Nat1/2(-/-) mice. We used a transcribed marker polymorphism approach to establish that the increased expression of Nat3 in Nat1/2(-/-) mice is a positional artifact of insertion of the phosphoglycerate kinase-neomycin resistance cassette in place of the Nat1/Nat2 gene region and upstream of the intact Nat3 gene, rather than a biological compensatory mechanism. Despite the increase in Nat3 transcript, the N-acetylation of p-aminosalicylate, sulfamethazine, 2-aminofluorene, and 4-aminobiphenyl was undetectable either in vivo or in vitro in Nat1/2(-/-) animals. In parallel, no difference was observed in the in vivo clearance or in vitro metabolism of any of these substrates between wild-type and Nat3(-/-) mice. Thus, Nat3 is unlikely to play a significant role in the N-acetylation of arylamines either in wild-type mice or in mice lacking Nat1 and Nat2 activities. PMID:17403913

  12. N-acetyltransferase 1 in colon and rectal cancer cases from an industrialized area.

    PubMed

    Roemer, Hermann C; Weistenhofer, Wobbeke; Lohlein, Dietrich; Geller, Frank; Blomeke, Brunhilde; Golka, Klaus

    2008-01-01

    Colon and rectal cancers are both associated with genetic as well as nutritional, occupational, and environmental factors. Aromatic amines and heterocyclic amines are established colorectal carcinogens. The polymorphic enzyme N-acetyltransferase 1 (NAT1) contributes to heterocyclic amine metabolism in the human colon. Thereby, NAT1 may influence the risk for development of colorectal cancer. The distribution of NAT1 genotypes was determined in 107 colon cancer cases, 77 rectal cancer cases, and 185 controls (suffering from nonmalignant diseases) by standard methods. In addition, possible occupational and nonoccupational risk factors were determined by a personal interview. Cancer cases and controls were derived from an area of former coal, iron, and steel industries, which is known for elevated colon cancer mortality. The proportions of NAT1*4/*4 genotype were 72% in controls, 75% in rectal cancer cases, and 72% in colon cancer cases. The proportions of the NAT1*4/*10 genotype were 17.8% in controls, 12.9% in rectal cancer cases, and 14% in colon cancer cases. Combinations of the determined NAT1 alleles *3/*3, *3/*10, *4/*3, *4/*11, *10/*10 and *11/*11 contributed to 10.2% of the genotypes in controls, 12.1% in rectal cancer cases, and 14% in colon cancer cases. In contrast to another study on healthy German volunteers, the NAT1*4/*4 genotype (wild type) is overrepresented. This might be due to the variation in the proportion of NAT1 alleles in the general population. The present study does not support a relevant impact of the NAT1 genotype on colorectal cancer risk development in the study area.

  13. Arylamine N-Acetyltransferase 2 (NAT2) Genetic Diversity and Traditional Subsistence: A Worldwide Population Survey

    PubMed Central

    Sabbagh, Audrey; Darlu, Pierre; Crouau-Roy, Brigitte; Poloni, Estella S.

    2011-01-01

    Arylamine N-acetyltransferase 2 (NAT2) is involved in human physiological responses to a variety of xenobiotic compounds, including common therapeutic drugs and exogenous chemicals present in the diet and the environment. Many questions remain about the evolutionary mechanisms that have led to the high prevalence of slow acetylators in the human species. Evidence from recent surveys of NAT2 gene variation suggests that NAT2 slow-causing variants might have become targets of positive selection as a consequence of the shift in modes of subsistence and lifestyle in human populations in the last 10,000 years. We aimed to test more extensively the hypothesis that slow acetylation prevalence in humans is related to the subsistence strategy adopted by the past populations. To this end, published frequency data on the most relevant genetic variants of NAT2 were collected from 128 population samples (14,679 individuals) representing different subsistence modes and dietary habits, allowing a thorough analysis at both a worldwide and continent scale. A significantly higher prevalence of the slow acetylation phenotype was observed in populations practicing farming (45.4%) and herding (48.2%) as compared to populations mostly relying on hunting and gathering (22.4%) (P = 0.0007). This was closely mirrored by the frequency of the slow 590A variant that was found to occur at a three-fold higher frequency in food producers (25%) as compared to hunter-gatherers (8%). These findings are consistent with the hypothesis that the Neolithic transition to subsistence economies based on agricultural and pastoral resources modified the selective regime affecting the NAT2 acetylation pathway. Furthermore, the vast amount of data collected enabled us to provide a comprehensive and up-to-date description of NAT2 worldwide genetic diversity, thus building up a useful resource of frequency data for further studies interested in epidemiological or anthropological research questions involving

  14. Human NAT10 Is an ATP-dependent RNA Acetyltransferase Responsible for N4-Acetylcytidine Formation in 18 S Ribosomal RNA (rRNA)*

    PubMed Central

    Ito, Satoshi; Horikawa, Sayuri; Suzuki, Tateki; Kawauchi, Hiroki; Tanaka, Yoshikazu; Suzuki, Takeo; Suzuki, Tsutomu

    2014-01-01

    Human N-acetyltransferase 10 (NAT10) is known to be a lysine acetyltransferase that targets microtubules and histones and plays an important role in cell division. NAT10 is highly expressed in malignant tumors, and is also a promising target for therapies against laminopathies and premature aging. Here we report that NAT10 is an ATP-dependent RNA acetyltransferase responsible for formation of N4-acetylcytidine (ac4C) at position 1842 in the terminal helix of mammalian 18 S rRNA. RNAi-mediated knockdown of NAT10 resulted in growth retardation of human cells, and this was accompanied by high-level accumulation of the 30 S precursor of 18 S rRNA, suggesting that ac4C1842 formation catalyzed by NAT10 is involved in rRNA processing and ribosome biogenesis. PMID:25411247

  15. A unique GCN5-related glucosamine N-acetyltransferase region exist in the fungal multi-domain glycoside hydrolase family 3 β-N-acetylglucosaminidase

    PubMed Central

    Qin, Zhen; Xiao, Yibei; Yang, Xinbin; Mesters, Jeroen R.; Yang, Shaoqing; Jiang, Zhengqiang

    2015-01-01

    Glycoside hydrolase (GH) family 3 β-N-acetylglucosaminidases widely exist in the filamentous fungi, which may play a key role in chitin metabolism of fungi. A multi-domain GH family 3 β-N-acetylglucosaminidase from Rhizomucor miehei (RmNag), exhibiting a potential N-acetyltransferase region, has been recently reported to show great potential in industrial applications. In this study, the crystal structure of RmNag was determined at 2.80 Å resolution. The three-dimensional structure of RmNag showed four distinctive domains, which belong to two distinguishable functional regions — a GH family 3 β-N-acetylglucosaminidase region (N-terminal) and a N-acetyltransferase region (C-terminal). From structural and functional analysis, the C-terminal region of RmNag was identified as a unique tandem array linking general control non-derepressible 5 (GCN5)-related N-acetyltransferase (GNAT), which displayed glucosamine N-acetyltransferase activity. Structural analysis of this glucosamine N-acetyltransferase region revealed that a unique glucosamine binding pocket is located in the pantetheine arm binding terminal region of the conserved CoA binding pocket, which is different from all known GNAT members. This is the first structural report of a glucosamine N-acetyltransferase, which provides novel structural information about substrate specificity of GNATs. The structural and functional features of this multi-domain β-N-acetylglucosaminidase could be useful in studying the catalytic mechanism of GH family 3 proteins. PMID:26669854

  16. Lysine Acetyltransferase GCN5 Potentiates the Growth of Non-small Cell Lung Cancer via Promotion of E2F1, Cyclin D1, and Cyclin E1 Expression*

    PubMed Central

    Chen, Long; Wei, Tingyi; Si, Xiaoxing; Wang, Qianqian; Li, Yan; Leng, Ye; Deng, Anmei; Chen, Jie; Wang, Guiying; Zhu, Songcheng; Kang, Jiuhong

    2013-01-01

    The lysine acetyltransferases play crucial but complex roles in cancer development. GCN5 is a lysine acetyltransferase that generally regulates gene expression, but its role in cancer development remains largely unknown. In this study, we report that GCN5 is highly expressed in non-small cell lung cancer tissues and that its expression correlates with tumor size. We found that the expression of GCN5 promotes cell growth and the G1/S phase transition in multiple lung cancer cell lines. Further study revealed that GCN5 regulates the expression of E2F1, cyclin D1, and cyclin E1. Our reporter assays indicated that the expression of GCN5 enhances the activities of the E2F1, cyclin D1, and cyclin E1 promoters. ChIP experiments suggested that GCN5 binds directly to these promoters and increases the extent of histone acetylation within these regions. Mechanistic studies suggested that GCN5 interacts with E2F1 and is recruited by E2F1 to the E2F1, cyclin D1, and cyclin E1 promoters. The function of GCN5 in lung cancer cells is abrogated by the knockdown of E2F1. Finally, we confirmed that GCN5 regulates the expression of E2F1, cyclin D1, and cyclin E1 and potentiates lung cancer cell growth in a mouse tumor model. Taken together, our results demonstrate that GCN5 specifically potentiates lung cancer growth by directly promoting the expression of E2F1, cyclin D1, and cyclin E1 in an E2F1-dependent manner. Our study identifies a specific and novel function of GCN5 in lung cancer development and suggests that the GCN5-E2F1 interaction represents a potential target for lung cancer treatment. PMID:23543735

  17. KEPLER AND GROUND-BASED TRANSITS OF THE EXO-NEPTUNE HAT-P-11b

    SciTech Connect

    Deming, Drake; Jackson, Brian; Jennings, Donald E.; Sada, Pedro V.; Peterson, Steven W.; Haase, Flynn; Bays, Kevin; Agol, Eric; Knutson, Heather A.

    2011-10-10

    We analyze 26 archival Kepler transits of the exo-Neptune HAT-P-11b, supplemented by ground-based transits observed in the blue (B band) and near-IR (J band). Both the planet and host star are smaller than previously believed; our analysis yields R{sub p} = 4.31 R{sub +} {+-} 0.06 R{sub +} and R{sub s} = 0.683 R{sub sun} {+-} 0.009 R{sub sun}, both about 3{sigma} smaller than the discovery values. Our ground-based transit data at wavelengths bracketing the Kepler bandpass serve to check the wavelength dependence of stellar limb darkening, and the J-band transit provides a precise and independent constraint on the transit duration. Both the limb darkening and transit duration from our ground-based data are consistent with the new Kepler values for the system parameters. Our smaller radius for the planet implies that its gaseous envelope can be less extensive than previously believed, being very similar to the H-He envelope of GJ 436b and Kepler-4b. HAT-P-11 is an active star, and signatures of star spot crossings are ubiquitous in the Kepler transit data. We develop and apply a methodology to correct the planetary radius for the presence of both crossed and uncrossed star spots. Star spot crossings are concentrated at phases -0.002 and +0.006. This is consistent with inferences from Rossiter-McLaughlin measurements that the planet transits nearly perpendicular to the stellar equator. We identify the dominant phases of star spot crossings with active latitudes on the star, and infer that the stellar rotational pole is inclined at about 12{sup 0} {+-} 5{sup 0} to the plane of the sky. We point out that precise transit measurements over long durations could in principle allow us to construct a stellar Butterfly diagram to probe the cyclic evolution of magnetic activity on this active K-dwarf star.

  18. HDAC Inhibition Modulates Hippocampus-Dependent Long-Term Memory for Object Location in a CBP-Dependent Manner

    ERIC Educational Resources Information Center

    Haettig, Jakob; Stefanko, Daniel P.; Multani, Monica L.; Figueroa, Dario X.; McQuown, Susan C.; Wood, Marcelo A.

    2011-01-01

    Transcription of genes required for long-term memory not only involves transcription factors, but also enzymatic protein complexes that modify chromatin structure. Chromatin-modifying enzymes, such as the histone acetyltransferase (HAT) CREB (cyclic-AMP response element binding) binding protein (CBP), are pivotal for the transcriptional regulation…

  19. Development of choline acetyltransferase-immunoreactive neurons in normal and intracranially transplanted retinas in rats.

    PubMed

    Guo, Q X; Chau, R M; Yang, S Z; Jen, L S

    1991-10-21

    Retinas from embryonic day 14 (E14) Sprague-Dawley rats were transplanted to the tectum of newborn (P0) recipient rats, and the distribution pattern of choline acetyltransferase immunoreactivity (ChAT-I) in developing transplants was studied and compared with those observed in the retinas of normal developing rats. In normal retinas, ChAT-I cells were first identified in restricted regions in the ganglion cell layer (GCL) at P4, but were found to cover the entire GCL by P6. A second population of ChAT-I cells was detected in the inner nuclear layer (INL) at P8, and they were observed in most parts of the INL on P10 when two immunoreactive sublaminae began to appear in the inner plexiform layer (IPL). The adult pattern of having two distinct populations of ChAT-I cells, organized in mirror symmetrical fashion in the inner retinal layers was basically established by P12. The time course of development and overall distribution pattern of ChAT-I cells in developing retinal transplants on the whole were very similar to those observed in normal retinas. The first identification of these cells and the establishment of their final distribution pattern were made at stages corresponding to P4 and P12 of normal developing retinas respectively. However, ChAT-I somata were located in the INL at a much earlier stage compared with their counterparts in the normal retina, and a transient population of immunoreactive cells with their processes extending to retinal layers other than the IPL was observed in some transplants from P6 to P10. These features were not observed in normal developing retinas. These results suggest that the development of cholinergic neurons, especially the expression of their characteristic antigen and their final distribution pattern is largely determined by programmes which are intrinsic to the original retinal tissue, despite some minor deviation or variation in the developmental process which may occur under certain abnormal conditions. PMID:1769097

  20. Sex-dependent differences in estrogen regulation of choline acetyltransferase are altered by neonatal treatments.

    PubMed

    Luine, V N; Renner, K J; McEwen, B S

    1986-08-01

    We investigated whether estrogenic actions of testosterone during development which mediate the suppression of feminine reproductive behavior and cyclic gonadotropin secretion also contribute to reported sex differences in the induction of choline acetyltransferase (ChAT) after estrogen priming in the diagonal band region of the preoptic area. Newborn female rats received estradiol (E2 females); newborn males received 1,4,6-androstatrien-3,17-dione (ATD), an inhibitor of aromatase (ATD males); and some of both sexes received vehicle treatment (control). In adulthood, feminine sexual behavior (lordosis) was tested after E2 plus progesterone priming. The neonatal treatments reversed the sex-specific response pattern; E2 females were defeminized and displayed minimal lordosis, as did control males, while ATD males showed maximal lordosis, as did control females. E2 was then administered, and ChAT activity was measured in the horizontal and vertical nuclei of the diagonal bands (hDB and vDB, respectively). Controls exhibited the normal sex-specific response to E2. Females showed increased ChAT activity in the hDB and unaltered activity in the vDB: males had unaltered ChAT activity in the hDB and decreased activity in the vDB. In neonatally treated males and females, ChAT activity after E2 administration was not altered from the normal sex-specific pattern in the hDB, i.e. all females showed increased hDB ChAT after E2, and no male responded. In the vDB, groups defeminized in terms of lordosis (E2 females and control males) showed higher ChAT activity in the absence of E2 priming, and E2 treatment decreased vDB ChAT in these groups. In addition, ATD males showed a unique response to E2 in the vDB, namely increased ChAT activity. Although neonatal E2 and ATD treatments did not completely reverse the sex-specific pattern of E2 priming on ChAT activity, the results obtained suggest that a net increase in diagonal band cholinergic function, as indexed by increased Ch

  1. Crystallization and preliminary X-ray characterization of arylamine N-acetyltransferase C (BanatC) from Bacillus anthracis

    SciTech Connect

    Pluvinage, Benjamin; Li de la Sierra-Gallay, Inés; Martins, Marta; Ragunathan, Nilusha; Dupret, Jean-Marie; Rodrigues-Lima, Fernando

    2007-10-01

    Bacillus anthracis arylamine N-acetyltransferase C (BanatC) is an enzyme that metabolizes the drug sulfamethoxazole. Crystals of the purified enzyme that diffract at 1.95 Å are reported. The arylamine N-acetyltransferase (NAT) enzymes are xenobiotic metabolizing enzymes that have been found in a large range of eukaryotes and prokaryotes. These enzymes catalyse the acetylation of arylamine drugs and/or pollutants. Recently, a Bacillus anthracis NAT isoform (BanatC) has been cloned and shown to acetylate the sulfonamide antimicrobial sulfamethoxazole (SMX). Subsequently, it was shown that BanatC contributes to the resistance of this bacterium to SMX. Here, the crystallization and the X-ray characterization of BanatC (Y38F mutant) are reported. The crystals belong to the tetragonal space group P4{sub 1}2{sub 1}2 or P4{sub 3}2{sub 1}2, with unit-cell parameters a = b = 53.70, c = 172.40 Å, and diffract to 1.95 Å resolution on a synchrotron source.

  2. Effects of restricted food access on circadian fluctuation of serotonin N-acetyltransferase activities in hereditary microphthalmic rats.

    PubMed

    Shim, S; Tanaka, H

    2000-12-01

    The characteristics in diurnal fluctuation of serotonin N-acetyltransferase activity were examined in normal and microphthalmic mutant rats of the Donryu strain under ad lib or restricted feeding conditions. Under a 12:12-h light:dark (12-h LD) cycle with free access to food, normal-sighted rats exhibited typical nocturnal increases in the activity of pineal serotonin N-acetyltransferase, being more than 50-fold higher in the dark period than that in the light period, but hereditary blind rats showed nonperiodic change in the pineal enzyme activity in the average, suggesting that the rhythms in individuals have become free-running, asynchronous. When the subjective night or subjective day of the mutants was discerned by active or inactive in the locomotor activity, the pineal enzyme activities in the mutants increased at the subjective night but depressed at the subjective daytime. When food access was restricted only for 6 h in the light period of the LD cycle, normal rats still showed the nocturnal increases in the pineal enzyme activity, but hereditary blind rats manifested a blunt peak in the activity of the pineal enzyme at eating time in the light period. The results suggest that microphthalmic mutant rats maintain the ability to shift and to synchronize their circadian phases induced by restricted access to food, even if they completely lack their optic nerve and visual input to the circadian clock.

  3. The human serotonin N-acetyltransferase (EC 2.3.1.87) gene (AANAT): Structure, chromosomal localization, and tissue expression

    SciTech Connect

    Coon, S.L.; Bernard, M.; Roseboom, P.H.

    1996-05-15

    Serotonin N-acetyltransferase (arylalkylamine N-acetyltransferase, AA-NAT, HGMW-approved symbol AANAT;EC 2.3.1.87) is the penultimate enzyme in melatonin synthesis and controls the night/day rhythm in melatonin production in the vertebrate pineal gland. We have found that the human AA-NAT gene spans {approx}2.5 kb, contains four exons, and is located at chromosome 17q25. The open reading frame encodes a 23.2-kDa protein that is {approx}80% identical to sheep and rat AA-NAT. The AA-NAT transcript ({approx}1 kb) is highly abundant in the pineal gland and is expressed at lower levels in the retina and in the Y79 retinoblastoma cell line. AA-NAT mRNA is also detectable at low levels in several brain regions and the pituitary gland, but not in several peripheral tissues examined. Brain and pituitary AA-NAT could modulate serotonin-dependent aspects of human behavior and pituitary function. 31 refs., 5 figs.

  4. The polyamine N-acetyltransferase-like enzyme PmvE plays a role in the virulence of Enterococcus faecalis.

    PubMed

    Martini, Cecilia; Michaux, Charlotte; Bugli, Francesca; Arcovito, Alessandro; Iavarone, Federica; Cacaci, Margherita; Paroni Sterbini, Francesco; Hartke, Axel; Sauvageot, Nicolas; Sanguinetti, Maurizio; Posteraro, Brunella; Giard, Jean-Christophe

    2015-01-01

    We previously showed that the mutant strain of Enterococcus faecalis lacking the transcriptional regulator SlyA is more virulent than the parental strain. We hypothesized that this phenotype was due to overexpression of the second gene of the slyA operon, ef_3001, renamed pmvE (for polyamine metabolism and virulence of E. faecalis). PmvE shares strong homologies with N(1)-spermidine/spermine acetyltransferase enzymes involved in the metabolism of polyamines. In this study, we used an E. faecalis strain carrying the recombinant plasmid pMSP3535-pmvE (V19/p3535-pmvE), which allows the induction of pmvE by addition of nisin. Thereby, we showed that the overexpression of PmvE increased the virulence of E. faecalis in the Galleria mellonella infection model, as well as the persistence within peritoneal macrophages. We were also able to show a direct interaction between the His-tagged recombinant PmvE (rPmvE) protein and putrescine by the surface plasmon resonance (SPR) technique on a Biacore instrument. Moreover, biochemical assays showed that PmvE possesses an N-acetyltransferase activity toward polyamine substrates. Our results suggest that PmvE contributes to the virulence of E. faecalis, likely through its involvement in the polyamine metabolism. PMID:25385793

  5. Nonenzymatic role of acetylcholinesterase in neuritic sprouting: regional changes in acetylcholinesterase and choline acetyltransferase after neonatal 6-hydroxydopamine lesions.

    PubMed

    Slotkin, Theodore A; Ryde, Ian T; Wrench, Nicola; Card, Jennifer A; Seidler, Frederic J

    2009-01-01

    Acetylcholinesterase (AChE) is postulated to play a nonenzymatic role in the development of neuritic projections. We gave the specific neurotoxin, 6-OHDA to rats on postnatal day (PN) 1, a treatment that destroys noradrenergic nerve terminals in the forebrain while producing reactive sprouting in the brainstem. AChE showed profound decreases in the forebrain that persisted in males over the entire phase of major synaptogenesis, from PN4 through PN21; in the brainstem, AChE was increased. Parallel examinations of choline acetyltransferase, an enzymatic marker for cholinergic nerve terminals, showed a different pattern of 6-OHDA-induced alterations, with initial decreases in both forebrain and brainstem in males and regression toward normal by PN21; females were far less affected. The sex differences are in accord with the greater plasticity of the female brain and its more rapid recovery from neurotoxic injury; our findings indicate that these differences are present well before puberty. These results support the view that AChE is involved in neurite formation, unrelated to its enzymatic role in cholinergic neurotransmission. Further, the results for choline acetyltransferase indicate that early depletion of norepinephrine compromises development of acetylcholine systems, consistent with a trophic role for this neurotransmitter.

  6. Biochemical evidence for relaxed substrate specificity of Nα-acetyltransferase (Rv3420c/rimI) of Mycobacterium tuberculosis

    PubMed Central

    Pathak, Deepika; Bhat, Aadil Hussain; Sapehia, Vandana; Rai, Jagdish; Rao, Alka

    2016-01-01

    Nα-acetylation is a naturally occurring irreversible modification of N-termini of proteins catalyzed by Nα-acetyltransferases (NATs). Although present in all three domains of life, it is little understood in bacteria. The functional grouping of NATs into six types NatA - NatF, in eukaryotes is based on subunit requirements and stringent substrate specificities. Bacterial orthologs are phylogenetically divergent from eukaryotic NATs, and only a couple of them are characterized biochemically. Accordingly, not much is known about their substrate specificities. Rv3420c of Mycobacterium tuberculosis is a NAT ortholog coding for RimIMtb. Using in vitro peptide-based enzyme assays and mass-spectrometry methods, we provide evidence that RimIMtb is a protein Nα-acetyltransferase of relaxed substrate specificity mimicking substrate specificities of eukaryotic NatA, NatC and most competently that of NatE. Also, hitherto unknown acetylation of residues namely, Asp, Glu, Tyr and Leu by a bacterial NAT (RimIMtb) is elucidated, in vitro. Based on in vivo acetylation status, in vitro assay results and genetic context, a plausible cellular substrate for RimIMtb is proposed. PMID:27353550

  7. An organellar nα-acetyltransferase, naa60, acetylates cytosolic N termini of transmembrane proteins and maintains Golgi integrity.

    PubMed

    Aksnes, Henriette; Van Damme, Petra; Goris, Marianne; Starheim, Kristian K; Marie, Michaël; Støve, Svein Isungset; Hoel, Camilla; Kalvik, Thomas Vikestad; Hole, Kristine; Glomnes, Nina; Furnes, Clemens; Ljostveit, Sonja; Ziegler, Mathias; Niere, Marc; Gevaert, Kris; Arnesen, Thomas

    2015-03-01

    N-terminal acetylation is a major and vital protein modification catalyzed by N-terminal acetyltransferases (NATs). NatF, or Nα-acetyltransferase 60 (Naa60), was recently identified as a NAT in multicellular eukaryotes. Here, we find that Naa60 differs from all other known NATs by its Golgi localization. A new membrane topology assay named PROMPT and a selective membrane permeabilization assay established that Naa60 faces the cytosolic side of intracellular membranes. An Nt-acetylome analysis of NAA60-knockdown cells revealed that Naa60, as opposed to other NATs, specifically acetylates transmembrane proteins and has a preference for N termini facing the cytosol. Moreover, NAA60 knockdown causes Golgi fragmentation, indicating an important role in the maintenance of the Golgi's structural integrity. This work identifies a NAT associated with membranous compartments and establishes N-terminal acetylation as a common modification among transmembrane proteins, a thus-far poorly characterized part of the N-terminal acetylome.

  8. Nonenzymatic role of acetylcholinesterase in neuritic sprouting: regional changes in acetylcholinesterase and choline acetyltransferase after neonatal 6-hydroxydopamine lesions.

    PubMed

    Slotkin, Theodore A; Ryde, Ian T; Wrench, Nicola; Card, Jennifer A; Seidler, Frederic J

    2009-01-01

    Acetylcholinesterase (AChE) is postulated to play a nonenzymatic role in the development of neuritic projections. We gave the specific neurotoxin, 6-OHDA to rats on postnatal day (PN) 1, a treatment that destroys noradrenergic nerve terminals in the forebrain while producing reactive sprouting in the brainstem. AChE showed profound decreases in the forebrain that persisted in males over the entire phase of major synaptogenesis, from PN4 through PN21; in the brainstem, AChE was increased. Parallel examinations of choline acetyltransferase, an enzymatic marker for cholinergic nerve terminals, showed a different pattern of 6-OHDA-induced alterations, with initial decreases in both forebrain and brainstem in males and regression toward normal by PN21; females were far less affected. The sex differences are in accord with the greater plasticity of the female brain and its more rapid recovery from neurotoxic injury; our findings indicate that these differences are present well before puberty. These results support the view that AChE is involved in neurite formation, unrelated to its enzymatic role in cholinergic neurotransmission. Further, the results for choline acetyltransferase indicate that early depletion of norepinephrine compromises development of acetylcholine systems, consistent with a trophic role for this neurotransmitter. PMID:19452616

  9. Chloroplast-encoded serotonin N-acetyltransferase in the red alga Pyropia yezoensis: gene transition to the nucleus from chloroplasts.

    PubMed

    Byeon, Yeong; Yool Lee, Hyoung; Choi, Dong-Woog; Back, Kyoungwhan

    2015-02-01

    Melatonin biosynthesis involves the N-acetylation of arylalkylamines such as serotonin, which is catalysed by serotonin N-acetyltransferase (SNAT), the penultimate enzyme of melatonin biosynthesis in both animals and plants. Here, we report the functional characterization of a putative N-acetyltransferase gene in the chloroplast genome of the alga laver (Pyropia yezoensis, formerly known as Porphyra yezoensis) with homology to the rice SNAT gene. To confirm that the putative Pyropia yezoensis SNAT (PySNAT) gene encodes an SNAT, we cloned the full-length chloroplastidic PySNAT gene by PCR and purified the recombinant PySNAT protein from Escherichia coli. PySNAT was 174 aa and had 50% amino acid identity with cyanobacteria SNAT. Purified recombinant PySNAT showed a peak activity at 55 °C with a K m of 467 µM and V max of 28 nmol min-1 mg(-1) of protein. Unlike other plant SNATs, PySNAT localized to the cytoplasm due to a lack of N-terminal chloroplast transit peptides. Melatonin was present at 0.16ng g(-1) of fresh mass but increased during heat stress. Phylogenetic analysis of the sequence suggested that PySNAT has evolved from the cyanobacteria SNAT gene via endosymbiotic gene transfer. Additionally, the chloroplast transit peptides of plant SNATs were acquired 1500 million years ago, concurrent with the appearance of green algae.

  10. The UmGcn5 gene encoding histone acetyltransferase from Ustilago maydis is involved in dimorphism and virulence.

    PubMed

    González-Prieto, Juan Manuel; Rosas-Quijano, Raymundo; Domínguez, Angel; Ruiz-Herrera, José

    2014-10-01

    We isolated a gene encoding a histone acetyltransferase from Ustilago maydis (DC.) Cda., which is orthologous to the Saccharomyces cerevisiae GCN5 gene. The gene was isolated from genomic clones identified by their specific hybridization to a gene fragment obtained by the polymerase chain reaction (PCR). This gene (Umgcn5; um05168) contains an open reading frame (ORF) of 1421bp that encodes a putative protein of 473 amino acids with a Mr. of 52.6kDa. The protein exhibits a high degree of homology with histone acetyltransferases from different organisms. Null a2b2 ΔUmgcn5 mutants were constructed by substitution of the region encoding the catalytic site with a hygromycin B resistance cassette. Null a1b1 ΔUmgcn5 mutants were isolated from genetic crosses of a2b2 ΔUmgcn5 and a1b1 wild-type strains in maize. Mutants displayed a slight reduction in growth rate under different conditions, and were more sensitive than the wild type to stress conditions, but more important, they grew as long mycelial cells, and formed fuzz-like colonies under all conditions where wild-type strains grew in the yeast-like morphology and formed smooth colonies. This phenotype was not reverted by cAMP addition. Mutants were not virulent to maize plants, and were unable to form teliospores. These phenotypic alterations of the mutants were reverted by their transformation with the wild-type gene.

  11. Biochemical characteristics of a novel vegetative tissue geraniol acetyltransferase from a monoterpene oil grass (Palmarosa, Cymbopogon martinii var. Motia) leaf.

    PubMed

    Sharma, Pankaj K; Sangwan, Neelam S; Bose, Subir K; Sangwan, Rajender S

    2013-04-01

    Plants synthesize volatile alcohol esters on environmental insult or as metabolic induction during flower/fruit development. However, essential oil plants constitutively produce them as the oil constituents. Their synthesis is catalyzed by BAHD family enzymes called alcohol acyltransferases (AATs). However, no AAT has been characterized from plant foliage synthesizing acyclic monoterpenoids containing essential oils. Therefore, we have purified and biochemically characterized a geraniol: acetyl coenzyme A acetyltransferase (GAAT) from Palmarosa aroma grass (Cymbopogon martinii) leaf. MALDI-assisted proteomic study of the 43kDa monomeric enzyme revealed its sequence motif novelties e.g. relaxed conservation at Phe and Trp in DFGWG'. This suggests permissiveness of variations in the conserved motif without loss of catalytic ability. Also, some new conserved/semi-conserved motifs of AATs were recognized. The GAAT k(cat)/K(m) values (300-700M(-1)s(-1)) were low (a generic characteristic for secondary metabolism enzyme) but higher than those of some floral AATs. Wide substrate acceptability for catalyzing acetylation of diverse primary alcohols (chain of ≥C(6)) implied its catalytic description as a 'primary aliphatic alcohol acetyltransferase'. It signifies metabolic ability to deliver diverse aroma esters, should the acceptor alcohols be available in planta. To our knowledge, this is the first report of detailed kinetics of a vegetal monoterpenol acyltransferase.

  12. N-acetylglucosamine sensing by a GCN5-related N-acetyltransferase induces transcription via chromatin histone acetylation in fungi

    PubMed Central

    Su, Chang; Lu, Yang; Liu, Haoping

    2016-01-01

    N-acetylglucosamine (GlcNAc) exists ubiquitously as a component of the surface on a wide range of cells, from bacteria to humans. Many fungi are able to utilize environmental GlcNAc to support growth and induce cellular development, a property important for their survival in various host niches. However, how the GlcNAc signal is sensed and subsequently transduced is largely unknown. Here, we identify a gene that is essential for GlcNAc signalling (NGS1) in Candida albicans, a commensal and pathogenic yeast of humans. Ngs1 can bind GlcNAc through the N-terminal β-N-acetylglucosaminidase homology domain. This binding activates N-acetyltransferase activity in the C-terminal GCN5-related N-acetyltransferase domain, which is required for GlcNAc-induced promoter histone acetylation and transcription. Ngs1 is targeted to the promoters of GlcNAc-inducible genes constitutively by the transcription factor Rep1. Ngs1 is conserved in diverse fungi that have GlcNAc catabolic genes. Thus, fungi use Ngs1 as a GlcNAc-sensor and transducer for GlcNAc-induced transcription. PMID:27694804

  13. Chloroplast-encoded serotonin N-acetyltransferase in the red alga Pyropia yezoensis: gene transition to the nucleus from chloroplasts

    PubMed Central

    Byeon, Yeong; Yool Lee, Hyoung; Choi, Dong-Woog; Back, Kyoungwhan

    2015-01-01

    Melatonin biosynthesis involves the N-acetylation of arylalkylamines such as serotonin, which is catalysed by serotonin N-acetyltransferase (SNAT), the penultimate enzyme of melatonin biosynthesis in both animals and plants. Here, we report the functional characterization of a putative N-acetyltransferase gene in the chloroplast genome of the alga laver (Pyropia yezoensis, formerly known as Porphyra yezoensis) with homology to the rice SNAT gene. To confirm that the putative Pyropia yezoensis SNAT (PySNAT) gene encodes an SNAT, we cloned the full-length chloroplastidic PySNAT gene by PCR and purified the recombinant PySNAT protein from Escherichia coli. PySNAT was 174 aa and had 50% amino acid identity with cyanobacteria SNAT. Purified recombinant PySNAT showed a peak activity at 55 °C with a K m of 467 µM and V max of 28 nmol min–1 mg–1 of protein. Unlike other plant SNATs, PySNAT localized to the cytoplasm due to a lack of N-terminal chloroplast transit peptides. Melatonin was present at 0.16ng g–1 of fresh mass but increased during heat stress. Phylogenetic analysis of the sequence suggested that PySNAT has evolved from the cyanobacteria SNAT gene via endosymbiotic gene transfer. Additionally, the chloroplast transit peptides of plant SNATs were acquired 1500 million years ago, concurrent with the appearance of green algae. PMID:25183745

  14. Broad-band spectrophotometry of HAT-P-32 b: search for a scattering signature in the planetary spectrum

    NASA Astrophysics Data System (ADS)

    Mallonn, M.; Bernt, I.; Herrero, E.; Hoyer, S.; Kirk, J.; Wheatley, P. J.; Seeliger, M.; Mackebrandt, F.; von Essen, C.; Strassmeier, K. G.; Granzer, T.; Künstler, A.; Dhillon, V. S.; Marsh, T. R.; Gaitan, J.

    2016-11-01

    Multicolour broad-band transit observations offer the opportunity to characterize the atmosphere of an extrasolar planet with small- to medium-sized telescopes. One of the most favourable targets is the hot Jupiter HAT-P-32 b. We combined 21 new transit observations of this planet with 36 previously published light curves for a homogeneous analysis of the broad-band transmission spectrum from the Sloan u' band to the Sloan z' band. Our results rule out cloud-free planetary atmosphere models of solar metallicity. Furthermore, a discrepancy at reddest wavelengths to previously published results makes a recent tentative detection of a scattering feature less likely. Instead, the available spectral measurements of HAT-P-32 b favour a completely flat spectrum from the near-UV to the near-IR. A plausible interpretation is a thick cloud cover at high altitudes.

  15. A Damage Tolerance Comparison of Composite Hat-Stiffened and Honeycomb Sandwich Structure for Launch Vehicle Interstage Applications

    NASA Technical Reports Server (NTRS)

    Nettles, A. T.

    2011-01-01

    In this study, a direct comparison of the compression-after-impact (CAI) strength of impact-damaged, hat-stiffened and honeycomb sandwich structure for launch vehicle use was made. The specimens used consisted of small substructure designed to carry a line load of approx..3,000 lb/in. Damage was inflicted upon the specimens via drop weight impact. Infrared thermography was used to examine the extent of planar damage in the specimens. The specimens were prepared for compression testing to obtain residual compression strength versus damage severity curves. Results show that when weight of the structure is factored in, both types of structure had about the same CAI strength for a given damage level. The main difference was that the hat-stiffened specimens exhibited a multiphase failure whereas the honeycomb sandwich structure failed catastrophically.

  16. Compressive Strength of 24S-T Aluminum-alloy Flat Panels with Longitudinal Formed Hat-section Stiffeners

    NASA Technical Reports Server (NTRS)

    Schuette, Evan H; Barab, Sual; Mccracken, Howard L

    1946-01-01

    Results are presented for a part of a test program on 24S-T aluminum alloy flat compression panels with longitudinal formed hat-section stiffeners. This part of the program is concerned with panels in which the thickness of the stiffener materials is 0.625 times the skin thickness. The results, presented in tabular and graphical form, show the effect of the relative dimensions of the panel on the buckling stress and the average stress at maximum load. Comparative envelope curves are presented for hat-stiffened and Z-stiffened panels having the same ratio of stiffener thickness to sheet thickness. These curves provide some indication of the relative structural efficiencies of the two types of panel.

  17. Design and evaluation of a foam-filled hat-stiffened panel concept for aircraft primary structural applications

    NASA Technical Reports Server (NTRS)

    Ambur, Damodar R.

    1995-01-01

    A structurally efficient hat-stiffened panel concept that utilizes a structural foam as stiffener core has been designed for aircraft primary structural applications. This stiffener concept utilizes a manufacturing process that can be adapted readily to grid-stiffened structural configurations which possess inherent damage tolerance characteristics due to their multiplicity of load paths. The foam-filled hat-stiffener concept in a prismatically stiffened panel configuration is more efficient than most other stiffened panel configurations in a load range that is typical for both fuselage and wing structures. The prismatically stiffened panel concept investigated here has been designed using AS4/3502 preimpregnated tape and Rohacell foam core and evaluated for its buckling and postbuckling behavior with and without low-speed impact damage. The results from single-stiffener and multi-stiffener specimens suggest that this structural concept responds to loading as anticipated and has good damage tolerance characteristics.

  18. Broad-band spectrophotometry of HAT-P-32 b: Search for a scattering signature in the planetary spectrum

    NASA Astrophysics Data System (ADS)

    Mallonn, M.; Bernt, I.; Herrero, E.; Hoyer, S.; Kirk, J.; Wheatley, P. J.; Seeliger, M.; Mackebrandt, F.; von Essen, C.; Strassmeier, K. G.; Granzer, T.; Künstler, A.; Dhillon, V. S.; Marsh, T. R.; Gaitan, J.

    2016-08-01

    Multi-colour broad-band transit observations offer the opportunity to characterise the atmosphere of an extrasolar planet with small- to medium-sized telescopes. One of the most favourable targets is the hot Jupiter HAT-P-32 b. We combined 21 new transit observations of this planet with 36 previously published light curves for a homogeneous analysis of the broad-band transmission spectrum from the Sloan u' band to the Sloan z' band. Our results rule out cloud-free planetary atmosphere models of solar metallicity. Furthermore, a discrepancy at reddest wavelengths to previously published results makes a recent tentative detection of a scattering feature less likely. Instead, the available spectral measurements of HAT-P-32 b favour a completely flat spectrum from the near-UV to the near-IR. A plausible interpretation is a thick cloud cover at high altitudes.

  19. Molecular Structure of WlbB, a Bacterial N-Acetyltransferase Involved in the Biosynthesis of 2,3-Diacetamido-2,3-dideoxy-d-mannuronic Acid

    SciTech Connect

    Thoden, James B.; Holden, Hazel M.

    2010-09-08

    The pathogenic bacteria Pseudomonas aeruginosa and Bordetella pertussis contain in their outer membranes the rare sugar 2,3-diacetamido-2,3-dideoxy-D-mannuronic acid. Five enzymes are required for the biosynthesis of this sugar starting from UDP-N-acetylglucosamine. One of these, referred to as WlbB, is an N-acetyltransferase that converts UDP-2-acetamido-3-amino-2,3-dideoxy-D-glucuronic acid (UDP-GlcNAc3NA) to UDP-2,3-diacetamido-2,3-dideoxy-D-glucuronic acid (UDP-GlcNAc3NAcA). Here we report the three-dimensional structure of WlbB from Bordetella petrii. For this analysis, two ternary structures were determined to 1.43 {angstrom} resolution: one in which the protein was complexed with acetyl-CoA and UDP and the second in which the protein contained bound CoA and UDP-GlcNAc3NA. WlbB adopts a trimeric quaternary structure and belongs to the L{beta}H superfamily of N-acyltransferases. Each subunit contains 27 {beta}-strands, 23 of which form the canonical left-handed {beta}-helix. There are only two hydrogen bonds that occur between the protein and the GlcNAc3NA moiety, one between O{sup {delta}1} of Asn 84 and the sugar C-3{prime} amino group and the second between the backbone amide group of Arg 94 and the sugar C-5{prime} carboxylate. The sugar C-3{prime} amino group is ideally positioned in the active site to attack the si face of acetyl-CoA. Given that there are no protein side chains that can function as general bases within the GlcNAc3NA binding pocket, a reaction mechanism is proposed for WlbB whereby the sulfur of CoA ultimately functions as the proton acceptor required for catalysis.

  20. Non-syndromic retinitis pigmentosa due to mutations in the mucopolysaccharidosis type IIIC gene, heparan-alpha-glucosaminide N-acetyltransferase (HGSNAT)

    PubMed Central

    Haer-Wigman, Lonneke; Newman, Hadas; Leibu, Rina; Bax, Nathalie M.; Baris, Hagit N; Rizel, Leah; Banin, Eyal; Massarweh, Amir; Roosing, Susanne; Lefeber, Dirk J.; Zonneveld-Vrieling, Marijke N.; Isakov, Ofer; Shomron, Noam; Sharon, Dror; Den Hollander, Anneke I.; Hoyng, Carel B.; Cremers, Frans P.M.; Ben-Yosef, Tamar

    2015-01-01

    Retinitis pigmentosa (RP), the most common form of inherited retinal degeneration, is clinically and genetically heterogeneous and can appear as syndromic or non-syndromic. Mucopolysaccharidosis type IIIC (MPS IIIC) is a lethal disorder, caused by mutations in the heparan-alpha-glucosaminide N-acetyltransferase (HGSNAT) gene and characterized by progressive neurological deterioration, with retinal degeneration as a prominent feature. We identified HGSNAT mutations in six patients with non-syndromic RP. Whole exome sequencing (WES) in an Ashkenazi Jewish Israeli RP patient revealed a novel homozygous HGSNAT variant, c.370A>T, which leads to partial skipping of exon 3. Screening of 66 Ashkenazi RP index cases revealed an additional family with two siblings homozygous for c.370A>T. WES in three Dutch siblings with RP revealed a complex HGSNAT variant, c.[398G>C; 1843G>A] on one allele, and c.1843G>A on the other allele. HGSNAT activity levels in blood leukocytes of patients were reduced compared with healthy controls, but usually higher than those in MPS IIIC patients. All patients were diagnosed with non-syndromic RP and did not exhibit neurological deterioration, or any phenotypic features consistent with MPS IIIC. Furthermore, four of the patients were over 60 years old, exceeding by far the life expectancy of MPS IIIC patients. HGSNAT is highly expressed in the mouse retina, and we hypothesize that the retina requires higher HGSNAT activity to maintain proper function, compared with other tissues associated with MPS IIIC, such as the brain. This report broadens the spectrum of phenotypes associated with HGSNAT mutations and highlights the critical function of HGSNAT in the human retina. PMID:25859010