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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. Comparison of protein acetyltransferase action of CRTAase with the prototypes of HAT.

    PubMed

    Ponnan, Prija; Kumar, Ajit; Singh, Prabhjot; Gupta, Prachi; Joshi, Rini; Gaspari, Marco; 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.

  4. 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

  5. Hat2p recognizes the histone H3 tail to specify the acetylation of the newly synthesized H3/H4 heterodimer by the Hat1p/Hat2p complex

    PubMed Central

    Li, Yang; Zhang, Li; Liu, Tingting; Chai, Chengliang; Fang, Qianglin; Wu, Han; Agudelo Garcia, Paula A.; Han, Zhifu; Zong, Shuai; Yu, You; Zhang, Xinyue; Parthun, Mark R.; Chai, Jijie; Xu, Rui-Ming; Yang, Maojun

    2014-01-01

    Post-translational modifications of histones are significant regulators of replication, transcription, and DNA repair. Particularly, newly synthesized histone H4 in H3/H4 heterodimers becomes acetylated on N-terminal lysine residues prior to its incorporation into chromatin. Previous studies have established that the histone acetyltransferase (HAT) complex Hat1p/Hat2p medicates this modification. However, the mechanism of how Hat1p/Hat2p recognizes and facilitates the enzymatic activities on the newly assembled H3/H4 heterodimer remains unknown. Furthermore, Hat2p is a WD40 repeat protein, which is found in many histone modifier complexes. However, how the WD40 repeat proteins facilitate enzymatic activities of histone modification enzymes is unclear. In this study, we first solved the high-resolution crystal structure of a Hat1p/Hat2p/CoA/H4 peptide complex and found that the H4 tail interacts with both Hat1p and Hat2p, by which substrate recruitment is facilitated. We further discovered that H3 N-terminal peptides can bind to the Hat2p WD40 domain and solved the structure of the Hat1p/Hat2p/CoA/H4/H3 peptide complex. Moreover, the interaction with Hat2p requires unmodified Arg2/Lys4 and Lys9 on the H3 tail, suggesting a novel model to specify the activity of Hat1p/Hat2p toward newly synthesized H3/H4 heterodimers. Together, our study demonstrated the substrate recognition mechanism by the Hat1p/Hat2p complex, which is critical for DNA replication and other chromatin remodeling processes. PMID:24835250

  6. Synthesis of isothiazol-3-one derivatives as inhibitors of histone acetyltransferases (HATs).

    PubMed

    Gorsuch, Stephen; Bavetsias, Vassilios; Rowlands, Martin G; Aherne, G Wynne; Workman, Paul; Jarman, Michael; McDonald, Edward

    2009-01-15

    High-throughput screening led to the identification of isothiazolones 1 and 2 as inhibitors of histone acetyltransferase (HAT) with IC50s of 3 microM and 5 microM, respectively. Analogues of these hit compounds with variations of the N-phenyl group, and with variety of substituents at C-4, C-5 of the thiazolone ring, were prepared and assayed for inhibition of the HAT enzyme PCAF. Potency is modestly favoured when the N-aryl group is electron deficient (4-pyridyl derivative 10 has IC(50)=1.5 microM); alkyl substitution at C-4 has little effect, whilst similar substitution at C-5 causes a significant drop in potency. The ring-fused compound 38 has activity (IC(50)=6.1 microM) to encourage further exploration of this bicyclic structure. The foregoing SAR is consistent with an inhibitory mechanism involving cleavage of the S-N bond of the isothiazolone ring by a catalytically important thiol residue.

  7. The ADA Complex Is a Distinct Histone Acetyltransferase Complex in Saccharomyces cerevisiae

    PubMed Central

    Eberharter, Anton; Sterner, David E.; Schieltz, David; Hassan, Ahmed; Yates, John R.; Berger, Shelley L.; Workman, Jerry L.

    1999-01-01

    We have identified two Gcn5-dependent histone acetyltransferase (HAT) complexes from Saccharomyces cerevisiae, the 0.8-MDa ADA complex and the 1.8-MDa SAGA complex. The SAGA (Spt-Ada-Gcn5-acetyltransferase) complex contains several subunits which also function as part of other protein complexes, including a subset of TATA box binding protein-associated factors (TAFIIs) and Tra1. These observations raise the question of whether the 0.8-MDa ADA complex is a subcomplex of SAGA or whether it is a distinct HAT complex that also shares subunits with SAGA. To address this issue, we sought to determine if the ADA complex contained subunits that are not present in the SAGA complex. In this study, we report the purification of the ADA complex over 10 chromatographic steps. By a combination of mass spectrometry analysis and immunoblotting, we demonstrate that the adapter proteins Ada2, Ada3, and Gcn5 are indeed integral components of ADA. Furthermore, we identify the product of the S. cerevisiae gene YOR023C as a novel subunit of the ADA complex and name it Ahc1 for ADA HAT complex component 1. Biochemical functions of YOR023C have not been reported. However, AHC1 in high copy numbers suppresses the cold sensitivity caused by particular mutations in HTA1 (I. Pinto and F. Winston, personal communication), which encodes histone H2A (J. N. Hirschhorn et al., Mol. Cell. Biol. 15:1999–2009, 1995). Deletion of AHC1 disrupted the integrity of the ADA complex but did not affect SAGA or give rise to classic Ada− phenotypes. These results indicate that Gcn5, Ada2, and Ada3 function as part of a unique HAT complex (ADA) and represent shared subunits between this complex and SAGA. PMID:10490601

  8. Activation Domain-Specific and General Transcription Stimulation by Native Histone Acetyltransferase Complexes

    PubMed Central

    Ikeda, Keiko; Steger, David J.; Eberharter, Anton; Workman, Jerry L.

    1999-01-01

    Recent progress in identifying the catalytic subunits of histone acetyltransferase (HAT) complexes has implicated histone acetylation in the regulation of transcription. Here, we have analyzed the function of two native yeast HAT complexes, SAGA (Spt-Ada-Gcn5 Acetyltransferase) and NuA4 (nucleosome acetyltransferase of H4), in activating transcription from preassembled nucleosomal array templates in vitro. Each complex was tested for the ability to enhance transcription driven by GAL4 derivatives containing either acidic, glutamine-rich, or proline-rich activation domains. On nucleosomal array templates, the SAGA complex selectively stimulates transcription driven by the VP16 acidic activation domain in an acetyl coenzyme A-dependent manner. In contrast, the NuA4 complex facilitates transcription mediated by any of the activation domains tested if allowed to preacetylate the nucleosomal template, indicating a general stimulatory effect of histone H4 acetylation. However, when the extent of acetylation by NuA4 is limited, the complex also preferentially stimulates VP16-driven transcription. SAGA and NuA4 interact directly with the VP16 activation domain but not with a glutamine-rich or proline-rich activation domain. These data suggest that recruitment of the SAGA and NuA4 HAT complexes by the VP16 activation domain contributes to HAT-dependent activation. In addition, extensive H4/H2B acetylation by NuA4 leads to a general activation of transcription, which is independent of activator-NuA4 interactions. PMID:9858608

  9. Histone Acetyltransferase Complexes Can Mediate Transcriptional Activation by the Major Glucocorticoid Receptor Activation Domain

    PubMed Central

    Wallberg, Annika E.; Neely, Kristen E.; Gustafsson, Jan-Åke; Workman, Jerry L.; Wright, Anthony P. H.; Grant, Patrick A.

    1999-01-01

    Previous studies have shown that the Ada adapter proteins are important for glucocorticoid receptor (GR)-mediated gene activation in yeast. The N-terminal transactivation domain of GR, τ1, is dependent upon Ada2, Ada3, and Gcn5 for transactivation in vitro and in vivo. Using in vitro techniques, we demonstrate that the GR-τ1 interacts directly with the native Ada containing histone acetyltransferase (HAT) complex SAGA but not the related Ada complex. Mutations in τ1 that reduce τ1 transactivation activity in vivo lead to a reduced binding of τ1 to the SAGA complex and conversely, mutations increasing the transactivation activity of τ1 lead to an increased binding of τ1 to SAGA. In addition, the Ada-independent NuA4 HAT complex also interacts with τ1. GAL4-τ1-driven transcription from chromatin templates is stimulated by SAGA and NuA4 in an acetyl coenzyme A-dependent manner. Low-activity τ1 mutants reduce SAGA- and NuA4-stimulated transcription while high-activity τ1 mutants increase transcriptional activation, specifically from chromatin templates. Our results demonstrate that the targeting of native HAT complexes by the GR-τ1 activation domain mediates transcriptional stimulation from chromatin templates. PMID:10454542

  10. 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

  11. 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.

  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. The Enok acetyltransferase complex interacts with Elg1 and negatively regulates PCNA unloading to promote the G1/S transition

    PubMed Central

    Huang, Fu; Saraf, Anita; Florens, Laurence; Kusch, Thomas; Swanson, Selene K.; Szerszen, Leanne T.; Li, Ge; Dutta, Arnob; Washburn, Michael P.; Abmayr, Susan M.; Workman, Jerry L.

    2016-01-01

    KAT6 histone acetyltransferases (HATs) are highly conserved in eukaryotes and are involved in cell cycle regulation. However, information regarding their roles in regulating cell cycle progression is limited. Here, we report the identification of subunits of the Drosophila Enok complex and demonstrate that all subunits are important for its HAT activity. We further report a novel interaction between the Enok complex and the Elg1 proliferating cell nuclear antigen (PCNA)-unloader complex. Depletion of Enok in S2 cells resulted in a G1/S cell cycle block, and this block can be partially relieved by depleting Elg1. Furthermore, depletion of Enok reduced the chromatin-bound levels of PCNA in both S2 cells and early embryos, suggesting that the Enok complex may interact with the Elg1 complex and down-regulate its PCNA-unloading function to promote the G1/S transition. Supporting this hypothesis, depletion of Enok also partially rescued the endoreplication defects in Elg1-depleted nurse cells. Taken together, our study provides novel insights into the roles of KAT6 HATs in cell cycle regulation through modulating PCNA levels on chromatin. PMID:27198229

  14. 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…

  15. Histone acetyltransferases: challenges in targeting bi-substrate enzymes.

    PubMed

    Wapenaar, Hannah; Dekker, Frank J

    2016-01-01

    Histone acetyltransferases (HATs) are epigenetic enzymes that install acetyl groups onto lysine residues of cellular proteins such as histones, transcription factors, nuclear receptors, and enzymes. HATs have been shown to play a role in diseases ranging from cancer and inflammatory diseases to neurological disorders, both through acetylations of histone proteins and non-histone proteins. Several HAT inhibitors, like bi-substrate inhibitors, natural product derivatives, small molecules, and protein-protein interaction inhibitors, have been developed. Despite their potential, a large gap remains between the biological activity of inhibitors in in vitro studies and their potential use as therapeutic agents. To bridge this gap, new potent HAT inhibitors with improved properties need to be developed. However, several challenges have been encountered in the investigation of HATs and HAT inhibitors that hinder the development of new HAT inhibitors. HATs have been shown to function in complexes consisting of many proteins. These complexes play a role in the activity and target specificity of HATs, which limits the translation of in vitro to in vivo experiments. The current HAT inhibitors suffer from undesired properties like anti-oxidant activity, reactivity, instability, low potency, or lack of selectivity between HAT subtypes and other enzymes. A characteristic feature of HATs is that they are bi-substrate enzymes that catalyze reactions between two substrates: the cofactor acetyl coenzyme A (Ac-CoA) and a lysine-containing substrate. This has important-but frequently overlooked-consequences for the determination of the inhibitory potency of small molecule HAT inhibitors and the reproducibility of enzyme inhibition experiments. We envision that a careful characterization of molecular aspects of HATs and HAT inhibitors, such as the HAT catalytic mechanism and the enzyme kinetics of small molecule HAT inhibitors, will greatly improve the development of potent and

  16. Histone acetyltransferase (HAT) activity of p300 modulates human T lymphotropic virus type 1 p30{sup II}-mediated repression of LTR transcriptional activity

    SciTech Connect

    Michael, Bindhu; Nair, Amrithraj M.; Datta, Antara; Hiraragi, Hajime; Ratner, Lee; Lairmore, Michael D. . E-mail: lairmore.1@osu.edu

    2006-10-25

    Human T-lymphotropic virus type-1 (HTLV-1) is a deltaretrovirus that causes adult T cell leukemia/lymphoma, and is implicated in a variety of lymphocyte-mediated inflammatory disorders. HTLV-1 provirus has regulatory and accessory genes in four pX open reading frames. HTLV-1 pX ORF-II encodes two proteins, p13{sup II} and p30{sup II}, which are incompletely defined in virus replication or pathogenesis. We have demonstrated that pX ORF-II mutations block virus replication in vivo and that ORF-II encoded p30{sup II}, a nuclear-localizing protein that binds with CREB-binding protein (CBP)/p300, represses CREB and Tax responsive element (TRE)-mediated transcription. Herein, we have identified p30{sup II} motifs important for p300 binding and in regulating TRE-mediated transcription in the absence and presence of HTLV-1 provirus. Within amino acids 100-179 of p30{sup II}, a region important for repression of LTR-mediated transcription, we identified a single lysine residue at amino acid 106 (K3) that significantly modulates the ability of p30{sup II} to repress TRE-mediated transcription. Exogenous p300, in a dose-responsive manner, reverses p30{sup II}-dependent repression of TRE-mediated transcription, in the absence or presence of the provirus, In contrast to wild type p300, p300 HAT mutants (defective in histone acetyltransferase activity) only partially rescued p30{sup II}-mediated LTR repression. Deacetylation by histone deacetylase-1 (HDAC-1) enhanced p30{sup II}-mediated LTR repression, while inhibition of deacetylation by trichostatin A decreases p30{sup II}-mediated LTR repression. Collectively, our data indicate that HTLV-1 p30{sup II} modulates viral gene expression in a cooperative manner with p300-mediated acetylation.

  17. 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...

  18. N-Terminal Domain of Nuclear IL-1α Shows Structural Similarity to the C-Terminal Domain of Snf1 and Binds to the HAT/Core Module of the SAGA Complex

    PubMed Central

    Zamostna, Blanka; Novak, Josef; Vopalensky, Vaclav; Masek, Tomas; Burysek, Ladislav; Pospisek, Martin

    2012-01-01

    Interleukin-1α (IL-1α) is a proinflammatory cytokine and a key player in host immune responses in higher eukaryotes. IL-1α has pleiotropic effects on a wide range of cell types, and it has been extensively studied for its ability to contribute to various autoimmune and inflammation-linked disorders, including rheumatoid arthritis, Alzheimer’s disease, systemic sclerosis and cardiovascular disorders. Interestingly, a significant proportion of IL-1α is translocated to the cell nucleus, in which it interacts with histone acetyltransferase complexes. Despite the importance of IL-1α, little is known regarding its binding targets and functions in the nucleus. We took advantage of the histone acetyltransferase (HAT) complexes being evolutionarily conserved from yeast to humans and the yeast SAGA complex serving as an epitome of the eukaryotic HAT complexes. Using gene knock-out technique and co-immunoprecipitation of the IL-1α precursor with TAP-tagged subunits of the yeast HAT complexes, we mapped the IL-1α-binding site to the HAT/Core module of the SAGA complex. We also predicted the 3-D structure of the IL-1α N-terminal domain, and by employing structure similarity searches, we found a similar structure in the C-terminal regulatory region of the catalytic subunit of the AMP-activated/Snf1 protein kinases, which interact with HAT complexes both in mammals and yeast, respectively. This finding is further supported with the ability of the IL-1α precursor to partially rescue growth defects of snf1Δ yeast strains on media containing 3-Amino-1,2,4-triazole (3-AT), a competitive inhibitor of His3. Finally, the careful evaluation of our data together with other published data in the field allows us to hypothesize a new function for the ADA complex in SAGA complex assembly. PMID:22879895

  19. 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

  20. 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

  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 Novel SLIK Histone Acetyltransferase Complex Functions in the Yeast Retrograde Response Pathway

    PubMed Central

    Pray-Grant, Marilyn G.; Schieltz, David; McMahon, Stacey J.; Wood, Jennifer M.; Kennedy, Erin L.; Cook, Richard G.; Workman, Jerry L.; Yates III, John R.; Grant, Patrick A.

    2002-01-01

    The SAGA complex is a conserved histone acetyltransferase-coactivator that regulates gene expression in Saccharomyces cerevisiae. SAGA contains a number of subunits known to function in transcription including Spt and Ada proteins, the Gcn5 acetyltransferase, a subset of TATA-binding-protein-associated factors (TAFIIs), and Tra1. Here we report the identification of SLIK (SAGA-like), a complex related in composition to SAGA. Notably SLIK uniquely contains the protein Rtg2, linking the function of SLIK to the retrograde response pathway. Yeast harboring mutations in both SAGA and SLIK complexes displays synthetic phenotypes more severe than those of yeast with mutation of either complex alone. We present data indicating that distinct forms of the SAGA complex may regulate specific subsets of genes and that SAGA and SLIK have multiple partly overlapping activities, which play a critical role in transcription by RNA polymerase II. PMID:12446794

  3. The transcriptional histone acetyltransferase cofactor TRRAP associates with the MRN repair complex and plays a role in DNA double-strand break repair.

    PubMed

    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.

  4. Crosstalk between NSL histone acetyltransferase and MLL/SET complexes: NSL complex functions in promoting histone H3K4 di-methylation activity by MLL/SET complexes.

    PubMed

    Zhao, Xiaoming; Su, Jiaming; Wang, Fei; Liu, Da; Ding, Jian; Yang, Yang; Conaway, Joan W; Conaway, Ronald C; Cao, Lingling; Wu, Donglu; Wu, Min; Cai, Yong; Jin, Jingji

    2013-11-01

    hMOF (MYST1), a histone acetyltransferase (HAT), forms at least two distinct multiprotein complexes in human cells. The male specific lethal (MSL) HAT complex plays a key role in dosage compensation in Drosophila and is responsible for histone H4K16ac in vivo. We and others previously described a second hMOF-containing HAT complex, the non-specific lethal (NSL) HAT complex. The NSL complex has a broader substrate specificity, can acetylate H4 on K16, K5, and K8. The WD (tryptophan-aspartate) repeat domain 5 (WDR5) and host cell factor 1 (HCF1) are shared among members of the MLL/SET (mixed-lineage leukemia/set-domain containing) family of histone H3K4 methyltransferase complexes. The presence of these shared subunits raises the possibility that there are functional links between these complexes and the histone modifications they catalyze; however, the degree to which NSL and MLL/SET influence one another's activities remains unclear. Here, we present evidence from biochemical assays and knockdown/overexpression approaches arguing that the NSL HAT promotes histone H3K4me2 by MLL/SET complexes by an acetylation-dependent mechanism. In genomic experiments, we identified a set of genes including ANKRD2, that are affected by knockdown of both NSL and MLL/SET subunits, suggested they are co-regulated by NSL and MLL/SET complexes. In ChIP assays, we observe that depletion of the NSL subunits hMOF or NSL1 resulted in a significant reduction of both H4K16ac and H3K4me2 in the vicinity of the ANKRD2 transcriptional start site proximal region. However, depletion of RbBP5 (a core component of MLL/SET complexes) only reduced H3K4me2 marks, but not H4K16ac in the same region of ANKRD2, consistent with the idea that NSL acts upstream of MLL/SET to regulate H3K4me2 at certain promoters, suggesting coordination between NSL and MLL/SET complexes is involved in transcriptional regulation of certain genes. Taken together, our results suggest a crosstalk between the NSL and MLL

  5. 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.

  6. Histone H3 specific acetyltransferases are essential for cell cycle progression

    PubMed Central

    Howe, LeAnn; Auston, Darryl; Grant, Patrick; John, Sam; Cook, Richard G.; Workman, Jerry L.; Pillus, Lorraine

    2001-01-01

    Longstanding observations suggest that acetylation and/or amino-terminal tail structure of histones H3 and H4 are critical for eukaryotic cells. For Saccharomyces cerevisiae, loss of a single H4-specific histone acetyltransferase (HAT), Esa1p, results in cell cycle defects and death. In contrast, although several yeast HAT complexes preferentially acetylate histone H3, the catalytic subunits of these complexes are not essential for viability. To resolve the apparent paradox between the significance of H3 versus H4 acetylation, we tested the hypothesis that H3 modification is essential, but is accomplished through combined activities of two enzymes. We observed that Sas3p and Gcn5p HAT complexes have overlapping patterns of acetylation. Simultaneous disruption of SAS3, the homolog of the MOZ leukemia gene, and GCN5, the hGCN5/PCAF homolog, is synthetically lethal due to loss of acetyltransferase activity. This key combination of activities is specific for these two HATs because neither is synthetically lethal with mutations of other MYST family or H3-specific acetyltransferases. Further, the combined loss of GCN5 and SAS3 functions results in an extensive, global loss of H3 acetylation and arrest in the G2/M phase of the cell cycle. The strikingly similar effect of loss of combined essential H3 HAT activities and the loss of a single essential H4 HAT underscores the fundamental biological significance of each of these chromatin-modifying activities. PMID:11731478

  7. 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

  8. 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.

  9. Regulation of KAT6 Acetyltransferases and Their Roles in Cell Cycle Progression, Stem Cell Maintenance, and Human Disease

    PubMed Central

    Huang, Fu

    2016-01-01

    The lysine acetyltransferase 6 (KAT6) histone acetyltransferase (HAT) complexes are highly conserved from yeast to higher organisms. They acetylate histone H3 and other nonhistone substrates and are involved in cell cycle regulation and stem cell maintenance. In addition, the human KAT6 HATs are recurrently mutated in leukemia and solid tumors. Therefore, it is important to understand the mechanisms underlying the regulation of KAT6 HATs and their roles in cell cycle progression. In this minireview, we summarize the identification and analysis of the KAT6 complexes and discuss the regulatory mechanisms governing their enzymatic activities and substrate specificities. We further focus on the roles of KAT6 HATs in regulating cell proliferation and stem cell maintenance and review recent insights that aid in understanding their involvement in human diseases. PMID:27185879

  10. 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.

  11. Epigenetic Modulation using Small Molecules - Targeting Histone Acetyltransferases in Disease.

    PubMed

    Richters, André; Koehler, Angela N

    2017-02-23

    Histone acetyltransferases (HATs) are epigenetic drivers that catalyze the acetyl transfer from acetyl-CoA to lysines of both histone and non-histone substrates and thereby induce transcription either by chromatin remodeling or direct transcription factor activation. Histone deacetylases (HDACs) conduct the reverse reaction to counter HAT activity. Physiological processes such as cell cycle progression or apoptosis require a thoroughly balanced equilibrium of the interplay between acetylation and deacetylation processes to maintain or, if required, alter the global acetylome status. Aberrant HAT activity has recently been demonstrated to play a crucial role in the progression of various diseases such as prostate, lung, and colon cancers as well as glioblastomas and neurodegenerative diseases. Recent investigations have aimed for the identification of HAT modulators to further decipher the complexity of acetyl transferase related signaling cascades and discover potential leads for drug design approaches. HDACs have been extensively characterized and targeted by small molecules, including four FDA-approved HDAC inhibitors; in contrast, HATs have not been active targets for therapeutic development. This review will summarize the status of HAT associated diseases and the arsenal of currently known and available HAT inhibitors with respect to their discovery, further improvements, and current applications.

  12. 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.

  13. Host Cell Factor and an Uncharacterized SANT Domain Protein Are Stable Components of ATAC, a Novel dAda2A/dGcn5-Containing Histone Acetyltransferase Complex in Drosophila

    PubMed Central

    Guelman, Sebastián; Suganuma, Tamaki; Florens, Laurence; Swanson, Selene K.; Kiesecker, Cheri L.; Kusch, Thomas; Anderson, Scott; Yates, John R.; Washburn, Michael P.; Abmayr, Susan M.; Workman, Jerry L.

    2006-01-01

    Gcn5 is a conserved histone acetyltransferase (HAT) found in a number of multisubunit complexes from Saccharomyces cerevisiae, mammals, and flies. We previously identified Drosophila melanogaster homologues of the yeast proteins Ada2, Ada3, Spt3, and Tra1 and showed that they associate with dGcn5 to form at least two distinct HAT complexes. There are two different Ada2 homologues in Drosophila named dAda2A and dAda2B. dAda2B functions within the Drosophila version of the SAGA complex (dSAGA). To gain insight into dAda2A function, we sought to identify novel components of the complex containing this protein, ATAC (Ada two A containing) complex. Affinity purification and mass spectrometry revealed that, in addition to dAda3 and dGcn5, host cell factor (dHCF) and a novel SANT domain protein, named Atac1 (ATAC component 1), copurify with this complex. Coimmunoprecipitation experiments confirmed that these proteins associate with dGcn5 and dAda2A, but not with dSAGA-specific components such as dAda2B and dSpt3. Biochemical fractionation revealed that ATAC has an apparent molecular mass of 700 kDa and contains dAda2A, dGcn5, dAda3, dHCF, and Atac1 as stable subunits. Thus, ATAC represents a novel histone acetyltransferase complex that is distinct from previously purified Gcn5/Pcaf-containing complexes from yeast and mammalian cells. PMID:16428443

  14. The MOZ histone acetyltransferase in epigenetic signaling and disease.

    PubMed

    Carlson, Samuel; Glass, Karen C

    2014-11-01

    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 action 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.

  15. 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.

  16. A pair of transposon-derived proteins function in a histone acetyltransferase complex for active DNA demethylation

    PubMed Central

    Duan, Cheng-Guo; Wang, Xingang; Xie, Shaojun; Pan, Li; Miki, Daisuke; Tang, Kai; Hsu, Chuan-Chih; Lei, Mingguang; Zhong, Yingli; Hou, Yueh-Ju; Wang, Zhijuan; Zhang, Zhengjing; Mangrauthia, Satendra K; Xu, Huawei; Zhang, Heng; Dilkes, Brian; Tao, W Andy; Zhu, Jian-Kang

    2017-01-01

    Transposons are generally kept silent by epigenetic mechanisms including DNA methylation. Here, we identified a pair of Harbinger transposon-derived proteins (HDPs), HDP1 and HDP2, as anti-silencing factors in Arabidopsis. hdp1 and hdp2 mutants displayed an enhanced silencing of transgenes and some transposons. Phylogenetic analyses revealed that HDP1 and HDP2 were co-domesticated from the Harbinger transposon-encoded transposase and DNA-binding protein, respectively. HDP1 interacts with HDP2 in the nucleus, analogous to their transposon counterparts. Moreover, HDP1 and HDP2 are associated with IDM1, IDM2, IDM3 and MBD7 that constitute a histone acetyltransferase complex functioning in DNA demethylation. HDP2 and the methyl-DNA-binding protein MBD7 share a large set of common genomic binding sites, indicating that they jointly determine the target specificity of the histone acetyltransferase complex. Thus, our data revealed that HDP1 and HDP2 constitute a functional module that has been recruited to a histone acetyltransferase complex to prevent DNA hypermethylation and epigenetic silencing. PMID:27934869

  17. Repression of GCN5 Histone Acetyltransferase Activity via Bromodomain-Mediated Binding and Phosphorylation by the Ku–DNA-Dependent Protein Kinase Complex

    PubMed Central

    Barlev, Nickolai A.; Poltoratsky, Vladimir; Owen-Hughes, Tom; Ying, Carol; Liu, Lin; Workman, Jerry L.; Berger, Shelley L.

    1998-01-01

    GCN5, a putative transcriptional adapter in humans and yeast, possesses histone acetyltransferase (HAT) activity which has been linked to GCN5’s role in transcriptional activation in yeast. In this report, we demonstrate a functional interaction between human GCN5 (hGCN5) and the DNA-dependent protein kinase (DNA-PK) holoenzyme. Yeast two-hybrid screening detected an interaction between the bromodomain of hGCN5 and the p70 subunit of the human Ku heterodimer (p70-p80), which is the DNA-binding component of DNA-PK. Interaction between intact hGCN5 and Ku70 was shown biochemically using recombinant proteins and by coimmunoprecipitation of endogenous proteins following chromatography of HeLa nuclear extracts. We demonstrate that the catalytic subunit of DNA-PK phosphorylates hGCN5 both in vivo and in vitro and, moreover, that the phosphorylation inhibits the HAT activity of hGCN5. These findings suggest a possible regulatory mechanism of HAT activity. PMID:9488450

  18. Yeast Sgf73/Ataxin-7 serves to anchor the deubiquitination module into both SAGA and Slik(SALSA) HAT complexes.

    PubMed

    Lee, Kenneth K; Swanson, Selene K; Florens, Laurence; Washburn, Michael P; Workman, Jerry L

    2009-02-18

    Spinocerebellar ataxia (SCA) is a physically devastating, genetically inherited disorder characterized by abnormal brain function that results in the progressive loss of the ability to coordinate movements. There are many types of SCAs as there are various gene mutations that can cause this disease. SCA types 1-3, 6-10, 12, and 17 result from a trinucleotide repeat expansion in the DNA-coding sequence. Intriguingly, recent work has demonstrated that increased trinucleotde expansions in the SCA7 gene result in defect in the function of the SAGA histone acetyltransferase complex. The SCA7 gene encodes a subunit of the SAGA complex. This subunit is conserved in yeast as the SGF73 gene. We demonstrate that Sgf73 is required to recruit the histone deubiquitination module into both SAGA and the related SliK(SALSA) complex, and to maintain levels of histone ubiquitination, which is necessary for regulation of transcription at a number of genes.

  19. Yeast Sgf73/Ataxin-7 serves to anchor the deubiquitination module into both SAGA and Slik(SALSA) HAT complexes

    PubMed Central

    Lee, Kenneth K; Swanson, Selene K; Florens, Laurence; Washburn, Michael P; Workman, Jerry L

    2009-01-01

    Spinocerebellar ataxia (SCA) is a physically devastating, genetically inherited disorder characterized by abnormal brain function that results in the progressive loss of the ability to coordinate movements. There are many types of SCAs as there are various gene mutations that can cause this disease. SCA types 1–3, 6–10, 12, and 17 result from a trinucleotide repeat expansion in the DNA-coding sequence. Intriguingly, recent work has demonstrated that increased trinucleotde expansions in the SCA7 gene result in defect in the function of the SAGA histone acetyltransferase complex. The SCA7 gene encodes a subunit of the SAGA complex. This subunit is conserved in yeast as the SGF73 gene. We demonstrate that Sgf73 is required to recruit the histone deubiquitination module into both SAGA and the related SliK(SALSA) complex, and to maintain levels of histone ubiquitination, which is necessary for regulation of transcription at a number of genes. PMID:19226466

  20. Anion-π recognition between [M(CN)6](3-) complexes and HAT(CN)6: structural matching and electronic charge density modification.

    PubMed

    Kobylarczyk, Jedrzej; Pinkowicz, Dawid; Srebro-Hooper, Monika; Hooper, James; Podgajny, Robert

    2017-03-14

    Hexacyanidometalates (M = Fe(III), Co(III)) and multisite anion receptor HAT(CN)6 (1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile) recognize each other in acetonitrile solution and self-assemble into the novel molecular networks (PPh4)3[M(CN)6][HAT(CN)6] (M = Fe, 1; Co, 2) and (AsPh4)3[M(CN)6][HAT(CN)6]·2MeCN·H2O (M = Fe, 3; Co, 4). 1-4 contain the stacked columns {[M(CN)6](3-);[HAT(CN)6]}∞ separated by the organic cations. All of the M-C[triple bond, length as m-dash]N vectors point collectively towards the centroids of pyrazine rings on neighboring HAT(CN)6 molecules, with Ncyanidecentroidpyrazine distances that are under 3 Å. The directional character and structural parameters of the new supramolecular synthons correspond to collective triple anion-π interactions between the CN(-) ligands of the metal complexes and the π-deficient areas of HAT(CN)6. Physicochemical characterisation (IR spectroscopy, UV-Vis spectroscopy, cyclic voltammetry) and dispersion-corrected DFT studies reveal the dominating charge-transfer (CT) and polarisation characters of the interactions. The electronic density flow occurs from the CN(-) ligands of [M(CN)6](3-) to the HAT(CN)6 orbital systems and further, toward the peripheral -CN groups of HAT(CN)6. Solid-state DFT calculations determined the total interaction energy of HAT(CN)6 to be ca. -125 kcal mol(-1), which gives ca. -15 kcal mol(-1) per one CN(-)HAT(CN)6 contact after subtraction of the interaction with organic cations. The UV-Vis electronic absorption measurements prove that the intermolecular interactions persist in solution and suggest a 1 : 1 composition of the anion-π {[M(CN)6](3-);[HAT(CN)6]} chromophore, with the formation constant Kadd = (5.8 ± 6) × 10(2) dm(3) mol(-1) and the molar absorption coefficient εadd = 180 ± 9 cm(-1) dm(3) mol(-1) at 600 nm, as estimated from concentration-dependent studies.

  1. 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.

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

    PubMed Central

    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. PMID:26263547

  3. The yeast SAS (something about silencing) protein complex contains a MYST-type putative acetyltransferase and functions with chromatin assembly factor ASF1

    PubMed Central

    Osada, Shigehiro; Sutton, Ann; Muster, Nemone; Brown, Christine E.; Yates, John R.; Sternglanz, Rolf; Workman, Jerry L.

    2001-01-01

    It is well established that acetylation of histone and nonhistone proteins is intimately linked to transcriptional activation. However, loss of acetyltransferase activity has also been shown to cause silencing defects, implicating acetylation in gene silencing. The something about silencing (Sas) 2 protein of Saccharomyces cerevisiae, a member of the MYST (MOZ, Ybf2/Sas3, Sas2, and TIP60) acetyltransferase family, promotes silencing at HML and telomeres. Here we identify a ∼450-kD SAS complex containing Sas2p, Sas4p, and the tf2f-related Sas5 protein. Mutations in the conserved acetyl-CoA binding motif of Sas2p are shown to disrupt the ability of Sas2p to mediate the silencing at HML and telomeres, providing evidence for an important role for the acetyltransferase activity of the SAS complex in silencing. Furthermore, the SAS complex is found to interact with chromatin assembly factor Asf1p, and asf1 mutants show silencing defects similar to mutants in the SAS complex. Thus, ASF1-dependent chromatin assembly may mediate the role of the SAS complex in silencing. PMID:11731479

  4. 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…

  5. 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.…

  6. 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.

  7. Nucleosome competition reveals processive acetylation by the SAGA HAT module

    PubMed Central

    Ringel, Alison E.; Cieniewicz, Anne M.; Taverna, Sean D.; Wolberger, Cynthia

    2015-01-01

    The Spt-Ada-Gcn5 acetyltransferase (SAGA) coactivator complex hyperacetylates histone tails in vivo in a manner that depends upon histone 3 lysine 4 trimethylation (H3K4me3), a histone mark enriched at promoters of actively transcribed genes. SAGA contains a separable subcomplex known as the histone acetyltransferase (HAT) module that contains the HAT, Gcn5, bound to Sgf29, Ada2, and Ada3. Sgf29 contains a tandem Tudor domain that recognizes H3K4me3-containing peptides and is required for histone hyperacetylation in vivo. However, the mechanism by which H3K4me3 recognition leads to lysine hyperacetylation is unknown, as in vitro studies show no effect of the H3K4me3 modification on histone peptide acetylation by Gcn5. To determine how H3K4me3 binding by Sgf29 leads to histone hyperacetylation by Gcn5, we used differential fluorescent labeling of histones to monitor acetylation of individual subpopulations of methylated and unmodified nucleosomes in a mixture. We find that the SAGA HAT module preferentially acetylates H3K4me3 nucleosomes in a mixture containing excess unmodified nucleosomes and that this effect requires the Tudor domain of Sgf29. The H3K4me3 mark promotes processive, multisite acetylation of histone H3 by Gcn5 that can account for the different acetylation patterns established by SAGA at promoters versus coding regions. Our results establish a model for Sgf29 function at gene promoters and define a mechanism governing crosstalk between histone modifications. PMID:26401015

  8. A Novel H2A/H4 Nucleosomal Histone Acetyltransferase in Tetrahymena thermophila

    PubMed Central

    Ohba, Reiko; Steger, David J.; Brownell, James E.; Mizzen, Craig A.; Cook, Richard G.; Côté, Jacques; Workman, Jerry L.; Allis, C. David

    1999-01-01

    Recently, we reported the identification of a 55-kDa polypeptide (p55) from Tetrahymena macronuclei as a catalytic subunit of a transcription-associated histone acetyltransferase (HAT A). Extensive homology between p55 and Gcn5p, a component of the SAGA and ADA transcriptional coactivator complexes in budding yeast, suggests an immediate link between the regulation of chromatin structure and transcriptional output. Here we report the characterization of a second transcription-associated HAT activity from Tetrahymena macronuclei. This novel activity is distinct from complexes containing p55 and putative ciliate SAGA and ADA components and shares several characteristics with NuA4 (for nucleosomal H2A/H4), a 1.8-MDa, Gcn5p-independent HAT complex recently described in yeast. A key feature of both the NuA4 and Tetrahymena activities is their acetylation site specificity for lysines 5, 8, 12, and 16 of H4 and lysines 5 and 9 of H2A in nucleosomal substrates, patterns that are distinct from those of known Gcn5p family members. Moreover, like NuA4, the Tetrahymena activity is capable of activating transcription from nucleosomal templates in vitro in an acetyl coenzyme A-dependent fashion. Unlike NuA4, however, sucrose gradient analyses of the ciliate enzyme, following sequential denaturation and renaturation, estimate the molecular size of the catalytically active subunit to be ∼80 kDa, consistent with the notion that a single polypeptide or a stable subcomplex is sufficient for this H2A/H4 nucleosomal HAT activity. Together, these data document the importance of this novel HAT activity for transcriptional activation from chromatin templates and suggest that a second catalytic HAT subunit, in addition to p55/Gcn5p, is conserved between yeast and Tetrahymena. PMID:10022893

  9. Structure and Histone Binding Properties of the Vps75-Rtt109 Chaperone-Lysine Acetyltransferase Complex

    SciTech Connect

    Su, Dan; Hu, Qi; Zhou, Hui; Thompson, James R.; Xu, Rui-Ming; Zhang, Zhiguo; Mer, Georges

    2011-11-02

    The histone chaperone Vps75 presents the remarkable property of stimulating the Rtt109-dependent acetylation of several histone H3 lysine residues within (H3-H4){sub 2} tetramers. To investigate this activation mechanism, we determined x-ray structures of full-length Vps75 in complex with full-length Rtt109 in two crystal forms. Both structures show similar asymmetric assemblies of a Vps75 dimer bound to an Rtt109 monomer. In the Vps75-Rtt109 complexes, the catalytic site of Rtt109 is confined to an enclosed space that can accommodate the N-terminal tail of histone H3 in (H3-H4){sub 2}. Investigation of Vps75-Rtt109-(H3-H4)2 and Vps75-(H3-H4)2 complexes by NMR spectroscopy-probed hydrogen/deuterium exchange suggests that Vps75 guides histone H3 in the catalytic enclosure. These findings clarify the basis for the enhanced acetylation of histone H3 tail residues by Vps75-Rtt109.

  10. 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.

  11. Chemical biology of histone acetyltransferase natural compounds modulators.

    PubMed

    Piaz, Fabrizio Dal; Vassallo, Antonio; Rubio, Osmany Cuesta; Castellano, Sabrina; Sbardella, Gianluca; De Tommasi, Nunziatina

    2011-05-01

    Histone acetyltransferases (HATs) are a class of epigenetic enzymes crucial for chromatin restructuring and transcriptional regulation in eukaryotic cells, thus being a promising target for therapeutic development. Nonetheless, differently from histone deacetylases (HDACs) inhibitors, there is still paucity of small-molecule modulators of HAT activity. After a decline during past decade, natural products and their derivatives could be once again a valuable tool in the lead discovery process and meet such need of Novel Chemical Entities (NCEs). In this review, we will provide a comprehensive summary on the discovery of small-molecule HAT modulators from naturally occurring molecular scaffolds.

  12. The histone acetyltransferases CBP and Chameau integrate developmental and DNA replication programs in Drosophila ovarian follicle cells.

    PubMed

    McConnell, Kristopher H; Dixon, Michael; Calvi, Brian R

    2012-10-01

    DNA replication origin activity changes during development. Chromatin modifications are known to influence the genomic location of origins and the time during S phase that they initiate replication in different cells. However, how chromatin regulates origins in concert with cell differentiation remains poorly understood. Here, we use developmental gene amplification in Drosophila ovarian follicle cells as a model to investigate how chromatin modifiers regulate origins in a developmental context. We find that the histone acetyltransferase (HAT) Chameau (Chm) binds to amplicon origins and is partially required for their function. Depletion of Chm had relatively mild effects on origins during gene amplification and genomic replication compared with previous knockdown of its ortholog HBO1 in human cells, which has severe effects on origin function. We show that another HAT, CBP (Nejire), also binds amplicon origins and is partially required for amplification. Knockdown of Chm and CBP together had a more severe effect on nucleosome acetylation and amplicon origin activity than knockdown of either HAT alone, suggesting that these HATs collaborate in origin regulation. In addition to their local function at the origin, we show that Chm and CBP also globally regulate the developmental transition of follicle cells into the amplification stages of oogenesis. Our results reveal a complexity of origin epigenetic regulation by multiple HATs during development and suggest that chromatin modifiers are a nexus that integrates differentiation and DNA replication programs.

  13. 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.

  14. 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

  15. Regulation and function of histone acetyltransferase MOF.

    PubMed

    Yang, Yang; Han, Xiaofei; Guan, Jingyun; Li, Xiangzhi

    2014-03-01

    The mammalian MOF (male absent on the first), a member of the MYST (MOZ, YBF2, SAS2, and Tip60) family of histone acetyltransferases (HATs), is the major enzyme that catalyzes the acetylation of histone H4 on lysine 16. Acetylation of K16 is a prevalent mark associated with chromatin decondensation. MOF has recently been shown to play an essential role in maintaining normal cell functions. In this study, we discuss the important roles of MOF in DNA damage repair, apoptosis, and tumorigenesis. We also analyze the role of MOF as a key regulator of the core transcriptional network of embryonic stem cells.

  16. Assays for mechanistic investigations of protein/histone acetyltransferases.

    PubMed

    Berndsen, Christopher E; Denu, John M

    2005-08-01

    Protein/histone acetyltransferases (PATs/HATs) have been implicated in a number of cellular functions including gene regulation, DNA synthesis, and repair. This paper reviews methods that can be used to quantitatively determine the activity and ultimately the catalytic/kinetic mechanism of PAT/HATs in vitro. Two methods will be described in detail. The first method is a filter-binding assay that measures the transfer of radiolabeled acetate from acetyl-CoA to protein. The second method is a continuous, spectroscopic, enzyme-coupled assay that links the PAT/HAT reaction to the reduction of NAD+ by pyruvate or alpha-ketoglutarate dehydrogenase. Both methods are highly applicable in determining steady-state reaction rates, and obtaining the kinetic constants Vmax, Km, and V/K from substrate saturation curves. We describe a new application of the filter-binding assay to determine the kinetic parameters for HATs using low concentrations of nucleosomal substrates.

  17. A PWWP Domain-Containing Protein Targets the NuA3 Acetyltransferase Complex via Histone H3 Lysine 36 trimethylation to Coordinate Transcriptional Elongation at Coding Regions*

    PubMed Central

    Gilbert, Tonya M.; McDaniel, Stephen L.; Byrum, Stephanie D.; Cades, Jessica A.; Dancy, Blair C. R.; Wade, Herschel; Tackett, Alan J.; Strahl, Brian D.; Taverna, Sean D.

    2014-01-01

    Post-translational modifications of histones, such as acetylation and methylation, are differentially positioned in chromatin with respect to gene organization. For example, although histone H3 is often trimethylated on lysine 4 (H3K4me3) and acetylated on lysine 14 (H3K14ac) at active promoter regions, histone H3 lysine 36 trimethylation (H3K36me3) occurs throughout the open reading frames of transcriptionally active genes. The conserved yeast histone acetyltransferase complex, NuA3, specifically binds H3K4me3 through a plant homeodomain (PHD) finger in the Yng1 subunit, and subsequently catalyzes the acetylation of H3K14 through the histone acetyltransferase domain of Sas3, leading to transcription initiation at a subset of genes. We previously found that Ylr455w (Pdp3), an uncharacterized proline-tryptophan-tryptophan-proline (PWWP) domain-containing protein, copurifies with stable members of NuA3. Here, we employ mass-spectrometric analysis of affinity purified Pdp3, biophysical binding assays, and genetic analyses to classify NuA3 into two functionally distinct forms: NuA3a and NuA3b. Although NuA3a uses the PHD finger of Yng1 to interact with H3K4me3 at the 5′-end of open reading frames, NuA3b contains the unique member, Pdp3, which regulates an interaction between NuA3b and H3K36me3 at the transcribed regions of genes through its PWWP domain. We find that deletion of PDP3 decreases NuA3-directed transcription and results in growth defects when combined with transcription elongation mutants, suggesting NuA3b acts as a positive elongation factor. Finally, we determine that NuA3a, but not NuA3b, is synthetically lethal in combination with a deletion of the histone acetyltransferase GCN5, indicating NuA3b has a specialized role at coding regions that is independent of Gcn5 activity. Collectively, these studies define a new form of the NuA3 complex that associates with H3K36me3 to effect transcriptional elongation. MS data are available via ProteomeXchange with

  18. Crx activates opsin transcription by recruiting HAT-containing co-activators and promoting histone acetylation

    PubMed Central

    Peng, Guang-Hua; Chen, Shiming

    2008-01-01

    The homeodomain transcription factor Crx is required for expression of many photoreceptor genes in the mammalian retina. The mechanism by which Crx activates transcription remains to be determined. Using protein–protein interaction assays, Crx was found to interact with three co-activator proteins (complexes): STAGA, Cbp and p300, all of which possess histone acetyl-transferase (HAT) activity. To determine the role of Crx–HAT interactions in target gene chromatin modification and transcriptional activation, quantitative RT–PCR and chromatin immunoprecipitation were performed on Crx target genes, rod and cone opsins, in developing mouse retina. Although cone opsins are transcribed earlier than rhodopsin during development, the transcription of each gene is preceded by the same sequence of events in their promoter and enhancer regions: (i) binding of Crx, followed by (ii) binding of HATs, (iii) the acetylation of histone H3, then (iv) binding of other photoreceptor transcription factors (Nrl and Nr2e3) and RNA polymerase II. In Crx knockout mice (Crx−/−), the association of HATs and AcH3 with target promoter/enhancer regions was significantly decreased, which correlates with aberrant opsin transcription and photoreceptor dysfunction in these mice. Similar changes to the opsin chromatin were seen in Y79 retinoblastoma cells, where opsin genes are barely transcribed. These defects in Y79 cells can be reversed by expressing a recombinant Crx or applying histone deacetylase inhibitors. Altogether, these results suggest that one mechanism for Crx-mediated transcriptional activation is to recruit HATs to photoreceptor gene chromatin for histone acetylation, thereby inducing and maintaining appropriate chromatin configurations for transcription. PMID:17656371

  19. The Functional Analysis of Histone Acetyltransferase MOF in Tumorigenesis.

    PubMed

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

    2016-01-14

    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.

  20. Yng1p Modulates the Activity of Sas3p as a Component of the Yeast NuA3 Histone Acetyltransferase Complex

    PubMed Central

    Howe, LeAnn; Kusch, Thomas; Muster, Nemone; Chaterji, Ranjana; Yates III, John R.; Workman, Jerry L.

    2002-01-01

    The mammalian ING1 gene encodes a tumor suppressor required for the function of p53. In this study we report a novel function for YNG1, a yeast homolog of ING1. Yng1p is a stable component of the NuA3 histone acetyltransferase complex, which contains Sas3p, the yeast homolog of the mammalian MOZ proto-oncogene product, as its catalytic subunit. Yng1p is required for NuA3 function in vivo but surprisingly is not required for the integrity of the complex. Instead, we find that Yng1p mediates the interaction of Sas3p with nucleosomes and is thus required for the ability of NuA3 to modify histone tails. These data, and the observations that other ING1 homologs are found in additional yeast complexes that posttranslationally modify histones, suggest that members of the ING1 class of proteins may have broad roles in enhancing or modifying the activities of chromatin-modifying complexes, thereby regulating their activities in transcription control. PMID:12077334

  1. Diencephalic Size Is Restricted by a Novel Interplay Between GCN5 Acetyltransferase Activity and Retinoic Acid Signaling.

    PubMed

    Wilde, Jonathan J; Siegenthaler, Julie A; Dent, Sharon Y R; Niswander, Lee A

    2017-03-08

    Diencephalic defects underlie an array of neurological diseases. Previous studies have suggested that retinoic acid (RA) signaling is involved in diencephalic development at late stages of embryonic development, but its roles and mechanisms of action during early neural development are still unclear. Here we demonstrate that mice lacking enzymatic activity of the acetyltransferase GCN5 ((Gcn5(hat/hat) )), which were previously characterized with respect to their exencephalic phenotype, exhibit significant diencephalic expansion, decreased diencephalic RA signaling, and increased diencephalic WNT and SHH signaling. Using a variety of molecular biology techniques in both cultured neuroepithelial cells treated with a GCN5 inhibitor and forebrain tissue from (Gcn5(hat/hat) ) embryos, we demonstrate that GCN5, RARα/γ, and the poorly characterized protein TACC1 form a complex in the nucleus that binds specific retinoic acid response elements in the absence of RA. Furthermore, RA triggers GCN5-mediated acetylation of TACC1, which results in dissociation of TACC1 from retinoic acid response elements and leads to transcriptional activation of RA target genes. Intriguingly, RA signaling defects caused by in vitro inhibition of GCN5 can be rescued through RA-dependent mechanisms that require RARβ. Last, we demonstrate that the diencephalic expansion and transcriptional defects seen in (Gcn5(hat/hat) ) mutants can be rescued with gestational RA supplementation, supporting a direct link between GCN5, TACC1, and RA signaling in the developing diencephalon. Together, our studies identify a novel, nonhistone substrate for GCN5 whose modification regulates a previously undescribed, tissue-specific mechanism of RA signaling that is required to restrict diencephalic size during early forebrain development.SIGNIFICANCE STATEMENT Changes in diencephalic size and shape, as well as SNPs associated with retinoic acid (RA) signaling-associated genes, have been linked to neuropsychiatric

  2. The crystal structure of spermidine/spermine N1-acetyltransferase in complex with spermine provides insights into substrate binding and catalysis.

    PubMed

    Montemayor, Eric J; Hoffman, David W

    2008-09-02

    The enzyme spermidine/spermine N (1)-acetyltransferase (SSAT) catalyzes the transfer of acetyl groups from acetylcoenzyme A to spermidine and spermine, as part of a polyamine degradation pathway. This work describes the crystal structure of SSAT in complex with coenzyme A, with and without bound spermine. The complex with spermine provides a direct view of substrate binding by an SSAT and demonstrates structural plasticity near the active site of the enzyme. Associated water molecules bridge several of the intermolecular contacts between spermine and the enzyme and form a "proton wire" between the side chain of Glu92 and the N1 amine of spermine. A single water molecule can also be seen forming hydrogen bonds with the side chains of Glu92, Asp93, and the N4 amine of spermine. Site-directed mutation of Glu92 to glutamine had a detrimental effect on both substrate binding and catalysis and shifted the optimal pH for enzyme activity further into alkaline solution conditions, while mutation of Asp93 to asparagine affected both substrate binding and catalysis without changing the pH dependence of the enzyme. Considered together, the structural and kinetic data suggest that Glu92 functions as a catalytic base to drive an otherwise unfavorable deprotonation step at physiological pH.

  3. GPS-PAIL: prediction of lysine acetyltransferase-specific modification sites from protein sequences

    PubMed Central

    Deng, Wankun; Wang, Chenwei; Zhang, Ying; Xu, Yang; Zhang, Shuang; Liu, Zexian; Xue, Yu

    2016-01-01

    Protein acetylation catalyzed by specific histone acetyltransferases (HATs) is an essential post-translational modification (PTM) and involved in the regulation a broad spectrum of biological processes in eukaryotes. Although several ten thousands of acetylation sites have been experimentally identified, the upstream HATs for most of the sites are unclear. Thus, the identification of HAT-specific acetylation sites is fundamental for understanding the regulatory mechanisms of protein acetylation. In this work, we first collected 702 known HAT-specific acetylation sites of 205 proteins from the literature and public data resources, and a motif-based analysis demonstrated that different types of HATs exhibit similar but considerably distinct sequence preferences for substrate recognition. Using 544 human HAT-specific sites for training, we constructed a highly useful tool of GPS-PAIL for the prediction of HAT-specific sites for up to seven HATs, including CREBBP, EP300, HAT1, KAT2A, KAT2B, KAT5 and KAT8. The prediction accuracy of GPS-PAIL was critically evaluated, with a satisfying performance. Using GPS-PAIL, we also performed a large-scale prediction of potential HATs for known acetylation sites identified from high-throughput experiments in nine eukaryotes. Both online service and local packages were implemented, and GPS-PAIL is freely available at: http://pail.biocuckoo.org. PMID:28004786

  4. GPS-PAIL: prediction of lysine acetyltransferase-specific modification sites from protein sequences.

    PubMed

    Deng, Wankun; Wang, Chenwei; Zhang, Ying; Xu, Yang; Zhang, Shuang; Liu, Zexian; Xue, Yu

    2016-12-22

    Protein acetylation catalyzed by specific histone acetyltransferases (HATs) is an essential post-translational modification (PTM) and involved in the regulation a broad spectrum of biological processes in eukaryotes. Although several ten thousands of acetylation sites have been experimentally identified, the upstream HATs for most of the sites are unclear. Thus, the identification of HAT-specific acetylation sites is fundamental for understanding the regulatory mechanisms of protein acetylation. In this work, we first collected 702 known HAT-specific acetylation sites of 205 proteins from the literature and public data resources, and a motif-based analysis demonstrated that different types of HATs exhibit similar but considerably distinct sequence preferences for substrate recognition. Using 544 human HAT-specific sites for training, we constructed a highly useful tool of GPS-PAIL for the prediction of HAT-specific sites for up to seven HATs, including CREBBP, EP300, HAT1, KAT2A, KAT2B, KAT5 and KAT8. The prediction accuracy of GPS-PAIL was critically evaluated, with a satisfying performance. Using GPS-PAIL, we also performed a large-scale prediction of potential HATs for known acetylation sites identified from high-throughput experiments in nine eukaryotes. Both online service and local packages were implemented, and GPS-PAIL is freely available at: http://pail.biocuckoo.org.

  5. The narrow active-site cleft of O-acetylserine sulfhydrylase from Leishmania donovani allows complex formation with serine acetyltransferases with a range of C-terminal sequences.

    PubMed

    Raj, Isha; Kumar, Sudhir; Gourinath, Samudrala

    2012-08-01

    Cysteine is a crucial substrate for the synthesis of glutathione and trypanothione, which in turn maintain intracellular redox homeostasis and defend against oxidative stress in the pathogen Leishmania donovani. Here, the identification, sequencing, characterization and crystal structure at 1.79 Å resolution of O-acetylserine sulfhydrylase (OASS), a cysteine-biosynthetic pathway enzyme from L. donovani (LdOASS), are reported. It shows binding to the serine acetyltransferase (SAT) C-terminal peptide, indicating that OASS and SAT interact with each other to form a cysteine synthase complex, further confirmed by the structure of LdOASS in complex with SAT C-terminal octapeptide at 1.68 Å resolution. Docking and fluorescence binding studies show that almost all SAT C-terminus mimicking tetrapeptides can bind to LdOASS. Some peptides had a higher binding affinity than the native peptide, indicating that SAT-OASS interactions are not sequence-specific. The structure of LdOASS with a designed peptide (DWSI) revealed that LdOASS makes more interactions with the designed peptide than with the native peptide. In almost all known SAT-OASS interactions the SAT C-terminal sequence was shown to contain amino acids with large side chains. Structural comparison with other OASSs revealed that LdOASS has a relatively less open active-site cleft, which may be responsible for its interaction with the smaller-amino-acid-containing C-terminal LdSAT peptide. Biochemical studies confirmed that LdOASS interacts with SATs from Entamoeba histolytica and Brucella abortus, further displaying its sequence-independent and versatile mode of interaction with SATs. This implicates a critical role of the size of the active-site cleft opening in OASS for SAT-OASS interaction and thus cysteine synthase complex formation.

  6. 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 Central

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

    2010-01-01

    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. PMID:17344214

  7. Analysis of p300/CBP histone acetyltransferase regulation using circular permutation and semisynthesis.

    PubMed

    Karukurichi, Kannan R; Wang, Ling; Uzasci, Lerna; Manlandro, Cara Marie; Wang, Qing; Cole, Philip A

    2010-02-03

    The histone acetyltransferase (HAT) p300/CBP has been shown to undergo autoacetylation on lysines in an apparent regulatory loop that stimulates HAT activity. Here we have developed a strategy to introduce acetyl-Lys at up to six known modification sites in p300/CBP HAT using a combination of circular permutation and expressed protein ligation. We show that these semisynthetic, circularly permuted acetylated proteins retain high affinity for an acetyl-CoA substrate analogue and that HAT activity correlates positively with degree of acetylation. This study provides novel evidence for control of p300/CBP HAT activity by site-specific autoacetylation and outlines a potentially general strategy for using expressed protein ligation and circular permutation to chemically interrogate internal regions of proteins.

  8. Enzyme kinetics and inhibition of histone acetyltransferase KAT8.

    PubMed

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

    2015-11-13

    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 anacardic acid (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.

  9. 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

  10. 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).

  11. Synergistic action of histone acetyltransferase GCN5 and receptor CLAVATA1 negatively affects ethylene responses in Arabidopsis thaliana.

    PubMed

    Poulios, Stylianos; Vlachonasios, Konstantinos E

    2016-02-01

    GENERAL CONTROL NON-REPRESSIBLE 5 (GCN5) is a histone acetyltransferase (HAT) and the catalytic subunit of several multicomponent HAT complexes that acetylate lysine residues of histone H3. Mutants in AtGCN5 display pleiotropic developmental defects including aberrant meristem function. Shoot apical meristem (SAM) maintenance is regulated by CLAVATA1 (CLV1), a receptor kinase that controls the size of the shoot and floral meristems. Upon activation through CLV3 binding, CLV1 signals to the transcription factor WUSCHEL (WUS), restricting WUS expression and thus the meristem size. We hypothesized that GCN5 and CLV1 act together to affect SAM function. Using genetic and molecular approaches, we generated and characterized clv gcn5 mutants. Surprisingly, the clv1-1 gcn5-1 double mutant exhibited constitutive ethylene responses, suggesting that GCN5 and CLV signaling act synergistically to inhibit ethylene responses in Arabidopsis. This genetic and molecular interaction was mediated by ETHYLENE INSENSITIVE 3/ EIN3-LIKE1 (EIN3/EIL1) transcription factors. Our data suggest that signals from the CLV transduction pathway reach the GCN5-containing complexes in the nucleus and alter the histone acetylation status of ethylene-responsive genes, thus translating the CLV information to transcriptional activity and uncovering a link between histone acetylation and SAM maintenance in the complex mode of ethylene signaling.

  12. 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.

  13. Autoacetylation of the MYST lysine acetyltransferase MOF protein.

    PubMed

    Yang, Chao; Wu, Jiang; Sinha, Sarmistha H; Neveu, John M; Zheng, Yujun George

    2012-10-12

    The MYST family of histone acetyltransferases (HATs) plays critical roles in diverse cellular processes, such as the epigenetic regulation of gene expression. Lysine autoacetylation of the MYST HATs has recently received considerable attention. Nonetheless, the mechanism and function of the autoacetylation process are not well defined. To better understand the biochemical mechanism of MYST autoacetylation and the impact of autoacetylation on the cognate histone acetylation, we carried out detailed analyses of males-absent-on-the-first (MOF), a key member of the MYST family. A number of mutant MOF proteins were produced with point mutations at several key residues near the active site of the enzyme. Autoradiography and immunoblotting data showed that mutation of these residues affects the autoacetylation activity and HAT activity of MOF by various degrees demonstrating that MOF activity is highly sensitive to the chemical changes in those residues. We produced MOF protein in the deacetylated form by using a nonspecific lysine deacetylase. Interestingly, both the autoacetylation activity and the histone acetylation activity of the deacetylated MOF were found to be very close to that of wild-type MOF, suggesting that autoacetylation of MOF only marginally modulates the enzymatic activity. Also, we found that the autoacetylation rates of MOF and deacetylated MOF were much slower than the cognate substrate acetylation. Thus, autoacetylation does not seem to contribute to the intrinsic enzymatic activity in a significant manner. These data provide new insights into the mechanism and function of MYST HAT autoacetylation.

  14. Effective Quenchers Are Required to Eliminate the Interference of Substrate: Cofactor Binding in the HAT Scintillation Proximity Assay

    PubMed Central

    Ngo, Liza; Wu, Jiang; Yang, Chao

    2015-01-01

    Abstract Histone acetyltransferases (HATs) mediate the transfer of an acetyl group from the cofactor, acetyl-CoA, to the side chain amino group of specific lysines in diverse protein substrates, most notably nuclear histones. The deregulation of HATs is connected to a number of disease states. Reliable and rapid biochemical assays for HATs are critical for understanding biological functions of protein acetylation, as well as for screening small-molecule inhibitors of HAT enzymes. In this report, we present a scintillation proximity assay (SPA) for the measurement of HAT enzymatic activities. The acetyl donor was [3H]Ac-CoA, and a biotin-modified histone peptide served as the HAT substrate. After the HAT reaction, streptavidin-coated beads were added to induce proximity of acetylated substrate to the scintillant molecules. However, we observed strong nonspecific binding between the cofactor and the histone peptide substrates, which adversely complicated the SPA performance. To prevent this problem, a set of chemical agents were evaluated to eliminate the cofactor–substrate interaction, thus providing reliable SPA readings. With optimization, the SPA showed consistent and robust performance for HAT activity measurement and HAT inhibitor evaluation. Overall, this mix-and-measure assay does not require any washing procedure, can be utilized in the microplate format, and is well suited for high-throughput screening of HAT chemical modulators. PMID:26065557

  15. Interactions of Histone Acetyltransferase p300 with the Nuclear Proteins Histone and HMGB1, As Revealed by Single Molecule Atomic Force Spectroscopy.

    PubMed

    Banerjee, S; Rakshit, T; Sett, S; Mukhopadhyay, R

    2015-10-22

    One of the important properties of the transcriptional coactivator p300 is histone acetyltransferase (HAT) activity that enables p300 to influence chromatin action via histone modulation. p300 can exert its HAT action upon the other nuclear proteins too--one notable example being the transcription-factor-like protein HMGB1, which functions also as a cytokine, and whose accumulation in the cytoplasm, as a response to tissue damage, is triggered by its acetylation. Hitherto, no information on the structure and stability of the complexes between full-length p300 (p300FL) (300 kDa) and the histone/HMGB1 proteins are available, probably due to the presence of unstructured regions within p300FL that makes it difficult to be crystallized. Herein, we have adopted the high-resolution atomic force microscopy (AFM) approach, which allows molecularly resolved three-dimensional contour mapping of a protein molecule of any size and structure. From the off-rate and activation barrier values, obtained using single molecule dynamic force spectroscopy, the biochemical proposition of preferential binding of p300FL to histone H3, compared to the octameric histone, can be validated. Importantly, from the energy landscape of the dissociation events, a model for the p300-histone and the p300-HMGB1 dynamic complexes that HAT forms, can be proposed. The lower unbinding forces of the complexes observed in acetylating conditions, compared to those observed in non-acetylating conditions, indicate that upon acetylation, p300 tends to weakly associate, probably as an outcome of charge alterations on the histone/HMGB1 surface and/or acetylation-induced conformational changes. To our knowledge, for the first time, a single molecule level treatment of the interactions of HAT, where the full-length protein is considered, is being reported.

  16. 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

  17. Structure and mechanism of non-histone protein acetyltransferase enzymes

    PubMed Central

    Friedmann, David R.

    2014-01-01

    Post translational modification (PTM) of proteins is ubiquitous and mediates many cellular processes including intracellular localization, protein-protein interactions, enzyme activity, transcriptional regulation and protein stability. While the role of phosphorylation as a key PTM has been well studied, the more evolutionarily conserved acetylation PTM has only recently attracted attention as a key regulator of cellular events. Protein acetylation has been largely studied in the context of its role in histone modification and gene regulation, where histones are modified by histone acetyltransferases (HATs) to promote transcription. However, more recent acetylomic and biochemical studies have revealed that acetylation is mediated by a broader family of protein acetyltransferases (PATs). The recent structure determination of several PATs has provided a wealth of molecular information regarding structural features of PATs, their enzymatic mechanisms, their mode of substrate-specific recognition and their regulatory elements. In this minireview, we will briefly describe what is known about non-histone protein substrates, but mainly focus on a few recent structures of PATs to compare and contrast them with HATs to better understand the molecular basis for protein recognition and modification by this burgeoning family of protein modification enzymes. PMID:23742047

  18. Tip60 HAT activity mediates APP induced lethality and apoptotic cell death in the CNS of a Drosophila Alzheimer's disease model.

    PubMed

    Pirooznia, Sheila K; Sarthi, Jessica; Johnson, Ashley A; Toth, Meridith S; Chiu, Kellie; Koduri, Sravanthi; Elefant, Felice

    2012-01-01

    Histone acetylation of chromatin promotes dynamic transcriptional responses in neurons that influence neuroplasticity critical for cognitive ability. It has been demonstrated that Tip60 histone acetyltransferase (HAT) activity is involved in the transcriptional regulation of genes enriched for neuronal function as well as the control of synaptic plasticity. Accordingly, Tip60 has been implicated in the neurodegenerative disorder Alzheimer's disease (AD) via transcriptional regulatory complex formation with the AD linked amyloid precursor protein (APP) intracellular domain (AICD). As such, inappropriate complex formation may contribute to AD-linked neurodegeneration by misregulation of target genes involved in neurogenesis; however, a direct and causative epigenetic based role for Tip60 HAT activity in this process during neuronal development in vivo remains unclear. Here, we demonstrate that nervous system specific loss of Tip60 HAT activity enhances APP mediated lethality and neuronal apoptotic cell death in the central nervous system (CNS) of a transgenic AD fly model while remarkably, overexpression of Tip60 diminishes these defects. Notably, all of these effects are dependent upon the C-terminus of APP that is required for transcriptional regulatory complex formation with Tip60. Importantly, we show that the expression of certain AD linked Tip60 gene targets critical for regulating apoptotic pathways are modified in the presence of APP. Our results are the first to demonstrate a functional interaction between Tip60 and APP in mediating nervous system development and apoptotic neuronal cell death in the CNS of an AD fly model in vivo, and support a novel neuroprotective role for Tip60 HAT activity in AD neurodegenerative pathology.

  19. Spin-orbit inclinations of the exoplanetary systems HAT-P-8b, HAT-P-9b, HAT-P-16b, and HAT-P-23b

    NASA Astrophysics Data System (ADS)

    Moutou, C.; Díaz, R. F.; Udry, S.; Hébrard, G.; Bouchy, F.; Santerne, A.; Ehrenreich, D.; Arnold, L.; Boisse, I.; Bonfils, X.; Delfosse, X.; Eggenberger, A.; Forveille, T.; Lagrange, A.-M.; Lovis, C.; Martinez, P.; Pepe, F.; Perrier, C.; Queloz, D.; Santos, N. C.; Ségransan, D.; Toublanc, D.; Troncin, J. P.; Vanhuysse, M.; Vidal-Madjar, A.

    2011-09-01

    We report the measurement of the spin-orbit angle of the extra-solar planets HAT-P-8 b, HAT-P-9 b, HAT-P-16 b, and HAT-P-23 b, based on spectroscopic observations performed at the Observatoire de Haute-Provence with the SOPHIE spectrograph on the 1.93-m telescope. Radial velocity measurements of the Rossiter-McLaughlin effect show the detection of an apparent prograde, aligned orbit for all systems. The projected spin-orbit angles are found to be λ = -17°+9.2-11.5, -16° ± 8°, -10° ± 16°, and +15° ± 22° for HAT-P-8, HAT-P-9, HAT-P-16, and HAT-P-23, respectively, with corresponding projected rotational velocities of 14.5 ± 0.8, 12.5 ± 1.8, 3.9 ± 0.8, and 7.8 ± 1.6 km s-1. These new results increase to 37 the number of accurately measured spin-orbit angles in transiting extrasolar systems. We conclude by drawing a tentative picture of the global behaviour of orbital alignement, involving the complexity and diversity of possible mechanisms. Based on observations collected with the SOPHIE spectrograph on the 1.93-m telescope at Observatoire de Haute-Provence (CNRS), France, by the SOPHIE Consortium (program 10A.PNP.CONS).

  20. Locus-specific control of DNA resection and suppression of subtelomeric VSG recombination by HAT3 in the African trypanosome.

    PubMed

    Glover, Lucy; Horn, David

    2014-11-10

    The African trypanosome, Trypanosoma brucei, is a parasitic protozoan that achieves antigenic variation through DNA-repair processes involving Variant Surface Glycoprotein (VSG) gene rearrangements at subtelomeres. Subtelomeric suppression of DNA repair operates in eukaryotes but little is known about these controls in trypanosomes. Here, we identify a trypanosome histone acetyltransferase (HAT3) and a deacetylase (SIR2rp1) required for efficient RAD51-dependent homologous recombination. HAT3 and SIR2rp1 were required for RAD51-focus assembly and disassembly, respectively, at a chromosome-internal locus and a synthetic defect indicated distinct contributions to DNA repair. Although HAT3 promoted chromosome-internal recombination, it suppressed subtelomeric VSG recombination, and these locus-specific effects were mediated through differential production of ssDNA by DNA resection; HAT3 promoted chromosome-internal resection but suppressed subtelomeric resection. Consistent with the resection defect, HAT3 was specifically required for the G2-checkpoint response at a chromosome-internal locus. HAT3 also promoted resection at a second chromosome-internal locus comprising tandem-duplicated genes. We conclude that HAT3 and SIR2rp1 can facilitate temporally distinct steps in DNA repair. HAT3 promotes ssDNA formation and recombination at chromosome-internal sites but has the opposite effect at a subtelomeric VSG. These locus-specific controls reveal compartmentalization of the T. brucei genome in terms of the DNA-damage response and suppression of antigenic variation by HAT3.

  1. Structural basis for MOF and MSL3 recruitment into the dosage compensation complex by MSL1.

    PubMed

    Kadlec, Jan; Hallacli, Erinc; Lipp, Michael; Holz, Herbert; Sanchez-Weatherby, Juan; Cusack, Stephen; Akhtar, Asifa

    2011-02-01

    The male-specific lethal (MSL) complex is required for dosage compensation in Drosophila melanogaster, and analogous complexes exist in mammals. We report structures of binary complexes of mammalian MSL3 and the histone acetyltransferase (HAT) MOF with consecutive segments of MSL1. MSL1 interacts with MSL3 as an extended chain forming an extensive hydrophobic interface, whereas the MSL1-MOF interface involves electrostatic interactions between the HAT domain and a long helix of MSL1. This structure provides insights into the catalytic mechanism of MOF and enables us to show analogous interactions of MOF with NSL1. In Drosophila, selective disruption of Msl1 interactions with Msl3 or Mof severely affects Msl1 targeting to the body of dosage-compensated genes and several high-affinity sites, without affecting promoter binding. We propose that Msl1 acts as a scaffold for MSL complex assembly to achieve specific targeting to the X chromosome.

  2. New perspectives for the regulation of acetyltransferase MOF.

    PubMed

    Li, Xiangzhi; Dou, Yali

    2010-04-01

    In higher eukaryotes, histone acetyltransferase MOF (male absent on the first) is the major enzyme that acetylates histone H4 lysine 16, a prevalent mark associated with chromatin decondensation. Recent studies show that MOF resides in two different but evolutionarily conserved complexes, MSL and MOF-MSL1v1. Although these two MOF complexes have indistinguishable activity on histone H4 K16, they differ dramatically in acetylating non-histone substrate p53. The regulation of MOF activity in these complexes remains elusive. Given the evolution conservation of MOF and the importance of H4 K16 acetylation in maintaining higher order chromatin structures, understanding the function and regulation of MOF bears great significance. Here, we discussed the key differences in two MOF complexes that may shed light on the regulation of their distinct acetyltransferase activities. We also discussed coordinated functions of two MOF complexes with different histone methyltransferase complexes in transcription regulation.

  3. Camello, a novel family of Histone Acetyltransferases that acetylate histone H4 and is essential for zebrafish development

    PubMed Central

    Karmodiya, Krishanpal; Anamika, Krishanpal; Muley, Vijaykumar; Pradhan, Saurabh J.; Bhide, Yoshita; Galande, Sanjeev

    2014-01-01

    In this study, we have investigated genome-wide occurrence of Histone Acetyltransferases (HATs) in genomes of Mus musculus and Danio rerio on the basis of presence of HAT domain. Our study identified a group of proteins that lacks characteristic features of known HAT families, relatively smaller in size and has no other associated domains. Most of the proteins in this unclassified group are Camello proteins, which are not yet known and classified as functional HATs. Our in vitro and in vivo analysis revealed that Camello family proteins are active HATs and exhibit specificity towards histone H4. Interestingly, Camello proteins are among the first identified HATs showing perinuclear localization. Moreover, Camello proteins are evolutionarily conserved in all chordates and are observed for the first time in cnidarians in phylogeny. Furthermore, knockdown of Camello protein (CMLO3) in zebrafish embryos exhibited defects in axis elongation and head formation. Thus, our study identified a novel family of active HATs that is specific for histone H4 acetylation, exhibits perinuclear localization and is essential for zebrafish development. PMID:25123547

  4. Epigenetic Control of Learning and Memory in Drosophila by Tip60 HAT Action

    PubMed Central

    Xu, Songjun; Wilf, Rona; Menon, Trisha; Panikker, Priyalakshmi; Sarthi, Jessica; Elefant, Felice

    2014-01-01

    Disruption of epigenetic gene control mechanisms in the brain causes significant cognitive impairment that is a debilitating hallmark of most neurodegenerative disorders, including Alzheimer’s disease (AD). Histone acetylation is one of the best characterized of these epigenetic mechanisms that is critical for regulating learning- and memory- associated gene expression profiles, yet the specific histone acetyltransferases (HATs) that mediate these effects have yet to be fully characterized. Here, we investigate an epigenetic role for the HAT Tip60 in learning and memory formation using the Drosophila CNS mushroom body (MB) as a well-characterized cognition model. We show that Tip60 is endogenously expressed in the Kenyon cells, the intrinsic neurons of the MB, and in the MB axonal lobes. Targeted loss of Tip60 HAT activity in the MB causes thinner and shorter axonal lobes while increasing Tip60 HAT levels cause no morphological defects. Functional consequences of both loss and gain of Tip60 HAT levels in the MB are evidenced by defects in immediate-recall memory. Our ChIP-Seq analysis reveals that Tip60 target genes are enriched for functions in cognitive processes, and, accordingly, key genes representing these pathways are misregulated in the Tip60 HAT mutant fly brain. Remarkably, we find that both learning and immediate-recall memory deficits that occur under AD-associated, amyloid precursor protein (APP)-induced neurodegenerative conditions can be effectively rescued by increasing Tip60 HAT levels specifically in the MB. Together, our findings uncover an epigenetic transcriptional regulatory role for Tip60 in cognitive function and highlight the potential of HAT activators as a therapeutic option for neurodegenerative disorders. PMID:25326235

  5. The lac operon galactoside acetyltransferase.

    PubMed

    Roderick, Steven L

    2005-06-01

    Of the proteins encoded by the three structural genes of the lac operon, the galactoside acetyltransferase (thiogalactoside transacetylase, LacA, GAT) encoded by lacA is the only protein whose biological role remains in doubt. Here, we briefly note the classical literature that led to the identification and initial characterization of GAT, and focus on more recent results which have revealed its chemical mechanism of action and its membership in a large superfamily of structurally similar acyltransferases. The structural and sequence similarities of several members of this superfamily confirm the original claim for GAT as a CoA-dependent acetyltransferase specific for the 6-hydroxyl group of certain pyranosides, but do not yet point to the identity of the natural substrate(s) of the enzyme.

  6. Isothiazolones as inhibitors of PCAF and p300 histone acetyltransferase activity.

    PubMed

    Stimson, Lindsay; Rowlands, Martin G; Newbatt, Yvette M; Smith, Nicola F; Raynaud, Florence I; Rogers, Paul; Bavetsias, Vassilios; Gorsuch, Stephen; Jarman, Michael; Bannister, Andrew; Kouzarides, Tony; McDonald, Edward; Workman, Paul; Aherne, G Wynne

    2005-10-01

    Histone acetylation plays an important role in regulating the chromatin structure and is tightly regulated by two classes of enzyme, histone acetyltransferases (HAT) and histone deacetylases (HDAC). Deregulated HAT and HDAC activity plays a role in the development of a range of cancers. Consequently, inhibitors of these enzymes have potential as anticancer agents. Several HDAC inhibitors have been described; however, few inhibitors of HATs have been disclosed. Following a FlashPlate high-throughput screen, we identified a series of isothiazolone-based HAT inhibitors. Thirty-five N-substituted analogues inhibited both p300/cyclic AMP-responsive element binding protein-binding protein-associated factor (PCAF) and p300 (1 to >50 micromol/L, respectively) and the growth of a panel of human tumor cell lines (50% growth inhibition, 0.8 to >50 micromol/L). CCT077791 and CCT077792 decreased cellular acetylation in a time-dependent manner (2-48 hours of exposure) and a concentration-dependent manner (one to five times, 72 hours, 50% growth inhibition) in HCT116 and HT29 human colon tumor cell lines. CCT077791 reduced total acetylation of histones H3 and H4, levels of specific acetylated lysine marks, and acetylation of alpha-tubulin. Four and 24 hours of exposure to the compounds produced the same extent of growth inhibition as 72 hours of continuous exposure, suggesting that growth arrest was an early event. Chemical reactivity of these compounds, as measured by covalent protein binding and loss of HAT inhibition in the presence of DTT, indicated that reaction with thiol groups might be important in their mechanism of action. As one of the first series of small-molecule inhibitors of HAT activity, further analogue synthesis is being pursued to examine the potential scope for reducing chemical reactivity while maintaining HAT inhibition.

  7. Mechanical regulation of the proangiogenic factor CCN1/CYR61 gene requires the combined activities of MRTF-A and CREB-binding protein histone acetyltransferase.

    PubMed

    Hanna, Mary; Liu, Haibo; Amir, Jawaria; Sun, Yi; Morris, Stephan W; Siddiqui, M A Q; Lau, Lester F; Chaqour, Brahim

    2009-08-21

    Smooth muscle-rich tissues respond to mechanical overload by an adaptive hypertrophic growth combined with activation of angiogenesis, which potentiates their mechanical overload-bearing capabilities. Neovascularization is associated with mechanical strain-dependent induction of angiogenic factors such as CCN1, an immediate-early gene-encoded matricellular molecule critical for vascular development and repair. Here we have demonstrated that mechanical strain-dependent induction of the CCN1 gene involves signaling cascades through RhoA-mediated actin remodeling and the p38 stress-activated protein kinase (SAPK). Actin signaling controls serum response factor (SRF) activity via SRF interaction with the myocardin-related transcriptional activator (MRTF)-A and tethering to a single CArG box sequence within the CCN1 promoter. Such activity was abolished in mechanically stimulated mouse MRTF-A(-/-) cells or upon inhibition of CREB-binding protein (CBP) histone acetyltransferase (HAT) either pharmacologically or by siRNAs. Mechanical strain induced CBP-mediated acetylation of histones 3 and 4 at the SRF-binding site and within the CCN1 gene coding region. Inhibition of p38 SAPK reduced CBP HAT activity and its recruitment to the SRF.MRTF-A complex, whereas enforced induction of p38 by upstream activators (e.g. MKK3 and MKK6) enhanced both CBP HAT and CCN1 promoter activities. Similarly, mechanical overload-induced CCN1 gene expression in vivo was associated with nuclear localization of MRTF-A and enrichment of the CCN1 promoter with both MRTF-A and acetylated histone H3. Taken together, these data suggest that signal-controlled activation of SRF, MRTF-A, and CBP provides a novel connection between mechanical stimuli and angiogenic gene expression.

  8. Is There a Link Between Expression Levels of Histone Deacetylase/Acetyltransferase in Mouse Sperm and Subsequent Blastocyst Development?

    PubMed

    Kim, Jayeon; Kim, Ji-Hee; Jee, Byung-Chul; Suh, Chang-Suk; Kim, Seok-Hyun

    2015-11-01

    Histone acetylation has been known to be significant in spermatogenesis. Histone acetylation is regulated by the act of histone deacetylases (HDACs) and histone acetyltransferases (HATs). We investigated the link between expression levels of HDACs and HATs in mouse sperm and subsequent blastocyst formation rate. In the univariate analysis, expression levels of HDAC1 and HAT were generally not associated with the blastocyst formation rate. When divided by the mature oocyte number category, a significant positive association was observed between the expression levels of HDAC1 and the blastocyst-forming rate in the highest (> 75th) percentile group (a group with ≥34 mature oocytes). In conclusion, expression of sperm HDAC1 could be considered as a possible predictor of embryo development in mice with high ovarian response.

  9. Involvement of Arabidopsis histone acetyltransferase HAC family genes in the ethylene signaling pathway.

    PubMed

    Li, Chao; Xu, Jiang; Li, Jian; Li, Qingyun; Yang, Hongchun

    2014-02-01

    Epigenetic modifications play a fundamental role in regulating chromatin dynamics and gene expression. The level of histone acetylation is controlled by two functionally antagonistic enzymes, namely histone acetyltransferase (HAT) and histone deacetylase (HDAC). CREB-binding protein (CBP)/p300 proteins, a subfamily of highly conserved HATs, are involved in various physiological events including proliferation, differentiation and apoptosis. In this work, we study the poorly known function of their homologous genes, the HAC genes, in Arabidopsis. We found that hac1-involved mutants displayed pleiotropic phenotypes, in particular hypersensitivity to ethylene both in the dark and in the light. We also found that the transcriptional levels of ethylene-responsive genes are significantly higher in the hac1hac5 double mutant than in wild-type plants. Moreover, an ethylene synthesis inhibitor cannot release the triple responses of hac mutants. These results suggest that HACs are involved in the ethylene signaling pathway.

  10. 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 Central

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

    2014-01-01

    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

  11. 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...

  12. 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...

  13. Sex-biased transcription enhancement by a 5' tethered Gal4-MOF histone acetyltransferase fusion protein in Drosophila

    PubMed Central

    2010-01-01

    Background In male Drosophila melanogaster, the male specific lethal (MSL) complex is somehow responsible for a two-fold increase in transcription of most X-linked genes, which are enriched for histone H4 acetylated at lysine 16 (H4K16ac). This acetylation requires MOF, a histone acetyltransferase that is a component of the MSL complex. MOF also associates with the non-specific lethal or NSL complex. The MSL complex is bound within active genes on the male X chromosome with a 3' bias. In contrast, the NSL complex is enriched at promoter regions of many autosomal and X-linked genes in both sexes. In this study we have investigated the role of MOF as a transcriptional activator. Results MOF was fused to the DNA binding domain of Gal4 and targeted to the promoter region of UAS-reporter genes in Drosophila. We found that expression of a UAS-red fluorescent protein (DsRed) reporter gene was strongly induced by Gal4-MOF. However, DsRed RNA levels were about seven times higher in female than male larvae. Immunostaining of polytene chromosomes showed that Gal4-MOF co-localized with MSL1 to many sites on the X chromosome in male but not female nuclei. However, in female nuclei that express MSL2, Gal4-MOF co-localized with MSL1 to many sites on polytene chromosomes but DsRed expression was reduced. Mutation of conserved active site residues in MOF (Glu714 and Cys680) reduced HAT activity in vitro and UAS-DsRed activation in Drosophila. In the presence of Gal4-MOF, H4K16ac levels were enriched over UAS-lacZ and UAS-arm-lacZ reporter genes. The latter utilizes the constitutive promoter from the arm gene to drive lacZ expression. In contrast to the strong induction of UAS-DsRed expression, UAS-arm-lacZ expression increased by about 2-fold in both sexes. Conclusions Targeting MOF to reporter genes led to transcription enhancement and acetylation of histone H4 at lysine 16. Histone acetyltransferase activity was required for the full transcriptional response. Incorporation of Gal

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

    PubMed

    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

    2015-01-06

    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.

  15. Histone acetyltransferase AtGCN5/HAG1 is a versatile regulator of developmental and inducible gene expression in Arabidopsis.

    PubMed

    Servet, Caroline; Conde e Silva, Natalia; Zhou, Dao-Xiu

    2010-07-01

    Histone acetylation/deacetylation is a dynamic process and plays an important role in gene regulation. Histone acetylation homeostasis is regulated by antagonist actions of histone acetyltransferases (HAT) and deacetylases (HDAC). Plant genome encodes multiple HATs and HDACs. The Arabidopsis HAT gene AtGCN5/HAG1plays an essential role in many plant development processes, such as meristem function, cell differentiation, leaf and floral organogenesis, and responses to environmental conditions such as light and cold, indicating an important role of this HAT in the regulation of both long-term developmental switches and short-term inducible gene expression. AtGCN5 targets to a large number of promoters and is required for acetylation of several histone H3 lysine residues. Recruitment of AtGCN5 to target promoters is likely to be mediated by direct or indirect interaction with DNA-binding transcription factors and/or by interaction with acetylated histone lysine residues on the targets. Interplay between AtGCN5 and other HAT and HDAC is demonstrated to control specific regulatory pathways. Analysis of the role of AtGCN5 in light-inducible gene expression suggests a function of AtGCN5 in preparing chromatin commitment for priming inducible gene activation in plants.

  16. Structure of the lac operon galactoside acetyltransferase.

    PubMed

    Wang, Xing-Guo; Olsen, Laurence R; Roderick, Steven L

    2002-04-01

    The galactoside acetyltransferase (thiogalactoside transacetylase) of Escherichia coli (GAT, LacA, EC 2.3.1.18) is a gene product of the classical lac operon. GAT may assist cellular detoxification by acetylating nonmetabolizable pyranosides, thereby preventing their reentry into the cell. The structure of GAT has been solved in binary complexes with acetyl-CoA or CoA and in ternary complexes with CoA and the nonphysiological acceptor substrates isopropyl beta-D-thiogalactoside (IPTG) or p-nitrophenyl beta-D-galactopyranoside (PNPbetaGal). A hydrophobic cleft that binds the thioisopropyl and p-nitrophenyl aglycones of IPTG and PNPbetaGal may discriminate against substrates with hydrophilic substituents at this position, such as lactose, or inducers of the lac operon. An extended loop projecting from the left-handed parallel beta helix domain contributes His115, which is in position to facilitate attack of the C6-hydroxyl group of the substrate on the thioester.

  17. Regulation of NuA4 histone acetyltransferase activity in transcription and DNA repair by phosphorylation of histone H4.

    PubMed

    Utley, Rhea T; Lacoste, Nicolas; Jobin-Robitaille, Olivier; Allard, Stéphane; Côté, Jacques

    2005-09-01

    The NuA4 complex is a histone H4/H2A acetyltransferase involved in transcription and DNA repair. While histone acetylation is important in many processes, it has become increasingly clear that additional histone modifications also play a crucial interrelated role. To understand how NuA4 action is regulated, we tested various H4 tail peptides harboring known modifications in HAT assays. While dimethylation at arginine 3 (R3M) had little effect on NuA4 activity, phosphorylation of serine 1 (S1P) strongly decreased the ability of the complex to acetylate H4 peptides. However, R3M in combination with S1P alleviates the repression of NuA4 activity. Chromatin from cells treated with DNA damage-inducing agents shows an increase in phosphorylation of serine 1 and a concomitant decrease in H4 acetylation. We found that casein kinase 2 phosphorylates histone H4 and associates with the Rpd3 deacetylase complex, demonstrating a physical connection between phosphorylation of serine 1 and unacetylated H4 tails. Chromatin immunoprecipitation experiments also link local phosphorylation of H4 with its deacetylation, during both transcription and DNA repair. Time course chromatin immunoprecipitation data support a model in which histone H4 phosphorylation occurs after NuA4 action during double-strand break repair at the step of chromatin restoration and deacetylation. These findings demonstrate that H4 phospho-serine 1 regulates chromatin acetylation by the NuA4 complex and that this process is important for normal gene expression and DNA repair.

  18. Imbalance between HAT and HDAC Activities in the PBMCs of Patients with Ankylosing Spondylitis or Rheumatoid Arthritis and Influence of HDAC Inhibitors on TNF Alpha Production

    PubMed Central

    Toussirot, Eric; Abbas, Wasim; Khan, Kashif Aziz; Tissot, Marion; Jeudy, Alicia; Baud, Lucile; Bertolini, Ewa; Wendling, Daniel; Herbein, Georges

    2013-01-01

    Objective Acetylation or deacetylation of histone proteins may modulate cytokine gene transcription such as TNF alpha (TNF). We evaluated the balance between histone deacetytlase (HDAC) and histone acetyltransferase (HAT) in patients with rheumatoid arthritis (RA) or ankylosing spondylitis (AS) compared to healthy controls (HC) and determined the influence of HDAC inhibitors (trichostatin A -TSA- or Sirtinol -Sirt-) on these enzymatic activities and on the PBMC production of TNF. Methods 52 patients with RA, 21 with AS and 38 HC were evaluated. HAT and HDAC activities were measured on nuclear extracts from PBMC using colorimetric assays. Enzymatic activities were determined prior to and after ex vivo treatment of PBMC by TSA or Sirt. TNF levels were evaluated in PBMC culture supernatants in the absence or presence of TSA or Sirt. Results HAT and HDAC activities were significantly reduced in AS, while these activities reached similar levels in RA and HC. Ex vivo treatment of PBMC by HDACi tended to decrease HDAC expression in HC, but Sirt significantly reduced HAT in RA. TNF production by PBMC was significantly down-regulated by Sirt in HC and AS patients. Conclusion HAT and HDAC were disturbed in AS while no major changes were found in RA. HDACi may modulate HDAC and HAT PBMC expression, especially Sirt in RA. Sirtinol was able to down regulate TNF production by PBMC in HC and AS. An imbalance between HAT and HDAC activities might provide the rationale for the development of HDACi in the therapeutic approach to inflammatory rheumatic diseases. PMID:24039666

  19. 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.

  20. Three-dimensional structure of a Streptomyces sviceus GNAT acetyltransferase with similarity to the C-terminal domain of the human GH84 O-GlcNAcase.

    PubMed

    He, Yuan; Roth, Christian; Turkenburg, Johan P; Davies, Gideon J

    2014-01-01

    The mammalian O-GlcNAc hydrolysing enzyme O-GlcNAcase (OGA) is a multi-domain protein with glycoside hydrolase activity in the N-terminus and with a C-terminal domain that has low sequence similarity to known acetyltransferases, prompting speculation, albeit controversial, that the C-terminal domain may function as a histone acetyltransferase (HAT). There are currently scarce data available regarding the structure and function of this C-terminal region. Here, a bacterial homologue of the human OGA C-terminal domain, an acetyltransferase protein (accession No. ZP_05014886) from Streptomyces sviceus (SsAT), was cloned and its crystal structure was solved to high resolution. The structure reveals a conserved protein core that has considerable structural homology to the acetyl-CoA (AcCoA) binding site of GCN5-related acetyltransferases (GNATs). Calorimetric data further confirm that SsAT is indeed able to bind AcCoA in solution with micromolar affinity. Detailed structural analysis provided insight into the binding of AcCoA. An acceptor-binding cavity was identified, indicating that the physiological substrate of SsAT may be a small molecule. Consistent with recently published work, the SsAT structure further questions a HAT function for the human OGA domain.

  1. Three-dimensional structure of a Streptomyces sviceus GNAT acetyltransferase with similarity to the C-terminal domain of the human GH84 O-GlcNAcase

    SciTech Connect

    He, Yuan; Roth, Christian; Turkenburg, Johan P.; Davies, Gideon J.

    2014-01-01

    The crystal structure of a bacterial acetyltransferase with 27% sequence identity to the C-terminal domain of human O-GlcNAcase has been solved at 1.5 Å resolution. This S. sviceus protein is compared with known GCN5-related acetyltransferases, adding to the diversity observed in this superfamily. The mammalian O-GlcNAc hydrolysing enzyme O-GlcNAcase (OGA) is a multi-domain protein with glycoside hydrolase activity in the N-terminus and with a C-terminal domain that has low sequence similarity to known acetyltransferases, prompting speculation, albeit controversial, that the C-terminal domain may function as a histone acetyltransferase (HAT). There are currently scarce data available regarding the structure and function of this C-terminal region. Here, a bacterial homologue of the human OGA C-terminal domain, an acetyltransferase protein (accession No. ZP-05014886) from Streptomyces sviceus (SsAT), was cloned and its crystal structure was solved to high resolution. The structure reveals a conserved protein core that has considerable structural homology to the acetyl-CoA (AcCoA) binding site of GCN5-related acetyltransferases (GNATs). Calorimetric data further confirm that SsAT is indeed able to bind AcCoA in solution with micromolar affinity. Detailed structural analysis provided insight into the binding of AcCoA. An acceptor-binding cavity was identified, indicating that the physiological substrate of SsAT may be a small molecule. Consistent with recently published work, the SsAT structure further questions a HAT function for the human OGA domain.

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

    DOEpatents

    Stephens, David S [Stone Mountain, GA; Gudlavalleti, Seshu K [Kensington, MD; Tzeng, Yih-Ling [Atlanta, GA; Datta, Anup K [San Diego, CA; Carlson, Russell W [Athens, GA

    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.

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

    PubMed Central

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

    2012-01-01

    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. PMID:22875992

  4. 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.

  5. Ex Vivo Expansion of Human Hematopoietic Stem Cells by Garcinol, a Potent Inhibitor of Histone Acetyltransferase

    PubMed Central

    Nishino, Taito; Wang, Changshan; Mochizuki-Kashio, Makiko; Osawa, Mitsujiro; Nakauchi, Hiromitsu; Iwama, Atsushi

    2011-01-01

    Background Human cord blood (hCB) is the main source of hematopoietic stem and progenitor cells (HSCs/PCs) for transplantation. Efforts to overcome relative shortages of HSCs/PCs have led to technologies to expand HSCs/PCs ex vivo. However, methods suitable for clinical practice have yet to be fully established. Methodology/Principal Findings In this study, we screened biologically active natural products for activity to promote expansion of hCB HSCs/PCs ex vivo, and identified Garcinol, a plant-derived histone acetyltransferase (HAT) inhibitor, as a novel stimulator of hCB HSC/PC expansion. During a 7-day culture of CD34+CD38– HSCs supplemented with stem cell factor and thrombopoietin, Garcinol increased numbers of CD34+CD38– HSCs/PCs more than 4.5-fold and Isogarcinol, a derivative of Garcinol, 7.4-fold. Furthermore, during a 7-day culture of CD34+ HSCs/PCs, Garcinol expanded the number of SCID-repopulating cells (SRCs) 2.5-fold. We also demonstrated that the capacity of Garcinol and its derivatives to expand HSCs/PCs was closely correlated with their inhibitory effect on HAT. The Garcinol derivatives which expanded HSCs/PCs inhibited the HAT activity and acetylation of histones, while inactive derivatives did not. Conclusions/Significance Our findings identify Garcinol as the first natural product acting on HSCs/PCs and suggest the inhibition of HAT to be an alternative approach for manipulating HSCs/PCs. PMID:21931675

  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. Mexican Hat Wavelet Kernel ELM for Multiclass Classification

    PubMed Central

    Wang, Jie; Ma, Tian-Lei

    2017-01-01

    Kernel extreme learning machine (KELM) is a novel feedforward neural network, which is widely used in classification problems. To some extent, it solves the existing problems of the invalid nodes and the large computational complexity in ELM. However, the traditional KELM classifier usually has a low test accuracy when it faces multiclass classification problems. In order to solve the above problem, a new classifier, Mexican Hat wavelet KELM classifier, is proposed in this paper. The proposed classifier successfully improves the training accuracy and reduces the training time in the multiclass classification problems. Moreover, the validity of the Mexican Hat wavelet as a kernel function of ELM is rigorously proved. Experimental results on different data sets show that the performance of the proposed classifier is significantly superior to the compared classifiers. PMID:28321249

  8. Distribution of acetylated histones resulting from Gal4-VP16 recruitment of SAGA and NuA4 complexes

    PubMed Central

    Vignali, Marissa; Steger, David J.; Neely, Kristen E.; Workman, Jerry L.

    2000-01-01

    We analyzed the targeting of histone acetyltransferase (HAT) complexes by DNA-binding activators during transcriptional activation and the resulting distribution of acetylated histones. An in vitro competition assay was developed to acetylate and transcribe a nucleosomal array template in the presence of excess non-specific chromatin, which mimics in vivo conditions. Stimulation of transcription from the nucleosomal array template under competitive conditions by the SAGA and NuA4 HAT complexes depended on the presence of the Gal4-VP16 activator, which recognizes sites in the promoter and directly interacts with these HATs. Importantly, the stimulation of transcription by SAGA and NuA4 depended on the presence of Gal4-VP16 during histone acetylation, and Gal4-VP16-bound nucleosomal templates were acetylated preferentially by SAGA and NuA4 relative to the competitor chromatin. While targeting of the SAGA complex led to H3 acetylation of promoter-proximal nucleosomes, targeting of the NuA4 complex led to a broader domain of H4 acetylation of >3 kbp. Thus, either promoter-proximal H3 acetylation by SAGA or broadly distributed acetylation of H4 by NuA4 activated transcription from chromatin templates. PMID:10835360

  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. 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

  11. Radiosensitizing effect of the histone acetyltransferase inhibitor anacardic acid on various mammalian cell lines

    PubMed Central

    CATE, ROSEMARIE TEN; KRAWCZYK, PRZEMEK; STAP, JAN; ATEN, JACOB A.; FRANKEN, NICOLAAS A.P.

    2010-01-01

    Agents that enhance the effectiveness of ionizing radiation have been investigated over many decades. A relatively new group of potential radiosensitizers consists of agents that inhibit histone acetyltransferases (HATs). This study evaluated the radiosensitizing properties of the HAT inhibitor anacardic acid (AA), used at a low-toxic concentration of 100 μM in V79, SW1573 and U2OS cells. Radiation survival curves were analyzed according to the linear quadratic model. Significant radiosensitization by AA was only obtained in U2OS cells. AA significantly increased the value of the linear parameter α, but not of the quadratic parameter β, indicating fixation of potentially lethal damage and an intact repair function of sublethal damage. The increase of the α value was also observed in SW1573 cells, but was not accompanied by a significant radiosensitization. A likely explanation for the enhancement of the α value may be an increase in the amount of lethal lesions due to the compacted chromatin structure. Despite the conflicting results of the radiosensitizing effect of AA in the three cell lines tested, the ability of AA to increase the α value suggests potential advantages for clinical application. PMID:22966377

  12. 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

  13. 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

  14. Histone Acetyltransferase Activity of MOF Is Required for MLL-AF9 Leukemogenesis.

    PubMed

    Valerio, Daria G; Xu, Haiming; Chen, Chun-Wei; Hoshii, Takayuki; Eisold, Meghan E; Delaney, Christopher; Cusan, Monica; Deshpande, Aniruddha J; Huang, Chun-Hao; Lujambio, Amaia; Zheng, YuJun George; Zuber, Johannes; Pandita, Tej K; Lowe, Scott W; Armstrong, Scott A

    2017-02-15

    Chromatin-based mechanisms offer therapeutic targets in acute myeloid leukemia (AML) that are of great current interest. In this study, we conducted an RNAi-based screen to identify druggable chromatin regulator-based targets in leukemias marked by oncogenic rearrangements of the MLL gene. In this manner, we discovered the H4K16 histone acetyltransferase (HAT) MOF to be important for leukemia cell growth. Conditional deletion of Mof in a mouse model of MLL-AF9-driven leukemogenesis reduced tumor burden and prolonged host survival. RNA sequencing showed an expected downregulation of genes within DNA damage repair pathways that are controlled by MOF, as correlated with a significant increase in yH2AX nuclear foci in Mof-deficient MLL-AF9 tumor cells. In parallel, Mof loss also impaired global H4K16 acetylation in the tumor cell genome. Rescue experiments with catalytically inactive mutants of MOF showed that its enzymatic activity was required to maintain cancer pathogenicity. In support of the role of MOF in sustaining H4K16 acetylation, a small-molecule inhibitor of the HAT component MYST blocked the growth of both murine and human MLL-AF9 leukemia cell lines. Furthermore, Mof inactivation suppressed leukemia development in an NUP98-HOXA9-driven AML model. Taken together, our results establish that the HAT activity of MOF is required to sustain MLL-AF9 leukemia and may be important for multiple AML subtypes. Blocking this activity is sufficient to stimulate DNA damage, offering a rationale to pursue MOF inhibitors as a targeted approach to treat MLL-rearranged leukemias. Cancer Res; 77(7); 1-10. ©2017 AACR.

  15. Extrasolar planet search with the HAT network

    NASA Astrophysics Data System (ADS)

    Bakos, G.; Noyes, R. W.; Latham, D. W.; Csák, B.; Gálfi, G.; Pál, A.

    2006-02-01

    We summarize the current status of the HAT Network project. Started up in 2003 with a single telescope, HATNet has grown to an array of six almost identical, fully automated, wide-field telescopes spread in geographical longitude, plus a higher resolution photometry follow-up instrument called TopHAT. The instruments are maintained and controlled from the Center for Astrophysics, and are fully dedicated to planetary transit and variability search. Photometric precision reaches 3mmag for stars at I≈8, and data from separate stations can be readily combined. TopHAT is able to achieve millimag follow-up photometry. As of June 2005, 100000 stars have been thoroughly analyzed (30000 with photometry better than 1%); numerous transit candidates have been found and followed up by spectroscopy or photometry. Most of these turned out to be false positives, with a few cases still pending.

  16. Conditions for the self-catalysed inactivation of carnitine acetyltransferase. A novel form of enzyme inhibition

    PubMed Central

    Chase, J. F. A.; Tubbs, P. K.

    1969-01-01

    1. Carnitine acetyltransferase is very rapidly inhibited in the presence of bromoacetyl-(−)-carnitine plus CoA or of bromoacetyl-CoA plus (−)-carnitine. 2. Under appropriate conditions, the enzyme may be titrated with either bromoacetyl substrate analogue; in each case about 1mole of inhibitor is required to inactivate completely 1mole of enzyme of molecular weight 58000±3000. 3. Inhibition by bromoacetyl-CoA plus (−)-carnitine results in the formation of an inactive enzyme species, containing stoicheiometric amounts of bound adenine nucleotide and (−)-carnitine in a form that is not removed by gel filtration. This is shown to be S-carboxymethyl-CoA (−)-carnitine ester. 4. The inhibited enzyme recovers activity slowly on prolonged standing at 4°. 5. Incubation with S-carboxymethyl-CoA (−)-carnitine ester causes a slow inhibition of carnitine acetyltransferase. 6. The formation of bound S-carboxymethyl-CoA (−)-carnitine ester by the enzyme is discussed. Presumably the resulting inhibition reflects binding of the ester to both the CoA- and carnitine-binding sites on the enzyme and its consequent very slow dissociation. These observations confirm that carnitine acetyltransferase can form ternary enzyme–substrate complexes; this also appears to be the case with carnitine palmitoyltransferase and choline acetyltransferase. PMID:5763788

  17. CBP and p300 histone acetyltransferases contribute to homologous recombination by transcriptionally activating the BRCA1 and RAD51 genes.

    PubMed

    Ogiwara, Hideaki; Kohno, Takashi

    2012-01-01

    Histone acetylation at DNA double-strand break (DSB) sites by CBP and p300 histone acetyltransferases (HATs) is critical for the recruitment of DSB repair proteins to chromatin. Here, we show that CBP and p300 HATs also function in DSB repair by transcriptionally activating the BRCA1 and RAD51 genes, which are involved in homologous recombination (HR), a major DSB repair system. siRNA-mediated depletion of CBP and p300 impaired HR activity and downregulated BRCA1 and RAD51 at the protein and mRNA levels. Chromatin immunoprecipitation assays showed that CBP and p300 bind to the promoter regions of the BRCA1 and RAD51 genes, and that depletion of CBP and/or p300 reduces H3 and H4 acetylation and inhibits binding of the transcription factor E2F1 to these promoters. Depletion of CBP and p300 impaired DNA damage-induced phosphorylation and chromatin binding of the single-strand DNA-binding protein RPA following BRCA1-mediated DNA end resection. Consistent with this, subsequent phosphorylation of CHK1 and activation of the G2/M damage checkpoint were also impaired. These results indicate that the HATs CBP and p300 play multiple roles in the activation of the cellular response to DSBs.

  18. 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.

  19. To learn better, keep the HAT on.

    PubMed

    Martin, Kelsey C; Sun, Yi E

    2004-06-24

    Long-lasting memories are known to require new transcription. Recent studies have highlighted a role for epigenetic alterations, including histone acetylation, in regulating gene expression. In this issue of Neuron, Alarcón et al. and Korzus et al. use two different mouse models of Rubinstein-Taybi syndrome to elucidate a role for the histone acetyltransferase activity of CREB binding protein (CBP) in long-term memory and plasticity.

  20. 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,…

  1. The chromosomal 2'-N-acetyltransferase of Providencia stuartii: physiological functions and genetic regulation.

    PubMed

    Macinga, D R; Rather, P N

    1999-02-01

    Intrinsic chromosomal acetyltransferases involved in aminoglycoside resistance have been identified in a number of bacteria. In Providencia stuartii, a chromosomal acetyltransferase (AAC(2')-Ia) has been characterized in detail. In addition to the ability to acetylate aminoglycosides, the AAC(2')-Ia enzyme has at least one physiological function, which is the acetylation of peptidoglycan. This modification is likely to influence the autolytic system in P. stuartii. The regulation of aac(2')-Ia expression is extremely complex involving at least seven regulatory genes acting in at least two pathways. This complexity in regulation indicates that aac(2')-Ia expression must be tightly controlled in response to different environmental conditions. This presumably reflects the importance of maintaining correct levels of peptidoglycan acetylation. In this review, a summary of data will be presented involving both the physiological and genetic aspects of aac(2')-Ia in P. stuartii.

  2. Spatial memory consolidation is associated with induction of several lysine-acetyltransferase (histone acetyltransferase) expression levels and H2B/H4 acetylation-dependent transcriptional events in the rat hippocampus.

    PubMed

    Bousiges, Olivier; Vasconcelos, Anne Pereira de; Neidl, Romain; Cosquer, Brigitte; Herbeaux, Karine; Panteleeva, Irina; Loeffler, Jean-Philippe; Cassel, Jean-Christophe; Boutillier, Anne-Laurence

    2010-12-01

    Numerous genetic studies have shown that the CREB-binding protein (CBP) is an essential component of long-term memory formation, through its histone acetyltransferase (HAT) function. E1A-binding protein p300 and p300/CBP-associated factor (PCAF) have also recently been involved in memory formation. By contrast, only a few studies have reported on acetylation modifications during memory formation, and it remains unclear as to how the system is regulated during this dynamic phase. We investigated acetylation-dependent events and the expression profiles of these HATs during a hippocampus-dependent task taxing spatial reference memory in the Morris water maze. We found a specific increase in H2B and H4 acetylation in the rat dorsal hippocampus, while spatial memory was being consolidated. This increase correlated with the degree of specific acetylated histones enrichment on some memory/plasticity-related gene promoters. Overall, a global increase in HAT activity was measured during this memory consolidation phase, together with a global increase of CBP, p300, and PCAF expression. Interestingly, these regulations were altered in a model of hippocampal denervation disrupting spatial memory consolidation, making it impossible for the hippocampus to recruit the CBP pathway (CBP regulation and acetylated-H2B-dependent transcription). CBP has long been thought to be present in limited concentrations in the cells. These results show, for the first time, that CBP, p300, and PCAF are dynamically modulated during the establishment of a spatial memory and are likely to contribute to the induction of a specific epigenetic tagging of the genome for hippocampus-dependent (spatial) memory consolidation. These findings suggest the use of HAT-activating molecules in new therapeutic strategies of pathological aging, Alzheimer's disease, and other neurodegenerative disorders.

  3. 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.

  4. Spatiotemporal expression of histone acetyltransferases, p300 and CBP, in developing embryonic hearts

    PubMed Central

    Chen, Guozhen; Zhu, Jing; Lv, Tiewei; Wu, Gang; Sun, Huichao; Huang, Xupei; Tian, Jie

    2009-01-01

    Histone acetyltransferases (HATs), p300 and cAMP response element binding protein (CREB)-binding protein (CBP) are two structurally related transcriptional co-activators that activate expression of many eukaryotic genes involved in cellular growth and signaling, muscle differentiation and embryogenesis. However, whether these proteins play important and different roles in mouse cardiogenesis is not clear. Here, we investigate the protein distributions and mRNA expression of the two HATs in embryonic and adult mouse heart during normal heart development by using immunohistochemical and RT-PCR techniques. The data from immunohistochemical experiments revealed that p300 was extensively present in nearly every region of the hearts from embryonic stages to the adulthood. However, no CBP expression was detected in embryonic hearts at day E7.5. CBP expression appeared at the later stages, and the distribution of CBP was less than that of p300. In the developmental hearts after E10.5, both for p300 and CBP, the mRNA expression levels reached a peak on day E10.5, and then were gradually decreased afterwards. These results reveal that both p300 and CBP are related to embryonic heart development. The dynamic expression patterns of these two enzymes during mouse heart development indicate that they may play an important role on heart development. However, there is a difference in spatiotemporal expression patterns between these two enzymes during heart development. The expression of p300 is earlier and more predominate, suggesting that p300 may play a more important role in embryonic heart development especially during cardiac precursor cell induction and interventricular septum formation. PMID:19272189

  5. 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.

  6. MOZ and MORF acetyltransferases: Molecular interaction, animal development and human disease.

    PubMed

    Yang, Xiang-Jiao

    2015-08-01

    Lysine residues are subject to many forms of covalent modification and one such modification is acetylation of the ε-amino group. Initially identified on histone proteins in the 1960s, lysine acetylation is now considered as an important form of post-translational modification that rivals phosphorylation. However, only about a dozen of human lysine acetyltransferases have been identified. Among them are MOZ (monocytic leukemia zinc finger protein; a.k.a. MYST3 and KAT6A) and its paralog MORF (a.k.a. MYST4 and KAT6B). Although there is a distantly related protein in Drosophila and sea urchin, these two enzymes are vertebrate-specific. They form tetrameric complexes with BRPF1 (bromodomain- and PHD finger-containing protein 1) and two small non-catalytic subunits. These two acetyltransferases and BRPF1 play key roles in various developmental processes; for example, they are important for development of hematopoietic and neural stem cells. The human KAT6A and KAT6B genes are recurrently mutated in leukemia, non-hematologic malignancies, and multiple developmental disorders displaying intellectual disability and various other abnormalities. In addition, the BRPF1 gene is mutated in childhood leukemia and adult medulloblastoma. Therefore, these two acetyltransferases and their partner BRPF1 are important in animal development and human disease.

  7. N-Acetyltransferase 1 Polymorphism and Breast Cancer Risk

    DTIC Science & Technology

    2011-10-01

    analysis of the N-acetyltransferase 1 gene (NAT1*) using polymerase chain reaction-restriction fragment- single strand conformation polymorphism assay...risk of smoking-induced lung cancer (Bouchardy et al., 1998). NAT1*14B is characterized by a single nucleotide polymorphism (SNP) G560A (rs4986782...Structure-function analyses of single nucleotide polymorphisms in human N-acetyltransferase 1. Drug Metab Rev 40, 169-184. Zheng, W., Deitz, A.C., Campbell

  8. HATS-31b through HATS-35b: Five Transiting Hot Jupiters Discovered By the HATSouth Survey

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

    We report the discovery of five new transiting hot-Jupiter planets discovered by the HATSouth survey, HATS-31b through HATS-35b. These planets orbit moderately bright stars with V magnitudes within the range of 11.9-14.4 mag while the planets span a range of masses of 0.88-1.22 {M}{{J}} and have somewhat inflated radii between 1.23 and 1.64 {R}{{J}}. These planets can be classified as typical hot Jupiters, with HATS-31b and HATS-35b being moderately inflated gas giant planets with radii of 1.64+/- 0.22 {R}{{J}} and {1.464}-0.044+0.069 {R}{{J}}, respectively, that can be used to constrain inflation mechanisms. All five systems present a higher Bayesian evidence for a fixed-circular-orbit model than for an eccentric orbit. The orbital periods range from 1.8209993+/- 0.0000016 day for HATS-35b) to 3.377960+/- 0.000012 day for HATS-31b. Additionally, HATS-35b orbits a relatively young F star with an age of 2.13+/- 0.51 Gyr. We discuss the analysis to derive the properties of these systems and compare them in the context of the sample of well-characterized transiting hot Jupiters known to date. 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 observations made with the MPG 2.2 m and Euler1.2 m Telescopes at the ESO Observatory in La Silla. This paper uses observations obtained with facilities of the Las Cumbres Observatory Global Telescope.

  9. 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

  10. Histone acetyltransferase Enok regulates oocyte polarization by promoting expression of the actin nucleation factor spire

    PubMed Central

    Huang, Fu; Paulson, Ariel; Dutta, Arnob; Venkatesh, Swaminathan; Smolle, Michaela

    2014-01-01

    KAT6 histone acetyltransferases (HATs) are highly conserved in eukaryotes and have been shown to play important roles in transcriptional regulation. Here, we demonstrate that the Drosophila KAT6 Enok acetylates histone H3 Lys 23 (H3K23) in vitro and in vivo. Mutants lacking functional Enok exhibited defects in the localization of Oskar (Osk) to the posterior end of the oocyte, resulting in loss of germline formation and abdominal segments in the embryo. RNA sequencing (RNA-seq) analysis revealed that spire (spir) and maelstrom (mael), both required for the posterior localization of Osk in the oocyte, were down-regulated in enok mutants. Chromatin immunoprecipitation showed that Enok is localized to and acetylates H3K23 at the spir and mael genes. Furthermore, Gal4-driven expression of spir in the germline can largely rescue the defective Osk localization in enok mutant ovaries. Our results suggest that the Enok-mediated H3K23 acetylation (H3K23Ac) promotes the expression of spir, providing a specific mechanism linking oocyte polarization to histone modification. PMID:25512562

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. Structural and Functional Evidence for Bacillus subtilis PaiA as a Novel N1-spermidine/spermine acetyltransferase (SSAT)

    SciTech Connect

    Forouhar,F.; Lee, I.; Vujcic, J.; Vujcic, S.; Shen, J.; Vorobiev, S.; Xiao, R.; Acton, T.; Montelione, G.; et al.

    2005-01-01

    Bacillus subtilis PaiA has been implicated in the negative control of sporulation as well as production of degradative enzymes. PaiA shares recognizable sequence homology with N-acetyltransferases, including those that can acetylate spermidine/spermine substrates (SSATs). We have determined the crystal structure of PaiA in complex with CoA at 1.9 Angstrom resolution and found that PaiA is a member of the N-acetyltransferase superfamily of enzymes. Unexpectedly, we observed the binding of an oxidized CoA dimer in the active site of PaiA, and the structural information suggests the substrates of the enzyme could be linear, positively charged compounds. Our biochemical characterization is also consistent with this possibility since purified PaiA possesses N1-acetyltransferase activity towards polyamine substrates including spermidine and spermine. Further, conditional over-expression of PaiA in bacteria results in increased acetylation of endogenous spermidine pools. Thus, our structural and biochemical analyses indicate that PaiA is a novel N-acetyltransferase capable of acetylating both spermidine and spermine. In this way, the pai operon may function in regulating intracellular polyamine concentrations and/or binding capabilities. In addition to preventing toxicity due to polyamine excess, this function may also serve to regulate expression of certain bacterial gene products such as those involved in sporulation.

  19. Evidence for arylamine N-acetyltransferase in Hymenolepis nana.

    PubMed

    Chung, J G; Kuo, H M; Wu, L T; Lai, J M; Lee, J H; Hung, C F

    1997-02-01

    N-acetyltransferase activities with p-aminobenzoic acid and 2-aminofluorene were determined in Hymenolepis nana, a cestode found in the intestine of the Sprague-Dawley rats. The N-acetyltransferase activity was determined using an acetyl CoA recycling assay and high pressure liquid chromatography. The N-acetyltransferase activities from a number of Hymenolepis nana whole tissue homogenizations were found to be 2.83 +/- 0.31 nmole/min/mg for 2-aminofluorene and 2.07 +/- 0.24 nmole/min/mg for p-aminobenzoic acid. The apparent Km and Vmax were 1.06 +/- 0.38 mM and 8.92 +/- 1.46 nmol/min/mg for 2-aminofluorene, and 2.16 +/- 0.19 mM and 12.68 +/- 2.26 nmol/min/mg for p-aminobenzoic acid. The optimal pH value for the enzyme activity was pH 8.0 for both substrates tested. The optimal temperature for enzyme activity was 37 degrees C for both substrates. The N-acetyltransferase activity was inhibited by iodacetamide. At 0.25 mM iodacetamide the activity was reduced 50% and 1.0 mM iodacetamide inhibited activity more than 90%. Among a series of divalent cations and salts, Fe2+, Ca2+ and Zn2+ were demonstrated to be the most potent inhibi-tors. Among the protease inhibitors, only ethylenediaminetetraacetic acid significantly protected N-acetyltransferase. Iodoacetate, in contrast to other agents, markedly inhibited N-acetyltransferase activity. This is the first demonstration of acetyl CoA:arylamine N-acetyltransferase activity in a cestode and extends the number of phyla in which this activity has been found.

  20. Six Thinking Hats: Argumentativeness and Response to Thinking Model.

    ERIC Educational Resources Information Center

    Carl, Walter John, III

    A study presents a perceptual model of thinking called the "Six Thinking Hats" and argumentativeness as a predictor of response to the model. The "Six Thinking Hats" model creates six artificial contexts for thinking, corresponding to the primary thought modes of objective, subjective, critical, and creative thinking, within a…

  1. Structure and evolution of the hAT transposon superfamily.

    PubMed

    Rubin, E; Lithwick, G; Levy, A A

    2001-07-01

    The maize transposon Activator (Ac) was the first mobile DNA element to be discovered. Since then, other elements were found that share similarity to Ac, suggesting that it belongs to a transposon superfamily named hAT after hobo from Drosophila, Ac from maize, and Tam3 from snapdragon. We addressed the structure and evolution of hAT elements by developing new tools for transposon mining and searching the public sequence databases for the hallmarks of hAT elements, namely the transposase and short terminal inverted repeats (TIRs) flanked by 8-bp host duplications. We found 147 hAT-related sequences in plants, animals, and fungi. Six conserved blocks could be identified in the transposase of most hAT elements. A total of 41 hAT sequences were flanked by TIRs and 8-bp host duplications and, out of these, 34 sequences had TIRs similar to the consensus determined in this work, suggesting that they are active or recently active transposons. Phylogenetic analysis and clustering of hAT sequences suggest that the hAT superfamily is very ancient, probably predating the plant-fungi-animal separation, and that, unlike previously proposed, there is no evidence that horizontal gene transfer was involved in the evolution of hAT elements.

  2. HATS-13b and HATS-14b: two transiting hot Jupiters from the HATSouth survey

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    We report the discovery of HATS-13b and HATS-14b, which are two hot-Jupiter transiting planets discovered by the HATSouth survey. The host stars are quite similar to each other (HATS-13: V = 13.9 mag, M⋆ = 0.96 M⊙, R⋆ = 0.89 R⊙, Teff ≈ 5500 K, [Fe/H] = 0.05; HATS-14: V = 13.8 mag, M⋆ = 0.97 M⊙, R⋆ = 0.93 R⊙, Teff ≈ 5350 K, [Fe/H] = 0.33) and both the planets orbit around them with a period of ~3 days and a separation of ~0.04 au. However, even though they are irradiated in a similar way, the physical characteristics of the two planets are very different. HATS-13b, with a mass of Mp = 0.543 ± 0.072 MJ and a radius of Rp = 1.212 ± 0.035 RJ, appears as an inflated planet, while HATS-14b, having a mass of Mp = 1.071 ± 0.070 MJ and a radius of Rp = 1.039 ± 0.032 RJ, is only slightly larger in radius than Jupiter. 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 (HESS) 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 (i) the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan; (ii) the MPG 2.2 m and the (iii) Euler 1.2 m Telescopes at the ESO Observatory in La Silla; (iv) the CTIO 0.9 m Telescope at the Observatory of Cerro Tololo.Appendix A is available in electronic form at http://www.aanda.orgFull Table A.1 and RV Tables 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/580/A63

  3. Arylamine N-Acetyltransferases in Mycobacteria

    PubMed Central

    Sim, Edith; Sandy, James; Evangelopoulos, Dimitrios; Fullam, Elizabeth; Bhakta, Sanjib; Westwood, Isaac; Krylova, Anna; Lack, Nathan; Noble, Martin

    2008-01-01

    Polymorphic Human arylamine N-acetyltransferase (NAT2) inactivates the anti-tubercular drug isoniazid by acetyltransfer from acetylCoA. There are active NAT proteins encoded by homologous genes in mycobacteria including M. tuberculosis, M. bovis BCG, M. smegmatis and M. marinum. Crystallographic structures of NATs from M. smegmatis and M. marinum, as native enzymes and with isoniazid bound share a similar fold with the first NAT structure, Salmonella typhimurium NAT. There are three approximately equal domains and an active site essential catalytic triad of cysteine, histidine and aspartate in the first two domains. An acetyl group from acetylCoA is transferred to cysteine and then to the acetyl acceptor e.g. isoniazid. M. marinum NAT binds CoA in a more open mode compared with CoA binding to human NAT2. The structure of mycobacterial NAT may promote its role in synthesis of cell wall lipids, identified through gene deletion studies. NAT protein is essential for survival of M. bovis BCG in macrophage as are the proteins encoded by other genes in the same gene cluster (hsaA-D). HsaA-D degrade cholesterol, essential for mycobacterial survival inside macrophage. Nat expression remains to be fully understood but is co-ordinated with hsaA-D and other stress response genes in mycobacteria. Amide synthase genes in the streptomyces are also nat homologues. The amide synthases are predicted to catalyse intramolecular amide bond formation and creation of cyclic molecules, e.g. geldanamycin. Lack of conservation of the CoA binding cleft residues of M. marinum NAT suggests the amide synthase reaction mechanism does not involve a soluble CoA intermediate during amide formation and ring closure. PMID:18680471

  4. 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.

  5. Identification of a BET family Bromodomain / Casein Kinase II / TAF-containing complex as a regulator of mitotic condensin function

    PubMed Central

    Kim, Hyun-Soo; Mukhopadhyay, Rituparna; Rothbart, Scott B.; Silva, Andrea C.; Vanoosthuyse, Vincent; Radovani, Ernest; Kislinger, Thomas; Roguev, Assen; Ryan, Colm J.; Xu, Jiewei; Jahari, Harlizawati; Hardwick, Kevin G.; Greenblatt, Jack F.; Krogan, Nevan J.; Fillingham, Jeffrey S.; Strahl, Brian D.; Bouhassira, Eric E.; Edelmann, Winfried; Keogh, Michael-Christopher

    2014-01-01

    SUMMARY Condensin is a central regulator of mitotic genome structure, with mutants showing poorly condensed chromosomes and profound segregation defects. Here we identify NCT complex, comprising the Nrc1 BET-family tandem bromodomain protein (SPAC631.02), Casein Kinase II (CKII) and several TAFs, as a regulator of condensin function. We show that NCT and condensin bind similar genomic regions, but only briefly co-localize during the periods of chromosome condensation and decondensation. This pattern of NCT binding at the core centromere, the region of maximal condensin enrichment, tracks the abundance of acetylated histone H4, as regulated by the Hat1-Mis16 acetyltransferase complex and recognized by the first Nrc1 bromodomain. Strikingly, mutants in NCT or Hat1-Mis16 restore the formation of segregation-competent chromosomes in cells containing defective condensin. These results are consistent with a model where NCT targets CKII to chromatin in a cell cycle-directed manner to modulate the activity of condensin during chromosome condensation and decondensation. PMID:24565511

  6. The Purification of Choline Acetyltransferase of Squid-Head Ganglia

    PubMed Central

    Husain, S. S.; Mautner, Henry G.

    1973-01-01

    Choline acetyltransferase (EC 2.3.1.6) isolated from the head ganglia of squid could be purified by use of mercurial-Sepharose columns as well as Sepharose columns to which the enzyme inhibitor p-(m-bromophenyl)vinyl pyridinium had been attached. These columns, in conjunction with 30-55% ammonium sulfate precipitation, 40-30% ammonium sulfate extraction, chromatography on sulfopropyl-Sephadex and on cellulose phosphate and hydroxylapatite columns, led to the isolation of three factions of choline acetyltransferase ranging in activity from 1000 to 4000 μmole/mg of protein/per hr. Polyacrylamide gel electrophoresis suggests that two of these fractions are homogeneous. The squid choline acetyltransferase is different from the mammalian-brain enzymes in having a larger molecular weight under the conditions used and in being relatively poorly inhibited by styryl pyridinium compounds. Images PMID:4521199

  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. 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.

  9. meso-[{Ru(phen)2}2(mu-HAT)]4+: a high-affinity DNA hairpin probe {HAT = 1,4,5,8,9,12-hexaazatriphenylene; phen = 1,10-phenanthroline}.

    PubMed

    Smith, Jayden A; Morgan, Joy L; Turley, Adam G; Collins, J Grant; Keene, F Richard

    2006-07-14

    1H NMR spectroscopy and fluorescent intercalator displacement (FID) assays have been used to investigate the DNA-binding abilities of two series of dinuclear polypyridyl ruthenium(II) complexes of the form [{Ru(L)2}2(mu-BL)]4+ {L = 2,2'-bipyridine (bpy), 4,4'-dimethyl-2,2'-bipyridine (Me2bpy), 1,10-phenanthroline (phen), or 4,7-dimethyl-1,10-phenanthroline (Me2phen); BL = 2,2'-bipyrimidine (bpm) or 1,4,5,8,9,12-hexaazatriphenylene (HAT)}. Preliminary FID surveys of these metal complexes against a variety of different oligonucleotides revealed that those complexes based upon the HAT bridging ligand induced greater fluorescence decreases in dye-bound DNA than did their bpm-bridged counterparts, suggesting a higher binding affinity by the HAT-bridged species. Furthermore, the greatest fluorescence decreases were typically observed in an oligonucleotide featuring a six-base hairpin loop. The apparent binding affinity of the metal complexes was also found to be a function of the stereochemistry and identity of the terminal ligands of the complex. The meso (DeltaLambda) stereoisomer generally induced greater fluorescence decreases than did either enantiomer (DeltaDelta or LambdaLambda), phen-based terminal ligands performed better than bpy-based terminal ligands, and those terminal ligands with methyl substituents demonstrated stronger apparent binding than did their non-methylated analogues. NMR experiments on meso-[{Ru(phen)2}2(mu-HAT)]4+ and meso-[{Ru(Me2phen)2}2(mu-HAT)]4+ demonstrated that both complexes bound with high affinity to the six-base hairpin oligonucleotide at the stem-loop interface and provided evidence to support stronger binding by the methylated species. meso-[{Ru(phen)2}2(mu-HAT)]4+ was found to bind poorly to duplex DNA and smaller four-base hairpin loops in FID and NMR experiments, whereas FID data suggest that the methylated analogue binds relatively strongly to most oligonucleotide sequences (the four- and six-base hairpins in particular). These

  10. 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.

  11. An acetyltransferase-independent function of Eso1 regulates centromere cohesion

    PubMed Central

    Lin, Su-Jiun; Tapia-Alveal, Claudia; Jabado, Omar J.; Germain, Doris; O’Connell, Matthew J.

    2016-01-01

    Eukaryotes contain three essential Structural Maintenance of Chromosomes (SMC) complexes: cohesin, condensin, and Smc5/6. Cohesin forms a ring-shaped structure that embraces sister chromatids to promote their cohesion. The cohesiveness of cohesin is promoted by acetylation of N-terminal lysines of the Smc3 subunit by the acetyltransferases Eco1 in Saccharomyces cerevisiae and the homologue, Eso1, in Schizosaccharomyces pombe. In both yeasts, these acetyltransferases are essential for cell viability. However, whereas nonacetylatable Smc3 mutants are lethal in S. cerevisiae, they are not in S. pombe. We show that the lethality of a temperature-sensitive allele of eso1 (eso1-H17) is due to activation of the spindle assembly checkpoint (SAC) and is associated with premature centromere separation. The lack of cohesion at the centromeres does not correlate with Psm3 acetylation or cohesin levels at the centromeres, but is associated ith significantly reduced recruitment of the cohesin regulator Pds5. The SAC activation in this context is dependent on Smc5/6 function, which is required to remove cohesin from chromosome arms but not centromeres. The mitotic defects caused by Smc5/6 and Eso1 dysfunction are cosuppressed in double mutants. This identifies a novel function (or functions) for Eso1 and Smc5/6 at centromeres and extends the functional relationships between these SMC complexes. PMID:27798241

  12. Bi-Directional Communication: A Critical Component of HAT

    NASA Technical Reports Server (NTRS)

    Shively, Robert J.

    2016-01-01

    Known problems with automation include lack of mode awareness, automation brittleness, and risk of miscalibrated trust. Human-Autonomy Teaming (HAT) is essential for improving these problems. This presentation outlines critical components for Human-Autonomy Teaming.

  13. 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.

  14. 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

  15. 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.

  16. Transpositionally active episomal hAT elements

    PubMed Central

    2009-01-01

    Background hAT elements and V(D)J recombination may have evolved from a common ancestral transposable element system. Extrachromosomal, circular forms of transposable elements (referred to here as episomal forms) have been reported yet their biological significance remains unknown. V(D)J signal joints, which resemble episomal transposable elements, have been considered non-recombinogenic products of V(D)J recombination and a safe way to dispose of excised chromosomal sequences. V(D)J signal joints can, however, participate in recombination reactions and the purpose of this study was to determine if hobo and Hermes episomal elements are also recombinogenic. Results Up to 50% of hobo/Hermes episomes contained two intact, inverted-terminal repeats and 86% of these contained from 1-1000 bp of intercalary DNA. Episomal hobo/Hermes elements were recovered from Musca domestica (a natural host of Hermes), Drosophila melanogaster (a natural host of hobo) and transgenic Drosophila melanogaster and Aedes aegypti (with autonomous Hermes elements). Episomal Hermes elements were recovered from unfertilized eggs of M. domestica and D. melanogaster demonstrating their potential for extrachromosomal, maternal transmission. Reintegration of episomal Hermes elements was observed in vitro and in vivo and the presence of Hermes episomes resulted in lower rates of canonical Hermes transposition in vivo. Conclusion Episomal hobo/Hermes elements are common products of element excision and can be maternally transmitted. Episomal forms of Hermes are capable of integration and also of influencing the transposition of canonical elements suggesting biological roles for these extrachromosomal elements in element transmission and regulation. PMID:20003420

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

    PubMed Central

    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. PMID:25365782

  18. 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.

  19. 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

  20. 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 Observatory

  1. 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.

  2. Structural Basis of Substrate-Binding Specificity of Human Arylamine N-acetyltransferases

    SciTech Connect

    Wu,H.; Dombrovsky, L.; Tempel, W.; Martin, F.; Loppnau, P.; Goodfellow, G.; Grant, D.; Plotnikov, A.

    2007-01-01

    The human arylamine N-acetyltransferases NAT1 and NAT2 play an important role in the biotransformation of a plethora of aromatic amine and hydrazine drugs. They are also able to participate in the bioactivation of several known carcinogens. Each of these enzymes is genetically variable in human populations, and polymorphisms in NAT genes have been associated with various cancers. Here we have solved the high resolution crystal structures of human NAT1 and NAT2, including NAT1 in complex with the irreversible inhibitor 2-bromoacetanilide, a NAT1 active site mutant, and NAT2 in complex with CoA, and have refined them to 1.7-, 1.8-, and 1.9- Angstroms resolution, respectively. The crystal structures reveal novel structural features unique to human NATs and provide insights into the structural basis of the substrate specificity and genetic polymorphism of these enzymes.

  3. 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.

  4. Radioenzymatic assays for aminoglycosides with kanamycin 6'- acetyltransferase

    SciTech Connect

    Weber, A.; Smith, A.L.; Opheim, K.E.

    1985-03-01

    To facilitate the rapid and accurate quantitation of parenterally administered aminoglycosides, the optimum conditions (pH, duration of incubation, and cofactor concentrations) were defined to permit radioenzymatic assays with kanamycin acetyltransferase. The accuracy in quantitating tobramycin, netilmicin, kanamycin, and amikacin at concentrations in the therapeutic range was greater than 90%, with a mean recovery of 102.8%. The mean of the interassay coefficient of variation was 7.8%. Typical standard curves at six different concentrations resulted in a correlation coefficient (r value) of greater than 0.99 for each aminoglycoside. The radioenzymatic assay correlates well with the bioassay (tobramycin and netilmicin) and radioimmunoassay (amikacin and kanamycin); the correlation coefficient is greater than 0.90 for all. The authors conclude that the radioenzymatic assay utilizing kanamycin 6'-acetyltransferase is feasible for all commercially available parenterally administered aminoglycosides.

  5. HAT-P-39b-HAT-P-41b: Three Highly Inflated Transiting Hot Jupiters

    NASA Astrophysics Data System (ADS)

    Hartman, J. D.; Bakos, G. Á.; Béky, B.; Torres, G.; Latham, D. W.; Csubry, Z.; Penev, K.; Shporer, A.; Fulton, B. J.; Buchhave, L. A.; Johnson, J. A.; Howard, A. W.; Marcy, G. W.; Fischer, D. A.; Kovács, G.; Noyes, R. W.; Esquerdo, G. A.; Everett, M.; Szklenár, T.; Quinn, S. N.; Bieryla, A.; Knox, R. P.; Hinz, P.; Sasselov, D. D.; Fűrész, G.; Stefanik, R. P.; Lázár, J.; Papp, I.; Sári, P.

    2012-11-01

    We report the discovery of three new transiting extrasolar planets orbiting moderately bright (V = 11.1, 11.7, and 12.4) F stars. The planets HAT-P-39b through HAT-P-41b have periods of P = 3.5439 days, 4.4572 days, and 2.6940 days, masses of 0.60 M J, 0.62 M J, and 0.80 M J, and radii of 1.57 R J, 1.73 R J, and 1.68 R J, respectively. They orbit stars with masses of 1.40 M ⊙, 1.51 M ⊙, and 1.51 M ⊙, respectively. The three planets are members of an emerging population of highly inflated Jupiters with 0.4 M J < M < 1.5 M J and R > 1.5 R J. 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 (A201Hr, A289Hr, and A284Hr), NASA (N049Hr, N018Hr, N167Hr, N029Hr, N108Hr, and N154Hr), and the NOAO Gemini/Keck time-exchange program (G329Hr). Based in part on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. Based in part on observations obtained with facilities of the Las Cumbres Observatory Global Telescope. Observations reported here were obtained at the MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona.

  6. HAT-P-20b-HAT-P-23b: Four Massive Transiting Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Bakos, G. Á.; Hartman, J.; Torres, G.; Latham, D. W.; Kovács, Géza; Noyes, R. W.; Fischer, D. A.; Johnson, J. A.; Marcy, G. W.; Howard, A. W.; Kipping, D.; Esquerdo, G. A.; Shporer, A.; Béky, B.; Buchhave, L. A.; Perumpilly, G.; Everett, M.; Sasselov, D. D.; Stefanik, R. P.; Lázár, J.; Papp, I.; Sári, P.

    2011-12-01

    We report the discovery of four relatively massive (2-7 M 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 Tc = 2455080.92661 ± 0.00021 (BJDUTC), and transit duration 0.0770 ± 0.0008 days. The host star has a mass of 0.76 ± 0.03 M ⊙, radius of 0.69 ± 0.02 R ⊙, 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 J and a radius of 0.867 ± 0.033 R J yielding a mean density of 13.78 ± 1.50 g cm-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 Tc = 2454996.41312 ± 0.00069, and transit duration 0.1530 ± 0.0027 days. The host star has a mass of 0.95 ± 0.04 M ⊙, radius of 1.10 ± 0.08 R ⊙, 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 J and a radius of 1.024 ± 0.092 R J yielding a mean density of 4.68+1.59 - 0.99 g cm-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 Tc = 2454930.22001 ± 0.00025, and transit duration 0.1196 ± 0.0014 days. The host star has a mass of 0.92 ± 0.03 M ⊙, radius of 1.04 ± 0.04 R ⊙, effective temperature 5302 ± 80 K, and metallicity [Fe/H] = +0.24 ± 0.08. The planet has a mass of 2.147 ± 0.061 M J and a compact radius of 1.080 ± 0.058 R J yielding a mean density of 2.11+0.40 - 0.29 g cm-3. The host star also harbors an M-dwarf companion at a wide separation. Finally, HAT-P-23b orbits the V = 12.432 G0 dwarf star GSC 1632-01396 on a close to circular orbit, with a period P = 1.212884 ± 0.000002 days

  7. MYST protein acetyltransferase activity requires active site lysine autoacetylation.

    PubMed

    Yuan, Hua; Rossetto, Dorine; Mellert, Hestia; Dang, Weiwei; Srinivasan, Madhusudan; Johnson, Jamel; Hodawadekar, Santosh; Ding, Emily C; Speicher, Kaye; Abshiru, Nebiyu; Perry, Rocco; Wu, Jiang; Yang, Chao; Zheng, Y George; Speicher, David W; Thibault, Pierre; Verreault, Alain; Johnson, F Bradley; Berger, Shelley L; Sternglanz, Rolf; McMahon, Steven B; Côté, Jacques; Marmorstein, Ronen

    2012-01-04

    The MYST protein lysine acetyltransferases are evolutionarily conserved throughout eukaryotes and acetylate proteins to regulate diverse biological processes including gene regulation, DNA repair, cell-cycle regulation, stem cell homeostasis and development. Here, we demonstrate that MYST protein acetyltransferase activity requires active site lysine autoacetylation. The X-ray crystal structures of yeast Esa1 (yEsa1/KAT5) bound to a bisubstrate H4K16CoA inhibitor and human MOF (hMOF/KAT8/MYST1) reveal that they are autoacetylated at a strictly conserved lysine residue in MYST proteins (yEsa1-K262 and hMOF-K274) in the enzyme active site. The structure of hMOF also shows partial occupancy of K274 in the unacetylated form, revealing that the side chain reorients to a position that engages the catalytic glutamate residue and would block cognate protein substrate binding. Consistent with the structural findings, we present mass spectrometry data and biochemical experiments to demonstrate that this lysine autoacetylation on yEsa1, hMOF and its yeast orthologue, ySas2 (KAT8) occurs in solution and is required for acetylation and protein substrate binding in vitro. We also show that this autoacetylation occurs in vivo and is required for the cellular functions of these MYST proteins. These findings provide an avenue for the autoposttranslational regulation of MYST proteins that is distinct from other acetyltransferases but draws similarities to the phosphoregulation of protein kinases.

  8. MYST protein acetyltransferase activity requires active site lysine autoacetylation

    PubMed Central

    Yuan, Hua; Rossetto, Dorine; Mellert, Hestia; Dang, Weiwei; Srinivasan, Madhusudan; Johnson, Jamel; Hodawadekar, Santosh; Ding, Emily C; Speicher, Kaye; Abshiru, Nebiyu; Perry, Rocco; Wu, Jiang; Yang, Chao; Zheng, Y George; Speicher, David W; Thibault, Pierre; Verreault, Alain; Johnson, F Bradley; Berger, Shelley L; Sternglanz, Rolf; McMahon, Steven B; Côté, Jacques; Marmorstein, Ronen

    2012-01-01

    The MYST protein lysine acetyltransferases are evolutionarily conserved throughout eukaryotes and acetylate proteins to regulate diverse biological processes including gene regulation, DNA repair, cell-cycle regulation, stem cell homeostasis and development. Here, we demonstrate that MYST protein acetyltransferase activity requires active site lysine autoacetylation. The X-ray crystal structures of yeast Esa1 (yEsa1/KAT5) bound to a bisubstrate H4K16CoA inhibitor and human MOF (hMOF/KAT8/MYST1) reveal that they are autoacetylated at a strictly conserved lysine residue in MYST proteins (yEsa1-K262 and hMOF-K274) in the enzyme active site. The structure of hMOF also shows partial occupancy of K274 in the unacetylated form, revealing that the side chain reorients to a position that engages the catalytic glutamate residue and would block cognate protein substrate binding. Consistent with the structural findings, we present mass spectrometry data and biochemical experiments to demonstrate that this lysine autoacetylation on yEsa1, hMOF and its yeast orthologue, ySas2 (KAT8) occurs in solution and is required for acetylation and protein substrate binding in vitro. We also show that this autoacetylation occurs in vivo and is required for the cellular functions of these MYST proteins. These findings provide an avenue for the autoposttranslational regulation of MYST proteins that is distinct from other acetyltransferases but draws similarities to the phosphoregulation of protein kinases. PMID:22020126

  9. A Naturally-Occurring Histone Acetyltransferase Inhibitor Derived from Garcinia indica Impairs Newly Acquired and Reactivated Fear Memories

    PubMed Central

    Maddox, Stephanie A.; Watts, Casey S.; Doyère, Valérie; Schafe, Glenn E.

    2013-01-01

    The study of the cellular and molecular mechanisms underlying the consolidation and reconsolidation of traumatic fear memories has progressed rapidly in recent years, yet few compounds have emerged that are readily useful in a clinical setting for the treatment of anxiety disorders such as post-traumatic stress disorder (PTSD). Here, we use a combination of biochemical, behavioral, and neurophysiological methods to systematically investigate the ability of garcinol, a naturally-occurring histone acetyltransferase (HAT) inhibitor derived from the rind of the fruit of the Kokum tree (Garcina indica), to disrupt the consolidation and reconsolidation of Pavlovian fear conditioning, a widely studied rodent model of PTSD. We show that local infusion of garcinol into the rat lateral amygdala (LA) impairs the training and retrieval-related acetylation of histone H3 in the LA. Further, we show that either intra-LA or systemic administration of garcinol within a narrow window after either fear conditioning or fear memory retrieval significantly impairs the consolidation and reconsolidation of a Pavlovian fear memory and associated neural plasticity in the LA. Our findings suggest that a naturally-occurring compound derived from the diet that regulates chromatin function may be useful in the treatment of newly acquired or recently reactivated traumatic memories. PMID:23349897

  10. 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.

  11. 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.

  12. The Active Latitudes of HAT-P-11

    NASA Astrophysics Data System (ADS)

    Morris, Brett; Hebb, Leslie; Davenport, James R. A.; Hawley, Suzanne L.

    2017-01-01

    Transiting planets map the brightness of their host stars, as the flux lost during exoplanet transits is proportional to the integrated flux occulted by the planet. We analyze four years of Kepler short-cadence photometry of HAT-P-11 - an active K4 dwarf with a 29 day rotation period, orbited by a hot-Neptune. Due to its highly-misaligned orbit, the planet occults most stellar latitudes during each transit, and the latitude distribution of spots is encoded in the transit light curves. We model each spot occultation in transit to create a spot map of HAT-P-11, which reveals two active latitudes near ±17 degrees. We investigate whether the spot distribution changes in time, and we compare the spot latitude distributions of HAT-P-11 and the Sun throughout the solar activity cycle.

  13. 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

  14. Geodetic VLBI Observations with the Hat Creek Telescope

    NASA Astrophysics Data System (ADS)

    Shaffer, D. B.; NASA/Gsfc Geodetic VLBI Group

    1993-05-01

    Geodetic VLBI observations made with the Hat Creek 85' antenna were important contributions to the NASA Crustal Dynamics Program (CDP). Among other things, the CDP studied motions of the Earth's crustal plates and deformation in the vicinity of the San Andreas Fault in California. The 85' antenna was one of the three fundamental anchor points in California east of the San Andreas fault that were used from 1983 to 1991 to determine the motions at various mobile VLBI sites along the San Andreas and to determine the Pacific plate motions at Vandenberg Air Force Base and Ft. Ord (California) and Kauai (Hawaii). The Hat Creek site itself was found to be moving 10.6 +/- 0.4 (one sigma ) mm/yr to the WNW (PA 305deg ) with respect to a ``stable" eastern North America. Hat Creek is located near the western edge of the Northern Basin and Range province. Its motion is thought to be a combination of WNW extension across the Basin and Range, and a small component of NW elastic deformation due to the interaction between the North American and Pacific plates. Geodetic VLBI measurements from Hat Creek to the nearby Quincy and the more distant Ely (Nevada) and Platteville (Colorado) mobile sites were the key measurements in defining the extension rate for the Northern Basin and Range as 8 +/- 2 mm/yr (PA ~ 300deg ). Hat Creek was also the anchor point for measuring a 5 cm northward seismic displacement at the Ft. Ord mobile site due to the Loma Prieta earthquake. We will show the motion of California and Pacific basin sites for which Hat Creek contributed important data.

  15. 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.

  16. 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.

  17. ORBITAL ORIENTATIONS OF EXOPLANETS: HAT-P-4b IS PROGRADE AND HAT-P-14b IS RETROGRADE

    SciTech Connect

    Winn, Joshua N.; Albrecht, Simon; Howard, Andrew W.; Marcy, Geoffrey W.; Isaacson, Howard; Johnson, John Asher; Crepp, Justin R.; Morton, Timothy D.; Shporer, Avi; Bakos, Gaspar A.; Hartman, Joel D.; Holman, Matthew J.

    2011-02-15

    We present observations of the Rossiter-McLaughlin effect for two exoplanetary systems, revealing the orientations of their orbits relative to the rotation axes of their parent stars. HAT-P-4b is prograde, with a sky-projected spin-orbit angle of {lambda} = -4.9 {+-} 11.9 deg. In contrast, HAT-P-14b is retrograde, with {lambda} = 189.1 {+-} 5.1 deg. These results conform with a previously noted pattern among the stellar hosts of close-in giant planets: hotter stars have a wide range of obliquities and cooler stars have low obliquities. This, in turn, suggests that three-body dynamics and tidal dissipation are responsible for the short-period orbits of many exoplanets. In addition, our data revealed a third body in the HAT-P-4 system, which could be a second planet or a companion star.

  18. 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.

  19. 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.

  20. Sulfonamide-Based Inhibitors of Aminoglycoside Acetyltransferase Eis Abolish Resistance to Kanamycin in Mycobacterium tuberculosis.

    PubMed

    Garzan, Atefeh; Willby, Melisa J; Green, Keith D; Gajadeera, Chathurada S; Hou, Caixia; Tsodikov, Oleg V; Posey, James E; Garneau-Tsodikova, Sylvie

    2016-12-08

    A two-drug combination therapy where one drug targets an offending cell and the other targets a resistance mechanism to the first drug is a time-tested, yet underexploited approach to combat or prevent drug resistance. By high-throughput screening, we identified a sulfonamide scaffold that served as a pharmacophore to generate inhibitors of Mycobacterium tuberculosis acetyltransferase Eis, whose upregulation causes resistance to the aminoglycoside (AG) antibiotic kanamycin A (KAN) in Mycobacterium tuberculosis. Rational systematic derivatization of this scaffold to maximize Eis inhibition and abolish the Eis-mediated KAN resistance of M. tuberculosis yielded several highly potent agents. A crystal structure of Eis in complex with one of the most potent inhibitors revealed that the inhibitor bound Eis in the AG-binding pocket held by a conformationally malleable region of Eis (residues 28-37) bearing key hydrophobic residues. These Eis inhibitors are promising leads for preclinical development of innovative AG combination therapies against resistant TB.

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

    PubMed

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

    2011-06-14

    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.

  2. Potent Inhibitors of Acetyltransferase Eis Overcome Kanamycin Resistance in Mycobacterium tuberculosis.

    PubMed

    Willby, Melisa J; Green, Keith D; Gajadeera, Chathurada S; Hou, Caixia; Tsodikov, Oleg V; Posey, James E; Garneau-Tsodikova, Sylvie

    2016-06-17

    A major cause of tuberculosis (TB) resistance to the aminoglycoside kanamycin (KAN) is the Mycobacterium tuberculosis (Mtb) acetyltransferase Eis. Upregulation of this enzyme is responsible for inactivation of KAN through acetylation of its amino groups. A 123 000-compound high-throughput screen (HTS) yielded several small-molecule Eis inhibitors that share an isothiazole S,S-dioxide heterocyclic core. These were investigated for their structure-activity relationships. Crystal structures of Eis in complex with two potent inhibitors show that these molecules are bound in the conformationally adaptable aminoglycoside binding site of the enzyme, thereby obstructing binding of KAN for acetylation. Importantly, we demonstrate that several Eis inhibitors, when used in combination with KAN against resistant Mtb, efficiently overcome KAN resistance. This approach paves the way toward development of novel combination therapies against aminoglycoside-resistant TB.

  3. RSRM top hat cover simulator lightning test, volume 1

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The test sequence was to measure electric and magnetic fields induced inside a redesigned solid rocket motor case when a simulated lightning discharge strikes an exposed top hat cover simulator. The test sequence was conducted between 21 June and 17 July 1990. Thirty-six high rate-of-rise Marx generator discharges and eight high current bank discharges were injected onto three different test article configurations. Attach points included three locations on the top hat cover simulator and two locations on the mounting bolts. Top hat cover simulator and mounting bolt damage and grain cover damage was observed. Overall electric field levels were well below 30 kilowatts/meter. Electric field levels ranged from 184.7 to 345.9 volts/meter and magnetic field levels were calculated from 6.921 to 39.73 amperes/meter. It is recommended that the redesigned solid rocket motor top hat cover be used in Configuration 1 or Configuration 2 as an interim lightning protection device until a lightweight cover can be designed.

  4. HATS: A Design Procedure for Routine Business Documents.

    ERIC Educational Resources Information Center

    Baker, William H.

    2001-01-01

    Describes an approach to teaching students a basic design process for routine business documents like memos, letters, and reports. Outlines the design principles of HATS (Headings, Access, Typography, and Spacing), how they apply in before-and-after fashion to various documents, and discusses an assignment in which students redesign an existing…

  5. Degrees of Freedom and Three-Cornered Hats

    DTIC Science & Technology

    2001-11-01

    differences between the clocks. To our knowledge, there has been no method of determining a confidence interval for such a siability 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.

  6. 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.

  7. 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…

  8. 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…

  9. My Essential Booklist for Museum Educators Wearing Many Hats

    ERIC Educational Resources Information Center

    Schatz, Dennis

    2006-01-01

    Besides being a content expert, it is critical for today's museum educator to be a marketer, a collaborator, and to understand how people learn best in a museum environment. This article provides a list of six books that the author recommends as essential references for today's museum educator who must wear many hats. (Contains 3 notes.)

  10. 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.

  11. 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

  12. 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.

  13. 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…

  14. Choline acetyltransferase expression does not identify early pathogenic events in fetal SMA spinal cord.

    PubMed

    Soler-Botija, Carolina; Cuscó, Ivón; López, Eva; Clua, Agustín; Gich, Ignasi; Baiget, Montserrat; Ferrer, Isidre; Tizzano, Eduardo F

    2005-03-01

    We investigated the expression of choline acetyltransferase, a specific marker for cholinergic neurons, in control and spinal muscular atrophy fetuses and newborns. By immunoblot we observed at 12 and 15 weeks a similar pattern of choline acetyltransferase expression in spinal muscular atrophy with respect to controls, although at 22 weeks this expression was reduced, probably due to a smaller number of motor neurons in the spinal muscular atrophy spinal cord. By immunohistochemistry, the counting of positive and negative motor neurons for choline acetyltransferase immunostaining in control and spinal muscular atrophy fetuses showed a similar proportion at all stages analyzed. The choline acetyltransferase-negative motor neurons were of similar appearance in both groups. After birth, chromatolytic motor neurons were detected in spinal muscular atrophy, all of which were choline acetyltransferase-negative. Our results in spinal muscular atrophy fetuses indicate that choline acetyltransferase immunostaining does not identify early events in neuronal pathogenesis and suggest that the spinal muscular atrophy surviving motor neurons may not be dysfunctional during this period. Furthermore, spinal muscular atrophy choline acetyltransferase-negative motor neurons showed detectable pathological changes only after birth, indicating that choline acetyltransferase is a late marker for motor neuron degeneration and not a primary contributing factor in this process.

  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. Formulation of Complex Action Theory

    NASA Astrophysics Data System (ADS)

    Nagao, K.; Nielsen, H. B.

    2011-12-01

    We formulate a complex action theory which includes operators of coordinate and momentum hat{q} and hat{p} being replaced with non-hermitian operators hat{q}_{new} and hat{p}_{new}, and their eigenstates | q >_{new} and | p >_{new} with complex eigenvalues q and p. Introducing a philosophy of keeping the analyticity in path integration variables, we define a modified set of complex conjugate, real and imaginary parts, hermitian conjugates and bras, and explicitly construct hat{q}_{new}, hat{p}_{new}, |q >_{new} and |p >_{new} by formally squeezing coherent states. We also pose a theorem on the relation between functions on the phase space and the corresponding operators. Only in our formalism can we describe a complex action theory or a real action theory with complex saddle points in the tunneling effect etc. in terms of bras and kets in the functional integral. Furthermore, in a system with a non-hermitian diagonalizable bounded Hamiltonian, we show that the mechanism to obtain a hermitian Hamiltonian after a long time development proposed in our paper [Prog. Theor. Phys. 125 (2011), 633] works also in the complex coordinate formalism. If the hermitian Hamiltonian is given in a local form, a conserved probability current density can be constructed with two kinds of wave functions.

  17. The Long Duration Flight of the TopHat Experiment

    NASA Technical Reports Server (NTRS)

    Silverberg, R.; Aguirre, J.; Bezaire, J.; Cheng, E.; Cordone, S.; Christensen, P. R.; Cottingham, D.; Crawford, T.; Fixsen, D.; Meyer, S. S.; Oegerle, William (Technical Monitor)

    2002-01-01

    TopHat is a balloon-borne instrument designed to operate on the top of a balloon. From this location, the experiment could efficiently observe using a clean beam with extremely low sidelobes. The experiment was designed to scan a large portion of the sky directly above it and to map the anisotropy of the Cosmic Microwave Background (CMBR) and thermal emission from galactic dust. The instrument used a one meter class telescope with a five band single pixel radiometer spanning the frequency range from 150-600 GHz. The radiometer used bolometric detectors operating at approx. 250 mK. Here, we will report on the flight of the TopHat experiment over Antarctica in January, 2001 and describe the scientific goals, the operation, and in-flight performance.

  18. 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.

  19. 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.

  20. The MOF chromobarrel domain controls genome-wide H4K16 acetylation and spreading of the MSL complex.

    PubMed

    Conrad, Thomas; Cavalli, Florence M G; Holz, Herbert; Hallacli, Erinc; Kind, Jop; Ilik, Ibrahim; Vaquerizas, Juan M; Luscombe, Nicholas M; Akhtar, Asifa

    2012-03-13

    The histone H4 lysine 16 (H4K16)-specific acetyltransferase MOF is part of two distinct complexes involved in X chromosome dosage compensation and autosomal transcription regulation. Here we show that the MOF chromobarrel domain is essential for H4K16 acetylation throughout the Drosophila genome and is required for spreading of the male-specific lethal (MSL) complex on the X chromosome. The MOF chromobarrel domain directly interacts with nucleic acids and potentiates MOF's enzymatic activity after chromatin binding, making it a unique example of a chromo-like domain directly controlling acetylation activity in vivo. We also show that the Drosophila-specific N terminus of MOF has evolved to perform sex-specific functions. It modulates nucleosome binding and HAT activity and controls MSL complex assembly, thus regulating MOF function in dosage compensation. We propose that MOF has been especially tailored to achieve tight regulation of its enzymatic activity and enable its dual role on X and autosomes.

  1. 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.

  2. 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

  3. 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.

  4. 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

  5. Melatonin production: proteasomal proteolysis in serotonin N-acetyltransferase regulation.

    PubMed

    Gastel, J A; Roseboom, P H; Rinaldi, P A; Weller, J L; Klein, D C

    1998-02-27

    The nocturnal increase in circulating melatonin in vertebrates is regulated by 10- to 100-fold increases in pineal serotonin N-acetyltransferase (AA-NAT) activity. Changes in the amount of AA-NAT protein were shown to parallel changes in AA-NAT activity. When neural stimulation was switched off by either light exposure or L-propranolol-induced beta-adrenergic blockade, both AA-NAT activity and protein decreased rapidly. Effects of L-propranolol were blocked in vitro by dibutyryl adenosine 3',5'-monophosphate (cAMP) or inhibitors of proteasomal proteolysis. This result indicates that adrenergic-cAMP regulation of AA-NAT is mediated by rapid reversible control of selective proteasomal proteolysis. Similar proteasome-based mechanisms may function widely as selective molecular switches in vertebrate neural systems.

  6. In Vitro Targeting Reveals Intrinsic Histone Tail Specificity of the Sin3/Histone Deacetylase and N-CoR/SMRT Corepressor Complexes

    PubMed Central

    Vermeulen, Michiel; Carrozza, Michael J.; Lasonder, Edwin; Workman, Jerry L.; Logie, Colin; Stunnenberg, Hendrik G.

    2004-01-01

    The histone code is among others established via differential acetylation catalyzed by histone acetyltransferases (HATs) and histone deacetylases (HDACs). To unambiguously determine the histone tail specificity of HDAC-containing complexes, we have established an in vitro system consisting of nucleosomal templates reconstituted with hyperacetylated histones or recombinant histones followed by acetylation with native SAGA or NuA4. Selective targeting of the mammalian Sin3/HDAC and N-CoR/SMRT corepressor complexes by using specific chimeric repressors created a near physiological setting to assess their histone tail specificity. Recruitment of the Sin3/HDAC complex to nucleosomal templates preacetylated with SAGA or NuA4 resulted in deacetylation of histones H3 and H4, whereas recruitment of N-CoR/SMRT resulted in deacetylation of histone H3 only. These results provide solid evidence that HDAC-containing complexes display distinct, intrinsic histone tail specificities and hence may function differently to regulate chromatin structure and transcription. PMID:14993276

  7. The GAPS Programme with HARPS-N at TNG. VIII. Observations of the Rossiter-McLaughlin effect and characterisation of the transiting planetary systems HAT-P-36 and WASP-11/HAT-P-10

    NASA Astrophysics Data System (ADS)

    Mancini, L.; Esposito, M.; Covino, E.; Raia, G.; Southworth, J.; Tregloan-Reed, J.; Biazzo, K.; Bonomo, A. S.; 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, Th.; Maggio, A.; Micela, G.; Molinari, E.; Pagano, I.; Piotto, G.; Rainer, M.; Scandariato, G.; Smareglia, R.; Zanmar Sanchez, R.

    2015-07-01

    Context. Orbital obliquity is thought to be a fundamental parameter in tracing the physical mechanisms that cause the migration of giant planets from the snow line down to roughly 10-2 au from their host stars. We are carrying out a large programme to estimate the spin-orbit alignment of a sample of transiting planetary systems to study what the possible configurations of orbital obliquity are and whether they correlate with other stellar or planetary properties. Aims: We determine the true and the projected obliquity of HAT-P-36 and WASP-11/HAT-P-10 systems, respectively, which are both composed of a relatively cool star (with effective temperature Teff< 6100 K) and a hot-Jupiter planet. Methods: Thanks to the high-resolution spectrograph HARPS-N, we observed the Rossiter-McLaughlin effect for both systems by acquiring precise (3-8 m s-1) radial-velocity measurements during planetary transit events. We also present photometric observations comprising six light curves that cover five transit events, which were obtained using three medium-class telescopes. One transit of WASP-11/HAT-P-10 was followed simultaneously from two observatories. The three transit light curves of HAT-P-36 b show anomalies that are attributable to starspot complexes on the surface of the parent star, in agreement with the analysis of its spectra that indicates moderate activity ( log R'HK = -4.65 dex). By analysing the complete HATNet data set of HAT-P-36, we estimated the stellar rotation period by detecting a periodic photometric modulation in the light curve caused by star spots, obtaining Prot = 15.3 ± 0.4 days, which implies that the inclination of the stellar rotational axis with respect to the line of sight is i⋆ = 65° ± 34°. Results: We used the new spectroscopic and photometric data to revise the main physical parameters and measure the sky-projected misalignment angle of the two systems. We found λ = -14° ± 18° for HAT-P-36 and λ = 7° ± 5° for WASP-11/HAT-P-10

  8. HAT-P-44b, HAT-P-45b, and HAT-P-46b: Three Transiting Hot Jupiters in Possible Multi-planet Systems

    NASA Astrophysics Data System (ADS)

    Hartman, J. D.; Bakos, G. Á.; Torres, G.; Kovács, G.; Johnson, J. A.; Howard, A. W.; Marcy, G. W.; Latham, D. W.; Bieryla, A.; Buchhave, L. A.; Bhatti, W.; Béky, B.; Csubry, Z.; Penev, K.; de Val-Borro, M.; Noyes, R. W.; Fischer, D. A.; Esquerdo, G. A.; Everett, M.; Szklenár, T.; Zhou, G.; Bayliss, D.; Shporer, A.; Fulton, B. J.; Sanchis-Ojeda, R.; Falco, E.; Lázár, J.; Papp, I.; Sári, P.

    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 J, and radii of 1.24, 1.43, and 1.28 R J. The stellar hosts have masses of 0.94, 1.26, and 1.28 M ⊙. 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 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-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 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. 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

  9. 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.

  10. Inference of Functionally-Relevant N-acetyltransferase Residues Based on Statistical Correlations.

    PubMed

    Neuwald, Andrew F; Altschul, Stephen F

    2016-12-01

    Over evolutionary time, members of a superfamily of homologous proteins sharing a common structural core diverge into subgroups filling various functional niches. At the sequence level, such divergence appears as correlations that arise from residue patterns distinct to each subgroup. Such a superfamily may be viewed as a population of sequences corresponding to a complex, high-dimensional probability distribution. Here we model this distribution as hierarchical interrelated hidden Markov models (hiHMMs), which describe these sequence correlations implicitly. By characterizing such correlations one may hope to obtain information regarding functionally-relevant properties that have thus far evaded detection. To do so, we infer a hiHMM distribution from sequence data using Bayes' theorem and Markov chain Monte Carlo (MCMC) sampling, which is widely recognized as the most effective approach for characterizing a complex, high dimensional distribution. Other routines then map correlated residue patterns to available structures with a view to hypothesis generation. When applied to N-acetyltransferases, this reveals sequence and structural features indicative of functionally important, yet generally unknown biochemical properties. Even for sets of proteins for which nothing is known beyond unannotated sequences and structures, this can lead to helpful insights. We describe, for example, a putative coenzyme-A-induced-fit substrate binding mechanism mediated by arginine residue switching between salt bridge and π-π stacking interactions. A suite of programs implementing this approach is available (psed.igs.umaryland.edu).

  11. Inference of Functionally-Relevant N-acetyltransferase Residues Based on Statistical Correlations

    PubMed Central

    Neuwald, Andrew F.

    2016-01-01

    Over evolutionary time, members of a superfamily of homologous proteins sharing a common structural core diverge into subgroups filling various functional niches. At the sequence level, such divergence appears as correlations that arise from residue patterns distinct to each subgroup. Such a superfamily may be viewed as a population of sequences corresponding to a complex, high-dimensional probability distribution. Here we model this distribution as hierarchical interrelated hidden Markov models (hiHMMs), which describe these sequence correlations implicitly. By characterizing such correlations one may hope to obtain information regarding functionally-relevant properties that have thus far evaded detection. To do so, we infer a hiHMM distribution from sequence data using Bayes’ theorem and Markov chain Monte Carlo (MCMC) sampling, which is widely recognized as the most effective approach for characterizing a complex, high dimensional distribution. Other routines then map correlated residue patterns to available structures with a view to hypothesis generation. When applied to N-acetyltransferases, this reveals sequence and structural features indicative of functionally important, yet generally unknown biochemical properties. Even for sets of proteins for which nothing is known beyond unannotated sequences and structures, this can lead to helpful insights. We describe, for example, a putative coenzyme-A-induced-fit substrate binding mechanism mediated by arginine residue switching between salt bridge and π-π stacking interactions. A suite of programs implementing this approach is available (psed.igs.umaryland.edu). PMID:28002465

  12. 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.

  13. 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

  14. Structural and Biochemical Characterization of Acinetobacter spp. Aminoglycoside Acetyltransferases Highlights Functional and Evolutionary Variation among Antibiotic Resistance Enzymes.

    PubMed

    Stogios, Peter J; Kuhn, Misty L; Evdokimova, Elena; Law, Melissa; Courvalin, Patrice; Savchenko, Alexei

    2017-02-10

    Modification of aminoglycosides by N-acetyltransferases (AACs) is one of the major mechanisms of resistance to these antibiotics in human bacterial pathogens. More than 50 enzymes belonging to the AAC(6') subfamily have been identified in Gram-negative and Gram-positive clinical isolates. Our understanding of the molecular function and evolutionary origin of these resistance enzymes remains incomplete. Here we report the structural and enzymatic characterization of AAC(6')-Ig and AAC(6')-Ih from Acinetobacter spp. The crystal structure of AAC(6')-Ig in complex with tobramycin revealed a large substrate-binding cleft remaining partially unoccupied by the substrate, which is in stark contrast with the previously characterized AAC(6')-Ib enzyme. Enzymatic analysis indicated that AAC(6')-Ig and -Ih possess a broad specificity against aminoglycosides but with significantly lower turnover rates as compared to other AAC(6') enzymes. Structure- and function-informed phylogenetic analysis of AAC(6') enzymes led to identification of at least three distinct subfamilies varying in oligomeric state, active site composition, and drug recognition mode. Our data support the concept of AAC(6') functionality originating through convergent evolution from diverse Gcn5-related-N-acetyltransferase (GNAT) ancestral enzymes, with AAC(6')-Ig and -Ih representing enzymes that may still retain ancestral nonresistance functions in the cell as provided by their particular active site properties.

  15. The acetyltransferase activity of San stabilizes the mitotic cohesin at the centromeres in a shugoshin-independent manner

    PubMed Central

    Hou, Fajian; Chu, Chih-Wen; Kong, Xiangduo; Yokomori, Kyoko; Zou, Hui

    2007-01-01

    Proper sister chromatid cohesion is critical for maintaining genetic stability. San is a putative acetyltransferase that is important for sister chromatid cohesion in Drosophila melanogaster, but not in budding yeast. We showed that San is critical for sister chromatid cohesion in HeLa cells, suggesting that this mechanism may be conserved in metazoans. Furthermore, although a small fraction of San interacts with the NatA complex, San appears to mediate cohesion independently. San exhibits acetyltransferase activity in vitro, and its activity is required for sister chromatid cohesion in vivo. In the absence of San, Sgo1 localizes correctly throughout the cell cycle. However, cohesin is no longer detected at the mitotic centromeres. Furthermore, San localizes to the cytoplasm in interphase cells; thus, it may not gain access to chromosomes until mitosis. Moreover, in San-depleted cells, further depletion of Plk1 rescues the cohesion along the chromosome arms, but not at the centromeres. Collectively, San may be specifically required for the maintenance of the centromeric cohesion in mitosis. PMID:17502424

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

    SciTech Connect

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

    2016-08-23

    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.

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

    DOE PAGES

    Chen, Ji-Yun; Liu, Liang; Cao, Chun-Ling; ...

    2016-08-23

    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 maymore » 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.« less

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 ...

  20. UMTRA project water sampling and analysis plan, Mexican Hat, Utah

    SciTech Connect

    Not Available

    1994-04-01

    The Mexican Hat, Utah, Uranium Mill Tailings Remedial Action (UMTRA) Project site is a former uranium mill that is undergoing surface remediation in the form of on-site tailings stabilization. Contaminated surface materials from the Monument Valley, Arizona, UMTRA Project site have been transported to the Mexican Hat site and are being consolidated with the Mexican Hat tailings. The scheduled completion of the tailings disposal cell is August 1995. Water is found in two geologic units at the site: the Halgaito Shale Formation and the Honaker Trail Formation. The tailings rest on the Halgaito Shale, and water contained in that unit is a result of milling activities and, to a lesser extent, water released from the tailings from compaction during remedial action construction of the disposal cell. Water in the Halgaito Shale flows through fractures and discharges at seeps along nearby arroyos. Flow from the seeps will diminish as water drains from the unit. Ground water in the lower unit, the Honaker Trail Formation, is protected from contamination by an upward hydraulic gradient. There are no nearby water supply wells because of widespread poor background ground water quality and quantity, and the San Juan River shows no impacts from the site. This water sampling and analysis plan (WSAP) recommends sampling six seeps and one upgradient monitor well compared in the Honaker Trail Formation. Samples will be taken in April 1994 (representative of high group water levels) and September 1994 (representative of low ground water levels). Analyses will be performed on filtered samples for plume indicator parameters.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. Spermidine/spermine-N(1)-acetyltransferase: a key metabolic regulator.

    PubMed

    Pegg, Anthony E

    2008-06-01

    Spermidine/spermine-N(1)-acetyltransferase (SSAT) regulates cellular polyamine content. Its acetylated products are either excreted from the cell or oxidized by acetylpolyamine oxidase. Since polyamines play critical roles in normal and neoplastic growth and in ion channel regulation, SSAT is a key enzyme in these processes. SSAT is very highly regulated. Its content is adjusted in response to alterations in polyamine content to maintain polyamine homeostasis. Certain polyamine analogs can mimic the induction of SSAT and cause a loss of normal polyamines. This may have utility in cancer chemotherapy. SSAT activity is also induced via a variety of other stimuli, including toxins, hormones, cytokines, nonsteroidal anti-inflammatory agents, natural products, and stress pathways, and by ischemia-reperfusion injury. These increases are initiated by alterations in Sat1 gene transcription reinforced by alterations at the other regulatory steps, including protein turnover, mRNA processing, and translation. Transgenic manipulation of SSAT activity has revealed that SSAT activity links polyamine metabolism to lipid and carbohydrate metabolism by means of alterations in the content of acetyl-CoA and ATP. A high level of SSAT stimulates flux through the polyamine biosynthetic pathway, since biosynthetic enzymes are induced in response to the fall in polyamines. This sets up a futile cycle in which ATP is used to generate S-adenosylmethionine for polyamine biosynthesis and acetyl-CoA is consumed in the acetylation reaction. A variety of other effects of increased SSAT activity include death of pancreatic cells, blockage of regenerative tissue growth, behavioral changes, keratosis follicularis spinulosa decalvans, and hair loss. These are very likely due to changes in polyamine and putrescine levels, although increased oxidative stress via the oxidation of acetylated polyamines may also contribute. Recently, it was found that the SSAT protein and/or a related protein, thialysine

  6. HATS9-b and HATS10-b: Two Compact Hot Jupiters in Field 7 of the K2 Mission

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    We report the discovery of two transiting extrasolar planets by the HATSouth survey. HATS-9b orbits an old (10.8 ± 1.5 Gyr) V = 13.3 G dwarf star with a period P≈ 1.9153 days. The host star has a mass of 1.03 {M}⊙ , radius of 1.503 {R}⊙ , and effective temperature 5366 ± 70 K. The planetary companion has a mass of 0.837 {M}{{J}} and radius of 1.065 {R}{{J}}, yielding a mean density of 0.85 {{g}} {{cm}}-3. HATS-10b orbits a V = 13.1 G dwarf star with a period P≈ 3.3128 days. The host star has a mass of 1.1 {M}⊙ , radius of 1.11 {R}⊙ , and effective temperature 5880 ± 120 K. The planetary companion has a mass of 0.53 {M}{{J}} and radius of 0.97 {R}{{J}}, yielding a mean density of 0.7 {{g}} {{cm}}-3. Both planets are compact in comparison with planets receiving similar irradiation from their host stars and lie in the nominal coordinates of Field 7 of K2, but only HATS-9b falls on working silicon. Future characterization of HATS-9b with the exquisite photometric precision of the Kepler telescope may provide measurements of its reflected light signature. The HATSouth network is operated by a collaboration consisting of Princeton University (PU), the Max Planck Institute for Astronomy (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 Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. Based in part on observations made 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. Based on observations obtained with the Apache

  7. The History of SETI at the Hat Creek Radio Observatory

    NASA Astrophysics Data System (ADS)

    Tarter, J.

    2006-12-01

    Since the first SETI search in 1960, observations have encountered an exponentially growing problem with radio frequency interference (RFI) generated by our own communication, entertainment, and military technologies. The signal processing equipment that is used for SETI has gotten much faster and more capable, yet the fraction of the possible search space that has been explored remains very small. More than 100 searches have been reported in the literature. Tarter (2001) has summarized the various search strategies and the SETI Institute maintains an updated search archive at http://www.seti.org/searcharchive. The Allen Telescope Array (ATA) at Hat Creek Radio Observatory will be the first instrument designed with SETI as a goal, and its speed and flexibility will permit a significant exploration of our local region of the Milky Way Galaxy, targeting ˜1 million stars for weak signals, as well as surveying for stronger signals from ˜40 billion distant stars, located in the direction of the galactic center and the surrounding 20 square degrees. Just as Jack Welch has been responsible for many of the innovations in the ATA and the SETI observations it will soon undertake, he has been the key to enabling SETI at the Hat Creek Radio Observatory for the past three decades.

  8. HAT-P-50b, HAT-P-51b, HAT-P-52b, and HAT-P-53b: Three Transiting Hot Jupiters and a Transiting Hot Saturn From the HATNet Survey

    NASA Astrophysics Data System (ADS)

    Hartman, J. D.; Bhatti, W.; Bakos, G. Á.; Bieryla, A.; Kovács, 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.; Kovács, T.; Hansen, T.; Béky, B.; Noyes, R. W.; Lázár, J.; Papp, I.; Sári, P.

    2015-12-01

    We report the discovery and characterization of four transiting exoplanets by the HATNet survey. The planet HAT-P-50b has a mass of 1.35 {M}{{J}} and radius of 1.29 {R}{{J}}, and orbits a bright (V=11.8 mag) M=1.27 {M}⊙ , R=1.70 {R}⊙ star every P=3.1220 days. The planet HAT-P-51b has a mass of 0.31 {M}{{J}} and radius of 1.29 {R}{{J}}, and orbits a V=13.4 mag, M=0.98 {M}⊙ , R=1.04 {R}⊙ star with a period of P=4.2180 days. The planet HAT-P-52b has a mass of 0.82 {M}{{J}} and radius of 1.01 {R}{{J}}, and orbits a V=14.1 mag, M=0.89 {M}⊙ , R=0.89 {R}⊙ star with a period of P=2.7536 days. The planet HAT-P-53b has a mass of 1.48 {M}{{J}} and radius of 1.32 {R}{{J}}, and orbits a V=13.7 mag, M=1.09 {M}⊙ , R=1.21 {R}⊙ star with a period of P=1.9616 days. All four planets are consistent with having circular orbits and have masses and radii measured to better than 10% precision. The low stellar jitter and favorable {R}p/{R}\\star ratio for HAT-P-51 make it a promising target for measuring the Rossiter-McLaughlin effect for a Saturn-mass planet. Based on observations obtained with the Hungarian-made Automated Telescope Network. Based 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 (A245Hr) and NASA (N154Hr, N130Hr). Based on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. Based on observations obtained with the Tillinghast Reflector 1.5 m telescope and the 1.2 m telescope, both operated by the Smithsonian Astrophysical Observatory at the Fred Lawrence Whipple Observatory in AZ. Based on radial velocities obtained with the

  9. 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

  10. In silico identification and characterization of N-Terminal acetyltransferase genes of poplar (Populus trichocarpa).

    PubMed

    Zhu, Hang-Yong; Li, Chun-Ming; Wang, Li-Feng; Bai, Hui; Li, Yan-Ping; Yu, Wen-Xi; Xia, De-An; Liu, Chang-Cai

    2014-01-27

    N-terminal acetyltransferase (Nats) complex is responsible for protein N-terminal acetylation (Nα-acetylation), which is one of the most common covalent modifications of eukaryotic proteins. Although genome-wide investigation and characterization of Nat catalytic subunits (CS) and auxiliary subunits (AS) have been conducted in yeast and humans they remain unexplored in plants. Here we report on the identification of eleven genes encoding eleven putative Nat CS polypeptides, and five genes encoding five putative Nat AS polypeptides in Populus. We document that the expansion of Nat CS genes occurs as duplicated blocks distributed across 10 of the 19 poplar chromosomes, likely only as a result of segmental duplication events. Based on phylogenetic analysis, poplar Nat CS were assigned to six subgroups, which corresponded well to the Nat CS types (CS of Nat A-F), being consistent with previous reports in humans and yeast. In silico analysis of microarray data showed that in the process of normal development of the poplar, their Nat CS and AS genes are commonly expressed at one relatively low level but share distinct tissue-specific expression patterns. This exhaustive survey of Nat genes in poplar provides important information to assist future studies on their functional role in poplar.

  11. Lysine acetyltransferases CBP and p300 as therapeutic targets in cognitive and neurodegenerative disorders.

    PubMed

    Valor, Luis M; Viosca, Jose; Lopez-Atalaya, Jose P; Barco, Angel

    2013-01-01

    Neuropsychiatric pathologies, including neurodegenerative diseases and neurodevelopmental syndromes, are frequently associated with dysregulation of various essential cellular mechanisms, such as transcription, mitochondrial respiration and protein degradation. In these complex scenarios, it is difficult to pinpoint the specific molecular dysfunction that initiated the pathology or that led to the fatal cascade of events that ends with the death of the neuron. Among the possible original factors, epigenetic dysregulation has attracted special attention. This review focuses on two highly related epigenetic factors that are directly involved in a number of neurological disorders, the lysine acetyltransferases CREB-binding protein (CBP) and E1A-associated protein p300 (p300). We first comment on the role of chromatin acetylation and the enzymes that control it, particularly CBP and p300, in neuronal plasticity and cognition. Next, we describe the involvement of these proteins in intellectual disability and in different neurodegenerative diseases. Finally, we discuss the potential of ameliorative strategies targeting CBP/p300 for the treatment of these disorders.

  12. 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.

  13. Moco biosynthesis and the ATAC acetyltransferase engage translation initiation by inhibiting latent PKR activity.

    PubMed

    Suganuma, Tamaki; Swanson, Selene K; Florens, Laurence; Washburn, Michael P; Workman, Jerry L

    2016-02-01

    Molybdenum cofactor (Moco) biosynthesis is linked to c-Jun N-terminal kinase (JNK) signaling in Drosophila through MoaE, a molybdopterin (MPT) synthase subunit that is also a component of the Ada Two A containing (ATAC) acetyltransferase complex. Here, we show that human MPT synthase and ATAC inhibited PKR, a double-stranded RNA-dependent protein kinase, to facilitate translation initiation of iron-responsive mRNA. MPT synthase and ATAC directly interacted with PKR and suppressed latent autophosphorylation of PKR and its downstream phosphorylation of JNK and eukaryotic initiation factor 2α (eIF2α). The suppression of eIF2α phosphorylation via MPT synthase and ATAC prevented sequestration of the guanine nucleotide exchange factor eIF2B, which recycles eIF2-GDP to eIF2-GTP, resulting in the promotion of translation initiation. Indeed, translation of the iron storage protein, ferritin, was reduced in the absence of MPT synthase or ATAC subunits. Thus, MPT synthase and ATAC regulate latent PKR signaling and link transcription and translation initiation.

  14. Early adipogenesis is regulated through USP7-mediated deubiquitination of the histone acetyltransferase TIP60.

    PubMed

    Gao, Yuan; Koppen, Arjen; Rakhshandehroo, Maryam; Tasdelen, Ismayil; van de Graaf, Stan F; van Loosdregt, Jorg; van Beekum, Olivier; Hamers, Nicole; van Leenen, Dik; Berkers, Celia R; Berger, Ruud; Holstege, Frank C P; Coffer, Paul J; Brenkman, Arjan B; Ovaa, Huib; Kalkhoven, Eric

    2013-01-01

    Transcriptional coregulators, including the acetyltransferase Tip60, have a key role in complex cellular processes such as differentiation. Whereas post-translational modifications have emerged as an important mechanism to regulate transcriptional coregulator activity, the identification of the corresponding demodifying enzymes has remained elusive. Here we show that the expression of the Tip60 protein, which is essential for adipocyte differentiation, is regulated through polyubiquitination on multiple residues. USP7, a dominant deubiquitinating enzyme in 3T3-L1 adipocytes and mouse adipose tissue, deubiquitinates Tip60 both in intact cells and in vitro and increases Tip60 protein levels. Furthermore, inhibition of USP7 expression and activity decreases adipogenesis. Transcriptome analysis reveals several cell cycle genes to be co-regulated by both Tip60 and USP7. Knockdown of either factor results in impaired mitotic clonal expansion, an early step in adipogenesis. These results reveal deubiquitination of a transcriptional coregulator to be a key mechanism in the regulation of early adipogenesis.

  15. The histone acetyltransferase MOF is a key regulator of the embryonic stem cell core transcriptional network.

    PubMed

    Li, Xiangzhi; Li, Li; Pandey, Ruchi; Byun, Jung S; Gardner, Kevin; Qin, Zhaohui; Dou, Yali

    2012-08-03

    Pluripotent embryonic stem cells (ESCs) maintain self-renewal and the potential for rapid response to differentiation cues. Both ESC features are subject to epigenetic regulation. Here we show that the histone acetyltransferase Mof plays an essential role in the maintenance of ESC self-renewal and pluripotency. ESCs with Mof deletion lose characteristic morphology, alkaline phosphatase (AP) staining, and differentiation potential. They also have aberrant expression of the core transcription factors Nanog, Oct4, and Sox2. Importantly, the phenotypes of Mof null ESCs can be partially suppressed by Nanog overexpression, supporting the idea that Mof functions as an upstream regulator of Nanog in ESCs. Genome-wide ChIP-sequencing and transcriptome analyses further demonstrate that Mof is an integral component of the ESC core transcriptional network and that Mof primes genes for diverse developmental programs. Mof is also required for Wdr5 recruitment and H3K4 methylation at key regulatory loci, highlighting the complexity and interconnectivity of various chromatin regulators in ESCs.

  16. Recombinant genomes which express chloramphenicol acetyltransferase in mammalian cells

    SciTech Connect

    Gorman, C.M.; Moffat, L.F.; Howard, B.H.

    1982-09-01

    The authors constructed a series of recombinant genomes which directed expression of the enzyme chloramphenicol acetyltransferase (CAT) in mammalian cells. The prototype recombinant in this series, pSV2-cat, consisted of the beta-lactamase gene and origin of replication from pBR322 coupled to a simian virus 40 (SV40) early transcription region into which CAT coding sequences were inserted. Readily measured levels of CAT accumulated within 48 h after the introduction of pSV2-cat DNA into African green monkey kidney CV-1 cells. Because endogenous CAT activity is not present in CV-1 or other mammalian cells, and because rapid, sensitive assays for CAT activity are available, these recombinants provided a uniquely convenient system for monitoring the expression of foreign DNAs in tissue culture cells. To demonstrate the usefulness of this system, we constructed derivatives of pSV2-cat from which part or all of the SV 40 promoter region was removed. Deletion of one copy of the 72-base-pair repeat sequence in the SV40 promoter caused no significant decrease in CAT synthesis in monkey kidney CV-1 cells; however, an additional deletion of 50 base pairs from the second copy of the repeats reduced CAT synthesis to 11% of its level in the wild type. They also constructed a recombinant, pSVO-cat, in which the entire SV40 promoter region was removed and a unique HindIII site was substituted for the insertion of other promoter sequences.

  17. 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

    2015-07-07

    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.

  18. 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%).

  19. The histone acetyltransferase p300 promotes intrinsic axonal regeneration.

    PubMed

    Gaub, Perrine; Joshi, Yashashree; Wuttke, Anja; Naumann, Ulrike; Schnichels, Sven; Heiduschka, Peter; Di Giovanni, Simone

    2011-07-01

    Axonal regeneration and related functional recovery following axonal injury in the adult central nervous system are extremely limited, due to a lack of neuronal intrinsic competence and the presence of extrinsic inhibitory signals. As opposed to what occurs during nervous system development, a weak proregenerative gene expression programme contributes to the limited intrinsic capacity of adult injured central nervous system axons to regenerate. Here we show, in an optic nerve crush model of axonal injury, that adenoviral (cytomegalovirus promoter) overexpression of the acetyltransferase p300, which is regulated during retinal ganglion cell maturation and repressed in the adult, can promote axonal regeneration of the optic nerve beyond 0.5 mm. p300 acetylates histone H3 and the proregenerative transcription factors p53 and CCAAT-enhancer binding proteins in retinal ganglia cells. In addition, it directly occupies and acetylates the promoters of the growth-associated protein-43, coronin 1 b and Sprr1a and drives the gene expression programme of several regeneration-associated genes. On the contrary, overall increase in cellular acetylation using the histone deacetylase inhibitor trichostatin A, enhances retinal ganglion cell survival but not axonal regeneration after optic nerve crush. Therefore, p300 targets both the epigenome and transcription to unlock a post-injury silent gene expression programme that would support axonal regeneration.

  20. 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.

  1. Hermitian hat wavelet design for singularity detection in the Paraguay river-level data analyses

    NASA Astrophysics Data System (ADS)

    Szu, Harold H.; Hsu, Charles C.; Sa, Leonardo D.; Li, Weigang

    1997-04-01

    The direct differentiation of a noisy signal ds/dt is known to be inaccurate. Differentiation can be improved by employing the Dirac (delta) -function introduced into a convolution product denoted by (direct product) and then integrated by parts: ds/dt equals ds/dt (direct product) (delta) equals - s (direct product) d(delta) /dt. The Schwartz Gaussian representation of the delta function is then explicitly used in the differentiation. It turns out that such a convolution approach to the first and the second derivatives produces a pair of mother wavelets the combination of which is the complex generalization of the Mexican hat called a Hermitian hat wavelet. It is shown that the Hermitian filter is a single oscillation wavelet having much lower frequency bandwidth than the Mortlet or Gabor wavelet. As a result of Nyquist theorem, a fewer number of grid points would be needed for the discrete convolution operation. Therefore, the singularity characteristic will not be overly smeared and the noise can be smoothed away. The phase plot of the Hermitian wavelet transform in terms of the time scale and frequency domains reveal a bifurcation discontinuity of a noisy cusp singularity at the precise location of the singularity as well as the scale nature of the underlying dynamics. This phase plot is defined as (theta) (t/a) equals tan-1 [(ds/dt)/(-d2s/dt2] equals tan-1 [((d(delta) (t/a)dt) (direct product) s)/((d2(delta) (t/a)/dt2) (direct product) s)] applied to a real world data of the Paraguay river levels.

  2. 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.

  3. 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…

  4. Not Just Hats Anymore: Binomial Inversion and the Problem of Multiple Coincidences

    ERIC Educational Resources Information Center

    Hathout, Leith

    2007-01-01

    The well-known "hats" problem, in which a number of people enter a restaurant and check their hats, and then receive them back at random, is often used to illustrate the concept of derangements, that is, permutations with no fixed points. In this paper, the problem is extended to multiple items of clothing, and a general solution to the problem of…

  5. 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.

  6. Sulfonamide-Based Inhibitors of Aminoglycoside Acetyltransferase Eis Abolish Resistance to Kanamycin in Mycobacterium tuberculosis

    SciTech Connect

    Garzan, Atefeh; Willby, Melisa J.; Green, Keith D.; Gajadeera, Chathurada S.; Hou, Caixia; Tsodikov, Oleg V.; Posey, James E.; Garneau-Tsodikova, Sylvie

    2016-12-08

    A two-drug combination therapy where one drug targets an offending cell and the other targets a resistance mechanism to the first drug is a time-tested, yet underexploited approach to combat or prevent drug resistance. By high-throughput screening, we identified a sulfonamide scaffold that served as a pharmacophore to generate inhibitors of Mycobacterium tuberculosis acetyltransferase Eis, whose upregulation causes resistance to the aminoglycoside (AG) antibiotic kanamycin A (KAN) in Mycobacterium tuberculosis. Rational systematic derivatization of this scaffold to maximize Eis inhibition and abolish the Eis-mediated KAN resistance of M. tuberculosis yielded several highly potent agents. A crystal structure of Eis in complex with one of the most potent inhibitors revealed that the inhibitor bound Eis in the AG-binding pocket held by a conformationally malleable region of Eis (residues 28–37) bearing key hydrophobic residues. These Eis inhibitors are promising leads for preclinical development of innovative AG combination therapies against resistant TB.

  7. Structures of Wild-Type and Mutant Human Spermidine/Spermine N1-acetyltransferase, a Potential Therapeutic Drug Target

    SciTech Connect

    Bewley,M.; Graziano, V.; Jiang, J.; Matz, E.; Studier, F.; Pegg, A.; Coleman, C.; Flanagan, J.

    2006-01-01

    Spermidine/spermine N{sup 1}-acetyltransferase (SSAT) is a key enzyme in the control of polyamine levels in human cells, as acetylation of spermidine and spermine triggers export or degradation. Increased intracellular polyamine levels accompany several types of cancers as well as other human diseases, and compounds that affect the expression, activity, or stability of SSAT are being explored as potential therapeutic drugs. We have expressed human SSAT from the cloned cDNA in Escherichia coli and have determined high-resolution structures of wild-type and mutant SSAT, as the free dimer and in binary and ternary complexes with CoA, acetyl-CoA (AcCoA), spermine, and the inhibitor N{sup 1},N{sup 11}-bis-(ethyl)-norspermine (BE-3-3-3). These structures show details of binding sites for cofactor, substrates, and inhibitor and provide a framework to understand enzymatic activity, mutations, and the action of potential drugs. Two dimer conformations were observed: a symmetric form with two open surface channels capable of binding substrate or cofactor, and an asymmetric form in which only one of the surface channels appears capable of binding and acetylating polyamines. SSAT was found to self-acetylate lysine-26 in the presence of AcCoA and absence of substrate, a reaction apparently catalyzed by AcCoA bound in the second channel of the asymmetric dimer. These unexpected and intriguing complexities seem likely to have some as yet undefined role in regulating SSAT activity or stability as a part of polyamine homeostasis. Sequence signatures group SSAT with proteins that appear to have thialysine N{sup {var_epsilon}}-acetyltransferase activity.

  8. 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.

  9. 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.

  10. Mapping HI and B at Hat Creek ... and Beyond

    NASA Astrophysics Data System (ADS)

    Heiles, C.

    2006-12-01

    The Hat Creek 85-foot telescope produced the first complete surveys of HI in the Northern sky--superseded only recently--and initiated measurements of the interstellar magnetic field using Zeeman splitting of the HI line in emission. These endeavors required state-of-the-art electronics and spectrometers. Here I review the role of the Berkeley Radio Astronomy Laboratory and its 85-foot telescope in their initiative roles for these three areas of science and technology and trace their evolution to the present. The present emphasizes the great single dishes of our times, the Green Bank Telescope (GBT) for Zeeman splitting and Arecibo for HI mapping; Fourier-transform spectrometers using FPGA technology; and sustaining the future with the synergy of research and education.

  11. 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.

  12. 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.

  13. 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.

  14. Secondary Eclipses of HAT-P-13b

    NASA Astrophysics Data System (ADS)

    Hardy, Ryan A.; Harrington, Joseph; Hardin, Matthew R.; Madhusudhan, Nikku; Loredo, Thomas J.; Challener, Ryan C.; Foster, Andrew S. D.; Cubillos, Patricio E.; Blecic, Jasmina

    2017-02-01

    We present Spitzer secondary-eclipse observations of the hot Jupiter HAT-P-13 b in the 3.6 and 4.5 μm bands. HAT-P-13 b inhabits a two-planet system with a configuration that enables constraints on the planet’s second Love number, {k}2, from precise eccentricity measurements, which in turn constrains models of the planet’s interior structure. We exploit the direct measurements of e\\cos ω from our secondary-eclipse data and combine them with previously published radial velocity data to generate a refined model of the planet’s orbit and thus an improved estimate on the possible interval for {k}2. We report eclipse phases of 0.49154+/- 0.00080 and 0.49711+/- 0.00083 and corresponding e\\cos ω estimates of -0.0136+/- 0.0013 and -0.0048+/- 0.0013. Under the assumptions of previous work, our estimate of {k}2 of 0.81 ± 0.10 is consistent with the lower extremes of possible core masses found by previous models, including models with no solid core. This anomalous result challenges both interior models and the dynamical assumptions that enable them, including the essential assumption of apsidal alignment. We also report eclipse depths of 0.081% ± 0.008% in the 3.6 μm channel and 0.088% ± 0.028% in the 4.5 μm channel. These photometric results are non-uniquely consistent with solar-abundance composition without any thermal inversion.

  15. 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.

  16. 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...

  17. 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...

  18. 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

  19. 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

  20. Radiant exposure level comparison between Gaussian and top hat beams in various scanning patterns.

    PubMed

    U-Thainual, Paweena; Yang, Yi; Le, Hanh N D; Kim, Do-Hyun

    2014-12-20

    The radiant exposure of optical irradiation beams with different scanning parameters has been theoretically studied. We analyzed the difference in radiant exposure introduced by Gaussian and top hat beams. Various parameters such as scanning pattern, aperture position, beam size and scan spacing were also introduced in this study. We found that Gaussian beams introduce higher calculated radiant exposure to the aperture than top hat beams for certain beam size to aperture size ratios. However, as the scan spacing decreases, the radiant exposure difference calculated from Gaussian and top hat beams diminishes.

  1. HnRNPA2 is a novel histone acetyltransferase that mediates mitochondrial stress-induced nuclear gene expression

    PubMed Central

    Guha, Manti; Srinivasan, Satish; Guja, Kip; Mejia, Edison; Garcia-Diaz, Miguel; Johnson, F Brad; Ruthel, Gordon; Kaufman, Brett A; Rappaport, Eric F; Glineburg, M Rebecca; Fang, Ji-Kang; Szanto, Andres Klein; Nakagawa, Hiroshi; Basha, Jeelan; Kundu, Tapas; Avadhani, Narayan G

    2016-01-01

    Reduced mitochondrial DNA copy number, mitochondrial DNA mutations or disruption of electron transfer chain complexes induce mitochondria-to-nucleus retrograde signaling, which induces global change in nuclear gene expression ultimately contributing to various human pathologies including cancer. Recent studies suggest that these mitochondrial changes cause transcriptional reprogramming of nuclear genes although the mechanism of this cross talk remains unclear. Here, we provide evidence that mitochondria-to-nucleus retrograde signaling regulates chromatin acetylation and alters nuclear gene expression through the heterogeneous ribonucleoprotein A2 (hnRNAP2). These processes are reversed when mitochondrial DNA content is restored to near normal cell levels. We show that the mitochondrial stress-induced transcription coactivator hnRNAP2 acetylates Lys 8 of H4 through an intrinsic histone lysine acetyltransferase (KAT) activity with Arg 48 and Arg 50 of hnRNAP2 being essential for acetyl-CoA binding and acetyltransferase activity. H4K8 acetylation at the mitochondrial stress-responsive promoters by hnRNAP2 is essential for transcriptional activation. We found that the previously described mitochondria-to-nucleus retrograde signaling-mediated transformation of C2C12 cells caused an increased expression of genes involved in various oncogenic processes, which is retarded in hnRNAP2 silenced or hnRNAP2 KAT mutant cells. Taken together, these data show that altered gene expression by mitochondria-to-nucleus retrograde signaling involves a novel hnRNAP2-dependent epigenetic mechanism that may have a role in cancer and other pathologies. PMID:27990297

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

    PubMed

    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.

  3. The use of choline acetyltransferase for measuring the synthesis of acetyl-coenzyme A and its release from brain mitochondria.

    PubMed

    Tucek, S

    1967-09-01

    1. A method for measuring small amounts of acetyl-CoA synthesized in subcellular fractions of the brain from pyruvate and released from particles into the incubation medium has been developed by using placental choline acetyltransferase and choline in the incubation medium to transform acetyl-CoA into acetylcholine. Acetylcholine is measured by biological assay. Optimum conditions of incubation are described. 2. With fresh mitochondria, a decrease of acetyl-CoA output into the medium is observed in the presence of ATP or ADP, and an increase in the presence of calcium chloride or 2,4-dinitrophenol. Fluorocitrate and malonate have little or no effect. 3. After the mitochondria had been treated with ether, the release of acetyl-CoA into the medium is much larger; presumably, nearly all acetyl-CoA synthesized is then released and transformed into acetylcholine under the conditions used. The release of acetyl-CoA is diminished in the presence of Krebs-cycle intermediates and ADP. 4. Of all subcellular fractions, the highest acetyl-CoA production from pyruvate is found in the crude mitochondria; rates up to 51 mumoles of acetyl-CoA/g. of original tissue/hr. are observed in ether-treated samples. 5. The activities of acetyl-CoA synthetase and ATP citrate lyase found in homogenates and nerve-ending fractions of brain tissue are considerably lower than those of pyruvate oxidase complex and choline acetyltransferase. 6. The bearing of some of the findings on the question of the source of acetyl radicals for the synthesis of acetylcholine in vivo is discussed.

  4. N-acetyltransferase 2, exposure to aromatic and heterocyclic amines, and receptor-defined breast cancer.

    PubMed

    Rabstein, Sylvia; Brüning, Thomas; Harth, Volker; Fischer, Hans-Peter; Haas, Susanne; Weiss, Tobias; Spickenheuer, Anne; Pierl, Christiane; Justenhoven, Christina; Illig, Thomas; Vollmert, Caren; Baisch, Christian; Ko, Yon-Dschun; Hamann, Ute; Brauch, Hiltrud; Pesch, Beate

    2010-03-01

    The role of N-acetyltransferase 2 (NAT2) polymorphism in breast cancer is still unclear. We explored the associations between potential sources of exposure to aromatic and heterocyclic amines (AHA), acetylation status and receptor-defined breast cancer in 1020 incident cases and 1047 population controls of the German GENICA study. Acetylation status was assessed as slow or fast. Therefore, NAT2 haplotypes were estimated using genotype information from six NAT2 polymorphisms. Most probable haplotypes served as alleles for the deduction of NAT2 acetylation status. The risks of developing estrogen receptor alpha (ER) and progesterone receptor (PR)-positive or negative tumors were estimated for tobacco smoking, consumption of red meat, grilled food, coffee, and tea, as well as expert-rated occupational exposure to AHA with logistic regression conditional on age and adjusted for potential confounders. Joint effects of these factors and NAT2 acetylation status were investigated. Frequent consumption of grilled food and coffee showed higher risks in slow acetylators for receptor-negative tumors [grilled food: ER-: odds ratio (OR) 2.57, 95% confidence interval (CI) 1.07-6.14 for regular vs. rare; coffee: ER-: OR 2.55, 95% CI 1.22-5.33 for >or=4 vs. 0 cups/day]. We observed slightly higher risks for never smokers that are fast acetylators for receptor-positive tumors compared with slow acetylators (ER-: OR 1.32, 95% CI 1.00-1.73). Our results support differing risk patterns for receptor-defined breast cancer. However, the modifying role of NAT2 for receptor-defined breast cancer is difficult to interpret in the light of complex mixtures of exposure to AHA.

  5. 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.

  6. Heroin-assisted treatment (HAT) a decade later: a brief update on science and politics.

    PubMed

    Fischer, Benedikt; Oviedo-Joekes, Eugenia; Blanken, Peter; Haasen, Christian; Rehm, Jürgen; Schechter, Martin T; Strang, John; van den Brink, Wim

    2007-07-01

    Since the initial Swiss heroin-assisted treatment (HAT) study conducted in the mid-1990s, several other jurisdictions in Europe and North America have implemented HAT trials. All of these studies embrace the same goal-investigating the utility of medical heroin prescribing for problematic opioid users-yet are distinct in various key details. This paper briefly reviews (initiated or completed) studies and their main parameters, including primary research objectives, design, target populations, outcome measures, current status and-where available-key results. We conclude this overview with some final observations on a decade of intensive HAT research in the jurisdictions examined, including the suggestion that there is a mounting onus on the realm of politics to translate the-largely positive-data from completed HAT science into corresponding policy and programming in order to expand effective treatment options for the high-risk population of illicit opioid users.

  7. Application of Human-Autonomy Teaming (HAT) Patterns to Reduced 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

    As part of the Air Force - NASA Bi-Annual Research Council Meeting, slides will be presented on recent Reduced Crew Operations (RCO) work. 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. A methodology for identifying HAT patterns to an advanced cockpit project is discussed.

  8. 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.

  9. FLOYDS Classification of DLT17h/AT 2017ahn as a Type II Supernova

    NASA Astrophysics Data System (ADS)

    Hosseinzadeh, G.; Valenti, S.; Arcavi, I.; Howell, D. A.; McCully, C.; Sand, D.; Tartaglia, L.

    2017-02-01

    We obtained a spectrum of DLT17h/AT 2017ahn (ATel #10058) on 2017 February 8.7 UT with the robotic FLOYDS instrument mounted on the Las Cumbres Observatory 2-meter telescope in Siding Spring, Australia.

  10. Biomechanical study of a hat type cervical intervertebral fusion cage.

    PubMed

    Gu, Yu-Tong; Jia, Lian-Shun; Chen, Tong-Yi

    2007-02-01

    The purpose of this study was to evaluate the biomechanical effect of a hat type cervical intervertebral fusion cage (HCIFC). In this in vitro biomechanical study, 48 goat cervical spines (C2-5) were tested in flexion, extension, axial rotation, and lateral bending with a nondestructive stiffness method using a nonconstrained testing apparatus, and three-dimensional displacement was measured. Autologous iliac bone and cervical spine intervertebral fusion cage were implanted according to manufacturers' information after complete discectomy (C3-4). Eight spines in each of the following groups were tested: intact, autologous iliac bone graft, Harms cage, SynCage C, carbon cage, and HCIFC. The mean apparent stiffness values were calculated from the corresponding load-displacement curves. Additionally, cage volume and volume-related stiffness were determined. The stiffness of the SynCage C was statistically greatest in all directions. After implantation of the HCIFC, flexion stiffness increased compared with that of the intact motion segment. There was no significant difference in stiffness between the HCIFC and carbon cage. The stiffness of the HCIFC was statistically higher than that of the Harms cage in axial rotation and significantly lower in flexion, extension, and lateral bending. Volume-related stiffness of all cages was higher than that of iliac bone graft. The Harms cage was highest in volume-related stiffness in all directions. The HCIFC can provide enough primary stability for cervical intervertebral fusion.

  11. HAT-P-42b and HAT-P-43b. Two inflated transiting hot Jupiters from the HATNet Survey

    NASA Astrophysics Data System (ADS)

    Boisse, I.; Hartman, J. D.; Bakos, G. Á.; Penev, K.; Csubry, Z.; Béky, B.; Latham, D. W.; Bieryla, A.; Torres, G.; Kovács, G.; Buchhave, L. A.; Hansen, T.; Everett, M.; Esquerdo, G. A.; Szklenár, T.; Falco, E.; Shporer, A.; Fulton, B. J.; Noyes, R. W.; Stefanik, R. P.; Lázár, J.; Papp, I.; Sári, P.

    2013-10-01

    Aims: We announce the discovery of two new transiting planets, and provide their accurate initial characterization. Methods: First identified from the HATNet wide-field photometric survey, these candidate transiting planets were then followed-up with a variety of photometric observations. Determining the planetary nature of the objects and characterizing the parameters of the systems were mainly done with the SOPHIE spectrograph at the 1.93 m telescope at OHP and the TRES spectrograph at the 1.5 m telescope at FLWO. Results: HAT-P-42b and HAT-P-43b are typical hot Jupiters on circular orbits around early-G/late-F main sequence host stars, with periods of 4.641878 ± 0.000032 and 3.332687 ± 0.000015 days, masses of 1.044 ± 0.083 and 0.662 ± 0.060 MJ, and radii of 1.280 ± 0.153 and 1.28+0.062-0.033RJ, respectively. These discoveries increase the sample of planets with measured mean densities, which are needed to constrain theories of planetary interiors and atmospheres. Moreover, their hosts are relatively bright (V < 13.5), which facilitates further follow-up studies. Full Table 2 is only available in electronic form 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/A86The photometric/spectroscopic data presented in this paper are based in part on observations carried out by the Hungarian-made Automated Telescope Network, using telescopes operated at the Fred Lawrence Whipple Observatory (FLWO) of the Smithsonian Astrophysical Observatory (SAO), and at the Submillimeter Array (SMA) of SAO, by the Tillinghast Reflector 1.5 m telescope and the 1.2 m telescope, both operated by SAO at FLWO, by the SOPHIE spectrograph mounted on the 1.93 m telescope at Observatoire de Haute Provence, France (runs DDT-Dec. 2011), by the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los

  12. Using a Home Automated Telemanagement (HAT) system: experiences and perceptions of patients with inflammatory bowel disease.

    PubMed

    Castro, Heather K; Cross, Raymond K; Finkelstein, Joseph

    2006-01-01

    The aim of this study was to evaluate the experiences and perceptions of patients with inflammatory bowel disease (IBD) who participated in an interactive, patient-centered computerized disease management program using the Home Automated Telemanagement (HAT) system. We conducted and analyzed qualitative exit interviews with 23 participants who used the system for six months. The HAT system was well accepted, increased patients' awareness about the disease and facilitated greater control of their IBD symptoms.

  13. 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...

  14. Phylogenetic and biological 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 eukaryotic organisms. The role of NATs in fungal biology has only recently been investigated. The NAT1 (FDB2) gene of Fusarium verticillioides was the first NAT cloned and character...

  15. AAC(3)-XI, a New Aminoglycoside 3-N-Acetyltransferase from Corynebacterium striatum

    PubMed Central

    Galimand, Marc; Fishovitz, Jennifer; Lambert, Thierry; Barbe, Valérie; Zajicek, Jaroslav

    2015-01-01

    Corynebacterium striatum BM4687 was resistant to gentamicin and tobramycin but susceptible to kanamycin A and amikacin, a phenotype distinct among Gram-positive bacteria. Analysis of the entire genome of this strain did not detect any genes for known aminoglycoside resistance enzymes. Yet, annotation of the coding sequences identified 12 putative acetyltransferases or GCN5-related N-acetyltransferases. A total of 11 of these coding sequences were also present in the genomes of other Corynebacterium spp. The 12th coding sequence had 55 to 60% amino acid identity with acetyltransferases in Actinomycetales. The gene was cloned in Escherichia coli, where it conferred resistance to aminoglycosides by acetylation. The protein was purified to homogeneity, and its steady-state kinetic parameters were determined for dibekacin and kanamycin B. The product of the turnover of dibekacin was purified, and its structure was elucidated by high-field nuclear magnetic resonance (NMR), indicating transfer of the acetyl group to the amine at the C-3 position. Due to the unique profile of the reaction, it was designated aminoglycoside 3-N-acetyltransferase type XI. PMID:26149994

  16. Histone acetyltransferase activity of MOF is required for adult but not early fetal hematopoiesis in mice.

    PubMed

    Valerio, Daria G; Xu, Haiming; Eisold, Meghan E; Woolthuis, Carolien M; Pandita, Tej K; Armstrong, Scott A

    2017-01-05

    K(lysine) acetyltransferase 8 (KAT8, also known as MOF) mediates the acetylation of histone H4 at lysine 16 (H4K16ac) and is crucial for murine embryogenesis. Lysine acetyltransferases have been shown to regulate various stages of normal hematopoiesis. However, the function of MOF in hematopoietic stem cell (HSC) development has not yet been elucidated. We set out to study the role of MOF in general hematopoiesis by using a Vav1-cre-induced conditional murine Mof knockout system and found that MOF is critical for hematopoietic cell maintenance and HSC engraftment capacity in adult hematopoiesis. Rescue experiments with a MOF histone acetyltransferase domain mutant illustrated the requirement for MOF acetyltransferase activity in the clonogenic capacity of HSCs and progenitors. In stark contrast, fetal steady-state hematopoiesis at embryonic day (E) 14.5 was not affected by homozygous Mof deletion despite dramatic loss of global H4K16ac. Hematopoietic defects start manifesting in late gestation at E17.5. The discovery that MOF and its H4K16ac activity are required for adult but not early and midgestational hematopoiesis supports the notion that multiple chromatin regulators may be crucial for hematopoiesis at varying stages of development. MOF is therefore a developmental-stage-specific chromatin regulator found to be essential for adult but not early fetal hematopoiesis.

  17. 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...

  18. HAT-P-1: A Direct Glimpse into the Atmosphere of a Hot Jupiter

    NASA Astrophysics Data System (ADS)

    Holman, Matthew

    2009-07-01

    The HATNet project has discovered a transiting planet that is an extremely valuable target for reflected light observations {Bakos et al. 2006}. HAT-P-1b, with mass M_p=0.53 +/- 0.04 M_Jup, and radius R_p=1.20 +/- 0.05 R_Jup {Winn et al. 2007}, has a density comparable to that of HD 209458b. However, HAT-P-1b's P=4.46536 day orbital period is longer than that of HD 209458b. It is expected that the cloud composition and particulate size distribution of HAT-P-1b will differ from that of HD 209458b, due to the larger semimajor axis and lower effective temperature of HAT-P-1b. The resulting geometric albedo for HAT-P-1b should be larger than that of HD 209458b. Furthermore, HAT-P-1 orbits one component of a wide binary {ADS 16402A and ADS 16402B are G0V stars with 11.2" at 1.39 pc}, making this an ideal target for ultra-precise differential photometry. Therefore, we propose ACS/HRC slitless grism photometry near times of its secondary eclipse to make the first detection of reflected light from an extrasolar planet.Note: this program was awarded DD time in Cycle 15 but the observations were not executed before the ACS failed.Holman and Bakos are co-PIs on this proposal.

  19. HAT-P-18b and HAT-P-19b: Two Low-density Saturn-mass Planets Transiting Metal-rich K Stars

    NASA Astrophysics Data System (ADS)

    Hartman, J. D.; Bakos, G. Á.; Sato, B.; Torres, G.; Noyes, R. W.; Latham, D. W.; Kovács, G.; Fischer, D. A.; Howard, A. W.; Johnson, J. A.; Marcy, G. W.; Buchhave, L. A.; Füresz, G.; Perumpilly, G.; Béky, B.; Stefanik, R. P.; Sasselov, D. D.; Esquerdo, G. A.; Everett, M.; Csubry, Z.; Lázár, J.; Papp, I.; Sári, P.

    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 Tc = 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 sun, radius of 0.75 ± 0.04 R 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 J and radius of 0.995 ± 0.052 R J, yielding a mean density of 0.25 ± 0.04 g cm-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 Tc = 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 sun, radius of 0.82 ± 0.05 R 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 J and radius of 1.132 ± 0.072 R J, yielding a mean density of 0.25 ± 0.04 g cm-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. 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 (A146Hr, A201Hr

  20. Nuclear Arc Interacts with the Histone Acetyltransferase Tip60 to Modify H4K12 Acetylation1,2,3

    PubMed Central

    Wee, Caroline L.; Teo, Shaun; Oey, Nicodemus E.; Wright, Graham D.; VanDongen, Hendrika M.A.

    2014-01-01

    Abstract Arc is an immediate-early gene whose genetic ablation selectively abrogates long-term memory, indicating a critical role in memory consolidation. Although Arc protein is found at synapses, it also localizes to the neuronal nucleus, where its function is less understood. Nuclear Arc forms a complex with the β-spectrin isoform βSpIVΣ5 and associates with PML bodies, sites of epigenetic regulation of gene expression. We report here a novel interaction between Arc and Tip60, a histone-acetyltransferase and subunit of a chromatin-remodelling complex, using biochemistry and super-resolution microscopy in primary rat hippocampal neurons. Arc and βSpIVΣ5 are recruited to nuclear Tip60 speckles, and the three proteins form a tight complex that localizes to nuclear perichromatin regions, sites of transcriptional activity. Neuronal activity-induced expression of Arc (1) increases endogenous nuclear Tip60 puncta, (2) recruits Tip60 to PML bodies, and (3) increases histone acetylation of Tip60 substrate H4K12, a learning-induced chromatin modification. These mechanisms point to an epigenetic role for Arc in regulating memory consolidation. PMID:26464963

  1. The Transmembrane Serine Protease HAT-like 4 Is Important for Epidermal Barrier Function to Prevent Body Fluid Loss

    PubMed Central

    Zhang, Zhiwei; Hu, Yae; Yan, Ruhong; Dong, Liang; Jiang, Yizhi; Zhou, Zhichao; Liu, Meng; Zhou, Tiantian; Dong, Ningzheng; Wu, Qingyu

    2017-01-01

    Membrane-bound proteases are essential for epidermal integrity. Human airway trypsin-like protease 4 (HAT-L4) is a type II transmembrane serine protease. Currently, its biochemical property, cellular distribution and physiological function remain unknown. Here we examined HAT-L4 expression and function in vitro and in vivo. In Western analysis, HAT-L4 expressed in transfected CHO cells appeared as a 48-kDa protein. Flow cytometry confirmed HAT-L4 expression on the cell surface with the expected membrane topology. RT-PCR and immunostaining experiments indicated that HAT-L4 was expressed in epithelial cells and exocrine glands in tissues including skin, esophagus, trachea, tongue, eye, bladder, testis and uterus. In the skin, HAT-L4 expression was abundant in keratinocytes and sebaceous glands. We generated HAT-L4 knockout mice by disrupting the Tmprss11f gene encoding HAT-L4. HAT-L4 knockout mice were viable and fertile. No defects were found in HAT-L4 knockout mice in hair growth, wound healing, water repulsion and body temperature regulation. Compared with wild-type controls, HAT-L4-deficient newborn mice had greater body fluid loss and higher mortality in a trans-epidermal body fluid loss test. In metabolic studies, HAT-L4-deficient adult mice drank water more frequently than wild-type controls did. These results indicate that HAT-L4 is important in epidermal barrier function to prevent body fluid loss. PMID:28338078

  2. Expression, purification and characterization of recombinant human choline acetyltransferase: phosphorylation of the enzyme regulates catalytic activity.

    PubMed Central

    Dobransky, T; Davis, W L; Xiao, G H; Rylett, R J

    2000-01-01

    Choline acetyltransferase synthesizes acetylcholine in cholinergic neurons and, in humans, may be produced in 82- and 69-kDa forms. In this study, recombinant choline acetyltransferase from baculovirus and bacterial expression systems was used to identify protein isoforms by two-dimensional SDS/PAGE and as substrate for protein kinases. Whereas hexa-histidine-tagged 82- and 69-kDa enzymes did not resolve as individual isoforms on two-dimensional gels, separation of wild-type choline acetyltransferase expressed in insect cells revealed at least nine isoforms for the 69-kDa enzyme and at least six isoforms for the 82-kDa enzyme. Non-phosphorylated wild-type choline acetyltransferase expressed in Escherichia coli yielded six (69 kDa) and four isoforms (82 kDa) respectively. Immunofluorescent labelling of insect cells expressing enzyme showed differential subcellular localization with the 69-kDa enzyme localized adjacent to plasma membrane and the 82-kDa enzyme being cytoplasmic at 24 h. By 64 h, the 69-kDa form was in cytoplasm and the 82-kDa form was only present in nucleus. Studies in vitro showed that recombinant 69-kDa enzyme was a substrate for protein kinase C (PKC), casein kinase II (CK2) and alpha-calcium/calmodulin-dependent protein kinase II (alpha-CaM kinase), but not for cAMP-dependent protein kinase (PKA); phosphorylation by PKC and CK2 enhanced enzyme activity. The 82-kDa enzyme was a substrate for PKC and CK2 but not for PKA or alpha-CaM kinase, with only PKC yielding increased enzyme activity. Dephosphorylation of both forms of enzyme by alkaline phosphatase decreased enzymic activity. These studies are of functional significance as they report for the first time that phosphorylation enhances choline acetyltransferase catalytic activity. PMID:10861222

  3. Acetyltransferase p300 collaborates with chromodomain helicase DNA-binding protein 4 (CHD4) to facilitate DNA double-strand break repair.

    PubMed

    Qi, Wenjing; Chen, Hongyu; Xiao, Ting; Wang, Ruoxi; Li, Ting; Han, Liping; Zeng, Xianlu

    2016-03-01

    Chromatin remodelling is critical for repairing DNA damage and maintaining genomic integrity. Previous studies have reported that histone acetyltransferase p300 and ATP-dependent chromatin remodeler chromodomain helicase DNA-binding protein 4 (CHD4) functions, respectively, in DNA double-strand breaks (DSBs) repair. But the physiological significance of their interaction remains elusive. Here, we showed that p300 and CHD4 were both recruited to the sites of DSBs. Their ablation led to impaired DSBs repair and sensitised cells to laser and the anti-cancer drug, etoposide. Using DR-GFP and EJ5-GFP reporter systems, we found that knockdown of p300 or CHD4 impaired the homologous recombination (HR) repair but no the non-homologous end joining (NHEJ) repair. Furthermore, p300 or CHD4 knockdown respectively suppressed the recruitment of replication protein A (RPA), a key protein for HR, to the DSB sites. In addition, immunofluorescence results showed that knockdown of p300 reduced the recruitment of CHD4 at DSB sites. In turn, CHD4 knockdown also decreased p300 assembly. Moreover, immunoprecipitation and purified protein pull down assay revealed that p300 physically interacted with CHD4 at DNA damage sites, and this interaction was dependent on the chromodomain and ATPase/helicase domain of CHD4 and the CH2, Bd and HAT domains of p300. These results indicate that p300 and CHD4 could function cooperatively at DSB sites and provide a new insight into the detailed crosstalk among the chromatin remodelling proteins.

  4. 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.

  5. Complexity.

    PubMed

    Gómez-Hernández, J Jaime

    2006-01-01

    It is difficult to define complexity in modeling. Complexity is often associated with uncertainty since modeling uncertainty is an intrinsically difficult task. However, modeling uncertainty does not require, necessarily, complex models, in the sense of a model requiring an unmanageable number of degrees of freedom to characterize the aquifer. The relationship between complexity, uncertainty, heterogeneity, and stochastic modeling is not simple. Aquifer models should be able to quantify the uncertainty of their predictions, which can be done using stochastic models that produce heterogeneous realizations of aquifer parameters. This is the type of complexity addressed in this article.

  6. 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.

  7. The RSC Complex Exploits Histone Acetylation to Abrogate the Nucleosomal Barrier to RNA Polymerase II Elongation

    PubMed Central

    Carey, Michael; Li, Bing; Workman, Jerry L.

    2007-01-01

    Summary The coordinated action of histone acetyltransferases (HATs) and ATP-dependent chromatin remodeling enzymes in promoter-dependent transcription initiation represents a paradigm for how epigenetic information regulates gene expression. However, little is known about how such enzymes function during transcription elongation. Here we investigated the role of RSC, a bromodomain-containing ATPase, in nucleosome transcription in vitro. Purified S. cerevisiae RNA polymerase II (pol II) arrests at two primary locations on a positioned mononucleosome. RSC stimulates passage of pol II through these sites. The function of RSC in elongation requires the energy of ATP hydrolysis. Moreover, the SAGA and NuA4 HATs strongly stimulated RSC’s effect on elongation. The stimulation correlates closely with Acetyl-CoA-dependent recruitment of RSC to nucleosomes. Thus, RSC can recognize acetylated nucleosomes and facilitate passage of pol II through them. These data support the view that histone modifications regulate accessibility of the coding region to pol II. PMID:17081996

  8. Disruption of the histone acetyltransferase MYST4 leads to a Noonan syndrome–like phenotype and hyperactivated MAPK signaling in humans and mice

    PubMed Central

    Kraft, Michael; Cirstea, Ion Cristian; Voss, Anne Kathrin; Thomas, Tim; Goehring, Ina; Sheikh, Bilal N.; Gordon, Lavinia; Scott, Hamish; Smyth, Gordon K.; Ahmadian, Mohammad Reza; Trautmann, Udo; Zenker, Martin; Tartaglia, Marco; Ekici, Arif; Reis, André; Dörr, Helmuth-Guenther; Rauch, Anita; Thiel, Christian Thomas

    2011-01-01

    Epigenetic regulation of gene expression, through covalent modification of histones, is a key process controlling growth and development. Accordingly, the transcription factors regulating these processes are important targets of genetic diseases. However, surprisingly little is known about the relationship between aberrant epigenetic states, the cellular process affected, and their phenotypic consequences. By chromosomal breakpoint mapping in a patient with a Noonan syndrome–like phenotype that encompassed short stature, blepharoptosis, and attention deficit hyperactivity disorder, we identified haploinsufficiency of the histone acetyltransferase gene MYST histone acetyltransferase (monocytic leukemia) 4 (MYST4), as the underlying cause of the phenotype. Using acetylation, whole genome expression, and ChIP studies in cells from the patient, cell lines in which MYST4 expression was knocked down using siRNA, and the Myst4 querkopf mouse, we found that H3 acetylation is important for neural, craniofacial, and skeletal morphogenesis, mainly through its ability to specifically regulating the MAPK signaling pathway. This finding further elucidates the complex role of histone modifications in mammalian development and adds what we believe to be a new mechanism to the pathogenic phenotypes resulting from misregulation of the RAS signaling pathway. PMID:21804188

  9. 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

  10. 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.

  11. 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

  12. 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.

  13. Association between polymorphisms at N-acetyltransferase 1 (NAT1) & risk of oral leukoplakia & cancer

    PubMed Central

    Majumder, Mousumi; Ghosh, Saurabh; Roy, Bidyut

    2012-01-01

    Background & objectives: N-acetyltransferases 1 and 2 (NAT1 and NAT2) are important enzymes for metabolism of tobacco carcinogens. Due to polymorphisms, improper activities of these enzymes might lead to the formation of DNA adducts that may modulate risk of tobacco related oral precancer and cancer. Previously, it was shown that NAT2 polymorphisms did not modulate the risk of oral precancer and cancer. We undertook this study to check whether polymorphisms at NAT1 can modulate the risk of oral leukoplakia and cancer either alone or in combination with NAT2. Methods: Genotypes at four SNPs on NAT1 were determined by TaqMan method in 389 controls, 224 leukoplakia and 310 cancer patients. Genotype data were analyzed to know haplotypes and acetylation status of individuals and, then to estimate the risk of diseases. Using our previously published NAT2 data, combination of NAT1 and NAT2 acetylation genotypes of patients and controls were also analyzed to estimate the risk of diseases. Results: Analysis of NAT1 genotype data revealed that 1088T and 1095C alleles exist in strong linkage disequilibrium (r2=0.97, P<0.0001) and SNPs are in Hardy-Weinberg Equilibrium (P=0.1). Wild type or normal acetylating and variant or rapid acetylating alleles were two major alleles (frequencies 0.62 and 0.36, respectively) present in the control population. NAT1 rapid acetylation could not modulate the risk of leukoplakia and cancer (OR=0.9, 95% CI: 0.6-1.3; OR=1.0, 95% CI: 0.7-1.4, respectively). Analysis of combined NAT1 and NAT2 acetylating data also showed no significant enhancement of the risk of diseases. Interpretation & conclusions: NAT1 rapid acetylation alone as well as combination of NAT1 rapid-NAT2 slow acetylation did not modulate the risk of oral precancer and cancer in our patient population. So, NAT1/NAT2 metabolized carcinogen products may not be involved in tobacco related oral precancer and cancer. It may be interpreted that large sample size as well as combination of

  14. Resistance to apramycin in two enterobacterial clinical isolates: detection of a 3-N-acetyltransferase IV.

    PubMed

    Gómez-Lus, R; Rivera, M J; Gómez-Lus, M L; Gil, J; Gómez-Lus, S; Castillo, J; Goñi, P; Madero, P; Rubio, M C

    1990-08-01

    Considering the possible role of farm animals in the contamination of human consumers by plasmid-mediated apramycin-resistant enterobacteria strains, this type of resistance should be tested more systematically in human isolates. Very recently we isolated in Zaragoza one apramycin-resistant Escheria coli strain obtained from the blood of a hospitalized patient; this clinical isolate produced a plasmid-mediated 3-N-aminoglycoside acetyltransferase IV. We describe also the isolation in Madrid of one multiresistant Klebsiella pneumoniae clinical strain. This isolate harbored a single plasmid and carried determinants for apramycin, gentamicin, tobramycin, hygromycin B, streptomycin, and ampicillin, which could be transferred en bloc to E. coli K-12 J62. Extracts from donor and transconjugant strains carrying pUZ6776 plasmid produce acetyltransferase activity AAC(3)-IV and double phosphotransferase activity (HPH and APH(3'')).

  15. Crystallization of ornithine acetyltransferase from yeast by counter-diffusion and preliminary X-ray study

    SciTech Connect

    Maes, Dominique Crabeel, Marjolaine; Van de Weerdt, Cécile; Martial, Joseph; Peeters, Eveline; Charlier, Daniël; Decanniere, Klaas; Vanhee, Celine; Wyns, Lode; Zegers, Ingrid

    2006-12-01

    A study on the crystallization of ornithine acetyltransferase from yeast, catalysing the fifth step in microbial arginine synthesis, is presented. The use of the counter-diffusion technique removes the disorder present in one dimension in crystals grown by either batch or hanging-drop techniques. A study is presented on the crystallization of ornithine acetyltransferase from yeast, which catalyzes the fifth step in microbial arginine synthesis. The use of the counter-diffusion technique removes the disorder present in one dimension in crystals grown by either the batch or hanging-drop techniques. This makes the difference between useless crystals and crystals that allow successful determination of the structure of the protein. The crystals belong to space group P4, with unit-cell parameters a = b = 66.98, c = 427.09 Å, and a data set was collected to 2.76 Å.

  16. 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.

  17. The histone acetyltransferase MOF overexpression blunts cardiac hypertrophy by targeting ROS in mice.

    PubMed

    Qiao, Weiwei; Zhang, Weili; Gai, Yusheng; Zhao, Lan; Fan, Juexin

    2014-06-13

    Imbalance between histone acetylation/deacetylation critically participates in the expression of hypertrophic fetal genes and development of cardiac hypertrophy. While histone deacetylases play dual roles in hypertrophy, current evidence reveals that histone acetyltransferase such as p300 and PCAF act as pro-hypertrophic factors. However, it remains elusive whether some histone acetyltransferases can prevent the development of hypertrophy. Males absent on the first (MOF) is a histone acetyltransferase belonging to the MYST (MOZ, Ybf2/Sas3, Sas2 and TIP60) family. Here in this study, we reported that MOF expression was down-regulated in failing human hearts and hypertrophic murine hearts at protein and mRNA levels. To evaluate the roles of MOF in cardiac hypertrophy, we generated cardiac-specific MOF transgenic mice. MOF transgenic mice did not show any differences from their wide-type littermates at baseline. However, cardiac-specific MOF overexpression protected mice from transverse aortic constriction (TAC)-induced cardiac hypertrophy, with reduced radios of heart weight (HW)/body weight (BW), lung weight/BW and HW/tibia length, decreased left ventricular wall thickness and increased fractional shortening. We also observed lower expression of hypertrophic fetal genes in TAC-challenged MOF transgenic mice compared with that of wide-type mice. Mechanically, MOF overexpression increased the expression of Catalase and MnSOD, which blocked TAC-induced ROS and ROS downstream c-Raf-MEK-ERK pathway that promotes hypertrophy. Taken together, our findings identify a novel anti-hypertrophic role of MOF, and MOF is the first reported anti-hypertrophic histone acetyltransferase.

  18. An Analytical Model for Top-Hat Long Transient Mode-Mismatched Thermal Lens Spectroscopy

    NASA Astrophysics Data System (ADS)

    Sabaeian, M.; Rezaei, H.

    2016-02-01

    It has been shown that a top-hat excitation beam gives rise to a more sensitive signal for the thermal lens spectroscopy (TLS). Recently, a numerical model has been presented for a top- hat excitation beam in a dual-beam mod-mismatched TLS [Opt. Lett. 33(13), 1464-1466 (2008)]. In this work, we present a full analytical version of this model. Our model was based on a new solution of time-dependent heat equation for a finite radius cylindrical sample exposed to a top-hat excitation laser beam. The Fresnel diffraction integration method was then used to calculate on-axis probe-beam intensity variations due to thermal lensing by taking the aberrant nature of the thermal lens into account. The model was confirmed with experimental data of LSCAS-2 with an excellent agreement.

  19. 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).

  20. Analysis and test of superplastically formed titanium hat-stiffened panels under compression

    NASA Technical Reports Server (NTRS)

    Davis, Randall C.; Royster, Dick M.; Bales, Thomas T.

    1987-01-01

    Four hat-stiffened titanium panels with two different stiffener configurations were fabricated by superplastic forming/weld brazing and tested under a moderately heavy compressive load. The panels had the same overall dimensions but differed in the shape of the hat-stiffener webs; three panels had stiffeners with flat webs and the other panel had stiffeners with beaded webs. Analysis indicated that the local buckling strain of the flat stiffener web was considerably lower than the general panel buckling strain or cap buckling strain. The analysis also showed that beading the webs of the hat stiffeners removed them as the critical element for local buckling and improved the buckling strain of the panels. The analytical extensional stiffness and failure loads compared very well with experimental results.

  1. 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.

  2. The design of Top-Hat morphological filter and application to infrared target detection

    NASA Astrophysics Data System (ADS)

    Zeng, Ming; Li, Jianxun; Peng, Zhang

    2006-04-01

    Automatic detection and track for infrared target is of great significance in modern world. In this paper, two novel methods which can develop optimizing Top-Hat morphological filtering parameters are presented for spot target detection. One is based on neural network. Its structuring element is a two-layer feed-forward network which is trained by a mass of sample nets. It regards Top-Hat operation as a whole and one layer, and defines the node of the output layer as the maximum gray-scale image vector after Top-Hat operation. The other is based on genetic algorithm. It adopts the interval discretization code and new primary and secondary mood crossover and mutation. Experimental results show that the identified probability of images (SNR is about 2) can reach more than 98% by this method.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

    Narita, Norio; Takahashi, Yasuhiro H.; Kuzuhara, Masayuki; Hirano, Teruyuki; Suenaga, Takuya; Kandori, Ryo; Kudo, Tomoyuki; Sato, Bun'ei; Suzuki, Ryuji; Ida, Shigeru; Nagasawa, Makiko; Abe, Lyu; Brandner, Wolfgang; Brandt, Timothy D.; Carson, Joseph; Egner, Sebastian E.; Feldt, Markus; Goto, Miwa; Grady, Carol A.; Guyon, Olivier; Hashimoto, Jun; Hayano, Yutaka; Hayashi, Masahiko; Hayashi, Saeko S.; Henning, Thomas; Hodapp, Klaus W.; Ishii, Miki; Iye, Masanori; Janson, Markus; Knapp, Gillian R.; Kusakabe, Nobuhiko; Kwon, Jungmi; Matsuo, Taro; Mayama, Satoshi; McElwain, Michael W.; Miyama, Shoken M.; Morino, Jun-Ichi; Moro-Martin, Amaya; Nishimura, Tetsuo; Pyo, Tae-Soo; Serabyn, Eugene; Suto, Hiroshi; Takami, Michihiro; Takato, Naruhisa; Terada, Hiroshi; Thalmann, Christian; Tomono, Daigo; Turner, Edwin L.; Watanabe, Makoto; Wisniewski, John P.; Yamada, Toru; Takami, Hideki; Usuda, Tomonori; Tamura, Motohide

    2012-12-01

    We report that HAT-P-7 has a common proper motion stellar companion. The companion is located at ˜3."9 to the east and estimated to be an M5.5V dwarf based on its colors. We also confirm the presence of a third companion, which was first reported by Winn et al. (2009, ApJ, 703, L99), based on long-term radial velocity measurements. We revisit the migration mechanism of HAT-P-7b given to the presence of those companions, and propose the 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, ApJ, 757, 18).

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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).

  10. The New Photometric Observations for Transiting Exoplanet HAT-P-24b

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Bin; Cameron, Andrew Collier; Gu, Sheng-Hong

    2014-04-01

    The transiting exoplanetary system HAT-P-24 was observed by using CCD cameras at Yunnan Observatory and Hokoon Astronomical Centre, China in 2010 and 2012. Three new transit light curves are analyzed by means of MCMC technique, and the new physical parameters of the system are derived, which are compatible with the old ones in the discovery paper. The orbital period of HAT-P-24b is refined and no obvious TTV signal can be found from five transit events during 2010-2012.

  11. [Remedial action plan for the codisposal and stabilization of the Monument Valley and Mexican Hat uranium mill tailings at Mexican Hat, Utah]. Appendix F, Groundwater hydrology calculations

    SciTech Connect

    1993-12-31

    This document contains the ground water hydrology calculations for the remedial action plan for the codisposal and stabilization of uranium mill tailings at Mexican Hat, Utah. Included are calculations for the following: slug test analyses for monitor wells, analyses of packer tests, hydraulic gradients and ground water velocities, volume of released water, aquifer pumping test analysis, slug test analysis to determine hydraulic conductivity, and gradient calculations.

  12. 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.

  13. 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.

  14. Induction of spermidine/spermine N1-acetyltransferase (SSAT) by aspirin in Caco-2 colon cancer cells.

    PubMed

    Babbar, Naveen; Gerner, Eugene W; Casero, Robert A

    2006-02-15

    Epidemiological, experimental and clinical results suggest that aspirin and other NSAIDs (non-steroidal anti-inflammatory drugs) inhibit the development of colon cancer. It has been shown that the NSAID sulindac induces apoptosis and suppresses carcinogenesis, in part, by a mechanism leading to the transcriptional activation of the gene encoding SSAT (spermidine/spermine N1-acetyltransferase), a rate-limiting enzyme in polyamine catabolism. In the present study, we show that a variety of NSAIDs, including aspirin, sulindac, ibuprofen and indomethacin, can induce SSAT gene expression in Caco-2 cells. Aspirin, at physiological concentrations, can induce SSAT mRNA via transcriptional initiation mechanisms. This induction leads to increased SSAT protein levels and enzyme activity. Promoter deletion analysis of the 5' SSAT promoter-flanking region led to the identification of two NF-kappaB (nuclear factor kappaB) response elements. Electrophoretic mobility-shift assays showed binding of NF-kappaB complexes at these sequences after aspirin treatment. Aspirin treatment led to the activation of NF-kappaB signalling and increased binding at these NF-kappaB sites in the SSAT promoter, hence providing a potential mechanism for the induction of SSAT by aspirin in these cells. Aspirin-induced SSAT ultimately leads to a decrease in cellular polyamine content, which has been associated with decreased carcinogenesis. These results suggest that activation of SSAT by aspirin and different NSAIDs may be a common property of NSAIDs that plays an important role in their chemopreventive actions in colorectal cancer.

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

    DOE PAGES

    Filippova, Ekaterina V.; Weigand, Steven J.; Osipiuk, Jerzy; ...

    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

  16. The dihydrolipoamide acetyltransferase is a novel metabolic longevity factor and is required for calorie restriction-mediated life span extension.

    PubMed

    Easlon, Erin; Tsang, Felicia; Dilova, Ivanka; Wang, Chen; Lu, Shu-Ping; Skinner, Craig; Lin, Su-Ju

    2007-03-02

    Calorie restriction (CR) extends life span in a wide variety of species. Recent studies suggest that an increase in mitochondrial metabolism mediates CR-induced life span extension. Here we present evidence that Lat1 (dihydrolipoamide acetyltransferase), the E2 component of the mitochondrial pyruvate dehydrogenase complex, is a novel metabolic longevity factor in the CR pathway. Deleting the LAT1 gene abolishes life span extension induced by CR. Overexpressing Lat1 extends life span, and this life span extension is not further increased by CR. Similar to CR, life span extension by Lat1 overexpression largely requires mitochondrial respiration, indicating that mitochondrial metabolism plays an important role in CR. Interestingly, Lat1 overexpression does not require the Sir2 family to extend life span, suggesting that Lat1 mediates a branch of the CR pathway that functions in parallel to the Sir2 family. Lat1 is also a limiting longevity factor in nondividing cells in that overexpressing Lat1 extends cell survival during prolonged culture at stationary phase. Our studies suggest that Lat1 overexpression extends life span by increasing metabolic fitness of the cell. CR may therefore also extend life span and ameliorate age-associated diseases by increasing metabolic fitness through regulating central metabolic enzymes.

  17. Opposing Functions of the N-terminal Acetyltransferases Naa50 and NatA in Sister-chromatid Cohesion.

    PubMed

    Rong, Ziye; Ouyang, Zhuqing; Magin, Robert S; Marmorstein, Ronen; Yu, Hongtao

    2016-09-02

    During the cell cycle, sister-chromatid cohesion tethers sister chromatids together from S phase to the metaphase-anaphase transition and ensures accurate segregation of chromatids into daughter cells. N-terminal acetylation is one of the most prevalent protein covalent modifications in eukaryotes and is mediated by a family of N-terminal acetyltransferases (NAT). Naa50 (also called San) has previously been shown to play a role in sister-chromatid cohesion in metazoans. The mechanism by which Naa50 contributes to cohesion is not understood however. Here, we show that depletion of Naa50 in HeLa cells weakens the interaction between cohesin and its positive regulator sororin and causes cohesion defects in S phase, consistent with a role of Naa50 in cohesion establishment. Strikingly, co-depletion of NatA, a heterodimeric NAT complex that physically interacts with Naa50, rescues the sister-chromatid cohesion defects and the resulting mitotic arrest caused by Naa50 depletion, indicating that NatA and Naa50 play antagonistic roles in cohesion. Purified recombinant NatA and Naa50 do not affect each other's NAT activity in vitro Because NatA and Naa50 exhibit distinct substrate specificity, we propose that they modify different effectors and regulate sister-chromatid cohesion in opposing ways.

  18. WASP-35b, WASP-48b, AND HAT-P-30b/WASP-51b: TWO NEW PLANETS AND AN INDEPENDENT DISCOVERY OF A HAT PLANET

    SciTech Connect

    Enoch, B.; Brown, D. J. A.; Cameron, A. Collier; Anderson, D. R.; Smalley, B.; Barros, S. C. C.; Faedi, F.; Gillon, M.; Hebrard, G.; Bouchy, F.; Lister, T. A.; Street, R. A.; Queloz, D.; Triaud, A. H. M. J.; Santerne, A.; West, R. G.; Butters, O.; Bento, J.; Fossati, L.; Haswell, C. A.

    2011-09-15

    We report the detection of WASP-35b, a planet transiting a metal-poor ([Fe/H] = -0.15) star in the Southern hemisphere, WASP-48b, an inflated planet which may have spun-up its slightly evolved host star of 1.75 R{sub sun} in the Northern hemisphere, and the independent discovery of HAT-P-30b/WASP-51b, a new planet in the Northern hemisphere. Using WASP, RISE, Faulkes Telescope South, and TRAPPIST photometry, with CORALIE, SOPHIE, and NOT spectroscopy, we determine that WASP-35b has a mass of 0.72 {+-} 0.06 M{sub J} and radius of 1.32 {+-} 0.05R{sub J} , and orbits with a period of 3.16 days, WASP-48b has a mass of 0.98 {+-} 0.09 M{sub J} , radius of 1.67 {+-} 0.10 R{sub J} , and orbits in 2.14 days, while HAT-P-30b/WASP-51b, with an orbital period of 2.81 days, is found to have a mass of 0.76 {+-} 0.05 M{sub J} and radius of 1.42 {+-} 0.03 R{sub J} , agreeing with values of 0.71 {+-} 0.03 M{sub J} and 1.34 {+-} 0.07 R{sub J} reported for HAT-P-30b.

  19. HAT-P-34b-HAT-P-37b: Four Transiting Planets More Massive than Jupiter Orbiting Moderately Bright Stars

    NASA Astrophysics Data System (ADS)

    Bakos, G. Á.; Hartman, J. D.; Torres, G.; Béky, B.; Latham, D. W.; Buchhave, L. A.; Csubry, Z.; Kovács, G.; Bieryla, A.; Quinn, S.; Szklenár, T.; Esquerdo, G. A.; Shporer, A.; Noyes, R. W.; Fischer, D. A.; Johnson, J. A.; Howard, A. W.; Marcy, G. W.; Sato, B.; Penev, K.; Everett, M.; Sasselov, D. D.; Fűrész, G.; Stefanik, R. P.; Lázár, J.; Papp, I.; Sári, P.

    2012-07-01

    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 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 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. 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 (A289Hr) and NASA (N167Hr and N029Hr). Based in part on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. Based in part on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.

  20. Effect of increased yeast alcohol acetyltransferase activity on flavor profiles of wine and distillates.

    PubMed

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

    2000-02-01

    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

  1. Global Position and Recruitment of HATs and HDACs in the Yeast Genome

    PubMed Central

    Robert, François; Pokholok, Dmitry K.; Hannett, Nancy M.; Rinaldi, Nicola J.; Chandy, Mark; Rolfe, Alex; Workman, Jerry L.; Gifford, David K.; Young, Richard A.

    2010-01-01

    Summary Chromatin regulators play fundamental roles in the regulation of gene expression and chromosome maintenance, but the regions of the genome where most of these regulators function has not been established. We explored the genome-wide occupancy of four different chromatin regulators encoded in Saccharomyces cerevisiae. The results reveal that the histone acetyltransferases Gcn5 and Esa1 are both generally recruited to the promoters of active protein-coding genes. In contrast, the histone deacetylases Hst1 and Rpd3 are recruited to specific sets of genes associated with distinct cellular functions. Our results provide new insights into the association of histone acetyltransferases and histone deacetylases with the yeast genome, and together with previous studies, suggest how these chromatin regulators are recruited to specific regions of the genome. PMID:15494307

  2. 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.

  3. Learning to Look, Learning to Read: Dr. Seuss'"The Cat in the Hat."

    ERIC Educational Resources Information Center

    Bodmer, George

    1997-01-01

    States that "The Cat in the Hat" (1957), written from a basic 225 word list, explores the level of activity that a child needs to keep secret from the adult world, and is a picture book which is also nominally a "reader" and not a storybook. Includes questions for stimulating student response; encapsulates classic elements in…

  4. 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)

  5. 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…

  6. Planet-induced Stellar Pulsations in HAT-P-2's Eccentric System

    NASA Astrophysics Data System (ADS)

    de Wit, Julien; Lewis, Nikole K.; Knutson, Heather A.; Fuller, Jim; Antoci, Victoria; Fulton, Benjamin J.; Laughlin, Gregory; Deming, Drake; Shporer, Avi; Batygin, Konstantin; Cowan, Nicolas B.; Agol, Eric; Burrows, Adam S.; Fortney, Jonathan J.; Langton, Jonathan; Showman, Adam P.

    2017-02-01

    Extrasolar planets on eccentric short-period orbits provide a laboratory in which to study radiative and tidal interactions between a planet and its host star under extreme forcing conditions. Studying such systems probes how the planet’s atmosphere redistributes the time-varying heat flux from its host and how the host star responds to transient tidal distortion. Here, we report the insights into the planet–star interactions in HAT-P-2's eccentric planetary system gained from the analysis of ∼350 hr of 4.5 μm observations with the Spitzer Space Telescope. The observations show no sign of orbit-to-orbit variability nor of orbital evolution of the eccentric planetary companion, HAT-P-2 b. The extensive coverage allows us to better differentiate instrumental systematics from the transient heating of HAT-P-2 b’s 4.5 μm photosphere and yields the detection of stellar pulsations with an amplitude of approximately 40 ppm. These pulsation modes correspond to exact harmonics of the planet’s orbital frequency, indicative of a tidal origin. Transient tidal effects can excite pulsation modes in the envelope of a star, but, to date, such pulsations had only been detected in highly eccentric stellar binaries. Current stellar models are unable to reproduce HAT-P-2's pulsations, suggesting that our understanding of the interactions at play in this system is incomplete.

  7. 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.

  8. 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,…

  9. Qualification test report bump protection hat (subassembly of T020/M509 head protective assembly)

    NASA Technical Reports Server (NTRS)

    Willis, D. B.

    1972-01-01

    The bump protection hat (BPH) was subjected to impact testing in which it underwent three impacts at 35 foot-pounds of energy. The impacts generated stress cracks, but no penetration. All impacts resulted in deflections of less than one-half inch. It was shown that the BPH is qualified for Skylab and the rescue vehicle.

  10. 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.

  11. 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.,…

  12. 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.

  13. Photometric Observations and Study of the Transiting Exoplanetary System HAT-P-8

    NASA Astrophysics Data System (ADS)

    Tan, H. B.; Wang, X. B.; Gu, S. H.; Cameron, A. C.

    2013-11-01

    Three transit events of HAT-P-8 are observed by using the 1 m telescope of Yunnan Observatory and 2.4 m telescope of Lijiang Observing Station in 2009 and 2012, respectively. The observational data were reduced with the coarse de-correlation and SysRem algorithms in order to obtain high signal to noise ratio for the transit feature. The MCMC (Markov Chain Monte Carlo) technique is applied to analyze three transit light curves simultaneously, then the new parameters of HAT-P-8 system are derived. The new value of the radius for HAT-P-8b is smaller than the one given by Latham et al., but it is consistent with the value derived by Mancini et al. recently. By linear fitting to the 23 mid-transit times with high precision, the orbital period of HAT-P-8b is refined as P=3.0763461±0.0000021 d. No obvious TTV (Transit Timing Variation) signal can be found from the present (O-C) analysis.

  14. Photometric Observation and Study of the Transiting Exoplanetary System HAT-P-8

    NASA Astrophysics Data System (ADS)

    Tan, Hong-Bo; Wang, Xiao-Bin; Gu, Sheng-Hong; Cameron, Andrew Collier

    2014-07-01

    Three transit events of HAT-P-8 were observed by using the 1 m telescope of Yunnan Observatory and the 2.4 m telescope of Lijiang Astronomical Station in 2009 and 2012, respectively. The observational data are reduced with the coarse de-correlation and SysRem algorithms in order to improve the signal to noise ratio of the transit signals. The MCMC (Markov Chain Monte Carlo) technique is applied to analyzing the three transit light curves simultaneously, then the new parameters of the HAT-P-8 system are derived. The new value of the radius of HAT-P-8b is smaller than that given by Latham et al., while it is consistent with the value derived recently by Mancini et al. By linear fitting on the 23 high-precision mid-transit times, the orbital period of HAT-P-8b is refined as P =3.0763461±0.0000021 d, and from the (O - C) analysis no obvious TTV (Transit Timing Variation) signal has been detected.

  15. Combined Action of Histone Reader Modules Regulates NuA4 Local Acetyltransferase Function but Not Its Recruitment on the Genome.

    PubMed

    Steunou, Anne-Lise; Cramet, Myriam; Rossetto, Dorine; Aristizabal, Maria J; Lacoste, Nicolas; Drouin, Simon; Côté, Valérie; Paquet, Eric; Utley, Rhea T; Krogan, Nevan; Robert, François; Kobor, Michael S; Côté, Jacques

    2016-11-15

    Recognition of histone marks by reader modules is thought to be at the heart of epigenetic mechanisms. These protein domains are considered to function by targeting regulators to chromosomal loci carrying specific histone modifications. This is important for proper gene regulation as well as propagation of epigenetic information. The NuA4 acetyltransferase complex contains two of these reader modules, an H3K4me3-specific plant homeodomain (PHD) within the Yng2 subunit and an H3K36me2/3-specific chromodomain in the Eaf3 subunit. While each domain showed a close functional interaction with the respective histone mark that it recognizes, at the biochemical level, genetic level (as assessed with epistatic miniarray profile screens), and phenotypic level, cells with the combined loss of both readers showed greatly enhanced phenotypes. Chromatin immunoprecipitation coupled with next-generation sequencing experiments demonstrated that the Yng2 PHD specifically directs H4 acetylation near the transcription start site of highly expressed genes, while Eaf3 is important downstream on the body of the genes. Strikingly, the recruitment of the NuA4 complex to these loci was not significantly affected. Furthermore, RNA polymerase II occupancy was decreased only under conditions where both PHD and chromodomains were lost, generally in the second half of the gene coding regions. Altogether, these results argue that methylated histone reader modules in NuA4 are not responsible for its recruitment to the promoter or coding regions but, rather, are required to orient its acetyltransferase catalytic site to the methylated histone 3-bearing nucleosomes in the surrounding chromatin, cooperating to allow proper transition from transcription initiation to elongation.

  16. 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.

  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. The Chromatin Regulator BRPF3 Preferentially Activates the HBO1 Acetyltransferase but Is Dispensable for Mouse Development and Survival*

    PubMed Central

    Yan, Kezhi; You, Linya; Degerny, Cindy; Ghorbani, Mohammad; Liu, Xin; Chen, Lulu; Li, Lin; Miao, Dengshun; Yang, Xiang-Jiao

    2016-01-01

    To interpret epigenetic information, chromatin readers utilize various protein domains for recognition of DNA and histone modifications. Some readers possess multidomains for modification recognition and are thus multivalent. Bromodomain- and plant homeodomain-linked finger-containing protein 3 (BRPF3) is such a chromatin reader, containing two plant homeodomain-linked fingers, one bromodomain and a PWWP domain. However, its molecular and biological functions remain to be investigated. Here, we report that endogenous BRPF3 preferentially forms a tetrameric complex with HBO1 (also known as KAT7) and two other subunits but not with related acetyltransferases such as MOZ, MORF, TIP60, and MOF (also known as KAT6A, KAT6B, KAT5, and KAT8, respectively). We have also characterized a mutant mouse strain with a lacZ reporter inserted at the Brpf3 locus. Systematic analysis of β-galactosidase activity revealed dynamic spatiotemporal expression of Brpf3 during mouse embryogenesis and high expression in the adult brain and testis. Brpf3 disruption, however, resulted in no obvious gross phenotypes. This is in stark contrast to Brpf1 and Brpf2, whose loss causes lethality at E9.5 and E15.5, respectively. In Brpf3-null mice and embryonic fibroblasts, RT-quantitative PCR uncovered no changes in levels of Brpf1 and Brpf2 transcripts, confirming no compensation from them. These results indicate that BRPF3 forms a functional tetrameric complex with HBO1 but is not required for mouse development and survival, thereby distinguishing BRPF3 from its paralogs, BRPF1 and BRPF2. PMID:26677226

  19. Overexpression and characterization of the chromosomal aminoglycoside 2'-N-acetyltransferase of Providencia stuartii.

    PubMed

    Franklin, K; Clarke, A J

    2001-08-01

    The gene coding for aminoglycoside 2'-N-acetyltransferase Ia [AAC(2')-Ia] from Providencia stuartii was amplified by PCR and cloned. The resulting construct, pACKF2, was transferred into Escherichia coli for overexpression of AAC(2')-Ia as a fusion protein with an N-terminal hexa-His tag. The fusion protein was isolated and purified by affinity chromatography on Ni(2+)-nitrilotriacetic acid agarose and gel permeation chromatography on Superdex 75. Comparison of the specific activity of this enzyme with that of its enterokinase-digested derivative lacking the His tag indicated that the presence of the extra N-terminal peptide does not affect activity. The temperature and pH optima for activity of both forms of the 2'-N-acetyltransferase were 20 degrees C and pH 6.0, respectively, while the enzymes were most stable at 15 degrees C and pH 8.1. The Michaelis-Menten kinetic parameters for AAC(2')-Ia at 20 degrees C and pH 6.0 were determined using a series of aminoglycoside antibiotics possessing a 2'-amino group and a concentration of acetyl coenzyme A fixed at 10 times its K(m) value of 8.75 microM. Under these conditions, gentamicin was determined to be the best substrate for the enzyme in terms of both K(m) and k(cat)/K(m) values, whereas neomycin was the poorest. Comparison of the kinetic parameters obtained with the different aminoglycosides indicated that their hexopyranosyl residues provided the most important binding sites for AAC(2')-Ia activity, while the enzyme exhibits greater tolerance further from these sites. No correlation was found between these kinetic parameters and MICs determined for P. stuartii PR50 expressing the 2'-N-acetyltransferase, suggesting that its true in vivo function is not as a resistance factor.

  20. Choline Acetyltransferase Activity in Striatum of Neonatal Rats Increased by Nerve Growth Factor

    NASA Astrophysics Data System (ADS)

    Mobley, William C.; Rutkowski, J. Lynn; Tennekoon, Gihan I.; Buchanan, Karen; Johnston, Michael V.

    1985-07-01

    Some neurodegenerative disorders may be caused by abnormal synthesis or utilization of trophic molecules required to support neuronal survival. A test of this hypothesis requires that trophic agents specific for the affected neurons be identified. Cholinergic neurons in the corpus striatum of neonatal rats were found to respond to intracerebroventricular administration of nerve growth factor with prominent, dose-dependent, selective increases in choline acetyltransferase activity. Cholinergic neurons in the basal forebrain also respond to nerve growth factor in this way. These actions of nerve growth factor may indicate its involvement in the normal function of forebrain cholinergic neurons as well as in neurodegenerative disorders involving such cells.

  1. 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.

  2. 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

  3. 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.

  4. 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)

  5. 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.

  6. Specific alkylation of a histidine residue in carnitine acetyltransferase by bromoacetyl-l-carnitine

    PubMed Central

    Chase, J. F. A.; Tubbs, P. K.

    1970-01-01

    Incubation of carnitine acetyltransferase with low concentrations of bromoacetyl-l-carnitine causes a rapid and irreversible loss of enzyme activity; one mol of inhibitor can inactivate one mol of enzyme. Bromoacetyl-d-carnitine, iodoacetate or iodoacetamide are ineffective. l-Carnitine protects the transferase from bromoacetyl-l-carnitine. Investigation shows that the enzyme first reversibly binds bromoacetyl-l-carnitine with an affinity similar to that shown for the normal substrate acetyl-l-carnitine; this binding is followed by an alkylation reaction, forming the carnitine ester of a monocarboxymethyl-protein, which is catalytically inactive. The carnitine is released at an appreciable rate by spontaneous hydrolysis, and the resulting carboxymethyl-enzyme is also inactive. Total acid hydrolysis of enzyme after treatment with 2-[14C]bromoacetyl-l-carnitine yields N-3-carboxy[14C]methylhistidine as the only labelled amino acid. These findings, taken in conjunction with previous work, suggest that the single active centre of carnitine acetyltransferase contains a histidine residue. PMID:5461620

  7. 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

  8. An extracellular factor regulating expression of the chromosomal aminoglycoside 2'-N-acetyltransferase of Providencia stuartii.

    PubMed

    Rather, P N; Parojcic, M M; Paradise, M R

    1997-08-01

    The chromosomal aac(2')-Ia gene in Providencia stuartii encodes a housekeeping 2'-N-acetyltransferase [AAC(2')-Ia] involved in the acetylation of peptidoglycan. In addition, the AAC(2')-Ia enzyme also acetylates and confers resistance to the clinically important aminoglycoside antibiotics gentamicin, tobramycin, and netilmicin. Expression of the aac(2')-Ia gene was found to be strongly influenced by cell density, with a sharp decrease in aac(2')-Ia mRNA accumulation as cells approached stationary phase. This decrease was mediated by the accumulation of an extracellular factor, designated AR (for acetyltransferase repressing)-factor. AR-factor was produced in both minimal and rich media and acted in a manner that was strongly dose dependent. The activity of AR-factor was also pH dependent, with optimal activity at pH 8.0 and above. Biochemical characterization of conditioned media from P. stuartii has shown that AR-factor is between 500 and 1,000 Da in molecular size and is heat stable. In addition, AR-factor was inactivated by a variety of proteases, suggesting that it may be a small peptide.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. Cysteine biosynthesis in Lactobacillus casei: identification and characterization of a serine acetyltransferase

    PubMed Central

    Bogicevic, Biljana; Berthoud, Hélène; Portmann, Reto; Bavan, Tharmatha; Meile, Leo; Irmler, Stefan

    2016-01-01

    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

  14. 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.

  15. 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

  16. Interaction between cysteine synthase and serine O-acetyltransferase proteins and their stage specific expression in Leishmania donovani.

    PubMed

    Singh, Kuljit; Singh, Krishn Pratap; Equbal, Asif; Suman, Shashi S; Zaidi, Amir; Garg, Gaurav; Pandey, Krishna; Das, Pradeep; Ali, Vahab

    2016-12-01

    Leishmania possess a unique trypanothione redox metabolism with undebated roles in protection from oxidative damage and drug resistance. The biosynthesis of trypanothione depends on l-cysteine bioavailability which is regulated by cysteine biosynthesis pathway. The de novo cysteine biosynthesis pathway is comprised of serine O-acetyltransferase (SAT) and cysteine synthase (CS) enzymes which sequentially mediate two consecutive steps of cysteine biosynthesis, and is absent in mammalian host. However, despite the apparent dependency of redox metabolism on cysteine biosynthesis pathway, the role of SAT and CS in redox homeostasis has been unexplored in Leishmania parasites. Herein, we have characterized CS and SAT to investigate their interaction and relative abundance of these proteins in promastigote vs. amastigote growth stages of L. donovani. CS and SAT genes of L. donovani (LdCS and LdSAT) were cloned, expressed, and fusion proteins purified to homogeneity with affinity column chromatography. Purified LdCS contains PLP as cofactor and showed optimum enzymatic activity at pH 7.5. Enzyme kinetics showed that LdCS catalyses the synthesis of cysteine using O-acetylserine and sulfide with a Km of 15.86 mM and 0.17 mM, respectively. Digitonin fractionation and indirect immunofluorescence microscopy showed that LdCS and LdSAT are localized in the cytoplasm of promastigotes. Size exclusion chromatography, co-purification, pull down and immuno-precipitation assays demonstrated a stable complex formation between LdCS and LdSAT proteins. Furthermore, LdCS and LdSAT proteins expression/activity was upregulated in amastigote growth stage of the parasite. Thus, the stage specific differential expression of LdCS and LdSAT suggests that it may have a role in the redox homeostasis of Leishmania.

  17. Mechanism of action of peptidoglycan O-acetyltransferase B involves a Ser-His-Asp catalytic triad.

    PubMed

    Moynihan, Patrick J; Clarke, Anthony J

    2014-10-07

    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.

  18. 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.

  19. 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.

  20. 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.

  1. Analytical and experimental study of structurally efficient composite hat-stiffened panels loaded in axial compression

    NASA Technical Reports Server (NTRS)

    Williams, J. G.; Mikulus, M. M., Jr.

    1976-01-01

    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 programming 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 suggests that most of the theoretical weight saving potential is available if design deficiencies are eliminated and strict fabrication control is exercised.

  2. Time-resolved thermal mirror technique with top-hat cw laser excitation.

    PubMed

    Astrath, Francine B; Astrath, Nelson G; Shen, Jun; Zhou, Jianqin; Malacarne, Luis C; Pedreira, P R B; Baesso, Mauro L

    2008-08-04

    A theoretical model was developed for time-resolved thermal mirror spectroscopy under top-hat cw laser excitation that induced a nanoscale surface displacement of a low absorption sample. An additional phase shift to the electrical field of a TEM(00) probe beam reflected from the surface displacement was derived, and Fresnel diffraction theory was used to calculate the propagation of the probe beam. With the theory, optical and thermal properties of three glasses were measured, and found to be consistent with literature values. With a top-hat excitation, an experimental apparatus was developed for either a single thermal mirror or a single thermal lens measurement. Furthermore, the apparatus was used for concurrent measurements of thermal mirror and thermal lens. More physical properties could be measured using the concurrent measurements.

  3. 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

    2009-08-07

    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.

  4. HAT-P-7: A Retrograde or Polar Orbit, and a Third Body

    NASA Technical Reports Server (NTRS)

    Winn, Joshua N.; Johnson, John Asher; Albrecht, Simon; Howard, Andrew W.; Marcy, Geoffrey W.; Crossfield, Ian J.; Holman, Matthew J.

    2009-01-01

    We showed that the exoplanet HAT-P-7b has an extremely tilted orbit, with a true angle of at least 86 degrees with respect to its parent star's equatorial plane, and a strong possibility of retrograde motion. We also report evidence for an additional planet or companion star. The Rossiter-McLaughlin effect was found to be a blueshift during the first half of the transit and a redshift during the second half, an inversion of the usual pattern, implying that the angle between the sky-projected orbital and stellar angular momentum vectors is 182.5 plus or minus 9.4 degrees. The third body is implicated by excess RV variation of the host star over 2 yr. Some possible explanations for the tilted orbit of HAT-P-7b are a close encounter with another planet, the Kozai effect, and resonant capture by an inward-migrating outer planet.

  5. The Red Hat Society: Exploring the role of play, liminality, and communitas in older women's lives.

    PubMed

    Mackay Yarnal, Careen

    2006-01-01

    There is an extensive literature on play. Yet, the role of play in older adults' lives has received limited attention. Strikingly absent is research on play and older women. Missing from the literature is how older women use play as a liminal context for social interaction and communitas. This is odd because by 2030 one in four American women will be over the age of sixty-five. The primary purpose of this study is to explore the roles of play, liminality, and communitas in older women's lives. The focus is the Red Hat Society, a social group for women over age 50 that fosters play and fun. Using qualitative interviews with focus groups and participant observation of a regional Red Hat Society event, the study highlights some of the strengths and weaknesses of current conceptualizations of play, liminality, and communitas.

  6. 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.

  7. 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.

  8. 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.

  9. HAT-P-26b: A Neptune-mass Exoplanet with Primordial Solar Heavy Element Abundance

    NASA Astrophysics Data System (ADS)

    Wakeford, Hannah R.; Sing, David K.; Kataria, Tiffany; Deming, Drake; Nikolov, Nikolay; Lopez, Eric; Tremblin, Pascal; Skalid Amundsen, David; Lewis, Nikole K.; Mandell, Avi; Fortney, Jonathan J.; Knutson, Heather; Benneke, Björn; Evans, Tom M.

    2017-01-01

    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.

  10. 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

  11. HATS-5b: A Transiting Hot Saturn from the HATSouth Survey

    NASA Astrophysics Data System (ADS)

    Zhou, G.; Bayliss, D.; Penev, K.; Bakos, G. Á.; Hartman, J. D.; Jordán, A.; Mancini, L.; Mohler, M.; Csubry, Z.; Ciceri, S.; Brahm, R.; Rabus, M.; Buchhave, L.; Henning, T.; Suc, V.; Espinoza, N.; Béky, B.; Noyes, R. W.; Schmidt, B.; Butler, R. P.; Shectman, S.; Thompson, I.; Crane, J.; Sato, B.; Csák, B.; Lázár, J.; Papp, I.; Sári, P.; Nikolov, N.

    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 Mp ≈ 0.24 M J, radius of Rp ≈ 0.91 R 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 ⊙, and radius of 0.87 R ⊙. 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. 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. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

  12. The discovery of DLT17h/AT 2017ahn with PROMPT

    NASA Astrophysics Data System (ADS)

    Tartaglia, L.; Sand, D.; Valenti, S.; Reichart, D. E.; Haislip, J. B.; Kouprianov, V.

    2017-02-01

    We report the discovery of DLT17h/AT 2017ahn. The object was discovered on 2017-02-08.29 UT at R 18.10 mag (absolute magnitude -14.94 mag, assuming a distance modulus of 32.87 mag and a Galactic foreground extinction of 0.17 mag), during the ongoing D20.8 mag) on 2017-02-07.23 UT or in prior imaging of the field.

  13. HAT-South: A Global Network of Southern Hemisphere Automated Telescopes to Detect Transiting Exoplanets

    NASA Astrophysics Data System (ADS)

    Bakos, G.; Afonso, C.; Henning, T.; Jordán, A.; Holman, M.; Noyes, R. W.; Sackett, P. D.; Sasselov, D.; Kovács, Gábor; Csubry, Z.; Pál, A.

    2009-02-01

    HAT-South is a network of six identical, fully automated wide field telescopes, to be located at three sites (Chile: Las Campanas, Australia: Siding Springs, and Namibia: HESS site) in the Southern hemisphere. The primary purpose of the network is to detect and characterize a large number of extra-solar planets transiting nearby bright stars, and to explore their diversity. Operation of HAT-South is a collaboration among the Harvard-Smithsonian Center for Astrophysics (CfA), Max Planck Institute for Astronomy (MPIA) and the Australian National University (ANU). The network is expected to be ready for initial science operations in 2009. The three sites will permit near round-the-clock monitoring of selected fields, and the continuous data-stream will greatly enhance recovery of transits. HAT-South will be sensitive to planetary transits down to R≈14 across a 128 square-degrees combined field of view, thereby targeting a large number of dwarfs with feasible confirmation-mode follow-up. We anticipate a yearly detection rate of approximately 25 planets transiting bright stars.

  14. 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.

  15. The Hat Yai 2000 flood: the worst flood in Thai history

    NASA Astrophysics Data System (ADS)

    Supharatid, Seree

    2006-02-01

    Hat Yai, the largest commercial and tourist city in southern Thailand, is subjected to regular flood events, primarily during the northeast monsoon period. Flooding in this region is recognized as a serious disaster in terms of frequency, rate of risk, and affected areas. The monsoon of 21-25 November 2000 caused extremely heavy rain in the southern part of Thailand, resulting in a great flood occupying Hat Yai. This caused significant damage. Therefore, the use of both structural and non-structural measures is mandatory to reduce the economic losses and the risk for society. This paper investigates two modelling approaches for flood prevention and mitigation of Hat Yai city. First, a hard computing approach by a physically distributed model was applied to study the flood behaviour in a two-dimensional floodplain flow. Second, a soft computing approach using a neuro-genetic algorithm was used to develop a flood-forecasting tool. It was found that the great flood of 2000 can be simulated well by the FLO-2D model. Computed discharges and flood level in the floodplain are close to the observed data. Countermeasures using diversion canals are guaranteed to accelerate the floodwater drainage to Songkla Lake, significantly reducing the flood impact to the people. In addition, the flood forecasting technique developed in this study can give satisfactory results. This would be very useful as a flood-warning tool for the community

  16. On Variable Geometric Factor Systems for Top-Hat Electrostatic Space Plasma Analyzers

    NASA Technical Reports Server (NTRS)

    Kataria, Dhiren O.; Collinson, Glyn A.

    2010-01-01

    Even in the relatively small region of space that is the Earth's magnetosphere, ion and electron fluxes can vary by several orders of magnitude. Top-hat electrostatic analyzers currently do not possess the dynamic range required to sample plasma under all conditions. The purpose of this study was to compare, through computer simulation, three new electrostatic methods that would allow the sensitivity of a sensor to be varied through control of its geometric factor (GF) (much like an aperture on a camera). The methods studied were inner filter plates, split hemispherical analyzer (SHA) and top-cap electrode. This is the first discussion of the filter plate concept and also the first study where all three systems are studied within a common analyzer design, so that their relative merits could be fairly compared. Filter plates were found to have the important advantage that they facilitate the reduction in instrument sensitivity whilst keeping all other instrument parameters constant. However, it was discovered that filter plates have numerous disadvantages that make such a system impracticable for a top-hat electrostatic analyzer. It was found that both the top-cap electrode and SHA are promising variable geometric factor system (VGFS) concepts for implementation into a top-hat electrostatic analyzer, each with distinct advantages over the other.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Discovery of the secondary eclipse of HAT-P-11 b

    NASA Astrophysics Data System (ADS)

    Huber, K. F.; Czesla, S.; Schmitt, J. H. M. M.

    2017-01-01

    We report the detection of the secondary eclipse of HAT-P-11 b, a Neptune-sized planet orbiting an active K4 dwarf. Using all available short-cadence data of the Kepler mission, we derive refined planetary ephemeris increasing their precision by more than an order of magnitude. Our simultaneous primary and secondary transit modeling results in improved transit and orbital parameters. In particular, the precise timing of the secondary eclipse allows to pin down the orbital eccentricity to . The secondary eclipse depth of ppm corresponds to a 5.5σ detection and results in a geometric albedo of 0.39 ± 0.07 for HAT-P-11 b, close to Neptune's value, which may indicate further resemblances between these two bodies. Due to the substantial orbital eccentricity, the planetary equilibrium temperature is expected to change significantly with orbital position and ought to vary between 630 K and 950 K, depending on the details of heat redistribution in the atmosphere of HAT-P-11 b.

  2. 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.

  3. 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.

  4. Production of tetraacetyl phytosphingosine (TAPS) in Wickerhamomyces ciferrii is catalyzed by acetyltransferases Sli1p and Atf2p.

    PubMed

    Ter Veld, Frank; Wolff, Daniel; Schorsch, Christoph; Köhler, Tim; Boles, Eckhard; Poetsch, Ansgar

    2013-10-01

    Wickerhamomyces ciferrii secretes tetraacetyl phytosphingosine (TAPS), and in this study, the catalyzing acetyltransferases were identified using mass spectrometry-based proteomics. The proteome of wild-type strain NRRL Y-1031 served as control and was compared to the tetraacetyl phytosphingosine defective mating type NRRL Y-1031-27. Acetylation of phytosphingosine in W. ciferrii is catalyzed by acetyltransferases Sli1p and Atf2p, encoded by genes similar to Saccharomyces cerevisiae YGR212W and YGR177C, respectively. Ablation of SLI1 resulted in an almost complete loss of tri- and tetraacetyl phytosphingosines, whereas the loss ATF2 resulted in an 15-fold increase in triacetyl phytosphingosine. Most likely, it is the concerted action of these two acetyltransferases that yields tetraacetyl phytosphingosine, in which Sli1p catalyzes initial O- and N-acetylation, producing triacetyl phytosphingosine. Finally, Atf2p catalyzes final O-acetylation to yield tetraacetyl phytosphingosine. The current study demonstrates that mass spectrometry-based proteomics can be employed to identify key steps in ill-explored metabolite biosynthesis pathways of nonconventional microorganisms. Furthermore, the identification of phytosphingosine as substrate for alcohol acetyltransferase Atf2p broadens the known substrate range of this enzyme. This interesting property of Atf2p may be exploited to enhance the secretion of heterologous compounds.

  5. Homologues of xenobiotic metabolizing N-acetyltransferases in plant-associated fungi: Novel functions for an old enzyme family

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant-pathogenic fungi and their hosts engage in chemical warfare, attacking each other with toxic products of secondary metabolism and defending themselves via an arsenal of xenobiotic metabolizing enzymes. One such enzyme is homologous to arylamine N-acetyltransferase (NAT) and has been identified...

  6. Arylamine N-acetyltransferases: a structural perspective. Comments regarding the BJP paper by Zhou et al., 2013

    PubMed Central

    Xu, Ximing; Kubiak, Xavier; Dupret, Jean-Marie; Rodrigues-Lima, Fernando

    2014-01-01

    This letter is a comment on Zhou et al. (2013). Arylamine N-acetyltransferases: a structural perspective. Br J Pharmacol 169: 748–760. To view this article visit http://dx.doi.org/10.1111/bph.12182 PMID:24328723

  7. Comparative genomic, phylogenetic, and functional 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 (Glenn and Bacon, 2009; Glenn et al., 2010). The NAT1 gene of Gibberella moniliformis was the...

  8. HATS-8b: A Low-density Transiting Super-Neptune

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    HATS-8b is a low density transiting super-Neptune discovered as part of the HATSouth project. The planet orbits its solar-like G-dwarf host (V = 14.03+/- 0.10, {T}{eff} = 5679+/- 50 K) with a period of 3.5839 days. HATS-8b is the third lowest-mass transiting exoplanet to be discovered from a wide-field ground-based search, and with a mass of 0.138+/- 0.019 {M}{{J}} it is approximately halfway between the masses of Neptune and Saturn. However, HATS-8b has a radius of {0.873}-0.075+0.123 {R}{{J}}, resulting in a bulk density of just 0.259+/- 0.091 {{g}} {{cm}}-3. The metallicity of the host star is super-solar ([{Fe}/{{H}}] = 0.210+/- 0.080), providing evidence against the idea that low-density exoplanets form from metal-poor environments. The low density and large radius of HATS-8b results in an atmospheric scale height of almost 1000 km, and in addition to this there is an excellent reference star of nearly equal magnitude at just 19″ separation in the sky. These factors make HATS-8b an exciting target for future atmospheric characterization studies, particularly for long-slit transmission spectroscopy. 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 site is operated in conjunction with MPIA, and the station at Siding Spring Observatory is operated jointly with ANU. This paper includes data gathered with the 6.5 m Magellan Telescopes located in LCO, Chile. The work is based in part on observations made with the MPG 2.2 m Telescope and the ESO 3.6 m Telescope at the ESO Observatory in La Silla. This paper uses observations obtained using the facilities of the Las Cumbres Observatory Global Telescope.

  9. 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.

  10. Lysine acetyltransferase NuA4 and acetyl-CoA regulate glucose-deprived stress granule formation in Saccharomyces cerevisiae

    PubMed Central

    Huard, Sylvain; Morettin, Alan; Fullerton, Morgan D.; Côté, Jocelyn

    2017-01-01

    Eukaryotic cells form stress granules under a variety of stresses, however the signaling pathways regulating their formation remain largely unknown. We have determined that the Saccharomyces cerevisiae lysine acetyltransferase complex NuA4 is required for stress granule formation upon glucose deprivation but not heat stress. Further, the Tip60 complex, the human homolog of the NuA4 complex, is required for stress granule formation in cancer cell lines. Surprisingly, the impact of NuA4 on glucose-deprived stress granule formation is partially mediated through regulation of acetyl-CoA levels, which are elevated in NuA4 mutants. While elevated acetyl-CoA levels suppress the formation of glucose-deprived stress granules, decreased acetyl-CoA levels enhance stress granule formation upon glucose deprivation. Further our work suggests that NuA4 regulates acetyl-CoA levels through the Acetyl-CoA carboxylase Acc1. Altogether this work establishes both NuA4 and the metabolite acetyl-CoA as critical signaling pathways regulating the formation of glucose-deprived stress granules. PMID:28231279

  11. A Metazoan ATAC Acetyltransferase Subunit That Regulates Mitogen-activated Protein Kinase Signaling Is Related to an Ancient Molybdopterin Synthase Component*

    PubMed Central

    Suganuma, Tamaki; Mushegian, Arcady; Swanson, Selene K.; Florens, Laurence; Washburn, Michael P.; Workman, Jerry L.

    2012-01-01

    Molybdopterin (MPT) synthase is an essential enzyme involved in the synthesis of the molybdenum cofactor precursor molybdopterin. The molybdenum cofactor biosynthetic pathway is conserved from prokaryotes to Metazoa. CG10238 is the Drosophila homolog of the MoaE protein, a subunit of MPT synthase, and is found in a fusion with the mitogen-activated protein kinase (MAPK)-upstream protein kinase-binding inhibitory protein (MBIP). This fused protein inhibits the activation of c-Jun N-terminal kinase (JNK). dMoaE (CG10238) carries out this function as a subunit of the ATAC histone acetyltransferase complex. In this study, we demonstrate that Drosophila MoaE (CG10238) also interacts with Drosophila MoaD and with itself to form a complex with stoichiometry identical to the MPT synthase holoenzyme in addition to its function in ATAC. We also show that sequence determinants that regulate MAPK signaling are located within the MoaE region of dMoaE (CG10238). Analysis of other metazoan MBIPs reveals that MBIP protein sequences have an N-terminal region that appears to have been derived from the MoaE protein, although it has lost residues responsible for catalytic activity. Thus, intact and modified copies of the MoaE protein may have been conscripted to play a new, noncatalytic role in MAPK signaling in Metazoa as part of the ATAC complex. PMID:22345504

  12. The Yeast ATF1 Acetyltransferase Efficiently Acetylates Insect Pheromone Alcohols: Implications for the Biological Production of Moth Pheromones.

    PubMed

    Ding, Bao-Jian; Lager, Ida; Bansal, Sunil; Durrett, Timothy P; Stymne, Sten; Löfstedt, Christer

    2016-04-01

    Many moth pheromones are composed of mixtures of acetates of long-chain (≥10 carbon) fatty alcohols. Moth pheromone precursors such as fatty acids and fatty alcohols can be produced in yeast by the heterologous expression of genes involved in insect pheromone production. Acetyltransferases that subsequently catalyze the formation of acetates by transfer of the acetate unit from acetyl-CoA to a fatty alcohol have been postulated in pheromone biosynthesis. However, so far no fatty alcohol acetyltransferases responsible for the production of straight chain alkyl acetate pheromone components in insects have been identified. In search for a non-insect acetyltransferase alternative, we expressed a plant-derived diacylglycerol acetyltransferase (EaDAcT) (EC 2.3.1.20) cloned from the seed of the burning bush (Euonymus alatus) in a yeast system. EaDAcT transformed various fatty alcohol insect pheromone precursors into acetates but we also found high background acetylation activities. Only one enzyme in yeast was shown to be responsible for the majority of that background activity, the acetyltransferase ATF1 (EC 2.3.1.84). We further investigated the usefulness of ATF1 for the conversion of moth pheromone alcohols into acetates in comparison with Ea DAcT. Overexpression of ATF1 revealed that it was capable of acetylating these fatty alcohols with chain lengths from 10 to 18 carbons with up to 27- and 10-fold higher in vivo and in vitro efficiency, respectively, compared to Ea DAcT. The ATF1 enzyme thus has the potential to serve as the missing enzyme in the reconstruction of the biosynthetic pathway of insect acetate pheromones from precursor fatty acids in yeast.

  13. Improved characterisation of exoplanets discovered in wide-field surveys: HAT-P-29b and HAT-P-31b

    NASA Astrophysics Data System (ADS)

    Rocchetto, M.; Fossey, S.

    2013-09-01

    In recent years a large population of exoplanets has been discovered thanks to ground-based surveys such as WASP and HATnet. These are typically relatively big planets in close orbits to their parent star that produce transit light curves with depths of up to a few percent which can be well observed using relatively smal-aperture ground-based telescopes. Due to the large number of planets discovered, systematic followup of most of these targets is often lacking. Moreover, in some discovery papers the characterisation of the planet is made with partial-transit follow-up light curves or relies entirely on the wide-field survey photometry, leading to relatively large uncertainties in the derived planetary parameters. We present followup photometry for two such cases, HAT-P-29b and HAT-P-31b, obtained with a 35-cm telescope based at UCL's University of London Observatory between 2011 and 2012. We find that our light curves are able to provide more accurate and/or precise parameters than those published. Follow-up observations are also important to monitor effects such as transit timing variations (TTVs), which can provide evidence for the presence of other planets in the system, and we explore the current limits on TTV detections for the two planets discussed here. The use of small-aperture telescopes provides an efficient and cost-effective way to improve the characterisation of known exoplanets, leading to an improvement in the statistical properties of these samples; and might also lead to the discovery of new exoplanets through TTV monitoring.

  14. Circadian clock controlling arylalkylamine N-acetyltransferase-like activity in the cricket (Gryllus bimaculatus) egg.

    PubMed

    Itoh, M T; Sumi, Y

    1998-07-13

    When cricket (Gryllus bimaculatus) eggs were incubated under a 12-h light/12-h dark (LD) cycle for 6 days after oviposition at 24-26 degrees C and thereafter transferred to constant darkness (DD), arylalkylamine N-acetyltransferase (NAT)-like activity fluctuated in a circadian manner, peaking during the subjective dark period, and the rhythmic activity persisted during the 3rd day of incubation in DD. When the eggs were transferred from LD to a lighting regime in which the light and dark periods were reversed, the rhythm of NAT-like activity continued to oscillate in phase with the light/dark cycle. These data demonstrate that the cricket egg (probably the embryo) contains a circadian clock controlling NAT-like activity, and that the circadian clock entrains to environmental light/dark cycles.

  15. 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.

  16. 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

  17. The histone acetyltransferase MOF activates hypothalamic polysialylation to prevent diet-induced obesity in mice

    PubMed Central

    Brenachot, Xavier; Rigault, Caroline; Nédélec, Emmanuelle; Laderrière, Amélie; Khanam, Tasneem; Gouazé, Alexandra; Chaudy, Sylvie; Lemoine, Aleth; Datiche, Frédérique; Gascuel, Jean; Pénicaud, Luc; Benani, Alexandre

    2014-01-01

    Overfeeding causes rapid synaptic remodeling in hypothalamus feeding circuits. Polysialylation of cell surface molecules is a key step in this neuronal rewiring and allows normalization of food intake. Here we examined the role of hypothalamic polysialylation in the long-term maintenance of body weight, and deciphered the molecular sequence underlying its nutritional regulation. We found that upon high fat diet (HFD), reduced hypothalamic polysialylation exacerbated the diet-induced obese phenotype in mice. Upon HFD, the histone acetyltransferase MOF was rapidly recruited on the St8sia4 polysialyltransferase-encoding gene. Mof silencing in the mediobasal hypothalamus of adult mice prevented activation of the St8sia4 gene transcription, reduced polysialylation, altered the acute homeostatic feeding response to HFD and increased the body weight gain. These findings indicate that impaired hypothalamic polysialylation contribute to the development of obesity, and establish a role for MOF in the brain control of energy balance. PMID:25161885

  18. 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

    2012-05-02

    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.

  19. The place of choline acetyltransferase activity measurement in the "cholinergic hypothesis" of neurodegenerative diseases.

    PubMed

    Contestabile, Antonio; Ciani, Elisabetta; Contestabile, Andrea

    2008-02-01

    The so-called "cholinergic hypothesis" assumes that degenerative dysfunction of the cholinergic system originating in the basal forebrain and innervating several cortical regions and the hippocampus, is related to memory impairment and neurodegeneration found in several forms of dementia and in brain aging. Biochemical methods measuring the activity of the key enzyme for acetylcholine synthesis, choline acetyltransferase, have been used for many years as a reliable marker of the integrity or the damage of the cholinergic pathways. Stereologic counting of the basal forebrain cholinergic cell bodies, has been additionally used to assess neurodegenerative changes of the forebrain cholinergic system. While initially believed to mark relatively early stages of disease, cholinergic dysfunction is at present considered to occur in advanced dementia of Alzheimer's type, while its involvement in mild and prodromal stages of the disease has been questioned. The issue is relevant to better understand the neuropathological basis of the diseases, but it is also of primary importance for therapy. During the last few years, indeed, cholinergic replacement therapies, mainly based on the use of acetylcholinesterase inhibitors to increase synaptic availability of acetylcholine, have been exploited on the assumption that they could ameliorate the progression of the dementia from its initial stages. In the present paper, we review data from human studies, as well as from animal models of Alzheimer's and Down's diseases, focusing on different ways to evaluate cholinergic dysfunction, also in relation to the time point at which these dysfunctions can be demonstrated, and on some discrepancy arising from the use of different methodological approaches. The reviewed literature, as well as some recent data from our laboratories on a mouse model of Down's syndrome, stress the importance of performing biochemical evaluation of choline acetyltransferase activity to assess cholinergic

  20. 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.

  1. 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

  2. Molecular Determinants of the N-Terminal Acetyltransferase Naa60 Anchoring to the Golgi Membrane.

    PubMed

    Aksnes, Henriette; Goris, Marianne; Strømland, Øyvind; Drazic, Adrian; Waheed, Qaiser; Reuter, Nathalie; Arnesen, Thomas

    2017-02-14

    Nα-acetyltransferase 60 (Naa60 or NatF) was recently identified as an unconventional N-terminal acetyltransferase (NAT) since it localizes to organelles, in particular the Golgi apparatus, and has a preference for acetylating N-termini of transmembrane proteins. This knowledge challenged the prevailing view of N-terminal acetylation as a co-translational ribosome-associated process and suggested a new mechanistic functioning for the enzymes responsible for this increasingly recognized protein modification. Crystallography studies on Naa60 were unable to resolve the C-terminal tail of Naa60, which is responsible for the organellar localization. Here, we combined modeling, in vitro assays, and cellular localization studies to study secondary structure and membrane interacting capacity of Naa60. The results show that Naa60 is a peripheral membrane protein. Two amphipathic helices within the Naa60 C-terminus bind the membrane directly in a parallel position relative to the lipid bilayer via hydrophobic and electrostatic interactions. A peptide corresponding to the C-terminus is unstructured in solution and only folds into an α-helical conformation in the presence of liposomes. Computational modeling and cellular mutational analysis revealed the hydrophobic face of two α-helices to be critical for membranous localization. Furthermore, we found a strong and specific binding preference of Naa60 towards membranes containing the phosphatidylinositol PI4P, thus possibly explaining the primary residency of Naa60 at the PI4P-rich Golgi. In conclusion, we have defined the mode of cytosolic Naa60 anchoring to the Golgi apparatus, most likely occurring post-translationally and specifically facilitating post-translational N-terminal acetylation of many transmembrane proteins.

  3. Ligand promiscuity through the eyes of the aminoglycoside N3 acetyltransferase IIa

    PubMed Central

    Norris, Adrianne L; Serpersu, Engin H

    2013-01-01

    Aminoglycoside-modifying enzymes (AGMEs) are expressed in many pathogenic bacteria and cause resistance to aminoglycoside (AG) antibiotics. Remarkably, the substrate promiscuity of AGMEs is quite variable. The molecular basis for such ligand promiscuity is largely unknown as there is not an obvious link between amino acid sequence or structure and the antibiotic profiles of AGMEs. To address this issue, this article presents the first kinetic and thermodynamic characterization of one of the least promiscuous AGMEs, the AG N3 acetyltransferase-IIa (AAC-IIa) and its comparison to two highly promiscuous AGMEs, the AG N3-acetyltransferase-IIIb (AAC-IIIb) and the AG phosphotransferase(3′)-IIIa (APH). Despite having similar antibiotic selectivities, AAC-IIIb and APH catalyze different reactions and share no homology to one another. AAC-IIa and AAC-IIIb catalyze the same reaction and are very similar in both amino acid sequence and structure. However, they demonstrate strong differences in their substrate profiles and kinetic and thermodynamic properties. AAC-IIa and APH are also polar opposites in terms of ligand promiscuity but share no sequence or apparent structural homology. However, they both are highly dynamic and may even contain disordered segments and both adopt well-defined conformations when AGs are bound. Contrary to this AAC-IIIb maintains a well-defined structure even in apo form. Data presented herein suggest that the antibiotic promiscuity of AGMEs may be determined neither by the flexibility of the protein nor the size of the active site cavity alone but strongly modulated or controlled by the effects of the cosubstrate on the dynamic and thermodynamic properties of the enzyme. PMID:23640799

  4. Structural and Functional Role of Acetyltransferase hMOF K274 Autoacetylation

    SciTech Connect

    McCullough, Cheryl E.; Song, Shufei; Shin, Michael H.; Johnson, F. Brad; Marmorstein, Ronen

    2016-07-05

    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.

  5. Specificity and versatility of substrate binding sites in four catalytic domains of human N-terminal acetyltransferases.

    PubMed

    Grauffel, Cédric; Abboud, Angèle; Liszczak, Glen; Marmorstein, Ronen; Arnesen, Thomas; Reuter, Nathalie

    2012-01-01

    Nt-acetylation is among the most common protein modifications in eukaryotes. Although thought for a long time to protect proteins from degradation, the role of Nt-acetylation is still debated. It is catalyzed by enzymes called N-terminal acetyltransferases (NATs). In eukaryotes, several NATs, composed of at least one catalytic domain, target different substrates based on their N-terminal sequences. In order to better understand the substrate specificity of human NATs, we investigated in silico the enzyme-substrate interactions in four catalytic subunits of human NATs (Naa10p, Naa20p, Naa30p and Naa50p). To date hNaa50p is the only human subunit for which X-ray structures are available. We used the structure of the ternary hNaa50p/AcCoA/MLG complex and a structural model of hNaa10p as a starting point for multiple molecular dynamics simulations of hNaa50p/AcCoA/substrate (substrate=MLG, EEE, MKG), hNaa10p/AcCoA/substrate (substrate=MLG, EEE). Nine alanine point-mutants of the hNaa50p/AcCoA/MLG complex were also simulated. Homology models of hNaa20p and hNaa30p were built and compared to hNaa50p and hNaa10p. The simulations of hNaa50p/AcCoA/MLG reproduce the interactions revealed by the X-ray data. We observed strong hydrogen bonds between MLG and tyrosines 31, 138 and 139. Yet the tyrosines interacting with the substrate's backbone suggest that their role in specificity is limited. This is confirmed by the simulations of hNaa50p/AcCoA/EEE and hNaa10p/AcCoA/MLG, where these hydrogen bonds are still observed. Moreover these tyrosines are all conserved in hNaa20p and hNaa30p. Other amino acids tune the specificity of the S1' sites that is different for hNaa10p (acidic), hNaa20p (hydrophobic/basic), hNaa30p (basic) and hNaa50p (hydrophobic). We also observe dynamic correlation between the ligand binding site and helix [Formula: see text] that tightens under substrate binding. Finally, by comparing the four structures we propose maps of the peptide-enzyme interactions

  6. 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

  7. 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

  8. 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

  9. HATS-1b: The First Transiting Planet Discovered by the HATSouth Survey

    NASA Astrophysics Data System (ADS)

    Penev, K.; Bakos, G. Á.; Bayliss, D.; Jordán, A.; Mohler, M.; Zhou, G.; Suc, V.; Rabus, M.; Hartman, J. D.; Mancini, L.; Béky, B.; Csubry, Z.; Buchhave, L.; Henning, T.; Nikolov, N.; Csák, B.; Brahm, R.; Espinoza, N.; Conroy, P.; Noyes, R. W.; Sasselov, D. D.; Schmidt, B.; Wright, D. J.; Tinney, C. G.; Addison, B. C.; Lázár, J.; Papp, I.; Sári, P.

    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 ≈ 3.4465 days, mass of Mp ≈ 1.86 M J, and radius of Rp ≈ 1.30 R J. The host star has a mass of 0.99 M ⊙ and radius of 1.04 R ⊙. 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. 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. Based in part on observations made with the Nordic Optical Telescope, operated on the island of La Palma in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. Based on observations made with the MPG/ESO 2.2 m Telescope at the ESO Observatory in La Silla. FEROS ID programmes: P087.A-9014(A), P088.A-9008(A), P089.A-9008(A), P087.C-0508(A). GROND ID programme: 089.A-9006(A). This paper uses observations obtained with facilities of the Las Cumbres Observatory Global Telescope.

  10. 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}⊙ and radius {1.020}-0.031+0.057 {R}⊙ ) 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.

  11. Refined System Parameters and TTV Study of Transiting Exoplanetary System HAT-P-20

    NASA Astrophysics Data System (ADS)

    Sun, Leilei; Gu, Shenghong; Wang, Xiaobin; Collier Cameron, Andrew; Cao, Dongtao; Wang, Yibo; Xiang, Yue; Hui, Ho-Keung; Kwok, Chi-Tai; Yeung, Bill; Ng, Eric; Grau Horta, Ferran

    2017-01-01

    We report new photometric observations of the transiting exoplanetary system HAT-P-20, obtained using CCD cameras at Yunnan Observatories and Ho Koon Nature Education cum Astronomical Centre, China, from 2010 to 2013, and Observatori Ca l’Ou, Sant Marti Sesgueioles, Spain, from 2013 to 2015. The observed data are corrected for systematic errors according to the coarse de-correlation and SYSREM algorithms, so as to enhance the signal of the transit events. In order to consistently model the star spots and transits of this exoplanetary system, we develop a highly efficient tool STMT based on the analytic models of Mandel & Agol and Montalto et al. The physical parameters of HAT-P-20 are refined by homogeneously analyzing our new data, the radial velocity data, and the earlier photometric data in the literature with the Markov chain Monte Carlo technique. New radii and masses of both host star and planet are larger than those in the discovery paper due to the discrepancy of the radius among K-dwarfs between predicted values by standard stellar models and empirical calibration from observations. Through the analysis of all available mid-transit times calculated with the normal model and spotted model, we conclude that the periodic transit timing variations in these transit events revealed by employing the normal model are probably induced by spot crossing events. From the analysis of the distribution of occulted spots by HAT-P-20b, we constrain the misaligned architecture between the planetary orbit and the spin of the host star.

  12. [The management of aortic root replacement using the Top-Hat/Gelweave composite graft].

    PubMed

    Imada, T; Morishige, N; Nonaka, K; Yamanaka, J

    2000-06-01

    Composite graft replacement of the aortic root has become a routine procedure for annuloaortic ectasia (AAE) and aortic valve insufficiency (AR) with aortic dissection and the results have improved. We treated six cases of aortic root reconstruction using the Carrel patch method in 1998. The Top-Hat/Gelweave Composite graft fit together well and the procedure is technically similar to standard valve replacement. Upon measuring the valve size a Gelweave graft 1 mm larger than the valve size should be selected. There were no incidence of hemorrhage or postoperative hemolysis. Further long-term follow-up is necessary.

  13. 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.

  14. 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

  15. Characterization of the serine acetyltransferase gene family of Vitis vinifera uncovers differences in regulation of OAS synthesis in woody plants.

    PubMed

    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.

  16. Nucleotide sequence and phylogeny of a chloramphenicol acetyltransferase encoded by the plasmid pSCS7 from Staphylococcus aureus.

    PubMed

    Schwarz, S; Cardoso, M

    1991-08-01

    The nucleotide sequence of the chloramphenicol acetyltransferase gene (cat) and its regulatory region, encoded by the plasmid pSCS7 from Staphylococcus aureus, was determined. The structural cat gene encoded a protein of 209 amino acids, which represented one monomer of the enzyme chloramphenicol acetyltransferase (CAT). Comparisons between the amino acid sequences of the pSCS7-encoded CAT from S. aureus and the previously sequenced CAT variants from S. aureus, Staphylococcus intermedius, Staphylococcus haemolyticus, Bacillus pumilis, Clostridium difficile, Clostridium perfringens, Escherichia coli, Shigella flexneri, and Proteus mirabilis were performed. An alignment of CAT amino acid sequences demonstrated the presence of 34 conserved amino acids among all CAT variants. These conserved residues were considered for their possible roles in the structure and function of CAT. On the basis of the alignment, a phylogenetic tree was constructed. It demonstrated relatively large evolutionary distances between the CAT variants of enteric bacteria, Clostridium, Bacillus, and Staphylococcus species.

  17. The Transit Light Curve Project. VII. The Not-So-Bloated Exoplanet HAT-P-1b

    NASA Astrophysics Data System (ADS)

    Winn, Joshua N.; Holman, Matthew J.; Bakos, Gaspar Á.; Pál, András; Johnson, John Asher; Williams, Peter K. G.; Shporer, Avi; Mazeh, Tsevi; Fernandez, José; Latham, David W.; Gillon, Michael

    2007-10-01

    We present photometry of the G0 star HAT-P-1 during six transits of its close-in giant planet, and we refine the estimates of the system parameters. Relative to Jupiter's properties, HAT-P-1b is 1.20 ± 0.05 times larger, and its surface gravity is 2.7 ± 0.2 times weaker. Although it remains the case that HAT-P-1b is among the least dense of the known sample of transiting exoplanets, its properties are in accord with previously published models of strongly irradiated, coreless, solar-composition giant planets. The times of the transits have a typical accuracy of 1 minute and do not depart significantly from a constant period.

  18. 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.

  19. Characterization of new hAT transposable elements in 12 Drosophila genomes.

    PubMed

    de Freitas Ortiz, Mauro; Loreto, Elgion Lucio Silva

    2009-01-01

    In silico searches for sequences homologous to hAT elements in 12 Drosophila genomes have allowed us to identify 37 new hAT elements (8 in D. ananassae, 11 in D. mojavensis, 2 in D. sechellia, 1 in D. simulans, 2 in D. virilis, 3 in D. yakuba, 3 in D. persimilis, 1 in D. grimshawi, 5 in D. willistoni and 1 in D. pseudobscura). The size of these elements varies from 2,359 to 4,962 bp and the terminal inverted repeats (TIRs) show lengths ranging from 10 to 24 bp. Several elements show intact transposase ORFs, suggesting that they are active. Conserved amino acid motifs were identified that correspond to those important for transposase activity. These elements are highly variable and phylogenetic analysis showed that they can be clustered into four different families. Incongruencies were observed between the phylogenies of the transposable elements and those of their hosts, suggesting that horizontal transfer may have occurred between some of the species.

  20. 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.

  1. The 'chef's hat' appearance of the femoral head in cleidocranial dysplasia.

    PubMed

    Aktas, S; Wheeler, D; Sussman, M D

    2000-04-01

    Cleidocranial dysplasia (CCD) is inherited as an autosomal dominant disorder characterised by failure of membranous ossification. The condition is due to a mutation of the cbfa1 gene on chromosome 6 which has a role in the development of osteoblasts from the mesenchymal cells. In their growing years, these patients have an unusual shape of the femoral head reminiscent of a 'chef's hat'. In order to confirm the consistency of this sign, we have reviewed the radiographs of 28 patients with CCD. All except three had this appearance. The sign was also seen in patients with coxa vara associated with a variety of other conditions. The chef's hat sign may occur secondary to the particular mechanical environment created by coxa vara as well as abnormal cellular function in patients with CCD. Although coxa vara has some influence on the shape of the femoral head, it is not entirely responsible for its morphology since it was present in only six of the 28 patients with CCD.

  2. 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.

  3. 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.

  4. 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.

  5. A Bayesian analysis of HAT-P-7b using the EXONEST algorithm

    NASA Astrophysics Data System (ADS)

    Placek, Ben; Knuth, Kevin H.

    2015-01-01

    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.

  6. 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.

  7. Free radical scavenger properties of α-mangostin: thermodynamics and kinetics of HAT and RAF mechanisms.

    PubMed

    Martínez, Ana; Galano, Annia; Vargas, Rubicelia

    2011-11-03

    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.

  8. 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.

  9. 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.

  10. 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}.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. Spontaneous breaking of chiral symmetry, and eventually of parity, in a σ-model with two Mexican hats

    NASA Astrophysics Data System (ADS)

    Giacosa, Francesco

    2010-02-01

    A σ-model with two linked Mexican hats is discussed. This scenario could be realized in low-energy QCD when the ground state and the first excited (pseudo)scalar mesons are included, and where not only in the subspace of the ground states, but also in that of the first excited states, a Mexican hat potential is present. This possibility can change some basic features of a low-energy hadronic theory of QCD. It is also shown that spontaneous breaking of parity can occur in the vacuum for some parameter choice of the model.

  20. 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.

  1. Solution of Newly Observed Transit of the Exoplanet Hat-P-24B:No TTV and TDV Signals

    NASA Astrophysics Data System (ADS)

    Kjurkchieva, Diana; Dimitrov, Dinko; Ibryamov, Sunay

    2016-01-01

    We present photometric observations of transit of the exoplanet HAT-P-24b using the Rozhen 2 m telescope. Its solution gives relative stellar radius r_s=0.1304 (a/R_s = 7.669), relative planet radius r_p=0.01304 and orbital inclination of 90°. The calculated planet radius is R_p = 1.316 R_J and corresponds to planet density of ρ_p = 0.37 g cm^{-3}. Our parameter values are between those of the previous two solutions. We did not find evidences of TTV and TDV signals of HAT-P-24b.

  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

    2014-10-06

    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. 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

  4. 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.

  5. 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.

  6. [Evaluation of a caffeine test for determining the phenotype of N-acetyltransferase].

    PubMed

    Gascon, M P; Leemann, T; Dayer, P

    1987-12-05

    Xenobiotic acetylation by N-acetyltransferase is genetically controlled. This polymorphism governs the intestinal and liver metabolism of numerous amines. The use of caffeine, a ubiquitous and nontoxic amine, has been proposed as a probe for phenotyping. The aim of the present study is to evaluate this test and to identify the metabolite of caffeine used as substrate by the polymorphic enzyme. - A cup of coffee, tea or Coca-Cola is administered to fasting subjects. The molar ratio of two metabolites of caffeine (AFMU and 1X) is determined on a spot urine sample 4-6 hours later by means of a UV liquid chromatographic assay. In a reference population (n = 63), the distribution of molar ratios is trimodal with frequencies of 0.14, 0.35 and 0.51. These results correlate with those obtained by the classic isoniazid test. However, in vitro experiments in human liver subcellular fractions did not lead to the identification of a xanthine as the precursor of the acetylated metabolite.

  7. Garcinol Inhibits GCN5-Mediated Lysine Acetyltransferase Activity and Prevents Replication of the Parasite Toxoplasma gondii

    PubMed Central

    Jeffers, Victoria; Gao, Hongyu; Checkley, Lisa A.; Liu, Yunlong; Ferdig, Michael T.

    2016-01-01

    Lysine acetylation is a critical posttranslational modification that influences protein activity, stability, and binding properties. The acetylation of histone proteins in particular is a well-characterized feature of gene expression regulation. In the protozoan parasite Toxoplasma gondii, a number of lysine acetyltransferases (KATs) contribute to gene expression and are essential for parasite viability. The natural product garcinol was recently reported to inhibit enzymatic activities of GCN5 and p300 family KATs in other species. Here we show that garcinol inhibits TgGCN5b, the only nuclear GCN5 family KAT known to be required for Toxoplasma tachyzoite replication. Treatment of tachyzoites with garcinol led to a reduction of global lysine acetylation, particularly on histone H3 and TgGCN5b itself. We also performed transcriptome sequencing (RNA-seq), which revealed increasing aberrant gene expression coincident with increasing concentrations of garcinol. The majority of the genes that were most significantly affected by garcinol were also associated with TgGCN5b in a previously reported chromatin immunoprecipitation assay with microarray technology (ChIP-chip) analysis. The dysregulated gene expression induced by garcinol significantly inhibits Toxoplasma tachyzoite replication, and the concentrations used exhibit no overt toxicity on human host cells. Garcinol also inhibits Plasmodium falciparum asexual replication with a 50% inhibitory concentration (IC50) similar to that for Toxoplasma. Together, these data support that pharmacological inhibition of TgGCN5b leads to a catastrophic failure in gene expression control that prevents parasite replication. PMID:26810649

  8. The acetyltransferase Tip60 contributes to mammary tumorigenesis by modulating DNA repair

    PubMed Central

    Bassi, C; Li, Y-T; Khu, K; Mateo, F; Baniasadi, P S; Elia, A; Mason, J; Stambolic, V; Pujana, M A; Mak, T W; Gorrini, C

    2016-01-01

    The acetyltransferase Tip60/Kat5 acetylates both histone and non-histone proteins, and is involved in a variety of biological processes. By acetylating p53, Tip60 controls p53-dependent transcriptional activity and so is implicated as a tumor suppressor. However, many breast cancers with low Tip60 also show p53 mutation, implying that Tip60 has a tumor suppressor function independent of its acetylation of p53. Here, we show in a p53-null mouse model of sporadic invasive breast adenocarcinoma that heterozygosity for Tip60 deletion promotes mammary tumorigenesis. Low Tip60 reduces DNA repair in normal and tumor mammary epithelial cells, both under resting conditions and following genotoxic stress. We demonstrate that Tip60 controls homologous recombination (HR)-directed DNA repair, and that Tip60 levels correlate inversely with a gene expression signature associated with defective HR-directed DNA repair. In human breast cancer data sets, Tip60 mRNA is downregulated, with low Tip60 levels correlating with p53 mutations in basal-like breast cancers. Our findings indicate that Tip60 is a novel breast tumor suppressor gene whose loss results in genomic instability leading to cancer formation. PMID:26915295

  9. Polyamine regulation of heat-shock-induced spermidine N1-acetyltransferase activity.

    PubMed Central

    Fuller, D J; Carper, S W; Clay, L; Chen, J R; Gerner, E W

    1990-01-01

    The enzyme spermidine/spermine N1-acetyltransferase (N1-SAT) is rapidly induced by heat shock in CHO and A549 cells, with activity declining by 24 h. Depletion of intracellular polyamines by alpha-difluoromethylornithine, an inhibitor of ornithine decarboxylase, blocks this induction. Re-addition of putrescine to these cultures restores the response to heat shock, with a concomitant increase in intracellular N1-acetylspermidine. Diaminopropane is more than twice as effective as the naturally occurring diamine putrescine, suggesting that the propylamine moiety of spermidine is involved in the regulation of N1-SAT induction. Inhibitor studies indicate transcriptional activation and that the enzyme has an apparent half-life of 30-60 min. A second heat shock rapidly inhibits induced N1-SAT activity, which decays with a half-life of 2-3 min. Despite its induction by heat, N1-SAT is not a stable enzyme, suggesting that the activity observed is not due to a modification of an existing peptide, but is due to a transcriptional event, which may justify the inclusion of this enzyme in the family of heat-shock proteins. Images Fig. 2. PMID:2111132

  10. 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

  11. Novel ligands of Choline Acetyltransferase designed by in silico molecular docking, hologram QSAR and lead optimization

    NASA Astrophysics Data System (ADS)

    Kumar, Rajnish; Långström, Bengt; Darreh-Shori, Taher

    2016-08-01

    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.

  12. Contribution of gentamicin 2'-N-acetyltransferase to the O acetylation of peptidoglycan in Providencia stuartii.

    PubMed

    Payie, K G; Rather, P N; Clarke, A J

    1995-08-01

    A collection of Providencia stuartii mutants which either underexpress or overexpress aac(2')-Ia, the chromosomal gene coding for gentamicin 2'-N-acetyltransferase (EC 2.3.1.59), have been characterized phenotypically as possessing either lower or higher levels of peptidoglycan O acetylation, respectively, than the wild type. These mutants were subjected to both negative-staining and thin-section electron microscopy. P. stuartii PR100, with 42% O acetylation of peptidoglycan compared with 52% O acetylation in the wild type, appeared as irregular rods. In direct contrast, P. stuartii strains PR50.LM3 and PR51, with increased levels of peptidoglycan O acetylation (65 and 63%, respectively), appeared as coccobacilli and chain formers, respectively. Membrane blebbing was also observed with the chain-forming strain PR51. Thin sectioning of this mutant indicated that it was capable of proper constriction and separation. P. stuartii PM1, when grown to mid-exponential phase, did not have altered peptidoglycan O-acetylation levels, and cellular morphology remained similar to that of wild-type strains. However, continued growth into stationary phase resulted in a 15% increase in peptidoglycan O acetylation concomitant with a change of some cells from a rod-shaped to a coccobacillus-shaped morphology. The fact that these apparent morphological changes were directly related to levels of O acetylation support the view that this modification plays a role in the maintenance of peptidoglycan structure, presumably through the control of autolytic activity.

  13. 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

  14. The Lysine Acetyltransferase Activator Brpf1 Governs Dentate Gyrus Development through Neural Stem Cells and Progenitors

    PubMed Central

    You, Linya; Yan, Kezhi; Zhou, Jinfeng; Zhao, Hong; Bertos, Nicholas R.; Park, Morag; Wang, Edwin; Yang, Xiang-Jiao

    2015-01-01

    Lysine acetylation has recently emerged as an important post-translational modification in diverse organisms, but relatively little is known about its roles in mammalian development and stem cells. Bromodomain- and PHD finger-containing protein 1 (BRPF1) is a multidomain histone binder and a master activator of three lysine acetyltransferases, MOZ, MORF and HBO1, which are also known as KAT6A, KAT6B and KAT7, respectively. While the MOZ and MORF genes are rearranged in leukemia, the MORF gene is also mutated in prostate and other cancers and in four genetic disorders with intellectual disability. Here we show that forebrain-specific inactivation of the mouse Brpf1 gene causes hypoplasia in the dentate gyrus, including underdevelopment of the suprapyramidal blade and complete loss of the infrapyramidal blade. We trace the developmental origin to compromised Sox2+ neural stem cells and Tbr2+ intermediate neuronal progenitors. We further demonstrate that Brpf1 loss deregulates neuronal migration, cell cycle progression and transcriptional control, thereby causing abnormal morphogenesis of the hippocampus. These results link histone binding and acetylation control to hippocampus development and identify an important epigenetic regulator for patterning the dentate gyrus, a brain structure critical for learning, memory and adult neurogenesis. PMID:25757017

  15. DNA damage induces N-acetyltransferase NAT10 gene expression through transcriptional activation.

    PubMed

    Liu, Haijing; Ling, Yun; Gong, Yilei; Sun, Ying; Hou, Lin; Zhang, Bo

    2007-06-01

    NAT10 (N-acetyltransferase 10) is a protein with histone acetylation activity and primarily identified to be involved in regulation of telomerase activity. The presented research shows its transcriptional activation by genotoxic agents and possible role in DNA damage. NAT10 mRNA could be markedly increased by using hydrogen peroxide (H2O2) or cisplatin in a dose- and time-dependent way, and the immunofluorescent staining revealed that the treatment of H2O2 or cisplatin induced focal accumulation of NAT10 protein in cellular nuclei. Both H2O2 and cisplatin could stimulate the transcriptional activity of the NAT10 promoter through the upstream sequences from -615 bp to +110 bp, with which some nuclear proteins interacted. Ectopic expression of NAT10 could enhance the number of survival cells in the presence of H2O2 or cisplatin. The above results suggested that NAT10 could be involved in DNA damage response and increased cellular resistance to genotoxicity.

  16. 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.

  17. 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.

  18. Application of the chloramphenicol acetyltransferase (CAT) diffusion assay to transgenic plant tissues.

    PubMed

    Peach, C; Velten, J

    1992-02-01

    Chloramphenicol acetyltransferase (CAT) activity was quantified in crude extracts from tobacco callus tissues using a modification of a previously reported diffusion assay. We describe here the alterations necessary in applying this rapid and simple assay procedure to plant materials. Due to the high concentration of nonspecific oxidases present in most plant tissues, some type of protective agent is required to maintain enzyme activity. We have tested beta-mercaptoethanol, cysteine, dithiothreitol, ascorbic acid and polyvinyl pyrrolidone as protective agents within the initial extraction buffer. We also investigated the effect of heat (60 degrees C, 10 min) and 5 mM EDTA on CAT activity. The highest CAT activity was obtained using 5 mM cysteine plus 5 mM EDTA in 40 mM Tris-HCl (pH 7.8) as the initial extraction buffer followed by a heat treatment. Using this buffer, CAT activity was stable on ice for more than two hours. In our hands, total acetyl-coenzyme A concentration within the assay mixture was found to be saturating at 250 microM and the Km determined to be 100 microM. Assays performed using the same crude plant extract indicate that 1) duplicate assays show less than 1.5% variation in activities and 2) CAT activity increases linearly with respect to volume of extract used.

  19. Molecular Basis of Substrate Specific Acetylation by N-Terminal Acetyltransferase NatB.

    PubMed

    Hong, Haiyan; Cai, Yongfei; Zhang, Shijun; Ding, Hongyan; Wang, Haitao; Han, Aidong

    2017-04-04

    The NatB N-terminal acetyltransferase specifically acetylates the N-terminal group of substrate protein peptides starting with Met-Asp/Glu/Asn/Gln. How NatB recognizes and acetylates these substrates remains unknown. Here, we report crystal structures of a NatB holoenzyme from Candida albicans in the presence of its co-factor CoA and substrate peptides. The auxiliary subunit Naa25 of NatB forms a horseshoe-like deck to hold specifically its catalytic subunit Naa20. The first two amino acids Met and Asp of a substrate peptide mediate the major interactions with the active site in the Naa20 subunit. The hydrogen bonds between the substrate Asp and pocket residues of Naa20 are essential to determine the NatB substrate specificity. Moreover, a hydrogen bond between the amino group of the substrate Met and a carbonyl group in the Naa20 active site directly anchors the substrate toward acetyl-CoA. Together, these structures define a unique molecular mechanism of specific N-terminal acetylation acted by NatB.

  20. Overexpression of the chromosomally encoded aminoglycoside acetyltransferase eis confers kanamycin resistance in Mycobacterium tuberculosis.

    PubMed

    Zaunbrecher, M Analise; Sikes, R David; Metchock, Beverly; Shinnick, Thomas M; Posey, James E

    2009-11-24

    The emergence of multidrug-resistant (MDR) tuberculosis (TB) highlights the urgent need to understand the mechanisms of resistance to the drugs used to treat this disease. The aminoglycosides kanamycin and amikacin are important bactericidal drugs used to treat MDR TB, and resistance to one or both of these drugs is a defining characteristic of extensively drug-resistant TB. We identified mutations in the -10 and -35 promoter region of the eis gene, which encodes a previously uncharacterized aminoglycoside acetyltransferase. These mutations led to a 20-180-fold increase in the amount of eis leaderless mRNA transcript, with a corresponding increase in protein expression. Importantly, these promoter mutations conferred resistance to kanamycin [5 microg/mL < minimum inhibitory concentration (MIC)

  1. Polyamine-Regulated Translation of Spermidine/Spermine-N1-Acetyltransferase

    PubMed Central

    Perez-Leal, Oscar; Barrero, Carlos A.; Clarkson, Allen B.; Casero, Robert A.

    2012-01-01

    Rapid synthesis of the polyamine catabolic enzyme spermidine/spermine-N1-acetyltransferase (SSAT) in response to increased polyamines is an important polyamine homeostatic mechanism. Indirect evidence has suggested that there is an important control mechanism involving the release of a translational repressor protein that allows the immediate initiation of SSAT protein synthesis without RNA transcription, maturation, or translocation. To identify a repressor protein, we used a mass spectroscopy-based RNA-protein interaction system and found six proteins that bind to the coding region of SSAT mRNA. Individual small interfering RNA (siRNA) experiments showed that nucleolin knockdown enhances SSAT translation. Nucleolin exists in several isoforms, and we report that the isoform that binds to SSAT mRNA undergoes autocatalysis in the presence of polyamines, a result suggesting that there is a negative feedback system that helps control the cellular content of polyamines. Preliminary molecular interaction data show that a nucleolin isoform binds to a 5′ stem-loop of the coding region of SSAT mRNA. The glycine/arginine-rich C terminus of nucleolin is required for binding, and the four RNA recognition motif domains are included in the isoform that blocks SSAT translation. Understanding SSAT translational control mechanisms has the potential for the development of therapeutic strategies against cancer and obesity. PMID:22354986

  2. 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

  3. 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

  4. Cloning and characterization of a serotonin N-acetyltransferase from a gymnosperm, loblolly pine (Pinus taeda).

    PubMed

    Park, Sangkyu; Byeon, Yeong; Lee, Hyoung Yool; Kim, Young-Soon; Ahn, Taeho; Back, Kyoungwhan

    2014-10-01

    Serotonin N-acetyltransferase (SNAT) is the penultimate enzyme in melatonin biosynthesis in both animals and plants. SNAT catalyzes serotonin into N-acetylserotonin, an immediate precursor for melatonin biosynthesis by N-acetylserotonin methyltransferase (ASMT). We cloned the SNAT gene from a gymnosperm loblolly pine (Pinus teada). The loblolly pine SNAT (PtSNAT) gene encodes 255 amino acids harboring a transit sequence with 67 amino acids and shows 67% amino acid identity with rice SNAT when comparing the mature polypeptide regions. Purified recombinant PtSNAT showed peak activity at 55°C with the K(m) (428 μM) and Vmax (3.9 nmol/min/mg protein) values. As predicted, PtSNAT localized to chloroplasts. The SNAT mRNA was constitutively expressed in all tissues, including leaf, bud, flower, and pinecone, whereas the corresponding protein was detected only in leaf. In accordance with the exclusive SNAT protein expression in leaf, melatonin was detected only in leaf at 0.45 ng per gram fresh weight. Sequence and phylogenetic analysis indicated that the gymnosperm PtSNAT had high homology with SNATs from all plant phyla (even with cyanobacteria), and formed a clade separated from the angiosperm SNATs, suggestive of direct gene transfer from cyanobacteria via endosymbiosis.

  5. Effect of undernutrition on the regional development of transmitter enzymes: glutamate decarboxylase and choline acetyltransferase.

    PubMed

    Patel, A J; del Vecchio, M; Atkinson, D J

    1978-01-01

    The effect of undernutrition on the activity of glutamate decarboxylase (GAD) and choline acetyltransferase (ChAc) (markers for the GABA-ergic and the cholinergic transmitter system, respectively) was studied in various parts of the rat brain at the age of 10, 15 and 21 days, and at day 54 following 33 days of rehabilitation. The brain regions investigated were the olfactory bulbs, cerebellum, pons-medulla, hypothalamus, colliculi, cerebral cortex hippocampus and the residual brain. Undernutrition resulted in a marked retardation of the developmental rise of the activities of both enzymes, expressed in terms of either total brain part or unit weight or protein. The effect diminished with age even during the period of nutritional deprivation. In most brain regions the enzyme activities were restored to normal after rehabilitation. In the cerebral cortex the total activity of both enzymes was persistently reduced, although the concentration of GAD exceeded the control levels. A negative correlation was manifested between the activities of GAD and ChAc in the different brain parts (except the cerebellum) during development. The correlation became significant by day 21 in the controls, but only after postweaning rehabilitation of the undernourished rats. The results showed therefore that undernutrition caused a reversible retardation in the development of these two transmitter enzymes, and they suggested that even the balance of the GABA-ergic and cholinergic systems throughout the brain can be restored to normal by rehabilitation.

  6. Characterizing the Covalent Targets of a Small Molecule Inhibitor of the Lysine Acetyltransferase P300

    PubMed Central

    2015-01-01

    C646 inhibits the lysine acetyltransferases (KATs) p300 and CBP and represents the most potent and selective small molecule KAT inhibitor identified to date. To gain insights into the cellular activity of this epigenetic probe, we applied chemoproteomics to identify covalent targets of the C646 chemotype. Modeling and synthetic derivatization was used to develop a clickable analogue (C646-yne) that inhibits p300 similarly to the parent compound and enables enrichment of bound proteins. LC–MS/MS identified the major covalent targets of C646-yne as highly abundant cysteine-containing proteins, and follow-up studies found that C646 can inhibit tubulin polymerization in vitro. Finally, we provide evidence that thiol reactivity of C646 may limit its ability to antagonize acetylation in cells. These findings should enable a more precise interpretation of studies utilizing C646 as a chemical probe of KAT activity and suggest that an underappreciated liability of electrophile-containing inhibitors is a reduction in their cellular potency due to consumption by abundant protein and metabolite thiol sinks. PMID:26985290

  7. Schizosaccharomyces pombe mst2+ Encodes a MYST Family Histone Acetyltransferase That Negatively Regulates Telomere Silencing†

    PubMed Central

    Gómez, Eliana B.; Espinosa, Joaquín M.; Forsburg, Susan L.

    2005-01-01

    Histone acetylation and deacetylation are associated with transcriptional activity and the formation of constitutively silent heterochromatin. Increasingly, histone acetylation is also implicated in other chromosome transactions, including replication and segregation. We have cloned the only Schizosaccharomyces pombe MYST family histone acetyltransferase genes, mst1+ and mst2+. Mst1p, but not Mst2p, is essential for viability. Both proteins are localized to the nucleus and bound to chromatin throughout the cell cycle. Δmst2 genetically interacts with mutants that affect heterochromatin, cohesion, and telomere structure. Mst2p is a negative regulator of silencing at the telomere but does not affect silencing in the centromere or mating type region. We generated a census of proteins and histone modifications at wild-type telomeres. A histone acetylation gradient at the telomeres is lost in Δmst2 cells without affecting the distribution of Taz1p, Swi6p, Rad21p, or Sir2p. We propose that the increased telomeric silencing is caused by histone hypoacetylation and/or an increase in the ratio of methylated to acetylated histones. Although telomere length is normal, meiosis is aberrant in Δmst2 diploid homozygote mutants, suggesting that telomeric histone acetylation contributes to normal meiotic progression. PMID:16199868

  8. 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

    2014-06-01

    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.

  9. A series of shuttle vectors using chloramphenicol acetyltransferase as a reporter enzyme in yeast.

    PubMed

    Mannhaupt, G; Pilz, U; Feldmann, H

    1988-07-30

    Reports from numerous laboratories have shown that the gene coding for the bacterial enzyme chloramphenicol-3-O-acetyltransferase can be used as a reporter gene (cat) in mammalian and plant systems to analyze gene activity at the transcriptional level when combined with endogenous regulatory signals; the enzyme activity can be quantified by a chromatographic or a photometric assay. To adapt this simple and highly sensitive test for the yeast system, we constructed a series of yeast vectors containing the cat gene together with selectable markers for Escherichia coli and yeast; integrating, autonomously replicating and centromere-carrying plasmids were used. We show that the cat gene lacking the endogenous promoter is expressed at low levels in yeast transformants. To demonstrate functional expression of the cat gene placed under the control of a yeast promoter, we chose the PHO5 regulatory region. We found that cat expression was induced via the PHO5 promoter in a manner as observed for the endogenous PHO5 gene, whereas in the repressed state cat expression remained low. Using these vectors, it should be feasible to analyze other sequences conferring promoter activity or other control functions in yeast.

  10. 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.

  11. Variation of the N-acetyltransferase 2 gene in a Romanian and a Kyrgyz population.

    PubMed

    Rabstein, Sylvia; Unfried, Klaus; Ranft, Ulrich; Illig, Thomas; Kolz, Melanie; Rihs, Hans-Peter; Mambetova, Chinara; Vlad, Mariana; Brüning, Thomas; Pesch, Beate

    2006-01-01

    As part of a project on environmental disasters in minority populations, this study aimed to evaluate differences in the sequence of N-acetyltransferase 2 (NAT2) as a metabolic susceptibility gene in yet unexplored ethnicities. Eight single nucleotide polymorphisms (SNP) in the NAT2 coding region and a variant in the 3' flanking region were analyzed in 290 unrelated Kyrgyz and 140 unrelated Romanians by SNP-specific PCR analysis. The variants 341C, 481T, and 803G were less and 857A more prevalent in Kyrgyz (P < 0.0001). The variant at site 857 indicates Asian descent. 282C>T and 590G>A showed no significant variation by ethnicity. 364G>A and 411A>T turned out to be monomorphic. Database comparisons of the NAT2 minor allele frequencies support that Romanians belong to Caucasians and Kyrgyz are in between Caucasians and East Asians. The distributions of predicted haplotypes differed significantly between the two ethnicities where the Kyrgyz showed a higher genetic diversity. The haplotype without mutations was more common in Kyrgyz (40.1% in Kyrgyz, 29.3% in Romanians). Accordingly, the imputed slow acetylator phenotype was less prevalent in Kyrgyz (35.2% versus 51.4% in Romanians). We found pronounced ethnic differences in NAT2 genotypes with yet unknown effect on the health risks for environmental or occupational exposures in minority populations.

  12. The Histone Acetyltransferase MOF Promotes Induces Generation of Pluripotent Stem Cells.

    PubMed

    Mu, Xupeng; Yan, Shaohua; Fu, Changhao; Wei, Anhui

    2015-08-01

    Histone modification plays an important role in maintaining pluripotency and self-renewal of embryonic stem cells (ESCs). The histone acetyltransferase MOF is a key regulator of ESCs; however, the role of MOF in the process of reprogramming back to induced pluripotent stem cells (iPSCs) remains unclear. In this study, we investigated the function of MOF on the generation of iPSCs. We show that iPSCs contain high levels of MOF mRNA, and the expression level of MOF protein is dramatically upregulated following reprogramming. Most importantly, overexpression of MOF improves reprogramming efficiency and facilitates the formation of iPSCs, whereas small hairpin RNA (shRNA)-mediated knockdown of MOF impairs iPSCs generation during reprogramming. Further investigation reveals that MOF interacts with the H3K4 methyltransferase Wdr5 to promote endogenous Oct4 expression during the reprogramming process. Knockdown of MOF reduces H4K16ac and H3K4me3 modification at the Oct4 promoter. In conclusion, our data indicate that MOF is an important epigenetic regulator that is critical for efficient reprogramming.

  13. Muscle-specific Deletion of Carnitine Acetyltransferase Compromises Glucose Tolerance and Metabolic Flexibility

    PubMed Central

    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.

    2012-01-01

    Summary 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

  14. 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

  15. 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

  16. Interaction with a kinesin-2 tail propels choline acetyltransferase flow towards synapse.

    PubMed

    Sadananda, Aparna; Hamid, Runa; Doodhi, Harinath; Ghosal, Debnath; Girotra, Mukul; Jana, Swadhin Chandra; Ray, Krishanu

    2012-07-01

    Bulk flow constitutes a substantial part of the slow transport of soluble proteins in axons. Though the underlying mechanism is unclear, evidences indicate that intermittent, kinesin-based movement of large protein-aggregates aids this process. Choline acetyltransferase (ChAT), a soluble enzyme catalyzing acetylcholine synthesis, propagates toward the synapse at an intermediate, slow rate. The presynaptic enrichment of ChAT requires heterotrimeric kinesin-2, comprising KLP64D, KLP68D and DmKAP, in Drosophila. Here, we show that the bulk flow of a recombinant Green Fluorescent Protein-tagged ChAT (GFP::ChAT), in Drosophila axons, lacks particulate features. It occurs for a brief period during the larval stages. In addition, both the endogenous ChAT and GFP::ChAT directly bind to the KLP64D tail, which is essential for the GFP::ChAT entry and anterograde flow in axon. These evidences suggest that a direct interaction with motor proteins could regulate the bulk flow of soluble proteins, and thus establish their asymmetric distribution.

  17. Identification of arylamine N-acetyltransferase inhibitors as an approach towards novel anti-tuberculars.

    PubMed

    Westwood, Isaac M; Bhakta, Sanjib; Russell, Angela J; Fullam, Elizabeth; Anderton, Matthew C; Kawamura, Akane; Mulvaney, Andrew W; Vickers, Richard J; Bhowruth, Veemal; Besra, Gurdyal S; Lalvani, Ajit; Davies, Stephen G; Sim, Edith

    2010-01-01

    New anti-tubercular drugs and drug targets are urgently needed to reduce the time for treatment and also to identify agents that will be effective against Mycobacterium tuberculosis persisting intracellularly. Mycobacteria have a unique cell wall. Deletion of the gene for arylamine N-acetyltransferase (NAT) decreases mycobacterial cell wall lipids, particularly the distinctive mycolates, and also increases antibiotic susceptibility and killing within macrophage of Mycobacterium bovis BCG. The nat gene and its associated gene cluster are almost identical in sequence in M. bovis BCG and M. tuberculosis. The gene cluster is essential for intracellular survival of mycobacteria. We have therefore used pure NAT protein for high-throughput screening to identify several classes of small molecules that inhibit NAT activity. Here, we characterize one class of such molecules-triazoles-in relation to its effects on the target enzyme and on both M. bovis BCG and M. tuberculosis. The most potent triazole mimics the effects of deletion of the nat gene on growth, lipid disruption and intracellular survival. We also present the structure-activity relationship between NAT inhibition and effects on mycobacterial growth, and use ligand-protein analysis to give further insight into the structure-activity relationships. We conclude that screening a chemical library with NAT protein yields compounds that have high potential as anti-tubercular agents and that the inhibitors will allow further exploration of the biochemical pathway in which NAT is involved.

  18. Role of Saccharomyces cerevisiae serine O-acetyltransferase in cysteine biosynthesis.

    PubMed

    Takagi, Hiroshi; Yoshioka, Kenji; Awano, Naoki; Nakamori, Shigeru; Ono, Bun ichiro

    2003-01-28

    Some strains of Saccharomyces cerevisiae have detectable activities of L-serine O-acetyltransferase (SATase) and O-acetyl-L-serine/O-acetyl-L-homoserine sulfhydrylase (OAS/OAH-SHLase), but synthesize L-cysteine exclusively via cystathionine by cystathionine beta-synthase and cystathionine gamma-lyase. To untangle this peculiar feature in sulfur metabolism, we introduced Escherichia coli genes encoding SATase and OAS-SHLase into S. cerevisiae L-cysteine auxotrophs. While the cells expressing SATase grew on medium lacking L-cysteine, those expressing OAS-SHLase did not grow at all. The cells expressing both enzymes grew very well without L-cysteine. These results indicate that S. cerevisiae SATase cannot support L-cysteine biosynthesis and that S. cerevisiae OAS/OAH-SHLase produces L-cysteine if enough OAS is provided by E. coli SATase. It appears as if S. cerevisiae SATase does not possess a metabolic role in vivo either because of very low activity or localization. For example, S. cerevisiae SATase may be localized in the nucleus, thus controlling the level of OAS required for regulation of sulfate assimilation, but playing no role in the direct synthesis of L-cysteine.

  19. 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.

  20. Arylamine N-acetyltransferase activity in bronchial epithelial cells and its inhibition by cellular oxidants

    SciTech Connect

    Dairou, Julien; Petit, Emile; Ragunathan, Nilusha; Baeza-Squiban, Armelle; Marano, Francelyne; Dupret, Jean-Marie; Rodrigues-Lima, Fernando

    2009-05-01

    Bronchial epithelial cells express xenobiotic-metabolizing enzymes (XMEs) that are involved in the biotransformation of inhaled toxic compounds. The activities of these XMEs in the lung may modulate respiratory toxicity and have been linked to several diseases of the airways. Arylamine N-acetyltransferases (NAT) are conjugating XMEs that play a key role in the biotransformation of aromatic amine pollutants such as the tobacco-smoke carcinogens 4-aminobiphenyl (4-ABP) and {beta}-naphthylamine ({beta}-NA). We show here that functional human NAT1 or its murine counterpart Nat2 are present in different lung epithelial cells i.e. Clara cells, type II alveolar cells and bronchial epithelial cells, thus indicating that inhaled aromatic amines may undergo NAT-dependent biotransformation in lung epithelium. Exposure of these cells to pathophysiologically relevant amounts of oxidants known to contribute to lung dysfunction, such as H{sub 2}O{sub 2} or peroxynitrite, was found to impair the NAT1/Nat2-dependent cellular biotransformation of aromatic amines. Genetic and non genetic impairment of intracellular NAT enzyme activities has been suggested to compromise the important detoxification pathway of aromatic amine N-acetylation and subsequently to contribute to an exacerbation of untoward effects of these pollutants on health. Our study suggests that oxidative/nitroxidative stress in lung epithelial cells, due to air pollution and/or inflammation, could contribute to local and/or systemic dysfunctions through the alteration of the functions of pulmonary NAT enzymes.

  1. Crystallization and preliminary X-ray analysis of maltose O-acetyltransferase.

    PubMed

    Lo Leggio, L; Dal Degan, F; Poulsen, P; Sørensen, S O; Harlow, K; Harris, P; Larsen, S

    2001-12-01

    Maltose O-acetyltransferase (Mac) is a member of the hexapeptide-repeat family of enzymes, which contains proteins with left-handed parallel beta-helix architecture forming homotrimers. Diffraction data for four well diffracting crystal forms were collected. Crystal form I diffracted beyond 1.53 A resolution but was perfectly merohedrally twinned with an apparent space group P622. Crystal forms II and III (space groups R3 and C2, respectively) could be obtained under very similar conditions by adjusting the buffer pH differently. Crystal forms II and III had several monomers in the asymmetric unit and were difficult to derivatize. However, during soaking with trimethyl lead acetate, the form III crystals dissolved and crystals with a different habit and space group grew in their place (form IV). In three of the crystal forms, a ladder of peaks was visible in the native Patterson maps along the c axis. These peaks were interpreted as corresponding to the vectors between the beta-strands in the turns of the beta-helix. Crystal form IV is suitable for structure determination of Mac exploiting the anomalous scattering of lead.

  2. N-Acetyltransferase Mpr1 confers ethanol tolerance on Saccharomyces cerevisiae by reducing reactive oxygen species.

    PubMed

    Du, Xiaoyi; Takagi, Hiroshi

    2007-07-01

    N-Acetyltransferase Mpr1 of Saccharomyces cerevisiae can reduce intracellular oxidation levels and protect yeast cells under oxidative stress, including H(2)O(2), heat-shock, or freeze-thaw treatment. Unlike many antioxidant enzyme genes induced in response to oxidative stress, the MPR1 gene seems to be constitutively expressed in yeast cells. Based on a recent report that ethanol toxicity is correlated with the production of reactive oxygen species (ROS), we examined here the role of Mpr1 under ethanol stress conditions. The null mutant of the MPR1 and MPR2 genes showed hypersensitivity to ethanol stress, and the expression of the MPR1 gene conferred stress tolerance. We also found that yeast cells exhibited increased ROS levels during exposure to ethanol stress, and that Mpr1 protects yeast cells from ethanol stress by reducing intracellular ROS levels. When the MPR1 gene was overexpressed in antioxidant enzyme-deficient mutants, increased resistance to H(2)O(2) or heat shock was observed in cells lacking the CTA1, CTT1, or GPX1 gene encoding catalase A, catalase T, or glutathione peroxidase, respectively. These results suggest that Mpr1 might compensate the function of enzymes that detoxify H(2)O(2). Hence, Mpr1 has promising potential for the breeding of novel ethanol-tolerant yeast strains.

  3. In vitro inhibition of choline acetyltransferase by a series of 2-benzylidene-3-quinuclidinones

    SciTech Connect

    Capacio, B.R.

    1988-01-01

    Ten substituted 2-benzylidene-3-quinuclidinones were synthesized and evaluated for their relative potency as in vitro inhibitors of choline acetyltransferase (ChAT). Acetylcholine (ACh) synthesis was followed radiometrically by the incorporation of labeled acetate originating from {sup 14}C-acetyl-CoA. Woolf-Augustinsson-Hofstee data analysis was used to calculate Vmax, Km, and Ki values. The inhibition was found to be noncompetitive or uncompetitive with respect to choline. Quantitative structure activity relationship correlations demonstrated a primary dependence on {kappa}-{sigma}, as well as steric properties of the substituted benzene ring. Additional radiometric and spectrophotometric were performed with 2-(3{prime}-methyl)-benzylidene-3-quinuclidinone, one of the more potent analogs, to further elucidate the inhibitory mechanism. ChAT-mediated cleavage of ACh was measured spectrophotometrically by following the appearance of NADH at 340 nanometers in an enzyme coupled assay. Lineweaver-Burk analysis indicated mixed or uncompetitive inhibition with respect to both substrates of the forward reaction, suggesting interference with a rate limiting step.

  4. Structural model of carnitine palmitoyltransferase I based on the carnitine acetyltransferase crystal.

    PubMed Central

    Morillas, Montserrat; López-VViñas, Eduardo; Valencia, Alfonso; Serra, Dolors; Gómez-Puertas, Paulino; Hegardt, Fausto G; Asins, Guillermina

    2004-01-01

    CPT I (carnitine palmitoyltransferase I) catalyses the conversion of palmitoyl-CoA into palmitoylcarnitine in the presence of L-carnitine, facilitating the entry of fatty acids into mitochondria. We propose a 3-D (three-dimensional) structural model for L-CPT I (liver CPT I), based on the similarity of this enzyme to the recently crystallized mouse carnitine acetyltransferase. The model includes 607 of the 773 amino acids of L-CPT I, and the positions of carnitine, CoA and the palmitoyl group were assigned by superposition and docking analysis. Functional analysis of this 3-D model included the mutagenesis of several amino acids in order to identify putative catalytic residues. Mutants D477A, D567A and E590D showed reduced L-CPT I activity. In addition, individual mutation of amino acids forming the conserved Ser685-Thr686-Ser687 motif abolished enzyme activity in mutants T686A and S687A and altered K(m) and the catalytic efficiency for carnitine in mutant S685A. We conclude that the catalytic residues are His473 and Asp477, while Ser687 probably stabilizes the transition state. Several conserved lysines, i.e. Lys455, Lys505, Lys560 and Lys561, were also mutated. Only mutants K455A and K560A showed decreases in activity of 50%. The model rationalizes the finding of nine natural mutations in patients with hereditary L-CPT I deficiencies. PMID:14711372

  5. Paleomagnetic, geochronologic, and petrologic data discriminate tholeiitic basalts of the northern Hat Creek graben, northeastern California

    NASA Astrophysics Data System (ADS)

    Muffler, L. J.; Champion, D. E.; Calvert, A. T.; Clynne, M. A.

    2012-12-01

    Geologic mapping carried out in 2010-2012 under a Cooperative Research and Development Agreement (CRADA) between the U.S. Geological Survey and Pacific Gas and Electric Company provides the framework for geochronologic, paleomagnetic, and petrologic studies of the widespread low-potassium olivine tholeiite (LKOT) basalts that inundate low topography between higher-elevation remnants of >1 Ma calc-alkaline volcanoes in the northern part of the Hat Creek graben. These tholeiitic basalts are monotonously similar in appearance and cannot be distinguished one from another with any confidence in the field or petrographically. They are, however, distinctive in age, paleomagnetic secular directions, and major-element compositions, allowing us to map three major tholeiitic units: the basalt of Rocky Ledge (40Ar/39Ar determinations on 3 different exposures give 203.2 ± 13.7 ka, 186.8 ± 12.5 ka, and 203.9 ± 15.2 ka; weighted average 197 ± 8 ka), the basalt of Rock Spring (545.7 ± 6.7 ka), and the basalt of Sam Wolfin Spring (647.3 ± 21.7 ka). These tholeiitic units are overlain to the east by the calc-alkaline basalt west of Six Mile Hill (53.5 ± 2.0 ka) and to the south by the calc-alkaline basaltic andesite of Cinder Butte (38 ± 7 ka) and the tholeiitic Hat Creek Basalt (24 ± 6 ka). These latter two ages are from Turrin et al. (2007); all other ages are new 40Ar/39Ar determinations from the USGS geochronology laboratory in Menlo Park, California. Paleomagnetic directions of the tholeiitic basalt of Rocky Ledge (16 sites) cluster tightly at inclination and declination of 63° and 349°, respectively. Inclinations and declinations for the tholeiitic basalt of Rock Spring (3 sites) cluster at 43° and 14°, whereas inclinations and declinations for the tholeiitic basalt of Sam Wolfin Spring (7 sites) cluster at 54