Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Spt3 of Saccharomyces cerevisiae is a factor required for normal transcription from particular RNA polymerase II-dependent promoters. As a step towards analysing Spt3 structure-function relationships, we have identified and studied Spt3 homologues from three other yeasts: Kluyveromyces lactis, Clavispora opuntiae and Schizosaccharomyces pombe. Alignment of their predicted amino acid sequences shows an overall identity of 30% between all four homologues and suggests that three conserved domains are present in Spt3. When tested for function in S. cerevisiae, K. lactis SPT3 was shown to fully complement and S. pombe SPT3 to partially complement an spt3 delta mutation. These data demonstrate that Spt3 is functionally conserved among distantly related yeasts.
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PMID:Identification and analysis of homologues of Saccharomyces cerevisiae Spt3 suggest conserved functional domains. 955 49

Mutations selected as suppressors of Ty or solo delta insertion mutations in Saccharomyces cerevisiae have identified several genes, SPT3, SPT7, SPT8, and SPT20, that encode components of the SAGA complex. However, the mechanism by which SAGA activates transcription of specific RNA polymerase II-dependent genes is unknown. We have conducted a fine-structure mutagenesis of one widely used SAGA-dependent promoter, the delta element of his4-912delta, to identify sequence elements important for its promoter activity. Our analysis has characterized three delta regions necessary for full promoter activity and accurate start site selection: an upstream activating sequence, a TATA region, and an initiator region. In addition, we have shown that factors present at the adjacent UASHIS4 (Gcn4, Bas1, and Pho2) also activate the delta promoter in his4-912delta. Our results suggest a model in which the delta promoter in his4-912delta is primarily activated by two factors: Gcr1 acting at the UASdelta and Gcn4 acting at the UASHIS4. Finally, we tested whether activation by either of these factors is dependent on components of the SAGA complex. Our results demonstrate that Spt3 and Spt20 are required for full delta promoter activity, but that Gcn5, another member of SAGA, is not required. Spt3 appears to be partially required for activation of his4-912delta by both Gcr1 and Gcn4. Thus, our work suggests that SAGA exerts a large effect on delta promoter activity through a combination of smaller effects on multiple factors.
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PMID:Specific components of the SAGA complex are required for Gcn4- and Gcr1-mediated activation of the his4-912delta promoter in Saccharomyces cerevisiae. 1010 Nov 63

Initiation of transcription of protein-encoding genes by RNA polymerase II was thought to require the transcription factor II D (TF(II)D), a complex comprising the TATA binding protein (TBP) and TBP-associated factors. However, another multiprotein complex isolated more recently and called TFTC (TBP-free TAF(II )containing complex), was shown to mediate initiation of RNA polymerase II (Pol II) transcription in the absence of TF(II)D as well as specific acetylation of histone H3 in a nucleosomal context. Several subunits of the TFTC complex were already identified using classical methods such as Edman based microsequencing and Western blot analysis. In this article we present a mass spectrometry based proteomic approach to confirm previous results and to identify other possible subunits of the TFTC complex. The TFTC complex was separated on one-dimensional sodium dodecyl sulfate polyacrylamide electrophoresis and analysed by matrix-assisted laser desorption/ionization-time of flight mass spectrometry and peptide mass fingerprinting. Identifications were realized after databank searches. This new characterization of TFTC complex confirmed the presence of already described subunits (TRRAP, GCN5, SAP130/KIA0017, TAF(II)150, TAF(II)135, TAF(II)100, TAF(II)80, TAF(II)20, SPT3 and PAF65beta). Moreover, a good coverage of these sequences was obtained. Interestingly, TAF(II)32 and PAF6alpha were also determined as potential novel subunits of TFTC. These results together show the suitability and the great potential of this method and offer new perspectives in fundamental studies of transcription factor complexes.
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PMID:Novel subunits of the TATA binding protein free TAFII-containing transcription complex identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry following one-dimensional gel electrophoresis. 1260 14

Spinocerebellar ataxia type 7 (SCA7) is a neurodegenerative disorder caused by a CAG repeat expansion in the SCA7 gene leading to elongation of a polyglutamine tract in ataxin-7, a protein of unknown function. A putative ataxin-7 yeast orthologue (SGF73) has been identified recently as a new component of the SAGA (Spt/Ada/Gcn5 acetylase) multisubunit complex, a coactivator required for transcription of a subset of RNA polymerase II-dependent genes. We show here that ataxin-7 is an integral component of the mammalian SAGA-like complexes, the TATA-binding protein-free TAF-containing complex (TFTC) and the SPT3/TAF9/GCN5 acetyltransferase complex (STAGA). In agreement, immunoprecipitation of ataxin-7 retained a histone acetyltransferase activity, characteristic for TFTC-like complexes. We further identified a minimal domain in ataxin-7 that is required for interaction with TFTC/STAGA subunits and is conserved highly through evolution, allowing the identification of a SCA7 gene family. We showed that this domain contains a conserved Cys(3)His motif that binds zinc, forming a new zinc-binding domain. Finally, polyglutamine expansion in ataxin-7 did not affect its incorporation into TFTC/STAGA complexes purified from SCA7 patient cells. We demonstrate here that ataxin-7 is the human orthologue of the yeast SAGA SGF73 subunit and is a bona fide subunit of the human TFTC-like transcriptional complexes.
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PMID:Ataxin-7 is a subunit of GCN5 histone acetyltransferase-containing complexes. 1511 62

SCA7 (spinocerebellar ataxia type 7) is a neurodegenerative disorder caused by a CAG repeat expansion in the SCA7 gene that leads to elongation of a polyglutamine tract in ataxin-7, a protein of unknown function. Sgf73, a putative yeast orthologue of ataxin-7, has been identified as a new component of the yeast SAGA (Spt/Ada/Gcn5 acetyltransferase) multisubunit complex, a co-activator required for the transcription of a subset of RNA polymerase II-dependent genes. We show here that ataxin-7 is an integral component of mammalian SAGA-like complexes, i.e. the TFTC [TBP (TATA-binding protein)-free TAF (TBP-associated factor) complex] and the STAGA (SPT3/TAF9/GCN5 acetyltransferase) complex. In agreement with this, immunoprecipitation of ataxin-7 retained a histone acetyltransferase activity characteristic of TFTC-like complexes. Moreover, polyglutamine expansion in ataxin-7 did not affect its incorporation into TFTCs/STAGA complexes purified from cells from a SCA7 patient. We demonstrate here that ataxin-7 is the human orthologue of a the yeast SAGA Sgf73 subunit, and is a bona fide subunit of human TFTC-like transcriptional complexes.
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PMID:Both normal and polyglutamine- expanded ataxin-7 are components of TFTC-type GCN5 histone acetyltransferase- containing complexes. 1662 96

Transcription in eukaryotes is a tightly regulated, multistep process. Gene-specific transcriptional activators, several different co-activators and general transcription factors are necessary to access specific loci to allow precise initiation of RNA polymerase II transcription. As the dense chromatin folding of the genome does not allow the access of these sites by the huge multiprotein transcription machinery, remodelling is required to loosen up the chromatin structure for successful transcription initiation. In the present review, we summarize the recent evolution of our understanding of the function of two histone acetyl transferases (ATs) from metazoan organisms: GCN5 and PCAF. Their overall structure and the multiprotein complexes in which they are carrying out their activities are discussed. Metazoan GCN5 and PCAF are subunits of at least two types of multiprotein complexes, one having a molecular weight of 2 MDa (SPT3-TAF9-GCN5 acetyl transferase/TATA binding protein (TBP)-free-TAF complex/PCAF complexes) and a second type with about a size of 700 kDa (ATAC complex). These complexes possess global histone acetylation activity and locus-specific co-activator functions together with AT activity on non-histone substrates. Thus, their biological functions cover a wide range of tasks and render them indispensable for the normal function of cells. That deregulation of the global and/or specific AT activities of these complexes leads to the cancerous transformation of the cells highlights their importance in cellular processes. The possible effects of GCN5 and PCAF in tumorigenesis are also discussed.
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PMID:Distinct GCN5/PCAF-containing complexes function as co-activators and are involved in transcription factor and global histone acetylation. 1769 77

Activation of eukaryotic gene transcription involves the recruitment by DNA-binding activators of multiprotein histone acetyltransferase (HAT) and Mediator complexes. How these coactivator complexes functionally cooperate and the roles of the different subunits/modules remain unclear. Here we report physical interactions between the human HAT complex STAGA (SPT3-TAF9-GCN5-acetylase) and a "core" form of the Mediator complex during transcription activation by the MYC oncoprotein. Knockdown of the STAF65gamma component of STAGA in human cells prevents the stable association of TRRAP and GCN5 with the SPT3 and TAF9 subunits; impairs transcription of MYC-dependent genes, including MYC transactivation of the telomerase reverse transcriptase (TERT) promoter; and inhibits proliferation of MYC-dependent cells. STAF65gamma is required for SPT3/STAGA interaction with core Mediator and for MYC recruitment of SPT3, TAF9, and core Mediator components to the TERT promoter but is dispensable for MYC recruitment of TRRAP, GCN5, and p300 and for acetylation of nucleosomes and loading of TFIID and RNA polymerase II on the promoter. These results suggest a novel STAF65gamma-dependent function of STAGA-type complexes in cell proliferation and transcription activation by MYC postloading of TFIID and RNA polymerase II that involves direct recruitment of core Mediator.
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PMID:STAGA recruits Mediator to the MYC oncoprotein to stimulate transcription and cell proliferation. 1796 94