Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

The past year has provided new insights into the biochemical mechanism of gene activation. Key discoveries include the finding that TFIIA plays an important regulatory role in transcription complex assembly, the TBP-associated factors are direct targets of at least two classes of activator, and a largely pre-assembled transcription complex has been isolated from yeast cells, challenging the step-wise assembly pathway. This review also presents an update on the argument that TFIIB is the target of VP16 and insights into the energetic role of ATP in RNA polymerase II initiation.
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PMID:The role of activators in assembly of RNA polymerase II transcription complexes. 803 1

The minimal requirements for transcription initiation from supercoiled templates were determined for the two major forms of TATA-binding factors found in cell extracts, the 300-kDa B-TFIID and the 1000-kDa D-TFIID complexes. As had been observed for the TATA-binding protein (TBP) subunit (Parvin and Sharp, 1993), transcription from the IgH promoter minimally requires TFIID activity plus TFIIB and RNA polymerase II. This minimal reaction is only active on negatively supercoiled template DNA. In contrast, the supercoiled templates encoding the adenovirus major late promoter (MLP), or several other promoters, require the addition of TFIIF to the minimal reaction. Further addition of TFIIE and TFIIH boosts the level of transcription from these latter promoters but is not required. In contrast to the complete reaction on linear template, transcription from supercoiled IgH or MLP templates does not require the hydrolysis of the beta-gamma bond of ATP. Fourteen different core promoters were compared in complete and minimal basal transcription reactions reconstituted with one of the three TATA activities: TBP, B-TFIID, and D-TFIID. Of these 14 promoters, only the IgH was active in the absence of TFIIF, and the other promoters demonstrated different levels of transcription depending on which basal factors were present in reaction. It is proposed that a significant level of basal transcription only requires a minimal set of factors, and stimulation by upstream activators may in part be mediated by the inclusion of additional basal factors into the initiation reaction.
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PMID:Multiple sets of basal factors initiate transcription by RNA polymerase II. 803 89

The human general transcription factors IIA and IIB bind directly to the TATA box-binding protein (TBP), and modulate transcription initiation by RNA polymerase II. RAP30, the small subunit of TFIIF, binds to TFIIB and RNA polymerase II and recruits RNA polymerase II to a preinitiation complex containing TBP and TFIIB. By using the adenovirus 2 major late promoter tagged site-specifically with the photoactivatible cross-linking reagent N3R-dUMP we have localized TBP, two subunits of TFIIA (A35 and A21), TFIIB, and RAP30 along promoter DNA. TFIIA cross-linked to the coding strand opposite TBP at the TATA box and cross-linked upstream of TBP around position -40. RAP30 cross-linked strongly and TFIIB weakly to the coding strand just downstream of TBP at -19. We interpret these data in the context of a molecular structure for the TBP promoter complex.
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PMID:Topological localization of the human transcription factors IIA, IIB, TATA box-binding protein, and RNA polymerase II-associated protein 30 on a class II promoter. 805 Oct 80

Phosphorylation of the COOH-terminal domain (CTD) of the largest subunit of RNA polymerase II by general transcription factor IIH (TFIIH) is believed to control the activity of polymerase at some stage of messenger RNA synthesis. In a recent study, transcription factor IIE (TFIIE) was proposed to play a key role in regulating phosphorylation of the RNA polymerase II CTD, on the basis of evidence indicating that preparations of recombinant TFIIE strongly stimulate CTD phosphorylation by TFIIH (Lu, H., Zawel, L., Fischer, L., Egly, J.-M., and Reinberg, D. (1992) Nature 358, 641-645). TFIIE is a heterodimer composed of 56-kDa (p56) and 34-kDa (p34) subunits and functions in concert with the TATA factor, TFIIB, TFIIF, and TFIIH to promote formation of the RNA polymerase II preinitiation complex. In the process of investigating the role that TFIIE plays in controlling phosphorylation of the RNA polymerase II CTD, we discovered that preparations of the recombinant TFIIE p56 subunit were sufficient to reconstitute stimulation of CTD phosphorylation by the TFIIH kinase. Further investigation revealed that CTD kinase stimulatory activity was chromatographically separable from the bulk of the transcriptionally active p56 subunit and was associated, instead, with a minor oligomeric form of p56. Taken together, these findings argue that the TFIIE p56 subunit is capable of interacting not only with the p34 subunit but also with itself to form either heterodimers or high molecular mass oligomers that play distinct roles in transcription initiation and regulation of the TFIIH kinase.
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PMID:An oligomeric form of the large subunit of transcription factor (TF) IIE activates phosphorylation of the RNA polymerase II carboxyl-terminal domain by TFIIH. 805 Nov 77

The general transcription factors (TF) IIB and TFIIA are the first factors to associate with the TATA-binding protein (TBP) during formation of a transcription initiation complex on RNA polymerase II promoters. DNase I footprint titration was used to measure the effects of TFIIB and TFIIA on binding of TBP to a consensus TATA box. Under reaction conditions optimized for TBP-DNA complex formation, the presence of TFIIB increased affinity of TBP for the TATA box by 2.5-fold, while TFIIA had no effect. When TBP binding conditions were sub-optimal, both TFIIB and TFIIA independently increased TBP affinity by approximately 10-fold. Therefore both TFIIB and TFIIA have the intrinsic ability to directly increase the affinity of TBP for the TATA box. We suggest that this property of TFIIA and TFIIB may increase the range of conditions under which high affinity TBP-DNA interactions can occur and may therefore favor the formation of the preinitiation complex.
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PMID:Transcription factor (TF) IIB and TFIIA can independently increase the affinity of the TATA-binding protein for DNA. 813 51

YY1 is a zinc finger transcription factor whose DNA-binding motif exhibits the properties of an initiator element. Only three factors were required to direct specific basal transcription on a supercoiled template DNA carrying the YY1 initiator: YY1, general transcription factor IIB, and RNA polymerase II. This minimal in vitro reaction did not require the TATA-binding protein (TBP). We propose that, under appropriate conditions, YY1 can function like TBP, as a factor that binds to the core promoter and recruits the polymerase to the initiation complex.
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PMID:TATA-binding protein-independent initiation: YY1, TFIIB, and RNA polymerase II direct basal transcription on supercoiled template DNA. 813 26

Using a defined RNA polymerase II (pol II) transcription system, we have investigated the roles of basal factors at discrete stages during the transcription cycle (e.g., initiation, promoter clearance, and transcript elongation). Abortive initiation assays revealed that TATA-binding protein, transcription factors TFIIB and TFIIF, and pol II were necessary and sufficient to form functional initiation complexes on both linear and supercoiled templates. By contrast, TFIIE, TFIIH, and ATP hydrolysis were additionally required during promoter clearance from linear templates, while negative supercoiling obviated the need for these auxiliary factors. Furthermore, TFIIE, TFIIH, and supercoiling were not required during elongation. Our results suggest a role for TFIIH-associated helicase activity or supercoiling during promoter clearance rather than open complex formation. These results establish abortive initiation as a useful assay for studying functional initiation complex formation in defined eukaryotic transcription systems and provide a framework for investigating regulation at different stages of the eukaryotic transcription cycle.
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PMID:Transcription factors IIE and IIH and ATP hydrolysis direct promoter clearance by RNA polymerase II. 815 90

General transcription factors are required for accurate initiation of transcription by RNA polymerase II. Human cDNAs encoding subunits of these factors have been cloned and sequenced. Using fluorescence in situ hybridization (FISH), we show here that the genes encoding the TATA-box binding protein (TBP), TFIIB, TFIIE alpha, TFIIE beta, RAP30, RAP74 and the 62 kDa subunit, of TFIIH are located at the human chromosomal bands 6q26-27, 1p21-22, 3q21-24, 8p12, 13q14, 19p13.3 and 11p14-15.1, respectively. This dispersed localization of a group of functionally related gene provides insights into the molecular mechanism of human genome evolution and their possible involvement in human diseases.
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PMID:Genes encoding general initiation factors for RNA polymerase II transcription are dispersed in the human genome. 816 52

Transcription initiation by RNA polymerase II is effected by an ordered series of general factor interactions with core promoter elements (leading to basal activity) and further regulated by gene-specific factors acting from distal elements. Both the general factor TFIID (refs 2,3), including the constituent TBP (TATA-binding polypeptide) and associated factors, and the interacting factor TFIIB (refs 9-11) have been implicated as targets for various activators. Towards an understanding of the basis for activator function, including the multiplicity of TBP interactions, we have now identified mutations in yeast TBP that selectively block activator (GAL4-VP16)-dependent but not basal transcription. We further show an effect of GAL4-VP16 on TFIIB recruitment to early preinitiation complexes, and that recruitment is disrupted by TBP mutations that impair its interactions with VP16 (L114K), TFIIB (L189K) or an unidentified component (K211L). Thus, GAL4-VP16 function seems to involve both direct interactions with TBP and a corresponding induction (or stabilization) of an activation-specific TBP-TFIIB-promoter complex.
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PMID:Effects of activation-defective TBP mutations on transcription initiation in yeast. 818 47

Enhancement of RNA polymerase II transcription by the viral transactivator VP16 requires the TFIID complex, which consists of the TATA-binding protein (TBP) and TBP-associated factors (TAFs). Here we report the molecular cloning, expression, and biochemical characterization of Drosophila TAFII40 (dTAFII40), a subunit of TFIID. In vitro protein-protein interaction assays revealed direct binding between dTAFII40 and a 39 amino acid VP16 activation domain. In addition, affinity chromatography indicated a direct binding of the basal factor TFIIB to immobilized dTAFII40. Since VP16 also binds TFIIB, our results suggest a ternary interaction among an activator, a coactivator, and a basal transcription factor. Antibodies directed against dTAFII40 inhibited activation by GAL4-VP16 without affecting basal transcription. These results, taken together with previous studies of Sp1 and dTAFII110, establish that different activators interact with distinct TAFs in the TFIID complex and that TAFs can contact both activators and basal factors.
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PMID:Drosophila TAFII40 interacts with both a VP16 activation domain and the basal transcription factor TFIIB. 822 91


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