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)

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

Transcription by RNA polymerase I (pol I), pol II, and pol III requires the TATA-binding protein (TBP). This protein functions in association with distinct TBP-associated factors (TAFs) which may specify the nature of the polymerase selected for initiation at a promoter site. In the pol III transcription system, the TBP-TAF complex is a component of the TFIIIB factor. This factor has been resolved into a TBP-TAF complex and another component, both of which are required for reconstitution of transcription by pol III. Neither the TBP-TAF complexes B-TFIID and D-TFIID, which were previously characterized as active for pol II transcription, nor TBP alone can complement pol III transcription reactions that are dependent upon the TBP-TAF subcomponent of TFIIIB. Surprisingly, the TBP-TAF subcomponent of TFIIIB is active in reconstitution of pol II transcription.
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PMID:TATA-binding protein and associated factors in polymerase II and polymerase III transcription. 824 10

The human U1 and U6 genes have similar basal promoter structures. A first analysis of the factor requirements for the transcription of a human U1 gene by RNA polymerase II in vitro has been undertaken, and these requirements compared with those of human U6 gene transcription by RNA polymerase III in the same extracts. Fractions containing PSE-binding protein (PBP) are shown to be essential for transcription of both genes, and further evidence that PBP itself is required for U1 as well as U6 transcription is presented. On the other hand, the two genes have distinct requirements for TATA-binding protein (TBP). On the basis of chromatographic and functional properties, the TBP, or TBP complex, required for U1 transcription appears to differ from previously described complexes required for RNA polymerase I, II or III transcription. The different TBP requirements of the U1 and U6 promoters are reflected by specific association with either TFIIB or TFIIIB respectively, thus providing a basis for differential RNA polymerase selection.
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PMID:Common and unique transcription factor requirements of human U1 and U6 snRNA genes. 825 82

A transcriptional initiator (Inr) for mammalian RNA polymerase II can be defined as a DNA sequence element that overlaps a transcription start site and is sufficient for (i) determining the start site location in a promoter that lacks a TATA box and (ii) enhancing the strength of a promoter that contains a TATA box. We have prepared synthetic promoters containing random nucleotides downstream of Sp1 binding sites to determine the range of DNA sequences that convey Inr activity. Numerous sequences behaved as functional Inrs in an in vitro transcription assay, but the Inr activities varied dramatically. An examination of the functional elements revealed loose but consistent sequence requirements, with the approximate consensus sequence Py Py A+1 N T/A Py Py. Most importantly, almost every functional Inr that has been described fits into the consensus sequence that we have defined. Although several proteins have been reported to bind to specific Inrs, manipulation of those elements failed to correlate protein binding with Inr activity. The simplest model to explain these results is that all or most Inrs are recognized by a universal binding protein, similar to the functional recognition of all TATA sequences by the same TATA-binding protein. The previously reported proteins that bind near specific Inr elements may augment the strength of an Inr or may impart transcriptional regulation through an Inr.
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PMID:DNA sequence requirements for transcriptional initiator activity in mammalian cells. 826 80

We have previously found that the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) induces specific transcription of tRNA and 5S RNA genes in Drosophila Schneider S-2 cells (M. Garber, S. Panchanathan, R. F. Fan, and D. L. Johnson, J. Biol. Chem. 266:20598-20601, 1991). Having derived cellular extracts from TPA-treated cells, that are capable of reproducing this stimulation in vitro, we have examined the mechanism for this regulatory event. Using conditions that limit reinitiation and produce single rounds of transcription from active gene complexes, we find that the number of functional transcription complexes is increased in extracts prepared from TPA-induced cells. We have analyzed the activities of the transcription factors TFIIIB and TFIIIC derived from extracts prepared from TPA-induced and noninduced cells. Examination of the relative activities of TFIIIC showed that both its ability to reconstitute transcription with TFIIIB and RNA polymerase III and its ability to stably bind to the DNA template are unchanged. However, the activity of TFIIIB derived from the TPA-induced cells is substantially increased compared with that derived from the noninduced cells. The differences in TFIIIB activity account for the differences in the overall transcriptional activities observed in the unfractionated extracts. Western blot analysis of the TATA-binding protein subunit of TFIIIB revealed that there is an increase in the amount of this polypeptide present in the induced cell extracts and TFIIIB fraction. Together, these results indicate that the TPA response in Drosophila cells stimulates specific transcription of RNA polymerase III genes by increasing the activity of the limiting transcription component, TFIIIB, and thereby increasing the number of functional transcription complexes.
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PMID:Induction of Drosophila RNA polymerase III gene expression by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) is mediated by transcription factor IIIB. 826 1

The role of the Acanthamoeba castellanii TATA-binding protein (TBP) in transcription was examined. Specific antibodies against the nonconserved N-terminal domain of TBP were used to verify the presence of TBP in the fundamental transcription initiation factor for RNA polymerase I, TIF-IB, and to demonstrate that TBP is part of the committed initiation complex on the rRNA promoter. The same antibodies inhibit transcription in all three polymerase systems, but they do so differentially. Oligonucleotide competitors were used to evaluate the accessibility of the TATA-binding site in TIF-IB, TFIID, and TFIIIB. The results suggest that insertion of TBP into the polymerase II and III factors is more similar than insertion into the polymerase I factor.
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PMID:TATA box-binding protein (TBP) is a constituent of the polymerase I-specific transcription initiation factor TIF-IB (SL1) bound to the rRNA promoter and shows differential sensitivity to TBP-directed reagents in polymerase I, II, and III transcription factors. 826 28

Unambiguous TATA boxes have not been identified in upstream sequences of Tetrahymena thermophila genes analyzed to date. To begin a characterization of the promoter requirements for RNA polymerase II, the gene encoding TATA-binding protein (TBP) was cloned from this species. The derived amino acid sequence for the conserved C-terminal domain of Tetrahymena TBP is one of the most divergent described and includes a unique 20-amino-acid C-terminal extension. Polyclonal antibodies generated against a fragment of Tetrahymena TBP recognize a 36-kDa protein in macronuclear preparations and also cross-react with yeast and human TBPs. Immunocytochemistry was used to examine the nuclear localization of TBP during growth, starvation, and conjugation (the sexual phase of the life cycle). The transcriptionally active macronuclei stained at all stages of the life cycle. The transcriptionally inert micronuclei did not stain during growth or starvation but surprisingly stained with anti-TBP throughout early stages of conjugation. Anti-TBP staining disappeared from developing micronuclei late in conjugation, corresponding to the onset of transcription in developing macronuclei. Since micronuclei do not enlarge or divide at this time, loss of TBP appears to be an active process. Thus, the transcriptional differences between macro- and micronuclei that arise during conjugation are associated with the loss of a major component of the basal transcription apparatus from developing micronuclei rather than its appearance in developing macronuclei.
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PMID:TATA-binding protein and nuclear differentiation in Tetrahymena thermophila. 826 41

The transcriptional activation of eukaryotic class II genes by sequence-specific regulatory proteins requires cofactors in addition to the general transcription factors. One cofactor (termed PC3) was purified from HeLa cells and identified by sequence analysis and functional assays as human DNA topoisomerase I (EC5.99.1.2). Under identical conditions PC3 mediates both a net activation of transcription by the acidic activator GAL4-AH and repression of basal transcription, thereby leading to a large induction of transcription by the activator. PC3-mediated activation of transcription is dependent on the presence of both the GAL4-AH activation domain and the TATA-binding protein (TBP)-associated-factors (TAFs) in natural transcription factor TFIID, while repression of basal transcription is observed with either TFIID or the derived TBP alone. These results suggest novel functions, apparently through distinct mechanisms, for human DNA topoisomerase I in the regulation of transcription initiation by RNA polymerase II.
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PMID:Identification of human DNA topoisomerase I as a cofactor for activator-dependent transcription by RNA polymerase II. 826 82

The multisubunit transcription factor TFIID is an essential component of the RNA polymerase II initiation apparatus. Recent studies suggest that TFIID subunits, or TAFs associated with the TATA-binding protein (TBP), play a critical role in modulating transcriptional activation by sequence-specific DNA-binding factors. Thus far, six of the largest TAFs associated with Drosophila TFIID have been cloned and partially characterized. Here, we report the molecular cloning, expression, and subunit interaction specificities of two small molecular mass TAFs. Both dTAFII30 alpha and dTAFII30 beta are associated with TFIID via interactions with other TAFs, including dTAFII250, dTAFII150, and dTAFII110. In addition, dTAFII30 alpha also contacts dTBP. The carboxy-terminal half of dTAFII110 was found to contact a short 67-amino-acid region of dTAFII30 alpha, which is predicted to form two potential alpha-helices, one of which is amphipathic. Interestingly, dTAFII30 alpha also appears to multimerize through its carboxy-terminal region. Although neither dTAFII30 alpha nor dTAFII30 beta have been found to interact with specific activators thus far, it is intriguing that both bind other TAFs such as dTAFII110 and dTAFII150, which are the targets of activation domains. Our studies suggest that both of the small subunits of TFIID play a role in the assembly of the complex and may contribute to the stability of multiple TAF-TAF interactions.
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PMID:Molecular cloning and characterization of dTAFII30 alpha and dTAFII30 beta: two small subunits of Drosophila TFIID. 827 41

Activation domains of mammalian transcription factors can be subdivided into at least two functional classes. One, exemplified by the glutamine-rich activation domains of Oct and Sp1 factors, mediates transcriptional activation only from a proximal promoter position, and in response to an enhancer. The other, exemplified by the 'acidic' domain of the viral activator VP16, has the ability to activate from remote enhancer as well as from proximal promoter positions. Here we report that two proteins of the basal transcription apparatus also contain activation domains whose stimulatory effect can be detected in fusion proteins containing the GAL4 DNA binding domain. The human TATA-binding protein (TBP) contains at its N-terminus a domain with typical 'promoter' activity. We propose that the TBP N-terminal region acts as an auxiliary activation domain which reinforces the activity of other promoter-bound factors. The largest subunit of RNA polymerase II contains at its C-terminus a conserved heptad repeat structure (CTD). Both natural and synthetic CTD consensus repeats fused to GAL4 can activate transcription from remote positions like a typical enhancer-active domain. Accordingly we propose that the RNA polymerase II large subunit contains a 'portable' domain for transcriptional activation which may synergize with the activation domains of enhancer-bound transcription factors.
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PMID:C-terminal domain (CTD) of RNA-polymerase II and N-terminal segment of the human TATA binding protein (TBP) can mediate remote and proximal transcriptional activation, respectively. 828 5


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