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)

Fractionation of yeast whole-cell extract has led to the identification and purification of four novel proteins required for promoter-dependent transcription by RNA polymerase II in vitro. These initiation factors have been shown to be related in structure and function to RNA polymerase II initiation factors purified from mammalian cells. When combined with the well known TATA-binding protein, the entire set of initiation factors proves necessary and sufficient for accurate initiation from a variety of eukaryotic promoters. Studies with this defined transcription system have revealed the existence of additional proteins required for transcriptional activation or derepression by enhancer-binding regulatory proteins.
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PMID:Mechanism and regulation of yeast RNA polymerase II transcription. 831 70

In the process of characterizing cellular proteins that modulate basal transcription by RNA polymerase II, we identified a novel repressor activity specific for promoters containing consensus TATA boxes. This activity strongly represses TATA-binding protein (TBP)-dependent transcription initiation from core promoter elements containing a consensus TATA sequence, but activates TBP-dependent transcription from core promoter elements lacking a consensus TATA sequence. Purification of this activity to near homogeneity from rat liver nuclear extracts led to the surprising discovery that it co-purifies closely with mammalian transcription factor IIA (TFIIA). The close association of TATA sequence-dependent transcriptional repressor activity with TFIIA adds a new and unexpected dimension to the already complex picture of this factor's function in transcription by RNA polymerase II.
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PMID:A TATA sequence-dependent transcriptional repressor activity associated with mammalian transcription factor IIA. 831 89

We report genetic and biochemical evidence that the RNA polymerase II carboxy-terminal domain (CTD) interacts with a large multisubunit complex that contains TATA-binding protein (TBP) and is an integral part of the transcription initiation complex. The isolation and characterization of extragenic suppressors of S. cerevisiae RNA polymerase II CTD truncation mutations led us to identify SRB2, SRB4, SRB5, and SRB6 as genes involved in CTD function in vivo. SRB2 was previously isolated and shown to encode a 23 kd TBP-binding protein. The four SRB proteins and a portion of cellular TBP are components of a high molecular weight multisubunit complex that is tightly bound to RNA polymerase II. This SRB-TBP complex binds specifically to recombinant CTD protein. In vitro transcription and template commitment assays confirm that SRB2 and SRB5 are components of a functional preinitiation complex and are required for efficient transcription initiation.
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PMID:A multisubunit complex associated with the RNA polymerase II CTD and TATA-binding protein in yeast. 832 25

We have examined the binding of chicken nuclear protein to the promoter regions of chicken ribosomal protein L5 and 5S rRNA genes. A nuclear protein was shown to bind to similar sequences in both promoter regions of the L5 gene (-36 to -21) and the internal control region of 5S rRNA gene (56 to 71). Its molecular mass was estimated to be 34 kDa. Competition gel mobility assay showed that the protein is different from the TATA-box binding protein (TBP). The protein may play a role in a transcriptional coordination of the two genes transcribed by different polymerases, RNA polymerase II and III.
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PMID:A common nuclear factor that binds to the transcriptional control regions of ribosomal protein L5 and 5S rRNA genes. 835 69

We describe techniques for production and chromatographic fractionation of a transcriptionally active whole-cell extract from Saccharomyces cerevisiae. The procedure is suitable for large-scale isolation of the factors involved in mRNA synthesis. Both yeast transcription factor IIB and TATA-binding protein were purified from the extract as single species using an immunoblot assay. In addition, the three previously described isoforms of yeast RNA polymerase II were resolved and form IIa, the intact, unphosphorylated isoform proposed to be involved in initiation, was purified to apparent homogeneity.
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PMID:Resolution of transcription factors from a transcriptionally active whole-cell extract from yeast: purification of TFIIB, TBP, and RNA polymerase IIa. 837 98

The minimal promoter elements required for initiation by RNA polymerase II include the TATA box and/or an initiator element (Inr) at or near the transcription start site. Studies of the adenovirus major late core promoter (containing both elements) have demonstrated an initiation pathway that involves binding of the transcription factor TFIID (or the derived subunit, the TATA-binding protein TBP (TFIID tau)) to the TATA element, which is facilitated by transcription factor TFIIA, followed by sequential interactions of other general factors. Here we describe a novel pathway that requires an intact Inr and the Inr-binding factor TFII-I (ref. 3). Sequential addition of the general factors generated TFII-I-dependent preinitiation complexes different from those formed with TFIIA. Furthermore, TBP bound cooperatively (with only TFII-I) to an Inr-containing TATA-less promoter, suggesting a means for activation of TATA-less promoters, which nonetheless require TFIID (refs 9-11). These observations provide support for functionally distinct pathways which could be subject to differential regulation by specific activators or repressors.
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PMID:An alternative pathway for transcription initiation involving TFII-I. 837 28

Host cell RNA polymerase II (Pol II)-mediated transcription is inhibited by poliovirus infection. This inhibition is correlated to a specific decrease in the activity of a chromatographic fraction which contains the transcription factor TFIID. To investigate the mechanism by which poliovirus infection results in a decrease of TFIID activity, we have analyzed a component of TFIID, the TATA-binding protein (TBP). Using Western immunoblot analysis, we show that TBP is cleaved in poliovirus-infected cells at the same time postinfection as when Pol II transcription is inhibited. Further, we show that one of the cleaved forms of TBP can be reproduced in vitro by incubating TBP with cloned, purified poliovirus encoded protease 3C. Protease 3C is a poliovirus-encoded protease that specifically cleaves glutamine-glycine bonds in the viral polyprotein. The cleavage of TBP by protease 3C occurs directly. Finally, incubation of an uninfected cell-derived TBP-containing fraction (TFIID) with protease 3C results in significant inhibition of Pol II-mediated transcription in vitro. These results demonstrate that a cellular transcription factor can be directly cleaved both in vitro and in vivo by a viral protease and suggest a role of the poliovirus proteinase 3C in host cell Pol II-mediated transcription shutoff.
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PMID:Direct cleavage of human TATA-binding protein by poliovirus protease 3C in vivo and in vitro. 838 Aug 94

Host cell RNA polymerase II-mediated transcription is inhibited by poliovirus infection. We have shown previously that the human TATA-binding protein (TBP), a general transcription factor required for transcription of all RNA polymerase II genes, is directly cleaved both in vitro and in vivo by the virus-coded protease 3CPro. 3CPro specifically cleaves glutamine-glycine bonds in the viral polyprotein. Cellular transcription factor TBP contains three glutamine-glycine sites, at amino acids 12, 18, and 108. By using site-directed mutagenesis, we determined that the glutamine-glycine bond at amino acid 18, but not that at amino acid 12 or 108, is cleaved by the viral protease. Both the glutamine and the glycine appear to be important for the cleavage. Further mutations around the glutamine-glycine site at position 18 suggest that determinants other than the glutamine-glycine bond in TBP are also required for 3CPro-induced cleavage. An alanine at position P4 and a proline at position P2, proximal to the scissile glutamine-glycine pair, appear to be important for 3CPro-mediated cleavage of TBP. Our results suggest that the cleavage specificity of 3CPro for a cellular transcription factor is very similar to its mode of cleavage of viral polyproteins.
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PMID:Identification of the cleavage site and determinants required for poliovirus 3CPro-catalyzed cleavage of human TATA-binding transcription factor TBP. 838 2

The function of a TATA element in RNA polymerase (EC 2.7.7.6) III transcription of a naturally TATA-containing U6 snRNA gene and a naturally TATA-less tRNA gene was probed by transcription and Ty3 transposition analyses. Deletion of the TATA box from a U6 minigene did not abolish transcription and Ty3 integration but changed the positions of initiation and insertion. Insertion of the U6 TATA box at three positions upstream of the TATA-less SUP2 tRNA(Tyr) gene resulted in novel transcription initiation and Ty3 integration patterns that depended upon position of the insertion. Nevertheless, the predominant tRNA gene initiation sites were not affected by insertion of the TATA sequence and remained at a fixed distance from the internal box A promoter element. Insertions of the TATA box upstream of a SUP2 box A mutant affected the level of transcription and restricted the use of upstream start sites, but they neither enhanced the use of TATA-dependent initiation sites nor restored expression to the level of the wild-type gene. We conclude that (i) the U6 TATA box is essential in vivo for correct initiation but not for transcription, (ii) a TATA box does not compensate for a weak box A sequence and so cannot perform equivalently, and (iii) the TATA-binding protein, and probably components of transcription factor IIIB, are present on the target at the time of Ty3 integration.
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PMID:Sites of RNA polymerase III transcription initiation and Ty3 integration at the U6 gene are positioned by the TATA box. 838 58

The ICP4 protein of herpes simplex virus can either increase or decrease the rate of transcription mediated by RNA polymerase II, depending on the target promoter. The interplay of DNA-protein and protein-protein contacts determining ICP4 function has yet to be characterized, and consequently the molecular mechanism by which the protein acts remains unclear. ICP4 can transactivate minimal promoters containing only TATA homologies, and therefore it is reasonable to hypothesize that ICP4 works by influencing the TATA-dependent assembly of general transcription factors via specific protein-protein interactions. This study directly addresses this hypothesis by determining whether ICP4 affects the assembly of general transcription factors on templates bearing a TATA box and an ICP4-binding site. Using gel retardation and footprinting assays, we found that ICP4 forms a tripartite complex with TFIIB and either the TATA-binding protein (TBP) or TFIID. The formation of this complex was not the result of simple tripartite occupancy of the DNA but the consequence of protein-protein interactions. In the presence of all three proteins, the affinity of ICP4 and TBP for their respective binding sites was substantially increased. Using mutant derivatives of ICP4 and defective versions of promoters, we also demonstrated that the ability of ICP4 to regulate gene expression correlated with its ability to form a tripartite complex with TFIIB and TBP in vitro.
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PMID:ICP4, the major transcriptional regulatory protein of herpes simplex virus type 1, forms a tripartite complex with TATA-binding protein and TFIIB. 839 7


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