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)

Accurate and regulated transcription by RNA polymerase II requires the assembly of an initiation complex involving multiple protein-DNA and protein-protein interactions. A key event is binding of TFIID, a complex consisting of TBP and associated factors (TAFs) to the template DNA. The TAF subunits of TFIID carry out diverse functions critical for transcription, including specific contact with enhancer proteins and binding to core promoter DNA. However, the role of TAFs in RNA polymerase II-mediated transcription initiation and cross talk with other basal factors remains poorly characterized. Here, we report the specific interaction of TAFII250 with RAP74, an essential subunit of the basal transcription factor IIF. Using various in vitro binding assays we have mapped recognition interfaces between TAFII250 and RAP74. In vivo complementation of a temperature-sensitive TAFII250 cell line reveals that the RAP74 interaction is critical for cell viability. Because TFIIF is thought to be responsible for binding and recruiting RNA polymerase II, the ability of TAFII250 to interact selectively with RAP74 is likely to contribute a critical contact for the assembly of an active transcription complex.
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PMID:Human TAFII250 interacts with RAP74: implications for RNA polymerase II initiation. 759 Feb 50

Basal transcription by human RNA polymerase II requires the coordinate action of several ancillary factors (TFIIA-J) and can be regulated by various promoter-specific DNA binding proteins. An additional class of factors, called coactivators, are dispensable for basal transcription but are indispensable for regulation by transcriptional activators. Biochemical studies established that some coactivators are associated with the TATA-binding protein (TBP) to form the TFIID complex. We therefore set out to define the relationship between TBP and these TBP-associated factors (TAFs). Here we describe the cloning, expression and properties of the first human TAF, hTAFII250. The hTAFII250 gene is identical to a gene, CCG1, (ref 7,8), implicated in cell-cycle progression. Recombinant hTAFII250 binds directly to TBP both in vitro and in yeast, and participates in the formation of the TFIID complex. This largest TAF may therefore play a central role in TFIID assembly by interacting with both TBP and other TAFs, as well as serving to link the control of transcription to the cell cycle.
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PMID:Cloning and expression of human TAFII250: a TBP-associated factor implicated in cell-cycle regulation. 768 Jul 71

RNA polymerase I and II transcription factors SL1 and TFIID, respectively, are composed of the TATA-binding protein (TBP) and a set of TBP-associated factors (TAFs) responsible for promoter recognition. How the universal transcription factor TBP becomes committed to a TFIID or SL1 complex has not been known. Complementary DNAs encoding each of the three TAFIs that are integral components of SL1 have not been isolated. Analysis of subunit interactions indicated that the three TAFIs can bind individually and specifically to TBP. In addition, these TAFIs interact with each other to form a stable TBP-TAF complex. When TBP was bound first by either TAFI110, 63, or 48, subunits of TFIID such as TAFII250 and 150 did not bind TBP. Conversely, if TBP first formed a complex with TAFII250 or 150, the subunits of SL1 did not bind TBP. These results suggest that a mutually exclusive binding specificity for TBP intrinsic to SL1 and TFIID subunits directs the formation of promoter- and RNA polymerase-selective TBP-TAF complexes.
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PMID:Reconstitution of transcription factor SL1: exclusive binding of TBP by SL1 or TFIID subunits. 780 Nov 23

Regulation of transcription initiation by RNA polymerase II requires TFIID, a multisubunit complex composed of the TATA binding protein (TBP) and at least seven tightly associated factors (TAFs). Some TAFs act as direct targets or coactivators for promoter-specific activators while others serve as interfaces for TAF-TAF interactions. Here, we report the molecular cloning, expression and characterization of Drosophila dTAFII60 and its human homolog, hTAFII70. Recombinant TAFII60/70 binds weakly to TBP and tightly to the largest subunit of TFIID, TAFII250. In the presence of TAFII60/70, TBP and TAFII250, a stable ternary complex is formed. Both the human and Drosophila proteins directly interact with another TFIID subunit, dTAFII40. Our findings reveal that Drosophila TAFII60 and human TAFII70 share a high degree of structural similarity and that their interactions with other subunits of TFIID are conserved.
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PMID:Cloning and expression of Drosophila TAFII60 and human TAFII70 reveal conserved interactions with other subunits of TFIID. 826 73

The acetylation of histones increases the accessibility of nucleosomal DNA to transcription factors [1,2], relieving transcriptional repression [3] and correlating with the potential for transcriptional activity in vivo [4 - 7]. The characterization of several novel histone acetyltransferases - including the human GCN5 homolog PCAF (p300/CBP-associated factor) [8], the transcription coactivator p300/CBP [9], and TAFII250 [10] - has provided a potential explanation for the relationship between histone acetylation and transcriptional activation. In addition to histones, however, other components of the basal transcription machinery might be acetylated by these enzymes and directly affect transcription. Here, we examine the acetylation of the basal transcriptional machinery for RNA polymerase II by PCAF, p300 and TAFII250. We find that all three acetyltransferases can direct the acetylation of TFIIEbetaand TFIIF, and we identify a preferred site of acetylation in TFIIEbeta. Human TFIIE consists of two subunits, alpha(p56) and beta(p34), which form a heterotetramer (alpha2 beta2) in solution ([11], reviewed in [12]). TFIIE enters the preinitiation complex after RNA polymerase II and TFIIF, suggesting that TFIIE may interact directly with RNA polymerase II and/or TFIIF [13,14]. In addition, TFIIE can facilitate promoter melting either in the presence or absence of TFIIH and can stimulate TFIIH-dependent phosphorylation of the carboxy-terminal domain of RNA polymerase II [15-18]. TFIIF has an essential role in both transcription initiation and elongation ([19,20], for review see [21]). We discuss the implications of the acetylation of TFIIEbetaand TFIIF for transcriptional control by PCAF, p300 and TAFII250.
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PMID:Acetylation of general transcription factors by histone acetyltransferases. 928 13

Human positive cofactor (PC4) acts as a general coactivator for activator-dependent transcription by RNA polymerase II. Here we show that PC4 coactivator function, in contrast to basal (activator-independent) transcription, is dependent both on TATA binding protein (TBP)-associated factors (TAFs) in TFIID and on TFIIH. Surprisingly, PC4 strongly represses transcription initiation by minimal preinitiation complexes in the absence of TAFs and TFIIH, while simultaneously promoting the formation of these complexes. Furthermore, TFIIH and TAFII250, the largest subunit of TFIID, can both phosphorylate PC4. These results provide evidence for an inactive, PC4-induced intermediate in preinitiation complex assembly and point to TFIIH and TAF requirements for its progression into a functional preinitiation complex. Thus PC4 coactivator activity is realized in a stepwise series of events reminiscent of prokaryotic activation pathways involving conversion of inactive RNA polymerase-promoter complexes to an initiation-competent state.
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PMID:A dynamic model for PC4 coactivator function in RNA polymerase II transcription. 948 61

The tumor suppressor protein p53 regulates transcriptional programs that control the response to cellular stress. We show that distinct mechanisms exist to activate p53 target genes as revealed by marked differences in affinities and damage-specific recruitment of transcription initiation components. p53 functions in a temporal manner to regulate promoter activity both before and after stress. Before DNA damage, basal levels of p53 are required to assemble a poised RNA polymerase II initiation complex on the p21 promoter. RNA pol II is converted into an elongating form shortly after stress but before p53 stabilization. Proapoptotic promoters, such as Fas/APO1, have low levels of bound RNA pol II but undergo damage-induced activation through efficient reinitiation. Surprisingly, in a p53-dependent process key basal factors TAFII250 and TFIIB assemble into the transcription machinery in a stress- and promoter-specific manner, behaving as differential cofactors for p53 action after distinct types of DNA damage.
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PMID:p53 functions through stress- and promoter-specific recruitment of transcription initiation components before and after DNA damage. 1458 Mar 51

The p53 tumour suppressor is regulated mainly by Mdm2, an E3 ubiquitin ligase that promotes the ubiquitylation and proteasome-mediated degradation of p53. Many agents that induce p53 are inhibitors of transcription, suggesting that the p53 pathway can detect a signal(s) arising from transcriptional malfunction. Mdm2 associates with TAFII250, a component of the general transcription factor TFIID. Inactivation of TAFII250 in ts13 cells, which express a temperature-sensitive mutant of TAFII250, leads to the induction of p53 and cell cycle arrest. In the present study, we show that TAFII250 stimulates the ubiquitylation and degradation of p53 in a manner that is dependent upon Mdm2 and requires its acidic domain. Mechanistically, TAFII250 downregulates Mdm2 auto-ubiquitylation, leading to Mdm2 stabilization, and promotes p53-Mdm2 association through a recently defined second binding site in the acidic domain of Mdm2. These data provide a novel route through which TAFII250 can directly influence p53 levels and are consistent with the idea that the maintenance of p53 turnover is coupled to the integrity of RNA polymerase II transcription.
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PMID:Transcription factor TAFII250 promotes Mdm2-dependent turnover of p53. 1723 21

Induction and activation of the p53 tumour suppressor protein occurs in response to a number of cellular stresses, including disruption of RNA polymerase II-mediated transcription. Both p53 itself and its principle negative regulator, the E3 ubiquitin ligase Mdm2, are substrates for phosphorylation by the protein kinase CK2 in vitro. CK2 phosphorylates Mdm2 within its central acidic domain, a region that is critical for making a second point of contact with p53 and mediating p53 ubiquitylation and turnover. Additionally, there is evidence that CK2 interacts with, and regulates, both p53 and Mdm2 within the cell but the molecular mechanisms through which CK2-mediated regulation of the p53 response can occur are only poorly understood. Previously, we showed that the basal transcription factor TAFII250, a critical component of TFIID, can interact with Mdm2 and promote the association of the Mdm2 acidic domain with p53. In the present study, we show that immunoprecipitates of TAFII250, either from mammalian cell extracts or from baculovirus-infected cells expressing elevated levels of HA-tagged TAFII250, can phosphorylate Mdm2 in vitro within its acidic domain. We show that CK2 is tightly associated with TAFII250 and is the principal activity responsible for TAFII250-mediated phosphorylation of Mdm2. Our data fit with recent observations that phosphorylation of the acidic domain of Mdm2 stimulates its association with p53 and are consistent with a model in which recruitment of CK2 by TAFII250 may play a contributory role in the maintenance of Mdm2 phosphorylation and function.
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PMID:Transcription factor TAFII250 phosphorylates the acidic domain of Mdm2 through recruitment of protein kinase CK2. 1854

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