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

TATA-binding protein (TBP)-associated factors (TAFs) in TFIID are required for activator proteins to stimulate transcription, but the mechanism by which TAFs function is poorly understood. To study how TAFs participate in transcriptional activation by the Epstein-Barr virus activator Zta, we used agarose gel electrophoresis and DNase I footprinting to compare transcription complex assembly in reactions with either TFIID or TBP in the presence and absence of wild-type Zta or a deletion of Zta lacking its activation domain. A stable complex of promoter DNA with Zta, TFIIA, and TFIID rapidly formed on a template with Zta-binding sites. Zta stimulation of stable complex formation required TAFs as well as the Zta activation domain and TFIIA. The Zta activation domain also induced a TAF-dependent DNA-protein interaction near and downstream of the transcription star site. Stable complexes formed within 1 min supported activated transcription when RNA polymerase II and the remaining general transcription factors were subsequently added. This rapid assembly of a stable Zta-TFIIA-TFIID-promoter complex is probably a significant component of the mechanism by which TAFs and the Zta activation domain cooperate to stimulate transcription.
 ...
PMID:A mechanism for TAFs in transcriptional activation: activation domain enhancement of TFIID-TFIIA--promoter DNA complex formation. 792 93

We report here that the largest subunit of yeast RNA polymerase II contains an acidic domain that is similar to acidic activators of transcription. This domain includes the highly conserved homology box H. A hybrid protein containing this acidic domain fused to the DNA-binding domain of GAL4 is a potent activator of transcription in the yeast Saccharomyces cerevisiae. Interestingly, mutations that reduce the upstream activating activity of this acidic domain also abolish the normal function of RNA polymerase II. Such functional defects can be rescued by the acidic activation domains of VP16 and GAL4 when inserted into the mutant derivatives of RNA polymerase II. We further show that this acidic domain of RNA polymerase II interacts directly with two general transcription factors, the TATA-binding protein and TFIIB, and that the acidic activation domain of VP16 can compete specifically with the acidic domain of the RNA polymerase for these interactions. We discuss the implications of this finding for the mechanisms of transcriptional activation in eucaryotes.
 ...
PMID:A highly conserved domain of RNA polymerase II shares a functional element with acidic activation domains of upstream transcription factors. 793 66

The rate at which the TATA-binding protein (TBP) interacts with the TATA element and promotes transcription by RNA polymerase II was determined in yeast cells. A TBP derivative with altered TATA-element specificity was rapidly induced, and transcription from promoters with appropriately mutated TATA elements was measured. Without a functional activator protein, basal transcription was observed only after a lag of several hours. In contrast, GCN4-activated transcription occurred rapidly upon induction of the TBP derivative. These results suggest that accessibility of TBP to the chromatin template in vivo is rate limiting and that activation domains increase recruitment of TBP to the promoter.
 ...
PMID:Increased recruitment of TATA-binding protein to the promoter by transcriptional activation domains in vivo. 793 64

The human general transcription factor IIF (TFIIF) is required for an accurate transcription initiation by RNA polymerase II and shares some analogous features with the sigma subunit of bacterial RNA polymerase. As an attempt to analyze the function of TFIIF, we examined its effect on bacterial transcription in vitro. TFIIF significantly enhanced the initiation of transcription by the bacterial RNA polymerase while other general transcription factors, TATA-binding protein, TFIIB, and TFIIE, did not. The enhancement of the bacterial transcription was ascribed to the 74 kDa subunit of TFIIF (RAP74). RAP74 had an activity of enhancing the binding of the bacterial RNA polymerase to the promoter. The enhancing activity of RAP74 depended on a low molar ratio of the RNA polymerase to the template DNA. The action of RAP74 in the bacterial transcription may be related to a possible regulatory role of RAP74 in the eukaryotic transcription initiation.
 ...
PMID:Enhancement of bacterial transcription initiation in vitro by the 74 kDa subunit of human general transcription factor IIF (RAP74). 794 16

Previously, we have isolated mutants of Saccharomyces cerevisiae primarily defective in the transcription of 35S rRNA genes by RNA polymerase I and have identified a number of genes (RRN genes) involved in this process. We have now cloned the RRN6 and RRN7 genes, determined their nucleotide sequences, and found that they encode proteins of calculated molecular weights of 102,000 and 60,300, respectively. Extracts prepared from rrn6 and rrn7 mutants were defective in in vitro transcription of rDNA templates. We used extracts from strains containing epitope-tagged wild-type Rrn6 or Rrn7 proteins to purify protein components that could complement these mutant extracts. By use of immunoaffinity purification combined with biochemical fractionation, we obtained a highly purified preparation (Rrn6/7 complex), which consisted of Rrn6p, Rrn7p, and another protein with an apparent molecular weight of 66,000, but which did not contain the TATA-binding protein (TBP). This complex complemented both rrn6 and rrn7 mutant extracts. Template commitment experiments carried out with this purified Rrn6/7 complex and with rrn6 mutant extracts have demonstrated that the Rrn6/7 complex does not bind stably to the rDNA template by itself, but its binding is dependent on the initial binding of some other factor(s) and that the Rrn6/7 complex is required for the formation of a transcription-competent preinitiation complex. These observations are discussed in comparison to in vitro rDNA transcription systems from higher eukaryotes.
 ...
PMID:RRN6 and RRN7 encode subunits of a multiprotein complex essential for the initiation of rDNA transcription by RNA polymerase I in Saccharomyces cerevisiae. 795 1

Basic mechanisms of transcription initiation are conserved from yeast to man. However, in contrast to genes transcribed by RNA polymerases II and III, ribosomal gene transcription by RNA polymerase I (Pol I) is species-specific. Promoter selectivity is mediated by SL1/TIF-IB, a multiprotein complex containing the TATA-binding protein (TBP) and TBP-associated factors (TAFs) which bind to DNA and nucleate the assembly of initiation complexes. Using a human cell line that expresses epitope-tagged yeast TBP, we have isolated a chimeric complex consisting of yeast TBP and human TAFs which faithfully promotes human rDNA transcription in vitro. This result argues that specific interactions between TBP and Pol I-specific TAFs have been evolutionarily conserved between distant species. In addition, this finding also underscores the importance of TAFs in determining promoter selectivity of Pol I.
 ...
PMID:Yeast TBP can replace its human homologue in the RNA polymerase I-specific multisubunit factor SL1. 796 4

The bacteriophage T4 middle-mode transcription factor MotA consists of two domains of approximately equal size. The C-terminal domain has been shown to contain the DNA-binding elements of the molecule, and the N-terminal domain appears to interact with RNA polymerase. A 12.5-kDa fragment of the C-terminal domain (MotCF), comprising residues 105-211 of MotA, was found to be suitable for structural studies by NMR. The 1H and 15N assignments have been made for MotCF by using two-dimensional homonuclear and heteronuclear experiments. A secondary structure has been determined which consists of a six-stranded antiparallel beta-pleated sheet with three alpha-helical segments. The secondary structure of MotCF has a clear similarity to one half of the eukaryotic TATA-binding protein (TBP), which is an intramolecular dimer. Therefore, MotCF may be related to a monomeric ancestral protein of TBP. TBP binds its target DNA in the minor groove by specific interactions with hydrophobic and aromatic residues on the exposed sheet surface of the protein. Similar residues are also present on the beta-sheet surface of MotCF, suggesting that it too binds DNA in the minor groove.
 ...
PMID:The DNA-binding domain of the MotA transcription factor from bacteriophage T4 shows structural similarity to the TATA-binding protein. 797 94

In Saccharomyces cerevisiae, two components of the RNA polymerase III (Pol III) general transcription factor TFIIIB are the TATA-binding protein (TBP) and the B-related factor (BRF), so called because its amino-terminal half is homologous to the Pol II transcription factor IIB (TFIIB). We have cloned BRF genes from the yeasts Kluyveromyces lactis and Candida albicans. Despite the large evolutionary distance between these species and S. cerevisiae, the BRF proteins are conserved highly. Although the homology is most pronounced in the amino-terminal half, conserved regions also exist in the carboxy-terminal half that is unique to BRF. By assaying for interactions between BRF and other Pol III transcription factors, we show that it is able to bind to the 135-kD subunit of TFIIIC and also to TBP. Surprisingly, in addition to binding the TFIIB-homologous amino-terminal portion of BRF, TBP also interacts strongly with the carboxy-terminal half. Deleting two conserved regions in the BRF carboxy-terminal region abrogates this interaction. Furthermore, TBP mutations that selectively inhibit Pol III transcription in vivo impair interactions between TBP and the BRF carboxy-terminal domain. Finally, we demonstrate that BRF but not TFIIB binds the Pol III subunit C34 and we define a region of C34 necessary for this interaction. These observations provide insights into the roles performed by BRF in Pol III transcription complex assembly.
 ...
PMID:Conserved functional domains of the RNA polymerase III general transcription factor BRF. 799 25

Regulation of transcription by RNA polymerase II in eukaryotic cells requires both basal and accessory factors, which interact through specific protein-DNA or protein-protein interactions. The high mobility group 1 protein (HMG1) was previously demonstrated to be a nonhistone chromatin-associated protein, which selectively recognizes cruciform DNA rather than a specific primary sequence element. During our investigations of proteins that interact with TFIID, we found that purified mammalian HMG1, as well as recombinant human HMG1, can interact with TATA-binding protein (TBP) in the presence of a TATA box-containing oligonucleotide to form a specific HMG1.TBP.promoter complex. This complex prevents TFIIB binding to TBP and consequently blocks formation of the preinitiation complex. In contrast, TFIIA can compete with HMG1 for binding to TBP. In an in vitro transcription assay reconstituted with highly purified or recombinant general factors, HMG1 is able to inhibit transcription by RNA polymerase II over 30-fold. As expected, addition of TFIIA can partially reverse this repression in a concentration-dependent manner. These results demonstrate that HMG1, a chromatin-associated protein, has the potential to act as a TBP-dependent negative transcription factor and may provide an important link between chromatin structure and the modulation of class II gene transcription.
 ...
PMID:The high mobility group protein HMG1 can reversibly inhibit class II gene transcription by interaction with the TATA-binding protein. 800 19

Unlike genes transcribed by RNA polymerases II and III, transcription by RNA polymerase I is highly species-specific. Ribosomal promoter selectivity is brought about by a multisubunit transcription factor (SL1/TIF-IB) which consists of the TATA-binding protein (TBP) and three TBP-associated factors (TAFs). To determine the basis for the inability of SL1/TIF-IB to recognize heterologous rDNA, the transcriptional properties and the subunit composition of the murine and the human factor, as well as a chimeric complex containing epitope-tagged human TBP and murine TAFs, have been compared. We show that TBP can be exchanged between the human and mouse factor indicating that the variable N-terminal domain of TBP does not play a significant role in rDNA promoter selectivity. Instead, DNA binding is brought about by the TAFs. UV crosslinking experiments demonstrate that binding to the ribosomal gene promoter is mediated by two TAFs (TAFI48 and TAFI68) which have the same electrophoretic mobility in the human and mouse factor. The largest TAF is different in both species and is suggested to play a role in the species-specific assembly of productive preinitiation complexes. Thus, evolutionary changes of rDNA promoter sequences have been accompanied by changes in specific TAFs.
 ...
PMID:TBP-associated factors interact with DNA and govern species specificity of RNA polymerase I transcription. 801 60


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>