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

---

Query: EC:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A set of deletion mutants of human RNA polymerase II-associated protein (RAP) 30, the small subunit of transcription factor IIF (TFIIF; RAP30/74), was constructed to map functional domains. Mutants were tested for accurate transcriptional activity, RAP74 binding, and TFIIB binding. Transcription assays indicate the importance of both N- and C-terminal sequences for RAP30 function. RAP74 binds to the N-terminal region of RAP30 between amino acids 1 and 98. TFIIB binds to an overlapping region of RAP30, localized to amino acids 1-176 (amino acids 27-152 comprise a minimal binding region). The C-terminal region of RAP74 (amino acids 358-517) binds directly and independently to TFIIB. Interestingly, RAP74 blocks TFIIB-RAP30 binding, both by binding TFIIB and by binding RAP30. When the TFIIF complex is intact, therefore, TFIIB-TFIIF contact is maintained through RAP74. If the TFIIB-RAP30 interaction is physiologically important, the TFIIF complex must dissociate within some transcription complexes.
...
PMID:RNA polymerase II-associated protein (RAP) 74 binds transcription factor (TF) IIB and blocks TFIIB-RAP30 binding. 866 60

The yeast RNA polymerase III (pol III) general transcription factor TFIIIB is composed of three subunits; the TATA-binding protein (TBP)1, the TFIIB-related factor (BRF1), and a third factor termed TFIIIB90 or B". Here we report the purification of yeast TFIIIB90, cloning of the gene encoding TFIIIB90, and reconstitution of TFIIIB from recombinant polypeptides. The TFIIIB90 open reading frame encodes a 68-kDa polypeptide and has no obvious similarity to any other known protein sequences. The gene encoding TFIIIB90 is essential for viability of yeast. Using recombinant TFIIIB subunits, we found that TFIIIB90 interacts weakly with TBP in the absence of BRF1, and that this interaction is enhanced at least 25-fold by BRF1. In addition, TFIIIB90 showed pol III specificity as it could not interact with the pol II-specific TFIIB-TBP-DNA complex. To localize the regions of the TBP-DNA complex that interact with BRF1 and TFIIIB90, we tested whether the pol II factors TFIIA and TFIIB interfered with the binding of BRF1 and TFIIIB90 to TBP-DNA. Our results suggest that the binding sites for BRF1 and TFIIIB90 on TBP-DNA both overlap the binding sites for TFIIA and TFIIB.
...
PMID:Cloning and functional characterization of the gene encoding the TFIIIB90 subunit of RNA polymerase III transcription factor TFIIIB. 866 56

We investigated the role of TFIIH in transcription by RNA polymerase II (pol II) in vivo by microinjection of antibodies against this factor into Xenopus oocytes. Five different antibodies directed against four subunits of TFIIH were tested for effects on transcription of coinjected human immunodeficiency virus type 2 and c-myc templates. Each of these antibodies severely reduced the efficiency of elongation through human immunodeficiency virus type 2 and c-myc terminator elements. In contrast, an anti-TFIIB antibody did not inhibit elongation. Anti-TFIIH antibodies also had a much smaller inhibitory effect on total transcription than did anti-TFIIB or anti-pol II large subunit. Three inhibitors of TFIIH kinase activity, H-7, H-8, and dichlororibofuranosylbenzimidazole (DRB), inhibited elongation similarly to anti-TFIIH antibodies. These results strongly suggest a role for TFIIH in the stimulation of transcriptional elongation in vivo.
...
PMID:TFIIH functions in regulating transcriptional elongation by RNA polymerase II in Xenopus oocytes. 866 44

The general transcription factor IIB (TFIIB) is required for RNA polymerase II transcription in eukaryotes. It provides a physical link between the TATA-binding protein (TBP) and the RNA polymerase and is a component previously suggested to respond to transcriptional activators in vitro. In this report, we compare the yeast (Saccharomyces cerevisiae) and human forms of the protein in yeast cells to study their functional differences. We demonstrate that human TFIIB fails to functionally replace yeast TFIIB in yeast cells. By analyzing various human-yeast hybrid TFIIB molecules, we show that a 14-amino-acid region at the amino terminus of the first repeat of yeast TFIIB plays an important role in determining species specificity in vivo. In addition, we identify four amino acids in this region that are critical for an amphipathic helix unique to yeast TFIIB. By site-directed mutagenesis analyses we demonstrate that these four amino acids are important for yeast TFIIB's activity in vivo. Finally, we show that mutations in the species-specific region of yeast TFIIB can differentially affect the expression of genes activated by different activators in vivo. These results provide strong evidence suggesting that yeast TFIIB is involved in the process of transcriptional activation in living cells.
...
PMID:Identifying a species-specific region of yeast TF11B in vivo. 866 81

Negative co-factor 2 (NC2) regulates transcription of the class II genes through binding to TFIID and inhibition of pre-initiation complex formation. We have isolated and cloned NC2, and investigated the molecular mechanism underlying repression of transcription. NC2 consists of two subunits, termed NC2alpha and NC2beta, the latter of which is identical to Dr1. The NC2 subunits dimerize and bind to TATA binding protein (TBP)-promoter complexes via histone fold domains of the H2A-H2B type. Repression of basal transcription requires the histone fold and carboxy-terminal domains of the NC2 subunits. Several mechanisms probably contribute to transcriptional repression. Binding of NC2 inhibits association of TFIIB with TBP-promoter complexes. NC2 binds directly to DNA, and binding of NC2 to TBP-promoter complexes affects the conformation of DNA, which could be one cause for the inhibition of TFIIB. In addition, multimerization of repressor-TBP complexes on DNA might inhibit the assembly of the pre-initiation complex. We suggest that binding of the repressor to TRP-promoter complexes establishes a mechanism that controls the rate of transcription by RNA polymerase II.
...
PMID:A mechanism for repression of class II gene transcription through specific binding of NC2 to TBP-promoter complexes via heterodimeric histone fold domains. 867 Aug 11

The X protein of hepatitis B virus (HBV) coactivates activators bearing potent (mostly acidic) activation domains. Here, we investigated the molecular mechanisms of this coactivation. We show that pX interacts with general transcription factors TFIIB and TFIIH, as well as with the potent activation domain of VP16. TFIIB interacts with both pX and VP16 simultaneously. In addition, the RNA polymerase II enzyme itself binds to pX. By reducing the activity of cellular coactivators, through squelching, we intensify the dependence of the activator on pX-mediated coactivation. Squelching is essentially diminished in the presence of pX, both in vivo and in vitro. The target of pX in this activity is the template-bound activator, and not the squelcher. Furthermore, by following transcription in a TAF-deprived reaction, we demonstrate absolute dependence of the activator on the activity of pX. We propose that pX coactivates transcription by substituting cellular coactivators in activator-preinitiation complex interactions.
...
PMID:pX, the HBV-encoded coactivator, interacts with components of the transcription machinery and stimulates transcription in a TAF-independent manner. 867 Aug 43

Recessive mutations in the SSU71, SSU72 and SSU73 genes of Saccharomyces cerevisiae were identified as either suppressors or enhancers of a TFIIB defect (sua7-1) that confers both a cold-sensitive growth phenotype and a downstream shift in transcription start site selection. The SSU71 (TFG1) gene encodes the largest subunit of TFIIF and SSU72 encodes a novel protein that is essential for cell viability. Here we report that SSU73 is identical to RPB9, the gene encoding the 14.2 kDa subunit of RNA polymerase II. The ssu73-1 suppressor compensates for both the growth defect and the downstream shift in start site selection associated with sua7-1. These effects are similar to those of the ssu71-1 suppressor and distinct from the ssu72-1 enhancer. The ssu73-1 allele was retrieved and sequenced, revealing a nonsense mutation at codon 107. Consequently, ssu73-1 encodes a truncated form of Rpb9 lacking the C-terminal 16 amino acids. This Rpb9 derivative retains at least partial function since the ssu73-1 mutant exhibits none of the growth defects associated with rpb9 null mutants. However, in a SUA7+ background, ssu73-1 confers the same upstream shift at ADH1 as an rpb9 null allele. This suggests that the C-terminus of Rpb9 functions in start site selection and demonstrates that the previously observed effects of rpb9 mutations on start site selection are not necessarily due to complete loss of function. These results establish a functional interaction between TFIIB and the Rpb9 subunit of RNA polymerase II and suggest that these two components of the preinitiation complex interact during transcription start site selection.
...
PMID:Functional interaction between TFIIB and the Rpb9 (Ssu73) subunit of RNA polymerase II in Saccharomyces cerevisiae. 869 96

All pairwise interactions of RNA polymerase II and general transcription factors (TF) IIB, E, F, and H have been quantitated by surface plasmon resonance with the use of a Ni2+ chelate on the sensor surface where necessary to attain higher sensitivity. Only 4 of 10 possible interactions were found above the detection limit: TFIIB, -E, and -F binding to RNA polymerase II and TFIIE binding to TFIIH. These four interactions constitute a minimal set for the formation of a transcription initiation complex and may represent the primary interactions involved in assembly of the complex. Point mutations in TFIIB that alter the location of transcription start sites in vivo markedly diminished the affinity of TFIIB binding to RNA polymerase II. Protein blotting revealed an interaction between the largest subunit of TFIIE and third largest subunit of TFIIH, which may be responsible for TFIIE binding to TFIIH.
...
PMID:A minimal set of RNA polymerase II transcription protein interactions. 870 41

Contact between a transcriptional activator and one or more components of the RNA polymerase II transcription initiation machinery is generally believed important for activators to function. Several different molecular targets have been suggested for direct contact by herpes simplex virus virion protein VP16, including the general initiation factor TFIIB. In this report we have used several strategies to critically assess this interaction between VP16 and TFIIB. Affinity columns of VP16 bound TFIIB activity from HeLa cell extracts and the binding was reduced by mutations in the activation domain of VP16. In assays of direct binding, VP16 bound recombinant human TFIIB but not Drosophila or yeast TFIIB. Unlike binding from an extract, however, we found that the interaction between VP16 and recombinant human TFIIB was not affected by mutations in VP16 that reduce transactivation. Point mutations within human TFIIB that reduce transactivation by VP16 have been shown to reduce VP16 binding, but we show here that these same mutations critically affect both the important TBP-TFIIB interaction and the ability of TFIIB to support activator-independent basal transcription in vitro. Taken together our results suggest more evidence is needed to support the notion that TFIIB is a functionally important target for the activator VP16.
...
PMID:Characterization of the interaction between the acidic activation domain of VP16 and the RNA polymerase II initiation factor TFIIB. 871 May 3

The binding of TBP (TFIID) to the TATA box has been considered to direct promoter recognition and pre-initiation complex formation because it is the first event leading to basal transcription by RNA polymerase II. Here, we analyse the binding of yeast TBP to a consensus TATAAA box and two point mutations, TAAAAA (inactive) and TATATA (active). Despite the fact that the TAAAAA sequence does not support transcription in vitro, yeast TBP binds the three sequences showing, in this sense, only a limited sequence specificity. However, the TBP-TAAAAA complex cannot be recognised by other basal transcription factors, in particular by TFIIB. DNase I footprinting patterns of the TBP-TAAAAA complex are different from those observed in functional TBP-TATA box complexes, indicating that, most likely, it is a different spatial arrangement of the TBP-DNA complex that prevents formation of the TFIIB-TBP-TAAAAA complex, also seriously impairing entry of TFIIA to the complex. DNA deformability of the A/T-rich sequences appears to be an important determinant in the formation of a productive TBP-TATA complex. These results indicate that the transcriptional competence of A/T-rich sequences is determined not only by TBP binding, but also by the ability of other basal transcription factors to recognise the preformed TBP-DNA complexes.
...
PMID:TBP binds the transcriptionally inactive TA5 sequence but the resulting complex is not efficiently recognised by TFIIB and TFIIA. 876 Aug 79


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

---