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Query: UNIPROT:P20226 (TATA-binding protein)
 1,297 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Transcription initiation in Archaea (archaebacteria) resembles the eucaryotic process, having been shown to involve TATA box-like promoter regions as well as TATA-binding protein and TFIIB homologs. However, little is known about transcription regulation in archaea. We have previously demonstrated that transcripts of nifHDK2 genes, encoding Methanosarcina barkeri nitrogenase, are present in N2-grown cells but not in ammonium-grown cells, indicating that nif transcription is regulated by the nitrogen source. In this study, we detected proteins in M. barkeri cell extracts that bind specifically to DNA containing the putative promoter region of nifHDK2. No binding was found when the promoter region was deleted from the DNA. A competition assay showed that the methyl coenzyme M reductase (mcr) promoter region DNA and the nifH2 promoter region DNA competed for a common factor(s). There was no binding to the nifH2 promoter region by extracts of ammonium-grown cells, but there was binding by these extracts to promoter regions for mcr genes, which are presumably constitutively expressed. Interestingly, extracts of ammonium-grown cells inhibited binding to the nif promoter region by extracts of N2-grown cells. Fractionation of extracts of ammonium-grown cells with a heparin-Sepharose column resolved them into a fraction eluting at 0 M NaCl, which inhibited binding by extracts of N2-grown cells, and a fraction eluting at 0.5 to 0.75 M NaCl, which showed binding to the promoter region. These results are congruent with a model for regulation of nif gene expression in M. barkeri in which a substance present in ammonium-grown cells inhibits DNA binding by a transcription-associated protein or proteins.
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PMID:Interactions between the promoter regions of nitrogenase structural genes (nifHDK2) and DNA-binding proteins from N2- and ammonium-grown cells of the archaeon Methanosarcina barkeri 227. 957 59

Previous studies have established that Archaea possess a homolog of the eukaryotic basal transcription factor TFIIB, termed TFB, that functions together with the archaeal TATA-binding protein (TBP) to direct transcription by RNA polymerase. Here, we analyze the strong S. shibatae viral (SSV) T6 promoter and show that the region of DNA immediately upstream of the TATA-like A box influences promoter strength. When placed upstream of the much weaker rRNA promoter, this sequence makes it as strong as the T6 promoter. By using a combination of approaches, we show that S. shibatae TFB mediates sequence-specific interactions with DNA flanking the A box. Thus, sequence-specific DNA recognition by TFB and TBP are codeterminants of promoter strength in Archaea.
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PMID:Sequence-specific DNA binding by the S. shibatae TFIIB homolog, TFB, and its effect on promoter strength. 966 Sep 23

Brf is the TFIIB-related component of Saccharomyces cerevisiae RNA polymerase III transcription initiation factor IIIB (TFIIIB). An extensive set of Brf fragments has been examined for the abilities to assemble the TFIIIB-DNA complex and recruit RNA polymerase III to accurately initiate transcription. The principal TFIIIB-assembly function of Brf was found to be contributed by a C-proximal segment spanning amino acids 435 to 545, while the principal transcription-directing function was contributed by a segment of its N-proximal, TFIIB-homologous half. The diverse activities of Brf were also reconstituted from combined fragments. The fragments spanning amino acids 1 to 282 and 284 to 596 were found to assemble into TFIIIB-DNA and TFIIIC-TFIIIB-DNA complexes that were very stable, transcriptionally highly active, and indistinguishable (by in vitro footprinting) from complexes formed with intact Brf. The proximities of the individual halves of split Brf to DNA were extensively mapped by photochemical cross-linking of the TFIIIB-DNA complex. We also identified sites of interaction of Brf fragments with TATA-binding protein (TBP), taking advantage of a recently completed mutational analysis of the TBP surface. The constraints established by these analyses specify a global model of the functional segments of Brf and how they fit into the structure of the TFIIIB-DNA complex.
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PMID:Functional and structural organization of Brf, the TFIIB-related component of the RNA polymerase III transcription initiation complex. 971 Jun 42

To modulate transcription, regulatory factors communicate with basal transcription factors and/or RNA polymerases in a variety of ways. Previously, it has been reported that RNA polymerase II subunit 5 (RPB5) is one of the targets of hepatitis B virus X protein (HBx) and that both HBx and RPB5 specifically interact with general transcription factor IIB (TFIIB), implying that RPB5 is one of the communicating subunits of RNA polymerase II involved in transcriptional regulation. In this context, we screened for a host protein(s) that interacts with RPB5. By far-Western blot screening, we cloned a novel gene encoding a 508-amino-acid-residue RPB5-binding protein from a HepG2 cDNA library and designated it RPB5-mediating protein (RMP). Expression of RMP mRNA was detected ubiquitously in various tissues. Bacterially expressed recombinant RMP strongly bound RPB5 but neither HBx nor TATA-binding protein in vitro. Endogenous RMP was immunologically detected interacting with assembled RPB5 in RNA polymerase in mammalian cells. The central part of RMP is responsible for RPB5 binding, and the RMP-binding region covers both the TFIIB- and HBx-binding sites of RPB5. Overexpression of RMP, but not mutant RMP lacking the RPB5-binding region, inhibited HBx transactivation of reporters with different HBx-responsive cis elements in transiently transfected cells. The repression by RMP was counteracted by HBx in a dose-dependent manner. Furthermore, RMP has an inhibitory effect on transcriptional activation by VP16 in the absence of HBx. These results suggest that RMP negatively modulates RNA polymerase II function by binding to RPB5 and that HBx counteracts the negative role of RMP on transcription indirectly by interacting with RPB5.
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PMID:RMP, a novel RNA polymerase II subunit 5-interacting protein, counteracts transactivation by hepatitis B virus X protein. 981 40

The action of oestrogen hormones is mediated through the oestrogen receptor (ER), a member of a large superfamily of nuclear receptors that function as ligand-activated transcription factors. Sequence-specific transcription factors, including the nuclear receptor superfamily, are thought to interact either directly or indirectly with general transcription factors to regulate transcription. Although numerous studies have focused on the identification of potential co-activators interacting with isolated trans-activation domains of ER, few have investigated the mechanisms by which ER transmits its signal to the basal transcription machinery. We show that ER does not stabilize the binding of the TATA-box binding protein (TBP) of the TFIID complex, or of TFIIB to the promoter, although a stable ER-TBP-TFIIB-promoter complex was detected, suggesting that ER, TBP and TFIIB might interact with each other to form a complex to the promoter. We also demonstrate that ER binds specifically to TFIIB, a key component of the preinitiation complex. Affinity chromatography with immobilized deletion mutants of ER maps a TFIIB interaction region that encompasses the DNA-binding domain. The addition of excess TFIIB to transcription reactions in vitro did not, however, affect the magnitude of transcriptional activation by ER. These results indicate that, in contrast with current models, ER does not activate transcription by increasing the rate of assembly of TFIIB into the transcription complex. An increased concentration of TFIIB was unable, by itself, to overcome the requirement for ER. By using an immobilized promoter-template assay employing nuclear extract from HeLa cells, recombinant human ER increased the stable association of subsequent components of the transcription machinery (TFIIE and TFIIF), in correlation with ER-induced transcription. Our results suggest that ER acts, in an early step, during or immediately after the formation of template-committed complexes containing TFIIB, favouring the recruitment of one or more components of the basic transcription machinery as well as co-activators.
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PMID:Oestrogen receptor facilitates the formation of preinitiation complex assembly: involvement of the general transcription factor TFIIB. 984 76

Eukaryotic transcriptional activators may function, at least in part, to facilitate the assembly of the RNA polymerase II (pol II) preinitiation complex at the core promoter region through their interaction with a subset of components of the basal transcription machinery. Previous studies have shown that artificial tethering of TATA-binding protein (TBP) to the promoter region is sufficient to stimulate pol II transcription in yeast. To test whether this phenomenon is a general one in eukaryotic pol II transcription, the DNA-binding domain of yeast GAL4 was fused to either Xenopus laevis TBP or TFIIB in order to enable these factors to be efficiently positioned near the transcription start site in a GAL4-binding site-dependent manner. We found that GAL4-xTBP as well as GAL4-xTFIIB directed an increased level of transcription without involvement of the transcriptional activator, suggesting that incorporation of these basal factors into a preinitiation complex (PIC) is a major rate-limiting step accelerated by activator proteins in metazoans. These results show that transcription activation by artificial recruitment of basal transcription machinery can be observed in general among eukaryotic transcription both in vivo and in vitro. Furthermore, failure of recovery of transcription by adding GAL4-xTFIIB after depletion of endogenous TBP with TATA oligo competitor suggests that recruitment of TBP cannot be bypassed for Pol II transcription.
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PMID:Recruitment of TBP or TFIIB to a promoter proximal position leads to stimulation of RNA polymerase II transcription without activator proteins both in vivo and in vitro. 1006 20

A mammalian protein highly homologous to TATA-binding protein (TBP) has been identified and cloned. The recombinant mammalian TBP-related factor binds to the TATA box of the Ad-MLP and forms stable complexes with TFIIB on the promoter DNA. The mammalian TBP-related factor is able to substitute for TBP in supporting transcription by RNA polymerase II in an in vitro reconstituted system.
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PMID:Transcriptional functions of a new mammalian TATA-binding protein-related factor. 1022 42

A model is proposed in which bending and wrapping of DNA around RNA polymerase causes untwisting of the DNA helix at the RNA polymerase catalytic center to stimulate strand separation prior to initiation. During elongation, DNA bending through the RNA polymerase active site is proposed to lower the energetic barrier to the advance of the transcription bubble. Recent experiments with mammalian RNA polymerase II along with accumulating evidence from studies of Escherichia coli RNA polymerase indicate the importance of DNA bending and wrapping in transcriptional mechanisms. The DNA-wrapping model describes specific roles for general RNA polymerase II transcription factors (TATA-binding protein [TBP], TFIIB, TFIIF, TFIIE, and TFIIH), provides a plausible explanation for preinitiation complex isomerization, suggests mechanisms underlying the synergy between transcriptional activators, and suggests an unforseen role for TBP-associating factors in transcription.
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PMID:DNA bending and wrapping around RNA polymerase: a "revolutionary" model describing transcriptional mechanisms. 1035 58

The general transcription factor IIB (TFIIB) plays an essential role in transcription of protein-coding genes by eukaryotic RNA polymerase II. We previously identified a yeast TFIIB mutant (R64E) that exhibited increased activity in the formation of stable TATA-binding protein-TFIIB-DNA (DB) complexes in vitro. We report here that the homologous human TFIIB mutant (R53E) also displayed increased activity in DB complex formation in vitro. Biochemical analyses revealed that the increased activity of the R64E mutant in DB complex formation was associated with an altered protease sensitivity of the protein and an enhanced interaction between the N-terminal region and the C-terminal core domain. These results suggest that the intramolecular interaction in yeast TFIIB stabilizes a productive conformation of the protein for the association with promoter-bound TATA-binding protein.
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PMID:An interaction between the N-terminal region and the core domain of yeast TFIIB promotes the formation of TATA-binding protein-TFIIB-DNA complexes. 1043 92

Mutation of glutamate 62 to lysine in yeast transcription factor (TF) IIB (Sua7) causes a cold-sensitive phenotype. This mutant also leads to preferential transcription of downstream start sites on some promoters in vivo. To explore the molecular nature of these phenotypes, the TFIIB E62K mutant was characterized in vitro. The mutant interacts with TATA-binding protein normally. In three different assays, the mutant can also interact with RNA polymerase II and recruit it and the other basal transcription factors to a promoter. Despite the ability to assemble a transcription complex, the TFIIB E62K protein is severely defective in transcription in vitro. Therefore, the role of TFIIB must be more than simply bridging TATA-binding protein and polymerase at the promoter. We propose that the region around Glu-62 in yeast TFIIB plays a role in start site selection, perhaps mediating a conformational change in the polymerase or the DNA during the search for initiation sites. This step may be related to the yeast-specific spacing between TATA elements and start sites since mutations of the corresponding glutamate in mammalian TFIIB do not produce a similar effect.
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PMID:Evidence that transcription factor IIB is required for a post-assembly step in transcription initiation. 1046 20


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