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Stefan G E Roberts - One of the best experts on this subject based on the ideXlab platform.

  • Interaction of the TFIIB zinc ribbon with RNA polymerase II.
    Biochemical Society transactions, 2008
    Co-Authors: Laura M Elsby, Stefan G E Roberts
    Abstract:

    Transcription by RNA polymerase II requires the assembly of the general Transcription Factors at the promoter to form a pre-initiation complex. The general Transcription Factor TF (Transcription Factor) IIB plays a central role in the assembly of the pre-initiation complex, providing a bridge between promoter-bound TFIID and RNA polymerase II/TFIIF. We have characterized a series of TFIIB mutants in their ability to support Transcription and recruit RNA polymerase II to the promoter. Our analyses identify several residues within the TFIIB zinc ribbon that are required for RNA polymerase II assembly. Using the structural models of TFIIB, we describe the interface between the TFIIB zinc ribbon region and RNA polymerase II.

  • core promoter elements recognized by Transcription Factor IIB
    Biochemical Society Transactions, 2006
    Co-Authors: W Deng, Stefan G E Roberts
    Abstract:

    The general Transcription Factor TFIIB (Transcription Factor IIB) plays a critical role in the assembly of the RNA polymerase II pre-initiation complex. TFIIB can make sequence-specific DNA contacts both upstream and downstream of the TATA box. This has led to the definition of two core promoter BREs (TFIIB-recognition elements), one upstream [BRE u (upstream BRE)] and one downstream of TATA box [BRE d (downstream BRE)]. TFIIB–BRE u and TFIIB–BRE d contacts are mediated by two independent DNA-recognition motifs within the core domain of TFIIB. Both the BRE u and the BRE d modulate the Transcriptional potency of a promoter. However, the net effect of the BREs on promoter activity is dependent on the specific blend of elements present within a core promoter.

  • assembly of Transcription Factor IIB at a promoter in vivo requires contact with rna polymerase ii
    EMBO Reports, 2006
    Co-Authors: Laura M Elsby, Amanda Odonnell, Laura Green, Andrew D Sharrocks, Stefan G E Roberts
    Abstract:

    The general Transcription Factor TFIIB has a central role in the assembly of the preinitiation complex at the promoter, providing a platform for the entry of RNA polymerase II/TFIIF. We used an RNA interference (RNAi)-based system in which TFIIB expression is ablated in vivo and replaced with a TFIIB derivative that contains a silent mutation and is refractory to the RNAi. Using this approach, we found that Transcriptionally defective TFIIB amino-terminal mutants showed distinct effects on the basis of their ability to compete with wild-type TFIIB in vivo. Moreover, analysis of the TFIIB mutant derivatives by chromatin immunoprecipitation showed that promoter occupancy by TFIIB is dependent on the association with RNA polymerase II. Together, our results support a mode of preinitiation complex assembly in which TFIIB/RNA polymerase II recruitment to the promoter occurs in vivo.

  • multiple functional domains of human Transcription Factor IIB distinct interactions with two general Transcription Factors and rna polymerase ii
    Genes & Development, 1993
    Co-Authors: Stefan G E Roberts, Edio Maldonado, Xiaoqing Sun, Leu Ung Kim, Michael R Green, Danny Reinberg
    Abstract:

    Transcription Factor IIB (TFIIB) plays a pivotal role in the formation of Transcription-competent initiation complexes. TFIIB was found to interact with the TATA-binding protein, the small subunit of TFIIF, and RNA polymerase II. These interactions require distinct domains in TFIIB. Using the gel mobility-shift assay, it was found that the amino terminus of TFIIB was necessary for the formation of complexes containing RNA polymerase II and TFIIF, whereas the carboxy-terminal domain, which is composed of two imperfect direct repeats and includes a putative amphipathic alpha-helix, was sufficient for the formation of complexes containing the TATA-binding protein and TFIIB (DB complex). Protein-protein interaction analyses demonstrate that the amphipathic alpha-helix in TFIIB is important for the interaction with the TATA-binding protein. Specific residues mapping to the carboxyl terminus of the second direct repeat were found to be crucial for the interaction of TFIIB and RNA polymerase II. The interaction with the small subunit of TFIIF was mapped to the amino terminus of TFIIB, which includes a zinc finger.

Thierry Lagrange - One of the best experts on this subject based on the ideXlab platform.

  • a plant specific Transcription Factor IIB related protein pbrp2 is involved in endosperm growth control
    PLOS ONE, 2011
    Co-Authors: Emilie Cavel, Marion Pillot, Dominique Pontier, Sylvie Lahmy, Natacha Biesetheve, Danielle Vega, Daniel Grimanelli, Thierry Lagrange
    Abstract:

    General Transcription Factor IIB (TFIIB) and TFIIB-related Factor (BRF), are conserved RNA polymerase II/III (RNAPII/III) selectivity Factors that are involved in polymerase recruitment and Transcription initiation in eukaryotes. Recent findings have shown that plants have evolved a third type of B-Factor, plant-specific TFIIB-related protein 1 (pBRP1), which seems to be involved in RNAPI Transcription. Here, we extend the repertoire of B-Factors in plants by reporting the characterization of a novel TFIIB-related protein, plant-specific TFIIB-related protein 2 (pBRP2), which is found to date only in the Brassicacea family. Unlike other B-Factors that are ubiquitously expressed, PBRP2 expression is restricted to reproductive organs and seeds as shown by RT-PCR, immunofluorescence labelling and GUS staining experiments. Interestingly, pbrp2 loss-of-function specifically affects the development of the syncytial endosperm, with both parental contributions required for wild-type development. pBRP2, is the first B-Factor to exhibit cell-specific expression and regulation in eukaryotes, and might play a role in enforcing bi-parental reproduction in angiosperms.

  • Transcription Factor IIB tfIIB related protein pbrp a plant specific member of the tfIIB related protein family
    Molecular and Cellular Biology, 2003
    Co-Authors: Thierry Lagrange, Dominique Pontier, Mohamedali Hakimi, Florence Courtois, Jean Pierre Alcaraz, Didier Grunwald, Eric Lam, Silva Lerbsmache
    Abstract:

    Although it is now well documented that metazoans have evolved general Transcription Factor (GTF) variants to regulate their complex patterns of gene expression, there is so far no information regarding the existence of specific GTFs in plants. Here we report the characterization of a ubiquitously expressed gene that encodes a bona fide novel Transcription Factor IIB (TFIIB)-related protein in Arabidopsis thaliana. We have shown that this protein is the founding member of a plant-specific TFIIB-related protein family named pBrp (for plant-specific TFIIB-related protein). Surprisingly, in contrast to common GTFs that are localized in the nucleus, the bulk of pBrp proteins are bound to the cytoplasmic face of the plastid envelope, suggesting an organelle-specific function for this novel class of TFIIB-related protein. We show that pBrp proteins harbor conditional proteolytic signals that can target these proteins for rapid turnover by the proteasome-mediated protein degradation pathway. Interestingly, under conditions of proteasome inhibition, pBrp proteins accumulate in the nucleus. Together, our results suggest a possible involvement of these proteins in an intracellular signaling pathway between plastids and the nucleus. Our data provide the first evidence for an organelle-related evolution of the eukaryotic general Transcription machinery.

  • New core promoter element in RNA polymerase II-dependent Transcription: sequence-specific DNA binding by Transcription Factor IIB
    Genes & development, 1998
    Co-Authors: Thierry Lagrange, Danny Reinberg, Achillefs N. Kapanidis, Hong Tang, Richard H. Ebright
    Abstract:

    A sequence element located immediately upstream of the TATA element, and having the consensus sequence 5'-G/C-G/C-G/A-C-G-C-C-3', affects the ability of Transcription Factor IIB to enter Transcription complexes and support Transcription initiation. The sequence element is recognized directly by the Transcription Factor IIB. Recognition involves alpha-helices 4' and 5' of IIB, which comprise a helix-turn-helix DNA-binding motif. These observations establish that Transcription initiation involves a fourth core promoter element, the IIB recognition element (BRE), in addition to the TATA element, the initiator element, and the downstream promoter element, and involves a second sequence-specific general Transcription Factor, IIB, in addition to Transcription Factor IID.

Seishi Murakami - One of the best experts on this subject based on the ideXlab platform.

  • rmp a novel rna polymerase ii subunit 5 interacting protein counteracts transactivation by hepatitis b virus x protein
    Molecular and Cellular Biology, 1998
    Co-Authors: Dorjbal Dorjsuren, Yong Lin, Takahiro Nomura, Wenxiang Wei, Tatsuya Yamashita, Naoyuki Hayashi, Seishi Murakami
    Abstract:

    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.

  • hepatitis b virus x protein is a Transcriptional modulator that communicates with Transcription Factor IIB and the rna polymerase ii subunit 5
    Journal of Biological Chemistry, 1997
    Co-Authors: Yong Lin, Takahiro Nomura, Jaehun Cheong, Dorjbal Dorjsuren, Katsuhira Iida, Seishi Murakami
    Abstract:

    Hepatitis B virus X protein (HBx) transactivates viral and cellular genes through a wide variety of cis-elements. However, the mechanism is still obscure. Our finding that HBx directly interacts with RNA polymerase II subunit 5 (RPB5), a common subunit of RNA polymerases, implies that HBx directly modulates the function of RNA polymerase (Cheong, J. H., Yi, M., Lin, Y., and Murakami, S. (1995) EMBO J. 14, 142-150). In this context, we examined the possibility that HBx and RPB5 interact with other general Transcription Factors. HBx and RPB5 specifically bound to Transcription Factor IIB (TFIIB) in vitro, both of which were detected by either far-Western blotting or the glutathione S-transferase-resin pull-down assay. Delineation of the binding regions of these three proteins revealed that HBx, RPB5, and TFIIB each has two binding regions for the other two proteins. Co-immunoprecipitation using HepG2 cell lysates that express HBx demonstrated trimeric interaction in vivo Some HBx substitution mutants, which had severely impaired transacting activity, exhibited reduced binding affinity with either TFIIB or RPB5 in a mutually exclusive manner, suggesting that HBx transactivation requires the interactions of both RPB5 and TFIIB. These results indicated that HBx is a novel virus modulator that facilitates Transcriptional initiation by stabilizing the association between RNA polymerase and TFIIB through communication with RPB5 and TFIIB.

Anny Usheva - One of the best experts on this subject based on the ideXlab platform.

  • Transcription Factor IIB acetylates itself to regulate Transcription
    Nature, 2003
    Co-Authors: Chu H Choi, Makoto Hiromura, Anny Usheva
    Abstract:

    Acetylation is a well-known regulatory post-translational modification, but a biological function for acetylation in regulating basal Transcription Factors has not been reported. Here we show that the general Transcription Factor TFIIB, which is required for the initiation of eukaryotic polymerase II Transcription, is acetylated. TFIIB is also an autoacetyltransferase, although it shares no sequence homology with any known acetyltransferases. In the absence of other enzymes, it binds acetyl-coenzyme A (acetyl-CoA), and catalyses the transfer of the acetyl group onto a specific lysine residue (K238). Both recombinant and cellular TFIIB can autoacetylate, markedly stabilizing the interaction between TFIIB and Transcription Factor TFIIF and activating Transcription in vitro and in cells. A K238A mutant, which cannot be autoacetylated, does not show this activation of Transcription. Our findings suggest that there is a regulatory pathway controlling acetylation of TFIIB, and they link acetyl-CoA with basal gene Transcription.

  • tata binding protein independent initiation yy1 tfIIB and rna polymerase ii direct basal Transcription on supercoiled template dna
    Cell, 1994
    Co-Authors: Anny Usheva
    Abstract:

    Abstract YY1 is a zinc finger Transcription Factor whose DNA-binding motif exhibits the properties of an initiator element. Only three Factors were required to direct specific basal Transcription on a supercoiled template DNA carrying the YY1 initiator: YY1, general Transcription Factor IIB, and RNA polymerase II. This minimal in vitro reaction did not require the TATA-binding protein (TBP). We propose that, under appropriate conditions, YY1 can function like TBP, as a Factor that binds to the core promoter and recruits the polymerase to the initiation complex.

Danny Reinberg - One of the best experts on this subject based on the ideXlab platform.

  • New core promoter element in RNA polymerase II-dependent Transcription: sequence-specific DNA binding by Transcription Factor IIB
    Genes & development, 1998
    Co-Authors: Thierry Lagrange, Danny Reinberg, Achillefs N. Kapanidis, Hong Tang, Richard H. Ebright
    Abstract:

    A sequence element located immediately upstream of the TATA element, and having the consensus sequence 5'-G/C-G/C-G/A-C-G-C-C-3', affects the ability of Transcription Factor IIB to enter Transcription complexes and support Transcription initiation. The sequence element is recognized directly by the Transcription Factor IIB. Recognition involves alpha-helices 4' and 5' of IIB, which comprise a helix-turn-helix DNA-binding motif. These observations establish that Transcription initiation involves a fourth core promoter element, the IIB recognition element (BRE), in addition to the TATA element, the initiator element, and the downstream promoter element, and involves a second sequence-specific general Transcription Factor, IIB, in addition to Transcription Factor IID.

  • multiple functional domains of human Transcription Factor IIB distinct interactions with two general Transcription Factors and rna polymerase ii
    Genes & Development, 1993
    Co-Authors: Stefan G E Roberts, Edio Maldonado, Xiaoqing Sun, Leu Ung Kim, Michael R Green, Danny Reinberg
    Abstract:

    Transcription Factor IIB (TFIIB) plays a pivotal role in the formation of Transcription-competent initiation complexes. TFIIB was found to interact with the TATA-binding protein, the small subunit of TFIIF, and RNA polymerase II. These interactions require distinct domains in TFIIB. Using the gel mobility-shift assay, it was found that the amino terminus of TFIIB was necessary for the formation of complexes containing RNA polymerase II and TFIIF, whereas the carboxy-terminal domain, which is composed of two imperfect direct repeats and includes a putative amphipathic alpha-helix, was sufficient for the formation of complexes containing the TATA-binding protein and TFIIB (DB complex). Protein-protein interaction analyses demonstrate that the amphipathic alpha-helix in TFIIB is important for the interaction with the TATA-binding protein. Specific residues mapping to the carboxyl terminus of the second direct repeat were found to be crucial for the interaction of TFIIB and RNA polymerase II. The interaction with the small subunit of TFIIF was mapped to the amino terminus of TFIIB, which includes a zinc finger.

  • cloning of a human gene encoding the general Transcription initiation Factor IIB
    Nature, 1991
    Co-Authors: William S Lane, Danny Reinberg
    Abstract:

    Transcription Factor IIB (TFIIB) has a central role in Transcription of class II genes. The purification of the human TFIIB protein and isolation of a complementary DNA encoding TFIIB activity is reported here. The sequence of TFIIB, which seems to be encoded by a single gene, contains a repeated motif, in addition to a motif with similarity to the prokaryotic sigma-Factors. The recombinant protein expressed in bacteria substituted for all the functions attributed to the human TFIIB protein.