PCF4 encodes an RNA polymerase III transcription factor with homology to TFIIB

López-De-León, Alfredo; Librizzi, Monett D.; Puglia, Karen V.; Willis, Ian M.

doi:10.1016/0092-8674(92)90350-l

Cited by 153 publications

(102 citation statements)

References 27 publications

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“…With the pre-assembly of TFlIIB, the poll system would benefit from the pre-assembly of all the transcriptional components: RNA polymerase IH, with its 16 subunits, TEIIB, and the multisubunit assembly factor and chromatin antirepressor (1, 43) TFIIIC (6 subunits). The present work, however, suggests a multistep pathway of 'FflB assembly on the DNA, as also suggested by genetic suppression data (16,18, Lefebvre et al, submitted). Recent studies on mammalian TFIIJB appear to lead to the same conclusion as TFIIB activity was found to be separable from TBP (K.Seifart, personal communication).…”

Section: Resultsmentioning

confidence: 55%

“…Yeast TFIIIB factor is constituted of TBP and two components first identified by photocrosslinking experiments (15), the 70 kDa subunit (hereafter termed TFIB70), encoded by the BRFJ/PCF4/TDS4 gene (16,17,18), and a 90 kDa polypeptide not yet cloned. Recent data suggest that the 70 and 90 kDa polypeptides are class Im (RNA polymerase Im-specific) TBP-associated factors (TAFs) (19).…”

Section: Introductionmentioning

confidence: 99%

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Interactions between yeast TFIIIB components

Huet¹,

Conesa²,

Manaud³

et al. 1994

Nucl Acids Res

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Section: Resultsmentioning

confidence: 55%

Section: Introductionmentioning

confidence: 99%

Interactions between yeast TFIIIB components

Huet¹,

Conesa²,

Manaud³

et al. 1994

Nucl Acids Res

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“…Rather, as is supported by our data, it seems more likely that the finger region functions as a protein-protein interaction surface, much like the potential metal-binding domain found in the adenovirus E1a protein that appears to mediate contacts with TBP important for transcriptional activation (23,45). The zinc finger is conserved in TFIIB homologs from Saccharomyces cerevisiae to humans (9,52), and the TFIIB-like factor BRF1 (also known as TDS4 or PCF4), involved in transcription by RNAP III, also has the potential to form a zinc finger through N-terminal sequences (8,13,44). A mutation in BRF1 that removes residues required for finger formation does not affect cell viability or transcriptional activity in vitro, although yeast cells harboring this mutation display thermal sensitivity, suggesting that the finger plays an important but nonessential role in RNAP III transcription (13).…”

Section: Discussionmentioning

confidence: 99%

A Direct Interaction between a Glutamine-Rich Activator and the N Terminus of TFIIB Can Mediate Transcriptional Activation In Vivo

Colgan

Ashali

Manley

1995

Molecular and Cellular Biology

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Studies examining the mechanism by which transcriptional activators function have suggested that the general transcription factor IIB (TFIIB) can be a target for certain regulatory proteins. For example, we showed previously that expression of a mutant form of TFIIB can specifically inhibit activation in vivo mediated by the strong, glutamine-rich activator protein GAL4-ftzQ. Using transient cotransfection assays, we have defined the regions in both GAL4-ftzQ and TFIIB that are required for activity in vivo and provide evidence that a potential zinc finger structure at the N terminus of TFIIB is necessary for the observed functional interaction between the two proteins. Using a protein binding assay, we have demonstrated that GAL4-ftzQ can specifically interact with TFIIB in vitro. This interaction requires the same regions in both molecules necessary for function in vivo and is reduced or eliminated by mutations predicted to disrupt the zinc finger in TFIIB. These results support the idea that a direct interaction between a regulatory protein and TFIIB can be important for transcriptional activation in vivo and, combined with previous data of others, suggest that different activators can function by contacting distinct regions of TFIIB.Initiation of transcription by RNA polymerase II (RNAP II) occurs through a complex set of interactions involving promoter DNA, a set of general transcription factors, and genespecific regulatory proteins. Promoters recognized by RNAP II usually consist of two classes of sequence elements in order to accomodate these interactions. Core, or basal, promoter elements include the TATA box and the initiator, which, individually or in tandem, can support the assembly of the general transcription factors into functional preinitiation complexes (for reviews, see references 5, 56, and 64). Core promoter elements are usually surrounded by members of the second class of promoter sequences, which consists of elements recognized by gene-specific factors that function to regulate the assembly and/or activity of the general transcription machinery (35,49,58).Principally through fractionation and reconstitution of transcription in vitro, the factors constituting the RNAP II general transcription machinery have been isolated and characterized (for reviews see references 6, 17, and 70). These general, or basal, transcription factors, designated TFIIA, -B, -D, -E, -F, and -H, were once thought to all be necessary in addition to the polymerase for transcription, but studies using a variety of promoters and/or more purified systems have suggested that several of these factors may be dispensible under certain conditions (19,25,39,51,59,60). The general factors can form preinitiation complexes on core promoter elements in vitro by way of an ordered assembly pathway involving protein-DNA and protein-protein contacts (7, 61). For TATA-containing promoters, this assembly process begins with the binding of TFIID to the TATA element, which may be facilitated by TFIIA, and is followed by the association of T...

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“…Although human TFIIIB is not fully characterized, yeast TFIIIB is composed of TBP, a 70-kDa subunit (TFIIB-related factor [BRF]/PCF4/TDS4) with homology to Pol II transcription factor TFIIB (4,7,27), and a 90-kDa subunit (2,20). UV cross-linking studies have indicated that intricate conformational changes result from protein-protein interactions between promoter-bound TFIIIB and TFIIIC and that TBP unmasks a cryptic DNA-binding domain of BRF (2,20), whereas other studies have indicated interactions of BRF with an RNA Pol III-specific subunit (44).…”

Section: Discussionmentioning

confidence: 99%

Proximal Sequence Element-Binding Transcription Factor (PTF) Is a Multisubunit Complex Required for Transcription of both RNA Polymerase II- and RNA Polymerase III-Dependent Small Nuclear RNA Genes

Yoon

Murphy

Bai

et al. 1995

Molecular and Cellular Biology

121

133

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The proximal sequence element (PSE), found in both RNA polymerase II (Pol II)-and RNA Pol IIItranscribed small nuclear RNA (snRNA) genes, is specifically bound by the PSE-binding transcription factor (PTF). We have purified PTF to near homogeneity from HeLa cell extracts by using a combination of conventional and affinity chromatographic methods. Purified PTF is composed of four polypeptides with apparent molecular masses of 180, 55, 45, and 44 kDa. A combination of preparative electrophoretic mobility shift and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses has conclusively identified these four polypeptides as subunits of human PTF, while UV cross-linking experiments demonstrate that the largest subunit of PTF is in close contact with the PSE. The purified PTF activates transcription from promoters of both Pol II-and Pol III-transcribed snRNA genes in a PSE-dependent manner. In addition, we have investigated factor requirements in transcription of Pol III-dependent snRNA genes. We show that in extracts that have been depleted of TATA-binding protein (TBP) and associated factors, recombinant TBP restores transcription from U6 and 7SK promoters but not from the VAI promoter, whereas the highly purified TBP-TBPassociated factor complex TFIIIB restores transcription from the VAI but not the U6 or 7SK promoter. Furthermore, by complementation of heat-treated extracts lacking TFIIIC activity, we show that TFIIIC1 is required for transcription of both the 7SK and VAI genes, whereas TFIIIC2 is required only for transcription of the VAI gene. From these observations, we conclude (i) that PTF and TFIIIC2 function as gene-specific factors for PSE-and B-box-containing Pol III genes, respectively, (ii) that the form of TBP used by class III genes with upstream promoter elements differs from the form used by class III genes with internal promoters, and (iii) that TFIIIC1 is required for both internal and external Pol III promoters.Mammalian small nuclear RNA (snRNA) genes contain related promoter structures, but some (class II) are transcribed by RNA polymerase II (Pol II), whereas others (class III) are transcribed by RNA Pol III (reviewed in references 8, 15, 23, 30, and 37). Class II snRNA genes (e.g., U1 to U5) contain two regulatory elements in the 5Ј-flanking region: a distal sequence element (DSE) located approximately 220 bp upstream of the transcription start site, and a proximal sequence element (PSE) centered around Ϫ55. The DSE contains at least one copy of the octamer motif and functions as an upstream enhancer, whereas the PSE is an essential promoter element which functions in start site selection and may be required for accurate 3Ј-end formation (17,33,35). The promoters of class III snRNA genes (e.g., 7SK and U6) are located solely in the 5Ј-flanking region and lack intragenic control elements typical of most other class III genes (9, 29). Like their class II snRNA gene counterparts, class III snRNA genes have similar DSE and PSE configurations but additionally contain a TATA-like sequen...

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PCF4 encodes an RNA polymerase III transcription factor with homology to TFIIB

Cited by 153 publications

References 27 publications

Interactions between yeast TFIIIB components

Interactions between yeast TFIIIB components

A Direct Interaction between a Glutamine-Rich Activator and the N Terminus of TFIIB Can Mediate Transcriptional Activation In Vivo

Proximal Sequence Element-Binding Transcription Factor (PTF) Is a Multisubunit Complex Required for Transcription of both RNA Polymerase II- and RNA Polymerase III-Dependent Small Nuclear RNA Genes

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