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

The carboxyl-terminal domain of RNA polymerase II contains a tandemly repeated heptapeptide sequence. Previous work has shown that this sequence is phosphorylated at multiple sites by a template-associated protein kinase, in a reaction that is closely associated with the initiation of RNA synthesis. We have purified this kinase to apparent homogeneity from human (HeLa) cells. The purified kinase phosphorylates native RNA polymerase II only in the presence of DNA and the general transcription factors TFIID (TBP), TFIIB, and TFIIF. Two kinase components are required for full activity: a catalytic component and a DNA-binding regulatory component. The regulatory component has been identified as Ku autoantigen, based on the molecular weights of its component polypeptides, its DNA-binding properties, and its reactivity with anti-Ku monoclonal antibodies. The Ku autoantigen recruits the catalytic component of the kinase to the template. Ku autoantigen has been previously proposed to interact with DNA by a characteristic bind-and-slide mechanism. This mode of interaction may provide a mechanism for targeting the kinase to the transcription complex and other DNA-bound substrates.
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PMID:Ku autoantigen is the regulatory component of a template-associated protein kinase that phosphorylates RNA polymerase II. 146 19

Resolution of whole cell extract through two chromatographic steps yields a single protein fraction requiring only the addition of TFIID for the initiation of transcription at RNA polymerase II promoters. This approach allows the convenient generation of RNA polymerase II transcription systems from Saccharomyces cerevisiae, human lymphocytes, and Schizosaccharomyces pombe. TFIIDs from all three organisms are interchangeable among all three systems. The S. cerevisiae and Sch. pombe systems support effects of acidic activator proteins, provided a further protein fraction from S. cerevisiae is supplied. This further fraction is distinct from the mediator of transcriptional activation described previously and represents a second component in addition to general initiation factors that may facilitate a response to acidic activators.
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PMID:Simple derivation of TFIID-dependent RNA polymerase II transcription systems from Schizosaccharomyces pombe and other organisms, and factors required for transcriptional activation. 150 79

The TATA-box-binding protein, first noted for its association with the general transcription factor TFIID, has recently been shown to be required for transcription by all three classes of nuclear RNA polymerase found in eukaryotes. As such, it plays a unique and pivotal role in gene expression in higher organisms.
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PMID:The TATA-binding protein: a central role in transcription by RNA polymerases I, II and III. 150 19

The major class of vertebrate genes transcribed by RNA polymerase (EC 2.7.7.6) III, which includes 5S rRNA genes, tRNA genes, and the adenovirus VA genes, is characterized by split internal promoters and no absolute dependence upon specific upstream sequences. Fractionation experiments have shown that transcription of such genes requires two general RNA polymerase III-specific factors, TFIIIB and TFIIIC. We now demonstrate that a third general factor is also employed by these genes. This is the TATA-box-binding protein originally identified as being a component of the general RNA polymerase II transcription factor TFIID. This protein is involved in the transcription by RNA polymerase III of every template tested, even though the promoters of VA and most vertebrate tRNA and 5S rRNA genes do not contain recognizable TATA elements.
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PMID:A role for the TATA-box-binding protein component of the transcription factor IID complex as a general RNA polymerase III transcription factor. 154 92

Regulation of expression of protein-encoding genes in eukaryotes is frequently mediated by sequence-specific transcription factors that control the activities of the basal factors and RNA polymerase II. Basal factors have been considered to be essential for all polymerase II promoters. Studies of the basal factor requirements for transcription from the immunoglobulin heavy chain gene (IgH) core promoter and the adenovirus major late gene core promoter (MLP) suggest that this paradigm is too simple. Basal transcription from the IgH promoter was reconstituted by TFIID, TFIIB, TFIIF, and polymerase, whereas basal transcription from the MLP is highly dependent upon TFIIE in addition to the above factors. Two novel protein activities, referred to as 700 kd and 90 kd, further stimulated the basal reaction from the MLP. Thus, these data indicate that not all basal factors are in fact general.
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PMID:Promoter specificity of basal transcription factors. 154 7

A Drosophila cDNA encoding a human transcription factor TFIIB homologue was isolated by PCR methods. The deduced amino acid sequence indicates 85% sequence similarity with human TFIIB, and the corresponding cDNA product expressed in Escherichia coli is interchangeable with human TFIIB for both basal and GAL4-VP16-induced transcription. Structural motifs including the direct repeats, basic repeats, and sigma sequence similarities are well conserved among Drosophila, human, and Xenopus TFIIB. However, the N-terminal region of each direct repeat is less conserved among the three species, suggesting the presence of two structural subdomains in the direct repeat. Moreover, the amino acid changes in the N-terminal subdomain produce altered positions of the conserved amino acids between the direct repeats. An overall similarity in general structural features between TFIIB and TFIID tau (the TATA-binding subunit of TFIID) was previously noted. However, in contrast to the sequence divergence reported for the N-terminal domains of TFIID tau from different species, the N-terminal sequence of TFIIB was highly conserved among the species. This suggests that TFIIB has a more rigid structure, consistent with its function as a "bridging" protein between TFIID and RNA polymerase II. Further implications of the TFIIB structure are discussed.
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PMID:Isolation and characterization of a cDNA encoding Drosophila transcription factor TFIIB. 155 90

Assembly of RNA polymerase II with the core region of TATA box-containing promoters requires the action of the TATA factor and four transcription factors designated alpha, beta gamma, delta, and epsilon, which have each been purified to near homogeneity from rat liver. Evidence from previous studies argues that alpha and beta gamma play a crucial role in delivering RNA polymerase II to the promoter (Conaway, R. C., Garrett, K. P., Hanley, J. P., and Conaway, J. W. (1991) Proc. Natl. Acad. Sci. U. S. A. 88, 6205-6209). Here we describe the interaction of transcription factor delta with preinitiation intermediates assembled in the presence of either recombinant yeast TFIID or the high molecular mass, endogenous TATA factor tau from rat liver (Conaway, J. W., Hanley, J. P., Garrett, K. P., and Conaway, R. C. (1991) J. Biol. Chem. 266, 7804-7811). Results of template challenge experiments argue that delta enters the preinitiation complex through interactions with multiple components of the transcription apparatus. We observe that, in the presence of recombinant TFIID, delta interacts stably with the preinitiation complex only in the presence of RNA polymerase II, alpha, and beta gamma, whereas, in the presence of tau, delta is capable of interacting stably with the Initial Complex independently of RNA polymerase II. Results of restriction site protection experiments reveal that delta and epsilon promote binding of the transcription apparatus to the Initiator element and support the model that RNA polymerase II assembles at the core promoter in at least two discrete steps, first "touching down" near the TATA element and finally extending its interaction downstream to encompass the cap site.
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PMID:Mechanism of assembly of the RNA polymerase II preinitiation complex. Transcription factors delta and epsilon promote stable binding of the transcription apparatus to the initiator element. 157 84

The adenovirus type 2 IVa2 promoter lacks a conventional TATA element yet directs transcription from two closely spaced initiation sites. To define elements required for in vitro transcription of this promoter, IVa2 templates carrying 5' deletions or linker-scanning mutations were transcribed in HeLa whole-cell extracts and the transcripts were analyzed by primer extension. Mutation of the sequence centered on position -47, which is specifically recognized by a cellular factor, reduced the efficiency of IVa2 transcription two- to threefold, whereas mutation of the sequence centered on position -30 selectively impaired utilization of the minor in vivo initiation site. Utilization of the major in vivo site was decreased no more than fivefold by deletion of all sequences upstream of position -15. By contrast, mutation of the region from +13 to +19 or of the initiation region severely impaired IVa2 transcription. The sequence spanning the initiation sites was sufficient to direct accurate initiation by RNA polymerase II from the major in vivo site. Thus, the two initiation sites of the IVa2 promoter are specified by independent elements, and a downstream element is the primary determinant of efficient transcription from both of these sites. The downstream element identified by mutational analysis altered the TATA element-like sequence TATAGAAA lying at positions +21 to +14 in the coding strand. Transcription from the wild-type IVa2 promoter was severely inhibited when endogenous TFIID was inactivated by mild heat treatment. Exogenous human TATA-binding protein (TBP) synthesized in Escherichia coli restored specific IVa2 transcription from both initiation sites when added to such heat-treated extracts. Although efficient IVa2 transcription requires both the downstream TATA sequence and active TFIID, bacterially synthesized TBP also stimulated the low level of IVa2 transcription observed when the TATA sequence was mutated to a sequence that failed to bind TBP.
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PMID:Anatomy of an unusual RNA polymerase II promoter containing a downstream TATA element. 158 75

Fractionation of a transcription-competent HeLa cell extract on a column containing one copy of the heptamer repeat (YSPTSPS) present in the carboxy-terminal domain (CTD) of the largest subunit of RNA polymerase II resulted in the loss of transcriptional activity. Fractionation of the extracts on columns containing mutations of the heptamer repeat was without effect. Such transcriptionally inactive extracts regained their ability to specifically transcribe different class II promoters upon the addition of human TFIID, recombinant yeast TATA-binding protein (TBP), or proteins bound to the column. Fractionation of RNA polymerase II on columns containing human or yeast TBP resulted in the specific retention of the nonphosphorylated form of RNA polymerase II. The phosphorylated form of the enzyme was unable to interact with TBP. The specific interaction of RNA polymerase II with TBP was mediated by the CTD of RNA polymerase II.
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PMID:Specific interaction between the nonphosphorylated form of RNA polymerase II and the TATA-binding protein. 159 81

The RNA polymerase II large subunit carboxy-terminal domain (CTD) plays a role in transcription initiation, but its mechanism of action is not well understood. We have investigated the function of the SRB2 gene, which was isolated as a dominant suppressor of CTD truncation mutations. The allele specificity of this suppressor indicates that SRB2 and the CTD are involved in the same function. Indeed, cells lacking SRB2 and cells lacking a large portion of the CTD exhibit the same set of conditional growth phenotypes and exhibit very similar defects in gene expression in vivo. The SRB2 protein is a novel transcription factor that has an important role in basal and activated transcription in vitro and is essential for efficient establishment of the transcription initiation apparatus. Template commitment experiments suggest that SRB2 becomes physically associated with the transcription initiation complex. We find that SRB2 binds specifically to TFIID. As SRB2 and the RNA polymerase II CTD are involved in the same function, these results reveal a functional link between the CTD and the TATA-binding factor. This study implicates the CTD in recruitment of RNA polymerase II to the transcription initiation complex.
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PMID:A novel transcription factor reveals a functional link between the RNA polymerase II CTD and TFIID. 159 82


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