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

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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

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

The HIV-1 trans-activator Tat increases the rate of transcription from the HIV-1 LTR promoter through the stem-loop-containing TAR RNA. To analyze the mechanisms of Tat action, a cell-free trans-activation system with no preincubation has been developed. Recombinant Tat specifically increased the level of a long runoff transcript but not a promoter-proximal transcript in a TAR-dependent fashion. These observations and the result of pulse-chase experiments support strongly the hypothesis that Tat enhances the ability of RNA polymerase to elongate over longer distances. Increased levels of the purified cellular factor TFIIF, essential for initiation and also implicated in elongation of transcription, obviated trans-activation by Tat by increasing the basal (Tat-independent) activity. However, another elongation factor, ATN/TFIIS, showed synergistic activation with Tat. An antiserum against a recombinant form of the large subunit of TFIIF (RAP 74) preferentially suppressed the activated level of transcription exerted by Tat. We propose the hypothesis that Tat acts as a processivity factor on RNA polymerase II in an analogous manner to TFIIF.
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PMID:HIV-1 Tat acts as a processivity factor in vitro in conjunction with cellular elongation factors. 155 13

We used an in vitro assay system based on HeLa cell core transcription components to examine transcript elongation by RNA polymerase II on either naked DNA or chromatin templates as a function of the three known elongation factors, IIS, TFIIF, and TFIIX. We demonstrate for the first time that mammalian RNA polymerase II can achieve physiological elongation rates on naked DNA templates in vitro. The addition of TFIIF alone gave this rate, although IIS was required to minimize the block to elongation at intrinsic termination sites. However, IIS and TFIIF provided only a slight increase in the very poor elongation efficiency of RNA polymerase II on chromatin templates. The addition of TFIIX to reactions containing IIS and TFIIF reduced the elongation rate on naked DNA templates but slightly increased the elongation efficiency on chromatin. The ability of elongation factors either separately or in combination to stimulate transcription on naked DNA and chromatin templates was also examined.
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PMID:Factor-stimulated RNA polymerase II transcribes at physiological elongation rates on naked DNA but very poorly on chromatin templates. 161 65

All genes encoding proteins in eukaryotes are transcribed by RNA polymerase II. The first step in analyzing transcriptional regulation requires understanding the general mechanisms of RNA polymerase II-specific gene transcription. The basal promoter, a template containing a TATA box devoid of upstream regulatory sequences, has been used to identify and characterize the factors which, together with RNA polymerase II, govern transcription in mammalian systems: TFIIA, TFIIB, TFIID, TFIIE, TFIIF, TFIIG, TFIIH, and TFIIJ. Interactions between regulatory transcription factors and basal elements of the transcriptional machinery affect the transcriptional rate in a positive or negative fashion. As these multiple proteins are purified, and their coding sequences are isolated, we come closer to reproducing these processes in vitro with pure components, and thus to elucidating the complex interactions among them.
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PMID:The basic RNA polymerase II transcriptional machinery. 163 39

Two new factors required for transcription of class II genes have been identified. These factors, TFIIH and TFIIJ, were required together with the previously described general factors (TFIIA, TFIIB, TFIID, TFIIE, and TFIIF) and RNA polymerase II for transcription of different class II genes. TFIIH was extensively purified, and the activity appeared to coelute with polypeptides of 33 and 95 kDa. The role of TFIIH and TFIIJ in preinitiation complex assembly was analyzed using mobility shift assays. It was found that TFIIH and TFIIJ association with the preinitiation complex was ordered and required the previous assembly of a preinitiation complex intermediate containing factors IID, IIB, IIF, IIE, and RNA polymerase II. A model for the ordered assembly of the general factors and RNA polymerase II is presented.
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PMID:Factors involved in specific transcription by mammalian RNA polymerase II. Identification and characterization of factor IIH. 173 73

At least six chromatographically resolvable general transcription factors may participate in accurate initiation by RNA polymerase II in HeLa cell-derived systems. TFIIF (also termed FC, RAP30/74 and beta/gamma) can bind directly to RNA polymerase II in solution and decrease the affinity of RNA polymerase II for nonspecific DNA. From studies on the kinetics of transcription initiation, on the composition of transcription initiation complexes fractionated by acrylamide gel electrophoresis, and on template competition experiments, TFIIF is known to act at an intermediate stage in initiation complex formation. It acts after TFIID firmly associates with DNA, but coincidentally with or immediately after RNA polymerase II binding to DNA, and before the recruitment of factor TFIIE. TFIIF may or may not have DNA helicase activity. The small subunit (RAP30) of TFIIF has been cloned and shows some amino-acid sequence homology to bacterial sigma factors. We have partially sequenced the RAP74 protein from purified HeLa cells, cloned its complementary DNA and shown that its translation product can interact with RAP30 in vitro as well as in vivo. The cDNA predicts an amino-acid sequence that lacks obvious DNA or RNA helicase motifs. It has regions rich in charged amino acids, including segments containing a higher content of acidic amino acids than are found in strong transcriptional activators such as VP16.
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PMID:Characterization of cDNA for the large subunit of the transcription initiation factor TFIIF. 173 83

RAP30/74 (also known as TFIIF, beta gamma and FC is one of several general factors required for initiation by RNA polymerase II. The small RAP30 subunit of RAP30/74 binds directly to polymerase and appears structurally and functionally homologous to bacterial sigma factors in their RNA polymerase-binding region. RAP30/74 or recombinant RAP30 suppresses nonspecific binding of RNA polymerase II to DNA and is required for RNA polymerase II to assemble stably into a preinitiation complex containing promoter DNA and the general factors TFIID, TFIIA and TFIIB; both RAP30 and RAP74 are physical components of the preinitiation complex. A complementary DNA encoding human RAP30 has been isolated, and here we report the isolation of a cDNA encoding human RAP74. RAP30 and RAP74 produced in Escherichia coli can be used in place of natural human RAP30/74 to direct accurate transcription initiation by RNA polymerase II in vitro.
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PMID:A cDNA encoding RAP74, a general initiation factor for transcription by RNA polymerase II. 173 84

We have purified from whole cell extracts of Saccharomyces cerevisiae a protein which alters the elongation properties of yeast RNA polymerase II in vitro. The yeast elongation stimulatory activity, YES, correlates with a 116-kDa protein and acts on both yeast and Drosophila RNA polymerase II during transcription of double-stranded dC-tailed templates. The stimulatory activity is specific for RNA polymerase II since it has no significant effect on the elongation properties of yeast RNA polymerase I or yeast RNA polymerase III. Elongation by RNA polymerase II can be stimulated by RNase H on dC-tailed templates; however, the stimulatory activity of YES is not due to RNase H activity. YES does not stimulate RNA polymerase II in the presence of manganese ions and therefore is distinct from the smaller elongation factor, S-II or DmS-II. YES is most similar to Drosophila factor 5 (mammalian TFIIF, or RAP30/74), an initiation factor that is also able to increase the rate of elongation of RNA polymerase II.
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PMID:Identification and purification of a yeast protein that affects elongation by RNA polymerase II. 185 Nov 72

Transcription factor TFIIB is a ubiquitous factor required for transcription initiation by RNA polymerase II. Previous studies have suggested that TFIIB serves as a bridge between the "TATA"-binding factor (TFIID) and RNA polymerase II during preinitiation complex assembly and, more recently, that TFIIB can be a target of acidic activators. We have purified TFIIB to homogeneity, shown that activity resides in a 33-kDa polypeptide, and obtained cDNAs encoding functional TFIIB. TFIIB contains a region with amino acid sequence similarity to a highly conserved region of prokaryotic sigma factors. This is consistent with analogous functions for these factors in promoter recognition by RNA polymerases and with similar findings for TFIID, TFIIE, and TFIIF/RAP30. Like TFIID, TFIIB contains both a large imperfect repeat that could contribute an element of symmetry to the folded protein and clusters of basic residues that could interact with acidic activator domains. These findings argue for a common origin of TFIIB, TFIID, and other general transcription factors and for the evolutionary segregation of complementary functions.
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PMID:Sequence of general transcription factor TFIIB and relationships to other initiation factors. 194 68


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