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Query: UNIPROT:P23193 (transcription elongation factor)
 739 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In addition to polynucleotide polymerization, DNA polymerases and bacterial RNA polymerase can also remove nucleotides from the growing end of nucleic acid chains. For DNA polymerases this activity is an important factor in establishing fidelity in DNA synthesis. This report describes a novel in vitro activity of RNA polymerase II whereby it cleaves an RNA chain contained within an active elongation complex. These elongation complexes are arrested at a previously identified, naturally occurring transcriptional pause site in a human gene. The new 3'-end revealed by this cleavage remains associated with an active elongation complex and is capable of being extended by RNA polymerase II. Nascent RNA cleavage is evident after removal of free nucleotides and is dependent upon a divalent metal cation and transcription elongation factor SII. This function of SII could be important in its function as an activator of transcription elongation. It is also possible that the transcript cleavage activity of RNA polymerase II represents a proofreading function of the enzyme.
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PMID:Elongation factor-dependent transcript shortening by template-engaged RNA polymerase II. 137 Dec 80

We have examined elongation by RNA polymerase II initiated at a promoter and have identified two classes of elongation complexes. Following initiation at a promoter, all polymerase molecules enter an abortive mode of elongation. Abortive elongation is characterized by the rapid generation of short transcripts due to pausing of the polymerase followed by termination of transcription. Termination of the early elongation complexes can be suppressed by the addition of 250 mM KCl or 1 mg of heparin per ml soon after initiation. Elongation complexes of the second class carry out productive elongation in which long transcripts can be synthesized. Productive elongation complexes are derived from early paused elongation complexes by the action of a factor which we call P-TEF (positive transcription elongation factor). P-TEF is inhibited by 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole at concentrations which have no effect on the initiation of transcription. By using templates immobilized on paramagnetic particles, we show that isolated preinitiation complexes lack P-TEF and give rise to transcription complexes which can carry out only abortive elongation. The ability to carry out productive elongation can be restored to isolated transcription complexes by the addition of P-TEF after initiation. A model is presented which describes the role of elongation factors in the formation and maintenance of elongation complexes. The model is consistent with the available in vivo data concerning control of elongation and is used to predict the outcome of other potential in vitro and in vivo experiments.
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PMID:Control of formation of two distinct classes of RNA polymerase II elongation complexes. 156 41

Purified RNA polymerase II terminates transcription in vitro at sites within genes which also block transcript elongation in vivo. Studies on a termination site within the first intron of the human histone H3.3 gene have shown that transcription elongation factor SII can promote read-through at this site when the polymerase initiates transcription from a promoter in the presence of the accessory initiation factors. Using 3'-extended templates to direct specific initiation by purified RNA polymerase II, we show here that purified SII is sufficient to effect read-through of this terminator by the purified polymerase alone. Thus, the interaction of purified SII with an elongation complex containing only the polymerase, the template, and the nascent transcript can change the termination properties of RNA polymerase II and can effect read-through of a region that blocks elongation in the cell.
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PMID:Purified elongation factor SII is sufficient to promote read-through by purified RNA polymerase II at specific termination sites in the human histone H3.3 gene. 238 69

Genomic sequences for the large subunit of human RNA polymerase II corresponding to a part of the fifth exon were inserted into an expression vector at the carboxy-terminal end of the beta-galactosidase gene. The in-frame construct produced a 125-kilodalton fusion protein, containing approximately 10 kilodaltons of the large subunit of RNA polymerase II and 116 kilodaltons of beta-galactosidase. The purified bacterially produced fusion protein inhibited specific transcription from the adenovirus type 2 major late promoter, while beta-galactosidase had no effect. This effect of the fusion protein was during RNA elongation, not at the level of initiation, resembling the faithfully initiated but incomplete transcripts produced with purified factors in the absence of SII. Similarly, monoclonal antibody 2-7B, which reacts with the RNA polymerase II region represented in the fusion protein, inhibited specific transcription at the level of elongation in a whole-cell extract. Both monoclonal antibody 2-7B and the fusion protein, although unable to inhibit purified RNA polymerase II in a nonspecific transcription assay, selectively blocked the stimulation elicited by transcription elongation factor SII on the activity of the purified enzyme in vitro. This suggests that the fusion protein traps the SII in nonstimulatory interactions and that antibody 2-7B inhibits SII binding to RNA polymerase II. Thus, this suggests that an SII-binding contact required for specific RNA elongation resides within the fifth exon region of the largest RNA polymerase II subunit.
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PMID:Transcription elongation factor SII interacts with a domain of the large subunit of human RNA polymerase II. 314 7

TFIIS is a transcription elongation factor that binds to RNA polymerase II and allows it to transcribe through a variety of transcriptional blockages by inducing cleavage near the 3' end of the nascent transcript. Although this cleavage reaction plays a key role in the process of reactivation of transcription by TFIIS, the exact mechanism by which TFIIS promotes readthrough by RNA polymerase II is not completely understood. We therefore undertook a systematic mutagenesis of the C-terminal half of TFIIS (delta TFIIS) to evaluate the contribution of charged residues in this region to induce transcript cleavage and promote readthrough in vitro. Twenty-two delta TFIIS alanine-scanning mutants were constructed by substitution of alanine for each amino acid in clusters of charged residues in the C-terminal half of HeLa TFIIS. The ability to induce transcript cleavage and readthrough of these mutants was tested in vitro using RNA polymerase II ternary elongation complexes arrested at a block to elongation. This alanine-scanning mutagenesis analysis allowed the identification of regions or residues important for the activity of TFIIS. Many of the mutants were reduced alike in both cleavage and readthrough activities. However, in several cases there was no simple correlation between these activity reductions.
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PMID:Alanine-scanning mutagenesis of human transcript elongation factor TFIIS. 757 53

Production of full-length runoff transcripts in vitro and functional mRNA in vivo is sensitive to the drug 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB). We previously proposed the existence of an activity, P-TEF (positive transcription elongation factor) that functions in a DRB-sensitive manner to allow RNA polymerase II elongation complexes to efficiently synthesize long transcripts (Marshall, N. F. and Price, D. H. (1992) Mol. Cell. Biol. 12, 2078-2090). We have fractionated nuclear extracts of Drosophila melanogaster Kc cells and identified three activities, P-TEFa, factor 2, and P-TEFb, that are directly involved in reconstructing DRB-sensitive transcription. P-TEFb is essential for the production of DRB-sensitive long transcripts in vitro, while P-TEFa and factor 2 are stimulatory. P-TEFb activity is associated with a protein comprising two polypeptide subunits with apparent molecular masses of 124 and 43 kDa. Using a P-TEFb-dependent transcription system, we show that P-TEFb acts after initiation and is the limiting factor in the production of long run-off transcripts.
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PMID:Purification of P-TEFb, a transcription factor required for the transition into productive elongation. 775 73

Saccharomyces cerevisiae has a TFIIS-related transcription elongation factor, originally called P37 (Sawadogo, M., Sentenac, A., and Fromageot, P. (1979) J. Biol. Chem. 255, 12-15; Nakanishi, T., Nakano, A., Nomura, K., Sekimizu, K., and Natori, S. (1992) J. Biol. Chem. 267, 13200-13204), which binds directly to RNA polymerase II and stimulates read-through of intrinsic blocks to elongation. To elucidate functional features of this protein:protein interaction, we tested the ability of several forms of RNA polymerase II to respond to either full-length or an amino-terminal truncation of TFIIS. The variants of the polymerase differed in the structure of the carboxyl-terminal domain of the largest subunit or lacked two of the smaller subunits. No differences in ability to recognize intrinsic blocks to elongation or to read through them in response to either form of TFIIS were detected among these variants. Furthermore, ternary complexes containing each variant form of RNA polymerase cleave the 3' end of the nascent transcripts in response to TFIIS, a reaction previously reported for mammalian and Drosophila TFIIS (Kassavetis, G. A., and Geiduschek, E. P. (1993) Science 259, 944-945) and likely to be important in TFIIS function. Thus the carboxyl-terminal domain of the largest subunit and subunits four and seven of the polymerase, required in vivo, are not required in vitro for recognition of intrinsic blocks to elongation, read-through in response to TFIIS, or TFIIS-stimulated cleavage of the nascent transcript.
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PMID:Purified yeast RNA polymerase II reads through intrinsic blocks to elongation in response to the yeast TFIIS analogue, P37. 828 47

Human RNA polymerase II is shown to be associated with a 3'-->5' exonuclease activity that removes nucleoside 5'-monophosphates from the 3' end of the transcripts in isolated ternary complexes. This activity is stimulated by SII, a protein that acts as a transcription elongation factor in vitro. In addition, we show that another transcription factor, TFIIF, stimulates a competing pyrophosphorolysis reaction. These findings raise interesting questions about the roles of these activities in vivo, including the possibility that this RNA polymerase may proofread the nascent transcript.
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PMID:Identification of a 3'-->5' exonuclease activity associated with human RNA polymerase II. 838 34

Transcription arrest plays a role in regulating the expression of a number of genes, including the murine adenosine deaminase (ADA) gene. We have previously identified two prominent arrest sites at the 5' end of the ADA gene: one in the first exon and one in the first intron (J. W. Innis and R. E. Kellems, Mol. Cell. Biol. 11:5398-5409, 1991). Here we report the functional characterization of the intron 1 arrest site, located 137 to 145 nucleotides downstream of the cap site. We have determined, using gel filtration, that the intron 1 arrest site is a stable RNA polymerase II pause site and that the transcription elongation factor SII promotes read-through at this site. Additionally, the sequence determinants for the pause are located within a 37-bp fragment encompassing this site (+123 to +158) and can direct transcription arrest in an orientation-dependent manner in the context of the ADA and adenovirus major late promoters. Specific point mutations in this region increase or decrease the relative pausing efficiency. We also show that the sequence determinants for transcription arrest can function when placed an additional 104 bp downstream of their natural position.
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PMID:Functional analysis of a stable transcription arrest site in the first intron of the murine adenosine deaminase gene. 847 37

Few of the auxiliary factors that assist RNA polymerase II in the process of mRNA chain elongation have been identified. We have isolated a novel cDNA, Tceb1l, from mouse and human sources that encodes a 163-amino-acid protein and shows a significant level of identity with a recently identified RNA polymerase II transcription elongation factor, p15. Tceb1l is highly conserved throughout vertebrates and maps to mouse chromosome 11 and to the syntenic region of human chromosome 5q31. Tceb1l shows a restricted pattern of expression in the early mouse embryo, where it is absent from the neurectoderm; later Tceb1l is expressed in the caudal region of the neural tube, followed by widespread expression in many tissues, including the brain and spinal cord. These observations are consistent with Tceb1l being an RNA polymerase II elongation factor and suggest that Tceb1l/p15-like peptides may be a new family of proteins that influence RNA elongation.
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PMID:A novel cDNA with homology to an RNA polymerase II elongation factor maps to human chromosome 5q31 (TCEB1L) and to mouse chromosome 11 (Tceb1l). 853 64


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