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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 present the cloning and sequence characterization of a HeLa cDNA encoding the SII transcription elongation factor. This cDNA clone is distinct from those previously isolated from a human kidney cDNA library [Yoo et al., Nucleic Acids Res. 19 (1991) 1073-1079]. Southern analysis suggests that more than one gene may exist for SII in the human genome. A comparison of deduced amino acid sequences for SII-related proteins from a variety of eukaryotes demonstrates very high similarity, especially within the C-terminal domain.
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PMID:Characterization of a HeLa cDNA clone encoding the human SII protein, an elongation factor for RNA polymerase II. 137 7

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

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

Previously, we characterized a rat cDNA for testis-specific transcription elongation factor S-II (SII-T1) (Q. Xu et al., J. Biol. Chem. 269, 3100-3103 (1994)). Here, we isolated a 335-bp fragment of the cDNA for mouse SII-T1, and used it to examine the expression of the SII-T1 gene in the testis by in situ hybridization. The results indicated that the SII-T1 gene is expressed exclusively in spermatocytes, showing no appreciable expression in spermatogonia, spermatids, or Leydig cells. RT-PCR experiments using testis RNA from W/Wv mutant mice also suggested that SII-T1 is a specific transcription elongation factor essential for spermatogenesis.
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PMID:Spermatocyte-specific expression of the gene for mouse testis-specific transcription elongation factor S-II. 864 58

RNA polymerase II contains a ribonuclease activity which is stimulated by the transcription elongation factor SII. This nuclease shortens the nascent RNA and facilitates relief of transcriptional arrest by allowing the enzyme to make multiple attempts to read through an obstacle to transcription. The catalytic center of this ribonuclease is unknown, although a region of the enzyme's second largest subunit shares local sequence similarly with barnase and other bacterial ribonucleases. To test the role of the barnase homology region in SII-activated cleavage, we engineered a single amino acid change in the Saccharomyces cerevisiae enzyme at a position homologous to a catalytic residue of barnase (Glu-371) and has been suggested as a participant in active site chemistry of RNA polymerase II. We purified RNA polymerase II from mutant yeast and assayed its ability to cleave and re-extend the nascent RNA following SII treatment. We find no defects in this function of the mutant enzyme, suggesting that the barnase homology region does not represent the active site of the SII-activated nuclease. These mutant yeast cells were also resistant to mycophenolic acid, which slows the growth of some yeast mutants bearing elongation defective RNA polymerase II or mutant elongation factor SII.
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PMID:Glutamic acid-371 of the barnase homology domain in RNA polymerase II is not required for SII-activated RNA cleavage. 903 12

The baculovirus late expression factor LEF-5 has a zinc ribbon that is homologous to a domain in the eukaryotic transcription elongation factor SII. To determine whether LEF-5 is an elongation factor, we purified it from a bacterial overexpression system and added it to purified baculovirus RNA polymerase. LEF-5 increased transcription from both late and very late viral promoters. Two acidic residues within the zinc ribbon were essential for stimulation. Unlike SII, however, LEF-5 did not appear to enable RNA polymerase to escape from intrinsic pause sites. Furthermore, LEF-5 did not increase transcription in the presence of small DNA-binding ligands that inhibit elongation in other systems or viral DNA-binding proteins which inhibit the baculovirus RNA polymerase. Exonuclease activity assays revealed that baculovirus RNA polymerase has an intrinsic exonuclease activity, but this was not increased by the addition of LEF-5. Initiation assays and elongation assays using heparin to prevent reinitiation indicated that LEF-5 was active only in the absence of heparin. Taken together, these results suggest that LEF-5 functions as an initiation factor and not as an elongation factor.
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PMID:In vitro activity of the baculovirus late expression factor LEF-5. 1243 92

SII-T1 is a tissue-specific member of the transcription elongation factor S-II that is expressed specifically in male germ cells. In the present study, we have identified a protein named GRIP1tau interacting with SII-T1 by yeast two-hybrid screening. GRIP1tau is a novel isoform of glutamate receptor-interacting protein 1 (GRIP1) that associates with the cytoplasmic domain of the alpha-amino-3-hydroxy-5-methyl-4-isoaxazolepropionate (AMPA)-type glutamate receptor. GRIP1tau is a testis-specific nuclear protein that activates transcription when fused with a GAL4 DNA binding domain in GAL4-responsive reporter gene assays. The transactivation domain of GRIP1tau overlapped with the region essential for interaction with SII-T1, as revealed by co-immunoprecipitation assays. Also, transactivation by GRIP1tau was stimulated by SII-T1 in a dose-dependent manner. Therefore, we propose that GRIP1tau is a novel testis-specific transcriptional activator regulated by interaction with the testis-specific transcription elongation factor SII-T1.
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PMID:GRIP1tau, a novel PDZ domain-containing transcriptional activator, cooperates with the testis-specific transcription elongation factor SII-T1. 1550 23

We have reconstituted a highly purified RNA polymerase II transcription system containing chromatin templates assembled with purified histones and assembly factors, the histone acetyltransferase p300, and components of the general transcription machinery that, by themselves, suffice for activated transcription (initiation and elongation) on DNA templates. We show that this system mediates activator-dependent initiation, but not productive elongation, on chromatin templates. We further report the purification of a chromatin transcription-enabling activity (CTEA) that, in a manner dependent upon p300 and acetyl-CoA, strongly potentiates transcription elongation through several contiguous nucleosomes as must occur in vivo. The transcription elongation factor SII is a major component of CTEA and strongly synergizes with p300 (histone acetylation) at a step subsequent to preinitiation complex formation. The purification of CTEA also identified HMGB2 as a coactivator that, while inactive on its own, enhances SII and p300 functions.
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PMID:Synergistic functions of SII and p300 in productive activator-dependent transcription of chromatin templates. 1663 Aug 16


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