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)

We report the identification of a transcription elongation factor from HeLa cell nuclear extracts that causes pausing of RNA polymerase II (Pol II) in conjunction with the transcription inhibitor 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB). This factor, termed DRB sensitivity-inducing factor (DSIF), is also required for transcription inhibition by H8. DSIF has been purified and is composed of 160-kD (p160) and 14-kD (p14) subunits. Isolation of a cDNA encoding DSIF p160 shows it to be a homolog of the Saccharomyces cerevisiae transcription factor Spt5. Recombinant Supt4h protein, the human homolog of yeast Spt4, is functionally equivalent to DSIF p14, indicating that DSIF is composed of the human homologs of Spt4 and Spt5. In addition to its negative role in elongation, DSIF is able to stimulate the rate of elongation by RNA Pol II in a reaction containing limiting concentrations of ribonucleoside triphosphates. A role for DSIF in transcription elongation is further supported by the fact that p160 has a region homologous to the bacterial elongation factor NusG. The combination of biochemical studies on DSIF and genetic analysis of Spt4 and Spt5 in yeast, also in this issue, indicates that DSIF associates with RNA Pol II and regulates its processivity in vitro and in vivo.
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PMID:DSIF, a novel transcription elongation factor that regulates RNA polymerase II processivity, is composed of human Spt4 and Spt5 homologs. 945 Sep 29

5,6-Dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) is a classic inhibitor of transcription elongation by RNA polymerase II (pol II). We have previously identified and purified a novel transcription elongation factor, termed DSIF (for DRB sensitivity-inducing factor), that makes transcription sensitive to DRB. DSIF is composed of 160- and 14-kDa subunits, which are homologs of the Saccharomyces cerevisiae transcription factors Spt5 and Spt4. DSIF may either repress or stimulate transcription in vitro, depending on conditions, but its physiological function remains elusive. Here we characterize the structure and function of DSIF p160. p160 is shown to be a ubiquitous nuclear protein that forms a stable complex with p14 and interacts directly with the pol II largest subunit. Mutation analysis of p160 is used to identify structural features essential for its in vitro activity and to map the domains required for its interaction with p14 and pol II. Finally, a p160 mutant that represses DSIF activity in a dominant-negative manner is identified and used to demonstrate that DSIF represses transcription from various promoters in vivo.
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PMID:Structure and function of the human transcription elongation factor DSIF. 1007 9

The HIV-1-encoded Tat protein controls transcription elongation by increasing processivity of RNA polymerase II (Pol II). Here, we have identified a Tat stimulatory activity (Tat-SF) as a novel RNA Pol II-containing complex. Remarkably, Tat-SF contains the previously identified Tat cofactors Tat-SF1, P-TEFb and hSPT5/Tat-CT1, in addition to RNA Pol II and other unidentified polypeptides, but none of the SRB/MED proteins or other factors found associated with the previously described RNA Pol II holoenzyme complex. Tat-SF supports basal, Sp1-activated and Tat-activated transcription in a reconstituted system, and a Tat-SF-derived fraction lacking RNA Pol II can complement non-responsive RNA Pol II complexes for Tat-enhanced HIV-1 transcription, indicating that Tat-SF contains factors that are critical for Tat function. Both Tat-SF and RNA Pol II holoenzyme are present in HeLa nuclear extracts and each can be recruited to the HIV-1 promoter. Our results indicate that Tat-SF is a Tat cofactor-containing RNA Pol II complex whose recruitment to the promoter provides elongation factors important for Tat-enhanced HIV-1 transcription following TAR RNA synthesis.
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PMID:A novel RNA polymerase II-containing complex potentiates Tat-enhanced HIV-1 transcription. 1039 84

RNA polymerase II nascent transcripts are capped during pausing before elongation. Here we report that hSPT5, the human homolog of yeast elongation factor SPT5, interacts directly with the capping enzyme. hSPT5 stimulated capping enzyme guanylylation and mRNA capping by severalfold. Although RNA 5'-triphosphatase activity was unaffected, binding to this domain in the full-length enzyme is likely involved in the stimulation, as hSPT5 did not increase the activity of the guanylyltransferase fragment. Consistent with capping enzyme binding, TFIIH-phosphorylated CTD stimulated guanylylation, and this increase was not additive with hSPT5.
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PMID:Transcription elongation factor hSPT5 stimulates mRNA capping. 1042 30

The CDK9-cyclin T kinase complex, positive transcription elongation factor b (P-TEFb), stimulates the process of elongation of RNA polymerase (Pol) II during transcription of human immunodeficiency virus. P-TEFb associates with the human immunodeficiency virus Tat protein and with the transactivation response element to form a specific complex, thereby mediating efficient elongation. Here, we show that P-TEFb preferentially phosphorylates hSPT5 as compared with the carboxyl-terminal domain of RNA Pol II in vitro. Phosphorylation of hSPT5 by P-TEFb occurred on threonine and serine residues in its carboxyl-terminal repeat domains. In addition, we provide several lines of evidence that P-TEFb is a CDK-activating kinase (CAK)-independent kinase. For example, CDK9 was not phosphorylated by CAK, whereas CDK2-cyclin A kinase activity was dramatically enhanced by CAK. Therefore, it is likely that P-TEFb participates in regulation of elongation by RNA Pol II by phosphorylation of its substrates, hSPT5 and the CTD of RNA Pol II, in a CAK-independent manner.
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PMID:Positive transcription elongation factor B phosphorylates hSPT5 and RNA polymerase II carboxyl-terminal domain independently of cyclin-dependent kinase-activating kinase. 1114 67