DSIF, a novel transcription elongation factor that regulates RNA polymerase II processivity, is composed of human Spt4 and Spt5 homologs
DSIF, a novel transcription elongation factor that regulates RNA polymerase II processivity, is composed of human Spt4 and Spt5 homologs
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DOI：
10.1101/gad.12.3.343
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发表时间：
1998-02-01
影响因子：
10.5
通讯作者：
Handa, H
中科院分区：
文献类型：
--
作者：
Wada, T;Takagi, T;Handa, H
我们报告了从HeLa细胞核提取液中鉴定出一种转录延伸因子，它与转录抑制剂5，6-dichloro-1-beta-D-ribofuranosylbenzimidazole(DRB)一起导致核糖核酸聚合酶II(POL II)暂停。这个因子，在bar Rb(S)下称为(D)，在bar敏感度下-(I)在bar acter(Dsif)下，在bar诱导(F)下，也是H8转录抑制所必需的。纯化的dsIF由160kD(P160)和14kD(P14)亚基组成。分离到一个编码dsif p160的cDNA，表明它与酿酒酵母转录因子Spt5同源。重组的Supt4h蛋白是酵母Spt4的人类同源物，与dSIF p14在功能上是相同的，表明dSIF是由Spt4和Spt5的人同源物组成的。除了在延伸过程中的负性作用外，在含有有限浓度的核糖核苷三磷酸盐的反应中，DSIF还能够刺激RNA Pol II的延伸率。P160具有与细菌延伸因子NusG同源的区域，这进一步支持了DSIF在转录延伸中的作用。结合对酵母中Spt4和Spt5的生物化学研究，以及对Spt4和Spt5的遗传分析，也在这一期中表明，DSIF与RNA Pol II结合，并调节其在体外和体内的加工能力。
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 (D) under bar RB (s) under bar ensitivity-(i) under bar nducing (f) under bar actor (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.