Song W, Carlson M
Departments of Genetics and Development, Columbia University, 701 W. 168th St., New York, NY 10032, USA.
EMBO J. 1998 Oct 1;17(19):5757-65. doi: 10.1093/emboj/17.19.5757.
Srb/mediator proteins that are associated with RNA polymerase II holoenzyme have been implicated in transcriptional repression in Saccharomyces cerevisiae. We show here that the defect in repression of SUC2 caused by mutation of SRB8, SRB9, SRB11, SIN4 or ROX3 is suppressed by increased dosage of the SFL1 gene, and the genetic behavior of the sfl1Delta mutation provides further evidence for a functional relationship. Sfl1 acts on SUC2 through a repression site located immediately 5' to the TATA box, and Sfl1 binds this DNA sequence in vitro. Moreover, LexA-Sfl1 represses transcription of a reporter, and repression is reduced in an srb9 mutant. Finally, we show that Sfl1 co-immunoprecipitates from cell extracts with Srb9, Srb11, Sin4 and Rox3. We propose that Sfl1, when bound to its site, interacts with Srb/mediator proteins to inhibit transcription by RNA polymerase II holoenzyme.
与RNA聚合酶II全酶相关的Srb/中介蛋白已被证明与酿酒酵母中的转录抑制有关。我们在此表明,SRB8、SRB9、SRB11、SIN4或ROX3突变导致的SUC2抑制缺陷可通过增加SFL1基因的剂量来抑制,并且sfl1Delta突变的遗传行为为功能关系提供了进一步的证据。Sfl1通过位于TATA框上游紧邻的抑制位点作用于SUC2,并且Sfl1在体外结合该DNA序列。此外,LexA-Sfl1抑制报告基因的转录,并且在srb9突变体中抑制作用减弱。最后,我们表明Sfl1可从细胞提取物中与Srb9、Srb11、Sin4和Rox3进行共免疫沉淀。我们提出,当Sfl1与其位点结合时,它与Srb/中介蛋白相互作用以抑制RNA聚合酶II全酶的转录。