Shimizu M, Li W, Shindo H, Mitchell A P
School of Pharmacy, Tokyo University of Pharmacy and Life Science, Hachioji, Japan.
Proc Natl Acad Sci U S A. 1997 Feb 4;94(3):790-5. doi: 10.1073/pnas.94.3.790.
The yeast repressor Rme1p acts from distant binding sites to block transcription of the chromosomal IME1 gene. Rme1p can also repress the heterologous CYC1 promoter when Rme1p binding sites are placed 250-300 bp upstream of CYC1 transcriptional activator binding sites (UAS1 and UAS2). Here, in vivo footprinting studies indicate that Rme1p acts over this distance by preventing the binding of the CYC1 transcriptional activators to UAS1 and UAS2. Inhibition of activator binding by Rme1p has the same genetic requirements as repression: both depend upon sequences flanking the Rme1p binding sites and upon Rgr1p and Sin4p, two subunits of the RNA polymerase II-associated Mediator complex that are required for normal nucleosome density. Thus Rme1p may alter chromatin to prevent binding of transcriptional activators to distant DNA sequences.
酵母阻遏物Rme1p从远距离结合位点发挥作用，以阻断染色体上IME1基因的转录。当Rme1p结合位点位于CYC1转录激活因子结合位点（UAS1和UAS2）上游250 - 300 bp处时，Rme1p也能抑制异源CYC1启动子。在此，体内足迹研究表明，Rme1p通过阻止CYC1转录激活因子与UAS1和UAS2结合，在这个距离上发挥作用。Rme1p对激活因子结合的抑制与阻遏具有相同的遗传要求：两者都依赖于Rme1p结合位点侧翼的序列，以及Rgr1p和Sin4p，这两个RNA聚合酶II相关中介复合物的亚基，它们是正常核小体密度所必需的。因此，Rme1p可能会改变染色质，以防止转录激活因子与远距离DNA序列结合。
