一种组蛋白变体Htz1p和一种类似Sir1p的蛋白质Esc2p介导HMR处的基因沉默。

A histone variant, Htz1p, and a Sir1p-like protein, Esc2p, mediate silencing at HMR.

作者信息

Dhillon N, Kamakaka R T

机构信息

Unit on Chromatin and Transcription, NICHD/NIH, Bethesda, Maryland 20892, USA.

出版信息

Mol Cell. 2000 Oct;6(4):769-80. doi: 10.1016/s1097-2765(00)00076-9.

DOI:10.1016/s1097-2765(00)00076-9

PMID:11090616

Abstract

Silencing at HMR requires silencers, and one of the roles of the silencer is to recruit Sir proteins. This work focuses on the function of Sir1p once it is recruited to the silencer. We have generated mutants of Sir1p that are recruited to the silencer but are unable to silence, and we have utilized these mutants to identify four proteins, Sir3p, Sir4p, Esc2p, and Htz1p, that when overexpressed, restored silencing. The isolation of Sir3p and Sir4p validated this screen. Molecular analysis suggested that Esc2p contributed to silencing in a manner similar to Sir1p and probably helped recruit or stabilize the other Sir proteins, while Htz1p present at HMR assembled a specialized chromatin structure necessary for silencing.

摘要

HMR位点的基因沉默需要沉默子，而沉默子的作用之一是招募Sir蛋白。这项工作聚焦于Sir1p被招募到沉默子后的功能。我们构建了能被招募到沉默子但无法实现基因沉默的Sir1p突变体，并利用这些突变体鉴定出了四种蛋白质，即Sir3p、Sir4p、Esc2p和Htz1p，当它们过表达时能恢复基因沉默。Sir3p和Sir4p的分离验证了该筛选方法。分子分析表明，Esc2p以类似于Sir1p的方式促进基因沉默，可能有助于招募或稳定其他Sir蛋白，而存在于HMR位点的Htz1p组装了基因沉默所需的特殊染色质结构。