A comparative structural study of ATP-dependent chromatin remodeling complexes

ATP依赖性染色质重塑复合物的比较结构研究

基本信息

批准号：
10220986
负责人：
Andres Leschziner
金额：
$ 35.55万
依托单位：
UNIVERSITY OF CALIFORNIA, SAN DIEGO
依托单位国家：
美国
项目类别：
财政年份：
2011
资助国家：
美国
起止时间：
2011-04-01 至 2023-07-31
项目状态：
已结题

项目摘要

PROJECT SUMMARY Nucleosomes are the basic DNA packaging unit in eukaryotes. ATP-dependent nucleosome remodeling complexes (“remodelers”) use ATP hydrolysis to non-covalently alter their structure to regulate genome dynamics. Remodelers, conserved from yeast to humans, generate a wide range of products despite sharing a conserved catalytic subunit: a 3’-5’ dsDNA translocase that binds to the nucleosome and breaks histone-DNA contacts and alters the structure of nucleosomes by propelling DNA over their surface. Remodeler ATPases are flanked by accessory domains that define 4 subfamilies: ISWI, CHD, SWI/SNF and INO80. These subfamilies differ in complexity, ranging from single-subunit remodelers (ISWI and CDH), to large, multi-subunit 1MDa+ complexes (SWI/SNF and INO80). Different subfamilies catalyze different outcomes. “Orphan” remodelers, whose translocases do not belong to any of the 4 subfamilies despite their conserved ATPase domains, are less well characterized. The overarching goal of this proposal is to understand the mechanistic underpinnings of the functional diversity of remodelers. ISWI and CHD remodelers, among the smallest and best understood, have provided insights into how they regulate their translocases to produce their specific remodeling outcomes. Although conceptual models have been proposed to explain the functional specialization of SWI/SNF and INO80 remodelers a mechanistic understanding is missing. Even less is known about orphan remodelers. In this proposal, we will tackle model systems representing functions for which mechanistic understanding is lacking. For orphan remodelers, we will focus on Rad26, the S. cerevisiae ortholog of the Cockayne Syndrome protein B (CSB), a protein that has long been known for its role in Transcription Coupled DNA Repair, and that we recently showed uses its DNA translocation to help RNA Polymerase II overcome transcriptional obstacles. For the SWI/SNF remodelers, we will focus on the RSC complex, an abundant and essential remodeler from S. cerevisiae capable of both sliding and ejecting histone octamers. For the INO80 family, we will continue working on the SWR1 complex, which is unique in its ability to exchange histone dimers in a nucleosome without altering its position. We will use a combination of structural (cryo-electron microscopy) and biochemical approaches to understand how these different remodelers regulate their DNA translocases to produce their specialized remodeling outcomes. !

项目摘要核小体是真核生物中的基本DNA包装单元。依赖ATP的核体重塑复合物（“重塑器”）使用ATP水解无共价改变其结构以调节基因组动力学。从酵母到人类配置的改建商生成了广泛的产品目的地共享保守的催化亚基：3'-5'DsDNA易位酶，与核小体结合并破坏Hisstone-DNA 接触并通过在其表面上推动DNA来改变核体的结构。重塑ATPase的侧面是定义4个亚家族的附件域：ISWI，CHD，SWI/SNF 和Ino80。这些亚家族的复杂性有所不同，范围从单sumunit远程（ISWI和CDH）到大的多余1MDA+复合物（SWI/SNF和INO80）。不同的亚家族催化不同的结果。 “孤儿”远程群，其易位酶不属于其保守的四个亚家族目的地中的任何一个 ATPase域的表征不佳。该提议的总体目标是了解远程功能多样性的机械基础。 ISWI和CHD远程最小，最好的理解，已经提供了有关它们如何调节易位酶以产生其生产的见解尽管已经提出了特定的重塑结果。尽管已经提出了概念模型来解释功能 SWI/SNF和INO80改建器的专业化缺失了机械理解。甚至更少知道关于孤儿遥控器。在此提案中，我们将解决代表机械理解的功能的模型系统缺乏。对于孤儿遥控器，我们将重点放在Cockayne综合征的S. cerevisiae od26上蛋白B（CSB），一种以转录耦合DNA修复的作用而闻名的蛋白质，并且我们最近显示，使用其DNA易位来帮助RNA聚合酶II克服转录障碍。对于SWI/SNF远程OROT，我们将重点关注RSC复合物，RSC复合物是S的绝对和必不可少的重塑。能够滑动和射出组蛋白八聚体的酿酒酵母。对于Ino80家庭，我们将继续工作在SWR1复合物上，它在其在核小体中交换组蛋白二聚体的能力是独一无二的它的位置。我们将结合结构（冷冻电子显微镜）和生化方法的结合了解这些不同的远方如何调节其DNA易位酶以产生其专业化重塑结果。呢