权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

The structural analysis of centromere specific nucleosome

着丝粒特异性核小体的结构分析

基本信息

批准号：
21870038
负责人：
TACHIWANA Hiroaki
金额：
$ 1.76万
依托单位：
Waseda University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Research Activity Start-up
财政年份：
2009
资助国家：
日本
起止时间：
2009 至 2010
项目状态：
已结题

项目摘要

In eukaryotes, genomic DNA is duplicated during S phase, and is equally divided into two daughter cells during M phase. Centromere, which is one of the distinct regions in chromosome, plays important rules in this division. Centromere formation is necessary for chromosome segregation. But, it is not known how centromere region is formed and distinguished from other region. Some proteins, which localize specifically at centromere region, are identified. CENP-A, a histone H3 variant, also localize specifically at centromere region. CENP-A is assembled into the chromatin of centromeres and is thought to generate unique chromatin features. In this study, we performed structural analysis of the CENP-A nucleosome and determined crystal structure of CENP-A nucleosome by X-ray crystallography. Determined structure revealed that CENP-A nucleosome contains two each of histones H2A, H2B, H4 and CENP-A and DNA is wrapped around histone octamer in a left-hand orientation. Surprisingly, only 121 bp of DNA are visible and 13 bp from both ends of DNA are flexible in the CENP-A-nucleosome. Structural comparison of the CENP-A and H3-nucleosomes revealed that the loop1 region of CENP-A is different from canonical H3 because of insertion of two extra amino acid residues. In vivo analysis revealed these amino acids are important to retain CENP-A at centromere region.

在真核生物中，基因组DNA在S期复制，并在M期平均分成两个子细胞。着丝粒是染色体上的一个独特区域，在染色体的分裂过程中起着重要的作用。着丝粒的形成是染色体分离所必需的。但是，目前尚不清楚着丝粒区是如何形成的，以及如何与其他区域区分开来。鉴定了一些特异定位于着丝粒区的蛋白质。CENP-A是一种组蛋白H3变体，也特异性定位于着丝粒区。CENP-A被组装到着丝粒的染色质中，并被认为产生独特的染色质特征。在本研究中，我们对CENP-A核小体进行了结构分析，并通过X射线晶体学确定了CENP-A核小体的晶体结构。结构测定表明CENP-A核小体含有组蛋白H2 A、H2 B、H4和CENP-A各两个，DNA以左手方向包裹在组蛋白八聚体周围。令人惊讶的是，在CENP-A-核小体中仅121 bp的DNA是可见的，并且来自DNA两端的13 bp是柔性的。CENP-A和H3-核小体的结构比较显示，CENP-A的loop 1区域不同于典型的H3，因为插入了两个额外的氨基酸残基。体内分析表明，这些氨基酸对于将CENP-A保留在着丝粒区域是重要的。