IDENTIFICATION OF COMPONENTS OF THE HIR COMPLEX REQUIRED FOR CHROMATIN ASSEMBLY

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者的研究机构。 核小体是真核生物染色体的基本组成部分，由DNA包裹在组蛋白周围形成。组蛋白在DNA上的快速有序沉积是由染色质组装蛋白介导的。在芽殖酵母中，已知遗传鉴定的一组四种Hir蛋白（Hir 1、Hir 2、Hir 3和Hpc 2）与Asf 1协同作用以确保组蛋白四聚体的适当沉积（萨顿等人，Genetics，2001; Sharp等人，Curr Biol，2001）。Hir蛋白在维持着丝粒处的染色质结构方面也具有突出的作用，从而有助于准确的染色体分离（Sharp et al.，Genes Dev，2002）。然而，Hir蛋白复合物的生物化学性质及其促进适当染色质组装的机制在很大程度上仍未被探索。例如，对Hir蛋白的天然寡聚状态几乎一无所知，以前的遗传实验也没有表明是否存在未发现的复合物亚基。 因此，我们提出了一种结构/功能的方法，通过分离天然Hir蛋白复合物，并通过质谱和功能测定来表征它们。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Nucleosomes are the fundamental building blocks of the eukaryotic chromosome, formed by wrapping DNA around histone proteins. The rapid and orderly deposition of histones on DNA is mediated by chromatin assembly proteins. In budding yeast, a set of four Hir proteins (Hir1, Hir2, Hir3, and Hpc2) identified genetically are known to act in concert with Asf1 to ensure proper deposition of histone tetramers (Sutton et al., Genetics, 2001; Sharp et al., Curr Biol, 2001). The Hir proteins also have a prominent role in maintaining the chromatin structure at the centromere, thereby contributing to accurate chromosome segregation (Sharp et al., Genes Dev, 2002). However, the biochemical nature of Hir protein complexes and their mechanisms for promoting proper chromatin assembly have remained largely unexplored. For example, almost nothing is known about the native oligomeric state of the Hir proteins, and previous genetic experiments do not indicate whether there may be undiscovered subunits of the complex. We therefore propose a structure/function approach by isolating native Hir protein complexes and characterizing them by both mass spectrometry and functional assays.