Biochemistry and Genetics of Chromatin Assembly Factors in Drosophila

描述(申请人提供)：活体的遗传材料(DNA)存储在染色体中。要了解细胞在正常发育和疾病中的活动，需要的不仅仅是基因组的DNA序列和个体特有的变异。通过将基因组包装成一种被称为染色质的保守的核蛋白复合体，也发挥了关键的调节作用。染色质的组装和维持是由两个蛋白质家族共同作用的，即组蛋白伴侣和ATP驱动的运动染色质重塑因子。染色质的结构及其新陈代谢的调节机制是唯一重要的，因此在进化中非常保守。我们工作的最终目的是了解染色质结构的建立与真核染色体功能调节之间的关系。我们将集中对介导染色质组装的蛋白质进行系统研究。我们将分析基本的分子事件，并检查在体外(试管)染色质组装过程中发生的组蛋白伴侣蛋白和运动因子界面上的相互作用。此外，我们还将研究染色质组装因子在活体模式生物--果蝇中的特定功能作用。我们将进行实验，以了解组装因子如何改变体内的染色质结构，并调节各种DNA导向的酶过程，如转录、DNA复制和修复。成熟精子的染色质在组成上与正常细胞染色质不同，特别是DNA高度凝聚。精子染色质在酶作用下是静态的，由DNA与被称为鱼精蛋白的小的富含半胱氨酸的碱性蛋白质紧密结合而成。在受精时，卵子面临着将浓缩的精子染色质重塑为可获得的、转录和复制能力强的形式的挑战。我们最近在体外和体内发现了介导精子染色质重塑的细胞机制。因此，我们还将研究介导精子染色质重塑的因素。该项目的成功完成将导致对调节各种形式的染色质组装的因素进行全面的生化和生物学表征。在全球范围内，我们的工作将提供对染色体组装和维持在细胞功能调节中的作用的见解，并将适用于理解、诊断和治疗涉及DNA代谢过程中缺陷的人类疾病。

DESCRIPTION (provided by applicant): Genetic inheritance material of a living organism (DNA) is stored in chromosomes. Understanding of cellular activities in normal development and disease requires more than the DNA sequence and individual- specific variations of the genome. Critical regulatory roles are also played by packaging of the genome into a conserved nucleoprotein complex termed chromatin. Chromatin is assembled and maintained by a concerted action of two families of proteins, namely histone chaperones and ATP-driven motor chromatin remodeling factors. The structure of chromatin and the regulatory machinery of its metabolism are uniquely important and thus strongly conserved in evolution. The ultimate objective of our work is to understand the relationship between the establishment of chromatin structure and regulation of the function of eukaryotic chromosomes. We will focus on a systematic study of proteins that mediate chromatin assembly. We will analyze elementary molecular events and examine interactions at the interface of histone chaperones and motor factors that take place during chromatin assembly in vitro (in a test tube). In addition, we will investigate specific functional roles for chromatin assembly factors in a living model organism, fruit fly (Drosophila melanogaster). We will perform experiments to understand how the assembly factors alter chromatin structure in vivo and regulate various DNA-directed enzymatic processes, such as transcription, DNA replication and repair. The chromatin of mature sperm differs in composition from normal cell chromatin, in particular by an extraordinary high degree of DNA condensation. Sperm chromatin is enzymatically static and is formed by compaction of DNA with small basic, cysteine-rich proteins termed protamines. At fertilization, the egg faces the challenge of remodeling the condensed sperm chromatin into an accessible, transcription- and replication- competent form. We recently discovered cellular machinery that mediates sperm chromatin remodeling in vitro and in vivo. Thus, we will also study the factors that mediate sperm chromatin remodeling. The successful completion of this project will lead to a comprehensive biochemical and biological characterization of factors that mediate the assembly of various forms of chromatin. More globally, our work will provide insights into the role of chromosome assembly and maintenance in regulation of the cell function and will be applicable to understanding, diagnosis and treatment of human diseases that involve defects in processes of DNA metabolism.