Regulation of chromatin topology

在你身体的每个细胞内，DNA并不是以简单的双螺旋形式存在的：在这种形式下，你的DNA太笨重而无法有效地组织起来。相反，DNA缠绕在组蛋白上，这种DNA-蛋白质混合物称为染色质。染色质存在于动物细胞和一些微生物中，如酵母。在染色质组织的最低水平，核小体“线轴”（由组蛋白组成）在DNA上以“串珠”的方式规则地间隔排列。然而，细胞内只有一小部分染色质以这种形式存在。相反，核小体相互作用形成复杂的染色质状态。我的研究项目采用酵母中的生物化学和遗传学来了解核小体相互作用形成不同拓扑结构的方式。我们发现了一种全新的机制，它改变了核小体相互作用和凝聚形成紧凑结构的方式。我们在此资助期间的目标是确定这个过程，称为组蛋白-脯氨酸异构化，如何影响DNA在细胞中的包装方式。我们有两个直接的目标：首先，使用纯化的DNA和核小体，我们将研究如何组蛋白脯氨酸异构化改变染色质在体外。其次，我们将测量组蛋白脯氨酸异构化染色质结构在体内酵母中使用遗传工具的贡献。

Inside each cell of your body DNA does not exist as a simple double helix: in this form your DNA is too cumbersome to be effectively organized. Instead DNA is spooled onto histone proteins and this DNA-protein mixture is called chromatin. Chromatin is present in the cells of animals and in some microbes, like yeast. At the lowest level of chromatin organization, the nucleosome 'spools' (made up of histone proteins), are spaced regularly on the DNA in a 'beads-on-a-string' assembly. However only a small proportion of chromatin inside cells exists in this form. Instead, the nucleosomes interact with each other to form complex chromatin states. My research program employs biochemistry and genetics in yeast to understand the ways that nucleosomes interact to form different topologies. We have found a completely new mechanism that changes the way nucleosomes interact and condense to form a compact structure. Our goal in this funding period is to define how this process, called histone-proline isomerisation, affects the way DNA is packaged in cells. We have two immediate aims: First, using purified DNA and nucleosomes we will study how histone proline isomerisation changes chromatin in vitro. Secondly we will measure the contribution of histone proline isomerisation to chromatin architecture in vivo using genetic tools in yeast.