LINKER HISTONE/DNA INTERACTIONS

我们实验室最近的证据表明，所谓的“链接器” 组蛋白(H1、H5及其变异体)可以与特定的DNA结构结合 以及比迄今认为的更具体的序列。在……里面 具体地说，这些组蛋白与DNA交叉结构紧密结合， 以四向交叉口为代表。这些都是受欢迎的相同结构 通过一类丰富的高迁移率基团蛋白(HMG 1/2)，以及 与核小体出入口的DNA结构相似。 连接子组蛋白和HMG1结合似乎与一般 基因抑制和表达的机制。我们提出了一个详细的 对这种选择性结合的研究，包括对结合的定量 由完整的组蛋白及其球状结构域连接到连接处，以及 组蛋白变异体和HMGI对这种结合的竞争。这个 结合/竞争实验将扩展到利用 核小体，作为体内结构的更直接模型。 第二个研究领域将利用聚合酶链式反应扩增方法 试图发现DNA序列或序列类型表现出很强的 连接子组蛋白结合。然后，这些信息将被用于研究这些影响 这种结合对DNA构象的影响。

Recent evidence from our laboratory indicates that the so-called "linker" histones (H1, H5, and their variants) can bind to certain DNA structures and sequences much more specifically than hitherto believed. In particular, these histones strongly bind to DNA crossover structures, typified by the four-way junction. These are the same structures favored by an abundant class of high mobility group proteins (HMG 1/2), and resemble the DNA structure at the entrance and exit from the nucleosome. Linker histones and HMG1 binding appear to be related to general mechanisms of genetic repression and expression. We propose a detailed investigation of this selective binding, including quantitation of binding by intact histones and their globular domains to the junction, and competition between histone variants and HMGI for such binding. The binding/competition experiments will then be extended to studies utilizing nucleosomes, as a more direct model of the in vivo structure. A second area of study will utilize PCR amplification methods in an attempt to discover DNA sequences or sequence types exhibiting strong linker histone binding. These will then be used in studies of the effects of such binding on DNA conformation.