甲基化 DNA 结合蛋白 2 结构域的独特物理性质和相互作用。

Unique physical properties and interactions of the domains of methylated DNA binding protein 2.

机构信息

Department of Biology, University of Massachusetts, Amherst, Massachusetts 01003, USA.

出版信息

Biochemistry. 2010 May 25;49(20):4395-410. doi: 10.1021/bi9019753.

Abstract

Methylated DNA binding protein 2 (MeCP2) is a methyl CpG binding protein whose key role is the recognition of epigenetic information encoded in DNA methylation patterns. Mutation or misregulation of MeCP2 function leads to Rett syndrome as well as a variety of other autism spectrum disorders. Here, we have analyzed in detail the properties of six individually expressed human MeCP2 domains spanning the entire protein with emphasis on their interactions with each other, with DNA, and with nucleosomal arrays. Each domain contributes uniquely to the structure and function of the full-length protein. MeCP2 is approximately 60% unstructured, with nine interspersed alpha-molecular recognition features (alpha-MoRFs), which are polypeptide segments predicted to acquire secondary structure upon forming complexes with binding partners. Large increases in secondary structure content are induced in some of the isolated MeCP2 domains and in the full-length protein by binding to DNA. Interactions between some MeCP2 domains in cis and trans seen in our assays likely contribute to the structure and function of the intact protein. We also show that MeCP2 has two functional halves. The N-terminal portion contains the methylated DNA binding domain (MBD) and two highly disordered flanking domains that modulate MBD-mediated DNA binding. One of these flanking domains is also capable of autonomous DNA binding. In contrast, the C-terminal portion of the protein that harbors at least two independent DNA binding domains and a chromatin-specific binding domain is largely responsible for mediating nucleosomal array compaction and oligomerization. These findings led to new mechanistic and biochemical insights regarding the conformational modulations of this intrinsically disordered protein, and its context-dependent in vivo roles.

摘要

甲基化 DNA 结合蛋白 2(MeCP2)是一种甲基 CpG 结合蛋白,其主要作用是识别 DNA 甲基化模式中编码的表观遗传信息。MeCP2 功能的突变或失调会导致雷特综合征以及多种其他自闭症谱系障碍。在这里,我们详细分析了跨越整个蛋白质的六个单独表达的人 MeCP2 结构域的特性,重点是它们之间的相互作用、与 DNA 的相互作用以及与核小体阵列的相互作用。每个结构域都为全长蛋白质的结构和功能做出独特的贡献。MeCP2 大约有 60%没有结构,有九个分散的α-分子识别特征(α-MoRFs),这些多肽片段预计在与结合伙伴形成复合物时会获得二级结构。一些分离的 MeCP2 结构域和全长蛋白质与 DNA 结合后,二级结构含量会大大增加。我们的实验中观察到一些顺式和反式 MeCP2 结构域之间的相互作用可能有助于完整蛋白质的结构和功能。我们还表明,MeCP2 有两个功能半体。N 端部分包含甲基化 DNA 结合域(MBD)和两个高度无序的侧翼结构域,这些结构域调节 MBD 介导的 DNA 结合。其中一个侧翼结构域也能够自主结合 DNA。相比之下,蛋白质的 C 端部分至少包含两个独立的 DNA 结合结构域和一个染色质特异性结合结构域,主要负责介导核小体阵列的压缩和寡聚化。这些发现为这种固有无序蛋白质的构象调节及其在体内的上下文相关作用提供了新的机制和生化见解。

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