Dodecameric structure of the small heat shock protein Acr1 from Mycobacterium tuberculosis
Dodecameric structure of the small heat shock protein Acr1 from Mycobacterium tuberculosis
复制标题
DOI：
10.1074/jbc.m504263200
复制
发表时间：
2005-09-30
影响因子：
4.8
通讯作者：
Keep, NH
中科院分区：
文献类型：
--
作者：
Kennaway, CK;Benesch, JLP;Keep, NH
小分子热休克蛋白是一个普遍存在的、多样的应激蛋白家族，它们都具有α-晶状体蛋白结构域。结核分枝杆菌有两种小的热休克蛋白，Acr 1（α-晶状体蛋白相关蛋白1，或Hsp16.3/16-kDa抗原）和Acr 2（HrpA），这两种蛋白在不同的应激条件下都高度表达。小的热休克蛋白形成大的寡聚体组装，并且通常是多分散的。纳米电喷雾质谱表明，Acr 2形成了一系列的低聚物组成的二聚体和四聚体，而Acr 1是一个十二聚体。Acr 2的电子显微镜显示出多种粒径。使用负染色电子显微镜图像的三维分析，我们已经表明，Acr 1形成一个四面体组装12多肽链。相关的α-晶状体蛋白结构域二聚体的原子结构对接到密度中，以构建十二聚体Acr 1复合物的分子结构。沿着这两种蛋白质的差异调节，它们四级结构的差异支持它们不同的功能作用。
Small heat shock proteins are a ubiquitous and diverse family of stress proteins that have in common an alpha-crystallin domain. Mycobacterium tuberculosis has two small heat shock proteins, Acr1 (alpha-crystallin-related protein 1, or Hsp16.3/16-kDa antigen) and Acr2 (HrpA), both of which are highly expressed under different stress conditions. Small heat shock proteins form large oligomeric assemblies and are commonly polydisperse. Nanoelectrospray mass spectrometry showed that Acr2 formed a range of oligomers composed of dimers and tetramers, whereas Acr1 was a dodecamer. Electron microscopy of Acr2 showed a variety of particle sizes. Using three-dimensional analysis of negative stain electron microscope images, we have shown that Acr1 forms a tetrahedral assembly with 12 polypeptide chains. The atomic structure of a related alpha-crystallin domain dimer was docked into the density to build a molecular structure of the dodecameric Acr1 complex. Along with the differential regulation of these two proteins, the differences in their quaternary structures demonstrated here supports their distinct functional roles.