Hop as an adaptor in the heat shock protein 70 (Hsp70) and Hsp90 chaperone machinery
Hop as an adaptor in the heat shock protein 70 (Hsp70) and Hsp90 chaperone machinery
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DOI：
10.1074/jbc.273.52.35194
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发表时间：
1998-12-25
影响因子：
4.8
通讯作者：
Smith, DF
中科院分区：
文献类型：
--
作者：
Chen, SY;Smith, DF
Hop是一种丰富且功能不明的保守蛋白，与热休克蛋白70 （Hsp70）和Hsp90结合，在孕酮受体组装的中间阶段参与热休克蛋白，并且是体外成熟受体复合物有效组装所必需的。一个很大程度上未经验证的假设是Hop作为靶向Hsp90-至Hsp70底物复合物的接头；如果这是真的，那么Hop失去Hsp70或Hsp90的结合，同样会破坏其促进成熟受体复合物组装的能力。为了产生选择性破坏热休克蛋白相互作用的啤酒花突变体，在先前绘制的啤酒花Hsp70和Hsp90结合域以及保守的c端结构域中的高度保守的氨基酸被靶向进行小的取代和缺失。在共沉淀试验中，这些突变体表现出与热休克蛋白的选择性丧失。在使用无hopp的兔网织细胞裂解液进行受体复合物的无细胞组装的实验中，没有一个突变体抑制Hsp70与受体的结合，但所有突变体在支持hsp90受体相互作用方面都存在缺陷。因此，Hop作为一种整合Hsp70和Hsp90相互作用的适配器，在伴侣机制中具有新的作用。
Hop, an abundant and conserved protein of unresolved function, binds concomitantly with heat shock protein 70 (Hsp70) and Hsp90, participates with heat shock proteins at an intermediate stage of progesterone receptor assembly, and is required for efficient assembly of mature receptor complexes in vitro, A largely untested hypothesis is that Hop functions as an adaptor that targets Hsp90- to Hsp70-substrate complexes; if true, then loss of either Hsp70 binding or Hsp90 binding by Hop should equally disrupt its ability to promote assembly of mature receptor complexes. To generate Hop mutants that selectively disrupt heat shock protein interactions, highly conserved amino acids in the previously mapped Hsp70 and Hsp90 binding domains of Hop and in a conserved C-terminal domain were targeted for small substitutions and deletions. In co-precipitation assays, these mutants displayed selective loss of association with heat shock proteins. In assays using Hop-depleted rabbit reticulocyte lysate for the cell-free assembly of receptor complexes, none of the Hop mutants inhibited Hsp70 binding to receptor, but all mutants were defective in supporting Hsp90-receptor interactions. Thus, Hop has a novel role in the chaperone machinery as an adaptor that can integrate Hsp70 and Hsp90 interactions.