Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Mol Cell. 2013 Feb 7;49(3):464-73. doi: 10.1016/j.molcel.2012.11.017. Epub 2012 Dec 20.
The heat shock protein 90 (Hsp90) family of heat shock proteins is an abundantly expressed and highly conserved family of ATP-dependent molecular chaperones. Hsp90 facilitates remodeling and activation of hundreds of proteins. In this study, we developed a screen to identify Hsp90-defective mutants in E. coli. The mutations obtained define a region incorporating residues from the middle and C-terminal domains of E. coli Hsp90. The mutant proteins are defective in chaperone activity and client binding in vitro. We constructed homologous mutations in S. cerevisiae Hsp82 and identified several that caused defects in chaperone activity in vivo and in vitro. However, the Hsp82 mutant proteins were less severely defective in client binding to a model substrate than the corresponding E. coli mutant proteins. Our results identify a region in Hsp90 important for client binding in E. coli Hsp90 and suggest an evolutionary divergence in the mechanism of client interaction by bacterial and yeast Hsp90.
热休克蛋白 90（Hsp90）家族是一类高度保守且广泛表达的 ATP 依赖性分子伴侣。Hsp90 能够促进数百种蛋白质的构象重排和激活。在本研究中，我们开发了一种筛选方法，以鉴定大肠杆菌中 Hsp90 缺陷突变体。获得的突变定义了一个包含大肠杆菌 Hsp90 中域和 C 末端域残基的区域。这些突变蛋白在体外的伴侣活性和客户结合中存在缺陷。我们在酿酒酵母 Hsp82 中构建了同源突变，并鉴定出几个突变体在体内和体外的伴侣活性存在缺陷。然而，与相应的大肠杆菌突变蛋白相比，Hsp82 突变蛋白在与模型底物的客户结合方面的缺陷程度较轻。我们的结果确定了大肠杆菌 Hsp90 中与客户结合相关的重要区域，并提示细菌和酵母 Hsp90 在客户相互作用的机制上存在进化分歧。
