Structural characterization of the substrate transfer mechanism in Hsp70/Hsp90 folding machinery mediated by Hop
Structural characterization of the substrate transfer mechanism in Hsp70/Hsp90 folding machinery mediated by Hop
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DOI：
10.1038/ncomms6484
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发表时间：
2014-11-01
影响因子：
16.6
通讯作者：
Valpuesta, Jose M.
中科院分区：
文献类型：
--
作者：
Alvira, Sara;Cuellar, Jorge;Valpuesta, Jose M.
在真核生物中，伴侣蛋白Hsp70和Hsp90在几个共同伴侣蛋白的帮助下协同作用于一系列关键蛋白的折叠和成熟，尤其是Hop。虽然生化数据定义了hop介导的Hsp70-Hsp90底物转移机制，但这些蛋白质的内在灵活性及其复合物的动态性质限制了该机制的结构研究。在这里，我们在Hsp70/Hsp90折叠途径中生成了几个复合物（Hsp90: Hop， Hsp90: Hop: Hsp70和Hsp90: Hop: Hsp70与客户蛋白糖皮质激素受体（GR-LBD）片段），并使用电子显微镜技术确定了它们的3D结构。我们的研究结果表明，当Hsp70或Hsp70: GR-LBD与Hsp90: Hop结合时，通过Hop结构域重排，一个Hop分子以扩展和紧凑的构象结合在Hsp90二聚体的一侧。Hsp90: Hop: Hsp70: GR-LBD复合物的紧凑构象表明GR-LBD与Hsp90二聚体在Hop附着位点对面的一侧结合。
In eukarya, chaperones Hsp70 and Hsp90 act coordinately in the folding and maturation of a range of key proteins with the help of several co-chaperones, especially Hop. Although biochemical data define the Hop-mediated Hsp70-Hsp90 substrate transfer mechanism, the intrinsic flexibility of these proteins and the dynamic nature of their complexes have limited the structural studies of this mechanism. Here we generate several complexes in the Hsp70/Hsp90 folding pathway (Hsp90: Hop, Hsp90: Hop: Hsp70 and Hsp90: Hop: Hsp70 with a fragment of the client protein glucocorticoid receptor (GR-LBD)), and determine their 3D structure using electron microscopy techniques. Our results show that one Hop molecule binds to one side of the Hsp90 dimer in both extended and compact conformations, through Hop domain rearrangement that take place when Hsp70 or Hsp70: GR-LBD bind to Hsp90: Hop. The compact conformation of the Hsp90: Hop: Hsp70: GR-LBD complex shows that GR-LBD binds to the side of the Hsp90 dimer opposite the Hop attachment site.