Blacklock Kristin, Verkhivker Gennady M
School of Computational Sciences and Crean School of Health and Life Sciences, Schmid College of Science and Technology, Chapman University, Orange, California, United States of America.
School of Computational Sciences and Crean School of Health and Life Sciences, Schmid College of Science and Technology, Chapman University, Orange, California, United States of America ; Department of Pharmacology, University of California San Diego, La Jolla, California, United States of America.
PLoS One. 2014 Jan 20;9(1):e86547. doi: 10.1371/journal.pone.0086547. eCollection 2014.
The fundamental role of the Hsp90 chaperone in supporting functional activity of diverse protein clients is anchored by specific cochaperones. A family of immune sensing client proteins is delivered to the Hsp90 system with the aid of cochaperones Sgt1 and Rar1 that act cooperatively with Hsp90 to form allosterically regulated dynamic complexes. In this work, functional dynamics and protein structure network modeling are combined to dissect molecular mechanisms of Hsp90 regulation by the client recruiter cochaperones. Dynamic signatures of the Hsp90-cochaperone complexes are manifested in differential modulation of the conformational mobility in the Hsp90 lid motif. Consistent with the experiments, we have determined that targeted reorganization of the lid dynamics is a unifying characteristic of the client recruiter cochaperones. Protein network analysis of the essential conformational space of the Hsp90-cochaperone motions has identified structurally stable interaction communities, interfacial hubs and key mediating residues of allosteric communication pathways that act concertedly with the shifts in conformational equilibrium. The results have shown that client recruiter cochaperones can orchestrate global changes in the dynamics and stability of the interaction networks that could enhance the ATPase activity and assist in the client recruitment. The network analysis has recapitulated a broad range of structural and mutagenesis experiments, particularly clarifying the elusive role of Rar1 as a regulator of the Hsp90 interactions and a stability enhancer of the Hsp90-cochaperone complexes. Small-world organization of the interaction networks in the Hsp90 regulatory complexes gives rise to a strong correspondence between highly connected local interfacial hubs, global mediator residues of allosteric interactions and key functional hot spots of the Hsp90 activity. We have found that cochaperone-induced conformational changes in Hsp90 may be determined by specific interaction networks that can inhibit or promote progression of the ATPase cycle and thus control the recruitment of client proteins.
热休克蛋白90（Hsp90）伴侣蛋白在支持多种蛋白质客户功能活性方面的基本作用由特定的辅助伴侣蛋白所支撑。一类免疫传感客户蛋白借助辅助伴侣蛋白 Sgt1 和 Rar1 被递送至 Hsp90 系统，它们与 Hsp90 协同作用，形成变构调节的动态复合物。在这项工作中，功能动力学与蛋白质结构网络建模相结合，以剖析客户招募辅助伴侣蛋白对 Hsp90 调节的分子机制。Hsp90 - 辅助伴侣蛋白复合物的动态特征体现在 Hsp90 盖子基序构象流动性的差异调节中。与实验结果一致，我们确定盖子动力学的靶向重组是客户招募辅助伴侣蛋白的一个统一特征。对 Hsp90 - 辅助伴侣蛋白运动的基本构象空间进行蛋白质网络分析，确定了结构稳定的相互作用群落、界面枢纽以及变构通讯途径的关键介导残基，它们与构象平衡的变化协同作用。结果表明，客户招募辅助伴侣蛋白可以协调相互作用网络动态和稳定性的全局变化，这可能增强 ATP 酶活性并协助客户招募。网络分析概括了广泛的结构和诱变实验，尤其阐明了 Rar1 作为 Hsp90 相互作用调节剂和 Hsp90 - 辅助伴侣蛋白复合物稳定性增强剂这一难以捉摸的作用。Hsp90 调节复合物中相互作用网络的小世界组织导致高度连接的局部界面枢纽、变构相互作用的全局介导残基与 Hsp90 活性的关键功能热点之间存在强烈对应关系。我们发现辅助伴侣蛋白诱导的 Hsp90 构象变化可能由特定的相互作用网络决定，这些网络可以抑制或促进 ATP 酶循环的进程，从而控制客户蛋白的招募。
