Department of Chemistry & Biochemistry, Miami University, Oxford, OH 45056, USA.
Department of Physics, Denison University, Granville, OH 43023, USA.
Int J Mol Sci. 2021 Feb 23;22(4):2200. doi: 10.3390/ijms22042200.
The 70 kDa and 90 kDa heat shock proteins Hsp70 and Hsp90 are two abundant and highly conserved ATP-dependent molecular chaperones that participate in the maintenance of cellular homeostasis. In , Hsp90 (Hsp90Ec) and Hsp70 (DnaK) directly interact and collaborate in protein remodeling. Previous work has produced a model of the direct interaction of both chaperones. The locations of the residues involved have been confirmed and the model has been validated. In this study, we investigate the allosteric communication between Hsp90Ec and DnaK and how the chaperones couple their conformational cycles. Using elastic network models (ENM), normal mode analysis (NMA), and a structural perturbation method (SPM) of asymmetric and symmetric DnaK-Hsp90Ec, we extract biologically relevant vibrations and identify residues involved in allosteric signaling. When one DnaK is bound, the dominant normal modes favor biological motions that orient a substrate protein bound to DnaK within the substrate/client binding site of Hsp90Ec and release the substrate from the DnaK substrate binding domain. The presence of one DnaK molecule stabilizes the entire Hsp90Ec protomer to which it is bound. Conversely, the symmetric model of DnaK binding results in steric clashes of DnaK molecules and suggests that the Hsp90Ec and DnaK chaperone cycles operate independently. Together, this data supports an asymmetric binding of DnaK to Hsp90Ec.
70kDa 和 90kDa 热休克蛋白 Hsp70 和 Hsp90 是两种丰富且高度保守的 ATP 依赖性分子伴侣，参与维持细胞内环境稳定。在大肠杆菌中，Hsp90（Hsp90Ec）和 Hsp70（DnaK）直接相互作用并协同进行蛋白质重塑。先前的工作已经产生了这两种伴侣蛋白直接相互作用的模型。涉及残基的位置已得到确认，并且该模型已得到验证。在这项研究中，我们研究了 Hsp90Ec 和 DnaK 之间的变构通讯以及伴侣蛋白如何耦合它们的构象循环。使用弹性网络模型（ENM）、正常模式分析（NMA）和不对称和对称 DnaK-Hsp90Ec 的结构扰动方法（SPM），我们提取了生物相关的振动并确定了参与变构信号的残基。当一个 DnaK 被结合时，主导的正常模式有利于将与 DnaK 结合的底物蛋白定向到 Hsp90Ec 的底物/客户结合位点内，并将底物从 DnaK 底物结合域中释放出来。一个 DnaK 分子的存在稳定了与其结合的整个 Hsp90Ec 原聚体。相反，DnaK 结合的对称模型导致 DnaK 分子的空间冲突，并表明 Hsp90Ec 和 DnaK 伴侣蛋白循环独立运行。总之，这些数据支持 DnaK 与 Hsp90Ec 的不对称结合。
