Zhang Huaqun, Zhou Chen, Chen Wuyan, Xu Yechun, Shi Yanhong, Wen Yi, Zhang Naixia
Department of Analytical Chemistry, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, P. R. China.
CAS Key Laboratory of Receptor Research, Drug Discovery and Design Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, P. R. China.
Sci Rep. 2015 Apr 13;5:9542. doi: 10.1038/srep09542.
Heat-shock protein 90 (Hsp90) is one of the most important chaperones involved in multiple cellular processes. The chaperoning function of Hsp90 is intimately coupled to the ATPase activity presented by its N-terminal domain. However, the molecular mechanism for the ATP-dependent working cycle of Hsp90 is still not fully understood. In this study, we use NMR techniques to investigate the structural characteristics and dynamic behaviors of Hsp90 N-terminal domain in its free and AMPPCP (ATP analogue) or ADP-bound states. We demonstrated that although AMPPCP and ADP bind to almost the same region of Hsp90, significantly different effects on the dynamics behaviors of the key structural elements were observed. AMPPCP binding favors the formation of the active homodimer of Hsp90 by enhancing the slow-motion featured conformational exchanges of those residues (A117-A141) within the lid segment (A111-G135) and around region, while ADP binding keeps Hsp90 staying at the inactive state by increasing the conformational rigidity of the lid segment and around region. Based on our findings, a dynamic working model for the ATP-dependent functioning cycle of Hsp90 was proposed.
热休克蛋白90（Hsp90）是参与多种细胞过程的最重要伴侣蛋白之一。Hsp90的伴侣功能与其N端结构域呈现的ATP酶活性密切相关。然而，Hsp90依赖ATP的工作循环的分子机制仍未完全阐明。在本研究中，我们使用核磁共振技术研究Hsp90 N端结构域在游离状态、与AMPPCP（ATP类似物）或ADP结合状态下的结构特征和动态行为。我们证明，尽管AMPPCP和ADP与Hsp90的几乎相同区域结合，但观察到它们对关键结构元件的动态行为有显著不同的影响。AMPPCP结合通过增强盖子片段（A111-G135）内及周围区域（A117-A141）那些残基的慢运动特征性构象交换，有利于Hsp90活性同源二聚体的形成，而ADP结合通过增加盖子片段及周围区域的构象刚性使Hsp90保持在非活性状态。基于我们的发现，提出了Hsp90依赖ATP的功能循环的动态工作模型。
