Communications Biology ( IF 5.2 ) Pub Date : 2024-03-02 , DOI: 10.1038/s42003-024-05959-3 Lorenzo I Finci 1 , Mayukh Chakrabarti 1 , Gulcin Gulten 1 , Joseph Finney 2 , Carissa Grose 1 , Tara Fox 2 , Renbin Yang 3 , Dwight V Nissley 1 , Frank McCormick 1, 4 , Dominic Esposito 1 , Trent E Balius 1 , Dhirendra K Simanshu 1
RAF kinases are integral to the RAS-MAPK signaling pathway, and proper RAF1 folding relies on its interaction with the chaperone HSP90 and the cochaperone CDC37. Understanding the intricate molecular interactions governing RAF1 folding is crucial for comprehending this process. Here, we present a cryo-EM structure of the closed-state RAF1-HSP90-CDC37 complex, where the C-lobe of the RAF1 kinase domain binds to one side of the HSP90 dimer, and an unfolded N-lobe segment of the RAF1 kinase domain threads through the center of the HSP90 dimer. CDC37 binds to the kinase C-lobe, mimicking the N-lobe with its HxNI motif. We also describe structures of HSP90 dimers without RAF1 and CDC37, displaying only N-terminal and middle domains, which we term the semi-open state. Employing 1 μs atomistic simulations, energetic decomposition, and comparative structural analysis, we elucidate the dynamics and interactions within these complexes. Our quantitative analysis reveals that CDC37 bridges the HSP90-RAF1 interaction, RAF1 binds HSP90 asymmetrically, and that HSP90 structural elements engage RAF1’s unfolded region. Additionally, N- and C-terminal interactions stabilize HSP90 dimers, and molecular interactions in HSP90 dimers rearrange between the closed and semi-open states. Our findings provide valuable insight into the contributions of HSP90 and CDC37 in mediating client folding.
中文翻译:
RAF1-HSP90-CDC37 和 HSP90 复合物的结构动力学揭示了不对称的客户相互作用和关键结构元件
RAF 激酶是 RAS-MAPK 信号通路不可或缺的一部分,适当的 RAF1 折叠取决于它与伴侣 HSP90 和伴侣 CDC37 的相互作用。了解控制 RAF1 折叠的复杂分子相互作用对于理解这一过程至关重要。在这里,我们提出了闭态 RAF1-HSP90-CDC37 复合物的冷冻电镜结构,其中 RAF1 激酶结构域的 C 叶与 HSP90 二聚体的一侧结合,RAF1 激酶结构域的展开 N 叶段穿过 HSP90 二聚体的中心。CDC37 与激酶 C 叶结合,模拟具有 HxNI 基序的 N 叶。我们还描述了没有 RAF1 和 CDC37 的 HSP90 二聚体的结构,仅显示 N 末端和中间结构域,我们称之为半开放状态。采用 1 μs 原子模拟、能量分解和比较结构分析,我们阐明了这些复合物内的动力学和相互作用。我们的定量分析表明,CDC37 桥接 HSP90-RAF1 相互作用,RAF1 不对称地结合 HSP90,并且 HSP90 结构元件参与 RAF1 的展开区域。此外,N 端和 C 端相互作用稳定了 HSP90 二聚体,HSP90 二聚体中的分子相互作用在闭合和半开放状态之间重排。我们的研究结果为 HSP90 和 CDC37 在介导客户折叠中的作用提供了有价值的见解。