Shibata Satoki, Wang Matthew Y, Imasaki Tsuyoshi, Shigematsu Hideki, Wei Yuanyuan, Jobichen Chacko, Hagio Hajime, Sivaraman J, Endow Sharyn A, Nitta Ryo
Division of Structural Medicine and Anatomy, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, Kobe, 650-0017, Japan.
Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA.
bioRxiv. 2024 Jul 29:2024.07.29.605428. doi: 10.1101/2024.07.29.605428.
Kinesin motor proteins hydrolyze ATP to produce force for spindle assembly and vesicle transport, performing essential functions in cell division and motility, but the structural changes required for force generation are uncertain. We now report high-resolution structures showing new transitions in the kinesin mechanochemical cycle, including power stroke fluctuations upon ATP binding and a post-hydrolysis state with bound ADP + free phosphate. We find that rate-limiting ADP release occurs upon microtubule binding, accompanied by central β-sheet twisting, which triggers the power stroke - stalk rotation and neck mimic docking - upon ATP binding. Microtubule release occurs with β-strand-to-loop transitions, implying that β-strand refolding induces Pi release and the recovery stroke. The strained β-sheet during the power stroke and strand-to-loop transitions identify the β-sheet as the long-sought motor spring.
驱动蛋白运动蛋白水解三磷酸腺苷（ATP）以产生用于纺锤体组装和囊泡运输的力，在细胞分裂和运动中发挥着重要功能，但产生力所需的结构变化尚不确定。我们现在报告的高分辨率结构显示了驱动蛋白机械化学循环中的新转变，包括ATP结合时的动力冲程波动以及结合ADP +游离磷酸的水解后状态。我们发现，限速的ADP释放发生在微管结合时，伴随着中央β折叠片层的扭曲，这在ATP结合时触发动力冲程——柄部旋转和颈部模拟对接。微管释放伴随着β链到环的转变，这意味着β链重新折叠诱导磷酸根离子（Pi）释放和恢复冲程。动力冲程和链到环转变过程中紧张的β折叠片层将β折叠片层确定为长期寻找的马达弹簧。
