Structural highlights
FunctionTBA1B_PIG Tubulin is the major constituent of microtubules. It binds two moles of GTP, one at an exchangeable site on the beta chain and one at a non-exchangeable site on the alpha chain. Publication Abstract from PubMedKinesin 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 beta-sheet twisting, which triggers the power stroke - stalk rotation and neck mimic docking - upon ATP binding. Microtubule release occurs with beta-strand-to-loop transitions, implying that beta-strand refolding induces Pi release and the recovery stroke. The strained beta-sheet during the power stroke and strand-to-loop transitions identify the beta-sheet as the long-sought motor spring. Structural transitions in kinesin minus-end directed microtubule motility.,Shibata S, Wang MY, Imasaki T, Shigematsu H, Wei Y, Jobichen C, Hagio H, Sivaraman J, Endow SA, Nitta R bioRxiv [Preprint]. 2024 Jul 29:2024.07.29.605428. doi: , 10.1101/2024.07.29.605428. PMID:39131399[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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