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Proc Natl Acad Sci U S A. 2018 Feb 20;115(8):E1779-E1788. doi: 10.1073/pnas.1718290115. Epub 2018 Feb 5.

A posttranslational modification of the mitotic kinesin Eg5 that enhances its mechanochemical coupling and alters its mitotic function.

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Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455.
Department of Developmental and Cell Biology, University of California, Irvine, CA 92697.
Department of Physics, University of California, Irvine, CA 92697.
Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI 48109.
Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05405.
Department of Cancer Biology, Lerner Research Institute of the Cleveland Clinic Foundation, Cleveland, OH 44195.
Department of Radiation Oncology, Ohio State University, Columbus, OH 43210.
Department of Medicine, University of California, San Diego, La Jolla, CA 92093.
Division of Biological Sciences, Section of Molecular Biology, University of California, San Diego, La Jolla, CA 92093.


Numerous posttranslational modifications have been described in kinesins, but their consequences on motor mechanics are largely unknown. We investigated one of these-acetylation of lysine 146 in Eg5-by creating an acetylation mimetic lysine to glutamine substitution (K146Q). Lysine 146 is located in the α2 helix of the motor domain, where it makes an ionic bond with aspartate 91 on the neighboring α1 helix. Molecular dynamics simulations predict that disrupting this bond enhances catalytic site-neck linker coupling. We tested this using structural kinetics and single-molecule mechanics and found that the K146Q mutation increases motor performance under load and coupling of the neck linker to catalytic site. These changes convert Eg5 from a motor that dissociates from the microtubule at low load into one that is more tightly coupled and dissociation resistant-features shared by kinesin 1. These features combined with the increased propensity to stall predict that the K146Q Eg5 acetylation mimetic should act in the cell as a "brake" that slows spindle pole separation, and we have confirmed this by expressing this modified motor in mitotically active cells. Thus, our results illustrate how a posttranslational modification of a kinesin can be used to fine tune motor behavior to meet specific physiological needs.


acetylation; kinesin; mitosis; molecular motor

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