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

作者：Muretta Joseph M; Reddy Babu J N; Scarabelli Guido; Thompson Alex F; Jariwala Shashank; Major Jennifer; Venere Monica; Rich Jeremy N; Willard Belinda; Thomas David D; Stumpff Jason; Grant Barry J; Gross Steven P; Rosenfeld Steven S^*

来源：Proceedings of the National Academy of Sciences, 2018, 115(8): E1779-E1788.

DOI：10.1073/pnas.1718290115

• kinesin
• acetylation
• mitosis
• molecular motor

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 alpha 2 helix of the motor domain, where it makes an ionic bond with aspartate 91 on the neighboring alpha 1 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.

• 出版日期2018-2-20