CYK4 relaxes the bias in the off-axis motion by MKLP1 kinesin-6.

Affiliation

Maruyama Y(1), Sugawa M(1)(2), Yamaguchi S(1), Davies T(3)(4), Osaki T(5), Kobayashi T(1), Yamagishi M(1)(2), Takeuchi S(5)(6), Mishima M(7), Yajima J(8)(9)(10).
Author information:
(1)Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan.
(2)Komaba Institute for Science, The University of Tokyo, Meguro-ku, Tokyo, Japan.
(3)Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK.
(4)Department of Biosciences, Durham University, Durham, UK.
(5)Institute of Industrial Science, The University of Tokyo, Meguro-ku, Tokyo, Japan.
(6)Research Center for complex Systems Biology, The University of Tokyo, Meguro-ku, Tokyo, Japan.
(7)Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK. [Email]
(8)Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan. [Email]
(9)Komaba Institute for Science, The University of Tokyo, Meguro-ku, Tokyo, Japan. [Email]
(10)Research Center for complex Systems Biology, The University of Tokyo, Meguro-ku, Tokyo, Japan. [Email]

Abstract

Centralspindlin, a complex of the MKLP1 kinesin-6 and CYK4 GAP subunits, plays key roles in metazoan cytokinesis. CYK4-binding to the long neck region of MKLP1 restricts the configuration of the two MKLP1 motor domains in the centralspindlin. However, it is unclear how the CYK4-binding modulates the interaction of MKLP1 with a microtubule. Here, we performed three-dimensional nanometry of a microbead coated with multiple MKLP1 molecules on a freely suspended microtubule. We found that beads driven by dimeric MKLP1 exhibited persistently left-handed helical trajectories around the microtubule axis, indicating torque generation. By contrast, centralspindlin, like monomeric MKLP1, showed similarly left-handed but less persistent helical movement with occasional rightward movements. Analysis of the fluctuating helical movement indicated that the MKLP1 stochastically makes off-axis motions biased towards the protofilament on the left. CYK4-binding to the neck domains in MKLP1 enables more flexible off-axis motion of centralspindlin, which would help to avoid obstacles along crowded spindle microtubules.