The Central Stalk Determines the Motility of Mitotic Kinesin-14 Homodimers

• Published in: Current biology Vol. 28; no. 14; pp. 2302 - 2308.e3
• Main Authors: Wang, Pan, Tseng, Kuo-Fu, Gao, Yuan, Cianfrocco, Michael, Guo, Lijun, Qiu, Weihong
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 23.07.2018
• Subjects: directionality; kinesin-14; processivity; TIRF microscopy; directionality; processivity; TIRF microscopy; kinesin-14
• ISSN: 0960-9822; 1879-0445
• DOI: 10.1016/j.cub.2018.05.026

Mitotic kinesin-14 homodimers that contain an N-terminal nonmotor microtubule-binding tail contribute to spindle organization by preferentially crosslinking two different spindle microtubules rather than interacting with a single microtubule to generate processive motility. However, the mechanism underlying such selective motility behavior remains poorly understood. Here, we show that when a flexible polypeptide linker is inserted into the coiled-coil central stalk, two homodimeric mitotic kinesin-14s of distinct motility—the processive plus-end-directed KlpA from Aspergillus nidulans [1] and the nonprocessive minus-end-directed Ncd from Drosophila melanogaster [2]—both switch to become processive minus-end-directed motors. Our results demonstrate that the polypeptide linker introduces greater conformational flexibility into the central stalk. Importantly, we find that the linker insertion significantly weakens the ability of Ncd to preferentially localize between and interact with two microtubules. Collectively, our results reveal that besides the canonical role of enabling dimerization, the central stalk also functions as a mechanical component to determine the motility of homodimeric mitotic kinesin-14 motors. We suggest that the central stalk is an evolutionary design that primes these kinesin-14 motors for nontransport roles within the mitotic spindle. •Enhanced central stalk flexibility causes KlpA to switch directionality•Ncd gains processive motility with enhanced central stalk flexibility•Enhanced central stalk flexibility weakens microtubule crosslinking by Ncd Wang et al. show that the central stalk, a coiled-coil structure commonly believed to mainly act as a structural component to enable dimerization, also functions as a mechanical coupler to determine the motility of mitotic kinesin-14 homodimers.