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Curr Biol. 2018 Jul 23;28(14):2302-2308.e3. doi: 10.1016/j.cub.2018.05.026. Epub 2018 Jul 12.

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

Author information

1
Institute of Photobiophysics, Henan University, Kaifeng, Henan 475004, China; Department of Physics, Oregon State University, Corvallis, OR 97331, USA.
2
Department of Physics, Oregon State University, Corvallis, OR 97331, USA.
3
School of Physics, Nankai University, Tianjin 300071, China.
4
Life Sciences Institute and Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA.
5
Institute of Photobiophysics, Henan University, Kaifeng, Henan 475004, China.
6
Department of Physics, Oregon State University, Corvallis, OR 97331, USA; Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331, USA. Electronic address: weihong.qiu@physics.oregonstate.edu.

Abstract

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.

KEYWORDS:

TIRF microscopy; directionality; kinesin-14; processivity

PMID:
30017487
DOI:
10.1016/j.cub.2018.05.026
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