Microtubule C-terminal tails can change characteristics of motor force production

Mitra Shojania Feizabadi, Babu Reddy J N, Omid Vadpey, Yonggun Jun, Dail Chapman, Steven Rosenfeld and Steven P. Gross

Control of intracellular transport is poorly understood, and functional ramifications of tubulin isoform differences between cell types are mostly unexplored. Motors’ force production and detachment kinetics are critical for their group function, but how microtubule details affect these properties—if at all—are unknown. We investigated these questions using both a vesicular transport human kinesin, Kinesin-1 and also a mitotic kinesin likely optimized for group function, Kinesin-5, moving along either bovine brain or MCF7(breast cancer) microtubules. We found that kinesin-1 functioned similarly on the two sets of microtubules—in particular, its mean force production was approximately the same, though due to its previously reported decreased processivity, the mean duration of Kinesin-1 force production was slightly decreased on MCF7 MTs.
In contrast, Kinesin-5's function changed dramatically on MCF7 microtubules: its average detachment force was reduced and its force-velocity curve was different. In spite of the reduced detachment force, the force-velocity alteration surprisingly improved high-load group function for Kinesin-5 on the cancer-cell microtubules, potentially contributing to functions such as spindle-mediated chromosome separation. Significant differences were previously reported for C-terminal tubulin tails in MCF7 vs bovine brain tubulin. Consistent with this difference being functionally important, elimination of the tails made transport along the two sets of microtubules similar.

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