Differences in single-motor and multi-motor motility properties across the kinesin-6 family

Kinesin motor proteins are responsible for orchestrating a variety of microtubule-based processes including intracellular transport, cell division, cytoskeletal organization, and cilium function. During cell division, members of the kinesin-6 family play critical roles in anaphase and cytokinesis, however little is known about their motility properties. We find that truncated versions of MKLP1 (HsKIF23), MKLP2 (HsKIF20A), and HsKIF20B predominately display non-processive behavior as single molecules although slow, processive motility was occasionally observed, most prominently for MKLP2. Despite their non-processive nature, all kinesin-6 proteins were able to work in teams to drive microtubule gliding. MKLP1 and KIF20B were also able to work in teams to drive robust transport of both peroxisomes, a low-load cargo, and Golgi, a high-load cargo, in cells. In contrast, MKLP2 showed minimal transport of peroxisomes and was unable to drive Golgi dispersion. These results indicate that while all three mammalian kinesin-6 motor proteins are generally non-processive as single motors, they differ in their ability to work in teams and generate forces needed to drive cargo transport in cells.