Introduction of Kinesin-13 family specific residues increases the microtubule end residence time of a Kinesin-1
Kinesins that regulate microtubule dynamics, such as the Kinesin-13 MCAK, require the ability to recognise the microtubule end. All microtubule regulating kinesins studied to date have this ability and thus exhibit increased microtubule end residence times. In contrast, purely translocating kinesins such as Kinesin-1 do not need to recognise the microtubule end for their function. The residues K524, E525 and R528 in the 4 helix of the Kinesin-13, MCAK, are critical for microtubule end recognition. Here, we show that introducing these Kinesin-13 family-specific residues into a Kinesin-1 increases its microtubule-end residence time up to 4-fold. However, this increase in end residence is not sufficient to confer microtubule depolymerisation activity to a Kinesin-1.\n\nSignificance StatementThe introduction of Kinesin-13 family specific residues from the 4 helix of the microtubule depolymerising kinesin, MCAK, into a Kinesin-1, increases the microtubule-end residence time between 2 and 4-fold. This demonstrates both the significance of these residues in modulating microtubule end residence, and the capacity to tune kinesin function by modifying the microtubule binding face of the motor domain using protein engineering. Increasing the microtubule end residence time in this way is not sufficient to confer depolymerisation activity to a Kinesin-1. Thus, indicating that the ability to recognise and reside at the microtubule end is not the only determinant of depolymerisation activity. The Kinesin-13 motor domain may also possess the ability to actively break interactions between tubulin subunits.