Chromokinesins NOD and KID Use Distinct ATPase Mechanisms and Microtubule Interactions To Perform a Similar Function.

Chromokinesins NOD and KID have similar DNA binding domains and functions during cell division, while their motor domain sequences show significant variations. It has been unclear whether these motors have the similar structure, chemistry, and microtubule interactions necessary to follow a similar mechanism of force generation. We used biochemical rate measurements, cosedimentation, and structural analysis to investigate the ATPase mechanisms of the NOD and KID core domains. These studies revealed that NOD and KID have different ATPase mechanisms, microtubule interactions, and catalytic domain structures. The ATPase cycles of NOD and KID have different rate-limiting steps. The ATPase rate of NOD was robustly stimulated by microtubules, and its microtubule affinity was weakened in all nucleotide-bound states. KID bound microtubules tightly in all nucleotide states and remained associated with the microtubule for more than 100 cycles of ATP hydrolysis before dissociating. The structure of KID was most like that of conventional kinesin (KIF5). Key differences in the microtubule binding region and allosteric communication pathway between KID and NOD are consistent with our biochemical data. Our results support the model in which NOD and KID utilize distinct mechanistic pathways to achieve the same function during cell division.