Structural links to kinesin directionality and movement

The kinesin motor proteins generate directional movement along microtubules and are involved in many vital processes, including cell division, in eukaryotes. The kinesin superfamily is characterized by a conserved motor domain of approximately 320 residues. Dimeric constructs of N and C class kinesins, with the motor domains at opposite ends of the heavy chain, move towards microtubule plus and minus ends, respectively. Their crystal structures differ mainly in the region linking the motor domain core to the alpha-helical coiled coil dimerization domain. Chimeric kinesins show that regions outside of the motor domain core determine the direction of movement and mutations in the linker region have a strong effect on motility. Recent work on chimeras and mutants is discussed in a structural context giving insights to possible molecular mechanisms of kinesin directionality and motility.