The C-terminus of kinesin-14 Ncd is a crucial component of the force generating mechanism

Ncd is a kinesin which participates in the formation and organization of the mitotic spindle. It was suggested that the C-terminal 30 amino acids of Ncd located next to the head play an important role in the generation of movement, acting as a “neck linker”. In order to examine the role of the C-terminus we constructed four Ncd mutants in which this region was altered or deleted. Ncd without the C-terminal region bound microtubules with much lower affinity, moved slower in in vitro motility assay and inefficiently hydrolyzed ATP. We showed that a 9-residue-long basic fragment of the region was sufficient to achieve high affinity to microtubules and fast ATP hydrolysis. However, the basic fragment alone was not enough for efficient movement generation. These findings support the hypothesis that force generation mechanism by Ncd is similar to kinesin-1. In both kinesins this process involves making and breaking of the bonds between the head and neck controlled by ATP hydrolysis.

23 April 2012