PT  - JOURNAL ARTICLE
AU  - Andrew R. Popchock
AU  - Kuo-Fu Tseng
AU  - Pan Wang
AU  - P. Andrew Karplus
AU  - Xin Xiang
AU  - Weihong Qiu
TI  - The mitotic kinesin-14 KlpA contains a context-dependent directionality switch
AID  - 10.1101/058602
DP  - 2016 Jan 01
TA  - bioRxiv
PG  - 058602
4099  - http://biorxiv.org/content/early/2016/06/23/058602.short
4100  - http://biorxiv.org/content/early/2016/06/23/058602.full
AB  - Kinesins are microtubule-based motor proteins that convert chemical energy from ATP hydrolysis into mechanical work for a variety of essential intracellular processes. Kinesin-14s (i.e. kinesins with a C-terminal motor domain) are commonly considered to be nonprocessive minus end-directed motors that mainly function for mitotic spindle assembly and maintenance. Here, we show that KlpA – a mitotic kinesin-14 motor from the filamentous fungus Aspergillus nidulans – contains a context-dependent directionality switch. KlpA exhibits canonical minus end-directed motility inside microtubule bundles, but on individual microtubules it unexpectedly moves processively toward the plus ends. Removal of the N-terminal nonmotor microtubule-binding domain renders KlpA diffusive on individual microtubules but does not abolish its minus end-directed motility to collectively glide microtubules, suggesting that the nonmotor microtubule-binding domain likely acts as a switch for controlling the direction of KlpA motility. Collectively, these findings provide important insights into the mechanism and regulation of KlpA functions inside the mitotic spindle.