A unique kinesin-8 surface loop provides specificity for chromosome alignment

• DOI: 10.1091/mbc.e14-06-1132
• Publication Date: 2014-09-11T02:04:48Z
• Authors: Haein Kim; Cindy Fonseca; Jason Stumpff
• Keywords: Kinesin

Microtubule length control is essential for the assembly and function of mitotic spindle. Kinesin-like motor proteins that directly attenuate microtubule dynamics make key contributions to this control, but specificity these motors different subpopulations spindle microtubules not understood. Kif18A (kinesin-8) localizes plus ends relatively slowly growing kinetochore fibers (K-fibers) attenuates their dynamics, whereas Kif4A (kinesin-4) chromatin suppresses growth highly dynamic, nonkinetochore microtubules. Although similarly suppress in vitro, it remains unclear whether microtubule-attenuating lengths K-fibers through a common mechanism. To address question, we engineered chimeric kinesins contain Kif4A, Kif18B (kinesin-8), or Kif5B (kinesin-1) domain fused C-terminal tail Kif18A. Each K-fibers; however, K-fiber requires an activity specific kinesin-8s. Mutational studies indicate depends on both its C-terminus unique, positively charged surface loop, called loop2, within domain. These data support model which are molecularly "tuned" subsets