4etp
C-terminal motor and motor homology domain of Kar3Vik1 fused to a synthetic heterodimeric coiled coilC-terminal motor and motor homology domain of Kar3Vik1 fused to a synthetic heterodimeric coiled coil
Structural highlights
Publication Abstract from PubMedKinesin-14 motors generate microtubule minus-end-directed force used in mitosis and meiosis. These motors are dimeric and operate with a nonprocessive powerstroke mechanism, but the role of the second head in motility has been unclear. In Saccharomyces cerevisiae, the Kinesin-14 Kar3 forms a heterodimer with either Vik1 or Cik1. Vik1 contains a motor homology domain that retains microtubule binding properties but lacks a nucleotide binding site. In this case, both heads are implicated in motility. Here, we show through structural determination of a C-terminal heterodimeric Kar3Vik1, electron microscopy, equilibrium binding, and motility that at the start of the cycle, Kar3Vik1 binds to or occludes two alphabeta-tubulin subunits on adjacent protofilaments. The cycle begins as Vik1 collides with the microtubule followed by Kar3 microtubule association and ADP release, thereby destabilizing the Vik1-microtubule interaction and positioning the motor for the start of the powerstroke. The results indicate that head-head communication is mediated through the adjoining coiled coil. Kar3Vik1, a member of the kinesin-14 superfamily, shows a novel kinesin microtubule binding pattern.,Rank KC, Chen CJ, Cope J, Porche K, Hoenger A, Gilbert SP, Rayment I J Cell Biol. 2012 Jun 25;197(7):957-70. doi: 10.1083/jcb.201201132. PMID:22734002[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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