Kinesin-1 is known to inhibit its own activity by binding of its tail to its head, but the mechanism of inhibition has not been certain. A new crystal structure now shows the dimeric motor complexed with its tail, which cross-links the heads to one another. The neck coiled coil also forms a cross-link between the two heads, and the two together are proposed to immobilize the heads by a 'double lockdown' mechanism, representing a novel mechanism of motor autoinhibition. Disulfide bond cross-linking experiments support this proposed mechanism and provide evidence that ADP release is coupled to neck linker undocking.
Kaan, H. Y., Hackney, D. D. & Kozielski, F. 2011. The structure of the kinesin-1 motor-tail complex reveals the mechanism of autoinhibition. Science 333, 883-5.
Kinesin-5 Directional Motility
Tetrameric kinesin-5 motors cross-link spindle microtubules and slide antiparallel microtubules apart, moving towards the microtubule plus end. Analysis of kinesin-5 Cin8 motility at low motor density shows, however, that single motors move towards the microtubule minus end, whereas arrays of Cin8 motors show plus-end motility. The basis of this density-dependent directional motility is attributed to mechanical constraints on the motor ensembles, which are coupled mechanically by binding to the same microtubule.
Roostalu, J., Hentrich, C., Bieling, P., Telley, I. A., Schiebel, E. & Surrey, T. 2007. Directional switching of the kinesin Cin8 through motor coupling. Science 332, 94-9.
The kinesin-8 Kif18A motor accumulates at kinetochore microtubule plus ends and suppresses their dynamics, controlling chromosome movements. Mutants now show that the C-terminal tail is needed for accumulation at plus ends, while the N-terminal motor acts to suppress microtubule growth. A second microtubule-binding domain in the tail may underlie the diffusional movement of the motor along the microtubule. The Kif18A tail thus contributes both to its processivity and accumulation at kinetochore microtubule plus ends.
Stumpff, J., Du, Y., English, C. A. Maliga, Z., Wagenbach, M., Asbury, C. L., Wordeman, L. & Ohi, R. 2011. A tethering mechanism controls the processivity and kinetochore-microtubule plus-end enrichment of the kinesin-8 Kif18AMolec. Cell 43, 764-75.
Kinesin-13 in Centrioles
Studies on centrosomes show that the kinesin-13 Kif24 localizes to mother centrioles and interacts with centrosomal proteins that regulate centriolar length and ciliogenesis. Kif24 disassembles microtubules in vitro and in cells acts specifically on centriolar microtubules to regulate cilia assembly.
Kobayashi, T., Tsang, W. Y., Li, J., Lane, W. & Dynlacht, B. D. 2011. Centriolar kinesin Kif24 interacts with CP110 to remodel microtubules and regulate ciliogenesis.Cell 145, 914-925.
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Copyright 1996-2011. All rights reserved.
Created 20 November 1997 00:55 GMT
Modified 23 September 2011 6:40 GMT