The EMBO Journal (2010) 29, 3437 - 3447
doi:10.1038/emboj.2010.220
Published online: 3 September 2010
Insight into the molecular mechanism of the multitasking kinesin-8 motor
Carsten Peters1,3, Katjuša Brejc2,3,4,5, Lisa Belmont2, Andrew J Bodey1, Yan Lee2, Ming Yu2, Jun Guo2, Roman Sakowicz2, James Hartman2 and Carolyn A Moores1
Institute of Structural and Molecular Biology, Birkbeck College, London, UK
Cytokinetics, San Francisco, CA, USA
Correspondence to:
Carolyn A Moores, Institute of Structural and Molecular Biology, Birkbeck College, Malet Street, London WC1E 7HX, UK. Tel.: +44 207 631 6858; Fax: +44 207 631 6803; E-mail: c.moores@mail.cryst.bbk.ac.uk
3These authors contributed equally to this work
4Present address: Howard Hughes Medical Institute, University of California, Berkeley, CA 94720, USA
5Present address: Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
Received 8 March 2010; Accepted 17 August 2010
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Members of the kinesin-8 motor class have the remarkable ability to both walk towards microtubule plus-ends and depolymerise these ends on arrival, thereby regulating microtubule length. To analyse how kinesin-8 multitasks, we studied the structure and function of the kinesin-8 motor domain. We determined the first crystal structure of a kinesin-8 and used cryo-electron microscopy to calculate the structure of the microtubule-bound motor. Microtubule-bound kinesin-8 reveals a new conformation compared with the crystal structure, including a bent conformation of the α4 relay helix and ordering of functionally important loops. The kinesin-8 motor domain does not depolymerise stabilised microtubules with ATP but does form tubulin rings in the presence of a non-hydrolysable ATP analogue. This shows that, by collaborating, kinesin-8 motor domain molecules can release tubulin from microtubules, and that they have a similar mechanical effect on microtubule ends as kinesin-13, which enables depolymerisation. Our data reveal aspects of the molecular mechanism of kinesin-8 motors that contribute to their unique dual motile and depolymerising functions, which are adapted to control microtubule length.
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Keywords: cryo-electron microscopy, crystallography, cytoskeleton regulation, kinesin, microtubule
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NOTA DESTE BLOGGER:
Apesar de Massimo Pigliucci ter sugerido recentemente um INDEX PROHIBITORUM para os cientistas evitarem utilizar linguagem descrevendo eventos biológicos em termos teleológicos (engenharia), esses aqui não puderam resistir e dizer outra coisa: existem sim sinais de inteligência e design, e eles são empiricamente detectados na natureza.
E os cientistas? Bem, os cientistas seguem as evidências aonde elas forem dar...
E os cientistas? Bem, os cientistas seguem as evidências aonde elas forem dar...
