TAILIEUCHUNG - Báo cáo khoa học: Properties of the Kinesin-3 NcKin3 motor domain and implications for neck function

Members of the Kinesin-3 family are microtubule motors involved in the transport of membranous cargo. NcKin3 from the fungus Neuros-pora crassais dimeric but inactivates one of its motor heads to generate nonprocessive motility. | ỊFEBS Journal Properties of the Kinesin-3 NcKin3 motor domain and implications for neck function Sarah Adio1 and Gunther Woehlke2 1 Department of PhysicalBiochemistry Max Planck Institute for BiophysicalChemistry Gottingen Germany 2 Department of Physics E22 TechnicalUniversity Munich Garching Germany Keywords ATPase kinetics kinesin motility mechanism processivity Correspondence S. Adio Department of Physical Biochemistry Max Planck Institute for BiophysicalChemistry Am Fassberg 11 D-37077 Gottingen Germany Fax 49 551 2O12III Tel 49 551 2012934 E-mail G. Woehlke Department of Physics E22 TechnicalUniversity Munich James-Franck-Str. D-85748 Garching Germany Fax 49 89 289 12523 Tel 49 89 289 12486 E-mail . Received 4 February 2009 revised 30 March 2009 accepted 5 May 2009 doi Members of the Kinesin-3 family are microtubule motors involved in the transport of membranous cargo. NcKin3 from the fungus Neuros-pora crassa is dimeric but inactivates one of its motor heads to generate nonprocessive motility. To determine how one of the heads is inactivated we investigated truncated monomeric constructs. None of the constructs generated processive single-molecule motility and multimotor velocities depended linearly on the number of residues remaining in the neck. The kinetic analysis suggests futile ATP hydrolysis cycles because a representative monomer showed a faster ATP turnover than the dimer while supporting slower motility. The MT was 70-fold lower the microtubule-bound portion of the kinetic cycle eight-fold longer and the microtubule detachment rate almost 15-fold slower than that of the dimer. Moreover the monomer s microtubule-dependent ADP release occurred three-fold to four-fold faster than kcat 125 versus 34 s 1 whereas phosphate release was approximately equally fast 29 s 1 . A dimeric construct containing a structure-breaking insert between motor head and neck .

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