Kinetic and mechanistic basis of the nonprocessive Kinesin-3 motor NcKin3

Adio, Sarah and Bloemink, Marieke J. and Hartel, Michaela and Leier, Sven and Geeves, Michael A. and Woehlke, Gunther (2006) Kinetic and mechanistic basis of the nonprocessive Kinesin-3 motor NcKin3. Journal of Biological Chemistry, 281 (49). pp. 37782-93. ISSN 0021-9258. (The full text of this publication is not available from this repository)

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Kinesin-3 motors have been shown to transport cellular cargo along microtubules and to function according to mechanisms that differ from the conventional hand-over-hand mechanism. To find out whether the mechanisms described for Kif1A and CeUnc104 cover the full spectrum of Kinesin-3 motors, we characterize here NcKin3, a novel member of the Kinesin-3 family that localizes to mitochondria of ascomycetes. We show that NcKin3 does not move in a K-loop-dependent way as Kif1A or in a cluster-dependent way as CeUnc104. Its in vitro gliding velocity ranges between 0.30 and 0.64 mum/s and correlates positively with motor density. The processivity index (k(bi,ratio)) of approximately 3 reveals that not more than three ATP molecules are hydrolyzed per productive microtubule encounter. The NcKin3 duty ratio of 0.03 indicates that the motor spends only a minute fraction of the ATPase cycle attached to the filament. Unlike other Kinesin-3 family members, NcKin3 forms stable dimers, but only one subunit releases ADP in a microtubule-dependent fashion. Together, these data exclude a processive hand-over-hand mechanism of movement and suggest a power-stroke mechanism where nucleotide-dependent structural changes in a single motor domain lead to displacement of the motor along the filament. Thus, NcKin3 is the first plus end-directed kinesin motor that is dimeric but moves in a nonprocessive fashion to its destination.

Item Type: Article
Additional information: 0021-9258 (Print) Journal Article Research Support, Non-U.S. Gov't
Uncontrolled keywords: Adenosine Triphosphate/metabolism Amino Acid Sequence Dimerization Fungal Proteins/chemistry/genetics/*metabolism Kinesin/chemistry/genetics/*metabolism Microtubules/metabolism Models, Biological Molecular Motor Proteins/chemistry/genetics/*metabolism Molecular Sequence Data Neurospora crassa/genetics/metabolism Protein Structure, Quaternary Protein Structure, Tertiary Recombinant Proteins/chemistry/genetics/metabolism Sequence Homology, Amino Acid
Subjects: Q Science
Divisions: Faculties > Science Technology and Medical Studies > School of Biosciences
Depositing User: Michael Geeves
Date Deposited: 16 Mar 2009 16:15
Last Modified: 29 Apr 2014 08:13
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