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Proc Natl Acad Sci U S A. 2009 Apr 28;106(17):6992-7. doi: 10.1073/pnas.0812620106. Epub 2009 Apr 14.

Single molecule mechanics of the kinesin neck.

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  • 1Physics Department E22, Technische Universität München, James Franck Strasse, 85748 Garching, Germany.

Abstract

Structural integrity as well as mechanical stability of the parts of a molecular motor are crucial for its function. In this study, we used high-resolution force spectroscopy by atomic force microscopy to investigate the force-dependent opening kinetics of the neck coiled coil of Kinesin-1 from Drosophila melanogaster. We find that even though the overall thermodynamic stability of the neck is low, the average opening force of the coiled coil is >11 pN when stretched with pulling velocities >150 nm/s. These high unzipping forces ensure structural integrity during motor motion. The high mechanical stability is achieved through a very narrow N-terminal unfolding barrier if compared with a conventional leucine zipper. The experimentally mapped mechanical unzipping profile allows direct assignment of distinct mechanical stabilities to the different coiled-coil subunits. The coiled-coil sequence seems to be tuned in an optimal way to ensure both mechanical stability as well as motor regulation through charged residues.

PMID:
19369199
[PubMed - indexed for MEDLINE]
PMCID:
PMC2678465
Free PMC Article
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