Single molecule mechanics of the kinesin neck.
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.
Physics Department E22, Technische Universität München, James Franck Strasse, 85748 Garching, Germany.
Thomas
T
Bornschlögl
Günther
G
Woehlke
Matthias
M
Rief
D000595:Amino Acid Sequence; D000818:Animals; D004331:Drosophila melanogaster / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D016547:Kinesins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment
D016547:Kinesins