Kinesin-microtubule binding depends on both nucleotide state and loading direction.
Kinesin is a motor protein that transports organelles along a microtubule toward its plus end by using the energy of ATP hydrolysis. To clarify the nucleotide-dependent binding mode, we measured the unbinding force for one-headed kinesin heterodimers in addition to conventional two-headed kinesin homodimers under several nucleotide states. We found that both a weak and a strong binding state exist in each head of kinesin corresponding to a small and a large unbinding force, respectively; that is, weak for the ADP state and strong for the nucleotide-free and adenosine 5'-[beta,gamma-imido]triphosphate states. Model analysis showed that (i) the two binding modes in each head could be explained by a difference in the binding energy and (ii) the directional instability of binding, i.e., dependence of unbinding force on loading direction, could be explained by a difference in the characteristic distance for the kinesin-microtubule interaction during plus- and minus-end-directed loading. Both these factors must play an important role in the molecular mechanism of kinesin motility.
Uemura
Sotaro
S
Department of Physics, School of Science and Engineering, and Advanced Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan.
Kawaguchi
Kenji
K
Yajima
Junichiro
J
Edamatsu
Masaki
M
Toyoshima
Yoko Yano
YY
Ishiwata
Shin'ichi
S
D000244:Adenosine Diphosphate / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000378:metabolism; D002417:Cattle; D019281:Dimerization; D016547:Kinesins / Q000737:chemistry*; D008870:Microtubules / Q000378:metabolism*; D008954:Models, Biological; D011485:Protein Binding; D013314:Stress, Mechanical; D013552:Swine; D013696:Temperature; D013997:Time Factors
D000244:Adenosine Diphosphate; D016547:Kinesins