Nucleotide-dependent single- to double-headed binding of kinesin |
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Authors: | Kawaguchi K Ishiwata S |
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Institution: | Department of Physics, School of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan. |
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Abstract: | The motility of kinesin motors is explained by a "hand-over-hand" model in which two heads of kinesin alternately repeat single-headed and double-headed binding with a microtubule. To investigate the binding mode of kinesin at the key nucleotide states during adenosine 5'-triphosphate (ATP) hydrolysis, we measured the mechanical properties of a single kinesin-microtubule complex by applying an external load with optical tweezers. Both the unbinding force and the elastic modulus in solutions containing AMP-PNP (an ATP analog) were twice the value of those in nucleotide-free solution or in the presence of both AMP-PNP and adenosine 5'-diphosphate. Thus, kinesin binds through two heads in the former and one head in the latter two states, which supports a major prediction of the hand-over-hand model. |
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