The motor domain determines the large step of myosin-V
Graduate School of Biomedical Sciences; Department of Physiology
Medical Subject Headings
Actins; Adenosine Triphosphate; Animals; Biomechanics; Chickens; Escherichia coli; Models, Biological; Molecular Motor Proteins; Mutation; Myosin Type V; Protein Structure, Tertiary; Recombinant Fusion Proteins; Xenopus
Life Sciences | Medicine and Health Sciences
Class-V myosin proceeds along actin filaments with large ( approximately 36 nm) steps. Myosin-V has two heads, each of which consists of a motor domain and a long (23 nm) neck domain. In accordance with the widely accepted lever-arm model, it was suggested that myosin-V steps to successive (36 nm) target zones along the actin helical repeat by tilting its long neck (lever-arm). To test this hypothesis, we measured the mechanical properties of single molecules of myosin-V truncation mutants with neck domains only one-sixth of the native length. Our results show that the processivity and step distance along actin are both similar to those of full-length myosin-V. Thus, the long neck domain is not essential for either the large steps or processivity of myosin-V. These results challenge the lever-arm model. We propose that the motor domain and/or the actomyosin interface enable myosin-V to produce large processive steps during translocation along actin.
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Citation: Nature. 2002 Jan 10;415(6868):192-5. Link to article on publisher's site
Tanaka, Hiroto; Homma, Kazuaki; Iwane, Atsuko Hikikoshi; Katayama, Eisaku; Ikebe, Reiko; Saito, Junya; Yanagida, Toshio; and Ikebe, Mitsuo, "The motor domain determines the large step of myosin-V" (2002). GSBS Student Publications. 1226.