Unconstrained steps of myosin VI appear longest among known molecular motors
Biochemistry & Molecular Pharmacology
Graduate School of Biomedical Sciences; Department of Physiology
Medical Subject Headings
Actins; Animals; Kinesin; Molecular Motor Proteins; Movement; Myosin Heavy Chains; Myosin Type V; Protein Binding; Rotation
Life Sciences | Medicine and Health Sciences
Myosin VI is a two-headed molecular motor that moves along an actin filament in the direction opposite to most other myosins. Previously, a single myosin VI molecule has been shown to proceed with steps that are large compared to its neck size: either it walks by somehow extending its neck or one head slides along actin for a long distance before the other head lands. To inquire into these and other possible mechanism of motility, we suspended an actin filament between two plastic beads, and let a single myosin VI molecule carrying a bead duplex move along the actin. This configuration, unlike previous studies, allows unconstrained rotation of myosin VI around the right-handed double helix of actin. Myosin VI moved almost straight or as a right-handed spiral with a pitch of several micrometers, indicating that the molecule walks with strides slightly longer than the actin helical repeat of 36 nm. The large steps without much rotation suggest kinesin-type walking with extended and flexible necks, but how to move forward with flexible necks, even under a backward load, is not clear. As an answer, we propose that a conformational change in the lifted head would facilitate landing on a forward, rather than backward, site. This mechanism may underlie stepping of all two-headed molecular motors including kinesin and myosin V.
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Citation: Biophys J. 2004 Jun;86(6):3804-10. Link to article on publisher's site
Ali, M. Yusuf; Homma, Kazuaki; Iwane, Atsuko Hikikoshi; Adachi, Kengo; Itoh, Hiroyasu; Kinosita, Kazuhiko; Yanagida, Toshio; and Ikebe, Mitsuo, "Unconstrained steps of myosin VI appear longest among known molecular motors" (2004). GSBS Student Publications. 43.