Unconstrained steps of myosin VI appear longest among known molecular motors
Graduate School of Biomedical Sciences; Department of Physiology
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.
DOI of Published Version
Biophys J. 2004 Jun;86(6):3804-10. Link to article on publisher's site
Ali MY, Homma K, Iwane AH, Adachi K, Itoh H, Kinosita K, Yanagida T, Ikebe M. (2004). Unconstrained steps of myosin VI appear longest among known molecular motors. Morningside Graduate School of Biomedical Sciences Student Publications. https://doi.org/10.1529/biophysj.103.037416. Retrieved from https://escholarship.umassmed.edu/gsbs_sp/43