Unconstrained steps of myosin VI appear longest among known molecular motors

M. Yusuf Ali, Kazuaki Homma, Atsuko Hikikoshi Iwane, Kengo Adachi, Hiroyasu Itoh, Kazuhiko Kinosita*, Toshio Yanagida, Mitsuo Ikebe

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

44 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)3804-3810
Number of pages7
JournalBiophysical Journal
Volume86
Issue number6
DOIs
StatePublished - Jun 2004

ASJC Scopus subject areas

  • Biophysics

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