1: Nat Struct Biol  2002 May 13; [epub ahead of print] 

Myosin V is a left-handed spiral motor on the right-handed actin helix.

Ali MY, Uemura S, Adachi K, Itoh H, Kinosita K, Ishiwata S.

[1] Center for Integrative Bioscience, Okazaki National Research Institutes,
Higashiyama 5-1, Myodaiji, Okazaki 444-8585, Japan. [2] CREST (Core Research for
Evolutional Science and Technology), 'Genetic Programming' Team 13, Nogawa 907,
Miyamae-ku, Kawasaki 216-0001, Japan. [3] Department of Physics, Faculty of
Science and Technology, Keio University, Hiyoshi 3-14-1, Kohoku-ku, Yokohama
223-8522, Japan.

Myosin V is a two-headed, actin-based molecular motor implicated in organelle
transport. Previously, a single myosin V molecule has been shown to move
processively along an actin filament in discrete approximately 36 nm steps.
However, 36nm is the helical repeat length of actin, and the geometry of the
previous experiments may have forced the heads to bind to, or halt at, sites on
one side of actin that are separated by 36 nm. To observe unconstrained motion,
we suspended an actin filament in solution and attached a single myosin V
molecule carrying a bead duplex. The duplex moved as a left-handed spiral around
the filament, disregarding the right-handed actin helix. Our results indicate a
stepwise walking mechanism in which myosin V positions and orients the unbound
head such that the head will land at the 11(th) or 13(th) actin subunit on the
opposing strand of the actin double helix.

PMID: 12006986 [PubMed - as supplied by publisher]