The diffusive search mechanism of processive myosin class-V motor involves directional steps along actin subunits.
It is widely accepted that the vesicle-transporter myosin-V moves processively along F-actin with large steps of approximately 36 nm using a hand-over-hand mechanism. A key question is how does the rear head of two-headed myosin-V search for the forward actin target in the forward direction. Scanning probe nanometry was used to resolve this underlying search process, which was made possible by attaching the head to a relatively large probe. One-headed myosin-V undergoes directional diffusion with approximately 5.5 nm substeps to develop an average displacement of approximately 20 nm, which was independent of the neck length (2IQ and 6IQ motifs). Two-headed myosin-V showed several approximately 5.5 nm substeps within each processive approximately 36 nm step. These results suggest that the myosin-V head searches in the forward direction for the actin target using directional diffusion on the actin subunits according to a potential slope created along the actin helix.
Okada
Takuya
T
Formation of Soft Nano-Machines, CREST JST, 1-3, Yamadaoka, Suita, Osaka 565-0871, Japan.
Tanaka
Hiroto
H
Iwane
Atsuko Hikikoshi
AH
Kitamura
Kazuo
K
Ikebe
Mitsuo
M
Yanagida
Toshio
T
D000199:Actins / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D006801:Humans; D020527:Microscopy, Scanning Probe; D018995:Myosin Heavy Chains / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D024701:Myosin Type V / Q000737:chemistry / Q000145:classification* / Q000502:physiology*; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D018411:Spodoptera
D000199:Actins; D021122:Protein Subunits; D024701:Myosin Type V; D018995:Myosin Heavy Chains