Myosin-V makes two brownian 90 degrees rotations per 36-nm step.
Myosin-V processively walks on actin filaments in a hand-over-hand fashion. The identical structures of the heads predict a symmetric hand-over-hand mechanism where regular, unidirectional rotation occurs during a 36-nm step. We investigated this by observing how fixed myosin-V rotates actin filaments. Actin filaments randomly rotated 90 degrees both clockwise and counter-clockwise during each step. Furthermore, ATP-dependent rotations were regularly followed by ATP-independent ones. Kinetic analysis indicated that the two 90 degrees rotations relate to the coordinated unbinding and rebinding of the heads with actin. We propose a 'brownian rotation hand-over-hand' model, in which myosin-V randomly rotates by thermally twisting its elastic neck domains during the 36-nm step. The brownian rotation may be advantageous for cargo transport through a crowded actin meshwork and for carrying cargoes reliably via multiple myosin-V molecules in the cell.
Komori
Yasunori
Y
Laboratories for Nanobiology, Graduate School of Frontier Biosciences, Osaka University, 1-3, Yamadaoka, Suita, Osaka, 565-0871, Japan.
Iwane
Atsuko H
AH
Yanagida
Toshio
T
D000199:Actins / Q000378:metabolism / Q000648:ultrastructure; D000255:Adenosine Triphosphate / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D020409:Molecular Motor Proteins / Q000378:metabolism / Q000648:ultrastructure; D024701:Myosin Type V / Q000378:metabolism / Q000648:ultrastructure; D011485:Protein Binding; D012399:Rotation
D000199:Actins; D020409:Molecular Motor Proteins; D000255:Adenosine Triphosphate; D024701:Myosin Type V