Myosin learns to walk.
Recent experiments, drawing upon single-molecule, solution kinetic and structural techniques, have clarified our mechanistic understanding of class V myosins. The findings of the past two years can be summarized as follows: (1) Myosin V is a highly efficient processive motor, surpassing even conventional kinesin in the distance that individual molecules can traverse. (2) The kinetic scheme underlying ATP turnover resembles those of myosins I and II but with rate constants tuned to favor strong binding to actin. ADP release precedes dissociation from actin and is rate-limiting in the cycle. (3) Myosin V walks in strides averaging approximately 36 nm, the long pitch pseudo-repeat of the actin helix, each step coupled to a single ATP hydrolysis. Such a unitary displacement, the largest molecular step size measured to date, is required for a processive myosin motor to follow a linear trajectory along a helical actin track.
Mehta
A
A
Howard Hughes Medical Institute and Laboratory of Sensory Neuroscience, The Rockefeller University, 1230 York Avenue, New York, NY 10021-6399, USA. mehtaa@rockvax.rockefeller.edu
D000199:Actins / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D000818:Animals; D002148:Calmodulin-Binding Proteins / Q000378:metabolism; D007700:Kinetics; D008954:Models, Biological; D008958:Models, Molecular; D020409:Molecular Motor Proteins / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D024701:Myosin Type V / Q000378:metabolism; D009218:Myosins / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D009419:Nerve Tissue Proteins / Q000378:metabolism; D020836:Protein Structure, Quaternary
D000199:Actins; D002148:Calmodulin-Binding Proteins; D020409:Molecular Motor Proteins; D009419:Nerve Tissue Proteins; C078829:chicken brain myosin-V p190; D024701:Myosin Type V; D009218:Myosins