The gated gait of the processive molecular motor, myosin V.
Class V myosins are actin-based molecular motors involved in vesicular and organellar transport. Single myosin V molecules move processively along F-actin, taking several 36-nm steps for each diffusional encounter. Here we have measured the mechanical interactions between mouse brain myosin V and rabbit skeletal F-actin. The working stroke produced by a myosin V head is approximately 25 nm, consisting of two separate mechanical phases (20 + 5 nm). We show that there are preferred myosin binding positions (target zones) every 36 nm along the actin filament, and propose that the 36-nm steps of the double-headed motor are a combination of the working stroke (25 nm) of the bound head and a biased, thermally driven diffusive movement (11 nm) of the free head onto the next target zone. The second phase of the working stroke (5 nm) acts as a gate - like an escapement in a clock, coordinating the ATPase cycles of the two myosin V heads. This mechanism increases processivity and enables a single myosin V molecule to travel distances of several hundred nanometres along the actin filament.
Veigel
Claudia
C
Department of Biology, University of York, PO Box 373, York YO10 5YW, UK. cv1@york.ac.uk
Wang
Fei
F
Bartoo
Marc L
ML
Sellers
James R
JR
Molloy
Justin E
JE
D000199:Actins / Q000737:chemistry* / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000378:metabolism; D006868:Hydrolysis; D051379:Mice; D008958:Models, Molecular; D020409:Molecular Motor Proteins; D018482:Muscle, Skeletal / Q000378:metabolism; D024701:Myosin Type V / Q000737:chemistry* / Q000378:metabolism; D011817:Rabbits; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism
D000199:Actins; D020409:Molecular Motor Proteins; D011994:Recombinant Proteins; D000255:Adenosine Triphosphate; D024701:Myosin Type V