Myosin-V stepping kinetics: a molecular model for processivity.
Myosin-V is a molecular motor that moves processively along its actin track. We have used a feedback-enhanced optical trap to examine the stepping kinetics of this movement. By analyzing the distribution of time periods separating discrete approximately 36-nm mechanical steps, we characterize the number and duration of rate-limiting biochemical transitions preceding each such step. These data show that myosin-V is a tightly coupled motor whose cycle time is limited by ADP release. On the basis of these results, we propose a model for myosin-V processivity.
Rief
M
M
Department of Biochemistry, Stanford University Medical Center, CA 94305, USA.
Rock
R S
RS
Mehta
A D
AD
Mooseker
M S
MS
Cheney
R E
RE
Spudich
J A
JA
D000199:Actins / Q000378:metabolism; D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001921:Brain; D002148:Calmodulin-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D002645:Chickens; D005246:Feedback; D007700:Kinetics; D007834:Lasers; D008863:Microspheres; D008954:Models, Biological; D020409:Molecular Motor Proteins / Q000737:chemistry* / Q000378:metabolism*; D009068:Movement; D024701:Myosin Type V; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000378:metabolism*
D000199:Actins; D002148:Calmodulin-Binding Proteins; D020409:Molecular Motor Proteins; D009419:Nerve Tissue Proteins; C078829:chicken brain myosin-V p190; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D024701:Myosin Type V