Myosin V stepping mechanism.
We observe the myosin V stepping mechanism by traveling wave tracking. This technique, associated with optical tweezers, allows one to follow a scattering particle in a two-dimensional plane, with nanometer accuracy and a temporal resolution in the microsecond range. We have observed that, at the millisecond time scale, the myosin V combines longitudinal and vertical motions during the step. Because at this time scale the steps appear heterogeneous, we deduce their general features by aligning and averaging a large number of them. Our data show that the 36-nm step occurs in three main stages. First, the myosin center of mass moves forward 5 nm; the duration of this short prestep depends on the ATP concentration. Second, the motor performs a fast motion over 23 nm; this motion is associated to a vertical movement of the myosin center of mass, whose distance from the actin filament increases by 6 nm. Third, the myosin head freely diffuses toward the next binding site and the vertical position is recovered. We propose a simple model to describe the step mechanism of the dimeric myosin V.
Cappello
Giovanni
G
Institut Curie, Centre National de la Recherche Scientifique Unité Mixte de Recherche 168, 75231 Paris, France. giovanni.cappello@curie.fr
Pierobon
Paolo
P
Symonds
Clémentine
C
Busoni
Lorenzo
L
Gebhardt
J Christof M
JC
Rief
Matthias
M
Prost
Jacques
J
D000199:Actins / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D002645:Chickens; D019281:Dimerization; D016547:Kinesins / Q000737:chemistry; D008958:Models, Molecular; D015233:Models, Statistical; D018482:Muscle, Skeletal / Q000378:metabolism; D024701:Myosin Type V / Q000737:chemistry*; D009218:Myosins / Q000737:chemistry; D011137:Polystyrenes / Q000737:chemistry; D011817:Rabbits; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics
D000199:Actins; D011137:Polystyrenes; D024701:Myosin Type V; D009218:Myosins; D016547:Kinesins