Nanometer localization of single green fluorescent proteins: evidence that myosin V walks hand-over-hand via telemark configuration.
Myosin V is a homodimeric motor protein involved in trafficking of vesicles in the cell. It walks bipedally along actin filaments, moving cargo approximately 37 nm per step. We have measured the step size of individual myosin heads by fusing an enhanced green fluorescent protein (eGFP) to the N-terminus of one head of the myosin dimer and following the motion with nanometer precision and subsecond resolution. We find the average step size to be 74.1 nm with 9.4 nm (SD) and 0.3 nm (SE). Our measurements demonstrate nanometer localization of single eGFPs, confirm the hand-over-hand model of myosin V procession, and when combined with previous data, suggest that there is a kink in the leading lever arm in the waiting state of myosin V. This kink, or "telemark skier" configuration, may cause strain, which, when released, leads to the powerstroke of myosin, throwing the rear head forward and leading to unidirectional motion.
Snyder
Gregory E
GE
Physics Department and Center for Biophysics and Computational Biology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA.
Sakamoto
Takeshi
T
Hammer
John A
JA
Sellers
James R
JR
Selvin
Paul R
PR
D000255:Adenosine Triphosphate / Q000737:chemistry; D000818:Animals; D055592:Biophysical Phenomena; D001703:Biophysics; D002465:Cell Movement; D019281:Dimerization; D049452:Green Fluorescent Proteins / Q000737:chemistry* / Q000378:metabolism; D051379:Mice; D008856:Microscopy, Fluorescence / Q000295:instrumentation* / Q000379:methods; D008954:Models, Biological; D024701:Myosin Type V / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D016011:Normal Distribution; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D012984:Software; D013997:Time Factors
D049452:Green Fluorescent Proteins; D000255:Adenosine Triphosphate; D024701:Myosin Type V