The prepower stroke conformation of myosin V.
We have used electron microscopy and single-particle image processing to study head conformation in myosin V molecules. We find that in the presence of ATP, many heads have a sharply angled conformation that is rare in its absence. The sharply angled conformation is similar to a myosin II atomic structure proposed to mimic the prepower stroke state. The leading head in molecules attached to actin by both heads has a similar conformation, but is also sharply angled in a second plane by tethering through the trail head. The lead head lever joins the motor domain approximately 5 nm axially from where it joins the trail motor. These positions locate the converter subdomain and show the lead motor is in the prepower stroke conformation. Tethering by the trail head places the lead head motor domain at the correct axial position along the actin for binding, but at the wrong orientation. Attachment is achieved either by bending the lead head lever throughout its length or at the pliant point. The microscopy shows that most of the walking stride is produced by changes in lever angle brought about by converter movement, but is augmented by distortion produced by thermal energy.
Burgess
Stan
S
Astbury Centre for Structural Molecular Biology and School of Biomedical Sciences, University of Leeds, Leeds, UK.
Walker
Matt
M
Wang
Fei
F
Sellers
James R
JR
White
Howard D
HD
Knight
Peter J
PJ
Trinick
John
J
D000199:Actins / Q000737:chemistry; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D018360:Crystallography, X-Ray; D006358:Hot Temperature; D006868:Hydrolysis; D007313:Insecta; D051379:Mice; D008854:Microscopy, Electron; D008958:Models, Molecular; D024462:Myosin Type II / Q000737:chemistry; D024701:Myosin Type V / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary
D000199:Actins; D000255:Adenosine Triphosphate; D024462:Myosin Type II; D024701:Myosin Type V