Orientation dependence of displacements by a single one-headed myosin relative to the actin filament.
Displacements of single one-headed myosin molecules in a sparse myosin-rod cofilament were measured from bead displacements at various angles relative to an actin filament by dual optical trapping nanometry. The sparse myosin-rod cofilaments, 5-8 micron long, were synthesized by slowly mixing one-headed myosin prepared by papain digestion with myosin rods at molar ratios of 1:400 to 1:1500, so that one to four one-headed myosin molecules were on average scattered along the cofilament. The bead displacement was approximately 10 nm at low loads ( approximately 0.5 pN) and at angles of 5-10 degrees between the actin and myosin filaments (near physiologically correct orientation). The bead displacement decreased with an increase in the angle. The bead displacement at nearly 90 degrees was approximately 0 nm. When the angle was increased to approximately 150 degrees-170 degrees, the bead displacements increased to 5 nm. A native two-headed myosin showed similar size and orientation dependence of bead displacements as a one-headed myosin.
Tanaka
H
H
Department of Biophysical Engineering, Faculty of Engineering Science, Osaka University, Toyonaka, Osaka, Japan.
Ishijima
A
A
Honda
M
M
Saito
K
K
Yanagida
T
T
D000199:Actins / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D004591:Electrophoresis, Polyacrylamide Gel; D005033:Ethylmaleimide; D007700:Kinetics; D008958:Models, Molecular; D018482:Muscle, Skeletal; D009218:Myosins / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D010206:Papain; D011487:Protein Conformation; D011817:Rabbits; D013997:Time Factors
D000199:Actins; D000255:Adenosine Triphosphate; D010206:Papain; D009218:Myosins; D005033:Ethylmaleimide