Myosin I can act as a molecular force sensor.
The ability to sense molecular tension is crucial for a wide array of cellular processes, including the detection of auditory stimuli, control of cell shape, and internalization and transport of membranes. We show that myosin I, a motor protein that has been implicated in powering key steps in these processes, dramatically alters its motile properties in response to tension. We measured the displacement generated by single myosin I molecules, and we determined the actin-attachment kinetics with varying tensions using an optical trap. The rate of myosin I detachment from actin decreases >75-fold under tension of 2 piconewtons or less, resulting in myosin I transitioning from a low (<0.2) to a high (>0.9) duty-ratio motor. This impressive tension sensitivity supports a role for myosin I as a molecular force sensor.
Laakso
Joseph M
JM
Pennsylvania Muscle Institute and Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
Lewis
John H
JH
Shuman
Henry
H
Ostap
E Michael
EM
D000199:Actins / Q000378:metabolism*; D000205:Actomyosin / Q000502:physiology; D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D020816:Amino Acid Motifs; D000818:Animals; D055592:Biophysical Phenomena; D001703:Biophysics; D007700:Kinetics; D016013:Likelihood Functions; D008954:Models, Biological; D020409:Molecular Motor Proteins / Q000378:metabolism / Q000502:physiology*; D009010:Monte Carlo Method; D024461:Myosin Type I / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D052898:Optical Tweezers; D017434:Protein Structure, Tertiary; D011817:Rabbits; D013314:Stress, Mechanical
D000199:Actins; D020409:Molecular Motor Proteins; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000205:Actomyosin; D024461:Myosin Type I