Key result
Tension of 2 piconewtons or less decreased the rate of myosin I detachment from actin by >75-fold, transitioning it from a low (<0.2) to a high (>0.9) duty-ratio motor.
Myosin I exhibits impressive tension sensitivity, supporting its role as a molecular force sensor in cellular processes.
Myosin I may act as a cellular force sensor; extends mechanobiology but leaves in vivo roles open.
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.
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Laakso et al. (2008) studied this question. Tension (≤2 piconewtons) vs. Varying tensions was evaluated on Rate of myosin I detachment from actin and duty-ratio (>75-fold decrease). Tension of 2 piconewtons or less decreased the rate of myosin I detachment from actin by >75-fold, transitioning it from a low (<0.2) to a high (>0.9) duty-ratio motor.
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