Blebbistatin induces lever priming in myosin.ADP complexes, revealing a previously inaccessible conformation that resembles the start of the working stroke.
Hypothesis-generating for myosin-targeted cardiac therapies; extends in vitro powerstroke models but leaves in vivo relevance open.
The powerstroke of the myosin motor is the basis of cell division and bodily movement, but has eluded empirical description due to the short lifetime and low abundance of intermediates during force generation. To gain insight into this process, we used well-established single-tryptophan and pyrene fluorescent sensors and electron microscopy to characterize the structural and kinetic properties of myosin complexed with ADP and blebbistatin, a widely used inhibitor. We found that blebbistatin does not weaken the tight actin binding of myosin.ADP, but unexpectedly it induces lever priming, a process for which the gamma-phosphate of ATP (or its analog) had been thought necessary. The results indicate that a significant fraction of the myosin.ADP.blebbistatin complex populates a previously inaccessible conformation of myosin resembling the start of the powerstroke.
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Takács et al. (2010) studied this question.
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