Key result
FRET-based sensor reveals a ~70 degree angle change in the myosin light-chain binding region.
Why the study?
Direct dynamic measurements have largely failed to show the large conformational changes of myosin proposed to produce motion coupled to nucleotide state changes.
A novel FRET-based sensor reveals that myosin undergoes a ~70 degree angle change and adopts two distinct prestroke states induced by Mg.ADP.Pi rather than Mg.ATP.
Answers are grounded in this paper and cite their sources.
Identifies distinct myosin prestroke states; extends mechanistic models but leaves open relevance to human cardiac contractility.
The molecular motor myosin is proposed to bind to actin and swing its light-chain binding region through a large angle to produce an approximately 10 nm step in motion coupled to changes in the nucleotide state at the active site. To date, however, direct dynamic measurements have largely failed to show changes of that magnitude. Here, we use a cysteine engineering approach to create a high resolution, FRET-based sensor that reports a large, approximately 70 degree nucleotide-dependent angle change of the light-chain binding region. The combination of steady-state and time-resolved fluorescence resonance energy transfer measurements unexpectedly reveals two distinct prestroke states. The measurements also show that bound Mg.ADP.Pi, and not bound Mg.ATP, induces the myosin to adopt the prestroke states.
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Shih et al. (2000) studied this question. FRET-based sensor was evaluated on Angle change of the light-chain binding region and prestroke states. A FRET-based sensor revealed a ~70 degree nucleotide-dependent angle change of the myosin light-chain binding region and two distinct prestroke states induced by bound Mg.ADP.Pi.
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