Abstract
A principal goal of molecular biophysics is to show how protein structural transitions explain physiology. We have developed a strategic tool, transient time-resolved FRET [(TR)2 FRET], for this purpose and use it here to measure directly, with millisecond resolution, the structural and biochemical kinetics of muscle myosin and to determine directly how myosin's power stroke is coupled to the thermodynamic drive for force generation, actin-activated phosphate release, and the weak-to-strong actin-binding transition. We find that actin initiates the power stroke before phosphate dissociation and not after, as many models propose. This result supports a model for muscle contraction in which power output and efficiency are tuned by the distribution of myosin structural states. This technology should have wide application to other systems in which questions about the temporal coupling of allosteric structural and biochemical transitions remain unanswered.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 14272-14277 |
| Number of pages | 6 |
| Journal | Proceedings of the National Academy of Sciences of the United States of America |
| Volume | 112 |
| Issue number | 46 |
| DOIs | |
| State | Published - Nov 17 2015 |
Bibliographical note
Funding Information:ACKNOWLEDGMENTS. This study was supported by NIH Grant AR32961 (to D.D.T.), American Heart Association Grant 14SDG20480032 (to J.M.M.), and NIH Grant 5 P30 AR05722), and by the Paul and Sheila Wellstone Foundation. J.A.R. was supported by the Graduate Excellence Fellowship from the University of Minnesota.
Funding Information:
This study was supported by NIH Grant AR32961 (to D.D.T.), American Heart Association Grant 14SDG20480032 (to J.M.M.), and NIH Grant 5 P30 AR05722), and by the Paul and Sheila Wellstone Foundation. J.A.R. was supported by the Graduate Excellence Fellowship from the University of Minnesota.
Keywords
- FRET
- Myosin
- Power stroke|phosphate release
- Structural kinetics
