Nucleotide Pocket Thermodynamics Measured by EPR Reveal How Energy Partitioning Relates Myosin Speed to Efficiency
| Autor: | Christopher L. Berger, Alexander R. Dunn, Edward Pate, Thomas J. Purcell, James A. Spudich, András Málnási-Csizmadia, Kathy Franks-Skiba, Catherine C. Eldred, Nariman Naber, Roger Cooke, Douglas M. Swank |
|---|---|
| Rok vydání: | 2011 |
| Předmět: |
Protein Conformation
Swine macromolecular substances Plasma protein binding Myosins Closed conformation Models Biological Article law.invention 03 medical and health sciences 0302 clinical medicine Protein structure Structural Biology law Myosin Animals Energy partitioning Dictyostelium Nucleotide Muscle Skeletal Electron paramagnetic resonance Molecular Biology Actin 030304 developmental biology chemistry.chemical_classification 0303 health sciences Nucleotides Chemistry Electron Spin Resonance Spectroscopy Actomyosin Actins Adenosine Diphosphate Crystallography Thermodynamics Spin Labels Rabbits Chickens 030217 neurology & neurosurgery Protein Binding |
| Zdroj: | Journal of Molecular Biology. 407:79-91 |
| ISSN: | 0022-2836 |
| DOI: | 10.1016/j.jmb.2010.11.053 |
| Popis: | We have used spin-labeled ADP to investigate the dynamics of the nucleotide-binding pocket in a series of myosins, which have a range of velocities. Electron paramagnetic resonance spectroscopy reveals that the pocket is in equilibrium between open and closed conformations. In the absence of actin, the closed conformation is favored. When myosin binds actin, the open conformation becomes more favored, facilitating nucleotide release. We found that faster myosins favor a more closed pocket in the actomyosin•ADP state, with smaller values of ΔH(0) and ΔS(0), even though these myosins release ADP at a faster rate. A model involving a partitioning of free energy between work-generating steps prior to rate-limiting ADP release explains both the unexpected correlation between velocity and opening of the pocket and the observation that fast myosins are less efficient than slow myosins. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect