Converter domain mutations in myosin alter structural kinetics and motor function
| Autor: | Joseph M. Muretta, Laura K. Gunther, Wanjian Tang, Shane D. Walton, Darshan V. Trivedi, William C. Unrath, John A. Rohde, David D. Thomas, Christopher M. Yengo |
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| Rok vydání: | 2018 |
| Předmět: |
0301 basic medicine
Models Molecular Protein Conformation ATPase Population Myosin Type V Sequence Homology Motor Activity medicine.disease_cause Biochemistry Mechanotransduction Cellular Motor protein 03 medical and health sciences Adenosine Triphosphate Protein Domains ATP hydrolysis Myosin medicine Molecular motor Animals Amino Acid Sequence education Molecular Biology Actin Adenosine Triphosphatases Mutation education.field_of_study 030102 biochemistry & molecular biology biology Chemistry Cell Biology Adenosine Diphosphate 030104 developmental biology biology.protein Biophysics Enzymology Chickens Protein Binding |
| Zdroj: | The Journal of biological chemistry. 294(5) |
| ISSN: | 1083-351X |
| Popis: | Myosins are molecular motors that use a conserved ATPase cycle to generate force. We investigated two mutations in the converter domain of myosin V (R712G and F750L) to examine how altering specific structural transitions in the motor ATPase cycle can impair myosin mechanochemistry. The corresponding mutations in the human β-cardiac myosin gene are associated with hypertrophic and dilated cardiomyopathy, respectively. Despite similar steady-state actin-activated ATPase and unloaded in vitro motility-sliding velocities, both R712G and F750L were less able to overcome frictional loads measured in the loaded motility assay. Transient kinetic analysis and stopped-flow FRET demonstrated that the R712G mutation slowed the maximum ATP hydrolysis and recovery-stroke rate constants, whereas the F750L mutation enhanced these steps. In both mutants, the fast and slow power-stroke as well as actin-activated phosphate release rate constants were not significantly different from WT. Time-resolved FRET experiments revealed that R712G and F750L populate the pre- and post-power-stroke states with similar FRET distance and distance distribution profiles. The R712G mutant increased the mole fraction in the post-power-stroke conformation in the strong actin-binding states, whereas the F750L decreased this population in the actomyosin ADP state. We conclude that mutations in key allosteric pathways can shift the equilibrium and/or alter the activation energy associated with key structural transitions without altering the overall conformation of the pre- and post-power-stroke states. Thus, therapies designed to alter the transition between structural states may be able to rescue the impaired motor function induced by disease mutations. |
| Databáze: | OpenAIRE |
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