期刊
CELLULAR AND MOLECULAR LIFE SCIENCES
卷 69, 期 2, 页码 299-311出版社
SPRINGER BASEL AG
DOI: 10.1007/s00018-011-0749-8
关键词
Actin; Myosin; Transient kinetics; ATPase; Mangnesium ions
资金
- Deutsche Forschungsgemeinschaft [Ma 1081/16-1]
- Cluster of Excellence Rebirth
Myosin-7a participates in auditory and visual processes. Defects in MYO7A, the gene encoding the myosin-7a heavy chain, are causative for Usher syndrome 1B, the most frequent cause of deaf-blindness in humans. In the present study, we performed a detailed kinetic and functional characterization of the isolated human myosin-7a motor domain to elucidate the details of chemomechanical coupling and the regulation of motor function. A rate-limiting, slow ADP release step causes long lifetimes of strong actin-binding intermediates and results in a high duty ratio. Moreover, our results reveal a Mg2+-sensitive regulatory mechanism tuning the kinetic and mechanical properties of the myosin-7a motor domain. We obtained direct evidence that changes in the concentration of free Mg2+ ions affect the motor properties of human myosin-7a using an in vitro motility assay system. Our results suggest that in a cellular environment, compartment-specific fluctuations in free Mg2+ ions can mediate the conditional switching of myosin-7a between cargo moving and tension bearing modes.
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