Why the study?
The degree to which oxidation of actin versus myosin contributes to attenuated force in myofibrils was unclear.
Oxidation of both actin and myosin contributes to decreased contractile force and velocity in skeletal muscle, providing a mechanistic basis for myofibrillar weakness.
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Oxidative attenuation of myofibrillar force may occur in disease; leaves open relative actin versus myosin contributions and clinical relevance.
The interaction between actin and myosin is the basis of contraction and force production in muscle fibers. Studies have shown that actin and myosin oxidation cause myofibrillar weakness in healthy and diseased muscles. The degree to which oxidation of each of these proteins contributes to an attenuated force in myofibrils is unclear. In this study, we show that exposure of actin and myosin to the chemical 5-amino-3-(4-morpholinyl)-1,2,3-oxadiazolium chloride (SIN-1), an NO and O 2 •− donor, affected actin-myosin interactions, as shown by a decreased myosin-propelled actin velocity in the in vitro motility assay. We also observed that oxidation of actin and myosin resulted in a decrease in force generated by myosin and actin filaments, as determined by a system of microfabricated cantilevers. Although myosin is more sensitive to oxidative modifications than actin, as indicated by a steeper decrease in velocity and force by the filaments, modifications on actin are sufficient to affect force and velocity and also contribute to a decrease in contractile activity in muscles.
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Elkrief et al. (2022) studied this question.
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