Low temperature traps myosin motors of mammalian muscle in a refractory state that prevents activation

• DOI: 10.1085/jgp.201912424
• Publication Date: 2019-09-25T18:55:17Z
• Authors: Marco Caremani; Elisabetta Brunello; Marco Linari; Luca Fusi; Thomas C. Irving; David Gore; Gabriella Piazzesi; Malcolm Irving; Vincenzo Lombardi; Massimo Reconditi
• Keywords: Molecular motor

Myosin motors in the thick filament of resting striated (skeletal and cardiac) muscle are trapped an OFF state, which packed helical tracks on surface, inhibiting their interactions with actin utilization ATP. To investigate structural changes induced mammalian skeletal by temperature, we collected x-ray diffraction patterns from fast extensor digitorum longus mouse temperature range near physiological (35°C) to 10°C, maximal isometric force (T0) shows a threefold decrease. In muscle, reflections signaling state indicate that cooling produces progressive disruption moving away ordered surface filament. We find number myosin at 10°C is half 35°C. At T0, signals report fraction conformation actin-attached can be explained if decrease associated lowering due not only force-generating transition but also twofold such motors. Thus, reduces same extent rest attached suggesting leave accumulate disordered refractory makes them unavailable for interaction upon stimulation. This regulatory effect could represent energetically convenient mechanism hibernating animals.