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

Abstract

Myosin motors in the thick filament of resting striated (skeletal and cardiac) muscle are trapped in an OFF state, in which the motors are packed in helical tracks on the filament surface, inhibiting their interactions with actin and utilization of ATP. To investigate the structural changes induced in the thick filament of mammalian skeletal muscle by changes in temperature, we collected x-ray diffraction patterns from the fast skeletal muscle extensor digitorum longus of the mouse in the temperature range from near physiological (35°C) to 10°C, in which the maximal isometric force ( T 0 ) shows a threefold decrease. In resting muscle, x-ray reflections signaling the OFF state of the thick filament indicate that cooling produces a progressive disruption of the OFF state with motors moving away from the ordered helical tracks on the surface of the thick filament. We find that the number of myosin motors in the OFF state at 10°C is half of that at 35°C. At T 0 , changes in the x-ray signals that report the fraction and conformation of actin-attached motors can be explained if the threefold decrease in force associated with lowering temperature is due not only to a decrease in the force-generatingmore » transition in the actin-attached motors but also to a twofold decrease in the number of such motors. Thus, lowering the temperature reduces to the same extent the fraction of motors in the OFF state at rest and the fraction of motors attached to actin at T 0 , suggesting that motors that leave the OFF state accumulate in a disordered refractory state that makes them unavailable for interaction with actin upon stimulation. This regulatory effect of temperature on the thick filament of mammalian skeletal muscle could represent an energetically convenient mechanism for hibernating animals.« less

Authors:
 [1]; ORCiD logo [1]; ORCiD logo [2];  [3]; ORCiD logo [4];  [4]; ORCiD logo [1];  [3]; ORCiD logo [1]; ORCiD logo [2]
  1. PhysioLab, University of Florence, Florence, Italy
  2. PhysioLab, University of Florence, Florence, Italy, Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, Firenze, Italy
  3. Randall Centre for Cell and Molecular Biophysics, King’s College London, London, UK
  4. Center for Synchrotron Radiation Research and Instrumentation and Department of Biological Sciences, Illinois Institute of Technology, Chicago, IL
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1566274
Grant/Contract Number:  
AC02-06CH11357; RBFR08JAMZ
Resource Type:
Published Article
Journal Name:
Journal of General Physiology
Additional Journal Information:
Journal Name: Journal of General Physiology; Journal ID: ISSN 0022-1295
Publisher:
Rockefeller University Press
Country of Publication:
United States
Language:
English

Citation Formats

Caremani, Marco, Brunello, Elisabetta, Linari, Marco, Fusi, Luca, Irving, Thomas C., Gore, David, Piazzesi, Gabriella, Irving, Malcolm, Lombardi, Vincenzo, and Reconditi, Massimo. Low temperature traps myosin motors of mammalian muscle in a refractory state that prevents activation. United States: N. p., 2019. Web. doi:10.1085/jgp.201912424.
Caremani, Marco, Brunello, Elisabetta, Linari, Marco, Fusi, Luca, Irving, Thomas C., Gore, David, Piazzesi, Gabriella, Irving, Malcolm, Lombardi, Vincenzo, & Reconditi, Massimo. Low temperature traps myosin motors of mammalian muscle in a refractory state that prevents activation. United States. doi:10.1085/jgp.201912424.
Caremani, Marco, Brunello, Elisabetta, Linari, Marco, Fusi, Luca, Irving, Thomas C., Gore, David, Piazzesi, Gabriella, Irving, Malcolm, Lombardi, Vincenzo, and Reconditi, Massimo. Wed . "Low temperature traps myosin motors of mammalian muscle in a refractory state that prevents activation". United States. doi:10.1085/jgp.201912424.
@article{osti_1566274,
title = {Low temperature traps myosin motors of mammalian muscle in a refractory state that prevents activation},
author = {Caremani, Marco and Brunello, Elisabetta and Linari, Marco and Fusi, Luca and Irving, Thomas C. and Gore, David and Piazzesi, Gabriella and Irving, Malcolm and Lombardi, Vincenzo and Reconditi, Massimo},
abstractNote = {Myosin motors in the thick filament of resting striated (skeletal and cardiac) muscle are trapped in an OFF state, in which the motors are packed in helical tracks on the filament surface, inhibiting their interactions with actin and utilization of ATP. To investigate the structural changes induced in the thick filament of mammalian skeletal muscle by changes in temperature, we collected x-ray diffraction patterns from the fast skeletal muscle extensor digitorum longus of the mouse in the temperature range from near physiological (35°C) to 10°C, in which the maximal isometric force ( T 0 ) shows a threefold decrease. In resting muscle, x-ray reflections signaling the OFF state of the thick filament indicate that cooling produces a progressive disruption of the OFF state with motors moving away from the ordered helical tracks on the surface of the thick filament. We find that the number of myosin motors in the OFF state at 10°C is half of that at 35°C. At T 0 , changes in the x-ray signals that report the fraction and conformation of actin-attached motors can be explained if the threefold decrease in force associated with lowering temperature is due not only to a decrease in the force-generating transition in the actin-attached motors but also to a twofold decrease in the number of such motors. Thus, lowering the temperature reduces to the same extent the fraction of motors in the OFF state at rest and the fraction of motors attached to actin at T 0 , suggesting that motors that leave the OFF state accumulate in a disordered refractory state that makes them unavailable for interaction with actin upon stimulation. This regulatory effect of temperature on the thick filament of mammalian skeletal muscle could represent an energetically convenient mechanism for hibernating animals.},
doi = {10.1085/jgp.201912424},
journal = {Journal of General Physiology},
number = ,
volume = ,
place = {United States},
year = {2019},
month = {9}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1085/jgp.201912424

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