Mechanism of force generation by myosin heads in skeletal muscle

Piazzesi, Gabriella; Reconditi, Massimo; Linari, Marco; Lucii, L; Sun, Yin-Biao; Narayanan, Theyencheri; Boesecke, Peter; Lombardi, Vincenzo; Irving, Malcolm

doi:10.1038/415659a

Cited by 136 publications

(219 citation statements)

References 28 publications

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“…At the tetanus plateau (Fig. 1B, dark blue), the 14.66-nm peak was more intense than the 14.47-nm peak (8,19). The total intensity of the M3 reflection (I M3 ), corrected for the decrease in lateral alignment between filaments on activation by multiplying by the radial width of the reflection (13), had a biphasic time course (Fig.…”

Section: Resultsmentioning

confidence: 97%

“…This multiplies the simple diffraction peak corresponding to the head periodicity (d) by an interference fringe pattern, splitting the M3 reflection into two or three component peaks, and allowing the movements of the heads along the filaments to be determined with subnanometer precision (8)(9)(10)(11).…”

Section: Resultsmentioning

confidence: 99%

“…Typically, the length of an active muscle fiber was rapidly decreased, displacing each set of myosin filaments by a few nanometers with respect to the opposing actin filaments (2). Such a shortening step produces an elastic force decrease during the step, followed in the next few milliseconds by rapid force regeneration driven by the working stroke in actin-attached myosin heads (2,7,8). This and related protocols have revealed fundamental properties of the working stroke, including its size, speed, and load dependence, and shown how the macroscopic performance of muscle is related to the molecular mechanics and dynamics of the myosin-actin interaction (8-11).…”

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confidence: 99%

“…Filament sliding is driven by a change in conformation of the actin-bound myosin head: its working stroke (1)(2)(3). A detailed molecular model for the working stroke has been derived from biochemical and structural studies of isolated myosin head domains and their interaction with actin and ATP (3)(4)(5)(6), and the quasi-crystalline organization of myosin and actin in muscle has allowed this model to be tested and elaborated by mechanical and structural studies on muscle cells (1,2,(7)(8)(9)(10)(11).…”

mentioning

confidence: 99%

“…Such a shortening step produces an elastic force decrease during the step, followed in the next few milliseconds by rapid force regeneration driven by the working stroke in actin-attached myosin heads (2,7,8). This and related protocols have revealed fundamental properties of the working stroke, including its size, speed, and load dependence, and shown how the macroscopic performance of muscle is related to the molecular mechanics and dynamics of the myosin-actin interaction (8)(9)(10)(11). However, these perturbations are applied to muscle cells that are already generating force, and do not directly address the question of the physiological mechanism of force generation starting from the resting state in which the myosin heads are detached from actin.…”

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confidence: 99%

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Motion of myosin head domains during activation and force development in skeletal muscle

Reconditi

Brunello²,

Linari³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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114

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Muscle contraction is driven by a change in the structure of the head domain of myosin, the "working stroke" that pulls the actin filaments toward the midpoint of the myosin filaments. This movement of the myosin heads can be measured very precisely in intact muscle cells by X-ray interference, but until now this technique has not been applied to physiological activation and force generation following electrical stimulation of muscle cells. By using this approach, we show that the long axes of the myosin head domains are roughly parallel to the filaments in resting muscle, with their center of mass offset by approximately 7 nm from the C terminus of the head domain. The observed mass distribution matches that seen in electron micrographs of isolated myosin filaments in which the heads are folded back toward the filament midpoint. Following electrical stimulation, the heads move by approximately 10 nm away from the filament midpoint, in the opposite direction to the working stroke. The time course of this motion matches that of force generation, but is slower than the other structural changes in the myosin filaments on activation, including the loss of helical and axial order of the myosin heads and the change in periodicity of the filament backbone. The rate of force development is limited by that of attachment of myosin heads to actin in a conformation that is the same as that during steadystate isometric contraction; force generation in the actin-attached head is fast compared with the attachment step.C ontraction of skeletal muscles is driven by a cyclical interaction between myosin and actin, fueled by the hydrolysis of ATP. The myosin and actin are polymerized into parallel thick and thin filaments, which themselves are organized into a hexagonal array in the muscle cell. The head domains of myosin lie on the surface of the thick filaments and bind to actin in the thin filaments. Filament sliding is driven by a change in conformation of the actin-bound myosin head: its working stroke (1-3). A detailed molecular model for the working stroke has been derived from biochemical and structural studies of isolated myosin head domains and their interaction with actin and ATP (3-6), and the quasi-crystalline organization of myosin and actin in muscle has allowed this model to be tested and elaborated by mechanical and structural studies on muscle cells (1, 2, 7-11).Many of these cell-based studies used rapid perturbations to synchronize the actions of the myosin heads in a muscle cell. Typically, the length of an active muscle fiber was rapidly decreased, displacing each set of myosin filaments by a few nanometers with respect to the opposing actin filaments (2). Such a shortening step produces an elastic force decrease during the step, followed in the next few milliseconds by rapid force regeneration driven by the working stroke in actin-attached myosin heads (2,7,8). This and related protocols have revealed fundamental properties of the working stroke, including its size, speed, and load dependence, and shown how ...

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Motion of myosin head domains during activation and force development in skeletal muscle

Reconditi

Brunello²,

Linari³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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114

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Myosin's powerstroke occurs prior to the release of phosphate from the active site

et al. 2021

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Myosins are a family of motor proteins responsible for various forms of cellular motility, including muscle contraction and vesicular transport. The most fundamental aspect of myosin is its ability to transduce the chemical energy from the hydrolysis of ATP into mechanical work, in the form of force and/or motion. A key unanswered question of the transduction process is the timing of the force-generating powerstroke relative to the release of phosphate (P i ) from the active site. We examined the ability of single-headed myosin Va to generate a powerstroke in a single molecule laser trap assay while maintaining P i in its active site, by either elevating P i in solution or by introducing a mutation in myosin's active site (S217A) to slow P irelease from the active site. Upon binding to the actin filament, WT myosin generated a powerstoke rapidly (≥500 s À1 ) and without a detectable delay, both in the absence and presence of 30 mM P i . The elevated levels of P i did, however, affect event lifetime, eliminating the longest 25% of binding events, confirming that P i rebound to myosin's active site and accelerated detachment. The S217A construct also generated a powerstroke similar in size and rate upon binding to actin despite the slower P i release rate. These findings provide direct evidence that myosin Va generates a powerstroke with P i still in its active site.

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Recent insights into the relative timing of myosin's powerstroke and release of phosphate

Debold

2021

Cytoskeleton

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Myosin is a motor enzyme that converts the chemical energy in ATP into mechanical work to drive a myriad of intracellular processes, from muscle contraction to vesicular transport. Key steps in the transduction of energy are the force‐generating powerstroke, and the release of phosphate (Pi) from the nucleotide‐binding site. Both events occur rapidly after binding to actin, making it difficult to determine which event occurs first. Early efforts suggested that these events occur simultaneously; however, recent findings indicate that they are separate and distinct events that occur at different rates. High‐resolution crystal structures of myosin captured in intermediate states of the ATPase cycle suggest that when Pi is in the active site it prevents the powerstroke from occurring, leading to the hypothesis that Pi‐release precedes the powerstroke. However, advances in functional assays, enabling sub‐millisecond temporal and nanometer spatial resolution, are challenging this hypothesis. For example, Föster Resonance Energy Transfer (FRET) based assays, as well as single molecule laser trap assays, suggest the opposite; that the powerstroke occurs prior to the release of Pi from myosin's active site. This review provides some historical context and then highlights recent reports that reveal exciting new insight into this fundamental mechanism of energy transduction by this prototypical motor enzyme.

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Mechanism of force generation by myosin heads in skeletal muscle

Cited by 136 publications

References 28 publications

Motion of myosin head domains during activation and force development in skeletal muscle

Motion of myosin head domains during activation and force development in skeletal muscle

Myosin's powerstroke occurs prior to the release of phosphate from the active site

Recent insights into the relative timing of myosin's powerstroke and release of phosphate

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