Structural changes of the regulatory proteins bound to the thin filaments in skeletal muscle contraction by X-ray fiber diffraction

Sugimoto, Yoshiaki; Takezawa, Yasunori; Matsuo, Tatsuhiro; Ueno, Yutaka; Minakata, Shiho; Tanaka, Hidehiro; Wakabayashi, Katsuzo

doi:10.1016/j.bbrc.2007.11.088

Cited by 16 publications

(21 citation statements)

References 26 publications

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“…The structural changes of the troponin complex may be followed by monitoring a series of meridional reflections based on its 38-nm repeat. According to previous timeresolved measurements using living frog muscles, the intensity of the strongest first-order reflection shows complex behavior after stimulation (i.e., enhancement followed by diminution) (9)(10)(11)(12)(13)(14).…”

Section: Introductionmentioning

confidence: 69%

“…After an initial fast phase, the rate of rise decreased, and finally the intensity began to decline. A transient rise of the first-order reflection, followed by a decline, was observed in living frog muscle (9,13,14), but the process seems to be slower in rabbit fibers. The behavior of the second reflection is similar to that of the first reflection.…”

Section: Time Course Of Intensity Changes After Flash Photolysis Of Cmentioning

confidence: 94%

“…These observations were interpreted to indicate the structural change of actin monomer upon thin-filament activation (17). Although the first meridional peak of the troponin reflection (1/38 nm À1 ) seems to be weakened during contraction, its off-meridional part is intensified, suggesting that the reflection is broadened along the equator because of decreased filament-lattice order (13). The integrated intensities of major thin-filament-based reflections, as determined in the same manner as in time-resolved measurements, are summarized in Table 1.…”

Section: Static Diffraction Patterns Of Fibers In Relaxing and Contramentioning

confidence: 97%

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Dynamics of Thin-Filament Activation in Rabbit Skeletal Muscle Fibers Examined by Time-Resolved X-Ray Diffraction

Tamura

Wakayama

Inoue

et al. 2009

Biophysical Journal

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By using skinned-rabbit skeletal muscle fibers, the time courses of changes of thin filament-based x-ray reflections were followed at a 3.4-ms time resolution during thin-filament activation. To discriminate between the effects of calcium binding and myosin binding on thin-filament activity, measurements were performed after caged-calcium photolysis in fibers with full-filament or no-filament overlap, or during force recovery after a quick release. All three reflections examined, i.e., the second actin layer line (second ALL, reporting the tropomyosin movement), the sixth ALL (reporting actin structural change), and the meridional troponin reflections, exhibited calcium-induced and myosin-induced components, but their rate constants and polarities were different. Generally, calcium-induced components exhibited fast rate constants (>100 s(-1)). The myosin-induced components of the second ALL had a rate constant similar to that of the force (7-10 s(-1)), but that of the sixth ALL was apparently faster. The myosin-induced component of troponin reflection was the only one with negative polarity, and was too slow to be analyzed with this protocol. The results suggest that the three regulation-related proteins change their structures with different rate constants, and the significance of these findings is discussed in the context of a cooperative thin-filament activation mechanism.

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Section: Introductionmentioning

confidence: 69%

Section: Time Course Of Intensity Changes After Flash Photolysis Of Cmentioning

confidence: 94%

Section: Static Diffraction Patterns Of Fibers In Relaxing and Contramentioning

confidence: 97%

See 1 more Smart Citation

Dynamics of Thin-Filament Activation in Rabbit Skeletal Muscle Fibers Examined by Time-Resolved X-Ray Diffraction

Tamura

Wakayama

Inoue

et al. 2009

Biophysical Journal

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“…2, thin line) the myosin‐based ML1 and M2 reflections become very weak (Huxley et al 1982), as does the C1 reflection (Martin‐Fernandez et al 1994; Matsuo & Yagi, 2008). The T1 reflection changes to a smaller extent (Martin‐Fernandez et al 1994; Matsuo & Yagi, 2008; Sugimoto et al 2008). The M3 remains strong, but broadens across the meridian and moves closer to the centre of the X‐ray diagram, indicating an increase in the axial spacing of the myosin filament backbone by about 1.5% (Huxley et al 1982; Linari et al 2000).…”

Section: Resultsmentioning

confidence: 99%

Structural changes in myosin motors and filaments during relaxation of skeletal muscle

Brunello

Fusi

Reconditi

et al. 2009

The Journal of Physiology

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Structural changes in myosin motors and filaments during relaxation from short tetanic contractions of intact single fibres of frog tibialis anterior muscles at sarcomere length 2.14 μm, 4• C were investigated by X-ray diffraction. Force declined at a steady rate for several hundred milliseconds after the last stimulus, while sarcomere lengths remained almost constant. During this isometric phase of relaxation the intensities of the equatorial and meridional M3 X-ray reflections associated with the radial and axial distributions of myosin motors also recovered at a steady rate towards their resting values, consistent with progressive net detachment of myosin motors from actin filaments. Stiffness measurements confirmed that the fraction of motors attached to actin declined at a constant rate, but also revealed a progressive increase in force per motor. The interference fine structure of the M3 reflection suggested that actin-attached myosin motors are displaced towards the start of their working stroke during isometric relaxation. There was negligible recovery of the intensities of the meridional and layer-line reflections associated with the quasi-helical distribution of myosin motors in resting muscle during isometric relaxation, and the 1.5% increase in the axial periodicity of the myosin filament associated with muscle activation was not reversed. When force had decreased to roughly half its tetanus plateau value, the isometric phase of relaxation abruptly ended, and the ensuing chaotic relaxation had an exponential half-time of ca 60 ms. Recovery of the equatorial X-ray intensities was largely complete during chaotic relaxation, but the other X-ray signals recovered more slowly than force.

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“…The intensity of the T1 meridional X-ray reflection (I T1 ) associated with the approximately 38-nm repeat of troponin along the thin filaments increases during latency relaxation (Fig. 4A), signaling a change in the structure of troponin on binding calcium (18,24,25). However, this I T1 increase is transient, and I T1 has already fallen to near its tetanus plateau value by approximately 50 ms, when force is only half-maximum.…”

Section: Sequence Of Structural Changes In Myosin and Actin Filamentsmentioning

confidence: 95%

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.

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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Structural changes of the regulatory proteins bound to the thin filaments in skeletal muscle contraction by X-ray fiber diffraction

Cited by 16 publications

References 26 publications

Dynamics of Thin-Filament Activation in Rabbit Skeletal Muscle Fibers Examined by Time-Resolved X-Ray Diffraction

Dynamics of Thin-Filament Activation in Rabbit Skeletal Muscle Fibers Examined by Time-Resolved X-Ray Diffraction

Structural changes in myosin motors and filaments during relaxation of skeletal muscle

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

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