Mode of filament assembly of myosins from muscle and nonmuscle cells

Hinssen, Horst; D’Haese, Jochen; Small, J. Victor; Sobieszek, Apolinary

doi:10.1016/s0022-5320(78)90037-0

Cited by 93 publications

(47 citation statements)

References 43 publications

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“…The 14.5-nm repeat in the relaxed scallop synthetic myosin filaments is similar to that in native scallop filaments (Vibert and Craig, 1983) and is much more regular than that in synthetic filaments formed from other (mainly rabbit) striated muscle myosins (e.g., Huxley, 1963;Moos et al, 1975; Pollard, 1975;Hinssen et al, 1978;Pinset-H/irstr6m and Truffy, 1979;Pinset-H/irstr6m, 1985). This may be related to the fact that some of these other studies were done in the absence of ATE conditions under which we find a disordered structure, and/or it may reflect a generally greater stability of the myosin cross-bridge array in regulated myosin filaments (cf.…”

Section: Discussionmentioning

confidence: 63%

“…This may be related to the fact that some of these other studies were done in the absence of ATE conditions under which we find a disordered structure, and/or it may reflect a generally greater stability of the myosin cross-bridge array in regulated myosin filaments (cf. Hinssen et al, 1978;Ikebe and Ogihara, 1982;Kensler and Levine, 1982;Craig, R., unpublished data), which can be switched off under relaxing conditions (giving rise to an ordered structure), compared with unregulated myosins (e.g., rabbit) which cannot be switched off. In the relaxed state the myosin heads appear to be closely associated with the filament backbone.…”

Section: Discussionmentioning

confidence: 97%

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Structural changes induced in Ca2+-regulated myosin filaments by Ca2+ and ATP.

Frado

Craig

1989

The Journal of Cell Biology

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Abstract. We have used electron microscopy and proteolytic susceptibility to study the structural basis of myosin-linked regulation in synthetic filaments of scallop striated muscle myosin. Using papain as a probe of the structure of the head-rod junction, we find that this region of myosin is approximately five times more susceptible to proteolytic attack under activating (ATP/high Ca 2÷) or rigor (no ATP) conditions than under relaxing conditions (ATP/Iow Ca2+). A similar result was obtained with native myosin filaments in a crude homogenate of scallop muscle. Proteolytic susceptibility under conditions in which ADP or adenosine 5'-(~,3~-imidotriphosphate) (AMPPNP) replaced ATP was similar to that in the absence of nucleotide. Synthetic myosin filaments negatively stained under relaxing conditions showed a compact structure, in which the myosin cross-bridges were close to the filament backbone and well ordered, with a clear 14.5-nm axial repeat. Under activating or rigor conditions, the cross-bridges became clumped and disordered and frequently projected further from the filament backbone, as has been found with native filaments; when ADP or AMPPNP replaced ATE the cross-bridges were also disordered. We conclude (a) that Ca 2÷ and ATP affect the affinity of the myosin cross-bridges for the filament backbone or for each other; (b) that the changes observed in the myosin filaments reflect a property of the myosin molecules alone, and are unlikely to be an artifact of negative staining; and (c) that the ordered structure occurs only in the relaxed state, requiring both the presence of hydrolyzed ATP on the myosin heads and the absence of Ca 2÷.

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Section: Discussionmentioning

confidence: 63%

Section: Discussionmentioning

confidence: 97%

Structural changes induced in Ca2+-regulated myosin filaments by Ca2+ and ATP.

Frado

Craig

1989

The Journal of Cell Biology

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“…One important determinant for the proposed structure of the contractile unit of smooth muscle is the side-polar thick filament; evidence for such filaments in smooth muscle was provided by several key studies (6, 37, 40, 45). The row-polar thick filament suggested by Hinssen et al (20) could also work for the proposed contractile unit. Evidence for the dense bodies acting as anchorage sites for the thin filaments was provided by some early studies (4,11,26,42).…”

Section: Assumptions Associated With the Modelsmentioning

confidence: 79%

Time course of isotonic shortening and the underlying contraction mechanism in airway smooth muscle

Syyong

Raqeeb

Paré

et al. 2011

Journal of Applied Physiology

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Syyong HT, Raqeeb A, Paré PD, Seow CY. Time course of isotonic shortening and the underlying contraction mechanism in airway smooth muscle. J Appl Physiol 111: 642-656, 2011. First published June 2, 2011; doi:10.1152/japplphysiol.00085.2011.-Although the structure of the contractile unit in smooth muscle is poorly understood, some of the mechanical properties of the muscle suggest that a sliding-filament mechanism, similar to that in striated muscle, is also operative in smooth muscle. To test the applicability of this mechanism to smooth muscle function, we have constructed a mathematical model based on a hypothetical structure of the smooth muscle contractile unit: a side-polar myosin filament sandwiched by actin filaments, each attached to the equivalent of a Z disk. Model prediction of isotonic shortening as a function of time was compared with data from experiments using ovine tracheal smooth muscle. After equilibration and establishment of in situ length, the muscle was stimulated with ACh (100 M) until force reached a plateau. The muscle was then allowed to shorten isotonically against various loads. From the experimental records, length-force and force-velocity relationships were obtained. Integration of the hyperbolic force-velocity relationship and the linear length-force relationship yielded an exponential function that approximated the time course of isotonic shortening generated by the modeled sliding-filament mechanism. However, to obtain an accurate fit, it was necessary to incorporate a viscoelastic element in series with the sliding-filament mechanism. The results suggest that a large portion of the shortening is due to filament sliding associated with muscle activation and that a small portion is due to continued deformation associated with an element that shows viscoelastic or power-law creep after a step change in force. mathematical model; contractile unit; sliding-filament mechanism THE STRUCTURE OF THE CONTRACTILE unit in smooth muscle is unknown, despite the common belief that the cycling-crossbridge/sliding-filament mechanism of contraction, which operates in striated muscle, is also responsible for smooth muscle contraction. The predominant model for the sarcomere-equivalent contractile unit in smooth muscle is a side-polar myosin (thick) filament sandwiched by two oppositely oriented actin (thin) filaments, each attached to a dense body that is believed to function like a Z disk in striated muscle (18,21,27), as shown in Fig. 1. An important assumption associated with the model is that the sliding of the thick and thin filaments relative to each other is caused by repetitive interaction of the myosin heads (cross bridges) of the thick filament with the thin filaments, in the same manner described for striated muscle (22,23). Such a cross-bridge mechanism for smooth muscle myosin has been observed in experiments where the interaction of isolated individual myosin heads with thin filaments was visualized and quantified directly (14, 15, 28). As predicted by Huxley's 1957 model (22), the ...

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“…Smooth muscle thick filaments are probably side-polar (Small, 1977;Cooke et al, 1987;Xu et al, 1996;Tonino et al, 2002), or row-polar (Hinssen et al, 1978), in contrast to the bipolar variety found in striated muscle. A contractile unit in smooth muscle therefore is probably different from a sarcomere in terms of its functional mechanism and how it is assembled.…”

Section: Smooth Muscle Contractile Unitmentioning

confidence: 99%

`Sarcomeres' of smooth muscle: functional characteristics and ultrastructural evidence

Herrera

McParland

Bienkowska

et al. 2005

Journal of Cell Science

103

123

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Smooth muscle cells line the walls of hollow organs and control the organ dimension and mechanical function by generating force and changing length. Although significant progress has been made in our understanding of the molecular mechanism of actomyosin interaction that produces sliding of actin (thin) and myosin (thick) filaments in smooth muscle, the sarcomeric structure akin to that in striated muscle, which allows the sliding of contractile filaments to be translated into cell shortening has yet to be elucidated. Here we show evidence from porcine airway smooth muscle that supports a model of malleable sarcomeric structure composed of contractile units assembled in series and in parallel. The geometric organization of the basic building blocks (contractile units) within the assembly and the dimension of individual contractile units can be altered when the muscle cells adapt to different lengths. These structural alterations can account for the different length-force relationships of the muscle obtained at different adapted cell lengths. The structural malleability necessary for length adaptation precludes formation of a permanent filament lattice and explains the lack of aligned filament arrays in registers, which also explains why smooth muscle is `smooth'.

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Mode of filament assembly of myosins from muscle and nonmuscle cells

Cited by 93 publications

References 43 publications

Structural changes induced in Ca2+-regulated myosin filaments by Ca2+ and ATP.

Structural changes induced in Ca2+-regulated myosin filaments by Ca2+ and ATP.

Time course of isotonic shortening and the underlying contraction mechanism in airway smooth muscle

`Sarcomeres' of smooth muscle: functional characteristics and ultrastructural evidence

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