Regulatory light-chains and scallop myosin: Full dissociation, reversibility and co-operative effects

Chantler, Peter D.; Szent‐Györgyi, Albert

doi:10.1016/s0022-2836(80)80013-1

Cited by 162 publications

(93 citation statements)

References 26 publications

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“…Myosin regulation has been extensively studied, particularly in scallop. Both regulatory light chains are required for the most robust myosin regulation (see below) Kendrick-Jones et al, 1976;Simmons andSzent-Györgyi, 1978, 1985;Nishita et al, 1979;Chantler and Szent-Györgyi, 1980;Suzuki et al, 1980;Konno et al, 1981;Ojima and Nishita, 1983;Ojima et al, 1983b;Vale et al, 1984;Chantler, 1985). Similar results have been obtained in abalone and squid (in which the regulatory chain is called LC-2), and abalone and squid LC-2s exchange with scallop regulatory light chains (Asakawa and Azuma, 1983) and can restore Ca ++ sensitivity to scallop myosin from which the regulatory chains have been removed (Konno et al, 1979;Asakawa et al, 1981;Kamiya et al, 1985).…”

Section: 411mentioning

confidence: 99%

Invertebrate muscles: Thin and thick filament structure; molecular basis of contraction and its regulation, catch and asynchronous muscle

Hooper

Hobbs

Thuma

2008

Progress in Neurobiology

128

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This is the second in a series of canonical reviews on invertebrate muscle. We cover here thin and thick filament structure, the molecular basis of force generation and its regulation, and two special properties of some invertebrate muscle, catch and asynchronous muscle. Invertebrate thin filaments resemble vertebrate thin filaments, although helix structure and tropomyosin arrangement show small differences. Invertebrate thick filaments, alternatively, are very different from vertebrate striated thick filaments and show great variation within invertebrates. Part of this diversity stems from variation in paramyosin content, which is greatly increased in very large diameter invertebrate thick filaments. Other of it arises from relatively small changes in filament backbone structure, which results in filaments with grossly similar myosin head placements (rotating crowns of heads every 14.5 nm) but large changes in detail (distances between heads in azimuthal registration varying from three to thousands of crowns). The lever arm basis of force generation is common to both vetebrates and invertebrates, and in some invertebrates this process is understood on the near atomic level. Invertebrate actomyosin is both thin (tropomyosin:troponin) and thick (primarily via direct Ca ++ binding to myosin) filament regulated, and most invertebrate muscles are dually regulated. These mechanisms are well understood on the molecular level, but the behavioral utility of dual regulation is less so. The phosphorylation state of the thick filament associated giant protein, twitchin, has been recently shown to be the molecular basis of catch. The molecular basis of the stretch activation underlying asynchronous muscle activity, however, remains unresolved.

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Section: 411mentioning

confidence: 99%

Invertebrate muscles: Thin and thick filament structure; molecular basis of contraction and its regulation, catch and asynchronous muscle

Hooper

Hobbs

Thuma

2008

Progress in Neurobiology

128

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“…We labeled each myosin molecule in a skinned muscle fiber bundle with a donor probe on one head and an acceptor probe on the other, detected resonance energy transfer to determine distances between the probes, and thus detected changes in this distance during contraction. This specific labeling was made possible by the negative cooperativity of RLC binding in scallop muscle (9,10); the reliability and precision of the measurements was greatly enhanced by the use of Tb 3ϩ as a luminescent donor (11,12).…”

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confidence: 99%

Coordination of the two heads of myosin during muscle contraction

Lidke

Thomas

2002

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

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We have used luminescence resonance energy transfer between regulatory light chains (RLC) to detect structural changes within the dimeric myosin molecule in contracting muscle fibers. Fully functional scallop muscle fibers were prepared such that each myosin molecule contained a terbium-labeled (luminescent donor) RLC on one head and a rhodamine-labeled (acceptor) RLC on the other. Time-resolved luminescence energy transfer between the two heads increased upon the transition from relaxation (ATP) to contraction (ATP plus Ca) and increased further in rigor (no ATP). Combined with experiments on mutant RLCs labeled specifically at other sites, these results support a model in which the forcegenerating weak-to-strong transition causes one myosin LC domain to tilt through a 30°angle toward the other, thus acting as a coordinated lever arm.

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“…5). Since Ca2+ does not bind to desensitized myosin (17), these data suggest that the changes observed in the photolabeling pattern of native myosin were due to Ca2+ binding to the regulatory complex.…”

Section: Discussionmentioning

confidence: 82%

“…Ca2+ binding to this domain increases the ATPase activity by causing a shift in the relative position of the light chains (14)(15)(16) and affects the interaction between the RLC and the heavy chain (11,17,18). The results of these conformational changes have been seen in electron micrographs in which the heads on myosin filaments shift from an ordered array in the absence of Ca2+ to a disordered array in its presence (19).…”

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confidence: 99%

Photolabeling evidence for calcium-induced conformational changes at the ATP binding site of scallop myosin.

Kerwin

Yount²

1993

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

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A change in the conformation ofthe active site of scallop myosin under the influence of regulatory amounts of Ca2+ has been identified by use of the ADP photoaffinity analog 2-[(4-azido-2-nitrophenyl)aminolethyl diphosphate (NANDP).NANDP, trapped at the active site with Mn2+ and vanadate, photolabeled preferentially Arg-128 of the heavy chain in the absence of added Mg2+ and Ca2+ [Kerwin, B. & Yount, R. (1992) Bioconjugate Chem. 3,[328][329][330][331][332][333][334][335][336]. However, addition of 2 mM Mg2+ and regulatory amounts of Ca2+ (0.01-1 ,uM) shifted the predominant labeling to Cys-198 of the heavy chain in a Ca2+-dependent manner. This Ca2+-dependent change in the photolabeling pattern was absent when the regulatory light chains were removed or when the unregulated head (subfragment 1) was examined under similar conditions. These results demonstrate that both Arg-128 and Cys-198 are part of the purine binding site which undergoes a conformational change in response to Ca2+ binding to the regulatory domain.There are two fundamental mechanisms by which Ca2+ regulates muscle contraction. These are either actin-based or myosin-based systems (for review, see ref. 1). Actin-based regulation is present in both skeletal (2, 3) and cardiac muscle (4). Here Ca2+ binding to troponin C on the thin filament promotes the high-affinity binding of myosin to actin necessary for contraction (for review, see ref. 5). In myosin-based systems Ca2+ regulates indirectly through a secondmessenger system or by direct interaction with the myosin. For smooth muscle such as gizzard (6, 7) and nonmuscle cells such as macrophages (8) be involved with the conformational changes associated with Ca2+ regulation.One method of identifying conformational changes in proteins is through photoaffinity labeling (22,23,24). The photoreactive ADP analog 2-[(4-azido-2-nitrophenyl)amino]-ethyl diphosphate (NANDP; Fig. 1) has been used to photolabel the purine binding site ofboth skeletal (25) and scallop (26) myosin. Although NANDP and ADP share only the diphosphate moiety, NANDP has proved to be an excellent analog of ADP. Both NANTP and ATP are hydrolyzed by skeletal (27) and scallop (26) myosin with similar kinetic properties, and NANTP, like ATP, supports tension development in skeletal muscle fibers (28). Molecular modeling of NANDP (S. Johns and R.G.Y., unpublished observations) demonstrated that the aryl azide is in essentially the same position as the aryl azide of 2-azido-ADP, when the purine ring is in the anti-conformation. Moreover, both NANDP (27) and 2-azido-ADP (H. Kuwayama, J. Grammer, and R.G.Y., unpublished results) photolabel Trp-130 of skeletal muscle myosin (25). The analogous amino acid in scallop myosin is Arg-128, which is also photolabeled by NANDP (26) when photolysis is done in the absence of added Mg2+ and Ca2+.In this report we have extended our previous photolabeling studies of the purine binding site of filamentous scallop myosin by photolabeling with NANDP in the presence of Mg2+ and various amounts of ...

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Regulatory light-chains and scallop myosin: Full dissociation, reversibility and co-operative effects

Cited by 162 publications

References 26 publications

Invertebrate muscles: Thin and thick filament structure; molecular basis of contraction and its regulation, catch and asynchronous muscle

Invertebrate muscles: Thin and thick filament structure; molecular basis of contraction and its regulation, catch and asynchronous muscle

Coordination of the two heads of myosin during muscle contraction

Photolabeling evidence for calcium-induced conformational changes at the ATP binding site of scallop myosin.

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