Abstract
Fluorescence stopped-flow experiments were performed to elucidate the elementary steps of the ATPase mechanism of scallop heavy meromyosin in the presence and in the absence of Ca2+. ATP binding and hydrolysis, as monitored by the change in tryptophan fluorescence, appear to be Ca2+-insensitive, whereas both Pi release and ADP release are markedly suppressed in the absence of Ca2+. Rate constants for Pi release are 0.2 s-1 and 0.002 s-1 and for ADP release are 6 s-1 and 0.01 s-1 in the presence and in the absence of Ca2+ respectively. Ca2+ binding to the specific site of the regulatory domain is rapid and its release occurs at 25 s-1, consistent with the time scale of a twitch of the striated adductor muscle. Nucleotide binding is a multi-step process requiring a minimum of three states. In such a model Ca2+ controls the rate of conformational changes at the active site in both the forward and the reverse direction, leading to a large dependence of the rate of nucleotide release, but a lesser effect on the overall equilibrium position. The kinetic trapping of nucleotides and Pi at the active site, in the absence of Ca2+, appears to be a fundamental step in suppressing the interaction of the myosin head with the thin filaments in relaxed molluscan muscle.
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Selected References
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- Bagshaw C. R., Eccleston J. F., Eckstein F., Goody R. S., Gutfreund H., Trentham D. R. The magnesium ion-dependent adenosine triphosphatase of myosin. Two-step processes of adenosine triphosphate association and adenosine diphosphate dissociation. Biochem J. 1974 Aug;141(2):351–364. doi: 10.1042/bj1410351. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bagshaw C. R., Trentham D. R. The characterization of myosin-product complexes and of product-release steps during the magnesium ion-dependent adenosine triphosphatase reaction. Biochem J. 1974 Aug;141(2):331–349. doi: 10.1042/bj1410331. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bagshaw C. R., Trentham D. R. The reversibility of adenosine triphosphate cleavage by myosin. Biochem J. 1973 Jun;133(2):323–328. doi: 10.1042/bj1330323. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bennett A. J., Bagshaw C. R. The kinetics of bivalent metal ion dissociation from myosin subfragments. Biochem J. 1986 Jan 1;233(1):173–177. doi: 10.1042/bj2330173. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bennett A. J., Bagshaw C. R. The mechanism of regulatory light chain dissociation from scallop myosin. Biochem J. 1986 Jan 1;233(1):179–186. doi: 10.1042/bj2330179. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Chantler P. D., Sellers J. R., Szent-Györgyi A. G. Cooperativity in scallop myosin. Biochemistry. 1981 Jan 6;20(1):210–216. doi: 10.1021/bi00504a035. [DOI] [PubMed] [Google Scholar]
- Chock S. P., Chock P. B., Eisenberg E. The mechanism of the skeletal muscle myosin ATPase. II. Relationship between the fluorescence enhancement induced by ATP and the initial Pi burst. J Biol Chem. 1979 May 10;254(9):3236–3243. [PubMed] [Google Scholar]
- Chock S. P., Eisenberg E. The mechanism of the skeletal muscle myosin ATPase. I. Identity of the myosin active sites. J Biol Chem. 1979 May 10;254(9):3229–3235. [PubMed] [Google Scholar]
- Gutfreund H. Kinetic analysis of the properties and reactions of enzymes. Prog Biophys Mol Biol. 1975;29(2):161–195. doi: 10.1016/0079-6107(76)90022-5. [DOI] [PubMed] [Google Scholar]
- Jackson A. P., Bagshaw C. R. Kinetic trapping of intermediates of the scallop heavy meromyosin adenosine triphosphatase reaction revealed by formycin nucleotides. Biochem J. 1988 Apr 15;251(2):527–540. doi: 10.1042/bj2510527. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Johnson K. A., Taylor E. W. Intermediate states of subfragment 1 and actosubfragment 1 ATPase: reevaluation of the mechanism. Biochemistry. 1978 Aug 22;17(17):3432–3442. doi: 10.1021/bi00610a002. [DOI] [PubMed] [Google Scholar]
- Konno K., Arai K., Watanabe S. Fluorescence intensity and UV absorption changes accompanying dissociation and association of regulatory light chain of scallop adductor myosin. J Biochem. 1983 Oct;94(4):1061–1066. doi: 10.1093/oxfordjournals.jbchem.a134448. [DOI] [PubMed] [Google Scholar]
- Lehman W., Szent-Györgyi A. G. Regulation of muscular contraction. Distribution of actin control and myosin control in the animal kingdom. J Gen Physiol. 1975 Jul;66(1):1–30. doi: 10.1085/jgp.66.1.1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Millar N. C., Geeves M. A. The limiting rate of the ATP-mediated dissociation of actin from rabbit skeletal muscle myosin subfragment 1. FEBS Lett. 1983 Aug 22;160(1-2):141–148. doi: 10.1016/0014-5793(83)80954-5. [DOI] [PubMed] [Google Scholar]
- Rall J. A. Mechanics and energetics of contraction in striated muscle of the sea scallop, Placopecten magellanicus. J Physiol. 1981 Dec;321:287–295. doi: 10.1113/jphysiol.1981.sp013984. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schaub M. C., Watterson J. G. Symmetry and asymmetry in the contractile protein myosin. Biochimie. 1981 Apr;63(4):291–299. doi: 10.1016/s0300-9084(81)80117-4. [DOI] [PubMed] [Google Scholar]
- Shibata-Sekiya K. Reaction intermediates of myosin ATPase from scallop adductor muscles: nonidentical two-headed structure of striated adductor muscle myosin. J Biochem. 1982 Oct;92(4):1151–1162. doi: 10.1093/oxfordjournals.jbchem.a134031. [DOI] [PubMed] [Google Scholar]
- Smith P. D., Liesegang G. W., Berger R. L., Czerlinski G., Podolsky R. J. A stopped-flow investigation of calcium ion binding by ethylene glycol bis(beta-aminoethyl ether)-N,N'-tetraacetic acid. Anal Biochem. 1984 Nov 15;143(1):188–195. doi: 10.1016/0003-2697(84)90575-x. [DOI] [PubMed] [Google Scholar]
- Taylor E. W. Mechanism of actomyosin ATPase and the problem of muscle contraction. CRC Crit Rev Biochem. 1979;6(2):103–164. doi: 10.3109/10409237909102562. [DOI] [PubMed] [Google Scholar]
- Trentham D. R., Eccleston J. F., Bagshaw C. R. Kinetic analysis of ATPase mechanisms. Q Rev Biophys. 1976 May;9(2):217–281. doi: 10.1017/s0033583500002419. [DOI] [PubMed] [Google Scholar]
- Trybus K. M., Taylor E. W. Transient kinetics of adenosine 5'-diphosphate and adenosine 5'-(beta, gamma-imidotriphosphate) binding to subfragment 1 and actosubfragment 1. Biochemistry. 1982 Mar 16;21(6):1284–1294. doi: 10.1021/bi00535a028. [DOI] [PubMed] [Google Scholar]
- Vibert P., Szentkiralyi E., Hardwicke P., Szent-Györgyi A. G., Cohen C. Structural models for the regulatory switch of Myosin. Biophys J. 1986 Jan;49(1):131–133. doi: 10.1016/S0006-3495(86)83622-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Walmsley A. R., Lowe A. G. Multifit: a flexible non-linear least squares regression program in BASIC. Comput Methods Programs Biomed. 1985 Nov;21(2):113–118. doi: 10.1016/0169-2607(85)90070-7. [DOI] [PubMed] [Google Scholar]
- Wells C., Bagshaw C. R. Calcium regulation of molluscan myosin ATPase in the absence of actin. Nature. 1985 Feb 21;313(6004):696–697. doi: 10.1038/313696a0. [DOI] [PubMed] [Google Scholar]
- Wells C., Bagshaw C. R. Segmental flexibility and head-head interaction in scallop myosin. A study using saturation transfer electron paramagnetic resonance spectroscopy. J Mol Biol. 1983 Feb 15;164(1):137–157. doi: 10.1016/0022-2836(83)90090-6. [DOI] [PubMed] [Google Scholar]
- Wells C., Warriner K. E., Bagshaw C. R. Fluorescence studies on the nucleotide- and Ca2+-binding domains of molluscan myosin. Biochem J. 1985 Oct 1;231(1):31–38. doi: 10.1042/bj2310031. [DOI] [PMC free article] [PubMed] [Google Scholar]