Pre-steady-state kinetic evidence for a cyclic interaction of myosin subfragment one with actin during the hydrolysis of adenosine 5'-triphosphate

Sp, Chock; Pb, Chock; Eisenberg, Evan

doi:10.1021/bi00660a013

Cited by 68 publications

(45 citation statements)

References 28 publications

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“…This effect of the ionic strength in a rather narrow range is not unexpected since several steps in the scheme of the ATP hydrolysis by acto-myosin subfragments are saltsensitive [24,381, such as the binding step of actin on myosin or on the intermediate complex of myosin and its reaction products. For these last steps the plot of log k,,, = a I/r + b is linear with a, the product of the interacting charges ZAZB, equal to -5.3, which indicates that there is a neutralization of charges at the binding site [25]. The close value of a (-8.…”

Section: Resultsmentioning

confidence: 96%

Effect of the filamentous structure of myosin on the actomyosin ATPase activity

Béchet

d’Albis

1985

European Journal of Biochemistry

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The ATPase activities of acto-heavy meromyosin and of acto-myosin minifilaments have been compared under the same conditions at low ATP (0.1 mM) and at several KCl concentrations. The activities, which are strongly salt-dependent in both systems, have been found to be similar at high ionic strength (about 0.16 M) but different at lower ionic strength (0.06-0.07 M). Under this last condition, the catalytic constants k,,, and K , are lower for acto-myosin minifilaments than for acto-heavy meromyosin ATPase. In addition, at low ionic strength, any decrease in the concentration of any of the ionic species (ATP, citrate, etc.) induces an increase in the interaction strength between myosin and actin filaments, as revealed by the K , changes. The presence of the troponintropomyosin complex and of Ca2+ also enhances the strength of this interaction. On the other hand, the occurrence of particular interactions between F-actin and myosin minifilaments is further substantiated by the phenomenon of superprecipitation which occurs when the ATP concentration decreases. The favourable effect of the organized structure of the myosin minifilaments on the ATPase activity of actomyosin is discussed.Studies of the Mg2+-ATPase activity of actomyosin in solution are complicated by the solubility properties of the two filamentous proteins of the complex, myosin and actin. Thus the time courses of ATP hydrolysis by actomyosin are not linear [l, 21, the Eadie plots (reaction rate versus reaction rate upon actin concentration) are biphasic [3], and actomyosin superprecipitates when the concentration of ATP becomes low [4, 51. The mechanism of actomyosin adenosine triphosphatase has therefore been mainly deduced from studies performed with the two active soluble myosin subfragments, heavy meromyosin (HMM) and subfragment-1 (S-l), with which the above complications do not occur.Reisler et al. have recently settled conditions for obtaining soluble myosin filaments; they determined that this preparation which consists of a homogeneous population of short bipolar minifilaments [6 -81 displays in the particular conditions of low ionic strength and high actin concentration an actin-activated Mg2 +-ATPase activity which is similar to that of acto-HMM [9, 101. With the purpose of specifying more precisely the effect of the organized structure of filamentous myosin on the mechanism of actomyosin ATPase, we have extended this comparison between the ATPase activities of acto-HMM and of acto-myosin minifilaments to various experimental conditions, at several ionic strengths.We have found that the ATPase activity of acto-myosin minifilaments is more sensitive to the concentration of any ionic species (KC1, ATP, citrate, etc.) present in the medium than the acto-HMM ATPase; in particular, the interaction strength between actin and myosin filaments in the presence of ATP increases strongly when the concentration of the ionic species decreases. The presence of both the tropomyosintroponin complex and Ca2+ also facilitates this interaction. Abbreviations....

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Section: Resultsmentioning

confidence: 96%

Effect of the filamentous structure of myosin on the actomyosin ATPase activity

Béchet

d’Albis

1985

European Journal of Biochemistry

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“…A rapid proton release can also be observed with a pH electrode at pH 8 at 20°C by comparing the pH change during single-turnover experiments in the presence and in the absence of ADP (Bagshaw & Trentham, 1974). However, since the rate of ATP cleavage is fast at this temperature, it is difficult to determine from these experiments whether the 'proton burst' with ATP is due to the binding step (suggested by Bagshaw & Trentham, 1974) or the cleavage step (suggested by Chock, 1979). Attempts to test this by measuring the pH-dependence of K2 remain equivocal, since K2 is constant between pH 8.5 and 7 but decreases below pH 7 (Taylor, 1977;.…”

Section: Thermodynamic Datamentioning

confidence: 99%

A transient kinetic study of enthalpy changes during the reaction of myosin subfragment 1 with ATP.

Millar

Howarth

Gutfreund

1987

Biochemical Journal

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1. The enthalpy changes during individual reaction steps of the myosin subfragment 1 ATPase were studied with the use of a new stopped-flow calorimeter [Howarth, Millar & Gutfreund (1987) Biochem. J. 248, 677-682]. 2. At 5 degrees C and pH 7.0, the endothermic on-enzyme ATP-cleavage step was observed directly (delta H = +64 kJ.mol-1). 3. ADP binding is accompanied by a biphasic enthalpy change. 4. The release and uptake of protons was investigated by the use of two buffers with widely different heats of ionization. 5. Protons are involved in all four principal steps of the myosin subfragment 1 ATPase.

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“…Since this slower rate process is not depefident on actin concentration, the turnover of ATP by S-1 (Al) appears to be controlled by a unimolecular transition occurring before actin reassociation (see [28]). …”

Section: Actin-activated Atpase Activities Of S-1 Isoenzymes Determinmentioning

confidence: 99%

“…Although this number is only a crude estimate, it seems unlikely that the cleavage step itself is rate limiting for S-1 (Al) and not for S-1 (A2) when both isoenzymes give the same rate of fluorescence enhancement on ATP binding. If the turnover of ATP by S-I (Al) in the presence of actin is controlled by a unimolecular transition occurring before actin reassociation, this may indicate another process in the ATPase mechanism [28].…”

Section: Actin-activated Atpase Activities Of S-1 Isoenzymes Determinmentioning

confidence: 99%

Studies on the Actin Activation of Myosin Subfragment‐1 Isoenzymes and the Role of Myosin Light Chains

Wagner¹,

Slater²,

Pope³

et al. 1979

European Journal of Biochemistry

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The actin-activated ATPase activity of myosin subfragment 1 (S-1) isoenzymes, separated on the basis of their alkali light chain (A1 and A2) content, has been analysed under a number of different conditions. Previous experiments on the effects of increasing actin concentrations on the ATPase have shown that the maximum turnover rate of ATP by S-1 (A2) was about twice that of S-1 (Al), and the K , for actin was also considerably larger for this isoenzyme. Here we show that these kinetic differences are maintained when regulated actin (actin + tropomyosin + troponin) is used in place of purified F-actin. However, while increasing the ionic strength of the solution from 6 mM to 46 mM KCl has little effect on V for S-1 (A2), the corresponding value for S-1 (Al) increases to approximately equal that of S-1 (A2), suggesting that the two isoenzymes are controlled by the same rate-limiting process in the steady state under these conditions. The value of K , also increases with increasing ionic strength for the two isoenzymes, but that for S-1 (Al) increases more rapidly and approaches that for S-1 (A2). These experiments were carried out at at fixed S-1 concentration, but the maximum rate of actin activation of the S-1 ATPase can also be obtained from experiments where the actin concentration is fixed and the S-1 concentration varied. Under these conditions in 6 mM KCl, the maximum rate of ATP hydrolysis expressed per mole of actin at infinite S-1 concentration is the same for both s-1 (Al) and s-1 (A2), and this value numerically equals the maximum rate of hydrolysis of ATP by S-1 (A2) expressed at infinite actin concentration. These results suggest that the rate-limiting step in the ATPase cycle for S-1 (A2) is the release of products from an actin . S-1 . ADP . Pi complex, while for S-1 (Al), where the value of V at infinite actin concentration is considerably lower, a different process is rate limiting, and this process may occur before actin reassociation with the S-1 . ADP . Pi complex, using the Lymn-Taylor kinetic model. Thus increasing the ionic strength appears to change the rate-limiting process in the steady-state hydrolysis of ATP by actoS-1 (Al). These experiments are discussed in terms of the role of the alkali light chains in the myosin ATPase and muscle contraction.

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Pre-steady-state kinetic evidence for a cyclic interaction of myosin subfragment one with actin during the hydrolysis of adenosine 5'-triphosphate

Cited by 68 publications

References 28 publications

Effect of the filamentous structure of myosin on the actomyosin ATPase activity

Effect of the filamentous structure of myosin on the actomyosin ATPase activity

A transient kinetic study of enthalpy changes during the reaction of myosin subfragment 1 with ATP.

Studies on the Actin Activation of Myosin Subfragment‐1 Isoenzymes and the Role of Myosin Light Chains

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