Characterization of the actin-binding site on the alkali light chain of myosin

Henry, Gillian D.; Winstanley, Monica A.; Dalgarno, David C.; Scott, G. M. M.; Levine, Barry A.; Trayer, Ian P.

doi:10.1016/0167-4838(85)90279-1

Cited by 62 publications

(34 citation statements)

References 33 publications

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“…The consideration of conformational distribution in our analysis resulted in a mean distance of 73 Å between Cys-177 on the ELC and Cys-374 of actin, which provides good correlation with the data (89 Å) calculated by using the atomic model of the acto-myosin complex (9). The wide conformational distribution of the ELC is compatible with earlier observations according to which the ELC of S1 might get, at least transiently, in contact with the C-terminal region of actin (29,30). The different helical symmetry of the actin and myosin filaments suggests that the presence of this wide conformational distribution may be important for the formation of rigor cross-bridges between the two filament systems.…”

Section: Resultssupporting

confidence: 79%

“…The simulated transfer efficiencies fit the experimental data only in the case when a wide positional distribution of the label on the light chain-binding domain was assumed ( ϭ 102 Å). These results are compatible with earlier observations according to which there might be a direct interaction between the ELC of S1 and the C-terminal region of actin (29,30). In addition to this our data can support the hypothesis stating that during the power stroke, the light chain-binding domain tilts against the catalytic domain, that is connected to the actin filament in a fixed orientation (9,27,28).…”

supporting

confidence: 82%

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Conformational Distributions and Proximity Relationships in the Rigor Complex of Actin and Myosin Subfragment-1

Nyitrai¹,

Hild²,

Lukács³

et al. 2000

Journal of Biological Chemistry

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Cyclic conformational changes in the myosin head are considered essential for muscle contraction. We hereby show that the extension of the fluorescence resonance energy transfer method described originally by Taylor The cyclic interaction between actin and myosin is thought to provide the molecular basis for muscle contraction (2). There have been numerous attempts to characterize the molecular events underlying the contractile acto-myosin interaction (3). The recent availability of high resolution atomic structures of the actin monomer (4), the actin filament (5-7), myosin S1 (8), and the acto-S1 complex (9) provided a framework for the description of conformational changes associated with the contractile cycle.The atomic models permit the study of proximity relationships between various sites in the acto-myosin complex. An alternative method for studying proximal relationships within a macromolecule is FRET 1 spectroscopy. Several interprotein distances within the acto-myosin complex have been already determined with this latter method (10 -14). The distance between Cys-374 of actin and Cys-707 of S1 under rigor conditions was found to be 60 (11), 50 (12, 15), and 51 Å (14). By the use of scallop myosin hybrid molecules this distance was determined to be 45 Å (16). The distance between Cys-374 of actin and Cys-177 in the ELC of S1 in rigor was measured to be 50 (11) and 60 Å (10). FRET spectroscopy was applied to determine the radial coordinate, i.e. the distance from the imaginary axis of a labeled side chain within the actin filament, where special symmetry conditions are fulfilled (1). The radial coordinate of a number of points in the actin filament and proximal relationships in the S1-and heavy meromyosin-decorated actin filament was determined by this approach (1,(17)(18)(19)(20)(21)(22)(23).Although FRET spectroscopy and x-ray crystallography are significantly different methods, there is usually a good correlation between the distances calculated from the atomic model and the ones obtained by . Accordingly, most of the FRET data obtained in the case of actin and acto-myosin are in a reasonably good agreement with the distances obtained by using the atomic models (5-7, 9). However, an exception is the distance between Cys-177 on ELC of S1 and Cys-374 on the actin filament, because FRET revealed 50 -60 Å (10, 11), whereas the atomic model resulted in ϳ89 Å (9). Although this discrepancy may originate from biologically irrelevant factors (e.g. the nonzero size of the FRET probes (24)), the problem deserves further investigations because of the central role of the light chainbinding domain of S1 in the force generating process (9,27,28).In the present work we analyze the proximity relationships in the rigor acto-S1 complex, with a particular focus on the conformational distributions of the light chain-binding domain associated with a donor-acceptor distance distribution. The FRET method, developed originally by Taylor et al. (1) for radial coordinate determinations in actin filament, was extended to obtai...

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Section: Resultssupporting

confidence: 79%

supporting

confidence: 82%

Conformational Distributions and Proximity Relationships in the Rigor Complex of Actin and Myosin Subfragment-1

Nyitrai¹,

Hild²,

Lukács³

et al. 2000

Journal of Biological Chemistry

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“…The myosin light chains are classified into two types: the alkali (MLCl) and the dinitro-benzoic acid removable light chains (MLC2). The physiological role of alkali MLCs is not well understood, although recent studies have suggested that alkali myosin light chain (MLC1) plays a role in the interaction of the myosin head region with actin (1)(2)(3). It is nevertheless clear that distinct isoforms of MLC1 are present in different muscle types suggesting that they are associated with different contractile properties.…”

Section: Introductionmentioning

confidence: 95%

Characterization of a rat myosin alkali light chain gene expressed in ventricular and slow twitch skeletal muscles

Periasamy

Wadgaonkar

Kumar³

et al. 1989

Nucl Acids Res

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“…Recent structural studies specify more precisely the location of LCI and LC2 on the head close to the neck region [7], the C-terminal part being in interaction with a limited 100-amino-acid-residue segment in the 20 kDa (C) region of S1 [8], while the N-terminus exhibiting a high degree of segmental mobility [9,10] as observed by ~H-NMR spectroscopy is suggested to have the possibility of interacting with elements foreign to the head itself [10,11]. In a general study of the effect of biologically relevant ligands (Me(II) and nucleotides) on the proteolytic susceptibility of various cleavage points in myosin heavy and light chains, a striking ionic strength effect was observed whereby two very fast cleavages in LCI and LC2 (at Lys-7 and Arg-8, respectively) were even faster in the filament when a slower cleavage would be expected [11].…”

Section: Introductionmentioning

confidence: 99%

Proteolysis rates of a myosin heavy chain site with papain Evidence for a combined LC2‐filament‐mediated mechanism

Cardinaud

1987

FEBS Letters

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In striated muscle myosin, a proteolysis site at the 25-50 kDa junction, susceptible in the filament and efficiently protected by nucleotides, is similarly protected when myosin is monomeric. Kinetic studies at low ionic strength show a close relationship between LC2 cleavage or degradation rate and cleavage of the 25-50 kDa heavy chain site. The myosin-[(T)-LC2'] species forms normal reconstituted filaments but its 25-50 kDa site susceptibility is closer to that of monomeric myosin, thus becoming practically ionic strength-independent. In this species the absence of the LC2 N-terminal segment induces a significantly greater susceptibility of the papain-sensitive site in LC1. In an LC2-depleted myosin the 25-50 kDa site susceptibility also becomes ionic strength-independent, however, the cleavage rates are then closer to that of filaments. Susceptibility in HMM and S1 is also much less dependent on ionic strength with rates intermediary between those of filament and monomer. These observations show that the maximum susceptibility to papain of the 25-50 kDa site requires both the integrity of the LC2 light chain and the filament structure and furthermore provide evidence that: (i) the LC2 N-terminus interacts specifically with some part of the filament; (ii) this interaction induces a specific transconformation in a region close to the ATPase active site; (iii) there is an interrelationship between LC 1 and LC2 light chain N-terminal extremities, at least in the filament structure. Studies related in the introductory part were presented at

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Characterization of the actin-binding site on the alkali light chain of myosin

Cited by 62 publications

References 33 publications

Conformational Distributions and Proximity Relationships in the Rigor Complex of Actin and Myosin Subfragment-1

Conformational Distributions and Proximity Relationships in the Rigor Complex of Actin and Myosin Subfragment-1

Characterization of a rat myosin alkali light chain gene expressed in ventricular and slow twitch skeletal muscles

Proteolysis rates of a myosin heavy chain site with papain Evidence for a combined LC2‐filament‐mediated mechanism

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