Size and Charge Requirements for Kinetic Modulation and Actin Binding by Alkali 1-type Myosin Essential Light Chains

Timson, David J.; Trayer, Hylary R.; Smith, K. John; Trayer, Ian P.

doi:10.1074/jbc.274.26.18271

Cited by 44 publications

(43 citation statements)

References 34 publications

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“…Therefore, it is possible that in those species in which MLC1F has a greater molecular mass and, hence, lower electrophoretic mobility, due in part to a greater number of A-P repeats, there is greater modulation of cross-bridge kinetics by MLC1F. Results from in vitro experiments indicate that there is a direct inverse correlation between the affinity of MLC1F for actin and the rate constant for actomyosin ATPase activity (41). This could translate into greater modulation of cross-bridge kinetics by MLC1F in those species with a greater number of A-P repeats, specifically slowing down cross-bridge kinetics in large animals and thereby accommodating slower limb kinematics during locomotion (14).…”

Section: Discussionmentioning

confidence: 75%

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Variations in apparent mass of mammalian fast-type myosin light chains correlate with species body size, from shrew to elephant

Bicer¹,

Reiser²

2007

American Journal of Physiology-Regulatory, Integrative and Comp

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Bicer S, Reiser PJ. Variations in apparent mass of mammalian fast-type myosin light chains correlate with species body size, from shrew to elephant. Am J Physiol Regul Integr Comp Physiol 292: R527-R534, 2007. First published August 10, 2006; doi:10.1152/ajpregu.00098.2006.-A recent study (Bicer S and Reiser PJ. J Muscle Res Cell Motil 25: 623-633, 2004) suggested considerable variation in the apparent molecular mass (M a), deduced from electrophoretic mobility, in fast-type myosin light chains (MLCF), especially MLC1F, among mammalian species. Furthermore, there was an indication that MLC1F M a generally correlates with species body mass, over an ϳ4,000-fold range in body mass. The results also suggested that M a of other low-molecular-weight myofibrillar proteins is less variable and not as strongly correlated with body mass among the same species. The objective of this study was to test the hypotheses that the M a of MLCs does, in fact, vary and correlate with species body mass. The electrophoretic mobilities of MLCF isoforms from 19 species, varying in size ϳ500,000-fold, were quantitated. The results confirm that the M a of MLC1F and MLC2F vary significantly among mammals, spanning a very broad range in body mass; the MLC1F M a varies more than that of other lowmolecular-weight myofibrillar proteins; and there is a significant correlation between species body mass and MLC1F M a. Differences in MLC1F M a among five species can be accounted for by differences in the reported amino acid sequence, especially the length of a common polyalanine region near the NH 2-terminal actin-binding site. The possibility that the differences in MLC1F sequence among mammalian species, in and adjacent to the actin-binding region, are related to differences in modulation of cross-bridge kinetics in species with diverse locomotion kinetics is discussed. isoforms; contractile proteins; myofibrillar proteins; body mass; scaling NEARLY FORTY YEARS AGO, Barany (6) reported that differences in maximal shortening velocity (V max ) among skeletal muscles of various species are strongly correlated with actomyosin ATPase activity. Fast-type and slow-type isoforms of myosin heavy chain (MHC), as well as isoforms of most of the other proteins of sarcomeric thick and thin filaments, are expressed in skeletal, cardiac, and smooth muscle. The results of a large number of studies, reviewed by Moss et al. (27) and by Schiaffino and Reggiani (35), have since convincingly demonstrated that the subunit of the hexameric myosin molecule that is primarily responsible for this correlation is MHC. That is, there is a general consensus that MHC subunits of myosin are the primary determinants of muscle shortening velocity and power output, because different isoforms of MHC are associated with variation in actomyosin cross-bridge kinetics and, therefore, in contraction kinetics.Each myosin molecule is composed of two MHCs and four myosin light chains (MLCs). Two isoforms of regulatory MLCs are expressed in skeletal muscle, fast-type and slowtype MLC2 ...

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Section: Discussionmentioning

confidence: 75%

“…is an actin-binding domain (41). The first four amino acids at this site are alanine-proline-lysine-lysine (some cardiac MLC1 sequences start with proline, instead of alanine).…”

Section: Discussionmentioning

confidence: 99%

Variations in apparent mass of mammalian fast-type myosin light chains correlate with species body size, from shrew to elephant

Bicer¹,

Reiser²

2007

American Journal of Physiology-Regulatory, Integrative and Comp

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“…In human cardiac muscle, both ventricular (ELC1v) and atrial (ELC1a) ELC isoforms have N-terminal extensions of approximately the same length as their A1-type counterparts in skeletal muscle. The atrial isoform N-terminal extension has been shown to interact with actin (13), and the ventricular isoform extension is generally assumed to do so as well.…”

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confidence: 99%

The Essential Light Chain N-terminal Extension Alters Force and Fiber Kinetics in Mouse Cardiac Muscle

Miller

Palmer

Ruch

et al. 2005

Journal of Biological Chemistry

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The functional significance of the actin-binding region at the N terminus of the cardiac myosin essential light chain (ELC) remains elusive. In a previous experiment, the endogenous ventricular ELC was replaced with a protein containing a 10-amino acid deletion at positions 5-14 (ELC1v⌬5-14, referred to as 1v⌬5-14), a region that interacts with actin (Sanbe, A., Gulick, J., Fewell, J., and Robbins, J. (2001) J. Biol. Chem. 276, 32682-32686). 1v⌬5-14 mice showed no discernable mutant phenotype in skinned ventricular strips. However, because the myofilament lattice swells upon skinning, the mutant phenotype may have been concealed by the inability of the ELC to reach the actin-binding site. Using the same mouse model, we repeated earlier measurements and performed additional experiments on skinned strips osmotically compressed to the intact lattice spacing as determined by x-ray diffraction. 1v⌬5-14 mice exhibited decreased maximum isometric tension without a change in calcium sensitivity. The decreased force was most evident in 5-6-month-old mice compared with 13-15-month-old mice and may account for the greater ventricular wall thickness in young 1v⌬5-14 mice compared with age-matched controls. No differences were observed in unloaded shortening velocity at maximum calcium activation. However, 1v⌬5-14 mice exhibited a significant difference in the frequency at which minimum complex modulus amplitude occurred, indicating a change in cross-bridge kinetics. We hypothesize that the ELC N-terminal extension interaction with actin inhibits the reversal of the power stroke, thereby increasing isometric force. Our results strongly suggest that an interaction between residues 5-14 of the ELC N terminus and the C-terminal residues of actin enhances cardiac performance.

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“…However ELC1 exhibited a slightly lower actin-dependent ATPase activity than most other mutants. The long arm in the N-terminus of ELC1 would exert an inhibitory effect on the ATP±actin±myosin interaction, possibly like the N-terminals of alkali 1-type essential light chains, which modulate the motor function of striated muscle myosin [40].…”

Section: Discussionmentioning

confidence: 99%

Functional regions in the essential light chain of smooth muscle myosin as revealed by the mutagenesis approach

Quevillon‐Chéruel

Janmot

Nozais

et al. 2000

European Journal of Biochemistry

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The endogenous essential light chain (LC17) of myosin from intestine smooth muscle was replaced with mutated essential light chains prepared using recombinant techniques. Complete exchange was observed with histidinetagged derivatives of LC17a, LC17b and E122A-LC17a (LC17a and LC17b are the usual constituants of smooth muscle myosin), with small changes in the ATPase activity of reconstituted myosins. Much less exchange was observed with the light-chain derivative lacking the last 12 amino acid residues, demonstrating the importance of this segment, which may act as one arm of a pair of pincers to bind the myosin heavy chain.Keywords: isoforms; mutants; myosin light chains; site-directed mutagenesis; smooth muscle.Myosin II is a major contractile protein composed of two heavy chains (< 200 kDa each) and two pairs of light chains (< 20 kDa each). One pair of light chains is described as regulatory (20 kDa) and the other as essential (17 kDa), based on their distinctive chemical and functional features. In smooth muscle myosin, the two 20-kDa regulatory chains (LC20) can be phosphorylated and phosphorylation generates high levels of actin-activated ATPase activity and actin motility. The other pair of myosin light chains consists of the two 17-kDa essential chains (LC17), the functional significance of which is unclear [1]. The regulatory and essential light chains are bound to an 8-nm stretch of myosin heavy chain, mostly a helix. This complex constitutes a regulatory domain [2,3] and is thought to act as a lever arm during force production by muscle motor proteins [4].The essential light chain, LC17, has two isoforms, the ratio of which depends on the tissue. The difference between these two species is five amino acid substitutions in the nine C-terminal residues (Fig. 1). In particular, one isoform, LC17a, has a charged glutamic acid residue at position 142, whereas the other, LC17b, has an alanine residue in the corresponding position [5]. An inverse correlation has been found between relative LC17b content and the maximal shortening velocity of skinned smooth muscle fibers [6] but this result is controversial [1]. Recently, weak but significant LC17 isoform-specific effects on the mechanical properties of smooth muscle cells [7] and strips [8] have been shown. In addition, the two isoforms have different subcellular distributions suggesting that they may have different functions [9].It has been shown that substitution mutations in the essential light chain of nonmuscle myosin from Dictyostelium may lead to decreases in actin-activated ATPase activity and motor function, as assessed by an in vitro motility assay [10].Katoh and co-workers [11,12] recently reported an efficient method for essential light chain exchange in smooth muscle myosin. We used this method to exchange LC17a, LC17b and mutated essential light chains with endogenous light chains from rabbit small-intestine myosin. The recombinant proteins were prepared ( Fig. 1; ELC1±6) with a histidine tag on their N-terminus to facilitate purification. In...

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Size and Charge Requirements for Kinetic Modulation and Actin Binding by Alkali 1-type Myosin Essential Light Chains

Abstract: The alkali 1-type isoforms of myosin essential light chains from vertebrate striated muscles have an additional 40 or so amino acids at their N terminus compared with the alkali 2-type. Consequently two light chain isoenzymes of myosin subfragment-1 can be isolated.

Cited by 44 publications

References 34 publications

Variations in apparent mass of mammalian fast-type myosin light chains correlate with species body size, from shrew to elephant

Variations in apparent mass of mammalian fast-type myosin light chains correlate with species body size, from shrew to elephant

The Essential Light Chain N-terminal Extension Alters Force and Fiber Kinetics in Mouse Cardiac Muscle

Functional regions in the essential light chain of smooth muscle myosin as revealed by the mutagenesis approach

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