Stability and substructure of cardiac myosin subfragment 1 and isolation and properties of its heavy-chain subunit

Mathern, Bruce; Burke, M. Desmond

doi:10.1021/bi00352a022

Cited by 6 publications

(3 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Notwithstanding the earlier reports that $1 heavy chains alone can hydrolyze ATP (Sivaramakrishnan & Burke, 1981;Wagner & Giniger, 1981;Mathern & Burke, 1986) the results detailed here implicate LC1 as directly influencing the catalytic activity of $1: actin-activated ATPase was reduced, CaZ+-regulation and ATPdependent actin movement on myosin were suppressed. A recent report on the movement of Dictyostdium discoideum support these observations: overexpressing in a cell line antisense essential light chain mRNA, this Dictyosteliurn cell line expressed < 0.5% of the essential light chain.…”

Section: Discussionsupporting

confidence: 50%

Functional effects of LC1-reassociation with cardiac papain Mg � S1

Margossian

White

Lefford

et al. 1993

J Muscle Res Cell Motil

View full text Add to dashboard Cite

The effect of LC1 on cardiac myosin structure and activity was investigated using as a model S1 prepared by papain digestion in the presence of Mg2+. The resulting S1 contained LC2 but a part of the N-terminal region of LC1 was cleaved. Sequencing the N-terminal part of the band migrating below LC1 on SDS gels revealed it to consist of alternating alanyl and prolyl residues thus establishing LC1 as the origin of this band. However, Western blots did not reveal any LC1 while radioimmunoassays indicated it to be present at the 5% level suggesting the anti-LC1 antibody used in these experiments did not recognize the C-terminal portion of LC1 still attached to Mg.S1. Mixing a 10-15 M excess of isolated light chains with Mg.S1 in the presence of 10 mM ATP, 12 mM MgCl2, 4.7 M NH4Cl allowed LC1 to recombine with LC1-deficient Mg.S1. Equilibrium ultracentrifugation analysis revealed a highly heterogeneous LC1-deficient S1 which upon recombination with intact LC1 became monodisperse as indicated by the superimposition of molecular weight averages all across the centrifuge cell. LC1-deficient Mg.S1 had a Vm of 0.4 s-1, Ka of 30 microM and a Kbind of 28 microM. In the presence of intact LC1, Vm rose to 0.8 s-1 while Ka and Kbind were reduced to 7.5 and 12 microM, respectively. The fourfold decrease in Ka strongly indicated an increased affinity for actin by Mg.S1 in the presence of uncleaved LC1. Also, Ca(2+)-regulation of dog heart myofibrils was suppressed when Ca(2+)-activated MgATPase assays, as a function of Ca2+, were performed in the presence of anti-LC1 antibodies. These observations suggest the presence of intact, uncleaved LC1 in S1 is required for the stability of S1 heavy chains and proper Ca(2+)-regulation.

show abstract

Section: Discussionsupporting

confidence: 50%

Functional effects of LC1-reassociation with cardiac papain Mg � S1

Margossian

White

Lefford

et al. 1993

J Muscle Res Cell Motil

View full text Add to dashboard Cite

show abstract

“…In order to generate S-1 cleaved at the 50/20-kDa junction, S-1 (2 mg/mL) was cligested with trypsin (1 :IO0 w/w) at room temperature for 15 min in the presence of 10 mM MgATP and 0.6 NaCl (Mathern & Burke, 1986;Chen et al, 1987) or with 20 units of Arg-C protease for 2 h . To generate the 25/50-kDa-cleaved S-1, S-1 (2 mg/mL) was digested by trypsin (1 : 10 w/w) in the presence of actin (2 mg/mL) (Chen et al, 1987).…”

Section: Methodsmentioning

confidence: 99%

Interactions of myosin subfragment 1 isozymes with G-actin

Chen¹,

Reisler²

1991

Biochemistry

View full text Add to dashboard Cite

The polymerization of G-actin by myosin subfragment 1 (S-1) isozymes, S-1(A1) and S-1(A2), and their proteolytically cleaved forms was studied by light-scattering, fluorescence, and analytical ultracentrifugation techniques. As reported previously, S-1(A1) polymerized G-actin rapidly while S-1(A2) could hardly promote the assembly reaction (Chaussepied & Kasprzak, 1989a; Chen and Reisler, 1990). This difference between the isozymes of S-1 was traced to the very poor, if any, ability of G-actin-S-1(A2) complexes to nucleate the assembly of actin filaments. The formation of G-actin-S-1(A2) complexes was verified in sedimentation velocity experiments and by fluorescence measurements using pyrene-labeled actin. The G-actin-S-1(A2) complexes supported the growth of actin filaments and accelerated the polymerization of actin in solutions seeded with MgCl2-, KCl-, and S-1(A1)-generated nuclei. The growth rates of actin-S-1(A2) filaments were markedly slower than those for actin-S-1(A1) filaments. Proteolytic cleavage of S-1 isozymes at the 50/20-kDa junction of the heavy chain greatly decreased their binding to G-actin and thus inhibited the polymerization of actin by S-1(A1). These results are discussed in the context of G-actin-S-1 interactions.

show abstract

“…However, a decade later it could be clearly demonstrated, that the pure heavy chain, i.e. without any Alkali light chains revealed both normal Ca2'^ or K+/EDTA activated as well as actin-activated myosin ATPase activities from skeletal (Wagner and Giniger, 1981;Sivaramakrishnan and Burke, 1982) and cardiac muscle (Mathem and Burke, 1986).…”

Section: Esftroductionmentioning

confidence: 99%

Human Atrial Myosin Light Chain 1 Expression Attenuates Heart Failure

Abdelaziz

Pagel

Schlegel

et al.

Sliding Filament Mechanism in Muscle Contraction

View full text Add to dashboard Cite

Most patients with hypertrophic cardiomyopathy and congenital heart diseases express the atrial essential myosin light chains (ALC-1) in their ventricles, replacing the ventricular essential light chains (VLC-1). VLC-1/ALC-1 isoform shift is correlated with increases in cardiac contractile parameters of a transgenic rat model overexpressing hALC-1 in the heart (TGR/hALC-1) compared to normal WKY rats. To investigate, whether the benefical effects of the hALC-1 on cardiac contractility could attenuate contractile failure of the overloaded heart, aortocaval shunt operations of 9-10 weeks old WKY and TGR/hALC-1 were performed. 5 weeks later, both animals groups were sacrificed for analysis of cardiac contraction and transgene expression. Control animals were operated but remained normal body and heart weights. The whole heart contractility parameters were evaluated using the Langendorff heart preparation. Shunt-operated TGR/hALC-1 and WKY rats developed comparable levels of cardiac hypertrophy which was associated with significant reduction of contractile parameters of the Langendorff hearts. However, the decline of cardiac contractility was less pronounced in shunt-operated TGR/hALC-1 compared to shunt-operated WKY. In fact, developed left ventricular pressure as well as maximal velocity of pressure development and relaxation were significantly higher in shunt-operated TGR/hALC-1 as compared to shunt-operated WKY. Expression of hALC-1 was 17 microg/mg whole SDS-protein in control (sham-operated) controls and declined significantly to 14 microg/mg whole SDS-protein in hypertrophied TGR/hALC-1. These results demonstrate that the expression of hALC-1 could have a beneficial effect on the overloaded hypertrophied heart.

show abstract

Stability and substructure of cardiac myosin subfragment 1 and isolation and properties of its heavy-chain subunit

Cited by 6 publications

References 32 publications

Functional effects of LC1-reassociation with cardiac papain Mg � S1

Functional effects of LC1-reassociation with cardiac papain Mg � S1

Interactions of myosin subfragment 1 isozymes with G-actin

Human Atrial Myosin Light Chain 1 Expression Attenuates Heart Failure

Contact Info

Product

Resources

About