Removal of the cardiac myosin regulatory light chain increases isometric force production
AUTOR(ES)
Pant, Kiran
FONTE
The Federation of American Societies for Experimental Biology
RESUMO
The myosin neck, which is supported by the interactions between light chains and the underlying α-helical heavy chain, is thought to act as a lever arm to amplify movements originating in the globular motor domain. Here, we studied the role of the cardiac myosin regulatory light chains (RLCs) in the capacity of myosin to produce force using a novel optical-trap-based isometric force in vitro motility assay. We measured the isometric force and actin filament velocity for native porcine cardiac (PC) myosin, RLC-depleted PC (PCdepl) myosin, and PC myosin reconstituted with recombinant bacterially expressed human cardiac RLC (PCrecon). RLC depletion reduced unloaded actin filament velocity by 58% and enhanced the myosin-based isometric force ∼2-fold. No significant change between PC and PCdepl preparations was observed in the maximal rate of actin-activated myosin ATPase activity. Reconstitution of PCdepl myosin with human RLC partially restored the velocity and force levels to near untreated values. The reduction in unloaded velocity after RLC extraction is consistent with the myosin neck acting as a lever, while the enhancement in isometric force can be directly related to enhancement of unitary force. The force data are consistent with a model in which the neck region behaves as a cantilevered beam.—Pant, K., Watt, J., Greenberg, M., Jones, M., Szczesna-Cordary, D., Moore, J. R. Removal of the cardiac myosin regulatory light chain increases isometric force production.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2747675Documentos Relacionados
- The essential light chain is required for full force production by skeletal muscle myosin.
- Regulatory myosin light-chain genes of Caenorhabditis elegans.
- The molecular effects of skeletal muscle myosin regulatory light chain phosphorylation
- Purification of myosin light chain kinase from bovine cardiac muscle.
- Effect of metabolic inhibition on intracellular Ca2+, phosphorylation of myosin regulatory light chain and force in rat smooth muscle.