Modeling Poly-Lysine Interactions with Mutant and Wild Type Cardiac Myosin Subfragment-2
Familial hypertrophic cardiomyopathy-causing mutations in β-cardiac myosin subfragment-2 destabilize the coiled coil structure which might be related to their phenotypes. Using a synthetic peptide model of this coiled coil region, it was found that the stability of the myosin coiled coil was inversely correlated with the phenotypic severity of the disease-causing mutations. Stability of the coiled coil was measured by luminescence resonance energy transfer in which some of the mutant and wildtype peptides were labeled with donor probes and others were labeled with acceptor probes so the fraction of peptides in a coiled coil could be determined. Similar results were obtained with dynamics simulations of the mutant and wildtype peptides. It was further found that the instability of the coiled coil caused by the mutations could be partially reversed by the addition of poly-D-lysine. Both molecular mechanics and dynamics simulations of the poly-lysine binding to the coiled coil peptide indicated that the poly-lysine of an appropriate length could wrap around the coiled coil by interacting with negatively-charged glutamate side-chains. Further modifications of the sequence of the poly-lysine were found to improve the interaction energy between the complex which may result in increased stabilization of the myosin coiled. These results suggest that it may be possible to design peptides that can counteract the destabilizing effects of specific disease-causing mutations. (Supported by NSF 082736 ARRA.)