RYR1 mutations in congenital myopathy altered myosin post-translational modifications and resulted in a faster ATP turnover time of myosin heads in the disordered-relaxed conformation.
Case-Control (n=15)
RYR1 mutations in congenital myopathy are associated with secondary negative consequences on myosin structure and function, including altered post-translational modifications and faster ATP turnover.
AIM: Conditions related to mutations in the gene encoding the skeletal muscle ryanodine receptor 1 (RYR1) are genetic muscle disorders and include congenital myopathies with permanent weakness, as well as episodic phenotypes such as rhabdomyolysis/myalgia. Although RYR1 dysfunction is the primary mechanism in RYR1-related disorders, other downstream pathogenic events are less well understood and may include a secondary remodeling of major contractile proteins. Hence, in the present study, we aimed to investigate whether congenital myopathy-related RYR1 mutations alter the regulation of the most abundant contractile protein, myosin. METHODS: We used skeletal muscle tissues from five patients with RYR1-related congenital myopathy and compared those with five controls and five patients with RYR1-related rhabdomyolysis/myalgia. We then defined post-translational modifications on myosin heavy chains (MyHCs) using LC/MS. In parallel, we determined myosin relaxed states using Mant-ATP chase experiments and performed molecular dynamics (MD) simulations. RESULTS: LC/MS revealed two additional phosphorylations (Thr1309-P and Ser1362-P) and one acetylation (Lys1410-Ac) on the β/slow MyHC of patients with congenital myopathy. This method also identified six acetylations that were lacking on MyHC type IIa of these patients (Lys35-Ac, Lys663-Ac, Lys763-Ac, Lys1171-Ac, Lys1360-Ac, and Lys1733-Ac). MD simulations suggest that modifying myosin Ser1362 impacts the protein structure and dynamics. Finally, Mant-ATP chase experiments showed a faster ATP turnover time of myosin heads in the disordered-relaxed conformation. CONCLUSIONS: Altogether, our results suggest that RYR1 mutations have secondary negative consequences on myosin structure and function, likely contributing to the congenital myopathic phenotype.
Sonne et al. (Mon,) conducted a case-control in RYR1-related congenital myopathy (n=15). RYR1 mutations vs. Controls and RYR1-related rhabdomyolysis/myalgia was evaluated on Post-translational modifications on myosin heavy chains and ATP turnover time. RYR1 mutations in congenital myopathy altered myosin post-translational modifications and resulted in a faster ATP turnover time of myosin heads in the disordered-relaxed conformation.