posted on 2021-06-01, 16:05authored byCarmen Suay-Corredera, Maria Rosaria Pricolo, Diana Velázquez-Carreras, Divya Pathak, Neha Nandwani, Carolina Pimenta-Lopes, David Sánchez-Ortiz, Iñigo Urrutia-Irazabal, Silvia Vilches, Fernando Dominguez, Giulia Frisso, Lorenzo Monserrat, Pablo García-Pavía, David de Sancho, James A. Spudich, Kathleen M. Ruppel, Elías Herrero-Galán, Jorge Alegre-Cebollada
Hypertrophic
cardiomyopathy (HCM) is a disease of the myocardium
caused by mutations in sarcomeric proteins with mechanical roles,
such as the molecular motor myosin. Around half of the HCM-causing
genetic variants target contraction modulator cardiac myosin-binding
protein C (cMyBP-C), although the underlying pathogenic mechanisms
remain unclear since many of these mutations cause no alterations
in protein structure and stability. As an alternative pathomechanism,
here we have examined whether pathogenic mutations perturb the nanomechanics
of cMyBP-C, which would compromise its modulatory mechanical tethers
across sliding actomyosin filaments. Using single-molecule atomic
force spectroscopy, we have quantified mechanical folding and unfolding
transitions in cMyBP-C domains targeted by HCM mutations that do not
induce RNA splicing alterations or protein thermodynamic destabilization.
Our results show that domains containing mutation R495W are mechanically
weaker than wild-type at forces below 40 pN and that R502Q mutant
domains fold faster than wild-type. None of these alterations are
found in control, nonpathogenic variants, suggesting that nanomechanical
phenotypes induced by pathogenic cMyBP-C mutations contribute to HCM
development. We propose that mutation-induced nanomechanical alterations
may be common in mechanical proteins involved in human pathologies.