Normal Mode Analysis of RyR2, a Cardiac Ca²⁺ Channel

Background: The cardiac ryanodine receptor RyR2 is a calcium release channel present in the cardiac muscle cells, which plays a major role in the regulation of Ca²⁺ homeostasis in the heart. We discovered a novel RyR2 missense mutation, G3118R, in a large family presenting with cardiac arrest phenotype and a unique autosomal recessive inheritance. Functionally, G3118R causes suppression of function of the channel, which is by far less described mechanism caused by most RyR2 mutations.

Methods: Normal Mode Analysis (NMA) was used to study the changes in the stability and the flexibility of RyR2 protein and to develop a computational tool to predict unknown mutations` pathogenicity.

Results: We found that G3118R mutation increases protein instability and flexibility in an allosteric and a dose-dependent manner. Using a dataset of 173 RyR2 verified mutations we were able to refine thermodynamic differences between the pathological and the healthy variants. This enabled us to propose a predictive tool capable of an accurate classification of any unknown mutation in RyR2 with 0.88 sensitivity and 0.97 specificity values.

Conclusion: Structural characterization of G3118R mutation explains its unusual recessive inheritance. Predictive method based on a modification of NMA with maschine learning approach allows a good classification of RyR2 mutations and could serve a basis for using a similar approach on other ion channels.