Crystallographic Investigation of Several Malignant Hyperthermia and CPVT Mutations in Ryanodine Receptors

Abstract

Mutations in the Ryanodine Receptor (RYR) are known to underlie many genetic diseases. In particular, the skeletal muscle isoform (RyR1) is involved in malignant hyperthermia (MH) and central core disease (CCD), whereas mutations in the cardiac isoform (RyR2) are known to cause catecholaminergic polymorphic ventricular tachycardia (CPVT) and arrhythmogenic right ventricular dysplasia (ARVD). Despite an extensive analysis of disease mutations on the functional level, very little is known about the structural changes induced by the mutations. Here we analyze the structures and stability of over 10 different disease mutants. We present crystal structures of mutant versions of the RyR1 N-terminal disease hot spot, encoding three domains, and of the RyR2 N-terminal domain, all solved between 2.0 and 3.0 Angstrom, and compare them to the wild type structures. The observed effects on structure and stability differ substantially among the mutants. Whereas some cause a major destabilization of the overall fold, others mainly cause relative domain-domain movements or confer large conformational changes within individual domains. We discuss the likely implications of the disease mutations on the overall structure and gating properties of the intact RyR.