The structure of a calsequestrin filament reveals mechanisms of familial arrhythmia

• Published in: Nature structural & molecular biology Vol. 27; no. 12; pp. 1142 - 1151
• Main Authors: Titus, Erron W., Deiter, Frederick H., Shi, Chenxu, Wojciak, Julianne, Scheinman, Melvin, Jura, Natalia, Deo, Rahul C.
• Format: Journal Article
• Language: English
• Published: New York Nature Publishing Group US 01.12.2020; Nature Publishing Group
• Subjects: 631/45/535; 631/535/1266; 82/16; 82/80; 82/83; Adult; Arrhythmia; Atomic structure; Binding Sites; Biochemistry; Biological Microscopy; Biomedical and Life Sciences; Calcium; Calcium - chemistry; Calcium - metabolism; Calcium-binding protein; Calcium-Binding Proteins - genetics; Calcium-Binding Proteins - metabolism; Calsequestrin; Calsequestrin - chemistry; Calsequestrin - genetics; Calsequestrin - metabolism; Cardiac arrhythmia; Cloning, Molecular; Crystal defects; Crystal structure; Crystallography, X-Ray; Escherichia coli - genetics; Escherichia coli - metabolism; Female; Filamentation; Filaments; Gene Expression; Genes, Dominant; Genetic Vectors - chemistry; Genetic Vectors - metabolism; Humans; Interfaces; Kinetics; Life Sciences; Male; Membrane Biology; Middle Aged; Mitochondrial Proteins - genetics; Mitochondrial Proteins - metabolism; Models, Molecular; Mutation; Myocardium - metabolism; Myocardium - pathology; Pedigree; Polymers; Protein Binding; Protein Conformation, alpha-Helical; Protein Conformation, beta-Strand; Protein Interaction Domains and Motifs; Protein Multimerization; Protein Structure; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Tachycardia; Tachycardia, Ventricular - genetics; Tachycardia, Ventricular - metabolism; Tachycardia, Ventricular - pathology; Ventricle; Ytterbium
• ISSN: 1545-9993; 1545-9985; 1545-9985
• DOI: 10.1038/s41594-020-0510-9

Mutations in the calcium-binding protein calsequestrin cause the highly lethal familial arrhythmia catecholaminergic polymorphic ventricular tachycardia (CPVT). In vivo, calsequestrin multimerizes into filaments, but there is not yet an atomic-resolution structure of a calsequestrin filament. We report a crystal structure of a human cardiac calsequestrin filament with supporting mutational analysis and in vitro filamentation assays. We identify and characterize a new disease-associated calsequestrin mutation, S173I, that is located at the filament-forming interface, and further show that a previously reported dominant disease mutation, K180R, maps to the same surface. Both mutations disrupt filamentation, suggesting that disease pathology is due to defects in multimer formation. An ytterbium-derivatized structure pinpoints multiple credible calcium sites at filament-forming interfaces, explaining the atomic basis of calsequestrin filamentation in the presence of calcium. Our study thus provides a unifying molecular mechanism through which dominant-acting calsequestrin mutations provoke lethal arrhythmias. A new X-ray crystal structure and supporting biochemical analyses of the human cardiac calsequestrin polymer reveal the basis of filament assembly and map disease-associated mutations to the multimerization interface.