| Structural highlights
Disease
[CASQ2_HUMAN] Defects in CASQ2 are the cause of catecholaminergic polymorphic ventricular tachycardia type 2 (CPVT2) [MIM:611938]; also known as stress-induced polymorphic ventricular tachycardia (VTSIP). CPVT2 is an autosomal recessive form of arrhythmogenic disorder characterized by stress-induced, bidirectional ventricular tachycardia that may degenerate into cardiac arrest and cause sudden death.[1] [2] [3] [4] [5]
Function
[CASQ2_HUMAN] Calsequestrin is a high-capacity, moderate affinity, calcium-binding protein and thus acts as an internal calcium store in muscle. The release of calcium bound to calsequestrin through a calcium release channel triggers muscle contraction. The skeletal muscle isoform (CASQ1) binds around 80 Ca(2+) ions, while the cardiac isoform (CASQ2) binds approximately 60 Ca(2+) ions.[6]
Publication Abstract from PubMed
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.
The structure of a calsequestrin filament reveals mechanisms of familial arrhythmia.,Titus EW, Deiter FH, Shi C, Wojciak J, Scheinman M, Jura N, Deo RC Nat Struct Mol Biol. 2020 Oct 12. pii: 10.1038/s41594-020-0510-9. doi:, 10.1038/s41594-020-0510-9. PMID:33046906[7]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Kim E, Youn B, Kemper L, Campbell C, Milting H, Varsanyi M, Kang C. Characterization of human cardiac calsequestrin and its deleterious mutants. J Mol Biol. 2007 Nov 2;373(4):1047-57. Epub 2007 Aug 29. PMID:17881003 doi:10.1016/j.jmb.2007.08.055
- ↑ Lahat H, Pras E, Olender T, Avidan N, Ben-Asher E, Man O, Levy-Nissenbaum E, Khoury A, Lorber A, Goldman B, Lancet D, Eldar M. A missense mutation in a highly conserved region of CASQ2 is associated with autosomal recessive catecholamine-induced polymorphic ventricular tachycardia in Bedouin families from Israel. Am J Hum Genet. 2001 Dec;69(6):1378-84. Epub 2001 Oct 25. PMID:11704930 doi:S0002-9297(07)61266-X
- ↑ Houle TD, Ram ML, Cala SE. Calsequestrin mutant D307H exhibits depressed binding to its protein targets and a depressed response to calcium. Cardiovasc Res. 2004 Nov 1;64(2):227-33. PMID:15485681 doi:S0008-6363(04)00394-3
- ↑ di Barletta MR, Viatchenko-Karpinski S, Nori A, Memmi M, Terentyev D, Turcato F, Valle G, Rizzi N, Napolitano C, Gyorke S, Volpe P, Priori SG. Clinical phenotype and functional characterization of CASQ2 mutations associated with catecholaminergic polymorphic ventricular tachycardia. Circulation. 2006 Sep 5;114(10):1012-9. Epub 2006 Aug 14. PMID:16908766 doi:CIRCULATIONAHA.106.623793
- ↑ Valle G, Galla D, Nori A, Priori SG, Gyorke S, de Filippis V, Volpe P. Catecholaminergic polymorphic ventricular tachycardia-related mutations R33Q and L167H alter calcium sensitivity of human cardiac calsequestrin. Biochem J. 2008 Jul 15;413(2):291-303. PMID:18399795 doi:BJ20080163
- ↑ Kim E, Youn B, Kemper L, Campbell C, Milting H, Varsanyi M, Kang C. Characterization of human cardiac calsequestrin and its deleterious mutants. J Mol Biol. 2007 Nov 2;373(4):1047-57. Epub 2007 Aug 29. PMID:17881003 doi:10.1016/j.jmb.2007.08.055
- ↑ Titus EW, Deiter FH, Shi C, Wojciak J, Scheinman M, Jura N, Deo RC. The structure of a calsequestrin filament reveals mechanisms of familial arrhythmia. Nat Struct Mol Biol. 2020 Oct 12. pii: 10.1038/s41594-020-0510-9. doi:, 10.1038/s41594-020-0510-9. PMID:33046906 doi:http://dx.doi.org/10.1038/s41594-020-0510-9
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