Calmodulin variant E140G associated with long QT syndrome impairs CaMKIIδ autophosphorylation and L-type calcium channel inactivation

Prakash, Ohm, Gupta, Nitika, Milburn, Amy, McCormick, Liam, Deugi, Vishvangi, Fisch, Pauline, Wyles, Jacob, Thomas, Nia ORCID: https://orcid.org/0000-0001-8822-8576, Antonyuk, Svetlana, Dart, Caroline and Helassa, Nordine 2022. Calmodulin variant E140G associated with long QT syndrome impairs CaMKIIδ autophosphorylation and L-type calcium channel inactivation. Journal of Biological Chemistry 299 (1) , 102777. 10.1016/j.jbc.2022.102777

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Abstract

Long QT syndrome (LQTS) is a human inherited heart condition that can cause life-threatening arrhythmia including sudden cardiac death. Mutations in the ubiquitous Ca2+-sensing protein calmodulin (CaM) are associated with LQTS, but the molecular mechanism by which these mutations lead to irregular heartbeats is not fully understood. Here, we use a multidisciplinary approach including protein biophysics, structural biology, confocal imaging, and patch-clamp electrophysiology to determine the effect of the disease-associated CaM mutation E140G on CaM structure and function. We present novel data showing that mutant-regulated CaMKIIδ kinase activity is impaired with a significant reduction in enzyme autophosphorylation rate. We report the first high-resolution crystal structure of a LQTS-associated CaM variant in complex with the CaMKIIδ peptide, which shows significant structural differences, compared to the WT complex. Furthermore, we demonstrate that the E140G mutation significantly disrupted Cav1.2 Ca2+/CaM-dependent inactivation, while cardiac ryanodine receptor (RyR2) activity remained unaffected. In addition, we show that the LQTS-associated mutation alters CaM’s Ca2+-binding characteristics, secondary structure content, and interaction with key partners involved in excitation-contraction coupling (CaMKIIδ, Cav1.2, RyR2). In conclusion, LQTS-associated CaM mutation E140G severely impacts the structure-function relationship of CaM and its regulation of CaMKIIδ and Cav1.2. This provides a crucial insight into the molecular factors contributing to CaM-mediated arrhythmias with a central role for CaMKIIδ.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Schools > Pharmacy
Additional Information:	License information from Publisher: LICENSE 1: URL: http://creativecommons.org/licenses/by/4.0/, Start Date: 2022-12-06
Publisher:	American Society for Biochemistry and Molecular Biology
ISSN:	0021-9258
Date of First Compliant Deposit:	4 January 2023
Date of Acceptance:	29 November 2022
Last Modified:	05 May 2023 22:32
URI:	https://orca.cardiff.ac.uk/id/eprint/155385

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