7zrp
2.65 Angstrom crystal structure of Ca/CaM:CaMKIIdelta peptide complex
Structural highlights
DiseaseCALM1_HUMAN The disease is caused by mutations affecting the gene represented in this entry. Mutations in CALM1 are the cause of CPVT4. The disease is caused by mutations affecting the gene represented in this entry. Mutations in CALM1 are the cause of LQT14. FunctionCALM1_HUMAN Calmodulin mediates the control of a large number of enzymes, ion channels, aquaporins and other proteins through calcium-binding. Among the enzymes to be stimulated by the calmodulin-calcium complex are a number of protein kinases and phosphatases. Together with CCP110 and centrin, is involved in a genetic pathway that regulates the centrosome cycle and progression through cytokinesis (PubMed:16760425). Mediates calcium-dependent inactivation of CACNA1C (PubMed:26969752). Positively regulates calcium-activated potassium channel activity of KCNN2 (PubMed:27165696).[1] [2] [3] [4] Publication Abstract from PubMedLong QT syndrome (LQTS) is a human inherited heart condition that can cause life-threatening arrhythmia including sudden cardiac death. Mutations in the ubiquitous Ca(2+)-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 CaMKIIdelta 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 CaMKIIdelta peptide, which shows significant structural differences, compared to the wild-type complex. Furthermore, we demonstrate that the E140G mutation significantly disrupted Ca(v)1.2 Ca(2+)/CaM-dependent inactivation, while cardiac ryanodine receptor (RyR2) activity remained unaffected. In addition, we show that the LQTS-associated mutation alters CaM's Ca(2+) binding characteristics, secondary structure content and interaction with key partners involved in excitation-contraction coupling (CaMKIIdelta, Ca(v)1.2, RyR2). In conclusion, LQTS-associated CaM mutation E140G severely impacts the structure-function relationship of CaM and its regulation of CaMKIIdelta and Ca(v)1.2. This provides a crucial insight into the molecular factors contributing to CaM-mediated arrhythmias with a central role for CaMKIIdelta. Calmodulin variant E140G associated with long QT syndrome impairs CaMKIIdelta autophosphorylation and L-type calcium channel (Ca(v)1.2) inactivation.,Prakash O, Gupta N, Milburn A, McCormick L, Deugi V, Fisch P, Wyles J, Thomas NL, Antonyuk S, Dart C, Helassa N J Biol Chem. 2022 Dec 7:102777. doi: 10.1016/j.jbc.2022.102777. PMID:36496072[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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