The LQT-associated calmodulin mutant E141G induces disturbed Ca2+-dependent binding and a vibration-like gating mode of the CaV1.2 channel.

In this study, by utilizing a semiquantitative pull-down assay, we explored the interaction of CaM-E141G with CaM-binding peptide fragments of CaV1.2. We also investigated its electrophysiological effects on CaV1.2 channel activity with the patch clamp technique. We found that the maximum binding (Bmax) of CaM-E141G to the proximal C-terminal region, PreIQ-IQ, PreIQ, IQ and NT (a N-terminal peptide) were all decreased (by 17.71-59.26%), compared to that of wild type CaM (CaM-WT). In particular, the Ca2+-dependent increase in the binding affinity was changed to a Ca2+-dependent decrease in the presence of a combination of CaM-E141G and PreIQ or NT. Functionally, CaM-E141G attenuated the inhibitory effects of Ca2+/CaM on the activity of CaV1.2 (CDI) by 55.6% at 500 nM Ca2+. Meanwhile the mean open time of CaV1.2 gating was elongated and the number of blank traces with no channel opening was significantly decreased. These results support the view that CaM-E141G shows disturbed binding with the cardiac CaV1.2 channel and induces a vibration-like gating mode, which may result in the dysfunction of CaV1.2 and thereby the development of LQTS. The present study, for the first time, investigated the detailed binding properties and single channel gating mode induced by the interaction of CaM-E141G with CaV1.2. PMID: 32186935 [PubMed - as supplied by publisher]
Source: Am J Physiol Cell Ph... - Category: Cytology Authors: Tags: Am J Physiol Cell Physiol Source Type: research