Properties of Calmodulin Binding to NaV1.2 IQ Motif and Its Autism-Associated Mutation R1902C |
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Authors: | Jia Wanying Liu Junyan Yu Zhiyi Zhang Xiaohong Xu Xiaoxue Wang Yuting Gao Qinghua Feng Rui Wan Yujun Xu Jianjun Minobe Etsuko Kameyama Masaki Wang Wuyang Guo Feng |
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Institution: | 1.Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, 110122, China ;2.Division of Medicinal Chemistry, School of Pharmaceutical Sciences, Shandong University, Jinan, 250012, China ;3.Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, 890-8544, Japan ;4.Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, 221004, China ; |
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Abstract: | Voltage-gated sodium channels (VGSCs) are fundamental to the initiation and propagation of action potentials in excitable cells. Ca2+/calmodulin (CaM) binds to VGSC type II (NaV1.2) isoleucine and glutamine (IQ) motif. An autism-associated mutation in NaV1.2 IQ motif, Arg1902Cys (R1902C), has been reported to affect the combination between CaM and the IQ motif compared to that of the wild type IQ motif. However, the detailed properties for the Ca2+-regulated binding of CaM to NaV1.2 IQ (1901Lys-1927Lys, IQwt) and mutant IQ motif (IQR1902C) remains unclear. Here, the binding ability of CaM and CaM's constituent proteins including N- and C lobe to the IQ motif of NaV1.2 and its mutant was investigated by protein pull-down experiments. We discovered that the combination between CaM and the IQ motif was U-shaped with the highest at Ca2+] ≈ free and the lowest at 100 nM Ca2+]. In the IQR1902C mutant, Ca2+-dependence of CaM binding was nearly lost. Consequently, the binding of CaM to IQR1902C at 100 and 500 nM Ca2+] was increased compared to that of IQwt. Both N- and C lobe of CaM could bind with NaV1.2 IQ motif and IQR1902C mutant, with the major effect of C lobe. Furthermore, CaMKII had no impact on the binding between CaM and NaV1.2 IQ motif. This research offers novel insight to the regulation of NaV1.2 IQwt and IQR1902C motif, an autism-associated mutation, by CaM. |
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