title: Two Ca(2+)-Binding Sites Cooperatively Couple Together in TMEM16A Channel.
abstract: TMEM16A is the molecular basis of calcium-activated chloride channels and shows Ca(2+)-dependent gating. It is critical to understand how the Ca(2+) sensors dynamically control the gate of TMEM16A. However, the detailed mechanism by which the calcium ions bind and open the channel is still obscure. In this study, the authors confirmed that there are two Ca(2+) sensors which cooperatively couple together in TMEM16A. Our data show that mutations at both Ca(2+)-sensitive domains, E447Y and E702Q-E705Q, weaken the Ca(2+) affinity for TMEM16A channel. The EC50 for WT, E447Y, and E702Q-E705Q are 0.53 ± 0.11, 14.5 ± 0.3, and 26.5 ± 3.6 μM, respectively. The triple mutation, including both of the Ca(2+) sensors, E447Y-E702Q-E705Q, with EC50 as 55.6 ± 5.1 μM, results in much further right-shifted dose response curve than the single sensor's mutations (E447Y, E702Q-E705Q) do, which indicates that there is a cooperation between the two Ca(2+)-sensitive domains. We also found that the divalent cations, both Ca(2+) and Sr(2+), share common mechanism of gating the TMEM16A.
authors.affiliation: Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, 300401, Tianjin, People's Republic of China.
authors.forename: Yuebin
authors.initials: Y
authors.lastname: Han
authors.affiliation: Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, 300401, Tianjin, People's Republic of China.
authors.forename: Suhua
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, 300401, Tianjin, People's Republic of China.
authors.forename: Shuxi
authors.initials: S
authors.lastname: Ren
authors.affiliation: Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, 300401, Tianjin, People's Republic of China.
authors.forename: Yafei
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, 300401, Tianjin, People's Republic of China.
authors.forename: Hongbo
authors.initials: H
authors.lastname: Yuan
authors.affiliation: Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, 300401, Tianjin, People's Republic of China.
authors.forename: Ran
authors.initials: R
authors.lastname: Chai
authors.affiliation: Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, 300401, Tianjin, People's Republic of China.
authors.forename: Hui
authors.initials: H
authors.lastname: Yu
authors.affiliation: Key Laboratory of Neural and Vascular Biology, Ministry of Education, The Key Laboratory of Pharmacology and Toxicology for New Drug, Hebei Province, Department of Pharmacology, Hebei Medical University, 050017, Shijiazhuang, People's Republic of China.
authors.forename: Hailin
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, 300401, Tianjin, People's Republic of China. zhany@hebut.edu.cn.
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhan
authors.affiliation: Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, 300401, Tianjin, People's Republic of China. hailong_an@hebut.edu.cn.
authors.forename: Hailong
authors.initials: H
authors.lastname: An
mesh_terms: D000818:Animals; D000075369:Anoctamin-1; D001665:Binding Sites; D002118:Calcium / Q000737:chemistry* / Q000378:metabolism; D002413:Cations, Divalent / Q000737:chemistry / Q000378:metabolism; D002460:Cell Line; D018118:Chloride Channels / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D015640:Ion Channel Gating; D051379:Mice; D009154:Mutation; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs / Q000235:genetics
chemical_list: C531181:ANO1 protein, mouse; D000075369:Anoctamin-1; D002413:Cations, Divalent; D018118:Chloride Channels; D002118:Calcium
keywords: Ca2+-binding site; Calcium-dependent gating; Cooperative activation; Divalent cations; TMEM16A channel