Abstract
TMEM16A is the molecular basis of calcium-activated chloride channels and shows Ca2+-dependent gating. It is critical to understand how the Ca2+ 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 Ca2+ sensors which cooperatively couple together in TMEM16A. Our data show that mutations at both Ca2+-sensitive domains, E447Y and E702Q-E705Q, weaken the Ca2+ 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 Ca2+ 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 Ca2+-sensitive domains. We also found that the divalent cations, both Ca2+ and Sr2+, share common mechanism of gating the TMEM16A.
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Acknowledgments
This work was supported by the Natural Science Fund for Distinguished Young Scholars of the Hebei Province of China (Grant No. C2015202340 to HA), the Fund for Outstanding Talents of Hebei Province of China (Grant No. C201400305 to HA), the Natural Science Fund of Hebei Province (Grant No. C2013202244 to YC), and the National Natural Science Fund of China (Grant No. 11247010 to HA, 11175055 to YZ, 11347017 to SZ, 31400711 to YC).
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Han, Y., Zhang, S., Ren, S. et al. Two Ca2+-Binding Sites Cooperatively Couple Together in TMEM16A Channel. J Membrane Biol 249, 57–63 (2016). https://doi.org/10.1007/s00232-015-9846-1
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DOI: https://doi.org/10.1007/s00232-015-9846-1