Voltage-gating and cytosolic Ca <sup>2+</sup> activation mechanisms of <i>Arabidopsis</i> two-pore channel AtTPC1
Fan Ye, Lingyi Xu, Xiaoxiao Li, Weizhong Zeng, Ninghai Gan, Cheng Zhao, Wei Yang, Youxing Jiang, Jiangtao Guo
Abstract
Significance How membrane potential drives conformational change at the voltage-sensing domain (VSD) and regulates channel gating is a central theme for voltage-gated ion channels. To elucidate voltage-gating mechanisms, one needs to capture VSD structures in both the activated state and resting state, the latter of which is difficult to obtain because VSDs tend to adopt an activated state in the absence of membrane potential in most in vitro experiments. Here, we determined AtTPC1 structures in a closed conformation with a resting VSDII and an unbound EF-hand domain and in a partially open conformation with an activated VSDII and a Ca 2+ -activated EF-hand domain, elucidating the structural mechanisms of voltage gating, cytosolic Ca 2+ activation, and their coupling in AtTPC1.