Zinc activation of OTOP proton channels identifies structural elements of the gating apparatus.
Zinc activation of OTOP proton channels identifies structural elements of the gating apparatus.
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DOI：
10.7554/elife.85317
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发表时间：
2023-04-13
期刊：
影响因子：
7.7
通讯作者：
Liman ER
中科院分区：
文献类型：
--
作者：
Teng B;Kaplan JP;Liang Z;Chyung KS;Goldschen-Ohm MP;Liman ER
耳啡肽蛋白（OTOP）形成质子选择性离子通道，在不同的细胞类型中表达，它们介导酸的检测或pH的调节。在脊椎动物中有三个家族成员：OTOP 1是前庭系统中耳石形成所必需的，它形成酸味受体，而OTOP 2和OTOP 3的功能尚不清楚。重要的是，任何OTOP通道的门控机制都没有很好地理解。在这里，我们表明，锌（Zn 2+），以及其他过渡金属，包括铜（Cu 2+），有效地激活鼠OTOP 3（mOTOP 3）。Zn 2+预暴露增加了mOTOP 3电流的幅度，随后的酸刺激多达10倍。相比之下，mOTOP 2电流对Zn 2+的激活不敏感。在mOTOP 3和mOTOP 2之间交换细胞外tm 11-12接头足以消除mOTOP 3的Zn 2+活化并赋予mOTOP 2 Zn 2+活化。tm 11-12接头内的H531和E535以及5-6接头内的H234和E238突变为丙氨酸，减少或消除了Zn 2+对mOTOP 3的激活，这表明这些残基可能对Zn 2+激活位点有贡献。动力学建模的数据是一致的Zn 2+稳定opn 2 +en状态的通道，竞争与H+激活的通道。这些结果确立了tm 11-12和tm 5-6接头作为OTOP通道的门控装置的一部分和药物发现的靶标。Zn 2+是一种必需的微量营养素，其激活OTOP通道无疑会产生重要的生理后遗症。
Otopetrin proteins (OTOPs) form proton-selective ion channels that are expressed in diverse cell types where they mediate detection of acids or regulation of pH. In vertebrates there are three family members: OTOP1 is required for formation of otoconia in the vestibular system and it forms the receptor for sour taste, while the functions of OTOP2 and OTOP3 are not yet known. Importantly, the gating mechanisms of any of the OTOP channels are not well understood. Here, we show that zinc (Zn2+), as well as other transition metals including copper (Cu2+), potently activates murine OTOP3 (mOTOP3). Zn2+ pre-exposure increases the magnitude of mOTOP3 currents to a subsequent acid stimulus by as much as 10-fold. In contrast, mOTOP2 currents are insensitive to activation by Zn2+. Swapping the extracellular tm 11–12 linker between mOTOP3 and mOTOP2 was sufficient to eliminate Zn2+ activation of mOTOP3 and confer Zn2+ activation on mOTOP2. Mutation to alanine of H531 and E535 within the tm 11–12 linker and H234 and E238 within the 5–6 linker reduced or eliminated activation of mOTOP3 by Zn2+, indicating that these residues likely contribute to the Zn2+ activating site. Kinetic modeling of the data is consistent with Zn2+ stabilizing the opn2+en state of the channel, competing with H+ for activation of the channels. These results establish the tm 11–12 and tm 5–6 linkers as part of the gating apparatus of OTOP channels and a target for drug discovery. Zn2+ is an essential micronutrient and its activation of OTOP channels will undoubtedly have important physiological sequelae.
DOI：
10.1085/jgp.200609492
发表时间：
2006-07
期刊：
The Journal of general physiology
影响因子：
--
作者：
Sack JT;Aldrich RW
通讯作者：
Aldrich RW
DOI：
10.1085/jgp.201110699
发表时间：
2012-03
期刊：
The Journal of general physiology
影响因子：
--
作者：
Shcheglovitov A;Vitko I;Lazarenko RM;Orestes P;Todorovic SM;Perez-Reyes E
通讯作者：
Perez-Reyes E