Functional and structural analysis of the human SLO3 pH- and voltage-gated K+ channel
Functional and structural analysis of the human SLO3 pH- and voltage-gated K+ channel
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DOI：
10.1073/pnas.1215078109
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发表时间：
2012-11-20
影响因子：
11.1
通讯作者：
MacKinnon, Roderick
中科院分区：
文献类型：
--
作者：
Leonetti, Manuel D.;Yuan, Peng;MacKinnon, Roderick
真核生物SLO K+通道的激活是由细胞内信号介导的，由称为门控环的细胞质结构介导，是其生理作用的核心。SLO 3通道仅在哺乳动物精子中表达，其中细胞内pH的变化对细胞功能至关重要。以前的研究主要集中在小鼠SLO 3的直系同源物，并显示，在小鼠精子中，SLO 3介导的电压和碱化激活的K+电流对男性生育力至关重要。在这里，我们调查的激活人SLO 3通道的细胞内pH值在功能和结构水平。通过在异源系统中使用电生理学，我们表明，人SLO3打开细胞内pH值的增加，其表达和功能特性的调节LRRC52，睾丸特异性辅助亚基。接下来，我们展示了人SLO 3门控环的晶体结构。与已知结构的相应结构域从SLO 1，钙激活的同源物的比较，表明SLO 3门控环结构可能代表一个开放的状态。总之，这些结果提供了对预期对人类生殖至关重要的蛋白质的功能的见解，并提供了一个框架来研究SLO 3通道中pH门控的机制。
The activation of eukaryotic SLO K+ channels by intracellular cues, mediated by a cytoplasmic structure called the gating ring, is central to their physiological roles. SLO3 channels are exclusively expressed in mammalian sperm, where variations of intracellular pH are critical to cellular function. Previous studies primarily focused on the mouse SLO3 orthologue and revealed that, in murine sperm, SLO3 mediates a voltage- and alkalization-activated K+ current essential to male fertility. Here we investigate the activation of the human SLO3 channel by intracellular pH at the functional and structural level. By using electrophysiology in a heterologous system, we show that human SLO3 opens upon intracellular pH increase and that its expression and functional properties are modulated by LRRC52, a testis-specific accessory subunit. We next present the crystal structure of the human SLO3 gating ring. Comparison with the known structures of the corresponding domain from SLO1, a Ca2+-activated homologue, suggests that the SLO3 gating ring structure may represent an open state. Together, these results present insights into the function of a protein expected to be critical for human reproduction and provide a framework to study the mechanism of pH gating in SLO3 channels.