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水糖素AQP3和GlpF的孔状结构缩小

Daisuke Kozai¹, Masao Inoue², Shota Suzuki¹

¹Cellular and Structural Physiology Laboratory (CeSPL), Advanced Research Initiative, Institute of Integrated Research, Institute of Science Tokyo, Tokyo, Japan.

Nature communications

|March 21, 2025

概括

像aquaporin-3 (AQP3) 这样的水糖素控制水和糖的运输. 新结构揭示了AQP3的新结构.

科学领域:

结构生物学是结构生物学.
膜运输是通过膜运输来实现的.
生物物理学的生物物理.

背景情况:

水糖蛋白 (AQPs),包括水素-3 (AQP3) 和细菌GlpF,是整体膜蛋白,促进水和甘油在细胞膜上的运输.
以前的研究,主要基于GlpF的X射线晶体学和AQP3的预测,表明这些通道具有开放的孔状结构.
了解AQP3独特的运输特性及其形状灵活性的结构基础对于破译其生理作用至关重要.

研究的目的:

阐明水甘油透水和甘油透的基础结构机制,重点关注老鼠水甘油-3 (AQP3) 和细菌GlpF.
调查特定残留物的作用,特别是像AQP3中的Tyr212这样的芳香残留物,在调节通道形状和透性方面.
探索aquaglyceroporins之间的结构多样性,并确定独特的结构状态.

主要方法:

使用冷电子显微镜 (cryo-EM) 在不同的脂质和洗剂环境中确定大鼠 AQP3 和 GlpF 的高分辨率结构.
进行了分子动力学 (MD) 模拟,以分析观察到的AQP3形状的稳定性和功能影响.
用于检测关键残留物在形状变化中的作用,利用位点定向突变 (AQP3 Y212F和Y212T) 来检测.

主要成果:

冷电磁检测显示了AQP3和GlpF两种明显的狭窄孔状,挑战了以前被认为是完全开放的状态.
在POPC纳米盘中,AQP3采用了独特的形状,Tyr212插入孔隙,显著降低了水的透性,MD模拟证实了这一点.
突变分析表明,Tyr212的芳香性质对于诱导AQP3中这种插入孔的构造至关重要,而GlpF则表现出覆盖其孔的细胞内循环,这种特征主要与透性无关.

结论:

这项研究揭示了AQP3独特的孔狭形状,由芳香残留物插入驱动,可以动态调节其水透性.
这些发现突出了水糖蛋白之间显著的结构多样性,与GlpF和AQP7相比,AQP3表现出独特的形状可塑性.
这些结构洞察力为我们提供了更深入的了解,了解在分子层面上对水甘油的功能和调节.

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