Department of Biological Sciences, National University of Singapore, Queenstown, Singapore.
Department and Chemistry and Molecular Biology, Gothenburg University, Göteborg, Sweden.
Life Sci Alliance. 2022 Oct 13;5(12):e202201491. doi: 10.26508/lsa.202201491.
Aquaporins are protein channels embedded in the lipid bilayer in cells from all organisms on earth that are crucial for water homeostasis. In fish, aquaporins are believed to be important for osmoregulation; however, the molecular mechanism behind this is poorly understood. Here, we present the first structural and functional characterization of a fish aquaporin; cpAQP1aa from the fresh water fish climbing perch (<i>Anabas testudineus</i>), a species that is of high osmoregulatory interest because of its ability to spend time in seawater and on land. These studies show that cpAQP1aa is a water-specific aquaporin with a unique fold on the extracellular side that results in a constriction region. Functional analysis combined with molecular dynamic simulations suggests that phosphorylation at two sites causes structural perturbations in this region that may have implications for channel gating from the extracellular side.
水通道蛋白是一种蛋白通道，嵌入地球上所有生物体的细胞膜脂质双层中，对于水稳态至关重要。在鱼类中，水通道蛋白被认为对渗透调节很重要；然而，其背后的分子机制还知之甚少。在这里，我们首次对鱼类水通道蛋白进行了结构和功能表征；来自淡水鱼攀鲈（<i>Anabas testudineus</i>）的 cpAQP1aa，由于其能够在海水中和陆地上停留的能力，该物种具有很高的渗透调节兴趣。这些研究表明，cpAQP1aa 是一种具有独特折叠的水特异性水通道蛋白，在细胞外表面形成一个狭窄区域。功能分析结合分子动力学模拟表明，两个位点的磷酸化会导致该区域的结构扰动，这可能对细胞外侧面的通道门控有影响。
