Johannes Gutenberg University, Johann-Joachim-Becher-Weg 30, 55128 Mainz, Germany.
Johannes Gutenberg University, Johann-Joachim-Becher-Weg 30, 55128 Mainz, Germany.
Biochim Biophys Acta Biomembr. 2018 Apr;1860(4):887-894. doi: 10.1016/j.bbamem.2017.10.018. Epub 2017 Oct 22.
The vestibule loop regions of aquaglyceroporins are involved in accumulation of glycerol inside the channel pore. Even though most loop regions do not show high sequence similarity among aquaglyceroporins, loop E is highly conserved in aquaglyceroporins, but not in members of the homologous aquaporins. Specifically, a tryptophan residue is extremely conserved within this loop. We have investigated the role of this residue (Trp219) that deeply protrudes into the protein and potentially interacts with adjacent loops, using the E. coli aqualgyeroporin GlpF as a model. Replacement of Trp219 affects the activity of GlpF and impairs the stability of the tetrameric protein. Furthermore, we have identified an amino acid cluster involving Trp219 that stabilizes the GlpF tetramer. Based on our results we propose that Trp219 is key for formation of a defined vestibule structure, which is crucial for glycerol accumulation as well as for the stability of the active GlpF tetramer.
水甘油通道蛋白的前庭环区参与甘油在通道孔内的积累。尽管大多数环区在水甘油通道蛋白之间没有显示出很高的序列相似性，但环 E 在水甘油通道蛋白中高度保守，但在同源水通道蛋白的成员中则不然。具体来说，该环中的一个色氨酸残基极其保守。我们使用大肠杆菌 aqualgyeroporin GlpF 作为模型，研究了这个残基（色氨酸 219）的作用，该残基深深地突入到蛋白质中，并可能与相邻的环相互作用。取代色氨酸 219 会影响 GlpF 的活性，并损害四聚体蛋白的稳定性。此外，我们已经确定了一个涉及色氨酸 219 的氨基酸簇，该簇稳定了 GlpF 四聚体。基于我们的结果，我们提出色氨酸 219 是形成特定前庭结构的关键，这对甘油积累以及活性 GlpF 四聚体的稳定性至关重要。
