研究揭示 hPepT2 侧向开口位点决定多黏菌素结合与肾毒性
Lateral opening site of human oligopeptide transporter 2 plays a key role in the interaction with polymyxins
研究整合计算建模、化学合成与细胞生物学方法，解析人多肽转运体 2（hPepT2）与多黏菌素的相互作用关系。生物信息学建模预测 hPepT2 呈外向构象并给出潜在转运通路，多黏菌素结合在侧向开口处，涉及 E214、D215、D317、D342 和 E622 等残基；转运体突变与分子分析确认 D215 对多黏菌素结合关键，其余残基影响转运体周转和/或表达。作者随后在 Dab1、Dab3、Dab5 和 Dab9 位点修饰合成多黏菌素类似物，降低了与 hPepT2 的相互作用；其中 Dab3 位点丙氨酸替换在小鼠中降低肾毒性，同时保留抗菌活性。
来源：eLife · doi.org
Multidrug-resistant (MDR) Gram-negative bacteria pose a critical global health threat, while polymyxins remain a last-line therapy. However, their clinical use is limited by nephrotoxicity. Human oligopeptide transporter 2 (hPepT2) is a membrane transporter mediating the reabsorption of polymyxins in renal cells and contributes to their nephrotoxicity, but the molecular basis of their interaction remains unclear. Here, we investigated the structure-interaction relationship (SIR) of polymyxins with hPepT2 by integrating computational, chemical, and cell biology approaches. Bioinformatic modeling predicted an outward-facing hPepT2 structure and a potential transport pathway, with polymyxins interacting at the lateral opening, particularly E214, D215, D317, D342, and E622. Transporter mutagenesis and molecular analyses confirmed that D215 is critical for polymyxin binding, while other residues influence transporter turnover and/or expression. We subsequently synthesized polymyxin analogs with modifications at Dab1, Dab3, Dab5, and Dab9 of polymyxins, which reduced interactions with hPepT2. Notably, alanine substitution at Dab3 reduced nephrotoxicity in mice while retaining antibacterial activity. Overall, this proof-of-concept study demonstrates that the hPepT2-polymyxin SIR model provides a viable strategy for developing novel, safer lipopeptide antibiotics.