Pentamidine and melarsoprol are primary drugs used to treat the lethal human sleeping sickness caused by the parasite Trypanosoma brucei. Cross-resistance to these two drugs has recently been linked to aquaglyceroporin 2 of the trypanosome (TbAQP2). TbAQP2 is the first member of the aquaporin family described as capable of drug transport; however, the underlying mechanism remains unclear. Here, we present cryo-electron microscopy structures of TbAQP2 bound to pentamidine or melarsoprol. Our structural studies, together with the molecular dynamic simulations, reveal the mechanisms shaping substrate specificity and drug permeation. Multiple amino acids in TbAQP2, near the extracellular entrance and inside the pore, create an expanded conducting tunnel, sterically and energetically allowing the permeation of pentamidine and melarsoprol. Our study elucidates the mechanism of drug transport by TbAQP2, providing valuable insights to inform the design of drugs against trypanosomiasis.

喷他脒和美拉丙醇是用于治疗由寄生虫布氏锥虫引起的致命性人类昏睡病的主要药物。最近发现这两种药物的交叉耐药性与锥虫的水甘油孔蛋白 2 (TbAQP2) 有关。 TbAQP2 是水通道蛋白家族中第一个被描述为具有药物转运能力的成员；然而，其根本机制仍不清楚。在这里，我们展示了与喷他脒或 melarsoprol 结合的 TbAQP2 的冷冻电子显微镜结构。我们的结构研究与分子动力学模拟一起揭示了形成底物特异性和药物渗透的机制。 TbAQP2 中的多个氨基酸在细胞外入口附近和孔内形成一个扩大的传导通道，在空间和能量上允许喷他脒和 melarsoprol 的渗透。我们的研究阐明了 TbAQP2 的药物转运机制，为抗锥虫病药物的设计提供了宝贵的见解。