Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom.
Computational Biology Centre for Translational and Interdisciplinary Research, University of Dundee, Dundee, United Kingdom.
Elife. 2020 Aug 11;9:e56416. doi: 10.7554/eLife.56416.
Mutations in the aquaporin AQP2 are associated with resistance to pentamidine and melarsoprol. We show that TbAQP2 but not TbAQP3 was positively selected for increased pore size from a common ancestor aquaporin. We demonstrate that TbAQP2's unique architecture permits pentamidine permeation through its central pore and show how specific mutations in highly conserved motifs affect drug permeation. Introduction of key TbAQP2 amino acids into TbAQP3 renders the latter permeable to pentamidine. Molecular dynamics demonstrates that permeation by dicationic pentamidine is energetically favourable in TbAQP2, driven by the membrane potential, although aquaporins are normally strictly impermeable for ionic species. We also identify the structural determinants that make pentamidine a permeant although most other diamidine drugs are excluded. Our results have wide-ranging implications for optimising antitrypanosomal drugs and averting cross-resistance. Moreover, these new insights in aquaporin permeation may allow the pharmacological exploitation of other members of this ubiquitous gene family.
水通道蛋白 AQP2 的突变与戊烷脒和喷他脒的耐药性有关。我们表明，TbAQP2 而不是 TbAQP3 从共同祖先水通道蛋白中被正选择以增加孔径。我们证明，TbAQP2 的独特结构允许戊烷脒通过其中心孔渗透，并展示了高度保守基序中的特定突变如何影响药物渗透。将关键的 TbAQP2 氨基酸引入 TbAQP3 使后者对戊烷脒具有渗透性。分子动力学表明，带正电荷的戊烷脒在 TbAQP2 中的渗透是有利的，这是由膜电位驱动的，尽管水通道蛋白通常对离子物质严格不可渗透。我们还确定了使戊烷脒成为可渗透的结构决定因素，尽管大多数其他二脒药物被排除在外。我们的研究结果对优化抗锥虫药物和避免交叉耐药性具有广泛的意义。此外，这些关于水通道蛋白渗透的新见解可能允许对该普遍存在的基因家族的其他成员进行药理学利用。
