Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA.
Departments of Biological Sciences, Chemistry, and Bioengineering, Lehigh University, Bethlehem, PA, USA.
Nat Chem Biol. 2024 Sep;20(9):1144-1153. doi: 10.1038/s41589-024-01559-8. Epub 2024 Feb 28.
Nucleoside analogs have broad clinical utility as antiviral drugs. Key to their systemic distribution and cellular entry are human nucleoside transporters. Here, we establish that the human concentrative nucleoside transporter 3 (CNT3) interacts with antiviral drugs used in the treatment of coronavirus infections. We report high-resolution single-particle cryo-electron microscopy structures of bovine CNT3 complexed with antiviral nucleosides N-hydroxycytidine, PSI-6206, GS-441524 and ribavirin, all in inward-facing states. Notably, we found that the orally bioavailable antiviral molnupiravir arrests CNT3 in four distinct conformations, allowing us to capture cryo-electron microscopy structures of drug-loaded outward-facing and drug-loaded intermediate states. Our studies uncover the conformational trajectory of CNT3 during membrane transport of a nucleoside analog antiviral drug, yield new insights into the role of interactions between the transport and the scaffold domains in elevator-like domain movements during drug translocation, and provide insights into the design of nucleoside analog antiviral prodrugs with improved oral bioavailability.
核苷类似物作为抗病毒药物具有广泛的临床应用。它们在体内的分布和细胞进入的关键是人体核苷转运蛋白。在这里，我们确定了人类高浓度核苷转运蛋白 3（CNT3）与用于治疗冠状病毒感染的抗病毒药物相互作用。我们报告了与抗病毒核苷 N-羟基胞苷、PSI-6206、GS-441524 和利巴韦林复合的牛 CNT3 的高分辨率单颗粒冷冻电镜结构，均处于内向状态。值得注意的是，我们发现可口服生物利用的抗病毒药物莫努匹韦以四种不同的构象使 CNT3 失活，使我们能够捕获药物负载的外向构象和药物负载的中间构象的冷冻电镜结构。我们的研究揭示了核苷类似物抗病毒药物在膜转运过程中 CNT3 的构象轨迹，深入了解了在药物转运过程中，转运和支架结构域之间的相互作用在电梯样结构域运动中的作用，为设计具有改善口服生物利用度的核苷类似物抗病毒前药提供了思路。
