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异源多聚氨基酸转运蛋白的结构生物学基础及靶向药物研究进展

Structural basis of heteromeric amino acid transporters and advances in targeted drug development

  • 摘要: 由SLC3与SLC7家族成员组装形成的异源多聚氨基酸转运蛋白(heteromeric amino acid transporters, HATs),在氨基酸跨膜转运、细胞营养感知及氧化还原稳态维持中发挥核心作用。多个家族成员的功能异常与肿瘤代谢重编程、铁死亡抵抗及遗传性氨基酸代谢病密切相关,使HATs成为重要的药物开发靶点。然而,该家族成员底物结合口袋高度保守、两性离子化合物成药性受限,以及其在正常组织中的广泛表达所带来的安全性顾虑,均在一定程度上制约了相关药物的临床转化进程。近年来,冷冻电镜技术的快速发展推动了多个HATs复合物高分辨率结构的解析,为理解其分子机制及靶向干预提供了关键基础。这些结构研究系统揭示了不同成员在底物选择性识别与离子耦联机制方面的分子差异,并揭示了一些非保守结构特征,为实现亚型选择性提供了潜在结构窗口。本文系统综述了HATs家族的结构生物学研究进展,重点总结其组装方式、底物识别模式及构象转换机制。在此基础上,进一步归纳了基于结构的药物设计(structure-based drug design, SBDD)的最新进展,包括通过利用非保守疏水侧袋提高配体亲和力,以及通过破坏跨膜螺旋TM3和TM10的二级结构以阻断转运循环的策略。上述研究为开发高选择性HATs抑制剂及相关治疗策略提供了重要的结构依据与研究思路。

     

    Abstract: Heteromeric amino acid transporters (HATs), formed by the assembly of solute carrier 3(SLC3) and solute carrier 7(SLC7) family members, play essential roles in amino acid transmembrane transport, cellular nutrient sensing, and redox homeostasis. Dysregulation of multiple HATs members has been closely associated with tumor metabolic reprogramming, ferroptosis resistance, and inherited amino acid metabolic disorders, making them important targets for drug development. However, the high conservation of substrate-binding pockets, the limited druggability of zwitterionic compounds, and safety concerns arising from their broad expression in normal tissues have collectively hindered the clinical translation of HATs-targeted therapeutics. Recent advances in cryo-electron microscopy (Cryo-EM) have enabled the determination of high-resolution structures of multiple HATs, providing a critical foundation for understanding their molecular mechanisms and for guiding targeted interventions. These structural studies have systematically revealed the molecular basis of selective substrate recognition and ion coupling among different family members and have identified non-conserved structural features that may serve as potential opportunities for subtype-selective targeting. In this review, we systematically summarize recent advances in the structural biology of HATs, with a particular emphasis on their assembly mechanisms, substrate recognition modes, and conformational transitions. Furthermore, we highlight recent progress in structure-based drug design (SBDD), including strategies to enhance ligand affinity by exploiting non-conserved hydrophobic side pockets, as well as approaches to block the transport cycle by disrupting the secondary structures of transmembrane helices TM3 and TM10. Collectively, these insights provide an important structural framework and new perspectives for the development of highly selective inhibitors for HATs and related therapeutic strategies.

     

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