Structural basis of disease mutation and substrate recognition by the human SLC2A9 transporter

• 成果类型: Article
• 署名作者: Khandelwal, Nitesh Kumar; Gupta, Meghna; Kumar, Paras; Balasubramani, Sree Ganesh; Echeverria, Ignacia; Stroud, Robert M.
• 署名单位: University of California System; University of California San Francisco; University of California System; University of California San Francisco; University of California System; University of California San Francisco; Oregon Health & Science University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-13379
• DOI: 10.1073/pnas.241828212
• 发表日期: 2025-02-18
• 关键词: urate transporter; glut9; identification; refinement; expression; gene

摘要

Urate provides similar to 50% of the reducing potential in human and primate plasma which is key to detoxifying reactive oxygen by- products of cellular metabolism. Urate is the endpoint of purine metabolism in primates, and its concentration in plasma is a bal-ance between excretion from kidney and intestine, and subsequent reabsorption in and through cells of kidney proximal tubules to maintain a regulated concentration in plasma. SLC2A9 is the primary transporter that returns urate from the basolateral side of kidney tubule cells back to plasma. A shorter splice variant of SLC2A9 is directed to the apical surface where several transporters recapture urate from the tubule back into cells. Too high a concentration in plasma causes hyperuricemia, is linked to gout, and favors kidney stone formation. To understand the molecular basis of uric acid transport and the role of disease- causing mutations in SLC2A9, we determined structures of human SLC2A9 in its apo form, and its urate- bound form by cryo- EM, at resolution of 3.3 angstrom and 4.1 angstrom respectively. Both structures are captured in an inward open confor-mation. Using the inward- facing structure as a template we modeled the outward- facing conformation to understand the alternating access mechanism. Alternative salt bridge pairs on the cytoplasmic side suggest a mechanism that can balance the energetics of the inward open and outward open states. The location of disease- causing mutants suggests their role in impacting function. Our structures elucidate the molecular basis for urate selectivity and transport and provide a platform for future structure- based drug discovery aimed at reducing plasma urate levels in diseases of hyperuricemia and gout.