Structural basis for CFTR inhibition by CFTRinh-172

• 成果类型: Article
• 署名作者: Young, Paul G.; Levring, Jesper; Fiedorczuk, Karol; Blanchard, Scott C.; Chen, Jue
• 署名单位: Rockefeller University; St Jude Children's Research Hospital; Rockefeller University; Howard Hughes Medical Institute
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-9830
• DOI: 10.1073/pnas.2316675121
• 发表日期: 2024-03-05
• 关键词: cystic-fibrosis; cholera-toxin; secretory diarrhea; membrane-proteins; chloride channel; fluid secretion; mechanism; potentiator; ivacaftor; DISCOVERY

摘要

The cystic fibrosis transmembrane conductance regulator (CFTR) is an anion channel that regulates electrolyte and fluid balance in epithelial tissues. While activation of CFTR is vital to treating cystic fibrosis, selective inhibition of CFTR is a potential therapeutic strategy for secretory diarrhea and autosomal dominant polycystic kidney disease. Although several CFTR inhibitors have been developed by high- throughput screening, their modes of action remain elusive. In this study, we determined the structure of CFTR in complex with the inhibitor CFTRinh- 172 to an overall resolution of 2.7 angstrom by cryogenic electron microscopy. We observe that CFTRinh- 172 binds inside the pore near transmembrane helix 8, a critical structural element that links adenosine triphosphate hydrolysis with channel gating. Binding of CFTRinh- 172 stabilizes a conformation in which the chloride selectivity filter is collapsed, and the pore is blocked from the extracellular side of the membrane. Single- molecule fluorescence resonance energy transfer experiments indicate that CFTRinh- 172 inhibits channel gating without compromising nucleotide- binding domain dimerization. Together, these data reconcile previous biophysical observations and provide a molecular basis for the activity of this widely used CFTR inhibitor.