The interaction between nuclear receptor coactivator 4 (NCOA4) and the iron storage protein ferritin is a crucial component of cellular iron homeostasis. The binding of NCOA4 to the FTH1 subunits of ferritin initiates ferritinophagy—a ferritin-specific autophagic pathway leading to the release of the iron stored inside ferritin. The dysregulation of NCOA4 is associated with several diseases, including neurodegenerative disorders and cancer, highlighting the NCOA4-ferritin interface as a prime target for drug development. Here, we present the cryo-EM structure of the NCOA4-FTH1 interface, resolving 16 amino acids of NCOA4 that are crucial for the interaction. The characterization of mutants, designed to modulate the NCOA4–FTH1 interaction, is used to validate the significance of the different features of the binding site. Our results explain the role of the large solvent-exposed hydrophobic patch found on the surface of FTH1 and pave the way for the rational development of ferritinophagy modulators.

核受体辅激活因子 4 (NCOA4) 和铁储存蛋白铁蛋白之间的相互作用是细胞铁稳态的重要组成部分。 NCOA4 与铁蛋白 FTH1 亚基的结合启动铁蛋白自噬——一种铁蛋白特异性自噬途径，导致铁蛋白内储存的铁释放。 NCOA4 的失调与多种疾病有关，包括神经退行性疾病和癌症，这凸显了 NCOA4-铁蛋白界面作为药物开发的主要目标。在这里，我们展示了 NCOA4-FTH1 界面的冷冻电镜结构，解析了 NCOA4 中对于相互作用至关重要的 16 个氨基酸。突变体的表征旨在调节 NCOA4-FTH1 相互作用，用于验证结合位点不同特征的重要性。我们的结果解释了 FTH1 表面发现的大型溶剂暴露疏水斑块的作用，并为合理开发铁蛋白自噬调节剂铺平了道路。