State Key Laboratory of Membrane Biology, College of Future Technology, Institute of Molecular Medicine, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, 100871, Beijing, China.
Peking-Tsinghua Center for Life Sciences, Peking University, 100871, Beijing, China.
Nat Commun. 2021 Jan 8;12(1):155. doi: 10.1038/s41467-020-20466-9.
Dual oxidases (DUOXs) produce hydrogen peroxide by transferring electrons from intracellular NADPH to extracellular oxygen. They are involved in many crucial biological processes and human diseases, especially in thyroid diseases. DUOXs are protein complexes co-assembled from the catalytic DUOX subunits and the auxiliary DUOXA subunits and their activities are regulated by intracellular calcium concentrations. Here, we report the cryo-EM structures of human DUOX1-DUOXA1 complex in both high-calcium and low-calcium states. These structures reveal the DUOX1 complex is a symmetric 2:2 hetero-tetramer stabilized by extensive inter-subunit interactions. Substrate NADPH and cofactor FAD are sandwiched between transmembrane domain and the cytosolic dehydrogenase domain of DUOX. In the presence of calcium ions, intracellular EF-hand modules might enhance the catalytic activity of DUOX by stabilizing the dehydrogenase domain in a conformation that allows electron transfer.
双氧化酶 (DUOXs) 通过将细胞内 NADPH 的电子转移到细胞外氧气中来产生过氧化氢。它们参与许多关键的生物过程和人类疾病，特别是甲状腺疾病。DUOXs 是由催化 DUOX 亚基和辅助 DUOXA 亚基共同组装而成的蛋白复合物，其活性受细胞内钙离子浓度的调节。在这里，我们报告了人 DUOX1-DUOXA1 复合物在高钙和低钙状态下的冷冻电镜结构。这些结构揭示了 DUOX1 复合物是一个由广泛的亚基间相互作用稳定的对称 2:2 异四聚体。底物 NADPH 和辅因子 FAD 夹在 DUOX 的跨膜结构域和胞质脱氢酶结构域之间。在钙离子存在的情况下，细胞内 EF 手模块可能通过稳定脱氢酶结构域使其处于允许电子转移的构象来增强 DUOX 的催化活性。
