Substrate binding and inhibition mechanism of norepinephrine transporter

• Published in: Nature (London) 2024-09, Vol.633 (8029), p.473-479
• Main Authors: Ji, Wenming, Miao, Anran, Liang, Kai, Liu, Jiameng, Qi, Yuhan, Zhou, Yue, Duan, Xinli, Sun, Jixue, Lai, Lipeng, Wu, Jing-Xiang
• Format: Article
• Language: English
• Subjects: 101/28; 631/378/1689/1414; 631/378/2587; 631/535/1258/1259; 692/617/375; 82/80; 82/83; Antidepressants; Attention deficit hyperactivity disorder; Binding Sites; Chromatography; Conformation; Cryoelectron Microscopy; Dopamine; Electron microscopy; Humanities and Social Sciences; Humans; Microscopy; Models, Molecular; multidisciplinary; Mutation; Neuroendocrine tumors; Noradrenaline; Norepinephrine; Norepinephrine - metabolism; Norepinephrine Plasma Membrane Transport Proteins - antagonists & inhibitors; Norepinephrine Plasma Membrane Transport Proteins - chemistry; Norepinephrine Plasma Membrane Transport Proteins - metabolism; Norepinephrine transporter; Protein Binding; Proteins; Science; Science (multidisciplinary); Substrate inhibition; Substrate Specificity; Substrates
• ISSN: 0028-0836; 1476-4687; 1476-4687
• DOI: 10.1038/s41586-024-07810-5

Norepinephrine transporter (NET; encoded by SLC6A2 ) reuptakes the majority of the released noradrenaline back to the presynaptic terminals, thereby affecting the synaptic noradrenaline level 1 . Genetic mutations and dysregulation of NET are associated with a spectrum of neurological conditions in humans, making NET an important therapeutic target 1 . However, the structure and mechanism of NET remain unclear. Here we provide cryogenic electron microscopy structures of the human NET (hNET) in three functional states—the apo state, and in states bound to the substrate meta-iodobenzylguanidine (MIBG) or the orthosteric inhibitor radafaxine. These structures were captured in an inward-facing conformation, with a tightly sealed extracellular gate and an open intracellular gate. The substrate MIBG binds at the centre of hNET. Radafaxine also occupies the substrate-binding site and might block the structural transition of hNET for inhibition. These structures provide insights into the mechanism of substrate recognition and orthosteric inhibition of hNET. Structures of human NET in the apo state and bound to meta-iodobenzylguanidine and radafaxine provide insights into the mechanism of substrate recognition and orthosteric inhibition of hNET.