Subjects: Pharmaceutical Science >> Structural Biology submitted time 2024-04-27
Heng Zhang
Yuling Yin
Tianwei Zhang
Canrong Wu
Wen Hu
Xinheng He
Benxun Pan
Sanshan Jin
Qingning Yuan
H. Eric Xu
Yi Jiang
Abstract： The norepinephrine transporter (NET) plays a pivotal role in regulating neurotransmitter balance and is critical for normal physiology and neurobiology. Dysfunction of NET has been implicated in numerous neuropsychiatric diseases including depression, anxiety, attention deficit hyperactivity disorder, and Parkinson’s disease. Here we report cryo-EM structures of NET in apo and substrate-bound forms, as well as complexes with six antidepressants. The structures reveal an unexpected NET dimer interface predominantly mediated by cholesterol and lipid molecules. The substrate norepinephrine is found to bind deep within the central binding pocket, with its amine group interacting with a conserved aspartate. The structures also provide insight into antidepressant recognition, including how subtle differences in binding poses confer selectivity over other monoamine transporters. Together these breakthrough findings significantly advance our understanding of NET regulation and inhibition, providing templates for designing improved antidepressants to treat neuropsychiatric disorders.
Subjects: Pharmaceutical Science >> Structural Biology submitted time 2024-02-24
Heng Liu
Shimeng Guo
Antao Dai
Peiyu Xu
Xin Li
Sijie Huang
Xinheng He
Kai Wu
Xinyue Zhang
Dehua Yang
Xin Xie
H. Eric Xu
Abstract： The orphan receptor GPR30, previously classified as a G protein-coupled estrogen receptor (GPER), has been a subject of debate regarding its ligand specificity. Through an integrative approach combining structure elucidation, biochemical binding, and cell signaling assays, we demonstrate that estrogen does not directly bind to or activate GPR30. Cryo-EM structures of GPR30 reveal an unexpected hydrophilic ligand-binding pocket, with striking differences from classical hydrophobic steroid-binding sites, inconsistent with estrogen binding. We further confirmed hydrophilic agonists like Lys05 as true activators of GPR30, providing structural insights into their binding mechanism and receptor activation. Our findings necessitate a paradigm shift in defining GPR30’s role in estrogen signaling, indicating that its activation occurs through mechanisms independent of estrogen binding. This study opens new avenues for developing targeted GPR30 ligands and reinterpreting its role in estrogen-mediated processes.
Peer Review Status:
Awaiting Review
Subjects: Pharmaceutical Science >> Structural Biology submitted time 2024-02-21
Abstract： Bombesin receptor subtype-3 (BRS3) is an important orphan G protein-coupled receptor that regulates energy homeostasis and insulin secretion. As a member of the bombesin receptor (BnR) family, which includes neuromedin B receptor (NMBR) and gastrin-releasing peptide receptor (GRPR), the lack of known endogenous ligands and high-resolution structure has impeded understanding of BRS3 signaling and function. Here, we present cryogenic electron microscopy (cryo-EM) structures of BRS3 in complex with heterotrimeric Gq protein in three states: apo, bound to the pan-BnR agonist, BA1, and bound to the synthetic BRS3-specific agonist MK-5046. These structures reveal the architecture of the orthosteric ligand pocket underpinning molecular recognition. Comparisons with BnR members provide insights into the structural basis for BRS3’s selectivity and low affinity for bombesin peptides. Examination of conserved micro-switches suggests a shared activation mechanism among BnRs. Together our results enable deeper exploration of BRS3’s ligand selectivity, signaling, and therapeutic targeting for diabetes and obesity.
Peer Review Status:Awaiting Review
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