title: Molecular basis for selective serotonin reuptake inhibition by the antidepressant agent fluoxetine (Prozac).
abstract: Inhibitors of the serotonin transporter (SERT) are widely used antidepressant agents, but the structural mechanism for inhibitory activity and selectivity over the closely related norepinephrine transporter (NET) is not well understood. Here we use a combination of chemical, biological, and computational methods to decipher the molecular basis for high-affinity recognition in SERT and selectivity over NET for the prototypical antidepressant drug fluoxetine (Prozac; Eli Lilly, Indianapolis, IN). We show that fluoxetine binds within the central substrate site of human SERT, in agreement with recent X-ray crystal structures of LeuBAT, an engineered monoamine-like version of the bacterial amino acid transporter LeuT. However, the binding orientation of fluoxetine is reversed in our experimentally supported model compared with the LeuBAT structures, emphasizing the need for careful experimental verification when extrapolating findings from crystal structures of bacterial transporters to human relatives. We find that the selectivity of fluoxetine and nisoxetine, a NET selective structural congener of fluoxetine, is controlled by residues in different regions of the transporters, indicating a complex mechanism for selective recognition of structurally similar compounds in SERT and NET. Our findings add important new information on the molecular basis for SERT/NET selectivity of antidepressants, and provide the first assessment of the potential of LeuBAT as a model system for antidepressant binding in human transporters, which is essential for future structure-based drug development of antidepressant drugs with fine-tuned transporter selectivity.
authors: Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark (J.A., N.S.-H., L.G.Z., K.S., A.S.K.); and Center for Insoluble Structures (inSPIN) and Interdisciplinary Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, Aarhus, Denmark (H.K., B.S.).
authors: Jacob
authors: J
authors: Andersen
authors: Nicolai
authors: N
authors: Stuhr-Hansen
authors: Linda Grønborg
authors: LG
authors: Zachariassen
authors: Heidi
authors: H
authors: Koldsø
authors: Birgit
authors: B
authors: Schiøtt
authors: Kristian
authors: K
authors: Strømgaard
authors: Anders S
authors: AS
authors: Kristensen
mesh_terms: D000818:Animals; D018687:Antidepressive Agents, Second-Generation / Q000737:chemistry* / Q000378:metabolism*; D019556:COS Cells; D002522:Chlorocebus aethiops; D018360:Crystallography, X-Ray; D005473:Fluoxetine / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D050484:Norepinephrine Plasma Membrane Transport Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D050486:Serotonin Plasma Membrane Transport Proteins / Q000378:metabolism; D017367:Selective Serotonin Reuptake Inhibitors / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D018687:Antidepressive Agents, Second-Generation; D005473:Fluoxetine; D050484:Norepinephrine Plasma Membrane Transport Proteins; D050486:Serotonin Plasma Membrane Transport Proteins; D017367:Selective Serotonin Reuptake Inhibitors; C493227:SLC6A2 protein, human; C493230:SLC6A4 protein, human