TY - JOUR T1 - Molecular Basis for Selective Serotonin Re-uptake Inhibition by the Antidepressant Agent Fluoxetine (Prozac) JF - Molecular Pharmacology JO - Mol Pharmacol DO - 10.1124/mol.113.091249 SP - mol.113.091249 AU - Jacob Andersen AU - Nicolai Stuhr-Hansen AU - Linda Gronborg Zachariassen AU - Heidi Koldso AU - Birgit Schiott AU - Kristian Stromgaard AU - Anders Skov Kristensen Y1 - 2014/01/01 UR - http://molpharm.aspetjournals.org/content/early/2014/02/12/mol.113.091249.abstract N2 - 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). 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 to the LeuBAT structures, emphasizing that 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. ER -