Binding of the Multimodal Antidepressant Drug Vortioxetine to the Human Serotonin Transporter

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Jacob Andersen, Lucy Kate Ladefoged, Danyang Wang, Trine N Bjerre Kristensen, Benny Bang-Andersen, Anders S Kristensen, Birgit Schiøtt, Kristian Strømgaard

Selective inhibitors of the human serotonin transporter (hSERT) have been first-line treatment against depression for several decades. Recently, vortioxetine was approved as a new therapeutic option for the treatment of depression. Vortioxetine represents a new class of antidepressant drugs with a multimodal pharmacological profile that in addition to potent inhibition of hSERT include agonistic or antagonistic effects at different serotonin receptors. We used a combination of computational, chemical, and biological methods to decipher the molecular basis for high affinity binding of vortioxetine in hSERT. X-ray crystal structures of the bacterial amino acid transporter LeuT and the Drosophila melanogaster dopamine transporter were used to build homology models of hSERT. Comparative modeling and ligand docking suggest that vortioxetine can adopt several distinct binding modes within the central binding site of hSERT. To distinguish between the identified binding modes, we determined the effect of 57 functional hSERT point mutants on vortioxetine potency and characterized seven structurally related analogs of vortioxetine in a subset of the point mutants. This allowed us to determine the orientation of vortioxetine within the central binding site and showed that only one of the proposed binding modes is functionally relevant. The findings provide important new insight about the molecular basis for high affinity recognition of vortioxetine in hSERT, which is essential for future structure-based drug discovery of novel multimodal drugs with fine-tuned selectivity across different transporter and receptor proteins in the human brain.

Original languageEnglish
JournalA C S Chemical Neuroscience
Volume6
Issue number11
Pages (from-to)1892-900
Number of pages9
ISSN1948-7193
DOIs
Publication statusPublished - 18 Nov 2015

ID: 156344334