Mapping the Binding Site for Escitalopram and Paroxetine in the Human Serotonin Transporter Using Genetically Encoded Photo-Cross-Linkers

TY - JOUR

T1 - Mapping the Binding Site for Escitalopram and Paroxetine in the Human Serotonin Transporter Using Genetically Encoded Photo-Cross-Linkers

AU - Rannversson, Hafsteinn

AU - Andersen, Jacob

AU - Bang-Andersen, Benny

AU - Strømgaard, Kristian

PY - 2017/10/20

Y1 - 2017/10/20

N2 - In spite of the important role of the human serotonin transporter (hSERT) in depression treatment, the molecular details of how antidepressant drugs bind are still not completely understood, in particular those related to potential high- and low-affinity binding sites in hSERT. Here, we utilize amber codon suppression in hSERT to encode the photo-cross-linking unnatural amino acid p-azido-l-phenylalanine into the suggested high- and low-affinity binding sites. We then employ UV-induced cross-linking with azF to map the binding site of escitalopram and paroxetine, two prototypical selective serotonin reuptake inhibitors (SSRIs). We find that the two antidepressant drugs exclusively cross-link to azF incorporated at the high-affinity binding site of hSERT, while cross-linking is not observed at the low-affinity binding site. Combined with previous homology models and recent structural data on hSERT, our results provide important information to understand the molecular details of these clinical relevant binding sites.

AB - In spite of the important role of the human serotonin transporter (hSERT) in depression treatment, the molecular details of how antidepressant drugs bind are still not completely understood, in particular those related to potential high- and low-affinity binding sites in hSERT. Here, we utilize amber codon suppression in hSERT to encode the photo-cross-linking unnatural amino acid p-azido-l-phenylalanine into the suggested high- and low-affinity binding sites. We then employ UV-induced cross-linking with azF to map the binding site of escitalopram and paroxetine, two prototypical selective serotonin reuptake inhibitors (SSRIs). We find that the two antidepressant drugs exclusively cross-link to azF incorporated at the high-affinity binding site of hSERT, while cross-linking is not observed at the low-affinity binding site. Combined with previous homology models and recent structural data on hSERT, our results provide important information to understand the molecular details of these clinical relevant binding sites.

KW - Binding Sites

KW - Citalopram

KW - Crystallography, X-Ray

KW - Humans

KW - Models, Molecular

KW - Paroxetine

KW - Protein Binding

KW - Protein Conformation

KW - Serotonin Plasma Membrane Transport Proteins

KW - Serotonin Uptake Inhibitors

KW - Journal Article

U2 - 10.1021/acschembio.7b00338

DO - 10.1021/acschembio.7b00338

M3 - Letter

C2 - 28910072

SN - 1554-8929

VL - 12

SP - 2558

EP - 2562

JO - ACS chemical biology

JF - ACS chemical biology

IS - 10

ER -