TY - JOUR
T1 - Homology modeling informs ligand discovery for the glutamine transporter ASCT2
AU - Garibsingh, Rachel Ann A.
AU - Otte, Nicholas J.
AU - Ndaru, Elias
AU - Colas, Claire
AU - Grewer, Christof
AU - Holst, Jeff
AU - Schlessinger, Avner
N1 - Publisher Copyright:
© 2018 Garibsingh, Otte, Ndaru, Colas, Grewer, Holst and Schlessinger.
PY - 2018
Y1 - 2018
N2 - The Alanine-Serine-Cysteine transporter (SLC1A5, ASCT2), is a neutral amino acid exchanger involved in the intracellular homeostasis of amino acids in peripheral tissues. Given its role in supplying glutamine to rapidly proliferating cancer cells in several tumor types such as triple-negative breast cancer and melanoma, ASCT2 has been identified as a key drug target. Here we use a range of computational methods, including homology modeling and ligand docking, in combination with cell-based assays, to develop hypotheses for structure-function relationships in ASCT2. We perform a phylogenetic analysis of the SLC1 family and its prokaryotic homologs to develop a useful multiple sequence alignment for this protein family. We then generate homology models of ASCT2 in two different conformations, based on the human EAAT1 structures. Using ligand enrichment calculations, the ASCT2 models are then compared to crystal structures of various homologs for their utility in discovering ASCT2 inhibitors. We use virtual screening, cellular uptake and electrophysiology experiments to identify a non-amino acid ASCT2 inhibitor that is predicted to interact with the ASCT2 substrate binding site. Our results provide insights into the structural basis of substrate specificity in the SLC1 family, as well as a framework for the design of future selective and potent ASCT2 inhibitors as cancer therapeutics.
AB - The Alanine-Serine-Cysteine transporter (SLC1A5, ASCT2), is a neutral amino acid exchanger involved in the intracellular homeostasis of amino acids in peripheral tissues. Given its role in supplying glutamine to rapidly proliferating cancer cells in several tumor types such as triple-negative breast cancer and melanoma, ASCT2 has been identified as a key drug target. Here we use a range of computational methods, including homology modeling and ligand docking, in combination with cell-based assays, to develop hypotheses for structure-function relationships in ASCT2. We perform a phylogenetic analysis of the SLC1 family and its prokaryotic homologs to develop a useful multiple sequence alignment for this protein family. We then generate homology models of ASCT2 in two different conformations, based on the human EAAT1 structures. Using ligand enrichment calculations, the ASCT2 models are then compared to crystal structures of various homologs for their utility in discovering ASCT2 inhibitors. We use virtual screening, cellular uptake and electrophysiology experiments to identify a non-amino acid ASCT2 inhibitor that is predicted to interact with the ASCT2 substrate binding site. Our results provide insights into the structural basis of substrate specificity in the SLC1 family, as well as a framework for the design of future selective and potent ASCT2 inhibitors as cancer therapeutics.
KW - Cancer metabolism
KW - Glutamine transporter
KW - Homology modeling
KW - SLC1A5
KW - Solute carrier transporter
KW - Structure prediction
KW - Structure-based ligand discovery
UR - http://www.scopus.com/inward/record.url?scp=85053086018&partnerID=8YFLogxK
U2 - 10.3389/fchem.2018.00279
DO - 10.3389/fchem.2018.00279
M3 - Article
AN - SCOPUS:85053086018
SN - 2296-2646
VL - 6
JO - Frontiers in Chemistry
JF - Frontiers in Chemistry
IS - JUL
M1 - 279
ER -