PT  - JOURNAL ARTICLE
AU  - Garibsingh, Rachel-Ann A.
AU  - Ndaru, Elias
AU  - Garaeva, Alisa A.
AU  - Bonomi, Massimiliano
AU  - Slotboom, Dirk J.
AU  - Paulino, Cristina
AU  - Grewer, Christof
AU  - Schlessinger, Avner
TI  - Structural basis for stereospecific inhibition of ASCT2 from rational design
AID  - 10.1101/2020.05.29.124305
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.05.29.124305
4099  - http://biorxiv.org/content/early/2020/05/31/2020.05.29.124305.short
4100  - http://biorxiv.org/content/early/2020/05/31/2020.05.29.124305.full
AB  - ASCT2 (SLC1A5) is a sodium-dependent neutral amino acid transporter that controls amino acid homeostasis in peripheral tissues. ASCT2 is upregulated in cancer, where it modulates intracellular glutamine levels, fueling cell proliferation. Nutrient deprivation via ASCT2 inhibition provides an emerging strategy for cancer therapy. Here, guided by a homology model of ASCT2 in an outward-facing conformation, we rationally designed novel inhibitors exploiting stereospecific pockets in the substrate binding site. A cryo-EM structure of ASCT2 in complex with inhibitor (Lc-BPE) validated our predictions and was subsequently refined based on computational analysis. The final structures, combined with MD simulations, show that the inhibitor samples multiple conformations in the ASCT2 binding site. Our results demonstrate the utility of combining computational modeling and cryo-EM for SLC ligand discovery, and a viable strategy for structure determination of druggable conformational states for challenging membrane protein targets.Competing Interest StatementAvner Schlessinger is the Co-Founder of AIchemy.