Cryo-EM structures of the human glutamine transporter SLC1A5 (ASCT2) in the outward-facing conformation
- Pfizer Inc, United States
- University of Oxford, United Kingdom
Abstract
Alanine-serine-cysteine transporter 2 (ASCT2, SLC1A5) is the primary transporter of glutamine in cancer cells and regulates the mTORC1 signaling pathway. The SLC1A5 function involves finely tuned orchestration of two domain movements that include the substrate-binding transport domain and the scaffold domain. Here, we present cryo-EM structures of human SLC1A5 and its complex with the substrate, L-glutamine in an outward-facing conformation. These structures reveal insights into the conformation of the critical ECL2a loop which connects the two domains, thus allowing rigid body movement of the transport domain throughout the transport cycle. Furthermore, the structures provide new insights into substrate recognition, which involves conformational changes in the HP2 loop. A putative cholesterol binding site was observed near the domain interface in the outward-facing state. Comparison with the previously determined inward-facing structure of SCL1A5 provides a basis for a more integrated understanding of substrate recognition and transport mechanism in the SLC1 family.
Data availability
All the cryo-EM data were deposited to the Protein Data Bank (PDB ID: 6MP6, 6MPB) and the EMDB (EMD-9187, EMD-9188) for immediate release upon publication.
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SLC1A5_cKM4012Protein Data Bank, 6MP6.
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SLC1A5_cKM4012_L_GlnProtein Data Bank, 6MPB.
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SLC1A5_cKM4012Electron Microscopy Data Bank, EMD-9187.
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SLC1A5_cKM4012_L_GlnElectron Microscopy Data Bank, EMD-9188.
Article and author information
Author details
Funding
Y.D. and E.P.C. are members of the SGC, (Charity ref: 1097737) funded by AbbVie, Bayer Pharma AG, Boehringer Ingelheim, the Canada Foundation for Innovation, Genome Canada, GlaxoSmithKline, Janssen, Lilly Canada, Merck & Co., Novartis, the Ontario Ministry of Economic Development and Innovation, Pfizer, São Paulo Research Foundation-FAPESP and Takeda, as well as the Innovative Medicines Initiative Joint Undertaking ULTRA-DD grant 115766 and the Wellcome Trust106169/Z/14/Z.
Copyright
© 2019, Yu et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Cryo-EM structures of the human glutamine transporter SLC1A5 (ASCT2) in the outward-facing conformation
eLife 8:e48120.
https://doi.org/10.7554/eLife.48120
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