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.

The following data sets were generated

Article and author information

Author details

  1. Xiaodi Yu

    Medicine Design, Pfizer Inc, Groton, United States
    Competing interests
    Xiaodi Yu, is affiliated with Pfizer Inc. The author has no other competing interests to declare..
  2. Olga Plotnikova

    Medicine Design, Pfizer Inc, Groton, United States
    Competing interests
    Olga Plotnikova, is affiliated with Pfizer Inc. The author has no other competing interests to declare..
  3. Paul D Bonin

    Medicine Design, Pfizer Inc, Groton, United States
    Competing interests
    Paul D Bonin, is affiliated with Pfizer Inc. The author has no other competing interests to declare..
  4. Timothy A Subashi

    Medicine Design, Pfizer Inc, Groton, United States
    Competing interests
    Timothy A Subashi, is affiliated with Pfizer Inc. The author has no other competing interests to declare..
  5. Thomas J McLellan

    Medicine Design, Pfizer Inc, Groton, United States
    Competing interests
    Thomas J McLellan, is affiliated with Pfizer Inc. The author has no other competing interests to declare..
  6. Darren Dumlao

    Medicine Design, Pfizer Inc, Groton, United States
    Competing interests
    Darren Dumlao, is affiliated with Pfizer Inc. The author has no other competing interests to declare..
  7. Ye Che

    Medicine Design, Pfizer Inc, Groton, United States
    Competing interests
    Ye Che, is affiliated with Pfizer Inc. The author has no other competing interests to declare..
  8. Yin Yao Dong

    Structural Genomics Consortium, University of Oxford, Oxford, United Kingdom
    Competing interests
    No competing interests declared.
  9. Elisabeth P Carpenter

    Structural Genomics Consortium, University of Oxford, Oxford, United Kingdom
    Competing interests
    No competing interests declared.
  10. Graham M West

    Medicine Design, Pfizer Inc, Groton, United States
    Competing interests
    Graham M West, is affiliated with Pfizer Inc. The author has no other competing interests to declare..
  11. Xiayang Qiu

    Medicine Design, Pfizer Inc, Groton, United States
    Competing interests
    Xiayang Qiu, is affiliated with Pfizer Inc. The author has no other competing interests to declare..
  12. Jeffrey S Culp

    Medicine Design, Pfizer Inc, Groton, United States
    Competing interests
    Jeffrey S Culp, is affiliated with Pfizer Inc. The author has no other competing interests to declare..
  13. Seungil Han

    Medicine Design, Pfizer Inc, Groton, United States
    For correspondence
    seungil.han@pfizer.com
    Competing interests
    Seungil Han, is affiliated with Pfizer Inc. The author has no other competing interests to declare..
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-1070-3880

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.

Reviewing Editor

  1. Lucy Forrest, National Institute of Neurological Disorders and Stroke, United States

Version history

  1. Received: May 1, 2019
  2. Accepted: October 2, 2019
  3. Accepted Manuscript published: October 3, 2019 (version 1)
  4. Version of Record published: October 18, 2019 (version 2)

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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  1. Xiaodi Yu
  2. Olga Plotnikova
  3. Paul D Bonin
  4. Timothy A Subashi
  5. Thomas J McLellan
  6. Darren Dumlao
  7. Ye Che
  8. Yin Yao Dong
  9. Elisabeth P Carpenter
  10. Graham M West
  11. Xiayang Qiu
  12. Jeffrey S Culp
  13. Seungil Han
(2019)
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

Share this article

https://doi.org/10.7554/eLife.48120

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