1. Structural Biology and Molecular Biophysics
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Structural basis for mammalian nucleotide sugar transport

  1. Shivani Ahuja
  2. Matthew R Whorton  Is a corresponding author
  1. Oregon Health and Science University, United States
Research Article
  • Cited 12
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Cite this article as: eLife 2019;8:e45221 doi: 10.7554/eLife.45221

Abstract

Nucleotide-sugar transporters (NSTs) are critical components of the cellular glycosylation machinery. They transport nucleotide-sugar conjugates into the Golgi lumen, where they are used for the glycosylation of proteins and lipids, and they then subsequently transport the nucleotide monophosphate byproduct back to the cytoplasm. Dysregulation of human NSTs causes several debilitating diseases, and NSTs are virulence factors for many pathogens. Here we present the first crystal structures of a mammalian NST, the mouse CMP-sialic acid transporter (mCST), in complex with its physiological substrates CMP and CMP-sialic acid. Detailed visualization of extensive protein-substrate interactions explains the mechanisms governing substrate selectivity. Further structural analysis of mCST's unique lumen-facing partially-occluded conformation, coupled with the characterization of substrate-induced quenching of mCST's intrinsic tryptophan fluorescence, reveals the concerted conformational transitions that occur during substrate transport. These results provide a framework for understanding the effects of disease-causing mutations and the mechanisms of this diverse family of transporters.

Data availability

Atomic coordinates and structure factors have been deposited in the Protein Data Bank (PDB) with entries 6OH2, 6OH3, and 6OH4.

The following data sets were generated

Article and author information

Author details

  1. Shivani Ahuja

    Vollum Institute, Oregon Health and Science University, Portland, United States
    Competing interests
    The authors declare that no competing interests exist.

  2. Matthew R Whorton

    Vollum Institute, Oregon Health and Science University, Portland, United States
    For correspondence
    whorton@ohsu.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-9915-7467

Funding

Oregon Health and Science University

  • Shivani Ahuja
  • Matthew R Whorton

National Institutes of Health (R01GM130909)

  • Shivani Ahuja
  • Matthew R Whorton

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Olga Boudker, Weill Cornell Medicine, United States

Publication history

  1. Received: January 17, 2019
  2. Accepted: April 13, 2019
  3. Accepted Manuscript published: April 15, 2019 (version 1)
  4. Version of Record published: May 9, 2019 (version 2)
  5. Version of Record updated: May 15, 2019 (version 3)

Copyright

© 2019, Ahuja & Whorton

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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