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Crystal structure of a phosphorylation-coupled vitamin C transporter

Nature Structural & Molecular Biology volume 22, pages 238241 (2015) | Download Citation

Abstract

Bacteria use vitamin C (L-ascorbic acid) as a carbon source under anaerobic conditions. The phosphoenolpyruvate-dependent phosphotransferase system (PTS), comprising a transporter (UlaA), a IIB-like enzyme (UlaB) and a IIA-like enzyme (UlaC), is required for the anaerobic uptake of vitamin C and its phosphorylation to L-ascorbate 6-phosphate. Here, we present the crystal structures of vitamin C–bound UlaA from Escherichia coli in two conformations at 1.65-Å and 2.35-Å resolution. UlaA forms a homodimer and exhibits a new fold. Each UlaA protomer consists of 11 transmembrane segments arranged into a ‘V-motif’ domain and a ‘core’ domain. The V motifs form the interface between the two protomers, and the core-domain residues coordinate vitamin C. The alternating access of the substrate from the opposite side of the cell membrane may be achieved through rigid-body rotation of the core relative to the V motif.

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Acknowledgements

We thank Shanghai Synchrotron Radiation Source for access to beamline BL17U, SPring-8 for access to beamline BL41XU and the Brookhaven National Synchrotron Light Source for access to beamline X29A. We thank N. Yan and E. Coutavas for discussion and comments on the manuscript and D. King (University of California, Berkeley) for MS analysis. This work was supported by funds from the Ministry of Science and Technology of China (grant nos. 2011CB911102 and 2015CB910104), Tsinghua University 985 Phase II funds, National Natural Science Foundation of China (31321062) and Beijing Municipal Commissions of Education and Science and Technology to J.W. We acknowledge the China National Center for Protein Sciences, Beijing, for providing the facility support. X.L. is supported as the Gordon and Betty Moore Foundation Fellow of the Life Sciences Research Foundation.

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Author notes

    • Ping Luo
    •  & Xinzhe Yu

    These authors contributed equally to this work.

Affiliations

  1. State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Life Sciences, Tsinghua University, Beijing, China.

    • Ping Luo
    • , Weiguang Wang
    •  & Jiawei Wang
  2. Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China.

    • Ping Luo
    • , Xinzhe Yu
    • , Weiguang Wang
    • , Shilong Fan
    •  & Jiawei Wang
  3. Ministry of Education Key Laboratory of Protein Science, School of Life Sciences, Tsinghua University, Beijing, China.

    • Xinzhe Yu
  4. Laboratory of Cell Biology, Rockefeller University, New York, New York, USA.

    • Xiaochun Li

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Contributions

P.L., X.Y., X.L. and J.W. designed all experiments. P.L., X.Y., W.W., S.F. and X.L. performed the experiments. All authors analyzed the data. P.L., X.Y., X.L. and J.W. contributed to manuscript preparation. J.W. wrote the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Xiaochun Li or Jiawei Wang.

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https://doi.org/10.1038/nsmb.2975

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