1. Structural Biology and Molecular Biophysics
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Structural basis of interprotein electron transfer in bacterial sulfite oxidation

  1. Aaron P McGrath
  2. Elise L Laming
  3. G Patricia Casas Garcia
  4. Marc Kvansakul
  5. J Mitchell Guss
  6. Jill Trewhella
  7. Benoit Calmes
  8. Paul V Bernhardt
  9. Graeme R Hanson
  10. Ulrike Kappler
  11. Megan J Maher  Is a corresponding author
  1. University of California, San Diego, United States
  2. The Victor Chang Cardiac Research Institute, Australia
  3. La Trobe University, Australia
  4. University of Sydney, Australia
  5. University of Queensland, Australia
Research Article
  • Cited 14
  • Views 1,075
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Cite this article as: eLife 2015;4:e09066 doi: 10.7554/eLife.09066

Abstract

Interprotein electron transfer underpins the essential processes of life and relies on the formation of specific, yet transient protein-protein interactions. In biological systems, the detoxification of sulfite is catalyzed by the sulfite-oxidizing enzymes (SOEs), which interact with an electron acceptor for catalytic turnover. Here, we report the structural and functional analyses of the SOE SorT from Sinorhizobium meliloti and its cognate electron acceptor SorU. Kinetic and thermodynamic analyses of the SorT/SorU interaction showed the complex is dynamic in solution, and that the proteins interact with Kd = 13.5 {plus minus} 0.8 βM. The crystal structures of the oxidized SorT and SorU both in isolation and in complex, reveal the interface to be remarkably electrostatic, with an unusually large number of direct hydrogen bonding interactions. The assembly of the complex is accompanied by an adjustment in the structure of SorU and conformational sampling provides a mechanism for dissociation of the SorT/SorU assembly.

Article and author information

Author details

  1. Aaron P McGrath

    Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Elise L Laming

    The Victor Chang Cardiac Research Institute, Sydney, Australia
    Competing interests
    The authors declare that no competing interests exist.
  3. G Patricia Casas Garcia

    La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Australia
    Competing interests
    The authors declare that no competing interests exist.
  4. Marc Kvansakul

    La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Australia
    Competing interests
    The authors declare that no competing interests exist.
  5. J Mitchell Guss

    School of Molecular Bioscience, University of Sydney, Sydney, Australia
    Competing interests
    The authors declare that no competing interests exist.
  6. Jill Trewhella

    School of Molecular Bioscience, University of Sydney, Sydney, Australia
    Competing interests
    The authors declare that no competing interests exist.
  7. Benoit Calmes

    Centre for Metals in Biology, University of Queensland, Brisbane, Australia
    Competing interests
    The authors declare that no competing interests exist.
  8. Paul V Bernhardt

    Centre for Metals in Biology, University of Queensland, Brisbane, Australia
    Competing interests
    The authors declare that no competing interests exist.
  9. Graeme R Hanson

    Centre for Metals in Biology, University of Queensland, Brisbane, Australia
    Competing interests
    The authors declare that no competing interests exist.
  10. Ulrike Kappler

    Centre for Metals in Biology, University of Queensland, Brisbane, Australia
    Competing interests
    The authors declare that no competing interests exist.
  11. Megan J Maher

    School of Molecular Bioscience, University of Sydney, New South Wales, Australia
    For correspondence
    m.maher@latrobe.edu.au
    Competing interests
    The authors declare that no competing interests exist.

Reviewing Editor

  1. Michael A Marletta, University of California, Berkeley, United States

Publication history

  1. Received: May 28, 2015
  2. Accepted: November 12, 2015
  3. Accepted Manuscript published: December 19, 2015 (version 1)
  4. Accepted Manuscript updated: December 23, 2015 (version 2)
  5. Version of Record published: February 4, 2016 (version 3)

Copyright

© 2015, McGrath 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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