1. Biochemistry and Chemical Biology
  2. Cell Biology
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Large-scale filament formation inhibits the activity of CTP synthetase

  1. Rachael Barry
  2. Anne-Florence Bitbol
  3. Alexander Lorestani
  4. Emeric J Charles
  5. Chris H Habrian
  6. Jesse M Hansen
  7. Hsin-Jung Li
  8. Enoch P Baldwin
  9. Ned S Wingreen
  10. Justin M Kollman
  11. Zemer Gitai  Is a corresponding author
  1. Princeton University, United States
  2. McGill University, Canada
  3. University of California, Davis, United States
Research Article
  • Cited 54
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Cite this article as: eLife 2014;3:e03638 doi: 10.7554/eLife.03638

Abstract

CTP Synthetase (CtpS) is a universally conserved and essential metabolic enzyme. While many enzymes form small oligomers, CtpS forms large-scale filamentous structures of unknown function in prokaryotes and eukaryotes. By simultaneously monitoring CtpS polymerization and enzymatic activity we show that polymerization inhibits activity and CtpS's product, CTP, induces assembly. To understand how assembly inhibits activity, we used electron microscopy to define the structure of CtpS polymers. This structure suggests that polymerization sterically hinders a conformational change necessary for CtpS activity. Structure-guided mutagenesis and mathematical modeling further indicate that coupling activity to polymerization promotes cooperative catalytic regulation. This previously-uncharacterized regulatory mechanism is important for cellular function since a mutant that disrupts CtpS polymerization disrupts E. coli growth and metabolic regulation without reducing CTP levels. We propose that regulation by large-scale polymerization enables ultrasensitive control of enzymatic activity while storing an enzyme subpopulation in a conformationally restricted form that is readily activatable.

Article and author information

Author details

  1. Rachael Barry

    Princeton University, Princeton, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Anne-Florence Bitbol

    Princeton University, Princeton, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Alexander Lorestani

    Princeton University, Princeton, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. Emeric J Charles

    McGill University, Montreal, Canada
    Competing interests
    The authors declare that no competing interests exist.
  5. Chris H Habrian

    University of California, Davis, Davis, United States
    Competing interests
    The authors declare that no competing interests exist.
  6. Jesse M Hansen

    McGill University, Montreal, Canada
    Competing interests
    The authors declare that no competing interests exist.
  7. Hsin-Jung Li

    Princeton University, Princeton, United States
    Competing interests
    The authors declare that no competing interests exist.
  8. Enoch P Baldwin

    University of California, Davis, Davis, United States
    Competing interests
    The authors declare that no competing interests exist.
  9. Ned S Wingreen

    Princeton University, Princeton, United States
    Competing interests
    The authors declare that no competing interests exist.
  10. Justin M Kollman

    McGill University, Montreal, Canada
    Competing interests
    The authors declare that no competing interests exist.
  11. Zemer Gitai

    Princeton University, Princeton, United States
    For correspondence
    zgitai@princeton.edu
    Competing interests
    The authors declare that no competing interests exist.

Reviewing Editor

  1. Mohan Balasubramanian, University of Warwick, United Kingdom

Publication history

  1. Received: June 9, 2014
  2. Accepted: July 15, 2014
  3. Accepted Manuscript published: July 16, 2014 (version 1)
  4. Version of Record published: August 11, 2014 (version 2)

Copyright

© 2014, Barry 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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