Control of cyclic oligoadenylate synthesis in a type III CRISPR system

Abstract

The CRISPR system for prokaryotic adaptive immunity provides RNA-mediated protection from viruses and mobile genetic elements. When viral RNA transcripts are detected, type III systems adopt an activated state that licenses DNA interference and synthesis of cyclic oligoadenylate (cOA). cOA activates nucleases and transcription factors that orchestrate the antiviral response. We demonstrate that cOA synthesis is subject to tight temporal control, commencing on target RNA binding, and is deactivated rapidly as target RNA is cleaved and dissociates. Mismatches in the target RNA are well tolerated and still activate the cyclase domain, except when located close to the 3' end of the target. Phosphorothioate modification reduces target RNA cleavage and stimulates cOA production. The 'RNA shredding' activity originally ascribed to type III systems may thus be a reflection of an exquisite mechanism for control of the Cas10 subunit, rather than a direct antiviral defence.

Data availability

All data generated or analysed during this study are included in the manuscript and supporting files.

Article and author information

Author details

  1. Christophe Rouillon

    Biomedical Sciences Research Complex, School of Biology, University of St Andrews, St Andrews, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  2. Januka S Athukoralage

    Biomedical Sciences Research Complex, School of Biology, University of St Andrews, St Andrews, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  3. Shirley Graham

    Biomedical Sciences Research Complex, School of Biology, University of St Andrews, St Andrews, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-2608-3815
  4. Sabine Grüschow

    Biomedical Sciences Research Complex, School of Biology, University of St Andrews, St Andrews, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  5. Malcolm F White

    Biomedical Sciences Research Complex, School of Biology, University of St Andrews, St Andrews, United Kingdom
    For correspondence
    mfw2@st-and.ac.uk
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-1543-9342

Funding

Biotechnology and Biological Sciences Research Council (Project grant BB/M000400/1)

  • Christophe Rouillon
  • Malcolm F White

Royal Society (Challenge grant CH160014)

  • Sabine Grüschow

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

Reviewing Editor

  1. Gisela Storz, National Institute of Child Health and Human Development, United States

Publication history

  1. Received: March 16, 2018
  2. Accepted: July 1, 2018
  3. Accepted Manuscript published: July 2, 2018 (version 1)
  4. Version of Record published: July 19, 2018 (version 2)

Copyright

© 2018, Rouillon 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. Christophe Rouillon
  2. Januka S Athukoralage
  3. Shirley Graham
  4. Sabine Grüschow
  5. Malcolm F White
(2018)
Control of cyclic oligoadenylate synthesis in a type III CRISPR system
eLife 7:e36734.
https://doi.org/10.7554/eLife.36734
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