1. Biochemistry and Chemical Biology
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Tetramerisation of the CRISPR ring nuclease Crn3/Csx3 facilitates cyclic oligoadenylate cleavage

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Cite this article as: eLife 2020;9:e57627 doi: 10.7554/eLife.57627

Abstract

Type III CRISPR systems detect foreign RNA and activate the cyclase domain of the Cas10 subunit, generating cyclic oligoadenylate (cOA) molecules that act as a second messenger to signal infection, activating nucleases that degrade the nucleic acid of both invader and host. This can lead to dormancy or cell death; to avoid this, cells need a way to remove cOA from the cell once a viral infection has been defeated. Enzymes specialised for this task are known as ring nucleases, but are limited in their distribution. Here, we demonstrate that the widespread CRISPR associated protein Csx3, previously described as an RNA deadenylase, is a ring nuclease that rapidly degrades cyclic tetra-adenylate (cA4). The enzyme has an unusual cooperative reaction mechanism involving an active site that spans the interface between two dimers, sandwiching the cA4 substrate. We propose the name Crn3 (CRISPR associated ring nuclease 3) for the Csx3 family.

Data availability

Diffraction data have been deposited in the PDB under the accession code 6YUD.

The following data sets were generated

Article and author information

Author details

  1. 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.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-1666-0180
  2. Stuart McQuarrie

    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:" 0000-0003-4828-4842
  3. 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.
  4. 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
  5. Tracey M Gloster

    Biology, University of St Andrews, St Andrews, United Kingdom
    For correspondence
    tmg@st-andrews.ac.uk
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-4692-2222
  6. 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 (BB/S000313/1)

  • Sabine Grüschow
  • Shirley Graham
  • Malcolm F White

Biotechnology and Biological Sciences Research Council (BB/T004789/1)

  • Stuart McQuarrie
  • Sabine Grüschow
  • Tracey M Gloster
  • Malcolm F White

Wellcome Trust Institutional Strategic Support Fund (204821/Z/16/Z)

  • Stuart McQuarrie
  • Tracey M Gloster
  • Malcolm F White

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

Reviewing Editor

  1. Joseph T Wade, Wadsworth Center, New York State Department of Health, United States

Publication history

  1. Received: April 6, 2020
  2. Accepted: June 28, 2020
  3. Accepted Manuscript published: June 29, 2020 (version 1)
  4. Version of Record published: July 20, 2020 (version 2)

Copyright

© 2020, Athukoralage 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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