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Nature. 2016 Apr 21;532(7599):385-8. doi: 10.1038/nature17436. Epub 2016 Apr 13.

The diversity-generating benefits of a prokaryotic adaptive immune system.

Author information

1
ESI and CEC, Biosciences, University of Exeter, Cornwall Campus, Penryn TR10 9EZ, UK.
2
CEFE UMR 5175, CNRS-Université de Montpellier, Université Paul-Valéry Montpellier, EPHE, 1919, route de Mende 34293, Montpellier Cedex 5, France.
3
Department of Integrative Biology, University of California, Berkeley, California 94720, USA.
4
CEC, Biosciences, University of Exeter, Cornwall Campus, Penryn TR10 9EZ, UK.
5
Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, California 94158, USA.
6
Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK.

Abstract

Prokaryotic CRISPR-Cas adaptive immune systems insert spacers derived from viruses and other parasitic DNA elements into CRISPR loci to provide sequence-specific immunity. This frequently results in high within-population spacer diversity, but it is unclear if and why this is important. Here we show that, as a result of this spacer diversity, viruses can no longer evolve to overcome CRISPR-Cas by point mutation, which results in rapid virus extinction. This effect arises from synergy between spacer diversity and the high specificity of infection, which greatly increases overall population resistance. We propose that the resulting short-lived nature of CRISPR-dependent bacteria-virus coevolution has provided strong selection for the evolution of sophisticated virus-encoded anti-CRISPR mechanisms.

PMID:
27074511
PMCID:
PMC4935084
DOI:
10.1038/nature17436
[Indexed for MEDLINE]
Free PMC Article

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