Cell Host & Microbe
Volume 27, Issue 2, 12 February 2020, Pages 189-198.e6
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Article
Exploitation of the Cooperative Behaviors of Anti-CRISPR Phages

https://doi.org/10.1016/j.chom.2019.12.004Get rights and content
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Highlights

  • Acr-positive phages limit evolution of CRISPR resistance during clonal and mixed infections

  • Acr-positive phages provide benefits to Acr-negative phages present in the community

  • Strong Acr help Acr-negative phages to amplify on immunosuppressed CRISPR-resistant cells

  • Weaker Acr provides larger advantages during competition with Acr-negative phages

Summary

Bacteriophages encoding anti-CRISPR proteins (Acrs) must cooperate to overcome phage resistance mediated by the bacterial immune system CRISPR-Cas, where the first phage blocks CRISPR-Cas immunity in order to allow a second Acr phage to successfully replicate. However, in nature, bacteria are frequently not pre-immunized, and phage populations are often not clonal, exhibiting variations in Acr presence and strength. We explored how interactions between Acr phages and initially sensitive bacteria evolve, both in the presence and absence of competing phages lacking Acrs. We find that Acr phages benefit “Acr-negative” phages by limiting the evolution of CRISPR-based resistance and helping Acr-negative phages to replicate on resistant host sub-populations. These benefits depend on the strength of CRISPR-Cas inhibitors and result in strong Acrs providing smaller fitness advantages than weaker ones when Acr phages compete with Acr-negative phages. These results indicate that different Acr types shape the evolutionary dynamics and social interactions of phage populations in natural communities.

Keywords

bacteriophages
anti-CRISPR
CRISPR-Cas
experimental evolution
cooperation
exploitation

Cited by (0)

4

Present address: MRC Laboratory for Molecular Cell Biology, University College London, London, UK

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Lead Contact