Phages can use ACR proteins that inhibit the adaptive immunity activities of bacterial CRISPR-Cas systems. Here, Philippe et al. show that these systems can block ACR-containing phages by targeting the acr gene, and this can select for phage mutants carrying a deletion within acr that does not block DNA cleavage (interference) but prevents the addition of new immunity (spacer acquisition).
- Cécile Philippe
- Carlee Morency
- Sylvain Moineau
