Fig. 1: A spacer that targets the acr gene provides phage resistance and leads to selection of phage-escaping mutants (CEM) containing a deleted acr gene.
From: A truncated anti-CRISPR protein prevents spacer acquisition but not interference
a Titers of phages carrying no ACR (phage 2972 in blue) or AcrIIA5 (D1126 in red) or AcrIIA6 (D3288 in green), on four S. thermophilus strains, namely the phage-sensitive strain DGCC7710, strain SMQ-1335-b containing a spacer in its CR1 array perfectly matching a conserved region in the three phage genomes, strain BIM-D1126ACR containing a spacer matching the acrIIA5 gene of phage D1126, and strain BIM-D3288ACR containing a spacer matching the acrIIA6 gene of phage D3288. The BIMs carrying a spacer targeting an acr gene provided a significant phage resistance phenotype (lower phage titers). The titers are from three biological replicates and each of two technical replicates. Error bars represent standard deviation. b PCR analyses on phage lysates based on the amplification of phage D1126 infecting the BIM that targets its acr (BIM-D1126ACR). The acr gene was amplified by PCR after two rounds of phage amplification. The gel shows deleted (lanes 2–4) and full-length (lane 5) PCR products for the acr in the CEM and wild-type phage D1126, respectively. c Nucleotide sequence alignment of the deleted and wild-type acr genes (PCR products) shows deletions within the targeted protospacer region.
