FIG. 2.

Cas1–2/3 acquire mostly PAM-flanked spacers, but Csy increases the fidelity of PAM selection. (A) Sequence context of protospacers for spacers acquired through Cas1–2/3 slipping. (B–D) Percentages of 31, 32, and 33 bp protospacers that uniquely map to pCas1–2/3 and were acquired through different categories of Cas1-/3 slipping. Spacers that produced more than one alignment to the genome or cas gene expression plasmids were not included in this analysis. Significances of T-tests performed for biological replicates between each condition are denoted as asterisks (N.S.: p > 0.05, *p ≤ 0.05, **p ≤ 0.01, ****p ≤ 0.0001).