Computational Detection of CRISPR/crRNA Targets.

The CRISPR-Cas systems in bacteria and archaea provide protection by targeting foreign nucleic acids. The sequence of the "spacers" within CRISPR arrays specifically determines the targets in invader genomes. These spacers provide the short specific RNA nucleotide sequences within the guide crRNAs. In addition to complementarity in the spacer-target (protospacer) interaction, short flanking protospacer adjacent motifs (PAMs), or mismatching flanks have a discriminatory role in accurate target detection. Here, we describe a bioinformatic method, called CRISPRTarget, to use the sequence of a CRISPR array (e.g., predicted via CRISPRDetect/CRISPRDirection) to identify the foreign nucleic acids it targets.