Priming in the Type I-F CRISPR-Cas system triggers strand-independent spacer acquisition, bi-directionally from the primed protospacer.

ABSTRACT: Clustered regularly interspaced short palindromic repeats (CRISPR), in combination with CRISPR associated (cas) genes, constitute CRISPR-Cas bacterial adaptive immune systems. To generate immunity, these systems acquire short sequences of nucleic acids from foreign invaders and incorporate these into their CRISPR arrays as spacers. This adaptation process is the least characterized step in CRISPR-Cas immunity. Here, we used Pectobacterium atrosepticum to investigate adaptation in Type I-F CRISPR-Cas systems. Pre-existing spacers that matched plasmids stimulated hyperactive primed acquisition and resulted in the incorporation of up to nine new spacers across all three native CRISPR arrays. Endogenous expression of the cas genes was sufficient, yet required, for priming. The new spacers inhi

SUBMITTER: Richter C 

PROVIDER: S-EPMC4117759 | biostudies-literature | 2014 Jul

REPOSITORIES: biostudies-literature