A Type IV-A CRISPR-Cas System in <i>Pseudomonas aeruginosa</i> Mediates RNA-Guided Plasmid Interference <i>In Vivo</i>

Abstract

Bacteria and archaea use CRISPR-Cas adaptive immune systems to destroy complementary nucleic acids using RNAs derived from CRISPR loci. Here, we provide the first functional evidence for type IV CRISPR-Cas, demonstrating that the system from <i>Pseudomonas aeruginosa</i> strain PA83 mediates RNA-guided interference against a plasmid <i>in vivo</i>, both clearing the plasmid and inhibiting its uptake. This interference depends on the putative NTP-dependent helicase activity of Csf4/DinG.