CRISPR control of virulence in Pseudomonas aeruginosa

Abstract

Clustered regularly interspaced short palindromic repeats (CRISPR) and their associated genes (cas) are essential components of an adaptive immune system that protects bacteria and archaea from viral infection. Now a recent paper published in Cell Research suggests that the Type I-F immune system in Pseudomonas aeruginosa may also be involved in post-transcriptional regulation of virulence.

Figure 1

DNA targeting controls viral infection, while RNA targeting controls expression of virulence genes. DNA binding by the CRISPR RNA-guided surveillance complex (Cascade I-F or Csy) relies on recognition of a double-stranded PAM and base pairing at the seed. Binding to the lasR mRNA requires base pairing at the opposite end of the crRNA, a region called the “core”, and recognition of a single-stranded PAM-like sequence. In both cases, target binding recruits Cas3 for degradation.