Oligoribonuclease is a central feature of cyclic diguanylate signaling in Pseudomonas aeruginosa

Many bacteria possess enzymes that synthesize and degrade the intracellular second messenger cyclic diguanylate (c-di-GMP). Bacteria use this molecule to relay environmental signals into physiological responses that control motility, virulence, and biofilm formation. There are two pathways for enzymatic c-di-GMP degradation. One of these pathways involves the production of an intermediate molecule called 5ʹ-phosphoguanylyl-(3ʹ,5&#697)-guanosine (pGpG). Although many enzymes responsible for c-di-GMP degradation have been characterized, microbiologists have long sought those responsible for pGpG degradation. Here we identify that oligoribonuclease (Orn) mediates pGpG degradation and show that Orn is important for c-di-GMP signaling in the human pathogen Pseudomonas aeruginosa. This discovery reveals that nanoribonucleases, which have been considered housekeeping proteins crucial for mRNA turnover, also have a key role in c-di-GMP signaling.