PA5339, a RidA Homolog, Is Required for Full Growth in Pseudomonas aeruginosa.

Abstract

The Rid protein superfamily (YjgF/YER057c/UK114) is found in all domains of life. The archetypal protein, RidA from Salmonella enterica, is a deaminase that quenches the reactive metabolite 2-aminoacrylate (2AA). 2AA deaminase activity is conserved in RidA proteins from humans, plants, yeast, archaea, and bacteria. Mutants of Salmonella enterica, Escherichia coli, and Saccharomyces cerevisiae that lack a functional RidA exhibit growth defects, suggesting that 2AA metabolic stress is similarly conserved. The PubSEED database shows Pseudomonas aeruginosa (PAO1) encodes eight members of the Rid superfamily. Mutants of P. aeruginosa PAO1 lacking each of five Rid proteins were screened, and the mutant phenotypes that arose in the absence of PA5339 were dissected. A PA5339::Tn mutant has growth, motility, and biofilm defects that can all be linked to the accumulation of 2AA. Further, the PA5339 protein was demonstrably a 2AA deaminase in vitro and restored metabolic balance to a S. enterica ridA mutant in vivo The data presented here show that the RidA paradigm in Pseudomonas aeruginosa had similarities to those described in other organisms but was distinct in that deleting only one of multiple homologs generated deficiencies. Based on the collective data presented here in, PA5339 was renamed RidA.IMPORTANCE RidA is a widely conserved protein that prevents endogenous metabolic stress caused by 2-aminoacrylate (2AA) damage to pyridoxal 5'-phosphate (PLP)-dependent enzymes in prokaryotes and eukaryotes. The framework for understanding the accumulation of 2AA and its consequences have largely been defined in Salmonella enterica We show here that in P. aeruginosa (PAO1), 2AA accumulation leads to reduced growth, compromised motility, and defective biofilm formation. This study expands our knowledge how the metabolic architecture of an organism contributes to the consequences of 2AA inactivation of PLP-dependent enzymes and identifies a key RidA protein in P. aeruginosa.