L-Arogenate is a chemoattractant which can be utilized as the sole source of carbon and nitrogen by Pseudomonas aeruginosa

Abstract

L-Arogenate is a commonplace amino acid in nature in consideration of its role as a ubiquitous precursor of L-phenylalanine and/or L-tyrpsine. However, the questions of whether it serves as a chemoattractant molecule and whether it can serve as a substrate for catabolism have never been studied. We found that Pseudomonas aeruginosa recognizes L-arogenate as a chemoattractant molecule which can be utilized as a source of both carbon and nitrogen. Mutants lacking expression of either cyclohexadienyl dehydratase or phenylalanine hydroxylase exhibited highly reduced growth rates when utilizing L-arogenate as a nitrogen source. Utilization of L-arogenate as a source of either carbon or nitrogen was dependent upon s54, as revealed by the use of an rpoN null mutant. The evidence suggests that catabolism of L- arogenate proceeds via alternative pathways which converge at 4- hydroxyphenylpyruvate. In one pathway, prephenate formed in the periplasm by deamination of L-arogenate is converted to 4-hydroxyphenylpyruvate by cyclohexadienyl dehydrogenase. The second route depends upon the sequential action of periplasmic cyclohexadienyl dehydratase, phenylalanine hydroxylase, and aromatic aminotransferase.