Identification of mutants with altered phenazine production in Pseudomonas aeruginosa

Pseudomonas aeruginosa is an opportunistic human pathogen that causes serious and chronic infections. Many secondary metabolites are secreted throughout its growth, among which phenazine is a known virulence factor and signalling molecule. Phenazine is coordinately controlled by the global regulatory quorum-sensing (QS) systems. Despite the detailed understanding of phenazine biosynthesis pathways in P. aeruginosa, the regulatory networks are still not fully clear. In the present study, the regulation of the phzA1B1C1D1E1F1G1 operon (phzA1) has been investigated. Screening of 5000 transposon mutants revealed 14 interrupted genes with altered phzA1 expression, including PA2593 (QteE), which has been identified as a novel regulator of the QS system. Overexpression of qteE in P. aeruginosa significantly reduced the accumulation of homoserine lactone signals and affected the QS-controlled phenotypes such as the production of pyocyanin, rhamnolipids and LasA protease and swarming motility. Indeed, overexpression of qteE in P. aeruginosa attenuated its pathogenicity in the potato and fruit fly infection models. These findings suggest that qteE plays an important role in P. aeruginosa pathogenicity and is part of the regulatory networks controlling phenazine production.