Influence of ptsP gene on pyocyanin production in Pseudomonas aeruginosa

A pyocyanin overproducer with insertional inactivation of ptsP gene was isolated from a mini-Mu insertion library in Pseudomonas aeruginosa PA68. The mutation was complemented by a functional ptsP gene in trans. The pyocyanin-overproducing phenotype was also found in a ptsP mutant constructed by gene replacement in the P. aeruginosa PAO1 strain. Reporter plasmids with P-qscR-lacZ, P-las-IacZ and P-rhlI-lacZ were constructed and the beta-galactosidase activity in the ptsP mutant/wild-type background was measured. The results showed that lack of Enzyme I-Ntr (EINtr, encoded by ptsP) decreased transcription from the P-qscR promoter and increased the activity of the Plas, and P-rhlI promoters. Normally, QscR represses the quorum-sensing LasR-LasI and RhlR-RhlI systems involved in pyocyanin regulation. Our results showed that the ptsP gene has an important role in the regulation of pyocyanin production and that two quorum-sensing systems and their repressor QscR are involved in this regulation. (c) 2005 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.