title: An rhl-like quorum-sensing system negatively regulates pyoluteorin production in Pseudomonas sp. M18.
abstract: Pseudomonas sp. M18, isolated from the watermelon rhizosphere, is antagonistic against a number of soil-borne pathogens. This strain produces an uncharacterized red pigment, pyoluteorin (Plt), and two N-acylhomoserine lactones (AHLs). A previously isolated red-pigment-defective mutant, M18-T510, contains an insert within a gene similar to rhlI in P. aeruginosa PAO1. The M18 rhlI gene product is responsible for the production of two AHL signals: N-butyryl-homoserine lactone and N-hexanoylhomoserine lactone. Mutants defective in either rhlI or rhlR showed enhanced Plt biosynthesis due to loss of transcriptional repression, which was mediated, at least in part, by suppressed expression of the activator PltR. A Plt-specific ABC transporter was also upregulated in the rhl mutants in a Plt-dependent manner. In comparison with the wild-type strain, the rhl mutants survived longer during stationary-phase growth.
authors.affiliation: Key Laboratory of Microbial Metabolism, Ministry of Education, College of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, P. R. China.
authors.forename: An
authors.initials: A
authors.lastname: Yan
authors.forename: Xianqing
authors.initials: X
authors.lastname: Huang
authors.forename: Haiming
authors.initials: H
authors.lastname: Liu
authors.forename: Dexian
authors.initials: D
authors.lastname: Dong
authors.forename: Dabing
authors.initials: D
authors.lastname: Zhang
authors.forename: Xuehong
authors.initials: X
authors.lastname: Zhang
authors.forename: Yuquan
authors.initials: Y
authors.lastname: Xu
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives / Q000378:metabolism; D029773:Citrullus / Q000382:microbiology*; D015536:Down-Regulation; D005798:Genes, Bacterial / Q000235:genetics; D008025:Ligases / Q000502:physiology*; D008969:Molecular Sequence Data; D010636:Phenols / Q000378:metabolism*; D018517:Plant Roots / Q000382:microbiology; D011549:Pseudomonas / Q000254:growth & development / Q000378:metabolism*; D011758:Pyrroles / Q000378:metabolism*; D053038:Quorum Sensing / Q000502:physiology*; D014157:Transcription Factors / Q000502:physiology*
chemical_list: C092312:N-butyrylhomoserine lactone; D010636:Phenols; D011758:Pyrroles; D014157:Transcription Factors; C095503:pyoluteorin; D008025:Ligases; C096955:RHLI protein, Pseudomonas aeruginosa; D015107:4-Butyrolactone