title: The roles of the quorum-sensing system in the release of extracellular DNA, lipopolysaccharide, and membrane vesicles from Pseudomonas aeruginosa.
abstract: Biofilms play an important role in the establishment of chronic infection caused by Pseudomonas aeruginosa. It has been suggested that membrane vesicles (MVs) are released into the surrounding medium during normal growth and might supply the bacterial extracellular DNA that is required for early biofilm formation, as MVs released from the bacterial outer membrane are suspected to be the source of extracellular DNA. MVs possess lipopolysaccharide (LPS), extracellular DNA, and several hydrolytic enzymes. It is well known that the quorum-sensing (QS) system is important in controlling virulence factors in P. aeruginosa and biofilm formation. In the current study, we investigated extracellular LPS and DNA in the supernatants of culture solutions from PAO1, the wild-type P. aeruginosa, and those of QS mutants. As compared to that of las QS mutants, the amount of LPS and DNA released was significantly higher in PAO1 and in las QS mutants complemented with N-(3-oxododecanoyl) homoserine lactone. Our study indicated that the QS is among the regulators involved in the release of extracellular DNA and LPS. It is possible that these extracellular components are supplied from MVs. Investigation of the mechanism of biofilm formation is of particular interest, as it may be useful for designing treatments for severe P. aeruginosa infection.
authors.affiliation: Second Department of Internal Medicine, Nagasaki University Graduate School of Medical Science, Nagasaki 852-8501, Japan.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Nakamura
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Higashiyama
authors.forename: Koichi
authors.initials: K
authors.lastname: Izumikawa
authors.forename: Masafumi
authors.initials: M
authors.lastname: Seki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kakeya
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Katsunori
authors.initials: K
authors.lastname: Yanagihara
authors.forename: Yoshitsugu
authors.initials: Y
authors.lastname: Miyazaki
authors.forename: Yohei
authors.initials: Y
authors.lastname: Mizuta
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kohno
mesh_terms: D018441:Biofilms / Q000254:growth & development; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure*; D004269:DNA, Bacterial / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D008070:Lipopolysaccharides / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D011550:Pseudomonas aeruginosa / Q000254:growth & development* / Q000648:ultrastructure; D053038:Quorum Sensing; D022161:Transport Vesicles / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D004269:DNA, Bacterial; D008070:Lipopolysaccharides