title: Interaction of quorum signals with outer membrane lipids: insights into prokaryotic membrane vesicle formation.
abstract: Bacteria have evolved elaborate communication strategies to co-ordinate their group activities, a process termed quorum sensing (QS). Pseudomonas aeruginosa is an opportunistic pathogen that utilizes QS for diverse activities, including disease pathogenesis. P. aeruginosa has evolved a novel communication system in which the signal molecule 2-heptyl-3-hydroxy-4-quinolone (Pseudomonas Quinolone Signal, PQS) is trafficked between cells via membrane vesicles (MVs). Not only is PQS packaged into MVs, it is required for MV formation. Although MVs are involved in important biological processes aside from signalling, the molecular mechanism of MV formation is unknown. To provide insight into the molecular mechanism of MV formation, we examined the interaction of PQS with bacterial lipids. Here, we show that PQS interacts strongly with the acyl chains and 4'-phosphate of bacterial lipopolysaccharide (LPS). Using PQS derivatives, we demonstrate that the alkyl side-chain and third position hydroxyl of PQS are critical for these interactions. Finally, we show that PQS stimulated purified LPS to form liposome-like structures. These studies provide molecular insight into P. aeruginosa MV formation and demonstrate that quorum signals serve important non-signalling functions.
authors.affiliation: The University of Texas at Austin, Austin, TX 78712, USA.
authors.forename: Lauren
authors.initials: L
authors.lastname: Mashburn-Warren
authors.forename: Jörg
authors.initials: J
authors.lastname: Howe
authors.forename: Patrick
authors.initials: P
authors.lastname: Garidel
authors.forename: Walter
authors.initials: W
authors.lastname: Richter
authors.forename: Frank
authors.initials: F
authors.lastname: Steiniger
authors.forename: Manfred
authors.initials: M
authors.lastname: Roessle
authors.forename: Klaus
authors.initials: K
authors.lastname: Brandenburg
authors.forename: Marvin
authors.initials: M
authors.lastname: Whiteley
mesh_terms: D002462:Cell Membrane / Q000502:physiology* / Q000648:ultrastructure; D020285:Cryoelectron Microscopy; D008070:Lipopolysaccharides / Q000378:metabolism; D008081:Liposomes / Q000378:metabolism; D008563:Membrane Lipids / Q000378:metabolism*; D015394:Molecular Structure; D010743:Phospholipids / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000502:physiology*; D015363:Quinolones / Q000378:metabolism*
chemical_list: C407944:2-heptyl-3-hydroxy-4-quinolone; D008070:Lipopolysaccharides; D008081:Liposomes; D008563:Membrane Lipids; D010743:Phospholipids; D015363:Quinolones