title: Role of the Pseudomonas quinolone signal (PQS) in sensitising Pseudomonas aeruginosa to UVA radiation.
abstract: One of the main stress factors that bacteria face in the environment is solar ultraviolet-A (UVA) radiation, which leads to lethal effects through oxidative damage. The aim of this work was to investigate the role of 2-heptyl-3-hydroxi-4-quinolone (the Pseudomonas quinolone signal or PQS) in the response of Pseudomonas aeruginosa to UVA radiation. PQS is an intercellular quorum sensing signal associated to membrane vesicles which, among other functions, regulates genes related to iron acquisition, forms stable complexes with iron and participates in oxidative phenomena. UVA exposure of the wild-type PAO1 strain and a pqsA mutant unable to produce PQS revealed a sensitising role for this signal. Research into the mechanism involved in this phenomenon revealed that catalase, an essential factor in the UVA defence, is not related to PQS-mediated UVA sensitivity. Absorption of UVA by PQS produced its own photo-degradation, oxidation of the probe 2',7'- dichlorodihydrofluorescein and generation of singlet oxygen and superoxide anion, suggesting that this signal could be acting as an endogenous photosensitiser. The results presented in this study could explain the high sensitivity to UVA of P. aeruginosa when compared to enteric bacteria.
authors.affiliation: Comisión Nacional de Energía Atómica, Departamento de Radiobiología, Argentina. Electronic address: pezzoni@cnea.gov.ar.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Pezzoni
authors.affiliation: Comisión Nacional de Energía Atómica, Gerencia de Química, Argentina. Electronic address: meichtry@cnea.gov.ar.
authors.forename: Martín
authors.initials: M
authors.lastname: Meichtry
authors.affiliation: Comisión Nacional de Energía Atómica, Departamento de Radiobiología, Argentina. Electronic address: pizarro@cnea.gov.ar.
authors.forename: Ramón A
authors.initials: RA
authors.lastname: Pizarro
authors.affiliation: Comisión Nacional de Energía Atómica, Departamento de Radiobiología, Argentina. Electronic address: costa@cnea.gov.ar.
authors.forename: Cristina S
authors.initials: CS
authors.lastname: Costa
mesh_terms: D002374:Catalase / Q000378:metabolism; D007501:Iron / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000528:radiation effects; D010782:Photolysis / Q000528:radiation effects; D011550:Pseudomonas aeruginosa / Q000502:physiology*; D015363:Quinolones / Q000737:chemistry / Q000378:metabolism; D053038:Quorum Sensing / Q000528:radiation effects*; D026082:Singlet Oxygen / Q000737:chemistry / Q000378:metabolism; D013481:Superoxides / Q000737:chemistry / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: C407944:2-heptyl-3-hydroxy-4-quinolone; D015363:Quinolones; D013481:Superoxides; D026082:Singlet Oxygen; D007501:Iron; D002374:Catalase