title: Quorum sensing enhancement of the stress response promotes resistance to quorum quenching and prevents social cheating.
abstract: Quorum sensing (QS) coordinates the expression of virulence factors and allows bacteria to counteract the immune response, partly by increasing their tolerance to the oxidative stress generated by immune cells. Despite the recognized role of QS in enhancing the oxidative stress response, the consequences of this relationship for the bacterial ecology remain unexplored. Here we demonstrate that QS increases resistance also to osmotic, thermal and heavy metal stress. Furthermore a QS-deficient lasR rhlR mutant is unable to exert a robust response against H2O2 as it has less induction of catalase and NADPH-producing dehydrogenases. Phenotypic microarrays revealed that the mutant is very sensitive to several toxic compounds. As the anti-oxidative enzymes are private goods not shared by the population, only the individuals that produce them benefit from their action. Based on this premise, we show that in mixed populations of wild-type and the mexR mutant (resistant to the QS inhibitor furanone C-30), treatment with C-30 and H2O2 increases the proportion of mexR mutants; hence, oxidative stress selects resistance to QS compounds. In addition, oxidative stress alone strongly selects for strains with active QS systems that are able to exert a robust anti oxidative response and thereby decreases the proportion of QS cheaters in cultures that are otherwise prone to invasion by cheats. As in natural environments stress is omnipresent, it is likely that this QS enhancement of stress tolerance allows cells to counteract QS inhibition and invasions by social cheaters, therefore having a broad impact in bacterial ecology.
authors.affiliation: Biochemistry Department, National Institute of Cardiology, Mexico City, Mexico.
authors.forename: Rodolfo
authors.initials: R
authors.lastname: García-Contreras
authors.affiliation: Biochemistry Department, National Institute of Cardiology, Mexico City, Mexico.
authors.forename: Leslie
authors.initials: L
authors.lastname: Nuñez-López
authors.affiliation: Biochemistry Department, National Institute of Cardiology, Mexico City, Mexico.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Jasso-Chávez
authors.affiliation: Department of Chemical Engineeringy, Pennsylvania State University, University Park, PA, USA.
authors.forename: Brian W
authors.initials: BW
authors.lastname: Kwan
authors.affiliation: Biochemistry Department, National Institute of Cardiology, Mexico City, Mexico.
authors.forename: Javier A
authors.initials: JA
authors.lastname: Belmont
authors.affiliation: Internal Medicine Department, Speciality Hospital, National Medical Center 'Siglo XXI', IMSS, Mexico City, Mexico.
authors.forename: Adrián
authors.initials: A
authors.lastname: Rangel-Vega
authors.affiliation: Department of Biological Functions Engineering, Kyushu Institute of Technology, Kitakyushu, Japan.
authors.forename: Toshinari
authors.initials: T
authors.lastname: Maeda
authors.affiliation: 1] Department of Chemical Engineeringy, Pennsylvania State University, University Park, PA, USA [2] Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, USA.
authors.forename: Thomas K
authors.initials: TK
authors.lastname: Wood
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D005663:Furans / Q000494:pharmacology; D009154:Mutation; D018384:Oxidative Stress / Q000235:genetics; D011550:Pseudomonas aeruginosa / Q000201:enzymology / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D053038:Quorum Sensing / Q000187:drug effects / Q000235:genetics; D037521:Virulence Factors / Q000378:metabolism
chemical_list: D000975:Antioxidants; D005663:Furans; D037521:Virulence Factors; C494198:furanone C-30