title: Quorum-quenching limits quorum-sensing exploitation by signal-negative invaders.
abstract: Some bacteria produce and perceive quorum-sensing (QS) signals that coordinate several behaviours, including the costly processes that are exoenzyme production and plasmid transfer. In the case of plasmid transfer, the emergence of QS signal-altered invaders and their policing are poorly documented. In Agrobacterium tumefaciens, the virulence Ti-plasmid encodes both synthesis and sensing of QS-signals, which promote its transfer from a donor to a recipient cell. Here, we reported that QS-altered A. tumefaciens mutants arose during experimental evolution. All showed improved growth compared to their ancestor. Genome sequencing revealed that, though some had lost the Ti-plasmid, most were defective for QS-signal synthesis and Ti-plasmid conjugation (traR mutations) and one exhibited a QS-signal exploitation behaviour, using signal produced by other cells to enhance its own Ti-plasmid transfer. We explored mechanisms that can limit this QS-hijacking. We showed that the A. tumefaciens capacity to inactivate QS-signals by expressing QS-degrading enzyme could attenuate dissemination of the QS signal-negative Ti-plasmids. This work shows that enzymatic QS-disruption whether encoded by the QS-producing Ti-plasmid itself, by a companion plasmid in the same donor cells, or by one in the recipient cells, in all cases can serve as a mechanism for controlling QS exploitation by QS signal-negative mutants.
authors.affiliation: Institute for Integrative Biology of the Cell (I2BC), CNRS CEA Univ. Paris-Sud, Université Paris-Saclay, Avenue de la Terrasse, Gif-sur-Yvette 91198, France.
authors.forename: Mélanie
authors.initials: M
authors.lastname: Tannières
authors.affiliation: Institute for Integrative Biology of the Cell (I2BC), CNRS CEA Univ. Paris-Sud, Université Paris-Saclay, Avenue de la Terrasse, Gif-sur-Yvette 91198, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Lang
authors.affiliation: Institute for Integrative Biology of the Cell (I2BC), CNRS CEA Univ. Paris-Sud, Université Paris-Saclay, Avenue de la Terrasse, Gif-sur-Yvette 91198, France.
authors.forename: Claudie
authors.initials: C
authors.lastname: Barnier
authors.affiliation: Ecologie Systématique Evolution, CNRS, Univ. Paris-Sud, AgroParisTech, Université Paris-Saclay, 91400 Orsay, France.
authors.forename: Jacqui A
authors.initials: JA
authors.lastname: Shykoff
authors.affiliation: Institute for Integrative Biology of the Cell (I2BC), CNRS CEA Univ. Paris-Sud, Université Paris-Saclay, Avenue de la Terrasse, Gif-sur-Yvette 91198, France.
authors.forename: Denis
authors.initials: D
authors.lastname: Faure
mesh_terms: D016960:Agrobacterium tumefaciens / Q000235:genetics* / Q000502:physiology*; D004252:DNA Mutational Analysis; D022761:Gene Transfer, Horizontal; D009154:Mutation; D036741:Plant Tumor-Inducing Plasmids / Q000378:metabolism*; D053038:Quorum Sensing; D000073336:Whole Genome Sequencing