title: Repressed Quorum sensing by overexpressing LsrR Hampers Salmonella evasion from oxidative killing within macrophages.
abstract: Bacterial cell-to-cell communication, termed quorum sensing (QS), leads to coordinated group behavior in a cell-density-dependent fashion and controls a variety of physiological processes including virulence gene expression. The repressor of the lsr operon, LsrR, is the only known regulator of LuxS/AI-2-mediated QS in Salmonella. Although lack of lsrR did not result in noticeable differences in Salmonella survival, the down-regulation of QS as a result of lsrR overexpression decreased Salmonella survival within macrophages. We found that impaired growth of Salmonella overexpressing lsrR within macrophages was due largely to its hypersensitivity to NADPH-dependent oxidative stress. This, in turn, was a result of decreased expression of genes involved in the oxidative stress response, such as sodA, sodCI, and sodCII, when lsrR was overexpressed. These results suggest that down-regulation of QS by excess LsrR can lower Salmonella virulence by hampering Salmonella evasion from oxidative killing within macrophages.
authors.affiliation: Department of Food and Animal Biotechnology, Seoul National University, Seoul 151-921, Korea.
authors.forename: Jeongjoon
authors.initials: J
authors.lastname: Choi
authors.forename: Joowon
authors.initials: J
authors.lastname: Park
authors.forename: Sangryeol
authors.initials: S
authors.lastname: Ryu
mesh_terms: D017353:Gene Deletion; D005786:Gene Expression Regulation; D008264:Macrophages / Q000382:microbiology*; D050296:Microbial Viability / Q000187:drug effects*; D018384:Oxidative Stress; D053038:Quorum Sensing; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D012486:Salmonella typhimurium / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*; D014774:Virulence
chemical_list: D012097:Repressor Proteins