title: LsrR-mediated quorum sensing controls invasiveness of Salmonella typhimurium by regulating SPI-1 and flagella genes.
abstract: Bacterial cell-to-cell communication, termed quorum sensing (QS), controls bacterial behavior by using various signal molecules. Despite the fact that the LuxS/autoinducer-2 (AI-2) QS system is necessary for normal expression of Salmonella pathogenicity island-1 (SPI-1), the mechanism remains unknown. Here, we report that the LsrR protein, a transcriptional regulator known to be involved in LuxS/AI-2-mediated QS, is also associated with the regulation of SPI-1-mediated Salmonella virulence. We determined that LsrR negatively controls SPI-1 and flagella gene expressions. As phosphorylated AI-2 binds to and inactivates LsrR, LsrR remains active and decreases expression of SPI-1 and flagella genes in the luxS mutant. The reduced expression of those genes resulted in impaired invasion of Salmonella into epithelial cells. Expression of SPI-1 and flagella genes was also reduced by overexpression of the LsrR regulator from a plasmid, but was relieved by exogenous AI-2, which binds to and inactivates LsrR. These results imply that LsrR plays an important role in selecting infectious niche of Salmonella in QS dependent mode.
authors.affiliation: Department of Food and Animal Biotechnology, Center for Agricultural Biomaterials, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, Korea.
authors.forename: Jeongjoon
authors.initials: J
authors.lastname: Choi
authors.forename: Dongwoo
authors.initials: D
authors.lastname: Shin
authors.forename: Minjeong
authors.initials: M
authors.lastname: Kim
authors.forename: Joowon
authors.initials: J
authors.lastname: Park
authors.forename: Sangyong
authors.initials: S
authors.lastname: Lim
authors.forename: Sangryeol
authors.initials: S
authors.lastname: Ryu
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D013437:Carbon-Sulfur Lyases / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005407:Flagella / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D046529:Microscopy, Electron, Transmission; D053038:Quorum Sensing / Q000235:genetics / Q000502:physiology*; D060888:Real-Time Polymerase Chain Reaction; D050436:Regulatory Elements, Transcriptional / Q000235:genetics*; D012486:Salmonella typhimurium / Q000378:metabolism / Q000472:pathogenicity* / Q000502:physiology; D014774:Virulence / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics*; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D017931:DNA Primers; C419942:Spi1 protein, Salmonella; D037521:Virulence Factors; D001616:beta-Galactosidase; D013437:Carbon-Sulfur Lyases; C117753:LuxS protein, Bacteria