title: Contribution of the RgfD Quorum Sensing Peptide to rgf Regulation and Host Cell Association in Group B Streptococcus.
abstract: Streptococcus agalactiae(group BStreptococcus; GBS) is a common inhabitant of the genitourinary and/or gastrointestinal tract in up to 40% of healthy adults; however, this opportunistic pathogen is able to breach restrictive host barriers to cause disease and persist in harsh and changing conditions. This study sought to identify a role for quorum sensing, a form of cell to cell communication, in the regulation of the fibrinogen-binding (rgfBDAC) two-component system and the ability to associate with decidualized endometrial cells in vitro. To do this, we created a deletion inrgfD, which encodes the putative autoinducing peptide, in a GBS strain belonging to multilocus sequence type (ST)-17 and made comparisons to the wild type. Sequence variation in thergfoperon was detected in 40 clinical strains and a non-synonymous single nucleotide polymorphism was detected inrgfDin all of the ST-17 genomes that resulted in a truncation. Using qPCR, expression ofrgfoperon genes was significantly decreased in the ST-17ΔrgfDmutant during exponential growth with the biggest difference (3.3-fold) occurring at higher cell densities. Association with decidualized endometrial cells was decreased 1.3-fold in the mutant relative to the wild type andrgfCexpression was reduced 22-fold inΔrgfDfollowing exposure to the endometrial cells. Collectively, these data suggest that this putative quorum sensing molecule is important for attachment to human tissues and demonstrate a role for RgfD in GBS pathogenesis through regulation ofrgfC.
authors.affiliation: Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA. parke274@msu.edu.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Parker
authors.affiliation: Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA. knuppdav@msu.edu.
authors.forename: David
authors.initials: D
authors.lastname: Knupp
authors.affiliation: Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA. rimalsafadi@gmail.com.
authors.forename: Rim
authors.initials: R
authors.lastname: Al Safadi
authors.affiliation: Infectiologie et Santé Publique ISP, Institut National de la Recherche Agronomique, Université de Tours, Equipe Bactéries et Risque Materno-fœtal, UMR1282 Tours, France. rosenau@univ-tours.fr.
authors.forename: Agnѐs
authors.initials: A
authors.lastname: Rosenau
authors.affiliation: Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA. mannin71@msu.edu.
authors.forename: Shannon D
authors.initials: SD
authors.lastname: Manning
keywords: Streptococcus agalactiae; colonization; group B Streptococcus; quorum sensing