title: Rga, a RofA-like regulator, is the major transcriptional activator of the PI-2a pilus in Streptococcus agalactiae.
abstract: Rapid adaptation to changing environments is key in determining the outcome of infections caused by the opportunistic human pathogen Streptococcus agalactiae. We previously demonstrated that the RofA-like protein (RALP) regulators RogB and Rga activate their downstream divergently transcribed genes, that is, the pilus operon PI-2a and the serine-rich repeat encoding gene srr1, respectively. Characterization of the Rga regulon by microarray revealed that the PI-2a pilus was strongly controlled by Rga, a result confirmed at the protein level. Complementation experiments showed that the expression of Rga, but not RogB, in the double ΔrogB/Δrga mutant, or in the clinical strain 2603V/R displaying frameshift mutations in rogB and rga genes, is sufficient to restore wild-type expression levels of PI-2a pilus and Srr1. Biofilm formation was impaired in the Δrga and Δrga/rogB mutants and restored on complementation with rga. Paradoxically, adherence to intestinal epithelial cells was unchanged in the Δrga mutant. Finally, the existence of several clinical isolates mutated in rga highlights the concept of strain-specific regulatory networks.
authors.affiliation: Institut Pasteur , Unité de Biologie des Bactéries Pathogènes à Gram-positif, Paris, France. shaynoor.dramsi@pasteur.fr
authors.forename: Shaynoor
authors.initials: S
authors.lastname: Dramsi
authors.forename: Sarah
authors.initials: S
authors.lastname: Dubrac
authors.forename: Yoan
authors.initials: Y
authors.lastname: Konto-Ghiorghi
authors.forename: Violette
authors.initials: V
authors.lastname: Da Cunha
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Couvé
authors.forename: Philippe
authors.initials: P
authors.lastname: Glaser
authors.forename: Elise
authors.initials: E
authors.lastname: Caliot
authors.forename: Michel
authors.initials: M
authors.lastname: Débarbouillé
authors.forename: Samuel
authors.initials: S
authors.lastname: Bellais
authors.forename: Patrick
authors.initials: P
authors.lastname: Trieu-Cuot
authors.forename: Michel-Yves
authors.initials: MY
authors.lastname: Mistou
mesh_terms: D019881:Aminoacyltransferases / Q000235:genetics / Q000378:metabolism; D001422:Bacterial Adhesion / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D018441:Biofilms / Q000254:growth & development; D045744:Cell Line, Tumor; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism; D004847:Epithelial Cells / Q000382:microbiology / Q000473:pathology; D010861:Fimbriae, Bacterial / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D053263:Gene Regulatory Networks; D006801:Humans; D007413:Intestinal Mucosa / Q000382:microbiology / Q000473:pathology; D009154:Mutation; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013292:Streptococcus agalactiae / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins; D014157:Transcription Factors; D019881:Aminoacyltransferases; D003546:Cysteine Endopeptidases