title: RegR, a global LacI/GalR family regulator, modulates virulence and competence in Streptococcus pneumoniae.
abstract: The homolactic and catalase-deficient pathogen Streptococcus pneumoniae is not only tolerant to oxygen but requires the activity of its NADH oxidase, Nox, to develop optimal virulence and competence for genetic transformation. In this work, we show that the global regulator RegR is also involved in these traits. Genetic dissection revealed that RegR regulates competence and the expression of virulence factors, including hyaluronidase. In bacteria grown in vitro, RegR represses hyaluronidase. At neutral pH, it increases adherence to A549 epithelial cells, and at alkaline pH, it acts upstream of the CiaRH two-component signaling system to activate competence. These phenotypes are not associated with changes in antibiotic resistance, central metabolism, and carbohydrate utilization. Although the RegR(0) (where 0 indicates the loss of the protein) mutation is sufficient to attenuate experimental virulence of strain 23477 in mice, the introduction of an additional hyl(0) (where 0 indicates the loss of function) mutation in the RegR(0) strain 23302 dramatically reduces its virulence. This indicates that residual virulence of the RegR(0) Hyl(+) derivative is due to hyaluronidase and supports the dual role of RegR in virulence. This LacI/GalR regulator, not essential for in vitro growth in rich media, is indeed involved in the adaptive response of the pneumococcus via its control of competence, adherence, and virulence.
authors.affiliation: Laboratoire Interactions et Signalisation Cellulaire: Relation Hôte Pathogène, Institut Louis Bugnard, Centre Hospitalo-Universitaire de Rangueil, Université Paul Sabatier, 31403 Toulouse Cedex, France.
authors.forename: Sabine
authors.initials: S
authors.lastname: Chapuy-Regaud
authors.forename: A David
authors.initials: AD
authors.lastname: Ogunniyi
authors.forename: Nicole
authors.initials: N
authors.lastname: Diallo
authors.forename: Yvette
authors.initials: Y
authors.lastname: Huet
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Desnottes
authors.forename: James C
authors.initials: JC
authors.lastname: Paton
authors.forename: Sonia
authors.initials: S
authors.lastname: Escaich
authors.forename: Marie-Claude
authors.initials: MC
authors.lastname: Trombe
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001422:Bacterial Adhesion; D001426:Bacterial Proteins; D050260:Carbohydrate Metabolism; D016680:Genome, Bacterial; D006801:Humans; D006821:Hyaluronoglucosaminidase / Q000096:biosynthesis; D006863:Hydrogen-Ion Concentration; D007769:Lactams; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D013296:Streptococcus pneumoniae / Q000235:genetics / Q000472:pathogenicity*; D014157:Transcription Factors / Q000502:physiology*; D014774:Virulence
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D007769:Lactams; C113722:RegR protein, bacteria; D014157:Transcription Factors; D006821:Hyaluronoglucosaminidase