title: LuxS impacts on LytA-dependent autolysis and on competence in Streptococcus pneumoniae.
abstract: The ubiquitous protein LuxS with S-ribosylhomocysteinase activity is involved in S-adenosyl methionine detoxification, C-1 unit recycling and the production of autoinducers that allow the cell to sense and respond to cell density. Independent reports describe the impact of LuxS deficiency on Streptococcus pneumoniae virulence in the mouse. In vitro, LuxS deficiency confers discrete phenotypes. A combined approach using genetic dissection and mixed-culture experiments allowed the involvement of LuxS in the developmental physiology of S. pneumoniae to be investigated. Functional LuxS was found to be related on the one hand to down-regulation of competence, and on the other hand to attenuation of autolysis in cultures entering stationary phase. The competence phenotype of luxS mutant bacteria was complemented by media conditioned by competence-defective ComAB0 bacteria, but not by BSA. The autolytic phenotype was complemented by BSA, but not by conditioned supernatants. It is suggested that the impact of LuxS on competence, but not on autolysis, involves cell-cell communication. The phenotype of luxS mutant strains reveals a hierarchy in the competence regulatory networks of S. pneumoniae.
authors.affiliation: Interactions et Signalisation Cellulaires: Relation Hôte-Pathogène, EA3036, IFR31, CHU Rangueil, Université Paul Sabatier, 31403 Toulouse, France.
authors.forename: Susana
authors.initials: S
authors.lastname: Romao
authors.affiliation: Laboratorio di Microbiologia Molecolare e Biotecnologia, Dipartimento di Biologia Molecolare, Università di Siena, Siena, Italy.
authors.forename: Guido
authors.initials: G
authors.lastname: Memmi
authors.affiliation: UOC Batteriologia, Azienda Ospedaliera Universitaria Senese, Siena, Italy.|Laboratorio di Microbiologia Molecolare e Biotecnologia, Dipartimento di Biologia Molecolare, Università di Siena, Siena, Italy.
authors.forename: Marco R
authors.initials: MR
authors.lastname: Oggioni
authors.affiliation: Interactions et Signalisation Cellulaires: Relation Hôte-Pathogène, EA3036, IFR31, CHU Rangueil, Université Paul Sabatier, 31403 Toulouse, France.
authors.forename: Marie-Claude
authors.initials: MC
authors.lastname: Trombe
mesh_terms: D001329:Autolysis; D001426:Bacterial Proteins / Q000502:physiology*; D013437:Carbon-Sulfur Lyases; D015964:Gene Expression Regulation, Bacterial; D009238:N-Acetylmuramoyl-L-alanine Amidase / Q000502:physiology*; D013296:Streptococcus pneumoniae / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity*; D014169:Transformation, Bacterial
chemical_list: D001426:Bacterial Proteins; D009238:N-Acetylmuramoyl-L-alanine Amidase; D013437:Carbon-Sulfur Lyases; C117753:LuxS protein, Bacteria