title: Competence pheromone, oligopeptide permease, and induction of competence in Streptococcus pneumoniae.
abstract: An unmodified heptadecapeptide pheromone capable of eliciting competence for genetic transformation in Streptococcus pneumoniae has recently been identified and characterized. In considering possible signal-transduction mechanisms for the peptide, the previously characterized Ami oligopeptide permease and the three highly homologous oligopeptide-binding lipo-proteins. AmiA, AliA, and AliB, appeared to be good candidates for receptors. We therefore compared the spontaneous transformability of Ami, AliA and AliB mutants to that of an isogenic wild-type strain and we investigated the response of the various mutants to treatment with synthetic competence-stimulating peptide (CSP). Our results clearly demonstrate that neither Ami nor any of the three highly homologous oligopeptide-binding lipoproteins identified so far in S. pneumoniae are required for competence induction following treatment with synthetic CSP. Although the existence of a fourth unidentified oligopeptide-binding lipoprotein and/or a second oligopeptide permease operon could not be completely ruled out, we favour the hypothesis that CSP signal transmission rather involves a two-component regulatory system. Although none of the single or double Ami and All mutants tested appeared severely affected for competence, an exceptional aliB plasmid-insertion mutation abolished competence completely. In addition, the triple AmiA-AliA-AliB mutant differed from wild type in showing no sharp peak of competence but exhibiting transformability throughout the exponential phase of growth. These and previous observations are discussed and a general hypothesis is proposed to account for the modulation of competence by peptide permease mutants in S. pneumoniae.
authors.affiliation: Microbiologie et Génétique Moléculaire CNRS-UPR, Université Paul Sabatler, Toulouse, France.
authors.forename: G
authors.initials: G
authors.lastname: Alloing
authors.forename: C
authors.initials: C
authors.lastname: Granadel
authors.forename: D A
authors.initials: DA
authors.lastname: Morrison
authors.forename: J P
authors.initials: JP
authors.lastname: Claverys
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D017353:Gene Deletion; D008074:Lipoproteins / Q000235:genetics* / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000235:genetics / Q000378:metabolism; D010675:Pheromones / Q000235:genetics* / Q000378:metabolism; D013296:Streptococcus pneumoniae / Q000235:genetics* / Q000378:metabolism; D014170:Transformation, Genetic
chemical_list: C088740:AliA protein, Streptococcus pneumoniae; C088715:AliB protein, Streptococcus pneumoniae; D001426:Bacterial Proteins; D002352:Carrier Proteins; C061262:ComA protein, Bacteria; D004268:DNA-Binding Proteins; D008074:Lipoproteins; D026901:Membrane Transport Proteins; D009842:Oligopeptides; D010675:Pheromones