Competence pheromone, oligopeptide permease, and induction of competence in Streptococcus pneumoniae

Mol Microbiol. 1996 Aug;21(3):471-8. doi: 10.1111/j.1365-2958.1996.tb02556.x.


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.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism
  • Carrier Proteins / genetics*
  • Carrier Proteins / metabolism
  • DNA-Binding Proteins / genetics*
  • DNA-Binding Proteins / metabolism
  • Gene Deletion
  • Lipoproteins / genetics*
  • Lipoproteins / metabolism
  • Membrane Transport Proteins / genetics*
  • Molecular Sequence Data
  • Oligopeptides / genetics
  • Oligopeptides / metabolism
  • Pheromones / genetics*
  • Pheromones / metabolism
  • Streptococcus pneumoniae / genetics*
  • Streptococcus pneumoniae / metabolism
  • Transformation, Genetic


  • AliA protein, Streptococcus pneumoniae
  • AliB protein, Streptococcus pneumoniae
  • Bacterial Proteins
  • Carrier Proteins
  • ComA protein, Bacteria
  • DNA-Binding Proteins
  • Lipoproteins
  • Membrane Transport Proteins
  • Oligopeptides
  • Pheromones

Associated data

  • GENBANK/Z15136