Sigma X induces competence gene expression in Streptococcus pyogenes

Res Microbiol. 2006 Nov;157(9):851-6. doi: 10.1016/j.resmic.2006.07.002. Epub 2006 Aug 18.


Although not thought to become competent for DNA uptake, the bacterium Streptococcus pyogenes appears to encode within its genome the DNA uptake and recombination machinery required for competence. The promoters of these genes contain a conserved sequence, CIN-box, which is recognized by the S. pyogenes alternative RNA polymerase sigma factor X. Using microarray technology, we found that sigma X induced the expression of competence genes in S. pyogenes. Real-time RT-PCR was performed to confirm that the expression of these transcripts was induced 2-265-fold by sigma X. Of the eight CIN-box loci induced, femB, the ortholog a virulence factor in Staphylococcus aureus, was shown to be transcribed in vitro by RNA polymerase containing sigma X, indicating that sigma X directly activates expression of this CIN-box gene. Sigma X-dependent induction of genes encoding competence machinery in S. pyogenes raises the possibility that some strains of this human pathogen can develop competence for genetic transformation.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Bacillus subtilis / genetics
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism
  • Binding Sites / genetics
  • Gene Expression Regulation, Bacterial / genetics*
  • Genes, Bacterial / genetics
  • Oligonucleotide Array Sequence Analysis
  • Promoter Regions, Genetic / genetics
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sigma Factor / genetics*
  • Sigma Factor / metabolism
  • Streptococcus pneumoniae / genetics
  • Streptococcus pyogenes / genetics*
  • Transcription, Genetic / genetics


  • Bacterial Proteins
  • Sigma Factor