Physiological and molecular characterization of genetic competence in Streptococcus sanguinis

Mol Oral Microbiol. 2011 Apr;26(2):99-116. doi: 10.1111/j.2041-1014.2011.00606.x. Epub 2011 Jan 30.


Streptococcus sanguinis is a major component of the oral flora and an important cause of infective endocarditis. Although S. sanguinis is naturally competent, genome sequencing has suggested significant differences in the S. sanguinis competence system relative to those of other streptococci. An S. sanguinis mutant possessing an in-frame deletion in the comC gene, which encodes competence-stimulating peptide (CSP), was created. Addition of synthetic CSP induced competence in this strain. Gene expression in this strain was monitored by microarray analysis at multiple time-points from 2.5 to 30 min after CSP addition, and verified by quantitative reverse transcription-polymerase chain reaction. Over 200 genes were identified whose expression was altered at least two-fold in at least one time point, with the majority upregulated. The 'late' response was typical of that seen in previous studies. However, comparison of the 'early' response in S. sanguinis with that of other oral streptococci revealed unexpected differences with regard to the number of genes induced, the nature of those genes, and their putative upstream regulatory sequences. Streptococcus sanguinis possesses a comparatively limited early response, which may define a minimal streptococcal competence regulatory circuit.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Load
  • Bacterial Proteins / genetics*
  • Bacteriological Techniques
  • Conserved Sequence / genetics
  • Down-Regulation / genetics
  • Frameshift Mutation / genetics
  • Gene Expression Profiling
  • Gene Expression Regulation, Bacterial / genetics*
  • Genes, Bacterial / genetics
  • Humans
  • Microarray Analysis
  • Plasmids / genetics
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sequence Deletion / genetics
  • Streptococcus gordonii / genetics
  • Streptococcus pneumoniae / genetics
  • Streptococcus sanguis / genetics*
  • Streptococcus sanguis / physiology
  • Transcription, Genetic / physiology
  • Transcriptional Activation / genetics
  • Transformation, Bacterial / genetics
  • Up-Regulation / genetics


  • Bacterial Proteins
  • competence factor, Streptococcus