Cell density- and ComE-dependent expression of a group of mutacin and mutacin-like genes in Streptococcus mutans

FEMS Microbiol Lett. 2006 Dec;265(1):11-7. doi: 10.1111/j.1574-6968.2006.00459.x. Epub 2006 Sep 19.


Streptococcus mutans is a major cariogenic inhabitant of the high cell density oral biofilm (dental plaque). In previous studies, we showed that production of one of its virulence factors, the bacteriocin mutacin IV, was regulated by high cell density as well as the competence regulatory system ComED. In this study, we utilized luciferase fusions and real-time reverse transcriptase polymerase chain reaction (RT-PCR), to demonstrate that high cell density and ComED also regulate an uncharacterized group of mutacin and mutacin-like genes. Under high cell density or in the presence of externally added competence-stimulating peptide (CSP), gene expression increased 10- to 30-fold. Interestingly, high cell density was able to bypass the requirement for CSP addition. However, both cell density and CSP-dependent gene expression had a strict requirement for the ComE response regulator.

Publication types

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

MeSH terms

  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism
  • Bacterial Proteins / pharmacology
  • Bacteriocins / biosynthesis
  • Bacteriocins / genetics*
  • Base Sequence
  • Dental Caries / microbiology*
  • Gene Expression Regulation, Bacterial
  • Genes, Bacterial
  • Molecular Sequence Data
  • Open Reading Frames
  • Streptococcus mutans / genetics*
  • Streptococcus mutans / growth & development
  • Streptococcus mutans / metabolism


  • Bacterial Proteins
  • Bacteriocins
  • ComE protein, Streptococcus pneumoniae
  • competence factor, Streptococcus
  • mutacin IV