The two-component system BfrAB regulates expression of ABC transporters in Streptococcus gordonii and Streptococcus sanguinis

Microbiology (Reading). 2009 Jan;155(Pt 1):165-173. doi: 10.1099/mic.0.023168-0.


The putative two-component system BfrAB is involved in Streptococcus gordonii biofilm development. Here, we provide evidence that BfrAB regulates the expression of bfrCD and bfrEFG, which encode two ATP-binding cassette (ABC) transporters, and bfrH, which encodes a CAAX amino-terminal protease family protein. BfrC and BfrE are ATP-binding proteins, and BfrD, BfrF and BfrG are homologous membrane-spanning polypeptides. Similarly, BfrABss, the BfrAB homologous system in Streptococcus sanguinis, controls the expression of two bfrCD-homologous operons (bfrCDss and bfrXYss), a bfrH-homologous gene (bfrH1ss) and another CAAX amino-terminal protease family protein gene (bfrH2ss). Furthermore, we demonstrate that the purified BfrA DNA-binding domain from S. gordonii binds to the promoter regions of bfrCD, bfrEFG, bfrH, bfrCDss, bfrXYss and bfrH1ss in vitro. Finally, we show that the BfrA DNA-binding domain recognizes a conserved DNA motif with a consensus sequence of TTTCTTTAGAAATATTTTAGAATT. These data suggest, therefore, that S. gordonii BfrAB controls biofilm formation by regulating multiple ABC-transporter systems.

Publication types

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

MeSH terms

  • ATP-Binding Cassette Transporters / chemistry
  • ATP-Binding Cassette Transporters / genetics
  • ATP-Binding Cassette Transporters / metabolism*
  • Amino Acid Sequence
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Base Sequence
  • Biofilms / growth & development
  • Gene Expression Profiling
  • Gene Expression Regulation, Bacterial*
  • Molecular Sequence Data
  • Oligonucleotide Array Sequence Analysis / methods
  • Operon
  • Peptide Hydrolases / chemistry
  • Peptide Hydrolases / genetics
  • Peptide Hydrolases / metabolism
  • Polymerase Chain Reaction
  • Sequence Alignment
  • Sequence Analysis, DNA
  • Signal Transduction*
  • Streptococcus gordonii / genetics
  • Streptococcus gordonii / growth & development*
  • Streptococcus gordonii / metabolism
  • Streptococcus sanguis / genetics
  • Streptococcus sanguis / growth & development*
  • Streptococcus sanguis / metabolism


  • ATP-Binding Cassette Transporters
  • Bacterial Proteins
  • Peptide Hydrolases