Characterization of DNA binding sites of the ComE response regulator from Streptococcus mutans

David C.I. Hung, Jennifer S. Downey, Eduardo A. Ayala, Jens Kreth, Richard Mair, Dilani B. Senadheera, Fengxia Qi, Dennis G. Cvitkovitch, Wenyuan Shi, Steven D. Goodman

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


In Streptococcus mutans, both competence and bacteriocin production are controlled by ComC and the ComED two-component signal transduction system. Recent studies of S. mutans suggested that purified ComE binds to two 11-bp direct repeats in the nlmC-comC promoter region, where ComE activates nlmC and represses comC. In this work, quantitative binding studies and DNase I footprinting analysis were performed to calculate the equilibrium dissociation constant and further characterize the binding site of ComE. We found that ComE protects sequences inclusive of both direct repeats, has an equilibrium dissociation constant in the nanomolar range, and binds to these two direct repeats cooperatively. Furthermore, similar direct repeats were found upstream of cslAB, comED, comX, ftf, vicRKX, gtfD, gtfB, gtfC, and gbpB. Quantitative binding studies were performed on each of these sequences and showed that only cslAB has a similar specificity and high affinity for ComE as that seen with the upstream region of comC. A mutational analysis of the binding sequences showed that ComE does not require both repeats to bind DNA with high affinity, suggesting that single site sequences in the genome may be targets for ComE-mediated regulation. Based on the mutational analysis and DNase I footprinting analysis, we propose a consensus ComE binding site, TCBTAAAYSGT.

Original languageEnglish (US)
Pages (from-to)3642-3652
Number of pages11
JournalJournal of bacteriology
Issue number14
StatePublished - Jul 2011
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology


Dive into the research topics of 'Characterization of DNA binding sites of the ComE response regulator from Streptococcus mutans'. Together they form a unique fingerprint.

Cite this