Distinct regulatory role of carbon catabolite protein A (CcpA) in oral streptococcal spxB expression

Sylvio Redanz, Revathi Masilamani, Nyssa Cullin, Rodrigo A. Giacaman, Justin Merritt, Jens Kreth

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


Pyruvate oxidase (SpxB)-dependent H 2 O 2 production is under the control of carbon catabolite protein A (CcpA) in the oral species Streptococcus sanguinis and Streptococcus gordonii. Interestingly, both species react differently to the presence of the preferred carbohydrate source glucose. S. gordonii CcpA-dependent regulation of spxB follows classical carbon catabolite repression. Conversely, spxB expression in S. sanguinis is not influenced by glucose but is repressed by CcpA. Here, we constructed strains expressing the heterologous versions of CcpA or the spxB promoter region to learn if the distinct regulation of spxB expression is transferable from S. gordonii to S. sanguinis and vice versa. While cross-species binding of CcpA to the spxB promoter is conserved in vitro, we were unable to swap the speciesspecific regulation. This suggests that a regulatory mechanism upstream of CcpA most likely is responsible for the observed difference in spxB expression. Moreover, the overall ecological significance of differential spxB regulation in the presence of various glucose concentrations was tested with additional oral streptococcus isolates and demonstrated that carbohydrate-dependent and carbohydrate-independent mechanisms exist to control expression of spxB in the oral biofilm. Overall, our data demonstrate the unexpected finding that metabolic pathways between two closely related oral streptococcal species can be regulated differently despite an exceptionally high DNA sequence identity.

Original languageEnglish (US)
Article numbere00619-17
JournalJournal of bacteriology
Issue number8
StatePublished - Apr 1 2018


  • CcpA
  • Hydrogen peroxide
  • Oral biofilm
  • Streptococcus

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology


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