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. Author manuscript; available in PMC: 2014 Jul 18.
Published in final edited form as: FEMS Microbiol Rev. 2013 Oct 31;38(3):473–492. doi: 10.1111/1574-6976.12046

Figure 5. Competence development in streptococci.

Figure 5

Left panel: Competence development in Anginosus and Mitis groups of streptococci uses the ComAB/ComCDE system and requires production and processing of ComC to the competence stimulating peptide CSP. CSP interaction with the surface sensor kinase ComD allows phosphorylation of ComE. Phosphorylated ComE binds to conserved CIN (C) box motifs upstream of late competence genes in streptococci of the Mitis and Anginosus groups as well as bacteriocins in S. mutans.

Right panel: In the Pyogenic, Bovis, Salivarius and Mutans groups of streptococci, the most proximal regulator of competence genes is the ComRS system. ComS is secreted and processed to the SigX inducing peptide (XIP) via an unknown mechanism. XIP is imported into the cell by the Opp transporter system where it directly interacts with ComR. ComR binds to DNA and upregulates expression of comS as well as sigX, an alternative sigma factor controlling expression of later competence genes. In S. mutans, these two pathways interact although the mechanism and reason for this interaction is not understood. The figure is a modified reproduction (Federle & Morrison, 2012)