The pneumococcal social network
Fig 2
Hierarchical activation of multiple double-glycine peptides.
The competence pathway is turned on by activation of ComDE by the double-glycine peptide, CSP. Competence induction by CSP results in transcriptional activation of a number of double-glycine peptides including BIP, CibAB, and BriC, each of which have phenotypic consequences. Activation of the competence pathway also allows for uptake of DNA and generation of genetic diversity. The schematic diagram illustrates ComE-dependent induction of briC along with other early competence genes. Upon being exported through ComAB, intercellular communication via BriC promotes biofilm development. This highlights the interconnectedness of mechanisms that impart genetic and phenotypic diversity. The design architecture that allows for hierarchical activation of different intercellular communication peptides may provide an opportunity for alternative activation of subsets of genes without expending energy to turn on the entire pathway. BIP, bacteriocin-inducing peptide; BriC, biofilm-regulating peptide induced by competence; competence-induced bacteriocin; CSP, competence-stimulating peptide; GG, double-glycine; TCS, two component systems.