FIG 1.
Overview of the regulatory network controlling competence in Streptococcus pneumoniae. (A) Positive-feedback loop responsible for activation of competence. HtrA-mediated degradation of CSP is relevant to the competence-inducing effect of certain antibiotics (8). (Adapted from reference 6 with permission of the publisher.) (B) Early competence is shut down through the action of late-competence protein DprA. Binding of DprA to phosphorylated ComE leads to an increase in the levels of unphosphorylated ComE dimers repressing comCDE expression. Late-competence shutdown is the result of competition for ComW and RNA polymerase binding between sigma factors ComX (σX) and RpoD (σA). Although expression of rpoD is strongly upregulated during competence, the underlying mechanism is unknown.