REGULATION OF COMPETENCE FOR GENETIC-TRANSFORMATION IN STREPTOCOCCUS-PNEUMONIAE BY AN AUTO-INDUCED PEPTIDE PHEROMONE AND A 2-COMPONENT REGULATORY SYSTEM

The regulation of competence for genetic transformation in Streptococc us pneumoniae depends on a quorum-sensing system, but the only molecul ar elements of the system whose specific role have been identified are an extracellular peptide signal and an ABC-transporter required for i ts export. Here we show that transcription of comC, the gene encoding a predicted 41-residue precursor peptide that is thought to be process ed and secreted as the 17-residue mature competence activator, increas ed approximately 40-fold above its basal level of expression in respon se to exogenous synthetic activator, consistent with earlier experimen ts indicating that the activator acts autocatalytically. We also descr ibe two new genes, comD and comE, that encode members of histidine pro tein kinase and response-regulator families and are linked to comC. Di sruption of comE abolished both response to synthetic activator peptid e and endogenous competence induction.