Feb 7, 2020
Streptococcus pneumonieae, model microorganism of natural genetic transformation, has been studied to understand competence development mechanisms. Competence stimulating peptide (CSP) precursor, which is encoded by comC, is processed and secreted by the ComAB transporter, resulting in extracellular accumulation of mature CSP. Mature CSP acts as pheromone to induce competence by binding to ComD receptor. CSP binding ComD is autophosphorylated and phosphotransfer to ComE. Phophorylated ComE induce about 20 early competence genes such as comAB operon, comX1, comX2, ComW and comCDE operon by binding to 9-bp imperfect direct repeat sequence located 5` region of these gene`s promoter. The alternative σ factor ComX, which is encoding comX1 or comX2, directs the transcription of around 60 late competence genes by binding to com-box located upstream of start codon. Some of late competence genes encode the DNA uptake and recombination machinery.