The catabolite control protein CcpA is a pleiotropic transcription factor that mediates the global transcriptional response to rapidly catabolizable carbohydrates such as glucose in Gram-positive bacteria from the Firmicutes phylum. CcpA belong to the LacI protein family and controls its target genes either positively or negtively, depending on the position of CcpA-binding sites (or Catabolite Responsive Elements, CRE) in the promoter regions of its target genes. The CcpA regulons comprise genes involved in sugar uptake and catabolism, fermentation, amino acid metabolism, suggetsing the role of CcpA as a link between carbon and nitrogen metabolic pathways.
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The CcpA-dependent regulation was experimentally studied in multiple model species including Bacillus subtilis, Staphylococcus aureus, Streptococcus spp, Lactococcus lactis, Clostridium acetobutylicum and Clostridium difficile. The comparative genomic analysis of CcpA regulons in distinct taxonomic groups of Bacteria from the Bacillus / Clostridium group identified the high divergence in the repertoires of CcpA-regulated genes. The CcpA-binding DNA motifs demonstrated good conservation inside of the Bacilli (including Bacillus, Staphylococcus, Lactobacillus, and Streptococcus) and Clostridia groups but the CcpA regulatory motifs are much more diverged between these phylogenetically distant groups of Firmicutes.
