Characterization of the ccpA Gene of Enterococcus faecalis : Identification of Starvation-Inducible Proteins Regulated by CcpA

Inactivation ofccpA inEnterococcus faecalis leads to reduction of the growth rate, derepression of thegalKETR operon in the presence of a mixture of glucose and galactose, and reduction of transcription ofldh in the presence of glucose. Moreover, theE. faecalis ccpA gene fully complements aBacillus subtilis ccpA mutant, arguing for similar functions of these two homologous proteins. Protein comparison on two-dimensional gels from the wild-type cells and theccpA mutant cells revealed a pleiotropic effect of the mutation on gene expression. The HPr protein of the carbohydrate-phosphotransferase system was identified by microsequencing, and a modification of its phosphorylation state was observed between the wild-type and the mutant strains. Moreover, at least 16 polypeptides are overexpressed in the mutant, and 6 are repressed. Interestingly, 13 of the 16 polypeptides whose synthesis is enhanced in the mutant were also identified as glucose starvation proteins. The N-terminal amino acid sequences of four of them match sequences deduced from genes coding forl -serine dehydratase, dihydroxyacetone kinase (two genes), and a protein of unknown function fromDeinococcus radiodurans.