The functional ccpA gene is required for carbon catabolite repression in Lactobacillus plantarum

We report the characterization of the ccpA gene of Lactobacillus plantarum, coding for catabolite control protein A. The gene is linked to the pepQ ge ne, encoding a proline peptidase, in the order ccpA-pepQ, with the two gene s transcribed in tandem from the same strand as distinct transcriptional un its. Two ccpA transcription start sites corresponding to two functional pro moters were found, expression from the upstream promoter being autogenously regulated through a catabolite-responsive element (cre) sequence overlappi ng the upstream fl site. During growth on ribose, the upstream promoter sho wed maximal expression, while growth on glucose led to transcription from t he downstream promoter. In a ccpA mutant strain, the gene was transcribed m ainly from the upstream promoter in both repressing and non repressing cond itions. Expression of two enzyme activities, beta -glucosidase and beta -ga lactosidase, was relieved from carbon catabolite repression in the ccpA mut ant strain. In vivo footprinting analysis of the catabolite-controlled bglH gene regulatory region in the ccpA mutant strain showed loss of protection of the cre under repressing conditions.