Inducing properties of analogs of 2-keto-3-deoxygluconate on the expression of pectinase genes of Erwinia chrysanthemi.

In Erwinia chrysanthemi, all the genes involved in pectin degradation are controlled by the negative regulatory gene kdgR. 2-keto-3-deoxy-gluconate (KDG) is the inducing molecule that interacts with KdgR to allow the expression of all the genes of the kdg regulon. The inducing properties on the expression of genes regulated by kdgR of various analogs and derivatives of KDG were tested. All the inducers share the common moiety COOH-CO-CH2-CHOH-C-C included in a pyranic cycle. Our results show that esterification of C1 prevents induction. Presence of a ketone function on C2 and absence of hydroxyl on C3 are necessary for induction. The nature and the configuration of substituent on C5 has no influence on induction. Two compounds have interesting properties: 5-O-methyl-KDG is a gratuitous inducer, and gluconic acid can prevent induction.