Role of GntR Family Regulatory Gene SCO1678 in Gluconate Metabolism in Streptomyces coelicolor M145

Here we report functional characterization of the Streptomyces coelicolor M145 gene SCO1678, which encodes a GntR-like regulator of the FadR subfamily. Bioinformatic analysis suggested that SCO1678 is part of putative operon (gnt) involved in gluconate metabolism. Combining the results of SCO1678 knockout, transcriptional analysis of gnt operon, and Sco1678 protein-DNA electromobility shift assays, we established that Sco1678 protein controls the gluconate operon. It does so via repression of its transcription from a single promoter located between genes SCO1678 and SCO1679. The knockout also influenced, in a medium-dependent manner, the production of secondary metabolites by S. coelicolor. In comparison to the wild type, on gluconate-containing minimal medium, the SCO1678 mutant produced much less actinorhodin and accumulated a yellow-colored pigment, likely to be the cryptic polyketide coelimycin. Possible links between gluconate metabolism and antibiotic production are discussed.