Transcriptional regulation of the redD transcriptional activator gene occounts for growth-phase-dependent production of the antibiotic undecylprodigiosin in Streptomyces coelicolor A3(2)

Transcription of redD, the activator gene required for production of the red-pigmented antibiotic undecylprodigiosin by Streptomyces coelicolor A3(2), showed a dramatic increase during the transition from exponential to stationary phase. The increase in redB expression was followed by transcription of redX, a biosynthetic structural gene, and the appearance of the antibiotic in the mycelium, and coincided with the intracellular appearance of ppGpp. However, ppGpp production elicited either by nutritional shiftdown of, or addition of serine hydroxamate to, exponentially growing cultures had no stimulatory effect on redD transcription. The presence of redD on a multicopy plasmid resulted in elevated levels of the redD transcript and production of redX and undecylprodigiosin during exponential growth; the normal growth-phase-dependent production of undecylprodigiosin appeared to be mediated entirely through the redD promoter, which shows limited similarity to the consensus sequence for the major class of eubacterial promoters.