Inducing effect of diamines on transcription of the cephamycin C genes from the lat and pcbAB promoters in Nocardia lactamdurans

The diamines putrescine, cadaverine, and diaminopropane stimulate cephamyci n biosynthesis in Nocardia lactamdurans, in shake flasks and fermenters, wi thout altering cell growth, Intracellular levels of the P7 protein (a compo nent of the methoxylation system involved in cephamycin biosynthesis) were increased by diaminopropane, as shown by immunoblotting studies. Lysine-6-a minotransferase and piperideine-6-carboxylate dehydrogenase activities invo lved in biosynthesis of the cr-aminoadipic acid precursor were also greatly stimulated. The diamine stimulatory effect is exerted at the transcription al level, as shown by low-resolution S1 protection studies. The transcript corresponding to the pcbAB gene and to a lesser extent also the lat transcr ipt were significantly increased in diaminopropane-supplemented cultures, w hereas transcription from the cefD promoter was not affected. Coupling of t he lat and pcbAB promoters to the reporter xylE gene showed that expression from the laf and pcbAB promoters was increased by addition of diaminopropa ne in Streptomyces lividans. Intracellular accumulation of diamines in Noca rdia may be a signal to trigger antibiotic production.