The entire nogalamycin biosynthetic gene cluster of Streptomyces nogalater: characterization of a 20-kb DNA region and generation of hybrid structures

Fragments spanning 20 kb of Streptomyces nogalater genomic DNA were charact erized to elucidate the molecular genetic basis of the biosynthetic pathway of the anthracycline antibiotic nogalamycin. Structural analysis of the pr oducts obtained by expression of the fragments in S. galilaeus and S. peuce this mutants producing aclacinomycin and daunomycin metabolites, respectiv ely, revealed hybrid compounds in which either the aglycone or the sugar mo iety was modified. Subsequent sequence analysis revealed twenty ORFs involv ed in nogalamycin biosynthesis, of which eleven could be assigned to the de oxysugar pathway, four to aglycone biosynthesis, while the remaining five e xpress products with unknown function. On the basis of sequence similarity and experimental data, the functions of the products of the newly discovere d genes were determined. The results suggest that the entire biosynthetic g ene cluster for nogalamycin is now known. Furthermore, the compounds obtain ed by heterologous expression of the genes show that it is possible to use the genes in combinatorial biosynthesis to create novel chemical structures for drug screening purposes.