A gene cluster from Streptomyces galilaeus involved in glycosylation of aclarubicin

We have cloned and characterized a gene cluster for anthracycline biosynthe sis from Streptomyces galilaeus. This cluster, 15-kb long, includes eight g enes involved in the deoxyhexose biosynthesis pathway, a gene for a glycosy ltransferase and one for an activator, as well as two genes involved in agl ycone biosynthesis. Gene disruption targeted to the activator gene blocked production of aclacinomycins in S. galilaeus. Plasmid pSgs4, containing gen es for a glycosyltransferase (aknS), an aminomethylase (aknX), a glucose-1- phosphate thymidylyltransferase (aknY) and two genes for unidentified glyco sylation functions (nknT and aknV), restored the production of aclacinomyci ns in the S. galilaeus mutants H063, which accumulates aklavinone, and H054 , which produces aklavinone with rhodinose and deoxyfucose residues. Furthe rmore, pSgs4 directed the production of L-rhamnosyl-epsilon-rhodomycinone a nd L-daunosaminyl-epsilon-rhodomycinone in S. peucetius strains that produc e epsilon-rhodomycinone endogenously. Subcloning of the gene cluster was ca rried out in order to further define the genes that are responsible for com plementation and hybrid anthracycline generation.