The biosyntheticgene cluster of zorbamycin, a member of the bleomycin family of antitumor antibiotics, from Streptomyces flavoviridis ATCC 21892

Abstract

The biosyntheticgene cluster for the glycopeptide-derived antitumor antibiotic zorbamycin (ZBM) was cloned by screening a cosmid library of Streptomyces flavoviridis ATCC 21892. Sequence analysis revealed 40 ORFs belonging to the ZBM biosyntheticgene cluster. However, only 23 and 22 ORFs showed striking similarities to the biosyntheticgene clusters for the bleomycins (BLMs) and tallysomycins (TLMs), respectively; the remaining ORFs do not show significant homology to ORFs from the related BLM and TLM clusters. The ZBM gene cluster consists of 16 nonribosomal peptide synthetase (NRPS) genes encoding eight complete NRPS modules, three incomplete didomain NRPS modules, and eight freestanding single NRPS domains or associated enzymes, a polyketide synthase (PKS) gene encoding one PKS module, six sugarbiosynthesisgenes, as well as genes encoding other biosynthesis and resistance proteins. A genetic system using Escherichia coli–Streptomyces flavoviridis intergeneric conjugation was developed to enable ZBM gene cluster boundary determinations and biosynthetic pathway manipulations.