Identification and characterization of the ficellomycin biosynthesis gene cluster from Streptomyces ficellus

Ficellomycin is a peptide-like antibiotic which exhibits potent in vitro activity against Penicillium oxalicum and Staphylococcus aureus, even against strains resistant to most clinically used antibiotics. The gene cluster responsible for ficellomycin biosynthesis was cloned from Streptomyces ficellus and sequenced. It was found to contain 26 ORFs and is located within 30 kb of contiguous DNA. Targeted disruption of the encoding genes revealed that most were involved in the functional section of ficellomycin biosynthesis, such as peptide assembly, regulation, resistance, and biosynthesis of the precursor of ficellomycin 2-[4-guanidyl-1-azabicyclo[3.1.0]hexan-2-yl] glycine (2-GAHG). Within the 2-GAHG synthesis pathway, a sulfate adenylyltransferase appears to be involved in the synthesis of the pharmaceutically important 1-azabicyclo[3.1.0]hexane ring moiety, which has been reported to cause DNA cross-linking or impairment of semiconservative DNA replication.