Bioactive secondary metabolites from Streptomycetes are important sources of lead compounds in current
drug development. Streptomyces costaricanus SCSIO ZS0073, a mangrove-derived actinomycete, produces
actinomycin D, a clinically used therapeutic for
Wilm's tumor of the kidney,
trophoblastic tumors and
rhabdomyosarcoma. In this work, we identified the
actinomycin biosynthetic gene cluster (BGC)
acn by detailed analyses of the S. costaricanus SCSIO ZS0073 genome. This organism produces
actinomycin D with a titer of ~69.8 μg mL-1 along with traces of
actinomycin Xoβ. The
acn cluster localized to a 39.8 kb length region consisting of 25 open reading frames (ORFs), including a set of four genes that drive the construction of the 4-methyl-3-hydroxy-anthranilic
acid (4-MHA) precursor and three non-ribosomal
peptide synthetases (NRPSs) that generate the
4-MHA pentapeptide semi-
lactone, which, upon dimerization, affords final
actinomycin D. Furthermore, the
acn cluster contains four positive regulatory genes acnWU4RO, which were identified by in vivo gene inactivation studies. Our data provide insights into the genetic characteristics of this new mangrove-derived
actinomycin D bioproducer, enabling future metabolic engineering campaigns to improve both titers and the structural diversities possible for
actinomycin D and related analogues.