A Structural Analysis of the Angucycline-Like Antibiotic Auricin from Subsp. CCM 3239 Revealed Its High Similarity to Griseusins.

We previously identified the gene cluster in subsp. CCM 3239 (formerly CCM 3239), which is responsible for the production of the angucycline-like antibiotic auricin (). Preliminary characterization of revealed that it possesses an aminodeoxyhexose d-forosamine and is active against Gram-positive bacteria. Here we determined the structure of , finding that it possesses intriguing structural features, which distinguish it from other known angucyclines. In addition to d-forosamine, compound also contains a unique, highly oxygenated aglycone similar to those of spiroketal pyranonaphthoquinones griseusins. Like several other griseusins, also undergoes methanolysis and displays modest cytotoxicity against several human tumor cell lines. Moreover, the central core of the cluster is highly similar to the partial gene cluster responsible for the biosynthesis of griseusin A and B in both the nature of the encoded proteins and the gene organization.