Albumycin, a new isoindolequinone from Streptomyces albus J1074 harboring the fluostatin biosynthetic gene cluster

Heterologous expression of the fluostatin biosynthetic gene cluster from the marine-derived Micromonospora rosaria SCSIO N160 in Streptomyces albus J1074 led to the isolation of a novel isoindolequinone albumycin (1) and a known isoquinolinequinone mansouramycin A (2). The structure of 1 was elucidated on the basis of detailed 1D and 2D NMR spectroscopic analysis. Mansouramycin A (2) is active against methicillin-resistant Staphylococcus aureus ATCC 43300, with a MIC of 8 μg ml−1, while albumycin (1) displayed negligible antibacterial activities. This study represents another example of activation of secondary metabolites that are non-relevant to the heterologously introduced biosynthetic gene cluster in a bacterial host.