Genetic Manipulation of an Aminotransferase Family Gene dtlAActivates Youssoufenes in Marine-Derived Streptomyces youssoufiensis

Disruption of an aminotransferase family gene dtlAactivated the production of a novel dimeric benzoic polyene acids (BPAs), named youssoufene A1 (1), along with four new (2–5, youssoufenes B1–B4) and a known (6) monomeric BPA in the marine-derived Streptomyces youssoufiensisOUC6819. The structures of 1–5were elucidated by extensive spectroscopic and computational approaches. Youssoufene A1 (1) exhibited notably increased growth inhibition (MIC = 12.5 μg/mL) against multidrug resistant Enterococcus faecaliscompared to monomeric structures (2–6).