Identification of pseudotetraivprolide from Pseudomonas entomophila give novel insights into the biosynthesis of detoxin/rimosamide-like anti-antibiotics

Novel variants of known natural product (NP) classes might guide our understanding of biosynthesis, mode of action and potential application as drugs for all members of such NP classes. Here we describe a novel member of the widespread detoxine/rimosamide-like (DRL) natural products named pseudotetraivprolide from Pseudomonas strains, which has the characteristic DRL-activity of protecting Bacillus cereus against the antibiotic blasticidin S. The generation of several deletion and complemented mutants, heterologous expression experiments, identification and structure elucidation of several derivatives, chemical synthesis of main derivatives, enzymatic characterization of individual biochemical steps and detailed homology modelling of enzyme complexes were performed. This allowed us to show the primary metabolism-derived malonyl CoA-ACP transacylase (AT) FabD acting as trans-AT in the biosynthesis, suggest an order for all late-stage modifications and provide a function for the three conserved hypothetical proteins PipDFG acting as last-step acetylation complex thereby stabilizing the final product.