Pseudobulbiferamides: Plasmid-Encoded Ureidopeptide Natural Products with Biosynthetic Gene Clusters Shared Among Marine Bacteria of Different Genera.

Ureidopeptidic natural products possess a wide variety of favorable pharmacological properties. In addition, they have been shown to mediate core physiological functions in producer bacteria. Here, we report that similar ureidopeptidic natural products with conserved biosynthetic gene clusters are produced by different bacterial genera that coinhabit marine invertebrate microbiomes. We demonstrate that a Microbulbifer strain isolated from a marine sponge can produce two different classes of ureidopeptide natural products encoded by two different biosynthetic gene clusters that are positioned on the bacterial chromosome and on a plasmid. The plasmid encoded ureidopeptide natural products, which we term the pseudobulbiferamides (5-8), resemble the ureidopeptide natural products produced by Pseudovibrio, a different marine bacterial genus that is likewise present in marine sponge commensal microbiomes. Using imaging mass spectrometry, we find that the two classes of Microbulbifer-derived ureidopeptides occupy different physical spaces relative to the bacterial colony, perhaps implying different roles for these two compound classes in Microbulbifer physiology and environmental interactions.