Figure 1.

Formicamycin biosynthesis requires 24 genes expressed on nine transcripts

The minimal for BGC contains 24 genes required for formicamycin biosynthesis; red = biosynthetic genes, blue = transporters, green = regulatory genes. Cappable RNA sequencing identified 10 transcription start sites in the for BGC, nine of which are in intergenic regions that likely represent promoter regions for the biosynthetic genes. Formicamycin biosynthesis occurs by the formation of fasamycins through the action of the PKS and associated gene products, including methyltransferases (MTase) and a halogenase. ForX-catalyzed hydroxylation and ring expansion leads to a lactone intermediate that undergoes a reductive ring contraction catalyzed by the flavin-dependent oxidoreductase ForY to yield the formicamycin backbone.