Mycolactone is a polyketide-derived macrolide produced and secreted by a group of very closely related pathogenic mycobacteria species including M. ulcerans, M. liflandii (an unofficial designation), M. pseudoshottsii, and some strains of M. marinum.

Three plasmid-encoded polyketide synthase (PKS) enzymes are responsible for its production: MLSA 1 and MLSA 2 which generate the core, and MLSB is responsible for the synthesis of the polyketide chain.

[10] The C-terminal domains of both MLSA2 and MLSB includes a thioesterase (TE) that was thought to catalyze the formation of the mycolactone core but appears inactive.

Type A and B KRs refer to the two directions of ketoreduction that are correlated with specific amino acids in the active site.

Four of the DH domains are predicted to be inactive based on a point mutation found in the active site sequence.