title: Tirandamycin biosynthesis is mediated by co-dependent oxidative enzymes.
abstract: Elucidation of natural product biosynthetic pathways provides important insights into the assembly of potent bioactive molecules, and expands access to unique enzymes able to selectively modify complex substrates. Here, we show full reconstitution, in vitro, of an unusual multi-step oxidative cascade for post-assembly-line tailoring of tirandamycin antibiotics. This pathway involves a remarkably versatile and iterative cytochrome P450 monooxygenase (TamI) and a flavin adenine dinucleotide-dependent oxidase (TamL), which act co-dependently through the repeated exchange of substrates. TamI hydroxylates tirandamycin C (TirC) to generate tirandamycin E (TirE), a previously unidentified tirandamycin intermediate. TirE is subsequently oxidized by TamL, giving rise to the ketone of tirandamycin D (TirD), after which a unique exchange back to TamI enables successive epoxidation and hydroxylation to afford, respectively, the final products tirandamycin A (TirA) and tirandamycin B (TirB). Ligand-free, substrate- and product-bound crystal structures of bicovalently flavinylated TamL oxidase reveal a likely mechanism for the C10 oxidation of TirE.
authors.affiliation: Life Sciences Institute and Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Jacob C
authors.initials: JC
authors.lastname: Carlson
authors.forename: Shengying
authors.initials: S
authors.lastname: Li
authors.forename: Shamila S
authors.initials: SS
authors.lastname: Gunatilleke
authors.forename: Yojiro
authors.initials: Y
authors.lastname: Anzai
authors.forename: Douglas A
authors.initials: DA
authors.lastname: Burr
authors.forename: Larissa M
authors.initials: LM
authors.lastname: Podust
authors.forename: David H
authors.initials: DH
authors.lastname: Sherman
mesh_terms: D000617:Aminoglycosides / Q000096:biosynthesis*; D000900:Anti-Bacterial Agents / Q000096:biosynthesis*; D004798:Enzymes / Q000378:metabolism*; D010084:Oxidation-Reduction; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D004798:Enzymes