Author: ["Jacob C. Carlson","Shengying Li","Shamila S. Gunatilleke","Yojiro Anzai","Douglas A. Burr","Larissa M. Podust","David H. Sherman"]
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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. Enzymes are capable of modifying complex organic structures with exquisite selectivity. Understanding these processes could help in the development and production of new bioactive compounds. Here, a complete reconstitution of tailoring steps in tirandamycin biosynthesis shows that two enzymes repeatedly exchange substrates to achieve several different oxidations en route to this family of antibiotic compounds. Cite this article
Carlson, J., Li, S., Gunatilleke, S. et al. Tirandamycin biosynthesis is mediated by co-dependent oxidative enzymes. Nature Chem 3, 628–633 (2011). https://doi.org/10.1038/nchem.1087 