7E36

A [6+4]-cycloaddition adduct is the biosynthetic intermediate in streptoseomycin biosynthesis

Summary for 7E36

• Entry DOI: 10.2210/pdb7e36/pdb
• Descriptor: Alkanesulfonate monooxygenase SsuD/methylene tetrahydromethanopterin reductase-like flavin-dependent oxidoreductase (Luciferase family), FMN-dependent oxidoreductase (Nitrilotriacetate monooxygenase family), SULFATE ION, ... (8 entities in total)
• Functional Keywords: nargenicin, biosynthetic protein, oxidase, oxidoreductase
• Biological source: Nocardia tenerifensis; More
• Total number of polymer chains: 2
• Total formula weight: 81575.15

Authors

Zhang, B.,Ge, H.M. (deposition date: 2021-02-08, release date: 2021-03-10, Last modification date: 2023-11-29)

Primary citation

Wang, K.B.,Wang, W.,Zhang, B.,Wang, X.,Chen, Y.,Zhu, H.J.,Liang, Y.,Tan, R.X.,Ge, H.M.
A [6+4]-cycloaddition adduct is the biosynthetic intermediate in streptoseomycin biosynthesis.
Nat Commun, 12:2092-2092, 2021

PubMed Abstract: Streptoseomycin (STM, 1) is a bacterial macrolactone that has a unique 5/14/10/6/6-pentacyclic ring with an ether bridge. We have previously identified the biosynthetic gene cluster for 1 and characterized StmD as [6 + 4]- and [4 + 2]-bispericyclase that catalyze a reaction leading to both 6/10/6- and 10/6/6-tricyclic adducts (6 and 7). The remaining steps, especially how to install and stabilize the required 10/6/6-tricyclic core for downstream modifications, remain unknown. In this work, we have identified three oxidoreductases that fix the required 10/6/6-tryciclic core. A pair of flavin-dependent oxidoreductases, StmO1 and StmO2, catalyze the direct hydroxylation at [6 + 4]-adduct (6). Subsequently, a spontaneous [3,3]-Cope rearrangement and an enol-ketone tautomerization result in the formation of 10/6/6-tricyclic intermediate 12b, which can be further converted to a stable 10/6/6-tricyclic alcohol 11 through a ketoreduction by StmK. Crystal structure of the heterodimeric complex NtfO1-NtfO2, homologues of StmO1-StmO2 with equivalent function, reveals protein-protein interactions. Our results demonstrate that the [6 + 4]-adduct instead of [4 + 2]-adduct is the bona fide biosynthetic intermediate.

PubMed: 33828077
DOI: 10.1038/s41467-021-22395-7

Experimental method

X-RAY DIFFRACTION (2 Å)