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Published on: February 7, 2019
Deciphering Early Oxidative Steps in Spirotetronate Biosynthesis Reveals a Two-Enzyme Cascade for Macrocyclic Lactone
Siqiang Chen1,2, Zuer Lin1,2, Qingbo Zhang1,2
1State Key Laboratory of Tropical Oceanography, Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, China.
Researchers identified key enzymes (PasO4/PasO3) in spirotetronate biosynthesis, creating a cascade for macrocyclic lactone formation. This biocatalytic tool offers new ways to diversify spirotetronate compounds.
Area of Science:
- Biochemistry
- Synthetic Biology
- Natural Product Biosynthesis
Background:
- Spirotetronates are a class of bioactive natural products with complex structures.
- Understanding the early biosynthetic steps is crucial for pathway engineering and compound diversification.
Purpose of the Study:
- To elucidate the functions of three monooxygenases (PasO1, PasO3, PasO4) in the biosynthesis of spirotetronate PA-46101.
- To demonstrate a novel enzymatic cascade for the formation of the spirotetronate macrocyclic lactone.
Main Methods:
- Gene knockout and heterologous expression of monooxygenases.
- In vitro enzymatic assays using purified enzymes.
- Structural analysis of a key enzyme (PasO3 homologue).
Main Results:
- PasO4, a P450 enzyme, was shown to oxidize a methyl group to a carboxylate.
- PasO3 catalyzes a regiospecific Baeyer-Villiger oxidation, enabled by the PasO4-generated carboxylate.
- Structural data revealed a carboxylate-binding pocket in PasO3, explaining its substrate specificity.
Conclusions:
- A two-enzyme cascade involving PasO4 and PasO3 is essential for constructing the spirotetronate macrocyclic lactone.
- This enzymatic cascade represents a portable biocatalytic tool for the generation of novel spirotetronate derivatives.
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