Biosynthesis and Assembly Logic of Fungal Hybrid Terpenoid Natural Products.

In recent decades, fungi have emerged as significant sources of diverse hybrid terpenoid natural products, and their biosynthetic pathways are increasingly unveiled. This review mainly focuses on elucidating the various strategies underlying the biosynthesis and assembly logic of these compounds. These pathways combine terpenoid moieties with diverse building blocks including polyketides, nonribosomal peptides, amino acids, p-hydroxybenzoic acid, saccharides, and adenine, resulting in the formation of plenty of hybrid terpenoid natural products via C-O, C-C, or C-N bond linkages. Subsequent tailoring steps, such as oxidation, cyclization, and rearrangement, further enhance the biological diversity and structural complexity of these hybrid terpenoid natural products. Understanding these biosynthetic mechanisms holds promise for the discovery of novel hybrid terpenoid natural products from fungi, which will promote the development of potential drug candidates in the future.

Biosynthesis of Cosmosporasides Reveals the Assembly Line for Fungal Hybrid Terpenoid Saccharides.

Fungal hybrid terpenoid saccharides constitute a new and growing family of natural products with significant biomedical and agricultural activities. One representative family is the cosmosporasides, which feature oxidized terpenoid units and saccharide moieties; however, the assembly line of these building blocks has been elusive. Herein, a cos cluster from Fusarium orthoceras was discovered for the synthesis of cosmosporaside C (1) by genome mining. A UbiA family intramembrane prenyltransferase (UbiA-type PT), a multifunctional cytochrome P450, an α,ß-hydrolase, an acetyltransferase, a dimethylallyl transferase (DMAT-type PT) and a glycosyltransferase function cooperatively in the assembly of the scaffold of 1 using primary central metabolites. The absolute configuration at C4, C6 and C7 of 1 was also established. Our work clarifies the unexpected functions of UbiA-type and DMAT-type PTs and provides an example for understanding the synthetic logic of hybrid terpenoid saccharides in fungi.

Reshaping the Diversity of Oxidized Polyquinane Sesquiterpenoids by Cytochrome P450s.

Polyquinane sesquiterpenoids (PQSTs) are complex compounds with two or three fused cabocyclopentane ring systems, and the biocatalysts for direct C-H bond oxidation on these scaffolds have rarely been discovered. In this study, we discovered two versatile fungal CYP450s capable of performing diverse oxidations on seven PQST scaffolds, resulting in the generation of 20 unique products. Our findings significantly expand the diversity of oxidized PQST scaffolds and provide important biocatalysts for the selective oxidation of inert carbons of terpenoids in future research.