Discovery and Biosynthesis of a Structurally Dynamic Antibacterial Diterpenoid

Area of Science:

• * Natural Product Chemistry
• * Microbial Genomics
• * Organic Chemistry

Background:

• * Soil-dwelling Streptomyces species are a rich source of diverse natural products.
• * Diterpenoids are complex molecules with various biological activities.
• * The biosynthesis of bacterial diterpenoids remains largely unexplored.

Purpose of the Study:

• * To isolate and characterize novel bicyclic diterpenoids from Streptomyces.
• * To elucidate the biosynthetic pathway and responsible gene cluster for a new diterpenoid.
• * To investigate the biological activity and structural properties of the isolated compound.

Main Methods:

• * Genome sequencing and comparative bioinformatics of Streptomyces sp. (CL12-4).
• * Identification and functional verification of the terpene synthase and biosynthetic gene cluster.
• * Isolation and extensive spectroscopic analysis (NMR, Mosher's analysis) for structural elucidation.
• * Heterologous production of the core diterpene and conformational analysis.

Main Results:

• * Isolation of a new bicyclic diterpenoid, benditerpenoic acid, from Streptomyces.
• * Identification of the biosynthetic gene cluster and terpene synthase responsible for eunicellane scaffold construction.
• * Determination of absolute configurations and characterization of two distinct ring-flipped conformations.
• * Moderate antibacterial activity observed against Gram-positive bacteria, including drug-resistant Staphylococcus aureus.

Conclusions:

• * This study reports the first bacterial source of an eunicellane-type diterpenoid.
• * The identified biosynthetic gene cluster and terpene synthase provide insights into bacterial diterpenoid biosynthesis.
• * Benditerpenoic acid represents a unique structural class with potential therapeutic applications.