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Updated: Jul 4, 2026

From a Natural Product to Its Biosynthetic Gene Cluster: A Demonstration Using Polyketomycin from Streptomyces diastatochromogenes Tü6028
Published on: January 13, 2017
Incomplete beta-ketone processing as a mechanism for polyene structural variation in the FR-008/candicidin complex
Yongjun Zhou1, Jialiang Li, Jing Zhu
1Laboratory of Microbial Metabolism and School of Life Science & Biotechnology, Shanghai Jiaotong University, Shanghai, China.
FR-008/candicidin, a heptaene macrolide antifungal, exhibits structural variations. Key enzymes KR21 and DH18 influence C-3 and C-9 modifications, impacting overall antifungal potency.
Area of Science:
- Microbiology
- Natural Product Chemistry
- Biochemistry
Background:
- FR-008/candicidin is a heptaene macrolide produced by Streptomyces sp. FR-008.
- It exists as a complex mixture of compounds with known antifungal activity.
Purpose of the Study:
- To elucidate the structural diversity within the FR-008/candicidin complex.
- To identify the roles of specific enzymes in generating these structural variations.
Main Methods:
- Isolation and characterization of six components (FR-008-I to -VI) from the FR-008/candicidin complex.
- Genetic inactivation of KR21 and DH18 genes in Streptomyces sp. FR-008.
- Comparative analysis of antifungal activity among different components and mutant strains.
Main Results:
- Three natural products (III, V, VI) were identified, differing at C-3 and C-9 positions.
- Inactivation of KR21 abolished production of V (C-3 hydroxyl), and DH18 abolished production of VI (C-9 methylene).
- A double mutant produced only III (C-3 ketone, C-9 hydroxyl), showing potent antifungal activity.
Conclusions:
- KR21 and DH18 enzymes are crucial for structural variations in the FR-008/candicidin complex.
- Specific modifications at C-3 and C-9 significantly influence the antifungal activity of these macrolides.
- Understanding these enzymatic pathways can guide the development of novel antifungal agents.
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