Genome Mining for Sesterterpenes Using Bifunctional Terpene Synthases Reveals a Unified Intermediate of Di/Sesterterpenes

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• 作者：Ying Ye ; Atsushi Minami ; Attila Mandi ; Chengwei Liu ; Tohru Taniguchi ; Tomohisa Kuzuyama ; Kenji Monde ; Katsuya Gomi ; Hideaki Oikawa
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：September 16, 2015
• 年：2015
• 卷：137
• 期：36
• 页码：11846-11853
• 全文大小：542K
• ISSN：1520-5126

文摘

Genome mining is a promising method to discover novel secondary metabolites in the postgenomic era. We applied the Aspergillus oryzae heterologous expression system to functionally characterize cryptic bifunctional terpene synthase genes found in fungal genomes and identified the sesterfisherol synthase gene (NfSS) from Neosartorya fischeri. Sesterfisherol contains a characteristic 5鈥?鈥?鈥? tetracyclic ring system and is modified by cytochrome P450 monooxygenase (NfP450) to sesterfisheric acid. The cyclization mechanism was proposed on the basis of the analysis of in vivo and in vitro enzymatic reactions with isotopically labeled precursors. The mechanism involves C1 cation鈥搊lefin IV鈥搊lefin V cyclization followed by five hydride shifts, allowing us to propose a unified biogenesis for sesterterpenes branching from bicyclic (5鈥?5), tricyclic (5鈥?2鈥?), and tetracyclic (5鈥?鈥?鈥?) cation intermediates. Furthermore, the mechanism is distinct from that of a separate class of di/sesterterpenes including fusicoccins and ophiobolins. The difference between mechanisms is consistent with phylogenetic analysis of bifunctional terpene synthases, suggesting that the amino acid sequence reflects the initial cyclization mode, which is most likely related to the initial conformation of a linear prenyl diphosphate.