Mechanistic Characterisation of a Diterpene Synthase for Chryseojoostenes A–E from Chryseobacterium Joostei

作者：Georges Bellier Tabekoueng, Heng Li, Kexin Yang, Lukas Lauterbach, Bernd Goldfuß, Jeroen S. Dickschat · 发表于：Angewandte Chemie International Edition · 年份：2025 · DOI：10.1002/anie.202513149 · 被引用次数：7 · 研究领域：Plant biochemistry and biosynthesis、Microbial Natural Products and Biosynthesis、Phytochemistry and biological activity of medicinal plants

A diterpene synthase from Chryseobacterium joostei was characterised and produces the five unique compounds chryseojoostenes A-E. Chryseojoostenes D and E were produced in too low amounts for isolation from the wildtype enzyme, but extensive site-directed mutagenesis resulted in an enzyme variant in which the production of these compounds was enhanced. The biosynthesis of the enzyme products was investigated in detail through a combined experimental and computational approach, indicating a complex hydrogen scrambling during terpene cyclisation and a long-range proton shift towards chryseojoostene E. Density functional theory (DFT) calculations revealed that a similar long range hydrogen shift is involved in the formation of an even fragment ion (m/z 216), characterising the unique chemistry of the chryseojoostene skeleton. Further insights into the cyclisation mechanism were obtained by enzymatic conversion of two substrate analogs with reduced reactivity.