Rieder C, Strauss G, Fuchs G, Arigoni D, Bacher A, Eisenreich W
Department of Organic Chemistry and Biochemistry, Technische Universität München, Lichtenbergstrasse 4, D-85747 Garching, Germany.
J Biol Chem. 1998 Jul 17;273(29):18099-108. doi: 10.1074/jbc.273.29.18099.
The biosynthesis of verrucosan-2beta-ol in the green phototrophic eubacterium Chloroflexus aurantiacus was investigated by in vivo incorporation of singly or doubly 13C-labeled acetate. The 13C labeling of the isolated diterpene was analyzed by one- and two-dimensional NMR spectroscopy. The 13C-labeling patterns of verrucosan-2beta-ol were compared with the labeling patterns of intermediary metabolites (acetyl-CoA, pyruvate, and glyceraldehyde 3-phosphate) which were deduced from amino acids and nucleosides by retrobiosynthetic analysis. The results show that verrucosan-2beta-ol is synthesized via mevalonate and not via the deoxyxylulose pathway, which was discovered recently in some eubacteria, algae, and plants. A scheme for the formation of the unusual tetracyclic ring system is offered. The cyclization process is initiated by the solvolysis of pyrophosphate from geranyllinaloyl pyrophosphate and the mechanism involves a Wagner-Meerwein rearrangement, a 1,5-hydride shift, and a cyclopropylcarbinyl to cyclopropylcarbinyl rearrangement.
通过体内掺入单标记或双标记的¹³C 乙酸盐，对绿色光合真细菌橙色绿屈挠菌中疣孢菌素 -2β-醇的生物合成进行了研究。通过一维和二维核磁共振光谱分析分离出的二萜的¹³C 标记。将疣孢菌素 -2β-醇的¹³C 标记模式与通过逆生物合成分析从氨基酸和核苷推导得出的中间代谢物（乙酰辅酶 A、丙酮酸和 3-磷酸甘油醛）的标记模式进行了比较。结果表明，疣孢菌素 -2β-醇是通过甲羟戊酸途径合成的，而不是通过最近在一些真细菌、藻类和植物中发现的脱氧木酮糖途径。提供了一个形成不寻常四环环系的方案。环化过程由香叶基芳樟醇焦磷酸的焦磷酸溶剂解引发，其机制涉及瓦格纳 - 米尔温重排、1,5-氢迁移和环丙基甲基到环丙基甲基的重排。
