Herz S, Wungsintaweekul J, Schuhr C A, Hecht S, Luttgen H, Sagner S, Fellermeier M, Eisenreich W, Zenk M H, Bacher A, Rohdich F
Lehrstuhl für Organische Chemie und Biochemie, Technische Universität München, Lichtenbergstrasse 4, D-85747 Garching, Germany.
Proc Natl Acad Sci U S A. 2000 Mar 14;97(6):2486-90. doi: 10.1073/pnas.040554697.
In many microorganisms, the putative orthologs of the Escherichia coli ygbB gene are tightly linked or fused to putative orthologs of ygbP, which has been shown earlier to be involved in terpenoid biosynthesis. The ygbB gene of E. coli was expressed in a recombinant E. coli strain and was shown to direct the synthesis of a soluble, 17-kDa polypeptide. The recombinant protein was found to convert 4-diphosphocytidyl-2C-methyl-D-erythritol 2-phosphate into 2C-methyl-D-erythritol 2,4-cyclodiphosphate and CMP. The structure of the reaction product was established by NMR spectroscopy using (13)C-labeled substrate samples. The enzyme-catalyzed reaction requires Mn(2+) or Mg(2+) but no other cofactors. Radioactivity from [2-(14)C]2C-methyl-D-erythritol 2,4-cyclodiphosphate was diverted efficiently to carotenoids by isolated chromoplasts from Capsicum annuum and, thus, was established as an intermediate in the deoxyxylulose phosphate pathway of isoprenoid biosynthesis. YgbB protein also was found to convert 4-diphosphocytidyl-2C-methyl-D-erythritol into 2C-methyl-D-erythritol 3,4-cyclophosphate. This compound does not serve as substrate for the formation of carotenoids by isolated chromoplasts and is assumed to be an in vitro product without metabolic relevance.
在许多微生物中，大肠杆菌ygbB基因的假定直系同源基因与ygbP的假定直系同源基因紧密连锁或融合，此前已证明ygbP参与萜类生物合成。大肠杆菌的ygbB基因在重组大肠杆菌菌株中表达，并被证明可指导合成一种可溶性的17 kDa多肽。发现该重组蛋白可将4-二磷酸胞苷-2C-甲基-D-赤藓糖醇2-磷酸转化为2C-甲基-D-赤藓糖醇2,4-环二磷酸和CMP。使用(13)C标记的底物样品通过核磁共振光谱确定了反应产物的结构。酶催化反应需要Mn(2+)或Mg(2+)，但不需要其他辅因子。来自[2-(14)C]2C-甲基-D-赤藓糖醇2,4-环二磷酸的放射性被来自辣椒的分离的有色体有效地转移到类胡萝卜素中，因此被确定为类异戊二烯生物合成的脱氧木酮糖磷酸途径中的一种中间体。还发现YgbB蛋白可将4-二磷酸胞苷-2C-甲基-D-赤藓糖醇转化为2C-甲基-D-赤藓糖醇3,4-环磷酸。该化合物不能作为分离的有色体形成类胡萝卜素的底物，被认为是一种无代谢相关性的体外产物。
