Elucidation of novel archaeal mevalonate pathways oriented to metabolic engineering application

古细菌甲羟戊酸途径中的一部分反应未被鉴定。因此，我们进行了转换试验的放射性标记的底物的无细胞提取物从古细菌和古细菌同系物的已知甲羟戊酸途径相关的酶的功能表征。结果发现，硫化叶菌属古细菌中存在着罕见的甲羟戊酸代谢途径，而热浆菌属古细菌中存在着一条新的甲羟戊酸代谢途径，即3-磷酸甲羟戊酸代谢途径，并对硫化叶菌属古细菌中的2型异戊烯基二磷酸异构酶和二磷酸甲羟戊酸脱羧酶进行了X射线晶体结构研究。所获得的结构和各种分析的结果显示了新的催化机制，活性调节和热稳定性。

A part of reactions in the archaeal mevalonate pathways were unidentified. Thus we performed the conversion assay of radio-labeled substrates by cell-free extract from archaea and functional characterization of archaeal homologs of known mevalonate pathway-related enzymes. As the result, we discovered the classical mevalonate pathway, which is rare in archaea, from an archaeon of genus Sulfolobus, and a novel modified pathway, which passes through 3-phosphomevalonate, from an archaeon of genus Thermoplasma.We also performed X-ray crystal structural studies on type 2 isopentenyl diphosphate isomerase and diphosphomevalonate decarboxylase from archaea of genus Sulfolobus. The obtained structures and the results of various analyses showed novel mechanisms of catalysis, regulation of activity, and thermostabilization.