嗜糖假单胞菌中两种表型互补的异柠檬酸脱氢酶。
Two phenotypically compensating isocitrate dehydrogenases in Ralstonia eutropha.
作者信息
Wang Zheng-Xiang, Brämer Christian, Steinbüchel Alexander
机构信息
Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Corrensstrabetae 3, 48149, Münster, Germany.
出版信息
FEMS Microbiol Lett. 2003 Oct 10;227(1):9-16. doi: 10.1016/S0378-1097(03)00612-8.
The tricarboxylic acid (TCA) cycle enzyme isocitrate dehydrogenase (IDH) and the glyoxylate bypass enzyme isocitrate lyase are involved in catabolism of isocitrate and play a key role in controlling the metabolic flux between the TCA cycle and the glyoxylate shunt. Two IDH genes icd1 and icd2 of Ralstonia eutropha HF39, encoding isocitrate dehydrogenase 1 (IDH1) and isocitrate dehydrogenase 2 (IDH2), were identified and characterized. Icd1 was functionally expressed in Escherichia coli, whereas icd2 was expressed in E. coli but no activity was obtained. Interposon-mutants of icd1 (HF39Deltaicd1) and icd2 (HF39Deltaicd2) of R. eutropha HF39 were constructed and their phenotypes were investigated. HF39Deltaicd1 retained 43% of IDH activity, which was not induced by acetate, and HF39Deltaicd2 expressed 74% of acetate-induced IDH activity. Both HF39Deltaicd1and HF39Deltaicd2 kept the same growth rate on acetate as the wild-type. These data suggested that IDH1 is induced by acetate. The interposon-mutants HF39Deltaicd1 and HF39Deltaicd2 accumulated the same amount of poly(3-hydroxybutyric acid) as the wild-type.
三羧酸（TCA）循环酶异柠檬酸脱氢酶（IDH）和乙醛酸支路酶异柠檬酸裂解酶参与异柠檬酸的分解代谢，并在控制TCA循环和乙醛酸分流之间的代谢通量中起关键作用。鉴定并表征了真养产碱菌HF39的两个IDH基因icd1和icd2，它们分别编码异柠檬酸脱氢酶1（IDH1）和异柠檬酸脱氢酶2（IDH2）。Icd1在大肠杆菌中实现了功能表达，而icd2虽在大肠杆菌中表达，但未获得活性。构建了真养产碱菌HF39的icd1（HF39Deltaicd1）和icd2（HF39Deltaicd2）的插入突变体，并对其表型进行了研究。HF39Deltaicd1保留了43%的IDH活性，该活性不受乙酸盐诱导，而HF39Deltaicd2表达了74%的乙酸盐诱导的IDH活性。HF39Deltaicd1和HF39Deltaicd2在乙酸盐上的生长速率与野生型相同。这些数据表明IDH1是由乙酸盐诱导的。插入突变体HF39Deltaicd1和HF39Deltaicd2积累的聚（3-羟基丁酸）量与野生型相同。
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