Shiota N, Kodama S, Inui H, Ohkawa H
Department of Biological and Environmental Science, Faculty of Agriculture, Kobe University, Nada, Japan.
Biosci Biotechnol Biochem. 2000 Oct;64(10):2025-33. doi: 10.1271/bbb.64.2025.
Among 11 isoforms of the human cytochrome P450 enzymes metabolizing xenobiotics, CYP 1A1 and CYP 1A2 were major P450 species in the metabolism of the herbicides chlortoluron and atrazine in a yeast expression system. CYP1A2 was more active in the metabolism of both herbicides than CYP1A1. The fused enzymes of CYP1A1 and CYP1A2 with yeast NADPH-cytochrome P450 oxidoreductase were functionally active in the microsomal fraction of the yeast Saccharomyces cerevisiae and showed increased specific activity towards 7-ethoxyresorufin as compared to CYP1A1 and CYP1A2 alone. Then, both fused enzymes were each expressed in the microsomes of tobacco (Nicotiana tabacum cv. Samsun NN) plants. The transgenic plants expressing the CYP1A2 fusion enzyme had higher resistance to the herbicide chlortoluron than the plants expressing the CYP1A1 fusion enzyme did. The transgenic plants expressing the CYP1A2 fused enzyme metabolized chlortoluron to a larger extent to its non-phytotoxic metabolites through N-demethylation and ring-methyl hydroxylation as compared to the plants expressing the CYP1A1 fused enzyme. Thus, the possibility of increasing the herbicide resistance in the transgenic plants by the selection of P450 species and the fusion with P450 reductase is discussed.
在人类代谢外源性物质的11种细胞色素P450酶亚型中，CYP 1A1和CYP 1A2是酵母表达系统中除草剂绿麦隆和莠去津代谢过程中的主要P450种类。CYP1A2在两种除草剂的代谢中比CYP1A1更具活性。CYP1A1和CYP1A2与酵母NADPH - 细胞色素P450氧化还原酶的融合酶在酿酒酵母的微粒体部分具有功能活性，并且与单独的CYP1A1和CYP1A2相比，对7 - 乙氧基试卤灵表现出更高的比活性。然后，两种融合酶分别在烟草（Nicotiana tabacum cv. Samsun NN）植株的微粒体中表达。表达CYP1A2融合酶的转基因植株比表达CYP1A1融合酶的植株对除草剂绿麦隆具有更高的抗性。与表达CYP1A1融合酶的植株相比，表达CYP1A2融合酶的转基因植株通过N - 去甲基化和环甲基羟基化将绿麦隆更大程度地代谢为非植物毒性代谢物。因此，讨论了通过选择P450种类以及与P450还原酶融合来提高转基因植株除草剂抗性的可能性。
