Lu Yi Chen, Luo Fang, Pu Zhong Ji, Zhang Shuang, Huang Meng Tian, Yang Hong
Jiangsu Key Laboratory of Pesticide Science, College of Sciences, Nanjing Agricultural University, Nanjing, 210095, China; College of Food Science and Light Industry, Nanjing Tech University, Nanjing, 211800, China.
Jiangsu Key Laboratory of Pesticide Science, College of Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
Chemosphere. 2016 Dec;165:487-496. doi: 10.1016/j.chemosphere.2016.09.025. Epub 2016 Sep 30.
Atrazine (ATR) as a toxic herbicide has become one of the seriously environmental contaminants worldwide due to its long-term intensive use in crop production. This study identified novel methyltransferases (MTs) involved in detoxification and degradation of ATR residues in rice plants. From a subset of MTs differentially expressed in ATR-exposed rice, forty-four O-methyltransferase genes were investigated. Total activities were significantly enhanced by ATR in rice tissues. To prove detoxifying capacity of the MTs in rice plants, two rice O-MTs (LOC_Os04g09604 and LOC_Os11g15040) were selected and transformed into yeast cells (Pichia pastoris X-33). The positive transformants accumulated less ATR and showed less toxicity. Using UPLC-TOF-MS/MS, ATR-degraded products in rice and yeast cells were characterized. A novel O-methylated-modified metabolite (atraton) and six other ATR-derivatives were detected. The topological interaction between LOC_Os04g09604 enzyme and its substrate was specially analyzed by homology modeling programs, which was well confirmed by the molecular docking analysis. The significance of the study is to provide a better understanding of mechanisms for the specific detoxification and degradation of ATR residues in rice growing in environmentally relevant ATR-contaminated soils and may hold a potential engineering perspective for generating ATR-resistant rice that helps to minimize ATR residues in crops.
阿特拉津（ATR）作为一种有毒除草剂，由于其在作物生产中的长期大量使用，已成为全球范围内严重的环境污染物之一。本研究鉴定了参与水稻植株中ATR残留解毒和降解的新型甲基转移酶（MTs）。从在ATR处理的水稻中差异表达的MTs子集中，研究了44个O-甲基转移酶基因。ATR显著提高了水稻组织中的总活性。为了证明水稻植株中MTs的解毒能力，选择了两个水稻O-MTs（LOC_Os04g09604和LOC_Os11g15040）并将其转化到酵母细胞（毕赤酵母X-33）中。阳性转化体积累的ATR较少且毒性较小。使用超高效液相色谱-飞行时间串联质谱（UPLC-TOF-MS/MS）对水稻和酵母细胞中的ATR降解产物进行了表征。检测到一种新型的O-甲基化修饰代谢物（莠去通）和其他六种ATR衍生物。通过同源建模程序专门分析了LOC_Os04g09604酶与其底物之间的拓扑相互作用，分子对接分析对此进行了很好的证实。该研究的意义在于更好地理解在环境相关的ATR污染土壤中生长的水稻对ATR残留进行特异性解毒和降解的机制，并可能为培育抗ATR水稻提供潜在的工程视角，有助于减少作物中的ATR残留。
