Laboratory of Enzyme Technology, Department of Agricultural Biotechnology, Agricultural University of Athens, 75 Iera Odos Street, 11855 Athens, Greece.
Planta. 2012 Jun;235(6):1253-69. doi: 10.1007/s00425-011-1572-z. Epub 2011 Dec 28.
Plant glutathione transferases (GSTs) comprise a large family of inducible enzymes that play important roles in stress tolerance and herbicide detoxification. Treatment of Phaseolus vulgaris leaves with the aryloxyphenoxypropionic herbicide fluazifop-p-butyl resulted in induction of GST activities. Three inducible GST isoenzymes were identified and separated by affinity chromatography. Their full-length cDNAs with complete open reading frame were isolated using RACE-RT and information from N-terminal amino acid sequences. Analysis of the cDNA clones showed that the deduced amino acid sequences share high homology with GSTs that belong to phi and tau classes. The three isoenzymes were expressed in E. coli and their substrate specificity was determined towards 20 different substrates. The results showed that the fluazifop-inducible glutathione transferases from P. vulgaris (PvGSTs) catalyze a broad range of reactions and exhibit quite varied substrate specificity. Molecular modeling and structural analysis was used to identify key structural characteristics and to provide insights into the substrate specificity and the catalytic mechanism of these enzymes. These results provide new insights into catalytic and structural diversity of GSTs and the detoxifying mechanism used by P. vulgaris.
植物谷胱甘肽 S-转移酶（GSTs）是一个庞大的家族，包括许多诱导酶，它们在胁迫耐受和除草剂解毒中起着重要作用。用芳氧苯氧丙酸类除草剂氟草烟丁酯处理菜豆叶片，导致 GST 活性诱导。通过亲和层析鉴定并分离出三种可诱导的 GST 同工酶。使用 RACE-RT 和 N 末端氨基酸序列信息，分离得到全长 cDNA 和完整开放阅读框。对 cDNA 克隆的分析表明，推导的氨基酸序列与属于 phi 和 tau 类的 GST 具有高度同源性。三种同工酶在大肠杆菌中表达，并测定了它们对 20 种不同底物的底物特异性。结果表明，来自菜豆的氟草烟诱导型谷胱甘肽 S-转移酶（PvGSTs）催化广泛的反应，并表现出相当不同的底物特异性。分子建模和结构分析用于鉴定关键的结构特征，并深入了解这些酶的底物特异性和催化机制。这些结果为 GST 的催化和结构多样性以及菜豆的解毒机制提供了新的见解。
