Mano Jun'ichi, Kanameda Sayaka, Kuramitsu Rika, Matsuura Nagisa, Yamauchi Yasuo
Science Research Center, Organization for Research Initiatives, Yamaguchi University, Yamaguchi, Japan.
Faculty of Agriculture, Yamaguchi University, Yamaguchi, Japan.
Front Plant Sci. 2019 Apr 24;10:487. doi: 10.3389/fpls.2019.00487. eCollection 2019.
Oxidative stimuli to living cells results in the formation of lipid peroxides, from which various aldehydes and ketones (oxylipin carbonyls) are inevitably produced. Among the oxylipin carbonyls, those with an α,β-unsaturated bond are designated as reactive carbonyl species (RCS) because they have high electrophilicity and biological activity. Plants have arrays of dehydrogenases and reductases to metabolize a variety of RCS that occur in the cells, but these enzymes are not efficient to scavenge the most toxic RCS (i.e., acrolein) because they have only low affinity. Two glutathione transferase (GST) isozymes belonging to the plant-specific Tau class were recently observed to scavenge acrolein with values at a submillimolar level. This suggests that GST could also be involved in the defense system against RCS. We tested the activities of 23 Tau isozymes of for five types of RCS, and the results revealed that 11 isozymes recognized either acrolein or 4-hydroxy-()-2-nonenal or both as a substrate(s). Such RCS-scavenging activities indicate the potential contribution of GST to RCS scavenging in plants, and they may account for the stress tolerance conferred by several Tau isozymes. RCS are therefore a strong candidate for endogenous substrates of plant GSTs.
对活细胞的氧化刺激会导致脂质过氧化物的形成，由此不可避免地产生各种醛和酮（氧化脂质羰基化合物）。在氧化脂质羰基化合物中，那些具有α,β-不饱和键的被指定为反应性羰基物种（RCS），因为它们具有高亲电性和生物活性。植物具有一系列脱氢酶和还原酶来代谢细胞中出现的各种RCS，但这些酶清除毒性最强的RCS（即丙烯醛）的效率不高，因为它们的亲和力很低。最近观察到属于植物特有的Tau类的两种谷胱甘肽转移酶（GST）同工酶能以亚毫摩尔水平的 值清除丙烯醛。这表明GST也可能参与了针对RCS的防御系统。我们测试了23种 Tau同工酶对五种类型RCS的活性，结果显示有11种同工酶将丙烯醛或4-羟基-（）-2-壬烯醛或两者都识别为底物。这种RCS清除活性表明GST在植物RCS清除中具有潜在作用，并且它们可能解释了几种Tau同工酶赋予的胁迫耐受性。因此，RCS是植物GSTs内源性底物的有力候选者。
