Wang J, Zhang H, Allen R D
Department of Biological Sciences, Texas Tech University, Lubbock 79409, USA.
Plant Cell Physiol. 1999 Jul;40(7):725-32. doi: 10.1093/oxfordjournals.pcp.a029599.
The Arabidopsis gene APX3 that encodes a putative peroxisomal membrane-bound ascorbate peroxidase was expressed in transgenic tobacco plants. APX3-expressing lines had substantial levels of APX3 mRNA and protein. The H2O2 can be converted to more reactive toxic molecules, e.g. .OH, if it is not quickly removed from plant cells. The expression of APX3 in tobacco could protect leaves from oxidative stress damage caused by aminotriazole which inhibits catalase activity that is found mainly in glyoxysomes and peroxisomes and leads to accumulation of H2O2 in those organelles. However, these plants did not show increased protection from oxidative damage caused by paraquat which leads to the production of reactive oxygen species in chloroplasts. Therefore, protection provided by the expression of APX3 seems to be specific against oxidative stress originated from peroxisomes, not from chloroplasts, which is consistent with the hypothesis that APX3 is a peroxisomal membrane-bound antioxidant enzyme.
编码一种假定的过氧化物酶体膜结合抗坏血酸过氧化物酶的拟南芥基因APX3在转基因烟草植株中表达。表达APX3的株系具有大量的APX3 mRNA和蛋白质。如果H2O2不能迅速从植物细胞中清除，它会转化为更具活性的有毒分子，例如·OH。烟草中APX3的表达可以保护叶片免受氨基三唑引起的氧化应激损伤，氨基三唑抑制主要存在于乙醛酸循环体和过氧化物酶体中的过氧化氢酶活性，导致这些细胞器中H2O2的积累。然而，这些植株对百草枯引起氧化损伤的保护作用并未增强，百草枯会导致叶绿体中产生活性氧。因此，APX3表达提供的保护似乎对源自过氧化物酶体而非叶绿体的氧化应激具有特异性，这与APX3是一种过氧化物酶体膜结合抗氧化酶的假设一致。
