Ostaszewska-Bugajska Monika, Rychter Anna M, Juszczuk Izabela M
Institute of Experimental Plant Biology and Biotechnology, Faculty of Biology, University of Warsaw, Poland.
J Plant Physiol. 2015 Aug 15;186-187:25-38. doi: 10.1016/j.jplph.2015.07.011. Epub 2015 Aug 20.
We examined the functioning of the antioxidative defense system in Arabidopsis thaliana under sulphur (S) deficiency with an emphasis on the role of mitochondria. In tissue extracts and in isolated mitochondria from S-deficient plants, the concentration of non-protein thiols declined but protein thiols did not change. Superoxide anion and hydrogen peroxide were accumulated in leaf blades and the generation of superoxide anion by isolated mitochondria was higher. Lower abundance of reduced (GSH) plus oxidized (GSSG) glutathione in the leaf and root tissues, and leaf mitochondria from S-deficient plants was accompanied by a decrease in the level of GSH and the changes in the GSH/GSSG ratios. In the chloroplasts, the total level of glutathione decreased. Lower levels of reduced (AsA) and oxidized (DHA) ascorbate were reflected in much higher ratios of AsA/DHA. Sulphur deficiency led to an increase in the activity of cytosolic, mitochondrial and chloroplastic antioxidative enzymes, peroxidases, catalases and superoxide dismutases. The protein carbonyl level was higher in the leaves of S-deficient plants and in the chloroplasts, while in the roots, leaf and root mitochondria it remained unchanged. Protease activity in leaf extracts of S-deficient plants was higher, but in root extracts it did not differ. The proteolytic system reflected subcellular specificity. In leaf and root mitochondria the protease activity was higher, whereas in the chloroplasts it did not change. We propose that the preferential incorporation of S to protein thiols and activation of antioxidative and proteolytic systems are likely important for the survival of S-deficient plants and that the mitochondria maintain redox homeostasis.
我们研究了硫（S）缺乏条件下拟南芥抗氧化防御系统的功能，重点关注线粒体的作用。在缺硫植物的组织提取物和分离的线粒体中，非蛋白质硫醇的浓度下降，但蛋白质硫醇没有变化。超氧阴离子和过氧化氢在叶片中积累，分离的线粒体中超氧阴离子的生成更高。缺硫植物的叶片、根系以及叶片线粒体中还原型（GSH）加氧化型（GSSG）谷胱甘肽的丰度降低，同时伴随着GSH水平的下降和GSH/GSSG比值的变化。在叶绿体中，谷胱甘肽的总水平降低。还原型（AsA）和氧化型（DHA）抗坏血酸水平的降低反映在AsA/DHA比值高得多。硫缺乏导致细胞质、线粒体和叶绿体抗氧化酶、过氧化物酶、过氧化氢酶和超氧化物歧化酶的活性增加。缺硫植物叶片和叶绿体中的蛋白质羰基水平较高，而在根系、叶片和根系线粒体中则保持不变。缺硫植物叶片提取物中的蛋白酶活性较高，但根系提取物中的蛋白酶活性没有差异。蛋白水解系统反映了亚细胞特异性。叶片和根系线粒体中的蛋白酶活性较高，而叶绿体中的蛋白酶活性没有变化。我们认为，硫优先掺入蛋白质硫醇以及抗氧化和蛋白水解系统的激活可能对缺硫植物的存活很重要，并且线粒体维持氧化还原稳态。
