Mitochondrial and peroxisomal manganese superoxide dismutase:: differential expression during leaf senescence
Mitochondrial and peroxisomal manganese superoxide dismutase:: differential expression during leaf senescence
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DOI：
10.1093/jxb/erg091
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发表时间：
2003-03-01
影响因子：
6.9
通讯作者：
Zilinskas, BA
中科院分区：
文献类型：
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作者：
del Río, LA;Sandalio, LM;Zilinskas, BA
在豌豆叶片中，锰超氧化物歧化酶（Mn-SOD）主要定位于线粒体和过氧化物酶体。在这项工作中，研究了叶片衰老对豌豆离体叶片过氧化物酶体和线粒体Mn-SOD的影响，豌豆离体叶片在25度的黑暗中孵育3-11 d。与豌豆叶片线粒体Mn-SOD编码cDNA和线粒体Mn-SOD转运肽特异性探针杂交的Northern blots显示，叶片衰老期间Mn-SOD转录水平增加，部分原因是线粒体Mn-SOD mRNA增加。利用重组表达的线粒体Mn-SOD，在豌豆叶片中纯化的过氧化物酶体中产生与Mn-SOD交叉反应的多克隆抗体。对豌豆线粒体Mn-SOD抗体粗提物进行Western blot检测发现，随着叶片衰老，总Mn-SOD蛋白水平逐渐升高。在天然PAGE作用下，豌豆叶片总Mn-SOD活性随衰老而升高。采用电镜免疫细胞化学方法对衰老叶片线粒体和过氧化物酶体Mn-SOD进行区分。线粒体中Mn-SOD标记增强，而过氧化物酶体的免疫金标记不随衰老而改变。总之，这些结果表明线粒体和过氧化物酶体Mn-SOD的表达受到不同的调控。在豌豆叶片衰老过程中，线粒体Mn-SOD的表达受到诱导，而过氧化物酶体Mn-SOD可被翻译后激活。先前报道的结果显示，线粒体Mn-SOD活性降低，过氧化物酶体Mn-SOD活性升高，这可能反映了叶片衰老过程中调节酶活性的翻译后事件。
In pea (Pisum sativum L.) leaves, manganese superoxide dismutase (Mn-SOD) is mainly localized in mitochondria as well as in peroxisomes. In this work, the effect of leaf senescence on the peroxisomal and mitochondrial Mn-SOD was studied in detached leaves from pea plants which were incubated in the dark at 25degreesC for 3-11 d. Northern blots hybridized with a cDNA encoding mitochondrial Mn-SOD from pea leaves and a mitochondrial Mn-SOD transit peptide-specific probe showed increased Mn-SOD transcript levels during leaf senescence, due in part to increased mitochondrial Mn-SOD mRNA. Recombinantly-expressed mitochondrial Mn-SOD was used to raise polyclonal antibodies which cross-reacted with Mn-SOD in peroxisomes purified from pea leaves. Western blot assays of crude extracts with the antibodies to pea mitochondrial Mn-SOD showed that the levels of total Mn-SOD protein gradually increased with leaf senescence. By native PAGE, the total Mn-SOD activity of pea leaves increased with senescence. EM immunocytochemistry was used to distinguish mitochondrial and peroxisomal Mn-SOD in senescent leaves. Increased Mn-SOD labelling in mitochondria was intensified, whereas the immunogold labelling of peroxisomes did not change with senescence. Overall, these results show that mitochondrial and peroxisomal Mn-SOD expression is regulated differently. The expression of mitochondrial Mn-SOD is induced during the senescence of pea leaves, whereas peroxisomal Mn-SOD could be post-translationally activated. Previously described results showing decreased mitochondrial Mn-SOD activity and increased peroxisomal Mn-SOD activity may be reflective of post-translational events regulating enzymatic activity during leaf senescence.