In vivo fragmentation of the large subunit of ribulose-1,5-bisphosphate carboxylase by reactive oxygen species in an intact leaf of cucumber under chilling-light conditions
In vivo fragmentation of the large subunit of ribulose-1,5-bisphosphate carboxylase by reactive oxygen species in an intact leaf of cucumber under chilling-light conditions
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DOI：
10.1093/pcp/pci245
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发表时间：
2006-02-01
影响因子：
4.9
通讯作者：
Mae, T
中科院分区：
文献类型：
--
作者：
Nakano, R;Ishida, H;Mae, T
以往的研究表明，核酮糖-1，5-二磷酸羧化酶（Rubisco）的大亚基（LSU）是定点切割的羟基自由基（中心点OH）中产生的叶绿体裂解液或人工中心点OH-产生系统。然而，它是不知道是否LSU的活性氧（ROS）的裂解实际上发生在一个完整的叶片。低温敏感黄瓜（Cucumis sativus L.）在4摄氏度的光照下，观察到LSU的五个主要碎片。这种断裂完全抑制活性氧清除剂，如正丙基没食子酸酯（中心点OH）和1，2-二羟基苯-3，5-二磺酸（Tiron）（超氧化物）。FeSO 4刺激这种断裂，而铁特异性螯合剂，去铁胺，抑制它。此外，这样的片段是相同的，从纯化的Rubisco的中心点OH-产生系统在体外的二维PAGE。这些结果表明，在完整的叶片中，活性氧也能直接裂解LSU。
Previous studies have demonstrated that the large subunit (LSU) of ribulose-1,5-bisphosphate carboxylase (Rubisco) is site-specifically cleaved by a hydroxyl radical (center dot OH) generated in the illuminated chloroplast lysates or by an artificial center dot OH-generating system. However, it is not known whether such cleavage of the LSU by reactive oxygen species (ROS) actually occurs in an intact leaf. When leaf discs of chilling-sensitive cucumber (Cucumis sativus L.) were illuminated at 4 degrees C, five major fragments of the LSU were observed. This fragmentation was completely inhibited by ROS scavengers, such as n-propyl gallate (for center dot OH) and 1,2-dihydroxybenzene-3,5-disulfonic acid (Tiron) (for superoxide). FeSO4 stimulated this fragmentation, whereas an iron-specific chelator, deferoxamine, suppressed it. Furthermore, such fragments were identical to those generated from the purified Rubisco by an center dot OH-generating system in vitro on two-dimensional PAGE. These results indicate that the direct fragmentation of the LSU by reacive oxygen species also occurs in an intact leaf.