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首页> 外文期刊>Journal of Experimental Botany >RecA maintains the integrity of chloroplast DNA molecules in Arabidopsis
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RecA maintains the integrity of chloroplast DNA molecules in Arabidopsis

机译：RecA维护拟南芥中叶绿体DNA分子的完整性

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摘要

Although our understanding of mechanisms of DNA repair in bacteria and eukaryotic nuclei continues to improve, almost nothing is known about the DNA repair process in plant organelles, especially chloroplasts. Since the RecA protein functions in DNA repair for bacteria, an analogous function may exist for chloroplasts. The effects on chloroplast DNA (cpDNA) structure of two nuclear-encoded, chloroplast-targeted homologues of RecA in Arabidopsis were examined. A homozygous T-DNA insertion mutation in one of these genes (cpRecA) resulted in altered structural forms of cpDNA molecules and a reduced amount of cpDNA, while a similar mutation in the other gene (DRT100) had no effect. Double mutants exhibited a similar phenotype to cprecA single mutants. The cprecA mutants also exhibited an increased amount of single-stranded cpDNA, consistent with impaired RecA function. After four generations, the cprecA mutant plants showed signs of reduced chloroplast function: variegation and necrosis. Double-stranded breaks in cpDNA of wild-type plants caused by ciprofloxacin (an inhibitor of Escherichia coli gyrase, a type II topoisomerase) led to an alteration of cpDNA structure that was similar to that seen in cprecA mutants. It is concluded that the process by which damaged DNA is repaired in bacteria has been retained in their endosymbiotic descendent, the chloroplast.
机译：尽管我们对细菌和真核细胞中DNA修复机制的理解不断提高，但对植物细胞器（尤其是叶绿体）中DNA修复过程的了解却很少。由于RecA蛋白在细菌的DNA修复中起作用，因此叶绿体可能存在类似的功能。研究了拟南芥中RecA的两个核编码，叶绿体靶向的同源物对叶绿体DNA（cpDNA）结构的影响。这些基因之一（cpRecA）中的纯合T-DNA插入突变导致cpDNA分子的结构形式改变和cpDNA数量减少，而另一个基因（DRT100）的类似突变则无效。双突变体表现出与cprecA单突变体相似的表型。 cprecA突变体还表现出增加的单链cpDNA量，与RecA功能受损相一致。四代后，cprecA突变植物显示出叶绿体功能降低的迹象：杂色和坏死。环丙沙星（大肠杆菌回旋酶抑制剂，II型拓扑异构酶）引起的野生型植物cpDNA的双链断裂导致cpDNA结构的改变，类似于cprecA突变体。结论是，在细菌中修复受损的DNA的过程已保留在其共生共生体后裔叶绿体中。

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