The organization of Physcomitrella patens RAD51 genes is unique among eukaryotic organisms
The organization of Physcomitrella patens RAD51 genes is unique among eukaryotic organisms
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DOI：
10.1073/pnas.032668199
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发表时间：
2002-03-05
影响因子：
11.1
通讯作者：
Reiss, B
中科院分区：
文献类型：
--
作者：
Markmann-Mulisch, U;Hadi, MZ;Reiss, B
基因重组途径和基因已经得到了很好的研究，但对植物，特别是低等植物的基因重组知之甚少。为了研究低地植物的重组机制，从苔藓小立藓（Physcomitrella patens）中分离出一个在酵母菌、小鼠和人类中都有明显特征的重组基因RAD51基因，并对其进行了鉴定。发现存在两个高度同源的RAD51基因。到目前为止，复制的RAD51基因仅在具有复制基因组的真核生物中被发现。因此，两个高度同源基因的存在表明，小立壶菌的祖先中最近发生了基因组重复事件。与其他生物Rad51蛋白序列的比较表明，这两个Rad51基因都起源于植物Rad51蛋白群。然而，这两个蛋白在植物Rad51蛋白的系统发育树上形成了一个独立的分支。与其他多细胞真核生物的RAD51基因不同，小壶菌的RAD51基因不会被内含子打断。由于内含子是小立壶菌基因的共同特征，RAD51基因中缺乏内含子是不寻常的，这可能表明该生物中存在不寻常的重组装置。存在重复的无内含子RAD51基因在真核生物中是独一无二的。需要对这一谱系的进一步成员进行研究，以确定这种特征是否可能是低等植物的典型特征。
Genetic recombination pathways and genes are well studied, but relatively little is known in plants, especially in lower plants. To study the recombination apparatus of a lower land plant, a recombination gene well characterized particularly in yeast, mouse, and man, the RAD51 gene, was isolated from the moss Physcomitrella patens and characterized. Two highly homologous RAD51 genes were found to be present. Duplicated RAD51 genes have been found thus far exclusively in eukaryotes with duplicated genomes. Therefore the presence of two highly homologous genes suggests a recent genome duplication event in the ancestry of Physcomitrella. Comparison of the protein sequences to Rad51 proteins from other organisms showed that both RAD51 genes originated within the group of plant Rad51 proteins. However, the two proteins form a separate clade in a phylogenetic tree of plant Rad51 proteins. In contrast to RAD51 genes from other multicellular eukaryotes, the Physcomitrella genes are not interrupted by introns. Because introns are a common feature of Physcomitrella genes, the lack of introns in the RAD51 genes is unusual and may indicate the presence of an unusual recombination apparatus in this organism. The presence of duplicated intronless RAD51 genes is unique among eukaryotes. Studies of further members of this lineage are needed to determine whether this feature may be typical of lower plants.