Odahara Masaki, Inouye Takayuki, Fujita Tomomichi, Hasebe Mitsuyasu, Sekine Yasuhiko
Department of Life Science, College of Science, Rikkyo, St. Paul's University, Tokyo, Japan.
Genes Genet Syst. 2007 Feb;82(1):43-51. doi: 10.1266/ggs.82.43.
Homologous recombination is a universal process that contributes to genetic diversity and genomic integrity. Bacterial-type RecA generally exists in all bacteria and plays a crucial role in homologous recombination. Although RecA homologues also exist in plant mitochondria, there have been few reports about the in vivo functions of these homologues. We identified a recA gene orthologue (named PprecA1) in a cDNA library of the moss, Physcomitrella patens. N-terminal fusion of the putative organellar targeting sequence of PpRecA1 to GFP caused a targeting of PpRecA1 to mitochondria. PprecA1 partially complemented the effects of a DNA damaging agent in an Escherichia coli recA deficient strain. Additionally, the expression of PprecA1 was induced by treating the plants with DNA damaging agents. Disruption of PprecA1 by targeted replacement resulted lower rate of the recovery of the mitochondrial DNA from methyl methan sulfonate damage. This is the first report about the characteristics of a null mutant of bacterial-type recA gene in plant. The data suggest that PprecA1 participates in the repair of mitochondrial DNA in P. patens.
同源重组是一个有助于遗传多样性和基因组完整性的普遍过程。细菌型RecA普遍存在于所有细菌中，在同源重组中起关键作用。尽管RecA同源物也存在于植物线粒体中，但关于这些同源物的体内功能的报道却很少。我们在苔藓小立碗藓的cDNA文库中鉴定出一个recA基因直系同源物（命名为PprecA1）。将PpRecA1假定的细胞器靶向序列与GFP进行N端融合，导致PpRecA1靶向线粒体。PprecA1部分弥补了DNA损伤剂对大肠杆菌recA缺陷菌株的影响。此外，用DNA损伤剂处理植物可诱导PprecA1的表达。通过靶向替换破坏PprecA1会导致从甲磺酸甲酯损伤中恢复线粒体DNA的速率降低。这是关于植物中细菌型recA基因缺失突变体特征的首次报道。数据表明PprecA1参与了小立碗藓线粒体DNA的修复。
