Shibata Tatsuya, Hishida Takashi, Kubota Yoshino, Han Yong-Woon, Iwasaki Hiroshi, Shinagawa Hideo
Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan.
Genes Cells. 2005 Mar;10(3):181-91. doi: 10.1111/j.1365-2443.2005.00831.x.
Escherichia coli RecA protein plays a role in DNA homologous recombination, recombination repair, and the rescue of stalled or collapsed replication forks. The mgsA (rarA) gene encodes a highly conserved DNA-dependent ATPase, whose yeast orthologue, MGS1, plays a role in maintaining genomic stability. In this study, we show a functional relationship between mgsA and recA during DNA replication. The mgsA recA double mutant grows more slowly and has lower viability than a recA single mutant, but they are equally sensitive to UV-induced DNA damage. Mutations in mgsA and recA cause lethality in DNA polymerase I deficient cells, and suppress the temperature-dependent growth defect of dnaE486 (Pol III alpha-catalytic subunit). Moreover, recAS25P, a novel recA allele identified in this work, does not complement the slow growth of DeltamgsA DeltarecA cells or the lethality of polA12 DeltarecA, but is proficient in DNA repair, homologous recombination, SOS mutagenesis and SOS induction. These results suggest that RecA and MgsA are functionally redundant in rescuing stalled replication forks, and that the DNA repair and homologous recombination functions of RecA are separated from its function to maintain progression of replication fork.
大肠杆菌RecA蛋白在DNA同源重组、重组修复以及停滞或崩溃的复制叉的拯救过程中发挥作用。mgsA（rarA）基因编码一种高度保守的依赖DNA的ATP酶，其酵母同源物MGS1在维持基因组稳定性方面发挥作用。在本研究中，我们展示了DNA复制过程中mgsA与recA之间的功能关系。mgsA recA双突变体比recA单突变体生长更缓慢且活力更低，但它们对紫外线诱导的DNA损伤同样敏感。mgsA和recA中的突变在DNA聚合酶I缺陷细胞中导致致死性，并抑制dnaE486（Pol IIIα催化亚基）的温度依赖性生长缺陷。此外，recAS25P是在本研究中鉴定出的一个新的recA等位基因，它不能弥补DeltamgsA DeltarecA细胞的生长缓慢或polA12 DeltarecA的致死性，但在DNA修复、同源重组、SOS诱变和SOS诱导方面功能正常。这些结果表明，RecA和MgsA在拯救停滞的复制叉方面功能冗余，并且RecA的DNA修复和同源重组功能与其维持复制叉进展的功能是分开的。
