The mechanism of recA polA lethality: suppression by RecA-independent recombination repair activated by the lexA(Def) mutation in Escherichia coli.
The mechanism of recA polA lethality: suppression by RecA-independent recombination repair activated by the lexA(Def) mutation in Escherichia coli.
复制标题
recA polA 致死机制：大肠杆菌中 lexA(Def) 突变激活的 RecA 独立重组修复的抑制。
DOI：
10.1093/genetics/139.4.1483
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发表时间：
1995
期刊：
影响因子：
3.3
通讯作者：
Kogoma,T
中科院分区：
文献类型：
--
作者：
Cao,Y;Kogoma,T
研究了recA polA对大肠杆菌的致死机制。互补测试表明，5'-->3' 核酸外切酶和 DNA 聚合酶 I 的聚合活性对于 RecA 蛋白缺失下的生存能力至关重要，而 DNA 聚合酶 I 缺陷细胞的生存能力和 DNA 复制则取决于 RecA 的重组酶活性。碱性蔗糖梯度沉降分析表明 RecA 在冈崎片段处理中仅发挥很小的作用。双链断裂修复被认为是在 DNA 聚合酶 I 缺失的情况下 RecA 的主要作用。 lexA(Def)::Tn5 突变先前已被证明可以抑制 recA200(Ts) polA25::spc 突变体的温度敏感生长。 lexA(Def) 突变可以减轻限制温度下 recA200(Ts) polA25::spc 突变细胞中 DNA 合成受损的情况。 recF+ 对于该抑制途径至关重要。 recJ和recQ突变对抑制有轻微但显着的不利影响。 recA200(Ts) polA25::spc lexA(Def) 突变体中的recA200(Ts) 等位基因可以被delta recA 取代，表明lexA(Def) 诱导的抑制是RecA 独立的。 lexA(Def) 可将 delta recA polA25::spc 细胞对紫外线损伤的敏感性降低约 10(4) 倍。 lexA(Def) 还将 delta recA polA25::spc 突变体的 P1 转导效率恢复至 recA+ 野生型的 7.3% 水平。这些结果表明，lexA(Def) 激活了不依赖于 RecA、依赖于 RecF 的重组修复途径，从而抑制了 recA polA 双突变体中 DNA 复制的缺陷。
The mechanism of recA polA lethality in Escherichia coli has been studied. Complementation tests have indicated that both the 5'-->3' exonuclease and the polymerization activities of DNA polymerase I are essential for viability in the absence of RecA protein, whereas the viability and DNA replication of DNA polymerase I-defective cells depend on the recombinase activity of RecA. An alkaline sucrose gradient sedimentation analysis has indicated that RecA has only a minor role in Okazaki fragment processing. Double-strand break repair is proposed for the major role of RecA in the absence of DNA polymerase I. The lexA(Def)::Tn5 mutation has previously been shown to suppress the temperature-sensitive growth of recA200(Ts) polA25::spc mutants. The lexA(Def) mutation can alleviate impaired DNA synthesis in the recA200(Ts) polA25::spc mutant cells at the restrictive temperature. recF+ is essential for this suppression pathway. recJ and recQ mutations have minor but significant adverse effects on the suppression. The recA200(Ts) allele in the recA200(Ts) polA25::spc lexA(Def) mutant can be replaced by delta recA, indicating that the lexA(Def)-induced suppression is RecA independent. lexA(Def) reduces the sensitivity of delta recA polA25::spc cells to UV damage by approximately 10(4)-fold. lexA(Def) also restores P1 transduction proficiency to the delta recA polA25::spc mutant to a level that is 7.3% of the recA+ wild type. These results suggest that lexA(Def) activates a RecA-independent, RecF-dependent recombination repair pathway that suppresses the defect in DNA replication in recA polA double mutants.