Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3 Darwin St., 28049, Madrid, Spain; SYNMIKRO, LOEWE-Zentrum für Synthetische Mikrobiologie, Hans-Meerwein-Straße, 35043, Marburg, Germany; Fachbereich Chemie, Hans-Meerwein-Straße 4, 35032, Marburg, Germany.
Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3 Darwin St., 28049, Madrid, Spain.
DNA Repair (Amst). 2019 Jun;78:27-36. doi: 10.1016/j.dnarep.2019.03.010. Epub 2019 Mar 21.
Bacterial RarA is thought to play crucial roles in the cellular response to blocked replication forks. We show that lack of Bacillus subtilis RarA renders cells very sensitive to HO, but not to methyl methane sulfonate or 4-nitroquinoline-1-oxide. RarA is epistatic to RecA in response to DNA damage. Inactivation of rarA partially suppressed the DNA repair defect of mutants lacking translesion synthesis polymerases. RarA may contribute to error-prone DNA repair as judged by the reduced frequency of rifampicin-resistant mutants in ΔrarA and in ΔpolY1 ΔrarA cells. The absence of RarA strongly reduced the viability of dnaD23ts and dnaB37ts cells upon partial thermal inactivation, suggesting that ΔrarA cells are deficient in replication fork assembly. A ΔrarA mutation also partially reduced the viability of dnaC30ts and dnaX51ts cells and slightly improved the viability of dnaG40ts cells at semi-permissive temperature. These results suggest that RarA links re-initiation of DNA replication with repair-by-recombination by controlling the access of the replication machinery to a collapsed replication fork.
细菌 RarA 被认为在细胞对受阻复制叉的反应中发挥关键作用。我们表明，枯草芽孢杆菌 RarA 的缺乏使细胞对 HO 非常敏感，但对甲基甲烷磺酸酯或 4-硝基喹啉 1-氧化物不敏感。RarA 在 DNA 损伤反应中与 RecA 上位。rarA 的失活部分抑制了缺乏跨损伤合成聚合酶的突变体的 DNA 修复缺陷。RarA 可能有助于易错 DNA 修复，这可以通过 rifampicin 抗性突变体在ΔrarA 和ΔpolY1 ΔrarA 细胞中的频率降低来判断。缺乏 RarA 会在部分热失活时强烈降低 dnaD23ts 和 dnaB37ts 细胞的存活率，表明ΔrarA 细胞在复制叉组装方面存在缺陷。ΔrarA 突变也部分降低了 dnaC30ts 和 dnaX51ts 细胞的存活率，并略微提高了 dnaG40ts 细胞在半许可温度下的存活率。这些结果表明，RarA 通过控制复制机制对塌陷复制叉的访问，将 DNA 复制的重新起始与修复相结合。
