Garzón A, Beuzón C R, Mahan M J, Casadesús J
Departamento de Genética, Facultad de Biologia, Universidad de Sevilla, Sevilla, Spain.
Mol Gen Genet. 1996 Mar 20;250(5):570-80. doi: 10.1007/BF02174445.
recB recJ mutants of Salmonella typhimurium are deficient in transduction of chromosomal markers and ColE1-derived plasmids, and also in the maintenance of ColE1 and F plasmids. Plasmid instability is less severe in recD recJ strains; ColE1 plasmid DNA preparations from these strains show an increased yield of high molecular weight (HMW) linear multimers and a concomitant reduction in plasmid monomers compared to the wild type. Plasmids remain unstable in recA recD recJ mutants; since these do not produce HMW linear concatemers, we propose that a decrease in monomer production leads to plasmid instability. recB recJ strains also display decreased viability, a component of which may be related to their deficiency in DNA repair. In contrast to their severe defects in recombination, DNA repair and plasmid maintenance, recB recJ mutants of S. typhimurium behave similarly to the wild type in the segregation of chromosome duplications. The latter observation suggests that neither RecBCD nor RecJ functions are required for chromosomal recombination events that do not involve the use of free ends as recombination substrates.
鼠伤寒沙门氏菌的recB recJ突变体在染色体标记和ColE1衍生质粒的转导方面存在缺陷，在ColE1和F质粒的维持方面也存在缺陷。recD recJ菌株中的质粒不稳定性较轻；与野生型相比，这些菌株的ColE1质粒DNA制备物显示高分子量（HMW）线性多聚体的产量增加，同时质粒单体减少。质粒在recA recD recJ突变体中仍然不稳定；由于这些突变体不产生HMW线性多联体，我们提出单体产量的降低导致质粒不稳定。recB recJ菌株还表现出活力下降，其中一个因素可能与其DNA修复缺陷有关。与它们在重组、DNA修复和质粒维持方面的严重缺陷形成对比的是，鼠伤寒沙门氏菌的recB recJ突变体在染色体复制的分离方面表现与野生型相似。后一观察结果表明，对于不涉及使用自由末端作为重组底物的染色体重组事件，RecBCD和RecJ功能都不是必需的。
