Niki H, Ogura T, Hiraga S
Department of Molecular Genetics, Kumamoto University Medical School, Japan.
Mol Gen Genet. 1990 Oct;224(1):1-9. doi: 10.1007/BF00259444.
The hopE mutants of Escherichia coli, which cannot stably maintain a mini-F plasmid during cell division, have mutations in the recD gene coding for subunit D of the RecBCD enzyme (exonuclease V). A large amount of linear multimer DNA of mini-F and pBR322 plasmid accumulates in these hopE mutants. The linear multimers of plasmid DNA in the hopE (recD) mutants accumulate in sbc+ genetic backgrounds and this depends on the recA+ gene function. Linear plasmid multimers also accumulated in a recBC xthA triple mutant, but not an isogenic xth A mutant or an isogenic recBC mutant. The recBC xth A mutant is defective in the conjugative type of recombination. Linear plasmid multimers were not detected in the recBC strain. We propose models to account for linear multimer formation of plasmids in various mutants.
大肠杆菌的hopE突变体在细胞分裂过程中不能稳定维持微型F质粒，其recD基因发生突变，该基因编码RecBCD酶（外切核酸酶V）的亚基D。在这些hopE突变体中积累了大量微型F和pBR322质粒的线性多聚体DNA。hopE（recD）突变体中质粒DNA的线性多聚体在sbc +遗传背景中积累，这取决于recA +基因功能。线性质粒多聚体也在recBC xthA三重突变体中积累，但不在同基因的xthA突变体或同基因的recBC突变体中积累。recBC xthA突变体在接合型重组中存在缺陷。在recBC菌株中未检测到线性质粒多聚体。我们提出了模型来解释各种突变体中质粒线性多聚体的形成。
