Lehrbach P R, Lee B T, Dirckze C D
J Bacteriol. 1979 Sep;139(3):953-60. doi: 10.1128/jb.139.3.953-960.1979.
The effect of R plasmids on spontaneous and radiation (ultraviolet and gamma)-induced mutability in Pseudomonas aeruginosa was studied in strains containing the radiation-sensitive markers polA3 or rec-2 and the revertable auxotrophic markers hisO27 and trpB1. In the absence of an R plasmid, the radiation-induced mutability was dependent on the recA+ genotype and independent of the polA+ genotype, whereas spontaneous mutability was similar in all genetic backgrounds. R plasmids pPL1, R2, and pMG15 increased the ultraviolet radiation survival and ultraviolet-induced mutability of wild-type and polA host cells but did not alter either effect in a recA mutant. These R plasmids also increased the gamma radiation survival and gamma-induced mutability of wild-type host cells bud pMG15 also enhanced the level of spontaneous mutagenesis in wild-type host cells but not in a polA or recA mutant. These data suggested that a common plasmid gene product(s) may participate in various recA-dependent, error-prone deoxyribonucleic acid repair pathways of P. aeruginosa. The properties of a mutant R plasmid, pPL2, originally selected because it lacked enhanced ultraviolet-induced mutability, supported this conclusion.
利用含有辐射敏感标记polA3或rec - 2以及可回复营养缺陷型标记hisO27和trpB1的菌株，研究了R质粒对铜绿假单胞菌自发突变及辐射（紫外线和γ射线）诱导突变的影响。在没有R质粒的情况下，辐射诱导的突变性依赖于recA +基因型，而与polA +基因型无关，而自发突变性在所有遗传背景中相似。R质粒pPL1、R2和pMG15提高了野生型和polA宿主细胞对紫外线的存活率以及紫外线诱导的突变性，但对recA突变体的这两种效应均无改变。这些R质粒还提高了野生型宿主细胞对γ射线的存活率以及γ射线诱导的突变性，并且pMG15还提高了野生型宿主细胞的自发诱变水平，但对polA或recA突变体则无此作用。这些数据表明，一种常见的质粒基因产物可能参与了铜绿假单胞菌各种依赖recA的易错脱氧核糖核酸修复途径。最初因缺乏增强的紫外线诱导突变性而筛选出的突变R质粒pPL2的特性支持了这一结论。
