Strike P, Lodwick D
Department of Genetics, University of Liverpool, UK.
J Cell Sci Suppl. 1987;6:303-21. doi: 10.1242/jcs.1984.supplement_6.20.
Many bacterial plasmids have the effect of increasing the ultraviolet (u.v.) resistance of host cells that harbour them, apparently by an error-prone repair mechanism that leads to a high level of mutation amongst the survivors. These plasmid systems are apparently analogues of the Escherichia coli umuD/C operon, which is absolutely required in this organism for mutation induced by u.v. light and by many chemical mutagens. This article reviews the extensive and sometimes conflicting literature relating to this phenomenon, and describes the further characterization of one such plasmid system, the imp (I group mutation and protection) operon of the I1 group plasmid TP110. It is demonstrated that each of the protection mutation systems well characterized to date shows a similar genetic arrangement, and that significant homology can be detected at the amino acid level between the proteins encoded by these different systems.
许多细菌质粒具有增强宿主细胞紫外线（uv）抗性的作用，这些宿主细胞携带着它们，显然是通过一种易出错的修复机制，这种机制会导致存活下来的细胞中出现高水平的突变。这些质粒系统显然类似于大肠杆菌umuD/C操纵子，在该生物体中，uv光和许多化学诱变剂诱导的突变绝对需要该操纵子。本文综述了与这一现象相关的广泛且有时相互矛盾的文献，并描述了一种这样的质粒系统——I1组质粒TP110的imp（I组突变与保护）操纵子的进一步特征。结果表明，迄今为止得到充分表征的每个保护突变系统都显示出相似的基因排列，并且在这些不同系统所编码的蛋白质之间，在氨基酸水平上可以检测到显著的同源性。
