Rodríguez M, Holcík M, Iyer V N
Department of Biology, Carleton University, Ottawa, Ontario, Canada.
J Bacteriol. 1995 Nov;177(22):6352-61. doi: 10.1128/jb.177.22.6352-6361.1995.
The transmission of plasmid pCU1 (or other IncN group plasmid) into a population of Klebsiella oxytoca cells reduces the viability of the population. A 2,400-bp region adjacent to traA is responsible for this phenotype and includes two regions, called kikA and kikC. Klebsiella cells which received this region and survived were found to acquire a chromosomal mutation which renders them immune to killing even after the plasmid is cured from the cells. To obtain insight into the mode of this apparent lethality, an appropriate pCU1lacZ derivative was constructed. It could be introduced with high efficiency into Klebsiella cells. Analyses of the resultant colonies indicate that the loss of viability is not a consequence of the death of plasmid-free segregants. On the contrary and unlike postsegregational killing by plasmids, cells survived by losing the plasmid or by acquiring, secondarily, a chromosomal mutation which confers immunity to killing.
将质粒pCU1（或其他IncN组质粒）导入产酸克雷伯菌细胞群体中会降低该群体的活力。traA附近一个2400bp的区域导致了这种表型，该区域包括两个区域，称为kikA和kikC。接受该区域并存活下来的克雷伯菌细胞被发现获得了一种染色体突变，即使质粒从细胞中消除后，这种突变也能使它们免受杀伤。为了深入了解这种明显致死性的模式，构建了合适的pCU1lacZ衍生物。它可以高效地导入克雷伯菌细胞。对所得菌落的分析表明，活力丧失不是无质粒分离菌死亡的结果。相反，与质粒的后分离杀伤不同，细胞通过丢失质粒或其次获得赋予抗杀伤能力的染色体突变而存活下来。
