Weitao T, Dasgupta S, Nordström K
Department of Cell and Molecular Biology, Uppsala University, Biomedical Center, Box 596, S-751 24 Uppsala, Sweden.
Mol Microbiol. 2000 Oct;38(2):392-400. doi: 10.1046/j.1365-2958.2000.02138.x.
The intracellular locations of oriC and oriR1, the replication origins of the chromosome and plasmid R1, respectively, were visualized by fluorescence in situ hybridization (FISH) in exponentially growing populations of Escherichia coli. The locations of oriC and oriR1 (from a Par+ R1 plasmid) were unique and different in the wild-type host. In a mukB mutant, the positions were perturbed for both origins. The position of oriR1 from a plasmid with active partition (Par+) in the mukB host was as randomized as that of oriR1 from the Par- plasmid in a wild-type host. However, this mukB-induced randomization did not result in unstable inheritance of the Par+ plasmid, as measured by the conventional segregation assay. This might result from the preferential association of the Par+ plasmid with the bigger, decondensed nucleoid-containing daughters during cell division of MukB- cells, whereas the Par- plasmids were distributed at random and were lost by frequently ending up in anucleate cells.
通过荧光原位杂交（FISH）技术，在指数生长期的大肠杆菌群体中观察到了染色体复制起点oriC和质粒R1复制起点oriR1的细胞内定位。oriC和oriR1（来自Par + R1质粒）在野生型宿主中的位置是独特且不同的。在mukB突变体中，两个复制起点的位置都受到了干扰。在mukB宿主中，具有活性分配功能（Par +）的质粒的oriR1位置与野生型宿主中Par - 质粒的oriR1位置一样随机。然而，通过传统的分离分析测定，这种由mukB诱导的随机化并没有导致Par + 质粒的不稳定遗传。这可能是由于在MukB - 细胞的细胞分裂过程中，Par + 质粒优先与较大的、解聚的含类核的子代细胞结合，而Par - 质粒则随机分布，并且由于经常最终进入无核细胞而丢失。
