Yoshimoto H, Yoshikawa M
J Bacteriol. 1975 Nov;124(2):661-7. doi: 10.1128/jb.124.2.661-667.1975.
An Hfr strain of Escherichia coli K-12 was obtained by integrative suppression with a thermosensitive plasmid, Rts1. The R plasmid was integrated into the chromosome between rif and thr, and transfer of the chromosome occurred counterclockwise. The thermosensitivity of host cell growth due to the dnaA mutation was markedly but not completely reduced in this integratively suppressed Hfr strain. When the dnaA mutation was removed by transducing the dnaA+ genome to this Hfr, the thermosensitivity of cell growth due to existence of Rts1 was suppressed in contrast to strains carrying it autonomously. Thermosensitivity of cell growth appeared again when the plasmid was detached from the chromosome to exist autonomously. Contrary to the effect on cell growth, the transfer of the chromosome and the plasmid itself and the ability to "restrict" T-even phages were still thermosensitive in all of these strains carrying Rts1, irrespective of its state of existence. The detached plasmid as well as the original Rts1 were segregated upon growth at 42 C. These data are discussed in relation to chromosome-plasmid interaction. One of the most important conculusions is that some plasmid genes, related to their replication, are phenotypically suppressed by the chromosome when it is integrated.
通过用温度敏感质粒Rts1进行整合抑制，获得了大肠杆菌K - 12的高频重组（Hfr）菌株。R质粒整合到染色体上rif和thr之间，染色体的转移呈逆时针方向。在这种整合抑制的Hfr菌株中，由于dnaA突变导致的宿主细胞生长温度敏感性显著但未完全降低。当通过将dnaA +基因组转导到该Hfr中去除dnaA突变时，与自主携带Rts1的菌株相比，由于Rts1的存在而导致的细胞生长温度敏感性受到抑制。当质粒从染色体上脱离而自主存在时，细胞生长的温度敏感性再次出现。与对细胞生长的影响相反，在所有携带Rts1的这些菌株中，无论其存在状态如何，染色体和质粒本身的转移以及“限制”T偶数噬菌体的能力仍然是温度敏感的。在42℃生长时，分离出的质粒以及原始的Rts1会发生分离。结合染色体 - 质粒相互作用对这些数据进行了讨论。最重要的结论之一是，一些与质粒复制相关的基因，在整合到染色体上时，其表型受到染色体的抑制。
