Mori H, Ogura T, Hiraga S
Mol Gen Genet. 1984;196(2):185-93. doi: 10.1007/BF00328049.
When bacterial cells harboring a temperature-sensitive replication plasmid, which carries the particular ccd segment (coupled cell division) containing the ccdA and ccdB genes of a mini-F plasmid, are transferred to 42 degrees C, cell division is inhibited after incubation for an appropriate time. The inhibition occurs, when the copy number of the plasmid decreases to become critically low, about one per cell (Ogura and Hiraga 1983b). In lambda phage lysogens carrying this type of plasmid, the prophage is induced in a small portion of the cell population under the same conditions, in addition to the inhibition of cell division in most of cells. The prophage induction, but not the inhibition of normal cell division, depends on normal recA function. Both induction of prophage and inhibition of cell division are suppressed by the simultaneous presence of a replication proficient plasmid carrying the ccdA gene. We discuss molecular mechanisms of the ccd function that couples host cell division to plasmid proliferation and induces the prophage. Additionally, we propose a hypothesis that the ccd mechanism of F plasmid contributes to indirect induction of prophage lambda by an F plasmid damaged by UV-irradiation and then introduced into a lysogen via conjugation.
当携带温度敏感型复制质粒的细菌细胞被转移到42摄氏度时，该质粒携带着特定的ccd片段（耦合细胞分裂），其中包含mini-F质粒的ccdA和ccdB基因，在适当的孵育时间后细胞分裂受到抑制。当质粒的拷贝数减少到极低水平，大约每个细胞一个时，就会发生这种抑制现象（小仓和平贺，1983b）。在携带这种质粒的λ噬菌体溶原菌中，除了大多数细胞中的细胞分裂受到抑制外，在相同条件下一小部分细胞群体中的原噬菌体也会被诱导。原噬菌体的诱导，而不是正常细胞分裂的抑制，取决于正常的recA功能。携带ccdA基因的复制 proficient 质粒的同时存在会抑制原噬菌体的诱导和细胞分裂的抑制。我们讨论了将宿主细胞分裂与质粒增殖耦合并诱导原噬菌体的ccd功能的分子机制。此外，我们提出了一个假设，即F质粒的ccd机制有助于通过紫外线照射受损然后通过接合引入溶原菌的F质粒间接诱导λ原噬菌体。
