Mauël C, Karamata D
Mol Gen Genet. 1984;194(3):451-6. doi: 10.1007/BF00425557.
Incubation of thermosensitive dna mutants of Bacillus subtilis at the non-permissive temperature leads in some instances to induction of defective prophage PBSX and cell lysis. A clear distinction can be made between mutants affected in DNA replication at the growing point (extension mutants) and those unable to initiate new rounds of replication (initiation mutants). The former promote PBSX induction to a variable and mutation-specific extent, whereas the latter do not exhibit any signs of induction. Analysis of mutants carrying two dna mutations suggests that products of some dna genes involved in initiation and in extension are not essential for induction but can substantially amplify its extent. However, mitomycin C treatment of dna mutants which have completed their residual DNA synthesis leads to a PBSX induction essentially identical to that obtained by mitomycin C treatment of the wild-type strain, which precludes an essential role for any of the mutated proteins in this induction process. On the basis of our observations we propose that the induction signal is related to the number of blocked replication forks: the larger that number, the higher the proportion of induced cells within the population.
将枯草芽孢杆菌的温度敏感型DNA突变体在非允许温度下培养，在某些情况下会导致缺陷前噬菌体PBSX的诱导和细胞裂解。在生长点影响DNA复制的突变体（延伸突变体）和那些无法启动新一轮复制的突变体（起始突变体）之间可以做出明确区分。前者以可变的、特定于突变的程度促进PBSX诱导，而后者没有表现出任何诱导迹象。对携带两个DNA突变的突变体的分析表明，一些参与起始和延伸的DNA基因的产物对于诱导不是必需的，但可以显著放大其程度。然而，对已经完成其残余DNA合成的DNA突变体进行丝裂霉素C处理，会导致PBSX诱导基本上与通过对野生型菌株进行丝裂霉素C处理所获得的诱导相同，这排除了任何突变蛋白在该诱导过程中的关键作用。根据我们的观察，我们提出诱导信号与受阻复制叉的数量有关：该数量越大，群体中诱导细胞的比例越高。
