von Meyenburg K, Boye E, Skarstad K, Koppes L, Kogoma T
J Bacteriol. 1987 Jun;169(6):2650-8. doi: 10.1128/jb.169.6.2650-2658.1987.
The alternative pathway of DNA replication in rnh mutants of Escherichia coli can be continuously initiated in the presence of chloramphenicol, giving rise to constitutive stable DNA replication (cSDR). We conducted a physiological analysis of cSDR in rnh-224 mutants in the presence or absence of the normal DNA replication system. The following results were obtained. cSDR allowed the cells to grow in the absence of the normal replication system at a 30 to 40% reduced growth rate and with an approximately twofold-decreased DNA content. cSDR initiation was random with respect to time in the cell cycle as well as choice of origins. cSDR initiation continued to increase exponentially for more than one doubling time when protein synthesis was inhibited by chloramphenicol. cSDR initiation was inhibited during amino acid starvation in stringent (relA+) but not in relaxed (relA1) strains, indicating its sensitivity to ppGpp. cSDR initiation was rifampin sensitive, demonstrating that RNA polymerase was involved. cSDR functioned in dnaA+ rnh-224 strains parallel to the normal oriC+ dnaA+-dependent chromosome replication system.
大肠杆菌rnh突变体中的DNA复制替代途径在氯霉素存在的情况下可连续起始，从而产生组成型稳定DNA复制（cSDR）。我们对存在或不存在正常DNA复制系统的rnh - 224突变体中的cSDR进行了生理学分析。获得了以下结果。cSDR使细胞能够在不存在正常复制系统的情况下生长，生长速率降低30%至40%，DNA含量降低约两倍。cSDR起始在细胞周期的时间以及起始点的选择方面是随机的。当氯霉素抑制蛋白质合成时，cSDR起始在超过一个倍增时间内持续呈指数增加。在严格（relA +）但非松弛（relA1）菌株中，氨基酸饥饿期间cSDR起始受到抑制，表明其对ppGpp敏感。cSDR起始对利福平敏感，表明RNA聚合酶参与其中。cSDR在dnaA + rnh - 224菌株中与正常oriC + dnaA +依赖性染色体复制系统平行发挥作用。
