Torrey T A, Kogoma T
Mol Gen Genet. 1982;187(2):225-30. doi: 10.1007/BF00331121.
The sdrA102 mutation confers upon cells the ability to replicate DNA in the absence of protein synthesis. This mutation was combined with the recA200 mutation, which renders the recA protein thermolabile, and had little effect on normal replication. However, the sdrA102 recA200 double mutant exhibited temperature-sensitive stable DNA replication: it replicated DNA continuously in the presence of chloramphenicol at 30 degrees C, whereas at 42 degrees C DNA replication ceased after the DNA content increased only 40-45%. Suppressor mutants (rin; recA-independent) capable of stable DNA replication at 42 degrees C were isolated from the double mutant. The suppressor mutant retained all other recA- characteristics, i.e., deficient general recombination, severe UV-sensitivity, and incapability of prophage induction in lysogens. This indicates that the rin mutation specifically suppresses the recA+ dependency of stable DNA replication. It is suggested that the recA+ protein stabilizes a specific structure, similar to an intermediate in recombination, which may function in the initiation of stable DNA replication.
sdrA102突变赋予细胞在缺乏蛋白质合成的情况下复制DNA的能力。该突变与recA200突变相结合，recA200突变使recA蛋白对温度敏感，且对正常复制影响很小。然而，sdrA102 recA200双突变体表现出温度敏感的稳定DNA复制：在30℃氯霉素存在的情况下它能持续复制DNA，而在42℃时，DNA含量仅增加40 - 45%后DNA复制就停止了。从双突变体中分离出了能够在42℃进行稳定DNA复制的抑制突变体（rin；不依赖recA）。该抑制突变体保留了所有其他recA - 的特性，即一般重组缺陷、严重的紫外线敏感性以及溶原菌中前噬菌体诱导能力丧失。这表明rin突变特异性地抑制了稳定DNA复制对recA + 的依赖性。有人提出recA + 蛋白稳定了一种特定结构，类似于重组中的中间体，它可能在稳定DNA复制的起始过程中发挥作用。
