Colasanti J, Denhardt D T
J Virol. 1985 Mar;53(3):807-13. doi: 10.1128/JVI.53.3.807-813.1985.
The A* gene of bacteriophage phi X174 has been cloned into the inducible expression vector pCQV2 under conditions allowing its lethal action to be controlled by the lambda cI857 repressor. Upon induction of expression, DNA synthesis in Escherichia coli carrying the recombinant plasmid is severely inhibited; however, these same cells permit beta-galactosidase induction at a rate similar to that observed in control cells at the inducing (for A*) temperature. Cells in which A* is expressed form filaments and produce more RecA protein, indicating at least a partial induction of the SOS response; however, there is no evidence of damage to the bacterial chromosome. It appears that the A* protein has as one function the inhibition of cell division and DNA replication but not transcription or protein synthesis during phage infection.
噬菌体φX174的A基因已被克隆到可诱导表达载体pCQV2中，其致死作用可由λcI857阻遏物控制。诱导表达后，携带重组质粒的大肠杆菌中的DNA合成受到严重抑制；然而，这些相同的细胞在诱导（针对A）温度下允许β-半乳糖苷酶以与对照细胞中观察到的速率相似的速度进行诱导。表达A的细胞形成丝状并产生更多的RecA蛋白，表明SOS反应至少部分被诱导；然而，没有证据表明细菌染色体受到损伤。看来A蛋白在噬菌体感染期间的一个功能是抑制细胞分裂和DNA复制，但不抑制转录或蛋白质合成。
