Shuster R C, Weissbach A
J Virol. 1968 Oct;2(10):1096-101. doi: 10.1128/JVI.2.10.1096-1101.1968.
Infection of nonlysogenic Escherichia coli CR34(S) (Thy(-)) with bacteriophage lambda C(I)857 resulted in the formation of twisted circular double-stranded phage deoxyribonucleic acid (DNA; species I). When such infected bacteria were incubated in the absence of thymine, there was a significant decrease in the amount of species I DNA after 60 min of incubation. A similar loss of species I lambda DNA during incubation in a thymine-deficient medium was also observed after infection of the endonuclease I-deficient strain, E. coli 1100(S) (Thy(-)). This destruction of twisted, circular lambda DNA in thymine-deprived cells did not occur in the presence of chloramphenicol nor in lysogenic E. coli CR34 carrying a noninducible lambda prophage. It is therefore concluded that the endonuclease which attacks this circular configuration of lambda DNA is newly synthesized after infection and is directed by the phage chromosome.
用噬菌体λC（I）857感染非溶原性大肠杆菌CR34（S）（胸苷营养缺陷型），会导致形成扭曲的环状双链噬菌体脱氧核糖核酸（DNA；I型）。当将此类感染的细菌在无胸腺嘧啶的条件下培养时，培养60分钟后I型DNA的量显著减少。在用核酸内切酶I缺陷型菌株大肠杆菌1100（S）（胸苷营养缺陷型）感染后，在胸腺嘧啶缺乏的培养基中培养期间也观察到了类似的I型λDNA损失。在胸腺嘧啶缺乏的细胞中，这种扭曲的环状λDNA的破坏在氯霉素存在的情况下不会发生，也不会在携带不可诱导的λ原噬菌体的溶原性大肠杆菌CR34中发生。因此得出结论，攻击这种λDNA环状结构的核酸内切酶是在感染后新合成的，并且由噬菌体染色体指导。
