Toothman P
J Virol. 1981 May;38(2):621-31. doi: 10.1128/JVI.38.2.621-631.1981.
Deletion analysis indicated that the phage lambda restriction alleviation gene(s) ral resides between the cIII and N genes. The Ral+ phenotype was expressed only when lambda ral+ carried a modification such that it was resistant to restriction by the host specificity system. Under these conditions, Ral function protected superinfecting unmodified phages from restriction by EcoK or EcoB but not from restriction by EcoP1. Ral-protected phage DNA was not concomitantly K and B modified, but rather received only the modification specified by the system of the restricting host. Possible mechanisms for Ral action are discussed. Of the other lambdoid phages tested, the hybrid phage lambda rev had Ral activity, whereas phi 80vir and one lambda-P22 hybrid did not. The restriction alleviation activity of lambda rev called Lar, may be the same as the activity expressed in sbcA- strains of Escherichia coli, but it was functionally separable from exonuclease VIII activity (the product of the recE gene), which is also expressed in sbcA- strains.
缺失分析表明，噬菌体λ限制缓解基因ral位于cIII和N基因之间。只有当λral +携带一种修饰使其对宿主特异性系统的限制具有抗性时，Ral +表型才会表达。在这些条件下，Ral功能保护超感染的未修饰噬菌体免受EcoK或EcoB的限制，但不能免受EcoP1的限制。Ral保护的噬菌体DNA不会同时进行K和B修饰，而是仅接受限制宿主系统指定的修饰。讨论了Ral作用的可能机制。在测试的其他类λ噬菌体中，杂交噬菌体λrev具有Ral活性，而φ80vir和一种λ-P22杂交噬菌体则没有。λrev的限制缓解活性称为Lar，可能与在大肠杆菌sbcA -菌株中表达的活性相同，但在功能上可与核酸外切酶VIII活性（recE基因的产物）分离，核酸外切酶VIII活性也在sbcA -菌株中表达。
