Simić D, Vuković-Gacić B, Ajanović A, Knezević-Vukcević J
Botanical Institute and Garden, University of Belgrade, Yugoslavia.
Mutat Res. 1991 May;254(3):255-62. doi: 10.1016/0921-8777(91)90064-v.
Activation of the RecA protein following UV-irradiation or bleomycin (BM) treatment was measured in rec mutants of E. coli by monitoring beta-galactosidase activity. We provide evidence here that the defect in the recN mutant results in high constitutive and induced levels of activated RecA protein. In all rec mutants studied, with the exception of the recN mutant, induction of enzyme activity, following DNA-damaging treatments, was reduced relative to the wild type. The kinetics of induced sfiA expression indicates that the DNA-unwinding activity of the RecBCD enzyme plays a major role in SOS-signal formation. The RecF protein is not needed for BM induction in strains with a functional RecBCD pathway of recombination. However, a functional product of recF gene is implied in the formation of an efficient inducing signal after UV-irradiation, as well as in the additional processing of BM-induced lesions after exposure to the drug. A fully expressed RecF pathway of recombination does not provide a high level of activated RecA protein following DNA-damaging treatments.
通过监测β-半乳糖苷酶活性，在大肠杆菌的rec突变体中测定紫外线照射或博来霉素（BM）处理后RecA蛋白的激活情况。我们在此提供证据表明，recN突变体中的缺陷导致活化的RecA蛋白具有高水平的组成型和诱导型表达。在所有研究的rec突变体中，除了recN突变体，DNA损伤处理后酶活性的诱导相对于野生型降低。诱导的sfiA表达动力学表明，RecBCD酶的DNA解旋活性在SOS信号形成中起主要作用。在具有功能性RecBCD重组途径的菌株中，BM诱导不需要RecF蛋白。然而，recF基因的功能性产物在紫外线照射后有效诱导信号的形成中发挥作用，并且在暴露于药物后BM诱导损伤的额外处理中也发挥作用。在DNA损伤处理后，完全表达的RecF重组途径不会产生高水平的活化RecA蛋白。
