Banerjee S K, Borden A, Christensen R B, LeClerc J E, Lawrence C W
Department of Biophysics, University of Rochester School of Medicine and Dentistry, New York 14642.
J Bacteriol. 1990 Apr;172(4):2105-12. doi: 10.1128/jb.172.4.2105-2112.1990.
We have transfected SOS-induced and uninduced cells of a uvrA6 strain of Escherichia coli with single-stranded M13mp7-based vectors that carried a single trans-syn T-T cyclobutane dimer at a unique site. Unlike constructs carrying the cis-syn isomer of this lesion, these vectors could be replicated with modest efficiency (14%) in the absence of SOS induction and therefore provided an opportunity to measure directly the influence of such induction on error rate and mutation spectrum. We found that translesion synthesis in the absence of SOS induction was remarkably accurate; only 4% of the replicated bacteriophage contained mutations, which were exclusively targeted single T deletions. In SOS-induced cells, error frequency increased to 11% and the resulting mutations included targeted substitutions and near-targeted single base additions, as well as the T deletions. Replication efficiency was 29% in these conditions. SOS induction therefore leads not only to an enhanced capacity to replicate damaged DNA but also to a marked change in mutation frequency and spectrum.
我们用基于单链M13mp7的载体转染了大肠杆菌uvrA6菌株中SOS诱导型和未诱导型细胞，这些载体在一个独特位点携带单个反式-syn T-T环丁烷二聚体。与携带该损伤顺式-syn异构体的构建体不同，这些载体在没有SOS诱导的情况下能够以适度的效率（14%）进行复制，因此提供了一个直接测量这种诱导对错误率和突变谱影响的机会。我们发现，在没有SOS诱导的情况下，跨损伤合成非常准确；只有4%的复制噬菌体含有突变，这些突变都是靶向单个T缺失。在SOS诱导的细胞中，错误频率增加到11%，产生的突变包括靶向替换、近靶向单碱基添加以及T缺失。在这些条件下，复制效率为29%。因此，SOS诱导不仅导致复制受损DNA的能力增强，还导致突变频率和谱的显著变化。
