Quillardet Philippe, Rouffaud Marie-Ange, Bouige Philippe
Unité de Programmation Moléculaire et Toxicologie Génétique, CNRS Ura 1444, Institut Pasteur, 25, rue du Docteur Roux, 75724 Paris cédex 15, France.
Res Microbiol. 2003 Oct;154(8):559-72. doi: 10.1016/S0923-2508(03)00149-9.
The capacity of DNA macroarrays that contain all 4290 predicted open reading frames of the E. coli K12 genome was evaluated by measuring changes in gene expression in response to irradiation by ultraviolet light (UV). UV and other DNA damaging agents are known to trigger the induction of the SOS response. This is a coordinated increase in the level of expression of a set of approximately 30 unlinked genes, the SOS genes, negatively regulated by the LexA repressor. The analysis was performed on a set of isogenic strains with mutations that affect expression of genes of the SOS system: (i) the lexA+ strain, in which the SOS system can be induced after DNA damage, (ii) lexAind- mutants in which the SOS system cannot be induced, and (iii) lexAdef mutants in which the SOS system is induced constitutively. We found that a large set of genes appeared to be either upregulated or downregulated following UV irradiation. Among the genes which appeared to be upregulated in a LexA-dependent manner, we correctly identified 9 out of 27 SOS genes printed on the arrays and one gene containing a LexA binding site. One gene, dnaN, encoding the beta subunit of DNA polymerase III holoenzyme, was identified as an upregulated gene in a LexA-independent manner. Our results were compared to those of similar studies previously published. Although the SOS response as a whole could not be illustrated by using DNA arrays, the data suggest that regulation of some SOS genes might be more complex than previously thought.
通过测量大肠杆菌K12基因组中所有4290个预测的开放阅读框的DNA宏阵列在紫外线（UV）照射后基因表达的变化，对其容量进行了评估。已知UV和其他DNA损伤剂会触发SOS反应的诱导。这是一组约30个不连锁基因（即SOS基因）的表达水平的协同增加，这些基因受LexA阻遏物的负调控。分析是在一组具有影响SOS系统基因表达的突变的同基因菌株上进行的：（i）lexA +菌株，其中SOS系统在DNA损伤后可被诱导；（ii）lexAind-突变体，其中SOS系统不能被诱导；（iii）lexAdef突变体，其中SOS系统组成性诱导。我们发现，一大组基因在UV照射后似乎上调或下调。在以LexA依赖方式上调的基因中，我们正确地鉴定出阵列上打印的27个SOS基因中的9个以及一个含有LexA结合位点的基因。一个基因dnaN，编码DNA聚合酶III全酶的β亚基，被鉴定为以LexA非依赖方式上调的基因。我们的结果与先前发表的类似研究的结果进行了比较。尽管使用DNA阵列无法说明整个SOS反应，但数据表明一些SOS基因的调控可能比以前认为的更复杂。
