ИСТИНА

E. coli 6S RNA is a small noncoding RNA which can bind RNA polymerase holoenzyme and regulate its activity. It’s well known that under starvation E. coli wild type has an advantage in comparison to cells with knockout of 6S RNA gene (Δ6S), while under alkaline stress conditions the opposite effect was observed. According to our previous experimental data, the survival of Δ6S strain significantly decreases in the presence of high concentrations of hydrogen peroxide (oxidative stress conditions). However, it’s still unclear how cellular stress response depends on 6S RNA functioning and why it leads to this phenotype. The therapeutic effect of some antibacterial drugs based on induction of reactive oxygen species, which are lethal for bacteria. Therefore, understanding of mechanisms of 6S RNA-dependent gene expression under oxidative stress might contribute to solving the problem of rapidly increasing bacterial resistance to antibiotics. The aim of this study was to find certain E. coli genes, which expression is dysregulated in the absence of 6S RNA under oxidative stress. We selected 15 genes encoding major oxidative stress response proteins and estimated by RT-qPCR their mRNA levels in E. coli wild type and in Δ6S strains before and after addition of hydrogen peroxide to cell cultures. GapA was chosen as a reference gene. SodA, yaaA and ahpC genes demonstrated 2-fold decrease of their transcription efficiency in case of 6S RNA knockout strain. They encode the enzymes participating in utilization of active oxygen species inside the cell. We also have shown that 6S RNA activates expression of the important transcription factor – oxidative stress-inducible protein SoxS. These findings may explain resistance of the E. coli wild type cells to hydrogen peroxide treatment in contrast to Δ6S strain. This work was supported by Russian Scientific Foundation (project No. 14-24-00061).