Stress-induced systems in Escherichia coli and their response to terahertz radiation

We summarize the latest data concerning the reactions of Escherichia coli to nonthermal terahertz radiation. Escherichia coli is the simplest and most convenient model object for studying the effects of terahertz radiation on living organisms. Its genetics and metabolism have been well studied, and its easy accessibity to genetic engineering allows designing biosensors that employ the promoters of genes activated by certain stress factors and the reporter GFP protein. Escherichia coli cells transformed with such biosensor constructs produce easily quantitatable fluorescence in response to terahertz radiation. In this review, we present data on the reaction of certain E. сoli stress-induced systems to terahertz radiation, both ours and reported by other authors. We discuss experimental results for E. сoli/pKatGGFP, E. сoli/pCopAGFP, and E. сoli/pEmrRGFP biosensors, which are used to identify E. сoli genetic networks responding to oxidative stress, copper ion homeostasis failures, and antiseptics, respectively. The data reviewed indicate that exposure to nonthermal terahertz radiation activates E. сoli gene networks related to oxidative stress and copper ion homeostasis but does not affect those induced by antibiotics, protonophores, or superoxide anions. The fact that E. сoli/pKatGGFP and E. сoli/pCopAGFP biosensors have different activation and reaction periods when exposed to terahertz radiation and natural inducers suggests that the responses of oxidative stress and copper ion homeostasis systems to terahertz radiation are specific.