E. coli aggregation and impaired cell division after terahertz irradiation

New Insights into Radio-Resistance Mechanism Revealed by (Phospho)Proteome Analysis of Deinococcus Radiodurans after Heavy Ion Irradiation

Deinococcus radiodurans (D. radiodurans) can tolerate various extreme environments including radiation. Protein phosphorylation plays an important role in radiation resistance mechanisms; however, there is currently a lack of systematic research on this topic in D. radiodurans. Based on label-free (phospho)proteomics, we explored the dynamic changes of D. radiodurans under various doses of heavy ion irradiation and at different time points. In total, 2359 proteins and 1110 high-confidence phosphosites were identified, of which 66% and 23% showed significant changes, respectively, with the majority being upregulated. The upregulated proteins at different states (different doses or time points) were distinct, indicating that the radio-resistance mechanism is dose- and stage-dependent. The protein phosphorylation level has a much higher upregulation than protein abundance, suggesting phosphorylation is more sensitive to irradiation. There were four distinct dynamic changing patterns of phosphorylation, most of which were inconsistent with protein levels. Further analysis revealed that pathways related to RNA metabolism and antioxidation were activated after irradiation, indicating their importance in radiation response. We also screened some key hub phosphoproteins and radiation-responsive kinases for further study. Overall, this study provides a landscape of the radiation-induced dynamic change of protein expression and phosphorylation, which provides a basis for subsequent functional and applied studies.

Specific Features of the Proteomic Response of Thermophilic Bacterium Geobacillus icigianus to Terahertz Irradiation

Studying the effects of terahertz (THz) radiation on the proteome of temperature-sensitive organisms is limited by a number of significant technical difficulties, one of which is maintaining an optimal temperature range to avoid thermal shock as much as possible. In the case of extremophilic species with an increased temperature tolerance, it is easier to isolate the effects of THz radiation directly. We studied the proteomic response to terahertz radiation of the thermophilic Geobacillus icigianus, persisting under wide temperature fluctuations with a 60 °C optimum. The experiments were performed with a terahertz free-electron laser (FEL) from the Siberian Center for Synchrotron and Terahertz Radiation, designed and employed by the Institute of Nuclear Physics of the SB of the RAS. A G. icigianus culture in LB medium was THz-irradiated for 15 min with 0.23 W/cm² and 130 μm, using a specially designed cuvette. The life cycle of this bacterium proceeds under conditions of wide temperature and osmotic fluctuations, which makes its enzyme systems stress-resistant. The expression of several proteins was shown to change immediately after fifteen minutes of irradiation and after ten minutes of incubation at the end of exposure. The metabolic systems of electron transport, regulation of transcription and translation, cell growth and chemotaxis, synthesis of peptidoglycan, riboflavin, NADH, FAD and pyridoxal phosphate cofactors, Krebs cycle, ATP synthesis, chaperone and protease activity, and DNA repair, including methylated DNA, take part in the fast response to THz radiation. When the response developed after incubation, the systems of the cell's anti-stress defense, chemotaxis, and, partially, cell growth were restored, but the respiration and energy metabolism, biosynthesis of riboflavin, cofactors, peptidoglycan, and translation system components remained affected and the amino acid metabolism system was involved.