Glutathionylspermidine Conjugate as a Potential Protective Agent of DNA Damage Caused by Oxidative Stress and UV Exposure

Glutathionylspermidine (G-Sp) produced by E. coli bacteria is a conjugate of the thiol glutathione (GSH) and po- lyamine spermidine. Compounds containing sulfhydryl and amino groups are known for their abilities to shield DNA from the damage caused by free radicals and other oxidants. In our study we tested the hypothesis that G-Sp might be a better protective agent against DNA damage than GSH and spermidine individually. The DNA plasmid was exposed to UV damage or reactive oxygen species produced during a Fenton-like reaction in the presence of GSH, spermidine, or G-Sp. G-Sp demonstrated very similar properties to GSH and did not appear to have any advantages in protecting DNA in vitro. There was no difference in the sensitivity to hydrogen peroxide treatment between control E. coli cells, cells incapable of G-Sp synthesis, and cells overpro- ducing G-Sp. Cells overproducing G-Sp were slightly more sensitive to UV exposure than control cells or cells lacking G-Sp. All together these results suggest that DNA protection is not a major function of glutathionylspermidine in bacterial cells.