Multiple modes of protection against hydrogen peroxide-induced oxidative damage in stationary and exponential phase Escherichia coli by DNA-binding protein (Dps)

Abstract

Bacteria have evolved various mechanisms to protect against oxidative stress. Previous studies have demonstrated a bimodal mechanism of the DNA-binding protein (Dps), which confers DNA protection in unique manners. In this study, we investigated the involvement of Dps against hydrogen peroxide-induced stress in E. coli ZK126 and the dps mutant E. coli ZK1146 in exponential and stationary phases. Survival and mutagenesis of these strains were assessed following hydrogen peroxide treatments. We found that wild-type cells survived better than the mutant, yet exhibited considerable mutation rates in the stationary phase, which suggests DNA damage. Restriction endonuclease digestion of genomic DNA corroborates the existence of different DNA conformations in the two phases and strains.