The Genes of dps, relA, and spoT are Each Important in the Resilience of Escherichia coli Exposed to UVA-Radiation during Stringency

Dps protein provides important protective effects on DNA against UVA irradiation. A previous study found that its presence during stringency increased survival of Escherichia coli upon exposure to UV, but in its absence, stringency still triggered an increase in survival. Since it was uncertain whether the observed protective effects triggered by stringency were due to Dps and other protein mechanisms or mostly to Dps alone, the aim of this study was to elucidate the relative importance of Dps. For the E. coli K12 strains BW23113 (parental dps ), and JW0797-1 ( Δdps mutant), valine was used to establish stringency while chloramphenicol (CAM) was used to simulate ΔrelAΔspoT double mutations, and inhibit protein synthesis. The experiments showed that even in the presence of Dps, the lack of stringency and protein synthesis lowered the resilience. Dps was most important for resilience against UVA, while protein synthesis and stringency were also significant and required to provide complete protection.