Non‐cytoplasmic localization of a Dps protein from Deinococcus radiodurans

Deinococcus radiodurans , a Gram‐positive eubacterium is widely recognized for its extreme resistance to various DNA‐damaging conditions, such as desiccation and ionizing and ultraviolet radiation. D. radiodurans is one of only a few bacteria which encode two different DNA protection during starvation (Dps) proteins. We report here a comparison of both Dps homologs from D. radiodurans . Dps‐2 was found to bind to DNA with a much lower affinity than Dps‐1 and both have the ability to oxidize Fe 2+ . Dps‐2 protects DNA from degradation by reactive oxygen species (ROS) where as Dps‐1 cannot. Dps‐1 was shown to condense DNA in vivo while Dps‐2 was incapable of doing so. In vivo localization assays showed that unlike all previously characterized Dps proteins, Dps‐2 is non‐cytoplasmically localized. While Dps‐1 may serve a function in iron homeostasis, the function of Dps‐2 may be to protect against ROS‐mediated hydroxyl radical damage. Together these proteins may contribute to D. radiodurans ability to withstand such extreme environments.