Modulating radiation resistance:: Insights based on defenses against reactive oxygen species in the radioresistant bacterium Deinococcus radiodurans

The classical dogma of radiation biology asserts that the cytotoxic effects of ionizing radiation (IR) are principally the result of DNA damage. Yet many organisms that encode a complement of DNA repair functions are killed by IR doses that cause little DNA damage. Instead, proteins likely are the first major class of molecules damaged by IR. This article presents a new perspective on extreme IR resistance in the eubacterium Deinococcus radiodurans, reevaluates the role of superoxide (O-2(.-)) ions in IR toxicity, and speculates on potential strategies for controlling resistance in prokaryotes and eukaryotes based on scavenging IR-induced O-2(.-).