PNNL

Abstract

The radiation resistant bacterium Deinococcus radiodurans accumulates very high intracellular manganese and relatively low iron levels compared to the dissimilatory metal-reducing bacterium Shewanella oneidensis which is extremely sensitive. For Fe-rich, Mn-poor cells, death at low doses might be caused by the release of Fe(II) from proteins during irradiation, followed by Fe(II)-dependent reduction of hydrogen peroxide produced by metabolism after irradiation. In contrast, Mn(II) ions concentrated in D. radiodurans might serve as antioxidants that reinforce enzymic systems which defend against oxidative stress during recovery. We extend our hypothesis here to include consideration of respiration, tricarboxylic acid cycle activity, peptide transport, and metal reduction, which together with Mn(II) transport represent potential new targets to control cell recovery from radiation injury.