Oxidative Stress Resistance inDeinococcus radiodurans

Abstract

SUMMARY Deinococcus radiodurans is a robust bacterium best known for its capacity to repair massive DNA damage efficiently and accurately. It is extremely resistant to many DNA-damaging agents, including ionizing radiation and UV radiation (100 to 295 nm), desiccation, and mitomycin C, which induce oxidative damage not only to DNA but also to all cellular macromolecules via the production of reactive oxygen species. The extreme resilience of D. radiodurans to oxidative stress is imparted synergistically by an efficient protection of proteins against oxidative stress and an efficient DNA repair mechanism, enhanced by functional redundancies in both systems. D. radiodurans assets for the prevention of and recovery from oxidative stress are extensively reviewed here. Radiation- and desiccation-resistant bacteria such as D. radiodurans have substantially lower protein oxidation levels than do sensitive bacteria but have similar yields of DNA double-strand breaks. These findings challenge the concept of DNA as the primary target of radiation toxicity while advancing protein damage, and the protection of proteins against oxidative damage, as a new paradigm of radiation toxicity and survival. The protection of DNA repair and other proteins against oxidative damage is imparted by enzymatic and nonenzymatic antioxidant defense systems dominated by divalent manganese complexes. Given that oxidative stress caused by the accumulation of reactive oxygen species is associated with aging and cancer, a comprehensive outlook on D. radiodurans strategies of combating oxidative stress may open new avenues for antiaging and anticancer treatments. The study of the antioxidation protection in D. radiodurans is therefore of considerable potential interest for medicine and public health.

Coherent X-ray diffractive imaging on the single-cell-level of microbial samples

“…Moreover, the bacterium is able to actively grow under chronic irradiation of 50 Gy/h [56]. Along the line of extreme resistance, D. radiodurans has been shown to be resistant to desiccation on the scale of years and UV-radiation [56,277].…”

“…a decrease of di usion of DNA fragments, a protection from free radicals and by preventing double strand breaks caused by proximal single strand breaks [277]. [277] but other media for high cell density production are known as well [120].…”

“…Assuming hypothetically that multiple copies of the genome are part of these dense regions within the single cells one can deduce a mass of about 110 ± 40 fg for the smallest unit of these genome copies. According to [277] there are at least 2 copies within one cell and there may be up to 10. Hence, the mass of a single genome may be close to 55 fg for the analysed cells.…”

“…The bacterium is nonpathogenic, nonmotile, red-pigmented, Grampositive and well-known due to its outstanding resistance to ionizing-radiation and oxidative stress [7,51,55,56,164,169,180,184,277]. For instance, D. radiodurans R1 reaches a D 10 value of 10 kGy [51], i.e.…”

“…To date, there have been identi ed ve to six layers: (i) the cytoplasmic membrane, (ii) the rigid peptidoglycan-containing holey layer, (iii) the compartmentalized layer, (iv) an outer membrane, (v) a distinct electrolucent zone, and (vi) the S-layer which contains hexagonally packed subunits [184,277]. There are many studies addressing the ne structure of D. radiodurans by using TEM and thin slices of stained and resin-embedded cellular material but also cryo-electron microscopy of vitreous sections and cryo-electron tomography studies have been carried out [48,75,76].…”