Radioresistance of Micrococcus Radiodurans during the Growth Cycle

Serianni, R. W.; Bruce, A. K.

doi:10.2307/3572645

Cited by 15 publications

(6 citation statements)

References 12 publications

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“…The relative survival rates of 1,000-Gy-irradiated cultures were 40.3% for the 5-day-old culture and 61.4% for the 10-day-old culture. Cells from a stationary-phase culture were more resistant to radiation, in agreement with previous studies of other systems, such as D. radiodurans (49). The measured relative survival rates show that G. obscuriglobus viability deteriorated by less than an order of magnitude in response to such IR doses.…”

Section: Resultssupporting

confidence: 79%

Chromatin Organization and Radio Resistance in the Bacterium Gemmata obscuriglobus

et al. 2009

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The organization of chromatin has a major impact on cellular activities, such as gene expression. For bacteria, it was suggested that the spatial organization of the genetic material correlates with transcriptional levels, implying a specific architecture of the chromosome within the cytoplasm. Accordingly, recent technological advances have emphasized the organization of the genetic material within nucleoid structures. Gemmata obscuriglobus, a member of the phylum Planctomycetes, exhibits a distinctive nucleoid structure in which chromatin is encapsulated within a discrete membrane-bound compartment. Here, we show that this soil and freshwater bacterium tolerates high doses of UV and ionizing radiation. Cryoelectron tomography of frozen hydrated sections and electron microscopy of freeze-substituted cells have indicated a more highly ordered condensed-chromatin organization in actively dividing and stationary-phase G. obscuriglobus cells. These three-dimensional analyses revealed a complex network of double membranes that engulf the condensed DNA. Bioinformatics analysis has revealed the existence of a putative component involved in nonhomologous DNA end joining that presumably plays a role in maintaining chromatin integrity within the bacterium. Thus, our observations further support the notion that packed chromatin organization enhances radiation tolerance.

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Section: Resultssupporting

confidence: 79%

Chromatin Organization and Radio Resistance in the Bacterium Gemmata obscuriglobus

et al. 2009

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“…Earlier studies established that stationary-phase cells are 3-fold more resistant than exponentially grown cells (287,548). However, according to recent studies, late-stationary-phase cells are 4-fold more sensitive than exponential-and earlystationary-phase cells (592).…”

Section: Ionizing Radiation Resistance Of D Radioduransmentioning

confidence: 83%

“…However, according to recent studies, late-stationary-phase cells are 4-fold more sensitive than exponential-and earlystationary-phase cells (592). The phasic response of cells is a result of the physiological changes occurring as a result of the passage of the organism from one metabolic state to another (548). The perturbation of exponential growth with a 1-h incubation in phosphate buffer increases radiation resistance (198,548).…”

Section: Ionizing Radiation Resistance Of D Radioduransmentioning

confidence: 99%

“…The phasic response of cells is a result of the physiological changes occurring as a result of the passage of the organism from one metabolic state to another (548). The perturbation of exponential growth with a 1-h incubation in phosphate buffer increases radiation resistance (198,548). Such a growth disruption may allow the cessation or completion of chromosome replication prior to irradiation and/or delay the onset of growth after irradiation, thereby increasing the opportunity for the repair of cell damage (198).…”

Section: Ionizing Radiation Resistance Of D Radioduransmentioning

confidence: 99%

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Oxidative Stress Resistance inDeinococcus radiodurans

Slade

Radman

2011

Microbiol Mol Biol Rev

649

639

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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.

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“…In Escherichia coli, increases in the DNA-protein ratio, through retarded protein synthesis, produce cells with increased resistance to ionizing and ultraviolet radiations (1,2,3,5,8,9,12). Also, stationary-phase cells of both Micrococcus radiodurans and E. coli were reported to be more X-ray-resistant than the corresponding cells in exponential phase (13,14). To investigate the role of the DNA-protein ratio in bacterial radioresistance, M. radiodurans was cultured exponentially and under conditions that alter such growth.…”

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confidence: 99%