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Salt shield: intracellular salts provide cellular protection against ionizing radiation in the halophilic archaeon, Halobacterium salinarum NRC-1.
- Source :
-
Environmental microbiology [Environ Microbiol] 2009 May; Vol. 11 (5), pp. 1066-78. - Publication Year :
- 2009
-
Abstract
- The halophilic archaeon Halobacterium salinarum NRC-1 was used as a model system to investigate cellular damage induced by exposure to high doses of ionizing radiation (IR). Oxidative damages are the main lesions from IR and result from free radicals production via radiolysis of water. This is the first study to quantify DNA base modification in a prokaryote, revealing a direct relationship between yield of DNA lesions and IR dose. Most importantly, our data demonstrate the significance of DNA radiation damage other than strand breaks on cell survival. We also report the first in vivo evidence of reactive oxygen species scavenging by intracellular halides in H. salinarum NRC-1, resulting in increased protection against nucleotide modification and carbonylation of protein residues. Bromide ions, which are highly reactive with hydroxyl radicals, provided the greatest protection to cellular macromolecules. Modified DNA bases were repaired in 2 h post irradiation, indicating effective DNA repair systems. In addition, measurements of H. salinarum NRC-1 cell interior revealed a high Mn/Fe ratio similar to that of Deinococcus radiodurans and other radiation-resistant microorganisms, which has been shown to provide a measure of protection for proteins against oxidative damage. The work presented here supports previous studies showing that radiation resistance is the product of mechanisms for cellular protection and detoxification, as well as for the repair of oxidative damage to cellular macromolecules. The finding that not only Mn/Fe but also the presence of halides can decrease the oxidative damage to DNA and proteins emphasizes the significance of the intracellular milieu in determining microbial radiation resistance.
- Subjects :
- DNA Damage
DNA Repair
Free Radical Scavengers metabolism
Halobacterium salinarum chemistry
Iron analysis
Manganese analysis
Microbial Viability
Radiation-Protective Agents metabolism
Reactive Oxygen Species toxicity
Salts metabolism
Free Radical Scavengers pharmacology
Halobacterium salinarum metabolism
Halobacterium salinarum radiation effects
Radiation, Ionizing
Radiation-Protective Agents pharmacology
Salts pharmacology
Subjects
Details
- Language :
- English
- ISSN :
- 1462-2920
- Volume :
- 11
- Issue :
- 5
- Database :
- MEDLINE
- Journal :
- Environmental microbiology
- Publication Type :
- Academic Journal
- Accession number :
- 19452594
- Full Text :
- https://doi.org/10.1111/j.1462-2920.2008.01828.x