Identifying the Proteins that Mediate the Ionizing Radiation Resistance of Deinococcus Radiodurans R1 (original) (raw)
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Genetics, 2004
During the first hour after a sublethal dose of ionizing radiation, 72 genes were upregulated threefold or higher in D. radiodurans R1. Thirty-three of these loci were also among a set of 73 genes expressed in R1 cultures recovering from desiccation. The five transcripts most highly induced in response to each stress are the same and encode proteins of unknown function. The genes (ddrA, ddrB, ddrC, ddrD, and pprA) corresponding to these transcripts were deleted, both alone and in all possible two-way combinations. Characterization of the mutant strains defines three epistasis groups that reflect different cellular responses to ionizing radiation-induced damage. The ddrA and ddrB gene products have complementary activities and inactivating both loci generates a strain that is more sensitive to ionizing radiation than strains in which either single gene has been deleted. These proteins appear to mediate efficient RecA-independent processes connected to ionizing radiation resistance. The pprA gene product is not necessary for homologous recombination during natural transformation, but nevertheless may participate in a RecA-dependent process during recovery from radiation damage. These characterizations clearly demonstrate that novel mechanisms significantly contribute to the ionizing radiation resistance in D. radiodurans.
Transcriptome dynamics of Deinococcus radiodurans recovering from ionizing radiation
Proceedings of The National Academy of Sciences, 2003
Deinococcus radiodurans R1 (DEIRA) is a bacterium best known for its extreme resistance to the lethal effects of ionizing radiation, but the molecular mechanisms underlying this phenotype remain poorly understood. To define the repertoire of DEIRA genes responding to acute irradiation (15 kGy), transcriptome dynamics were examined in cells representing early, middle, and late phases of recovery by using DNA
Expression recA R1 Is a Novel Regulator of radiodurans Deinococcus The IrrE Protein of
2014
IRS24 is a DNA damage-sensitive strain of Deinococcus radiodurans strain 302 carrying a mutation in an uncharacterized locus designated irrE. Five overlapping cosmids capable of restoring ionizing radiation resistance to IRS24 were isolated from a genomic library. The ends of each cloned insert were sequenced, and these sequences were used to localize irrE to a 970-bp region on chromosome I of D. radiodurans R1. The irrE gene corresponds to coding sequence DR0167 in the R1 genome. The irrE gene encodes a 35,000-Da protein that has no similarity to any previously characterized peptide. The irrE locus of R1 was also inactivated by transposon mutagenesis, and this strain was sensitive to ionizing radiation, UV light, and mitomycin C. Preliminary findings indicate that IrrE is a novel regulatory protein that stimulates transcription of the recA gene following exposure to ionizing radiation.
Proteomic analysis ofDeinococcus radiodurans recovering from ?-irradiation
Proteomics, 2005
In order to reveal the mechanisms of the extreme radioresistance and DNA repair in Deinococcus radiodurans, we examined proteome changes in a wild-type strain following γ-irradiation using two-dimensional polyacrylamide gel electrophoresis and Silver-staining. The expression levels of 26 protein spots showed significant changes under radiation stress. Of these spots, 21 were identified with peptide mass fingerprinting using matrix-assisted laser desorption/ionization-time of flight mass spectrometry after tryptic in-gel digestion. These proteins exhibited various cellular functions, including (i) translation; (ii) transcription; (iii) signal transduction; (iv) post-translational modification, protein turnover, chaperones; (v) carbohydrate transport and metabolism; (vi) energy production and conversion; (vii) nucleotide transport and metabolism; (viii) inorganic ion transport and metabolism; (ix) DNA replication, recombination and repair; and (x) yet unknown. Most of the proteins have not previously been reported to be relevant to radioresistance.
Oncotarget, 2016
The role of the pprI gene from Deinococcus radiodurans R1 in therapy of acute radiation injury of a mammalian host was investigated. We injected a plasmid containing the pprI gene into the muscle of mice exposed to total 6Gy of 60Co γ-ray radiation. After injection, we used in vivo gene electroporation technology to transfer the pprI gene into the cell. We found the PprI protein was expressed significantly at 1 d after irradiation, but there was no expression of pprI gene 7 d post-irradiation. The expression of pprI gene evidently decreased the death rate of mice exposed to lethal dose radiation, significantly relieved effects on blood cells in the acute stage, shortened the persistence time of the decrease of lymphocytes, and decreased the apoptotic rates of spleen cells, thymocytes and bone marrow cells. The expression of Rad51 protein in the lungs, livers, and kidneys was significantly higher in the mice treated with the pprI plasmid after irradiation. However, there were no obvi...
Physiologic Determinants of Radiation Resistance in Deinococcus radiodurans
Applied and Environmental Microbiology, 2000
Immense volumes of radioactive wastes, which were generated during nuclear weapons production, were disposed of directly in the ground during the Cold War, a period when national security priorities often surmounted concerns over the environment. The bacterium Deinococcus radiodurans is the most radiationresistant organism known and is currently being engineered for remediation of the toxic metal and organic components of these environmental wastes. Understanding the biotic potential of D. radiodurans and its global physiological integrity in nutritionally restricted radioactive environments is important in development of this organism for in situ bioremediation. We have previously shown that D. radiodurans can grow on rich medium in the presence of continuous radiation (6,000 rads/h) without lethality. In this study we developed a chemically defined minimal medium that can be used to analyze growth of this organism in the presence and in the absence of continuous radiation; whereas cell growth was not affected in the absence of radiation, cells did not grow and were killed in the presence of continuous radiation. Under nutrient-limiting conditions, DNA repair was found to be limited by the metabolic capabilities of D. radiodurans and not by any nutritionally induced defect in genetic repair. The results of our growth studies and analysis of the complete D. radiodurans genomic sequence support the hypothesis that there are several defects in D. radiodurans global metabolic regulation that limit carbon, nitrogen, and DNA metabolism. We identified key nutritional constituents that restore growth of D. radiodurans in nutritionally limiting radioactive environments.
Novel ionizing radiation-sensitive mutants of Deinococcus radiodurans
Journal of Bacteriology, 1994
Two new loci, irrB and irrI, have been identified in Deinococcus radiodurans. Inactivation of either locus results in a partial loss of resistance to ionizing radiation. The magnitude of this loss is locus specific and differentially affected by inactivation of the uvrA gene product. An irrB uvrA double mutant is more sensitive to ionizing radiation than is an irrB mutant. In contrast, the irrI uvrA double mutant and the irrI mutant are equally sensitive to ionizing radiation. The irrB and irrI mutations also reduce D. radiodurans resistance to UV radiation, this effect being most pronounced in uvrA+ backgrounds. Subclones of each gene have been isolated, and the loci have been mapped relative to each other. The irrB and irrI genes are separated by approximately 20 kb of intervening sequence that encodes the uvrA and pol genes.