An exonuclease I‐sensitive DNA repair pathway in <i>Deinococcus radiodurans</i>: a major determinant of radiation resistance

Misra, Hari S.; Khairnar, Nivedita P.; Kota, Swathi; Shrivastava, Smriti; Joshi, Vasudha; Apte, Shree Kumar

doi:10.1111/j.1365-2958.2005.05005.x

Cited by 83 publications

(73 citation statements)

References 38 publications

(55 reference statements)

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“…This pathway is inhibited by the SbcB nuclease (reference 24 and references therein), and D. radiodurans is naturally devoid of the SbcB protein. Moreover, it was shown that expression in trans of the SbcB protein from E. coli renders D. radiodurans cells radiation sensitive (35). Thus, a RecF-like pathway may operate in D. radiodurans to generate 3Ј overhangs of single-stranded DNA.…”

Section: Discussionmentioning

confidence: 99%

Additive Effects of SbcCD and PolX Deficiencies in the In Vivo Repair of DNA Double-Strand Breaks inDeinococcus radiodurans

et al. 2007

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Orthologs of proteins SbcD (Mre11) and SbcC (Rad50) exist in all kingdoms of life and are involved in a wide variety of DNA repair and maintenance functions, including homologous recombination and nonhomologous end joining. Here, we have inactivated the sbcC and/or sbcD genes of Deinococcus radiodurans, a highly radioresistant bacterium able to mend hundreds of radiation-induced DNA double-strand breaks (DSB). Mutants devoid of the SbcC and/or SbcD proteins displayed reduced survival and presented a delay in kinetics of DSB repair and cell division following ␥-irradiation. It has been recently reported that D. radiodurans DNA polymerase X (PolX) possesses a structure-modulated 3-to-5 exonuclease activity reminiscent of specific nuclease activities displayed by the SbcCD complex from Escherichia coli. We constructed a double mutant devoid of SbcCD and PolX proteins. The double-mutant ⌬sbcCD ⌬polX Dr (where Dr indicates D. radiodurans) bacteria are much more sensitive to ␥-irradiation than the single mutants, suggesting that the deinococcal SbcCD and PolX proteins may play important complementary roles in processing damaged DNA ends. We propose that they are part of a backup repair system acting to rescue cells containing DNA lesions that are excessively numerous or difficult to repair.

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Section: Discussionmentioning

confidence: 99%

Additive Effects of SbcCD and PolX Deficiencies in the In Vivo Repair of DNA Double-Strand Breaks inDeinococcus radiodurans

et al. 2007

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“…6, step 2). The 5Ј-to-3Ј polarity of end recession in D. radiodurans was indirectly demonstrated by expression in trans of the SbcB 3Ј-5Ј exonuclease from E. coli, which rendered D. radiodurans radiation sensitive and inhibited DNA double-strand-break repair (418). Among possible candidates for 5Ј-3Ј exonuclease activity in D. radiodurans are RecJ and the 5Ј-3Ј exonuclease activity of Pol I.…”

Section: Dna Degradation In Irradiated D Radioduransmentioning

confidence: 99%

“…D. radiodurans does not encode RecB and RecC homologs, or SbcB (a 3Ј-5Ј ssDNA nuclease), and the levels of nuclease activity in deinococcal cell extracts are consequently much lower than that in E. coli extracts (288). The overexpression of E. coli RecBC (288) and SbcB (418) in D. radiodurans sensitizes the cells to ionizing radiation and delays or inhibits DSB repair in gamma-irradiated cells, respectively. RecBC-expressing D. radiodurans cells suffer from an extensive degradation of DNA ends, while the inhibition of DSB repair in SbcB-expressing cells suggests that 3Ј ssDNA ends are indispensable for the recombinational repair of DSBs (418).…”

Section: Recombinational Processes In D Radiodurans Dna Repairmentioning

confidence: 99%

“…The overexpression of E. coli RecBC (288) and SbcB (418) in D. radiodurans sensitizes the cells to ionizing radiation and delays or inhibits DSB repair in gamma-irradiated cells, respectively. RecBC-expressing D. radiodurans cells suffer from an extensive degradation of DNA ends, while the inhibition of DSB repair in SbcB-expressing cells suggests that 3Ј ssDNA ends are indispensable for the recombinational repair of DSBs (418). Moreover, the ATP-sensitive 3Ј-5Ј exonuclease activity of a dual-function esterase/nuclease, DR0505, is attenuated during the initial stages of postirradiation recovery by higher ATP levels (282,318).…”

Section: Recombinational Processes In D Radiodurans Dna Repairmentioning

confidence: 99%

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Oxidative Stress Resistance inDeinococcus radiodurans

Slade

Radman

2011

Microbiol Mol Biol Rev

645

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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“…The TGY agar plates containing D. radiodurans R1 and its derivatives were incubated at 32°C for 48 h before the colonies were counted. The shuttle expression vector pRADgro and derivatives of this vector were maintained in E. coli strain HB101 as described previously (34). Other recombinant techniques used have been described previously (37).…”

Section: Methodsmentioning

confidence: 99%

Involvement of a Protein Kinase Activity Inducer in DNA Double Strand Break Repair and Radioresistance of Deinococcus radiodurans

2008

Self Cite

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Transgenic bacteria producing pyrroloquinoline quinone, a known cofactor for dehydrogenases and an inducer of a periplasmic protein kinase activity, show resistance to both oxidative stress and protection from nonoxidative effects of radiation and DNA-damaging agents. Deinococcus radiodurans R1 encodes an active pyrroloquinoline quinone synthase, and constitutive synthesis of pyrroloquinoline quinone occurred in wildtype bacteria. Disruption of a genomic copy of pqqE resulted in cells that lacked this cofactor. The mutant showed a nearly 3-log decrease in ␥ radiation resistance and a 2-log decrease in mitomycin C tolerance compared to wild-type cells. The mutant cells did not show sensitivity to UVC radiation. Expression of pyrroloquinoline quinone synthase in trans showed that there was functional complementation of ␥ resistance and mitomycin C tolerance in the pqqE mutant. The sensitivity to ␥ radiation was due to impairment or slow kinetics of DNA double strand break repair. Low levels of 32 P incorporation were observed in total soluble proteins of mutant cells compared to the wild type. The results suggest that pyrroloquinoline quinone has a regulatory role as a cofactor for dehydrogenases and an inducer of selected protein kinase activity in radiation resistance and DNA strand break repair in a radioresistant bacterium.Pyrroloquinoline quinone (PQQ) has been shown to be a redox cofactor for periplasmic as well as cytosolic dehydrogenases, contributing to the mineral phosphate solubilization phenotype in bacteria (11). This compound has been reported to act as an antioxidant in vitro (33), in animal systems (13), and in bacterial systems (18) in vivo and as a member of the B group vitamins (16). He and coworkers (13) have shown that the antioxidant nature of PQQ is concentration dependent. Higher concentrations of PQQ induce oxidative stress for mitochondrial activity in rats, which leads to both apoptotic and necrotic cell death. Further studies indicated that the necrotic cell death could be selectively inhibited in the presence of antioxidants, while apoptotic cell death continued by a stillunknown mechanism. Further, a possible role for PQQ as an inducer for proteins kinases involved in distinctly different metabolic and physiological processes has been suggested (20).Deinococcus radiodurans R1, a gram-positive bacterium, exhibits extraordinary tolerance to various abiotic stresses, including radiation, desiccation, and other DNA-damaging factors (3). DNA double strand break repair in D. radiodurans R1 follows biphasic kinetics (8). Phase I is RecA independent and involves an extended synthesis-dependent strand annealing mechanism for reassembly of the fragmented genome (42), while phase II involves RecA-dependent slow crossover events (9). The extreme phenotypes of this bacterium are believed to be due to the presence of an efficient DNA strand break repair mechanism (1, 31) and strong oxidative stress tolerance (27). A comparison of the genome sequence of D. radiodurans R1 (41) with the genome sequenc...

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An exonuclease I‐sensitive DNA repair pathway in Deinococcus radiodurans: a major determinant of radiation resistance

Cited by 83 publications

References 38 publications

Additive Effects of SbcCD and PolX Deficiencies in the In Vivo Repair of DNA Double-Strand Breaks inDeinococcus radiodurans

Additive Effects of SbcCD and PolX Deficiencies in the In Vivo Repair of DNA Double-Strand Breaks inDeinococcus radiodurans

Oxidative Stress Resistance inDeinococcus radiodurans

Involvement of a Protein Kinase Activity Inducer in DNA Double Strand Break Repair and Radioresistance of Deinococcus radiodurans

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