Down-regulation of radioresistance by LexA2 in Deinococcus radiodurans

Satoh, Katsuya; Ohba, Hirofumi; Sghaier, Haïtham; Narumi, Issay

doi:10.1099/mic.0.29139-0

Cited by 38 publications

(31 citation statements)

References 47 publications

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“…LexA1 (DRA0344) undergoes RecA-mediated cleavage but does not repress the expression of RecA, as the level of RecA in unirradiated cells is the same in wild-type and lexA mutant cells (64,458,537). Furthermore, the deletion of lexA does not affect the repair of DSBs (277).…”

Section: Recombinational Processes In D Radiodurans Dna Repairmentioning

confidence: 99%

Oxidative Stress Resistance inDeinococcus radiodurans

Slade

Radman

2011

Microbiol Mol Biol Rev

622

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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Section: Recombinational Processes In D Radiodurans Dna Repairmentioning

confidence: 99%

Oxidative Stress Resistance inDeinococcus radiodurans

Slade

Radman

2011

Microbiol Mol Biol Rev

622

639

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“…16 It has also been shown that two other deinococcal regulatory proteins, LexA2 and RecX, suppress the expression of PprA. 17,18 Thus, PprA is a DNA repair protein that is induced in response to radiation stress in D. radiodurans.…”

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confidence: 99%

Interaction of double‐stranded DNA with polymerized PprA protein from Deinococcus radiodurans

et al. 2014

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Pleiotropic protein promoting DNA repair A (PprA) is a key protein that facilitates the extreme radioresistance of Deinococcus radiodurans. To clarify the role of PprA in the radioresistance mechanism, the interaction between recombinant PprA expressed in Escherichia coli with several double-stranded DNAs (i.e., super coiled, linear, or nicked circular dsDNA) was investigated. In a gel-shift assay, the band shift of supercoiled pUC19 DNA caused by the binding of PprA showed a bimodal distribution, which was promoted by the addition of 1 mM Mg, Ca, or Sr ions. The dissociation constant of the PprA-supercoiled pUC19 DNA complex, calculated from the relative portions of shifted bands, was 0.6 lM with Hill coefficient of 3.3 in the presence of 1 mM Mg acetate. This indicates that at least 281 PprA molecules are required to saturate a supercoiled pUC19 DNA, which is consistent with the number (280) of bound PprA molecules estimated by the UV absorption of the PprA-pUC19 complex purified by gel filtration. This saturation also suggests linear polymerization of PprA along the dsDNA. On the other hand, the bands of linear dsDNA and nicked circular dsDNA that eventually formed PprA complexes did not saturate, but created larger molecular complexes when the PprA concentration was >1.3 lM. This result implies that DNAbound PprA aids association of the termini of damaged DNAs, which is regulated by the concentration of PprA. These findings are important for the understanding of the mechanism underlying effective DNA repair involving PprA.

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“…The absence of a lexA mutation effect on the expression of recA and absence of umuDC in D. radiodurans suggested the absence of the SOS response in this bacterium (Narumi et al, 2001;Bonacossa de Almeida et al, 2002;Sheng et al, 2004). However, the role of LexA2 in radioresistance by over expression of pprA indicated the possibility of LexA2 functioning through a different mechanism in D. radiodurans (Satoh et al, 2006). Since D. radiodurans contains PolX, a homologue of Polb, along with other components of a BER system, the role of this enzyme in radiation and oxidative stress-induced DNAdamage repair merited investigation.…”

Section: Introductionmentioning

confidence: 99%

DNA polymerase X from Deinococcus radiodurans implicated in bacterial tolerance to DNA damage is characterized as a short patch base excision repair polymerase

Khairnar

Misra

2009

Microbiology

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The Deinococcus radiodurans R1 genome encodes an X-family DNA repair polymerase homologous to eukaryotic DNA polymerase b. The recombinant deinococcal polymerase X (PolX) purified from transgenic Escherichia coli showed deoxynucleotidyltransferase activity. Unlike the Klenow fragment of E. coli, this enzyme showed short patch DNA synthesis activity on heteropolymeric DNA substrate. The recombinant enzyme showed 59-deoxyribose phosphate (59-dRP) lyase activity and base excision repair function in vitro, with the help of externally supplied glycosylase and AP endonuclease functions. A polX disruption mutant of D. radiodurans expressing 59-dRP lyase and a truncated polymerase domain was comparatively less sensitive to c-radiation than a polX deletion mutant. Both mutants showed higher sensitivity to hydrogen peroxide. Excision repair mutants of E. coli expressing this polymerase showed functional complementation of UV sensitivity. These results suggest the involvement of deinococcal polymerase X in DNA-damage tolerance of D. radiodurans, possibly by contributing to DNA double-strand break repair and base excision repair.

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Down-regulation of radioresistance by LexA2 in Deinococcus radiodurans

Cited by 38 publications

References 47 publications

Oxidative Stress Resistance inDeinococcus radiodurans

Oxidative Stress Resistance inDeinococcus radiodurans

Interaction of double‐stranded DNA with polymerized PprA protein from Deinococcus radiodurans

DNA polymerase X from Deinococcus radiodurans implicated in bacterial tolerance to DNA damage is characterized as a short patch base excision repair polymerase

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