scholarly journals Defects in the Error Prevention Oxidized Guanine System Potentiate Stationary-Phase Mutagenesis in Bacillus subtilis

2008 ◽  
Vol 191 (2) ◽  
pp. 506-513 ◽  
Author(s):  
Luz E. Vidales ◽  
Lluvia C. Cárdenas ◽  
Eduardo Robleto ◽  
Ronald E. Yasbin ◽  
Mario Pedraza-Reyes
Keyword(s):  
Oxidative Stress ◽  
Bacillus Subtilis ◽  
Stationary Phase ◽  
Repair System ◽  
Induced Mutations ◽  
General Role ◽  
Error Prevention ◽  
Repair Mechanisms ◽  
Induced Mutagenesis ◽  
Oxidized Guanine

ABSTRACT Previous studies showed that a Bacillus subtilis strain deficient in mismatch repair (MMR; encoded by the mutSL operon) promoted the production of stationary-phase-induced mutations. However, overexpression of the mutSL operon did not completely suppress this process, suggesting that additional DNA repair mechanisms are involved in the generation of stationary-phase-associated mutants in this bacterium. In agreement with this hypothesis, the results presented in this work revealed that starved B. subtilis cells lacking a functional error prevention GO (8-oxo-G) system (composed of YtkD, MutM, and YfhQ) had a dramatic propensity to increase the number of stationary-phase-induced revertants. These results strongly suggest that the occurrence of mutations is exacerbated by reactive oxygen species in nondividing cells of B. subtilis having an inactive GO system. Interestingly, overexpression of the MMR system significantly diminished the accumulation of mutations in cells deficient in the GO repair system during stationary phase. These results suggest that the MMR system plays a general role in correcting base mispairing induced by oxidative stress during stationary phase. Thus, the absence or depression of both the MMR and GO systems contributes to the production of stationary-phase mutants in B. subtilis. In conclusion, our results support the idea that oxidative stress is a mechanism that generates genetic diversity in starved cells of B. subtilis, promoting stationary-phase-induced mutagenesis in this soil microorganism.

scholarly journals Role of Bacillus subtilis Error Prevention Oxidized Guanine System in Counteracting Hexavalent Chromium-Promoted Oxidative DNA Damage

2014 ◽  
Vol 80 (17) ◽  
pp. 5493-5502 ◽  
Author(s):  
Fernando Santos-Escobar ◽  
J. Félix Gutiérrez-Corona ◽  
Mario Pedraza-Reyes
Keyword(s):  
Dna Damage ◽  
Bacillus Subtilis ◽  
Hexavalent Chromium ◽  
Oxidative Dna Damage ◽  
Chromosomal Dna ◽  
Error Prevention ◽  
Content Type ◽  
Induced Mutagenesis ◽  
Oxidized Guanine ◽  
Life On Earth

ABSTRACTChromium pollution is potentially detrimental to bacterial soil communities, compromising carbon and nitrogen cycles that are essential for life on earth. It has been proposed that intracellular reduction of hexavalent chromium [Cr(VI)] to trivalent chromium [Cr(III)] may cause bacterial death by a mechanism that involves reactive oxygen species (ROS)-induced DNA damage; the molecular basis of the phenomenon was investigated in this work. Here, we report thatBacillus subtiliscells lacking a functional error prevention oxidized guanine (GO) system were significantly more sensitive to Cr(VI) treatment than cells of the wild-type (WT) strain, suggesting that oxidative damage to DNA is involved in the deleterious effects of the oxyanion. In agreement with this suggestion, Cr(VI) dramatically increased the ROS concentration and induced mutagenesis in a GO-deficientB. subtilisstrain. Alkaline gel electrophoresis (AGE) analysis of chromosomal DNA of WT and ΔGO mutant strains subjected to Cr(VI) treatment revealed that the DNA of the ΔGO strain was more susceptible to DNA glycosylase Fpg attack, suggesting that chromium genotoxicity is associated with 7,8-dihydro-8-oxodeoxyguanosine (8-oxo-G) lesions. In support of this notion, specific monoclonal antibodies detected the accumulation of 8-oxo-G lesions in the chromosomes ofB. subtiliscells subjected to Cr(VI) treatment. We conclude that Cr(VI) promotes mutagenesis and cell death inB. subtilisby a mechanism that involves radical oxygen attack of DNA, generating 8-oxo-G, and that such effects are counteracted by the prevention and repair GO system.

scholarly journals Contribution of the Mismatch DNA Repair System to the Generation of Stationary-Phase-Induced Mutants of Bacillus subtilis

2004 ◽  
Vol 186 (19) ◽  
pp. 6485-6491 ◽  
Author(s):  
Mario Pedraza-Reyes ◽  
Ronald E. Yasbin
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Bacillus Subtilis ◽  
Stationary Phase ◽  
Assay System ◽  
Repair System ◽  
Induced Mutants ◽  
Induced Mutagenesis ◽  
Mmr Deficiency

ABSTRACT A reversion assay system previously implemented to demonstrate the existence of adaptive or stationary-phase-induced mutagenesis in Bacillus subtilis was utilized in this report to study the influence of the mismatch DNA repair (MMR) system on this type of mutagenesis. Results revealed that a strain deficient in MutSL showed a significant propensity to generate increased numbers of stationary-phase-induced revertants. These results suggest that absence or depression of MMR is an important factor in the mutagenesis of nongrowing B. subtilis cells because of the role of MMR in repairing DNA damage. In agreement with this suggestion, a significant decrease in the number of adaptive revertant colonies, for the three markers tested, occurred in B. subtilis cells which overexpressed a component of the MMR system. Interestingly, the single overexpression of mutS, but not of mutL, was sufficient to decrease the level of adaptive mutants in the reversion assay system of B. subtilis. The results presented in this work, as well as in our previous studies, appear to suggest that an MMR deficiency, putatively attributable to inactivation or saturation with DNA damage of MutS, may occur in a subset of B. subtilis cells that differentiate into the hypermutable state.

scholarly journals The Bacillus Subtilis K-State Promotes Stationary-Phase Mutagenesis via Oxidative Damage

Genes ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 190
Author(s):  
Holly A. Martin ◽  
Amanda A. Kidman ◽  
Jillian Socea ◽  
Carmen Vallin ◽  
Mario Pedraza-Reyes ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Oxidative Damage ◽  
Stationary Phase ◽  
Bacterial Cells ◽  
Dna Uptake ◽  
Cellular Division ◽  
Exogenous Dna ◽  
K Cells ◽  
Induced Mutagenesis ◽  
Underlying Mechanisms

Bacterial cells develop mutations in the absence of cellular division through a process known as stationary-phase or stress-induced mutagenesis. This phenomenon has been studied in a few bacterial models, including Escherichia coli and Bacillus subtilis; however, the underlying mechanisms between these systems differ. For instance, RecA is not required for stationary-phase mutagenesis in B. subtilis like it is in E. coli. In B. subtilis, RecA is essential to the process of genetic transformation in the subpopulation of cells that become naturally competent in conditions of stress. Interestingly, the transcriptional regulator ComK, which controls the development of competence, does influence the accumulation of mutations in stationary phase in B. subtilis. Since recombination is not involved in this process even though ComK is, we investigated if the development of a subpopulation (K-cells) could be involved in stationary-phase mutagenesis. Using genetic knockout strains and a point-mutation reversion system, we investigated the effects of ComK, ComEA (a protein involved in DNA transport during transformation), and oxidative damage on stationary-phase mutagenesis. We found that stationary-phase revertants were more likely to have undergone the development of competence than the background of non-revertant cells, mutations accumulated independently of DNA uptake, and the presence of exogenous oxidants potentiated mutagenesis in K-cells. Therefore, the development of the K-state creates conditions favorable to an increase in the genetic diversity of the population not only through exogenous DNA uptake but also through stationary-phase mutagenesis.

scholarly journals Spontaneous and photosensitization-induced mutations in primary mouse cells transitioning through senescence and immortalization

2020 ◽  
Vol 295 (29) ◽  
pp. 9974-9985
Author(s):  
Andrew W. Caliri ◽  
Stella Tommasi ◽  
Steven E. Bates ◽  
Ahmad Besaratinia
Keyword(s):  
Oxidative Stress ◽  
Cancer Biology ◽  
Induced Mutations ◽  
Dna Mismatch ◽  
Replication Errors ◽  
Primary Mouse ◽  
Immortalized Cells ◽  
Oxidized Guanine ◽  
Mutation Type

To investigate the role of oxidative stress–induced DNA damage and mutagenesis in cellular senescence and immortalization, here we profiled spontaneous and methylene blue plus light–induced mutations in the cII gene from λ phage in transgenic mouse embryonic fibroblasts during the transition from primary culture through senescence and immortalization. Consistent with detection of characteristic oxidized guanine lesions (8-oxodG) in the treated cells, we observed significantly increased relative cII mutant frequency in the treated pre-senescent cells which was augmented in their immortalized counterparts. The predominant mutation type in the treated pre-senescent cells was G:C→T:A transversion, whose frequency was intensified in the treated immortalized cells. Conversely, the prevailing mutation type in the treated immortalized cells was A:T→C:G transversion, with a unique sequence-context specificity, i.e. flanking purines at the 5′ end of the mutated nucleotide. This mutation type was also enriched in the treated pre-senescent cells, although to a lower extent. The signature mutation of G:C→T:A transversions in the treated cells accorded with the well-established translesion synthesis bypass caused by 8-oxodG, and the hallmark A:T→C:G transversions conformed to the known replication errors because of oxidized guanine nucleosides (8-OHdGTPs). The distinctive features of photosensitization-induced mutagenesis in the immortalized cells, which were present at attenuated levels, in spontaneously immortalized cells provide insights into the role of oxidative stress in senescence bypass and immortalization. Our results have important implications for cancer biology because oxidized purines in the nucleoside pool can significantly contribute to genetic instability in DNA mismatch repair–defective human tumors.

scholarly journals Role of Mfd and GreA in Bacillus subtilis Base Excision Repair-Dependent Stationary-Phase Mutagenesis

2020 ◽  
Vol 202 (9) ◽  
Author(s):  
Hilda C. Leyva-Sánchez ◽  
Norberto Villegas-Negrete ◽  
Karen Abundiz-Yañez ◽  
Ronald E. Yasbin ◽  
Eduardo A. Robleto ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Stationary Phase ◽  
Excision Repair ◽  
Dna Lesions ◽  
Ap Endonuclease ◽  
Content Type ◽  
Error Prone Repair ◽  
Base Excision ◽  
Oxidized Guanine

ABSTRACT We report that the absence of an oxidized guanine (GO) system or the apurinic/apyrimidinic (AP) endonucleases Nfo, ExoA, and Nth promoted stress-associated mutagenesis (SAM) in Bacillus subtilis YB955 (hisC952 metB5 leuC427). Moreover, MutY-promoted SAM was Mfd dependent, suggesting that transcriptional transactions over nonbulky DNA lesions promoted error-prone repair. Here, we inquired whether Mfd and GreA, which control transcription-coupled repair and transcription fidelity, influence the mutagenic events occurring in nutritionally stressed B. subtilis YB955 cells deficient in the GO or AP endonuclease repair proteins. To this end, mfd and greA were disabled in genetic backgrounds defective in the GO and AP endonuclease repair proteins, and the strains were tested for growth-associated and stress-associated mutagenesis. The results revealed that disruption of mfd or greA abrogated the production of stress-associated amino acid revertants in the GO and nfo exoA nth strains, respectively. These results suggest that in nutritionally stressed B. subtilis cells, spontaneous nonbulky DNA lesions are processed in an error-prone manner with the participation of Mfd and GreA. In support of this notion, stationary-phase ΔytkD ΔmutM ΔmutY (referred to here as ΔGO) and Δnfo ΔexoA Δnth (referred to here as ΔAP) cells accumulated 8-oxoguanine (8-OxoG) lesions, which increased significantly following Mfd disruption. In contrast, during exponential growth, disruption of mfd or greA increased the production of His+, Met+, or Leu+ prototrophs in both DNA repair-deficient strains. Thus, in addition to unveiling a role for GreA in mutagenesis, our results suggest that Mfd and GreA promote or prevent mutagenic events driven by spontaneous genetic lesions during the life cycle of B. subtilis. IMPORTANCE In this paper, we report that spontaneous genetic lesions of an oxidative nature in growing and nutritionally stressed B. subtilis strain YB955 (hisC952 metB5 leuC427) cells drive Mfd- and GreA-dependent repair transactions. However, whereas Mfd and GreA elicit faithful repair events during growth to maintain genome fidelity, under starving conditions, both factors promote error-prone repair to produce genetic diversity, allowing B. subtilis to escape from growth-limiting conditions.

scholarly journals Oxidative Damage to Nucleic Acids and Benzo(a)pyrene-7,8-diol-9,10-epoxide-DNA Adducts and Chromosomal Aberration in Children with Psoriasis Repeatedly Exposed to Crude Coal Tar Ointment and UV Radiation

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Lenka Borska ◽  
Ctirad Andrys ◽  
Jan Krejsek ◽  
Vladimir Palicka ◽  
Marcela Chmelarova ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Uv Radiation ◽  
Dna Adducts ◽  
Coal Tar ◽  
Metabolic Enzyme ◽  
Repair System ◽  
Rna Repair ◽  
Pasi Score ◽  
Markers Of Oxidative Stress ◽  
Oxidized Guanine

The paper presents a prospective cohort study. Observed group was formed of children with plaque psoriasis (n=19) treated by Goeckerman therapy (GT). The study describes adverse (side) effects associated with application of GT (combined exposure of 3% crude coal tar ointment and UV radiation). After GT we found significantly increased markers of oxidative stress (8-hydroxy-2′-deoxyguanosine, 8-hydroxyguanosine, and 8-hydroxyguanine), significantly increased levels of benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE) DNA adducts (BPDE-DNA), and significantly increased levels of total number of chromosomal aberrations in peripheral lymphocytes. We found significant relationship between (1) time of UV exposure and total number of aberrated cells and (2) daily topical application of 3% crude coal tar ointment (% of body surface) and level of BPDE-DNA adducts. The findings indicated increased hazard of oxidative stress and genotoxic effects related to the treatment. However, it must be noted that the oxidized guanine species and BPDE-DNA adducts also reflect individual variations in metabolic enzyme activity (different extent of bioactivation of benzo[a]pyrene to BPDE) and overall efficiency of DNA/RNA repair system. The study confirmed good effectiveness of the GT (significantly decreased PASI score).

scholarly journals DNA SEQUENCE ANALYSIS OF MUTAGENICITY AND SITE SPECIFICITY OF ETHYL METHANESULFONATE IN Uvr+ AND UvrB- STRAINS OF ESCHERICHIA COLI

Genetics ◽  
1986 ◽  
Vol 113 (4) ◽  
pp. 811-819
Author(s):  
Philip A Burns ◽  
Frances L Allen ◽  
Barry W Glickman
Keyword(s):  
Dna Sequence ◽  
Excision Repair ◽  
Base Sequence ◽  
Site Specificity ◽  
Repair System ◽  
Induced Mutations ◽  
Base Pairs ◽  
E Coli ◽  
Laci Gene ◽  
Induced Mutagenesis

ABSTRACT EMS-induced mutations within a 180 base pair region of the lacI gene of E. coli were cloned and sequenced. In total, 105 and 79 EMS-induced mutations from a Uvr+ and a UvrB- strain, respectively, were sequenced. The specificity of EMS-induced mutagenesis was very similar in the two strians; G:C → A:T transitions accounted for all but three of the mutants. The overall frequency of induced mutation was fivefold higher in the UvrB- strain compared to the Uvr+ strain. This demonstrates, at the DNA sequence level, that the presumed pre-mutagenic lesion, O  6-ethylguanine, is subject to repair by the uvrABC excision repair system of E. coli. An analysis of mutation frequencies with respect to neighboring base sequence, in the two strains, shows that O  6-ethylguanine lesions adjacent to A:T base pairs present better targets for the excision repair machinery than those not adjacent to A:T base pairs.

scholarly journals Cellular Response against Oxidative Stress, a Novel Insight into Lupus Nephritis Pathogenesis

2021 ◽  
Vol 11 (8) ◽  
pp. 693
Author(s):  
Corina Daniela Ene ◽  
Simona Roxana Georgescu ◽  
Mircea Tampa ◽  
Clara Matei ◽  
Cristina Iulia Mitran ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Lupus Nephritis ◽  
Cellular Response ◽  
Molecular Mechanisms ◽  
Control Group ◽  
Dna Repair Mechanisms ◽  
Glycation End Products ◽  
Repair Mechanisms ◽  
Low Levels ◽  
Defective Dna Repair

The interaction of reactive oxygen species (ROS) with lipids, proteins, nucleic acids and hydrocarbonates promotes acute and chronic tissue damage, mediates immunomodulation and triggers autoimmunity in systemic lupus erythematous (SLE) patients. The aim of the study was to determine the pathophysiological mechanisms of the oxidative stress-related damage and molecular mechanisms to counteract oxidative stimuli in lupus nephritis. Our study included 38 SLE patients with lupus nephritis (LN group), 44 SLE patients without renal impairment (non-LN group) and 40 healthy volunteers as control group. In the present paper, we evaluated serum lipid peroxidation, DNA oxidation, oxidized proteins, carbohydrate oxidation, and endogenous protective systems. We detected defective DNA repair mechanisms via 8-oxoguanine-DNA-glycosylase (OGG1), the reduced regulatory effect of soluble receptor for advanced glycation end products (sRAGE) in the activation of AGE-RAGE axis, low levels of thiols, disulphide bonds formation and high nitrotyrosination in lupus nephritis. All these data help us to identify more molecular mechanisms to counteract oxidative stress in LN that could permit a more precise assessment of disease prognosis, as well as developing new therapeutic targets.

scholarly journals Cellular repair mechanisms triggered by exposure to silver nanoparticles and ionic silver in embryonic zebrafish cells

2021 ◽  
Author(s):  
Ana C. Quevedo ◽  
Iseult Lynch ◽  
Eugenia Valsami-Jones
Keyword(s):  
Oxidative Stress ◽  
Silver Nanoparticles ◽  
Cell Death ◽  
Zebrafish Embryo ◽  
Genetic Damage ◽  
Cellular Repair ◽  
Embryo Cells ◽  
Repair Mechanisms ◽  
Toxicity Pathways ◽  
Dynamic Interplay

The dynamic interplay between toxicity pathways (oxidative stress, calcium disturbances, genetic damage) caused by nanoparticles and the repair mechanisms of inhibition of cell division and induction of cell death is explored in zebrafish embryo cells.

scholarly journals Non-B DNA-Forming Motifs Promote Mfd-Dependent Stationary-Phase Mutagenesis in Bacillus subtilis

2021 ◽  
Vol 9 (6) ◽  
pp. 1284
Author(s):  
Tatiana Ermi ◽  
Carmen Vallin ◽  
Ana Gabriela Regalado García ◽  
Moises Bravo ◽  
Ismaray Fernandez Cordero ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Stationary Phase ◽  
Genome Instability ◽  
Mutagenic Effect ◽  
Genetic Changes ◽  
Dna Structures ◽  
Coding Regions ◽  
G4 Dna ◽  
Stressed Cells ◽  
Growing Conditions

Transcription-induced mutagenic mechanisms limit genetic changes to times when expression happens and to coding DNA. It has been hypothesized that intrinsic sequences that have the potential to form alternate DNA structures, such as non-B DNA structures, influence these mechanisms. Non-B DNA structures are promoted by transcription and induce genome instability in eukaryotic cells, but their impact in bacterial genomes is less known. Here, we investigated if G4 DNA- and hairpin-forming motifs influence stationary-phase mutagenesis in Bacillus subtilis. We developed a system to measure the influence of non-B DNA on B. subtilis stationary-phase mutagenesis by deleting the wild-type argF at its chromosomal position and introducing IPTG-inducible argF alleles differing in their ability to form hairpin and G4 DNA structures into an ectopic locus. Using this system, we found that sequences predicted to form non-B DNA structures promoted mutagenesis in B. subtilis stationary-phase cells; such a response did not occur in growing conditions. We also found that the transcription-coupled repair factor Mfd promoted mutagenesis at these predicted structures. In summary, we showed that non-B DNA-forming motifs promote genetic instability, particularly in coding regions in stressed cells; therefore, non-B DNA structures may have a spatial and temporal mutagenic effect in bacteria. This study provides insights into mechanisms that prevent or promote mutagenesis and advances our understanding of processes underlying bacterial evolution.

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