scholarly journals A bacterial DNA repair pathway specific to a natural antibiotic

2018 ◽  
Author(s):  
Peter E. Burby ◽  
Lyle A. Simmons
Keyword(s):  
Dna Repair ◽  
Bacillus Subtilis ◽  
Mitomycin C ◽  
Related Species ◽  
Excision Repair ◽  
Bacterial Species ◽  
Genetic Material ◽  
Repair Pathway ◽  
Closely Related Species ◽  
Repair Pathways

SummaryAll organisms possess several DNA repair pathways to maintain the integrity of their genetic material. Although there are several DNA repair pathways that are well understood, we recently identified several genes in Bacillus subtilis that are important for surviving treatment with drugs that damage DNA. Here, we report a drug specific DNA repair pathway in B. subtilis. We identified genes coding for a previously uncharacterized helicase and exonuclease, mrfA and mrfB, respectively. Deletion of mrfA and mrfB resulted in sensitivity to the DNA damaging agent mitomycin C, but not other types of DNA damage. We found that MrfAB operate independently of canonical nucleotide excision repair, forming a novel excision repair pathway in bacteria. A phylogenetic analysis demonstrates that MrfAB homologs are present in diverse bacterial phyla, and a cross-complementation assay shows that MrfAB function is conserved in closely related species. Mitomycin C is a natural antibiotic that is produced by the soil dwelling bacterium Streptomyces lavendulae, and B. subtilis is also a soil dwelling organism. The specificity of the ΔmrfAB phenotype suggests that MrfAB have been adapted as a countermeasure to mitomycin producing bacteria.Abbreviated SummaryBacteria possess DNA repair pathways to maintain the integrity of their genetic material. The helicase MrfA and the exonuclease MrfB are part of a mitomycin C specific DNA repair pathway in Bacillus subtilis. Despite being present in many bacterial species, MrfAB activity in repairing MMC damaged DNA appears to be restricted to closely related species, suggesting that these proteins have likely been adapted to the specific needs of each bacterium.

scholarly journals DNA repair and the evolution of transformation in Bacillus subtilis. II. Role of inducible repair.

Genetics ◽  
1989 ◽  
Vol 121 (3) ◽  
pp. 411-422
Author(s):  
M F Wojciechowski ◽  
M A Hoelzer ◽  
R E Michod
Keyword(s):  
Dna Repair ◽  
Bacillus Subtilis ◽  
Plasmid Dna ◽  
Excision Repair ◽  
Physiological State ◽  
Transformation Rate ◽  
Exogenous Dna ◽  
Expression Of Genes ◽  
Cell Subpopulations ◽  
Experimental Treatments

Abstract In Bacillus subtilis, DNA repair and recombination are intimately associated with competence, the physiological state in which the bacterium can bind, take up and recombine exogenous DNA. Previously, we have shown that the homologous DNA transformation rate (ratio of transformants to total cells) increases with increasing UV dosage if cells are transformed after exposure to UV radiation (UV-DNA), whereas the transformation rate decreases if cells are transformed before exposure to UV (DNA-UV). In this report, by using different DNA repair-deficient mutants, we show that the greater increase in transformation rate in UV-DNA experiments than in DNA-UV experiments does not depend upon excision repair or inducible SOS-like repair, although certain quantitative aspects of the response do depend upon these repair systems. We also show that there is no increase in the transformation rate in a UV-DNA experiment when repair and recombination proficient cells are transformed with nonhomologous plasmid DNA, although the results in a DNA-UV experiment are essentially unchanged by using plasmid DNA. We have used din operon fusions as a sensitive means of assaying for the expression of genes under the control of the SOS-like regulon in both competent and noncompetent cell subpopulations as a consequence of competence development and our subsequent experimental treatments. Results indicate that the SOS-like system is induced in both competent and noncompetent subpopulations in our treatments and so should not be a major factor in the differential response in transformation rate observed in UV-DNA and DNA-UV treatments. These results provide further support to the hypothesis that the evolutionary function of competence is to bring DNA into the cell for use as template in the repair of DNA damage.

scholarly journals Molecular Mechanisms of the Whole DNA Repair System: A Comparison of Bacterial and Eukaryotic Systems

2010 ◽  
Vol 2010 ◽  
pp. 1-32 ◽  
Author(s):  
Rihito Morita ◽  
Shuhei Nakane ◽  
Atsuhiro Shimada ◽  
Masao Inoue ◽  
Hitoshi Iino ◽  
...  
Keyword(s):  
Dna Repair ◽  
Molecular Mechanisms ◽  
Excision Repair ◽  
Thermus Thermophilus ◽  
Repair System ◽  
System A ◽  
Recombination Repair ◽  
Repair Mechanisms ◽  
Repair Pathways ◽  
Base Excision

DNA is subjected to many endogenous and exogenous damages. All organisms have developed a complex network of DNA repair mechanisms. A variety of different DNA repair pathways have been reported: direct reversal, base excision repair, nucleotide excision repair, mismatch repair, and recombination repair pathways. Recent studies of the fundamental mechanisms for DNA repair processes have revealed a complexity beyond that initially expected, with inter- and intrapathway complementation as well as functional interactions between proteins involved in repair pathways. In this paper we give a broad overview of the whole DNA repair system and focus on the molecular basis of the repair machineries, particularly inThermus thermophilusHB8.

scholarly journals Systematic analysis of mutational spectra associated with DNA repair deficiency in C. elegans

2020 ◽  
Author(s):  
B Meier ◽  
NV Volkova ◽  
Y Hong ◽  
S Bertolini ◽  
V González-Huici ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Excision Repair ◽  
Structural Variants ◽  
Systematic Analysis ◽  
C Elegans ◽  
Mutational Spectra ◽  
Base Substitutions ◽  
Repair Pathways ◽  
Complex Structural

AbstractGenome integrity is particularly important in germ cells to faithfully preserve genetic information across generations. As yet little is known about the contribution of various DNA repair pathways to prevent mutagenesis. Using the C. elegans model we analyse mutational spectra that arise in wild-type and 61 DNA repair and DNA damage response mutants cultivated over multiple generations. Overall, 44% of lines show >2-fold increased mutagenesis with a broad spectrum of mutational outcomes including changes in single or multiple types of base substitutions induced by defects in base excision or nucleotide excision repair, or elevated levels of 50-400 bp deletions in translesion polymerase mutants rev-3(pol ζ) and polh-1(pol η). Mutational signatures associated with defective homologous recombination fall into two classes: 1) mutants lacking brc-1/BRCA1 or rad-51/RAD51 paralogs show elevated base substitutions, indels and structural variants, while 2) deficiency for MUS-81/MUS81 and SLX-1/SLX1 nucleases, and HIM-6/BLM, HELQ-1/HELQ and RTEL-1/RTEL1 helicases primarily cause structural variants. Genome-wide investigation of mutagenesis patterns identified elevated rates of tandem duplications often associated with inverted repeats in helq-1 mutants, and a unique pattern of ‘translocation’ events involving homeologous sequences in rip-1 paralog mutants. atm-1/ATM DNA damage checkpoint mutants harboured complex structural variants enriched in subtelomeric regions, and chromosome end-to-end fusions. Finally, while inactivation of the p53-like gene cep-1 did not affect mutagenesis, combined brc-1 cep-1 deficiency displayed increased, locally clustered mutagenesis. In summary, we provide a global view of how DNA repair pathways prevent germ cell mutagenesis.

scholarly journals Mutational signatures are jointly shaped by DNA damage and repair

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Nadezda V. Volkova ◽  
Bettina Meier ◽  
Víctor González-Huici ◽  
Simone Bertolini ◽  
Santiago Gonzalez ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Excision Repair ◽  
Point Mutations ◽  
Mutational Signatures ◽  
Dna Damage And Repair ◽  
C Elegans ◽  
Dna Repair Deficiency ◽  
Dna Alterations ◽  
Repair Pathways

AbstractCells possess an armamentarium of DNA repair pathways to counter DNA damage and prevent mutation. Here we use C. elegans whole genome sequencing to systematically quantify the contributions of these factors to mutational signatures. We analyse 2,717 genomes from wild-type and 53 DNA repair defective backgrounds, exposed to 11 genotoxins, including UV-B and ionizing radiation, alkylating compounds, aristolochic acid, aflatoxin B1, and cisplatin. Combined genotoxic exposure and DNA repair deficiency alters mutation rates or signatures in 41% of experiments, revealing how different DNA alterations induced by the same genotoxin are mended by separate repair pathways. Error-prone translesion synthesis causes the majority of genotoxin-induced base substitutions, but averts larger deletions. Nucleotide excision repair prevents up to 99% of point mutations, almost uniformly across the mutation spectrum. Our data show that mutational signatures are joint products of DNA damage and repair and suggest that multiple factors underlie signatures observed in cancer genomes.

scholarly journals PARP Inhibitors as a Therapeutic Agent for Homologous Recombination Deficiency in Breast Cancers

2019 ◽  
Vol 8 (4) ◽  
pp. 435 ◽  
Author(s):  
Man Keung ◽  
Yanyuan Wu ◽  
Jaydutt Vadgama
Keyword(s):  
Dna Repair ◽  
Homologous Recombination ◽  
Cancer Cells ◽  
Anticancer Agents ◽  
Excision Repair ◽  
Parp Inhibitor ◽  
Predictive Biomarkers ◽  
Parp Inhibitors ◽  
Homologous Recombination Deficiency ◽  
Repair Pathways

Poly (ADP-ribose) polymerases (PARPs) play an important role in various cellular processes, such as replication, recombination, chromatin remodeling, and DNA repair. Emphasizing PARP’s role in facilitating DNA repair, the PARP pathway has been a target for cancer researchers in developing compounds which selectively target cancer cells and increase sensitivity of cancer cells to other anticancer agents, but which also leave normal cells unaffected. Since certain tumors (BRCA1/2 mutants) have deficient homologous recombination repair pathways, they depend on PARP-mediated base excision repair for survival. Thus, inhibition of PARP is a promising strategy to selectively kill cancer cells by inactivating complementary DNA repair pathways. Although PARP inhibitor therapy has predominantly targeted BRCA-mutated cancers, this review also highlights the growing conversation around PARP inhibitor treatment for non-BRCA-mutant tumors, those which exhibit BRCAness and homologous recombination deficiency. We provide an update on the field’s progress by considering PARP inhibitor mechanisms, predictive biomarkers, and clinical trials of PARP inhibitors in development. Bringing light to these findings would provide a basis for expanding the use of PARP inhibitors beyond BRCA-mutant breast tumors.

scholarly journals Tautomerization-dependent recognition and excision of oxidation damage in base-excision DNA repair

2016 ◽  
Vol 113 (28) ◽  
pp. 7792-7797 ◽  
Author(s):  
Chenxu Zhu ◽  
Lining Lu ◽  
Jun Zhang ◽  
Zongwei Yue ◽  
Jinghui Song ◽  
...  
Keyword(s):  
Dna Repair ◽  
Excision Repair ◽  
Mammalian Genome ◽  
Dna Bases ◽  
Repair Pathway ◽  
Thymine Glycol ◽  
Base Excision ◽  
Oxidation Damage ◽  
Biochemical Analyses ◽  
Base Excision Dna Repair

NEIL1 (Nei-like 1) is a DNA repair glycosylase guarding the mammalian genome against oxidized DNA bases. As the first enzymes in the base-excision repair pathway, glycosylases must recognize the cognate substrates and catalyze their excision. Here we present crystal structures of human NEIL1 bound to a range of duplex DNA. Together with computational and biochemical analyses, our results suggest that NEIL1 promotes tautomerization of thymine glycol (Tg)—a preferred substrate—for optimal binding in its active site. Moreover, this tautomerization event also facilitates NEIL1-catalyzed Tg excision. To our knowledge, the present example represents the first documented case of enzyme-promoted tautomerization for efficient substrate recognition and catalysis in an enzyme-catalyzed reaction.

Nucleotide Excision Repair in the Three Domains of Life

2011 ◽  
Vol 2 (1) ◽  
Author(s):  
David A Farnell
Keyword(s):  
Dna Repair ◽  
Nucleotide Excision Repair ◽  
Xeroderma Pigmentosum ◽  
Excision Repair ◽  
Human Diseases ◽  
Repair Pathway ◽  
Functional Conservation ◽  
Wide Range ◽  
Nucleotide Excision ◽  
Domains Of Life

Nucleotide excision repair (NER) is a vital DNA repair pathway which acts on a wide range of helix-distorting lesions. The importance of this pathway is highlighted by its functional conservation throughout evolution and by several human diseases, such as xeroderma pigmentosum, which are caused by a defective NER pathway. This review summarizes the NER mechanisms present in all three domains of life: eukaryotes, bacteria, and archaea.

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