scholarly journals RecA and RadA Proteins of Brucella abortus Do Not Perform Overlapping Protective DNA Repair Functions following Oxidative Burst

2006 ◽  
Vol 188 (14) ◽  
pp. 5187-5195 ◽  
Author(s):  
Christelle M. Roux ◽  
Natha J. Booth ◽  
Bryan H. Bellaire ◽  
Jason M. Gee ◽  
R. Martin Roop ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Brucella Abortus ◽  
Oxidative Burst ◽  
Bacterial Species ◽  
Reca Protein ◽  
Repair Process ◽  
Sensitivity Analyses ◽  
E Coli ◽  
Functional Analyses

ABSTRACT Very little is known about the role of DNA repair networks in Brucella abortus and its role in pathogenesis. We investigated the roles of RecA protein, DNA repair, and SOS regulation in B. abortus. While recA mutants in most bacterial species are hypersensitive to UV damage, surprisingly a B. abortus recA null mutant conferred only modest sensitivity. We considered the presence of a second RecA protein to account for this modest UV sensitivity. Analyses of the Brucella spp. genomes and our molecular studies documented the presence of only one recA gene, suggesting a RecA-independent repair process. Searches of the available Brucella genomes revealed some homology between RecA and RadA, a protein implicated in E. coli DNA repair. We considered the possibility that B. abortus RadA might be compensating for the loss of RecA by promoting similar repair activities. We present functional analyses that demonstrated that B. abortus RadA complements a radA defect in E. coli but could not act in place of the B. abortus RecA. We show that RecA but not RadA was required for survival in macrophages. We also discovered that recA was expressed at high constitutive levels, due to constitutive LexA cleavage by RecA, with little induction following DNA damage. Higher basal levels of RecA and its SOS-regulated gene products might protect against DNA damage experienced following the oxidative burst within macrophages.

Ordered Intracellular Reca-Dna Assemblies

2000 ◽  
Vol 6 (S2) ◽  
pp. 860-861
Author(s):  
S. G. Wolf ◽  
S. Levin-Zaidman ◽  
D. Frenkiel-Krispin ◽  
E. Shimoni ◽  
I. Sabanay ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Electron Micrographs ◽  
Reca Protein ◽  
Sos Response ◽  
Structural Features ◽  
Wild Type ◽  
E Coli ◽  
Dna Damaging Agents

The inducible SOS response increases the ability of bacteria to cope with DNA damage through various DNA repair processes in which the RecA protein plays a central role. We find that induction of the SOS system in wild-type E. coli bacteria results in fast and massive intracellular coaggregation of RecA and DNA into lateral assemblies, which comprise substantial portions of both the cellular RecA and the DNA complement. The structural features of the coaggregates and their relation to in-vitro RecA-DNA are consistent with the possibility that the intracellular assemblies represent a functional entity in which RecA-mediated DNA repair and protection activities occur.Bacterial chromatin is demarcated in electron micrographs of metabolically active cells as amorphous ribosome-free spaces that are irregularly spread over the cytoplasm (Fig. A). Wild-type E. coli cells exposed to DNA-damaging agents that induce the SOS response reveal a strikingly different morphology (Fig. B).

scholarly journals The emerging role of RNAs in DNA damage repair

2017 ◽  
Vol 24 (4) ◽  
pp. 580-587 ◽  
Author(s):  
Ben R Hawley ◽  
Wei-Ting Lu ◽  
Ania Wilczynska ◽  
Martin Bushell
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Critical Role ◽  
Repair Process ◽  
Rna Molecules ◽  
Processing Enzymes ◽  
Damage Repair ◽  
New Findings ◽  
Integral Role ◽  
Repair Mechanisms

Abstract Many surveillance and repair mechanisms exist to maintain the integrity of our genome. All of the pathways described to date are controlled exclusively by proteins, which through their enzymatic activities identify breaks, propagate the damage signal, recruit further protein factors and ultimately resolve the break with little to no loss of genetic information. RNA is known to have an integral role in many cellular pathways, but, until very recently, was not considered to take part in the DNA repair process. Several reports demonstrated a conserved critical role for RNA-processing enzymes and RNA molecules in DNA repair, but the biogenesis of these damage-related RNAs and their mechanisms of action remain unknown. We will explore how these new findings challenge the idea of proteins being the sole participants in the response to DNA damage and reveal a new and exciting aspect of both DNA repair and RNA biology.

Involvement of the cgtA gene function in stimulation of DNA repair in Escherichia coli and Vibrio harveyi

Microbiology ◽  
2003 ◽  
Vol 149 (7) ◽  
pp. 1763-1770 ◽  
Author(s):  
Ryszard Zielke ◽  
Aleksandra Sikora ◽  
Rafał Dutkiewicz ◽  
Grzegorz Wegrzyn ◽  
Agata Czyż
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Dna Repair ◽  
Gene Product ◽  
Uv Irradiation ◽  
Vibrio Harveyi ◽  
Bacterial Species ◽  
Wild Type ◽  
E Coli ◽  
Stimulation Of

CgtA is a member of the Obg/Gtp1 subfamily of small GTP-binding proteins. CgtA homologues have been found in various prokaryotic and eukaryotic organisms, ranging from bacteria to humans. Nevertheless, despite the fact that cgtA is an essential gene in most bacterial species, its function in the regulation of cellular processes is largely unknown. Here it has been demonstrated that in two bacterial species, Escherichia coli and Vibrio harveyi, the cgtA gene product enhances survival of cells after UV irradiation. Expression of the cgtA gene was found to be enhanced after UV irradiation of both E. coli and V. harveyi. Moderate overexpression of cgtA resulted in higher UV resistance of E. coli wild-type and dnaQ strains, but not in uvrA, uvrB, umuC and recA mutant hosts. Overexpression of the E. coli recA gene in the V. harveyi cgtA mutant, which is very sensitive to UV light, restored the level of survival of UV-irradiated cells to the levels observed for wild-type bacteria. Moreover, the basal level of the RecA protein was lower in a temperature-sensitive cgtA mutant of E. coli than in the cgtA + strain, and contrary to wild-type bacteria, no significant increase in recA gene expression was observed after UV irradiation of this cgtA mutant. Finally, stimulation of uvrB gene transcription under these conditions was impaired in the V. harveyi cgtA mutant. All these results strongly suggest that the cgtA gene product is involved in DNA repair processes, most probably by stimulation of recA gene expression and resultant activation of RecA-dependent DNA repair pathways.

scholarly journals A Review on DNA Repair Inhibition by PARP Inhibitors in Cancer Therapy

Folia Medica ◽  
2018 ◽  
Vol 60 (1) ◽  
pp. 39-47 ◽  
Author(s):  
Ashish P. Shah ◽  
Chhagan N. Patel ◽  
Dipen K. Sureja ◽  
Kirtan P. Sanghavi
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Cancer Therapy ◽  
Repair Process ◽  
Parp Inhibitors ◽  
Brca Mutations ◽  
Development Of Resistance ◽  
Damage Repair ◽  
Future Therapy

AbstractThe DNA repair process protects the cells from DNA damaging agent by multiple pathways. Majority of the cancer therapy cause DNA damage which leads to apoptosis. The cell has natural ability to repair this damage which ultimately leads to development of resistance of drugs. The key enzymes involved in DNA repair process are poly(ADP-ribose) (PAR) and poly(ADP-ribose) polymerases (PARP). Tumor cells repair their defective gene via defective homologues recombination (HR) in the presence of enzyme PARP. PARP inhibitors inhibit the enzyme poly(ADP-ribose) polymerases (PARPs) which lead to apoptosis of cancer cells. Current clinical data shows the role of PARP inhibitors is not restricted to BRCA mutations but also effective in HR dysfunctions related tumors. Therefore, investigation in this area could be very helpful for future therapy of cancer. This review gives detail information on the role of PARP in DNA damage repair, the role of PARP inhibitors and chemistry of currently available PARP inhibitors.

scholarly journals Clustered DNA Damage: Electronic Properties and Their Influence on Charge Transfer. 7,8-Dihydro-8-Oxo-2′-Deoxyguaosine Versus 5′,8-Cyclo-2′-Deoxyadenosines: A Theoretical Approach

Cells ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 424 ◽  
Author(s):  
Boleslaw T. Karwowski
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Charge Transfer ◽  
Human Cancer ◽  
Double Helix ◽  
Proximal Part ◽  
Repair Process ◽  
Dna Lesions ◽  
Human Cancer Cells ◽  
Order Of Magnitude

Approximately 3 × 1017 DNA damage events take place per hour in the human body. Within clustered DNA lesions, they pose a serious problem for repair proteins, especially for iron–sulfur glycosylases (MutyH), which can recognize them by the electron-transfer process. It has been found that the presence of both 5′,8-cyclo-2′-deoxyadenosine (cdA) diastereomers in the ds-DNA structure, as part of a clustered lesion, can influence vertical radical cation distribution within the proximal part of the double helix, i.e., d[~oxoGcAoxoG~] (7,8-dihydro-8-oxo-2′-deoxyguaosine - oxodG). Here, the influence of cdA, “the simplest tandem lesion”, on the charge transfer through ds-DNA was taken into theoretical consideration at the M062x/6-31+G** level of theory in the aqueous phase. It was shown that the presence of (5′S)- or (5′R)-cdA leads to a slowdown in the hole transfer by one order of magnitude between the neighboring dG→oxodG in comparison to “native” ds-DNA. Therefore, it can be concluded that such clustered lesions can lead to defective damage recognition with a subsequent slowing down of the DNA repair process, giving rise to an increase in mutations. As a result, the unrepaired, oxodG: dA base pair prior to genetic information replication can finally result in GC → TA or AT→CG transversion. This type of mutation is commonly observed in human cancer cells. Moreover, because local multiple damage sites (LMSD) are effectively produced as a result of ionization factors, the presented data in this article might be useful in developing a new scheme of radiotherapy treatment against the background of DNA repair efficiency.

scholarly journals A CRISPR-based assay for the study of eukaryotic DNA repair onboard the International Space Station

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0253403
Author(s):  
Sarah Stahl-Rommel ◽  
David Li ◽  
Michelle Sung ◽  
Rebecca Li ◽  
Aarthi Vijayakumar ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
International Space Station ◽  
Space Station ◽  
Repair Process ◽  
Double Strand Breaks ◽  
Repair Pathway ◽  
Strand Breaks ◽  
International Space ◽  
Break Site

As we explore beyond Earth, astronauts may be at risk for harmful DNA damage caused by ionizing radiation. Double-strand breaks are a type of DNA damage that can be repaired by two major cellular pathways: non-homologous end joining, during which insertions or deletions may be added at the break site, and homologous recombination, in which the DNA sequence often remains unchanged. Previous work suggests that space conditions may impact the choice of DNA repair pathway, potentially compounding the risks of increased radiation exposure during space travel. However, our understanding of this problem has been limited by technical and safety concerns, which have prevented integral study of the DNA repair process in space. The CRISPR/Cas9 gene editing system offers a model for the safe and targeted generation of double-strand breaks in eukaryotes. Here we describe a CRISPR-based assay for DNA break induction and assessment of double-strand break repair pathway choice entirely in space. As necessary steps in this process, we describe the first successful genetic transformation and CRISPR/Cas9 genome editing in space. These milestones represent a significant expansion of the molecular biology toolkit onboard the International Space Station.

scholarly journals Genetic Interactions of DNA Repair Pathways in the Pathogen Neisseria meningitidis

2007 ◽  
Vol 189 (15) ◽  
pp. 5728-5737 ◽  
Author(s):  
Tonje Davidsen ◽  
Hanne K. Tuven ◽  
Magnar Bjørås ◽  
Einar A. Rødland ◽  
Tone Tønjum
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Neisseria Meningitidis ◽  
Excision Repair ◽  
Spontaneous Mutation ◽  
Recombinational Repair ◽  
Major Pathway ◽  
Current Increase ◽  
E Coli ◽  
Repair Pathways

ABSTRACT The current increase in the incidence and severity of infectious diseases mandates improved understanding of the basic biology and DNA repair profiles of virulent microbes. In our studies of the major pathogen and model organism Neisseria meningitidis, we constructed a panel of mutants inactivating genes involved in base excision repair, mismatch repair, nucleotide excision repair (NER), translesion synthesis, and recombinational repair pathways. The highest spontaneous mutation frequency among the N. meningitidis single mutants was found in the MutY-deficient strain as opposed to mutS mutants in Escherichia coli, indicating a role for meningococcal MutY in antibiotic resistance development. Recombinational repair was recognized as a major pathway counteracting methyl methanesulfonate-induced alkylation damage in the N. meningitidis. In contrast to what has been shown in other species, meningococcal NER did not contribute significantly to repair of alkylation-induced DNA damage, and meningococcal recombinational repair may thus be one of the main pathways for removal of abasic (apurinic/apyrimidinic) sites and strand breaks in DNA. Conversely, NER was identified as the main meningococcal defense pathway against UV-induced DNA damage. N. meningitidis RecA single mutants exhibited only a moderate decrease in survival after UV exposure as opposed to E. coli recA strains, which are extremely UV sensitive, possibly reflecting the lack of a meningococcal SOS response. In conclusion, distinct differences between N. meningitidis and established DNA repair characteristics in E. coli and other species were identified.

scholarly journals RecA and RecB: probing complexes of DNA repair proteins with mitomycin C in live Escherichia coli with single-molecule sensitivity

2021 ◽  
Author(s):  
Alex L. Payne-Dwyer ◽  
Aisha H. Syeda ◽  
Jack W. Shepherd ◽  
Lewis Frame ◽  
Mark. C. Leake
Keyword(s):  
Escherichia Coli ◽  
Dna Damage ◽  
Dna Repair ◽  
Mitomycin C ◽  
Single Molecule ◽  
Reca Protein ◽  
Live Cells ◽  
Dna Breaks ◽  
Fluorescent Reporters ◽  
Double Stranded Dna

AbstractThe RecA protein and RecBCD complex are key bacterial components for the maintenance and repair of DNA, RecBCD a helicase-nuclease that uses homologous recombination to resolve double-stranded DNA breaks and also facilitating decoration of single-stranded DNA with RecA to form RecA filaments, a vital step in the double-stranded break DNA repair pathway. However, questions remain about the mechanistic roles of RecA and RecBCD in live cells. Here, we use millisecond super-resolved fluorescence microscopy to pinpoint the spatial localization of fluorescent reporters of RecA and the RecB at physiological levels of expression in individual live Escherichia coli cells. By introducing the DNA crosslinker mitomycin C, we induce DNA damage and quantify the resulting changes in stoichiometry, copy number and molecular mobilities of RecA and RecB. We find that both proteins accumulate in molecular hotspots to effect repair, resulting in RecA filamental stoichiometries equivalent to several hundred molecules that act largely in RecA tetramers before DNA damage, but switch to approximately hexameric subunits when mature filaments are formed. Unexpectedly, we find that the physiologically predominant form of RecB is a dimer.

scholarly journals The RASSF1A Tumor Suppressor Regulates XPA-Mediated DNA Repair

2014 ◽  
Vol 35 (1) ◽  
pp. 277-287 ◽  
Author(s):  
Howard Donninger ◽  
Jennifer Clark ◽  
Francesca Rinaldo ◽  
Nicholas Nelson ◽  
Thibaut Barnoud ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Tumor Suppressor ◽  
Human Cancer ◽  
Protein A ◽  
Repair Process ◽  
Protein Acetylation ◽  
Repair Protein ◽  
Dna Repair Protein ◽  
Repair Activity

RASSF1A may be the most frequently inactivated tumor suppressor identified in human cancer so far. It is a proapoptotic Ras effector and plays an important role in the apoptotic DNA damage response (DDR). We now show that in addition to DDR regulation, RASSF1A also plays a key role in the DNA repair process itself. We show that RASSF1A forms a DNA damage-regulated complex with the key DNA repair protein xeroderma pigmentosum A (XPA). XPA requires RASSF1A to exert full repair activity, and RASSF1A-deficient cells exhibit an impaired ability to repair DNA. Moreover, a cancer-associated RASSF1A single-nucleotide polymorphism (SNP) variant exhibits differential XPA binding and inhibits DNA repair. The interaction of XPA with other components of the repair complex, such as replication protein A (RPA), is controlled in part by a dynamic acetylation/deacetylation cycle. We found that RASSF1A and its SNP variant differentially regulate XPA protein acetylation, and the SNP variant hyperstabilizes the XPA-RPA70 complex. Thus, we identify two novel functions for RASSF1A in the control of DNA repair and protein acetylation. As RASSF1A modulates both apoptotic DDR and DNA repair, it may play an important and unanticipated role in coordinating the balance between repair and death after DNA damage.

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