Singlet oxygen-mediated damage to cellular DNA determined by the comet assay associated with DNA repair enzymes

2004 ◽  
Vol 385 (1) ◽  
pp. 17-20 ◽  
Author(s):  
J.-L. Ravanat ◽  
S. Sauvaigo ◽  
S. Caillat ◽  
G. R. Martinez ◽  
M. H. G. Medeiros ◽  
...  
Keyword(s):  
Dna Repair ◽  
Comet Assay ◽  
Singlet Oxygen ◽  
Mammalian Cells ◽  
Singlet Molecular Oxygen ◽  
Dna Repair Enzymes ◽  
Strand Breaks ◽  
Endonuclease Iii ◽  
Repair Enzymes ◽  
Cellular Dna

Abstract The damage profile produced by the reaction of singlet molecular oxygen with cellular DNA was determined using the comet assay associated with DNA repair enzymes. Singlet oxygen was produced intracellularly by thermal decomposition of a watersoluble endoperoxide of a naphthalene derivative which is able to penetrate through the membrane into mammalian cells. We found that the DNA modifications produced by singlet oxygen were almost exclusively oxidised purines recognised by the formamidopyrimidine DNA N-glycosylase. In contrast, significant amounts of direct strand breaks and alkalilabile sites or oxidised pyrimidines, detectable by the bacterial endonuclease III, were not produced.

DNA Repair Enzymes in Mammalian Cells

1977 ◽  
pp. 263-322 ◽  
Author(s):  
Errol C. Friedberg ◽  
Kern H. Cook ◽  
James Duncan ◽  
Kristien Mortelmans
Keyword(s):  
Dna Repair ◽  
Mammalian Cells ◽  
Dna Repair Enzymes ◽  
Repair Enzymes

scholarly journals A new member of the endonuclease III family of DNA repair enzymes that removes methylated purines from DNA

1999 ◽  
Vol 9 (12) ◽  
pp. 653-656 ◽  
Author(s):  
Thomas J. Begley ◽  
Brian J. Haas ◽  
Jerry Noel ◽  
Alexander Shekhtman ◽  
William A. Williams ◽  
...  
Keyword(s):  
Dna Repair ◽  
Dna Repair Enzymes ◽  
Endonuclease Iii ◽  
Repair Enzymes

scholarly journals HIV-1 Vpr Reprograms CLR4DCAF1E3 Ubiquitin Ligase to Antagonize Exonuclease 1-Mediated Restriction of HIV-1 Infection

mBio ◽  
2018 ◽  
Vol 9 (5) ◽  
Author(s):  
Junpeng Yan ◽  
Ming-Chieh Shun ◽  
Caili Hao ◽  
Yi Zhang ◽  
Juan Qian ◽  
...  
Keyword(s):  
T Cells ◽  
Dna Repair ◽  
Accessory Protein ◽  
Dna Repair Enzymes ◽  
New Class ◽  
Repair Enzymes ◽  
Immunodeficiency Virus ◽  
Exonuclease 1 ◽  
Cellular Dna ◽  
Hiv 1

ABSTRACTViral accessory proteins hijack host cell E3 ubiquitin ligases to antagonize innate/intrinsic defenses and thereby provide a more permissive environment for virus replication. Human immunodeficiency virus type 1 (HIV-1) accessory protein Vpr reprograms CRL4DCAF1E3 to antagonize select postreplication DNA repair enzymes, but the significance and role of these Vpr interactions are poorly understood. To gain additional insights, we performed a focused screen for substrates of CRL4DCAF1E3 reprogrammed by HIV-1 Vpr among known postreplication DNA repair proteins and identified exonuclease 1 (Exo1) as a novel direct HIV-1 Vpr target. We show that HIV-1 Vpr recruits Exo1 to the CRL4DCAF1E3 complex for ubiquitination and subsequent proteasome-dependent degradation and that Exo1 levels are depleted in HIV-1-infected cells in a Vpr-dependent manner. We also show that Exo1 inhibits HIV-1 replication in T cells. Notably, the antagonism of Exo1 is a conserved function of main group HIV-1 and its ancestor Vpr proteins in the simian immunodeficiency virus from chimpanzee (SIVcpz) lineage, further underscoring the relevance of our findings. Overall, our studies (i) reveal that HIV-1 Vpr extensively remodels the cellular postreplication DNA repair machinery by impinging on multiple repair pathways, (ii) support a model in which Vpr promotes HIV-1 replication by antagonizing select DNA repair enzymes, and (iii) highlight the importance of a new class of restrictions placed on HIV-1 replication in T cells by the cellular DNA repair machinery.IMPORTANCEHIV-1 polymerase reverse transcribes the viral RNA genome into imperfectly double-stranded proviral DNA, containing gaps and flaps, for integration into the host cell chromosome. HIV-1 reverse transcripts share characteristics with cellular DNA replication intermediates and are thought to be converted into fully double-stranded DNA by cellular postreplication DNA repair enzymes. Therefore, the finding that the HIV-1 accessory protein Vpr antagonizes select postreplication DNA repair enzymes that can process HIV-1 reverse transcripts has been surprising. Here, we show that one such Vpr-antagonized enzyme, exonuclease 1, inhibits HIV-1 replication in T cells. We identify exonuclease 1 as a member of a new class of HIV-1 restriction factors in T cells and propose that certain modes of DNA “repair” inhibit HIV-1 infection.

scholarly journals CRISPR-Cas immunity, DNA repair and genome stability

2018 ◽  
Vol 38 (5) ◽  
Author(s):  
Andrew Cubbon ◽  
Ivana Ivancic-Bace ◽  
Edward L. Bolt
Keyword(s):  
Dna Repair ◽  
Genome Editing ◽  
Genome Stability ◽  
Short Review ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Dna Repair Enzymes ◽  
Strand Breaks ◽  
Repair Enzymes ◽  
Maintain Genome Stability

Co-opting of CRISPR-Cas ‘Interference’ reactions for editing the genomes of eukaryotic and prokaryotic cells has highlighted crucial support roles for DNA repair systems that strive to maintain genome stability. As front-runners in genome editing that targets DNA, the class 2 CRISPR-Cas enzymes Cas9 and Cas12a rely on repair of DNA double-strand breaks (DDSBs) by host DNA repair enzymes, using mechanisms that vary in how well they are understood. Data are emerging about the identities of DNA repair enzymes that support genome editing in human cells. At the same time, it is becoming apparent that CRISPR-Cas systems functioning in their native environment, bacteria or archaea, also need DNA repair enzymes. In this short review, we survey how DNA repair and CRISPR-Cas systems are intertwined. We consider how understanding DNA repair and CRISPR-Cas interference reactions in nature might help improve the efficacy of genome editing procedures that utilise homologous or analogous systems in human and other cells.

scholarly journals DASH-type cryptochromes – solved and open questions

2020 ◽  
Vol 401 (12) ◽  
pp. 1487-1493
Author(s):  
Stephan Kiontke ◽  
Tanja Göbel ◽  
Annika Brych ◽  
Alfred Batschauer
Keyword(s):  
Dna Repair ◽  
Circadian Clock ◽  
Blue Light ◽  
Dna Repair Enzymes ◽  
Repair Enzymes ◽  
Open Questions ◽  
Essential Components ◽  
Repair Activity ◽  
Almost All ◽  
Uv Lesions

AbstractDrosophila, Arabidopsis, Synechocystis, human (DASH)-type cryptochromes (cry-DASHs) form one subclade of the cryptochrome/photolyase family (CPF). CPF members are flavoproteins that act as DNA-repair enzymes (DNA-photolyases), or as ultraviolet(UV)-A/blue light photoreceptors (cryptochromes). In mammals, cryptochromes are essential components of the circadian clock feed-back loop. Cry-DASHs are present in almost all major taxa and were initially considered as photoreceptors. Later studies demonstrated DNA-repair activity that was, however, restricted to UV-lesions in single-stranded DNA. Very recent studies, particularly on microbial organisms, substantiated photoreceptor functions of cry-DASHs suggesting that they could be transitions between photolyases and cryptochromes.

scholarly journals DNA damage shifts circadian clock time via Hausp-dependent Cry1 stabilization

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Stephanie J Papp ◽  
Anne-Laure Huber ◽  
Sabine D Jordan ◽  
Anna Kriebs ◽  
Madelena Nguyen ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Circadian Clock ◽  
Transcriptional Response ◽  
Genotoxic Stress ◽  
Genomic Integrity ◽  
Clock Time ◽  
Dna Repair Enzymes ◽  
Repair Enzymes ◽  
Specific Protease

The circadian transcriptional repressors cryptochrome 1 (Cry1) and 2 (Cry2) evolved from photolyases, bacterial light-activated DNA repair enzymes. In this study, we report that while they have lost DNA repair activity, Cry1/2 adapted to protect genomic integrity by responding to DNA damage through posttranslational modification and coordinating the downstream transcriptional response. We demonstrate that genotoxic stress stimulates Cry1 phosphorylation and its deubiquitination by Herpes virus associated ubiquitin-specific protease (Hausp, a.k.a Usp7), stabilizing Cry1 and shifting circadian clock time. DNA damage also increases Cry2 interaction with Fbxl3, destabilizing Cry2. Thus, genotoxic stress increases the Cry1/Cry2 ratio, suggesting distinct functions for Cry1 and Cry2 following DNA damage. Indeed, the transcriptional response to genotoxic stress is enhanced in Cry1−/− and blunted in Cry2−/− cells. Furthermore, Cry2−/− cells accumulate damaged DNA. These results suggest that Cry1 and Cry2, which evolved from DNA repair enzymes, protect genomic integrity via coordinated transcriptional regulation.

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