• Title, Summary, Keyword: DNA repair enzymes

Search Result 23, Processing Time 0.047 seconds

Collaborative Effect of CuZnSOD and Human AP Endonuclease against Oxidative Stress

  • Kim Young Gon
    • Proceedings of the Microbiological Society of Korea Conference
    • /
    • /
    • pp.47-50
    • /
    • 2004
  • The defenses against free radical damage include specialized repair enzymes that correct oxidative damages in DNA, and detoxification systems such as superoxide dismutases. These defenses may be coordinated genetically as global responses. We hypothesized that the expression of the SOD and the DNA repair genes would inhibit DNA damage under oxidative stress. Therefore, the protection of E. coli mutants deficient in SOD and DNA repair genes $(sod^-\;xth^-\;and\;nfo^-)$ was demonstrated by transforming the mutant strain with a plasmid pYK9 which encoded Photobacterium leiognathi CuZnSOD and human AP endonuclease. The results show that survival rates were increased in $sod^+\;xth^-\;nfo^+$ cells compared to $sod^-\;xth^-\;ap^+,\;sod^-\;xth^-\;ap^-,\;and\;sod^+\;xth^-\;ap^-$ cells under oxidative stress generated from 0.1 mM Paraquat or 3 mM $H_2O_2$. The data suggested that, at least, SOD and DNA repair enzymes may have collaborate protection and repair of the damaged DNA. Additionally, both enzymes are required for protection against free radicals.

  • PDF

Computer-based screening for novel inhibitors of human topoisomerase I with FlexiDock docking protocol

  • Choi, In-Hee;Kim, Choon-Mi
    • Proceedings of the PSK Conference
    • /
    • /
    • pp.315.1-315
    • /
    • 2002
  • DNA topoisomerases I (topo I) and II are essential enzymes that relax DNA supercoiling and relieve torsional strain during DNA processing. including replication. transcription. and repair. Topo I relaxes DNA by cleaving one strand of DNA by attacking a backbone phosphale with a catalytic lyrosine (Tyr723. human topo I). This enzyme has recently been investigated as a new target for antineoplastic drugs. Inhibitors to the enzyme intercalate between the DNA base pairs. interfering religation of cleaved DNA, therefore inhibit the activity of topo I. (omitted)

  • PDF

Effects of 3-Aminobenzamide on DNA Strand Breaks and Excision Repair in CHO cells Exposed to Methyl Methanesulfonate and Ultraviolet-light (MMS와 자외선을 처리한 CHO세포에 있어서 DNA사 절단과 절제회복에 미치는 3-aminobenzamide의 영향)

  • Park, Sang-Dai;Jang, Young-Ju;Roh, Jung-Koo
    • The Korean Journal of Zoology
    • /
    • v.26 no.3
    • /
    • pp.171-179
    • /
    • 1983
  • Amounts of DNA single strand breaks and unscheduled DNA synthesis in CHO cells exposed to MMS were increased in the presence of 3-aminobenzamide, a potent inhibitor of poly (ADP-ribose) polymerase. However, those in cells irradiated with UV-light were decreased. These results suggest that poly (ADP-ribose) polymerase acts negatively on the MMS-induced base excision repair but positively on the UV-induced nucleotide excision repair. In the combined treatment with MMS and UV-light in the presence of this inhibitor, amounts of strand breaks were just the same as those in the absence of the inhibitor. But those of unscheduled DNA synthesis were increased up to the amount induced by UV-light alone. These results may suggest that poly (ADP-ribose) polymerase affects the incision step of excision repair induced by MMS and UV-light independently, and that it may potentiate the complete cleaving of UV-induced pyrimidine dimers possibly by the repair enzymes which might have been partially inactivated by MMS.

  • PDF

The Expression of DNA Polymerase-$\beta$ and DNA Damage in Jurkat Cells Exposed to Hydrogen Peroxide under Hyperbaric Pressure

  • Sul, Dong-Geun;Oh, Sang-Nam;Lee, Eun-Il
    • Molecular & Cellular Toxicology
    • /
    • v.4 no.1
    • /
    • pp.66-71
    • /
    • 2008
  • Long term exposure of Jurkat cells to 2 ATA pressure resulted in the inhibition of cell growth. Under a 2 ATA pressure, the morphological changes in the cells were visualized by electron microscopy. The cells exhibited significant inhibitory responses after three passages. However, short-term exposure study was carried out, 2 ATA pressure may have beneficial effects. The Jurkat cells were exposed to $H_2O_2$ (25 and $50{\mu}M$) in order to induce DNA damage, and then incubated under at either normal pressure or 2 ATA for 1 or 2 hours in order to recover the DNA damage. The extent of DNA damage was determined via Comet assay. More recovery from DNA damage was observed at 2 ATA than at normal pressure. The activity of the DNA repair enzymes, DNA polymerase-$\beta$, was also evaluated at both normal pressure and 2 ATA. The activity of DNA polymerase-$\beta$ was observed to have increased significantly at the 2 ATA than at normal pressure. In conclusion, the effects of hyperbaric pressure from 1 ATA to 2 ATA on biochemical systems can be either beneficial or harmful. Long term exposure to hyperbaric pressure clearly inhibited cell proliferation and caused genotoxic effects, but short-term exposure to hyperbaric pressure proved to be beneficial in terms of bolstering the DNA repair system. The results of the present study have clinical therapeutic application, and might prove to be an useful tool in the study of genotoxicity in the future.

Enzymatic DNA oxidation: mechanisms and biological significance

  • Xu, Guo-Liang;Walsh, Colum P.
    • BMB Reports
    • /
    • v.47 no.11
    • /
    • pp.609-618
    • /
    • 2014
  • DNA methylation at cytosines (5mC) is a major epigenetic modification involved in the regulation of multiple biological processes in mammals. How methylation is reversed was until recently poorly understood. The family of dioxygenases commonly known as Ten-eleven translocation (Tet) proteins are responsible for the oxidation of 5mC into three new forms, 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC). Current models link Tet-mediated 5mC oxidation with active DNA demethylation. The higher oxidation products (5fC and 5caC) are recognized and excised by the DNA glycosylase TDG via the base excision repair pathway. Like DNA methyltransferases, Tet enzymes are important for embryonic development. We will examine the mechanism and biological significance of Tet-mediated 5mC oxidation in the context of pronuclear DNA demethylation in mouse early embryos. In contrast to its role in active demethylation in the germ cells and early embryo, a number of lines of evidence suggest that the intragenic 5hmC present in brain may act as a stable mark instead. This short review explores mechanistic aspects of TET oxidation activity, the impact Tet enzymes have on epigenome organization and their contribution to the regulation of early embryonic and neuronal development.

Binding Pattern Elucidation of NNK and NNAL Cigarette Smoke Carcinogens with NER Pathway Enzymes: an Onco-Informatics Study

  • Jamal, Qazi Mohammad Sajid;Dhasmana, Anupam;Lohani, Mohtashim;Firdaus, Sumbul;Ansari, Md Yousuf;Sahoo, Ganesh Chandra;Haque, Shafiul
    • Asian Pacific Journal of Cancer Prevention
    • /
    • v.16 no.13
    • /
    • pp.5311-5317
    • /
    • 2015
  • Cigarette smoke derivatives like NNK (4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone) and NNAL (4-(methylnitrosamino)-1-(3-pyridyl)-1-butan-1-ol) are well-known carcinogens. We analyzed the interaction of enzymes involved in the NER (nucleotide excision repair) pathway with ligands (NNK and NNAL). Binding was characterized for the enzymes sharing equivalent or better interaction as compared to +Ve control. The highest obtained docking energy between NNK and enzymes RAD23A, CCNH, CDK7, and CETN2 were -7.13 kcal/mol, -7.27 kcal/mol, -8.05 kcal/mol and -7.58 kcal/mol respectively. Similarly the highest obtained docking energy between NNAL and enzymes RAD23A, CCNH, CDK7, and CETN2 were -7.46 kcal/mol, -7.94 kcal/mol, -7.83 kcal/mol and -7.67 kcal/mol respectively. In order to find out the effect of NNK and NNAL on enzymes involved in the NER pathway applying protein-protein interaction and protein-complex (i.e. enzymes docked with NNK/NNAL) interaction analysis. It was found that carcinogens are well capable to reduce the normal functioning of genes like RAD23A (HR23A), CCNH, CDK7 and CETN2. In silico analysis indicated loss of functions of these genes and their corresponding enzymes, which possibly might be a cause for alteration of DNA repair pathways leading to damage buildup and finally contributing to cancer formation.

Mechanisms of Cadmium Carcinogenicity in the Gastrointestinal Tract

  • Bishak, Yaser Khaje;Payahoo, Laleh;Osatdrahimi, Alireza;Nourazarian, Alireza
    • Asian Pacific Journal of Cancer Prevention
    • /
    • v.16 no.1
    • /
    • pp.9-21
    • /
    • 2015
  • Cancer, a serious public health problem in worldwide, results from an excessive and uncontrolled proliferation of the body cells without obvious physiological demands of organs. The gastrointestinal tract, including the esophagus, stomach and intestine, is a unique organ system. It has the highest cancer incidence and cancer-related mortality in the body and is influenceed by both genetic and environmental factors. Among the various chemical elements recognized in the nature, some of them including zinc, iron, cobalt, and copper have essential roles in the various biochemical and physiological processes, but only at low levels and others such as cadmium, lead, mercury, arsenic, and nickel are considered as threats for human health especially with chronic exposure at high levels. Cadmium, an environment contaminant, cannot be destroyed in nature. Through impairment of vitamin D metabolism in the kidney it causes nephrotoxicity and subsequently bone metabolism impairment and fragility. The major mechanisms involved in cadmium carcinogenesis could be related to the suppression of gene expression, inhibition of DNA damage repair, inhibition of apoptosis, and induction of oxidative stress. In addition, cadmium may act through aberrant DNA methylation. Cadmium affects multiple cellular processes, including signal transduction pathways, cell proliferation, differentiation, and apoptosis. Down-regulation of methyltransferases enzymes and reduction of DNA methylation have been stated as epigenetic effects of cadmium. Furthermore, increasing intracellular free calcium ion levels induces neuronal apoptosis in addition to other deleterious influence on the stability of the genome.

Imidazole Ring-Opened DNA Purines and Their Biological Significance

  • Barbara, Tudek
    • BMB Reports
    • /
    • v.36 no.1
    • /
    • pp.12-19
    • /
    • 2003
  • Fragmentation of purine imidazole ring and production of formamidopyrimidines in deoxynucleosides (Fapy lesions) occurs upon DNA oxidation as well as upon spontaneous or alkali-triggered rearrangement of certain alkylated bases. Many chemotherapeutic agents such as cyclophosphamide or thiotepa produce such lesions in DNA. Unsubstituted FapyA and FapyG, formed upon DNA oxidation cause moderate inhibition of DNA synthesis, which is DNA polymerase and sequence dependent. Fapy-7MeG, a methylated counterpart of FapyG-, a efficiently inhibits DNA replication in vitro and in E.coli, however its mutagenic potency is low. This is probably due to preferential incorporation of cytosine opposite Fapy-7MeG and preferential extension of Fapy-7MeG:C pair. In contrast, FapyA and Fapy-7MeA possess miscoding potential. Both lesions in SOS induced E.coli preferentially mispair with cytosine giving rise to A$\rightarrow$G transitions. Fapy lesions substituted with longer chain alkyl groups also show simult aneous lethal and mutagenic properties. Fapy lesions are actively eliminated from DNA by repair glycosylases specific for oxidized purines and pyrimidines both in bacteria and eukaryotic cells. Bacterial enzymes include E.coli formamidopyrimidine-DNA-glycosylase (Fpg protein), endonuclease III (Nth protein) and endonuclease VIII (Nei protein).

The RecA-like protein of Schizosoccharomvces pombe: its cellular level is induced by DNA-damaging agents (DNA 상해요인에 의한 Schizosaccharomyces pombe RecA 유사 단백질의 유도생성)

  • 이정섭;박상대
    • The Korean Journal of Zoology
    • /
    • v.37 no.2
    • /
    • pp.232-239
    • /
    • 1994
  • RecA protein plans a central role in homologous recombination and DNA repair in Escherichia cofi (E. colD. The function 8nd structure of this protein are universal in prokarvotes and also conserved in eukaryotes such as yeast. The RecA-like protein with 74 lInDa in size has already been identified and purified from a fission yeast Schizosaccharomyces pombe (5. pommel (Lee, 19911. From this study it was revealed that the RecA-like protein of 5. pombe was highly inducible to various DNA damaging agents and inhibitors of nucleotide pool svnthesizins enzymes. The cellular level of the 5. pombe RecA-like protein wi,u markedly increased, upto 5- to 10-fold, by treatment with various DNA-damains agents including ultraviolet (UV) light, methyl methanesulfonate WS),4-nitroquinoline-1-oxide (4-NQO), and mitomycin-C (MMC), similar to E. cofi RecA protein. Interestingly, the protein level was also increased by inhibitors of nucleotide pool forming enzlwnes such as methotrexate (MTX) and hvdroxvurea (HU). The most effective doses for the inducibility of 4-NQO, MMS, W, MMC, MTX, and HU were 0.2 Ug/ml, 30 mM, 200 J/ma, 0.4 $\mus/ml,$ 1 Ug/ml, and 100 mM, respectively. The range of effective duration time for the inducibilitv of RecA-like protein was from 270 to 450 mins. These results suggest that the 5. pombe RecA-like protein also platys an imortant role in cellular responses to DNA damage as in E. coli system.

  • PDF

Comparative Genome Analysis of Psychrobacillus Strain PB01, Isolated from an Iceberg

  • Choi, Jun Young;Kim, Sun Chang;Lee, Pyung Cheon
    • Journal of Microbiology and Biotechnology
    • /
    • v.30 no.2
    • /
    • pp.237-243
    • /
    • 2020
  • A novel psychrotolerant Psychrobacillus strain PB01, isolated from an Antarctic iceberg, was comparatively analyzed with five related strains. The complete genome of strain PB01 consists of a single circular chromosome (4.3 Mb) and a plasmid (19 Kb). As potential low-temperature adaptation strategies, strain PB01 has four genes encoding cold-shock proteins, two genes encoding DEAD-box RNA helicases, and eight genes encoding transporters for glycine betaine, which can serve as a cryoprotectant, on the genome. The pan-genome structure of the six Psychrobacillus strains suggests that strain PB01 might have evolved to adapt to extreme environments by changing its genome content to gain higher capacity for DNA repair, translation, and membrane transport. Notably, strain PB01 possesses a complete TCA cycle consisting of eight enzymes as well as three additional Helicobacter pylori-type enzymes: ferredoxin-dependent 2-oxoglutarate synthase, succinyl-CoA/acetoacetyl-CoA transferase, and malate/quinone oxidoreductase. The co-existence of the genes for TCA cycle enzymes has also been identified in the other five Psychrobacillus strains.