Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.30.2 (endonuclease)
18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An Arabidopsis thaliana cDNA encoding an analogue, referred to as Arp for apurinic endonuclease-redox protein, of the human redox factor REF has been cloned. Arp stimulates in vitro DNA-binding activity of the human transcription factor Jun and Fos by the reduction of a cysteine residue located in the DNA-binding domain. Based on amino acid sequence homology, this redox activity is probably confined to the small internal domain of the Arp protein. In analogy to REF, we show that the Arabidopsis Arp protein also functions as an apurinic/apyrimidinic class II endonuclease. This base-free endonuclease activity resides in the carboxyl-terminal domain, and this part of the protein has significant sequence similarity to bacterial (Escherichia coli exonuclease III and Streptococcus pneumoniae exonuclease A) and animal (Drosophila Rrp1 and human REF/HAP) apurinic/apyrimidinic endonucleases. The amino-terminal domain of the Arp protein is highly charged and apparently increases the affinity of the protein for DNA. Therefore, the Arabidopsis Arp protein is multifunctional and may be involved both in DNA repair and in the regulation of transcription.
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PMID:The Arabidopsis thaliana apurinic endonuclease Arp reduces human transcription factors Fos and Jun. 751 29

We have cloned mouse and human cDNAs for a multifunctional DNA repair enzyme (APEX nuclease) having apurinic/apyrimidinic (AP) endonuclease, 3',5' exonuclease, DNA 3' repair diesterase and DNA 3'-phosphatase activities. To investigate the biological role of APEX nuclease, sense or antisense APEX RNA was stably expressed at a high level in cultured rat glioma cells by introducing plasmids (pABWN-HAPX1F for expression of sense RNA or pABWN-HAPX2R for expression of antisense RNA) constructed from the human APEX cDNA and an expression vector pABWN. Multiple copies of the construct were integrated into the glioma cells transfected with pABWN-HAPX1F or pABWN-HAPX2R. These transfectants showed markedly high expression of RNA hybridizable to human APEX cDNA, indicating the expression of the sense or antisense RNA. Activity blotting analyses of salt extracts of these transfectants showed that the sense RNA-expressed cells had higher AP endonuclease activity and that the antisense RNA-expressed cells had extremely lower AP endonuclease activity than the control cells. The APEX nuclease-depressed glioma cells became more sensitive to methyl methanesulfonate and hydrogen peroxide than the control cells or the APEX nuclease-overexpressed cells. The results indicate that APEX nuclease plays an important role in repair of DNA damage caused by these genotoxic agents. The present stable expression systems for the sense and antisense APEX RNAs should be useful for analyzing the biological functions such as an antimutagenic function of the enzyme.
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PMID:Stable expression in rat glioma cells of sense and antisense nucleic acids to a human multifunctional DNA repair enzyme, APEX nuclease. 751 11

A mammalian apurinic/apyrimidinic endonuclease (AP endonuclease) is known to have two distinct functional domains. One domain is responsible for regulating the activity of Fos/Jun proto-oncogene products to bind to DNA at specific recognition sites. The other domain, which is highly conserved from bacteria to mammals, is responsible for repairing DNA damage caused by ionizing radiation, oxidative damage, and alkylating agents. This study reports on the isolation and characterization of the genomic structure of the mouse AP endonuclease gene (Apex). The genomic sequence of the Apex gene was 2.14 kb in length and contained four exons. Exon 1 contained a 0.24-kb untranslated 5' region upstream of the initiation codon. Consensus sequences for two CAAT boxes and a GC box were found upstream of the end of exon 1. A polymorphism was noted in the untranslated region of exon 1 in a comparison of a number of mouse strains. These data indicate that the 5' end of the mouse gene (Apex) differs from the previously isolated human gene (Ape), which has five exons and an untranslated region between exons 1 and 2. Data are also presented that suggest the presence of two pseudogenes in the mouse.
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PMID:Genomic structure of the mouse apurinic/apyrimidinic endonuclease gene. 753 13

Apurinic/apyrimidinic endonuclease (APE; also referred to as Ref-1) repairs oxidative damage to DNA and regulates the redox state of DNA binding proteins. This later property influences the ability of DNA binding proteins, which include Fos and Jun, to bind to AP-1 complexes. Since DNA binding proteins may play important roles in regulating neuronal activity in the hypothalamus, we examined the expression of APE in the hypothalami of rats. In situ hybridization studies revealed high levels of APE mRNA expression in the suprachiasmatic nuclei (SCN), supraoptic nuclei (SON) and paraventricular nuclei (PVN). Since the SCN are the site of a biological clock, we examined whether APE gene expression was regulated by the circadian cycle or by light. Quantitative in situ hybridization studies showed that APE mRNA levels remained constant over the circadian cycle and were not increased by light exposure at night. We also tested if APE expression was under osmotic control in the SON and PVN. Hypertonic stimulus, however, did not induce further expression of APE mRNA in either the SON or the PVN. These findings identify the SCN, SON and PVN as sites of high level APE gene expression. These data suggest that APE may play an important role in these structures either to facilitate DNA repair or DNA binding protein action.
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PMID:Expression of a multifunctional DNA repair enzyme gene, apurinic/apyrimidinic endonuclease (APE; Ref-1) in the suprachiasmatic, supraoptic and paraventricular nuclei. 753 93

Expression of the mammalian major apurinic/apyrimidinic (AP) endonuclease (designated as APEX nuclease, or HAP1, APE or Ref-1 gene product) during mouse brain development was investigated by in situ and northern blot hybridizations. The enzyme is known to be a redox factor (Ref-1) stimulating DNA binding activity of AP-1 binding proteins such as Fos and Jun as well as a multifunctional DNA repair enzyme having 5' AP endonuclease, DNA 3' repair diesterase, 3'-5' exonuclease and DNA 3'-phosphatase activities. In the embryonic and postnatal development, APEX mRNA was expressed at high levels in the proliferative zone of various brain regions, with showing temporal and spatial changes. Its expression decreased in association with brain development to the basal expression level which was observed even in adulthood, with the exception of its expression in the hippocampal formation. The growth-dependent expression of APEX gene suggests that it has some roles on cell proliferation and/or differentiation in developmental brain. Its expression on the hippocampal formation became significant from postnatal day 7 and then increased. The pyramidal and granule cell layers expressed it at a higher level than most other brain regions at postnatal day 21. The developmental change of APEX gene expression was not necessarily associated with the changes of expression of c-fos and c-jun genes measured by northern blot hybridization. However, the present results suggested that APEX/Ref-1 gene product can interact with AP-1 binding proteins in brain, especially in the hippocampal formation, to regulate some brain functions by redox-activation.
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PMID:Developmental expression of APEX nuclease, a multifunctional DNA repair enzyme, in mouse brains. 765 3

The DNA of all species is constantly under threat from both endogenous and exogenous factors, which damage its chemical structure. Probably the most common lesion that arises in cellular DNA is the loss of a base to generate an abasic site, which is usually referred to as an apurinic or apyrimidinic (AP) site. Since these lesions are potentially both cytotoxic and mutagenic, cells of all organisms express dedicated repair enzymes, termed AP endonucleases, to counteract their damaging effects. Indeed, many organisms consider it necessary to express two or more of these lesion-specific endonucleases, underscoring the requirement that exists to remove AP sites for the maintenance of genome integrity and cell viability. Most AP endonucleases are very versatile enzymes, capable of performing numerous additional repair roles. In this article, we review the AP endonuclease class of repair enzymes, with emphasis on the evolutionary conservation of structural features, not only between prokaryotic and eukaryotic homologues, but also between these enzymes and the RNase H domain of one class of reverse transcriptase.
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PMID:Structure and function of apurinic/apyrimidinic endonucleases. 766 52

1. Mammalian major apurinic/apyrimidinic (AP) endonuclease, APEX nuclease (M(r) 35.4 kDa) was purified from HeLa cells. A hybrid protein (M(r) 36.4 kDa), which was expressed in BW2001 strain cells of E. coli, comprising human APEX nuclease headed by 10 additional amino acids was also purified. 2. The purified preparations were frequently associated with 31-, 33- and 35-kDa peptides having AP endonuclease activity. 3. The 33- and 35-kDa peptides were suggested to be formed from the hybrid protein or APEX nuclease during their purification processes by proteolytic cleavage with subtilisin-like protease. The 31-kDa peptide was thought to be produced by chemical cleavage of the aspartyl-prolyl bond of APEX nuclease. 4. The results support the notion that some of AP endonuclease heterogeneity based on the molecular weight difference are caused by proteolytic (and chemical) cleavage of a species of AP endonucleases during the extraction and purification.
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PMID:A possible cause of heterogeneity of mammalian apurinic/apyrimidinic endonuclease. 767 58

Ionizing radiation produces a variety of DNA damage through active oxygen species such as the superoxide radical (O2.-), the hydroxyl radical (OH.), and hydrogen peroxide (H2O2). The removal of alkylation-induced apurinic (AP) sites and 3'-blocking deoxyribose fragments by exonuclease III (xth) and endonuclease IV (nfo) has been well demonstrated in E. coli. Very little information on the repair of radiation-induced DNA damage by human apurinic endonuclease is available. We examined the biological roles of the human AP endonuclease in the repair of radiation-induced DNA damage. An expression vector was constructed with human APE cDNA and transformed into radiation-sensitive E. coli mutants (xth- and nfo-). The radiation cytotoxicity was assayed by cell survival curves. Expression of human AP endonuclease in E. coli confirmed that AP endonuclease could complement exonuclease III functionally to diminish radiation cytotoxicity. In contrast, AP endonuclease was not able to increase resistance to H2O2, owing to a poor 3'-termini repair. We also tested whether AP endonuclease is a limiting factor for radiation cytotoxicity by using a plasmid nicking assay. Cell extracts from mutant cells with or without AP endonuclease expression were added to irradiated supercoiled plasmid DNA. The inability to convert supercoiled plasmid DNA to relaxed or linear forms suggested that there were large accumulations of AP sites in the mutant cell extracts. The AP endonuclease activities estimated from the plasmid nicking assays are 20-fold lower in the cell extracts of AP endonuclease-deficient mutant than in AP endonuclease-expressing cells. Therefore, AP endonuclease is a limiting step of base excision repair for the radiation-sensitive E. coli mutant, BW528. Our results conclude that AP endonuclease is responsible for the removal of AP sites from gamma-radiation-induced base damage in E. coli.
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PMID:Reduction of radiation cytotoxicity by human apurinic endonuclease in a radiation-sensitive Escherichia coli mutant. 769 Sep 78

Drosophila Rrp1 (Recombination repair protein 1) belongs to a family of DNA repair nucleases that includes Escherichia coli exonuclease III, Streptococcus pneumoniae exonuclease A, bovine BAP, mouse APEX endonuclease, and human APE. Within a 252 amino acid region, colinear homology is shared between all members. Rrp1 is unique in that it includes a 427 amino acid N-terminal region not related to any known sequence. The protein copurifies with an apurinic endonuclease and a double-stranded DNA 3'-exonuclease. In this study, a 5'-end-labeled 37 base pair oligonucleotide substrate containing a single apurinic site was used to characterize the endonuclease activity of Rrp1. This substrate is utilized efficiently by Rrp1: the specific activity observed is 1 x 10(5) units/mg. The abasic double-stranded DNA oligonucleotide is cleaved only at the abasic site to create a single-strand break. Strand breaks are not detected in the complementary strand, in the single-stranded DNA oligonucleotide, or in the base-paired control substrate. After endonucleolytic cleavage at the abasic site, exonucleolytic processing at the nick is slow and requires a molar excess of Rrp1, while exonuclease III degrades the nicked substrate more efficiently. The Rrp1 cleavage product comigrates with a DNaseI cleavage product, and the newly formed terminus supports DNA synthesis by DNA polymerase. Therefore, Rrp1 cleaves the phosphodiester backbone at one position 5' to the apurinic site and leaves a 3'-hydroxyl terminus. Rrp1 is a class II apurinic endonuclease and is likely to be important in DNA repair in Drosophila.
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PMID:Characterization of the apurinic endonuclease activity of Drosophila Rrp1. 769 63

A human apurinic/apyrimidinic endonuclease activity, called AP endonuclease I, is missing from or altered specifically in cells cultured from Xeroderma pigmentosum group-D individuals (XP-D cells) (Kuhnlein, U., Lee, B., Penhoet, E. E., and Linn, S. (1978) Nucleic Acids Res. 5,951-960). We have now observed that another nuclease activity, UV endonuclease III, is similarly not detected in XP-D cells and is inseparable from the AP endonuclease I activity. This activity preferentially cleaves the phosphodiester backbone of heavily ultraviolet-irradiated DNA at unknown lesions as well as at one of the phosphodiester bonds within a cyclobutane pyrimidine dimer. The nuclease activities have been purified from mouse cells to yield a peptide of M(r) = 32,000, whose sequence indicates identity with ribosomal protein S3. The nuclease activities all cross-react with immunopurified antibody directed against authentic rat ribosomal protein S3, and, upon expression in Escherichia coli of a cloned rat cDNA for ribosomal protein S3, each of the activities was recovered and was indistinguishable from those of the mammalian UV endonuclease III. Moreover, the protein expressed in E. coli and its activities cross-react with the rat protein antibody. Ribosomal protein S3 contains a potential nuclear localization signal, and the protein isolated as a nuclease also has a glycosylation pattern consistent with a nuclear localization as determined by lectin binding. The unexpected role of a ribosomal protein in DNA damage processing and the unexplained inability to detect the nuclease activities in extracts from XP-D cells are discussed.
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PMID:Implication of mammalian ribosomal protein S3 in the processing of DNA damage. 777 13


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