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)

Exonuclease III is the major apurinic/apyrimidinic (AP) endonuclease of Escherichia coli, accounting for more than 80% of the total cellular AP endonuclease activity. We have shown earlier that the endonucleolytic activity of exonuclease III is able to hydrolyze the phosphodiester bond 5' to the urea N-glycoside in a duplex DNA [Kow, Y. W., & Wallace, S. S. (1985) Proc. Natl. Acad. Sci. U.S.A. 82, 8354-8358]. Therefore, we were interested in studying the mechanism of action of the endonucleolytic activity of exonuclease III by preparing DNA containing different base lesions as well as chemically modified AP sites. When AP sites were converted to O-alkylhydroxylamine residues, exonuclease III was able to hydrolyze the phosphodiester bond 5' to O-alkylhydroxylamine residues. The apparent Km for different O-alkylhydroxylamine residues was not affected by the particular O-alkylhydroxylamine residue substituted; however, the apparent Vmax decreased as the size of the residue increased. On the basis of a study of the substrate specificity of exonuclease III, a modification of the Weiss model for the mechanism of action of exonuclease III is presented. Furthermore, a temperature study of exonucleolytic activity of exonuclease III in the presence of Mg2+ showed discontinuity in the Arrhenius plot. However, no discontinuity was observed when the reaction was performed in the presence of Ca2+. Similarly, no discontinuity was observed for the endonucleolytic activity of exonuclease III, in the presence of either Ca2+ or Mg2+. These data suggest that, in the presence of Mg2+, exonuclease III, in the presence of either Ca2+ or Mg2+.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Mechanism of action of Escherichia coli exonuclease III. 266 68

Incubation of isolated rat liver nuclei with ATP, NAD+, and submicromolar Ca2+ concentrations resulted in extensive DNA hydrolysis. Half-maximal activity occurred with 200 nM Ca2+, and saturation of the process was observed with 1 microM Ca2+. ATP stimulated a calmodulin-dependent nuclear Ca2+ uptake system which apparently mediated endonuclease activation. Ca2+-activated DNA fragmentation was inhibited by the inhibitor of poly(ADP-ribose) synthetase, 3-aminobenzamide, and was associated with poly(ADP-ribosyl)ation of nuclear protein. The characteristics of this endonuclease activity indicate that it may be responsible for the Ca2+-dependent fragmentation of DNA involved in programmed cell death (apoptosis) and in certain forms of chemically induced cell killing.
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PMID:Calcium-activated DNA fragmentation in rat liver nuclei. 270 97

Restriction endonuclease analysis (BamHI and EcoRI) was used to investigate the structural variability of 40-50 Mdal plasmids from 129 Yersinia enterocolitica strains isolated from human patients, animals, and food in 12 countries in Europe, North America, and Asia. A total of 12 restriction patterns was detected among plasmids from the six serogroups examined. The DNA fragment profiles were found to vary, not only between serogroups, but also among plasmids isolated from strains with the same serogroup affiliation. Despite widespread geographical and ecological origin, the plasmids isolated from the 0:3 and 0:9 strains examined revealed a surprising stability, whereas plasmids from 0:8 and 0:5,27 showed substantial diversity. The genes associated with autoagglutination, calcium dependency, and mouse virulence were conserved in all 12 plasmid variants detected. Our finding that porcine and human isolates harboured plasmids with identical restriction patterns, provides additional support for the importance of pigs in the epidemiology of human Y. enterocolitica infection.
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PMID:Structural variability of 40-50 Mdal virulence plasmids from Yersinia enterocolitica. Geographical and ecological distribution of plasmid variants. 282 Jan 89

The rapid involution of the rat ventral prostate after castration is an active process initiated by removal of the inhibitory effects of androgen on prostatic cell death. The present studies demonstrate that after castration-induced androgen deprivation a series of temporally discrete biochemical events are activated which result in the rapid programmed death of the subset of androgen-dependent cells within the rat ventral prostate. These biochemical steps involve 1) rapid loss of nuclear androgen receptor retention; by 12 h after castration, androgen receptors are no longer detectable in ventral prostatic nuclei; 2) an initial fragmentation of nuclear DNA into low mol wt (less than 1000 basepairs) nucleosomal oligomers which lack intranucleosomal break points; and 3) eventual complete digestion of these nucleosomal oligomers into component nucleotides. Additional studies demonstrate that activation of a Ca2+-Mg2+-dependent endonuclease is associated with this DNA fragmentation. By 4 days after castration, maximal DNA fragmentation is obtained, with 15% of the total nuclear DNA extractable as low mol wt fragments. Proteolytic enzymes are apparently not involved initially in this process, suggesting that DNA fragmentation is a discrete event in, rather than a result of, cell death. Flow cytometric analysis of nuclear DNA content demonstrated that each day after castration, a subpopulation of androgen-dependent cells in rat ventral prostate fragmented all of their genomic DNA, as opposed to the whole population of cells fragmenting an increasing portion of their DNA daily.
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PMID:Activation of programmed cell death in the rat ventral prostate after castration. 282 3

Yersinia pseudotuberculosis was isolated from retail pork and from healthy swine throats. These wild-type strains and their representative cured isogenic strains were tested for the presence of plasmids and several virulence factors, and these characteristics were compared with those of virulent strains from humans. Two pork isolates (serotype IVB) and four swine isolates (serotypes IIB, IIC, III, and IVB) harbored a 42- to 48-megadalton plasmid which had similar fragmentation patterns resulting from digestion with restriction endonuclease. These six strains were lethal for mice via oral challenge and were positive in autoagglutination and calcium dependency tests. They also invaded HeLa cells and induced cytotoxicity. Histopathological examination and indirect fluorescent-antibody staining provided definite evidence of the pathogenicity of these strains when tissue sections from orally infected mice were used. The virulence factors of wild-type pork and swine isolates with the 42- to 48-megadalton plasmid were identical to those of two human isolates (serotypes IVB and VB). Hence, these pork and swine isolates should be considered potentially pathogenic for humans. The finding suggests that retail pork and swine may play an important role in the epidemiology of human infections caused by Y. pseudotuberculosis.
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PMID:Virulence of Yersinia pseudotuberculosis isolated from pork and from the throats of swine. 283 45

An endonuclease was purified from the cap tissues of basidiocarp of Coprinus cinereus collected at early meiotic prophase. It has an optimal activity at pH 7.0 and 37 degrees C. It is a cationic enzyme with a molecular mass of 22 kDa by gel filtration, and contains a 12-kDa and a 14-kDa peptide as revealed by SDS gel electrophoresis and Western blot analysis. An antiserum was produced in rabbits against the purified Coprinus endonuclease. The specificity of this antiserum was demonstrated in a dot-blot analysis and, more critically, in an immunoinhibition of endonuclease activity. The Coprinus endonuclease requires Mg2+ and/or Ca2+ as co-factors. Ca2+ is more efficient than Mg2+ while the effect of combining both co-factors is the highest. The Coprinus endonuclease has a substrate preference for single-strand and supercoiled DNA. It gives only single-strand nicks on supercoiled DNA at low enzyme concentration and limited time of incubation. At high enzyme concentration and/or long incubation time, double-strand fragmentation occurred. As is discussed, this endonuclease is believed to be involved in the early phase of meiotic recombination.
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PMID:Purification and characterization of an endonuclease from fruiting caps of basidiomycete Coprinus cinereus. 283 39

Incubation of freshly isolated rat hepatocytes with moderately toxic concentrations of menadione [2-methyl-1,4-naphthoquinone) resulted in chromatin condensation and progressive DNA fragmentation, suggestive of the stimulation of an endogenous endonuclease activity previously found to be involved in programmed cell death (apoptosis). Endonuclease activation followed upon a sustained increase in cytosolic Ca2+ concentration and preceded cell killing by 1-2 h. It is concluded that generation of oxidative stress in hepatocytes can activate processes similar to those observed during programmed cell death.
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PMID:Stimulation of endogenous endonuclease activity in hepatocytes exposed to oxidative stress. 284 75

The mechanism of glucocorticoid-induced internucleosomal DNA cleavage and cytolysis of lymphatic cells is not known. Recent data (Compton, M.M., and Cidlowski, J.A. (1987) J. Biol. Chem. 262, 8288-8292) suggested that in vivo treatment of rat thymocytes with glucocorticoids induces a nucleolytic "lysis gene" product(s) responsible for lymphocytolysis. In this paper, the possibility that lymphocytolysis may result from glucocorticoid-induced nuclease(s) was examined. Using the rat thymocytes as a model system, we have shown by electrophoretic, enzymatic, and amino acid sequence analysis that the putative glucocorticoid-induced nucleases identified recently by Compton and Cidlowski are in fact H1, H1(0), and core histones, and their gross appearance is not the result of new histone protein synthesis, but a result of the release of histone-containing nucleosomes during chromatin breakdown. Evidence presented here shows that the putative induced nuclease activity is an artifact of the assay system employed. Because our data do not support induction of a glucocorticoid-induced nuclease(s), we examined the possibility that DNA cleavage might be induced by activation of a constitutive endogenous endonuclease. We have shown that it is possible to produce characteristic internucleosomal DNA cleavage of rat thymocytes, merely by incubating intact nuclei from untreated adrenalectomized rat thymocytes with Ca2+ and Mg2+ for a short period of time. However, in glucocorticoid-sensitive human CEM-C7 lymphocytes activation of internucleosomal DNA cleavage was independent of calcium uptake. We conclude that glucocorticoid induction of internucleosomal DNA fragmentation does not necessarily require expression of a new nuclease(s), but is the result of the activation of a constitutive endogenous endonuclease(s). Also, our data suggest that the mechanism which controls activation of internucleosomal DNA cleavage in rat thymocytes differs from that which operates in CEM-C7 lymphocytes.
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PMID:Glucocorticoid-induced lymphocytolysis is not mediated by an induced endonuclease. 291 90

An endodeoxyribonuclease, designated CreI, was purified 16,000-fold from zygotes of the eukaryote Chlamydomonas reinhardtii. CreI preferentially attacks the sequence TATA producing double strand breaks with 3'-phosphomonoester and 5'-hydroxyl termini. The endonuclease has an Mr = 27,000 and requires Ca2+ at pH 7.5 for optimal activity.
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PMID:An endonuclease from Chlamydomonas reinhardtii that cleaves the sequence TATA. 300 78

Autodigestion of nuclei isolated from the androgen-dependent Shionogi mouse mammary carcinoma revealed the presence of endogenous endonuclease activity which was stimulated by Ca2+ and Mg2+ and generated a repeating pattern of DNA fragments with an average monomeric size of 179 base pairs. The nuclear concentration of endonuclease activity declined rapidly after castration to a level 45% of that measured in tumours from non-castrated hosts. Most of the endonuclease activity (80%) could be extracted in a soluble form after sonication of the nuclei and subsequent centrifugation. The reduced concentration of endonuclease activity in regressing tumours following castration was not due to changes in chromatin template conformation and could be restored to normal levels within 1 day of androgen treatment. Examination of DNA synthetic activity and the concentration of nuclear androgen receptors during tumour regression indicated that the decrease in endonuclease activity paralleled the declining rate of DNA synthesis but was preceded by a loss of nuclear androgen receptors. Together these results suggest that the endonuclease activity of the Shionogi carcinoma is more likely involved with androgen-stimulated cell proliferation rather than with the autophagic mechanism responsible for tumour regression and cell death.
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PMID:Changes in endonuclease activity during growth and regression of the Shionogi mammary carcinoma. 301 60


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