Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.21.1 (DNase)
 7,655 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Small unilamellar vesicles (75-100 nm diameter) and large liposomes (greater than 1 micron in diameter) were prepared containing the lamB protein, an outer membrane protein of Escherichia coli and Shigella which serves as the receptor for bacteriophage lambda. Bacteriophage were observed to bind to these liposomes and vesicles by their tails and in most cases the heads of the bound bacteriophage appeared empty or partially empty of DNA. The lambda DNA was usually only partially ejected from the bacteriophage head when small unilamellar liposomes were used, presumably because the vesicles are too small to contain all the DNA. The partially ejected DNA was not susceptible to DNase unless the vesicle bilayer was first disrupted suggesting that DNA injection of phage DNA into the vesicle had occurred. After disruption of these vesicles on electron microscope grids, the bacteriophage are seen to have partially empty heads and a small mass of DNA associated with their tails. Using larger liposomes prepared by the fusion of lamB bearing vesicles with polyethylene glycol and n-hexyl bromide, the heads of most of the bound bacteriophage appeared to be completely empty of DNA. Disruption of these preparations on electron microscope grids revealed circular arrays of empty-headed bacteriophage surrounding DNA which had apparently been contained within the intact liposomes. These results indicate that high molecular weight DNA can be entrapped within liposomes with high efficiency by ejection from bacteriophage lambda. The possible use of these DNA-containing liposomes to facilitate gene transfer in eukaryotic cells is discussed.
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PMID:Injection of DNA into liposomes by bacteriophage lambda. 621 8

A sensitive, modified 3,5-diaminobenzoic acid (DABA), fluorometric DNA assay was developed and compared to mithramycin and ethidium bromide assays in determining the DNA content of dense connective tissues including: Swarm rat chondrosarcoma, rabbit, dog, monkey, and most importantly, adult human articular cartilage. In the more cellular cartilages, the three methods gave equivalent results. However, in the relatively acellular human cartilage, the DABA method was shown to be superior. Both the mithramycin and ethidium bromide gave falsely high values compared to the DABA method, which by subtraction after DNase digestion approached the DABA value. The latter was completely DNase sensitive. With the DABA method, the DNA content of human cartilage can be obtained on less than 5 mg wet weight of fresh, alcohol-fixed, or lyophilized material. While the DNA can also be released by digestion with papain or protease from Streptomyces griseus, proteinase K was preferable. The comparison of literature values for other fluorometric and spectrophotometric assays of human cartilage suggest these methods overestimate human articular cartilage DNA concentrations, whereas the DABA values were in line with those predicted from previous morphometric analysis. Thus, the modified method represents an improvement in DNA analysis of dense connective tissues.
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PMID:Fluorometric determination of DNA in cartilage of various species. 623 38

An apurinic endonuclease activity has been characterized in yeast mitochondrial. It is dependent on Mg2+, stimulated by about 50% in the presence of 50 mM NaCl and inhibited at higher NaCl concentrations. It is located in the inner mitochondrial membrane and requires high concentrations of detergent (1.5-3% Triton X-100) to be extracted. The same treatment extracts several other endonuclease activities: the two Mg2+-dependent endonuclease activities cleaving double-stranded DNA at pH 7.5 and 5.4 respectively, the ethidium-bromide-stimulated endonuclease activity, the endonuclease activity cleaving single-stranded DNA at pH 7.l5 [Jacquemin-Sablon et al. (1979) Biochemistry, 18, 119-127], and a manganese-stimulated deoxyribonuclease activity cleaving double-stranded DNA at pH 7.5 which has been discovered during the present work. Another endonuclease activity cleaving double-stranded DNA at pH 7.5 in the presence of Mg2+, slightly stimulated by low NaCl concentrations and inhibited by ethidium bromide is extracted from the membrane pellet remaining after the treatment with 1.5% Triton X-100 by a second treatment with 1.5% Triton X-100 plus 1 M KCl. The presence in the mitochondrial membrane of this apurinic endonuclease activity indicates that, like nuclear and prokaryotic DNA, yeast mitochondrial DNA is also subject to specialized repair systems.
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PMID:Endonucleases in yeast mitochondria: apurinic and manganese-stimulated deoxyribonuclease activities in the inner mitochondrial membrane of Saccharomyces cerevisiae. 628 1

The acid-extractable leaf proteins of potato spindle tuber viroid (PSTV) infected tomato plants were analysed electrophoretically on polyacrylamide gels. The most prominent alteration found during disease development was the appearance of a "pathogenesis-related" protein with an apparent molecular weight of 14,000 (called P14) which is drastically increased in concentration. Its induction, however, is not viroid-specific because it is also accumulating after viral and fungal infections. The degree of P14 accumulation could be directly correlated with the severity of the disease symptoms and its concentration was found to be highest in leaves of the tomato cultivar "Rutgers" four weeks after infection. P14 was isolated from such leaf material by acid-extraction of the leaf proteins, which were concentrated from the clarified homogenates by ultrafiltration through hollow fiber systems or by precipitation at 60 per cent ammonium sulphate saturation. P14 was finally purified by ion exchange chromatography on sulfopropyl (SP-C25) Sephadex and on DEAE cellulose. A protein with properties similar to those of P14 could also be isolated from healthy tomato leaves, where its concentration is about forty to fifty times lower than PSTV-infected tissue. P14 can be stained with Coomassie Brilliant Blue, silver and ethidium bromide, it is sensitive to digestion with pronase and not altered when treated with RNase and DNase. P14 is a basic protein with an estimated isoelectric point of 10.7 and its unusual behaviour during ultrafiltration indicates that it represents an elongated rather than a globular molecule in solution. P14 seems to be different from any of the so-called "pathogenesis-related" proteins described so far in Gynura aurantiaca, "Etrog" citron, potato and tomato after viroid-infection and in tobacco, cucumber and bean leaves after virus- or fungus-induced hypersensitive reactions.
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PMID:Purification and partial characterization of the major "pathogenesis-related" tomato leaf protein P14 from potato spindle tuber viroid (PSTV)-infected tomato leaves. 647 30

High-level resistance to gentamicin, tobramycin, and kanamycin was transferred between staphylococci of the same and different species by filter mating. Resistance and transfer proficiency were mediated by plasmids ranging from 38 to 54 kilobases in size. All of the plasmids encoded intermediate resistance to amikacin and netilmicin and resistance to ethidium bromide; some encoded beta-lactamase production. None of these plasmids carried resistance to other antibiotics or heavy metals. Transfer of antibiotic resistance occurred by a mechanism similar to that of conjugation, because it was DNase resistant, required cell-to-cell contact, and did not appear to involve phage. The participation of phage in transfer appeared to be unlikely because mijtomicin C-induced lysates of donor isolates did not mediate transfer, filter mating transfer proceeded at high frequency between nonlysogenic donor and recipient cells, and transfer of the aminoglycoside resistance plasmid mobilized the transfer of as many as five additional plasmids. All 17 gentamicin-resistant Staphylococcus aureus and all 6 Staphylococcus epidermidis isolates obtained from an outbreak of staphylococcal infections in a newborn nursery contained conjugative plasmids, as did all 6 gentamicin-resistant S. aureus isolates from bacteremic adults. However, only 3 of 10 gentamicin-resistant S. epidermidis isolates from colonized cardiac surgery patients and 1 of 2 S. epidermidis isolates from patients with prosthetic valve endocarditis transferred gentamicin resistance by filter mating. The recent increase in nosocomial infections caused by gentamicin-resistant staphylococci may be partially explained by the evolution of self-transmissible plasmids in these isolates.
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PMID:Self-transmissible plasmids in staphylococci that encode resistance to aminoglycosides. 662 57

Cyanophora paradoxa, a unicellular flagellate, contains cyanelles which are supposed to be cyanobacterial origin. DNA was isolated from subcellular fractions and separated according to density components in CsC1 density gradients. The main DNA component, comprising more than 90% of the total DNA, has a buoyant density of 1.724 g X cm-3. Several subsfractions in the range from 1.718 g X cm-3 to 1.735 g X cm-3 are contained in this component. This DNA of high complexity was considered to be host nuclear DNA. The DNA from the endosymbiotic cyanelles, which were isolated, treated with DNase, and purified by sucrose density gradient centrifugation exhibited a buoyant density of 1.692 g X cm-3 in one strain and 1.695 g X cm-3 in a second strain. Both cyanelle DNAs (cyDNA) have a complexity of approximately 126 X 10(3) base pairs and comprise about 5% of the total cellular DNA content. Two additional DNA components of low complexity were isolated from crude cyanelle pellets obtained without DNase treatment. The larger of these, approximately 48 X 10(3) base pairs in size, had a density of approximately 1.688 g X cm-3. The second component, about 15 X 10(3) base pairs in size, banded in the density range between 1.710 g X cm-3 and 1.720 g X cm-3. The latter is associated with nuclear DNA. The 48 X 10(3)-base-pair component was located in the cytosol and could be obtained after CsC1/ethidium bromide density gradient centrifugation at the position of covalently closed circular DNA. Both these components amounted to approximately 0.5-1% of total DNA. A further DNA component with a complexity of more than 150 X 10(3) base pairs, enriched in fractions where mitochondria are expected, was not characterized further. The density was intermediate between cyDNA and nuclear DNA (1.710-1.720 g X cm-3) and it amounted to 1-2% of the total DNA. Our results indicate that the DNA from cyanelles, believed to be endosymbiotic cyanobacteria, is not more complex than higher plant chloroplast DNAs.
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PMID:The subcellular localization of DNA components from Cyanophora paradoxa, a flagellate containing endosymbiotic cyanelles. 681 19

When lymphocytes obtained from W/Fu rats primed with BCG are cultured in the presence of PPD, they elaborate a factor that is capable of potentiating the specific in vitro generation of cytotoxic lymphocytes to syngeneic (C58NT)D lymphoma cells and to BN alloantigen. Purification of the factor, achieved by gel filtration on Sephadex G-100, was facilitated by using a serum-free culture condition and the removal of the specific stimulating antigen, PPD, after an initial incubation period. The factor isolated contains DNA by its absorption spectrum, resistance to trypsin and RNase, but complete susceptibility to DNAase, and by the presence of ethidium bromide-positive material in the purified sample. It displays a 260/280 nm absorption ratio of 1.6 and a m.w. estimate of 10,000 to 30,000. Electrophoresis of the purified factor on agarose gel yielded three ethidium bromide reactive bands. Data obtained following the slicing and elution of these bands, and then testing for potentiating activity indicated that two of the three bands contained potentiating activity.
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PMID:Specific enhancement of immune responses by BCG: isolation of extracellular DNA from supernatants of specifically stimulated BCG-primed lymphoid cells. 698 4

The "killer" plasmid and a larger double-stranded RNA plasmid of yeast exist in intracellular virion particles. Purification of these particles from a diploid killer strain of yeast (grown into stationary growth on ethanol) resulted in co-purification of a DNA-independent RNA polymerase activity. This activity incorporates and requires all four ribonucleoside triphosphates and will not act on deoxyribonucleoside triphosphates. The reaction requires magnesium, is inhibited by sulfhydryl-oxidizing reagents and high concentrations of monovalent cation, but is insensitive to DNase, alpha-amanitin, and actinomycin D. Pyrophosphate inhibits the reaction as does ethidium bromide. Exogenous nucleic acids have no effect on the reaction. The product is mostly single-stranded RNA, some of which is released from the enzymatically active virions.
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PMID:Virion DNA-independent RNA polymerase from Saccharomyces cerevisiae. 700 33

The effect of various metabolic inhibitors (carbonylcyanid-m-chlorophenylhydrazone, nigericin, valinomycin, dicyclocarbodiimide, arsenate, NaF, etc.) and lipid-soluble synthetic ions (tetraphenylphosphonium bromide and tetraphenylboron sodium) on deoxyribonucleic acid (DNA) entry during transformation of Ca2+-treated Escherichia coli cells with plasmid DNA and on cell viability was investigated. In contrast to intact cells, Ca2+-treated E. coli cells were permeable to nigericin, valinomycin, and the other drugs tested. The inhibitors differentially affected [14C]proline active transport, and whereas some drugs inhibited transformation, the effects did not correlate with the effects on transport. The most potent inhibitors of transformation were nigericin, dicyclocarbodiimide, and tetraphenylboron sodium. Carbonylcyanid-m-chlorophenylhydrazone, tetraphenylphosphonium bromide, and valinomycin were relatively inactive. Tetraphenylboron sodium- and nigericin-treated cells bound were plasmid [14C]DNA in the deoxyribonuclease-resistant form than the control and other sample cells. Nevertheless, te penetration of exogenous plasmid DNA into the cell was greatly reduced, at least in case of nigericin. Unlike the other drugs, nigericin and dicyclocarbodiimide drastically affected the cell viability, the former within very short times of interaction. It is concluded that proton motive force does not play any significant role in DNA entry into Ca2+-treated E. coli cells. The results also suggest that adenosine 5'-triphosphate is not required for DNA entry either. The inhibitory effect of certain drugs is discussed in terms of structural perturbations induced by the drugs in cell envelope membranes.
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PMID:Effect of metabolic inhibitors on entry of exogenous deoxyribonucleic acid into Ca2+-treated Escherichia coli cells. 701 27

Four nuclear thermosensitive mutants have been obtained in which induction of up 100% cytoplasmic petite mutants (rho-) is observed upon cell incubation at 36 degrees C. For a given incubation time at 36 degrees C, the percentage of rho- is increased by preliminary gamma-ray irradiation. Under these conditions, the induction of rho- is a linear function of the irradiation dose. The retention of genetic information by rho- and of mitochondrial DNA synthesis in vivo and in vitro exclude that the mutants are deficient in the replication of mitochondrial DNA. The degradation of mitochondrial DNA labeled with [3H]dTTP in isolated mitochondria, has been monitored at 26 degrees C and at 36 degrees C after addition of 0.5% Triton X-100 in the presence or in the absence of ethidium bromide. In assays carried out at 26 degrees C, the degradation of mitochondrial DNA is similar in the parental strain and in the mutant gamma s rho 2. However, at 36 degrees C, the degradation of mitochondrial DNA is slower in the mutant. We have shown that a mitochondrial membrane deoxyribonuclease acting on double-stranded DNA at acid pH is thermosensitive in the mutant. Analysis of the meiotic segregants of a tetrad issued from the cross of the mutant with an isogenic parental strain shows co-segregation of rho- induction and of nuclease thermosensitivity in a 2:2 Mendelian pattern. These results suggest that a mitochondrial deoxyribonuclease is involved in the repair of damages caused to mitochondrial DNA by elevated temperature and by x-rays.
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PMID:Repair of mitochondrial DNA in Saccharomyces cerevisiae. Induction of cytoplasmic petite mutants in a nuclear mutant exhibiting thermosensitive mitochondrial deoxyribonuclease activity. 703 19


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