Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.21.3 (deoxyribonuclease)
 1,528 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have investigated the use of liposomes as carriers for the transfer of simian virus 40 (SV40) DNA into mammalian cells. The amount of DNA entrapped in liposomes was dependent on the input DNA concentration and lipid composition. DNA remained intact after liposome encapsulation and was resistant to deoxyribonuclease digestion. Combined transfer to and expression of liposome-entrapped SV40 DNA in monkey kidney cells was assayed by infectious plaque formation. Negatively-charged liposomes containing phosphatidylserine were more effective in DNA transfer and expression than neutral liposomes. The inclusion of carrier salmon sperm DNA inhibited liposome-entrapped SV40 DNA infectivity. Infectivity of liposome-entrapped DNA was directly related to both liposome DNA concentration and number of vesicles added. Liposome-entrapped SV40 minichromosome was 20-fold more infective than free minichromosome, but only 20% more infective than liposome-entrapped SV40 DNA. Thus, the presence of hyperacetylated histones on the DNA failed to enhance liposome-mediated DNA transfer appreciably. Incubation of cells with various modulators of endocytosis implicated the endocytotic pathway in the mechanism of liposome-mediated DNA transfer. These studies show that liposomes are suitable carriers for the introduction of viral DNA and chromatin into mammalian cells.
J Gen Virol 1983 Apr
PMID:Liposome-mediated transfer of simian virus 40 DNA and minichromosome into mammalian cells. 630 Mar 9

The actual cellular target of the cytotoxic intermediates of melanin synthesis is not yet known. In the present paper it is shown that eukaryotic DNA binds in vitro to soluble reaction products of tyrosinase (EC 1.14.18.1) and is physically modified, as ascertained by the following criteria: (a) buoyant density in cesium chloride density gradients; (b) polyacrylamide gel electrophoresis; (c) deoxyribonuclease (EC 3.1.4.5) test; (d) electron microscopy. The results reported here support the view that DNA itself may be a target for the cytotoxic intermediates of melanin synthesis.
Mol Gen Genet 1984
PMID:Possible genotoxicity of melanin synthesis intermediates: tyrosinase reaction products interact with DNA in vitro. 642 31

During transformation of B. subtilis cells with the Bsu R restriction-modification system by means of pUB110 plasmid restriction and modification of the plasmid DNA occurs. The effect of restriction on the transformation frequency is relatively weak, bringing about 20-fold decrease only. When using cells of a modifying recipient, the frequency of AR9 phage-mediated transduction of unmodified plasmid DNA is also relatively little decreased. The frequency of transduction by chromosomal markers, under the same conditions, falls much lower.
Mol Gen Genet 1980
PMID:Transformation and transduction of Bacillus subtilis strains with the Bsu R restriction-modification system by means of modified and unmodified DNA of pUB110 plasmid. 677 30

Transforming chromosomal DNA, irradiated with long-wave UV light in the presence of 4,5',8-trimethylpsoralen (TMP) binds to competent B. subtilis cells as effectively as non-treated DNA, but its transforming activity is strongly reduced. Uptake studies show that the entry of transforming DNA, after some stimulation by short periods of irradiation in the presence of TMP, decreases proportionally with the dose of irradiation. Crosslinking was quantitated by electron microscopy. Since the number of crosslinks increases proportionally with the dose of irradiation, it is suggested that entry of donor DNA is prevented by crosslinks. The inhibition of entry of DNA is paralleled both by decreased breakdown of crosslinked DNA interacting with competent cells, and decreased breakdown by nuclease activity liberated during protoplasting of competent cultures. These data support the model of Lacks et al. (1976) which postulates that a membrane-bound deoxyribonuclease is engaged in the entry of donor DNA into the competent cell. The transforming activity of the chloramphenicol-resistance carrying plasmid pC194, originally obtained from Staphylococcus aureus, is also destroyed by TMP crosslinks. Contrary to chromosomal DNA, its association with the cells is stimulated by long-wave UV irradiation in the presence of TMP, but experiments are presented suggesting that the DNA is still vulnerable to the action of exogenous pancreatic deoxyribonuclease. Transfecting SPP1 DNA is also inactivated by TMP crosslinks. Marker rescue of transfecting DNA containing crosslinks occurs; the extent of rescue of one marker is considerably in excess of that of linked markers.
Mol Gen Genet 1980
PMID:The effect of trimethylpsoralen--crosslinks on entry of donor DNA in transformation and transfection of Bacillus subtilis. 677 93

A mutant of Pseudomonas aeruginosa PAO1 originally isolated on the basis of its sensitivity to methyl methanesulphonate was found to be (i) sensitive to u.v.- and gamma-irradiation, (ii)deficient in recombination as assayed by transduction and conjugation and (iii) deficient in an ATP-dependent deoxyribonuclease activity. Its marker (mms-13) is cotransducible with argB and pyrE which are mapped at approximately 22 min on the P. aeruginosa chromosome.
J Gen Microbiol 1980 Oct
PMID:A mutant of Pseudomonas aeruginosa deficient in an ATP-dependent deoxyribonuclease. 678 84

The genetic determinant for pyocin AP41, a bacteriocin produced by Pseudomonas aeruginosa, has been cloned. The determinant is located on the chromosome flanked by a pair of inverted repeats, forming a transposon-like structure (TnAP41). TnAP41 possesses some features characteristic of the Tn3 family of transposons. Based on a comparison with the structure of the corresponding region of the chromosome of a non-producer strain, we propose that P. aeruginosa has acquired pyocinogeny by the transposition of TnAP41 into the chromosome. The determinant comprises two ORFs encoding the protein subunits responsible for the killing action (the large component) and immunity (the small component). Amino acid sequences of the C-terminus of the large component (the deoxyribonuclease domain) and the immunity protein show remarkable homology to those of E2 group colicins, suggesting that these bacteriocins, which are produced by distantly related species, have originated from a common ancestor.
Mol Gen Genet 1993 Feb
PMID:A novel transposon-like structure carries the genes for pyocin AP41, a Pseudomonas aeruginosa bacteriocin with a DNase domain homology to E2 group colicins. 838 91

The salIR and salIM genes encode the endonuclease and methyltransferase components of the SalI restriction-modification system from Streptomyces albus G. Expression of the salI genes in Escherichia coli was investigated and major differences with Streptomyces were found. In E. coli there is no detectable expression of the salI R gene due to inactivity of the sal-pR promoter region. In the natural host of the system this region directs transcription of the salI genes as a bicistronic message. In contrast to salIR, salIM is transcribed in the heterologous host from a promoter within the salI DNA. Since sal-pR is not active, the gene cannot be expressed as part of the salI operon. It is probably transcribed from sal-pM, a promoter internal to the operon which allows independent expression of the modification gene in Streptomyces. Replacement of sal-pR by the strong pLac promoter allows expression of salIR in E. coli and enhances expression of salIM. The resulting strain produces about 10 times more endonuclease than a Streptomyces clone containing the SalI system under the control of sal-pR.
Mol Gen Genet 1996 Nov 27
PMID:Comparative analysis of expression of the SalI restriction-modification system in Escherichia coli and Streptomyces. 900 89

BsoBI is a type II restriction enzyme found in Bacillus stearothermophilus JN209 that recognizes the symmetric sequence 5'-CYCGRG-3' (Y=C or T; R=A or G) and cleaves between the first and second base to generate a four-base 5' extension. The cloning and sequencing of BsoBI restriction-modification system has been described by Ruan et al. [Mol. Gen. Genet. 252 (1996) 695-699]. Here we report the overexpression of BsoBI restriction endonuclease gene in E. coli by insertion of the endonuclease gene into an expression vector pRRS. The recombinant BsoBI was purified to homogeneity and its N-terminus sequence was determined. It has the same N-terminal aa sequence as the native enzyme. The constitutive expression of BsoBI from pRRS is lethal to E. coli in the absence of the cognate methylase. The bsoBIR gene was mutagenized with either hydroxylamine or by error-prone polymerase chain reaction in vitro and transferred into E. coli via plasmid vectors in the absence of the cognate methylase. Surviving transformants were selected that carry BsoBI variants which lost endonuclease activity. DNA sequencing of the mutant alleles revealed that G123, D124, D212, D246, E252 and H253 are important residues for enzymatic activity. An electrophoretic mobility shift assay was used to identify binding-proficient and cleavage-deficient variants. Seven variants I95M&D124Y, G123R, D212N, K207R&D212V, D246N, D246G and E252K can still bind DNA despite the loss of cleavage activity. Thus, residues D124, D212, D246 and E252 may be located near or within the catalytic center, and are likely involved in metal ion binding.
 ...
PMID:Overexpression of BsoBI restriction endonuclease in E. coli, purification of the recombinant BsoBI, and identification of catalytic residues of BsoBI by random mutagenesis. 909 56

The genes encoding the ApaLI (5'-GTGCAC-3'), NspI (5'-RCATGY-3'), NspHI (5'-RCATGY-3'), SacI (5'-GAGCTC-3'), SapI (5'-GCTCTTCN1-3', 5'-N4GAAGAGC-3') and ScaI (5'-AGTACT-3') restriction-modification systems have been cloned in E. coli. Amino acid sequence comparison of M.ApaLI, M.NspI, M.NspHI, and M.SacI with known methylases indicated that they contain the ten conserved motifs characteristic of C5 cytosine methylases. NspI and NspHI restriction-modification systems are highly homologous in amino acid sequence. The C-termini of the NspI and NlaIII (5'-CATG-3') restriction endonucleases share significant similarity. 5mC modification of the internal C in a SacI site renders it resistant to SacI digestion. External 5mC modification of a SacI site has no effect on SacI digestion. N4mC modification of the second base in the sequence 5'-GCTCTTC-3' blocks SapI digestion. N4mC modification of the other cytosines in the SapI site does not affect SapI digestion. N4mC modification of ScaI site blocks ScaI digetion. A DNA invertase homolog was found adjacent to the ApaLI restriction-modification system. A DNA transposase subunit homolog was found upstream of the SapI restriction endonuclease gene.
Mol Gen Genet 1998 Nov
PMID:Cloning and expression of the ApaLI, NspI, NspHI, SacI, ScaI, and SapI restriction-modification systems in Escherichia coli. 986 76

Lambda coli phage is not inactivated by chymotrypsin, trypsin, or ficin. T(2) phage is slowly inactivated by high concentrations of (alpha-, beta-, gamma-, or Delta-chymotrypsin, but not by trypsin or ficin. P(1) phage is slowly inactivated by alpha-, beta-, or gamma-chymotrypsin, or ficin, more rapidly by Delta-chymotrypsin, and much more rapidly by trypsin. Crystalline egg albumin, crystalline serum albumin, E. coli nucleoprotein, and yeast nucleoprotein are hydrolyzed slowly by alpha-chymotrypsin. Yeast nucleoprotein, like P(1) phage, is hydrolyzed more rapidly by Delta-chymotrypsin than by alpha-chymotrypsin, but not by trypsin or ficin. Neither phages nor native proteins were attacked by papain, carboxypeptidase, deoxyribonuclease, or ribonuclease.
J Gen Physiol 1964 Sep
PMID:THE EFFECT OF PROTEOLYTIC ENZYMES ON E. COLI PHAGES AND ON NATIVE PROTEINS. 1421 51


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