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:3.1.21.1 (DNase)
7,655 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The existence of a DNA-dependent protein methylase activity without any concomitant DNA methylase activity was demonstrated in bull seminal plasma. The enzyme utilized S-adenosyl-L-methionine as a methyl donor, and endogenous seminal plasma protein as the substrate. There was no demonstrable enzyme activity when the seminal plasma was preheated at 100 degrees for 10 min, or when the enzyme reaction mixture was incubated at 4 degrees. The protein methylase required a heterologous DNA source, had optimal activity at pH 8.1, and was enhanced in the presence of Mg2+, NH4+, and reduced glutathione. After the methylated protein product was separated from DNA by extraction with 0.2 M HCl, the incorporated radioactivity was shown to be totally solubilized by incubating the protein either with Pronase or 1 M NaOH, while RNase and DNase had no effect. Approximately 70% of the enzymatically synthesized amino acids in the protein product were tentatively identified as O-methylated amino acid ethers by virtue of their elution from a Dowex 50 H+ column with 0.2 M pyridine, and their stability to acid and base hydrolysis. The partially purified methylated product was shown by Sephadex G-50 chromatography to consist of three distinct radioactive proteins with molecular weights of approximately 21,000, 15,000, and 10,000.
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PMID:DNA-dependent protein methylase activity in bull seminal plasma. 24 Mar 99

On growing the cells of Bacillus brevis S methionine-auxotroph mutant in the presence of [Me-3H]methionine, practically all the radioactivity incorporated into DNA is found to exist in 5-methylcytosine and N6-methyladenine. The analysis of pyrimidine isopliths isolated from DNA shows that radioactivity only exists in mono- and dinucleotides and the content of 5-methylcytosine in R-m5 C-R and R-m5 C-T-R oligonucleotides is equal. The analysis of dinucleotides isolated from DNA by means of pancreatic DNAase hydrolysis allows the nature of purine residues neighbouring 5-methylcytosine to be identified and shows that 5-methylcytosine localizes in G-m5 C-A and G-m5 C-Tr fragments. B. brevis S DNA methylase modifying cytosine residues recognizes the GCA/TGC degenerate nucleotide sequence which is a part of the following complementary structure with a two-fold rotational axis of symmetry: (5')...N'-G-C-T-G-C-N... (3') (3')...N-C-G-A-C-G-N'... (5') (Methylated cytosine residues are askerisked). Cytosine-modifying DNA methylase activity is isolated from B. brevis cells; it is capable of methylating in vitro homologous and heterologous DNA. Hence DNA in bacterial cells can be undermethylated. This enzyme methylates cytosine residues in native and denatured DNA in the same nucleotide sequences. Specificity of methylation of cytosine residues in vitro and in vivo does not depend on the nature of substrate DNA. DNA methylases of different variants of B. brevis (R, S, P+, P-)) methylate cytosine residues in the same nucleotide sequences. It means that specificity or methylation of DNA cytosine residues in the cells of different variants of B. brevis is the same.
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PMID:On the nature of the cytosine-methylated sequence in DNA of Bacillus brevis var. G.-B. 118 Sep 70

Fibrobacter succinogenes is an important cellulolytic bacterium found in the rumen and cecum of herbivores. Numerous attempts to introduce foreign DNA into F. succinogenes S85 have failed, suggesting the presence of genetic barriers in this organism. Results from this study clearly demonstrate that F. succinogenes S85 possesses a type II restriction endonuclease, FsuI, which recognizes the sequence 5'-GG(A/T)CC-3'. Analysis of the restriction products on sequencing gels showed that FsuI cleaves between the two deoxyguanosine residues, yielding a 3-base 5' protruding end. These data demonstrate that FsuI is an isoschizomer of AvaII. A methyltransferase activity has been identified in the cell extract of F. succinogenes S85. This activity modified DNA in vitro and protected the DNA from the restriction by FsuI and AvaII. DNA modified in vivo by a cloned methylase gene, which codes for M.Eco47II, also protected the DNA from restriction by FsuI, suggesting that FsuI is inhibited by methylation at one or both deoxycytosine residues of the recognition sequence. The methyltransferase activity in F. succinogenes S85 is likely modifying the same deoxycytosine residues, but the exact site(s) is unknown. A highly active DNase (DNase A) was also isolated from the cell extract of this organism. DNase A is an endonuclease which showed high activity on all forms of DNA (single stranded, double-stranded, linear, and circular) but no activity on RNA. In vitro, the DNase A hydrolyzed F. succinogenes S85 DNA extensively, indicating the lack of protection against hydrolysis by this enzyme. In the presence of Mg2+, DNA was hydrolyzed to fragments of 8 to 10 nucleotides in length. The presence of DNase A and the type II restriction-modification system of F. succinogenes S85 may be the barriers preventing the introduction of foreign DNA into this bacterium.
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PMID:Type II DNA restriction-modification system and an endonuclease from the ruminal bacterium Fibrobacter succinogenes S85. 164 54

The Escherichia coli-Brevibacterium lactofermentum shuttle vector pBLA was introduced into intact cells of B. lactofermentum by electrotransformation. Several parameters of this procedure such as voltage and cell concentration were analysed. Optimal conditions gave an efficiency of 10(6) transformants per microgram of DNA. Two recalcitrant strains could be electrotransformed when an ampicillin pretreatment step was used. Electrotransformation experiments using DNAase or different structural forms of plasmid DNA showed that the electrotransformation process is quite different from natural transformation involving competence development. Restriction-modification-proficient B. lactofermentum could be efficiently electrotransformed with pBLA DNA isolated from E. coli. This restriction-modification system therefore seems to be overcome by electrotransformation. Thus electrotransformation may efficiently replace the protoplast bacterial transformation method.
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PMID:Transfer of plasmid DNA to Brevibacterium lactofermentum by electrotransformation. 226 76

Transformation of pBR322 DNA into Shigella occurred at a low frequency. The efficiency of transformation was highest in S. dysenteriae 1 and lowest in S. flexneri. Treatment of cells with CaCl2 for a prolonged period (24h) increased the efficiency of transformation in all strains, except in S. flexneri, where transformation efficiency could not be improved by a variety of manipulations. Transformation efficiency did not increase in any of the strains when transformation was carried out with plasmid DNA obtained from a transformant (homologous transformation), suggesting the absence of a strong restriction-modification system. Extracellular deoxyribonuclease (DNase) levels were low in all the strains tested, but the levels of endogenous DNAse, released after CaCl2 treatment or sonication of the cells, were high. Washing the cells with a solution of CaCl2 did not enhance transformation, suggesting that endogenous DNase could be a significant factor affecting transformation efficiency in species of Shigella.
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PMID:Studies on transformation in Shigella. 239 Jul 45

Transformation (i.e., DNase-sensitive genetic transfer) of strains of Streptococcus mutans representing serotypes c and e was accomplished by using chromosomal DNA from a Rifr Strr Spcr isolate of strain GS5 (UAB525) and a chimeric plasmid, pYA629. Shuttle plasmid pYA629 comprises the S. mutans plasmid pVA318, an inducible erythromycin resistance determinant originally isolated from a group A streptococcal strain, the tetracycline resistance gene and replication region of the Escherichia coli plasmid pBR322, and the promoter region of the S. mutans gene for aspartate beta-semialdehyde dehydrogenase. The strains examined for recipient ability included those known to lack a cryptic plasmid (GS5, UA130, UA159, and MT8148) and those known to contain a widely disseminated 5.8-kilobase cryptic plasmid (LM7, V318, UA101, UA174, and 3098791). The transformation frequencies in GS5 for GS5 chromosomal antibiotic resistance markers were comparable to those reported by others, but UA101, UA130, UA159 and UA174 were transformed with both chromosomal and plasmid markers at much higher efficiencies. In a larger strain survey, strains containing the 5.8-kilobase cryptic plasmid were more frequently transformable with both chromosomal and pYA629 DNAs than were strains lacking this cryptic plasmid. All plasmid-containing strains except LM7 lost their resident cryptic plasmids when transformed with pYA629. LM7 transformed with pYA629 retained pLM7. There are therefore at least two incompatibility groups among S. mutans cryptic plasmids. yPA629 DNA isolated from either E. coli or S. mutans transformed S. mutans with equal efficiency. pYA629 DNA isolated from S. mutans transformed both restriction-deficient and restriction-proficient E. coli recipients. Therefore, the strains of S. mutans used lack a restriction-modification system for pYA629 DNA sequences. S. mutans strains that are readily transformable, display maximal cariogenicity in gnotobiotic rats, and give high scores for in vitro measures of important virulence attributes have been identified to facilitate studies on the genetic basis and control of virulence.
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PMID:Transformation of Streptococcus mutans with chromosomal and shuttle plasmid (pYA629) DNAs. 302 26

In human placenta, the DNA of all subfractions of the third level of chromatin organization exhibits similar values of the methylcytosine-to-cytosine ratio. The tightly bound form of DNA methyltransferase is mostly recovered in the 'stripped loop' fraction, although, on the basis of the DNA content, the 'stripped loops' and the 'stripped matrix' appear to possess a similar amount of the enzyme. DNA methyltransferase activity is instead totally absent from the 'digested matrix', i.e., from the fraction remaining after digestion of the 'stripped matrix' with DNAase I. Upon addition of exogenous DNA methyltransferase, however, the DNA of this fraction, which is only 1% (in weight) of the total chromatin DNA and which has a length of approx. 9 kbp, can readily undergo methylation.
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PMID:Localization, in human placenta, of the tightly bound form of DNA methylase in the higher order of chromatin organization. 319 Nov 32

When chromatin matrix, "stripped" from its loosely-bound components by extraction with 3 M NaCl, is extensively digested with DNAase I, a fraction is obtained, which carries no endogenous DNA methyltransferase activity but which is a good substrate for externally added enzyme. Under the same conditions, protein-free DNA isolated from this fraction can instead hardly be methylated, this different behaviour pointing to a role of DNA-tightly-bound proteins in favoring or promoting the catalytic action of the enzyme. A similar stimulation of enzymatic methylation could also be shown when, in the presence of this same fraction, single stranded Micrococcus luteus DNA was incubated with placental methyltransferase, using S-adenosylmethionine as a methyl donor. This finding can be correlated to the existence, in chromatin loops, of small regions which resist digestion by DNAase I also after high-salt removal of their loosely-bound components (presumably because of the presence of tightly-bound proteins) and whose DNA is characterized by high methylation levels and, at the same time, by high relative content of thymine.
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PMID:Do tightly-bound chromatin proteins play a role in DNA methylation? 325 63

A library of Bacillus subtilis chromosomal deoxyribonucleic acid (DNA) was constructed, using lambda charon 4A as a cloning vector. Partially cleaved Bacillus subtilis DNA was prepared by partial methylation with EcoRI methylase, followed by complete EcoRI endonuclease digestion. More than 95% of the phage particles carried B. subtilis DNA inserts. When this library was screened for transforming activity, using competent cells, 70% of the genetic markers tested were found in a sample of 1,710 plaques. Cloned genetic loci were found to be about 100-fold more efficient in transforming activity than chromosomal DNA. Intact phage particles containing the pheA locus were found to be able to transform competent recipients with approximately the same efficiency as phage DNA. Transformation by intact particles was insensitive to deoxyribonuclease.
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PMID:Isolation of Bacillus subtilis genes from a charon 4A library. 626 Jul 47

In 1995, we discovered new antiherpetic antibiotics, called fattiviracins. The producing organism was classified as a strain belonging to Streptomyces microflavus. The strain produced at least 13 fattiviracin derivatives (FV-1 to FV-13). Fattiviracins were obtained as a white amorphous powder, and their molecular weights are in the range of 1400 to 1500. They are readily soluble in water, methanol, pyridine, and DMSO, but insoluble in other organic solvents. Fattiviracins have macrocyclic diesters formed by the binding of two trihydroxy fatty acids and two D-glucose residues in the molecule, and they can be divided into five families according to the length of the fatty acid moiety. Fattiviracins have potent activity against enveloped DNA viruses such as the herpes family, HSV-1, and VZV and enveloped RNA viruses such as influenza A and B viruses, and three strains of HIV-1, with EC(50) values on the order of a few micrograms per milliliter. The biosynthetic pathway of fattiviracins is also becoming clearer. Using bacitracin-resistant strains, enhanced and astringent production of fattiviracin was achieved. Fattiviracin FV-13, which has the longest fatty acid chains in the molecule, was dramatically enhanced by a C(55)-isoprenyl phosphate metabolism. In addition, we have screened various inhibitors of enzymes such as alkaline protease, glucosyltransferase, glucuronidase, phospholipase, deoxyribonuclease, DNA methyltransferase, and DNA topoisomerase. All the inhibitors we discovered are briefly summarized in this paper.
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PMID:[Metabolites produced by actinomycetes--antiviral antibiotics and enzyme inhibitors]. 1529 17


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