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)

A class of revertants of Bacillus subtilis mutant rec H, which completely restored the ability to transformation but without restoring the activity of ATP-dependent deoxyribonuclease, is isolated and studied. Reversions are located in the same chromosome region as the original mutation. The detection of such revertants points out the existence of more than one recombination pathway for Bac. subtilis transformation.
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PMID:[One of the classes of revertants of a rec H Bacillus subtilis mutant]. 9 71

Infection by bacteriophage T4 has previously been shown to cause a rapid inhibition of the host recBC DNase, an ATP-dependent DNase that is required for genetic recombination in Escherichia coli. We report here the partial purification of a protein ("T4 rec inhibitor") from extracts of T4-infected cells and some characteristics of the in vitro inhibition reaction with purified inhibitor and recBC nuclease. This inhibitory activity could not be purified from extracts of uninfected E. coli. Both the ATP-dependent exonuclease and DNA-dependent ATPase activities of recBC DNase are inhibited by T4 rec inhibitor. Experiments suggest that the inhibitor interacts with the nuclease in a stoichiometric manner. The biological significance of this inhibition is discussed with respect to control reactions in phage-infected cells.
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PMID:Postinfection control by bacteriophage T4 of Escherichia coli recBC nuclease activity. 13 May 1

Over 95% of the deoxyribonuclease (DNase) activity of log-phase mycelia of Neurospora crassa is expressed as single-strand (ss) specific endonucleolytic activity. This activity is associated with three nucleases (D1, D2, and D3) which after partial purification from extracts, express activity with double-strand (ds) DNA as well. All three enzymes also degrade RNA at approximately the same rates that they degrade ss-DNA. D3 has been identified as endoexonuclease, an enzyme previously shown to have endonuclease activity with ss-DNA and RNA and exonuclease activity with ds-DNA, both of which are inhibited by ATP. D3 is inhibited by ATP, is relatively resistant to p-hydroxymercuribenzoate (PHMB), and sediments with an apparent molecular weight of 75 000. D2 has the properties of the previously described mitochondrial nuclease. It is a relatively unstable Mg2+-dependent endonuclease with no appreciable strand specificity for DNA. In addition, it is not inhibited by ATP and is strongly inhibited by PHMB and by the ethylenediamine tetraacetic acid (EDTA). It also sediments with an apparent molecular weight of 75,000. The properties of D1 are quite variable from one preparation to another. Freshly isolated D1 sediments with an apparent molecular weight of 180 000. It often shows some inhibition by ATP, but is relatively resistant to both PHMB and EDTA. However, on 'ageing,' the properties of D1 gradually convert to those of D2 with concomitant decrease in molecular weight, loss of inhibition by ATP, and increase in sensitivities to PHMB and EDTA. The results indicate that D1 is very likely a second form of the mitochondrial enzyme. Evidence was obtained for the presence of protein inhibitor(s) in crude extracts which may account for the masking of the ds-DNase activities of these enzymes in extracts. Two Rec-like mutants of Neurospora (uvs-3, and nuh-4) are deficient mainly inexpressed levels of D3, the endo-exonuclease. However, the levels of inactive endo-exonuclease precursor in these two mutants are higher than in the wild type. There may, therefore, be some defect in the conversion of precursor to active enzyme in these two mutants. Another mutant, which is not sensitive to mutagens relative to the wild (nuh-3), has depressed levels of both endo-exonuclease and the mitochondrial enzyme. Nuh-3 has some defect in the conversion of D1 to D2. Proteinases probably play some role in vivo in these enzyme conversions.
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PMID:The major intracellular alkaline deoxyribonuclease activities expressed in wild-type and Rec-like mutants of Neurospora crassa. 15 96

Genetic recombination of phage lambda DNA mediated by Rec function of Escherichia coli was studied in the absence of duplication, transcription, translation, and maturation. Cells were jointly infected with double amber mutants, lambda D-F-I and lambda S-R-, and incubated in the presence of chloramphenicol and rifampin. The am+ recombinant DNA molecules formed within the cell were detected by in vitro packaging as viable recombinant phages. This system was used to measure the recombination activity of rec- bacteria. In recA or recA recB bacteria, the number of recombinant DNA molecules was about 1% of the rec+ level. In contrast, almost normal numbers of recombinant DNA molecules were formed in recB or recC cells. Therefore, (1) the recombination mediated by recA function does not need de novo protein synthesis; all gene products required for the recombination are present in the cell. (2) It can occur without duplication, transcription, and maturation of recombining DNA molecules. (3) The ATP dependent DNase (exonuclease V) controlled by recB and recC genes is not required for formation of recombinant DNA molecules.
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PMID:Formation of recombinant DNA of bacteriophage lambda by recA function of Escherichia coli without duplication, transcription, translation, and maturation. 33 Oct 71

Upon exposure to the carcinogens N-acetoxy-N-2-acetylaminofluorene and 7-bromomethyl-benz[a]anthracene, which bind covalently to DNA, ether-permeabilized (nucleotide-permeable) Escherichia coli wild-type cells responded with DNA excision repair. This repair was missing in mutants carrying defects in genes uvrA, uvrB and uvrC, whereas it was present in uvrD and several rec mutants. Enzymic activities involved were identified by measuring repair polymerization and size reduction of denatured DNA. 1. An easily measurable effect in E. coli wild-type cells was carcinogen-induced repair polymerization. When initiated by N-acetoxy-N-2-acetylaminofluorene or 7-bromomethyl-benz[a]anthracene, it depended upon an ATP-requiring step; CTP, GTP or UTP did not substitute for ATP. DNA repair synthesis was inhibited by p-chloromercuribenzoate and quinacrine. In uvrA, uvrB and uvrC mutants no carcinogen-stimulated DNA synthesis could be detected, indicating that steps involved in pyrimidine dimer excision are also involved in chemorepair. In recA, recB and recC mutant cells, repair synthesis was stimulated by the carcinogens to a normal extent. This evidence excludes the ATP-dependent recB,C deoxyribonuclease and recA gene products as playing an important role in carcinogen-induced excision repair. polA1 cells showed drastically reduced levels of rapair polymerization, indicating that DNA polymerase I is the main polymerizing enzyme. 2. As determined by DNA size reduction in alkaline sucrose gradients, the arylalkylating carcinogens caused endonucleolytic cleavage of endogenous DNA in wild-type cells. This incision step was most effectively performed in the presence of ATP; UTP, CTP and GTP were only slightly effective. Incision was inhibited by p-chloromercuribenzoate and quinacrine. When exposed to the arylalkylating carcinogens, uvrA, uvrB and uvrC mutant cells did not perform the incision step in the presence of ATP, suggesting the involvement of the respective gene products in the initiation of chemorepair.
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PMID:Carcinogen-induced DNA repair in nucleotide-permeable Escherichia coli cells. Analysis of DNA repair induced by the carcinogens N-acetoxy-N-2-acetylaminofluorene and 7-bromomethyl-benz(a)anthracene. 76 31

Mice were injected three times over an 8-hour period with a total of 48 muci 3H-T/gm of body weight and were sacrificed 1, 3, 5, 9 and 17 days afterwards. Radioautographs of the ovaries showed significantly higher grain counts in oocytes of follicles that are in the antrum formation stage. The radioautographic visualization of DNase digestible 3H-thymidine incorporation into the juxtanucleolar region in oocytes of mature mice occurs in association with ooctye growth in follicles that are in the antrum formation stage. The scheduled disappearance of this juxtanucleolar oocyte DNA and its label during later oocyte growth suggests a degradation or dispersion of this labeled DNA prior to ovulation.
Anat Rec 1976 Dec
PMID:DNA synthesis in the oocyte of the mature mouse: a radioautographic study. 100 56

Previous attempts to prepare skeletal muscle basal laminae (BL) for ultrastructural analyses have been hampered by difficulties in successfully removing skeletal muscle proteins and cellular debris from BL tubes. In the present study we describe a two phase method which results in an acellular muscle preparation, the BL of which are examined by light, transmission electron, and scanning electron microscopy. In the first phase, excised rat extensor digitorum longus muscles are subjected to x-radiation and then soaked in Marcaine to inhibit muscle regeneration and to destroy peripheral muscle fibers. The muscles are then grafted back into their original sites and allowed to remain in place 7-14 days to allow for maximal removal of degenerating muscle tissue with minimal scar tissue formation. In the second phase, the muscle grafts are subjected sequentially to EDTA, triton X-100, DNAase, and sodium deoxycholate to remove phagocytizing cells and associated degenerating muscle tissue. These procedures result in translucent, acellular muscle grafts which show numerous empty tubes of BL backed by endomysial collagenous fibers. These preparations should be useful for morphological analyses of isolated muscle BL and for possible in vitro studies by which the biological activity of muscle BL can be examined.
Anat Rec 1991 Jul
PMID:A method for preparing skeletal muscle fiber basal laminae. 190 15

The inactivation of rec BC (D) DNase upon chromatography on DEAE-cellulose was observed. Simultaneously DNA-stimulated ATPases (I and II) and DNase activities on single- and double-stranded DNA substrates were measured in Escherichia coli rec+ and rec- cell extracts. Normal levels of ATPase I and II were detected in rec+ cells. Rec A- cells were lacking DNA dependent ATPase I, while rec B single and rec BC double mutants were defective in DNA dependent ATPase II, the second major enzyme of this type. Rec B and C mutations did not change DNase activities. Rec A mutation significantly increased DNase activity on linear single-stranded substrate.
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PMID:Rec mutants of Escherichia coli deficient in subunits of rec BC (D) complex. 196 45

Four out of more than 8,200 Staphylococcus aureus strains isolated in Japan between 1961 and 1980 were constitutively resistant to a variety of macrolide antibiotics except tylosin and rokitamycin, but susceptible to lincosamide and streptogramin type B antibiotics (PM). The data obtained by agarose gel electrophoresis, CsCl-ethidium bromide density gradient analysis, diagnosis with ATP-dependent deoxyribonuclease, and a test transducing into a rec- mutant with phage 80L2 propagated on PM-resistant S. aureus all suggested that the determinant for the PM-resistance is located in chromosome.
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PMID:Localization of a determinant mediating partial macrolide resistance in Staphylococcus aureus. 212 34

ATP-dependent DNAase genes of Bac. subtilis were originally cloned in E. coli plasmid pBR322. These genes are expressed in rec BC mutant E. coli cells leading to a complete recovery of the enzyme activity. Bac. subtilis enzyme suppresses reparative properties of the rec BC mutant to a considerable extent but is unable to replace functionally the E. coli mutant enzyme in recombination process.
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PMID:[Partial suppression of rec B rec C mutations in E. coli by plasmid pBR 322 containing a Bacillus subtilis chromosome insertion]. 298 61


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