Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Numerous DNA-interactive proteins have been shown to locate specific sequences within large domains of non-target DNA in vitro and in vivo by a one-dimensional diffusion mechanism; however, the biological significance of this process has not been evaluated. We have examined the biological consequences of sliding for the pyrimidine dimer-specific DNA repair enzyme T4 endonuclease V, an enzyme which scans non-target DNA both in vitro and in vivo. An endonuclease V mutant was constructed whose only altered biochemical characteristic, measured in vitro, was a loss in its ability to slide on non-target DNA. In contrast to the native enzyme, when the mutated endonuclease V was expressed in DNA repair-deficient Escherichia coli, no enhanced ultraviolet survival was conferred. These results suggest that the mechanisms which DNA-interactive proteins employ to enhance the probability of locating their target sequences are of significant biological importance.
J Mol Biol 1989 Aug 20
PMID:Biological consequences of a reduction in the non-target DNA scanning capacity of a DNA repair enzyme. 268 89

We have examined the effects of changes in cytosine methylation on DNA repair in UV-irradiated Chinese hamster ovary (CHO) cells. A hypomethylated derivative of the CHO K1B11 line, B11aza, was established by passaging B11 cells over several months in increasing concentrations of 5-azacytidine; greater than 60% demethylation was consistently demonstrated in these conditioned cells. Following a UV dose of 10 J/m2, the amount of repair replication performed within 24 h was approximately twofold higher in B11aza cells than in control B11 cells. Removal of T4 endonuclease V-sensitive sites (ESS) from specific restriction fragments within and around the dihydrofolate reductase (DHFR) gene was then examined in B11aza cells and compared with that in B11 cells. Although demethylation had little or no effect on repair in the 5' half of the DHFR gene, within a nontranscribed sequence immediately downstream from the gene, or within an extragenic region further downstream from the DHFR gene, significant increases in repair were observed at the 3' end of the DHFR gene and within an extragenic region upstream of the DHFR gene. However, the increases in DNA repair were not accompanied by any changes in overall cellular resistance to UV when colony-forming ability was assayed. We suggest that the level of DNA methylation may play an indirect role in the regulation of DNA repair, perhaps through an effect on chromatin structure or transcriptional activity.
Mol Cell Biol 1989 Apr
PMID:Demethylation enhances removal of pyrimidine dimers from the overall genome and from specific DNA sequences in Chinese hamster ovary cells. 272 18

Human hereditary diseases such as xeroderma pigmentosum, Fanconi's anemia, ataxia telangiectasia, and Bloom's syndrome are characterized by a proneness for developing cancer associated with abnormalities in the processing of DNA damage. The molecular defects responsible for predisposing human tissues to cancer are still not well understood, despite the fact that a considerable amount of work has already been done on this problem. In this paper, we show that in human tumor cell lines, in cells transformed by DNA tumor viruses, and in cells derived from certain cancer-prone disorders, the level of activity of a 42-kDa deoxyribonuclease is many times higher than in diploid untransformed control cells. This suggests that this activity is linked to, or may play a role in, malignant transformation.
Mol Carcinog 1989
PMID:Enhanced deoxyribonuclease activity in human transformed cells and in Bloom's syndrome cells. 280 19

Extracts of Rad+ and radiation-sensitive (rad) mutants of the yeast Saccharomyces cerevisiae were examined for total Mg2+-dependent alkaline deoxyribonuclease activity and the presence of a nuclease that crossreacts immunologically with an antiserum raised against an endo-exonuclease from Neurospora crassa, an enzyme exhibiting both deoxyribo- and ribonuclease activities. No significant differences were observed in total deoxyribonuclease activity between Rad+ and rad mutants. The antibody precipitable activity, however, was found to be 30%-40% of the total alkaline deoxyribonuclease activity in logarithmically growing Rad+ cells. Extracts of stationary phase cells were lacking in antibody precipitable activity. Using immunoblot methods, a 72 kDa crossreacting protein was identified from logarithmically growing cells that was absent from stationary phase cells. In all radiation-sensitive mutants examined, except rad52, at least 20% of total activity was precipitable. Extracts from logarithmically growing rad52 mutants, including a rad52::LEU2 insertion mutant, exhibited less than 10% of the Rad+ precipitable activity; however, some crossreacting material was detected. Although, the level of endo-exonuclease activity is influenced by the RAD52 gene, it is not the product of this gene. The total deoxyribonuclease and the antibody precipitable endo-exonuclease activities were also followed during meiosis. Unlike the Rad+ strain which had previously been shown to have increased levels of total and immunoprecipitable endo-exonuclease as cells underwent meiosis, the rad52 mutant exhibited no increases in either category of nuclease activity. Given the importance of the RAD52 gene in repair, recombination and mutagenesis, the endo-exonuclease may be a significant component of these processes.
Mol Gen Genet 1988 Jan
PMID:An endo-exonuclease activity of yeast that requires a functional RAD52 gene. 283 Apr 67

Replacement of the amino-terminal 40-amino-acid region of the 588-amino-acid precursor of the membrane-bound penicillin-binding protein 3 (PBP3) by the decapeptide MKGKEFQAWI was carried out by altering the amino-coding end of the ftsI gene. Insertion of the modified gene into a runaway-replication plasmid under the control of a fused lpp promoter and lac promoter/operator, resulted in the overexpression by Escherichia coli of the modified PBP3 (designated PBP3**) in the cytoplasm. About 80% of the accumulated PBP3** underwent sequestration in the form of insoluble protein granules that were isolated by cell breakage or cell lysis. After selective removal of contaminants by an EDTA-lysozyme/DNase (deoxyribonuclease)/Nonidet extraction, treatment of the granules with guanidinium chloride followed by dialysis against buffer containing 0.5 M NaCl yielded a refolded, water-soluble PBP3**, which, upon chromatography on Superose 12, exhibited the expected 60,000 molecular mass. The refolded PBP3** bound benzylpenicillin in a 1 to 1 molar ratio, was highly sensitive to aztreonam and showed the same degree of thermostability, in terms of penicillin-binding capacity, as the parent, membrane-bound PBP3, suggesting that protein refolding occurred with formation of the correct intramolecular interactions. Two to three mg of refolded PBP3** can be obtained from 1 litre of culture of the overproducing strain.
Mol Microbiol 1988 Jul
PMID:Overexpression, solubilization and refolding of a genetically engineered derivative of the penicillin-binding protein 3 of Escherichia coli K12. 305 Mar 60

Bacteriophage T4 endonuclease V, which is an excision-repair enzyme specific to pyrimidine dimers within DNA, has been crystallized from polyethylene glycol 4000 solution by a vapour diffusion technique. The unit cell is monoclinic, space group P2(1), with unit cell parameters: a = 41.4 A, b = 40.1 A, c = 37.5 A, beta = 90.01 degrees. The unit cell contains two 16,000 Mr molecules. The crystals diffract X-rays beyond 2.3 A resolution and are suitable for structural analysis at high resolution.
J Mol Biol 1988 Aug 05
PMID:Preliminary crystallographic study of pyrimidine dimer-specific excision-repair enzyme from bacteriophage T4. 317 33

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

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 sensitive endonuclease assay was used to study the fate of pyrimidine dimers introduced by ultraviolet irradiation into the nuclear deoxyribonucleic acid of the cellular slime mold Dictyostelium discoideum. Analysis of the frequency of T4 endonuclease V-induced single-strand breaks by alkaline sucrose gradient sedimentation showed that strain NC4 (rad+) removed greater than 98% of the dimers induced by irradiation at 40 J/m2 (254 nm) within 215 min after irradiation. HPS104 (radC44), a mutant sensitive to ultraviolet irradiation, removed 91% under these conditions, although at a significantly slower rate than NC4: only 8% were removed during the 10- to 15-min period immediately after irradiation, whereas NC4 excised 64% during this interval. HPS104 thus appears to be deficient in the activity(ies) responsible for rapidly incising ultraviolet-irradiated nuclear deoxyribonucleic acid at the sites of pyrimidine dimers.
Mol Cell Biol 1981 Feb
PMID:Excision of pyrimidine dimers from nuclear deoxyribonucleic acid in ultraviolet-irradiated Dictyostelium discoideum. 696 95

We have isolated epithelial cell clusters from mammary glands of pregnant and lactating rats by collagenase-hyaluronidase-deoxyribonuclease digestion, followed by Ficoll density-gradient centrifugation. Clusters of greater than 90% viable cells were identified by light microscopy as essentially devoid of other cell types; the integrity of their subcellular organelles verified by electron microscopy. Binding characteristics of the synthetic glucocorticoid [3H]dexamethasone were studied in cytosols prepared from isolated cell clusters. Cytosols from both pregnant and lactating rats bound [3H]dexamethasone with high affinity to a single class of low capacity binding sites. In both types of cytosol the dissociation constant (Kd 4 degrees C approximately/nM) of the binding was similar; the number of sites per cell in lactating rats was approximately double that in pregnant rats. The specificity of binding was typical of a classical glucocorticoid receptor, with a hierarchy of affinity by competition studies dexamethasone greater than progesterone greater than aldosterone much much greater than testosterone = estradiol. In particular, no difference in progesterone affinity for these glucocorticoid receptors was seen between pregnancy and lactation. This suggests that reported differences in inhibitory action of progesterone, pregnancy versus post-partum, are not glucocorticoid-receptor mediated.
Mol Cell Endocrinol 1982 Feb
PMID:Glucocorticoid receptors in epithelial cells isolated from the mammary glands of pregnant and lactating rats. 705 35


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