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:3.1.30.2 (endonuclease)
18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Apoptosis is a distinct form of cell death characterized by internucleosomal cleavage of DNA, cell membrane blebbing, condensation of nuclear chromatin in the nuclear periphery, and the formation of apoptotic, condensed nuclear bodies. The finding of internucleosomal cleavage of chromatin, perhaps caused by endonuclease activation, has become accepted as a hallmark of this form of cell death. We describe the incidental and artifactual finding of internucleosomal cleavage of chromatin from kidney tissue from normal animals. Nephrectomy was performed in living animals, and renal tissue was digested with proteinase K in 10 mmol/L Tris, 1 mmol/L ethylenediaminetetraacetic acid (EDTA), 10 mmol/L NaCl, and 0.5% sodium dodecyl sulfate. Agarose gel electrophoresis of extracted DNA showed internucleosomal cleavage. Internucleosomal cleavage of DNA was not tissue specific but was evident also in liver DNA from a number of animals. Histologic examination of kidney tissue where DNA exhibited internucleosomal cleavage showed normal morphology, with no evidence of either apoptotic or necrotic cell death. Cleavage was not completely prevented by immediate freezing of kidney tissue in liquid nitrogen before DNA extraction, nor was it prevented by the addition of spermidine, of ethyleneglycol-bis-(beta-aminoethylether)-N,N,N',N'-tetraace tic acid, of phenylmethylsulfonylfluride, or by an increased concentration of NaCl to 100 mmol/L in the digestion buffer. Internucleosomal cleavage of DNA was mostly, although not invariably, inhibited by the use of a digestion buffer containing 10 mmol/L Tris, 25 mmol/L EDTA, and 100 mmol/L NaCl. "Apoptotic" chromatin changes (internucleosomal fragmentation) are not always associated with histologic evidence of apoptosis and may occur artifactually.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Internucleosomal cleavage of DNA as the sole criterion for apoptosis may be artifactual. 803 5

In the process of developing a gene transfer system for the marine, unicellular, nitrogen-fixing cyanobacterium Cyanothece sp. strain BH68K, two major restriction barriers have been identified. A cell wall-associated nuclease exhibited non-site-specific degradation of covalently closed circular and linear double-stranded DNA molecules, including Cyanothece sp. strain BH68K chromosomal DNA. The nuclease is easily released from intact cells by using water or buffer containing Triton X-100. Nuclease activity was undetectable in cell extracts prepared from water-washed cells. Comparison of the restriction endonuclease susceptibility of Cyanothece sp. strain BH68K DNA to that of Anabaena sp. strain PCC 7120 revealed that these organisms have a nearly identical pattern of restriction and therefore may contain similar systems for DNA methylation. Restriction by DpnI, MboI, and Sau3AI indicated the presence of adenine methylation. Cyanothece sp. strain BH68K cell extracts contain a type II restriction endonuclease, Csp68KI. The activity of Csp68KI was easily detected in cell extracts without extensive purification. Csp68KI is an isoschizomer of AvaII and recognizes the nucleotide sequence 5'-GG(A/T)CC-3'. Cleavage occurs between the guanosine nucleotides producing 3-bp 5' overhang ends.
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PMID:Identification of a nuclease and host restriction-modification in the unicellular, aerobic nitrogen-fixing cyanobacterium Cyanothece sp. 807 Dec 41

Four Burkholderia cepacia strains isolated from the rhizosphere and pathological samples of infected human patients were characterized at the molecular level by different methodologies, including the determination of 16S ribosomal rDNA sequence, restriction endonuclease analysis of total DNA, random amplified polymorphic DNA fingerprinting and Southern hybridization with gene probes for nitrogen fixation and siderophore synthesis. The results indicate that the four strains cluster together within genus Burkholderia, but differ from one another. The DNA from the four strains hybridized to the nifA gene probe from Klebsiella pneumoniae, and an appreciable homology with the nifHDK structural genes of Azospirillum brasilense was demonstrated for one rhizosphere strain. Although the four isolates produced an ornibactin-like siderophore, they did not give hybridization with the pvdA probe for hydroxamate biosynthesis from Pseudomonas aeruginosa.
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PMID:Molecular characterization of rhizosphere and clinical isolates of Burkholderia cepacia. 857 94

Ionizing radiation and other free radical-generating systems induce a great variety of oxidative damage to DNA bases. The major known lesions are repaired by two well-characterized DNA glycosylases of Escherichia coli, endonuclease III (Nth) and formamidopyrimidine-DNA glycosylase (Fpg), which have associated AP lyase activities. To detect and characterize potentially harmful oxidative base DNA lesions that may be repaired by alternative means, we exposed plasmid DNA to low doses of gamma-rays and removed the major base lesions by treatment with Nth and Fpg proteins. The closed circular DNA remaining after these treatments was used as a substrate of the UvrABC endonuclease complex from E. coli and as a template in a DNA polymerase arrest assay in vitro. The circular DNA contained lesions that were recognized and incised by the UvrABC nuclease and also lesions that blocked DNA polymerization in vitro. The blocking lesions were more abundant in DNA irradiated under nitrogen than under air and occurred mainly at tandem guanines; however, they were also frequent at tandem adenines and tandem cytosines.
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PMID:DNA base damage induced by ionizing radiation recognized by Escherichia coli UvrABC nuclease but not Nth or Fpg proteins. 878 61

The human (h) protein hormones, growth hormone (hGH-N) and prolactin (hPRL), are mainly produced in the pituitary, whereas the human placenta expresses the other four members of the protein hormone gene family, designated placental lactogens (PL-A, PL-B, PL-L) and growth hormone variant (GH-V), GH-N stimulates somatic growth, supports nitrogen-, phosphate- and potassium retention and promotes lipolytic and anabolic metabolism, whereas PRL acts on the mammary gland and induces mammogenesis, lactogenesis and galactopoesis. Both hyperprolactinemia and growth hormone deficiency affect the onset of puberty and reproduction in man and mice. In addition to the glycoprotein hormones, these hormones play a role in the maintenance of testicular function. Our group previously demonstrated eutopic production of glycoprotein hormones hLH (human luteinizing hormone) and hCG (human chorionic gonadotropin) in the testis. We have now extended our investigations to the local testicular expression of protein hormones. By means of the molecular biology techniques of the reverse transcription-polymerase chain reaction (RT-PCR), Southern blot and by restriction endonuclease analyses of the generated PCR products we demonstrated the eutopic expression of genes coding for the protein hormones. GH-N gene transcripts were detected only in the pituitary and abundant PL-A/B and a few GH-V gene transcripts were demonstrable in the placenta. In contrast, in the testis GH/PL and PRL genes are transcribed. Since testicular protein hormone gene expression is rather low, these hormones may act locally and not as systemic factors; they presumably modulate the LH/CG-mediated testosterone biosynthesis and/or may act on the spermatogenesis.
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PMID:[The testis as eutopic production site of human growth hormone, placental lactogen and prolactin: possible autocrine/paracrine effects on testicular function]. 899 85

The site-specific endonuclease AbaI was isolated and purified to functional purity from the soil nitrogen-fixing bacterium Azospirillum brasilense UQ 1796. Purification included successive chromatography on columns with phosphocellulose, heparin-Sepharose, and hydroxyapatite. The purified enzyme recognizes the palindromic DNA sequence 5'-T decreases ATCA-3' and cleaves it as shown by the arrow. The isolated enzyme belongs to class II restriction endonuclease and is an isoschizomer of endonuclease BclI. The enzyme of AbaI is active at 26-56 degrees C. The optimal temperature is 48 degrees C and the optimal buffer is LRB.
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PMID:Site-specific endonuclease AbaI from Azospirillum brasilense UQ 1796 is an isoschizomer of endonuclease BclI. 927 72

The presence of endophytic Acetobacter diazotrophicus was tested for pineapple plants (Ananas comosus [L.] Merr.) grown in the field. Diazotrophic bacteria were isolated from the inner tissues of surface sterilized roots, stems, and leaves of pineapple plants. Phenotypic tests permitted the selection of presumptive nitrogen-fixing A. diazotrophicus isolates. Restriction fragment length polymorphisms (RFLPs) of small subunit (SSU) rDNA using total DNA digested with endonuclease SphI and with endonuclease NcoI, hybridizations of RNA with an A. diazotrophicus large subunit (LSU) rRNA specific probe, as well as patterns in denaturing protein electrophoresis (SDS-PAGE) and multilocus enzyme tests allowed the identification of A. diazotrophicus isolates. High frequencies of isolation were obtained from propagative buds that had not been nitrogen-fertilized, and lower frequencies from 3-month-old plants that had been nitrogen-fertilized. No isolates were recovered from 5- to 7-month-old nitrogen-fertilized plants. All the A. diazotrophicus isolates recovered from pineapple plants belonged to the multilocus genotype which shows the most extensive distribution among all host species previously analyzed. </hea
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PMID:Natural Endophytic Occurrence of Acetobacter diazotrophicus in Pineapple Plants. 1079 May 17

Cells of Geobacter metallireducens, Magnetospirillum strain AMB-1, Magnetospirillum magnetotacticum and Magnetospirillum gryphiswaldense showed N2-dependent growth, the first anaerobically with Fe(III) as the electron acceptor, and the latter three species microaerobically in semi-solid oxygen gradient cultures. Cells of the Magnetospirillum species grown with N2 under microaerobic conditions were magnetotactic and therefore produced magnetosomes. Cells of Geobacter metallireducens reduced acetylene to ethylene (11.5+/-5.9 nmol C2H4 produced min(-1) mg(-1) cell protein) while growing with Fe(III) as the electron acceptor in anaerobic growth medium lacking a fixed nitrogen source. Cells of the Magnetospirillum species, grown in a semi-solid oxygen gradient medium, also reduced acetylene at comparable rates. Uncut chromosomal and fragments from endonuclease-digested chromosomal DNA from these species, as well as Geobacter sulphurreducens organisms, hybridized with a nifHDK probe from Rhodospirillum rubrum, indicating the presence of these nitrogenase structural genes in these organisms. The evidence presented here shows that members of the metal-metabolizing genera, Geobacter and Magnetospirillum, fix atmospheric dinitrogen.
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PMID:N2-dependent growth and nitrogenase activity in the metal-metabolizing bacteria, Geobacter and Magnetospirillum species. 1120 Apr 27

The conformation of N-(deoxyguanosin-8-yl)-2-acetylaminofluorene and N-(deoxyguanosin-8-yl)-2-aminofluorene was investigated by 1H n.m.r. spectroscopy. There was rotation about the glycosyl bond and preference for either the anti or syn conformation depended on whether or not the 8-arylamino nitrogen was acetylated. The unacetylated adduct existed preferentially in the anti form and the acetylated adduct existed preferentially in the alternate syn form. There was also rotation about the backbone C4' -C5' bond. The unacetylated adduct was mainly in the gauche-gauche conformation about C4'-C5', while the acetylated adduct was mainly in the alternate gauche-trans/trans-gauche form. Using space filling models with the conformation of the unacetylated adduct conserved in the helix, a possible structure of modified DNA was proposed which had less perturbation of the helix than that of the acetylated adduct. This was consistent with single strand endonuclease hydrolysis data. The acetylated and unacetylated adducts may cause entirely different types of local conformational changes in DNA because of major differences in interactions between the base and the sugar moiety at the modified nucleoside level.
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PMID:Sensitivity of the conformation of deoxyguanosine to binding at the C-8 position by N-acetylated and unacetylated 2-aminofluorene. 1121 50

A novel method is proposed for large-scale synthesis of (13)C- and (15)N-labeled DNA for NMR studies. In this methodology, endonuclease-sensitive repeat amplification (ESRA), a modified PCR strategy, has been used to amplify tandem repeats of the target DNA sequence. The design of the template is such that restriction enzyme (RE) sites separate repeats of the target sequence. The ESRA product is then cloned into a suitable vector. The Escherichia coli cells harboring the plasmid are grown in minimal medium containing [(13)C]glucose and (15)NH(4)Cl as the sole source of carbon and nitrogen, respectively. The target sequence is released by RE digestion of the plasmid, followed by purification using PAGE. Under optimized conditions, the yield ( approximately 5 mg/liter of culture) of (13)C/(15)N-labeled DNA prepared using this approach is found to be several times higher compared to other known enzymatic methods. Successful incorporation of the isotopes has been confirmed using 2D NMR techniques.
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PMID:A novel approach for uniform (13)C and (15)N labeling of DNA for NMR studies. 1179 62


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