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)

The positions of the several sea urchin histone genes on the eukaryotic fragments of the chimeric plasmids pSp2 and pSp17 have been mapped relative to the Eco RI and Hind III restriction endonuclease sites on the plasmids. Two principal mapping methods using the electron microscope have been used: (a) the R-loop procedure and a new modification thereof to map the genes on duplex DNA; (b) the gene 32-ethidium bromide technique to visualize RNA-DNA hybrids on single strands of DNA. It is known that there are two histone genes, H3 and H2A, on pSp17. There are two Eco RI sites at the two junctions of the procaryotic segment with the eucaryotic segment on the plasmid. We show, by an electron microscope method, that for H2A, with a length of 0.52 kilobases (kb), one end of the gene is situated 0.02 to 0.03 kb from one RI site, and that there is a Hind III site within this gene at about 0.13 kb from the end phe other RI site of this plasmid. The H4 gene lies between H2B and H1. The ms the incubation temperature is raised up to a temperature just below that at which strand dissociation of the duplex DNA occurs.
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PMID:Positions of sea urchin (Strongylocentrotus purpuratus) histone genes relative to restriction endonuclease sites on the chimeric plasmids pSp2 and pSp17. 32 Oct 20

We have analyzed the histone genes from the sea urchin Lytechinus pictus. Examination of native DNA from individuals reveals four major Eco RI restriction endonuclease histone gene DNA fragments which have been labeled A (6.0 kb), B (4.1 kb), C (3.1kb) and D (1.2 kb). The fragments A, B and C have been cloned into E. coli plasmids (pLpA, pLpB and pLpC). These histone gene fragments display length and sequence heterogeneity in different individuals. The plasmid pLpA contains the coding regions for H1, H4, H2B and H3 histones, and we determined that the DNA fragment D is tandem to A in native DNA and that it contains the H2A gene. The plasmids pLpB and pLpC contain the histone genes H2A-H1-H4 and H2B-H3, respectively, and together contain the sequences for the five major histones. Restriction analysis of native L. pictus DNA reveals that B and C are tandem to each other but not intermingled with the A--D-type repeat units, and are thus in separate clusters with a repeat length of 7.2 kb. Since the two cluster types do not segregate, they are not alleles. Hybridization of histone mRNA to exonuclease III-digested linear DNA demonstrated an identical polarity of the histone genes in the A--D- and B--C-type repeat units. This result revealed that the L. pictus histone genes have a polarity which is the same as other sea urchin histone genes examined to date--that is, 3' H1-H4-H2B-H3-H2A 5'. Restriction endonuclease cleavage patterns of the cloned segments indicate that considerable sequence heterogeneity exists between the two types of histone gene repeat units.
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PMID:Nonallelic histone gene clusters of individual sea urchins (Lytechinus pictus): polarity and gene organization. 51 57

Herpes simplex type 1 (HSV-1) and type 2 (HSV-2) isolates from genital and nongenital infections were submitted to restriction endonuclease analysis for possible genomic changes in relation with the adaptation of the virus to a new site on the body. HSV-1 and HSV-2 strains were successfully divided into two subgroups using the Hin c II restriction enzyme. No correlation was found, however, between the proposed genomic subtypes H1A, H1B, H2A and H2B, and the genital or nongenital origin of the HSV strains.
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PMID:Restriction endonuclease patterns of herpes simplex virus DNA: subtyping of HSV-1 and HSV-2 strains from genital and nongenital lesions. 164 30

Large amounts of histones, H1, H2A, H2B, H3, and H4, were observed in total extracts of T4 lymphocytes and derived cell lines infected with the human immunodeficiency virus (HIV) type 1 or type 2. These histones were simply detectable by analysis of crude cellular extracts by polyacrylamide gel electrophoresis in SDS and staining the proteins with Coomassie blue or by immunoblot assays using specific polyclonal antibodies. The histones were found to be localized in the nucleoplasm, bound to low molecular weight (LMW) DNA in the form of nucleosomes. The mechanism responsible for the accumulation of nucleosomes during HIV infection was found to be due to fragmentation of cellular DNA, a mechanism referred to as apoptosis or programmed cell death in which a nuclear endonuclease becomes activated and cleaves DNA at internucleosomal regions. Accordingly, the LMW DNA accumulated in the course of infection was found to have a characteristic pattern of nucleosomal ladder and its accumulation was reduced in the presence of zinc, a known inhibitor of the endonuclease. Routinely in acute HIV infections, the accumulation of nucleosomes was observed at least 24 hr before lysis of infected cells. In a particular HIV-1 infection, in which the first signals of the cytopathic effect (vacuolization of cells and appearance of syncytia) was observed at Days 6-7 whereas maximal virus production occurred at Days 10-17, the accumulation of nucleosomes was at its maximal level already on Day 6 postinfection. In the nucleoplasm of chronically infected cells producing virus but not manifesting a cytopathic effect, no LMW DNA or histones were detectable. These observations indicate that the cytopathic effect of HIV infection is associated with apoptosis. The detection of histones and oligonucleosomal DNA fragments in the nucleoplasm can be used as a convenient marker for chromatin fragmentation during this process.
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PMID:The cytopathic effect of HIV is associated with apoptosis. 168 28

The influence of nucleosome structure on the activity of 2 chromatin-associated DNA endonucleases, pIs 4.6 and 7.6, from normal human and xeroderma pigmentosum, complementation group A (XPA), lymphoblastoid cells was examined on DNA containing either psoralen monoadducts or cross-links. As substrate a reconstituted nucleosomal system was utilized consisting of a plasmid DNA and either core (H2A, H2B, H3, H4), or total (core plus H1) histones from normal or XPA cells. Both non-nucleosomal and nucleosomal DNA were treated with 8-methoxypsoralen (8-MOP) plus long-wavelength ultraviolet radiation (UVA), which produces monoadducts and DNA interstrand cross-links, and angelicin plus UVA, which produces monoadducts. Both normal endonucleases were over 2-fold more active on both types of psoralen-plus-UVA-damaged core nucleosomal DNA than on damaged non-nucleosomal DNA. Addition of histone H1 to the system reduced but did not abolish this increase. By contrast, neither XPA endonuclease showed any increase on psoralen-treated nucleosomal DNA, with or without histone H1. Mixing the normal with the XPA endonucleases led to complementation of the XPA defect. These results indicate that interaction of these endonucleases with chromatin is of critical importance and that it is at this level that a defect exists in XPA endonucleases.
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PMID:Chromatin-associated DNA endonucleases from xeroderma pigmentosum cells are defective in interaction with damaged nucleosomal DNA. 230 93

The influence of nucleosomes on the activity of two chromatin-associated apurinic/apyrimidinic (AP) DNA endonuclease activities, pIs 9.2 and 9.8, from normal and xeroderma pigmentosum, complementation group A (XPA), lymphoblastoid cells was examined. These AP endonuclease activities were studied on non-nucleosomal and nucleosomal plasmid pWT830/pBR322 DNA which had been reconstituted with core (H2A, H2B, H3, H4) or total (core plus H1) histones from normal or XPA cells. Both nucleosomal and non-nucleosomal DNA was rendered partially AP by alkylation with 12.5 mM methyl methanesulfonate, followed by heating it at 70 degrees C, to produce approximately three AP sites per DNA molecule. The activities of both normal lymphoblastoid AP endonuclease activities on nucleosomal AP DNA, reconstituted with core histones, was approximately 2.5 times greater than that on non-nucleosomal AP DNA. When histone H1 was added to the system, this increase was reduced. XPA AP endonuclease activities, on the other hand, did not show any increase in activity on nucleosomal AP DNA reconstituted with core histones. These differences between normal and XPA endonuclease activities on AP nucleosomal DNA were the same regardless of whether histones from normal or XPA cells were used in the reconstituted system.
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PMID:Enhancement of two apurinic/apyrimidinic endonuclease activities from normal but not xeroderma pigmentosum lymphoblastoid cells by nucleosome structure. 242 53

We have previously shown that transcript levels expressed from the yeast TMP1 gene fluctuate periodically during the yeast cell cycle. However, it was not known whether periodic expression resulted from a regulatory mechanism acting at the level of transcription or a regulatory mechanism acting at the level of cell cycle stage-dependent changes in the stability of the TMP1 transcript. In this report we now show that the periodic expression of TMP1 transcript is primarily controlled at the level of its transcription by sequences which are upstream of its transcription initiation sites. We also localized the upstream sequences necessary for periodic transcription to a 150-base-pair region and show that this region encodes an element(s) with the properties of a periodic upstream activating sequence. The regulatory region defined in this study apparently does not contain consensus sequences similar to those reported for the cell cycle-regulated HO endonuclease or for the histone H2A and H2B genes of Saccharomyces cerevisiae.
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PMID:Transcriptional regulation of the cell cycle-dependent thymidylate synthase gene of Saccharomyces cerevisiae. 306 62

The histones isolated from the siliceous sponge Geodia cydonium have been separated using two electrophoretic techniques. A comparison of their mobilities with those of calf thymus and rat liver show that some Geodia histone species (H3, H1 and H1(0) exhibit electrophoretic variance. The results show, that as in other eukaryotic systems the sponge chromatin contains the core histones (H2A, H2B, H3 and H4) and the linker histone (H1). ADP-ribosylation of Geodia histones and separation of the individual histones by electrophoresis resulted in four histones being radiolabeled. Digestion of Geodia chromatin with endogenous endonuclease is shown to result in the formation of nucleosome particles containing approximately 200 base pairs of DNA. A major product of endogenous endonuclease digestion is a relatively stable 110 base pair intermediate. Incubation of chromatin with DNase II and separation of the products under denaturing conditions reveals 20 bands migrating at 10 base intervals.
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PMID:Chromatin structure from the marine sponge Geodia cydonium. 631 75

The activity of purified Ca2+, Mg2+-dependent endonuclease was inhibited when the enzyme was incubated in a system containing poly(ADP-ribose) synthetase, NAD+, Mg2+, and DNA. All four ingredients were essential to mediate ADP-ribosylation and to demonstrate inhibition of the endonuclease. In the absence of Mg2+, ADP-ribose transferring activity of poly(ADP-ribose) synthetase was stimulated by the addition of purified endonuclease to the reaction mixture in a dose-dependent manner. Analysis of the reaction product showed that the endonuclease was ADP-ribosylated. The average chain length of the initial oligo(ADP-ribose) attached to the enzyme was about 5.9 residues. The oligomer was found to be extensively elongated during the chase experiment using unlabeled NAD+ and Mg2+. The present finding suggests that Mg2+ is essential for the extensive elongation of the oligo(ADP-ribose). The DNA-binding affinity of the modified endonuclease was significantly lower than that of unmodified enzyme. Also, free poly(ADP-ribose) was not an effective inhibitor of the endonuclease. These findings suggest that the observed inhibition of the endonuclease induced by ADP-ribosylation is probably due to an electrostatic repulsion between the substrate (DNA) and poly(ADP-ribose) covalently linked to the endonuclease. Histone H1 and H2B stimulated endonuclease activity and were acceptors of ADP-ribose; however, their capacity to stimulate endonuclease activity remained unchanged after ADP-ribosylation.
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PMID:Mechanism of the inhibition of Ca2+, Mg2+-dependent endonuclease of bull seminal plasma induced by ADP-ribosylation. 632 87

We have investigated protein-DNA interactions in the proximal promoter of the human amyloid precursor protein (APP) gene in temporal lobe neocortical nuclei isolated from control and Alzheimer disease (AD) affected brains. We report that the human APP 5' promoter sequence from -203 to +55 bp, which has been previously reported to contain essential regulatory elements for APP gene transcription, lies in a deoxyribonuclease I, micrococcal nuclease- and restriction endonuclease-sensitive, G+C-rich nucleosome-free gap flanked both 5' and 3' by typical nucleosome structures. As analyzed by electrophoretic mobility shift assay, this extended internucleosomal linker DNA is heavily occupied by nuclear protein factors, and interacts differentially with nuclear protein extracts obtained from HeLa and human brain neocortical nuclei. This suggests that the chromatin conformation of the APP gene promoter may vary in different cell types, and may correlate with differences in APP gene expression. Human recombinant transcription factors AP1, SP1 and TFIID (but not AP2 or brain histones H1, H2B and H4) interact with the -203 to +55 bp of the human APP promoter sequence. Only minor differences were observed in the chromatin structure of the immediate APP promoter between non-AD and AD affected neocortical nuclei, suggesting either that post-transcriptional processes, or that regulatory elements lying elsewhere in the APP gene may be important in the aberrant accumulation of the APP gene product.
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PMID:Protein-DNA interactions in the promoter region of the amyloid precursor protein (APP) gene in human neocortex. 801 72


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