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 properties and structure of Epstein-Barr virus (EBV) DNA are described. The restriction endonuclease maps of the viral genome are presented. Differences in the structure of DNAs from various subtypes of EBV and their influence on the phenotype status are discussed.
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PMID:[Structural organization of the Epstein-Barr virus genome]. 620 94

The NC37-R1 cell line, established after transformation of human cord blood lymphocytes with Epstein-Barr virus (EBV) recovered from P3HR-1 superinfected NC37 cells, spontaneously produces viral particles with transforming but without early antigen-inducing properties. Progeny virus of NC37-R1 has retained its biological characteristics of spontaneous virus release and transformation up to four cycles of transformation at present. Analysis of purified NC37-R1 virion DNA, after cleavage with restriction endonuclease Hind III and comparison of its fragments with P3HR-1 EBV as well as intracellular NC37 viral DNA using the blot hybridization technique, suggests that NC37-R1 originates from a recombination between superinfecting P3HR-1 and endogenous NC37 EBV DNA.
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PMID:NC37-R1 Epstein-Barr virus (EBV): a possible recombinant between intracellular NC37 viral DNA and superinfecting P3HR-1 EBV. 624 34

A continuous lymphoblastoid cell line, IB-4, was established by infection and growth transformation of normal neonatal B lymphocytes with the B95-8 isolate of Epstein-Barr virus (EBV). The IB-4 cells contained the intranuclear antigen, EBNA, but not early antigen, EA. The fragments produced by the digestion of intracellular episomal viral DNA (density, 1.700 to 1.720 g/cm3) with EcoRI restriction endonuclease were identical in size to the A, B, C, E, F, G, and H fragments of virion DNA. As expected from the previous observation that episomal intracellular DNA is circular, the fragment containing the rightward terminal sequences of EBV DNA in IB-4 cells was larger than the corresponding fragment of linear viral DNA, probably as a consequence of covalent linkage to the leftward terminal fragment. Also, two fragments, EcoRI-I and -J, which were adjacent to each other in the virion DNA, were absent from the intracellular DNA. The labeled EcoRI-J of viral DNA hybridized instead to a new fragment equal in size to EcoRI-I and -J combined. Analysis of viral RNA in IB-4 cells showed that RNAs encoded by more than 30% of the viral DNA comprised approximately 0.06% of the nuclear RNA, whereas RNAs encoded by 20% and 10% of the viral DNA comprised approximately 0.06% and 0.003% of the polyadenylated and polyribosomal RNAs, respectively. Viral mRNA (polyribosomal RNA) was encoded by DNA which mapped at 0.05 x 10(8) to 0.36 x 10(8) daltons and to a lesser extent by DNAs which mapped at 0.62 x 10(8) to 0.67 x 10(8), 0.70 x 10(8) to 0.73 x 10(8), and 1.13 x 10(8) to 1.15 x 10(8) daltons in the B95-8 genome. The most agundant nuclear viral RNAs were encoded primarily by DNA which mapped at the same loci; but RNAs encoded by many other fragments of viral DNA could also be detected among nuclear RNAs. Viral mRNA(s) (polyribosomal) was encoded by about 40% of the internal reiteration and by 25% of the BamHI-H fragments which mapped from 0.32 x 10(8) to 0.36 x 10(8) daltons, nuclear RNAs were encoded by at least 57% of the internal reiteration and 40% of BamHI-H. These data indicate that there is selective accumulation of some viral RNAs within the nucleus of IB-4 cells and that there is selective post-transcriptional processing of these RNAs. Finer mapping of the DNA which encodes mRNA (polyribosomal) in IB-4 cells indicated that some of this DNA is deleted in the DNA of the P3 HR-1 virus, the only isolate of EBV which cannot initiate growth transformation. These data, therefore, support the hypothesis that expression of this region of EBV genome is important for growth transformation or for the maintenance of restrigent infection.
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PMID:Epstein-Barr virus RNA. V. Viral RNA in a restringently infected, growth-transformed cell line. 625 74

DNA from the B95-8 strain of Epstein-Barr virus was cleaved into 29 different fragments by BamHI endonuclease (EC 3.1.23.6). All of the fragments except the terminal fragments have been inserted into the pBR322 cloning vector and replicated in Escherichia coli. The location of each cloned DNA fragment in the viral genome has been determined, providing a more detailed physical map of the genome than has been available previously.
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PMID:Cloning and mapping of BamHi endonuclease fragments of DNA from the transforming B95-8 strain of Epstein-Barr virus. 625 94

An endonuclease has been isolated from human B lymphoblastoid cells that copurifies with an exonucleolytic activity and has been shown to produce double-strand breaks and a high proportion of single-strandedness in phage lambda DNA in vitro. The data are consistent with a model in which single-strand cuts are made by the endonucleolytic activity, possibly in A+T-rich regions of the DNA, followed by creation of single-stranded regions (gaps) precessing from the site of a cut. Generation of overlapping gaps on opposite strands or of a gap opposite a nick would lead to the creation of the banding patterns that we have seen on electrophoretic gels. This endonucleolytic activity copurifies with other enzymes induced by Epstein-Barr virus that relate to the process of viral DNA replication in productively infected cells. However, a more general role is proposed for this class of eukaryotic endonuclease activities. A marked degree of single-strandedness has been found in the replicating DNAs of many eukaryotes, ad these gaps could be generated by endonucleases with associated exonucleolytic activity such as that reported here. This Epstein-Barr virus-induced nuclease activity has been shown to resemble the recBC nuclease isolated from the prokaryote Escherichia coli and also the endonuclease isolated from the eukaryote Chlamydomonas.
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PMID:An endonuclease isolated from Epstein-Barr virus-producing human lymphoblastoid cells. 625 79

EcoRI, HindII, SalI, nd XbaI restriction endonuclease maps of herpesvirus papio (HVPapio) DNA were derived by determining the fragment sizes and the linkage relationships between fragments generated by the different enzymes. The data indicate that HVPapio DNA has a single molecular arrangement which is similar to that of Epstein-Barr virus DNA. The size of the DNA was 110 X 10(6) to 114 X 10(6) daltons. Restriction fragments from both ends varied in the number of repeats of a 4 X 10(5)-dalton sequence, TR, and hybridized to each other. This suggests that there is an identical repeating unit, TR, at both ends of the DNA. There were usually six tandem repetitions (range, 1 to 11) of a 2 X 10(6)-dalton sequence, IR, within the DNA. IR separated the DNA into two domains of largely unique sequence complexity, a 9 X 10(6)-dalton segment, Us, and an 88 X 10(6)-dalton segment, UL. There was homology between DNA fragments which mapped at 25 X 10(6) to 29 X 10(6) to 91 X 10(6) to 95 X 10(6) daltons in UL.
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PMID:Herpesvirus papio DNA is similar in organization to Epstein-Barr virus DNA. 626 Oct 14

A comparative analysis of three Epstein-Barr virus DNAs from American patients with infectious mononucleosis (B95-8, Cherry, and Lamont) and four Epstein-Barr virus DNAs from African patients with Burkitt lymphoma (AG876, W91, Raji, and P3HR-1) indicated that the usual format of Epstein-Barr virus DNA includes a variable number of direct repeats of a 0.35 X 10(6)-dalton sequence (TR) at both ends of the DNA, a 9 X 10(6)-dalton sequence of largely unique DNA (Us), a variable number of repeats of a 2 X 10(6)-dalton sequence (IR), and a 89 X 10(6)-dalton sequence of largely unique DNA (UL). Within UL there was homology between DNA at 26 X 10(6) to 28 X 10(6) daltons and DNA at 93 X 10(6) to 95 X 10(6) daltons. The relative sequence order (TR, US, IR, UL, TR) did not vary among "standard" Epstein-Barr virus DNA molecules of each isolate. B95-8 DNA had an unusual deletion extending from 91 X 10(6) to 100 X 10(6) daltons, and P3HR-1 DNA had an unusual deletion extending from 23.5 X 10(6) to 26 X 10(6) daltons. There was sufficient variability among the EcoRI and BamHI fragments of the DNAs to identify each isolate specifically. However, we discerned no distinguishing features for the two geographic or pathogenic origins of the seven isolates. Three intracellular DNAs (Raji, Lamont, and Cherry) and one virion DNA (P3HR-1) were heterogenous in molecular organization and had subpopulations of rearranged or defective molecules. Some regions, particularly 59 X 10(6) to 63 X 10(6) daltons and sequences around TR, frequently participated in rearrangements. Restriction endonuclease maps of the standard and rearranged DNAs of the seven isolates are presented.
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PMID:Epstein-Barr virus DNA. IX. Variation among viral DNAs from producer and nonproducer infected cells. 626 34

Epstein-Barr viral (EBV) DNA is nearly always detectable in African Burkitt's lymphoma (BL) but is infrequently found in the histologically indistinguishable American BL. We have derived a tumor cell line from a patient with American BL which produces EBV, and we have compared this virus isolate [JLP(c)] with African BL EBV. The American JLP(c) virus immortalizes human umbilical cord lymphocytes in vitro, and its DNA is indistinguishable from African BL EBV DNA by nucleic acid hybridization and preliminary restriction endonuclease cleavage analysis.
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PMID:Characterization of the Epstein-Barr virus isolated from a cell line derived from a patient with American Burkitt's lymphoma. 626 76

A complete collection of fragments of Epstein-Barr virus DNA, obtained by cleavage with restriction endonuclease Eco RI, has been cloned. Fourteen different internal fragments of the virus genome, derived from linear virion DNA of the B95-8 strain, and sequences corresponding to the terminal regions of virion DNA, derived from intracellular circular EBV DNA isolated from 895-8 cells, were cloned. Sizes of fragments were determined by agarose gel electrophoresis and their sum leads to an estimated molecular weight of 110 x 10(6) for virion DNA. Large Eco RI DNA fragments of special interest were also cloned in cosmids using another source of EBV DNA, that is, to circular viral DNA derived from Raji cells. In order to provide a set of overlapping sequences, all the 29 internal Bam HI fragments of B95-8 virion DNA were cloned in pBR322. The map location within the viral genome of each cloned DNA fragment was identified by hybridizing to blots of virion DNA cleaved with several different restriction endonucleases.
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PMID:Molecular cloning of the complete Epstein-Barr virus genome as a set of overlapping restriction endonuclease fragments. 626 68

Cytoplasmic RNA prepared from five lymphoid cell lines and a Burkitt lymphoma biopsy was radioactively labeled in vitro and hybridized to cloned EcoRI restriction endonuclease fragments of B95-8 Epstein-Barr virus DNA. The results confirmed that the most abundant cytoplasmic RNA species in such cells is specified by a small region of the genome defined by the EcoRI J fragment. Detailed mapping experiments precisely localized these transcripts within the sequence of the rightmost one-third of the EcoRI J fragment. DNA sequencing suggested that this region of the Epstein-Barr virus genome is unable to code for protein. The major early transcripts consisted of two non-polyadenylated RNA species, each about 170 nucleotides in length. They were both transcribed off the same strand of the DNA and showed significant sequence homology with each other. The coding sequences of the two small RNAs contained potential intragenic control regions for RNA polymerase III.
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PMID:Characterization of the major Epstein-Barr virus-specific RNA in Burkitt lymphoma-derived cells. 628 55


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