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 two Epstein-Barr virus (EBV) types, EBV-1 and EBV-2, are known to differ in their EBNA-2 genes, which are 64 and 53% identical in their nucleotide and predicted amino acid sequences, respectively. Restriction endonuclease maps and serologic analyses detect few other differences between EBV-1 and EBV-2 except in the EBNA-3 gene family. We determined the DNA sequence of the AG876 EBV-2 EBNA-3 coding region and have compared it with known B95-8 EBV-1 EBNA-3 sequences to delineate the extent of divergence between EBV-1 and EBV-2 isolates in their EBNA-3 genes. The B95-8 and AG876 EBV isolates had nucleotide and amino acid identity levels of 90 and 84%, 88 and 80%, and 81 and 72% for the EBNA-3A, -3B, and -3C genes, respectively. In contrast, nucleotide sequence identity in the noncoding DNA adjacent to the B95-8 and AG876 EBNA-3 open reading frames was 96%. We used the polymerase chain reaction to demonstrate that five additional EBV-1 isolates and six additional EBV-2 isolates have the type-specific differences in their EBNA-3 genes predicted from the B95-8 or AG876 sequences. Thus, EBV-1 and EBV-2 are two distinct wild-type EBV strains that have significantly diverged at four genetic loci and have maintained type-characteristic differences at each locus. The delineation of these sequence differences between EBV-1 and EBV-2 is essential to ongoing molecular dissection of the biologic properties of EBV and of the human immune response to EBV infection. The application of these data to the delineation of epitopes recognized in the EBV-immune T-cell response is also discussed.
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PMID:Epstein-Barr virus types 1 and 2 differ in their EBNA-3A, EBNA-3B, and EBNA-3C genes. 216 6

Epstein-Barr virus (EBV) is often associated with lethal lymphoproliferative diseases in immunologically compromised individuals. Recently, we have studied a 20-month-old boy with X-linked lymphoproliferative disease (XLP) who had succumbed to infectious mononucleosis (IM) complicated by fulminant hepatitis and virus-associated hemophagocytic syndrome following EBV infection. EBV genomes were detected in peripheral blood lymphocytes (PBL), cervical and mesenteric lymph nodes, liver, spleen, thymus, and bone marrow. According to restriction endonuclease analyses, the EBV-DNA pattern was similar in all samples except for the EBV-DNA from the bone marrow. Additionally, circular EBV-DNA (suggesting a latent infection) predominated in spontaneously established lymphoblastoid cell lines (LCLs) derived from both the lymph node and cord lymphocytes co-cultured with PBL. In contrast, both circular and linear EBV-DNA (suggesting a lytic infection) were noted in spontaneously established LCLs derived from his PBL. Furthermore, LCLs derived from both the lymph node and cord lymphocytes co-cultured with PBL expressed fewer reactive cells for early antigen (EA) and viral capsid antigen (VCA) than spontaneous LCLs from his PBL, thus providing evidence for different B cellular susceptibility to EBV infection in this patient with XLP. Finally, defective EBV-specific cytotoxic T cell activity was observed in this patient. Latent EBV infected cells may easily escape immunosurveillance by the host. These findings may explain the fatal course of EBV infection in this patient.
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PMID:Differential cellular susceptibility to Epstein-Barr virus infection in a patient with X-linked lymphoproliferative disease. 217 37

DNA sequence analysis was carried out on the 1-kilobase SacI-EcoRI region of the EcoRI J fragment of four strains of Epstein-Barr virus (EBV) (MABA, P3HR-1, FF41, and NPC-5), and the sequences were compared with the prototype sequence from strain B95-8. Ten single-base changes which grouped the strains into two families (1 and 2) were found. Restriction endonuclease polymorphisms predicted from the sequences were used to classify the EBV DNA from a further 26 EBV-positive cell lines into these two families. The EBNA-2 types (A or B) of the strains were found to correlate with the J region type; EBNA-2 type A DNA regularly contained J region sequence type 1, while EBNA-2 type B DNA generally carried J region sequence type 2. These data are consistent with the notion of there being two distinct families of EBV with discrete, conserved differences in DNA sequence.
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PMID:Two families of sequences in the small RNA-encoding region of Epstein-Barr virus (EBV) correlate with EBV types A and B. 253 22

A recombinant plasmid harboring both genomic termini of tupaia herpesvirus (THV) DNA was characterized by restriction enzyme analysis and by determination of the nucleotide sequence. A unique NotI cleavage site was found that is located approximately 19 base pairs upstream of the THV terminal junction. THV DNA fragments from virion DNA were analyzed by using the same restriction enzymes as for the recombinant plasmid. The comparative fine mapping of virion THV DNA revealed heterogeneous molecules of variable lengths with the NotI cleavage site conserved. A number of short direct and inverted repeats and palindromes were found surrounding the THV terminal joint. The THV repetitive sequences were compared with the repeats reported for the DNA termini of herpes simplex virus, varicella-zoster virus, and Epstein-Barr virus and are discussed in respect to signals for a site-specific endonuclease required for packaging.
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PMID:Analysis of the genomic termini of tupaia herpesvirus DNA by restriction mapping and nucleotide sequencing. 299 69

Three single-stranded oligonucleotide probes, 22 bases long, homologous to unique regions of herpes simplex virus (HSV) types 1 (HSV-1) and 2 (HSV-2) and a region common to both were chemically synthesized with use of a modified phosphochloridite protocol. For hybridization experiments each probe was labeled with use of polynucleotide kinase and [gamma-32P] ATP to a specific activity of approximately 2 X 10(9) cpm/micrograms. Two hundred one clinical isolates of HSV (96 HSV-1 and 105 HSV-2) collected from vesicles in the mucocutaneous junction of the mouth or from the genital area were analyzed. There was a 99% (199 of 201) agreement between hybridization and monoclonal antibody typing; the two discrepant isolates of HSV-2 that were negative by monoclonal antibody typing were confirmed as HSV-2 by restriction endonuclease analysis. The probes detected between 10(4) and 10(5) HSV infectious units and from 150 to 600 HSV-infected Vero cells. No binding was detected between any of the three probes and isolates of cytomegalovirus, Epstein-Barr virus, and varicella-zoster virus.
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PMID:Typing of herpes simplex virus with synthetic DNA probes. 300 36

We have demonstrated the presence of an Epstein-Barr virus (EBV)-coded thymidine kinase (TK) by producing biochemically transformed, TK-positive mammalian cell lines using either microinjection of whole EBV virions or calcium phosphate-mediated transfection of the SalI-B restriction endonuclease fragment of EBV DNA. Analysis of these cell lines showed that: (i) EBV DNA was present in the cell lines, (ii) sequences from the SalI-B restriction endonuclease fragment of EBV were expressed, (iii) a TK activity was present and (iv) a protein with antigenic cross-reactivity with the herpes simplex virus (HSV) TK was produced. The identity of the EBV TK gene was determined by demonstrating that a recombinant plasmid, which expressed the protein product of the BXLF1 open reading frame as a fusion protein, could complement TK- strains of E. coli. A comparison of the predicted amino acid sequences of the TK proteins of EBV and HSV-1 revealed significant regions of homology.
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PMID:Identification of an Epstein-Barr virus-coded thymidine kinase. 301 75

The linear virion form of Epstein-Barr virus (EBV) DNA has variable numbers of direct tandem 500 bp repeats at each terminus. The terminal restriction endonuclease fragments and the fused terminal fragments in the intracellular episomal form are heterogeneous in size, and vary by increments of 500 bp. The structure of the termini of EBV in carcinomas of the nasopharynx and the parotid gland was compared with the EBV termini in monoclonal and polyclonal tissues or cell lines. A single band representing the EBV joined termini was detected in each of the carcinomas and in the monoclonal lymphoid proliferations. Polyclonal cell lines contained multiple forms of the joined termini. The detection of a homogeneous episomal population suggests that EBV-associated epithelial malignancies are clonal expansions of a single EBV-infected progenitor cell.
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PMID:The structure of the termini of the Epstein-Barr virus as a marker of clonal cellular proliferation. 302 42

Mammalian ribonucleotide reductase consists of two nonidentical subunits, proteins M1 and M2, which are differentially regulated during the cell cycle. We have isolated expressible cDNA clones of both subunits from an Okayama-Berg cDNA library made with mRNA from hydroxyurea-resistant, M2 protein-overproducing mouse TA3 cells. Expression of M2 protein could be demonstrated by electron paramagnetic resonance spectroscopy after transfection of COS-7 monkey cells with the plasmid. Electrophoresis and blot analyses of the parent and hydroxyurea-resistant TA3 mRNA revealed two M2 transcripts, a major one of 2.1 kilobases and a minor one of about 1.6 kilobases. Restriction endonuclease mapping of the corresponding cDNAs indicated that the two mRNAs differed only in the length of the 3' untranslated ends. By contrast, there was only one mRNA corresponding to the M1 protein, and its mobility corresponded to about 3.1 kilobases. The hydroxyurea-resistant TA3 cells contained a 50- to 100-fold excess of the M2 mRNAs over that of the parent cells and a 10-fold excess of the M1 mRNA. However, a Southern blot analysis of the corresponding genomic DNA sequences showed that the M2 gene was amplified fivefold but the M1 gene was still single copy. The complete nucleotide sequence of the 2,111-base-pair-long M2 cDNA revealed an open reading frame coding for 390 amino acids, which corresponds to a molecular weight of 45,100. The mouse M2 protein sequence was quite homologous to the equivalent protein in the clam Spisula solidissima, while the homology to the smaller subunits of Epstein-Barr virus, herpes simplex virus type 2, and Escherichia coli ribonucleotide reductases were less pronounced.
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PMID:Isolation and characterization of expressible cDNA clones encoding the M1 and M2 subunits of mouse ribonucleotide reductase. 302 93

The Epstein-Barr virus (EBV) BamHI restriction endonuclease fragment K (B95-8 strain) was introduced into a polyoma virus expression vector and used to transfect murine NIH 3T3 cells. An EBV-associated nuclear antigen was detected in these cells in an indirect immunofluorescence test using anti-EBV nuclear antigen-positive human sera. These sera recognized a Mr 88,000 polypeptide in 3T3 cells transfected with the BamHI fragment K-containing polyoma virus plasmid by radioimmunoelectrophoresis. A Mr 88,000 polypeptide also was detected in a B-cell line latently infected with the B95-8 strain of EBV. Plasmids containing insertion and deletion mutations in BamHI fragment K directed the synthesis of truncated forms of the Mr 88,000 polypeptide in 3T3 cells. These data directly demonstrate that the polypeptide identified in EBV-infected lymphocyte lines by anti-EBV nuclear antigen-positive human sera is encoded by the viral genome.
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PMID:Identification of Epstein-Barr virus sequences that encode a nuclear antigen expressed in latently infected lymphocytes. 608 22

Epstein-Barr virus (EBV) nuclear antigen (EBNA) was purified from the Burkitt lymphoma line Raji and its EBV DNA-binding properties were characterized. EBNA binding protected fragments of about 30 bp of B95-8 cell-derived EBV DNA from an excess of DNase I. Human anti-EBNA antibodies prevented DNA binding. Purified extracts from EBNA-negative cells did not protect EBV DNA against DNase I digestion. Mapping of the EBV DNA fragments protected from endonuclease (EcoRI, HindIII, SalI) digestion revealed many binding sites. Similar results were obtained following mixing of crude cell extracts and HindIII-digested fragments of EBV DNA and subsequent immunoprecipitation of the EBNA-DNA complex. In experiments involving the analysis of EBV DNA, fragments were protected from DNase I digestion by purified EBNA.
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PMID:Interaction between Epstein-Barr virus-determined nuclear antigen (EBNA) and the viral DNA. 609 16


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