Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:BIOD00001 (DNase I)
 8,324 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In cells latently infected with Epstein-Barr virus, the switch from latency to productive infection is linked to the expression of two Epstein-Barr virus transcription factors called EB1 and R. R is an enhancer factor, and an R-responsive element (RRE) has been identified in the BMLF1 promoter. In this study, we have used bidirectional deletion mutagenesis to delineate the BMLF1 RRE (RRE-M) to a 44-bp sequence. We also show that R expressed from a recombinant vaccinia virus protects RRE-M against digestion by DNase I. Using mobility shift assays and dimethyl sulfate interferences, we have characterized the contact points between in vitro-translated R and the DNA. R binds in vitro to one site by simultaneously contacting two sequences within the site, which are separated by 8 bp: 5'-catGTCCCtctatcatGGCGCagac-3'. Site-directed mutagenesis of this sequence completely impaired the binding of R in vitro and rendered the BMLF1 promoter nonresponsive to R. The results suggest that the R-inducible BMLF1 enhancer is composed of a single R-binding site, called RRE-M.
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PMID:Characterization of an R-binding site mediating the R-induced activation of the Epstein-Barr virus BMLF1 promoter. 130 56

ZEBRA is an Epstein-Barr virus (EBV) transcriptional activator that mediates a genetic switch between the latent and lytic states of the virus by binding to the promoters of genes involved in lytic DNA replication and activating their transcription. A computer survey revealed that 9 of 23 potential or known ZEBRA-responsive EBV genes contained two or more upstream binding sites; this suggested that ZEBRA can stimulate transcription synergistically. By using a series of synthetic promoters bearing one, two, three, five, and seven upstream recognition sites, we showed that ZEBRA activates transcription synergistically when templates bearing multiple sites were compared with a template bearing a single site. This phenomenon was observed in both uninfected and EBV-infected B-lymphoid cells and in vitro in a HeLa cell nuclear extract. DNase I footprinting was used to show that the synergy was not due to cooperative DNA binding mediated by direct contact between ZEBRA dimers. The in vitro experiments revealed two manifestations of synergy. One was seen when the levels of transcription observed with the same amounts of ZEBRA added to templates bearing different numbers of sites were compared. The other was observed when the two lowest concentrations of ZEBRA that stimulated measurable transcription from any given template were compared. On the basis of both the number of sites and the calculated Kd of ZEBRA for a single site, we estimated that the critical concentration of ZEBRA needed to elicit transcriptional synergy corresponds to a site occupancy of two or three bound ZEBRA dimers. Our results have biologic implications for both the EBV lytic cycle and other processes in which the concentration of an activator changes either temporally or spatially.
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PMID:Transcriptional synergy by the Epstein-Barr virus transactivator ZEBRA. 132 Dec 70

Eukaryotic transcriptional activators are believed to stimulate transcription through direct and/or indirect interactions with one or more of the general transcription factors. We show here that the Zta transcriptional activator protein encoded by the Epstein-Barr virus makes direct physical contact with the basic transcription factor TFIID. Both Zta and TFIID were expressed in and purified from Escherichia coli. Zta stabilized the binding of TFIID to Zta-responsive promoters as assayed by gel electrophoresis mobility-shift and immunoprecipitation of radiolabeled promoter DNA. A deletion mutant of Zta that failed to activate transcription failed to stabilize TFIID binding. DNase I footprinting showed that Zta reduced the dissociation rate of TFIID bound to the TATA element. Protein blotting and immunoprecipitation experiments demonstrated that TFIID and Zta also interact in the absence of promoter DNA. The amino acid residues 25-86 of Zta were essential for the stable association with TFIID and were shown to be required for trans-activation in vivo. We propose that Zta stimulates transcription, in part, by direct physical contact with the conserved domain of TFIID and the formation of a stable Zta-TFIID-promoter complex.
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PMID:The Zta trans-activator protein stabilizes TFIID association with promoter DNA by direct protein-protein interaction. 166 Dec 58

The specific binding of HeLa cell factors to DNA sequences at the Epstein-Barr virus (EBV) latent origin of DNA replication was detected by gel shift experiments and DNase I footprinting analysis. These cellular proteins protected at least five discrete regions of the DNA replication origin. The viral protein required for EBV plasmid replication, EBV nuclear antigen 1 (EBNA-1), binds to specific sequences within the origin region. The HeLa cell proteins competed with EBNA-1 for binding to EBV origin DNA in vitro, leading to the possibility that these cellular proteins regulate EBV DNA replication by displacing EBNA-1 at the origin sites.
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PMID:Identification of cellular factors that bind specifically to the Epstein-Barr virus origin of DNA replication. 184 5

During latent Epstein-Barr virus (EBV) infection of human B lymphocytes, six viral nuclear antigen (EBNAs) are expressed from long primary transcripts by means of alternative splicing and alternative polyadenylylation sites. These transcripts initiate from one of two promoters, Cp or Wp, that function in a mutually exclusive fashion. Wp is exclusively utilized during the initial stages of infection of primary B lymphocytes, followed by a switch to Cp usage. These studies have been extended to show that (i) a mutant EBV strain lacking the gene encoding EBNA 2 fails to switch from Wp to Cp usage in primary B lymphocytes, although the virus contains a functional Cp; (ii) a region from -429 to -245 base pairs upstream of Cp is essential for Cp activity in B lymphocytes, but only in the context of upstream and downstream sequences; (iii) this region contains an EBNA 2-dependent enhancer; and (iv) DNase I protection employing nuclear extracts from B and T lymphocytes revealed a B-cell-specific footprint in the region of the EBNA 2-dependent enhancer. These results support a model for viral promoter switching during the initial stages of infection in which Wp activity leads to the expression of EBNA 2, followed by activation of Cp through the EBNA 2-dependent enhancer.
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PMID:Role for the Epstein-Barr virus nuclear antigen 2 in viral promoter switching during initial stages of infection. 185 Aug 41

A transcriptional enhancer has been mapped to a region 5.5 kilobases 3' of the C beta 2 gene in the human T-cell receptor (TCR) beta-chain locus. Transient transfections allowed localization of enhancer activity to a 480-base-pair HincII-XbaI restriction enzyme fragment. The TCR beta enhancer was active on both the minimal simian virus 40 promoter and a TCR beta variable gene promoter in both TCR alpha/beta + and TCR gamma/delta + T cells. It displayed significantly less activity in Epstein-Barr virus-transformed B cells and K562 chronic myelogenous leukemia cells and no activity in HeLa fibroblasts. DNA sequence analysis revealed that the enhancer contains a consensus immunoglobulin kappa E2 motif, as well as an AP-1-binding site and a cyclic AMP response element. DNase I footprint analyses using Jurkat T-cell nuclear extracts allowed the identification of five nuclear protein-binding sites, T beta 1 to T beta 5, within the enhancer element. Deletion and in vitro mutagenesis studies demonstrated that the T beta 2- and T beta 3- and T beta 4-binding sites are each required for full transcriptional enhancer activity. In contrast, deletion of the T beta 1- and T beta 5-binding sites had essentially no effect on enhancer function. Electrophoretic mobility shift assays demonstrated that TCR alpha/beta + and TCR gamma/delta + T cells expressed T beta 2-, T beta 3-, and T beta 4-binding activities. In contrast, non-T-cell lines, in which the enhancer was inactive, each lacked expression of at least one of these binding activities. TCR alpha and beta gene expression may be regulated by a common set of T-cell nuclear proteins in that the T beta 2 element binding a set of cyclic AMP response element-binding proteins that are also bound by the T alpha 1 element of the human TCR alpha enhancer and the decamer element present in a large number of human and murine TCR beta promoters. Similarly, the T beta 5 TCR beta-enhancer element and the T alpha 2 TCR alpha-enhancer element bind at least one common T-cell nuclear protein. Taken together, these results suggest that TCR beta gene expression is regulated by the interaction of multiple T cell nuclear proteins with a transcriptional enhancer element located 3' of the C beta 2 gene and that some of these proteins may be involved in the coordinate regulation of TCR alpha and beta gene expression.
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PMID:Identification and functional characterization of the human T-cell receptor beta gene transcriptional enhancer: common nuclear proteins interact with the transcriptional regulatory elements of the T-cell receptor alpha and beta genes. 214 10

A cDNA corresponding to the BGLF5 open reading frame of the Epstein-Barr virus (EBV) genome and coding for an early DNase was inserted into the procaryotic expression vector pKK223-3. One bacterial clone producing the expected 52-kilodalton DNase was used as a source of EBV DNase. The 52-kilodalton Dnase was purified in the active form to near homogeneity by ammonium sulfate precipitation and successive chromatographies on phosphocellulose, DNA-cellulose, and gel filtration columns. The purified enzyme exhibited both exonuclease and endonuclease activities, an absolute requirement for divalent cations, an alkaline pH preference, and a typical residual activity in presence of 300 mM KCl. Moreover, the enzyme was specifically inhibited by human sera with high antibody titers to EBV early antigens. These properties are similar to those observed for EBV-induced DNase from lymphoblastoid cell extracts. In addition, the enzyme was recognized by both immunoglobulin G and A serum fractions from patients with nasopharyngeal carcinoma (NPC). From these results and previous studies which demonstrated the value of antibody titers to this viral DNase as an NPC marker, it appears that EBV-encoded DNase produced in a heterologous expression system could be used in the development of a specific and early NPC diagnosis test.
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PMID:Purification and properties of Epstein-Barr virus DNase expressed in Escherichia coli. 215 38

We have previously shown that 12-O-tetradecanoylphorbol-13-acetate (TPA) which activates expression of the latent genome of the Epstein-Barr virus (EBV) in Burkitt lymphoma cells induces the synthesis of two cellular anti-EBNA-1 competitor proteins, anti-EBNA-1.1 and anti-EBNA-1.2. Both anti-EBNA-1 proteins can uncouple the specific binding of the EBNA-1 to the region required for EBV plasmid maintenance (oriP). Here, we show by DNase I footprinting that the binding sites on oriP for the EBNA-1 and the anti-EBNA-1 proteins were indistinguishable. The proteins bound to the 30-bp tandem repeats of the oriP. Glycerol-gradient centrifugation and gel retardation assay revealed that a 60-kDa protein formed the anti-EBNA-1.1-DNA complex and a 40-kDa protein formed the anti-EBNA-1.2-DNA complex.
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PMID:Interaction of Epstein-Barr viral (EBV) origin of replication (oriP) with EBNA-1 and cellular anti-EBNA-1 proteins. 216 56

The Epstein-Barr virus (EBV) nuclear antigen EBNA-1 plays an integral role in the maintenance of latency in EBV-infected B lymphocytes. EBNA-1 binds to sequences within the plasmid origin of replication (oriP). It is essential for the replication of the latent episomal form of EBV DNA and may also regulate the expression of the EBNA group of latency gene products. We have used sequence-specific DNA-binding assays to purify EBNA-1 away from nonspecific DNA-binding proteins in a B-lymphocyte cell extract. The availability of this eucaryotic protein has allowed an examination of the interaction of EBNA-1 with its specific DNA-binding sites and an evaluation of possible roles for the different binding loci within the EBV genome. DNA filter binding assays and DNase I footprinting experiments showed that the intact Raji EBNA-1 protein recognized the two binding site loci in oriP and the BamHI-Q locus and no other sites in the EBV genome. Competition filter binding experiments with monomer and multimer region I consensus binding sites indicated that cooperative interactions between binding sites have relatively little impact on EBNA-1 binding to region I. An analysis of the binding parameters of the Raji EBNA-1 to the three naturally occurring binding loci revealed that the affinity of EBNA-1 for the three loci differed. The affinity for the sites in region I of oriP was greater than the affinity for the dyad symmetry sites (region II) of oriP, while the physically distant region III locus showed the lowest affinity. This arrangement may provide a mechanism whereby EBNA-1 can lowest affinity. This arrangement may provide a mechanism whereby EBNA-1 can mediate differing regulatory functions through differential binding to its recognition sequence.
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PMID:Interaction of the lymphocyte-derived Epstein-Barr virus nuclear antigen EBNA-1 with its DNA-binding sites. 253 19

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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