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:3.2.1.23 (beta-galactosidase)
14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A quantitative bioassay for human immunodeficiency viruses has been developed on the basis of the ability of the tat gene to transactivate the expression of an integrated beta-galactosidase gene in a HeLa-CD4+ cell line. Infection by a single virion of HIV-1 or HIV-2 corresponds to a unique blue syncytium or a cell cluster detected after fixation and addition of 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (a beta-galactosidase substrate). The number of infected lymphoid cells in a culture (stimulated human peripheral blood lymphocytes and cell lines) can also be quantified by cell-to-cell transmission of HIV into the HeLa-CD4(+)-beta-galactosidase monolayer. Infections by simian immunodeficiency viruses are similarly detected. This assay has been used to determine the dose response of drugs, the half-life of HIV at 37 degrees C, and the appearance of infectious particles after virus infection.
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PMID:Activation of a beta-galactosidase recombinant provirus: application to titration of human immunodeficiency virus (HIV) and HIV-infected cells. 211 May 96

We show that the stimulation of human immunodeficiency virus (HIV) brought about by tumor necrosis factor alpha and phorbol 12-myristate 13-acetate can be inhibited by adding N-acetyl-L-cysteine (NAC). NAC, which replenishes intracellular glutathione, effectively inhibits the tumor necrosis factor alpha- or phorbol ester-stimulated replication of HIV in acutely infected cell cultures. NAC also inhibits the cytokine-enhanced HIV long terminal repeat-directed expression of beta-galactosidase in in vitro HIV model systems. These results show that intracellular thiol levels influence HIV production. Furthermore, because NAC reverses tumor necrosis factor alpha toxicity both in cells and in animals and is a well-known drug that can be administered orally without known toxicity in humans, these results suggest that NAC is a possible therapeutic agent in AIDS.
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PMID:Cytokine-stimulated human immunodeficiency virus replication is inhibited by N-acetyl-L-cysteine. 211 50

A number of nucleosides with anti-human immunodeficiency virus (HIV) activity were evaluated in two colorimetric (beta-galactosidase) assays for induction of the SOS response in Escherichia coli. 3'-Azido-3'-deoxythymidine (azidothymidine; AZT), 2',3'-dideoxyadenosine (ddA), 2',3'-dideoxyguanosine (ddG), and 2',3'-dideoxyinosine (ddI) induced cell filamentation (sulA) and prophage lambda in well-agar diffusion and liquid microsuspension assays. AZT was approximately 100 times more potent than the dideoxypurine nucleosides, inducing sulA at less than 100 ng/ml. 2',3'-Dideoxythymidine (ddT) and 2',3'-dideoxy-2',3'-didehydrothymidine (D4T) induced sulA at 100 to 1,000 micrograms/ml, while 2',3'-dideoxycytidine (ddC) weakly induced prophage lambda. Activity relationships thus were AZT greater than ddA greater than or equal to ddI greater than or equal to ddG greater than ddT = D4T greater than ddC. ddA and ddI had equivalent activities in agar diffusion assays, but different activity profiles were observed in liquid microsuspension assays. The differences may be related to drug metabolism. AZT and ddA showed marginal effects in a DNA repair (preferential toxicity) assay in which E. coli WP2 and CM871 uvrA recA lexA were used. Furthermore, none of the agents was able to preferentially inhibit Bacillus subtilis M45 recA relative to wild-type strain H17. These data suggest that AZT and the dideoxynucleosides do not cause DNA lesions that are repairable by excision repair and/or error-free postreplication repair processes. Rather, the SOS response appears to be induced by DNA chain termination leading to the inhibition of DNA replication. Bacterial assays for induction of the SOS response may be useful as simple, rapid prescreens for the discovery of new anti-HIV agents. Moreover, such assays may provide an additional parameter in the evaluation of agents with demonstrated activity against HIV and other retroviruses.
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PMID:Induction of the SOS response in Escherichia coli by azidothymidine and dideoxynucleosides. 211 27

It has been previously shown in vitro that the human immunodeficiency virus type 1 long terminal repeat (LTR) is activated by ultraviolet irradiation. In order to analyze if a similar effect could occur in vivo, transgenic mice carrying the lacZ gene under the control of the viral LTR were irradiated at 280-300 and 254 nm. These mice spontaneously expressed the transgene in the epidermis and the lens of both adults and embryos. Irradiations caused a significant increase in skin beta-galactosidase activity. This phenomenon might be involved in viral activation and could be of interest in regard to the skin pathology observed during an HIV infection.
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PMID:In vivo activation by ultraviolet rays of the human immunodeficiency virus type 1 long terminal repeat. 212 Feb 88

A "cleavage cassette" specifying a decapeptide human immunodeficiency virus (HIV) protease cleavage site was introduced into six different locations of beta-galactosidase (beta-D-galactoside galactohydrolase, EC 3.2.1.23) in Escherichia coli. Four of these constructs retained beta-galactosidase activity despite the insertion of the cleavage cassette. Of these four constructs, one was cleaved by HIV protease, resulting in the inactivation of beta-galactosidase both in vivo and in vitro. This cleavage was inhibited by pepstatin A, a known inhibitor of HIV protease. Thus, beta-galactosidase has been converted into an easily assayed substrate for HIV protease. An analogous construct of beta-galactosidase containing a polio protease cleavage site was cleaved likewise by polio protease, suggesting that this system may be generic for monitoring cleavage by a variety of proteases.
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PMID:beta-Galactosidase containing a human immunodeficiency virus protease cleavage site is cleaved and inactivated by human immunodeficiency virus protease. 212 94

The Epstein-Barr virus immediate-early gene product BZLF1 transactivates the human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR). The BZLF1 gene product caused an 18-fold increase in beta-galactosidase activity from an HIV-1 LTR lacZ expression vector, whereas the HIV-1 transactivator tat caused a 44-fold increase in beta-galactosidase activity. When cells were transfected with both BZLF1 (pEBV-Z) and tat (pTAT3) expression vectors, as well as HIV-1 LTR lacZ plasmid (pLRON), a 214-fold increase in beta-galactosidase activity was observed. This result suggests a synergistic effect of BZLF1 and tat on HIV-1 LTR-directed lacZ gene expression. Analysis of quantitative BZLF1 and tat requirements for maximal HIV-1 LTR activation indicates that BZLF1 does not reduce the amount of tat required for maximal LTR activation, as would be expected if the BZLF1 synergistic effect was due to increased tat gene expression. Thus, coordinate effects of BZLF1 and tat on the HIV-1 LTR or its transcript are probably responsible for synergistic HIV-1 LTR activation.
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PMID:The Epstein-Barr virus BZLF1 gene product activates the human immunodeficiency virus type 1 5' long terminal repeat. 217 93

The rev (art/trs) protein of human immunodeficiency virus type 1 (HIV-1), a phosphoprotein of 20 K apparent molecular weight, is essential to target the mRNA for virion polypeptides into the cytoplasm. The rev protein was expressed in Escherichia coli as a beta-galactosidase fusion protein with a cleavage site for proteinase factor Xa. The rev-specific fragment was isolated to immunize mice. Five stable hybridoma cell lines were obtained producing monoclonal antibodies that reacted with rev protein in Western blot and ELISA. Using the monoclonal antibodies in indirect immunofluorescence, the rev protein could be localized in the nucleus, mostly in the nucleoli, of Hela cells that were transfected with a eukaryotic rev expression plasmid.
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PMID:Monoclonal antibodies directed against the rev protein of human immunodeficiency virus type 1. 217 12

The human immunodeficiency virus rev gene product regulates the expression of viral structural genes. It was recently shown that Rev regulates the export of viral structural mRNAs from the nucleus to the cytoplasm. Analysis of Rev subcellular localization reveals marked accumulation in the nucleolus, suggesting a role for the nucleolus in this export process. We report here the identification of amino acid residues critical to the nucleolar localization of Rev. Consistent with this finding, a Rev/beta-galactosidase fusion protein, harboring this region of Rev, localized entirely within the nucleolus. Of most significance, mutations that eliminated nucleolar localization markedly diminished Rev function, even though accumulation in the nucleoplasm was retained. These findings support a model whereby Rev-induced export of human immunodeficiency virus structural mRNAs from the nucleus to the cytoplasm is likely to involve nucleolar events.
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PMID:Identification of sequences important in the nucleolar localization of human immunodeficiency virus Rev: relevance of nucleolar localization to function. 240 40

The sequences encoding the p24 core protein of human immunodeficiency virus type 1 were identified in a cDNA library made from infected CEM cells. The nucleotide sequence of the DNA coding for p24 was shown to be very similar but not identical to the sequences of lymphadenopathy virus and human T-cell leukaemia virus type IIIb. These sequences were expressed in Escherichia coli at the amino terminus of beta-galactosidase and used to screen a panel of monoclonal antibodies raised against virus-expressed p24. Regions containing the epitopes of five of the monoclonal antibodies were located using a series of amino- and carboxy-terminal deletion mutants of the recombinant p24 protein.
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PMID:The cloning and expression in Escherichia coli of sequences coding for p24, the core protein of human immunodeficiency virus, and the use of the recombinant protein in characterizing a panel of monoclonal antibodies against the viral p24 protein. 247 10

The sequences coding for the p18 protein of CBL-1, a British human immunodeficiency virus (HIV) type 1 isolate, were expressed in Escherichia coli as beta-galactosidase fusion proteins. The recombinant proteins were used to screen a panel of five monoclonal antibodies (MAbs) raised against p18 expressed in CBL-1-infected cells. The regions containing the epitopes for four of the MAbs were located using carboxy deletion mutants and synthetic peptides. The epitope of one of the MAbs (1D9) was reconstructed as part of an unfused, E. coli-expressed p18 protein using the polymerase chain reaction technique. Four different HIV strains and one lymphadenopathy virus type 2 strain were analysed by fluorescence-activated cell sorting of live infected cells using the p18-reactive MAbs.
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PMID:The expression in Escherichia coli of sequences coding for the p18 protein of human immunodeficiency virus and the use of the recombinant protein in characterizing a panel of monoclonal antibodies against the viral p18 protein. 247 11


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