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)

Few foamy (spuma) retroviruses have been investigated in molecular detail, despite their previous isolation from several mamalian species, including ten neutralization serotypes from various primates. Here, we have studied a new gorilla foamy virus (SFV-Gg) and investigated its functional and phylogenetic relationship to the human (HFV) and other primate foamy viruses, including that recently described in orangutans (SFV-11). Nucleotide sequencing of PCR products obtained from the R/U5 region of the LTR, gag, and pol genes revealed a close relationship between HFV and three chimpanzee isolates (SFV-6, SFV-7, and SFV-cpz). The SFV-Gg, SFV-11, rhesus macaque (SFV-1), and African green monkey (SFV-3) isolates were more divergent. To explore functional relationships, primate foamy virus transactivation of HFV LTR driven beta-galactosidase expression in a newly constructed cell line, BHLL, was investigated. HFV, SFV-6, and SFV-7 potently transactivated HFV LTR driven lacZ gene expression, SFV-Gg induced expression approximately 10-fold less efficiently, and SFV types 1, 2, 3, and 11 did not significantly transactivate the HFV LTR. It was, thus, possible to assay serum neutralizing activity in SFV-infected primates against HFV, SFV-6, and SFV-7 by reduction of beta-galactosidase activity following infection of the indicator cell line. Sera from infected chimpanzees and gorillas neutralized, to varying degrees, each of these three viruses, whereas orangutan sera did not. Our results, based on DNA sequences and functional assays, support the conclusion that HFV is closely related to foamy viruses of chimpanzee origin.
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PMID:A comparative study of higher primate foamy viruses, including a new virus from a gorilla. 787 29

GPD1 (encoding glyceraldehyde-3-phosphate dehydrogenase) is a constitutively expressed gene in Cochliobolus heterostrophus that produces a single transcript. The steady state level of GPD1 mRNA is 14-fold greater than that of the constitutively-expressed TRP1 gene (encoding a tryptophan biosynthesis enzyme) indicating that GPD1 has a stronger promoter and/or a more stable mRNA. A set of lacZ translational fusion vectors was constructed to compare the gene expression signals of GPD1, TRP1 and PRO1 (a C. heterostrophus genomic fragment selected for promoter activity) in C. heterostrophus as single copies at the same site in the chromosome. Under conditions that repressed endogenous beta-galactosidase expression, beta-galactosidase activity in transformants was constitutive and required the GPD1, TRP1 or PRO1 expression signals. In-frame GPD1::lacZ activities were 6-fold greater than in-frame TRP1::lacZ and PRO1::lacZ activities, indicating that GPD1 has more efficient expression signals.
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PMID:Relative strengths of promoters from Cochliobolus heterostrophus. 792 7

Two early and potential rate-limiting steps in the biosynthesis of isoquinoline alkaloids, such as morphine and codeine, in opium poppy (Papaver somniferum) involve decarboxylation of L-tyrosine and L-dihydroxyphenylalanine (L-dopa) to yield tyramine and dopamine, respectively. A DNA fragment was amplified by polymerase chain reaction (PCR) using degenerate primers designed to two highly conserved domains found in other aromatic amino acid decarboxylases. A poppy seedling cDNA library was screened with this PCR product and a cDNA (cTYDC1) for tyrosine/dopa decarboxylase (TYDC/DODC) was isolated. Two other independent cDNAs (cTYDC2 and cTYDC3) encoding TYDC/DODC were isolated by heterologous screening with a plant tryptophan decarboxylase (TDC) cDNA as probe. A poppy genomic library was screened with cTYDC1 and two intronless genomic clones (gTYDC1 and gTYDC4) were isolated. The deduced amino acid sequences of all poppy clones share extensive identity with other reported pyridoxal phosphate-dependent decarboxylases from both plants and animals. Based on sequence homology, members of the gene family were divided into two subsets (cTYDC1 and gTYDC4; cTYDC2 and cTYDC3) of proteins with predicted M(r) = 56,983 and 59,323, respectively. Within each subset the clones exhibit greater than 90% identity, whereas clones between subsets share less than 75% identity. Expression of gTYDC1 and cTYDC2 as beta-galactosidase fusion proteins in Escherichia coli resulted in catalytically active enzymes immunodetectable with TDC-specific polyclonal antibodies. Each enzyme showed marginally higher substrate specificity for L-dopa over L-tyrosine, but did not accept L-tryptophan and L-phenylalanine as substrates. Genomic DNA blot-hybridization analysis revealed 6 to 8 genes homologous to cTYDC1 and 4 to 6 genes homologous to cTYDC2 in the tetraploid poppy genome. A premature translation stop codon was found in the gTYDC4 clone suggesting that it may not encode a functional protein. RNA blot-hybridization with probes specific to the gTYDC1- or cTYDC2-like subsets showed that members of the TYDC gene family are differentially expressed in various plant tissues.
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PMID:Differential and tissue-specific expression of a gene family for tyrosine/dopa decarboxylase in opium poppy. 792 1

It has previously been shown that the hepatitis B virus X gene product, pX, transactivates homologous and heterologous transcriptional regulatory sequences of viruses and various cellular genes in vitro. However, there is no evidence about the reproducibility and the relevance of this phenomenon in vivo. In this study we crossbred transgenic mice expressing the X gene under the control of the human antithrombin III (ATIII) gene regulatory sequences with transgenics carrying either the chloramphenicol acetyl-transferase or the LacZ bacterial reporter genes driven by the HIV1-LTR, which is known to be activated in trans by pX. Expression of pX in the liver stimulates the HIV1-LTR driven expression of both chloramphenicol acetyl-transferase and beta-galactosidase reporter genes in double transgenic mice. No detectable increase in chloramphenicol acetyl-transferase expression was observed in tissues, such as the spleen, brain and heart, that do not express pX. Our results confirm the transactivating properties of pX in vivo for the first time and support the hypothesis that pX might indeed modify gene expression in HBV-infected hepatocytes and influence viral pathogenesis.
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PMID:Hepatitis B virus X gene product acts as a transactivator in vivo. 796 9

The possibility was studied to use the U3 promoter from LTR region of bovine leukemia virus to control the expression of the antisense RNA genes directed against the BLV genome in cell cultures FLK-BLV, CC81, and HeLa. The genetic engineering constructions were obtained carrying the reporter beta-galactosidase gene and the genome of antisense RNA to R-U5 region of the viral genome under the control of the promoter. The functioning of the viral promoter was studied in three cell lines. Its specific activation and kinetics of inhibition of BLV virus reproduction in cell culture CC81 have been demonstrated. The maximal 75% level of the viral reproduction inhibition was achieved at threefold molar excess of the plasmid containing the antisense RNA gene over the pregenomic viral DNA.
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PMID:[Use of U3 promotor from the LTR region of bovine leukemia virus for expressing genes for antiviral antisense RNAs in cell cultures]. 806 78

To develop a reporter system to study the response of an integrated retroviral LTR and cellular and viral events which influence transcription, the 5' LTR of HTLV-1 was coupled to the Escherichia coli beta-galactosidase gene (lacZ). This construct was assembled within a vector containing the neomycin resistance gene controlled by the SV40 promoter, and introduced into HeLa cells. Expression from the LTR in one clone was upregulated by positive regulators of HTLV-1 expression, including 12-O-tetradecanoylphorbol-13-acetate (TPA) and the HTLV-1 transregulatory protein (tax), as has been previously reported using transient transfection assays. This method proved to be a rapid and reproducible assay for the measurement of integrated viral LTR activation in a single cell system.
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PMID:Cytochemical analysis of human T cell leukaemia virus I LTR-regulated beta-galactosidase gene expression using a novel integrated cell system. 811 42

Tryptophan biosynthesis in Escherichia coli is regulated by the product of the trpR gene, the tryptophan (Trp) repressor. Trp aporepressor binds the corepressor, L-tryptophan, to form a holorepressor complex, which binds trp operator DNA tightly, and inhibits transcription of the tryptophan biosynthetic operon. The conservation of trp operator sequences among enteric Gram-negative bacteria suggests that trpR genes from other bacterial species can be cloned by complementation in E. coli. To clone trpR homologues, a deletion of the E. coli trpR gene, delta trpR504, was made on a plasmid by site-directed mutagenesis, then crossed onto the E. coli genome. Plasmid clones of the trpR genes of Enterobacter aerogenes and Enterobacter cloacae were isolated by complementation of the delta trpR504 allele, scored as the ability to repress beta-galactosidase synthesis from a prophage-borne trpE-lacZ gene fusion. The predicted amino acid sequences of four enteric TrpR proteins show differences, clustered on the backside of the folded repressor, opposite the DNA-binding helix-turn-helix substructures. These differences are predicted to have little effect on the interactions of the aporepressor with tryptophan, holorepressor with operator DNA, or tandemly bound holorepressor dimers with one another. Although there is some variation observed at the dimer interface, interactions predicted to stabilize the interface are conserved. The phylogenetic relationships revealed by the TrpR amino acid sequence alignment agree with the results of others.
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PMID:The tryptophan repressor sequence is highly conserved among the Enterobacteriaceae. 820 6

The human T-lymphotropic virus type I (HTLV-I) Tax protein is a transcriptional regulatory protein that has been suggested to play a causal role in the development of several HTLV-I-associated diseases. Tax regulates expression of its own LTR and of certain cellular promoters perhaps by usurping the function of the host transcriptional machinery. We have established a transgenic mouse model system to define the spectrum of tissues in vivo that are capable of supporting Tax-mediated transcriptional transactivation. Transgenic mice carrying the HTLV-I LTR driving expression of the Escherichia coli beta-galactosidase (beta gal) gene were generated, and this LTR-beta gal gene was transcriptionally inactive in all tissues. When LTR-beta gal mice were mated to transgenic mice carrying the same LTR driving expression of the HTLV-I tax gene, mice that carried both transgenes showed restricted expression of the beta gal reporter gene in several tissues including muscle, bone, salivary glands, skin, and nerve. In addition, a dramatic increase in the number of beta gal-expressing cells was seen in response to wounding. These observations provide direct evidence for viral transactivation in vivo, delimit the tissues capable of supporting that transactivation, and provide a model system to study the mechanism of gene regulation by Tax.
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PMID:A transgenic model of transactivation by the Tax protein of HTLV-I. 835 1

Recombinant retroviruses are widely used for gene transfer into eukaryotic cells and exhibit significant potential for human gene therapy. Despite the utility of retroviral vectors, their design is still essentially empirical. We have constructed a series of reciprocal, double-gene vectors to compare the dual expression of beta-galactosidase (beta-gal) and neomycin phosphotransferase (neor) in a retroviral delivery system. The first gene of the pair was driven by the viral LTR promoter and the internal gene was regulated by either the SV40 virus early promoter or the cytomegalovirus (CMV) major late promoter. Clones of vector producer cells were isolated either by G418 selection for expression of neor, or by fluorescence-activated cell sorting for expression of beta-gal, and the activity of both genes was evaluated. In general, vectors using the SV40 promoter performed better than those with the CMV promoter, regardless of whether the selected gene was regulated by the LTR or the internal promoter. Southern analysis of clones indicated that loss of beta-gal gene function was related to significant rearrangements and deletions in vector structure. We also found that the arrangement of genes within the vector was important. When beta-gal preceded neor, gene expression and vector stability were markedly enhanced relative to vectors containing these genes in the inverse order.
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PMID:Factors affecting retroviral vector function and structural integrity. 839 Nov 78

We have analyzed the effect of transfection into murine NIH/3T3 cells of the human dsRNA-activated kinase PKR on the expression of the beta-galactosidase reporter gene, placed under control of the HIV1 or the HTLV-I LTR. beta-Galactosidase expression is stimulated when the reporter plasmids are cotransfected with wild-type PKR but inhibited when cotransfected with a catalytically inactive mutant PKR. In the case of HIV1, beta-galactosidase expression was not stimulated when cotransfection was carried out with PKR harboring mutations in the dsRNA binding domains, indicating that stimulation depends on the classical mode of PKR activation through dsRNA binding. In contrast, the dsRNA binding mutants of PKR could still partially stimulate beta-galactosidase expression from the HTLV-I LTR, suggesting that PKR activation in this case may involve different/additional mechanisms. These results show that, in addition to the known down-regulation of protein synthesis through elF2 phosphorylation, PKR can also positively stimulate gene expression in vivo, most probably through phosphorylation of a substrate distinct from elF2.
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PMID:Human PKR transfected into murine cells stimulates expression of genes under control of the HIV1 or HTLV-I LTR. 855 71


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