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 defective herpes simplex virus 1 (HSV-1) vector, pHSVlac, has been developed that contains a transcription unit that places the Escherichia coli lacZ gene under the control of the HSV-1 immediate early 4/5 promoter. The vector pHSVlac was propagated with the HSV-1 temperature-sensitive mutant ts K as helper virus. Infection of neurons from rat superior cervical ganglia and dorsal root ganglia in primary culture resulted in stable expression of high levels of beta-galactosidase without cell death. These HSV-1 vectors should be useful for introducing genes into postmitotic cells, such as neurons, in vitro and in vivo.
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PMID:A defective HSV-1 vector expresses Escherichia coli beta-galactosidase in cultured peripheral neurons. 284 86

We show that a gene introduced into cells of mouse embryos by a retrovirus can serve as a heritable marker for the study of cell lineage in vivo. We constructed a defective recombinant retrovirus in which the Escherichia coli beta-galactosidase (lacZ) gene is inserted in the genome of a Muloney murine leukemia virus (M-MuLV). Expression of lacZ was detected with a histochemical stain that can be applied to cultured cells and embryonic tissue. Infection of cultured cells showed that lacZ has no detectable deleterious effects on cell viability or growth, that the enzyme is stably expressed in the progeny of infected cells for many generations in the absence of selective pressure, and that the virus can induce lacZ in a variety of cell types. Following injection of the virus into mid-gestation mouse embryos, clones of lacZ-positive cells were detected in skin, skull, meninges, brain, visceral yolk sac, and amnion. We identified the cell types comprising a series of lacZ-positive clones in the visceral yolk sac and skin to learn the lineage relationships of the labelled cells. In each tissue, we obtained evidence that several cell types have a pluripotential ancestor and that cell fate is progressively restricted as development proceeds.
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PMID:Use of a recombinant retrovirus to study post-implantation cell lineage in mouse embryos. 310 26

The beta-galactosidase gene (lacZ) of Escherichia coli was inserted in phase with the coding sequence of the Autographa californica nuclear polyhedrosis virus (AcMNPV) late-expressed Mr 10,000 (p10) gene. The fusion gene was inserted into the AcMNPV genome by cotransfection of a recombinant plasmid pAcR159Z, consisting of the EcoRI P fragment-containing pBR325-derived plasmid pAcR159 and the lacZ insert in the p10 gene, and wild-type AcMNPVDNA. Infection of Spodoptera frugiperda cells by the resulting recombinant AcMNPV/p10Z-2 showed high level expression of a p10-lacZ fusion protein, but no synthesis of p10. Therefore, the p10 gene is dispensable for virus replication and the p10 promoter is effective in driving the expression of foreign genes. Cells infected with AcMNPV/p10Z recombinants resembled those infected with wild-type AcMNPV in the amounts of polyhedrin synthesized and polyhedra formed, although p10 was absent. The nucleus and cytoplasm of AcMNPV/p10Z-2-infected cells lacked the fibrous structures that are associated with p10 in wild-type AcMNPV-infected cells. Instead, large granular structures were observed that were found by immunogold labelling to contain the lacZ gene product. The electron-dense 'spacers', thought to be precursors of the polyhedron membrane, were absent from cells infected by the recombinant virus and the polyhedra did not have a membrane. The recombinant AcMNPV/p10Z-2 was at least twice as virulent for second instar S. exigua larvae than was wild-type AcMNPV. The increased virulence of the recombinant is an important property for the control of insects.
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PMID:Functional studies on the p10 gene of Autographa californica nuclear polyhedrosis virus using a recombinant expressing a p10-beta-galactosidase fusion gene. 312 41

Degradation of bacterial deoxyribonucleic acid (DNA) after infection with T4 bacteriophage was studied in an endonuclease I-deficient host. The kinetics of degradation were similar to those seen in other hosts with a normal level of this enzyme. Irradiation of extracellular phage with ultraviolet (UV) destroyed the capacity of the infecting virus to induce extensive breakdown of host DNA, which was, however, converted to high-molecular-weight material. Addition of chloramphenicol to T4-infected cells provided data which can be interpreted to indicate the involvement of at least two endodeoxyribonucleases and one exodeoxyribonuclease having a high degree of specificity. A model is proposed showing the sequential action of two endodeoxyribonucleases followed by an exodeoxyribonuclease in the degradation of host DNA. The appearance of these hydrolytic enzymes requires protein synthesis. Infections leading to partial degradation only (UV-irradiated phages, gene 46 mutants) effectively inhibited the synthesis of bacterial messenger ribonucleic acid and of beta-galactosidase.
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PMID:Bacteriophage-induced inhibition of host functions. II. Evidence for multiple, sequential bacteriophage-induced deoxyribonucleases responsible for degradation of cellular deoxyribonucleic acid. 489 64

Infection by ribonucleic acid (RNA) bacteriophage R23 inhibited the synthesis of beta-galactosidase in Escherichia coli. The inhibition, although not complete, was apparent shortly after infection and was maximal after the first 20 min of infection. R23 diminished the beta-galactosidase-synthesizing capacity when inducer was added after phage infection, but not when infection followed inducer removal. These findings suggested that the primary effect of R23 on enzyme-forming capacity was limitation of synthesis of enzyme-specific messenger RNA. Studies with ultraviolet irradiated phage and amber mutants of R23 indicated that the inhibitory process could be separated into two phases. Early inhibition did not require the expression of the viral genome, whereas late inhibition required the expression of the viral RNA synthetase cistron.
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PMID:Effect of infection with ribonucleic acid bacteriophage R23 on the inducible synthesis of beta-galactosidase in Escherichia coli. 491 Aug 18

Two gene clusters on the Escherichia coli chromosome were induced at early times after T4 infection when >99% of the cells were infected: the lactose (lac) operon and prophage lambda. Their messenger ribonucleic acid (mRNA) was detected by hybridization to phi80 dlac deoxyribonucleic acid (DNA) and lambdaDNA, respectively. Synthesis of host mRNA could be initiated during the first few minutes after T4 infection, although no beta-galactosidase activity could be detected. Hybridization analyses of selected fractions from sucrose gradients revealed that most of this lac mRNA induced at very early times of T4 infection was not associated with ribosomes. In contrast, virtually all lac mRNA in uninfected bacteria was associated with polysomes. This exclusion affected all host mRNA; about 70% of E. coli(3)H-mRNA, labeled from 2 to 3 min after T4 infection, was excluded from polysomes. Infection even reduced the yield of beta-galactosidase from lac mRNA induced before infection. Gradients from rifampicin-inhibited cells showed the normal growth of lac mRNA polysomes; in contrast, T4 infection prevented growth of the preinduced lac polysomes. It is concluded that T4 infection interferes within seconds with the reassociation of ribosomes to host mRNA.
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PMID:Inhibition of host protein synthesis during infection of Escherichia coli by bacteriophage T4. II. Induction of host messenger ribonucleic acid and its exclusion from polysomes. 492 74

A derivative strain of a K-12 isolate of Escherichia coli was selected utilizing the operon fusion technique of Casadaban. This derivative strain (VL 361) was characterized by its ability to synthesize the enzyme beta-galactosidase - the gene product of the inserted lacZ gene - as if it were type 1 fimbriae. Enzyme production was found to behave according to the properties of phase variation, thus mimicking the phase variation seen with type 1 fimbriae. The oscillation between the on-and-off synthesis of enzyme was found to be random, and was not influenced by such environmental factors as temperature, glucose or cyclic AMP. Thus the selection in various media of either fimbriate or non-fimbriate states is probably not genetic in nature, but rather the outgrowth of one type of phase over another.
Infection 1982
PMID:Operon fusion of the phase variation switch. A virulence factor in Escherichia coli. 612 7

Hepatitis B is a widespread viral disease. In the absence of cell cultures capable of propagating the virus (HBV) an efficient vaccine has been prepared from viral envelopes isolated from the plasma of chronic carriers. The major polypeptide of the envelope is one of molecular weight 25,000 which carries the surface antigen (HBsAg). Therefore, the biosynthesis of this polypeptide in Escherichia coli may offer an alternative procedure to produce HbsAg free from human proteins. Recently, the HBV genome has been cloned in E.coli. Determination of its primary structure allowed the localization of the gene (called gene S) coding for HBsAg and the synthesis of the core antigen in E.coli has been reported. We have constructed a derivative of bacteriophage lambda carrying a fusion between the beta-galactosidase gene (lacZ) and the HBsAg coding sequence (lambdalacHBs-1). Infection of E.coli with lambdalacHBs-1 leads to the biosynthesis of a polypeptide of molecular weitht 138,000 carrying antigenic determinants of HBV surface antigen.
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PMID:Biosynthesis of hepatitis B virus surface antigen in Escherichia coli. 615 92

A cloned interferon alpha 2 (IFN-alpha 2) gene was partially digestd with Pvu II to give a fragment that was inserted into the HincII site of the lacZ gene of bacteriophage M13mp7. Two recombinant phages containing the IFN-alpha 2 sequences in the correct orientation for expression from the lac promoter were characterized in detail. DNA sequence analysis showed that the inserted IFN-alpha 2 gene was in phase with the initiation codon of the lacZ gene. The polypeptide product has an additional 19 amino amino acids at the amino terminus of the mature IFN-alpha 2. The first 11 amino acids originate from the amino terminus of beta-galactosidase, and the remaining 8 amino acids are part of the signal sequence of pre-IFN-alpha 2. Infection of Escherichia coli with these phage followed by induction of the lac promoter with isopropyl thiogalactoside gives high yields (up to 10(9) units/liter with an average of 1.5 X 10(8) units/liter) of the modified IFN-alpha 2. This was purified to homogeneity in a single step by immunochromatography using the monoclonal antibody NK2. The nonreduced product had an apparent molecular weight of 20,500 and was shown by immunoradiometric assay to have the same specific activity as IFN made in Namalwa cells. It exhibited the characteristic cross-species antiviral activity of IFN-alpha 2.
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PMID:High-level expression of an interferon alpha 2 gene cloned in phage M13mp7 and subsequent purification with a monoclonal antibody. 675 48

To target gene expression to malignant hepatic cells, we have constructed recombinant retroviral vectors containing a reporter gene encoding nuclear beta-galactosidase (nls-LacZ) under transcriptional control of regulatory sequences from the rat alpha-fetoprotein (AFP) or human insulinlike growth factor II (IGFII) genes. The AFP and IGFII P3 promoters activate transcription during fetal development and are often reactivated in hepatocellular carcinoma (HCC). Infection of several cultured cell types with the retroviral vector containing the IGFII P3 sequence resulted in expression of the reporter gene in all cell lines tested, including those that do not produce IGFII. In contrast, selective expression was achieved by vectors containing the AFP transcriptional regulatory sequence. Nuclear beta-galactosidase activity was detectable in cells from lines that produce AFP, and not in cells that do not express the AFP gene. In most infected cell lines, retroviral RNA synthesis from the 5' LTR was inhibited, and deletion of the retroviral LTR enhancer did not change expression from either the IGFII P3-nls-LacZ or the AFP-nls-LacZ cassettes. After treatment of cells with 12-O-tetradecanoylphorbol-13-acetate and epidermal growth factor (EGF), the decrease in concentrations of endogenous AFP messenger RNA (mRNA) and nls-LacZ mRNA transcribed from the transferred AFP regulatory sequence were similar. In the context of an integrated provirus, the AFP transcriptional regulatory sequence is therefore subject to similar regulatory control as that of the endogenous gene. These data show that the AFP sequence, and not the IGFII P3 promoter we used, is suitable for targeting gene expression to malignant hepatic cells.
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PMID:Hepatoma cell-specific expression of a retrovirally transferred gene is achieved by alpha-fetoprotein but not insulinlike growth factor II regulatory sequences. 748 90


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