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)

Previous work ascribed antibiotic hypersensitivity of the envA1 mutant to lowered lipopolysaccharide levels and exposure of the lipid bilayer. In the detailed characterization of the EnvA permeability phenotype presented here, the envA1 mutation was shown to confer leakage of the periplasmic enzymes beta-lactamase and RNase I. Leakage was observed in three different genetic backgrounds, including the original envA1 strain and its parent. In contrast, no detectable leakage of the cytoplasmic enzyme beta-galactosidase was observed. Sensitivity of envA1 strains to a range of antibiotics not previously reported was tested, and lipophilicity (partition coefficient) of a number of antibiotics was determined. On the basis of observations of periplasmic leakage and sensitivity to large hydrophilic antibiotics and lysozyme, part of the permeability phenotype of the envA1 mutant is proposed to be due to transient rupture and resealing of the EDTA-sensitive outer membrane layer. In this regard, the EnvA permeability phenotype falls into a general class of permeability/leaky mutants of both Escherichia coli and Salmonella typhimurium.
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PMID:Leakage of periplasmic enzymes from envA1 strains of Escherichia coli. 190 54

Transgenic mice carrying a liver-specific promoter fused to a nuclear-targeted lacZ reporter gene were generated. Three separate lines of mice showed liver expression in the adult and no expression elsewhere in the animal. These results show that a 1.7 kb 5'-flanking region in the retinol-binding protein gene contains necessary and sufficient transcriptional signals for expression in adult livers. A fourth line (R197) did not express the transgene in the liver; instead, constitutive lacZ expression was seen during postimplantation stages of development from Day 9.5 onwards and appeared to be associated with segmented structures including somites, branchial arches, and hindbrain rhombomeres until late fetal stages. The beta-galactosidase positive cells in R197 were later seen to give rise to facial and flank musculature, and to other region-specific subpopulations of the jaws, neocortex, and brain stem. Northern blot analysis for the host retinol-binding protein RNA transcript did not show overlapping tissue expression with the reporter gene and suggests that transgenic phenotype seen in segmented embryonic structures of R197 and other extra-hepatic sites is from novel cis-acting transcriptional specificity. RNase protection assays of the R197 mRNA indicate that the lacZ sequences are appropriately transcribed downstream of the RBP canonical TATA box, even though the RBP promoter is itself silent. This result would suggest host flanking sequences with enhancer activity may have either activated the lacZ reporter gene or cooperated with the RBP promoter to create novel region-specific transcription. Breeding experiments have so far failed to produce offsprings that are homozygous for the transgene, and mating of transgenic F1 siblings routinely produce reduced litter sizes. Embryos that are homozygous for the transgene appear to be unable to survive beyond the egg cylinder stages of development. Thus, disruption of the host genome by insertional mutation appears to be manifest at an earlier stage than when position-effect expression of the transgene is first apparent. These experiments demonstrate that the component parts of a transgene may be subject to differential activation or suppression by host genomic flanking sequences and that even a strong, tissue-specific promoter may be overridden by host genes.
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PMID:Liver-specific and position-effect expression of a retinol-binding protein-lacZ fusion gene (RBP-lacZ) in transgenic mice. 206 Jul 5

The outB gene of Bacillus subtilis is under the control of two promoters (P1 and P2). To study the regulation of expression from the P1 promoter we have constructed a set of multicopy plasmids carrying different portions of the outB region and analyzed the transcripts present in vivo by RNase protection experiments. The data indicate that the product of gene outB regulates its own transcription from the P1 promoter. We also constructed an outB-lacZ fusion in an insertional plasmid. The plasmid was inserted into the chromosome adjacent to or distal from the outB gene. Assays of beta-galactosidase activity and RNase protection experiments are in accordance with a model implying that the product of gene outB regulates the initiation of transcription from the P1 promoter acting in the cis configuration.
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PMID:The outB gene of Bacillus subtilis regulates its own transcription. 246 9

We have overproduced and purified wild type regA protein, a translational repressor encoded by bacteriophage T4. The repressor activity of the cloned regA protein has been tested on four known regA target genes (T4 genes: 44, 45, rpbA and regA) using in vitro coupled transcription-translation reactions. We have demonstrated the sensitivity of two additional T4 genes coding for alpha- and beta-glucosyltransferases to regA protein in vitro. The regA target site on the gene 44 messenger RNA has been identified through deletion analysis and RNase protection assays, using plasmids containing gene 44-lacZ fusions. The effect of regA protein on expression of 44P-beta-galactosidase fusion proteins was assayed in vitro, in coupled transcription-translation reactions. Analysis of deletion mutants of gene 44-lacZ localized the regA recognition region to between nucleotides -11 and +9 of the mRNA. RNase protection assays of g44-lacZ transcripts further defined the site of regA protein interaction to between nucleotides -10 and +2 of the mRNA. This region overlaps the gene 44 Shine-Dalgarno region and the A and U of the initiation codon.
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PMID:Bacteriophage T4 regA protein binds to the Shine-Dalgarno region of gene 44 mRNA. 269

In order to study the biochemical changes associated with the cell body response to axonal crush injury, two systems, hypoglossal nucleus and spinal cord ventral horn, were used. The time intervals chosen were 7, 14, and 28 days after unilateral crushing of the right hypoglossal nerve and cervicothoracic nerves of the rabbit. Non-crushed, contralateral nerves were used as controls. Three groups of enzyme activities were tested: (a) phospholipase A2, acyl CoA:2-acyl-sn-glycero-3-phosphocholine acyltransferase, and choline phosphotransferase, as indicators of phospholipid degradation and biosynthesis; (b) seven hydrolases, namely, beta-D-glucuronidase, beta-N-acetyl-D-hexosaminidase, arylsulfatase A, galactosylceramidase, GM1-ganglioside beta-galactosidase, and acid RNase, as indicators of lysosomal activity; and (c) free and inhibitor-bound alkaline RNase, as an index of RNA metabolism. Changes could be grouped into three distinct patterns. Compared to contralateral control, choline phosphotransferase showed a slight increase, whereas phospholipase A2 and most lysosomal hydrolases showed a significant increase of activity, especially evident in the ventral spinal cord neurons 14-28 days after crushing. These changes correlate with known increases of membrane and organelle numbers, including lysosomes, in motor and sensory neurons during peripheral regeneration. In contrast, free and acid alkaline RNase activity significantly decreased in the injured sides compared to the controls. This change can probably be correlated with a stabilization of RNAs needed for increased protein synthesis. No changes in total alkaline RNase and acyltransferase activities in either regeneration model were observed.
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PMID:Changes of phospholipid-metabolizing and lysosomal enzymes in hypoglossal nucleus and ventral horn motoneurons during regeneration of craniospinal nerves. 283 34

Homogenates of Giardia lamblia trophozoites exhibited the following hydrolase activities: acid phosphatase (EC 3.1.3.2), proteinase (EC 3.1.4) with urea-denatured hemoglobin and N-benzoyl-DL-arginine-2-naphthylamide as substrates, deoxyribonuclease (EC 3.1.4.5), and ribonuclease (EC 2.7.7.16). beta-N-Acetylglucosaminidase (EC 3.2.1.30), beta-galactosidase (EC 3.2.1.23), beta-glucuronidase (EC 3.2.1.31), alpha-D-glucosidase (EC 3.2.1.20), beta-D-glucosidase (EC 3.2.1.21), and beta-D-xylosidase (EC 3.2.1.37) activities were below the level of detection. Differential and isopycnic centrifugation of homogenates demonstrated that giardial hydrolases were localized in a single-particle population sedimenting at 7200g for 30 min. The particles had a buoyant density in sucrose of 1.15 and exhibited latency. Latency was completely destroyed by Triton X-100 or 15 cycles of freezing and thawing. After centrifugation of Triton- or freeze-thaw-treated particle fractions, the hydrolase activities, though no longer latent, were still sedimentable suggesting tight binding to the organelle membrane. Latency was destroyed simultaneously for all hydrolases, in direct proportion to the amount of Triton added to a particle preparation or to the number of times a particle preparation was subjected to freezing and thawing. These results support the suggestion that the hydrolases of G. lamblia trophozoites are localized in a single-particle population of lysosome-like organelles.
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PMID:Giardia lamblia: localization of hydrolase activities in lysosome-like organelles of trophozoites. 327 50

A synthetic gene for bovine pancreatic ribonuclease A (RNase A) has been expressed in Escherichia coli as a fusion protein with beta-galactosidase linked by the tetrapeptide Ile-Glu-Gly-Arg. RNase A was cleaved from the fusion using factor Xa, and the resulting product purified and reconstituted. The isolated RNase A was chromatographically, catalytically, and immunologically identical with authentic RNase A. This work argues that the method suggested by Nagai and Thogersen [Nagai, K. & Thogersen, H. C. (1984) Nature (Lond.) 309, 810-812] for releasing fusion proteins is quite general, even when applied to particularly complicated expression problem. The procedure here makes RNase A available for the first time as a model for studying structure-function relationships in proteins using site-directed mutagenesis.
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PMID:Expression of bovine pancreatic ribonuclease A in Escherichia coli. 354 26

One hundred twenty-seven isolates of Aeromonas comprising the three currently recognizable species (A. hydrophila, A. sobria, and A. caviae) were evaluated for biochemical and exoenzymatic properties. Aeromonas species were generally (greater than 90%) characterized as gram-negative fermentative rods that were oxidase-, catalase-, and beta-galactosidase-positive, produced arginine dihydrolase, and failed to decarboxylate ornithine. More than 95% of all isolates tested failed to grow on 6.5% salt or thiosulfate-citrate bile salts agar and were resistant to the vibriostatic agent 0/129. Most Aeromonas species produced acid from hexoses while failing to ferment alcoholic sugars or trisaccharides. In exoenzymatic studies, Aeromonas species were uniformly found to produce several exoenzymes, including amylase, DNase, RNase, esterase, lipase, gelatinase, protease, fibrinolysin, and chitinase. Within the genus, a number of biochemical and enzymatic properties were found to be associated with one or more of the taxonomically recognizable species. These properties included glycoside utilization, Heiberg grouping based upon fermentation of arabinose, sucrose, and mannose, and the elaboration of several extracellular enzymes (elastase, hemolysin, lecithinase, phosphatase). In addition, phenotypic markers previously associated with enterotoxigenic Aeromonas isolates were almost exclusively found among A. hydrophila and A. sobria species, suggesting that these species are the major enteric pathogens.
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PMID:Biochemical and exoenzymatic properties of Aeromonas species. 388 8

A number of "surface" enzymes of Escherichia coli (i.e., among those selectively released by osmotic shock) all displayed higher specific activities in extracts of minicells than in extracts of typical rod forms; these enzymes included alkaline phosphatase, cyclic phosphodiesterase, acid hexose monophosphatase, 5'-nucleotidase, and ribonuclease I. In addition, alkaline phosphatase, cyclic phosphodiesterase, and acid hexose monophosphatase were cytochemically localized to regions of minicell periplasm that resembled reactive polar enlargements of the periplasm in rod forms. In contrast, a number of "internal" cytoplasmic enzymes (inorganic pyrophosphatase, beta-galactosidase, glutamine synthetase, polynucleotide phosphorylase, and ribonuclease II) showed elevated or similar specific activities in extracts of rod forms versus extracts of minicells. A specific heat-labile inhibitor for 5'-nucleotidase, known to occur in the cytoplasm, also showed no enrichment in minicells. These findings indicate that the "surface" enzymes are segregated in vivo into the terminal minicell buds, possibly because these enzymes are concentrated in the polar enlargements of the periplasm in typical rod forms.
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PMID:Biochemical and cytochemical evidence for the polar concentration of periplasmic enzymes in a "minicell" strain of Escherichia coli. 431 25

Strains of Escherichia coli that possess ribonucleic acid accumulated under relaxed growth conditions show a considerable increase in time before the onset of beta-galactosidase inducibility. This time dependency can be related to the presence or absence of ribonuclease I.
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PMID:Screening procedure for Escherichia coli mutants deficient in ribonuclease I. 457 May 95


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