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)

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

Using RNA-directed synthesis of the alpha-peptide of beta-galactosidase as an assay, a factor was purified that inactivated further function of the mRNA. In the presence of Ca2+ ions to inhibit most nuclease activity, inactivation of mRNA occurred during incubation with ribosomes or with a 1 M KCl wash of ribosomes. The inactivation activity required Mg2+ ions, and purified as a single factor which did not bind to DEAE-cellulose, but bound reversibly to phosphocellulose. The factor eluted from Sephadex G-150 with an apparent molecular weight of about 43,000. Purified 700-fold, it showed no detectable exonuclease activity, and little or no cleavage of a variety of single-stranded substrates, including full length lac operon mRNA; but repurified inactivated mRNA was still inactive for protein synthesis. The factor did not inhibit poly(U)-directed polyphenylalanine synthesis. When proteins isolated from the ribosomal wash were individually tested, highly purified RNase III, which purifies in the same way and has the same size, also inactivated lac mRNA. The ribosomal wash from an RNase III- strain showed little if any activity compared to that from an isogenic RNase III+ strain. The possibility of a site-specific inactivating cleavage of mRNA by RNase III at or near the 5' end is considered.
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PMID:Functional inactivation of lac alpha-peptide mRNA by a factor that purifies that Escherichia coli RNase III. 625 91

The factor(s) derived from fibrosarcoma-induced suppressor T cells was sensitive to pronase and neuraminidase, but not to trypsin, beta-galactosidase, DNase, or RNase. Protein and RNA, but not DNA, synthesis were required to mediate suppression. Suppressor T cell-derived factor(s) could be precipitated by a 50% saturated ammonium sulfate (SAS) solution. The 50% SAS fraction inhibited both in vitro and in vivo spleen cell blastogenesis, whereas the 80% and unprecipitated fractions had no inhibitory activity. Using Sephadex G-200 chromatography, the 2nd protein fraction (fraction II) contained an inhibitor of both DNA polymerases (IDP) and DNA synthesis (IDS) activity, which possessed no cytotoxic activity. In vitro DNA polymerase alpha activity was suppressed by fraction II, whereas DNA polymerase beta and gamma activities remained unchanged. Molecular weight of IDP/IDS, as determined by Sephadex G-200 gel filtration chromatography, was approximately 14,500. Attempts to separate IDP/IDS activities found in fraction II by anion-exchange chromatography and slab gel electrophoresis were not successful, which suggested that the 2 activities were the same or very similar molecules.
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PMID:Suppressor cell activity in tumor-bearing mice. III. Co-purification of a factor inhibiting cellular DNA synthesis and DNA polymerase activity. 645 73

The tyrosine hydroxylase (TH) gene is expressed exclusively in cells and neurons that synthesize and release L-DOPA or catecholamines. To further understand the molecular genetic mechanisms that regulate this cell-type specific expression, a chimeric gene was prepared by linking 3.6 kb of the 5' flanking DNA of the mouse TH gene, including the +1 initiation site for transcription, to an E. coli beta-galactosidase reporter. This fusion gene (TH3.6LAC) was used to prepare transgenic mice, and the tissue distribution of expression of TH3.6LAC was determined by the measurement of beta-galactosidase enzymatic activity and/or by the detection of the transcription product of the chimeric gene by RNase protection assays. In two separate founder lines, TH3.6LAC expression was observed in every region of the brain that was examined, including the olfactory bulb, brainstem, cerebellum, diencephalon, hippocampus, striatum, and cerebral cortex. Expression of TH3.6LAC was observed in the adrenal gland of one founder line but not in the other. TH3.6LAC activation was undetectable in peripheral organs that were examined, including the liver, heart, salivary gland, kidney, lung, and spleen. Although 3.6 kb of the 5' regulatory DNA of the mouse TH gene is sufficient to activate the TH fusion gene in the mouse, it is not enough to restrict its expression to catecholaminergic cells.
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PMID:3.6 kb of the 5' flanking DNA activates the mouse tyrosine hydroxylase gene promoter without catecholaminergic-specific expression. 852 54

The beta-globin locus control region (LCR) confers high levels of position-independent, copy number-dependent expression onto globin transgenes. Here > 40 independent transgenic mouse lines and founders that carried the LCR in cis with the beta-globin gene promoter driving a lacZ reporter gene were studied. Expression of the lacZ transgene was assayed by measuring beta-galactosidase enzyme activity in fetal liver extracts, the levels of which correlated with the quantity of lacZ mRNA determined using RNase protection assays. Unexpectedly, expression of the lacZ transgene was found to show strong position effects, varying as much as 700-fold per transgene copy. These position effects occurred even if the whole beta-globin gene was incorporated as part of the lacZ reporter gene. Moreover, DNase I-hypersensitive sites appeared in the transgene LCR in high expressing but not in low expressing lines, suggesting that the LCR itself was position dependent. In contrast, MEL cell clones, in which transcriptionally active integration sites were selected for, gave < 13-fold variation in expression per copy of an LCR-lacZ construct. These results show that the lacZ reporter affects the ability of the LCR to activate chromatin in mice and that culture cells are not an adequate model for position-independent gene expression studies.
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PMID:The beta-globin locus control region enhances transcription of but does not confer position-independent expression onto the lacZ gene in transgenic mice. 867 Aug 75

The promoter region of the alpha-subunit of the calcium/calmodulin-dependent protein kinase II (alpha-CaMKII) gene was inserted into a beta-galactosidase (beta-gal) reporter plasmid, and beta-gal activities were examined in neuroblastoma (NB2a) and pheochromocytoma (PC12) cells after transient or stable transfections. The alpha-CaMKII promoter was 12- to 45-fold more active in NB2a compared with PC12 cells after transient or stable transfections. All-trans retinoic acid (RA) stimulated reporter gene expression at both protein and mRNA levels in transfected PC12 cells. RA increased the level of endogenous alpha-CaMKII mRNA in untransfected PC12 cells by 4.4-fold. The transcription initiation site(s) (TIS) of the alpha-CaMKII gene in PC12 cells and rat brain was examined by RNase protection assays (RPA) and reverse transcriptase PCRs. The TIS for the alpha-CaMKII/beta-gal reporter gene in transfected PC12 cells was indistinguishable from the TIS+1 in rat hippocampus. In contrast, the only detectable TIS for the alpha-CaMKII gene in untransfected PC12 cells was located near the ATG translation start codon, 147 nucleotides 3' to TIS+1 in hippocampus. This unusual TIS was also the predominant TIS in rat cerebellum. These results suggest that the alpha-CaMKII promoter may contain sequences that respond directly or indirectly to RA. In addition, the unusual TIS of the alpha-CaMKII gene in PC12 cells and rat cerebellum may contribute to the very low expression of this gene compared with that in hippocampus.
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PMID:Retinoic acid stimulates alpha-CAMKII gene expression in PC12 cells at a distinct transcription initiation site. 879 26

The amount of porin protein OmpF in the outer membrane of Escherichia coli was reduced to one-third by the pgsA3 mutation that diminishes the amount of phosphatidylglycerol and cardiolipin in the membrane, whereas a cls (cardiolipin synthase) null mutation had no effect. Osmoregulation of OmpF was functional in the pgsA3 mutant. As assessed by the beta-galactosidase activities of lacZ fusions, the ompF expression was not reduced at the transcriptional level but was reduced about threefold at the posttranscriptional level by pgsA3. This reduction was mostly restored by a micF null mutation, and the micF RNA that inhibits the ompF mRNA translation was present 1.3 to 1.4 times more in the pgsA3 mutant, as assayed by RNase protection and Northern blot analyses. Elevation of the level of micF RNA was not restricted to acidic-phospholipid deficiency: OmpF was hardly detected and micF RNA was present 2.7 to 2.8 times more in a pssA null mutant that lacked phosphatidylethanolamine. Other common phenotypes of pgsA3 and pssA null mutants, reduced rates of cell growth and phospholipid synthesis, were not the cause of micF activation. Salicylate, which activates micF expression and inhibits cell motility, did not repress the flagellar master operon. These results imply that an unbalanced phospholipid composition, rather than a decrease or increase in the amount of specific phospholipid species, induces a phospholipid-specific stress signal to which certain regulatory genes respond positively or negatively according to their intrinsic mechanisms.
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PMID:Unbalanced membrane phospholipid compositions affect transcriptional expression of certain regulatory genes in Escherichia coli. 913 2

Bacillus subtilis cytochrome c oxidase caa3 is encoded by the ctaCDEF genes at the ctaABCDEF locus, with the ctaBCDEF genes organized as an operon-like unit. A dyad symmetry sequence and a catabolite response element homolog can be recognized in the 240-bp intercistronic region between ctaB and ctaC. ctaB'-lacZ and ctaBCD'-lacZ transcriptional fusions integrated at the native locus were used to study catabolite effects on transcription of the ctaB and ctaCDEF genes. In Schaeffer's medium lacking glucose, ctaBCD'-lacZ was expressed at a very low level during the exponential phase, and expression increased about 30-fold 2 h after entry into the stationary phase. In the presence of 0.5% glucose, ctaBCD'-lacZ expression was totally repressed. In contrast to ctaBCD'-lacZ, ctaB'-lacZ was constitutively expressed regardless of carbon source. The ctaCDEF genes were separated from ctaB by insertion of plasmids carrying selectable markers in such a way that the ctaCDEF and ctaB transcription units remained intact. Enzymatic assays of caa3 with these constructs, showed that ctaCDEF was not expressed independently of ctaB. Also, when a 'ctaB-ctaC'-lacZ fusion (containing the ctaB-ctaC intercistronic region) was placed at a remote nonessential locus, beta-galactosidase activity could not be detected. The absence of a promoter in the ctaB-ctaC intercistronic space also was indicated by the inability to detect ctaC-specific transcripts with RNase protection assays, primer extension, and rapid amplification of 5' cDNA ends. Direct mRNA measurements showed that, in the presence of 0.5% glucose, ctaBCDEF transcripts terminated at the 3' end of the putative stem-loop structure and the distal portion was down-regulated. A possible mechanism for ctaCDEF gene regulation is suggested. Catabolite repression of ctaBCD'-lacZ was partly dependent on CcpA but was independent of HPr. The expression of ctaBCDEF also appears to require the strC, ctaA, and resD-resE gene products.
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PMID:Catabolite regulation of the Bacillus subtilis ctaBCDEF gene cluster. 982 23

Transgenic mice were generated expressing an alpha1 connexin/beta-galactosidase fusion protein previously shown to exert dominant negative effects on gap junctional communication. RNase protection analysis and assays for beta-galactosidase enzymatic activity showed that the transgene RNA and protein are expressed in the embryo and adult tissues. In situ hybridization analysis revealed that in the embryo, expression was predominantly restricted to neural crest cells and their progenitors in the dorsal neural tube, regions where the endogenous alpha1 connexin gene is also expressed. Dye-coupling analysis indicated that gap junctional communication was inhibited in the cardiac neural crest cells. All of the transgenic lines were homozygote inviable, dying neonatally and exhibiting heart malformations involving the right ventricular outflow tract-the same region affected in the alpha1 connexin knockout mice. As in the knockout mice, the conotruncal heart malformations were accompanied by outflow tract obstruction. Histological analysis showed that this was associated with abnormalities in the differentiation of the conotruncal myocardium. These results suggest that the precise level of gap junctional communication in cardiac neural crest cells is of critical importance in right ventricular outflow tract morphogenesis. Consistent with this possibility is the fact that cardiac crest cells from the alpha1 connexin knockout mice also exhibited a greatly reduced level of gap junctional communication. These studies show the efficacy of a dominant negative approach for manipulating gap junctional communication in the mouse embryo and demonstrate that targeted expression of this fusion protein can be a powerful tool for examining the role of gap junctions in mammalian development.
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PMID:Heart malformations in transgenic mice exhibiting dominant negative inhibition of gap junctional communication in neural crest cells. 985 55

High-performance liquid chromatography with on-line electrospray ionization mass spectrometry (ESI-LC/MS) was investigated for the analysis of carbohydrate heterogeneity using RNase B as a model glycoprotein. Oligosaccharides released from RNase B with endoglycosidase H were reduced and separated on a graphitized carbon column (GCC). GCC-HPLC/MS in the positive-ion mode was successful in the identification of one Man5GlcNAc, three Man6GlcNAc, three Man7GlcNAc, three Man8GlcNAc, one Man9GlcNAc, and an oligosaccharide having six hexose units (Hex) and two N-acetylhexosamine units (HexNAc). The branch structures of the three Man7GlcNAc isomers were determined by liquid chromatography with tandem mass spectrometry (LC/MS/MS). LC/MS/MS analysis was shown to be useful for the detection and identification of a trace amount of Hex6HexNAc2 alditol as a hybrid-type oligosaccharide. Its structure was confirmed by the combination of LC/MS with enzymatic digestion using beta-galactosidase and N-acetyl-beta-glucosaminidase. The relative quantities of high-mannose-type oligosaccharides in RNase B detected by ESI-LC/MS are in reasonable agreement with those by UV, high-pH anion-exchange chromatography with pulsed amperometric detection, fluorophore-assisted carbohydrate electrophoresis. Our results indicate that LC/MS and LC/MS/MS can be utilized to elucidate the distribution of oligosaccharides and their structures, which differ in molecular weight, sugar sequence, and branch structure.
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PMID:Analysis of carbohydrate heterogeneity in a glycoprotein using liquid chromatography/mass spectrometry and liquid chromatography with tandem mass spectrometry. 1022 1


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