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 set of protein hybrids composed of variable portions of the amino-terminal residues of the yeast phosphate-repressible acid phosphatase (product of PHO5) and an active fragment of bacterial beta-galactosidase has been constructed. When these PHO5-LACZ hybrids are expressed in a yeast strain carrying an intact chromosomal PHO5 gene, they show a size-dependent interference with the secretion of native acid phosphatase. Hybrid proteins containing approximately 50 residues of acid phosphatase do not affect secretion of native acid phosphatase. Hybrids containing greater than 200 residues of acid phosphatase reduce the amount of secreted acid phosphatase more than by 50%. The interference with secretion is specific for acid phosphatase. The hybrids do not affect secretion of invertase, and do not confer a growth-deficient phenotype on yeast. Both the hybrid proteins and acid phosphatase accumulate in non-glycosylated, membrane-bound forms which are sensitive to proteolysis from the cytoplasmic side of the membrane. The hybrids and accumulated acid phosphatase co-migrate on Percoll density gradients with markers of the endoplasmic reticulum, but not with markers of the Golgi or secretory vesicles. These results suggest that PHO5-LACZ hybrid proteins specifically block secretion of native acid phosphatase by interfering with enzyme after targeting but before translocation across the endoplasmic reticulum.
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PMID:PHO5-LACZ hybrid proteins block translocation of native acid phosphatase in Saccharomyces cerevisiae. 312 33

It has been shown previously that Escherichia coli accumulates endogenously synthesized trehalose under osmotic stress. We report here that E. coli contained an osmotically regulated trehalose-phosphate synthase which utilized UDP-glucose and glucose 6-phosphate as substrates. In the wild type, the synthase was induced by growth in glucose-mineral medium of elevated osmotic strength and the synthase itself was strongly stimulated by K+ and other monovalent cations. A laboratory strain which expressed the synthase at a high constitutive level was found. GalU mutants, defective in synthesis of UDP-glucose, did not accumulate trehalose. Two genes governing the synthase were identified and named otsA and otsB (osmoregulatory trehalose synthesis). They mapped near 42 min in the flbB-uvrC region. Mutants with an otsA-lacZ or otsB-lacZ operon fusion displayed osmotically inducible beta-galactosidase activity; i.e., the activity was increased fivefold by growth in medium of elevated osmotic strength. Mutants unable to synthesize trehalose (galU, otsA, and otsB) were osmotically sensitive in glucose-mineral medium. But an osmotically tolerant phenotype was restored in the presence of glycine betaine, which also partially repressed the synthesis of synthase in the wild type and of beta-galactosidase in ots-lacZ fusion mutants.
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PMID:Biochemical and genetic characterization of osmoregulatory trehalose synthesis in Escherichia coli. 313 12

The mutagenicity of urine obtained from five cigarette smokers was investigated using two bacterial assays: the Ames test and the SOS Chromotest. Urinary mutagens were extracted on Amberlite XAD-2 resin. Four urine samples showed activity towards Salmonella typhimurium tester strain TA98 with S9 mix while no SOS-inducing activity could be measured with Escherichia coli strain PQ37 in the SOS Chromotest. Using factorial design and a positive control benzo[a]pyrene (BaP), the concentration of S9, nicotinamide adenine dinucleotide phosphate (NADP) and glucose-6-phosphate (G6P) were optimized (2%, 0.5 mM and 10 mM respectively) for the SOS Chromotest. The SOS-inducing power of BaP was 1.42/nM with the standard S9 mix and 3.26/nM with the optimized S9 mix. B buffer and the age of L-broth were found to decrease the sensitivity of beta-galactosidase assays in the SOS Chromotest. A 4000-fold urine concentrate from a smoker was finally tested using the Ames test and the modified SOS Chromotest. Mutagenic and toxic activities were found toward tester strain TA98 (+S9 mix) showing that the SOS Chromotest is not at present suitable for assaying urinary mutagens in the presence of an in vitro metabolic activating mixture.
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PMID:Applicability of the SOS Chromotest to detect urinary mutagenicity caused by smoking. 313 23

The Escherichia coli glpT gene encodes a transport protein that mediates uptake of sn-glycerol-3-phosphate. This permease is a member of a class of bacterial organophosphate permeases which transport substrates by antiport with inorganic phosphate. The glpT gene product, probably an oligomer of a single polypeptide chain, is thought to span the cytoplasmic membrane several times, as predicted by the hydropathic profile. Protein fusions, in which varying lengths of the amino-terminal end of the permease is attached to alkaline phosphatase (phoA) and to beta-galactosidase (lacZ) were constructed. On the assumption that phoA fusions only exhibit high enzymatic activity when fused to extra-cytoplasmic regions of the target protein, whereas lacZ fusions will only be active when the beta-galactosidase portion is attached to cytoplasmic domains of the target protein, the activities of the fusions were used to test a two-dimensional model for the permease. The model proposes that GlpT contains 12 transmembrane segments divided by a larger cytoplasmic region. Despite some limitation caused by hot-spot sites of transpositions, the TnphoA approach was consistent with the model. In contrast, we feel that the enzymatic activity of lacZ fusions is only a limited parameter for studying the topology of a complex membrane protein.
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PMID:The transmembrane topology of the sn-glycerol-3-phosphate permease of Escherichia coli analysed by phoA and lacZ protein fusions. 314 44

The nucleotide sequence of a 2.1 kb DNA fragment bearing the HIS5 gene of Saccharomyces cerevisiae, which encodes histidinol-phosphate aminotransferase (EC 2.6.1.9), has been determined. An open reading frame of 1,152 bp was found. S1 nuclease mapping indicated that the major transcription starts at position -37 from the ATG codon and the minor (approximately 20%) at -34 in both repressive and derepressive conditions. Northern analysis indicated that transcription of the HIS5 gene is under the general control of amino acid biosynthesis. The 5' noncoding region of the gene, thus far examined up to position -616, contains three copies of sequences homologous to the short repeats of the consensus sequence, 5'-AATGTGACTC-3', suggested for general amino acid control in the HIS1, HIS3, HIS4, and TRP5 at positions -336, -275 and -205. The consensus sequence closest to the open reading frame was shown to be necessary but not sufficient for general amino acid control, by examination of beta-galactosidase appearance in S. cerevisiae cells carrying various mutant HIS5 promoter regions fused to the lac'Z gene and inserted at the leu2 locus of chromosome III.
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PMID:Structure of the yeast HIS5 gene responsive to general control of amino acid biosynthesis. 330 7

In this clinically useful enzyme immunoassay of digoxin in serum, we mix sample, beta-galactosidase-labeled digoxin, and anti-digoxin Fab fragments for 30 min at room temperature, then use Sepharose-bound second antibody for phase separation, and measure the unbound enzyme activity directly in the supernate of the equilibrium reaction mixture. The immunoassay buffer--phosphate-buffered isotonic saline with added rabbit globulin (4 g/L), hydrolyzed gelatin (2 g/L), Brij 96 detergent (5 g/L), glycerol (0.25 mol/L), and N-acetyl-8-anilinonaphthalene-1-sulfonic acid (2 mmol/L)--minimizes serum matrix effects for convenient measuring of unbound enzyme--digoxin conjugate. The immunoassay developed with Fab fragments has better displacement characteristics than that with intact antibody. Performance of the assay compares favorably with that of other manual digoxin immunoassays; in comparison studies with EMIT involving 110 clinical specimens, the coefficient of correlation was 0.97.
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PMID:Competitive solid-phase enzyme immunoassay for measuring digoxin in serum. 351 90

17- and 20-mer oligodeoxyribonucleotides and their analogues, containing one to four phosphate groups esterified with ethyl alcohol in different positions of oligonucleotide chain, were synthesized by modified triester method. Ethylated di- and trinucleotide blocks were prepared by transesterification method from chlorophenyl derivatives. The structures of the oligonucleotides were confirmed by Maxam-Gilbert sequencing method. Oligonucleotides were not totally complementary to the N-terminal region of lac Z'gene (coding for N-terminal fragment of beta-galactosidase) of phage M13mpB DNA and induced the formation of the proposed deletion mutant DNA M13mp1 delta T. Phosphotriester analogues were more effective mutagens as compared to phosphodiester oligonucleotides due to their stability to nucleases. The use of E. coli DNA-polymerase I provided the increase in the mutant yields in case of the phosphotriester analogues. The stability of the analogues to 5'----3'----5'-endonuclease action, the specificity of oligonucleotide: DNA binding and the structure of mutant DNA were studied by the Sanger sequencing method.
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PMID:[Site-localized mutagenesis directed by phosphotriester analogs of oligonucleotides]. 377 34

phoB is a positive regulatory gene of the phosphate regulon of Escherichia coli. A plasmid carrying a phoB'-'lacZ fusion gene was constructed by in vitro recombination. A PhoB-LacZ hybrid protein was purified from the cells carrying the plasmid by monitoring beta-galactosidase activity. The amino-terminal amino acid sequence of the PhoB protein was determined by utilizing the hybrid protein. Antiserum against the PhoB protein was prepared by immunizing rabbits with the hybrid protein. The serum thus prepared showed specificity for both the PhoB protein and beta-galactosidase.
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PMID:Use of a phoB'-'lacZ fusion gene to determine the N-terminal amino acid sequence of the phoB protein and to prepare antiserum against the protein. 392 8

In porcine areolar placental epithelia, the following enzymes were demonstrated by histochemical methods after 30, 58, 80, 100, and 110 d of pregnancy, respectively: beta-N-acetyl-hexosaminidase, beta-galactosidase, beta-glucuronidase, alpha-mannosidase, acid phosphatase, alkaline phosphatase, nonspecific esterases, cytochrome oxidase, 5-nucleotidase, leucine aminopeptidase, adenosine triphosphatase, diaphorases (NADH, NADPH), glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, succinate dehydrogenase, isocitrate dehydrogenase (NAD, NADP), beta-hydroxybutyrate dehydrogenase, glycero-3-phosphate dehydrogenase, NAD-glycero-3-phosphate dehydrogenase, glutamate dehydrogenase (NAD, NADP), lactate dehydrogenase. The results show that the enzyme activities remained almost unchanged during the period of investigation. Of the dehydrogenases, the diaphorases as well as succinate and lactate dehydrogenase demonstrated generally an intensive activity within the epithelia. The activity of the other dehydrogenases was only low. The activity of unspecific esterase was very intensive within the uterine epithelia but remarkably low within chorionic epithelia. Contrarily, the reaction of adenosine triphosphatase was more intensive within chorionic than uterine epithelia. All investigated glucosidases reacted distinctly positive within chorionic epithelia, but only beta-N-acetyl-hexosaminidase and beta-galactosidase in uterine epithelia. The high activity of acid phosphatase, especially within the chorionic epithelium, seems to be connected with uteroferrin, an iron-binding protein. The histochemical results are discussed in context with the function of the areolae in histiotrophic nutrition and iron transport.
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PMID:[Enzyme-histochemical studies of the pig placenta. II. Histotopics of enzymes in the areolar placenta epithelium]. 392 41

1. Both permanent and transient catabolite repression of beta-galactosidase synthesis in Escherichia coli are abolished by 5mm-3':5'-cyclic-AMP when elicited by glucose, but not when caused by a mixture of glucose, glucose 6-phosphate, gluconate and casein hydrolysate (casamino acids). 2. Glucose uptake is slightly increased by 3':5'-cyclic-AMP. 3. No significant effects of the nucleotide were found on the synthesis of protein and RNA, either in exponential growth on one substrate, or during a growth shift from glycerol to glycerol plus glucose. 4. Marked changes in the soluble-protein profiles of cells growing in glycerol and glucose were caused by the presence of 3':5'-cyclic-AMP. 5. Measurements of (14)CO(2) release from specifically-labelled glucose showed that 3':5'-cyclic-AMP greatly stimulated glycolytic activity while having a minor depressing effect on the metabolic flow through the pentose phosphate cycle. 6. The concentrations of several metabolic intermediates, particularly fructose 1,6-diphosphate, were greatly affected by the presence of 3':5'-cyclic-AMP. 7. Several metabolites partially relieved glucose repression of beta-galactosidase synthesis in EDTA-treated cells; three out of five of these metabolites reversed the effect more effectively than did 3':5'-cyclic-AMP. 8. The evidence for and against a direct role for 3':5'-cyclic-AMP is discussed. It is concluded that the evidence for indirect action is at least as strong as that for direct action.
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PMID:Adenosine 3':5'-cyclic monophosphate and catabolite repression in Escherichia coli. 431 43


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