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)

Phage Mu d1(Ap,lac) was used to construct the hybrid crp-lac operon in Escherichia coli cells possessing crps mutation which increases sensitivity of bacterial growth to exogenous cAMP. Transcription of the structural lac genes in this hybrid operon was initiated from the promoter region of the crp gene. By measuring levels of beta-galactosidase enzyme, the maximal transcription of the crp gene was obtained in strains with cya or crp mutations causing inactivation of the CRP - cAMP complex. Restoration of cya+crp+ genotype resulted in 5 to 7 times decrease of the lacZ gene activity. At the concentration of exogenous cAMP which induces catabolic derepression in the wild-type strain, the expression of crp-lac operon increased 2-3 times. Using F'ts114lac-mediated chromosome mobilization, the direction of transcription of the crp gene was found to be counterclockwise, relative to the E. coli genetic map.
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PMID:[Construction of the hybrid crp-lac operon and study of the role of CRP-cAMP complex in its regulation in Escherichia coli]. 308 71

The construction and characterization of plasmid vectors useful in the analysis of translation initiation signals in Escherichia coli and in the construction of lacZ gene hybrids are described. Transcription on the vectors proceeds from a cAMP-independent lac promoter through several restriction sites into a truncated lacZ structural gene lacking its first eight codons. Because this gene has no translation initiation signal, its level of expression is extremely low. A DNA fragment containing a translation start signal can be inserted between the promoter and truncated lacZ gene to produce a hybrid protein with functional beta-galactosidase activity. The vectors described here differ in sequence between the EcoRI cloning site and the lacZ gene to allow easy, in-frame joining of DNA containing a translation initiation signal to the lacZ gene. Cells containing plasmids can be screened directly for in-frame inserts by colony color on indicator plates.
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PMID:Plasmid vectors useful in the study of translation initiation signals. 309 57

Correlation between activity of beta-galactosidase, N-acetyl-beta-D-glucosaminidase and content of cAMP and cGMP was studied in lymphocytes and polymorphonuclear leukocytes obtained from 20 children with atopic form of bronchial asthma and 9 patients with dermorespiratory syndrome. Activity of the lysosomal hydrolases studied correlated distinctly with the content of cyclic nucleotides in the leukocytes and lymphocytes of children with bronchial asthma and dermorespiratory syndrome. The most distinct relationship was found between the eosinophilia, the enzymatic activity and the cGMP content in lymphocytes and neutrophils under conditions of dermorespiratory syndrome. The data obtained suggest the dissimilarity of regulatory effects of cyclic nucleotides on functional activity of lysosomes in leukocytes of children with atopic form of bronchial asthma and dermorespiratory syndrome.
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PMID:[Correlations between lysosomal enzymes and cyclic nucleotides during allergies in children]. 321 25

Catabolite repression of tryptophanase was studied in detail under various conditions in several strains of Escherichia coli and was compared with catabolite repression of beta-glactosidase. Induction of tryptophanase and beta-galactosidase in cultures grown with various carbon sources including succinate, glycerol, pyruvate, glucose, gluconate, and arabinose is affected differently by the various carbon sources. The extent of induction does not seem to be related to the growth rate of the culture permitted by the carbon source during the course of the experiment. In cultures grown with glycerol as carbon source, preinduced for beta-galactosidase or tryptophanase and made permeable by ethylenediaminetetraacetic acid (EDTA) treatment, catabolite repression of tryptophanase was not affected markedly by the addition of cAMP (3',5'-cyclic adenosine monophosphate). Catabolite repression by glucose was only partially relieved by the addition of cAMP. In contrast, under the same conditions, cAMP completely relieved catabolite repression of beta-galactosidase by either pyruvate or glucose. Under conditions of limited oxygen, induction of tryptophanase is sensitive to catabolite repression; under the same conditions, beta-galactosidase induction is not sensitive to catabolite repression. Induction of tryptophanase in cells grown with succinate as carbon source is sensitive to catabolite repression by glycerol and pyruvate as well as by glucose. Studies with a glycerol kinaseless mutant indicate that glycerol must be metabolized before it can cause catabolite repression. The EDTA treatment used to make the cells permeable to cAMP was found to affect subsequent growth and induction of either beta-galactosidase or tryptophanase much more adversely in E. coli strain BB than in E. coli strain K-12. Inducation of tryptophanase was reduced by the EDTA treatment significantly more than induction of beta-galactosidase in both strains. Addition of 2.5 x 10(-3)m cAMP appeared partially to reverse the inhibitory effect of the EDTA treatment on enzyme induction but did not restore normal growth.
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PMID:Catabolite repression of tryptophanase in Escherichia coli. 432 48

DNA from a transducing bacteriophage carrying a fusion of the tryptophan and lactose operons of E. coli (lambdadtrp-lac) has been used to direct cell-free synthesis of beta-galactosidase (EC 3.2.1.23). Whereas normal lac operon (lambdadlac) DNA requires adenosine-3':5'-cyclic monophosphate (cAMP) for beta-galactosidase synthesis, trp-lac DNA is unaffected by cAMP. This difference in cAMP dependence verifies the presence of a cAMP-requiring promoter in the lac operon that has been removed from the trp-lac DNA. Synthesis with trp-lac DNA is controlled by the protein product of the tryptophan repressor gene (trpR). Synthesis in extracts of trpR(-) (repressor-negative) cells is progressively reduced by increased additions of extract from trpR(+) cells. No trpR(-) product repression is seen when beta-galactosidase synthesis is programmed by normal lac DNA. This highly sensitive and specific assay has facilitated quantitation and partial purification of the trp repressor.
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PMID:Detection and isolation of the repressor protein for the tryptophan operon of Escherichia coli. 433 82

THE EFFECT OF POLYADENYLIC: polyundylic acid complexes (poly A:U) on the amount of antibody on the surface of various populations of mouse lymphoid cells has been investigated by means of a sensitive measure of such activity-the binding by primed cell populations of beta-galactosidase (betaGZ) as an antigen. The sensitivity derives from the liberation of fluorescein from an artificial substrate, fluorescein-di-beta-galactopyranoside (FDbetaG). After incubation with 100 ng/ml of poly A:U, only 40% of the cells previously showing antigen-binding were still active. The optimum range of activity lay between 0.01-1.0 microg/ml poly A:U. Such cells showed increased RNA and protein synthesis as indicated by [(3)H]uridine and [(14)C]amino acid incorporation. The polynucleotide effect was abolished by incubation of the cells with sodium azide or iodoacetate, but not by puromycin. When the proteins on the cell surface were labeled by (125)I, poly A:U caused their release into the medium. Reports by others that the enhancing effect of polynucleotides on the immune response involves the adenylcyclase system are consistent with the finding reported here that reduction of binding by dibutryl 5'-cyclic monophosphoric acid (cAMP) and poly A:U were parallel in extent, and that theophylline and poly A:U acted synergistically in suboptimal concentrations of each.
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PMID:Studies on membrane-bound receptors for antigen. Preparation of populations of receptor-depleted lymphocytes. 435 80

I have sequenced the first 63 bases of mRNA transcribed in vitro from the UV5 promoter mutant of the E. coli lactose operon. Sonic fragments of DNA, 1000 base pairs long and purified to contain only the lac operator-promoter region, were used as template. The UV5 promoter mutation allows transcription of the lac operon in the absence of catabolite activator protein and cAMP; lac repressor controls the synthesis of this RNA. I find that during synthesis, RNA polymerase pauses at particular sites along the DNA, naturally generating several discrete sizes of RNA that provide overlaps useful for sequencing. The UV5 lac mRNA initiates within the lac operator and copies the operator sequence. The AUG initiator codon for beta-galactosidase occurs at position 39 of the message. The sequence is: pppA-A-U-U-G-U-G-A-G-C-G-G-A-U-A-A-C-A-A-U-U-U- C-A-C-A-C-A-G-G-A-A-A-C-A-G-C-U-A-U-G-A-C-C-A-U- G-A-U-U-A-C-G-G-A-U-U-C-A-C-U-G-G.
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PMID:The nucleotide sequence of the lactose messenger ribonucleic acid transcribed from the UV5 promoter mutant of Escherichia coli. 458 56

S1 nuclease was used to generate a series of deletions which extend into the CAP-cAMP binding site from upstream of the Escherichia coli lactose operon promoter (lacP). Deletion and insertion mutations were also created which changed the spacing region between the CAP-cAMP binding site and the lacP -35 region. The promoter activities of these mutations were compared by measuring the levels of beta-galactosidase gene expression in vivo. The results show that sequence information prior to 74 base pairs (-74) upstream from the transcription start site (designated as +1) is not necessary for the full activation of the lac promoter by the CAP-cAMP complex. However, the deletion which extends to the -71 position retains only one third of the promoter activity in the presence of the CAP-cAMP complex. Removal of one symmetrical element from the two fold symmetry in the CAP-cAMP binding site abolished the CAP-cAMP stimulation of the lac promoter. Spacer mutations which increase by one base pair or decrease by two base pairs the length of the spacing region between the CAP-cAMP binding site and the lacP -35 region drastically reduced the CAP-cAMP stimulation of the lac promoter. This suggests that the distance between the lac promoter transcription start site and CAP-cAMP binding site is crucial for the function of the lac promoter, despite the fact that this distance varies in other E. coli promoters positively regulated by CAP-cAMP. A deletion which extends to the -59 position results in a two fold enhanced expression of lac in the absence of CAP-cAMP. This is consistent with the existance of a competitive RNA polymerase binding site in this region which would normally act to inhibit RNA polymerase binding.
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PMID:Deletion analysis of the CAP-cAMP binding site of the Escherichia coli lactose promoter. 608 87

Prostaglandin E2 (PGE2) seems to stimulate cAMP accumulation in ovaries of all mammals. While it acts through specific receptors in some species, our earlier observations (1) suggest absence of PGE2 receptors in the rat ovary. In order to further substantiate this assumption we digested ovarian membranes from the bovine and the rat with various enzymes and measured cAMP after stimulation with PGE2, NaF, and hCG. Pronase, trypsin, and phospholipase C abolished cAMP accumulation completely. Neuraminidase, beta-galactosidase and phospholipase D did not interfere with cAMP formation. After treatment with phospholipase A2, PGE2-mediated cAMP accumulation was abolished in the bovine but not in the rat ovary. Formation of cAMP disappeared after hCG but not after NaF in both species. Furthermore specific binding of PGE2 could not be demonstrated in phospholipase A2-treated bovine ovaries. These findings are consistent with presence of specific PGE2 receptors in the bovine and their absence in the rat ovary.
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PMID:Further evidence for lack of specific receptors for PGE2 in the rat ovary. 614 70

Alkaline phosphate, catalase and beta-galactosidase activities of Vibrio et tor were decreased after acquisition of resistance towards rifampicin. Zn2+, Mn2+ and EDTA inhibited alkaline phosphatase which is most active with p-nitrophenylphosphate as substrate while Mg2+ was found to suppress alkaline phosphatase activity. Removal of EDTA however, restores the original activity. Rifampicin could not induce mutation of lactose nonfermenting Vibrio el for cells allowing them to grow on lactose as sole carbon source, z-galactosidase which is a constitutive enzyme in this case is repressed by glucose. This repression is overcome by cAMP.
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PMID:Studies on alkaline phosphatase, catalase and z-galactosidase in Vibrio el tor under normal and rifampicin resistant conditions. 618 76


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