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)

The promoter of the threonine operon was joined to the structural genes of the lac operon in Escherichia coli K 12. The synthesis of beta-galactosidase was thus repressed by threonine plus isoleucine in the fusion strains. To isolate mutations which affect the expression of the threonine operon, alterations in the level of expression of the lacZ gene were selected. A new type of regulatory mutation was discovered.
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PMID:New regulatory mutations affecting the expression of the threonine operon in Escherichia coli K-12. 9 15

Aminoethylated beta-galactosidase from Escherichia coli was cleaved by CNBr. The fragment C4a was purified by gel filtration and ion-exchange chromatography. The molecular weight of the fragment C4a was determined to be 9000 +/- 600. The N-terminal amino acid was found to be isoleucine. Qualitative examination of homogeneity was carried out by disc-gel electrophoresis. The fragment C4a was shown to be active as an alpha donor in complementation of beta-galactosidase activity in vitro with E. coli mutant M15, which has a deletion in the alpha region of the z gene. The molecular weights of complementable fractions from mutant M15 were found to be 123 000 +/- 2500 and 507 000 +/- 11 000, and of the complemented enzyme 522 500 +/- 11 400.
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PMID:A cyanogen bromide fragment of beta-galactosidase from Escherichia coli with alpha-donor activity in complementation of the enzyme from mutant M15. 77 70

Intracistronic alpha-complementation between a cyanogen bromide digest of beta-galactosidase and an extract of the lac Zminus operator-proximal deletion mutant M15 was used to monitor the purification of a cyanogen bromide peptide (CB2) responsible for the complementation. Key steps in the purification were ion exchange chromatography on carboxymethylcellulose and sulfopropyl-Sephadex in the presence of urea, and Sephadex gel filtration. CB2 contains residues 3 to 92 of beta-galactosidase. Its sequence is: Ile-Thr-Asp-Ser-Leu-Ala-Val-Val-Leu-Gln-Arg-Arg-Asp-Trp-Glu-Asn-Pro-Gly-Val-Thr-Gln-Leu-Asn-Arg-Leu-Ala-Ala-His-Pro-Pro-Phe-Ala-Ser-Trp-Arg-Asn-Ser-Glu-Glu-Ala-Arg-Thr-Asp-Arg-Pro-Ser-Gln-Gln-Leu-Arg-Ser-Leu-Asn-Gly-Glu-Trp-Arg-Phe-Ala-Trp-Phe-Pro-Ala-Pro-Glu-Ala-Val-Pro-Glu-Ser-Trp-Leu-Glu-Cys-Asp-Leu-Pro-Glu-Ala-Asp-Thr-Val-Val-Val-Pro-Ser-Asn-Trp-Gln-Met. Thus no more than 1/13 of the beta-galactosidase polypeptide chain, starting 2 residues from the NH2 terminus, is necessary for alpha-complementation with M15 as alpha-acceptor.
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PMID:Amino acid sequence of beta-galactosidase. IV. Sequence of an alpha-complementing cyanogen bromide peptide, residues 3 to 92. 109 37

The Avi-3 antigen, which is found only in Mycobacterium avium culture sonic extracts, is species specific and results in strong skin test activity in guinea pigs sensitized with heat-killed M. avium. Its gene was cloned by using a previously developed single-probe method and was sequenced. The gene encoded a 194-amino-acid polypeptide with a molecular weight of 21,500. A recombinant Avi-3 antigen expressed in Escherichia coli reacted with monoclonal and polyclonal antibodies raised against the native Avi-3 antigen. To identify epitopes on this protein for immunodiagnostic purposes, various parts of the Avi-3 antigen were expressed as beta-galactosidase fusion proteins, using pUR and pURS expression vectors. The clones screened by both antibody reactivity and T-cell proliferative activity defined fragments with coexisting B- and T-cell epitopes. A B-cell epitope (Asn-176 to Ala-186) and two T-cell epitopes (Glu-75 to Ile-86 and Arg-155 to Leu-164) were thus defined. The synthetic polymerized peptides of the T-cell epitopes were proven to elicit a delayed cutaneous hypersensitivity reaction in guinea pigs. This mapping method would be useful in the development of a subunit vaccine consisting of an immunodominant B-cell epitope linked to a T-cell epitope in the vicinity.
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PMID:Cloning and expression of the gene for the Avi-3 antigen of Mycobacterium avium and mapping of its epitopes. 137 65

The XylS protein is the positive regulator of the TOL plasmid-encoded meta-cleavage pathway for the metabolism of alkylbenzoates in Pseudomonas putida. This protein is activated by a variety of benzoate analogues. To elucidate the functional domains of the regulator and their interactions, several fusions of the XylS C-terminus to MS2 polymerase and of the N-terminus to beta-galactosidase were constructed but all are inactive. In addition, 15 double mutant xylS genes were constructed in vitro by fusing parts of various mutant genes to produce mutant regulators exhibiting C-terminal and N-terminal amino acid substitutions. The phenotypic properties of the parental single mutant genes, and those of the double mutant genes, suggest that the C-terminal region is involved in binding to DNA sequences at the promoter of the meta-cleavage pathway operon, and that the benzoate effector binding pocket includes critical residues present at both the N-terminal and C-terminal ends of the protein. The intraallelic dominance of the Ile229 (Ser229-->Ile) and Val274 (Asp274-->Val) substitutions over the N-terminal His41 (Arg41-->His) substitution, and the intraallelic dominance of Thr45 (Arg45-->Thr) over Ile229 and Val274, support the proposal that these two regions of the regulator interact functionally. Combination of the Leu88 (Trp88-->Leu) and Arg256 (Pro256-->Arg) substitutions did not suppress the semiconstitutive phenotype conferred by Leu88, but resulted in a protein with altered ability to recognize benzoates. In contrast, the Leu88 semiconstitutive phenotype was suppressed by Val288 (Asp288-->Val), and the double mutant was susceptible to activation by benzoates.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:XylS domain interactions can be deduced from intraallelic dominance in double mutants of Pseudomonas putida. 146 13

Influence of rare codons upon gene expression in E. coli was investigated. The chimeric gene was created combining CAT gene and a fragment of the gene, encoding for alpha-domain of beta-galactosidase. The synthetic oligonucleotides were inserted in different parts of the chimeric gene. The constructed synthetic oligonucleotides encoded the same amino acid sequences and contained arginine codons AGG, AGA and CGT in various combinations. It was shown that the presence of rare arginine codons AGG and AGA in the template and their mutual arrangement significantly influence the level of gene expression. At the same time the presence of leucine, isoleucine, glycine and proline rare codons does not cause such an effect. Translation of AGGAGG and AGAAGA sequences was found to lead to the formation of a considerable amount of polypeptides of incomplete length. It was shown that the presence of such a cluster of rare codons effects on the length of specific mRNA.
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PMID:[Rare codons and gene expression in Escherichia coli]. 147 Jan 73

A strategy for the purification and cleavage of chimeric recombinant proteins based on a genetically engineered metal-binding peptide and a human renin cleavage site is described. Vectors were constructed to direct the synthesis of chimeric human immunodeficiency virus (HIV) reverse transcriptase (RT) or beta-galactosidase in Escherichia coli. As shown below, two control chimerics without the metal-binding peptide were also included: 1. Pro-Ile-His-Asp-His-Asp-His-Pro-Phe-His-Leu-Val-Ile-His-Ser-HIV RT 2. Pro-Ile-His-Asp-His-Asp-His-Pro-Phe-His-Leu-Leu-Tyr-Tyr-Ser-HIV RT 3. Pro-Ile-Pro-Phe-His-Leu-Val-Ile-His-Ser-HIV RT 4. Pro-Ile-Pro-Phe-His-Leu-Leu-Tyr-Tyr-Ser-HIV RT 5. Pro-Ile-His-Asp-His-Asp-His-Pro-Phe-His-Leu-beta-galactosidase Both N-terminal sequencing and an enzyme-linked immunosorbent assay utilizing antibodies to the metal-binding peptide were used to characterize the purified chimeric proteins. The relative RT activity of the chimeric protein was indistinguishable from the HIV-1 RT without the fusion sequence, indicating that the metal-binding and renin-cleavage sequences have no effect on the polymerase function of HIV-1 RT. The cleavage by recombinant human renin occurred at the expected site. A future paper will describe results on the use of genetically engineered alternating histidines in the purification of these chimerics by immobilized metal affinity chromatography.
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PMID:Expression and characterization of chimeric rDNA proteins engineered for purification and enzymatic cleavage. 172 60

Molecular analysis of the human beta-galactosidase gene revealed six different mutations in 10 of 11 Japanese GM1-gangliosidosis patients. They were the only abnormalities in each allele examined in this study. A 165-nucleotide duplication (positions 1103-1267) was found in two infantile patients, producing an abnormally large mRNA; one patient was probably a homozygote, and the other was a heterozygote of this mutation. The other two infantile patients had different mutations; a 123 Gly(GGG)----Arg(AGG) mutation in one patient and a 316 Tyr(TAT)----Cys(TGT) mutation in the other. A 201 Arg(CGC)----Cys(TGC) mutation, eliminating a BspMI site, was detected in a late-infantile/juvenile patient; the restriction-site analysis of amplified genomic DNA confirmed his heterozygosity for this mutation. A 51 Ile(ATC)----Thr(ACC) mutation was found in all five adult/chronic patients examined in this study. It created a SauI site, and restriction-site analysis confirmed that four patients were homozygous mutants. The other was a compound heterozygote for this mutation and another 457 Arg(CGA)----Gln(CAA) mutation. These mutant genes expressed markedly decreased or completely deficient enzyme activities in beta-galactosidase-deficient human fibroblasts transformed by adenovirus-SV40 recombinants. We conclude that gene mutations are heterogeneous in GM1-gangliosidosis but that the 51 Ile(ATC)----Thr(ACC) mutation is common among the Japanese adult/chronic cases. Genotype-phenotype correlations in GM1-gangliosidosis are briefly discussed.
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PMID:Human beta-galactosidase gene mutations in GM1-gangliosidosis: a common mutation among Japanese adult/chronic cases. 190

The inducibility of ermC by erythromycin, megalomicin, and celesticetin was tested with both wild-type ermC and several regulatory mutants altered in the 19-amino-acid-residue leader peptide, MGIFSIFVISTVHYQP NKK. In the model test system that was used, the ErmC methylase was translationally fused to beta-galactosidase. Mutational alterations that mapped in the interval encoding Phe-4 through Ile-9 of the leader peptide not only affected induction by individual antibiotics, but did so differentially. The subset of mutations that affected inducibility by the two macrolides erythromycin and megalomicin overlapped and were distinct from the subset of mutations that affected induction by celesticetin. These studies provide a model system for experimentally varying the relative efficiencies with which different antibiotics induce the expression of ermC. The possibility that antibiotics with inducing activity interact directly with the nascent leader peptide was tested by using a chemically synthesized decapeptide, MGIFSIFVIS--, attached at its C-terminus to a solid-phase support. This peptide, however, failed to bind erythromycin in vitro.
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PMID:The ermC leader peptide: amino acid alterations leading to differential efficiency of induction by macrolide-lincosamide-streptogramin B antibiotics. 211 11

Several fusion proteins of our previously chemically synthesized gene encoding the interleukin-2-receptor alpha subunit (IL-2R alpha or Tac protein) were constructed. They were designed in order to be cleavable by cyanogen bromide. Thus, the original internal methionines of the IL-2R alpha were replaced by either alanine, valine, leucine or isoleucine, based on secondary structure predictions. Additionally, aspartate at position 6 was substituted for glutamate in order to stabilize the acid-labile Asp-Pro bond. Direct C-terminal fusion of total beta-galactosidase and portions thereof did not result in substantial amounts of the expected construct. Ternary fusions consisting of beta-galactosidase domains N- and C-terminally fused to the mutant synthetic methionine-free interleukin-2 receptor alpha subunit (synIL-2R alpha) yielded inclusion bodies amounting to 4-7% of the total protein. This first overexpression of a type I membrane receptor can be rationalized by the known beta-galactosidase structure models. The fusion protein can be cleaved with cyanogen bromide, isolated and the resulting synIL-2R alpha detected by Western blot analysis.
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PMID:Overexpression in Escherichia coli of a methionine-free designed interleukin-2 receptor (Tac protein) based on a chemically cleavable fusion protein. 212 81


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