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 control of RepFIB replication appears to rely on the interaction between an initiator protein (RepA) and two sets of DNA repeat elements located on either side of the repA gene. Limited N-terminal sequence information obtained from a RepA:beta-galactosidase fusion protein indicates that although the first residue of RepA is methionine, the initiation of translation of RepA occurs from a CTG codon rather than from the predicted GTG codon located further downstream. Overexpressed RepA in trans is capable of repressing a repA:lacZ fusion plasmid in which the expression of the fusion protein is under the control of the repA promoter. The repA promoter has been located functionally by testing a series of repA:lacZ fusion plasmids. Both in vivo genetic tests and in vitro DNA-binding studies indicate that repA autoregulation can be achieved by RepA binding to one or more repeat elements which overlap the repA promoter sequence.
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PMID:Expression and regulation of the RepA protein of the RepFIB replicon from plasmid P307. 144 26

The nucleotide sequence of the virG gene for a transcriptional activator on the agropine-type hairy-root-inducing plasmid pRiA4 was determined. The sequence contained one possible open reading frame. The gene product with a molecular size of 26.5 kDa was identified by an Escherichia coli coupled-transcription-translation system using cloned virG plasmids as templates. However, neither an ATG nor a GTG start codon which could give rise to such a protein was identified in the nucleotide sequence. Instead, TTG was found as a candidate for the start codon. This TTG was preceded, like most other TTG start codons, by both a Shine-Dalgarno (SD) sequence and a T signal which are respectively complementary to the 3'-end region of 16S rRNA and the T psi loop of initiator tRNA. Further evidence for the start at TTG was obtained by gene fusion experiments. When the E. coli lacZ gene, whose expression entirely depends on the transcription and translation from upstream regions, was connected in-phase with virG either directly upstream or downstream of the TTG sequence, only the latter fused gene expressed the beta-galactosidase activity in Agrobacterium cells in response to a plant phenolic compound, acetosyringone. The TTG codon preceded by an SD sequence and a T signal is also conserved in the virG sequences from other three tumor-inducing plasmids previously reported.
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PMID:Putative start codon TTG for the regulatory protein VirG of the hairy-root-inducing plasmid pRiA4. 267 Jun 79

The kinetics for imino hydrogen exchange, at individual base pairs in the DNA sequence corresponding to the lactose operon operator of Escherichia coli, has been examined by NMR saturation recovery measurements as a function of temperature. Three 17-base-pair subsections of the lac operator DNA were chemically synthesized for these studies. The results support our previous observations in the 36-base-pair complete lac operator DNA fragment that has been used in our previous NMR studies. The results indicate faster opening kinetics at a GTG/CAC that is also the site of operator mutations leading to the highest level of constitutive beta-galactosidase synthesis. The GTG/CAC sequence occurs frequently and often symmetrically in prokaryotic and eukaryotic DNA sites where one anticipates specific protein interaction for gene regulation or recombination.
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PMID:Correlation of lac operator DNA imino proton exchange kinetics with its function. 632 23

The regulatory gene camR on the CAM plasmid of Pseudomonas putida (ATCC 17453) negatively controls expression of the cytochrome P-450cam hydroxylase operon (camDCAB) for the camphor degradation pathway and is oriented in a direction opposite to that of the camDCAB operon. In this study, we examined expression of the camR gene by monitoring the beta-galactosidase activity of camR-lacZ translational fusions in P. putida camR and camR+ strains. We found that the camR gene was autogenously regulated by its own product, CamR. To search for an operator site of the camR gene, a cam repressor (CamR)-overproducing plasmid, pHAOV1, was constructed by placing the camR gene under the control of a pL promoter. The translational initiation codon of CamR was changed by site-directed mutagenesis from GTG to ATG to improve translation efficiency. Judging from sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis, the CamR protein was expressed up to about 10% of the soluble protein of CamR-overproducing Escherichia coli JM83/pHAOV1 cells. Results of DNase I footprinting assays using the cell lysate indicated that the CamR repressor covered a single region between the camR gene and the camDCAB operon. Our findings also suggest that the camR gene autogenously regulates its own expression by binding of the gene product, CamR, to the operator, which also serves as an operator of the camDCAB operon.
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PMID:Evidence for autoregulation of camR, which encodes a repressor for the cytochrome P-450cam hydroxylase operon on the Pseudomonas putida CAM plasmid. 825 71

The virulence (vir) genes of Agrobacterium tumefaciens KU12, a Korean strain, were not induced by acetosyringone and the strain showed weak tumor forming ability and broad plant host ranges. We identified complete nucleotide sequence of virG of pTiKU12, an octopine Ti plasmid of this strain. When it was compared with those of other Ti plasmids, pTiKU12 virG contained an open reading frame (ORF) of 726 nucleotides which showed much lower homology (about 77%) than those (above 98%) already known among octopine Ti plasmids and it started with GTG codon instead of TTG found in other Ti plasmids. Only two vir boxes and one promoter region were confirmed in 5'-untranslated region instead of three vir boxes and two promoters which were found in pTiA6 virG. Nevertheless, important amino acids for the functional activity of VirG were so conserved that the virG included in pUCDG could complement a virG mutant Agrobacterium tumefaciens Mx19 in beta-galactosidase activity assays and on plant tumor tests.
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PMID:Molecular characterization of the virulence gene virG of pTiKU 12. 974 25

We evaluated the effect of several genetic factors reported as having a role in the induction of the expression of significant levels of recombinant protein in Bacillus subtilis. We utilized the beta-galactosidase reporter protein from Escherichia coli as our model for measuring the overproduction of heterologous proteins in B. subtilis. The lacZ gene was expressed in B. subtilis using the regulatory region of the subtilisin gene aprE. In this study, we considered factors known to modulate the transcription and translation initiation rates and genetic and mRNA stability. We also consider the effects of different genetic backgrounds, such as degU32 and hpr2, that until now have been studied independently. By changing the native -35 promoter box to the consensus TTGACA sequence of the aprE promoter, a significant 100-fold increase in the beta-galactosidase activity was obtained. On the other hand, changes such as the GTG to ATG start codon, the construction of a consensus AAGGAGG ribosome binding site, and the addition of the cryIIIA transcription terminator at the 3' end of the lacZ gene, produced only marginal effects on the final beta-galactosidase activity.
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PMID:Construction of protein overproducer strains in Bacillus subtilis by an integrative approach. 1123 61

In our previous study, the first structural gene (GGTI) encoding g-glutamyl transpeptidase was cloned and characterized from the fission yeast Schizosaccharomyces pombe, and its transcription, using the GGTI-lacZ fusion gene, containing the 1,085 bp upstream region from the translational initiation point, was found to be enhanced by sodium nitroprusside and L-buthionine-(S,R)-sulfoximine (BSO). In the present work, regulation of the GGTI gene was further elucidated. Non-fermentable carbon sources, such as acetate and ethanol, markedly enhanced the synthesis of beta-galactosidase from the GGTI-lacZ fusion gene. However, its induction by non-fermentable carbon sources appeared to be independent of the presence of the Pap1 protein. Nitrogen starvation also gave rise to induction of GGTI gene expression in a Pap1-independent manner. The three additional fusion plasmids, carrying 754, 421 and 156 bp regions, were constructed. The sequence responsible for the induction by non-fermentable carbon sources and nitrogen starvation was identified to exist within a -421 bp region of the GGTI gene. Taken together, the S. pombe GGTI gene is regulated by non-fermentable carbon sources and nitrogen starvation.
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PMID:The Schizosaccharomyces pombe gene encoding gamma-glutamyl transpeptidase I is regulated by non-fermentable carbon sources and nitrogen starvation. 1576 57

Moraxella catarrhalis strains can express either a UspA2 protein or a UspA2H protein. The latter protein is encoded by a gene that possesses a homopolymeric nucleotide tract containing eight adenine (A) residues [i.e., a poly(A) tract] which is located near the 5' end. A spontaneous UspA2H-negative variant of M. catarrhalis strain O46E, designated O46E.U2V, was found to have a uspA2H poly(A) tract that contained seven A residues. Northern blot analysis of total RNA from the O46E parent strain revealed a readily detectable uspA2H mRNA transcript, whereas little or no uspA2H transcript was detectable in total RNA from the UspA2H-negative variant O46E.U2V. The 5' end of the uspA2H genes from both the O46E parent strain and the O46E.U2V variant were ligated to a promoterless lacZ gene to prepare translational fusions for use as reporter constructs. The level of beta-galactosidase activity expressed by the fusion construct containing eight A residues in its poly(A) tract was 200-fold greater than that obtained with the construct that had seven A residues. Site-directed mutagenesis of the 5' end of the uspA2H gene confirmed that translation was initiated at a GTG codon located 21 nucleotides (nt) upstream of the poly(A) tract. Primer extension analysis determined that the transcriptional start site of the uspA2H gene was located 291 nt upstream from the GTG translational start codon. This poly(A) tract was also found to be present in the uspA2H genes of other M. catarrhalis strains.
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PMID:A UspA2H-negative variant of Moraxella catarrhalis strain O46E has a deletion in a homopolymeric nucleotide repeat common to uspA2H genes. 1722 Mar 16

Tuberculosis (TB) remains a major global health problem, and successful genetic manipulation of mycobacteria is crucial for developing new approaches to study the mechanism of pathogenesis of Mycobacterium tuberculosis (M.tb) and to combat TB. In this study, a series of M.tb furA gene operator/promoter (pfurA) mutants were generated aiming at optimization of the promoter activities in mycobacterial strains. Measured by the lacZ gene-fusion reporter system, change of the initial codon GTG to the preferred ATG resulted in a double increase of beta-galactosidase activity, while a 6-bp substitution in the conserved FurA binding AT-rich region upstream of furA gene led to 4-6 folds increase of the activity. It is significant that combination of both mutations showed about 10 folds of beta-galactosidase activity higher than that of the prototype pfurA. Furthermore, all of the furA promoters were expressed continuously in vivo during intracellular growth of Mycobacterium bovis BCG, and were induced early upon infection in macrophages. Employing the series of pfurA-based differential expression vectors, M.tb chimeric antigen Ag856A2 known for its excellent immunogenicity, was shown to be expressed at different levels in the recombinant Mycobacterium smegmatis and BCG strains. These results indicated that this differential expression system is feasible to express any target antigen of interest in a modular fashion for the study of gene regulation in mycobacterial strains, and also for the development of different recombinant BCG vaccine candidates against TB or other infectious diseases, which would be beneficial for elicitation of optimal immune response.
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PMID:A novel differential expression system for gene modulation in Mycobacteria. 1883 6

Gene therapy for a variety of human cancers containing the mutant p53 (mt-p53) gene has been performed by direct injection of a retroviral or adenoviral vector containing the wild-type p53 (wt-p53) gene. Because many individuals with skin squamous cell carcinoma (SCC) have been shown to carry the p53 gene mutation, these patients are candidates for p53 gene therapy. For this reason, we established ponasterone A-inducible the wild-type p53 (wt-p53) protein-expressing clones by transfecting a ponasterone-inducible vector containing the wt-p53 gene into HSC-1 cells, which harbor the mutated p53 (m/w) at codon 173 (GTG --> TTG in one allele). Upon the induction of the wt-p53 protein, severe growth suppression was observed. Based on the results of the expression patterns of the p21, p16, RB, BAX and Bcl-2 proteins, as well as on the results of senescence-associated beta-galactosidase staining, the suppression was caused by senescence-like growth arrest of the cells. Although it is generally accepted that the suppression of tumor cell growth is caused by p53-induced apoptosis, permanent G1 arrest induced by p53 is also an important part of the growth-suppression mechanism in p53 gene therapy. The present results should expand the possibilities for p53 gene therapy for human skin SCCs containing the mutant p53 gene.
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PMID:Establishment of ponasterone A-inducible the wild-type p53 protein-expressing clones from HSC-1 cells, cell growth suppression by p53 expression and the suppression mechanism. 1900 4


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