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)

Weaver, Judith R. (Iowa State University, Ames), and P. A. Pattee. Inducible resistance to erythromycin in Staphylococcus aureus. J. Bacteriol. 88:574-580. 1964.-The dissociated resistance of Staphylococcus aureus to erythromycin was examined and was found to possess the characteristics of an inducible enzyme. The induction of resistance to high concentrations of erythromycin in S. aureus occurred only after prior exposure to subinhibitory concentrations of erythromycin. The only macrolide antibiotic examined which induced resistance was erythromycin, and the resistance of induced populations was rapidly lost when they were grown in the absence of this antibiotic. Induction did not occur when protein synthesis was inhibited by either chloramphenicol or histidine starvation of a histidine auxotroph. The macrolide antibiotics inhibited the induction of resistance at the same minimal concentrations required to inhibit growth and induced synthesis of beta-galactosidase. Therefore, the mode of action of the macrolide antibiotics is to inhibit protein synthesis, and the induction of resistance overcomes this inhibition in some manner which is associated with the synthesis of new protein.
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PMID:INDUCIBLE RESISTANCE TO ERYTHROMYCIN IN STAPHYLOCOCCUS AUREUS. 1420 90

Culturable cells and non-culturable cells of fecal coliforms, obtained by irradiation at 312 nm were submitted to the combined stress conditions of salinity and starvation. After 14 days, beta-galactosidase activity of UV-irradiated cells was at least twice the value of non-irradiated cells. UV-irradiated cells thus contribute more than non-irradiated cells to the enzyme assay after incubation in saline water. This finding is essential for the interpretation of quantitative investigations into the environment using enzymatic methods.
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PMID:On the relationship between the physiological state of bacteria and rapid enzymatic assays of fecal coliforms in the environment. 1451 61

To develop reporter systems to study the regulation of protein degradation in innervated muscle, we have used strains of the nematode Caenorhabditis elegans containing transgenes that fuse lacZ or green fluorescent protein (GFP) coding regions to muscle-specific promoter/enhancer regions, such that the fusion proteins are expressed exclusively in body-wall and vulval muscle cells. The starvation-induced degradation of the beta-galactosidase reporter protein is quantitatively similar to that of two endogenous muscle proteins, arginine kinase and adenylate kinase. A soluble GFP in the muscle cytosol is degraded during starvation, but when GFP is fused to a full-length myosin heavy chain and incorporated into myofibrils, it is resistant to starvation-induced degradation. This suggests that under some conditions soluble muscle proteins may be extensively catabolized in preference to the proteins of the contractile fibers.
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PMID:Degradation of transgene-coded and endogenous proteins in the muscles of Caenorhabditis elegans. 1463 38

The intracellular concentration of the Escherichia coli factor for inversion stimulation (Fis), a global regulator of transcription and a facilitator of certain site-specific DNA recombination events, varies substantially in response to changes in the nutritional environment and growth phase. Under conditions of nutritional upshift, fis is transiently expressed at very high levels, whereas under induced starvation conditions, fis is repressed by stringent control. We show that both of these regulatory processes operate on the chromosomal fis genes of the enterobacteria Klebsiella pneumoniae, Serratia marcescens, Erwinia carotovora, and Proteus vulgaris, strongly suggesting that the physiological role of Fis is closely tied to its transcriptional regulation in response to the nutritional environment. These transcriptional regulatory processes were previously shown to involve a single promoter (fis P) preceding the fis operon in E. coli. Recent work challenged this notion by presenting evidence from primer extension assays which appeared to indicate that there are multiple promoters upstream of fis P that contribute significantly to the expression and regulation of fis in E. coli. Thus, a rigorous analysis of the fis promoter region was conducted to assess the contribution of such additional promoters. However, our data from primer extension analysis, S1 nuclease mapping, beta-galactosidase assays, and in vitro transcription analysis all indicate that fis P is the sole E. coli fis promoter in vivo and in vitro. We further show how certain conditions used in the primer extension reactions can generate artifacts resulting from secondary annealing events that are the likely source of incorrect assignment of additional fis promoters.
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PMID:Growth phase-dependent regulation and stringent control of fis are conserved processes in enteric bacteria and involve a single promoter (fis P) in Escherichia coli. 1467 32

Here we developed the new expression system P(Zn) zitR, based on the regulatory signals (P(Zn) promoter and zitR repressor) of the Lactococcus lactis zit operon, involved in Zn(2+) high-affinity uptake and regulation. A P(Zn) zitR-controlled expression vector was constructed, and expression regulation was studied with two reporter genes, uspnuc and lacLM; these genes encode, respectively, a protein derived from Staphylococcus aureus secreted nuclease and Leuconostoc mesenteroides cytoplasmic beta-galactosidase. Nuclease and beta-galactosidase activities of L. lactis MG1363 cells expressing either uspnuc or lacLM under the control of P(Zn) zitR were evaluated on plates and quantified from liquid cultures as a function of divalent metal ion, particularly Zn(2+), availability in the environment. Our results demonstrate that P(Zn) zitR is highly inducible upon divalent cation starvation, obtained either through EDTA addition or during growth in chemically defined medium, and is strongly repressed in the presence of excess Zn(2+). The efficiency of the P(Zn) zitR expression system was compared to that of the well-known nisin-controlled expression (NICE) system with the same reporter genes cloned under either P(Zn) zitR or P(nisA) nisRK control. lacLM induction levels reached with both systems were on the same order of magnitude, even though the NICE system is fivefold more efficient than the P(Zn) zitR system. An even smaller difference or no difference was observed after 3 h of induction when nuclease was used as a reporter for Western blotting detection. P(Zn) zitR proved to be a powerful expression system for L. lactis, as it is tightly controlled by the zinc concentration in the medium.
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PMID:New expression system tightly controlled by zinc availability in Lactococcus lactis. 1534 26

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

Translating ribosomes can pass through a stretch of messenger RNA without translating and resume protein chain elongation after the bypassed region. We previously investigated the stimulation of bypassing when the codon in the ribosome [corrected] A-site called for an aminoacyl-tRNA species in short supply. Here, we investigate bypassing in unstarved, growing cells. A collection of lacZ bypass reporters was constructed with nearly all the sense codons as the "takeoff site", each with its matched landing site 16 nucleotides downstream in the beta-galactosidase reading frame. Beta-galactosidase [corrected] synthesis in unstarved cells carrying these reporters was found to vary over a large range. The takeoff sites UUU and AGG yielded unusually high enzyme activities, sufficient for protein sequence analysis; in these cases, sequencing (by Edman degradation or by mass spectrometry) confirmed that the synthesis of lacZ protein occurred through the 16 nt bypass from takeoff to landing site. Thus, bypassing occurs spontaneously under normal conditions, and is not limited to the pathology of amino acid starvation. Indirect evidence suggests that most of the lower enzyme activities of the rest of the collection also reflects bypassing. Another collection of reporters was made with [corrected] various triplets in the A-site [corrected] the codon immediately following a UUC [corrected] takeoff triplet. Spontaneous bypassing in representatives of this collection varied roughly inversely with the abundance of the tRNA encoded at the A-site. For two A-site codons tested, introduction of additional copies of the relevant tRNA gene on a second plasmid reduced spontaneous bypassing. We conclude that any pause with the A-site empty stimulates bypassing. From the P-site and A-site effects on bypassing, we estimated the average frequency of ribosome takeoff; from this, we calculate that the probability that a ribosome will succeed in translating the entire lacZ coding sequence is about 0.73, in agreement with earlier, independent estimates.
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PMID:Spontaneous ribosome bypassing in growing cells. 1589 Jan 94

The rel gene is responsible for the maintenance of the level of (p)ppGpp in bacteria under nutrient starvation. This phenomenon known as stringent response plays an important role during survival of the microorganisms in stationary phase. We have cloned 1.6 kb upstream sequence of rel gene of Mycobacterium tuberculosis in a shuttle vector pSD5B containing promoterless lacZ gene and promoter activity was observed in Mycobacterium smegmatis cells by blue/white selection and was measured by beta-galactosidase assay. In order to delineate the minimal promoter element of rel gene, a 200 bp fragment from this 1.6 kb upstream sequence was further cloned in promoterless lacZ shuttle vector pSD5B and promoter activity was observed in M. smegmatis cells in similar way. The 200 bp promoter fragment was found to be mycobacterium specific and did not respond when transformed in Escherichia coli. The +1 transcription start site was determined by primer extension method. The -10 promoter region was identified to be TATCCT. The three T bases when mutated, showed a remarkable decrease in the lacZ expression thus confirming the -10 region. The translation start site has also been identified by site directed frame shift mutagenesis. It appears that this rel promoter can be used for expression of proteins in mycobacteria.
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PMID:Identification and characterization of rel promoter element of Mycobacterium tuberculosis. 1592 71

The expression of the Bacillus subtilis W23 tar genes specifying the biosynthesis of the major wall teichoic acid, the poly(ribitol phosphate), was studied under phosphate limitation using lacZ reporter fusions. Three different regulation patterns can be deduced from these beta-galactosidase activity data: (i) tarD and tarL gene expression is downregulated under phosphate starvation; (ii) tarA and, to a minor extent, tarB expression after an initial decrease unexpectedly increases; and (iii) tarO is not influenced by phosphate concentration. To dissect the tarA regulatory pattern, its two promoters were analysed under phosphate limitation: The P(tarA)-ext promoter is repressed under phosphate starvation by the PhoPR two-component system, whereas, under the same conditions, the P(tarA)-int promoter is upregulated by the action of an extracytoplasmic function (ECF) sigma factor, sigma(M). In contrast to strain 168, sigma(M) is activated in strain W23 in phosphate-depleted conditions, a phenomenon indirectly dependent on PhoPR, the two-component regulatory system responsible for the adaptation to phosphate starvation. These results provide further evidence for the role of sigma(M) in cell-wall stress response, and suggest that impairment of cell-wall structure is the signal activating this ECF sigma factor.
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PMID:Analysis of teichoic acid biosynthesis regulation reveals that the extracytoplasmic function sigma factor sigmaM is induced by phosphate depletion in Bacillus subtilis W23. 1615 Dec 14

The senescence associated-beta-galactosidase (SA-betaG) assay has become one of the most commonly used markers of cell-aging. However, the reliability of the assay is questionable because the enzyme is a non-specific marker for cell-aging. In this study, we found that the SA-betaG activity increased with cell age as well as in confluent quiescent cells or cells under serum starvation, and in cells treated with H2O2. Importantly, we found that SA-betaG activity was irreversibly increased in the senescent cells or H2O2-teated cells, but was reversible in quiescent cells induced by serum starvation or confluence. Using fluorescein di-beta-d-galactopyranoside (FDG) method for SA-betaG detection, we showed that senescent human foreskin fibroblast Hs68 cells did not express a specific enzyme that has a maximal activity at pH 6.0. In the pH profile of the cellular betaG activity in senescent Hs68 cells, only a single peak was found (with maximum at pH 4.6), and no addition peak was found at or around pH 6.0 that could be attributed to the SA-betaG activity. These results support the contention that SA-betaG is the lysosomal betaG that is detectable at suboptimal pH (i.e. pH 6.0) and demonstrate that cell-aging is not the only factor that can increase SA-betaG activity, rendering SA-betaG activity unspecific for cell-aging. Thus, the assay for cell-aging is only reliable when these confounding factors are controlled or excluded.
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PMID:The limitations and validities of senescence associated-beta-galactosidase activity as an aging marker for human foreskin fibroblast Hs68 cells. 1615 6


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