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)

Expression of beta-galactosidase in transcriptional fusions with the pps gene (encoding phosphoenolpyruvate [PEP] synthase), the aceBAK operon (encoding malate synthase, isocitrate lyase, and isocitrate dehydrogenase kinase, respectively), and the phs operon (encoding either thiosulfate reductase or a regulatory protein controlling its expression) was studied in Salmonella typhimurium. beta-Galactosidase synthesis in these strains was repressible either by growth in the presence of glucose or by the presence of a fruR mutation, which resulted in the constitutive expression of the fructose (fru) regulon. Five enzymes of gluconeogenesis (PEP synthase, PEP carboxykinase, isocitrate lyase, malate synthase, and fructose-1,6-diphosphatase) were shown to be repressed either by growth in the presence of glucose or the fruR mutation, while the glycolytic enzymes, enzyme I and enzymes II of the phosphotransferase system as well as phosphofructokinase, were induced either by growth in the presence of glucose or the fruR mutation. Overexpression of the cloned fru regulon genes (not including fruR) resulted in parallel repression of representative gluconeogenic, Krebs cycle, and glyoxylate shunt enzymes. Studies with temperature-sensitive mutants of S. typhimurium which synthesized heat-labile IIIFru proteins provided evidence that this protein plays a role in the regulation of gluconeogenic substrate utilization. Other mutant analyses revealed a complex relationship between fru gene expression and the expression of genes encoding gluconeogenic enzymes. Taken together, the results suggest that a number of genes encoding catabolic, biosynthetic, and amphibolic enzymes in enteric bacteria are transcriptionally regulated by a complex catabolite repression/activation mechanism which may involve enzyme IIIFru of the phosphotransferase system as one component of the regulatory system.
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PMID:Altered transcriptional patterns affecting several metabolic pathways in strains of Salmonella typhimurium which overexpress the fructose regulon. 249 6

PEP is an intracellular protein tyrosine phosphatase expressed primarily by cells of hematopoietic origin that can be divided structurally into a catalytic domain and a large carboxy-terminal domain. The carboxy-terminal domain is enriched in proline, glutamic acid, serine, and threonine residues (PEST sequences) and contains a nonperfect tandem repeat sequence enriched in proline residues and a carboxy terminus enriched in basic amino acids. Here we show that PEP is diffusely expressed in lymphoid tissues, consistent with expression by many different cell types. Analysis of the PEP protein identifies a nuclear localization sequence within the extreme carboxy terminus. Transfer of 18 amino acids from the carboxy terminus of PEP to beta-galactosidase conferred nuclear localization, indicating that this sequence was sufficient for nuclear localization. Proteins enriched in PEST sequences are often rapidly degraded. However, pulse-chase analysis indicates that PEP has a half-life of greater than 5 h.
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PMID:Nuclear localization of the PEP protein tyrosine phosphatase. 751 75

We studied the antimutagenic effects of urine on the SOS-inducing activity of mutagenic substances by using a novel test system (umu-test) for detecting DNA damaging agents, which uses a new tester strain (Salmonella typhimurium TA1535/pSK1002). The SOS-inducing activity of chemicals was detected in terms of the level of umu operon expression by measuring beta-galactosidase activity. We first examined the effects of various amounts of urine on SOS responses caused by mitomycin C (MMC). As a result, the urine suppressed beta-galactosidase activity of MMC dose-dependently. A urine concentration of 50 microliters/ml in the medium also suppressed 89.9% of SOS response induced by 0.1 microgram/ml of PEP, 75.6% of that induced by 0.02 microgram/ml of AF2 and 60.9% of that induced by 0.1 microgram/ml of AFB1. In addition, a urine concentration of 50 microliters/ml in the medium also suppressed 85.6% of SOS response by 5 J/m2 of UV irradiation. The observed suppression seemed to be directly related to the SOS responses at a cellular level, rather than to interaction between urine and mutagens, because the urine suppressed SOS responses induced not only by various mutagens but also by UV irradiation. These results suggest that urine works as a strong antimutagen against UV and chemical substances.
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PMID:Suppressive effects of urine on the SOS responses induced by UV and chemical mutagens. 801 82

The role of the Lactobacillus pentosus phosphoenolpyruvate:mannose phosphotransferase system (mannose PTS) in sugar transport and control of sugar utilization was investigated. Growth experiments and measurements of PEP-dependent phosphorylation of sugars, of sugar transport and of catabolic enzyme activity were performed, to compare a wild-type strain with an EIIB(Man) mutant, LPE6, and a ccpA mutant, LPE4. Fructose uptake in wild-type bacteria demonstrated the presence of two fructose-specific PTSs: a high-affinity system, EII(Fru) (K:(m)=52 microM) which is inducible by fructose, and a low-affinity system (K:(m)=300 microM). The latter system was lacking in LPE6 and therefore corresponds to EII(Man). LPE6 was unable to phosphorylate glucose, mannose, N:-acetylglucosamine and 2-deoxyglucose in a PEP-dependent reaction, indicating that these sugars are substrates of EII(Man). Transport and phosphorylation of these compounds was the same in LPE4 and in wild-type bacteria, although growth of LPE4 on these sugars was impaired. In wild-type bacteria and in LPE4 the activity of EII(Fru) was lowered by the presence of EII(Man) substrates in the growth medium, but this decrease was not observed in LPE6. These results indicate that EII(Man) but not CcpA regulates the synthesis of EII(Fru). Mutations in EII(Man) or CcpA resulted in a relief of catabolite repression exerted by EII(Man) substrates on the activity of beta-galactosidase and beta-glucosidase, indicating that EII(Man) and CcpA are important components in catabolite repression in L. pentosus. Fructose-mediated repression of these two enzymes appeared to be correlated with the activity of EII(Fru).
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PMID:Contribution of the phosphoenolpyruvate:mannose phosphotransferase system to carbon catabolite repression in Lactobacillus pentosus. 1123 74

A tetrapeptide derivative Boc-L-Lys(Boc)-L-Arg-L-Asp-L-Ser(Bu(t))-OBu(t) (PEP 1261; Boc is butoxycarbonyl, Bu(t) is t-butyl and OBu(t) is t-butyl ester), synthesized by a solution-phase strategy, exhibited antimicrobial activity against a broad spectrum of micro-organisms at an optimal concentration of 500 mug/ml. Whereas the tetrapeptide salt (L-Lys-L-Arg-L-Asp-L-Ser.HCl) was found to be fairly effective against bacterial cultures, it was not effective against fungal cultures. Comparative growth studies showed that PEP 1261 was equally as potent as the conventional antibiotics kanamycin, streptomycin and actidione for the Gram-negative bacteria Escherichia coli, Pseudomonas alcaligenes and the non-filamentous fungus Saccharomyces cerevisiae (baker's yeast), whereas 62 and 88.9% inhibition were observed for Gram-positive organisms such as Staphylococcus aureus and Bacillus thuringiensis respectively. PEP 1261 might exert its antimicrobial activity by permeabilizing the bacterial membrane, and this was confirmed by an increase in beta-galactosidase activity.
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PMID:A novel synthetic peptide derivative from lactoferrin exhibiting antimicrobial activity. 1499 93