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)

Clinical isolates of rhamnose-positive Yersinia enterocolitica (Y.e.rh+) were compared with typical rhamnose-negative Y. enterocolitica (Y.e.rh-) and with Yersinia pseudotuberculosis. The Y.e.rh+ differed from the Y.e.rh- and Y. pseudotuberculosis in their ability to ferment raffinose and lactose, utilize citrate and in their inability to grow on Hektoen enteric agar at 22 or 37 C, on Salmonella-Shigella agar at 37 C, and scant on xylose-lysine-deoxycholate agar at 37 C. An extensive temperature-dependent profile of characteristics was established for the Y.e.rh+: motility, acetoin production, citrate utilization, growth on Salmonella-Shigella agar, and ampicillin resistance occurred at 22 C but not 37 C; fermentation of melibiose, raffinose, and cellobiose occurred within 24 h at 22 C, but not before 5 days at 37 C; fermentation of rhamnose and production of beta-galactosidase occurred within 24 h at 22 C, but not before 48 h at 37 C; greater resistance to ampicillin, chloramphenicol, streptomycin, kanamycin, carbenicillin, and gentamicin was observed at 22 than 37 C; and good growth on xylose-lysine-deoxycholate agar occurred at 22 but not 37 C. For optimal recovery of Y.e.rh+ from mixed culture, e.g., stools, two MacConkey plates should be inoculated and incubated, one at 37 C, and one at 22 C. Lactose-negative colonies appearing after 48 h on the 22 C MacConkey agar but not the 37 C MacConkey agar should be considered possible Y.e.rh+. Biochemicals should be tested in duplicate, one set incubated at 22 C, one set at 37 C. Antibiotic susceptibility tests of Y.e.rh+ isolates should be incubated at both 37 C and at a lower temperature to allow the greatest expression of resistance of these organisms to the various antibiotics.
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PMID:Temperature-dependent cultural and biochemical characteristics of rhamnose-positive Yersinia enterocolitica. 125 9

The expression of listeriolysin, a major virulence factor of the gram-positive facultative intracellular pathogen Listeria monocytogenes, is positively regulated by a transcriptional activator, the prfA gene product. We had previously shown that mutations within the prfA gene lead to loss of listeriolysin production. In this communication, the regulation of expression of listeriolysin by a specific environmental condition, namely, temperature, was studied in wild-type strains of Listeria monocytogenes. We found that expression of the hemolysis phenotype was thermoregulated. A lisA::lacZ fusion was constructed, and its expression in the wild-type strain was studied at various growth temperatures. The results showed that the fusion beta-galactosidase activity was expressed only when cultures were grown at temperatures above 30 degrees C. This activity could be either specifically repressed or induced, depending on growth temperature. No change in activity was detected in a strain harboring a control beta-galactosidase fusion at the various growth temperatures tested. Northern (RNA) blot analysis of lisA-specific RNA transcripts showed that thermoregulation is manifested at the level of transcription. We also found that the transcription of other PrfA-regulated virulence genes in L. monocytogenes was similarly affected by growth temperature. Hence, as in other facultative intracellular pathogens, Shigella and Yersinia spp., temperature is an important cue in the induction of expression of virulence genes in L. monocytogenes. Our studies revealed that a higher level of regulation is imposed on the PrfA-mediated activation of virulence genes in pathogenic L. monocytogenes.
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PMID:The expression of virulence genes in Listeria monocytogenes is thermoregulated. 173 27

Yersinia pestis is one of many microorganisms responding to environmental iron concentrations by regulating the synthesis of proteins and an iron transport system(s). In a number of bacteria, expression of iron uptake systems and other virulence determinants is controlled by the Fur regulatory protein. DNA hybridization analysis revealed that both pigmented and nonpigmented cells of Y. pestis possess a DNA locus homologous to the Escherichia coli fur gene. Introduction of a Fur-regulated beta-galactosidase reporter gene into Y. pestis KIM resulted in iron-responsive beta-galactosidase activity, indicating that Y. pestis KIM expresses a functional Fur regulatory protein. A cloned 1.9-kb ClaI fragment of Y. pestis chromosomal DNA hybridized specifically to the fur gene of E. coli. The coding region of the E. coli fur gene hybridized to a 1.1-kb region at one end of the cloned Y. pestis fragment. The failure of this clone to complement an E. coli fur mutant suggests that the 1.9-kb clone does not contain a functional promoter. Subcloning of this fragment into an inducible expression vector restored Fur regulation in an E. coli fur mutant. In addition, a larger 4.8-kb Y. pestis clone containing the putative promoter region complemented the Fur- phenotype. These results suggest that Y. pestis possesses a functional Fur regulatory protein capable of interacting with the E. coli Fur system. In Y. pestis Fur may regulate the expression of iron transport systems and other virulence factors in response to iron limitation in the environment. Possible candidates for Fur regulation in Y. pestis include genes involved in ferric iron transport as well as hemin, heme/hemopexin, heme/albumin, ferritin, hemoglobin, and hemoglobin/haptoglobin utilization.
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PMID:Identification and cloning of a fur regulatory gene in Yersinia pestis. 189 28

After incubation at 37 degrees C in the absence of Ca2+ ions, pathogenic strains of Yersinia spp. release large amounts of a set of plasmid-encoded proteins called Yops. The secretion of these proteins, involved in pathogenicity, occurs via a mechanism that involves neither the removal of a signal sequence nor the recognition of a C-terminal domain. Analysis of deletion mutants allowed the secretion recognition domain to be localized within the 48 N-terminal amino acids of protein YopH, within the 98 N-terminal residues of protein YopE, and within the 76 N-terminal residues of YopQ. Comparison of these regions failed to reveal any sequence similarity, suggesting that the secretion signal of Yop proteins is conformational rather than sequential. Hybrid proteins containing the amino-terminal part of YopH fused to either the alpha-peptide of beta-galactosidase or to alkaline phosphatase deprived of its signal sequence were efficiently secreted to the Yersinia culture medium. This observation opens new prospects in using Yersinia spp. as chimeric-protein producers and as potential live carriers for foreign antigens.
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PMID:Secretion of hybrid proteins by the Yersinia Yop export system. 199 87

A genomic library containing DNA fragments of 0.5 to 2 kilobase pairs in length from Yersinia enterocolitica serovar O:8 was constructed in a bacteriophage lambda gt11 expression vector. Mouse antibodies specific for the iron-regulated high-molecular-weight proteins (HMWPs) were used to screen the library. Two positive clones of 1 and 0.5 kilobase pairs, designated A13 and D7, respectively, were detected and isolated. They coded for beta-galactosidase fusion proteins of 151,000 and 138,000 daltons (Da). Antibodies affinity purified on the two recombinant lambda gt11 vectors specifically recognized the smaller HMWP (190,000 Da) and not the larger (240,000 Da). The two cloned DNA fragments were used to construct recombinant amplification plasmid pUC13 and to obtain large amounts of purified A13 and D7 inserts. Southern hybridizations performed with the inserts used as probes revealed that: (i) the two cloned DNA fragments overlap; (ii) only one gene hybridizes with the A13 and D7 inserts; (iii) the gene coding for the HMWP is conserved among all highly pathogenic Yersinia species studied; (iv) this gene is missing in the low-virulence and nonvirulent strains; and (v) transcription of the HMWP gene is induced by iron starvation.
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PMID:The gene coding for the 190,000-dalton iron-regulated protein of Yersinia species is present only in the highly pathogenic strains. 246 94

Yersinia enterocolitica has the capacity to invade the intestinal tissue and to resist the primary host resistance. The former is chromosome coded while the second largely depends on the presence of a 70 kb plasmid called pYV. This plasmid directs the conditional synthesis of high amounts of proteins (YOPs) that are secreted and inserted in the outer membrane. In order to evaluate Y. enterocolitica W22703 as a potential live carrier for immunization, three strains expressing beta-galactosidase (GZ), were tested for their ability to induce an antibody response to this antigen in mice. The first strain contained plasmid pGC1256, a mutated pYV plasmid containing lacZ transcribed from a yop gene promoter. This strain produced high amounts of GZ instead of a YOP protein and was shown to be hypovirulent. The other strains tested were W22703 pYV+ and pYV- containing a derepressed lac operon carried on an independent plasmid. Immunoblot analysis of sera of mice having received by oral inoculation, W22703(pGC1256) or the pYV+ GZ producing strain revealed the presence of antibodies to GZ. The response to GZ after inoculation of W22703(pGC1256) was shown by ELISA to be only slightly inferior to that obtained by subcutaneous injection of GZ. No response was obtained after oral inoculation of the pYV-GZ producing strain. This showed that the presence of pYV was necessary to obtain an antibody response in this system.
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PMID:Yersinia enterocolitica O:9 as a potential live oral carrier for protective antigens. 314 43

The results are given of the ortho-nitrophenol test for beta-galactosidase production (ONPG test) on 588 strains of 123 aerobic species of bacteria, representing 30 genera. Apart from some strains of Erwinia herbicola (synonym Chromobacterium typhiflavum) and of Yersinia spp, these strains were not members of the Enterobacteriaceae, in which family the ONPG test is widely used and well documented. The strains were also tested for acid production from 1, 5, and 10% lactose and the findings are discussed in relation to the ONPG test.
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PMID:The ortho-nitrophenol (ONPG) test and acid from lactose in Gram-negative genera. 458 39

The Analytab system of 20 biochemical tests for identification of Enterobacteriaceae was evaluated in parallel with conventional tests on 128 Enterobacteriaceae, 5 Aeromonas, and 1 Yersinia enterocolitica. The results of tests for H(2)S and indole production, citrate utilization, lysine and ornithine decarboxylase, arginine dihydrolase, nitrate reduction, beta-galactosidase, and fermentation of arabinose, rhamnose, mannitol, and glucose showed almost complete agreement between the two systems. Eighty-eight per cent of Enterobacteriaceae were correctly speciated with the Analytab system; on repeat testing with heavier inocula of organisms failing to ferment glucose initially, the proportion of Enterobacteriaceae correctly speciated became 93%.
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PMID:Evaluation of accuracy of multitest micromethod system for identification of Enterobacteriaceae. 494 Aug 67

Yersinia pestis strain KIM requires plasmid pCD1 for expression of the low calcium response, plague virulence antigen V, and virulence. We constructed Mu d1(Ap lac) insertion mutants of this plasmid which were unable to express the low calcium response. The insertions mapped to a 17-kilobase region of the plasmid. By determining the orientation of the insertions and examining beta-galactosidase production from the Mu d1 lac genes, we determined that this region contains three units of transcription, one of which is transcribed in a direction opposite the direction of transcription of the other two. Transcription of at least two of these units was induced significantly at 37 degrees C compared with 26 degrees C. Ca2+ (2.5 mM) and ATP (18 mM) had no significant effect on the level of expression of the Mu d1 lac genes of these mutants. All insertions in the region strongly reduced production of the V antigen. Insertions from each unit of transcription also reduced virulence in mice.
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PMID:Genetic analysis of the low calcium response in Yersinia pestis mu d1(Ap lac) insertion mutants. 609 9

A Yersinia pestis fur mutation was constructed by insertionally disrupting the fur open reading frame. Analysis of a Fur-regulated beta-galactosidase reporter gene revealed a loss of iron regulation as a result of the fur mutation. trans complementation with the cloned Y. pestis fur gene restored iron regulation. The expression of most iron-regulated proteins was also deregulated by this mutation; however, a number of iron-repressible and two iron-inducible polypeptides retained normal regulation. Mutations in fur or hmsH, a gene encoding an 86-kDa surface protein required for hemin storage, increased the sensitivity of Y. pestis cells to the bacteriocin pesticin. Interestingly, the Y. pestis fur mutant lost temperature control of hemin storage; however, expression of the HmsH polypeptide was not deregulated. When grown with excess iron, a Y. pestis fur mutant possessing the 102-kb pigmentation locus exhibited severe growth inhibition and a dramatic increase in the number of spontaneous nonpigmented chromosomal deletion mutants present at late log phase. These results suggest that the Fur protein of Y. pestis is an important global regulator and that a separate Fur-independent iron regulatory system may exist.
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PMID:Pleiotropic effects of a Yersinia pestis fur mutation. 800 85


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