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: UMLS:C0043167 (pertussis)
19,595 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous studies of the S1 subunit of pertussis toxin, an NAD(+)-dependent ADP-ribosyltransferase, suggested that a small amino-terminal region of amino acid sequence similarity to the active fragments of both cholera toxin and Escherichia coli heat-labile enterotoxin represents a region containing critical active-site residues that might be involved in the binding of the substrate NAD+. Other studies of two other bacterial toxins possessing ADP-ribosyltransferase activity, diphtheria toxin and Pseudomonas exotoxin A, have revealed the presence of essential glutamic acid residues vicinal to the active site. To help determine the relevance of these observations to activities of the enterotoxins, the A-subunit gene of the E. coli heat-labile enterotoxin was subjected to site-specific mutagenesis in the region encoding the amino-terminal region of similarity to the S1 subunit of pertussis toxin delineated by residues 6 through 17 and at two glutamic acid residues, 110 and 112, that are conserved in the active domains of all of the heat-labile enterotoxin variants and in cholera toxin. Mutant proteins in which arginine 7 was either deleted or replaced with lysine exhibited undetectable levels of ADP-ribosyltransferase activity. However, limited trypsinolysis of the arginine 7 mutants yielded fragmentation kinetics that were different from that yielded by the wild-type recombinant subunit or the authentic A subunit. In contrast, mutant proteins in which glutamic acid residues at either position 110 or 112 were replaced with aspartic acid responded like the wild-type subunit upon limited trypsinolysis, while exhibiting severely depressed, but detectable, ADP-ribosyltransferase activity. The latter results may indicate that either glutamic acid 110 or glutamic acid 112 of the A subunit of heat-labile enterotoxin is analogous to those active-site glutamic acids identified in several other ADP-ribosylating toxins.
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PMID:Effect of site-directed mutagenic alterations on ADP-ribosyltransferase activity of the A subunit of Escherichia coli heat-labile enterotoxin. 190 25

Exposure of rat heart muscle cells to noradrenaline (1 microM) for 48 hr led to a decrease in the number of beta 1-adrenoceptors of 50% and a concomitant decrease in adenylyl cyclase stimulation by isoprenaline and forskolin of about 60 and 30%, respectively. In addition, the levels of two inhibitory guanine nucleotide-binding protein (Gi protein) alpha-subunits (Gi alpha 40 and Gi alpha 41) were increased in membranes of noradrenaline-treated cells. Evidence is presented that noradrenaline induces this increase by activation of beta-adrenoceptors. First, the noradrenaline action was mimicked by the beta-adrenoceptor agonist isoprenaline. Second, beta-adrenoceptor blockade by timolol but not alpha-adrenoceptor blockade by prazosin prevented the noradrenaline-induced up-regulation of Gi alpha proteins. Furthermore, timolol but not prazosin abolished the noradrenaline-induced down-regulation of beta 1-adrenoceptors and the decreases in receptor-dependent (isoprenaline) and -independent (forskolin) adenylyl cyclase stimulation. The specific protein synthesis inhibitor Pseudomonas exotoxin A was used to study whether the noradrenaline-induced up-regulation of Gi alpha subunits depends on increased synthesis of these proteins. This toxin inhibits peptide chain elongation by ADP-ribosylating elongation factor 2. Treatment of rat heart muscle cells with Pseudomonas exotoxin A (1 ng/ml) completely prevented the noradrenaline-induced increase in Gi alpha proteins, measured by both pertussis toxin-catalyzed ADP-ribosylation and immunoblotting with anti-Gi alpha antibodies. Most importantly, Pseudomonas exotoxin A also completely prevented the noradrenaline-induced decrease in forskolin-stimulated adenylyl cyclase activity. Furthermore, the noradrenaline-induced decrease in isoprenaline-stimulated adenylyl cyclase activity was significantly attenuated by the toxin, although the down-regulation of beta 1-adrenoceptors caused by noradrenaline treatment was not affected. The data presented suggest that prolonged activation of beta-adrenoceptors in rat heart muscle cells, in addition to causing a receptor down-regulation, induces the synthesis of Gi alpha proteins, which then apparently mediate a decreased adenylyl cyclase responsiveness. The data, additionally, suggest that the synthesis of Gi alpha proteins is under control of the activity of the adenylyl cyclase system and that altered levels of these proteins may play a major role in long term regulation of signal transduction by this enzyme.
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PMID:Pseudomonas exotoxin A prevents beta-adrenoceptor-induced upregulation of Gi protein alpha-subunits and adenylyl cyclase desensitization in rat heart muscle cells. 197 Oct 89

In a previous study, all convalescent-phase sera from patients with culture-confirmed legionellosis reacted on immunoblots with a Legionella genus-wide 58-kilodalton (kDa) protein antigen (J.S. Sampson, B.B. Plikaytis, and H.W. Wilkinson, J. Clin. Microbiol. 23:92-99, 1986). The present study was done to immunologically characterize and determine the diagnostic relevance of this purified antigen. The antigen was precipitated from enriched cell extracts with ammonium sulfate and purified by high-pressure liquid chromatography. High-titered rabbit antiserum produced to the purified protein was used to show its presence on immunoblots in the 60-kDa range in 38 Legionella serogroups, representing 23 species, and in 39 non-Legionella bacteria. The antiserum was made specific for Legionella strains by sequential absorptions with Bordetella pertussis, Pseudomonas aeruginosa, and Pseudomonas fluorescens whole cells. Serum from legionellosis patients reacted with both specific and nonspecific epitopes. Results of indirect immunofluorescence experiments showed that neither specific nor nonspecific epitopes of the 60-kDa protein were surface exposed on Legionella cells and that cross-reactive epitopes were variably exposed on non-Legionella bacteria. The 60-kDa protein antigen should be useful in diagnostic tests for legionellosis if care is taken to expose cryptic epitopes and if the tests use or measure only the Legionella-specific epitopes.
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PMID:Purified 60-kilodalton Legionella protein antigen with Legionella-specific and nonspecific epitopes. 244 17

The enzymatic ADP-ribosyltransferase activity associated with the S1 subunit of pertussis toxin is considered to be responsible for its biological effects. Although pertussis toxin has no significant homology to other ADP-ribosylating toxins such as diphtheria toxin and Pseudomonas aeruginosa exotoxin A, the results presented in this paper show that, as for diphtheria toxin and exotoxin A, tryptophan and glutamic acid residues are essential for the enzymatic activities of pertussis toxin. Moreover, a structural motif can be identified around the critical glutamic acid residue. Chemical modification or site-directed deletion or replacement of Trp-26 abolishes ADP-ribosyltransferase and the associated NAD glycohydrolase activities. Both enzymatic activities are also abolished when Glu-129 is deleted or replaced by aspartic acid. Mutations at the Glu-106 position do not significantly reduce the enzymatic activities of the S1 subunit. The mutations do not affect the ability of the different S1 forms to be recognized by a variety of monoclonal antibodies, including neutralizing antibodies. Pertussis toxin containing a deletion or replacement of Trp-26, Glu-129, or both in the S1 subunit should thus be devoid of toxic activities without losing its reactivity with protective antibodies and, therefore, could be safely included in new generation vaccines against whooping cough.
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PMID:Identification of amino acid residues essential for the enzymatic activities of pertussis toxin. 247 88

Type IIb heat-labile enterotoxin (LT-IIb) is produced by Escherichia coli 41. Restriction fragments of total cell DNA from strain 41 were cloned into a cosmid vector, and one cosmid clone that encoded LT-IIb was identified. The genes for LT-IIb were subcloned into a variety of plasmids, expressed in minicells, sequenced, and compared with the structural genes for other members of the Vibrio cholerae-E. coli enterotoxin family. The A subunits of these toxins all have similar ADP-ribosyltransferase activity. The A genes of LT-IIa and LT-IIb exhibited 71% DNA sequence homology with each other and 55 to 57% homology with the A genes of cholera toxin (CT) and the type I enterotoxins of E. coli (LTh-I and LTp-I). The A subunits of the heat-labile enterotoxins also have limited homology with other ADP-ribosylating toxins, including pertussis toxin, diphtheria toxin, and Pseudomonas aeruginosa exotoxin A. The B subunits of LT-IIa and LT-IIb differ from each other and from type I enterotoxins in their carbohydrate-binding specificities. The B genes of LT-IIa and LT-IIb were 66% homologous, but neither had significant homology with the B genes of CT, LTh-I, and LTp-I. The A subunit genes for the type I and type II enterotoxins represent distinct branches of an evolutionary tree, and the divergence between the A subunit genes of LT-IIa and LT-IIb is greater than that between CT and LT-I. In contrast, it has not yet been possible to demonstrate an evolutionary relationship between the B subunits of type I and type II heat-labile enterotoxins. Hybridization studies with DNA from independently isolated LT-II producing strains of E. coli also suggested that additional variants of LT-II exist.
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PMID:Cloning, nucleotide sequence, and hybridization studies of the type IIb heat-labile enterotoxin gene of Escherichia coli. 267 Sep

The in vitro susceptibilities of 1,310 clinical isolates to QA-241, a novel tricyclic quinolone, were evaluated in comparison with susceptibilities to norfloxacin, ofloxacin, enoxacin, and ciprofloxacin. The MICs of QA-241 for 90% of staphylococci, Enterococcus faecalis isolates, and streptococcal species ranged from 1.56 to 6.25 micrograms/ml, and the activity of QA-241 was similar to those of norfloxacin and enoxacin but two to four times less potent than those of ofloxacin and ciprofloxacin. At the concentration of less than or equal to 1.56 micrograms/ml, QA-241 inhibited 90% of Haemophilus influenzae, Bordetella pertussis, Neisseria gonorrhoeae, and gram-negative enteric bacteria except for Serratia marcescens and Citrobacter freundii. QA-241 was moderately active (MIC for 90% of strains tested, 6.25 to 12.5 micrograms/ml) against S. marcescens, Pseudomonas aeruginosa, Xanthomonas maltophilia, and Bacteroides fragilis. The antibacterial activity of QA-241 was roughly comparable to that of enoxacin but two to four times less potent than that of ofloxacin. In systemic infections in mice with gram-positive cocci and gram-negative rods, the efficacy of QA-241 was generally greater than that of norfloxacin and similar to those of ofloxacin and ciprofloxacin. In urinary tract infections in mice with Escherichia coli or Pseudomonas aeruginosa, QA-241 was as active as ofloxacin and more active than norfloxacin but less active than ciprofloxacin. In pulmonary infections in mice with Klebsiella pneumoniae, the effectiveness of QA-241 was similar to that of ofloxacin.
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PMID:In vitro and in vivo activities of QA-241, a new tricyclic quinolone derivative. 267 69

UV irradiation was shown to induce efficient transfer of radiolabel from nicotinamide-labeled NAD to a recombinant protein (C180 peptide) containing the catalytic region of the S-1 subunit of pertussis toxin. Incorporation of label from [3H-nicotinamide]NAD was efficient (0.5 to 0.6 mol/mol of protein) relative to incorporation from [32P-adenylate]NAD (0.2 mol/mol of protein). Label from [3H-nicotinamide]NAD was specifically associated with Glu-129. Replacement of Glu-129 with glycine or aspartic acid made the protein refractory to photolabeling with [3H-nicotinamide]NAD, whereas replacement of a nearby glutamic acid, Glu-139, with serine did not. Photolabeling of the C180 peptide with NAD is similar to that observed with diphtheria toxin and exotoxin A of Pseudomonas aeruginosa, in which the nicotinamide portion of NAD is transferred to Glu-148 and Glu-553, respectively, in the two toxins. These results implicate Glu-129 of the S-1 subunit as an active-site residue and a potentially important site for genetic modification of pertussis toxin for development of an acellular vaccine against Bordetella pertussis.
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PMID:Photolabeling of Glu-129 of the S-1 subunit of pertussis toxin with NAD. 280 35

The toxicity of pertussis toxin is mediated by the ADP-ribosyltransferase activity of subunit S1. To understand the structure-function relationship of subunit S1 and guide the construction of nontoxic molecules suitable for vaccines, we constructed and expressed in Escherichia coli a series of amino-terminal and carboxyl-terminal deletion mutants as well as a number of molecules containing amino acid substitutions. The shortest peptide still retaining enzymatic activity contains amino acids 2-179. Within this region we identified three mutants in which amino acid substitutions abolish the enzymatic activity. Mutation of amino acids 8 and 9 or 50 and 53, located within the region of the S1 subunit of pertussis toxin homologous to cholera toxin, causes loss of enzymatic activity. Outside this homology region, substitution of Glu-129 with glycine or aspartic acid also eliminates the enzymatic activity of the S1 subunit. In this respect, Glu-129 resembles the glutamic acid that is crucial for the catalytic activity of diphtheria and Pseudomonas toxins. Once introduced into the Bordetella pertussis chromosome, the above mutations should lead to the synthesis of nontoxic pertussis toxin molecules suitable for vaccine production.
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PMID:Subunit S1 of pertussis toxin: mapping of the regions essential for ADP-ribosyltransferase activity. 290 32

Exotoxin A (ETA) is recognized as the most toxic product associated with the opportunistic pathogen Pseudomonas aeruginosa. Identification of the amino acids in the polypeptide sequence that are required for toxin activity is critical for vaccine development. By defining the nucleotide sequence of the structural gene of a mutant that encodes an enzymatically inactive ETA (CRM 66), we identified an essential amino acid (His-426), which is involved in the ADP-ribosyltransferase activity associated with functional ETA. A monoclonal antibody that inhibits ETA enzymatic activity in vitro fails to react with ETA variants that have a His 426----Tyr substitution. Several mono-ADP-ribosylating toxins, including diphtheria and pertussis toxins, within the primary amino acid sequences carry a histidine residue that is conserved in spacing and in location with respect to other critical residues. Analysis of the three-dimensional structure of ETA revealed that His-426 is not associated with the proposed NAD+ binding site. These findings should be useful for the design and construction of toxin vaccines.
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PMID:His-426 of the Pseudomonas aeruginosa exotoxin A is required for ADP-ribosylation of elongation factor II. 314 11

Endotoxicity of bacterial vaccines was quantitated in mice by using actinomycin D as potentiating agent. The results were compared with those obtained by the mouse weight gain test. The lethality of Escherichia coli lipopolysaccharide was increased 2,140 times when 12.5 mug of actinomycin D was used. The mean lethal dose values of heated and unheated pertussis vaccines were similar in the actinomycin D enhancement assay, but the unheated vaccine was significantly more toxic in the mouse weight gain test. Acetone-inactivated typhoid vaccine was slightly less toxic than the heat-phenol-inactivated vaccine in both the actinomycin D enhancement assay and mouse weight gain test. Endotoxicity of experimental vaccines prepared by extraction of Pseudomonas aeruginosa strains was high as compared with E. coli lipopolysaccharide. The BALB/c mice were about four times more susceptible than the random bred NIH strain mice. The results indicate that the actinomycin D enhancement assay had the advantages of being more sensitive and probably more specific.
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PMID:Determination of endotoxicity in bacterial vaccines. 463 27


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