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)

Most Serratia marcescens strains produce a new type of cytolysin (hemolysin) which is also found in other Serratia species. The hemolytic polypeptide ShlA (M(r) 162 101) is secreted across the outer membrane through the help of the ShlB protein which also involves conversion of an inactive precursor in an hemolytically active form. Both proteins are synthesized with signal sequences which are released during export across the cytoplasmic membrane. Mutants expressing inactive ShlB derivatives are impaired in activation and secretion suggesting a tight coupling between both processes. The region of ShlA for activation and secretion is confined to the N-terminal 16% of the polypeptide which contains the sequence NPNG which is also found in the Proteus hemolysin, the Bordetella pertussis filamentous hemagglutinin and two highly expressed outer membrane proteins of Haemophilus influenzae. Substitution of the first asparagine (N) residue by isoleucine converts the Serratia hemolysin into an inactive secretion incompetent form. It is concluded that this region is recognized by ShlB for activation and secretion of ShlA. The Serratia hemolysin forms defined pores in erythrocyte membranes.
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PMID:Serratia marcescens forms a new type of cytolysin. 147 65

The S1 subunit (Mr 28,000) of pertussis toxin expresses thiol-dependent enzymatic ADP-ribosyltransferase and NAD-glycohydrolase activities. Site-directed mutagenesis experiments were performed on the codon for Cys-41 of this subunit to investigate the role of this residue in both enzymatic activities. Deletion of Cys-41 caused a decrease in both activities below detectable levels, whereas replacement of this residue by serine, glycine, proline, or asparagine only slightly reduced the activities. The enzymatic activities of these mutants were thiol-independent. The deletion of Ser-40, adjacent to Cys-41, again caused reduction of the enzymatic activities to undetectable levels. Steady-state kinetic experiments showed that the kcat of the mutant protein in which Cys-41 was replaced by glycine was nearly identical to the kcat of the parent version. However, the Km for NAD of the mutant was significantly higher relative to that of the wild type version. These results indicate that the side-chain of Cys-41 is not essential for enzymatic activities and that Cys-41 is not involved in the rate of catalysis but is probably located at or close to the NAD-binding site. The introduction of a negative charge at position 41 through the replacement of Cys-41 by either aspartate or glutamate reduced the enzymatic activities to very low but measurable levels, suggesting a charge-charge repulsive interaction between these residues and possibly one or both of the phosphates of NAD. Cys-41 may therefore be located close to the phosphate subsite of the NAD-binding site.
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PMID:The role of cysteine 41 in the enzymatic activities of the pertussis toxin S1 subunit as investigated by site-directed mutagenesis. 215 32

Sulfhydryl-alkylating reagents are known to inactivate the NAD glycohydrolase and ADP-ribosyltransferase activities of the S1 subunit of pertussis toxin, a protein which contains two cysteines at positions 41 and 200. It has been proposed that NAD can retard alkylation of one of the two cysteines of this protein (Kaslow, H.R., and Lesikar, D.D. (1987) Biochemistry 26, 4397-4402). We now report that NAD retards the ability of these alkylating reagents to inactivate the S1 subunit. In order to determine which cysteine is protected by NAD, we used site-directed mutagenesis to construct analogs of the toxin with serines at positions 41 and/or 200. Sulfhydryl-alkylating reagents reduced the ADP-ribosyltransferase activity of the analog with a single cysteine at position 41; NAD retarded this inactivation. In contrast, sulfhydryl-alkylating reagents did not inactivate analogs with serine at position 41. An analog with alanine at position 41 possessed substantial ADP-ribosyltransferase activity. We conclude that alkylation of cysteine 41, and not cysteine 200, inactivates the S1 subunit of pertussis toxin, but that the sulfhydryl group of cysteine 41 is not essential for the ADP-ribosyltransferase activity of the toxin. These results suggest that the region near cysteine 41 contributes to features of the S1 subunit important for ADP-ribosyltransferase activity. Using site-directed mutagenesis, we found that changing aspartate 34 to asparagine, arginine 39 to lysine, and glutamine 42 to glutamate had little effect on ADP-ribosyltransferase activity. However, substituting an asparagine for the histidine at position 35 markedly decreased, but did not eliminate, ADP-ribosyltransferase activity. Chou-Fasman analysis predicted no significant modifications in secondary structure of the S1 peptide with the change of histidine 35 to asparagine. Thus, histidine 35 may interact with a substrate of the S1 subunit without being essential for catalysis.
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PMID:Alkylation of cysteine 41, but not cysteine 200, decreases the ADP-ribosyltransferase activity of the S1 subunit of pertussis toxin. 270 95

Pertussis toxin catalyzes the transfer of ADP-ribose from NAD to the guanine nucleotide-binding regulatory proteins Gi, Go, and transducin. Based on a partial amino acid sequence for a tryptic peptide of ADP-ribosylated transducin, asparagine had been characterized as the site of pertussis toxin-catalyzed ADP-ribosylation. Subsequently, cDNA data for the alpha subunit of transducin indicated that the putative asparagine residue was, in fact, not present in the protein. To determine the amino acid that served as the ADP-ribose acceptor, radiolabel from [adenine-U-14C]NAD was incorporated, in the presence of pertussis toxin, into the alpha subunit of transducin (0.3 mol/mol). An ADP-ribosylated, tryptic peptide was purified and fully sequenced by automated Edman degradation. The amino acid sequence, Glu-Asn 343-Leu-Lys-Asp 346-X-Gly 348-Leu-Phe, corresponds to the cDNA sequence coding the carboxyl-terminal nonapeptide, Glu 342-Phe 350, which includes by cDNA sequence cysteine at position 347. Neither Asn 343 nor Asp 346 appeared to be modified; residue 347 adhered to the sequencing resin. Cysteine, the missing residue, was eluted from the sequencing resin with acetic acid along with 76% of the peptide-associated radioactivity, half of which, presumably ADP-ribosylcysteine, eluted from an anion exchange column between NAD and ADP-ribose; the other half had a retention time corresponding to 5'-AMP. We conclude that Cys 347 and not Asn 343 or Asp 346 is the site of pertusis toxin-catalyzed ADP-ribosylation in transducin.
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PMID:Pertussis toxin-catalyzed ADP-ribosylation of transducin. Cysteine 347 is the ADP-ribose acceptor site. 386 18

The effects of seven lectins with various sugar-specificities on histamine release from rat peritoneal mast cells induced by non-immunologic stimuli were studied. The non-immunologic stimuli used were three basic secretagogues, compound 48/80, bradykinin and PEI6 (polyethylenimine with a molecular weight of 600). In this study, we observed inhibition of the histamine release by Macckia amurensis mitogen and Solanum tuberosum agglutinin (100 micrograms/ml at 37 degrees C for 10 min), which are specific for sialic acid-alpha 2,3-N-acetyl galactosamine (Sia alpha 2,3GalNAc) and N-acetyl glucosamine (GlcNAc) oligomers, respectively. The effects of Phytolacca americana mitogen and Sambucus sieboldiana agglutinin were different. Three lectins specific for mucin type oligosaccharides inhibited the histamine release induced by compound 48/80 but not that induced by bradykinin or PEI6. Since bradykinin and PEI6 additively enhanced the histamine release induced by compound 48/80, they partially shared the same signalling pathways. Glycoproteins with bisecting GlcNAc and Sia residues, as described previously (Jpn. J. Pharmacol. 57, 79-90, 1991), seemed to be one of the action sites for compound 48/80, bradykinin and PEI6. In addition to the direct activation of the pertussis toxin-sensitive G proteins, we propose another mechanism of non-immunologic stimuli via specific glycoproteins on rat peritoneal mast cells. The apparent sugar residues involved were asparagine-linked oligosaccharides with Sia (especially Sia alpha 2,3Gal), GlcNAc oligomers and/or bisecting GlcNAc.
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PMID:Inhibitory effects of sialic acid- or N-acetylglucosamine-specific lectins on histamine release induced by compound 48/80, bradykinin and a polyethylenimine in rat peritoneal mast cells. 751 32

Expression of the OmpU outer membrane protein of Vibrio cholerae is positively regulated by toxR, which also regulates critical virulence factors such as cholera toxin and the toxin-coregulated pilus colonization factor. In this study, we have characterized the 38-kDa OmpU protein and investigated its role in the adhesion of V. cholerae to mammalian cells. The amino-terminal sequence of OmpU has similarity with the sequences of Haemophilus influenzae HMW1 and HMW2 adhesins, which, in turn, also have similarity with the sequence of Bordetella pertussis filamentous hemagglutinin. A monoclonal antibody directed against FHA recognized both V. cholerae OmpU and Escherichia coli OmpA, and polyclonal anti-OmpU antibodies recognized FHA and E. coli OmpA, suggesting the existence of common epitopes among these proteins. OmpU was strongly recognized by convalescent-phase serum from volunteers experimentally infected with virulent V. cholerae strains, indicating that OmpU is immunogenic and produced in vivo. OmpU selectively bound to fibronectin and to an arginine-glycine-asparagine (RGD) tripeptide but not to other matrix glycoproteins tested such as collagen or laminin. Antibodies directed against OmpU or their F(ab)2 fragments completely inhibited adhesion of several V. cholerae strains to HeLa, HEp-2, Caco-2, and Henle 407 epithelial cells and also inhibited intestinal colonization and conferred protection in newborn mice against both biotypes (El Tor and classical) of V. cholerae O1. Collectively, these data indicate that OmpU has adhesive properties which may play a role in the pathogenesis of cholera.
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PMID:The OmpU outer membrane protein, a potential adherence factor of Vibrio cholerae. 759 Oct 82

Pertussis toxin is one of several virulence factors produced by Bordetella pertussis, the etiologic agent of whooping cough. Pertussis toxin is an oligomeric A-B class toxin composed of an ADP-ribosyltransferase S1 (A) subunit and a B oligomer containing lectin-like binding domains. The carbohydrate binding specificity of the B oligomer is for sialooligosaccharide sequences expressed on target cell receptors and asparagine-linked glycans found in many serum glycoproteins. Pertussis toxin also has the ability to bind to the inert surfaces of culture tubes. In this report we present data showing that pertussis toxin binding to polypropylene microcentrifuge tubes was enhanced in a time- and concentration-dependent manner by the addition of soluble glycoprotein or oligosaccharide receptor analogs. Evidence obtained using the hydrophilic and hydrophobic surfaces of Gel Bond electrophoresis casting film indicated that receptor-enhanced binding was likely due to hydrophobic interactions. Hydrophobic binding of the isolated B oligomer of pertussis toxin was enhanced only in the presence of high concentrations of glycoproteins. Therefore, the S1 (A) subunit of pertussis holotoxin appears to play a role in receptor-enhanced hydrophobic binding. We propose, therefore, that pertussis toxin binding to its receptors may expose or preferentially orient hydrophobic residues that may contribute to the functional association of the toxin with host cell plasma membranes and delivery of the S1 subunit to its intracellular target.
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PMID:Hydrophobic binding of pertussis toxin is enhanced by oligosaccharide receptors. 768 2

A rat glycohydrolase which catalyzes the hydrolysis of ADP-ribosylarginine was expressed in Escherichia coli and purified to homogeneity for characterization of its enzymatic properties. The purified glycohydrolase catalyzed the hydrolysis of N-glycoside linked ADP-ribosylarginine on the alpha-subunits of stimulatory GTP-binding proteins (Gs) and cholera toxin A1-subunit that had been modified by cholera toxin and NAD. Nonmuscle actin of which an arginine residue was ADP-ribosylated by botulinum C2 toxin also served as a substrate of the glycohydrolase. On the other hand, the glycohydrolase did not hydrolyze ADP-ribosylated cysteine on the alpha-subunits of pertussis toxin-substrate GTP-binding proteins, ADP-ribosylated diphthamide on elongation factor 2, or ADP-ribosylated asparagine on rho GTP-binding proteins. The rate of the reaction catalyzed by the glycohydrolase was affected by nucleotide-binding form of the ADP-ribosylated substrate proteins; the GDP-bound form of the modified Gs-alpha was more rapidly hydrolyzed than the guanosine 5'-(3-O-thio)triphosphate-bound form. Interestingly, the glycohydrolase activity was markedly inhibited by mM order concentration of ATP in addition to ADP-ribose, the product of the enzyme reaction, though ADP had no inhibitory effect on the activity. Moreover, alpha NAD, but not beta NAD, inhibited the enzyme activity, suggesting that the glycohydrolase reaction was stereospecific for the alpha-anomer.
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PMID:ADP-ribosylarginine glycohydrolase catalyzing the release of ADP-ribose from the cholera toxin-modified alpha-subunits of GTP-binding proteins. 789 43

We have mutated the aspartate residue in the putative second transmembrane spanning domain of the alpha 2A-adrenergic receptor (alpha 2AAR) to the non-negatively charged asparagine (D79N) and glutamine (D79Q) and the negatively charged glutamate (D79E) residue in an effort to better characterize the role of this residue, highly conserved among G-protein-coupled receptors, in Na+ regulation of ligand binding and in receptor G-protein coupling. Allosteric modulation of receptor-ligand interactions by Na+ is retained by the D79E alpha 2AAR but lost upon mutation to the uncharged D79N and D79Q residues. Loss of allosteric effects of Na+ is paralleled by a complete loss of retrograde information transfer from G-proteins to alpha 2AAR in AtT20 cells, measured via the sensitivity of radiolabeled agonist binding to Gpp(NH)p. In contrast to the complete elimination of retrograde signaling via the D79N and D79Q alpha 2AAR, anterograde information transfer from receptor to G-protein is modified in a more subtle quantitative way, since agonist-stimulated GTPase activity via D79N and D79Q alpha 2AAR, although apparently attenuated compared to wild type and D79E alpha 2AAR, is no less than the GTPase activity elicited by endogenous somatostatin receptors in AtT20 cells. These data indicate that a negative charge at amino acid residue 79 forecasts sensitivity to allosteric regulation by monovalent cations and its mutation to non-negatively charged residues elicits a nonparallel modulation of receptor-->G-protein versus G-protein-->receptor communication between alpha 2AAR and pertussis toxin-sensitive GTP-binding proteins.
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PMID:Mutation of an aspartate residue highly conserved among G-protein-coupled receptors results in nonreciprocal disruption of alpha 2-adrenergic receptor-G-protein interactions. A negative charge at amino acid residue 79 forecasts alpha 2A-adrenergic receptor sensitivity to allosteric modulation by monovalent cations and fully effective receptor/G-protein coupling. 796 41

Recently it was demonstrated that the metabolism of both glycoproteins and sphingo(glyco)lipids is dependent upon the state of enterocytic differentiation of HT-29 cells. Furthermore, it was shown that undifferentiated HT-29 cells display an important autophagic sequestration, controlled by a heterotrimeric Gi3 protein. In order to correlate the metabolism of sphingo(glyco)lipids with the extent of autophagic sequestration, we have incubated undifferentiated and differentiated HT-29 cells with tritium-labelled GM1 ganglioside and sphingosine in the absence and presence of pertussis toxin (an inhibitor of autophagic sequestration) or asparagine (an inhibitor of autophagic vacuole maturation). In addition, undifferentiated HT-29 cells transfected with a cDNA encoding the G alpha i3 protein (cells expressing an amplified autophagic pathway) were labelled with both GM1 and sphingosine. The results show that the catabolism of sphingo(glyco)lipids is dramatically enhanced in parallel with the increase of the autophagic pathway while at the same time their biosynthesis is reduced. The inhibition of autophagy in both undifferentiated cells and alpha i3-overexpressing cells restores sphingo(glyco)lipid metabolism, as normally expressed in differentiated cells, as well as in other mammalian cell types. We conclude that autophagy plays an important role in governing the metabolic fate of sphingo(glyco)lipids in HT-29 cells. Since autophagy regulates the N-linked glycoprotein metabolism in this cell line, our results corroborate the idea that glycolipid and glycoprotein metabolisms are controlled by similar mechanisms.
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PMID:The metabolism of sphingo(glyco)lipids is correlated with the differentiation-dependent autophagic pathway in HT-29 cells. 864 85


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