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

Five Bordetella pertussis strains of phase I were grown in conventional casamino-acid medium and in media modified by adding high concentrations of MgSO4 or nicotinic acid. Cells grown in high-magnesium media (in the C-mode) had only about 4% of the protective antigen (PA) and 6% of the histamine-sensitising factor (HSF) of cells from the normal medium. Envelopes from C-mode organisms when examined by SDS-PAGE showed a loss of 28K and 30K polypeptide bands. Similar parallel losses of PA, HSF and 28K and 30K bands were found with cells from the high-nicotinic-acid medium. A medium with a high concentration of nicotinamide gave cells with normal amounts of PA, HSF and 28K and 30K bands. Growth in high concentrations of Na2SO4 caused partial losses of PA, HSF and 28K and 30K bands, while a high-succinate medium gave cells with somewhat diminished PA and HSF but without appreciable attenuation of the 28K and 30K bands. Because of the close correlation between the presence or absence of PA, HSF and 28K and 30K envelope polypeptides, it is suggested that the latter may represent or be closely associated with the components responsible for PA and HSF activities.
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PMID:Loss of protective antigen, histamine-sensitising factor and envelope polypeptides in cultural variants of Bordetella pertussis. 5 40

We have cloned and sequenced new Escherichia coli genes which belong to member of the family of environmentally responsive two-component system and named evgA and evgS because their amino acid sequences were found the most homologus to the Bordetella pertussis bvgA and bvgS. They were mapped at 51 min. and extending from 6B9 to 7G9 in the Kohara miniset library of the E. coli chromosome. In fact, both EvgA and EvgS proteins predicted from their DNA sequences were identified in the in vitro coupled transcription translation system. When the evgA and evgS were expressed on multiple copy plasmid in an envZ deletion strain, ompC expression was also regulated by temperature, MgSO4 and nicotinic acid, by which virulence of Bordetella pertussis is controlled via BvgA and BvgS. These results indicate that ompC expression was controlled by in vivo cross-talk via EvgA and EvgS which can work in E. coli the same way as BvgA and BvgS.
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PMID:Cloning and sequence analysis of the evgAS genes involved in signal transduction of Escherichia coli K-12. 128 96

Adenylyl cyclase in rat adipose cells is stimulated by ligands for Rs receptors (e.g. isoproterenol) and inhibited by ligands for Ri receptors (e.g. adenosine). In contrast, Rs receptors mediate inhibition and Ri receptors mediate augmentation of insulin-stimulated glucose transport activity by a process independent of changes in cellular cAMP-dependent protein kinase activity [Kuroda M., Honnor R. C., Cushman S. W., Londos C. and Simpson I. A. (1987) J. biol. Chem. 262, 245-253]. The present study examines the possible role of G-proteins in the regulation of insulin-stimulated glucose transport activity by Rs and Ri receptors. First, conditions were established that permit intoxication of isolated rat adipocytes by cholera and pertussis toxins without compromising cell integrity. Effectiveness of toxin treatment was monitored by examining adenylyl cyclase activity in isolated plasma membranes. Secondly, neither toxin interfered with the ability of a maximal concentration insulin to initiate the glucose transport response. Thirdly, pertussis toxin eliminated the augmenting effects of adenosine on insulin-stimulated glucose transport activity, but enhanced the inhibitory effects of isoproterenol. Findings with ligands for other Ri receptors (nicotinic acid and prostaglandin E2) mirrored those with adenosine. Finally, cholera toxin elicited a modest depression of transport activity, and only in the absence of an Ri ligand (e.g. adenosine). Furthermore, in contrast to the enhanced stimulation of adenylyl cyclase by isoproterenol and GTP, cholera toxin eliminated the inhibitory effect of isoproterenol on transport activity. The augmentative effects of adenosine on transport activity were unchanged. Measurements of (-/+cAMP) cAMP-dependent protein kinase activity ratios reinforce the notion that modulation of glucose transport activity is independent of changes in cAMP. We conclude that regulation of glucose transport activity by Rs and Ri receptors is mediated by the G-proteins, Gs and Gi (or other toxin substrates), respectively. Inasmuch as such regulation occurs at the plasma membrane and appears to be cAMP-independent, it is suggested that glucose transporters may be direct targets for receptor: G-protein interactions.
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PMID:Cholera and pertussis toxins modify regulation of glucose transport activity in rat adipose cells: evidence for mediation of a cAMP-independent process by G-proteins. 131 47

The expression of many of the known virulence determinants of Bordetella pertussis is coordinately regulated by the vir regulatory locus and reduced in response to environmental signals called modulators. We have previously identified eight TnphoA gene fusions in B. pertussis in which the expression of alkaline phosphatase was maximal in the absence of the modulators nicotinic acid and MgSO4. We have termed the genes identified by these fusions vir-activated genes. Here we report the characterization of these TnphoA mutant strains. Four fusion strains were defective in known virulence determinants. For one of these, fusion strain SK39, Southern blot hybridization demonstrated that TnphoA was inserted in the S1 subunit gene of pertussis toxin. Hemagglutination assays, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and immunoblots identified three fusions strains, SK16, SK75, and SK91, that were defective in filamentous hemagglutinin. Whereas all three filamentous hemagglutinin-defective mutants showed either normal or enhanced colonization, the pertussis toxin-defective mutant showed a marked defect in pulmonary persistence. Of the four other fusion strains, two were deficient in outer membrane proteins. One of these, strain SK8, was defective in a major outer membrane protein of 95 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This strain colonized mouse lungs less well and did not induce lymphocytosis after aerosol challenge. The other strain, SK34, was defective in four outer membrane proteins, three of which were detectable only on a Western blot with polyclonal sera against B. pertussis. Two of our gene fusion strains did not show any defect in identifiable vir-regulated proteins.
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PMID:Characterization of vir-activated TnphoA gene fusions in Bordetella pertussis. 165 62

Coordinate regulation of gene expression in Bordetella pertussis is controlled by the products of the vir locus, BvgA and BvgS. In the presence of modulating signals such as MgSO4 and nicotinic acid, expression of vir-activated genes (vag) is reduced, while expression of vir-repressed genes (vrg) is maximal. We have cloned one of these vir-repressed genes, vrg-6, in Escherichia coli. DNA sequencing has shown that vrg-6 is contained on a single EcoRI restriction endonuclease fragment and is predicted to code for a protein of 105 amino acids with a molecular weight of 11,441. The predicted protein product appears to have two domains, one consisting of seven hydrophobic proline-rich pentameric repeats and the other consisting of five alkaline trimeric repeats. Southern blot analysis has revealed vrg-6-homologous sequences in the chromosomes of Bordetella bronchiseptica and Bordetella parapertussis, but, unlike Bordetella pertussis, these species do not express vrg-6-homologous RNA when grown under modulating conditions. In order to assess the role of vrg gene products in B. pertussis pathogenesis, two 18323 derivatives which harbor TnphoA insertions in vrg genes were analyzed in a mouse model of respiratory infection. Strain SK6, which carries a vrg-6::TnphoA mutation, failed to induce lymphocytosis and was significantly less able to colonize lungs and trachea than its parent strain 18323 or than SK18, which harbors a TnphoA fusion in the vrg-18 locus. This is the first evidence that a vir-repressed gene may play an important role in the virulence of B. pertussis and the pathogenesis of whooping cough.
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PMID:A vir-repressed gene of Bordetella pertussis is required for virulence. 173 Apr 91

The products of the bvgAS locus coordinately regulate expression of the Bordetella pertussis virulence regulon in response to environmental signals. Transcription of bvgAS-activated genes is nearly eliminated by several modulating conditions, including the presence of sulfate anion or nicotinic acid and growth at low temperature. We have isolated spontaneous mutations that result in the constitutive synthesis of multiple bvg-regulated loci. Several of these mutations have been analyzed and were found to result from single-nucleotide substitutions within bvgS, in a region encoding a 161-amino-acid segment which links the transmembrane sequence with cytoplasmic domains that appear to be involved in signaling events. The effect of signal transduction mutations in Escherichia coli was determined by measuring the expression of an fhaB-lacZYA transcriptional fusion, and that in B. pertussis was determined by measuring expression of both fhaB-cat and ptxA3201-cat fusions. The constitutive mutations have little effect on fhaB-cat or fhaB-lacZYA expression in the absence of modulating signals but result in a nearly complete insensitivity to MgSO4, nicotinic acid, or growth at low temperature. Furthermore, insertion and deletion mutations in bvgS sequences encoding the periplasmic domain eliminate activity of the wild-type product, whereas constitutive mutants remain active. In B. pertussis cultures grown in Stainer-Scholte broth, expression of ptxA3201-cat differed from that of fhaB-cat in several respects. In combination with a wild-type bvgS allele, ptxA3201-cat expression required the addition of heptakis-(2,6-O-dimethyl)-beta-cyclodextrin, and this requirement was eliminated by the presence of the constitutive mutations.
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PMID:Constitutive sensory transduction mutations in the Bordetella pertussis bvgS gene. 173 30

Adenylate cyclase activity in isolated rat liver plasma membranes was inhibited by NADH in a concentration-dependent manner. Half-maximal inhibition of adenylate cyclase was observed at 120 microM concentration of NADH. The effect of NADH was specific since adenylate cyclase activity was not altered by NAD+, NADP+, NADPH, and nicotinic acid. The ability of NADH to inhibit adenylate cyclase was not altered when the enzyme was stimulated by activating the cyclase was not altered when the enzyme was stimulated by activating the Gs regulatory element with either glucagon or cholera toxin. Similarly, inhibition of Gi function by pertussis toxin treatment of membranes did not attenuate the ability of NADH to inhibit adenylate cyclase activity. Inhibition of adenylate cyclase activity to the same extent in the presence and absence of the Gpp (NH) p suggested that NADH directly affects the catalytic subunit. This notion was confirmed by the finding that NADH also inhibited solubilized adenylate cyclase in the absence of Gpp (NH)p. Kinetic analysis of the NADH-mediated inhibition suggested that NADH competes with ATP to inhibit adenylate cyclase; in the presence of NADH (1 mM) the Km for ATP was increased from 0.24 +/- 0.02 mM to 0.44 +/- 0.08 mM with no change in Vmax. This observation and the inability of high NADH concentrations to completely inhibit the enzyme suggest that NADH interacts at a site(s) on the enzyme to increase the Km for ATP by 2-fold and this inhibitory effect is overcome at high ATP concentrations.
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PMID:Inhibition of hepatic adenylate cyclase by NADH. 187

Two spontaneous phase variants of Bordetella avium were isolated at a frequency of 2 x 10(-4) by colony immunoblot assay of B. avium with antibody against B. avium dermonecrotic toxin. The two phase variants, designated GOBL309 and GOBL312, lack dermonecrotic toxin and four outer membrane proteins with molecular masses of 93, 48, 38, and 27 kDa but retain the ability to agglutinate guinea pig erythrocytes. The proteins which are not expressed by GOBL309 and GOBL312 correspond to five proteins which are phenotypically modulated in B. avium by growth in the presence of nicotinic acid or MgSO4. Growth of the phase variants in supplemented Stainer-Scholte media containing nicotinamide did not alter expression of these five proteins. Intranasal inoculation of the spontaneous phase variants into 3-day-old turkeys and reisolation of B. avium at 2 weeks postinoculation resulted in the recovery of B. avium which had the wild-type phenotype, colonized the turkey tracheas, and produced the four outer membrane proteins and dermonecrotic toxin. Hybridization of B. avium and B. avium-like chromosomal DNA with internal portions of the Bordetella pertussis virulence regulatory genes, bvgA and bvgS, revealed that B. avium and B. avium-like isolates contain 5.3- and 5.7-kb DNA fragments, respectively, which are homologous to bvgS. B. avium and B. avium-like chromosomal DNA failed to hybridize to B. pertussis bvgA.
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PMID:Isolation and characterization of Bordetella avium phase variants. 193 61

Gene expression in Bordetella pertussis is altered by environmental signals in a process called antigenic modulation. In the presence of modulating signals, expression of several known virulence factors and outer membrane proteins is coordinately reduced. From a bank of TnphoA fusions, we have identified five genes whose expression profiles are reciprocal of those of the major virulence determinants; that is, alkaline phosphatase activity is maximal during growth in the presence of the modulators nicotinic acid and MgSO4 (S. Knapp and J. J. Mekalanos, J. Bacteriol. 170:5059-5066, 1988). We have called these loci vir-repressed genes (vrg). Two of these gene fusions (vrg-6 and vrg-18) have been cloned in Escherichia coli, returned on low-copy-number plasmids to several strains of B. pertussis, and found to be regulated similarly to the fusions harbored on the chromosome. Deletions of the two vrg promoters were constructed and returned to B. pertussis. Regulation was maintained even when all but 24 nucleotides upstream of the vrg-18 initiation codon and 60 nucleotides upstream of the vrg-6 initiation codon were deleted, suggesting that cis-acting regulatory elements of these genes lie very near or within the coding region. We observed a 21-base palindromic sequence overlapping an 8-base direct repeat within the signal sequence coding region of vrg-6; insertion of a 6-bp linker in this region abolished regulation. These repetitive sequences are also at the site of greatest primary sequence identify between vrg-6 and vrg-18 and correspond to the signal sequence coding region. We propose models that involve recognition of this region by a vir-regulated gene product.
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PMID:Evidence that modulation requires sequences downstream of the promoters of two vir-repressed genes of Bordetella pertussis. 217 66

The aim of this study was to establish the mechanism by which adrenalectomy promotes the antilipolytic effect of the adenosine analog (-)-N6-(R-phenyl-isopropyl)adenosine (R-PIA) in rat fat cells. This action of adrenalectomy was not specific for R-PIA, since it was also observed with nicotinic acid and was prevented by phosphodiesterase inhibitors. In contrast, the inhibitory effect of R-PIA and nicotinic acid toward isoproterenol-stimulated cAMP accumulation was unaltered by adrenalectomy regardless of whether phosphodiesterase inhibitors were present. Whatever the conditions used, however, the cAMP levels in adrenalectomized rat adipocytes were one quarter to one third of those in sham-operated rats and remained below the limit over which variations in cAMP had no more influence in lipolysis. Both total and particulate low Km cAMP phosphodiesterase activities per adipocyte were decreased in adrenalectomized rats, but the stimulatory responses of the particulate enzyme to R-PIA remained unchanged. Pertussis toxin-catalyzed ADP ribosylation studies revealed a marked decrease in the total amount of the alpha-subunits of Go and the adenylate cyclase inhibitory regulatory protein Gi after adrenalectomy. However, the inhibitory dose-response curves of adenylate cyclase to R-PIA, nicotinic acid, GTP, guanylylimidodiphosphate, and guanosine 5'-O-(3-thiotriphosphate) were unaltered by adrenalectomy, indicating that the inhibitory function of Gi is unimpaired by adrenalectomy. Lastly, adrenalectomy resulted in a 60% reduction of the Mn2+-stimulated adenylate cyclase activity/adipocyte, which indicates that adrenalectomy causes a defect in adenylate cyclase catalytic activity. Thus, enhanced antilipolytic effects of R-PIA induced by adrenalectomy do not involve increased function of the adenosine receptor Gi-coupled adenylate cyclase inhibitory pathway, but are related to abnormally low intracellular cAMP levels due to defective adenylate cyclase catalytic activity.
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PMID:Role of adenosine 3',5'-monophosphate and the Ri-receptor Gi-coupled adenylate cyclase inhibitory pathway in the mechanism whereby adrenalectomy increases the adenosine antilipolytic effect in rat fat cells. 246 35


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