Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0043167 (pertussis)
 19,595 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Adenylate cyclase (AC) toxin from Bordetella pertussis is unusual in that, unlike most other members of the repeats-in-toxin family that are released into the extracellular milieu, it remains associated with the bacterial surface. In this study, we investigated the nature of the association of this toxin with the surface of B. pertussis. AC toxin was extracted from crude outer membrane preparations of B. pertussis with 8 M urea, but only partially with alkaline sodium carbonate and not at all with octylglucoside, suggesting that denaturation of the toxin is necessary for its removal from the membrane. B. pertussis mutants lacking filamentous haemagglutinin (FHA) released significantly more AC toxin into the medium, and AC toxin association with the bacterial surface was partially restored by expression of FHA from a plasmid, suggesting a role for FHA in surface retention of AC toxin. AC toxin distribution was unaffected by the absence of pertactin, or full-length lipopolysaccharide, or a defect in secretion of pertussis toxin. Using overlay and immunoprecipitation, we found that a direct physical association can occur between AC toxin and FHA. Combined, these findings suggest that FHA may play a role in AC toxin retention on the surface of B. pertussis and raise the possibility of an involvement of adherence mediated by FHA in delivery of AC toxin from the bacterium to the target cell.
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PMID:Mechanism of association of adenylate cyclase toxin with the surface of Bordetella pertussis: a role for toxin-filamentous haemagglutinin interaction. 1235 27

Ingestion of a salty meal induces secretion of guanylin (GN) and uroguanylin (UGN) into the intestinal lumen, where they inhibit Na+ absorption and induce Cl-, HCO3-, and water secretion. Simultaneously, these hormones stimulate renal electrolyte excretion by inducing natriuresis, kaliuresis, and diuresis. GN and UGN therefore participate in the prevention of hypernatremia and hypervolemia after salty meals. The signaling pathway of GN and UGN in the intestine is well known. They activate enterocytes via guanylate cyclase C (GC-C), which leads to cGMP-dependent inhibition of Na+/H+ exchange and activation of the cystic fibrosis transmembrane regulator. In GC-C-deficient mice, GN and UGN still produce renal natriuresis, kaliuresis, and diuresis, suggesting different signaling pathways in the kidney compared with the intestine. Signaling pathways for GN and UGN in the kidney differ along the various nephron segments. In proximal tubule cells, a cGMP- and GC-C-dependent signaling was demonstrated for both peptides. In addition, UGN activates a pertussis toxin-sensitive G-protein-coupled receptor. A similar dual signaling pathway is also known for atrial natriuretic peptide. Recently, a cGMP-independent signaling pathway for GN and UGN was also shown in principal cells of the human and mouse cortical collecting duct. Because GN and UGN activate different signaling pathways in specific organs and even within the kidney, this review focuses on more recent findings on cellular effects and signaling mechanisms of these peptides and their pathophysiologic implications in the intestine and the kidney.
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PMID:Cellular effects of guanylin and uroguanylin. 1638 16


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