Bordetella Adenylate Cyclase Toxin Can Bind Ganglioside GM1

Abstract Adenylate cyclase toxin (CyaA) is produced by Bordetella pertussis, the causative agent of whooping cough. CyaA specifically binds to the heavily Nglycosylated β 2 integrin receptor CD11b/CD18 on its main cellular target myeloid phagocytic cells. However, CyaA can also interact with and intercalate into cell membranes lacking CD11b/CD18, where saccharides may play a propagating role in membrane binding. The present study was undertaken to examine whether CyaA can bind to ganglioside GM1 (GM1), a membrane raft associated oligosaccharidebearing lipid. For this sake, the potency of highly selective GM1 ligand cholera toxin subunit B (CTB) to block CyaA binding in GM1-positive CD11b/ CD18-negative human erythrocytes and K562 cells was studied by flow cytometry. Pre-treatment of erythrocytes and K562 cells with CTB markedly (29% and 28%, respectively) decreased their binding of CyaA, indicating that CyaA can bind to GM1, apparently by recognizing terminal galactose and sialic acid residues in GM1