Chattip KurehongBusaba PowthongchinNiramon ThamwiriyasatiChanan AngsuthanasombatMahidol UniversitySilpakorn UniversityBurapha University2018-05-032018-05-032011-05-01Toxicon. Vol.57, No.6 (2011), 897-903004101012-s2.0-79955012734https://repository.li.mahidol.ac.th/handle/20.500.14594/12812Adenylate cyclase-haemolysin toxin (CyaA) is a virulence factor secreted from the etiologic agent of whooping cough, Bordetella pertussis. Previously, the haemolysin or pore-forming domain (CyaA-PF) has been shown to cause cell lysis of sheep erythrocytes independently, and the predicted helix 3 (570-593) within the PF-hydrophobic stretch could be a pore-lining constituent. Here, a plausible involvement in haemolytic activity of polar or charged residues (Glu 570 , Gln 574 , Glu 581 , Ser 584 and Ser 585 ) lining the hydrophilic side of CyaA-PF helix 3 was investigated via single-alanine substitutions. All the 126-kDa mutant proteins over-expressed in Escherichia coli were verified for toxin acylation as the results are corresponding to the wild-type toxin. When haemolytic activity of E. coli lysates containing soluble mutant proteins was tested against sheep erythrocytes, the importance of Glu 570 , which is highly conserved among the pore-forming RTX cytotoxin family, was revealed for pore formation, conceivably for a general pore-lining residue involved in ion conduction. © 2011 Elsevier Ltd.Mahidol UniversityPharmacology, Toxicology and PharmaceuticsArticleSCOPUS10.1016/j.toxicon.2011.03.010