Structure-function studies of the cyclase toxin of Bordetella pertussis and the leukotoxin of Pasteurella haemolytica by heterogenous C protein activation and construction of hybrid proteins

A hybrid Bordetella pertussis adenylate cyclase toxin (CyaA) with narrower target cell specificity compared to the native toxin was constructed and analyzed to determine the structure-function relationship of CyaA. Analysis of the hybrid CyaA toxin in Escherichia coli host cells indicated the absence of toxic activity due to changes in the CyaA C-terminal region which mediated the delivery of the enzymatic domain across the target cell membrane. Furthermore, amino acids in the C-terminal region and hydrophobic domain of CyaA were important for toxic activity.