Adenylate cyclase toxin (ACT or CyaA) is a key virulence factor produced by Bordetella pertussis, the causative agent of whooping cough. Once inside eukaryotic cells, the toxin catalyzes the conversion of ATP to cyclic AMP (cAMP), disrupting host immune function and inducing macrophage apoptosis. The ACT protein consists of distinct structural regions, including an N-terminal catalytic domain (amino acids 1–400), a hydrophobic segment (amino acids 500–700), a glycine/aspartate-rich repeat region (amino acids 1000–1600), and a C-terminal domain (amino acids 1600–1706).
