Bordetella pertussis adenylate cyclase: a toxin with multiple talents.

The adenylate cyclase toxin of Bordetella pertussis is a secreted multifunctional protein, endowed with calmodulin-activated catalytic, haemolytic and cytotoxic activities. Residues and domains involved in different functions have been localized and several permissive sites, able to accommodate insertion of peptides without impairing the different functions of the toxin, have been identified. A 400-bp region in the promoter upstream region of the cyaA gene, encoding the toxin, has been defined as the target of transcriptional activation.