Adenylate cyclase toxin-mediated delivery of the S1 subunit of pertussis toxin into mammalian cells.

The adenylate cyclase toxin (ACT) of Bordetella pertussis internalizes its catalytic domain into target cells. ACT can function as a tool for delivering foreign protein antigen moieties into immune effector cells to induce a cytotoxic T lymphocyte response. In this study, we replaced the catalytic domain of ACT with an enzymatically active protein moiety, the S1 (ADP-ribosyltransferase) subunit of pertussis toxin (PT). The S1 moiety was successfully internalized independent of endocytosis into sheep erythrocytes. The introduced polypeptide exhibited ADP-ribosyltransferase activity in CHO cells and induced clustering typical to PT. The results indicate that ACT can act as a vehicle for not only epitopes but also enzymatically active peptides to mammalian cells.