Bordetella pertussis adenylate cyclase toxin as a tool to analyze molecular interactions in a bacterial two-hybrid system.

Bordetella pertussis secretes a calmodulin-activated adenylate cyclase toxin (CyaA) that is able to enter into eukaryotic cells. We took advantage of the modular structure of the catalytic domain of CyaA to design a genetic system that can detect protein-protein interactions in Escherichia coli. This bacterial two-hybrid system is based on the functional complementation between two complementary fragments, T25 and T18, of the catalytic domain of CyaA, in an E. coli cya strain. This bacterial two-hybrid system could find applications in the studies of structure/function relationships of proteins, in functional analysis of genomes, in high-throughput screening of interacting ligands and in design of new therapeutic agents.