Co-expression of the Bordetella pertussis leader peptidase I results in enhanced processing and expression of the pertussis toxin S1 subunit in Escherichia coli.

Bordetella pertussis is the causative agent of whooping cough. Traditional vaccines against this disease are inherently reactogenic, thus research is currently focussed on the production of less reactive, acellular vaccines. Expression of candidate antigens for these vaccines in Escherichia coli would be preferable, however, several B. pertussis antigens undergo incorrect post-translational processing in E. coli. The leader peptidase gene (lep) of B. pertussis encodes a protein of 294 amino acid residues that shares homology with other prokaryote leader peptidase I sequences. Hydrophilicity analysis based on the predicted amino acid sequence has demonstrated a similar membrane topology to that of E. coli and Salmonella typhimurium leader peptidase I. Co-expression of the B. pertussis lep gene in E. coli strain TOPP2 expressing the pertussis toxin S1 subunit was found to markedly increase the expression and post-translational processing of the S1 protein.