Molecular characterization of an operon required for pertussis toxin secretion.

Mutants of Bordetella pertussis which are defective in secretion of pertussis toxin were isolated and characterized. The region of the B. pertussis chromosome identified by mutagenesis as playing a role in transport of pertussis toxin was sequenced. Analysis of this region revealed eight open reading frames, seven of which predict a protein exhibiting homology with one of the VirB proteins of Agrobacterium tumefaciens, which are involved in the transport of the T-DNA molecule across bacterial and plant membranes. Thus a set of accessory proteins are most likely involved in the secretion of pertussis toxin, and these proteins appear to be members of a family of proteins involved in the secretion of macromolecules from bacteria.