Structure of a pertussis toxin-sugar complex as a model for receptor binding.

Pertussis toxin is an exotoxin from the bacterium Bordetella pertussis which is important the pathogenesis of whooping cough and the generation of a protective immune response. The diverse biological activities of the toxin depend on its ability to recognize carbohydrate-containing receptors on a wide variety of eukaryotic cells. We present here the crystal structure of pertussis toxin complexed with a soluble oligosaccharide from transferrin. Binding sites for the terminal sialic acid-galactose moiety are revealed on both subunits S2 and S3 of the B-oligomer. Identification of amino acid residues involved in receptor binding will improve the design of genetically inactivated toxins for use in new acellular whooping cough vaccines.