Aerolysin and pertussis toxin share a common receptor-binding domain

Abstract

We have discovered that the bacterial toxins aerolysin and pertussis toxin share a common domain. This is surprising because the two toxins affect cells in very different ways. The common domain, which we call the APT domain, consists of two three-stranded anti-parallel β-sheets that come together and wrap around a central pair of helices. The APT domain shares a common fold with the C-type lectins and Link modules, and there appears to be a divergent relationship among the three families. One surface region of the APT domain is highly conserved, raising the possibility that the domains have a common function in both proteins. Mutation of one of the conserved surface residues in aerolysin, T..