Structural Basis for Receptor Recognition by the Human CD59-Responsive Cholesterol-Dependent Cytolysins

• Published in: Structure (London) 2016-09, Vol.24 (9), p.1488-1498
• Main Authors: Lawrence, Sara L., Gorman, Michael A., Feil, Susanne C., Mulhern, Terrence D., Kuiper, Michael J., Ratner, Adam J., Tweten, Rodney K., Morton, Craig J., Parker, Michael W.
• Format: Article
• Language: English
• Subjects: Amino Acid Motifs; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacterial Toxins - chemistry; Bacterial Toxins - genetics; Bacterial Toxins - metabolism; Bacteriocins - chemistry; Bacteriocins - genetics; Bacteriocins - metabolism; Binding Sites; CD59 Antigens - chemistry; CD59 Antigens - genetics; CD59 Antigens - metabolism; Cholesterol - chemistry; Cholesterol - metabolism; Cloning, Molecular; Crystallography, X-Ray; Escherichia coli - genetics; Escherichia coli - metabolism; Gene Expression; Humans; Molecular Dynamics Simulation; Mutation; Protein Binding; Protein Conformation, alpha-Helical; Protein Conformation, beta-Strand; Protein Interaction Domains and Motifs; Protein Multimerization; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Scattering, Small Angle; X-Ray Diffraction
• ISSN: 0969-2126; 1878-4186
• DOI: 10.1016/j.str.2016.06.017

Cholesterol-dependent cytolysins (CDCs) are a family of pore-forming toxins that punch holes in the outer membrane of eukaryotic cells. Cholesterol serves as the receptor, but a subclass of CDCs first binds to human CD59. Here we describe the crystal structures of vaginolysin and intermedilysin complexed to CD59. These studies, together with small-angle X-ray scattering, reveal that CD59 binds to each at different, though overlapping, sites, consistent with molecular dynamics simulations and binding studies. The CDC consensus undecapeptide motif, which for the CD59-responsive CDCs has a proline instead of a tryptophan in the motif, adopts a strikingly different conformation between the structures; our data suggest that the proline acts as a selectivity switch to ensure CD59-dependent CDCs bind their protein receptor first in preference to cholesterol. The structural data suggest a detailed model of how these water-soluble toxins assemble as prepores on the cell surface. [Display omitted] •VLY and ILY recognize their receptor in related but not identical ways•A key proline residue may promote CD59 binding indirectly•A domain-swapping model could explain CD59 detachment Lawrence et al. present crystal structures of the cholesterol-dependent cytolysins vaginolysin and intermedilysin bound to their receptor, human CD59. The structures provide new insights into how this family of toxins pierces eukaryotic cell membranes to form gigantic pores.