1. Volume 89, Issue 5, Pages 685-692 (May 1997)
Structure of a Cholesterol-Binding, Thiol-Activated Cytolysin and a Model of Its Membrane Form 
Jamie Rossjohn, Susanne C Feil, William J McKinstry, Rodney K Tweten, Michael W Parker 
Cell 
Volume 89, Issue 5, Pages (May 1997)
DOI: /S (00)

2. Figure 1 Structure of the PFO Molecule
The structure is shown in ribbon representation with each domain designated by a different color. This figure was generated using RIBBONS (Carson 1991).
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3. Figure 2 Views of the Conserved Trp-Rich Motif Region
(A) As found in the crystal structure of PFO. Trp-464 points into the sheet and is surrounded by Arg-457, Lys-455, Gln-405, Tyr-432, and Trp-467.
(B) On binding cholesterol. This figure was constructed based on a putative model of the complex as described in the text. These figures were generated using MidasPlus (Ferrin et al. 1988).
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4. Figure 3
A Model for Membrane Insertion of Thiol-Activated Cytolysins as Suggested by the PFO Structure
(A) Initial interaction with the target cell occurs with the PFO monomer being concentrated at the membrane surface by virtue of its binding to the membrane-bound receptor, cholesterol.
(B) Large arc- and ring-shaped oligomers form on the membrane surface. The oligomers are activated with cholesterol molecules (indicated by dark blue spheres) binding in the Trp-464 pocket, causing displacement of the Trp-rich motif loop and formation of a hydrophobic dagger (see Figure 2B), which causes the oligomer to partition into the membrane. Because the aliphatic side chain of cholesterol is likely buried toward the center of the bilayer, cholesterol binding would also help to draw the toxin into the bilayer.
(C) The inserted oligomer forms a pore. The charged face of Domain 4 contributes to the water-filled pore, and the other face (see Figure 5A) forms an extended β sheet structure that packs against the hydrophobic core of the membrane via clusters of cholesterol molecules. All of these pictures were generated with the program MidasPlus (Ferrin et al. 1988).
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5. Figure 5 Views of the Surface of Domain 4
(A) The opposite face to the conserved Trp-rich motif.
(B) Domain 4 loops. Residues are colored according to their charge: red is negatively charged, blue is positively charged, cyan is polar, and green is nonpolar. These figures were generated using MidasPlus (Ferrin et al. 1988).
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6. Figure 4
Complementary Fit of a Pair of Domains 1 in the Oligomer after Docking
The view is looking down onto the oligomeric ring. This figure was generated using GRASP (Nicholls et al. 1991).
Cell  , DOI: ( /S (00) )