The Cysteine-Rich Interdomain Region from the Highly Variable Plasmodium falciparum Erythrocyte Membrane Protein-1 Exhibits a Conserved Structure
Figure 5
CIDR and DBL domains have structurally identical three-helix bundles.
(A) The three-helix bundle of MC179 closely overlays the C-terminal three-helix bundle of the F1 DBL domain of EBA-175 (gray). MC179 superimposes similarly on the F2 DBL domain of EBA-175 and the Pkα-DBL domain (not shown). Note that the connecting helices (yellow) extend between H2 and H3, but the DBL subdomain–subdomain interaction is approximately 120° away between the H1 and H2 helices. This overlay models our prediction of the DBL1α C-terminal three-helix bundle, with the yellow connecting helices of MC179 modeling the predicted connecting helices of DBL1α (see text). DBL subdomain 2 (S2) and subdomain 3 (S3) are labeled [41]. (B) The three-helix bundles of MC179 (pink helices) and of the F1 DBL domain (steel blue helices) are superimposed, after an approximate 180° reorientation from (A) about the vertical axis. The connecting helices between H2 and H3 are not shown for clarity. Note the almost identical positions of the helices and of conserved Phe, Trp, Tyr, and Cys side chains (red, MC179; blue, F1 DBL). Cysteines making conserved disulfide bonds (rectangles) are from MC179 (red font) and from the F1 DBL domain (blue font). Parentheses enclose the three cysteines not observed in the MC179 electron density. Cartoon diagram serves as a reference for the orientation of MC179 in (B).