Characterization of the Duffy-Binding-Like Domain of Plasmodium falciparum Blood-Stage Antigen 332
Figure 2
Homology model of Pf332-DBL created using EBA-175 as a template. (a) Sequence alignment of PfEBA-175 F1 and F2 (amino acids 152–426 and 460–743, resp.), Pkα-DBL (amino acids 15–317) and Pf332-DBL (amino acids 1–255). The sequence identity between Pf332 and EBA-175 F1, F2, and Pkα-DBL is 26%, 29%, and 24%, respectively. Cysteines are numbered according to the occurrence in the EBA-175 F2 template. Of the twelve cysteines encoded by Pf332-DBL, eight are conserved between all DBL domains investigated here (Cys numbering displayed in red), two are conserved with only EBA-175 F2 (marked with white arrowheads) whilst the remaining two are unique for Pf332-DBL (numbering marked with an asterisk). Cysteines that are missing in the Pf332-DBL domain but that are present in EBA-175 F1, F2, and Pkα-DBL are marked with black arrowheads. (b) Homology model of Pf332-DBL (PF11_0506 amino acids 1–255) created using EBA-175 F2 (PDB code 1ZRO) as a template. Cysteines are shown in yellow, and residues predicted to be involved in disulphide bridges are shown as spheres. (c) The predicted Pf332-DBL model can be subdivided into three subdomains; subdomain 1 (yellow), subdomain 2 (red), and subdomain 3 (green). Subdomains 1 and 2 have one disulphide bridge each (Cys 2-3 and Cys 5-6, resp.) whilst subdomain 3 has three (Cys 7–12, Cys 8–10, and Cys 11–13). For Pf332-DBL, Cys 2 = Cys residue 15, Cys 3 = residue 21, Cys 5* = residue 69, Cys 5 = residue 73, Cys 6* = residue 140, Cys 6 = residue 144, Cys 7 = residue 168, Cys 8 = residue 181, Cys 10 = residue 187, Cys 11 = residue 191, Cys 12 = residue 235, and Cys 13 = residue 254.
