Malarial EBA-175 region VI crystallographic structure reveals a KIX-like binding interface.
Withers-Martinez, Chrislaine;
Haire, Lesley F;
Hackett, Fiona;
Walker, Philip A;
Howell, Steven A;
Smerdon, Stephen J;
Dodson, Guy G;
Blackman, Michael J;
(2008)
Malarial EBA-175 region VI crystallographic structure reveals a KIX-like binding interface.
Journal of molecular biology, 375 (3).
pp. 773-781.
ISSN 0022-2836
DOI: https://doi.org/10.1016/j.jmb.2007.10.071
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The malaria parasite proliferates in the bloodstream of its vertebrate host by invading and replicating within erythrocytes. To achieve successful invasion, a number of discrete and essential events need to take place at the parasite-host cell interface. Erythrocyte-binding antigen 175 (EBA-175) is a member of a family of Plasmodium falciparum erythrocyte-binding proteins involved in the formation of a tight junction, a necessary step in invasion. Here we present the crystal structure of EBA-175 region VI (rVI), a cysteine-rich domain that is highly conserved within the protein family and is essential for EBA-175 trafficking. The structure was solved by selenomethionine single-wavelength anomalous dispersion at 1.8 A resolution. It reveals a homodimer, containing in each subunit a compact five-alpha-helix core that is stabilized by four conserved disulfide bridges. rVI adopts a novel fold that is likely conserved across the protein family, indicating a conserved function. It shows no similarity to the Duffy-binding-like domains of EBA-175 involved in erythrocyte binding, indicating a distinct role. Remarkably, rVI possesses structural features related to the KIX-binding domain of the coactivator CREB-binding protein, supporting the binding and trafficking roles that have been ascribed to it and providing a rational basis for further experimental investigation of its function.