1ynt
From Proteopedia
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Structure of the immunodominant epitope displayed by the surface antigen 1 (SAG1) of Toxoplasma gondii complexed to a monoclonal antibody
Overview
Toxoplasma gondii, the intracellular parasite responsible for, toxoplasmosis infects more than one-third of the world population and can, be life-threatening for fetuses and immunocompromised patients. The, surface protein SAG1 is an important immune target, which provides a, strong immune response against the invasive tachyzoite while the other, forms of the parasite, devoid of SAG1 at their surface, are multiplying., In addition to this role as a "hot spot" decoy, SAG1 is predicted to act, as an adhesin during host-cell attachment through its binding to, proteoglycans. To begin to understand the relationships between SAG1, epitopes and the ligand-binding site, we have solved the crystal structure, of the monomeric form of T.gondii SAG1 complexed to a Fab derived from a, monoclonal antibody raised against tachyzoite particles. This antibody, competes strongly with human Toxoplasma-specific sera, suggesting that its, epitope is part of an immunodominant region present on the surface of, SAG1. The structure reveals that this conformational epitope, located, within the SAG1 N-terminal domain, does not overlap with the proposed, ligand-binding pocket. This study provides the first structural, description of the monomeric form of SAG1, and significant insights into, its dual role of adhesin and immune target during parasite infection.
About this Structure
1YNT is a Single protein structure of sequence from Finegoldia magna, Mus musculus and Toxoplasma gondii with CD as ligand. Full crystallographic information is available from OCA.
Reference
Crystal structure of the complex between the monomeric form of Toxoplasma gondii surface antigen 1 (SAG1) and a monoclonal antibody that mimics the human immune response., Graille M, Stura EA, Bossus M, Muller BH, Letourneur O, Battail-Poirot N, Sibai G, Gauthier M, Rolland D, Le Du MH, Ducancel F, J Mol Biol. 2005 Nov 25;354(2):447-58. Epub 2005 Sep 30. PMID:16242717
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