Crystal structure of the complex mAb 17.2 and the C-terminal region of Trypanosoma cruzi P2β protein: implications in cross-reactivity

• Published in: PLoS neglected tropical diseases Vol. 5; no. 11; p. e1375
• Main Authors: Pizarro, Juan Carlos, Boulot, Ginette, Bentley, Graham A, Gómez, Karina A, Hoebeke, Johan, Hontebeyrie, Mireille, Levin, Mariano J, Smulski, Cristian R
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 01-11-2011; Public Library of Science (PLoS)
• Subjects: Animals; Antibodies, Monoclonal - chemistry; Antibodies, Monoclonal - immunology; Antibodies, Monoclonal - metabolism; Antibodies, Protozoan - chemistry; Antibodies, Protozoan - immunology; Antibodies, Protozoan - metabolism; Biochemistry, Molecular Biology; Biology; Causes of; Chagas' disease; Cross Reactions; Crystallography, X-Ray; Female; Health aspects; Heart diseases; Humans; Immunoglobulin Fab Fragments - chemistry; Immunoglobulin Fab Fragments - immunology; Immunoglobulin Fab Fragments - metabolism; Life Sciences; Medicine; Mice; Mice, Inbred BALB C; Models, Molecular; Monoclonal antibodies; Phosphoproteins - chemistry; Phosphoproteins - immunology; Phosphoproteins - metabolism; Protein Binding; Protein Structure, Quaternary; Receptors, Adrenergic, beta-1 - immunology; Receptors, Adrenergic, beta-1 - metabolism; Ribosomal Proteins - chemistry; Ribosomal Proteins - immunology; Ribosomal Proteins - metabolism; Risk factors; Structural Biology; Trypanosoma cruzi; Trypanosoma cruzi - chemistry; France
• ISSN: 1935-2735; 1935-2727; 1935-2735
• DOI: 10.1371/journal.pntd.0001375

Patients with Chronic Chagas' Heart Disease possess high levels of antibodies against the carboxyl-terminal end of the ribosomal P2ß protein of Trypanosoma cruzi (TcP2ß). These antibodies, as well as the murine monoclonal antibody (mAb) 17.2, recognize the last 13 amino acids of TcP2ß (called the R13 epitope: EEEDDDMGFGLFD) and are able to cross-react with, and stimulate, the ß1 adrenergic receptor (ß1-AR). Indeed, the mAb 17.2 was able to specifically detect human β1-AR, stably transfected into HEK cells, by flow cytometry and to induce repolarisation abnormalities and first degree atrioventricular conduction block after passive transfer to naïve mice. To study the structural basis of this cross-reactivity, we determined the crystal structure of the Fab region of the mAb 17.2 alone at 2.31 Å resolution and in complex with the R13 peptide at 1.89 Å resolution. We identified as key contact residues on R13 peptide Glu3, Asp6 and Phe9 as was previously shown by alanine scanning. Additionally, we generated a model of human β1-AR to elucidate the interaction with anti-R13 antibodies. These data provide an understanding of the molecular basis of cross-reactive antibodies induced by chronic infection with Trypanosoma cruzi.