Mapping of Epitopes for Autoantibodies to the Type 1 Diabetes Autoantigen IA-2 by Peptide Phage Display and Molecular Modeling: Overlap of Antibody and T Cell Determinants
| Autor: | Josef Endl, James A. Dromey, Sarah M. Weenink, Michael R. Christie, Ian Todd, Patrick J. Tighe, Günther H.J. Peters |
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| Rok vydání: | 2004 |
| Předmět: |
Models
Molecular Phage display Protein Conformation Molecular Sequence Data Immunology Epitopes T-Lymphocyte Peptide Biology Autoantigens Epitope Protein structure Peptide Library Humans Immunology and Allergy Amino Acid Sequence Homology modeling Peptide library Peptide sequence Autoantibodies chemistry.chemical_classification Antibodies Monoclonal Molecular biology Clone Cells Amino acid Diabetes Mellitus Type 1 Amino Acid Substitution Biochemistry chemistry Mutagenesis Site-Directed Binding Sites Antibody Epitope Mapping Bacteriophage M13 |
| Zdroj: | ResearcherID |
| ISSN: | 1550-6606 0022-1767 |
| DOI: | 10.4049/jimmunol.172.7.4084 |
| Popis: | IA-2 is a major target of autoimmunity in type 1 diabetes. IA-2 responsive T cells recognize determinants within regions represented by amino acids 787–817 and 841–869 of the molecule. Epitopes for IA-2 autoantibodies are largely conformational and not well defined. In this study, we used peptide phage display and homology modeling to characterize the epitope of a monoclonal IA-2 Ab (96/3) from a human type 1 diabetic patient. This Ab competes for IA-2 binding with Abs from the majority of patients with type 1 diabetes and therefore binds a region close to common autoantibody epitopes. Alignment of peptides obtained after screening phage-displayed peptide libraries with purified 96/3 identified a consensus binding sequence of Asn-x-Glu-x-x-(aromatic)-x-x-Gly. The predicted surface on a three-dimensional homology model of the tyrosine phosphatase domain of IA-2 was analyzed for clusters of Asn, Glu, and aromatic residues and amino acids contributing to the epitope investigated using site-directed mutagenesis. Mutation of each of amino acids Asn858, Glu836, and Trp799 reduced 96/3 Ab binding by >45%. Mutations of these residues also inhibited binding of serum autoantibodies from IA-2 Ab-positive type 1 diabetic patients. This study identifies a region commonly recognized by autoantibodies in type 1 diabetes that overlaps with dominant T cell determinants. |
| Databáze: | OpenAIRE |
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