title: Activity-regulating structural changes and autoantibody epitopes in transglutaminase 2 assessed by hydrogen/deuterium exchange.
abstract: The multifunctional enzyme transglutaminase 2 (TG2) is the target of autoantibodies in the gluten-sensitive enteropathy celiac disease. In addition, the enzyme is responsible for deamidation of gluten peptides, which are subsequently targeted by T cells. To understand the regulation of TG2 activity and the enzyme's role as an autoantigen in celiac disease, we have addressed structural properties of TG2 in solution by using hydrogen/deuterium exchange monitored by mass spectrometry. We demonstrate that Ca(2+) binding, which is necessary for TG2 activity, induces structural changes in the catalytic core domain of the enzyme. Cysteine oxidation was found to abolish these changes, suggesting a mechanism whereby disulfide bond formation inactivates the enzyme. Further, by using TG2-specific human monoclonal antibodies generated from intestinal plasma cells of celiac disease patients, we observed that binding of TG2 by autoantibodies can induce structural changes that could be relevant for the pathogenesis. Detailed mapping of two of the main epitopes targeted by celiac disease autoantibodies revealed that they are located adjacent to each other in the N-terminal part of the TG2 molecule.
authors.affiliation: Centre for Immune Regulation and Department of Immunology, University of Oslo and Oslo University Hospital, N-0372 Oslo, Norway; and.
authors.forename: Rasmus
authors.initials: R
authors.lastname: Iversen
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5320 Odense M, Denmark.
authors.forename: Simon
authors.initials: S
authors.lastname: Mysling
authors.affiliation: Centre for Immune Regulation and Department of Immunology, University of Oslo and Oslo University Hospital, N-0372 Oslo, Norway; and.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Hnida
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5320 Odense M, Denmark l.m.sollid@medisin.uio.no tjdj@bmb.sdu.dk.
authors.forename: Thomas J D
authors.initials: TJ
authors.lastname: Jørgensen
authors.affiliation: Centre for Immune Regulation and Department of Immunology, University of Oslo and Oslo University Hospital, N-0372 Oslo, Norway; and l.m.sollid@medisin.uio.no tjdj@bmb.sdu.dk.
authors.forename: Ludvig M
authors.initials: LM
authors.lastname: Sollid
mesh_terms: D001323:Autoantibodies / Q000276:immunology* / Q000378:metabolism; D001665:Binding Sites / Q000235:genetics; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D002446:Celiac Disease / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D041961:Deuterium Exchange Measurement / Q000379:methods*; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D018604:Epitope Mapping / Q000379:methods; D000939:Epitopes / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000276:immunology / Q000473:pathology; D013058:Mass Spectrometry / Q000379:methods; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D010950:Plasma Cells / Q000276:immunology / Q000378:metabolism; D011485:Protein Binding; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D017434:Protein Structure, Tertiary; D011503:Transglutaminases / Q000737:chemistry / Q000235:genetics / Q000276:immunology*
chemical_list: D001323:Autoantibodies; D004220:Disulfides; D000939:Epitopes; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D019204:GTP-Binding Proteins; D002118:Calcium
keywords: autoantibodies; celiac disease; hydrogen/deuterium exchange; transglutaminase 2