| Author |
Evans, Stephen V. Müller-loennies, Sven Muniyappa, Mohankumar Brade, Lore Rudd, Pauline M. Brade, Helmut Haji-ghassemi, Omid Harvey, David J. Saldova, Radka Kosma, Paul |
| Description |
Author Affiliation: Haji-Ghassemi O ( From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 3P6, Canada.); Müller-Loennies S ( Research Center Borstel, Leibniz-Center for Medicine and Biosciences, Parkallee 22, Borstel D-23845, Germany, sml@fz-borstel.de.); Saldova R ( GlycoScience Group, the National Institute for Bioprocessing Research and Training (NIBRT), Mount Merrion, Blackrock, Dublin 4, Ireland.); Muniyappa M ( GlycoScience Group, the National Institute for Bioprocessing Research and Training (NIBRT), Mount Merrion, Blackrock, Dublin 4, Ireland.); Brade L ( Research Center Borstel, Leibniz-Center for Medicine and Biosciences, Parkallee 22, Borstel D-23845, Germany.); Rudd PM ( GlycoScience Group, the National Institute for Bioprocessing Research and Training (NIBRT), Mount Merrion, Blackrock, Dublin 4, Ireland.); Harvey DJ ( Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom.); Kosma P ( University of Natural Resources and Life Sciences, Vienna, Austria, and.); Brade H ( Research Center Borstel, Leibniz-Center for Medicine and Biosciences, Parkallee 22, Borstel D-23845, Germany.); Evans SV ( From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 3P6, Canada, svevans@uvic.ca.) |
| Abstract |
The structure of the antigen binding fragment of mAb S25-26, determined to 1.95 Å resolution in complex with the Chlamydiaceae family-specific trisaccharide antigen Kdo(2â 8)Kdo(2â 4)Kdo (Kdo = 3-deoxy- -d-manno-oct-2-ulopyranosonic acid), displays a germ-line-coded paratope that differs significantly from previously characterized Chlamydiaceae-specific mAbs despite being raised against the identical immunogen. Unlike the terminal Kdo recognition pocket that promotes cross-reactivity in S25-2-type antibodies, S25-26 and the closely related S25-23 utilize a groove composed of germ-line residues to recognize the entire trisaccharide antigen and so confer strict specificity. Interest in S25-23 was sparked by its rare high µm affinity and strict specificity for the family-specific trisaccharide antigen; however, only the related antibody S25-26 proved amenable to crystallization. The structures of three unliganded forms of S25-26 have a labile complementary-determining region H3 adjacent to significant glycosylation of the variable heavy chain on asparagine 85 in Framework Region 3. Analysis of the glycan reveals a heterogeneous mixture with a common root structure that contains an unusually high number of terminal Gal-Gal moieties. One of the few reported structures of glycosylated mAbs containing these epitopes is the therapeutic antibody Cetuximab; however, unlike Cetuximab, one of the unliganded structures in S25-26 shows significant order in the glycan with appropriate electron density for nine residues. The elucidation of the three-dimensional structure of an Gal-containing N-linked glycan on a mAb variable heavy chain has potential clinical interest, as it has been implicated in allergic response in patients receiving therapeutic antibodies. |
