Antibody recognition of a unique tumor-specific glycopeptide antigen.Brooks, C.L., Schietinger, A., Borisova, S.N., Kufer, P., Okon, M., Hirama, T., Mackenzie, C.R., Wang, L.X., Schreiber, H., Evans, S.V.
(2010) Proc.Natl.Acad.Sci.USA 107: 10056-10061
- PubMed: 20479270
- DOI: 10.1073/pnas.0915176107
- Primary Citation of Related Structures:
- PubMed Abstract:
- A mutant chaperone converts a wild-type protein into a tumor-specific antigen
Schietinger, A.,Philip, M.,Yoshida, B.A.,Azadi, P.,Liu, H.,Meredith, S.C.,Schreiber, H.
(2006) Science 314: 304
Aberrant glycosylation and the overexpression of certain carbohydrate moieties is a consistent feature of cancers, and tumor-associated oligosaccharides are actively investigated as targets for immunotherapy. One of the most common aberrations in gly ...
Aberrant glycosylation and the overexpression of certain carbohydrate moieties is a consistent feature of cancers, and tumor-associated oligosaccharides are actively investigated as targets for immunotherapy. One of the most common aberrations in glycosylation patterns is the presentation of a single O-linked N-acetylgalactosamine on a threonine or serine residue known as the "Tn antigen." Whereas the ubiquitous nature of Tn antigens on cancers has made them a natural focus of vaccine research, such carbohydrate moieties are not always tumor-specific and have been observed on embryonic and nonmalignant adult tissue. Here we report the structural basis of binding of a complex of a monoclonal antibody (237mAb) with a truly tumor-specific glycopeptide containing the Tn antigen. In contrast to glycopeptide-specific antibodies in complex with simple peptides, 237mAb does not recognize a conformational epitope induced in the peptide by sugar substitution. Instead, 237mAb uses a pocket coded by germ-line genes to completely envelope the carbohydrate moiety itself while interacting with the peptide moiety in a shallow groove. Thus, 237mAb achieves its striking tumor specificity, with no observed physiological cross-reactivity to the unglycosylated peptide or the free glycan, by a combination of multiple weak but specific interactions to both the peptide and to the glycan portions of the antigen.
Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada V8P 3P6.