Recognition of the Thomsen-Friedenreich pancarcinoma carbohydrate antigen by a lamprey variable lymphocyte receptor.

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TitleRecognition of the Thomsen-Friedenreich pancarcinoma carbohydrate antigen by a lamprey variable lymphocyte receptor.
Publication TypeJournal Article
Year of Publication2013
AuthorsLuo, M, Velikovsky, CA, Yang, X, Siddiqui, MA, Hong, X, Barchi, JJ, Gildersleeve, JC, Pancer, Z, Mariuzza, RA
JournalJ Biol Chem
Volume288
Issue32
Pagination23597-606
Date Published2013 Aug 9
ISSN1083-351X
Abstract

Variable lymphocyte receptors (VLRs) are leucine-rich repeat proteins that mediate adaptive immunity in jawless vertebrates. VLRs were recently shown to recognize glycans, such as the tumor-associated Thomsen-Friedenreich antigen (TFα; Galβ1-3GalNAcα), with a selectivity rivaling or exceeding that of lectins and antibodies. To understand the basis for TFα recognition by one such VLR (VLRB.aGPA.23), we measured thermodynamic parameters for the binding interaction and determined the structure of the VLRB.aGPA.23-TFα complex to 2.2 Å resolution. In the structure, four tryptophan residues form a tight hydrophobic cage encasing the TFα disaccharide that completely excludes buried water molecules. This cage together with hydrogen bonding of sugar hydroxyls to polar side chains explains the exquisite selectivity of VLRB.aGPA.23. The topology of the glycan-binding site of VLRB.aGPA.23 differs markedly from those of lectins or antibodies, which typically consist of long, convex grooves for accommodating the oligosaccharide. Instead, the TFα disaccharide is sandwiched between a variable loop and the concave surface of the VLR formed by the β-strands of the leucine-rich repeat modules. Longer oligosaccharides are predicted to extend perpendicularly across the β-strands, requiring them to bend to match the concavity of the VLR solenoid.

DOI10.1074/jbc.M113.480467
Alternate JournalJ. Biol. Chem.
PubMed ID23782692
Grant ListAI036900 / AI / NIAID NIH HHS / United States
AI083892 / AI / NIAID NIH HHS / United States