super(1)H resonance assignments and secondary structure of the 13.6 kDa glycosylated adhesion domain of human CD2

• Published in: Biochemistry (Easton) Vol. 32; no. 41; pp. 10995 - 11006
• Main Authors: Wyss, D F, Withka, J M, Knoppers, M H, Sterne, KA, Recny, MA, Wagner, G
• Format: Journal Article
• Language: English
• Published: 01-01-1993
• ISSN: 0006-2960

Human CD2, a glycosylated transmembrane receptor found on all-T-lymphocytes, plays a key role in facilitating cellular adhesion between T-cells and target cells or antigen-presenting cells by binding to its counter receptor CD58 (LFA-3) present on the surface of those cells. All CD2 adhesion functions are localized within the amino-terminal 105-residue domain, which contains a single high mannose N-glycan required for maintaining both the conformational stability and CD58 binding properties of the glycoprotein. In order to better understand the structural basis for CD2-CD58-mediated adhesion and the critical role of the carbohydrate moiety in maintaining the functional stability of the molecule, we have determined the secondary structure of the N-glycosylated adhesion domain of human CD2 (hu-sCD2 sub(105)) using NMR spectroscopy. Most of the super(1)H resonance assignments have been obtained from super(1)H- super(1)H homonuclear 2D NMR spectra, which were further extended by applying super(1)H- super(15)N heteronuclear 2D experiments on a hu-sCD2 sub(105) sample selectively labeled with [ super(15)N]lysine. Thus, 98% of all backbone super(1)H resonances and over 80% of all side chain super(1)H resonances have been assigned. An overall topology characteristic of an immunoglobulin variable domain is observed, which consists of two beta -sheets comprised of three (residues 16-20, 67-71, and 60-63) and five (residues 94-103, 80-86, 32-37, 45-47, and 53-55) antiparallel beta -strands, respectively, with a hydrophobic core sandwiched between them. A ninth beta -strand (residues 7-12) makes parallel contacts to the carboxy-terminal beta -strand. NOEs between the N-linked glycan and the protein have tentatively been identified.