Functional glycan-free adhesion domain of human cell surface receptor CD58: design, production and NMR studies

A general strategy is presented here for producing glycan-free forms of gly coproteins without loss of function by employing apolar-to-polar mutations of surface residues in functionally irrelevant epitopes, The success of thi s structure-based approach was demonstrated through the expression in Esche richia coli of a soluble 11 kDa adhesion domain extracted from the heavily glycosylated 55 kDa human CD58 ectodomain. The solution structure was subse quently determined and binding to its counter-receptor CD2 studied by NMR. This mutant adhesion domain is functional as determined by several experime ntal methods, and the size of its binding site has been probed by chemical shift perturbations in NMR titration experiments. The new structural inform ation supports a 'hand-shake' model of CD2-CD58 interaction involving the G FCC'C " faces of both CD2 and CD58 adhesion domains. The region responsible for binding specificity is most likely localized on the C, C' and C " stra nds and the C-C' and C'-C " loops on CD58.