Characterisation of the dynamic interactions between complex N-glycans and human CD22

CD22 (Siglec-2) is a B-cell surface inhibitory protein able to selectively recognize sialylated glycans, dampening autoimmune responses against self-antigens. We here characterize the dynamic recognition of complex-type N-glycans by human CD22, by means of orthogonal approaches including NMR spectroscopy, computational methods and biophysical assays. We provide novel molecular insights into the binding mode of sialoglycans in complex with h-CD22, highlighting the role of the sialic acid-galactose moieties in the recognition process, elucidating the conformational behaviour of complex-type N-glycans bound to Siglec-2 and dissecting the formation of CD22 homo-oligomers on the B-cell surface. Our results will enable the development of additional therapeutics able to modulate the activity of h-CD22 in autoimmune diseases and B-cell derived malignancies.