Abstract
Dendritic cell inhibitory receptor 2 (DCIR2) is a C-type lectin expressed on classical dendritic cells. We recently identified the unique ligand specificity of mouse DCIR2 (mDCIR2) toward biantennary complex-type glycans containing bisecting N-acetylglucosamine (GlcNAc). Here, we report the crystal structures of the mDCIR2 carbohydrate recognition domain in unliganded form as well as in complex with an agalactosylated complex-type N-glycan unit carrying a bisecting GlcNAc residue. Bisecting GlcNAc and the α1-3 branch of the biantennary oligosaccharide asymmetrically interact with canonical and non-canonical mDCIR2 residues. Ligand-protein interactions occur directly through mDCIR2-characteristic amino acid residues as well as via a calcium ion and water molecule. Our structural and biochemical data elucidate for the first time the unique binding mode of mDCIR2 for bisecting GlcNAc-containing glycans, a mode that contrasts sharply with that of other immune C-type lectin receptors such as DC-SIGN.
Highlights
Mouse dendritic cell inhibitory receptor 2 (DCIR2) binds to bisecting glycans containing bisecting Nacetylglucosamine (GlcNAc)-containing N-glycans
A difference observed in the mouse DCIR2 (mDCIR2) carbohydrate recognition domain (CRD) structure compared with other CRDs is that the 2 strand is short and, does not participate in the -sheet composed of the 3 and 4 strands
We investigated the interaction between mDCIR2 or its mutants, which are expressed on BWZ.mDCIR2 cells, and bisecting GlcNAc-containing glycans expressed on Lec8mgatIII cells
Summary
Mouse dendritic cell inhibitory receptor 2 (DCIR2) binds to bisecting GlcNAc-containing N-glycans. Results: The crystal structure of DCIR2 carbohydrate recognition domain in complex with bisected glycan was elucidated. We recently identified the unique ligand specificity of mouse DCIR2 (mDCIR2) toward biantennary complex-type glycans containing bisecting Nacetylglucosamine (GlcNAc). We report the crystal structures of the mDCIR2 carbohydrate recognition domain in unliganded form as well as in complex with an agalactosylated complex-type N-glycan unit carrying a bisecting GlcNAc residue. Bisecting GlcNAc and the ␣1-3 branch of the biantennary oligosaccharide asymmetrically interact with canonical and non-canonical mDCIR2 residues. Our structural and biochemical data elucidate for the first time the unique binding mode of mDCIR2 for bisecting GlcNAc-containing glycans, a mode that contrasts sharply with that of other immune C-type lectin receptors such as DC-SIGN
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