Structural Basis for Selective Recognition of Endogenous and Microbial Polysaccharides by Macrophage Receptor Sign-R1Silva-Martin, N., Bartual, S.G., Rodriguez, A., Ramirez, E., Chacon, P., Anthony, R.M., Park, C.G., Hermoso, J.A.
(2014) Structure 22: 1595
- PubMed: 25450767
- DOI: 10.1016/j.str.2014.09.001
- Structures With Same Primary Citation
- PubMed Abstract:
SIGN-R1 is a principal receptor for microbial polysaccharides uptake and is responsible for C3 fixation via an unusual complement activation pathway on splenic marginal zone macrophages. In these macrophages, SIGN-R1 is also involved in anti-inflamma ...
SIGN-R1 is a principal receptor for microbial polysaccharides uptake and is responsible for C3 fixation via an unusual complement activation pathway on splenic marginal zone macrophages. In these macrophages, SIGN-R1 is also involved in anti-inflammatory activity of intravenous immunoglobulin by direct interaction with sialylated Fcs. The high-resolution crystal structures of SIGN-R1 carbohydrate recognition domain and its complexes with dextran sulfate or sialic acid, and of the sialylated Fc antibody provide insights into SIGN-R1’s selective recognition of a-2,6-sialylated glycoproteins. Unexpectedly, an additional binding site has been found in the SIGNR1 carbohydrate recognition domain, structurally separate from the calcium-dependent carbohydrate-binding site. This secondary binding site could bind repetitive molecular patterns, as observed in microbial polysaccharides, in a calcium-independent manner. These two binding sites may allow SIGNR1 to simultaneously bind both immune glycoproteins and microbial polysaccharide components, accommodating SIGN-R1’s ability to relate the recognition of microbes to the activation of the classical complement pathway.
Membrane Protein Disease Research Group, Department of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7.