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The crystal structure of staphylococcal superantigen-like protein 11 in complex with sialyl Lewis X reveals the mechanism for cell binding and immune inhibition.
- Source :
- Molecular Microbiology; Dec2007, Vol. 66 Issue 6, p1342-1355, 14p, 1 Color Photograph, 1 Diagram, 3 Charts, 3 Graphs
- Publication Year :
- 2007
-
Abstract
- Staphylococcus aureus is a major pathogen that produces a family of 14 staphylococcal superantigen-like (SSL) proteins, which are structurally similar to superantigens but do not stimulate T cells. SSL11 is one member of the family that is found in all staphylococcal strains. Recombinant SSL11 bound to granulocytes and monocytes through a sialic acid-dependent mechanism and was rapidly internalized. SSL11 also bound to sialic acid-containing glycoproteins, such as the Fc receptor for IgA (FcαRI) and P-selectin glycoprotein ligand-1 (PSGL-1), and inhibited neutrophil attachment to a P-selectin-coated surface. Biosensor analysis of two SSL11 alleles binding to sialyl Lewis X [sLe<superscript>x</superscript>– Neu5Acα2-3Galβ1-4(Fuc1-3)GlcNAc] coupled to bovine serum albumin gave dissociation constants of 0.7 and 7 μm respectively. Binding of SSL11 to a glycan array revealed specificity for glycans containing the trisaccharide sialyllactosamine (sLacNac – Neu5Acα2-3Galβ1-4GlcNAc). A 1.6 Å resolution crystal structure of SSL11 complexed with sLe<superscript>x</superscript> revealed a discrete binding site in the C-terminal β-grasp domain, with predominant interactions with the sialic acid and galactose residues. A single amino acid mutation in the carbohydrate binding site abolished all SSL11 binding. Thus, SSL11 is a staphylococcal protein that targets myeloid cells by binding sialyllactosamine-containing glycoproteins. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 0950382X
- Volume :
- 66
- Issue :
- 6
- Database :
- Complementary Index
- Journal :
- Molecular Microbiology
- Publication Type :
- Academic Journal
- Accession number :
- 27629773
- Full Text :
- https://doi.org/10.1111/j.1365-2958.2007.05989.x