Structural basis of chemokine recognition by sulfotyrosine residues in chemokine receptors — ASN Events
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  2. Session Seven - Poster Session B includes Happy Hour & Trade Display
  3. Structural basis of chemokine recognition by sulfotyrosine residues in chemokine receptors

Structural basis of chemokine recognition by sulfotyrosine residues in chemokine receptors (#224)

Martin J Stone 1 , Christopher J Millard 1 , Justin P Ludeman 1 , Mahdieh Nazari 1 , Meritxell Canals 2 , Arthur Christopoulos 2 , Richard J Payne 3 , Brendan Wilkinson 3
  1. Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, Australia
  2. Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
  3. School of Chemistry, University of Sydney, Sydney, NSW, Australia

The trafficking of leukocytes to sites of inflammation is orchestrated by the interactions of chemokines with chemokine receptors. Chemokine receptors commonly contain sulfated tyrosine residues in their amino-terminal regions, which are critical for recognition of their chemokine ligands. We have investigated the role of tyrosine sulfation in controlling binding affinity and selectivity of chemokine receptors for their cognate chemokines. The interactions of several chemokines with tyrosine-sulfated peptides derived from chemokine receptors CCR2 and CCR3 have been studied using NMR and fluorescence anisotropy methods.

The NMR structure of the chemokine eotaxin-1 bound to sulfated tyrosine residues in a CCR3 peptide highlights the importance of a hydrophobic pocket and surface basic residues in sulfotyrosine recognition. The contributions of several critical residues to binding affinity have been verified by mutational analysis. Although these residues vary across the chemokine family, NMR chemical shift mapping indicates that the sulfotyrosine binding site is conserved. We propose that the variations of specific amino acids in this conserved binding site give rise to the abilities of different chemokines to bind preferentially to differently sulfated states of their shared receptors.

Many chemokines form oligomeric structures that can interact with glycosaminoglycans (GAGs) on endothelial surfaces. However, it remains unclear whether these oligomers can bind and activate chemokine receptors. We have engineered a constitutively dimeric form of the chemokine MCP-1 and demonstrated that it is unable to activate the MCP-1 receptor CCR2. Nevertheless, both dimeric and monomeric forms of MCP-1 bind tightly to tyrosine-sulfated peptides derived from CCR2, but peptide binding induces dimer dissociation to the active monomeric form. These results lead to a model in which chemokine dimerization is coupled to binding of both GAGs on endothelial surfaces and receptors on leukocyte surfaces. The subtle interplay between these states of the receptors may contribute to regulation of leukocyte recruitment in inflammatory responses.