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Structural basis for chemokine recognition by a G protein-coupled receptor and implications for receptor activation. Sci Signal 2017 Mar 21;10(471) PMID: 28325822 PMCID: PMC5648539

Abstract

Chemokines orchestrate cell migration for development, immune surveillance, and disease by binding to cell surface heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs). The array of interactions between the nearly 50 chemokines and their 20 GPCR targets generates an extensive signaling network to which promiscuity and biased agonism add further complexity. The receptor CXCR4 recognizes both monomeric and dimeric forms of the chemokine CXCL12, which is a distinct example of ligand bias in the chemokine family. We demonstrated that a constitutively monomeric CXCL12 variant reproduced the G protein-dependent and β-arrestin-dependent responses that are associated with normal CXCR4 signaling and lead to cell migration. In addition, monomeric CXCL12 made specific contacts with CXCR4 that are not present in the structure of the receptor in complex with a dimeric form of CXCL12, a biased agonist that stimulates only G protein-dependent signaling. We produced an experimentally validated model of an agonist-bound chemokine receptor that merged a nuclear magnetic resonance-based structure of monomeric CXCL12 bound to the amino terminus of CXCR4 with a crystal structure of the transmembrane domains of CXCR4. The large CXCL12:CXCR4 protein-protein interface revealed by this structure identified previously uncharacterized functional interactions that fall outside of the classical "two-site model" for chemokine-receptor recognition. Our model suggests a mechanistic hypothesis for how interactions on the extracellular face of the receptor may stimulate the conformational changes required for chemokine receptor-mediated signal transduction.

Author List

Ziarek JJ, Kleist AB, London N, Raveh B, Montpas N, Bonneterre J, St-Onge G, DiCosmo-Ponticello CJ, Koplinski CA, Roy I, Stephens B, Thelen S, Veldkamp CT, Coffman FD, Cohen MC, Dwinell MB, Thelen M, Peterson FC, Heveker N, Volkman BF

Authors

Michael B. Dwinell PhD Professor in the Microbiology and Molecular Genetics department at Medical College of Wisconsin
Francis C. Peterson PhD Professor in the Biochemistry department at Medical College of Wisconsin
Brian F. Volkman PhD Professor in the Biochemistry department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Amino Acid Sequence
Cell Line, Tumor
Cell Movement
Chemokine CXCL12
Humans
Magnetic Resonance Spectroscopy
Models, Molecular
Mutation
Protein Binding
Receptors, CXCR4
Signal Transduction



View this publication's entry at the Pubmed website PMID: 28325822
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