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The chemokine X-factor: Structure-function analysis of the CXC motif at CXCR4 and ACKR3. J Biol Chem 2020 Oct 02;295(40):13927-13939



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Pubmed Central ID




Scopus ID

2-s2.0-85092681956   3 Citations


The human chemokine family consists of 46 protein ligands that induce chemotactic cell migration by activating a family of 23 G protein-coupled receptors. The two major chemokine subfamilies, CC and CXC, bind distinct receptor subsets. A sequence motif defining these families, the X position in the CXC motif, is not predicted to make significant contacts with the receptor, but instead links structural elements associated with binding and activation. Here, we use comparative analysis of chemokine NMR structures, structural modeling, and molecular dynamic simulations that suggested the X position reorients the chemokine N terminus. Using CXCL12 as a model CXC chemokine, deletion of the X residue (Pro-10) had little to no impact on the folded chemokine structure but diminished CXCR4 agonist activity as measured by ERK phosphorylation, chemotaxis, and Gi/o-mediated cAMP inhibition. Functional impairment was attributed to over 100-fold loss of CXCR4 binding affinity. Binding to the other CXCL12 receptor, ACKR3, was diminished nearly 500-fold. Deletion of Pro-10 had little effect on CXCL12 binding to the CXCR4 N terminus, a major component of the chemokine-GPCR interface. Replacement of the X residue with the most frequent amino acid at this position (P10Q) had an intermediate effect between WT and P10del in each assay, with ACKR3 having a higher tolerance for this mutation. This work shows that the X residue helps to position the CXCL12 N terminus for optimal docking into the orthosteric pocket of CXCR4 and suggests that the CC/CXC motif contributes directly to receptor selectivity by orienting the chemokine N terminus in a subfamily-specific direction.

Author List

Wedemeyer MJ, Mahn SA, Getschman AE, Crawford KS, Peterson FC, Marchese A, McCorvy JD, Volkman BF


Adriano Marchese PhD Professor in the Biochemistry department at Medical College of Wisconsin
John McCorvy PhD Assistant Professor in the Cell Biology, Neurobiology and Anatomy 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 Motifs
Chemokine CXCL12
Molecular Docking Simulation
Molecular Dynamics Simulation
Receptors, CXCR
Receptors, CXCR4
Structure-Activity Relationship