Structural Features of an Extended C-Terminal Tail Modulate the Function of the Chemokine CCL21. Biochemistry 2020 Apr 07;59(13):1338-1350
Date
03/18/2020Pubmed ID
32182428Pubmed Central ID
PMC7307649DOI
10.1021/acs.biochem.0c00047Scopus ID
2-s2.0-85083041593 (requires institutional sign-in at Scopus site) 11 CitationsAbstract
The chemokines CCL21 and CCL19, through binding of their cognate receptor CCR7, orchestrate lymph node homing of dendritic cells and naïve T cells. CCL21 differs from CCL19 via an unstructured 32 residue C-terminal domain. Previously described roles for the CCL21 C-terminus include GAG-binding, spatial localization to lymphatic vessels, and autoinhibitory modulation of CCR7-mediated chemotaxis. While truncation of the C-terminal tail induced chemical shift changes in the folded chemokine domain, the structural basis for its influence on CCL21 function remains largely unexplored. CCL21 concentration-dependent NMR chemical shifts revealed weak, nonphysiological self-association that mimics the truncation of the C-terminal tail. We generated a series of C-terminal truncation variants to dissect the C-terminus influence on CCL21 structure and receptor activation. Using NMR spectroscopy, we found that CCL21 residues 80-90 mediate contacts with the chemokine domain. In cell-based assays for CCR7 and ACKR4 activation, we also found that residues 92-100 reduced CCL21 potency in calcium flux, cAMP inhibition, and β-arrestin recruitment. Taken together, these structure-function studies support a model wherein intramolecular interactions with specific residues of the flexible C-terminus stabilize a less active monomer conformation of the CCL21. We speculate that the autoinhibitory intramolecular contacts between the C-terminal tail and chemokine body are disrupted by GAG binding and/or interactions with the CCR7 receptor to ensure optimal functionality.
Author List
Moussouras NA, Hjortø GM, Peterson FC, Szpakowska M, Chevigné A, Rosenkilde MM, Volkman BF, Dwinell MBAuthors
Michael B. Dwinell PhD Center Director, Professor in the Microbiology and Immunology department at Medical College of WisconsinFrancis 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 MotifsCalcium
Chemokine CCL21
Dendritic Cells
Humans
Protein Binding
Receptors, CCR
Receptors, CCR7
