Abstract
Neutrophil plays an essential role in host defense against infection, but uncontrolled neutrophilic infiltration can cause inflammation and severe epithelial damage. We recently showed that CXCR2 formed a signaling complex with NHERF1 and PLC-2, and that the formation of this complex was required for intracellular calcium mobilization and neutrophilic transepithelial migration. To uncover the structural basis of the complex formation, we report here the crystal structure of the NHERF1 PDZ1 domain in complex with the C-terminal sequence of CXCR2 at 1.16 Å resolution. The structure reveals that the CXCR2 peptide binds to PDZ1 in an extended conformation with the last four residues making specific side chain interactions. Remarkably, comparison of the structure to previously studied PDZ1 domains has allowed the identification of PDZ1 ligand-specific interactions and the mechanisms that govern PDZ1 target selection diversities. In addition, we show that CXCR2 can bind both NHERF1 PDZ1 and PDZ2 in pulldown experiments, consistent with the observation that the peptide binding pockets of these two PDZ domains are highly structurally conserved. The results of this study therefore provide structural basis for the CXCR2-mediated neutrophilic migration and could have important clinical applications in the prevention and treatment of numerous neutrophil-dependent inflammatory disorders.
Highlights
Interleukin 8 receptor, beta (CXCR2) is a G-protein-coupled receptor that mediates neutrophil migration to sites of inflammation and controls the positioning of oligodendrocyte precursors in developing spinal cord by arresting their migration [1,2]
We showed that the formation of this complex was mediated by the PDZ domains of NHERF1, which bridged CXCR2 and phospholipase C (PLC)-β2 by binding to their C-terminal PDZ-binding motifs [6]
To facilitate NHERF1-CXCR2 cocrystallization and reveal the mechanism by which NHERF1 recognizes CXCR2, we generated a chimeric protein with the C-terminus of the NHERF1 PDZ1 domain fused to five amino acids (TSTTL) corresponding to the CXCR2 residues 356–360
Summary
Interleukin 8 receptor, beta (CXCR2) is a G-protein-coupled receptor that mediates neutrophil migration to sites of inflammation and controls the positioning of oligodendrocyte precursors in developing spinal cord by arresting their migration [1,2]. We speculate that these structural differences may be important for PDZ1 ligand discrimination, as it was shown that highly specific contacts with different types of contextual residues contributed significantly to the binding specificities of all peptide-mediated protein interactions [25].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
