Structural basis of PDZ-mediated chemokine receptor CXCR2 scaffolding by guanine nucleotide exchange factor PDZ-RhoGEF.
The CXC chemokine receptor 2 (CXCR2) is a G protein coupled receptor mediating interleukin-8 chemotactic signaling and plays an important role in neutrophil mobility and tumor migration. However, efficient CXCR2 signaling requires PDZ domain-mediated scaffolding of signaling complexes at the plasma membrane and functional coupling of the signaling to specific downstream signaling pathways, in which only one PDZ protein has been characterized to interact with CXCR2. Here, we identified five novel CXCR2-binding PDZ-containing proteins, among which PDZ-RhoGEF is of particular interest because this PDZ and RGS-containing guanine nucleotide exchange factor (GEF) is also involved in cell signaling and mobility. To reveal the molecular basis of the interaction, we solved the crystal structure of PDZ-RhoGEF PDZ domain in complex with the CXCR2 C-terminal PDZ binding motif. The structure reveals that the PDZ-CXCR2 binding specificity is achieved by numerous hydrogen bonds and hydrophobic contacts with the last four CXCR2 residues contributing to specific interactions. Structural comparison of CXCR2-binding PDZ domains and PDZ-RhoGEF PDZ bound with different ligands reveals PDZ- and ligand-specific interactions that may underlie the ability of promiscuous CXCR2 binding by different PDZ domains and PDZ binding promiscuity. The structure also reveals an unexpected asymmetric disulfide bond-linked PDZ dimer that allows simultaneous parallel binding of CXCR2 to two PDZ domains. This study provides not only the structural basis for PDZ-mediated CXCR2-PDZ-RhoGEF interaction, but also a new mode of PDZ dimerization, which both could prove valuable in understanding signaling complex scaffolding in CXCR2 signaling and coupling to specific signaling pathways.
Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, MI, USA.
Nicholas
N
Spellmon
Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, MI, USA.
Joshua
J
Holcomb
Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, MI, USA.
Andrea
A
Niu
Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, MI, USA.
Vishakha
V
Choudhary
Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, MI, USA.
Xiaonan
X
Sun
Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, MI, USA.
Yingxue
Y
Zhang
Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, MI, USA.
Junmei
J
Wan
Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, MI, USA.
Maysaa
M
Doughan
Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, MI, USA.
Stephanie
S
Hayden
Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, MI, USA.
Fatme
F
Hachem
Advanced Photon Source, Argonne National Lab, Argonne, IL, USA.
Joseph
J
Brunzelle
Center for Molecular and Translational Medicine, Georgia State University, Atlanta, GA, USA. Electronic address: cli19@gsu.edu.
Chunying
C
Li
Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, MI, USA. Electronic address: zyang@med.wayne.edu.
Zhe
Z
Yang
D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D018360:Crystallography, X-Ray; D006801:Humans; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D008024:Ligands; D008958:Models, Molecular; D054731:PDZ Domains; D011485:Protein Binding; D055503:Protein Multimerization; D023063:Receptors, Interleukin-8B / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D064067:Rho Guanine Nucleotide Exchange Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D008024:Ligands; D023063:Receptors, Interleukin-8B; D064067:Rho Guanine Nucleotide Exchange Factors
CXCR2; Chemokine signaling; Dimerization; PDZ-RhoGEF; Scaffold protein; X-ray crystallography