Structural insights into the interaction between a potent anti-inflammatory protein, viral CC chemokine inhibitor (vCCI), and the human CC chemokine, Eotaxin-1.
Chemokines play important roles in the immune system, not only recruiting leukocytes to the site of infection and inflammation but also guiding cell homing and cell development. The soluble poxvirus-encoded protein viral CC chemokine inhibitor (vCCI), a CC chemokine inhibitor, can bind to human CC chemokines tightly to impair the host immune defense. This protein has no known homologs in eukaryotes and may represent a potent method to stop inflammation. Previously, our structure of the vCCI·MIP-1β (macrophage inflammatory protein-1β) complex indicated that vCCI uses negatively charged residues in β-sheet II to interact with positively charged residues in the MIP-1β N terminus, 20s region and 40s loop. However, the interactions between vCCI and other CC chemokines have not yet been fully explored. Here, we used NMR and fluorescence anisotropy to study the interaction between vCCI and eotaxin-1 (CCL11), a CC chemokine that is an important factor in the asthma response. NMR results reveal that the binding pattern is very similar to the vCCI·MIP-1β complex and suggest that electrostatic interactions provide a major contribution to binding. Fluorescence anisotropy results on variants of eotaxin-1 further confirm the critical roles of the charged residues in eotaxin-1. In addition, the binding affinity between vCCI and other wild type CC chemokines, MCP-1 (monocyte chemoattractant protein-1), MIP-1β, and RANTES (regulated on activation normal T cell expressed and secreted), were determined as 1.1, 1.2, and 0.22 nm, respectively. To our knowledge, this is the first work quantitatively measuring the binding affinity between vCCI and multiple CC chemokines.
Molecular Cell Biology, University of California, Merced, California 95343.
Nai-Wei
NW
Kuo
Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
Yong-Guang
YG
Gao
Molecular Cell Biology, University of California, Merced, California 95343.
Megan S
MS
Schill
High Field NMR Facility, William R. Wiley Environmental Molecular Sciences Laboratory, Richland, Washington 99352.
Nancy
N
Isern
Department of Chemistry and Biochemistry, University of Missouri, St. Louis, Missouri 63121.
Cynthia M
CM
Dupureur
Molecular Cell Biology, University of California, Merced, California 95343. Electronic address: pliwang@ucmerced.edu.
Patricia J
PJ
LiWang
D000595:Amino Acid Sequence; D054413:Chemokine CCL11 / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D018932:Chemokine CCL2 / Q000737:chemistry / Q000276:immunology; D054407:Chemokine CCL4 / Q000737:chemistry / Q000276:immunology; D018946:Chemokine CCL5 / Q000737:chemistry / Q000276:immunology; D006801:Humans; D007249:Inflammation / Q000276:immunology; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding / Q000276:immunology; D017433:Protein Structure, Secondary; D014764:Viral Proteins / Q000737:chemistry / Q000276:immunology*; D037521:Virulence Factors / Q000737:chemistry / Q000276:immunology*
C414049:CCI protein, Cowpox virus; C515456:CCL11 protein, human; C111835:CCL2 protein, human; C066507:CCL4 protein, human; D054413:Chemokine CCL11; D018932:Chemokine CCL2; D054407:Chemokine CCL4; D018946:Chemokine CCL5; D014764:Viral Proteins; D037521:Virulence Factors
Anti-inflammatory Protein; Biophysics; Chemokine-binding Protein; Chemokines; Eotaxin; Fluorescence Anisotropy; Molecular Docking; NMR; Protein-Protein Interactions; vCCI