Structure of the tyrosine-sulfated C5a receptor N terminus in complex with chemotaxis inhibitory protein of Staphylococcus aureus.
Complement component C5a is a potent pro-inflammatory agent inducing chemotaxis of leukocytes toward sites of infection and injury. C5a mediates its effects via its G protein-coupled C5a receptor (C5aR). Although under normal conditions highly beneficial, excessive levels of C5a can be deleterious to the host and have been related to numerous inflammatory diseases. A natural inhibitor of the C5aR is chemotaxis inhibitory protein of Staphylococcus aureus (CHIPS). CHIPS is a 121-residue protein excreted by S. aureus. It binds the N terminus of the C5aR (residues 1-35) with nanomolar affinity and thereby potently inhibits C5a-mediated responses in human leukocytes. Therefore, CHIPS provides a starting point for the development of new anti-inflammatory agents. Two O-sulfated tyrosine residues located at positions 11 and 14 within the C5aR N terminus play a critical role in recognition of C5a, but their role in CHIPS binding has not been established so far. By isothermal titration calorimetry, using synthetic Tyr-11- and Tyr-14-sulfated and non-sulfated C5aR N-terminal peptides, we demonstrate that the sulfate groups are essential for tight binding between the C5aR and CHIPS. In addition, the NMR structure of the complex of CHIPS and a sulfated C5aR N-terminal peptide reveals the precise binding motif as well as the distinct roles of sulfated tyrosine residues sY11 and sY14. These results provide a molecular framework for the design of novel CHIPS-based C5aR inhibitors.
Ippel
Johannes H
JH
Department of Medicinal Chemistry and Chemical Biology, Utrecht University, Sorbonnelaan 16, 3584 CA Utrecht, The Netherlands.
de Haas
Carla J C
CJ
Bunschoten
Anton
A
van Strijp
Jos A G
JA
Kruijtzer
John A W
JA
Liskamp
Rob M J
RM
Kemmink
Johan
J
D020816:Amino Acid Motifs; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D046912:Multiprotein Complexes / Q000737:chemistry* / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D044087:Receptor, Anaphylatoxin C5a; D011951:Receptors, Complement / Q000737:chemistry* / Q000378:metabolism; D013211:Staphylococcus aureus / Q000737:chemistry*; D013431:Sulfates / Q000737:chemistry / Q000378:metabolism; D014443:Tyrosine / Q000737:chemistry / Q000378:metabolism
D001426:Bacterial Proteins; C488033:C5AR1 protein, human; D046912:Multiprotein Complexes; D044087:Receptor, Anaphylatoxin C5a; D011951:Receptors, Complement; D013431:Sulfates; C493134:chemotaxis inhibitory protein, Staphylococcus aureus; D014443:Tyrosine