Structural highlights
Function
CHIPS_STAAE Involved in countering the first line of host defense mechanisms. Specifically inhibits the response of human neutrophils and monocytes to complement anaphylatoxin C5a and formylated peptides, like N-formyl-methionyl-leucyl-phenylalanine (fMLP). Acts by binding directly to the C5a receptor (C5aR) and formylated peptide receptor (FPR), thereby blocking the C5a- and fMLP-induced calcium responses. Prevents phagocytosis of the bacterium.[1] [2]
Publication Abstract from PubMed
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.
Structure of the tyrosine-sulfated C5a receptor N terminus in complex with chemotaxis inhibitory protein of Staphylococcus aureus.,Ippel JH, de Haas CJ, Bunschoten A, van Strijp JA, Kruijtzer JA, Liskamp RM, Kemmink J J Biol Chem. 2009 May 1;284(18):12363-72. Epub 2009 Feb 27. PMID:19251703[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ de Haas CJ, Veldkamp KE, Peschel A, Weerkamp F, Van Wamel WJ, Heezius EC, Poppelier MJ, Van Kessel KP, van Strijp JA. Chemotaxis inhibitory protein of Staphylococcus aureus, a bacterial antiinflammatory agent. J Exp Med. 2004 Mar 1;199(5):687-95. PMID:14993252 doi:http://dx.doi.org/10.1084/jem.20031636
- ↑ Postma B, Poppelier MJ, van Galen JC, Prossnitz ER, van Strijp JA, de Haas CJ, van Kessel KP. Chemotaxis inhibitory protein of Staphylococcus aureus binds specifically to the C5a and formylated peptide receptor. J Immunol. 2004 Jun 1;172(11):6994-7001. PMID:15153520
- ↑ Ippel JH, de Haas CJ, Bunschoten A, van Strijp JA, Kruijtzer JA, Liskamp RM, Kemmink J. Structure of the tyrosine-sulfated C5a receptor N terminus in complex with chemotaxis inhibitory protein of Staphylococcus aureus. J Biol Chem. 2009 May 1;284(18):12363-72. Epub 2009 Feb 27. PMID:19251703 doi:10.1074/jbc.M808179200
