2cm4

The complement inhibitor OmCI in complex with ricinoleic acid

spinqualitylabelsall models 2cm4, resolution 1.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2cm4 is a 1 chain structure with sequence from Argasid tick. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: ACT, RCL Related: 2cm9 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed The complement (C) system is a potent innate immune defence system against parasites. We have recently characterised and expressed OmCI, a 16 kDa protein derived from the soft tick Ornithodoros moubata that specifically binds C5, thereby preventing C activation. The structure of recombinant OmCI determined at 1.9 A resolution confirms a lipocalin fold and reveals that the protein binds a fatty acid derivative that we have identified by mass spectrometry as ricinoleic acid. We propose that OmCI could sequester one of the fatty acid-derived inflammatory modulators from the host plasma, thereby interfering with the host inflammatory response to the tick bite. Mapping of sequence differences between OmCI and other tick lipocalins with different functions, combined with biochemical investigations of OmCI activity, supports the hypothesis that OmCI acts by preventing interaction with the C5 convertase, rather than by blocking the C5a cleavage site. The structure of OMCI, a novel lipocalin inhibitor of the complement system.,Roversi P, Lissina O, Johnson S, Ahmat N, Paesen GC, Ploss K, Boland W, Nunn MA, Lea SM J Mol Biol. 2007 Jun 8;369(3):784-93. Epub 2007 Mar 30. PMID:17445829 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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