2imq | pdb_00002imq

Crystal structure of ferrous cimex nitrophorin

spinqualitylabelsall models 2imq, resolution 1.30Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2imq is a 1 chain structure with sequence from Cimex lectularius. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.3Å Ligands: HEM Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function NP_CIMLE Heme-based protein that delivers nitric oxide gas (NO) to the victim while feeding, resulting in vasodilation (Probable). In place of heme, the heme-binding cysteine can also reversibly bind NO when it is present in high concentrations (PubMed:15637157). 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 Certain bloodsucking insects deliver nitric oxide (NO) while feeding, to induce vasodilation and inhibit blood coagulation. We have expressed, characterized, and determined the crystal structure of the Cimex lectularius (bedbug) nitrophorin, the protein responsible for NO storage and delivery, to understand how the insect successfully handles this reactive molecule. Surprisingly, NO binds not only to the ferric nitrophorin heme, but it can also be stored as an S-nitroso (SNO) conjugate of the proximal heme cysteine (Cys-60) when present at higher concentrations. EPR- and UV-visible spectroscopies, and a crystallographic structure determination to 1.75-A resolution, reveal SNO formation to proceed with reduction of the heme iron, yielding an Fe-NO complex. Stopped-flow kinetic measurements indicate that an ordered reaction mechanism takes place: initial NO binding occurs at the ferric heme and is followed by heme reduction, Cys-60 release from the heme iron, and SNO formation. Release of NO occurs through a reversal of these steps. These data provide, to our knowledge, the first view of reversible metal-assisted SNO formation in a protein and suggest a mechanism for its role in NO release from ferrous heme. This mechanism and Cimex nitrophorin structure are completely unlike those of the nitrophorins from Rhodnius prolixus, where NO protection is provided by a large conformational change that buries the heme nitrosyl complex, highlighting the remarkable evolution of proteins that assist insects in bloodfeeding. Heme-assisted S-nitrosation of a proximal thiolate in a nitric oxide transport protein.,Weichsel A, Maes EM, Andersen JF, Valenzuela JG, Shokhireva TKh, Walker FA, Montfort WR Proc Natl Acad Sci U S A. 2005 Jan 18;102(3):594-9. Epub 2005 Jan 6. PMID:015637157 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Nitrophorin

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