4g99

Rat Heme Oxygenase-1 in complex with Heme and CO at 100 K after warming to 160 K

spinqualitylabelsall models 4g99, resolution 2.30Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4g99 is a 1 chain structure with sequence from Rattus norvegicus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.3Å Ligands: CMO, FMT, HEM Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function HMOX1_RAT Heme oxygenase cleaves the heme ring at the alpha methene bridge to form biliverdin. Biliverdin is subsequently converted to bilirubin by biliverdin reductase. Under physiological conditions, the activity of heme oxygenase is highest in the spleen, where senescent erythrocytes are sequestrated and destroyed. Publication Abstract from PubMed Heme oxygenase (HO) catalyzes heme degradation, one of its products being carbon monoxide (CO). It is well known that CO has a higher affinity for heme iron than does molecular oxygen (O(2)); therefore, CO is potentially toxic. Because O(2) is required for the HO reaction, HO must discriminate effectively between CO and O(2) and thus escape product inhibition. Previously, we demonstrated large conformational changes in the heme-HO-1 complex upon CO binding that arise from steric hindrance between CO bound to the heme iron and Gly-139. However, we have not yet identified those changes that are specific to CO binding and do not occur upon O(2) binding. Here we determine the crystal structure of the O(2)-bound form at 1.8 A resolution and reveal the structural changes that are specific to CO binding. Moreover, difference Fourier maps comparing the structures before and after CO photolysis at <160 K clearly show structural changes such as movement of the distal F-helix upon CO photolysis. No such changes are observed upon O(2) photolysis, consistent with the structures of the ligand-free, O(2)-bound, and CO-bound forms. Protein motions even at cryogenic temperatures imply that the CO-bound heme-HO-1 complex is severely constrained (as in ligand binding to the T-state of hemoglobin), indicating that CO binding to the heme-HO-1 complex is specifically inhibited by steric hindrance. The difference Fourier maps also suggest new routes for CO migration. Discrimination between CO and O(2) in heme oxygenase: comparison of static structures and dynamic conformation changes following CO photolysis.,Sugishima M, Moffat K, Noguchi M Biochemistry. 2012 Oct 30;51(43):8554-62. doi: 10.1021/bi301175x. Epub 2012 Oct, 18. PMID:23043644 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Heme oxygenase 3D structures

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