1p3t
From Proteopedia
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Crystal Structures of the NO-and CO-Bound Heme Oxygenase From Neisseria Meningitidis: Implications for Oxygen Activation
Overview
Heme oxygenases catalyze the oxidation of heme to biliverdin, carbon, monoxide, and free iron while playing a critical role in mammalian heme, homeostasis. Pathogenic bacteria such as Neisseriae meningitidis also, produce heme oxygenase as part of a mechanism to mine host iron. The key, step in heme oxidation is the regioselective oxidation of the heme, alpha-meso-carbon by an activated Fe(III)-OOH complex. The structures of, various diatomic ligands bound to the heme iron can mimic the dioxygen, complex and provide important insights on the mechanism of O2 activation., Here we report the crystal structures of N. meningitidis heme oxygenase, (nm-HO) in the Fe(II), Fe(II)-CO, and Fe(II)-NO states and compare these, to the NO complex of human heme oxygenase-1 (Lad, L., Wang, J., Li, H., Friedman, J., Bhaskar, B., Ortiz de Montellano, P. R., and Poulos, T. L., (2003) J. Mol. Biol. 330, 527-538). Coordination of NO or CO results in a, reorientation of Arg-77 that enables Arg-77 to participate in an active, site H-bonded network involving a series of water molecules. One of these, water molecules directly H-bonds to the Fe(II)-linked ligand and very, likely serves as the proton source required for oxygen activation., Although the active site residues differ between nm-HO and human HO-1, the, close similarity in the H-bonded water network suggests a common mechanism, shared by all heme oxygenases.
About this Structure
1P3T is a Single protein structure of sequence from Neisseria meningitidis with HEM as ligand. Active as Heme oxygenase, with EC number 1.14.99.3 Full crystallographic information is available from OCA.
Reference
Crystal structures of the NO- and CO-bound heme oxygenase from Neisseriae meningitidis. Implications for O2 activation., Friedman J, Lad L, Deshmukh R, Li H, Wilks A, Poulos TL, J Biol Chem. 2003 Sep 5;278(36):34654-9. Epub 2003 Jun 22. PMID:12819228
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