1aop

SULFITE REDUCTASE STRUCTURE AT 1.6 ANGSTROM RESOLUTION

spinqualitylabelsall models 1aop, resolution 1.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1aop is a 1 chain structure with sequence from Escherichia coli B. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.6Å Ligands: K, PO4, SRM Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function CYSI_ECOLI Component of the sulfite reductase complex that catalyzes the 6-electron reduction of sulfite to sulfide. This is one of several activities required for the biosynthesis of L-cysteine from sulfate.[HAMAP-Rule:MF_01540] 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 Fundamental chemical transformations for biogeochemical cycling of sulfur and nitrogen are catalyzed by sulfite and nitrite reductases. The crystallographic structure of Escherichia coli sulfite reductase hemoprotein (SiRHP), which catalyzes the concerted six-electron reductions of sulfite to sulfide and nitrite to ammonia, was solved with multiwavelength anomalous diffraction (MAD) of the native siroheme and Fe4S4 cluster cofactors, multiple isomorphous replacement, and selenomethionine sequence markers. Twofold symmetry within the 64-kilodalton polypeptide generates a distinctive three-domain alpha/beta fold that controls cofactor assembly and reactivity. Homology regions conserved between the symmetry-related halves of SiRHP and among other sulfite and nitrite reductases revealed key residues for stability and function, and identified a sulfite or nitrite reductase repeat (SNiRR) common to a redox-enzyme superfamily. The saddle-shaped siroheme shares a cysteine thiolate ligand with the Fe4S4 cluster and ligates an unexpected phosphate anion. In the substrate complex, sulfite displaces phosphate and binds to siroheme iron through sulfur. An extensive hydrogen-bonding network of positive side chains, water molecules, and siroheme carboxylates activates S-O bonds for reductive cleavage. Sulfite reductase structure at 1.6 A: evolution and catalysis for reduction of inorganic anions.,Crane BR, Siegel LM, Getzoff ED Science. 1995 Oct 6;270(5233):59-67. PMID:7569952 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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