4dsq

Crystal structure of peroxiredoxin Ahp1 from Saccharomyces cerevisiae in oxidized form

spinqualitylabelsall models 4dsq, resolution 2.40Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4dsq is a 4 chain structure with sequence from Saccharomyces cerevisiae S288C. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.4Å Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function AHP1_YEAST Thiol-specific antioxidant protein with alkyl hydroperoxidase activity. Involved in osmotic stress resistance and detoxification of the cell. Preferentially eliminates organic peroxides rather than H(2)O(2). Involved in cellular Mn(2+) homeostasis. Publication Abstract from PubMed Peroxiredoxins (Prxs) are thiol-specific antioxidant proteins that protect cells against reactive oxygen species and are involved in cellular signaling pathways. Alkyl hydroperoxide reductase Ahp1 belongs to the Prx5 subfamily and is a two-cysteine (2-Cys) Prx that forms an intermolecular disulfide bond. Enzymatic assays and bioinformatics enabled us to re-assign the peroxidatic cysteine (C(P)) to Cys-62 and the resolving cysteine (C(R)) to Cys-31 but not the previously reported Cys-120. Thus Ahp1 represents the first 2-Cys Prx with a peroxidatic cysteine after the resolving cysteine in the primary sequence. We also found the positive cooperativity of the substrate t-butyl hydroperoxide binding to Ahp1 homodimer at a Hill coefficient of approximately 2, which enabled Ahp1 to eliminate hydroperoxide at much higher efficiency. To gain the structural insights into the catalytic cycle of Ahp1, we determined the crystal structures of Ahp1 in the oxidized, reduced, and Trx2-complexed forms at 2.40, 2.91, and 2.10 A resolution, respectively. Structural superposition of the oxidized to the reduced form revealed significant conformational changes at the segments containing C(P) and C(R). An intermolecular C(P)-C(R) disulfide bond crossing the A-type dimer interface distinguishes Ahp1 from other typical 2-Cys Prxs. The structure of the Ahp1-Trx2 complex showed for the first time how the electron transfers from thioredoxin to a peroxidase with a thioredoxin-like fold. In addition, site-directed mutagenesis in combination with enzymatic assays suggested that the peroxidase activity of Ahp1 would be altered upon the urmylation (covalently conjugated to ubiquitin-related modifier Urm1) of Lys-32. Structural Snapshots of Yeast Alkyl Hydroperoxide Reductase Ahp1 Peroxiredoxin Reveal a Novel Two-cysteine Mechanism of Electron Transfer to Eliminate Reactive Oxygen Species.,Lian FM, Yu J, Ma XX, Yu XJ, Chen Y, Zhou CZ J Biol Chem. 2012 May 18;287(21):17077-87. Epub 2012 Apr 2. PMID:22474296 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Peroxiredoxin 3D structures

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