2zod

Crystal structure of selenophosphate synthetase from Aquifex aeolicus

spinqualitylabelsall models 2zod, resolution 1.98Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2zod is a 2 chain structure with sequence from "aquifex_aeolicus"_huber_and_stetter_2001 "aquifex aeolicus" huber and stetter 2001. This structure supersedes the now removed PDB entry 2yyd. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: SO4 Related: 2yye, 2zau Gene: selD, aq_1030 ("Aquifex aeolicus" Huber and Stetter 2001) Activity: Selenide, water dikinase, with EC number 2.7.9.3 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT, TOPSAN Function [SELD_AQUAE] Synthesizes selenophosphate from selenide and ATP (By similarity). 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 Selenophosphate synthetase (SPS) catalyzes the activation of selenide with adenosine 5'-triphosphate (ATP) to generate selenophosphate, the essential reactive selenium donor for the formation of selenocysteine (Sec) and 2-selenouridine residues in proteins and RNAs, respectively. Many SPS are themselves Sec-containing proteins, in which Sec replaces Cys in the catalytically essential position (Sec/Cys). We solved the crystal structures of Aquifex aeolicus SPS and its complex with adenosine 5'-(alpha,beta-methylene) triphosphate (AMPCPP). The ATP-binding site is formed at the subunit interface of the homodimer. Four Asp residues coordinate four metal ions to bind the phosphate groups of AMPCPP. In the free SPS structure, the two loop regions in the ATP-binding site are not ordered, and no enzyme-associated metal is observed. This suggests that ATP binding, metal binding, and the formation of their binding sites are interdependent. To identify the amino-acid residues that contribute to SPS activity, we prepared six mutants of SPS and examined their selenide-dependent ATP consumption. Mutational analyses revealed that Sec/Cys13 and Lys16 are essential. In SPS.AMPCPP, the N-terminal loop, including the two residues, assumes different conformations ("open" and "closed") between the two subunits. The AMPCPP gamma-phosphate group is solvent-accessible, suggesting that a putative nucleophile could attack the ATP gamma-phosphate group to generate selenophosphate and adenosine 5'-diphosphate (ADP). Selenide attached to Sec/Cys13 as -Se-Se(-)/-S-Se(-) could serve as the nucleophile in the "closed" conformation. A water molecule, fixed close to the beta-phosphate group, could function as the nucleophile in subsequent ADP hydrolysis to orthophosphate and adenosine 5'-monophosphate. Structure of selenophosphate synthetase essential for selenium incorporation into proteins and RNAs.,Itoh Y, Sekine S, Matsumoto E, Akasaka R, Takemoto C, Shirouzu M, Yokoyama S J Mol Biol. 2009 Feb 6;385(5):1456-69. Epub 2008 Aug 26. PMID:18773910 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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