2z67

Crystal structure of archaeal O-phosphoseryl-tRNA(Sec) selenium transferase (SepSecS)

spinqualitylabelsall models 2z67, resolution 2.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2z67 is a 4 chain structure with sequence from Methanococcus maripaludis S2. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.5Å Ligands: MSE, PLP, SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function SPCS_METMP Converts O-phosphoseryl-tRNA(Sec) to selenocysteinyl-tRNA(Sec) required for selenoprotein biosynthesis. 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 The micronutrient selenium is present in proteins as selenocysteine (Sec). In eukaryotes and archaea, Sec is formed in a tRNA-dependent conversion of O-phosphoserine (Sep) by O-phosphoseryl-tRNA:selenocysteinyl-tRNA synthase (SepSecS). Here, we present the crystal structure of Methanococcus maripaludis SepSecS complexed with PLP at 2.5 A resolution. SepSecS, a member of the Fold Type I PLP enzyme family, forms an (alpha2)2 homotetramer through its N-terminal extension. The active site lies on the dimer interface with each monomer contributing essential residues. In contrast to other Fold Type I PLP enzymes, Asn247 in SepSecS replaces the conserved Asp in binding the pyridinium nitrogen of PLP. A structural comparison with Escherichia coli selenocysteine lyase allowed construction of a model of Sep binding to the SepSecS catalytic site. Mutations of three conserved active site arginines (Arg72, Arg94, Arg307), protruding from the neighboring subunit, led to loss of in vivo and in vitro activity. The lack of active site cysteines demonstrates that a perselenide is not involved in SepSecS-catalyzed Sec formation; instead, the conserved arginines may facilitate the selenation reaction. Structural phylogeny shows that SepSecS evolved early in the history of PLP enzymes, and indicates that tRNA-dependent Sec formation is a primordial process. Structural insights into RNA-dependent eukaryal and archaeal selenocysteine formation.,Araiso Y, Palioura S, Ishitani R, Sherrer RL, O'Donoghue P, Yuan J, Oshikane H, Domae N, Defranco J, Soll D, Nureki O Nucleic Acids Res. 2008 Mar;36(4):1187-99. Epub 2007 Dec 23. PMID:18158303 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Selenocysteine synthase

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