3w1i

Crystal structure of the N-terminal truncated selenocysteine synthase SelA

spinqualitylabelsall models 3w1i, resolution 3.19Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3w1i is a 10 chain structure with sequence from Aquae. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: K, PT NonStd Res: LLP, MSE Related: 3w1h, 3w1j, 3w1k Gene: selA (AQUAE) Activity: L-seryl-tRNA(Sec) selenium transferase, with EC number 2.9.1.1 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [SELA_AQUAE] Converts seryl-tRNA(Sec) to selenocysteinyl-tRNA(Sec) required for selenoprotein biosynthesis (By similarity). Publication Abstract from PubMed The 21st amino acid, selenocysteine (Sec), is synthesized on its cognate transfer RNA (tRNA(Sec)). In bacteria, SelA synthesizes Sec from Ser-tRNA(Sec), whereas in archaea and eukaryotes SepSecS forms Sec from phosphoserine (Sep) acylated to tRNA(Sec). We determined the crystal structures of Aquifex aeolicus SelA complexes, which revealed a ring-shaped homodecamer that binds 10 tRNA(Sec) molecules, each interacting with four SelA subunits. The SelA N-terminal domain binds the tRNA(Sec)-specific D-arm structure, thereby discriminating Ser-tRNA(Sec) from Ser-tRNA(Ser). A large cleft is created between two subunits and accommodates the 3'-terminal region of Ser-tRNA(Sec). The SelA structures together with in vivo and in vitro enzyme assays show decamerization to be essential for SelA function. SelA catalyzes pyridoxal 5'-phosphate-dependent Sec formation involving Arg residues nonhomologous to those in SepSecS. Different protein architecture and substrate coordination of the bacterial enzyme provide structural evidence for independent evolution of the two Sec synthesis systems present in nature. Decameric SelA*tRNA(Sec) ring structure reveals mechanism of bacterial selenocysteine formation.,Itoh Y, Brocker MJ, Sekine S, Hammond G, Suetsugu S, Soll D, Yokoyama S Science. 2013 Apr 5;340(6128):75-8. doi: 10.1126/science.1229521. PMID:23559248 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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