2dr5 | pdb_00002dr5

Complex structure of CCA adding enzyme with mini-helix lacking CCA

spinqualitylabelsall models 2dr5, resolution 2.80Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2dr5 is a 2 chain structure with sequence from Arcfl. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: SO4 Related: 2dr7, 2dr8, 2dr9, 2dra, 2drb Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [CCA_ARCFU] Catalyzes the addition and repair of the essential 3'-terminal CCA sequence in tRNAs without using a nucleic acid template. Adds these three nucleotides in the order of C, C, and A to the tRNA nucleotide-73, using CTP and ATP as substrates and producing inorganic pyrophosphate. 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 CCA-adding polymerase matures the essential 3'-CCA terminus of transfer RNA without any nucleic-acid template. However, it remains unclear how the correct nucleotide triphosphate is selected in each reaction step and how the polymerization is driven by the protein and RNA dynamics. Here we present complete sequential snapshots of six complex structures of CCA-adding enzyme and four distinct RNA substrates with and without CTP (cytosine triphosphate) or ATP (adenosine triphosphate). The CCA-lacking RNA stem extends by one base pair to force the discriminator nucleoside into the active-site pocket, and then tracks back after incorporation of the first cytosine monophosphate (CMP). Accommodation of the second CTP clamps the catalytic cleft, inducing a reorientation of the turn, which flips C74 to allow CMP to be accepted. In contrast, after the second CMP is added, the polymerase and RNA primer are locked in the closed state, which directs the subsequent A addition. Between the CTP- and ATP-binding stages, the side-chain conformation of Arg 224 changes markedly; this is controlled by the global motion of the enzyme and position of the primer terminus, and is likely to achieve the CTP/ATP discrimination, depending on the polymerization stage. Throughout the CCA-adding reaction, the enzyme tail domain firmly anchors the TPsiC-loop of the tRNA, which ensures accurate polymerization and termination. Complete crystallographic analysis of the dynamics of CCA sequence addition.,Tomita K, Ishitani R, Fukai S, Nureki O Nature. 2006 Oct 26;443(7114):956-60. Epub 2006 Oct 15. PMID:17051158 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also CCA-adding enzyme

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