Figure 2
Crystal structure and multiple sequence alignment of CpsORN. (A) The overall structure of the unliganded CpsORN monomer with one magnesium ion (light orange sphere) in the active site. (B) Ribbon diagram of the pNP-TMP-bound D163A inactive mutant CpsORN structure. The bound ligand is shown as a stick model (magenta) with a 2Fo-Fc electron density map (contoured at 1σ). (C) Ribbon diagram of the two linked uridine (U-U)-bound CpsORN structure. The bound ligand is shown as a stick model (cyan) with a 2Fo-Fc electron density map (contoured at 1σ). (D) Ribbon diagram of the two separated uridine-bound CpsORN structure. The bound ligand is shown as a stick model (yellow) with a 2Fo-Fc electron density map (contoured at 1σ) (E) Structure-based multiple sequence alignment of CpsORN with other ORNs. The secondary structures marked above the sequences are according to the unliganded CpsORN. The aligned sequences include CpsORN (UniProtKB code Q47VZ4), CbuORN (UniProtKB code Q83C93, PDB code 3TR8), EcoORN (UniProtKB code P0A784, PDB code 1YTA), HinORN (UniProtKB code P45340, PDB code 1J9A), XcaORN (UniProtKB code Q8P8S1, PDB code 2GBZ), and AbaORN (UniProtKB code V5VGJ9, PDB code 5CY4). The conserved motifs (ExoI, ExoII, and ExoIII) of the DEDD superfamily are boxed in red. The four conserved invariant acidic residues (Asp12, Glu14, Asp112, and Asp163) are indicated by filled triangles. The residue (His158) suspected as an activator of water molecule in the enzymatic reaction is indicated by the filled circle.
