Figure 2. Structure of OgOGA and similarity to other OGAs.

(A) Domain architecture of human OGA. Predicted ordered domains are shown as coloured boxes (cyan, catalytic domain; purple, stalk domain; orange, HAT domain), predicted disordered regions are indicated by red wavy lines. (B) Sequence alignment of OgOGA and hOGA. Secondary-structure elements from the OgOGA structure are shown (red, α-helices; blue, β-strands; yellow, 3₁₀-helices), broken lines denote residues disordered in apo-OgOGA. The proposed domains are indicated by boxes coloured as in (A). (C) Cartoon view of the OgOGA apo structure and domains 2 and 3 of CpNagJ. (D) Surface view of OgOGA shaded by sequence conservation among metazoan OGAs (light blue) and metazoan OGAs+OgOGA (dark blue). The PUGNAc (green) complex is shown with additional ordered loops taken from the apo-structure. (E) Active sites of the OgOGA–PUGNAc and CpNagJ–GlcNAcstatin complexes. The ligands are represented as sticks with green carbons, an unbiased F_o−F_c;ϕ_c map (2.3 σ) is shown for PUGNAc. Hydrogen bonds are drawn as black broken lines. Hydrogen bonds to/from protein backbone amides are shown as originating from the Cα. Active-site residues in OgOGA are labelled in black, alongside the equivalent hOGA residues in blue.