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. 2014 Apr 2;136(15):5709–5721. doi: 10.1021/ja500172d

Figure 3.

Figure 3

Ternary structure of polβ incorporating nonhydrolyzable dCTP analogue (dCTP*, shown in green) opposite templating O6MeG in the presence of Mg2+ (PDB ID 4MFC). (A) Overall structure of the O6MeG·C–Mg2+ ternary structure. (B) Structural overlay of the O6MeG·C–Mg2+ ternary complex and the O6MeG binary gapped complex. Protein in the binary structure is shown in blue. (C) Active-site view of the O6MeG·C–Mg2+ ternary structure. Protein is in an open conformation. O6MeG and dCTP* form a staggered base pair. The distance between the 3′-OH of the primer terminus and Pα of dTTP* is indicated as a red double-headed arrow. (D) A 2Fo – Fc map contoured at 1σ around O6MeG and dCTP*. (E) Close-up view of the active-site metal ion binding site. Only the nucleotide-binding metal ion is present in this structure, and the metal ion is not coordinated to Asp192. (F) Overlay of the O6MeG·C–Mg2+ ternary structure with published C·A–Mn2+ ternary structure (PDB ID 3C2L(42)). (G) Overlay of the O6MeG·C–Mg2+ ternary structure with published A·G ternary structure with Arg283Lys mutation (PDB ID 4F5P(43)).