Figure 8.
Active site of the Pol β Asn279Ala mutant containing the oxoA:dGTP nascent base pair (PDB ID: 6PKZ) [5]. Interbase bifurcated hydrogen bonds between syn 8-oxoA and syn dGTP were observed, and the nascent mispair is distorted. The A-site metal ion is absent, and the B-site metal is in a non-optimal position. In the absence of Asn279-mediated contacts, Tyr271 forms a hydrogen bond with O8 of syn 8-oxoA and stabilizes the mismatch in the active site. Hydrogen bonds between nucleobases or interactions with the enzyme amino acids are represented with dashed lines.