Fig. 1: Characteristics of 8-oxoguanine underlying base pairing, mutagenesis, and DNA repair.
From: 8-Oxoguanine: from oxidative damage to epigenetic and epitranscriptional modification
a 8-Oxoguanine (*G), formed by reacting with oxygen at the C8 position (highlighted in red), pairs with cytosine (C) through its anticonformation (*G•C; upper panel). 8-Oxoguanine (*G) in syn conformation uses a Hoogsteen edge to pair with adenine (*G•A; lower panel). b 8-Oxo-dG-induced mutagenesis and its repair pathways. 8-Oxo-dG (*G) is recognized and removed by OGG1, subsequently processed into nicks by APE1 and repaired either by short-patch or long-patch BER (upper panel). *G•A mismatch is recognized by MUTYH, followed by the APE1 reaction, and repaired by MUTYH-initiated BER (middle panel). Unrepaired 8-oxo-dG results in G > T transversion (same as C > A) during DNA replication (lower left panel). ROS induce oxidation of free nucleotide (8-oxo-dGTP), which is actively hydrolyzed by MTH1 (8-oxo-dGMP) to prevent its incorporation from DNA replication. The unrepaired 8-oxo-dG results in an A > C mutation (same as T > G; lower panel).
