Cover: The Y-family DNA polymerase IV (Dpo4) from Sulfolobus solfataricus P2 normally employs Watson–Crick base pairing in DNA replication. The illustration shows a simulated ternary complex of Dpo4 incorporating a dCTP (yellow) opposite a 2-acetylaminofluorene (AAF, red) adducted dG (cyan) at the active site. The dG modified by AAF at C8 (AAF-dG), which strongly prefers the syn glycosidic conformation, adopts an anti conformation within Dpo4 to allow Watson–Crick pairing between the adducted guanine and an incoming dCTP. The new anti-AAF-dG conformation employs a shift of the sugar pucker to C1′-exo to relieve steric hindrance and explains the preferred dCTP incorporation in Dpo4 {see article by Wang et al. in this issue [Nucleic Acids Res. (2006), 34, 785–795]}.
[Table of Contents]