title: Impact of conformational heterogeneity of OxoG lesions and their pairing partners on bypass fidelity by Y family polymerases.
abstract: 7,8-Dihydro-8-oxoguanine (oxoG), the predominant oxidative DNA damage lesion, is processed differently by high-fidelity and Y-family lesion bypass polymerases. Although high-fidelity polymerases extend predominantly from an A base opposite an oxoG, the Y-family polymerases Dpo4 and human Pol eta preferentially extend from the oxoG*C base pair. We have determined crystal structures of extension Dpo4 ternary complexes with oxoG opposite C, A, G, or T and the next nascent base pair. We demonstrate that neither template backbone nor the architecture of the active site is perturbed by the oxoG(anti)*C and oxoG*A pairs. However, the latter manifest conformational heterogeneity, adopting both oxoG(syn)*A(anti) and oxoG(anti)*A(syn) alignment. Hence, the observed reduced primer extension from the dynamically flexible 3'-terminal primer base A is explained. Because of homology between Dpo4 and Pol eta, such a dynamic screening mechanism might be utilized by Dpo4 and Pol eta to regulate error-free versus error-prone bypass of oxoG and other lesions.
authors.affiliation: Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.
authors.forename: Olga
authors.initials: O
authors.lastname: Rechkoblit
authors.forename: Lucy
authors.initials: L
authors.lastname: Malinina
authors.forename: Yuan
authors.initials: Y
authors.lastname: Cheng
authors.forename: Nicholas E
authors.initials: NE
authors.lastname: Geacintov
authors.forename: Suse
authors.initials: S
authors.lastname: Broyde
authors.forename: Dinshaw J
authors.initials: DJ
authors.lastname: Patel
mesh_terms: D020029:Base Pairing; D001483:Base Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry; D004249:DNA Damage; D019951:DNA Polymerase beta / Q000737:chemistry* / Q000378:metabolism; D004260:DNA Repair; D006147:Guanine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011487:Protein Conformation
chemical_list: C453560:7,8-dihydro-8-oxoguanine; D006147:Guanine; D004247:DNA; D019951:DNA Polymerase beta