title: A fidelity mechanism in DNA polymerase lambda promotes error-free bypass of 8-oxo-dG.
abstract: 8-oxo-7,8-dihydroxy-2'-deoxyguanosine (8-oxo-dG) has high mutagenic potential as it is prone to mispair with deoxyadenine (dA). In order to maintain genomic integrity, post-replicative 8-oxo-dG:dA mispairs are removed through DNA polymerase lambda (Pol λ)-dependent MUTYH-initiated base excision repair (BER). Here, we describe seven novel crystal structures and kinetic data that fully characterize 8-oxo-dG bypass by Pol λ. We demonstrate that Pol λ has a flexible active site that can tolerate 8-oxo-dG in either the anti- or syn-conformation. Importantly, we show that discrimination against the pro-mutagenic syn-conformation occurs at the extension step and identify the residue responsible for this selectivity. This residue acts as a kinetic switch, shunting repair toward long-patch BER upon correct dCMP incorporation, thus enhancing repair efficiency. Moreover, this switch also provides a potential mechanism to increase repair fidelity of MUTYH-initiated BER.
authors.affiliation: Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY, USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Burak
authors.affiliation: Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY, USA.
authors.forename: Kip E
authors.initials: KE
authors.lastname: Guja
authors.affiliation: Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY, USA.
authors.forename: Elena
authors.initials: E
authors.lastname: Hambardjieva
authors.affiliation: Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY, USA.
authors.forename: Burak
authors.initials: B
authors.lastname: Derkunt
authors.affiliation: Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY, USA miguel.garcia-diaz@stonybrook.edu.
authors.forename: Miguel
authors.identifier: 0000-0003-1605-6861
authors.initials: M
authors.lastname: Garcia-Diaz
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D020137:Base Pair Mismatch; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D019951:DNA Polymerase beta / Q000737:chemistry* / Q000378:metabolism*; D004260:DNA Repair; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D011487:Protein Conformation
chemical_list: D000080242:8-Hydroxy-2'-Deoxyguanosine; C415367:DNA polymerase beta2; D019951:DNA Polymerase beta; D003849:Deoxyguanosine
keywords: 8‐oxo‐deoxyguanosine; DNA repair; MUTYH; polymerase lambda