title: O6-alkylguanine postlesion DNA synthesis is correct with the right complement of hydrogen bonding.
abstract: The ability of a DNA polymerase to replicate DNA beyond a mismatch containing a DNA lesion during postlesion DNA synthesis (PLS) can be a contributing factor to mutagenesis. In this study, we investigate the ability of Dpo4, a Y-family DNA polymerase from Sulfolobus solfataricus, to perform PLS beyond the pro-mutagenic DNA adducts O(6)-benzylguanine (O(6)-BnG) and O(6)-methylguanine (O(6)-MeG). Here, O(6)-BnG and O(6)-MeG were paired opposite artificial nucleosides that were structurally altered to systematically test the influence of hydrogen bonding and base pair size and shape on O(6)-alkylguanine PLS. Dpo4-mediated PLS was more efficient past pairs containing Benzi than pairs containing the other artificial nucleoside probes. Based on steady-state kinetic analysis, frequencies of mismatch extension were 7.4 × 10(-3) and 1.5 × 10(-3) for Benzi:O(6)-MeG and Benzi:O(6)-BnG pairs, respectively. Correct extension was observed when O(6)-BnG and O(6)-MeG were paired opposite the smaller nucleoside probes Benzi and BIM; conversely, Dpo4 did not extend past the larger nucleoside probes, Peri and Per, placed opposite O(6)-BnG and O(6)-MeG. Interestingly, Benzi was extended with high fidelity by Dpo4 when it was paired opposite O(6)-BnG and O(6)-MeG but not opposite G. These results indicate that hydrogen bonding is an important noncovalent interaction that influences the fidelity and efficiency of Dpo4 to perform high-fidelity O(6)-alkylguanine PLS.
authors.affiliation: Department of Health Sciences and Technology, Institute of Food Nutrition and Health, ETH Zürich , Schmelzbergstrasse 9, 8092 Zürich, Switzerland.
authors.forename: Hailey L
authors.initials: HL
authors.lastname: Gahlon
authors.forename: Melissa L
authors.initials: ML
authors.lastname: Boby
authors.forename: Shana J
authors.initials: SJ
authors.lastname: Sturla
mesh_terms: D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D020029:Base Pairing; D018736:DNA Adducts / Q000737:chemistry / Q000378:metabolism; D004249:DNA Damage; D019951:DNA Polymerase beta / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair; D004261:DNA Replication; D019641:DNA, Archaeal / Q000096:biosynthesis*; D015870:Gene Expression; D006147:Guanine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D006860:Hydrogen Bonding; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D048229:Sulfolobus solfataricus / Q000235:genetics / Q000378:metabolism
chemical_list: D019843:Archaeal Proteins; D018736:DNA Adducts; D019641:DNA, Archaeal; D011994:Recombinant Proteins; C064976:O(6)-benzylguanine; D006147:Guanine; C008449:O-(6)-methylguanine; D019951:DNA Polymerase beta