title: Impact of Ribonucleotide Backbone on Translesion Synthesis and Repair of 7,8-Dihydro-8-oxoguanine.
abstract: Numerous ribonucleotides are incorporated into the genome during DNA replication. Oxidized ribonucleotides can also be erroneously incorporated into DNA. Embedded ribonucleotides destabilize the structure of DNA and retard DNA synthesis by DNA polymerases (pols), leading to genomic instability. Mammalian cells possess translesion DNA synthesis (TLS) pols that bypass DNA damage. The mechanism of TLS and repair of oxidized ribonucleotides remains to be elucidated. To address this, we analyzed the miscoding properties of the ribonucleotides riboguanosine (rG) and 7,8-dihydro-8-oxo-riboguanosine (8-oxo-rG) during TLS catalyzed by the human TLS pols κ and η in vitro The primer extension reaction catalyzed by human replicative pol α was strongly blocked by 8-oxo-rG. pol κ inefficiently bypassed rG and 8-oxo-rG compared with dG and 7,8-dihydro-8-oxo-2'-deoxyguanosine (8-oxo-dG), whereas pol η easily bypassed the ribonucleotides. pol α exclusively inserted dAMP opposite 8-oxo-rG. Interestingly, pol κ preferentially inserted dCMP opposite 8-oxo-rG, whereas the insertion of dAMP was favored opposite 8-oxo-dG. In addition, pol η accurately bypassed 8-oxo-rG. Furthermore, we examined the activity of the base excision repair (BER) enzymes 8-oxoguanine DNA glycosylase (OGG1) and apurinic/apyrimidinic endonuclease 1 on the substrates, including rG and 8-oxo-rG. Both BER enzymes were completely inactive against 8-oxo-rG in DNA. However, OGG1 suppressed 8-oxo-rG excision by RNase H2, which is involved in the removal of ribonucleotides from DNA. These results suggest that the different sugar backbones between 8-oxo-rG and 8-oxo-dG alter the capacity of TLS and repair of 8-oxoguanine.
authors.affiliation: From the Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan and a-sassa@nihs.go.jp.
authors.forename: Akira
authors.initials: A
authors.lastname: Sassa
authors.affiliation: the Genome Integrity and Structural Biology Laboratory, National Institutes of Health, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709.
authors.forename: Melike
authors.initials: M
authors.lastname: Çağlayan
authors.affiliation: the Genome Integrity and Structural Biology Laboratory, National Institutes of Health, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709.
authors.forename: Yesenia
authors.initials: Y
authors.lastname: Rodriguez
authors.affiliation: the Genome Integrity and Structural Biology Laboratory, National Institutes of Health, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709.
authors.forename: William A
authors.initials: WA
authors.lastname: Beard
authors.affiliation: the Genome Integrity and Structural Biology Laboratory, National Institutes of Health, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709.
authors.forename: Samuel H
authors.initials: SH
authors.lastname: Wilson
authors.affiliation: From the Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan and.
authors.forename: Takehiko
authors.initials: T
authors.lastname: Nohmi
authors.affiliation: From the Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan and.
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Honma
authors.affiliation: From the Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan and m-yasui@nihs.go.jp.
authors.forename: Manabu
authors.initials: M
authors.lastname: Yasui
mesh_terms: D004247:DNA / Q000096:biosynthesis / Q000737:chemistry*; D004260:DNA Repair; D004259:DNA-Directed DNA Polymerase / Q000737:chemistry* / Q000378:metabolism; D006147:Guanine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D016914:Ribonuclease H / Q000737:chemistry* / Q000378:metabolism
chemical_list: C024829:8-hydroxyguanine; D006147:Guanine; D004247:DNA; D004259:DNA-Directed DNA Polymerase; C546205:POLN protein, human; C091139:ribonuclease HII; D016914:Ribonuclease H
keywords: 8-oxoguanine (8-oxoG); DNA damage; DNA polymerase; base excision repair (BER); oxidative stress; ribonucleotide; translesion DNA synthesis