title: Bypass of a 5',8-cyclopurine-2'-deoxynucleoside by DNA polymerase β during DNA replication and base excision repair leads to nucleotide misinsertions and DNA strand breaks.
abstract: 5',8-Cyclopurine-2'-deoxynucleosides including 5',8-cyclo-dA (cdA) and 5',8-cyclo-dG (cdG) are induced by hydroxyl radicals resulting from oxidative stress such as ionizing radiation. 5',8-cyclopurine-2'-deoxynucleoside lesions are repaired by nucleotide excision repair with low efficiency, thereby leading to their accumulation in the human genome and lesion bypass by DNA polymerases during DNA replication and base excision repair (BER). In this study, for the first time, we discovered that DNA polymerase β (pol β) efficiently bypassed a 5'R-cdA, but inefficiently bypassed a 5'S-cdA during DNA replication and BER. We found that cell extracts from pol β wild-type mouse embryonic fibroblasts exhibited significant DNA synthesis activity in bypassing a cdA lesion located in replication and BER intermediates. However, pol β knock-out cell extracts exhibited little DNA synthesis to bypass the lesion. This indicates that pol β plays an important role in bypassing a cdA lesion during DNA replication and BER. Furthermore, we demonstrated that pol β inserted both a correct and incorrect nucleotide to bypass a cdA at a low concentration. Nucleotide misinsertion was significantly stimulated by a high concentration of pol β, indicating a mutagenic effect induced by pol β lesion bypass synthesis of a 5',8-cyclopurine-2'-deoxynucleoside. Moreover, we found that bypass of a 5'S-cdA by pol β generated an intermediate that failed to be extended by pol β, resulting in accumulation of single-strand DNA breaks. Our study provides the first evidence that pol β plays an important role in bypassing a 5',8-cyclo-dA during DNA replication and repair, as well as new insight into mutagenic effects and genome instability resulting from pol β bypassing of a cdA lesion.
authors.affiliation: Department of Chemistry and Biochemistry, USA; Biochemistry Ph.D. Program, USA.
authors.forename: Zhongliang
authors.initials: Z
authors.lastname: Jiang
authors.affiliation: Department of Chemistry and Biochemistry, USA.
authors.forename: Meng
authors.initials: M
authors.lastname: Xu
authors.affiliation: Department of Chemistry and Biochemistry, USA.
authors.forename: Yanhao
authors.initials: Y
authors.lastname: Lai
authors.affiliation: Department of Chemistry and Biochemistry, USA.
authors.forename: Eduardo E
authors.initials: EE
authors.lastname: Laverde
authors.affiliation: ISOF, Consiglio Nazionale delle Ricerche, Via P. Gobetti 101, 40129 Bologna, Italy.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Terzidis
authors.affiliation: ISOF, Consiglio Nazionale delle Ricerche, Via P. Gobetti 101, 40129 Bologna, Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Masi
authors.affiliation: ISOF, Consiglio Nazionale delle Ricerche, Via P. Gobetti 101, 40129 Bologna, Italy; Institute of Nanoscience and Nanotechnology, N.C.S.R. "Demokritos", 15341, Agia Paraskevi, Athens, Greece.
authors.forename: Chryssostomos
authors.initials: C
authors.lastname: Chatgilialoglu
authors.affiliation: Department of Chemistry and Biochemistry, USA; Biochemistry Ph.D. Program, USA; Biomolecular Sciences Institute, School of Integrated Sciences and Humanities, Florida International University, 11200 SW 8th Street, Miami, FL 33199, USA. Electronic address: yualiu@fiu.edu.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000818:Animals; D004247:DNA / Q000096:biosynthesis / Q000378:metabolism; D053904:DNA Breaks, Single-Stranded; D019951:DNA Polymerase beta / Q000378:metabolism*; D004260:DNA Repair; D004261:DNA Replication; D045585:Flap Endonucleases / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D009705:Nucleosides / Q000737:chemistry / Q000378:metabolism*; D009711:Nucleotides / Q000378:metabolism*; D011687:Purines / Q000737:chemistry / Q000378:metabolism*
chemical_list: D009705:Nucleosides; D009711:Nucleotides; C022262:Okazaki fragments; D011687:Purines; D004247:DNA; D019951:DNA Polymerase beta; C572473:Fen1 protein, mouse; D045585:Flap Endonucleases
keywords: 5′,8-Cyclopurine-2′-deoxynucleoside; Base excision repair; DNA polymerase β; DNA replication; Lesion bypass synthesis; Mutagenesis