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Liyanage PS, Walker AR, Brenlla A, Cisneros GA, Romano LJ, Rueda D. Bulky Lesion Bypass Requires Dpo4 Binding in Distinct Conformations. Sci Rep 2017; 7:17383. [PMID: 29234107 PMCID: PMC5727293 DOI: 10.1038/s41598-017-17643-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 11/28/2017] [Indexed: 11/23/2022] Open
Abstract
Translesion DNA synthesis is an essential process that helps resume DNA replication at forks stalled near bulky adducts on the DNA. Benzo[a]pyrene (B[a]P) is a polycyclic aromatic hydrocarbon (PAH) that can be metabolically activated to benzo[a]pyrene diol epoxide (BPDE), which then can react with DNA to form carcinogenic DNA adducts. Here, we have used single-molecule florescence resonance energy transfer (smFRET) experiments, classical molecular dynamics simulations, and nucleotide incorporation assays to investigate the mechanism by which the model Y-family polymerase, Dpo4, bypasses a (+)-cis-B[a]P-N2-dG adduct in DNA. Our data show that when (+)-cis-B[a]P-N2-dG is the templating base, the B[a]P moiety is in a non-solvent exposed conformation stacked within the DNA helix, where it effectively blocks nucleotide incorporation across the adduct by Dpo4. However, when the media contains a small amount of dimethyl sulfoxide (DMSO), the adduct is able to move to a solvent-exposed conformation, which enables error-prone DNA replication past the adduct. When the primer terminates across from the adduct position, the addition of DMSO leads to the formation of an insertion complex capable of accurate nucleotide incorporation.
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Affiliation(s)
| | - Alice R Walker
- Department of Chemistry, University of North Texas, Denton, TX, 76201, USA
| | - Alfonso Brenlla
- Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA
| | - G Andrés Cisneros
- Department of Chemistry, University of North Texas, Denton, TX, 76201, USA
| | - Louis J Romano
- Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA.
| | - David Rueda
- Molecular Virology, Department of Medicine, Imperial College London, Du Cane Road, London, W12 0NN, UK. .,Single Molecule Imaging Group, MRC London Institute of Medical Sciences, Du Cane Road, London, W12 0NN, UK.
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Gahlon HL, Romano LJ, Rueda D. Influence of DNA Lesions on Polymerase-Mediated DNA Replication at Single-Molecule Resolution. Chem Res Toxicol 2017; 30:1972-1983. [PMID: 29020440 DOI: 10.1021/acs.chemrestox.7b00224] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Faithful replication of DNA is a critical aspect in maintaining genome integrity. DNA polymerases are responsible for replicating DNA, and high-fidelity polymerases do this rapidly and at low error rates. Upon exposure to exogenous or endogenous substances, DNA can become damaged and this can alter the speed and fidelity of a DNA polymerase. In this instance, DNA polymerases are confronted with an obstacle that can result in genomic instability during replication, for example, by nucleotide misinsertion or replication fork collapse. It is important to know how DNA polymerases respond to damaged DNA substrates to understand the mechanism of mutagenesis and chemical carcinogenesis. Single-molecule techniques have helped to improve our current understanding of DNA polymerase-mediated DNA replication, as they enable the dissection of mechanistic details that can otherwise be lost in ensemble-averaged experiments. These techniques have also been used to gain a deeper understanding of how single DNA polymerases behave at the site of the damage in a DNA substrate. In this review, we evaluate single-molecule studies that have examined the interaction between DNA polymerases and damaged sites on a DNA template.
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Affiliation(s)
- Hailey L Gahlon
- Molecular Virology, Department of Medicine, Imperial College London , Du Cane Road, London W12 0NN, U.K.,Single Molecule Imaging Group, MRC London Institute of Medical Sciences , Du Cane Road, London W12 0NN, U.K
| | - Louis J Romano
- Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States
| | - David Rueda
- Molecular Virology, Department of Medicine, Imperial College London , Du Cane Road, London W12 0NN, U.K.,Single Molecule Imaging Group, MRC London Institute of Medical Sciences , Du Cane Road, London W12 0NN, U.K
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Raper AT, Reed AJ, Gadkari VV, Suo Z. Advances in Structural and Single-Molecule Methods for Investigating DNA Lesion Bypass and Repair Polymerases. Chem Res Toxicol 2016; 30:260-269. [PMID: 28092942 DOI: 10.1021/acs.chemrestox.6b00342] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Innovative advances in X-ray crystallography and single-molecule biophysics have yielded unprecedented insight into the mechanisms of DNA lesion bypass and damage repair. Time-dependent X-ray crystallography has been successfully applied to view the bypass of 8-oxo-7,8-dihydro-2'-deoxyguanine (8-oxoG), a major oxidative DNA lesion, and the incorporation of the triphosphate form, 8-oxo-dGTP, catalyzed by human DNA polymerase β. Significant findings of these studies are highlighted here, and their contributions to the current mechanistic understanding of mutagenic translesion DNA synthesis (TLS) and base excision repair are discussed. In addition, single-molecule Förster resonance energy transfer (smFRET) techniques have recently been adapted to investigate nucleotide binding and incorporation opposite undamaged dG and 8-oxoG by Sulfolobus solfataricus DNA polymerase IV (Dpo4), a model Y-family DNA polymerase. The mechanistic response of Dpo4 to a DNA lesion and the complex smFRET technique are described here. In this perspective, we also describe how time-dependent X-ray crystallography and smFRET can be used to achieve the spatial and temporal resolutions necessary to answer some of the mechanistic questions that remain in the fields of TLS and DNA damage repair.
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Affiliation(s)
- Austin T Raper
- Department of Chemistry and Biochemistry and The Ohio State Biochemistry Program, The Ohio State University , Columbus, Ohio 43210, United States
| | - Andrew J Reed
- Department of Chemistry and Biochemistry and The Ohio State Biochemistry Program, The Ohio State University , Columbus, Ohio 43210, United States
| | - Varun V Gadkari
- Department of Chemistry and Biochemistry and The Ohio State Biochemistry Program, The Ohio State University , Columbus, Ohio 43210, United States
| | - Zucai Suo
- Department of Chemistry and Biochemistry and The Ohio State Biochemistry Program, The Ohio State University , Columbus, Ohio 43210, United States
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Xu L, Cho BP. Conformational Insights into the Mechanism of Acetylaminofluorene-dG-Induced Frameshift Mutations in the NarI Mutational Hotspot. Chem Res Toxicol 2016; 29:213-26. [PMID: 26733364 DOI: 10.1021/acs.chemrestox.5b00484] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Frameshift mutagenesis encompasses the gain or loss of DNA base pairs, resulting in altered genetic outcomes. The NarI restriction site sequence 5'-G1G2CG3CX-3' in Escherichia coli is a well-known mutational hotspot, in which lesioning of acetylaminofluorene (AAF) at G3* induces a greater -2 deletion frequency than that at other guanine sites. Its mutational efficiency is modulated by the nature of the nucleotide in the X position (C ∼ A > G ≫ T). Here, we conducted a series of polymerase-free solution experiments that examine the conformational and thermodynamic basis underlying the propensity of adducted G3 to form a slipped mutagenic intermediate (SMI) and its sequence dependence during translesion synthesis (TLS). Instability of the AAF-dG3:dC pair at the replication fork promoted slippage to form a G*C bulge-out SMI structure, consisting of S- ("lesion stacked") and B-SMI ("lesion exposed") conformations, with conformational rigidity increasing as a function of primer elongation. We found greater stability of the S- compared to the B-SMI conformer throughout TLS. The dependence of their population ratios was determined by the 3'-next flanking base X at fully elongated bulge structures, with 59% B/41% S and 86% B/14% S for the dC and dT series, respectively. These results indicate the importance of direct interactions of the hydrophobic AAF lesion with the 3'-next flanking base pair and its stacking fit within the -2 bulge structure. A detailed conformational understanding of the SMI structures and their sequence dependence may provide a useful model for DNA polymerase complexes.
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Affiliation(s)
- Lifang Xu
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island , Kingston, Rhode Island 02881, United States
| | - Bongsup P Cho
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island , Kingston, Rhode Island 02881, United States
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