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Sakai N, Assies L, Matile S. G‐Quartets, 4‐Way Junctions and Triple Helices but Not DNA Duplexes: Planarization of Twisted Push‐Pull Flipper Probes by Surface Recognition Rather Than Physical Compression. Helv Chim Acta 2022. [DOI: 10.1002/hlca.202200052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Naomi Sakai
- University of Geneva: Universite de Geneve Department of Organic Chemistry SWITZERLAND
| | - Lea Assies
- University of Geneva: Universite de Geneve Department of Organic Chemistry SWITZERLAND
| | - Stefan Matile
- University of Geneva Department of Organic Chemistry Quai Ernest-Ansermet 30 CH-1211 Geneva SWITZERLAND
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2
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Cai A, Wilson KA, Patnaik S, Wetmore SD, Cho BP. DNA base sequence effects on bulky lesion-induced conformational heterogeneity during DNA replication. Nucleic Acids Res 2019; 46:6356-6370. [PMID: 29800374 PMCID: PMC6158707 DOI: 10.1093/nar/gky409] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Accepted: 05/03/2018] [Indexed: 12/11/2022] Open
Abstract
4-Aminobiphenyl (ABP) and its structure analog 2-aminofluorene (AF) are well-known carcinogens. In the present work, an unusual sequence effect in the 5′-CTTCTG1G2TCCTCATTC-3′ DNA duplex is reported for ABP- and AF-modified G. Specifically, the ABP modification at G1 resulted in a mixture of 67% major groove B-type (B) and 33% stacked (S) conformers, while at the ABP modification at G2 exclusively resulted in the B-conformer. The AF modification at G1 and G2 lead to 25%:75% and 83%:17% B:S population ratios, respectively. These differences in preferred conformation are due to an interplay between stabilizing (hydrogen bonding and stacking that is enhanced by lesion planarity) and destabilizing (solvent exposure) forces at the lesion site. Furthermore, while the B-conformer is a thermodynamic stabilizer and the S-conformer is a destabilizer in duplex settings, the situation is reversed at the single strands/double strands (ss/ds) junction. Specifically, the twisted biphenyl is a better stacker at the ss/ds junction than the coplanar AF. Therefore, the ABP modification leads to a stronger strand binding affinity of the ss/ds junction than the AF modification. Overall, the current work provides conformational insights into the role of sequence and lesion effects in modulating DNA replication.
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Affiliation(s)
- Ang Cai
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI 02881, USA
| | - Katie A Wilson
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive West, Lethbridge, Alberta T1K 3M4, Canada
| | - Satyakam Patnaik
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI 02881, USA
| | - Stacey D Wetmore
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive West, Lethbridge, Alberta T1K 3M4, Canada
| | - Bongsup P Cho
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI 02881, USA
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3
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Berger FD, Sturla SJ, Kung RW, Montina T, Wetmore SD, Manderville RA. Conformational Preference and Fluorescence Response of a C-Linked C8-Biphenyl-Guanine Lesion in the NarI Mutational Hotspot: Evidence for Enhanced Syn Adduct Formation. Chem Res Toxicol 2017; 31:37-47. [DOI: 10.1021/acs.chemrestox.7b00266] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Florence D. Berger
- Department
of Health Sciences and Technology, Institute of Food, Nutrition, and
Health, ETH Zürich, 8092 Zürich, Switzerland
| | - Shana J. Sturla
- Department
of Health Sciences and Technology, Institute of Food, Nutrition, and
Health, ETH Zürich, 8092 Zürich, Switzerland
| | - Ryan W. Kung
- Department
of Chemistry and Biochemistry, and the Canadian Centre for Research
in Advanced Fluorine Technologies, University of Lethbridge, Lethbridge, Alberta T1K 3M4, Canada
| | - Tony Montina
- Department
of Chemistry and Biochemistry, and the Canadian Centre for Research
in Advanced Fluorine Technologies, University of Lethbridge, Lethbridge, Alberta T1K 3M4, Canada
| | - Stacey D. Wetmore
- Department
of Chemistry and Biochemistry, and the Canadian Centre for Research
in Advanced Fluorine Technologies, University of Lethbridge, Lethbridge, Alberta T1K 3M4, Canada
| | - Richard A. Manderville
- Departments
of Chemistry and Toxicology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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4
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Abstract
The eukaryotic global genomic nucleotide excision repair (GG-NER) pathway is the major mechanism that removes most bulky and some nonbulky lesions from cellular DNA. There is growing evidence that certain DNA lesions are repaired slowly or are entirely resistant to repair in cells, tissues, and in cell extract model assay systems. It is well established that the eukaryotic DNA lesion-sensing proteins do not detect the damaged nucleotide, but recognize the distortions/destabilizations in the native DNA structure caused by the damaged nucleotides. In this article, the nature of the structural features of certain bulky DNA lesions that render them resistant to NER, or cause them to be repaired slowly, is compared to that of those that are good-to-excellent NER substrates. Understanding the structural features that distinguish NER-resistant DNA lesions from good NER substrates may be useful for interpreting the biological significance of biomarkers of exposure of human populations to genotoxic environmental chemicals. NER-resistant lesions can survive to replication and cause mutations that can initiate cancer and other diseases. Furthermore, NER diminishes the efficacy of certain chemotherapeutic drugs, and the design of more potent pharmaceuticals that resist repair can be advanced through a better understanding of the structural properties of DNA lesions that engender repair-resistance.
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Affiliation(s)
- Nicholas E. Geacintov
- Chemistry and Biology Departments, New York University, New York, New York 10003-5180, United States
| | - Suse Broyde
- Chemistry and Biology Departments, New York University, New York, New York 10003-5180, United States
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5
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Urbančič I, Ljubetič A, Štrancar J. Resolving Internal Motional Correlations to Complete the Conformational Entropy Meter. J Phys Chem Lett 2014; 5:3593-3600. [PMID: 26278615 DOI: 10.1021/jz5020828] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Conformational entropy (SΩ) has long been used to theoretically characterize the dynamics of proteins, DNA, and other polymers. Though recent advances enabled its calculation also from simulations and nuclear magnetic resonance (NMR) relaxation experiments, correlated molecular motion has hitherto greatly hindered both numerical and experimental determination, requiring demanding empirical and computational calibrations. Herein, we show that these motional correlations can be estimated directly from the temperature-dependent SΩ series that reveal effective persistence lengths of the polymers, which we demonstrate by measuring SΩ of amphiphilic molecules in model lipid systems by spin-labeling electron paramagnetic resonance (EPR) spectroscopy. We validate our correlation-corrected SΩ meter against the basic biophysical interactions underlying biomembrane formation and stability, against the changes in enthalpy and diffusion coefficients upon phase transitions, and against the energetics of fatty acid dissociation. As the method can be directly applied to conformational analysis of proteins and other polymers, as well as adapted to NMR or polarized fluorescence techniques, we believe that the approach can greatly enrich the scope of experimentally available statistical thermodynamics, offering new physical insights into the behavior of biomolecules.
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Affiliation(s)
- Iztok Urbančič
- Laboratory of Biophysics, Condensed Matter Physics Department, "Jožef Stefan" Institute, Jamova cesta 39, SI-1000 Ljubljana, Slovenia
| | - Ajasja Ljubetič
- Laboratory of Biophysics, Condensed Matter Physics Department, "Jožef Stefan" Institute, Jamova cesta 39, SI-1000 Ljubljana, Slovenia
| | - Janez Štrancar
- Laboratory of Biophysics, Condensed Matter Physics Department, "Jožef Stefan" Institute, Jamova cesta 39, SI-1000 Ljubljana, Slovenia
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6
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Wilson KA, Wetmore SD. Complex Conformational Heterogeneity of the Highly Flexible O6-Benzyl-guanine DNA Adduct. Chem Res Toxicol 2014; 27:1310-25. [PMID: 24941023 DOI: 10.1021/tx500178x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Katie A. Wilson
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive West, Lethbridge, Alberta, Canada T1K 3M4
| | - Stacey D. Wetmore
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive West, Lethbridge, Alberta, Canada T1K 3M4
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7
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Jain V, Vaidyanathan VG, Patnaik S, Gopal S, Cho BP. Conformational insights into the lesion and sequence effects for arylamine-induced translesion DNA synthesis: 19F NMR, surface plasmon resonance, and primer kinetic studies. Biochemistry 2014; 53:4059-71. [PMID: 24915610 PMCID: PMC4075988 DOI: 10.1021/bi5003212] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
![]()
Adduct-induced DNA damage can affect
transcription efficiency and
DNA replication and repair. We previously investigated the effects
of the 3′-next flanking base (G*CT vs G*CA; G*, FABP, N-(2′-deoxyguanosin-8-yl)-4′-fluoro-4-aminobiphenyl;
FAF, N-(2′-deoxyguanosin-8-yl)-7-fluoro-2-aminofluorene)
on the conformation of arylamine-DNA lesions in relation to E. coli nucleotide excision repair (JainV., HiltonB., LinB., PatnaikS., LiangF., DarianE., ZouY., MackerellA. D.Jr., and ChoB. P. (2013) Nucleic Acids Res., 41, 869−88023180767). Here,
we report the differential effects of the same pair of sequences on
DNA replication in vitro by the polymerases exofree
Klenow fragment (Kf-exo–) and Dpo4. We obtained
dynamic 19F NMR spectra for two 19-mer modified templates
during primer elongation: G*CA [d(5′-CTTACCATCG*CAACCATTC-3′)]
and G*CT [d(5′-CTTACCATCG*CTACCATTC-3′)].
We found that lesion stacking is favored in the G*CT sequence compared to the G*CA counterpart. Surface
plasmon resonance binding results showed consistently weaker affinities
for the modified DNA with the binding strength in the order of FABP
> FAF and G*CA > G*CT. Primer extension was stalled at
(n) and near (n – 1 and n + 1) the lesion site, and the extent of blockage and the extension
rates across the lesion were influenced by not only the DNA sequences
but also the nature of the adduct’s chemical structure (FAF
vs FABP) and the polymerase employed (Kf-exo– vs
Dpo4). Steady-state kinetics analysis with Kf-exo– revealed the most dramatic sequence and lesion effects at the lesion
(n) and postinsertion (n + 1) sites,
respectively. Taken together, these results provide insights into
the important role of lesion-induced conformational heterogeneity
in modulating translesion DNA synthesis.
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Affiliation(s)
- Vipin Jain
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island , Kingston, Rhode Island 02881, United States
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8
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Sandineni A, Lin B, MacKerell AD, Cho BP. Structure and thermodynamic insights on acetylaminofluorene-modified deletion DNA duplexes as models for frameshift mutagenesis. Chem Res Toxicol 2013; 26:937-51. [PMID: 23688347 DOI: 10.1021/tx400116n] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
2-Acetylaminofluorene (AAF) is a prototype arylamine carcinogen that forms C8-substituted dG-AAF and dG-AF as the major DNA lesions. The bulky N-acetylated dG-AAF lesion can induce various frameshift mutations depending on the base sequence around the lesion. We hypothesized that the thermodynamic stability of bulged-out slipped mutagenic intermediates (SMIs) is directly related to deletion mutations. The objective of the present study was to probe the structural/conformational basis of various dG-AAF-induced SMIs formed during translesion synthesis. We performed spectroscopic, thermodynamic, and molecular dynamics studies of several AAF-modified 16-mer model DNA duplexes, including fully paired and -1, -2, and -3 deletion duplexes of the 5'-CTCTCGATG[FAAF]CCATCAC-3' sequence and an additional -1 deletion duplex of the 5'-CTCTCGGCG[FAAF]CCATCAC-3' NarI sequence. Modified deletion duplexes existed in a mixture of external B and stacked S conformers, with the population of the S conformer being 'GC'-1 (73%) > 'AT'-1 (72%) > full (60%) > -2 (55%) > -3 (37%). Thermodynamic stability was in the order of -1 deletion > -2 deletion > fully paired > -3 deletion duplexes. These results indicate that the stacked S-type conformer of SMIs is thermodynamically more stable than the conformationally flexible external B conformer. Results from the molecular dynamics simulations indicate that perturbation of base stacking dominates the relative stability along with contributions from bending, duplex dynamics, and solvation effects that are important in specific cases. Taken together, these results support a hypothesis that the conformational and thermodynamic stabilities of the SMIs are critical determinants for the induction of frameshift mutations.
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Affiliation(s)
- Anusha Sandineni
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, Rhode Island 02881, USA
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10
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Jain V, Hilton B, Lin B, Patnaik S, Liang F, Darian E, Zou Y, MacKerell AD, Cho BP. Unusual sequence effects on nucleotide excision repair of arylamine lesions: DNA bending/distortion as a primary recognition factor. Nucleic Acids Res 2013; 41:869-80. [PMID: 23180767 PMCID: PMC3553991 DOI: 10.1093/nar/gks1077] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Revised: 10/11/2012] [Accepted: 10/15/2012] [Indexed: 12/30/2022] Open
Abstract
The environmental arylamine mutagens are implicated in the etiology of various sporadic human cancers. Arylamine-modified dG lesions were studied in two fully paired 11-mer duplexes with a -G*CN- sequence context, in which G* is a C8-substituted dG adduct derived from fluorinated analogs of 4-aminobiphenyl (FABP), 2-aminofluorene (FAF) or 2-acetylaminofluorene (FAAF), and N is either dA or dT. The FABP and FAF lesions exist in a simple mixture of 'stacked' (S) and 'B-type' (B) conformers, whereas the N-acetylated FAAF also samples a 'wedge' (W) conformer. FAAF is repaired three to four times more efficiently than FABP and FAF. A simple A- to -T polarity swap in the G*CA/G*CT transition produced a dramatic increase in syn-conformation and resulted in 2- to 3-fold lower nucleotide excision repair (NER) efficiencies in Escherichia coli. These results indicate that lesion-induced DNA bending/thermodynamic destabilization is an important DNA damage recognition factor, more so than the local S/B-conformational heterogeneity that was observed previously for FAF and FAAF in certain sequence contexts. This work represents a novel 3'-next flanking sequence effect as a unique NER factor for bulky arylamine lesions in E. coli.
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Affiliation(s)
- Vipin Jain
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI 02881, Department of Biomedical Sciences, East Tennessee State University, Johnson city, TN 37614 and Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD 21201, USA
| | - Benjamin Hilton
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI 02881, Department of Biomedical Sciences, East Tennessee State University, Johnson city, TN 37614 and Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD 21201, USA
| | - Bin Lin
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI 02881, Department of Biomedical Sciences, East Tennessee State University, Johnson city, TN 37614 and Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD 21201, USA
| | - Satyakam Patnaik
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI 02881, Department of Biomedical Sciences, East Tennessee State University, Johnson city, TN 37614 and Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD 21201, USA
| | - Fengting Liang
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI 02881, Department of Biomedical Sciences, East Tennessee State University, Johnson city, TN 37614 and Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD 21201, USA
| | - Eva Darian
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI 02881, Department of Biomedical Sciences, East Tennessee State University, Johnson city, TN 37614 and Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD 21201, USA
| | - Yue Zou
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI 02881, Department of Biomedical Sciences, East Tennessee State University, Johnson city, TN 37614 and Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD 21201, USA
| | - Alexander D. MacKerell
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI 02881, Department of Biomedical Sciences, East Tennessee State University, Johnson city, TN 37614 and Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD 21201, USA
| | - Bongsup P. Cho
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI 02881, Department of Biomedical Sciences, East Tennessee State University, Johnson city, TN 37614 and Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD 21201, USA
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11
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C8-linked bulky guanosine DNA adducts: experimental and computational insights into adduct conformational preferences and resulting mutagenicity. Future Med Chem 2012; 4:1981-2007. [PMID: 23088278 DOI: 10.4155/fmc.12.138] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Bulky DNA adducts are formed through the covalent attachment of aryl groups to the DNA nucleobases. Many of these adducts are known to possess conformational heterogeneity, which is responsible for the variety of mutagenic outcomes associated with these lesions. The present contribution reviews several conformational and mutagenic themes that are prevalent among the DNA adducts formed at the C8-site of the guanine nucleobase. The most important conclusions obtained (to date) from experiments are summarized including the anti/syn conformational preference of the adducts, their potential to inflict DNA mutations and mismatch stabilization, and their interactions with DNA polymerases and repair enzymes. Additionally, the unique role that computer calculations can play in understanding the structural properties of these adducts are highlighted.
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12
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Loakes D. Nucleotides and nucleic acids; oligo- and polynucleotides. ORGANOPHOSPHORUS CHEMISTRY 2012. [DOI: 10.1039/9781849734875-00169] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- David Loakes
- Medical Research Council Laboratory of Molecular Biology, Hills Road Cambridge CB2 2QH UK
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13
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Vaidyanathan VG, Cho BP. Sequence Effects on Translesion Synthesis of an Aminofluorene–DNA Adduct: Conformational, Thermodynamic, and Primer Extension Kinetic Studies. Biochemistry 2012; 51:1983-95. [DOI: 10.1021/bi2017443] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- V. G. Vaidyanathan
- 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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14
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Jain V, Hilton B, Patnaik S, Zou Y, Chiarelli MP, Cho BP. Conformational and thermodynamic properties modulate the nucleotide excision repair of 2-aminofluorene and 2-acetylaminofluorene dG adducts in the NarI sequence. Nucleic Acids Res 2012; 40:3939-51. [PMID: 22241773 PMCID: PMC3351159 DOI: 10.1093/nar/gkr1307] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Nucleotide excision repair (NER) is a major repair pathway that recognizes and corrects various lesions in cellular DNA. We hypothesize that damage recognition is an initial step in NER that senses conformational anomalies in the DNA caused by lesions. We prepared three DNA duplexes containing the carcinogen adduct N-(2'-deoxyguanosin-8-yl)-7-fluoro-2-acetylaminofluorene (FAAF) at G(1), G(2) or G(3) of NarI sequence (5'-CCG(1)G(2)CG(3)CC-3'). Our (19)F-NMR/ICD results showed that FAAF at G(1) and G(3) prefer syn S- and W-conformers, whereas anti B-conformer was predominant for G(2). We found that the repair of FAAF occurs in a conformation-specific manner, i.e. the highly S/W-conformeric G(3) and -G(1) duplexes incised more efficiently than the B-type G(2) duplex (G(3)∼G(1)> G(2)). The melting and thermodynamic data indicate that the S- and W-conformers produce greater DNA distortion and thermodynamic destabilization. The N-deacetylated N-(2'-deoxyguanosin-8-yl)-7-fluoro-2-aminofluorene (FAF) adducts in the same NarI sequence are repaired 2- to 3-fold less than FAAF: however, the incision efficiency was in order of G(2)∼G(1)> G(3), a reverse trend of the FAAF case. We have envisioned the so-called N-acetyl factor as it could raise conformational barriers of FAAF versus FAF. The present results provide valuable conformational insight into the sequence-dependent UvrABC incisions of the bulky aminofluorene DNA adducts.
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Affiliation(s)
- Vipin Jain
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI 02881, USA
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15
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Liang F, Cho BP. Conformational and thermodynamic impact of bulky aminofluorene adduction on simulated translesion DNA synthesis. Chem Res Toxicol 2011; 24:597-605. [PMID: 21410284 DOI: 10.1021/tx2000587] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We report a systematic spectroscopic investigation on the conformational evolution during primer extension of a bulky fluoroaminofluorene-modified dG adduct (FAF-dG) in chemically simulated translesion synthesis. FAF-dG was paired either with dC or dA (dC-match and dA-mismatch series, respectively). Dynamic (19)F NMR/CD results showed that the FAF-adduct exists in a syn/anti equilibrium and that its conformational characteristics are modulated by the identity of an inserted nucleotide at the lesion site and the extent of primer elongation. At the pre-insertion site, the adduct adopted preferentially a syn conformation where FAF stacked with preceding bases. Insertion of the correct nucleotide dC at the lesion site and subsequent elongation resulted in a gradual transition to the anti conformation. By contrast, the syn conformer was persistent along with primer extension in the dA-mismatch series. In the dC-match series, FAF-induced thermal (T(m)) and thermodynamic (-ΔG°(37 °C)) stabilities were significantly reduced relative to those of the controls. However, the corresponding T(m) and -ΔG°(37 °C) values were increased in the FAF-modified mismatched dA series. The lesion impact persisted up to three 5'-nucleotides from the lesion. Occupation of the minor groove of the W-conformer with the bulky carcinogenic fluorene moiety not only would limit the DNA mobility but also would impose a serious difficulty for the active site of a polymerase throughout the replication process. Our spectroscopic results are consistent with reported data on AF, which showed dramatic (~10(4)-fold) differences in the nucleotide insertion rates between the dC-match and dA-mismatch series. The results emphasize the importance of adduct-induced steric constraints for determining the replication fidelity of a polymerase.
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Affiliation(s)
- Fengting Liang
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI 02881, United States
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