1
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Crisalli AM, Chen YT, Cai A, Li D, Cho BP. Conformation-dependent lesion bypass of bulky arylamine-dG adducts generated from 2-nitrofluorene in epigenetic sequence contexts. Nucleic Acids Res 2023; 51:12043-12053. [PMID: 37953358 PMCID: PMC10711442 DOI: 10.1093/nar/gkad1038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Revised: 09/27/2023] [Accepted: 10/24/2023] [Indexed: 11/14/2023] Open
Abstract
Sequence context influences structural characteristics and repair of DNA adducts, but there is limited information on how epigenetic modulation affects conformational heterogeneity and bypass of DNA lesions. Lesions derived from the environmental pollutant 2-nitrofluorene have been extensively studied as chemical carcinogenesis models; they adopt a sequence-dependent mix of two significant conformers: major groove binding (B) and base-displaced stacked (S). We report a conformation-dependent bypass of the N-(2'-deoxyguanosin-8-yl)-7-fluoro-2-aminofluorene (dG-FAF) lesion in epigenetic sequence contexts (d[5'-CTTCTC#G*NCCTCATTC-3'], where C# is C or 5-methylcytosine (5mC), G* is G or G-FAF, and N is A, T, C or G). FAF-modified sequences with a 3' flanking pyrimidine were better bypassed when the 5' base was 5mC, whereas sequences with a 3' purine exhibited the opposite effect. The conformational basis behind these variations differed; for -CG*C- and -CG*T-, bypass appeared to be inversely correlated with population of the duplex-destabilizing S conformer. On the other hand, the connection between conformation and a decrease in bypass for flanking purines in the 5mC sequences relative to C was more complex. It could be related to the emergence of a disruptive non-S/B conformation. The present work provides novel conformational insight into how 5mC influences the bypass efficiency of bulky DNA damage.
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Affiliation(s)
- Alicia M Crisalli
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI 02881, USA
| | - Yi-Tzai Chen
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI 02881, USA
| | - Ang Cai
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI 02881, USA
| | - Deyu Li
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI 02881, USA
| | - Bongsup P Cho
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI 02881, USA
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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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Evdokimov AN, Tsidulko AY, Popov AV, Vorobiev YN, Lomzov AA, Koroleva LS, Silnikov VN, Petruseva IO, Lavrik OI. Structural basis for the recognition and processing of DNA containing bulky lesions by the mammalian nucleotide excision repair system. DNA Repair (Amst) 2018; 61:86-98. [DOI: 10.1016/j.dnarep.2017.10.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 10/05/2017] [Accepted: 10/23/2017] [Indexed: 11/30/2022]
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4
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Jahnz-Wechmann Z, Lisowiec-Wachnicka J, Framski G, Kosman J, Boryski J, Pasternak A. Thermodynamic, structural and fluorescent characteristics of DNA hairpins containing functionalized pyrrolo-2′-deoxycytidines. Bioorg Chem 2017; 71:294-298. [DOI: 10.1016/j.bioorg.2017.02.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 01/30/2017] [Accepted: 02/26/2017] [Indexed: 12/22/2022]
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5
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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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6
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Sproviero M, Verwey AMR, Rankin KM, Witham AA, Soldatov DV, Manderville RA, Fekry MI, Sturla SJ, Sharma P, Wetmore SD. Structural and biochemical impact of C8-aryl-guanine adducts within the NarI recognition DNA sequence: influence of aryl ring size on targeted and semi-targeted mutagenicity. Nucleic Acids Res 2014; 42:13405-21. [PMID: 25361967 PMCID: PMC4245952 DOI: 10.1093/nar/gku1093] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Chemical mutagens with an aromatic ring system may be enzymatically transformed to afford aryl radical species that preferentially react at the C8-site of 2′-deoxyguanosine (dG). The resulting carbon-linked C8-aryl-dG adduct possesses altered biophysical and genetic coding properties compared to the precursor nucleoside. Described herein are structural and in vitro mutagenicity studies of a series of fluorescent C8-aryl-dG analogues that differ in aryl ring size and are representative of authentic DNA adducts. These structural mimics have been inserted into a hotspot sequence for frameshift mutations, namely, the reiterated G3-position of the NarI sequence within 12mer (NarI(12)) and 22mer (NarI(22)) oligonucleotides. In the NarI(12) duplexes, the C8-aryl-dG adducts display a preference for adopting an anti-conformation opposite C, despite the strong syn preference of the free nucleoside. Using the NarI(22) sequence as a template for DNA synthesis in vitro, mutagenicity of the C8-aryl-dG adducts was assayed with representative high-fidelity replicative versus lesion bypass Y-family DNA polymerases, namely, Escherichia coli pol I Klenow fragment exo− (Kf−) and Sulfolobus solfataricus P2 DNA polymerase IV (Dpo4). Our experiments provide a basis for a model involving a two-base slippage and subsequent realignment process to relate the miscoding properties of C-linked C8-aryl-dG adducts with their chemical structures.
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Affiliation(s)
- Michael Sproviero
- Department of Chemistry and Toxicology, University of Guelph, Guelph, Ontario, Canada, N1G 2W1
| | - Anne M R Verwey
- Department of Chemistry and Toxicology, University of Guelph, Guelph, Ontario, Canada, N1G 2W1
| | - Katherine M Rankin
- Department of Chemistry and Toxicology, University of Guelph, Guelph, Ontario, Canada, N1G 2W1
| | - Aaron A Witham
- Department of Chemistry and Toxicology, University of Guelph, Guelph, Ontario, Canada, N1G 2W1
| | - Dmitriy V Soldatov
- Department of Chemistry and Toxicology, University of Guelph, Guelph, Ontario, Canada, N1G 2W1
| | - Richard A Manderville
- Department of Chemistry and Toxicology, University of Guelph, Guelph, Ontario, Canada, N1G 2W1
| | - Mostafa I Fekry
- Department of Health Sciences and Technology, Institute of Food, Nutrition and Health, ETH Zürich, 8032 Zürich, Switzerland Pharmacognosy Department, Faculty of Pharmacy, Cairo University, Kasr El-Aini, Cairo 11562, Egypt
| | - Shana J Sturla
- Department of Health Sciences and Technology, Institute of Food, Nutrition and Health, ETH Zürich, 8032 Zürich, Switzerland
| | - Purshotam Sharma
- Department of Chemistry & Biochemistry, University of Lethbridge, Lethbridge, AB, Canada, T1K 3M4
| | - Stacey D Wetmore
- Department of Chemistry and Toxicology, University of Guelph, Guelph, Ontario, Canada, N1G 2W1 Department of Health Sciences and Technology, Institute of Food, Nutrition and Health, ETH Zürich, 8032 Zürich, Switzerland Pharmacognosy Department, Faculty of Pharmacy, Cairo University, Kasr El-Aini, Cairo 11562, Egypt Department of Chemistry & Biochemistry, University of Lethbridge, Lethbridge, AB, Canada, T1K 3M4
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7
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Sharma P, Manderville RA, Wetmore SD. Structural and energetic characterization of the major DNA adduct formed from the food mutagen ochratoxin A in the NarI hotspot sequence: influence of adduct ionization on the conformational preferences and implications for the NER propensity. Nucleic Acids Res 2014; 42:11831-45. [PMID: 25217592 PMCID: PMC4191402 DOI: 10.1093/nar/gku821] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The nephrotoxic food mutagen ochratoxin A (OTA) produces DNA adducts in rat kidneys, the major lesion being the C8-linked-2′-deoxyguanosine adduct (OTB-dG). Although research on other adducts stresses the importance of understanding the structure of the associated adducted DNA, site-specific incorporation of OTB-dG into DNA has yet to be attempted. The present work uses a robust computational approach to determine the conformational preferences of OTB-dG in three ionization states at three guanine positions in the NarI recognition sequence opposite cytosine. Representative adducted DNA helices were derived from over 2160 ns of simulation and ranked via free energies. For the first time, a close energetic separation between three distinct conformations is highlighted, which indicates OTA-adducted DNA likely adopts a mixture of conformations regardless of the sequence context. Nevertheless, the preferred conformation depends on the flanking bases and ionization state due to deviations in discrete local interactions at the lesion site. The structural characteristics of the lesion thus discerned have profound implications regarding its repair propensity and mutagenic outcomes, and support recent experiments suggesting the induction of double-strand breaks and deletion mutations upon OTA exposure. This combined structural and energetic characterization of the OTB-dG lesion in DNA will encourage future biochemical experiments on this potentially genotoxic lesion.
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Affiliation(s)
- Purshotam Sharma
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, T1K 3M4, Canada
| | - Richard A Manderville
- Department of Chemistry and Toxicology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - Stacey D Wetmore
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, T1K 3M4, Canada
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8
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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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9
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Jain V, Hilton B, Lin B, Jain A, MacKerell AD, Zou Y, Cho BP. Structural and thermodynamic insight into Escherichia coli UvrABC-mediated incision of cluster diacetylaminofluorene adducts on the NarI sequence. Chem Res Toxicol 2013; 26:1251-62. [PMID: 23841451 DOI: 10.1021/tx400186v] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Cluster DNA damage refers to two or more lesions in a single turn of the DNA helix. Such clustering may occur with bulky DNA lesions, which may be responsible for their sequence-dependent repair and mutational outcomes. Here we prepared three 16-mer cluster duplexes in which two fluoroacetylaminofluorene adducts (dG-FAAF) are separated by zero, one, and two nucleotides in the Escherichia coli NarI mutational hot spot (5'-CTCTCG1G2CG3CCATCAC-3'): 5'-CG1*G2*CG3CC-3', 5'-CG1G2*CG3*CC-3', and 5'-CG1*G2CG3*CC-3' (G* = dG-FAAF), respectively. We conducted spectroscopic, thermodynamic, and molecular dynamics studies of these di-FAAF duplexes, and the results were compared with those of the corresponding mono-FAAF adducts in the same NarI sequence [Jain, V., et al. (2012) Nucleic Acids Res. 40, 3939-3951]. Our nucleotide excision repair results showed the diadducts were more reparable than the corresponding monoadducts. Moreover, we observed dramatic flanking base sequence effects on their repair efficiency in the following order: NarI-G2G3 > NarI-G1G3 > NarI-G1G2. The nuclear magnetic resonance, circular dichroism, ultraviolet melting, and molecular dynamics simulation results revealed that in contrast to the monoadducts, diadducts produced a synergistic effect on duplex destabilization. In addition, dG-FAAF at G2G3 and G1G3 destacks the neighboring bases, with greater destabilization occurring with the former. Overall, the results indicate the importance of base stacking and related thermal and thermodynamic destabilization in the repair of bulky cluster arylamine DNA adducts.
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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, USA
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10
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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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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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12
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Manderville RA, Omumi A, Rankin née Schlitt KM, Wilson KA, Millen AL, Wetmore SD. Fluorescent C-linked C8-aryl-guanine probe for distinguishing syn from anti structures in duplex DNA. Chem Res Toxicol 2012; 25:1271-82. [PMID: 22667322 DOI: 10.1021/tx300152q] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The synthesis and optical properties of the carbon (C)-linked C(8)-(2"-benzo[b]thienyl)-2'-deoxyguanosine ((Bth)dG), which acts as a fluorescent reporter of syn versus anti glycosidic conformations in duplex DNA, are described. In the syn-conformation, the probe stabilizes a G:G mismatch, emits at ∼385 nm (excitation ∼285 nm), and shows an induced circular dichroism (ICD) signal at ∼320 nm. Molecular dynamics (MD) simulations predict a wedge (W)-conformation for the mismatched duplex with the C(8)-benzo[b]thienyl moiety residing in the minor groove. In contrast, the probe destabilizes the duplex when base paired with its normal pyrimidine partner C. With flanking purine bases, a major groove B-type duplex is favored with (Bth)dG present in the anti-conformation emitting at ∼413 nm (excitation ∼326 nm) and no ICD signal. However, with flanking pyrimidine bases, (Bth)dG adopts the syn-conformation when base paired with C, and MD simulations predict a base-displaced stacked (S)-conformation, with the opposing C flipped out of the helix. The different duplex (B-, S-, and W-) conformers formed upon incorporation of (Bth)dG are known to play a critical role in the biological activity of N-linked C8-dG adducts formed by arylamine carcinogens. Bulky environment-sensitive fluorescent C(8)-dG adducts that mimic the duplex structures formed by carcinogens may be useful in luminescence-based DNA polymerase assays.
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13
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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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14
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Liang F, Cho BP. Enthalpy-entropy contribution to carcinogen-induced DNA conformational heterogeneity. Biochemistry 2010; 49:259-66. [PMID: 19961237 DOI: 10.1021/bi901629p] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
DNA damage by adduct formation is a critical step for the initiation of carcinogenesis. Aromatic amines are strong inducers of environmental carcinogenesis. Their DNA adducts are known to exist in an equilibrium between the major groove (B) and base-displaced stacked (S) conformations. However, the factors governing such heterogeneity remain unclear. Here we conducted extensive calorimetry/NMR/CD studies on the model DNA lesions caused by fluorinated 2-aminfluorene (FAF) and 4-aminobiphenyl (FABP) in order to gain thermodynamic and kinetic insights into the S/B conformational equilibrium. We demonstrate that there are large differences in enthalpy-entropy compensations for FABP and FAF. The small and flexible FABP exclusively adopts the less perturbed B conformer with small enthalpy (DeltaDeltaH-2.7 kcal/mol)/entropy (DeltaDeltaS-0.7 eu) change. In contrast, FAF stacks better and exists as a mixture of B and S conformers with large enthalpy (DeltaDeltaH-13.4 kcal/mol)/entropy (DeltaDeltaS-34.2 eu) compensation. van't Hoff analysis of dynamic (19)F NMR data indicated DeltaH(B<-->S) = 4.1 kcal/mol in favor of the B conformer and DeltaS(B<-->S) = 15.6 cal mol(-1) K(-1) in favor of the intercalated S conformer. These findings demonstrate that the favorable entropy of the S conformer over B conformer determines the S/B population ratios at physiological temperatures.
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Affiliation(s)
- Fengting Liang
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, Rhode Island 02881, USA
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15
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Brown KL, Roginskaya M, Zou Y, Altamirano A, Basu AK, Stone MP. Binding of the human nucleotide excision repair proteins XPA and XPC/HR23B to the 5R-thymine glycol lesion and structure of the cis-(5R,6S) thymine glycol epimer in the 5'-GTgG-3' sequence: destabilization of two base pairs at the lesion site. Nucleic Acids Res 2009; 38:428-40. [PMID: 19892827 PMCID: PMC2811006 DOI: 10.1093/nar/gkp844] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The 5R thymine glycol (5R-Tg) DNA lesion exists as a mixture of cis-(5R,6S) and trans-(5R,6R) epimers; these modulate base excision repair. We examine the 7:3 cis-(5R,6S):trans-(5R,6R) mixture of epimers paired opposite adenine in the 5′-GTgG-3′ sequence with regard to nucleotide excision repair. Human XPA recognizes the lesion comparably to the C8-dG acetylaminoflourene (AAF) adduct, whereas XPC/HR23B recognition of Tg is superior. 5R-Tg is processed by the Escherichia coli UvrA and UvrABC proteins less efficiently than the C8-dG AAF adduct. For the cis-(5R, 6S) epimer Tg and A are inserted into the helix, remaining in the Watson–Crick alignment. The Tg N3H imine and A N6 amine protons undergo increased solvent exchange. Stacking between Tg and the 3′-neighbor G•C base pair is disrupted. The solvent accessible surface and T2 relaxation of Tg increases. Molecular dynamics calculations predict that the axial conformation of the Tg CH3 group is favored; propeller twisting of the Tg•A pair and hydrogen bonding between Tg OH6 and the N7 atom of the 3′-neighbor guanine alleviate steric clash with the 5′-neighbor base pair. Tg also destabilizes the 5′-neighbor G•C base pair. This may facilitate flipping both base pairs from the helix, enabling XPC/HR23B recognition prior to recruitment of XPA.
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Affiliation(s)
- Kyle L Brown
- Department of Chemistry and Center in Molecular Toxicology, Vanderbilt University, Nashville, TN 37235, USA
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16
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Jain N, Meneni S, Jain V, Cho BP. Influence of flanking sequence context on the conformational flexibility of aminofluorene-modified dG adduct in dA mismatch DNA duplexes. Nucleic Acids Res 2009; 37:1628-37. [PMID: 19151371 PMCID: PMC2655675 DOI: 10.1093/nar/gkn1063] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
When positioned opposite to a dA in a DNA duplex, the prototype arylamine-DNA adduct [N-(2'-deoxyguanosin-yl)-7-fluoro-2-aminofluorene (FAF)] adopts the so-called 'wedge' (W) conformation, in which the carcinogen resides in the minor groove of the duplex. All 16 FAF-modified 12-mer NG*N/NAN dA mismatch duplexes (G* = FAF, N = G, A, C, T) exhibited strongly positive induced circular dichroism in the 290-360 nm range (ICD(290-360 nm)), which supports the W conformation. The ICD(290-360 nm) intensities were the greatest for duplexes with a 3'-flanking T. The AG*N duplex series showed little adduct-induced destabilization. An exception was the AG*T duplex, which displayed two well-resolved signals in the (19)F NMR spectra. This was presumably due to a strong lesion-destabilizing effect of the 3'-T. The flanking T effect was substantiated further by findings with the TG*T duplex, which exhibited greater lesion flexibility and nucleotide excision repair recognition. Adduct conformational heterogeneity decreased in order of TG*T > AG*T > CG*T > AG*A > AG*G > AG*C. The dramatic flanking T effect on W-conformeric duplexes is consistent with the strong dependence of the ICD(290-360) on both temperature and salt concentration and could be extended to the arylamine food mutagens that are biologically relevant in humans.
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Affiliation(s)
- Nidhi Jain
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI 02881, USA
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17
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Gao L, Zhang L, Cho BP, Chiarelli MP. Sequence verification of oligonucleotides containing multiple arylamine modifications by enzymatic digestion and liquid chromatography mass spectrometry (LC/MS). JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2008; 19:1147-1155. [PMID: 18524623 PMCID: PMC2819294 DOI: 10.1016/j.jasms.2008.04.034] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2007] [Revised: 04/25/2008] [Accepted: 04/25/2008] [Indexed: 05/26/2023]
Abstract
An analytical method for the structure differentiation of arylamine modified oligonucleotides (ODNs) using on-line LC/MS analysis of raw exonuclease digests is described. Six different dodeca ODNs derived from the reaction of N-acetoxy-N-(trifluoroacetyl)-2-aminofluorene with the dodeca oligonucleotide 5'-CTCGGCGCCATC-3' are isolated and sequenced with this LC/MS method using 3'- and 5'-exonucleases. When the three products modified by a single aminofluorene (AF) are subjected to 3'-exonuclease digestion, the exonuclease will cleave a modified nucleotide but when di-AF modified ODNs are analyzed the 3'-exonuclease ceases to cleave nucleotides when the first modification is exposed at the 3'-terminus. Small abundances of ODN fragments formed by the cleavage of an AF-modified nucleotide were observed when two of the three di-AF modified ODNs were subjected to 5'-exonuclease digestion. The results of the 5'-exonuclease studies of the three di-AF modified ODNs suggest that as the number of unmodified bases between two modifications in an ODN sequence increases, the easier it becomes to sequence beyond the modification closest to the 5'-terminus. The results of this study indicate that the LC/MS method described here would be useful in sequencing ODNs modified by multiple arylamines to be used as templates for site-specific mutagenesis studies.
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Affiliation(s)
- Lan Gao
- Department of Chemistry, Loyola University, 1068 W. Sheridan Road, Chicago, IL 60626, USA
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18
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Jain N, Reshetnyak YK, Gao L, Chiarelli MP, Cho BP. Fluorescence probing of aminofluorene-induced conformational heterogeneity in DNA duplexes. Chem Res Toxicol 2008; 21:445-52. [PMID: 18193841 DOI: 10.1021/tx7003536] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Fluorescence spectroscopy was used to study carcinogen-induced conformational heterogeneity in DNA duplexes. The fluorophore 2-aminopurine (AP) was incorporated adjacent (5') to the lesion (G*) in eight different DNA duplexes [d(5'-CTTCT PG* NCCTC-3'):d(5'-GAGGN XTAGAAG-3'), G* = FAF adduct, P = AP, N = G, A, C, T, and X = C, A] modified by FAF [ N-(2'-deoxyguanosin-8-yl)-7-fluoro-2-aminofluorene], a fluorine-tagged model DNA adduct derived from the potent carcinogen 2-aminofluorene. Steady-state measurements showed that fluorescence intensity and Stern-Volmer constants ( Ksv) derived from acrylamide quenching experiments decreased for all carcinogen-modified duplexes relative to the controls, which suggests greater AP stacking in the duplex upon adduct formation. Conformation-specific stacking of AP with the neighboring adduct was evidenced by a sequence-dependent variation in fluorescence intensity, position of emission maximum, degree of emission quenching by acrylamide, and temperature-dependent spectral changes. The magnitude of stacking was in the order of FAF residue in base-displaced stacked (S) > minor groove wedged (W) > major groove B type (B). This work represents a novel utility of AP in probing adduct-induced conformational heterogeneities in DNA duplexes.
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Affiliation(s)
- Nidhi Jain
- Department of Biomedical and Pharmaceutical Sciences and Physics, University of Rhode Island, Kingston, RI 02881, USA
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Jain N, Li Y, Zhang L, Meneni SR, Cho BP. Probing the sequence effects on NarI-induced -2 frameshift mutagenesis by dynamic 19F NMR, UV, and CD spectroscopy. Biochemistry 2007; 46:13310-21. [PMID: 17960913 DOI: 10.1021/bi701386f] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The NarI recognition sequence (5'-G1G2CG3CN-3') is the most vulnerable hot spot for frameshift mutagenesis induced by the carcinogen 2-aminofluorene and its analogues in Escherichia coli. Lesioning of the guanine in the G3 position induces an especially high frequency of -2 deletion mutations; vulnerability to these mutations is modulated by the nature of the nucleotide in the N position (C approximately A > G > T). The objective of the present study was to probe the structural basis of this N-mediated influence on the propensity of the G3 lesion to form a slipped mutagenic intermediate (SMI) during translesion synthesis. We studied NarI-based fully paired [(5'-CTCG1G2CG3*CNATC-3')(5'-GATNCGGCCGAG-3'), N = dC or dT] and -2 deletion [(5'-CTCG1G2CG3*CNATC-3')(5'-GATNGCCGAG-3'), N = dC or dT] duplexes, in which G* was either AF [N-(2'-deoxyguanosin-8-yl)-2-aminofluorene] or the 19F probe FAF [N-(2'-deoxyguanosin-8-yl)-7-fluoro-2-aminofluorene]. The latter sequences mimic the bulged SMI for -2 deletion mutations. Dynamic 19F NMR, circular dichroism, and UV melting results indicated that the NarI-dC/-2 deletion duplex adopts exclusively an intercalated conformer, whereas the NarI-dT/-2 deletion duplex exists as multiple conformers. The data support the presence of a putative equilibrium between a carcinogen-intercalated and a carcinogen-exposed SMI for the dT/-2 duplex. A similar dT-induced conformational heterogeneity was observed for the fully paired duplexes in which all three guanines were individually modified by AF or FAF. The frequency of the carcinogen stacked S-conformation was found to be highest (69-75%) at the G3 hot spot in NarI-dC duplexes. Taken together, our results support the hypothesis that the conformational stability of the SMI is a critical determinant for the efficacy of -2 frameshift mutagenesis in the NarI sequence. We also provide evidence for AF/FAF conformational compatibility in the NarI sequences.
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Affiliation(s)
- Nidhi Jain
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, Rhode Island 02881, USA
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20
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Meneni S, Liang F, Cho BP. Examination of the long-range effects of aminofluorene-induced conformational heterogeneity and its relevance to the mechanism of translesional DNA synthesis. J Mol Biol 2006; 366:1387-400. [PMID: 17217958 PMCID: PMC1850230 DOI: 10.1016/j.jmb.2006.12.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2006] [Revised: 12/06/2006] [Accepted: 12/12/2006] [Indexed: 10/23/2022]
Abstract
Adduct-induced conformational heterogeneity complicates the understanding of how DNA adducts exert mutation. A case in point is the N-deacetylated AF lesion [N-(2'-deoxyguanosin-8-yl)-2-aminofluorene], the major adduct derived from the strong liver carcinogen N-acetyl-2-aminofluorene. Three conformational families have been previously characterized and are dependent on the positioning of the aminofluorene rings: B is in the "B-DNA" major groove, S is "stacked" into the helix with base-displacement, and W is "wedged" into the minor groove. Here, we conducted (19)F NMR, CD, T(m), and modeling experiments at various primer positions with respect to a template modified by a fluorine tagged AF-adduct (FAF). In the first set, the FAF-G was paired with C and in the second set it was paired with A. The FAF-G:C oligonucleotides were found to preferentially adopt the B or S-conformers while the FAF-G:A mismatch ones preferred the B and W-conformers. The conformational preferences of both series were dependent on temperature and complementary strand length; the largest differences in conformation were displayed at lower temperatures. The CD and T(m) results are in general agreement with the NMR data. Molecular modeling indicated that the aminofluorene moiety in the minor groove of the W-conformer would impose a steric clash with the tight-packing amino acid residues on the DNA binding area of the Bacillus fragment (BF), a replicative DNA polymerase. In the case of the B-type conformer, the carcinogenic moiety resides in the solvent-exposed major groove throughout the replication/translocation process. The present dynamic NMR results, combined with previous primer extension kinetic data by Miller & Grollman, support a model in which adduct-induced conformational heterogeneities at positions remote from the replication fork affect polymerase function through a long-range DNA-protein interaction.
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Affiliation(s)
| | | | - Bongsup P. Cho
- *Address correspondence to: Bongsup P. Cho, Dept. of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, 41 Lower College Road, Kingston, Rhode Island 02881, Tel. 401-874-5024; Fax. 401-874-5766;
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