Preparation and characterization of an aflatoxin B1 adduct with the oligodeoxynucleotide d(ATCGAT)2

Gopalakrishnan, Sandeep; Stone, Michael P.; Harris, Thomas M.

doi:10.1021/ja00200a051

Cited by 58 publications

(65 citation statements)

References 8 publications

(12 reference statements)

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“…1) at the position of X were prepared as described previously (6,30). Nondamaged (ND) oligodeoxynucleotides (12-and 46-mers) with a dG in place of AFB 1 -N7-Gua and primer DNAs were obtained from Integrated DNA Technologies, Inc.…”

Section: Methodsmentioning

confidence: 99%

Error-prone Replication Bypass of the Primary Aflatoxin B1 DNA Adduct, AFB1-N7-Gua

Lin¹,

Makarova

et al. 2014

Journal of Biological Chemistry

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Background: Aflatoxin B 1 exposure causes mutations that are associated with liver cancer. Results: The AFB 1 -N7-Gua adduct is highly mutagenic in primate cells, with contributions by both replicative and translesion synthesis DNA polymerases. Conclusion: AFB 1 -N7-Gua adduct is a biologically relevant DNA adduct. Significance: This is the first study demonstrating the mutagenicity of AFB 1 -N7-Gua in mammalian cells and the identification of candidate DNA polymerases involved in these processes.

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Section: Methodsmentioning

confidence: 99%

Error-prone Replication Bypass of the Primary Aflatoxin B1 DNA Adduct, AFB1-N7-Gua

Lin¹,

Makarova

et al. 2014

Journal of Biological Chemistry

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“…All reactions were performed under an argon atmosphere and at room temperature. The compounds were characterized by 1 H, 13 C, and 31 P NMR (when applicable) and high-resolution MS.…”

Section: Methodsmentioning

confidence: 99%

“…Additional evidence for a 5Ј intercalation event arises from stoichiometric studies with the two self-complementary hexamers ATCGAT and ATGCAT. Reaction with excess AFB 1 epoxide yields only a 1:1 ratio of AFB 1 to the duplex oligonucleotide (ATCGAT) 2 , where the two guanines share the same 5Ј intercalation site; in contrast, in the case where distinct 5Ј intercalation sites exist in each strand, a 2:1 AFB 1 ͞ (ATGCAT) 2 ratio is observed (13). Furthermore, modifications of the ring systems in AFB 1 that decrease planarity and therefore intercalation ability, a situation that exists with aflatoxin G 1 , decrease affinity for DNA and result in lower reactivity (14).…”

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confidence: 98%

“…Study of the chemical basis of this hotspot has been hampered by the presence of numerous guanines in the nucleotide sequence surrounding codon 249. Due to the formidable obstacle of resolving and purifying highly labile AFB 1 adducts from complex mixtures of multiple reaction products, the synthesis of site-specifically modified AFB 1 adducts thus far has been limited to targets containing a single target guanine (4,13). In light of the above observations suggesting that intercalation of AFB 1 epoxide precedes covalent bond formation, we reasoned that physical occupation of an intercalation site with a thymidinebenzofuran photoproduct would inhibit intercalation by AFB 1 epoxide and thereby prevent the formation of an AFB 1 adduct at the proximal guanine (Fig.…”

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confidence: 99%

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An intercalation inhibitor altering the target selectivity of DNA damaging agents: Synthesis of site-specific aflatoxin B ₁ adducts in a p53 mutational hotspot

Kobertz

Wang

Wogan

et al. 1997

Proc. Natl. Acad. Sci. U.S.A.

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Af latoxin B 1 (AFB 1 ) is a potent human carcinogen implicated in the etiology of hepatocellular carcinoma. Upon metabolic activation to the reactive epoxide, AFB 1 forms DNA adducts primarily at the N7 position of guanines. To elucidate more fully the molecular mechanism of AFB 1 -induced mutagenesis, an intercalation inhibitor was designed to probe the effects of intercalation by AFB 1 epoxide on its reaction with DNA. DNA duplexes were prepared consisting of a target strand containing multiple potentially reactive guanines and a nontarget strand containing a cis-syn thymidinebenzofuran photoproduct. Because the covalently linked benzofuran moiety physically occupies an intercalation site, we reasoned that such a site would be rendered inaccessible to AFB 1 epoxide. By strategic positioning of this intercalation inhibitor in the intercalation site 5 to a specific guanine, the adduct yield at that site was greatly diminished, indicating that intercalation by AFB 1 epoxide contributes favorably to adduct formation. Using this approach it has been possible to simplify the production of site-specifically modified oligonucleotides containing AFB 1 adducts in the sequence context of a p53 mutational hotspot. Moreover, we report herein isolation of site-specifically AFB 1 -modified oligonucleotides in sequences containing multiple guanines. Use of intercalation inhibitors will facilitate both investigation of the ability of other carcinogens to intercalate into DNA and the synthesis of specific carcinogen-DNA adducts.Exposure to aflatoxin B 1 (AFB 1 ) and infection by hepatitis B virus are known risk factors for hepatocellular carcinoma (1). The molecular mechanism of human hepatocellular carcinogenesis is poorly defined, but AFB 1 is known to be a potent mutagen and hence may induce the mutations that appear in end-stage tumors. Upon metabolic activation to the exo-8,9-epoxide, AFB 1 reacts almost exclusively with the N7 of guanine to form guanine DNA adducts (AFB 1 -N7-Gua) ( Fig. 1) (2). Analysis of bacterial mutational spectra and phage genomes containing a specific AFB 1 -N7-Gua adduct reveals G3T substitutions as the predominant mutagenic event (3, 4). Interestingly, approximately 50% of hepatocellular carcinomas in portions of eastern Asia and sub-Saharan Africa, where exposure to AFB 1 through contaminated food is a frequent event, possess G:C3T:A transversions in the third position of codon 249 of the p53 tumor suppressor gene (5-7).A recent advance in chemical synthesis has facilitated the production of AFB 1 epoxide, which has enabled investigations of the mechanism of the reaction of AFB 1 epoxide with DNA (8). Current evidence suggests that formation of AFB 1 -N7-Gua DNA adducts proceeds through a transition state in which the AFB 1 epoxide is intercalated on the 5Ј side of the target guanine. This hypothesis is supported by the observation that the reactivity of AFB 1 epoxide with double-stranded B-form DNA is greatly enhanced as compared with single-stranded DNA or alternative duplex structure...

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“…The epoxide reacts rapidly with water, t 1/2 = <1 sec at ambient temperature and pH 7.0, 2 but reaction with duplex DNA occurs much more rapidly leading to high adduction yields. 1,3 The reaction occurs almost exclusively at the N7 position of guanine. Excellent results have been obtained in preparation of adducted oligonucleotides in cases where only one guanine is present in a chain but the presence of multiple guanines creates separation problems since all can potentially react with the epoxide (Scheme 1).…”

Section: Direct Adductionmentioning

confidence: 99%

Synthesis of oligodeoxynucleotides bearing structurally defined adducts of mutagens

Harris

Harris²

2001

Arkivoc

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Methodology is reviewed for the preparation of oligodeoxynucleotides bearing site-specific adducts of mutagens. Examples are presented of the use of the three general synthetic approaches: (1) direct adduction of oligonucleotides, (2) introduction of adducted nucleosides during oligonucleotide assembly, and (3) post-oligomerization methods in which an oligonucleotide is assembled containing an electrophilic equivalent of the target nucleoside, followed by formation of the adduct by condensation with a nucleophilic equivalent of the mutagen. The merits and limitations of the three methods are discussed.

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Preparation and characterization of an aflatoxin B1 adduct with the oligodeoxynucleotide d(ATCGAT)2

Cited by 58 publications

References 8 publications

Error-prone Replication Bypass of the Primary Aflatoxin B1 DNA Adduct, AFB1-N7-Gua

Error-prone Replication Bypass of the Primary Aflatoxin B1 DNA Adduct, AFB1-N7-Gua

An intercalation inhibitor altering the target selectivity of DNA damaging agents: Synthesis of site-specific aflatoxin B ₁ adducts in a p53 mutational hotspot

Synthesis of oligodeoxynucleotides bearing structurally defined adducts of mutagens

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Preparation and characterization of an aflatoxin B1 adduct with the oligodeoxynucleotide d(ATCGAT)2

Cited by 58 publications

References 8 publications

Error-prone Replication Bypass of the Primary Aflatoxin B1 DNA Adduct, AFB1-N7-Gua

Error-prone Replication Bypass of the Primary Aflatoxin B1 DNA Adduct, AFB1-N7-Gua

An intercalation inhibitor altering the target selectivity of DNA damaging agents: Synthesis of site-specific aflatoxin B 1 adducts in a p53 mutational hotspot

Synthesis of oligodeoxynucleotides bearing structurally defined adducts of mutagens

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An intercalation inhibitor altering the target selectivity of DNA damaging agents: Synthesis of site-specific aflatoxin B ₁ adducts in a p53 mutational hotspot