NMR Data Show that the Carcinogen N‐2‐Acetylaminofluorene Stabilises an Intermediate of −2 Frameshift Mutagenesis in a Region of High Mutation Frequency

Milhe, Catherine; Fuchs, Robert P. P.; Lefèvre, Jean‐François

doi:10.1111/j.1432-1033.1996.00120.x

Cited by 50 publications

(76 citation statements)

References 20 publications

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“…As a result, the 5Ј-G AAF pC dinucleotide in the template strand remains unpaired. We have previously shown that the G-AAF adduct stabilizes such a slipped structure by virtue of stacking interactions between the aromatic AAF moiety with the adjacent bases (33)(34)(35). We suggest that the LT can adopt two conformations.…”

Section: Characterization Of the Frameshift Replication Intermediate mentioning

confidence: 99%

Mechanism of DNA polymerase II-mediated frameshift mutagenesis

Bécherel

Fuchs

2001

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

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Escherichia coli possesses three SOS-inducible DNA polymerases (Pol II, IV, and V) that were recently found to participate in translesion synthesis and mutagenesis. Involvement of these polymerases appears to depend on the nature of the lesion and its local sequence context, as illustrated by the bypass of a single N-2-acetylaminofluorene adduct within the NarI mutation hot spot. Indeed, error-free bypass requires Pol V (umuDC), whereas mutagenic (؊2 frameshift) bypass depends on Pol II (polB). In this paper, we show that purified DNA Pol II is able in vitro to generate the ؊2 frameshift bypass product observed in vivo at the NarI sites. Although the ⌬polB strain is completely defective in this mutation pathway, introduction of the polB gene on a low copy number plasmid restores the ؊2 frameshift pathway. In fact, modification of the relative copy number of polB versus umuDC genes results in a corresponding modification in the use of the frameshift versus error-free translesion pathways, suggesting a direct competition between Pol II and V for the bypass of the same lesion. Whether such a polymerase competition model for translesion synthesis will prove to be generally applicable remains to be confirmed. NarI mutation hot spot ͉ translesion synthesis ͉ slippage mutagenesis ͉ N-2-acetylaminofluorene ͉ umuDC (Pol V) P oint mutations are formed during DNA replication either as genuine replication errors or as a consequence of the presence of damage in the parental DNA. By changing the chemical structure of the bases, damaging agents are often effective blocks to the progression of replicative DNA polymerases. It has now become clear that these blocks are overcome by specialized enzymes (translesional DNA polymerases) that can read through damaged bases in a process known as translesion synthesis (TLS) (1-5). Because of the presence of the lesion, this process is inevitably less accurate than normal replication and will thus trigger increased mutation rates in the newly synthesized strand opposite the damaged base.Recently it was shown that in Escherichia coli, all three SOS-inducible DNA polymerases, Pol II (polB), Pol IV (dinB), and Pol V (umuDC), can be involved in TLS, depending on the nature of the DNA damage and its sequence context (6). We have identified an intriguing situation where the bypass of a given lesion, N-2-acetylaminofluorene (AAF), located within a frameshift mutation hot spot, the NarI site, is mediated by two genetically distinct pathways. Indeed, in that sequence context, the bypass of an AAF guanine adduct requires Pol V for nonslipped elongation, yielding error-free TLS but Pol II for slipped elongation, thus producing Ϫ2 frameshift TLS (6). The nonslipped TLS pathway obeys the rules previously described for base substitution mutagenesis induced by UV light or abasic sites, i.e., Pol V and RecA* dependence (for a recent review, see ref. 7). In contrast, the involvement of DNA Pol II in the slipped Ϫ2 frameshift pathway is more intriguing. Although a series of phenotypes related to DNA repair...

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Section: Characterization Of the Frameshift Replication Intermediate mentioning

confidence: 99%

Mechanism of DNA polymerase II-mediated frameshift mutagenesis

Bécherel

Fuchs

2001

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

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“…However, the molecular understanding of how they exert mutation in vivo is generally poor and is complicated by adduct-induced conformational heterogeneities. The AAF-adduct exists predominantly in the base-displaced "stacked" (S) conformation (9)(10)(11). Because it lacks Watson-Crick base pairs at the lesion site, the AAF-adduct produces a major structural distortion in DNA.…”

Section: And N-(2′-deoxyguanosin-8-yl)-2-aminofluorene (Af)mentioning

confidence: 99%

Examination of the Long-range Effects of Aminofluorene-induced Conformational Heterogeneity and Its Relevance to the Mechanism of Translesional DNA Synthesis

Meneni¹,

Liang²,

Cho³

2007

Journal of Molecular Biology

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SUMMARYAdduct-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. In the present study, we conducted 19 F NMR, CD, Tm, 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 Tm 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 and 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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“…To simulate the two-base slippage product, Fuchs and Romano independently examined the thermal stability of an oligonucleotide duplex in which the GpC nucleotides opposite the C8-AAF adduct were deleted (41,46). The C8-AAF adduct at the G 3 -position was found to stabilize the duplex relative to the unmodified oligonucleotide by 15 °C.…”

Section: Thermal Melting (T M ) Studies Of Iq-adducted Oligo-nucleotidesmentioning

confidence: 99%

Conformational Differences of the C8-Deoxyguanosine Adduct of 2-Amino-3-methylimidazo[4,5-f]quinoline (IQ) within the NarI Recognition Sequence

Elmquist

Wang

Stover

et al. 2007

Chem. Res. Toxicol.

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Abstract2-Amino-3-methylimidazo [4,5-f]quinoline (IQ) is a highly mutagenic heterocyclic amine found in cooked meats. The major DNA adduct of IQ is at the C8-position of dGuo. We have previously reported the incorporation of the C8-IQ adduct into oligonucleotides, namely, the G 1 -position of codon 12 of the N-ras oncogene sequence (G 1 G 2 T) and the G 3 -position of the NarI recognition sequence (G 1 G 2 CG 3 CC) (Elmquist et al. (2004) J. Am. Chem. Soc. 126, 11189-11201). Ultraviolet spectroscopy and circular dichroism studies indicated that the conformation of the adduct in the two oligonucleotides was different, and they were assigned as groove-bound and base-displaced intercalated, respectively. The conformation of the latter was subsequently confirmed through NMR and restrained molecular dynamics studies (Wang et al. (2006) J. Am. Chem. Soc. 128, 10085-10095). We report here the incorporation of the C8-IQ adduct into the G 1 -and G 2 -positions of the NarI sequence. A complete analysis of the UV, CD, and NMR chemical shift data for the IQ protons are consistent with the IQ adduct adopting a minor groove-bound conformation at the G 1 -and G 2 -positions of the NarI sequence. To further correlate the spectroscopic data with the adduct conformation, the C8-aminofluorene (AF) adduct of dGuo was also incorporated into the NarI sequence; previous NMR studies demonstrated that the AF-modified oligonucleotides were in a sequence-dependent conformational exchange between major groove-bound and base-displaced intercalated conformations. The spectroscopic data for the IQ-and AF-modified oligonucleotides are compared. The sequence-dependent conformational preferences are likely to play a key role in the repair and mutagenicity of C8-arylamine adducts.

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NMR Data Show that the Carcinogen N‐2‐Acetylaminofluorene Stabilises an Intermediate of −2 Frameshift Mutagenesis in a Region of High Mutation Frequency

Cited by 50 publications

References 20 publications

Mechanism of DNA polymerase II-mediated frameshift mutagenesis

Mechanism of DNA polymerase II-mediated frameshift mutagenesis

Examination of the Long-range Effects of Aminofluorene-induced Conformational Heterogeneity and Its Relevance to the Mechanism of Translesional DNA Synthesis

Conformational Differences of the C8-Deoxyguanosine Adduct of 2-Amino-3-methylimidazo[4,5-f]quinoline (IQ) within the NarI Recognition Sequence

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