NMR study of stacking interactions and conformational adjustments in the dinucleotide-carcinogen adduct 2'-deoxycytidylyl-(3 .fwdarw. 5)-2'-deoxy-8-(N-fluoren-2-ylacetamido)guanosine

Evans, Frederick E.; Levine, Robert A.

doi:10.1021/bi00408a057

Cited by 13 publications

(15 citation statements)

References 56 publications

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“…Thus, the dG-unit can correctly pair with an incoming dCTP in the active site by forming a Watson-Crick base pair (14,18,19). The acetylated bulky adducts in contrast, are not bypassed by high-fidelity polymerases because these lesions are fixed in the syn-conformation (10,16,17,(29)(30)(31)(32), independent of the size of the aromatic unit attached to the C8 portion of the dG base (29). Faithful bypass of the acetylated lesions in vivo is achieved by low-fidelity TLS polymerases, with Pol η playing a major role (5-7).…”

Section: Discussionmentioning

confidence: 99%

Mechanism of replication blocking and bypass of Y-family polymerase η by bulky acetylaminofluorene DNA adducts

Schorr

Schneider²,

Lammens³

et al. 2010

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

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Heterocyclic aromatic amines produce bulky C8 guanine lesions in vivo, which interfere and disrupt DNA and RNA synthesis. These lesions are consequently strong replication blocks. In addition bulky adducts give rise to point and frameshift mutations. The translesion synthesis (TLS) DNA polymerase η is able to bypass slowly C8 bulky adduct lesions such as the widely studied 2-aminofluorene-dG and its acetylated analogue mainly in an error-free manner. Replicative polymerases are in contrast fully blocked by the acetylated lesion. Here, we show that TLS efficiency of Pol η depends critically on the size of the bulky adduct forming the lesion. Based on the crystal structure, we show why the bypass reaction is so difficult and we provide a model for the bypass reaction. In our model, TLS is accomplished without rotation of the lesion into the anti conformation as previously thought.DNA damage | DNA polymerase | translesion DNA synthesis | aromatic amines A romatic amines are known to be strong carcinogens. After metabolic activation, aromatic amines react as electrophilic arylnitrenium ions with nucleophilic functionalities of the DNA duplex. Preferred reaction sides are the amino groups of adenine and guanine and particularly the C8-position of guanine (1, 2). The latter reaction gives rise to the so called C8-bulky adduct lesions, which interfere with the replication process leading to mutations (2). Two types of aromatic amine lesions are known. The nonacetylated lesions depicted in Fig. 1A reduce the replication efficiency but are in general faithfully bypassed by highfidelity polymerases (3). In contrast, the acetylated derivatives ( Fig. 1B) block replicative polymerases (3, 4), but can be bypassed with special low-fidelity polymerases (5-9). Moreover, if these acetylated lesions are present in certain repetitive sequences, they are known to induce frameshift mutations (4,(10)(11)(12). Recently, in vivo experiments revealed that the low-fidelity Y-family polymerase η is able to replicate DNA containing acetylated aromatic amine lesions such as the acetylated analogue of 2-aminofluorene-dG (AF-dG), 2-acetylaminofluorene-dG (AAF-dG) (13). Replication through the lesion is even for Pol η very difficult and hence slow, but if it occurs it is typically error free.The distinct mutagenic properties of the acetylated and nonacetylated aromatic amine lesions are caused by their different conformational preferences. While the nonacetylated lesions exist both in syn and anti conformation (14, 15), the corresponding acetylated lesions seem to adopt the syn-conformation with high preference (10,16,17). Crystal structures of Ellenberger, Beese, and Patel, showing the nonacetylated AF-dG-lesion inside different polymerases, prove that the lesion is indeed bound in anti conformation, allowing Watson-Crick base pairing with an incoming dCTP (18)(19)(20). While bypass of the nonacetylated lesions by high-fidelity polymerases is rather well understood, the mechanism that allows low-fidelity polymerases such as Pol η to replicate...

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Section: Discussionmentioning

confidence: 99%

Mechanism of replication blocking and bypass of Y-family polymerase η by bulky acetylaminofluorene DNA adducts

Schorr

Schneider²,

Lammens³

et al. 2010

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

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“…As noted in the Introduction, several studies have shown that the binding of acetoxyAAF distorts the structure of the DNA (8)(9)(10)(11)(12)(13)(14)(15) and other studies have indicated that altering the structure of a DNA sequence affects the activity of restriction enzymes on that sequence (16)(17)(18)(19)(20). Thus the inhibitions observed arise from the presence of AAF adducts near the putative restriction enzyme cleavage sites.…”

Section: T G T G a G C G C T G T T G C T A A G T G *2258 A T G A Gcagmentioning

confidence: 99%

“…Early studies suggested that AAF adducts can produce base displacement type distortions (8)(9)(10) or B-Z structural conversions (11)(12)(13). Krugh and co-workers recently presented NMR data suggesting that the binding of an AAF adduct leads to the flipping of the adduct-bound guanine to the syn conformation with concommitant disruption of the surrounding helix (14).…”

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confidence: 99%

Locating Binding Sites for the Carcinogen N-Acetoxy-N-Acetyl-2-Aminofluorene Using Restriction Enzyme Inhibition Assays

Mallamaci

Bascoy

Brown

et al. 1992

Journal of Biomolecular Structure and Dynamics

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Restriction enzyme inhibition studies have been employed to map the locations of high affinity binding sites of the carcinogen N-acetoxy-N-acetyl-2-aminofluorene (acetoxyAAF) on pBR322, phiX174 and SV40 DNAs. Bound carcinogen levels were kept low (less than 20 bound AAF moieties per DNA molecule) in order to observe only the binding to the high affinity sites. Inhibition of certain restriction enzymes was observed in a limited number of locations on these DNAs. Inhibition increased as bound AAF increased and the particular restriction enzymes inhibited varied with location. On all three DNAs, activities of these enzymes was not affected in other locations. Comparison of the sequences at the sites of inhibition on the three DNAs indicates that all sites have common sequence elements: the presence of either the sequence T(C/G)TT(G/C) or the sequence T(G/C)CTT(G/C).

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“…As noted earlier, lambda exonuclease is a highly processive enzyme which is sensitive to regions of altered DNA structure, such as denatured regions (9). Evidence suggests that the binding of acetoxyAAF distorts the structure of the DNA around the binding site (10)(11)(12)(13)(14)(15). The lambda exonuclease would be inhibited from digestion in such regions and thus an attempted digestion of acetoxy AAF bound DNA fragments would produce partially digested fragments.…”

Section: Resultsmentioning

confidence: 95%

“…These properties make lambda exonuclease an ideal probe for locating DNA sequences which might be structurally altered by the presence of bound acetoxyAAF moieties. Lambda exonuclease activity is inhibited by the presence of denaturation such as is believed to occur upon formation of acetoxyAAF adducts (10)(11)(12)(13)(14)(15). Due to such inhibition, enzyme digestion is prematurely halted, resulting in subfragments of the original Hinf I fragment.…”

Section: Introductionmentioning

confidence: 99%

Using Lambda Exonuclease Inhibition Assays to Map Carcinogen Binding Sites

Combates

Winkle²

1992

Journal of Biomolecular Structure and Dynamics

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Previous restriction mapping studies (M.A. Mallamaci, D.P. Reed and S.A. Winkle, J. Biomolecular Structure and Dynamics, in press (1992)) have indicated that a small number of locations on the plasmid pBR322 may be high affinity binding sites for the carcinogen N-acetoxy-N-acetyl-2-aminofluorene (acetoxyAAF). PBR322 was reacted with acetoxyAAF to produce DNA with one, three or seven acetoxyAAF moieties per DNA molecule. Thus only the higher affinity binding sites are affected. Subsequent digestion with the restriction enzyme Hinf I produced fragments containing previously indicated locations of potential acetoxyAAF binding sites. Fragments thought not to contain binding sites were also examined as controls. The isolated fragments, singly 32P end-labeled, were digested with lambda exonuclease. The three fragments suspected of containing acetoxyAAF binding sites possess new lambda exonuclease inhibition sites when the fragments are obtained from acetoxyAAF reacted DNA. No such inhibition sites are found with the two fragments suggested previously not to contain acetoxyAAF binding sites. These carcinogen produced inhibition sites occur in sequences which are similar, suggesting that acetoxyAAF preferentially may target a small number of sequences.

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NMR study of stacking interactions and conformational adjustments in the dinucleotide-carcinogen adduct 2'-deoxycytidylyl-(3 .fwdarw. 5)-2'-deoxy-8-(N-fluoren-2-ylacetamido)guanosine

Cited by 13 publications

References 56 publications

Mechanism of replication blocking and bypass of Y-family polymerase η by bulky acetylaminofluorene DNA adducts

Mechanism of replication blocking and bypass of Y-family polymerase η by bulky acetylaminofluorene DNA adducts

Locating Binding Sites for the Carcinogen N-Acetoxy-N-Acetyl-2-Aminofluorene Using Restriction Enzyme Inhibition Assays

Using Lambda Exonuclease Inhibition Assays to Map Carcinogen Binding Sites

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