Examination of the long-range effects of aminofluorene-induced conformational heterogeneity and its relevance to the mechanism of translesional DNA synthesis
| Autor: | Bongsup P. Cho, Srinivasarao Meneni, Fengting Liang |
|---|---|
| Rok vydání: | 2006 |
| Předmět: |
DNA Replication
Models Molecular DNA polymerase Stereochemistry Base pair Base Pair Mismatch Article chemistry.chemical_compound DNA Adducts Structural Biology Molecular Biology Conformational isomerism Base Pairing Nuclear Magnetic Resonance Biomolecular Polymerase Fluorenes biology Molecular Structure Oligonucleotide Chemistry Circular Dichroism DNA replication Temperature Hydrogen Bonding DNA Templates Genetic biology.protein Nucleic Acid Conformation Primer (molecular biology) DNA Damage |
| Zdroj: | Journal of molecular biology. 366(5) |
| ISSN: | 0022-2836 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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