Mechanism of aromatic amine carcinogen bypass by the Y-family polymerase, Dpo4

Bulky DNA damage inhibits DNA synthesis by replicative polymerases and often requires the action of error prone bypass polymerases. The exact mechanism governing adduct-induced mutagenesis and its dependence on the DNA sequence context remains unclear. In this work, we characterize Dpo4 binding conf...

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Bibliographic Details
Published in:Nucleic acids research 2015-11, Vol.43 (20), p.9918-9927
Main Authors: Brenlla, Alfonso, Rueda, David, Romano, Louis J
Format: Article
Language:English
Subjects:
2-Acetylaminofluorene - chemistry
Carcinogens - chemistry
DNA - biosynthesis
DNA - chemistry
DNA - metabolism
DNA Adducts - chemistry
DNA Polymerase beta - metabolism
DNA Primers
Fluorenes - chemistry
Guanine - chemistry
Nucleic Acid Enzymes
Nucleotides - metabolism
Protein Binding
Templates, Genetic
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Summary:Bulky DNA damage inhibits DNA synthesis by replicative polymerases and often requires the action of error prone bypass polymerases. The exact mechanism governing adduct-induced mutagenesis and its dependence on the DNA sequence context remains unclear. In this work, we characterize Dpo4 binding conformations and activity with DNA templates modified with the carcinogenic DNA adducts, 2-aminofluoene (AF) or N-acetyl-2-aminofluorene (AAF), using single-molecule FRET (smFRET) analysis and DNA synthesis extension assays. We find that in the absence of dNTPs, both adducts alter polymerase binding as measured by smFRET, but the addition of dNTPs induces the formation of a ternary complex having what appears to be a conformation similar to the one observed with an unmodified DNA template. We also observe that the misincorporation pathways for each adduct present significant differences: while an AF adduct induces a structure consistent with the previously observed primer-template looped structure, its acetylated counterpart uses a different mechanism, one consistent with a dNTP-stabilized misalignment mechanism.
ISSN:0305-1048
1362-4962
DOI:10.1093/nar/gkv1067