Dynamic basis for dG.dT misincorporation via tautomerization and ionization

Article

关键词: DNA-POLYMERASE EPSILON;    MISPAIRING FREQUENCIES;    STRUCTURAL INSIGHTS;    CHEMICAL-EXCHANGE;    KINETIC MECHANISM;    NMR-SPECTROSCOPY;    FIDELITY;    REPLICATION;    RNA;    SELECTION;   

DOI  :  10.1038/nature25487

来源: SCIE

【 摘 要 】

Tautomeric and anionic Watson-Crick-like mismatches have important roles in replication and translation errors through mechanisms that are not fully understood. Here, using NMR relaxation dispersion, we resolve a sequence-dependent kinetic network connecting G center dot T/U wobbles with three distinct Watson-Crick mismatches: two rapidly exchanging tautomeric species (G(enol)center dot T/U reversible arrow G center dot T-enol/U-enol; population less than 0.4%) and one anionic species (G center dot T-/U-; population around 0.001% at neutral pH). The sequence-dependent tautomerization or ionization step was inserted into a minimal kinetic mechanism for correct incorporation during replication after the initial binding of the nucleotide, leading to accurate predictions of the probability of dG center dot dT misincorporation across different polymerases and pH conditions and for a chemically modified nucleotide, and providing mechanisms for sequence-dependent misincorporation. Our results indicate that the energetic penalty for tautomerization and/or ionization accounts for an approximately 10(-2) to 10(-3)-fold discrimination against misincorporation, which proceeds primarily via tautomeric dG(enol)center dot dT and dG center dot dT(enol), with contributions from anionic dG center dot dT(-) dominant at pH 8.4 and above or for some mutagenic nucleotides.

【 授权许可】

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