1 research outputs found
Biochemical Investigations into the Mutagenic Potential of 8‑Oxo-2′-deoxyguanosine Using Nucleotide Analogues
8-Oxo-2′-deoxyguanosine (OdG) is an abundant DNA
lesion
produced during oxidative damage to DNA. It can form relatively stable
base pairs with both dC and dA that mimic natural dG:dC and dT:dA
base pairs, respectively. Thus, when in the template strand, OdG can
direct the insertion of either dCTP or dATP during replication, the
latter of which can lead to a dG → T transversion. The potential
for OdG to cause mutation is dependent on the preference for dCTP
or dATP insertion opposite OdG, as well as the ability to extend past
the resulting base pairs. The C2-amine and C8-oxygen could play major
roles during these reactions since both would lie outside the Watson–Crick
cognate base pairs shape in the major groove when OdG base pairs to
dA and dC, respectively, and both have the ability to form strong
interactions, like hydrogen bonds. To gain a more generalized understanding
of how the C2-amine and C8-oxygen of OdG affect its mutagenic potential,
the incorporation opposite and extension past seven analogues of dG/OdG
that vary at C2 and/or C8 were characterized for three DNA polymerases,
including an exonuclease-deficient version of the replicative polymerase
from RB69 (RB69), human polymerase (pol) β, and polymerase IV
from <i>Sulfolobus solfataricus</i> P2 (Dpo4). Based on
the results from these studies, as well as those from previous studies
with RB69, pol β, Dpo4, and two A-family polymerases, the influence
of the C2-amine and C8-oxygen during each incorporation and extension
reaction with each polymerase is discussed. In general, it appears
that when the C2-amine and the C8-oxygen are in the minor groove,
they allow OdG to retain interactions that are normally present during
insertion and extension. However, when the two groups are in the major
groove, they each tend to form novel active site interactions, both
stabilizing and destabilizing, that are not present during insertion
and extension with natural DNA