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PDBsum entry 5dba
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Transferase/DNA
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PDB id
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5dba
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References listed in PDB file
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Key reference
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Title
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N7 methylation alters hydrogen-Bonding patterns of guanine in duplex DNA.
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Authors
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Y.Kou,
M.C.Koag,
S.Lee.
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Ref.
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J Am Chem Soc, 2015,
137,
14067-14070.
[DOI no: ]
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PubMed id
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Abstract
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N7-Alkyl-2'-deoxyguanosines are major adducts in DNA that are generated by
various alkylating mutagens and drugs. However, the effect of the N7 alkylation
on the hydrogen-bonding patterns of the guanine remains poorly understood. We
prepared N7-methyl-2'-deoxyguanosine (N7mdG)-containing DNA using a
transition-state destabilization strategy, developed a novel polĪ²-host-guest
complex system, and determined eight crystal structures of N7mdG or dG paired
with dC, dT, dG, and dA. The structures of N7mdG:dC and N7mdG:dG are very
similar to those of dG:dC and dG:dG, respectively, indicating the involvement of
the keto tautomeric form of N7mdG in the base pairings with dC and dG. On the
other hand, the structure of N7mdG:dT shows that the mispair forms three
hydrogen bonds and adopts a Watson-Crick-like geometry rather than a wobble
geometry, suggesting that the enol tautomeric form of N7mdG involves in its base
pairing with dT. In addition, N7mdG:dA adopts a novel shifted anti:syn base pair
presumably via the enol tautomeric form of N7mdG. The polĪ²-host-guest complex
structures reveal that guanine-N7 methylation changes the hydrogen-bonding
patterns of the guanine when paired with dT or dA and suggest that N7 alkylation
may alter the base pairing patterns of guanine by promoting the formation of the
rare enol tautomeric form of guanine.
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