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PDBsum entry 3raq
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Transferase/DNA
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PDB id
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3raq
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References listed in PDB file
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Key reference
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Title
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Implications for damage recognition during dpo4-Mediated mutagenic bypass of m1g and m3c lesions.
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Authors
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O.Rechkoblit,
J.C.Delaney,
J.M.Essigmann,
D.J.Patel.
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Ref.
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Structure, 2011,
19,
821-832.
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PubMed id
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Abstract
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DNA is susceptible to alkylation damage by a number of environmental agents that
modify the Watson-Crick edge of the bases. Such lesions, if not repaired, may be
bypassed by Y-family DNA polymerases. The bypass polymerase Dpo4 is strongly
inhibited by 1-methylguanine (m1G) and 3-methylcytosine (m3C), with nucleotide
incorporation opposite these lesions being predominantly mutagenic. Further,
extension after insertion of both correct and incorrect bases, introduces
additional base substitution and deletion errors. Crystal structures of the Dpo4
ternary extension complexes with correct and mismatched 3'-terminal primer bases
opposite the lesions reveal that both m1G and m3C remain positioned within the
DNA template/primer helix. However, both correct and incorrect pairing partners
exhibit pronounced primer terminal nucleotide distortion, being primarily
evicted from the DNA helix when opposite m1G or misaligned when pairing with
m3C. Our studies provide insights into mechanisms related to hindered and
mutagenic bypass of methylated lesions and models associated with damage
recognition by repair demethylases.
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