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PDBsum entry 3cq8
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Transferase/DNA
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PDB id
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3cq8
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References listed in PDB file
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Key reference
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Title
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Characterization of a replicative DNA polymerase mutant with reduced fidelity and increased translesion synthesis capacity.
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Authors
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X.Zhong,
L.C.Pedersen,
T.A.Kunkel.
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Ref.
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Nucleic Acids Res, 2008,
36,
3892-3904.
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PubMed id
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Abstract
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Changing a highly conserved amino acid in motif A of any of the four yeast
family B DNA polymerases, DNA polymerase alpha, delta, epsilon or zeta, results
in yeast strains with elevated mutation rates. In order to better understand
this phenotype, we have performed structure-function studies of homologous
mutants of RB69 DNA polymerase (RB69 pol), a structural model for family B
members. When Leu415 in RB69 pol is replaced with phenylalanine or glycine, the
mutant polymerases retain high-catalytic efficiency for correct nucleotide
incorporation, yet have increased error rates due to increased misinsertion,
increased mismatch extension and inefficient proofreading. The Leu415Phe mutant
also has increased dNTP insertion efficiency opposite a template 8-oxoG and
opposite an abasic site. The 2.5 A crystal structure of a ternary complex of
RB69 L415F pol with a correctly base-paired incoming dTTP reveals that the
phenylalanine ring is accommodated within a cavity seen in the wild-type enzyme,
without steric clash or major change in active site geometry, consistent with
retention of high-catalytic efficiency for correct incorporation. In addition,
slight structural differences were observed that could be relevant to the
reduced fidelity of L415F RB69 pol.
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