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M94B0817.TXT
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1994-11-11
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Document 0817
DOCN M94B0817
TI Nucleotide insertion and primer extension at abasic template sites in
different sequence contexts.
DT 9412
AU Goodman MF; Cai H; Bloom LB; Eritja R; Department of Biological
Sciences, University of Southern; California, Los Angeles 90089-1340.
SO Ann N Y Acad Sci. 1994 Jul 29;726:132-42; discussion 142-3. Unique
Identifier : AIDSLINE MED/94379618
AB Efficiencies of insertion and extension at a single site-directed abasic
lesion, X, were measured while varying 5'- and 3'-template bases
adjacent to X. The preference for insertion was found to be A > G > T
approximately C, with the upstream (3'-neighboring) template base
perturbing insertion efficiencies by an order of magnitude or more.
Efficiencies of synthesis past the abasic lesion depended strongly on
the downstream (5'-neighboring) template base and on the properties of
the polymerase. HIV-1 RT favored direct extension of X.A > X.G > X.T >
X.C, by addition of the next correct nucleotide. However, it was found
that X.C, least favored for direct extension, was most favored for
misalignment extension, occurring when the DNA structure in the vicinity
of the lesion collapsed to realign a primer 3'-C terminus opposite a
downstream template G site. Polymerase properties have an important role
in copying abasic lesions. Drosophila DNA polymerase alpha, HIV-1, and
AMV reverse transcriptases had little difficulty inserting opposite
abasic lesions, with efficiencies comparable to misinsertions opposite
normal template bases. However, AMV RT did not extent past the lesion
using direct or misalignment mechanisms. Wild-type and mutant T4 DNA
polymerases were used to show that although exonucleolytic proofreading
inhibits lesion bypass, the presence of a highly active proofreading
exonuclease is not sufficient to prevent bypass.
DE *DNA Damage *DNA Primers *DNA Repair Nucleotides Support, Non-U.S.
Gov't Support, U.S. Gov't, P.H.S. Templates JOURNAL ARTICLE REVIEW
REVIEW, TUTORIAL
SOURCE: National Library of Medicine. NOTICE: This material may be
protected by Copyright Law (Title 17, U.S.Code).