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Long patch base excision repair compensates for DNA polymerase β inactivation by the C4'-oxidized abasic site.

Authors
  • Jacobs, Aaron C
  • Kreller, Cortney R
  • Greenberg, Marc M
Type
Published Article
Journal
Biochemistry
Publisher
American Chemical Society
Publication Date
Jan 11, 2011
Volume
50
Issue
1
Pages
136–143
Identifiers
PMID: 21155533
Source
Medline
License
Unknown

Abstract

The C4'-oxidized abasic site (C4-AP), which is produced by a variety of damaging agents, has significant consequences for DNA. The lesion is highly mutagenic and reactive, resulting in interstrand cross-links. The base excision repair of DNA containing independently generated C4-AP was examined. C4-AP is incised by Ape1 ~12-fold less efficiently than an apurinic/apyrimidinic lesion. DNA polymerase β induces the β-elimination of incised C4-AP in ternary complexes, duplexes, and single-stranded substrate. However, excision from a ternary complex is most rapid. In addition, the lesion inactivates the enzyme after approximately seven turnovers on average by reacting with one or more lysine residues in the lyase active site. Unlike 5'-(2-phosphoryl-1,4-dioxobutane), which very efficiently irreversibly inhibits DNA polymerase β, the lesion is readily removed by strand displacement synthesis conducted by the polymerase in conjunction with flap endonuclease 1. DNA repair inhibition by C4-AP may be a partial cause of the cytotoxicity of drugs that produce this lesion.

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