Enzymatic repair of 5-formyluracil. II. Mismatch formation between 5- formyluracil and guanine during DNA replication and its recognition by two proteins involved in base excision repair (AlkA) and mismatch repair (MutS)

Hiroaki Terato, Aya Masaoka, Mutsumi Kobayashi, Sachiko Fukushima, Yoshihiko Ohyama, Mitsuo Yoshida, Hiroshi Ide

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

5-Formyluracil (fU), a major methyl oxidation product of thymine, forms correct (fU:A) and incorrect (fU:G) base pairs during DNA replication. In the accompanying paper (Masaoka, A., Terato, H., Kobayashi, M., Honsho, A., Ohyama, Y., and Ide, H. (1999) J. Biol. Chem. 274, 25136-25143), it has been shown that fU correctly paired with A is recognized by AlkA protein (Escherichia coli 3-methyladenine DNA glycosylase II). In the present work, mispairing frequency of fU with G and cellular repair protein that specifically recognized fU:G mispairs were studied using defined oligonucleotide substrates. Mispairing frequency of fU was determined by incorporation of 2'-deoxyribonucleoside 5'-triphosphate of fU opposite template G using DNA polymerase I Klenow fragment deficient in 3'-5' exonuclease. Mispairing frequency of fU was dependent on the nearest neighbor base pair in the primer terminus and 2-12 times higher than that of thymine at pH 7.8 and 2.6-6.7 times higher at pH 9.0 with an exception of the nearest neighbor T(template):A(primer). AlkA catalyzed the excision of fU placed opposite G, as well as A, and the excision efficiencies of fU for fU:G and fU:A pairs were comparable. In addition, MutS protein involved in methyl- directed mismatch repair also recognized fU:G mispairs and bound them with an efficiency comparable to T:G mispairs, but it did not recognize fU:A pairs. Prior complex formation between MutS and a heteroduplex containing an fU:G mispair inhibited the activity of AlkA to fU. These results suggest that fU present in DNA can be restored by two independent repair pathways, i.e. the base excision repair pathway initiated by AlkA and the methyl-directed mismatch repair pathway initiated by MutS. Biological relevance of the present results is discussed in light of DNA replication and repair in cells.

Original languageEnglish
Pages (from-to)25144-25150
Number of pages7
JournalJournal of Biological Chemistry
Volume274
Issue number35
DOIs
Publication statusPublished - Aug 27 1999
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Fingerprint Dive into the research topics of 'Enzymatic repair of 5-formyluracil. II. Mismatch formation between 5- formyluracil and guanine during DNA replication and its recognition by two proteins involved in base excision repair (AlkA) and mismatch repair (MutS)'. Together they form a unique fingerprint.

  • Cite this