Generation, biological consequences and repair mechanisms of cytosine deamination in DNA

Shin Ichiro Yonekura, Nobuyai Nakamura, Shuji Yonei, Qiu Mei Zhang-Akiyama

Research output: Contribution to journalArticlepeer-review

32 Citations (Scopus)


Base moieties in DNA are spontaneously threatened by naturally occurring chemical reactions such as deamination, hydrolysis and oxidation. These DNA modifications have been considered to be major causes of cell death, mutations and cancer induction in organisms. Organisms have developed the DNA base excision repair pathway as a defense mechanism to protect them from these threats. DNA glycosylases, the key enzyme in the base excision repair pathway, are highly conserved in evolution. Uracil constantly occurs in DNA. Uracil in DNA arises by spontaneous deamination of cytosine to generate pro-mutagenic U:G mispairs. Uracil in DNA is also produced by the incorporation of dUMP during DNA replication. Uracil-DNA glycosylase (UNG) acts as a major repair enzyme that protects DNA from the deleterious consequences of uracil. The first UNG activity was discovered in E. coli in 1974. This was also the first discovery of base excision repair. The sequence encoded by the ung gene demonstrates that the E. coli UNG is highly conserved in viruses, bacteria, archaea, yeast, mice and humans. In this review, we will focus on central and recent findings on the generation, biological consequences and repair mechanisms of uracil in DNA and on the biological significance of uracil-DNA glycosylase.

Original languageEnglish
Pages (from-to)19-26
Number of pages8
JournalJournal of radiation research
Issue number1
Publication statusPublished - 2009
Externally publishedYes

ASJC Scopus subject areas

  • Radiation
  • Radiology Nuclear Medicine and imaging
  • Health, Toxicology and Mutagenesis


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