KsgA, a 16S rRNA adenine methyltransferase, has a novel DNA glycosylase/ AP lyase activity to prevent mutations in Escherichia coli

Qiu Mei Zhang-Akiyama, Hironobu Morinaga, Masahiro Kikuchi, Shin Ichiro Yonekura, Hiroshi Sugiyama, Kazuo Yamamoto, Shuji Yonei

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13 Citations (Scopus)

Abstract

The 5-formyluracil (5-foU), a major mutagenic oxidative damage of thymine, is removed from DNA by Nth, Nei and MutM in Escherichia coli. However, DNA polymerases can also replicate past the 5-foU by incorporating C and G opposite the lesion, although the mechanism of correction of the incorporated bases is still unknown. In this study, using a borohydride-trapping assay, we identified a protein trapped by a 5-foU/C-containing oligonucleotide in an extract from E. coli mutM nth nei mutant. The protein was subsequently purified from the E. coli mutM nth nei mutant and was identified as KsgA, a 16S rRNA adenine methyltransferase. Recombinant KsgA also formed the trapped complex with 5-foU/C- and thymine glycol (Tg)/C-containing oligonucleotides. Furthermore, KsgA excised C opposite 5-foU, Tg and 5-hydroxymethyluracil (5-hmU) from duplex oligonucleotides via a β-elimination reaction, whereas it could not remove the damaged base. In contrast, KsgA did not remove C opposite normal bases, 7,8-dihydro-8-oxoguanine and 2-hydroxyadenine. Finally, the introduction of the ksgA mutation increased spontaneous mutations in E. coli mutM mutY and nth nei mutants. These results demonstrate that KsgA has a novel DNA glycosylase/ AP lyase activity for C mispaired with oxidized T that prevents the formation of mutations, which is in addition to its known rRNA adenine methyltransferase activity essential for ribosome biogenesis.

Original languageEnglish
Pages (from-to)2116-2125
Number of pages10
JournalNucleic acids research
Volume37
Issue number7
DOIs
Publication statusPublished - 2009

ASJC Scopus subject areas

  • Genetics

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    Zhang-Akiyama, Q. M., Morinaga, H., Kikuchi, M., Yonekura, S. I., Sugiyama, H., Yamamoto, K., & Yonei, S. (2009). KsgA, a 16S rRNA adenine methyltransferase, has a novel DNA glycosylase/ AP lyase activity to prevent mutations in Escherichia coli. Nucleic acids research, 37(7), 2116-2125. https://doi.org/10.1093/nar/gkp057