Characterization of spontaneous mutation in the oxyR strain of Escherichia coli

Eiji Yamamura, Tatsuo Nunoshiba, Masakado Kawata, Kazuo Yamamoto

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


Escherichia coli K-12 strain EY5, deficient in oxyR, was constructed to assess the role of oxyR and oxyR-regulated regulon in spontaneous mutagenesis. Mutagenesis was monitored by selecting two forward mutations of colicin B-sensitive to resistance and valine-sensitive to resistance, one base substitution mutation of rifampicin-sensitive to resistance and one reversion of argE3 his-4 to Arg+ His+. Deficiency of oxyR did not lead to the enhancement of spontaneous mutation frequencies of the four markers tested. By DNA sequence analysis, we determined 49 colicin B-resistant mutants derived from EY5 and found that 37% were base substitutions, 29% IS element insertions, 20% deletions, and 14% single base frameshifts. Among the base substitutions, G:C→T:A transversions predominated followed by G:C→A:T transitions and A:T→T:A transversions. These spectra were essentially the same as those from oxyR+ strains. The results indicate that oxyR and oxyR-regulated genes do not play a significant role in the defense against spontaneous mutagenesls.

Original languageEnglish
Pages (from-to)427-432
Number of pages6
JournalBiochemical and Biophysical Research Communications
Issue number2
Publication statusPublished - 2000


  • Hydrogen peroxide
  • oxyR
  • Spontaneous mutagenesis
  • tonB gene


Dive into the research topics of 'Characterization of spontaneous mutation in the oxyR strain of Escherichia coli'. Together they form a unique fingerprint.

Cite this