Mutagenesis, Vol. 15, No. 2, 121-125,
March 2000
© 2000 UK Environmental Mutagen Society/Oxford University Press
Spontaneous and osmium tetroxide-induced mutagenesis in an Escherichia coli strain deficient in both endonuclease III and endonuclease VIII
Biological Institute, Graduate School of Science, Tohoku University, Sendai 980-8578 and 1 Department of Radiology, School of Veterinary Medicine, University of Osaka Prefecture, Sakai 599-8531, Japan
Thymine glycol, uracil glycol, 5-hydroxycytosine and 5-hydroxyuracil are common base lesions produced by cellular metabolism as well as ionizing radiation and environmental carcinogens. Escherichia coli DNA glycosylase, endonuclease III and endonuclease VIII recognize and remove these lesions from DNA. In this study, we assessed the mutagenic potential of these lesions in the supF gene as a forward mutation target in double-stranded plasmid DNA using an E.coli strain deficient in both endonuclease III and endonuclease VIII. These lesions were introduced into pTN89 DNA by the chemical oxidant osmium tetroxide. Spontaneous supF mutations occurred at a frequency of 3.03x10–7 and osmium tetroxide-induced at a frequency of 8.25x10–7. Sequence analysis of supF mutants revealed that mutations occurred at cytosine sites rather than thymine sites, suggesting that thymine glycol is not the principal premutagenic lesion. In contrast, G:C
A:T transitions were dominantly detected in the spontaneous and osmium tetroxide-induced mutations in the endonuclease III and endonuclease VIII double defective host. In this case, products of cytosine oxidation such as 5-hydroxycytosine, which are the substrate for endonuclease III and endonuclease VIII, were the principal mutagenic lesions.
2 To whom correspondence should be addressed. Tel: +81 22 217 6706; Fax: +81 22 217 6706; Email: yamamot{at}mail.cc.tohoku.ac.jp
3 Present address: Department of Cell Biology, Graduate School of Medicine, Tohoku University, Sendai 980-8575, Japan
4 Present address: School of Environmental Science, Division of Science, Murdoch University, Murdoch, WA 6150, Australia
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  S. M. Bharatan, M. Reddy, and J. Gowrishankar Distinct Signatures for Mutator Sensitivity of lacZ Reversions and for the Spectrum of lacI/lacO Forward Mutations on the Chromosome of Nondividing Escherichia coli Genetics, February 1, 2004; 166(2): 681 - 692. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. Mashimo, M. Kawata, and K. Yamamoto Roles of the RecJ and RecQ proteins in spontaneous formation of deletion mutations in the Escherichia coli K12 endogenous tonB gene Mutagenesis, July 1, 2003; 18(4): 355 - 363. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. Nilsen and H. E. Krokan Base excision repair in a network of defence and tolerance Carcinogenesis, July 1, 2001; 22(7): 987 - 998. [Full Text] [PDF]
|
|