Nucleic Acids Research, Vol 27, Issue 2 496-502, Copyright © 1999 by Oxford University Press
V Duarte, JG Muller and CJ Burrows
Oxidative damage to DNA bases commonly resultsin the formation of oxidized
purines, particularly 7,8-dihydro-8-oxoguanine (8-oxoG) and
7,8-dihydro-8-oxoadenine (8-oxoA), the former being a well-known mutagenic
lesion. Since 8-oxoG is readily subject to further oxidation compared with
normal bases, the insertion of a base during DNA synthesis opposite an
oxidized form of 8-oxoG was investigated in vitro. A synthetic template
containing a single 8-oxoG lesion was first treated with different
one-electron oxidants or under singlet oxygen conditions and then subjected
to primer extension catalyzed by Klenow fragment exo- (Kf exo-), calf
thymus DNA polymerase alpha (pol alpha) or human DNA polymerase beta (pol
beta). Consistent with previous reports, dAMP and dCMP are inserted
selectively opposite 8-oxoG with all three DNA polymerases. Interestingly,
oxidation of 8-oxoG was found to induce dAMP and dGMP insertion opposite
the lesion by Kf exo- with transient inhibition of primer extension
occurring at the site of the modified base. Furthermore, the lesion
constitutes a block during DNA synthesis by pol alpha and pol beta.
Experiments with an 8-oxoA- modified template oligonucleotide show that
both 8-oxoA and an oxidized form of 8-oxoA direct insertion of dTMP by Kf
exo-. Mass spectrometric analysis of 8-oxoG-containing oligonucleotides
before and after oxidation with IrCl62-are consistent with oxidation of
primarily the 8- oxoG site, resulting in formation of a guanidinohydantoin
moiety as the major product. No evidence for formation of abasic sites was
obtained. These results demonstrate that an oxidized form of 8-oxoG,
possibly guanidinohydantoin, may direct misreading and misinsertion of
dNTPs during DNA synthesis. If such a process occurred in vivo, it would
represent a point mutagenic lesion leading to G-->T and G-->C
transversions. However, the corresponding oxidized form of 8-oxoA primarily
shows correct insertion of T during DNA synthesis with Kf exo- .
ARTICLES
Insertion of dGMP and dAMP during in vitro DNA synthesis opposite an oxidized form of 7,8-dihydro-8-oxoguanine
Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, UT 84112-0850, USA.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  M. Ganguly, F. Wang, M. Kaushik, M. P. Stone, L. A. Marky, and B. Gold A study of 7-deaza-2'-deoxyguanosine 2'-deoxycytidine base pairing in DNA Nucleic Acids Res., September 25, 2007; 35(18): 6181 - 6195. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 W. L. Neeley, S. Delaney, Y. O. Alekseyev, D. F. Jarosz, J. C. Delaney, G. C. Walker, and J. M. Essigmann DNA Polymerase V Allows Bypass of Toxic Guanine Oxidation Products in Vivo J. Biol. Chem., April 27, 2007; 282(17): 12741 - 12748. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
V. I. Bruskov, L. V. Malakhova, Z. K. Masalimov, and A. V. Chernikov Heat-induced formation of reactive oxygen species and 8-oxoguanine, a biomarker of damage to DNA Nucleic Acids Res., March 15, 2002; 30(6): 1354 - 1363. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
X. Li, P. M. Wright, and A-L. Lu The C-terminal Domain of MutY Glycosylase Determines the 7,8-Dihydro-8-oxo-guanine Specificity and Is Crucial for Mutation Avoidance J. Biol. Chem., March 17, 2000; 275(12): 8448 - 8455. [Abstract] [Full Text] [PDF]
|
|