DNA METHYLATION BY N-METHYL-N-NITROSOUREA - METHYLATION PATTERN CHANGES IN SINGLE-STRANDED AND DOUBLE-STRANDED DNA, AND IN DNA WITH MISMATCHED OR BULGED GUANINES
Rl. Wurdeman et al., DNA METHYLATION BY N-METHYL-N-NITROSOUREA - METHYLATION PATTERN CHANGES IN SINGLE-STRANDED AND DOUBLE-STRANDED DNA, AND IN DNA WITH MISMATCHED OR BULGED GUANINES, Nucleic acids research, 21(21), 1993, pp. 4975-4980
The detection of abnormal DNA base pairing arrangements and conformati
ons is chemically probed in synthetic P-32-end-labeled deoxyribonucleo
tide oligomers using N-methyl-N-nitrosourea (MNU) and etraazabicyclo-[
11.3.1]heptadeca-1-[17],2,11,13,15 pentaene-Ni (II) (Ni-complex) with
KHSO5. The DNA targets studied are single-stranded (s-s) DNA, double-s
tranded (d-s) DNA, d-s DNA with G-G, G-A and G-T mismatches, d-s DNA w
ith a single bulged G and d-s DNA with two bulged G's. The effect of t
he non-Watson - Crick structures on the formation of N7-methylguanine
(N7-MeG) by MNU and the oxidation of G by Ni-complex is reported along
with the T(m)'s and circular dichroism spectra of the different duple
x oligomers. The results for MNU and Ni-complex show that the qualitat
ive and quantitative character of the cleavage patterns at a G3 run ch
ange with the nature of the abnormal base pairing motif. Based on the
DNA substrates studied, the results indicate that a combination of rea
gents which report electronic and steric perturbations can be a useful
approach to monitor DNA mismatches and bulges