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Endonuclease VII of phage T4 nicks N-2-acetylaminofluorene-induced DNA structures in vitro
E Bertrand-Burggraf1, B Kemper, R P Fuchs
1UPR 9003 de Cancérogenèse et de Mutagenèse Moléculaire et Structurale, Institut de Biologie Moléculaire et Cellulaire du Centre National de la Recherche Scientifique, Strasbourg, France.
Abstract:
We have tested in vitro the activity of T4 endonuclease VII on three different double-stranded oligonucleotides bearing a single N-2-acetylaminofluorene (AAF) adduct covalently bound to each of the three guanine residues located within the NarI site (G1G2CG3CC), a strong frameshift mutation hot spot in E. coli. With the oligonucleotides modified at G2 and G3 a specific cleavage pattern with T4 endonuclease VII was observed in the complementary strand while no cleavage was found in the adduct-bearing strand. On the other hand, when G1 was modified, only a very faint cleavage band was observed (< 1%). These differences in nicking among the three AAF-modified DNA substrates are discussed in terms of the polymorphic nature in adduct-induced DNA structures as previously shown. This "non-physiological" activity of a DNA resolvase is discussed in terms of a potential role for such enzymes in the induction of frameshift mutations.