Kamiya H, Kasai H
Department of Environmental Oncology, Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu 807, Japan.
Nucleic Acids Res. 1997 Jan 15;25(2):304-11. doi: 10.1093/nar/25.2.304.
To evaluate the mutation frequency and the mutation spectrum of 2-hydroxyadenine (2-OH-Ade), an oxidative DNA lesion, the modified base was site-specifically incorporated into a unique restriction enzyme site (SalI, GTCGAC or AflII, CTTAAG where A* represents 2-OH-Ade) in single- and double-stranded vectors. The 2-OH-Ade residues were introduced into (+)- and (-)-strands of the double-stranded vectors and into the (+)-strand of single-stranded vectors. When the vectors were transfected intoEscherichia coli, the modified base showed little to no cytotoxicity. The mutation frequencies of 2-OH-Ade in the SalI and AflII sites were approximately 0.8 and 0.07%, respectively, with double-stranded (+)-vectors. An increase in the mutation frequencies was not observed with single-stranded vectors. When incorporated into the (-)-strand, the mutation frequencies of 2-OH-Ade in the SalI and AflII sites were approximately 0.3 and 0.1%, respectively. The mutations observed most frequently were -1 deletions at both positions, in the case of the (+)-strand. On the other hand, we observed that 2-OH-Ade in the (-)-strand induced A-->G and A-->T substitutions. These results indicate that 2-OH-Ade residues in DNA induce substitution and deletion mutations without blocking replication inE.coli.
为了评估氧化DNA损伤产物2-羟基腺嘌呤（2-OH-Ade）的突变频率和突变谱，将该修饰碱基位点特异性地掺入单链和双链载体中的一个独特限制性酶切位点（SalI，GTCGAC或AflII，CTTAAG，其中A*代表2-OH-Ade）。2-OH-Ade残基被引入双链载体的（+）链和（-）链以及单链载体的（+）链中。当这些载体转染到大肠杆菌中时，该修饰碱基几乎没有显示出细胞毒性。在双链（+）载体中，SalI和AflII位点处2-OH-Ade的突变频率分别约为0.8%和0.07%。单链载体未观察到突变频率增加。当掺入（-）链时，SalI和AflII位点处2-OH-Ade的突变频率分别约为0.3%和0.1%。在（+）链的情况下，最常观察到的突变是两个位置的-1缺失。另一方面，我们观察到（-）链中的2-OH-Ade诱导A→G和A→T替换。这些结果表明，DNA中的残基2-OH-Ade在大肠杆菌中诱导替换和缺失突变，而不会阻断复制。
