TY - JOUR
T1 - Spectrum of N4-aminocytidine mutagenesis
AU - Bessho, Tadayoshi
AU - Matsumoto, Keiko
AU - Nomura, Akinori
AU - Hayatsu, Hikoya
AU - Negishi, Kazuo
N1 - Funding Information:
We thank Dr T. A. Kunkel of the National Institute of Environmental Health Sciences, U.S.A. for valuable discussions and for a gift of mutant M13mp2 phages. This work was supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Culture, Japan (no. 63571942 to K.N.).
PY - 1989/2/20
Y1 - 1989/2/20
N2 - N4-Aminocytidine, a nucleoside analog, is a potent mutagen towards phages, bacteria, Drosophila and mammalian cells in culture. In vitro, biochemical studies indicate that this reagent acts by being incorporated into DNA. To elucidate the mechanism of N4-aminocytidine mutagenesis, it is essential to identify the nature of DNA sequence alterations taking place during the mutagenesis. We have analyzed the nucleotide sequence changes in the lac promoter-lacZα region of M13mp2 phage induced by treatment of phage-infected Escherichia coli with N4-aminocytidine. The sequence alterations of DNA samples from 89 mutants of the phage were determined. These mutants had single point mutations, except one mutant, in which a double point mutation was detected. Several hot spots were found: however, there are no apparent relations to particular DNA sequences regarding the locations of these spots. All the mutations are transitions; neither transversions nor deletions/insertions were found. A feature in these transitions is that the A/T to G/C and G/C to A/T changes occur at approximately equal rates. The overall picture of the mutagenesis is consistent with a scheme in which misincorporation and misreplication caused by the modified cytosine structure are the key steps in the DNA replication leading to transitions. Similar nucleotide alterations were found for the mutagenesis induced by an alkylated derivative, N′-methyl-N4-arninocytidine. N4-Aminocytidine also induced reversions of these mutants; both A/T to G/C and G/C to A/T transitions again took place.
AB - N4-Aminocytidine, a nucleoside analog, is a potent mutagen towards phages, bacteria, Drosophila and mammalian cells in culture. In vitro, biochemical studies indicate that this reagent acts by being incorporated into DNA. To elucidate the mechanism of N4-aminocytidine mutagenesis, it is essential to identify the nature of DNA sequence alterations taking place during the mutagenesis. We have analyzed the nucleotide sequence changes in the lac promoter-lacZα region of M13mp2 phage induced by treatment of phage-infected Escherichia coli with N4-aminocytidine. The sequence alterations of DNA samples from 89 mutants of the phage were determined. These mutants had single point mutations, except one mutant, in which a double point mutation was detected. Several hot spots were found: however, there are no apparent relations to particular DNA sequences regarding the locations of these spots. All the mutations are transitions; neither transversions nor deletions/insertions were found. A feature in these transitions is that the A/T to G/C and G/C to A/T changes occur at approximately equal rates. The overall picture of the mutagenesis is consistent with a scheme in which misincorporation and misreplication caused by the modified cytosine structure are the key steps in the DNA replication leading to transitions. Similar nucleotide alterations were found for the mutagenesis induced by an alkylated derivative, N′-methyl-N4-arninocytidine. N4-Aminocytidine also induced reversions of these mutants; both A/T to G/C and G/C to A/T transitions again took place.
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U2 - 10.1016/0022-2836(89)90311-2
DO - 10.1016/0022-2836(89)90311-2
M3 - Article
C2 - 2648011
AN - SCOPUS:0024476974
SN - 0022-2836
VL - 205
SP - 659
EP - 664
JO - Journal of Molecular Biology
JF - Journal of Molecular Biology
IS - 4
ER -