Mutagenicity of the 1-nitropyrene-DNA adduct N-(deoxyguanosin-8-yl)-1-aminopyrene in Escherichia coli located in a nonrepetitive CGC sequence.
1-Nitropyrene, a common environmental pollutant, forms a major DNA adduct, N-(deoxyguanosin-8-yl)-1-aminopyrene (dG(AP)). Mutational spectra of randomly introduced dG(AP) in Escherichia coli included many different types of mutations. However, a prior site-specific study in a CGCG(AP)CG sequence showed only CpG deletions and +1 frame shifts. To further explore the context effects of dG(AP) in mutagenesis, in this work this adduct was incorporated into a nonrepetitive CGC sequence in single-stranded M13mp7L2 DNA. Upon replication of this construct in repair-competent E. coli, one-base deletions and base substitutions were detected. The -1 frame shifts, whose frequency increased 3-6-fold with SOS (to an average frequency of 1.5%), involved deletion of the adjacent C residues. The base substitutions ( approximately 2.2%) included targeted G-to-T and G-to-C transversions, whose frequencies did not increase with SOS. This suggests that dG(AP) mutagenesis is highly dependent on the local DNA sequence.
Bacolod
M D
MD
Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, USA.
Krishnasamy
R
R
Basu
A K
AK
D001482:Base Composition; D004261:DNA Replication / Q000187:drug effects; D004269:DNA, Bacterial / Q000187:drug effects*; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000633:toxicity; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D016296:Mutagenesis; D009152:Mutagenicity Tests; D009153:Mutagens / Q000633:toxicity*; D011721:Pyrenes / Q000633:toxicity*; D012091:Repetitive Sequences, Nucleic Acid; D013014:SOS Response, Genetics / Q000187:drug effects; D014169:Transformation, Bacterial / Q000187:drug effects
D004269:DNA, Bacterial; D009153:Mutagens; D011721:Pyrenes; C045229:N-(deoxyguanosin-8-yl)-1-aminopyrene; D003849:Deoxyguanosine