University of Rhode Island Kingston, Rhode Island, United States
Purpose: Arylamines are used to study mutagenicity and are implicated in various human cancers. Fluoroaminofluorene guanine adduct (dG-FAF) is arylamine DNA bulky lesions that produces a mixture of syn-stacked(S) and anti-major groove (B) conformational heterogeneity. Its sequence dependence may implicate the outcomes of DNA replication and mutagenicity. 5-Methylcytosine, methylation of cytosine, regulates gene transcription and epigenetic modifications. In this study, we report the replication block and mutagenicity of the dG-FAF adduct and different epigenetic-related sequences. Methods: We synthesized and identified the site-specifically context 5’- CTTCTC#G*NCCTCATTC -3’ (where C#= cytosine or 5-methylcytosine; G*= dG-FAF; N= A, C, T, or G) with dG-FAF adduct oligonucleotides. Following the replication bypass [Competitive Replication and Adduct Bypass (CRAB)] and mutagenicity [Restriction Endonuclease and Post-labeling (REAP)] Assays. Results: The results show that the change of replication bypass ratio of dG-FAF in sequence-dependent manners in those various sequence contexts and the flanking 5-methylcytosine affects the bypass efficiency significantly (P < 0.05). Conclusion: dG-FAF lesion has sequence-specific effects on the bypass efficiency. 5-Methylcytosine modified epigenetic sequences showed interesting replication block patterns in those sequences.
