High-resolution mapping of carcinogen binding sites on DNA

We have used a photochemical method to map covalent binding sites of the carcinogen benzo[a]pyrenediol epoxide (BPDE) within DNA from the transcriptional control region of the chicken adult beta-globin gene. Our preliminary low-resolution mapping has demonstrated that this region contains highly preferred BPDE binding sites [Boles, T.C., & Hogan, M.E. (1984) Proc. Natl. Acad. Sci. U.S.A. 81, 5623-5627]. Here, we find that BPDE binding at individual G residues in this region is influenced by nearest-neighbor interactions and also by longer range interactions that may be attributable to sequence-specific variation of DNA secondary structure. Our findings suggest that long poly(dG) sequences should be preferred sites for BPDE action in other genes.