Interstrand cross-linking of the 5S DNA of Xenopus borealis.

J.T. Millard, A. Wooley, A. Thompson, J.E. Conklin, J.M. St.Clair

The antitumor activities of agents such as cisplatin, nitrogen mustard, and mitomycin C have been attributed to the ability to form DNA interstrand cross-links. Although the sites of cross-linking have been identified in DNA oligomers for many agents, there is less information about cross-linking sites within genomic DNA. We have examined interstrand cross-linking by cisplatin and diepoxyalkanes within a 154 base pair restriction fragment of the Xenopus borealis 5S RNA gene and found evidence for similar consensus sequences as within DNA oligomers. We are extending our analyses on samples of this DNA reconstituted with chicken histones to form uniquely positioned nucleosomes to see the effects of nucleosomal structure on DNA interstrand cross-linking.