Nucleic Acids Research, 1988, Vol. 16, No. 24 11607-11615
© 1988
MOLECULAR BIOLOGY |
Specific binding of o-phenanthroline at a DNA structural lesion
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School Boston, MA 02115, USA
+Present address: Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
Received August 5, 1988. Revised November 16, 1988. Accepted November 16, 1988.
DNA intercalators are found to recognize a DNA lesion as a high affinity receptor site. This lesion-specific binding is observed when one strand of a DNA double helix contains an extra, unpaired nucleotide. Our assay for binding controls for the effects of sequence with a series of oligodeoxynucleotide duplexes which are identical except for the location of the lesion, an extra cytidine. Scission of the series of oligodeoxynucleotides by the cuprous complex of ortho-phenanthroline (OP-Cu) indicates that OP-Cu binds at the lesion-specific stable intercalation site, suggesting that OP-Cu intercalates into DNA. The dispersion of OP-Cu scission sites over three residues is consistent with scission via a diffusible intermediate. The location of the scission sites, directly on the 3' side of the lesion, is consistent with minor groove binding in B DNA.