PHOTOAFFINITY-LABELING OF A DNA-BINDING SITE ON THE GLOBULAR DOMAIN OF HISTONE H5

We have labelled a DNA-binding site on the globular domain of histone H5 (GH5) by ultraviolet activated cross-linking of a self-complementar y 5-bromodeoxyuridine (5BrU)-substituted oligonucleotide with the sequ ence 5'-AGCGA5BrUATCGCT-3'. Cross-linking was to His62, mainly to the protein backbone. This observation provides further support for the mo de of binding of GH5 to DNA proposed on the basis of the similarity be tween the X-ray crystal structure of GH5 and the DNA-bound structures of catabolite activator protein and hepatic nuclear factor 3 gamma [Ra makrishnan, V. (1994) Curr. Opin. Struct Biol. 4, 44-50].