UNRESTRAINING GENETIC PROCESSES WITH A PROTEIN-DNA HINGE

Genetic processes require direct interactions between proteins bound a t nonadjacent cis elements. Because duplex DNA is rigid, either the pr otein-protein interactions are strong enough to deform the double heli x or some feature of the intervening DNA must encourage juxtaposition of separated sites. For example, bent DNA can bring together only cert ain precisely positioned cis elements with the same helical phase. Int erposing a DNA segment that both bends and twists easily to create a u niversal joint would provide an even more general mechanism to promote the association of separated sites regardless of position. A cis elem ent of the human c-myc gene, known to be melted in vivo, and its assoc iated single-strand DNA binding protein were examined and found to com prise just such a protein-DNA hinge.