High-resolution footprinting of sequence-specific protein-DNA contacts

Gene transcription is regulated by proteins that bind specific DNA sequences and control the initiation of RNA synthesis. A major challenge is to map all of the regulatory sites in the genome and to identify the proteins that bind them. Because members of transcription factor families often exhibit similar sequence preferences, methods for determining intermolecular contacts in protein-DNA interfaces must be sensitive to even subtle structural differences. The most detailed structural views of protein-DNA interfaces have been obtained through X-ray crystallography and NMR spectroscopy, and these methods have revolutionized the understanding of the structural determinants of sequence-specific recognition(1). Neither crystallography nor NMR, however, is particularly well-suited to high-throughput applications such as pan-genomic elucidation of regulatory sequences; in addition, these methods yield no information on the energetic contribution of particular contacts. Here we report a straightforward, high-resolution biochemical method for mapping, at single-nucleotide resolution, DNA bases that are subject to sequence-specific contacts by regulatory proteins.