Site-Directed Chemical Probing of Histone-DNA Interactions

The protein-DNA complexes that make up the chromosome serve not only to package the genomic DNA within the confines of the nucleus but to directly participate in the efficient and controlled utilization of the DNA for nuclear processes such as replication, transcription, recombination, and DNA repair (1 ). Understanding these complex functions will require a molecular description of the multitude of protein-DNA interactions and associations within the chromatin complex. For example, the core histone tail domains make multiple and complex interactions that vary as a function of the condensation state of the chromatin fiber (2 ). Moreover, the molecular interactions of these flexible domains are undoubtedly modulated by the multiple posttranslational modifications known to occur within these residues (3 ). Thus, the histone tails represent critical points for signal transduction within the chromatin complex, and these signals are likely to be manifested as subtle structural alterations within the chromatin complex.