Site-Directed Cleavage of DNA by Linker Histone-Fe(II) EDTA Conjugates

The ordered and regular packaging of eukaryotic DNA within the chromatin complex allows the efficient utilization of this substrate for nuclear processes such as DNA replication, transcription, recombination, and repair (1,2). Thus, an understanding of the organization of protein-DNA interactions and associations within the chromatin complex is a prerequisite for a complete molecular description of these processes. For example, the linker histone protein plays crucial roles in the stability and organization of the chromatin fiber (3,4). This multidomain protein undoubtedly makes complicated and diverse but poorly understood interactions within the chromatin fiber (1). Currently, there is disagreement regarding the site of association of the globular domain of this protein within the nucleosome proper (5,6). Moreover, the molecular interactions and chemical activities of its N- and C-terminal tails are most likely modulated by the multiple posttranslational phosphorylation events known to occur within these domains (11,2). Thus, the linker histone tails represent critical points for signal transduction within the chromatin complex likely to be manifested as structural alterations within chromatin.