The histone proteins within the nucleosome core particle (NCP) contain N-terminal �tail� domains. Their structures and molecular interactions with DNA have not been well defined due to their flexibility and transient nature of the interactions. The interactions between N-terminal tails and the proximal DNA are largely responsible for the assembly of chromatin fibers. In addition, recent studies reveal that the interaction between lysine residues of the histone tails and DNA abasic lesions greatly affects the reactivity of these lesions. A further understanding of the transient contacts between histone tails and nucleosomal DNA awaits a detection method clarifying these interactions. We developed a probe to detect these interactions by generating DNA-protein cross-links (DPCs). Precursor 1  is introduced at defined sites within NCPs. The oxidation of 1  rapidly generates a methide-type intermediate 2  that reacts readily with nucleophilic amino acid residues in proximity. When 1 is incorporated at positions 89 and 205 within the NCP, the cross-linked proteins are consistent with those detected in a previous report on an abasic lesion's reactivity in NCP. Mutation studies reveal that multiple amino acid residues are involved in the DPC. In addition, the fast reaction enables us to investigate the kinetics of the DPC formation. This probe is potentially useful for studying other DNA-protein interactions.

Probing for the interactions between nucleosomal DNA and N-terminal histone tails within a nucleosome core particle

247th National Meeting (2014)

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