Author(s): Ueda T, Chou H, Kawase T, Shirakawa H, Yoshida M
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Abstract HMGB1, a nonhistone chromosomal protein in higher eukaryotic nuclei, consists of two DNA binding motifs called HMG boxes and an acidic C-tail comprising a continuous array of 30 acidic amino acid residues. In the preceding study, we showed that the acidic C-tail of HMGB1 is required for transcription stimulation accompanied by chromatin decondensation in cultured cells. However, details of the involvement of the acidic C-tail in transcription stimulation were not clear. To clarify the mechanism of transcription stimulation by the acidic C-tail, we assessed the effect of the acidic C-tail on the transcription stimulation and nucleosome binding. Transcription stimulation assays using acidic C-tail deletion mutants showed that the five amino acid residues at the C-terminal end of HMGB1, a DDDDE sequence, are essential for the stimulation. The DDDDE sequence was also required for the preferential binding of HMGB1 to nucleosome linker DNA, which is a cognate HMGB1 binding site in chromatin. Cross-linking and far-Western experiments demonstrated that the DDDDE sequence interacts with the core histone H3 N-tail. These results strongly suggest that the interaction between the DDDDE sequence of HMGB1 and the H3 N-tail is a key factor for the transcription stimulation by HMGB1 as well as the preferential binding of HMGB1 to chromatin.
This article was published in Biochemistry
and referenced in Journal of Biomolecular Research & Therapeutics