Abstract
During chromatin-regulated processes, the histone H2A-H2B heterodimer functions dynamically in and out of the nucleosome. Although detailed crystal structures of nucleosomes have been established, that of the isolated full-length H2A-H2B heterodimer has remained elusive. Here, we have determined the solution structure of human H2A-H2B by NMR coupled with CS-Rosetta. H2A and H2B each contain a histone fold, comprising four α-helices and two β-strands (α1–β1–α2–β2–α3–αC), together with the long disordered N- and C-terminal H2A tails and the long N-terminal H2B tail. The N-terminal αN helix, C-terminal β3 strand, and 310 helix of H2A observed in the H2A-H2B nucleosome structure are disordered in isolated H2A-H2B. In addition, the H2A α1 and H2B αC helices are not well fixed in the heterodimer, and the H2A and H2B tails are not completely random coils. Comparison of hydrogen-deuterium exchange, fast hydrogen exchange, and {1H}-15N hetero-nuclear NOE data with the CS-Rosetta structure indicates that there is some conformation in the H2A 310 helical and H2B Lys11 regions, while the repression domain of H2B (residues 27–34) exhibits an extended string-like structure. This first structure of the isolated H2A-H2B heterodimer provides insight into its dynamic functions in chromatin.
Highlights
Graduate School of Medical Life Science,Yokohama City University, 1-7-29 Suehiro-cho,Tsurumi-ku,Yokohama 2300045, Japan
The calculated structures of H2A-H2B indicate that the positions of the H2A α 1 and H2B α C helices are not well fixed as compared with other helices, suggesting that these two helices dynamically fluctuate in solution
We examined the secondary structures of the isolated H2A-H2B heterodimer by TROSY-NMR (Fig. 1)
Summary
Graduate School of Medical Life Science,Yokohama City University, 1-7-29 Suehiro-cho,Tsurumi-ku,Yokohama 2300045, Japan. The calculated structures of H2A-H2B indicate that the positions of the H2A α 1 and H2B α C helices are not well fixed as compared with other helices, suggesting that these two helices dynamically fluctuate in solution. To reveal the dynamics of H2A-H2B, we performed hydrogen-deuterium (H/D) exchange[25], fast hydrogen exchange[26] and {1H}-15N hetero-nuclear NOE27 experiments on H2A-H2B. Comparison of these data with the calculated structures suggests that the long disordered tails of H2A-H2B form some dynamic conformations
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call