Fig. 6: Structural asymmetries of H2B N-tails and H2A C-tails confer a polarity to the chromatin fiber.
From: Structural basis for linker histone H5–nucleosome binding and chromatin fiber compaction
a Top: two different structural conformations of the H2B N-tails, i.e., H2B-Nextend (yellow) and H2B-Nhook (green), in the chromatosome are viewed from two angles. Down: the unidirectionally tandem arrangement of the H2B N-tails, except N1 and N3 as indicated by arrows, in the H5-chromatin fiber. All elements in the nucleosome are shown in grey except the two copies of H2B (red). b Top: two different structural conformations of H2A C-tails, i.e., H2A-Cextend (red) and H2A-Cbend (blue), in the chromatosome are viewed from two angles. Down: the unidirectionally tandem arrangement of the H2A C-tails, except N1 and N3 as indicated by arrows, in the H5-chromatin fiber. All elements in the nucleosome are shown in grey except the two copies of H2A (yellow). c Interplays between H2A-CTD and H5 in the chromatin fiber. Left: the relative positions of H2A C-tails and H5. The extended H2A C-tail in each nucleosome of the chromatin fiber points either to H5-CTD (N1) or to H5-GD (N10), depending on the positions of nucleosomes in the chromatin fiber. Right: the unidirectionally tandem arrangement of the asymmetric interactions between the H2A C-tails and the H5, except N1 and N3 as indicated by arrows, in the H5-chromatin fiber. The extended H2A C-terminal tails pointing toward H5-CTD are shown in cyan while those pointing toward H5-GD are shown in red.
