Etudes sur le mécanisme de remodelage des nucléosomes par ...

tel-00413908, version 1 - 7 Sep 2009
11 nm
Figure I.5. Structure of the 147 bp nucleosome core particle at 1.9 Å resolution. (a) View down
the axis of 2-fold pseudo-symmetry (dyad axis, black) with the DNA superhelix axis oriented
vertically (broken line). The dyad axis bisects the central base-pair. The 147 bp palindromic DNA
sequence shows nearly perfect 2-fold symmetry relating the two 73 bp halves of the DNA superhelix
extending from the central base-pair. The DNA strands are cyan and brown. The histone-fold domains
of the histone proteins are blue for H3, green for H4, yellow for H2A and red for H2B. The histonefold
extensions and N-terminal tail regions shown are white. (b) View down the DNA superhelix axis
showing one half of the structure to illustrate the organization of histone and DNA. Colors are as for
(a). The superhelix locations are labeled at the DNA-binding sites of the histone-fold pairs and the H3αN
helix (SHL: 0.5, 1.5, 2.5, 3.5, 4.5, 5.5, 6.5). The central base-pair is indicated (0). The histone-fold
substructure for histones H3 and H2B are labeled (α1, L1, α2, L2, α3) as are histone-fold extensions
(αN, αC) and segments of the N and C-terminal tails (N, C, N′, C′). Adapted from Davey et al., 2002.
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