Figure 1
The CENP-A octamer and nucleosome structures display greater local flexibility than their canonical H3 counterparts.
(A) The CENP-A and H3 nucleosomes are nearly identical by crystal structure alignment. Colors label CENP-A and CENP-A’ (green), CENP-A loop 1 (purple) and a region spanning the H2A acidic patch (red). The pseudo-dyad is an axis of rotational symmetry that divides the nucleosomal DNA in two and bisects the central four-helix bundle. (B) Structural alignment of CENP-A and H3 proteins highlights the longer CENP-A loop 1 as a major difference. (C) Cα root mean square fluctuations (RMSF) of the first heterotypic half of the CENP-A and H3 structures display greater local flexibility in the CENP-A systems at several specific regions. (D) Cα RMSF of the second heterotypic half demonstrates specific asymmetries in local flexibility. Dashed lines separate protein segments. Differences in Cα RMSF greater than 0.6 Å are considered very significant. Structure figures rendered in Pymol.
