Figure 6.

(A) Human chromosome showing the centromere in grey and the structure of the human centromeric alpha satellite DNA. The 171 bp monomers (green arrows) are AT-rich sequences that can contain either A box (red and black) or CENP-B box (orange and black). The monomers are tandemly repeated and form a higher order repeat, which in turn appears repeated along the centromere. (B) Schematic and cartoon structures of the dimeric i-motifs formed by truncated A box (PDB ID: 2MRZ) and CENP-B box (PDB ID: 1C11). Cytosines are represented in grey, thymines in green, adenines in magenta and guanines in blue. (C) Proposed model for nucleosome organization at the centromere. The i-motifs formed by C-rich sequences of A and CENP-B boxes (orange) would maintain the structural organization of the centromere.