Figure 6
CENP-A nucleosomal DNA is relatively unstable near the pseudo-dyad compared to the corresponding H3 nucleosomal DNA.
(A) RMSF per basepair for the CENP-A and H3 nucleosomes demonstrates asymmetric entry/exit unwinding for both systems and further highlights significantly increased fluctuations for CENP-A basepairs +10 to +30 (inset). Two lines are shown for each system since the DNA is double-stranded and the shaded areas represent the RMSF ± one standard deviation. (B) His 59, unique to CENP-A, has electrostatic interactions with the entry terminal of DNA before it detaches. (C) Coinciding with the detachment of entry DNA, His59 turns towards DNA SHL +1 or +2, disrupting the local stability of DNA. (D) N85 in CENP-A, substituted for R83 in H3, has a weaker binding affinity to DNA and two other substitutions, F84 and R80, develop a hydrophobic hotspot with K79 of H4, further contributing to DNA instability near the pseudo-dyad. Basepairs 10–30 are highlighted in red, key residues are shown as sticks and CENP-A interactions not found in the H3 nucleosome are represented by dashed lines. Structure figures rendered in VMD.
