Fig. 7.

Overproduced CenH3 particles occupy canonical nucleosome positions and protect ∼135 bp. Size distributions (A) of mapped fragments for FLAG-H2A (magenta) and Cse4-Myc (green) ChIPs, including a FLAG-Cse4 size distribution from a control (blue). See also Fig. S8A. (B) V-plots show nucleosomal fragments from the 20 most highly expressed genes aligned at their 5′ ORF ends. Black lines indicate median fragment sizes. (C) Overproduced Cse4-Myc and H2A over the SNT1-FEN1 region showing enrichment of Cse4/H2A (Top), an aligned hot nucleosome map reproduced from Dion et al. (31) (Middle), and enrichment of Cse4 and H2A (Bottom). (D) Scatterplot of ChIP signals versus turnover rates for Cse4/H2A. (E) Model in which CenH3 hemisomes are stably held in place by Cbf1 and CBF3, whereas unstable CenH3 octamers are rapidly evicted from chromosome arms and targeted for degradation.