Structural Transitions of Centromeric Chromatin Regulate the Cell Cycle-dependent Recruitment of CENP-N

Junnan Fang1,2, Yuting Liu1,2, Yun Wei1, Wenqiang Deng1,2, Zhouliang Yu1,2, Li Huang1, Yan Teng1, Ting Yao1, Qinglong You1,2, Haihe Ruan1, Ping Chen1, Rui-Ming Xu1, Guohong Li1,3*

1 National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
2 University of Chinese Academy of Sciences, Beijing 100049, China
3 Collaborative Innovation Center of Genetics and Development, China

Abstract

        Specific recognition of centromere-specific histone variant CENP-A-containing chromatin by CENP-N is an essential process in the assembly of the kinetochore complex at centromeres prior to mammalian cell division. However, the mechanisms of CENP-N recruitment to centromeres/kinetochores remain unknown. Here, we show that a CENP-A-specific RG loop (Arg80/Gly81) plays an essential and dual regulatory role in this process. The RG loop assists the formation of a compact “Ladder-like” structure of CENP-A chromatin, concealing the loop and thus impairing its role in recruiting CENP-N. Upon G1/S phase transition, however, centromeric chromatin switches from the compact to an open state, enabling the now exposed RG loop to recruit CENP-N prior to cell division. Our results provide the first insights into the mechanisms by which the recruitment of CENP-N is regulated by the structural transitions between compaction and relaxation of centromeric chromatin during the cell cycle.

Highlights

• CENP-N recognizes the RG loop of CENP-A nucleosome
• RG loop of CENP-A is involved in formation of a “Ladder-like” chromatin structure
• “Ladder-like” conformation of CENP-A chromatin impairs the binding of CENP-N
• Structural transitions of centromeric chromatin regulate the recruitment of CENP-N

• Graphical Abstract