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| Title | Cnp1 N-terminal dynamics regulate L1 loop recognition by Mis15 to orchestrate kinetochore assembly in Schizosaccharomyces pombe. |
|---|---|
| Journal, issue, pages | J Mol Cell Biol, Year 2025 |
| Publish date | Dec 26, 2025 |
Authors | Yujie Xiong / Yanze Jian / Yongliang Zhang / Min Zhang / Xuan Zhang / Kaiming Zhang / Chuanhai Fu / Tian Tian / Jianye Zang / ![]() |
| PubMed Abstract | Centromeres are defined by the histone H3 variant CENP-A, which serve as the foundation for kinetochore assembly and ensure faithful chromosome segregation. CENP-A nucleosomes possess distinctive ...Centromeres are defined by the histone H3 variant CENP-A, which serve as the foundation for kinetochore assembly and ensure faithful chromosome segregation. CENP-A nucleosomes possess distinctive dynamic features, including flexible DNA ends at the entry/exit sites and a mobile N-terminal region, which are properties proposed to facilitate kinetochore assembly, yet the underlying molecular mechanisms remain elusive. Here, we present cryo-electron microscopy structures of Cnp1, the Schizosaccharomyces pombe (S. pombe) ortholog of CENP-A, alone and in complex with Mis15, the fission yeast ortholog of CENP-N. By integrating structural, biochemical, and molecular dynamics analyses, we demonstrate that the N-terminal region of Cnp1 regulates both DNA-end breathing and the conformational mobility of the L1 loop, a critical structural element for Mis15 recognition. Either enhanced dynamics caused by N-terminal deletion or reduced dynamics from targeted residue substitution disrupt Mis15 binding in vitro and impair its centromeric localization in vivo, thereby compromising the earliest steps of constitutive centromere-associated network assembly. Our findings establish the Cnp1 N-terminus as a dynamic allosteric modulator of chromatin architecture and reveal an L1 loop modulation mechanism that links nucleosome flexibility to kinetochore specification and chromosome segregation fidelity in fission yeast. |
External links | J Mol Cell Biol / PubMed:41453208 |
| Methods | EM (single particle) |
| Resolution | 2.99 - 3.83 Å |
| Structure data | EMDB-63344, PDB-9lrv: EMDB-63345, PDB-9lrw: ![]() EMDB-63346: cryo-EM structure of Mis151-249-Cnp1 nucleosome complex |
| Source |
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Keywords | NUCLEAR PROTEIN/DNA / Nucleosome dynamics / CENP-A / Cnp1 / kinetochore assembly / Chromosome Segregation / NUCLEAR PROTEIN-DNA complex |
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