Cryo-EM structure of the complete inner kinetochore of the budding yeast point centromere

Sci Adv. 2023 Jul 28;9(30):eadg7480. doi: 10.1126/sciadv.adg7480. Epub 2023 Jul 28.

Abstract

The point centromere of budding yeast specifies assembly of the large kinetochore complex to mediate chromatid segregation. Kinetochores comprise the centromere-associated inner kinetochore (CCAN) complex and the microtubule-binding outer kinetochore KNL1-MIS12-NDC80 (KMN) network. The budding yeast inner kinetochore also contains the DNA binding centromere-binding factor 1 (CBF1) and CBF3 complexes. We determined the cryo-electron microscopy structure of the yeast inner kinetochore assembled onto the centromere-specific centromere protein A nucleosomes (CENP-ANuc). This revealed a central CENP-ANuc with extensively unwrapped DNA ends. These free DNA duplexes bind two CCAN protomers, one of which entraps DNA topologically, positioned on the centromere DNA element I (CDEI) motif by CBF1. The two CCAN protomers are linked through CBF3 forming an arch-like configuration. With a structural mechanism for how CENP-ANuc can also be linked to KMN involving only CENP-QU, we present a model for inner kinetochore assembly onto a point centromere and how it organizes the outer kinetochore for chromosome attachment to the mitotic spindle.

MeSH terms

  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / genetics
  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / metabolism
  • Centromere / metabolism
  • Centromere Protein A / genetics
  • Chromosomal Proteins, Non-Histone / metabolism
  • Cryoelectron Microscopy
  • DNA
  • Kinetochores / metabolism
  • Nuclear Proteins / metabolism
  • Protein Subunits / metabolism
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae Proteins* / metabolism
  • Saccharomycetales* / genetics

Substances

  • Centromere Protein A
  • Protein Subunits
  • Chromosomal Proteins, Non-Histone
  • DNA
  • NDC80 protein, S cerevisiae
  • Nuclear Proteins
  • Saccharomyces cerevisiae Proteins
  • CBF1 protein, S cerevisiae
  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors