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

• DOI: 10.1126/sciadv.adg7480
• Publication Date: 2023-07-28T17:58:35Z
• Authors: Tom Dendooven; Ziguo Zhang; Jing Yang; Stephen H. McLaug...; Johannes Schwab; Sjors H. W. Scheres; Stanislau Yatskevich; David Barford
• Keywords: 0301 basic medicine; Saccharomyces cerevisiae Proteins; Chromosomal Proteins, Non-Histone; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; Cryoelectron Microscopy; Centromere; Nuclear Proteins; Saccharomyces cerevisiae; DNA; Protein Subunits; 03 medical and health sciences; Saccharomycetales; Biomedicine and Life Sciences; Kinetochores; Centromere Protein A

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-A Nuc ). This revealed a central CENP-A Nuc 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-A Nuc 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.