Functional framework of the kinetochore and spindle assembly checkpoint in Arabidopsis thaliana

The kinetochore, critical for accurate chromosome segregation and genome stability in eukaryotes, comprises the Constitutive Centromere Associated Network (CCAN) and the KMN network. In animals, the CCAN associates with centromeric nucleosomes throughout the cell cycle, while the KMN network assembles at kinetochores during M phase, binding spindle microtubules and serving as a platform for the spindle assembly checkpoint (SAC) complex. Despite conserved functions, kinetochore components vary across organisms. This study investigates the subcellular localization and interaction maps of core kinetochore components in Arabidopsis thaliana, finding that only CENP-C of the four conserved CCAN components localizes to kinetochores, while all KMN components consistently localize to the kinetochore throughout the cell cycle. Immunoprecipitation assays revealed interactions between core kinetochore proteins and regulators involved in DNA replication, histone modification, and chromatin remodeling, suggesting that the kinetochore may also function outside of M phase. Examining interactions between kinetochore and SAC components elucidates plant-specific SAC localization mechanisms providing a functional framework for understanding plant kinetochores and offering new insights into SAC regulation in plants.