The composition and structure of the outer kinetochore KMN complex is conserved across Kingdoms

ABSTRACT: In eukaryotes, chromosome segregation during cell division requires attachment to the spindle, which is ensured by a large multi-protein structure called the kinetochore. The outer layer of the kinetochore attaches to the microtubules and is named after three of its components KNL1C, MIS12C, and NDC80C (KMN). The KMN complex comprises ten proteins in humans and eleven in S. cerevisiae, whether it is fully conserved in more distant eukaryotes is unclear. Here, we aimed to define the KMN complex in the plant clade using co-immunoprecipitations in Arabidopsis cell cultures. We identified thirteen KMN proteins, including seven with previously known conserved functions (atMIS12, atNNF1, atNDC80, atSPC24, atSPC25, atNUF2, and atKNL1) and six that were uncharacterized. These six proteins show remote similarity to the four yeast/human KMN components whose homologs have not been characterized in plants so far. Accordingly, we named these proteins atDSN1, atCSM1, atNSL1A/B, and atZWINT1A/B. We showed that atDSN1, atCSM1, atNSL1A, and atZWINT1A localize to the kinetochore in planta and that atDSN1, atCSM1, and ZWINT1A/B are essential, further supporting their kinetochore function. AlphaFold2 predictions support an alike3D organization of the KMN complex in plants and mammals. We conclude that the KMN complex is globally conserved with an identical composition and similar organization in very distant eukaryotes, and was likely present in the common ancestors of all living eukaryotes.

INSTRUMENT(S):

ORGANISM(S): Arabidopsis Thaliana (mouse-ear Cress)

TISSUE(S): Plant Cell, Cell Suspension Culture

SUBMITTER: Dominique Eeckhout  

LAB HEAD: Geert De Jaeger

PROVIDER: PXD062209 | Pride | 2025-11-17

REPOSITORIES: Pride