Kinetochore protein Cnn1 promotes sister chromatid bi-orientation by modulating intraKMN affinities in a biphasic, phospho-regulated manner.. Saccharomyces cerevisiae

Kinetochores are large proteinaceous structures that assemble on centromeres to align sister chromatids to the mitotic spindle and orchestrate their segregation to the daughter cells. At the core of kinetochores lies a network of proteins known as KMN, whose microtubule-binding activity is regulated by the Ipl1/Aurora B and Mps1 kinases. Here, we have characterized a novel structural yeast kinetochore protein named Cnn1 and show that it regulates KMN-spindle activity by modulating the affinity between the KMN subcomplexes at their basis. Cnn1 supports KMN from S phase to anaphase, and is controlled by the Cdc28, Mps1 and Ipl1 kinases. Cnn1 has evolved to associate the KMN complexes into a coherent network activity to ensure efficient Overall design: S.cerevisiae oligonucleotide microarrays were provided by Affymetrix (S.cerevisiae Tiling 1.0R, P/N 900645). ChIP-chip analyses were carried out as described (Bermejo et al., Cell, 2009).