Modular Assembly of RWD Domains on the Mis12 Complex Underlies Outer Kinetochore Organization

• DOI: 10.1016/j.molcel.2014.01.019
• Publication Date: 2014-02-13T17:00:22Z
• Authors: Arsen Petrovic; Shyamal Mosalaganti; Jenny Keller; Marta Mattiuzzo; Katharina Overlack; Veronica Krenn; Anna De Antoni; Sabine Wohlgemuth; Valentina Cecatiello; Sebastiano Pasqua...; Stefan Raunser; Andrea Musacchio
• Keywords: Models, Molecular; Protein Conformation; Centromere; Molecular Sequence Data; Mitosis; Crystallography, X-Ray; Microtubules; 03 medical and health sciences; Chromosome Segregation; Escherichia coli; Humans; Amino Acid Sequence; Kinetochores; Molecular Biology; 0303 health sciences; Sequence Homology, Amino Acid; Amino Acid Sequence; Centromere; Chromosome Segregation; Crystallography, X-Ray; Escherichia coli; HeLa Cells; Humans; Kinetochores; M Phase Cell Cycle Checkpoints; Microscopy, Electron; Microtubule-Associated Proteins; Microtubules; Mitosis; Models, Molecular; Molecular Sequence Data; Plasmids; Protein Conformation; Protein Structure, Tertiary; Sequence Homology, Amino Acid; Cell Biology; Protein Structure, Tertiary; Microscopy, Electron; M Phase Cell Cycle Checkpoints; Biologie; Microtubule-Associated Proteins; HeLa Cells; Plasmids

Faithful chromosome segregation is mandatory for cell and organismal viability. Kinetochores, large protein assemblies embedded in centromeric chromatin, establish a mechanical link between chromosomes and spindle microtubules. The KMN network, a conserved 10-subunit kinetochore complex, harbors the microtubule-binding interface. RWD domains in the KMN subunits Spc24 and Spc25 mediate kinetochore targeting of the microtubule-binding subunits by interacting with the Mis12 complex, a KMN subcomplex that tethers directly onto the underlying chromatin layer. Here, we show that Knl1, a KMN subunit involved in mitotic checkpoint signaling, also contains RWD domains that bind the Mis12 complex and that mediate kinetochore targeting of Knl1. By reporting the first 3D electron microscopy structure of the KMN network, we provide a comprehensive framework to interpret how interactions of RWD-containing proteins with the Mis12 complex shape KMN network topology. Our observations unveil a regular pattern in the construction of the outer kinetochore.