CCAN Assembly Configures Composite Binding Interfaces to Promote Cross-Linking of Ndc80 Complexes at the Kinetochore

Gülsah Pekgöz Altunkaya, Francesca Malvezzi, Zuzana Demianova, Tomasz Zimniak, Gabriele Litos, Florian Weissmann, Karl Mechtler, Franz Herzog, Stefan Westermann

Publikation: Beitrag in FachzeitschriftArtikelBegutachtung

Abstract

Partitioning of the genome requires kinetochores, large protein complexes that mediate dynamic attachment of chromosomes to the spindle. Kinetochores contain two supramolecular protein assemblies. The ten-protein KMN network harbors key microtubule-binding sites in the Ndc80 complex and mediates assembly of checkpoint complexes via the KNL-1/Spc105 protein [1, 2]. As KMN does not contact DNA directly, it relies on different centromere-binding proteins for recruitment and cell-cycle-dependent assembly. These proteins are collectively referred to as the CCAN (constitutive centromere-associated network) [2–4]. The molecular mechanisms by which CCAN subunits associate, however, have remained incompletely defined. In particular, it is unclear how CCAN subunits facilitate the assembly of a microtubule-binding interface that contains multiple Ndc80 molecules bound to different receptors [5]. Here, we dissect molecular mechanisms that underlie targeting of the CCAN subunit Cnn1/CENP-T to the sequence-determined point centromeres of budding yeast. Systematic quantitative mass spectrometry experiments reveal association dependencies within the yeast CCAN network. We show that evolutionarily conserved residues in the histone-fold domain of Cnn1 are required for the formation of a stable five-subunit CCAN subassembly with the Ctf3 complex. Cnn1 localizes in a Ctf3-dependent manner to the core of the yeast point centromere, overlapping with the yeast CENP-A protein Cse4. By arranging the N-terminal domains of the CCAN subunits Mcm16, Mcm22, and Cnn1 into close proximity, the Ctf3c-Cnn1-Wip1 complex configures a composite interaction site for two molecules of the Ndc80 complex. Our experiments show how cooperative assembly mechanisms organize the microtubule-binding interface of the kinetochore.

OriginalspracheEnglisch
Seiten (von - bis)2370-2378
Seitenumfang9
FachzeitschriftCurrent Biology
Jahrgang26
Ausgabenummer17
DOIs
PublikationsstatusVeröffentlicht - 12 Sep. 2016
Extern publiziertJa

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