Regulation of outer kinetochore Ndc80 complex-based microtubule attachments by the central kinetochore Mis12/MIND complex

Abstract

Multiple protein subcomplexes of the kinetochore cooperate as a cohesive molecular unit that forms load-bearing microtubule attachments that drive mitotic chromosome movements. There is intriguing evidence suggesting that central kinetochore components influence kinetochore-microtubule attachment, but the mechanism remains unclear. Here, we find that the conserved Mis12/MIND (Mtw1, Nsl1, Nnf1, Dsn1) and Ndc80 (Ndc80, Nuf2, Spc24, Spc25) complexes are connected by an extensive network of contacts, each essential for viability in cells, and collectively able to withstand substantial tensile load. Using a single-molecule approach, we demonstrate that an individual MIND complex enhances the microtubulebinding affinity of a single Ndc80 complex by fourfold. MIND itself does not bind microtubules. Instead, MIND binds Ndc80 complex far from the microtubule-binding domain and confers increased microtubule interaction of the complex. In addition, MIND activation is redundant with the effects of a mutation in Ndc80 that might alter its ability to adopt a folded conformation. Together, our results suggest a previously unidentified mechanism for regulating microtubule binding of an outer kinetochore component by a central kinetochore complex.

Hec1 Tail Phosphorylation Differentially Regulates Mammalian Kinetochore Coupling to Polymerizing and Depolymerizing Microtubules

“…Direction-specific regulation could in principle arise from differences in microtubule plus-end tip structure, but this structure so far appears not to differ between sisters [29]. Alternatively, Hec1 structure may vary when bound to polymerizing versus depolymerizing microtubules [30,31], or proteins other than Hec1 may bear load and govern chromosome velocity during depolymerization [32,33]. To uncover the molecular basis for Hec1 tail phosphorylation’s direction-dependent role, it will be essential to determine whether such phosphorylation regulates friction directly (by changing the tail’s microtubule affinity) or indirectly (by changing how its other domains, or other proteins, interact with microtubules), and whether and how it affects k-fiber microtubule dynamics.…”

The kinetochore module Okp1 CENP‐Q /Ame1 CENP‐U is a reader for N‐terminal modifications on the centromeric histone Cse4 CENP‐A

“…Here, several copies of the Ndc80 complex (Wigge & Kilmartin, 2001), which is a dumbbell-shaped structure, interact with the Dam1 ring (Nogales & Ramey, 2009). At its centromere-proximal side, the Ndc80 complex contacts the MIND complex (Kudalkar et al, 2015). At its centromere-proximal side, the Ndc80 complex contacts the MIND complex (Kudalkar et al, 2015).…”

“…The core kinetochore is a large multiprotein complex consisting its centromere-proximal side, the Ndc80 complex contacts the MIND complex (Kudalkar et al, 2015). On the chromatin-proximal side of the kinetochore, the Ctf19 complex is an important component of the inner kinetochore that interacts with centromeric chromatin and serves as an assembly platform for the outer kinetochore (Foltz et al, 2006;Izuta et al, 2006;Okada et al, 2006).…”

Anaphase A: Disassembling Microtubules Move Chromosomes toward Spindle Poles

“…The earliest laser trap assays of this kind used tip-couplers made from recombinant Dam1c or Ndc80c alone, which tracked against one or two piconewtons [119,150]. Coupling performance improved with the incorporation of additional microtubule-binding kinetochore elements [153,154], with the use of native kinetochore particles isolated from yeast [58], and with the use of flexible tethers for linking sub-complexes to beads [155]. Further improvements seem likely, especially as continued advancements in kinetochore biochemistry enable reconstitutions of ever more complete and stable kinetochore assemblies [156,157,158].…”