Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Conserved Tetramer Junction in the Kinetochore Ndc80 Complex.

ABSTRACT: The heterotetrameric Ndc80 complex establishes connectivity along the principal longitudinal axis of a kinetochore. Its two heterodimeric subcomplexes, each with a globular end and a coiled-coil shaft, connect end-to-end to create a ?600 Å long rod spanning the gap from centromere-proximal structures to spindle microtubules. Neither subcomplex has a known function on its own, but the heterotetrameric organization and the characteristics of the junction are conserved from yeast to man. We have determined crystal structures of two shortened ("dwarf") Ndc80 complexes that contain the full tetramer junction and both globular ends. The junction connects two ?-helical coiled coils through regions of four-chain and three-chain overlap. The complexity of its structure depends on interactions among conserved amino-acid residues, suggesting a binding site for additional cellular factor(s) not yet identified.

SUBMITTER: Valverde R

PROVIDER: S-EPMC5131873 | biostudies-literature | 2016 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Conserved Tetramer Junction in the Kinetochore Ndc80 Complex.

Valverde Roberto R Ingram Jessica J Harrison Stephen C SC

Cell reports 20161101 8

The heterotetrameric Ndc80 complex establishes connectivity along the principal longitudinal axis of a kinetochore. Its two heterodimeric subcomplexes, each with a globular end and a coiled-coil shaft, connect end-to-end to create a ∼600 Å long rod spanning the gap from centromere-proximal structures to spindle microtubules. Neither subcomplex has a known function on its own, but the heterotetrameric organization and the characteristics of the junction are conserved from yeast to man. We have de ...[more]

PMID: 27851957

Similar Datasets

Multimodal microtubule binding by the Ndc80 kinetochore complex.

Project description:The Ndc80 complex is a key site of kinetochore-microtubule attachment during cell division. The human complex engages microtubules with a globular 'head' formed by tandem calponin-homology domains and an 80-amino-acid unstructured 'tail' that contains sites of phosphoregulation by the Aurora B kinase. Using biochemical, cell biological and electron microscopy analyses, we dissected the roles of the tail in binding of microtubules and mediation of cooperative interactions between Ndc80 complexes. Two segments of the tail that contain Aurora B phosphorylation sites become ordered at interfaces; one with tubulin and the second with an adjacent Ndc80 head on the microtubule surface, forming interactions that are disrupted by phosphorylation. We propose a model in which Ndc80's interaction with either growing or shrinking microtubule ends can be tuned by the phosphorylation state of its tail.

| S-EPMC3492541 | biostudies-literature

The Ndc80 kinetochore complex directly modulates microtubule dynamics.

Project description:The conserved Ndc80 complex is an essential microtubule-binding component of the kinetochore. Recent findings suggest that the Ndc80 complex influences microtubule dynamics at kinetochores in vivo. However, it was unclear if the Ndc80 complex mediates these effects directly, or by affecting other factors localized at the kinetochore. Using a reconstituted system in vitro, we show that the human Ndc80 complex directly stabilizes the tips of disassembling microtubules and promotes rescue (the transition from microtubule shortening to growth). In vivo, an N-terminal domain in the Ndc80 complex is phosphorylated by the Aurora B kinase. Mutations that mimic phosphorylation of the Ndc80 complex prevent stable kinetochore-microtubule attachment, and mutations that block phosphorylation damp kinetochore oscillations. We find that the Ndc80 complex with Aurora B phosphomimetic mutations is defective at promoting microtubule rescue, even when robustly coupled to disassembling microtubule tips. This impaired ability to affect dynamics is not simply because of weakened microtubule binding, as an N-terminally truncated complex with similar binding affinity is able to promote rescue. Taken together, these results suggest that in addition to regulating attachment stability, Aurora B controls microtubule dynamics through phosphorylation of the Ndc80 complex.

| S-EPMC3479545 | biostudies-literature

The highly conserved Ndc80 complex is required for kinetochore assembly, chromosome congression, and spindle checkpoint activity.

Project description:We show that the Xenopus homologs of Ndc80/Tid3/HEC1 (xNdc80) and Nuf2/MPP1/Him-10 (xNuf2) proteins physically interact in a 190-kD complex that associates with the outer kinetochore from prometaphase through anaphase. Injecting function-blocking antibodies to either xNdc80 or xNuf2 into XTC cells caused premature exit from mitosis without detectable chromosome congression or anaphase movements. Injected cells did not arrest in response to microtubule drugs, showing that the complex is required for the spindle checkpoint. Kinetochores assembled in Xenopus extracts after immunodepletion of the complex did not contain xRod, xZw10, xP150 glued (Dynactin), xMad1, xMad2, xBub1, and xBub3, demonstrating that the xNdc80 complex is required for functional kinetochore assembly. In contrast, function-blocking antibodies did not affect the localization of other kinetochore proteins when added to extracts containing previously assembled kinetochores. These extracts with intact kinetochores were deficient in checkpoint signaling, suggesting that the Ndc80 complex participates in the spindle checkpoint. We also demonstrate that the spindle checkpoint can arrest budding yeast cells lacking Ndc80 or Nuf2, whereas yeast lacking both proteins fail to arrest in mitosis. Systematic deletion of yeast kinetochore genes suggests that the Ndc80 complex has a unique role in spindle checkpoint signaling. We propose that the Ndc80 complex has conserved roles in kinetochore assembly, chromosome congression, and spindle checkpoint signaling.

| S-EPMC195965 | biostudies-literature

The Ndc80 kinetochore complex forms oligomeric arrays along microtubules.

Project description:The Ndc80 complex is a key site of regulated kinetochore-microtubule attachment (a process required for cell division), but the molecular mechanism underlying its function remains unknown. Here we present a subnanometre-resolution cryo-electron microscopy reconstruction of the human Ndc80 complex bound to microtubules, sufficient for precise docking of crystal structures of the component proteins. We find that the Ndc80 complex binds the microtubule with a tubulin monomer repeat, recognizing ?- and ?-tubulin at both intra- and inter-tubulin dimer interfaces in a manner that is sensitive to tubulin conformation. Furthermore, Ndc80 complexes self-associate along protofilaments through interactions mediated by the amino-terminal tail of the NDC80 protein, which is the site of phospho-regulation by Aurora B kinase. The complex's mode of interaction with the microtubule and its oligomerization suggest a mechanism by which Aurora B could regulate the stability of load-bearing kinetochore-microtubule attachments.

| S-EPMC2957311 | biostudies-literature

Architecture and flexibility of the yeast Ndc80 kinetochore complex.

Project description:Kinetochores mediate microtubule-chromosome attachment and ensure accurate segregation of sister chromatids. The highly conserved Ndc80 kinetochore complex makes direct contacts with the microtubule and is essential for spindle checkpoint signaling. It contains a long coiled-coil region with globular domains at each end involved in kinetochore localization and microtubule binding, respectively. We have directly visualized the architecture of the yeast Ndc80 complex and found a dramatic kink within the 560-A coiled-coil rod located about 160 A from the larger globular head. Comparison of our electron microscopy images to the structure of the human Ndc80 complex allowed us to position the kink proximal to the microtubule-binding end and to define the conformational range of the complex. The position of the kink coincides with a coiled-coil breaking region conserved across eukaryotes. We hypothesize that the kink in Ndc80 is essential for correct kinetochore geometry and could be part of a tension-sensing mechanism at the kinetochore.

| S-EPMC2640231 | biostudies-literature

Structural mechanism of outer kinetochore Dam1-Ndc80 complex assembly on microtubules.

Project description:Kinetochores couple chromosomes to the mitotic spindle to segregate the genome during cell division. An error correction mechanism drives the turnover of kinetochore-microtubule attachments until biorientation is achieved. The structural basis for how kinetochore-mediated chromosome segregation is accomplished and regulated remains an outstanding question. In this work, we describe the cryo-electron microscopy structure of the budding yeast outer kinetochore Ndc80 and Dam1 ring complexes assembled onto microtubules. Complex assembly occurs through multiple interfaces, and a staple within Dam1 aids ring assembly. Perturbation of key interfaces suppresses yeast viability. Force-rupture assays indicated that this is a consequence of impaired kinetochore-microtubule attachment. The presence of error correction phosphorylation sites at Ndc80-Dam1 ring complex interfaces and the Dam1 staple explains how kinetochore-microtubule attachments are destabilized and reset.

| S-EPMC7615550 | biostudies-literature

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

Project description: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 microtubule-binding 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.

| S-EPMC4611631 | biostudies-other

Stable kinetochore-microtubule attachment requires loop-dependent Ndc80-Ndc80 binding.

Project description:During cell division, kinetochores link chromosomes to spindle microtubules. The Ndc80 complex, a crucial microtubule binder, populates each kinetochore with dozens of copies. Whether adjacent Ndc80 complexes cooperate to promote microtubule binding remains unclear. Here we demonstrate that the Ndc80 loop, a short sequence that interrupts the Ndc80 coiled-coil at a conserved position, folds into a more rigid structure than previously assumed and promotes direct interactions between full-length Ndc80 complexes on microtubules. Mutations in the loop impair these Ndc80-Ndc80 interactions, prevent the formation of force-resistant kinetochore-microtubule attachments, and cause cells to arrest in mitosis for hours. This arrest is not due to an inability to recruit the kinetochore-microtubule stabilizing SKA complex and cannot be overridden by mutations in the Ndc80 tail that strengthen microtubule attachment. Thus, loop-mediated organization of adjacent Ndc80 complexes is crucial for stable end-on kinetochore-microtubule attachment and spindle assembly checkpoint satisfaction.

| S-EPMC10308368 | biostudies-literature

Astrin-SKAP complex reconstitution reveals its kinetochore interaction with microtubule-bound Ndc80.

Project description:Chromosome segregation requires robust interactions between the macromolecular kinetochore structure and dynamic microtubule polymers. A key outstanding question is how kinetochore-microtubule attachments are modulated to ensure that bi-oriented attachments are selectively stabilized and maintained. The Astrin-SKAP complex localizes preferentially to properly bi-oriented sister kinetochores, representing the final outer kinetochore component recruited prior to anaphase onset. Here, we reconstitute the 4-subunit Astrin-SKAP complex, including a novel MYCBP subunit. Our work demonstrates that the Astrin-SKAP complex contains separable kinetochore localization and microtubule binding domains. In addition, through cross-linking analysis in human cells and biochemical reconstitution, we show that the Astrin-SKAP complex binds synergistically to microtubules with the Ndc80 complex to form an integrated interface. We propose a model in which the Astrin-SKAP complex acts together with the Ndc80 complex to stabilize correctly formed kinetochore-microtubule interactions.

| S-EPMC5602300 | biostudies-literature

Sos7, an essential component of the conserved Schizosaccharomyces pombe Ndc80-MIND-Spc7 complex, identifies a new family of fungal kinetochore proteins.

Project description:Chromosome segregation is powered by the kinetochore, a large macromolecular structure assembled on centromeric chromatin. Attachment of sister chromatids to microtubules is mediated by the highly conserved tripartite KMN (acronym for KNL-1-Mis12-Ndc80) kinetochore network. In the fission yeast Schizosaccharomyces pombe, the equivalent complex is called NMS (Ndc80-MIND-Spc7). Here, we show that not all components of the NMS complex had been identified previously. A 10th NMS component exists, the essential Sos7 protein, which is a genetic and physical interaction partner of Spc7. The analysis of sos7 kinetochore-null mutant yeast strains demonstrated that Sos7 is central to NMS function. In particular, Sos7 is required for kinetochore targeting of Spc7 as well as components of the MIND complex. sos7 mutant strains show severe chromosome missegregation phenotypes and have compromised microtubule-kinetochore interactions. Sos7 is the founding member of a functionally conserved fungal kinetochore family not present in the point centromere carrying Saccharomycotina clusters, suggesting that the new Sos7 family might be a signature motif of fungi with regional centromeres.

| S-EPMC3434540 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data