Structure and function of the yeast kinetochore and microtubule dynamics

@article{pmid22908300,

title = {The Ndc80 kinetochore complex directly modulates microtubule dynamics},

author = {Umbreit, Neil T. and Gestaut, Daniel R. and Tien, Jerry F. and Vollmar, Breanna S. and Gonen, Tamir and Asbury, Charles L. and Davis, Trisha N. },

url = {https://cryoem.ucla.edu/wp-content/uploads/2012_umbreit.pdf, Main text},

doi = {10.1073/pnas.1209615109},

year  = {2012},

date = {2012-10-02},

journal = {Proc. Natl. Acad. Sci. U.S.A.},

volume = {109},

number = {40},

pages = {16113--16118},

abstract = {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.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid22885327,

title = {The structure of purified kinetochores reveals multiple microtubule-attachment sites},

author = {Shane Gonen and Bungo Akiyoshi and Matthew G Iadanza and Dan Shi and Nicole Duggan and Sue Biggins and Tamir Gonen},

url = {https://cryoem.ucla.edu/wp-content/uploads/2012_gonen.pdf, Main text},

doi = {10.1038/nsmb.2358},

year  = {2012},

date = {2012-08-12},

journal = {Nat. Struct. Mol. Biol.},

volume = {19},

number = {9},

pages = {925--929},

abstract = {Chromosomes must be accurately partitioned to daughter cells to prevent aneuploidy, a hallmark of many tumors and birth defects. Kinetochores are the macromolecular machines that segregate chromosomes by maintaining load-bearing attachments to the dynamic tips of microtubules. Here, we present the structure of isolated budding-yeast kinetochore particles, as visualized by EM and electron tomography of negatively stained preparations. The kinetochore appears as an ~126-nm particle containing a large central hub surrounded by multiple outer globular domains. In the presence of microtubules, some particles also have a ring that encircles the microtubule. Our data, showing that kinetochores bind to microtubules via multivalent attachments, lay the foundation to uncover the key mechanical and regulatory mechanisms by which kinetochores control chromosome segregation and cell division.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid21107429,

title = {Tension directly stabilizes reconstituted kinetochore-microtubule attachments},

author = {Akiyoshi, Bungo and Sarangapani, Krishna K. and Powers, Andrew F. and Nelson, Christian R. and Reichow, Steve L. and Arellano-Santoyo, Hugo and Gonen, Tamir and Ranish, Jeffrey A. and Asbury, Charles L. and Biggins, Sue},

url = {https://cryoem.ucla.edu/wp-content/uploads/2010_akiyoshi.pdf, Main text},

doi = {10.1038/nature09594},

year  = {2010},

date = {2010-11-24},

journal = {Nature},

volume = {468},

number = {7323},

pages = {576--579},

abstract = {Kinetochores are macromolecular machines that couple chromosomes to dynamic microtubule tips during cell division, thereby generating force to segregate the chromosomes. Accurate segregation depends on selective stabilization of correct 'bi-oriented' kinetochore-microtubule attachments, which come under tension as the result of opposing forces exerted by microtubules. Tension is thought to stabilize these bi-oriented attachments indirectly, by suppressing the destabilizing activity of a kinase, Aurora B. However, a complete mechanistic understanding of the role of tension requires reconstitution of kinetochore-microtubule attachments for biochemical and biophysical analyses in vitro. Here we show that native kinetochore particles retaining the majority of kinetochore proteins can be purified from budding yeast and used to reconstitute dynamic microtubule attachments. Individual kinetochore particles maintain load-bearing associations with assembling and disassembling ends of single microtubules for >30 min, providing a close match to the persistent coupling seen in vivo between budding yeast kinetochores and single microtubules. Moreover, tension increases the lifetimes of the reconstituted attachments directly, through a catch bond-like mechanism that does not require Aurora B. On the basis of these findings, we propose that tension selectively stabilizes proper kinetochore-microtubule attachments in vivo through a combination of direct mechanical stabilization and tension-dependent phosphoregulation.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid20479468,

title = {Cooperation of the Dam1 and Ndc80 kinetochore complexes enhances microtubule coupling and is regulated by aurora B},

author = {Jerry F Tien and Neil T Umbreit and Daniel R Gestaut and Andrew D Franck and Jeremy Cooper and Linda Wordeman and Tamir Gonen and Charles L Asbury and Trisha N Davis},

url = {https://cryoem.ucla.edu/wp-content/uploads/Tien_2010.pdf, Main text},

doi = {10.1083/jcb.200910142},

year  = {2010},

date = {2010-05-17},

journal = {J. Cell Biol.},

volume = {189},

number = {4},

pages = {713--723},

abstract = {The coupling of kinetochores to dynamic spindle microtubules is crucial for chromosome positioning and segregation, error correction, and cell cycle progression. How these fundamental attachments are made and persist under tensile forces from the spindle remain important questions. As microtubule-binding elements, the budding yeast Ndc80 and Dam1 kinetochore complexes are essential and not redundant, but their distinct contributions are unknown. In this study, we show that the Dam1 complex is a processivity factor for the Ndc80 complex, enhancing the ability of the Ndc80 complex to form load-bearing attachments to and track with dynamic microtubule tips in vitro. Moreover, the interaction between the Ndc80 and Dam1 complexes is abolished when the Dam1 complex is phosphorylated by the yeast aurora B kinase Ipl1. This provides evidence for a mechanism by which aurora B resets aberrant kinetochore-microtubule attachments. We propose that the action of the Dam1 complex as a processivity factor in kinetochore-microtubule attachment is regulated by conserved signals for error correction.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid17572669,

title = {Tension applied through the Dam1 complex promotes microtubule elongation providing a direct mechanism for length control in mitosis},

author = {Andrew D Franck and Andrew F Powers and Daniel R Gestaut and Tamir Gonen and Trisha N Davis and Charles L Asbury},

url = {https://cryoem.ucla.edu/wp-content/uploads/franck2007.pdf, Main text},

doi = {10.1038/ncb1609},

year  = {2007},

date = {2007-06-17},

journal = {Nat. Cell Biol.},

volume = {9},

number = {7},

pages = {832--837},

abstract = {In dividing cells, kinetochores couple chromosomes to the tips of growing and shortening microtubule fibres and tension at the kinetochore-microtubule interface promotes fibre elongation. Tension-dependent microtubule fibre elongation is thought to be essential for coordinating chromosome alignment and separation, but the mechanism underlying this effect is unknown. Using optical tweezers, we applied tension to a model of the kinetochore-microtubule interface composed of the yeast Dam1 complex bound to individual dynamic microtubule tips. Higher tension decreased the likelihood that growing tips would begin to shorten, slowed shortening, and increased the likelihood that shortening tips would resume growth. These effects are similar to the effects of tension on kinetochore-attached microtubule fibres in many cell types, suggesting that we have reconstituted a direct mechanism for microtubule-length control in mitosis.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}