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Hierarchical assembly of the budding yeast kinetochore from multiple subcomplexes
Peter De Wulf1, Andrew D McAinsh, Peter K Sorger
1Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Genes & Development
|November 25, 2003
Summary
Yeast kinetochores are large, multi-subunit structures essential for chromosome attachment to spindle microtubules. This study identifies new protein complexes that bridge DNA-binding and microtubule-binding proteins, revealing key assembly platforms.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Kinetochores are crucial protein complexes on centromeric DNA, mediating chromosome attachment to spindle microtubules.
- The Saccharomyces cerevisiae kinetochore comprises over 60 proteins, but assembly mechanisms and structural details remain largely unknown.
Purpose of the Study:
- To investigate protein-protein interactions and the structure of microtubule-attachment sites within the yeast kinetochore.
- To identify and characterize new kinetochore subunits and their roles in assembly.
Main Methods:
- Biophysical techniques
- Affinity purification
- Mass spectrometry
- In vivo assays
- Examination of 31 centromere-binding proteins
Main Results:
- Yeast kinetochores are large structures (>5 MD) composed of at least 17 discrete subcomplexes.
- Two novel complexes, COMA and MIND, function as essential bridges between DNA- and microtubule-binding kinetochore proteins.
- COMA, MIND, and the Ndc80 complex serve as independent platforms for outer kinetochore assembly.
Conclusions:
- Kinetochore assembly relies on bridging proteins connecting DNA- and microtubule-interacting subunits.
- The COMA and MIND complexes, along with Ndc80, are critical platforms for kinetochore assembly.
- These three complexes likely play distinct roles in force generation and microtubule attachment.