4GEQ: Crystal structure of the Spc24-Spc25/Cnn1 binding interface

The Ndc80 complex is the key microtubule-binding element of the kinetochore. In contrast to the well-characterized interaction of Ndc80-Nuf2 heads with microtubules, little is known about how the Spc24-25 heterodimer connects to centromeric chromatin. Here, we present molecular details of Spc24-25 in complex with the histone-fold protein Cnn1/CENP-T illustrating how this connection ultimately links microtubules to chromosomes. The conserved Ndc80 receptor motif of Cnn1 is bound as an alpha helix in a hydrophobic cleft at the interface between Spc24 and Spc25. Point mutations that disrupt the Ndc80-Cnn1 interaction also abrogate binding to the Mtw1 complex and are lethal in yeast. We identify a Cnn1-related motif in the Dsn1 subunit of the Mtw1 complex, necessary for Ndc80 binding and essential for yeast growth. Replacing this region with the Cnn1 peptide restores viability demonstrating functionality of the Ndc80-binding module in different molecular contexts. Finally, phosphorylation of the Cnn1 N-terminus coordinates the binding of the two competing Ndc80 interaction partners. Together, our data provide structural insights into the modular binding mechanism of the Ndc80 complex to its centromere recruiters.
PDB ID: 4GEQDownload
MMDB ID: 107176
PDB Deposition Date: 2012/8/2
Updated in MMDB: 2015/07
Experimental Method:
x-ray diffraction
Resolution: 2.01  Å
Source Organism:
Saccharomyces cerevisiae S288C
Similar Structures:
Biological Unit for 4GEQ: trimeric; determined by author and by software (PISA)
Molecular Components in 4GEQ
Label Count Molecule
Proteins (3 molecules)
Kinetochore Protein Spc25(Gene symbol: SPC25)
Molecule annotation
Kinetochore Protein Spc24(Gene symbol: SPC24)
Molecule annotation
Kinetochore-associated Protein Cnn1(Gene symbol: CNN1)
Molecule annotation
Chemical (1 molecule)
* Click molecule labels to explore molecular sequence information.

Citing MMDB