The structure of the Ctf19c/CCAN from budding yeast

Area of Science:

• Cell Biology
• Molecular Biology
• Structural Biology

Background:

• Eukaryotic kinetochores are essential protein complexes that link spindle microtubules to chromosomal centromeres.
• The Ctf19 complex (Ctf19c) in yeast, and its homolog the constitutive centromere associated network (CCAN) in other organisms, forms the foundational layer of the kinetochore.
• Ctf19c/CCAN plays critical roles in kinetochore assembly timing, localization via Cse4/CENP-A nucleosomes, and organization of microtubule attachment machinery.

Purpose of the Study:

• To determine the high-resolution structure of the reconstituted 13-subunit Ctf19 complex.
• To understand how the Ctf19 complex interacts with the Cse4/CENP-A nucleosome.
• To elucidate the assembly hierarchy and regulatory implications of the Ctf19 complex.

Main Methods:

• Reconstitution of the 13-subunit Ctf19 complex.
• Cryo-electron microscopy (cryo-EM) for structural determination.
• Analysis of subunit interactions and nucleosome association.

Main Results:

• Determined the structure of the 13-subunit Ctf19 complex at approximately 4 Å resolution.
• The structure provides insights into known and inferred contacts with the Cse4/CENP-A nucleosome.
• The structure explains the observed assembly hierarchy of the Ctf19 complex.

Conclusions:

• The determined structure of Ctf19c provides a molecular basis for its foundational role in kinetochore assembly.
• Understanding Ctf19c structure illuminates its association with Cse4/CENP-A and its role in organizing microtubule attachments.
• This work has implications for understanding kinetochore establishment and cell cycle regulation by kinases.