CCAN makes multiple contacts with centromeric DNA to provide distinct pathways to the outer kinetochore

Area of Science:

• Cell Biology
• Molecular Biology
• Genetics

Background:

• Kinetochore assembly requires specialized nucleosomes with CENP-A at centromeres.
• CENP-A alone is insufficient for complete kinetochore formation, and centromeric chromatin establishment mechanisms remain unclear.

Purpose of the Study:

• To identify novel proteins involved in centromeric chromatin establishment.
• To elucidate the role of CENP-W in the constitutive centromere-associated network (CCAN) and kinetochore assembly.

Main Methods:

• Protein complex identification and characterization.
• Biochemical assays to determine DNA and histone binding properties.
• Analysis of protein function in centromere and kinetochore assembly pathways.

Main Results:

• CENP-W is identified as a DNA-binding component of the CCAN, forming a complex with CENP-T.
• The CENP-T/CENP-W complex binds nucleosomal DNA and canonical histone H3, but not CENP-A.
• CENP-T/CENP-W acts upstream of most CCAN components, with CENP-C, suggesting distinct roles in connecting centromeres to kinetochores.

Conclusions:

• The CENP-T/CENP-W complex is crucial for establishing centromeric chromatin structure.
• This complex works coordinately with CENP-A to facilitate kinetochore assembly.
• Distinct pathways involving CENP-T/CENP-W and CENP-C are essential for linking centromeric chromatin to outer kinetochore structures.