The budding yeast point centromere associates with two Cse4 molecules during mitosis

Area of Science:

• Cell Biology
• Molecular Biology
• Genetics

Background:

• The centromere, essential for chromosome segregation, is characterized by the histone variant centromere protein A (CENP-A).
• The in vivo structure of CENP-A chromatin (hemisomes, canonical, or heterotypic nucleosomes) remains debated.
• Understanding CENP-A chromatin architecture is crucial for centromere assembly, maintenance, and kinetochore function.

Purpose of the Study:

• To determine the precise number of CENP-A molecules at the centromere in vivo.
• To elucidate the in vivo architecture of CENP-A chromatin in budding yeast.
• To understand the implications for centromere assembly and function.

Main Methods:

• Utilized live-cell fluorescence microscopy in Saccharomyces cerevisiae.
• Developed novel assays to quantify CENP-A (Cse4) deposition and stability.
• Leveraged the genetically defined point centromere of budding yeast.

Main Results:

• Demonstrated that budding yeast centromeres recruit two molecules of Cse4 (ScCENP-A).
• Showed Cse4 deposition occurs during S phase and remains stable through late anaphase.
• Provided evidence for the incorporation of a Cse4-H4 tetramer at the centromere.

Conclusions:

• The budding yeast centromere incorporates a Cse4-H4 tetramer, consisting of two Cse4 (ScCENP-A) molecules.
• This finding refines models of centromere architecture and CENP-A deposition.
• Accurate quantification of CENP-A molecules is key to understanding centromere function.