FACT mediates cohesin function on chromatin.

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Cohesin regulates genome architecture, sister chromatid cohesion, and chromosome compaction.
• Nucleosomes restrict cohesin complex recruitment and mobility on DNA.

Purpose of the Study:

• Investigate the role of the histone chaperone FACT in cohesin-mediated chromosome organization in Saccharomyces cerevisiae.
• Determine if FACT is required for cohesin localization and function in chromosome folding.

Main Methods:

• Co-immunoprecipitation to assess FACT-cohesin interaction.
• Chromatin immunoprecipitation followed by sequencing (ChIP-seq) to analyze cohesin localization.
• Hi-C technique to study genome-wide chromatin interactions and topological domain formation.
• Depletion of FACT in metaphase yeast cells.

Main Results:

• FACT directly interacts with cohesin and is dynamically required for its chromatin localization.
• FACT depletion leads to reduced cohesin accumulation at pericentric regions and chromosome arms.
• Cohesin-dependent topological associated domain (TAD)-like structures are reduced in FACT-depleted cells.
• Sister chromatid cohesion remains intact, but chromosome segregation fails upon FACT depletion.

Conclusions:

• The histone chaperone FACT plays a crucial role in cohesin-dependent chromosome organization.
• FACT is required for the formation of cohesin-mediated TADs during interphase and mitosis.
• This study uncovers a novel function for FACT in nuclear organization and chromosome folding.