HEI10 is subject to phase separation and mediates RPA1a degradation during meiotic interference-sensitive crossover...

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Meiotic crossovers (COs) shuffle genetic information, crucial for sexual reproduction.
• Class I COs, the majority, are regulated by interference and involve ZMM proteins like HEI10.
• The recruitment mechanism of HEI10 to CO sites remained unclear.

Purpose of the Study:

• To elucidate the mechanism by which HEI10 is recruited to meiotic recombination sites.
• To investigate the role of liquid-liquid phase separation (LLPS) in HEI10 function.
• To identify HEI10 interacting partners and their roles in CO formation.

Main Methods:

• Chromatin immunoprecipitation followed by mass spectrometry (IP-MS) to identify protein interactions.
• Analysis of HEI10 foci formation and LLPS properties in vivo.
• Characterization of a HEI10 mutant allele (S70F) affecting LLPS and CO formation.
• Investigation of RPA1a ubiquitination and degradation regulated by HEI10.

Main Results:

• HEI10 forms foci on chromatin via LLPS, dependent on Ser70 residue.
• A HEI10^S70F mutation disrupts LLPS and impairs class I CO formation.
• RPA1a was identified as a HEI10 interacting protein, also undergoing phase separation.
• HEI10 regulates RPA1a ubiquitination and degradation, and is essential for other class I CO factor condensation.

Conclusions:

• HEI10 utilizes LLPS for chromatin recruitment, a critical step in class I CO formation.
• HEI10 couples LLPS with ubiquitination-mediated protein regulation to control meiotic COs.
• This study provides novel mechanistic insights into the regulation of meiotic recombination.