Control of meiotic crossover interference by a proteolytic chaperone network

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Meiosis is crucial for sexual reproduction, generating genetic diversity through homologous chromosome crossovers.
• Crossover distribution is tightly regulated by interference, ensuring at least one exchange per chromosome pair.
• The E3 ligase HEI10 is implicated in crossover site selection in Arabidopsis, but its regulation remains unclear.

Purpose of the Study:

• To identify genetic factors controlling HEI10 dynamics and meiotic crossover distribution in Arabidopsis.
• To elucidate the molecular mechanisms underlying crossover interference and recombination landscape regulation.

Main Methods:

• Forward genetic screen in Arabidopsis to identify mutants affecting crossover rates.
• Characterization of the high crossover rate3 (hcr3) mutant and identification of the HCR3 gene.
• Biochemical and genetic analyses to determine the function of HCR3/J3 and its interaction with HSP70 and HEI10.

Main Results:

• Identification of hcr3, a dominant-negative mutant that reduces crossover interference and increases genome-wide crossovers.
• HCR3 encodes J3, an HSP40 co-chaperone that targets protein aggregates and condensates for degradation.
• The J3-HSP70 chaperone network facilitates HEI10 proteolysis, thereby regulating meiotic recombination and interference.

Conclusions:

• The HSP40/J3-HSP70 chaperone system plays a novel role in regulating meiotic recombination dynamics.
• Control of HEI10 proteolysis by J3-HSP70 is a key mechanism for managing crossover interference and distribution.
• These findings reveal a new layer of regulation in the meiotic recombination landscape, impacting genetic variation.