DNA-driven condensation assembles the meiotic DNA break machinery

Area of Science:

• Cell Biology
• Genetics
• Molecular Biology

Background:

• Accurate chromosome segregation during meiosis is vital for genome stability.
• Homologous recombination, initiated by DNA double-strand breaks (DSBs) from Spo11, is crucial for this process.
• The protein assemblies controlling DSB formation are not well understood.

Purpose of the Study:

• To investigate the molecular mechanisms of the Saccharomyces cerevisiae RMM (Rec114, Mei4, Mer2) protein complex in DSB formation.
• To elucidate how these proteins self-assemble and interact with DNA to regulate DSB sites.

Main Methods:

• Molecular characterization of Rec114, Mei4, and Mer2 protein subcomplexes.
• Analysis of protein condensation with DNA in vitro and in vivo.
• Investigating the role of multivalent interactions and protein-DNA interactions in condensate formation and DSB activity.

Main Results:

• Rec114-Mei4 and Mer2 subcomplexes independently condense with DNA into reversible, phase-separated-like nucleoprotein clusters.
• Multivalent interactions drive this condensation, and weakened protein-DNA interactions disrupt condensate formation and DSBs.
• In vitro, RMM condensates fuse and recruit Spo11 complexes, forming active DSB centers on chromosome axes.

Conclusions:

• The DSB machinery self-assembles on chromosome axes to create centers of DNA double-strand break activity.
• Multilayered control of Spo11 activity is achieved through regulatory component recruitment and modulation of condensate biophysical properties.
• This study provides insight into the self-assembly and regulation of the meiotic DSB machinery.