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Recruitment of the MRX complex to recombination sites during meiosis by Priyanka PRIYADARSHINI -
Lundi 20 avril 2026 à 15h00 - Salle Jean-Baptiste Carnoy (B.059) - Bâtiment Carnoy - Croix du Sud - 1348 Louvain-la-Neuve
Meiosis is a specialized form of cell division that generates haploid
gametes containing half the chromosomal content from diploid germ
cells and is essential for sexual reproduction in all eukaryotes.
Accurate chromosome segregation during meiosis relies on meiotic
recombination, a highly coordinated process that promotes genetic
diversity by breaking allelic linkages and forming crossovers that
physically connect homologous chromosomes until their separation.
Meiotic recombination is initiated by the programmed induction of
hundreds of DNA double-strand breaks (DSBs) across the genome,
which are rapidly repaired by homologous recombination. In
budding yeast, DSB formation and subsequent initiation of DSB repair
are carried out by at least ten proteins organized into three subcomplexes:
the Spo11 core complex, which makes the breaks, the
RMM complex, which is thought to act as an assembly platform, and
the MRX (Mre11-Rad50-Xrs2) complex, best known for its role in DSB
repair.
A long-standing question in the field is why and how the MRX complex
is recruited to meiotic DSB sites prior to break formation, despite its
canonical role in DNA repair. Using biochemical, molecular genetics,
biophysical, and structural approaches, I show that MRX recruitment
is driven by multiple cooperative mechanisms.
I demonstrate that Mre11 and MRX undergo DNA-dependent
biomolecular condensation mediated by the Mre11 C-terminal
intrinsically disordered region. I further identify direct interactions
between Mre11 and the DSB protein Mer2, as well as a SUMO-interacting
motif within Mre11 that contributes to its recruitment in vivo.
Additionally, I define a minimal region mediating Xrs2-Mer2 interaction.
Together, this work reveals how biomolecular condensation, protein-protein
interactions, protein-DNA interactions, and SUMO-dependent
recruitment collaborate to ensure the timely and precise recruitment of
the MRX complex prior to meiotic DSB formation, thereby safeguarding
genome integrity during meiosis.
Jury members :
Prof. Corentin Claeys Bouuaert (UCLouvain)(Promoteur)
Prof. Bernard Hallet (UCLouvain) (Président)
Prof. Charles Hachez (UCLouvain) (Secrétaire)
Prof. Chloé Girard (Université Paris Saclay, France)
Prof. Joao Matos (Max Perutz Labs, Université de Vienne, Autriche)
Pay attention : the public defense of Priyanka PRIYADARSHINI will also take place in the form of a videoconference
