
==== Front
bioRxiv
BIORXIV
bioRxiv
2692-8205
Cold Spring Harbor Laboratory

10.1101/2024.09.14.613089
preprint
1
Article
Synaptonemal complex protects double-Holliday junctions during meiosis
Tang Shangming
Koo Jennifer
Pourhosseinzadeh Mohammad
Nguyen Emerald
Liu Natalie
Ma Christopher
Lu Hanyu
Lee Monica
Hunter Neil http://orcid.org/0000-0003-1498-2327

15 9 2024
2024.09.14.613089https://creativecommons.org/licenses/by/4.0/ This work is licensed under a Creative Commons Attribution 4.0 International License, which allows reusers to distribute, remix, adapt, and build upon the material in any medium or format, so long as attribution is given to the creator. The license allows for commercial use.
http://biorxiv.org/lookup/doi/10.1101/2024.09.14.613089
nihpp-2024.09.14.613089.pdf
Chromosomal linkages formed through crossover recombination are essential for accurate segregation of homologous chromosomes during meiosis 1 . DNA events of recombination are spatially and functionally linked to structural components of meiotic chromosomes 2 . Imperatively, biased resolution of double-Holliday junction (dHJ) intermediates into crossovers 3,4 occurs within the synaptonemal complex (SC), the meiosis-specific structure that mediates homolog synapsis during the pachytene stage 5,6 . However, the SC’s role in crossing over remains unclear. Here we show that SC promotes crossover-specific resolution by protecting dHJs from unscheduled and aberrant resolution. When key SC components are conditionally inactivated during pachytene, dHJs are resolved into noncrossover products by Sgs1-Top3-Rmi1 (STR), the yeast ortholog of the human BLM complex 7 . Cohesin, the core component of SC lateral elements, plays a primary role in chromatin organization and is required to maintain both SCs and crossover recombination complexes (CRCs) during pachytene. SC central region component Zip1 is required to maintain CRCs even when dHJs are stabilized by inactivating STR. Reciprocally, SC stability requires continuous presence of CRCs, an unanticipated interdependence with important implications for SC dynamics. In conclusion, through hierarchical and interdependent functions of its key components, the SC enables crossover-specific dHJ resolution and thereby ensures the linkage and segregation of homologous chromosomes.
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