388 / 2019-02-21 20:25:25

SWITCH 1/DYAD is a novel WINGS APART-LIKE antagonist that maintains sister chromatid cohesion in meiosis

Arabidopsis thaliana,chromosome segregation,cohesion,meiosis

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The development and reproduction of the majority of multicellular organisms depend on two types of cell division - mitosis and meiosis that both rely on cohesin, which embraces the sister chromatids and plays a crucial role for the faithful distribution of chromosomes to daughter cells and thus for the genomic stability. The functional cohesin is ensured by its dynamic chromosomal association that is under a spatiotemporal control; prior to the cleavage by Separase at anaphase onset, cohesin is largely removed from chromosomes by the non-proteolytic action of WINGS APART-LIKE (WAPL), a mechanism referred to as the prophase pathway. To prevent the premature loss of sister chromatid cohesion, WAPL is inhibited in early mitosis by Sororin. However, Sororin homologs have only been found to function as WAPL inhibitors during mitosis in vertebrates and Drosophila. Here, combining the biochemical, genetic and cytological approaches next to live cell imaging, we demonstrate that SWITCH 1/DYAD, a cohesin regulator identified previously for two decades with a yet unknown molecular mechanism, defines a novel WAPL antagonist that acts in meiosis of Arabidopsis. Crucially, SWI1 becomes dispensable for sister chromatid cohesion in the absence of WAPL. In addition, despite the lack of any sequence similarities, we found that SWI1 is regulated and functions in a similar manner as Sororin hence likely representing a case of convergent molecular evolution across the eukaryotic kingdom.