BUB-1 targets PP2A:B56 to regulate chromosome congression during meiosis I in <i>C. elegans</i> oocytes.

Bel Borja, Laura; Soubigou, Flavie; Taylor, Samuel J P; Fraguas Bringas, Conchita; Budrewicz, Jacqueline; Lara-Gonzalez, Pablo; Sorensen Turpin, Christopher G; Bembenek, Joshua N et al. · Elife · 2020

basic_science · Level V

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Abstract

Protein Phosphatase 2A (PP2A) is a heterotrimer composed of scaffolding (A), catalytic (C), and regulatory (B) subunits. PP2A complexes with B56 subunits are targeted by Shugoshin and BUBR1 to protect centromeric cohesion and stabilise kinetochore-microtubule attachments in yeast and mouse meiosis. In <i>Caenorhabditis elegans</i>, the closest BUBR1 orthologue lacks the B56-interaction domain and Shugoshin is not required for meiotic segregation. Therefore, the role of PP2A in <i>C. elegans</i> female meiosis is unknown. We report that PP2A is essential for meiotic spindle assembly and chromosome dynamics during <i>C. elegans</i> female meiosis. BUB-1 is the main chromosome-targeting factor for B56 subunits during prometaphase I. BUB-1 recruits PP2A:B56 to the chromosomes via a newly identified LxxIxE motif in a phosphorylation-dependent manner, and this recruitment is important for proper chromosome congression. Our results highlight a novel mechanism for B56 recruitment, essential for recruiting a pool of PP2A involved in chromosome congression during meiosis I.

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