Eco1-dependent cohesin acetylation anchors chromatin loops and cohesion to define functional meiotic chromosome domains

Barton, R.E., Massari, L.F., Robertson, D., and Marston, A.L.

eLife (2022) 11, e74447



Meiotic recombination and chromosome segregation require the establishment of chromatin boundaries by the acetyltransferase Eco1 which anchors both chromatin loops and cohesion.

Summary of Paper by Lori Koch 

Meiosis involves recombination between homologous chromosomes, followed by the segregation of homologous chromosomes in meiosis I and sister chromatids in meiosis II. Central to this process is the interaction of the ring-shaped cohesin complex with chromosomes, which can both link sister chromatids together and produce DNA loops within each sister chromatid. In their latest publication in eLife, scientists in the Marston group found that the acetyltransferase Eco1 is required for the positioning of DNA loops, meiotic recombination and chromosome segregation in meiosis I and II. Eco1 is known to link sister chromatids together by counteracting the cohesin-destabilizing factor Wpl1. The scientists depleted Eco1 and found that it was essential for progression through meiosis, even in the absence of Wpl1. They mapped the contacts within chromosomes in 3D using the Hi-C technique and observed that loops were increased in size and less uniformly positioned in Eco1-depleted cells. By performing experiments with cells which do not undergo DNA replication, they showed that Eco1 can position DNA loops even in the absence of a sister chromatid. Live-cell imaging showed that positioned DNA loops are important for both meiotic recombination and chromosome segregation. Interestingly, they found that the meiosis I chromosome segregation defect caused by loss of Eco1 could be rescued by loss of Wpl1, however this was not the case for defective recombination and meiosis II segregation. Their results demonstrate that the precise positioning of DNA loops is important for multiple functions of meiotic chromosomes.

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