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bioRxiv · 10.1101/2020.12.15.422856

Phase separation of Mer2 organizes the meiotic loop-axis structure of chromatin during meiosis I

Tsai, B.·Liu, W.·Dong, D.·Shi, K.·Chen, L.·Gao, N.
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Abstract

Sexually reproducing organisms acquire genetic diversity through meiotic recombination during meiosis I, which is initiated via programmed DNA double-strand breaks (DSBs) induced by Spo11-containing machinery in each meiotic cell. The combination of programmed DSB sites in each meiotic cell must be diverse, which requires a certain degree of randomness in the distribution of DSBs. The formation of programmed DSBs requires a preestablished loop-axis structure of chromatin. Here, we demonstrate that the axial element protein Mer2 undergoes liquid-liquid phase separation in vitro and in vivo through its intrinsically disordered C-terminal domain. A DNA binding motif within its central domain is responsible for bringing DNA into Mer2 liquid droplets and Mer2-DNA complex could assemble into filamentous structures extending from the droplets. These results suggest that phase separation of Mer2 drives the formation of a droplet-loop structure of meiotic chromatin to facilitate and to diversify programmed DSB formation.

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Tsai, B., Liu, W., Dong, D., Shi, K., Chen, L., Gao, N.. 2020-12-15. Phase separation of Mer2 organizes the meiotic loop-axis structure of chromatin during meiosis I. https://doi.org/10.1101/2020.12.15.422856

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