The vacuole shapes the nucleus and the ribosomal DNA loop during mitotic delays.

Emiliano Matos-Perdomo, Silvia Santana-Sosa, Jessel Ayra-Plasencia, Sara Medina-Suárez, Félix Machín

Life science alliance 2022 Oct

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The ribosomal DNA (rDNA) array of Saccharomyces cerevisiae has served as a model to address chromosome organization. In cells arrested before anaphase (mid-M), the rDNA acquires a highly structured chromosomal organization referred to as the rDNA loop, whose length can double the cell diameter. Previous works established that complexes such as condensin and cohesin are essential to attain this structure. Here, we report that the rDNA loop adopts distinct presentations that arise as spatial adaptations to changes in the nuclear morphology triggered during mid-M arrests. Interestingly, the formation of the rDNA loop results in the appearance of a space under the loop (SUL) which is devoid of nuclear components yet colocalizes with the vacuole. We show that the rDNA-associated nuclear envelope (NE) often reshapes into a ladle to accommodate the vacuole in the SUL, with the nucleus becoming bilobed and doughnut-shaped. Finally, we demonstrate that the formation of the rDNA loop and the SUL require TORC1, membrane synthesis and functional vacuoles, yet is independent of nucleus-vacuole junctions and rDNA-NE tethering. © 2022 Matos-Perdomo et al.

Citation

Emiliano Matos-Perdomo, Silvia Santana-Sosa, Jessel Ayra-Plasencia, Sara Medina-Suárez, Félix Machín. The vacuole shapes the nucleus and the ribosomal DNA loop during mitotic delays. Life science alliance. 2022 Oct;5(10)