Biology subjects

Makrantoni, V.

Publications and source records attributed to Makrantoni, V..

3 recordsLinked to original sources

bioRxiv2020

The proteomic landscape of centromeric chromatin reveals an essential role for the Ctf19CCAN complex in meiotic kinetochore assembly

Kinetochores direct chromosome segregation in mitosis and meiosis. Faithful gamete formation through meiosis requires that kinetochores take on new functions that impact homolog pairing, recombination and the orientation of kinetochore attachment to microtubules in meiosis I. Using an unbiased proteomics pipeline, we determined the composition of centromeric chromatin and kinetochores at distinct cell-cycle stages, revealing extensive reorganisation of kinetochores during meiosis. The data uncover a network of meiotic chromosome axis and recombination proteins that replace the microtubule-binding outer kinetochore sub-complexes during meiotic prophase. We show that this kinetochore remodelling in meiosis requires the Ctf19cCCAN inner kinetochore complex. Through functional analyses, we identify a Ctf19cCCAN-dependent kinetochore assembly pathway that is dispensable for mitotic growth, but becomes critical upon meiotic entry. Therefore, extensive kinetochore remodelling and a distinct assembly pathway direct the specialization of meiotic kinetochores for successful gametogenesis.

cell biology↗

bioRxiv2020

A dCas9/CRISPR-based targeting system identifies a central role for Ctf19 in kinetochore-derived suppression of meiotic recombination

In meiosis, crossover formation between homologous chromosomes is essential for faithful segregation. However, improperly controlled or placed meiotic recombination can have catastrophic consequences on genome stability. Specifically, within centromeres and surrounding regions (i.e. pericentromeres), crossovers are associated with chromosome missegregation and developmental aneuploidy. In organisms ranging from yeast to humans, crossovers are repressed within (peri)centromeric regions. We previously identified a key role for the multi-subunit, kinetochore-associated Ctf19 complex (Ctf19c; the budding yeast equivalent of the human CCAN) in regulating pericentromeric crossover formation. Here, we develop a dCas9/CRISPR-based system that allows ectopic targeting of Ctf19c-subunits to a non-centromeric locus during meiosis. Using this approach, we query sufficiency in meiotic crossover suppression, and identify Ctf19 (the budding yeast homologue of vertebrate CENP-P) as a central mediator of kinetochore-associated crossover control. We show that the effect of Ctf19 is encoded in its NH2-terminal tail, and depends on residues known to be important for the recruitment of the Scc2-Scc4 cohesin regulator to kinetochores. We thus reveal a crucial determinant that links kinetochores to meiotic recombinational control. This work provides insight into localized control of meiotic recombination. Furthermore, our approach establishes a dCas9/CRISPR-based experimental platform that can be utilized to investigate and locally manipulate meiotic crossover control. This platform can easily be adapted in order to investigate other aspects of localized chromosome biology.

genetics↗

bioRxiv2019

Evolutionary repair: changes in multiple functional modules allow meiotic cohesin to support mitosis

Different members of the same protein family often perform distinct cellular functions. How much are these differing functions due to changes in a proteins biochemical activity versus changes in other proteins? We asked how the budding yeast, Saccharomyces cerevisiae, evolves when forced to use the meiosis-specific kleisin, Rec8, instead of the mitotic kleisin, Scc1, during the mitotic cell cycle. This perturbation impairs sister chromosome linkage and reduces reproductive fitness by 45%. We evolved 15 populations for 1750 generations, substantially increasing their fitness, and analyzed their genotypes and phenotypes. We found no mutations in Rec8, but many populations had mutations in the transcriptional mediator complex, cohesin-related genes, and cell cycle regulators that induce S phase. These mutations improve sister chromosome cohesion and slow genome replication in Rec8-expressing cells. We conclude that changes in known and novel partners allow proteins to improve their ability to perform new functions.

evolutionary biology↗