Non-essential kinetochore proteins contribute to meiotic chromosome condensation through polo-like kinase

Abstract

Chromosome condensation plays a pivotal role during faithful chromosome segregation, hence understanding the factors that drive condensation is crucial to get mechanistic insight into chromosome segregation. Previously we showed that in budding yeast, the absence of the non-essential kinetochore proteins affects chromatin-condensin association in meiosis but not in mitosis. A differential organization of the kinetochores, that we and others observed earlier during mitosis and meiosis may contribute to the meiotic-specific role. Here, with our in-depth investigation using in vivo chromosome condensation assays in cells sans a non-essential kinetochore protein, Ctf19, we establish that these proteins have roles in achieving a higher meiotic condensation without influencing much of the mitotic condensation. We further observed an accumulation of the polo-like kinase Cdc5 owing to its higher protein stability in ctf19{Delta} meiotic cells. High Cdc5 activity causes hyper-phosphorylation of the condensin resulting in its reduced stability and concomitant decreased association with the chromatin. Overall, our findings highlight the role of Ctf19 in promoting meiotic chromosome condensation by influencing the activity of Cdc5 and thereby affecting the stability and association of condensin with the chromatin.