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. The results of our in vivo chromosome condensation assays in budding yeast reveal that chromosomes undergo a higher degree of condensation during meiosis than in mitosis. Earlier the non-essential kinetochore proteins were shown to have several significant meiotic functions. We conclude that these proteins might also have a role in achieving higher meiotic condensation since we observed meiotic-specific condensation defects in the absence of the non-essential kinetochore protein, Ctf19. To address the mechanism involved, we observed an accumulation of the polo-like kinase Cdc5 owing to its higher protein stability in ctf19Delta meiotic cells. High Cdc5 activity perhaps leads to hyper-phosphorylation of the condensin which shows reduced stability with 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.