Cell size is not just a physical characteristic of biological cells but a crucial factor influencing their functions. Proliferating cells must coordinate growth and division to maintain uniformity in size.
In plants, KRP4 is a protein that plays a pivotal role in regulating cell size in meristems. During the mitotic phase of a cell cycle, KRP4 interacts with chromosomes and consequently is distributed equally to daughter cells upon asymmetric division. The concentration of KRP4 in newly formed daughter cells determines how long it takes before the cell can replicate its DNA and divide. Consequently, the equal distribution of KRP4 during cell divisions ensures that sister cells progress through the cell cycle at comparable sizes, correcting the size variability caused by asymmetric divisions (D’Ario et al., 2021).
Studying KRP4's dynamic interaction with chromatin across the cell cycle is critical to understanding cell size control. Our application of AlphaFold modeling predicts interactions between KRP4 and other nuclear proteins in Arabidopsis thaliana, pinpointing potentially interesting regulators of its chromatin association. Additionally, we employed the TurboID approach to uncover both strong and transient partners of KRP4, providing a comprehensive view of its proteome network. We will discuss our current results and hypotheses for how KRP4 interacts with chromatin during the cell cycle.
Chromatin partitioning by cell cycle regulators like KRP4 has been proposed as part of the mechanism for cell size control across diverse organisms (Xie & Skotheim, 2021). Our work marks a step forward to understanding this fundamental process in various biological contexts.