Kinase-phosphatase cooperativity on individual molecules during the cell cycle

Protein phosphorylation regulates protein function to control most aspects of cell biology. Although each phosphorylation site only exists in two states (on/off), the frequency of switching between these states can vary dramatically. Individual molecules that “flash” on and off rapidly can possess unique signalling properties, but these are difficult to study because this dynamic information remains hidden from current analytical methods. This is a major blind-spot in our knowledge because these phosphorylation- dephosphorylation (PdP) dynamics are a fundamental property of all phosphorylation sites, they can produce specific signalling properties and outputs, and they could also be altered to drive disease. This proposal will quantify PdP dynamics for the first time and focus on specific kinase- phosphatase pairs that induce rapid dynamics during mitosis. By combining mathematical modelling, biochemical reconstitution and cell biology, we will uncover how PdP dynamics can produce unique signalling outputs to drive chromosome segregation. During later years, we will examine how PdP dynamics can regulate other cell cycle phases, and we will test our hypothesis that PdP dynamics are deregulated to drive chromosomal instability in cancer. Together, this will reveal a hidden yet fundamental aspect of phospho-regulation that has widespread implications for cell biology and disease.