The analysis of novel Far1 motif important for Cdk1 inhibition

Abstract

The cell cycle progression in yeast is regulated by cyclin-dependent kinases (CDKs), which phosphorylate different substrate proteins to ensure proper order and timing of cell cycle events. In the presence of pheromones, cell division can be interrupted in the G1 phase via activation of the mating mitogen-activated protein kinase (MAPK) pathway. In this pathway, MAP kinase Fus3 phosphorylates Far1 protein. Consequently, phosphorylated Far1 can bind to the CDK complex and suppress its activity. Although T306 phosphorylation of Far1 was shown to be crucial for CDK inhibition, the exact mechanism and main determinants of this process in the Far1 protein sequence remain unclear. In this study, we analysed the previously undescribed amino acid region of Far1 and identified key residues with the strongest impact on CDK activity, which likely points to their importance for protein-protein interactions. Our results suggest that the analysed Far1 region may potentially serve as a CDK docking site. However, further analyses are required to reveal the exact mechanism of inhibition.