Aurora promotes cell division during recovery from TOR-mediated cell cycle arrest by driving spindle pole body recruitment of Polo

The coordination of cell division and growth in response to changes in nutrient supply is mediated by TOR signalling. In fission yeast, increased nutrient provision transiently delays mitotic onset without affecting growth. The result is an increase in cell size at division. We find that this block to cell division relies upon TOR and MAPK signalling and that mitotic entry during recovery from this block is regulated by the Aurora kinase Ark1. We show that Ark1 phosphorylation of polo kinase Plo1 within the linker region between the kinase domain and polo boxes drives Plo1 onto the spindle poles where it promotes mitosis. Interestingly, the use of Ark1 to phosphorylate Plo1 and promote mitotic entry is dependent on the environment.