TORC2 dependent phosphorylation modulates calcium regulation of fission yeast myosin

Abstract

30All cells have the ability to respond to changes in their environment. Signalling 31 networks modulate cytoskeleton and membrane organisation to impact cell 32 cycle progression, polarised cell growth and multicellular development 33 according to the environmental setting. Using diverse in vitro, in vivo and single 34 molecule techniques we have explored the role of myosin-1 signalling in 35 regulating endocytosis during both mitotic and meiotic cell cycles. We have 36 established that a conserved serine within the neck region of the sole fission 37 yeast myosin-1 is phosphorylated in a TORC2 dependent manner to modulate 38 myosin function. Myo1 neck phosphorylation brings about a change in the 39 conformation of the neck region and modifies its interaction with calmodulins, 40Myo1 dynamics at endocytic foci, and promotes calcium dependent switching 41 between different calmodulin light chains. These data provide insight into a 42 novel mechanism by which myosin neck phosphorylation modulates acto-43 myosin dynamics to control polarised cell growth in response to mitotic and 44 meiotic cell-cycle progression and the cellular environment. 45 46