Regulation of Ace2-dependent genes requires components of the PBF complex in Schizosaccharomyces pombe.

The division cycle of unicellular yeasts is completed with the activation of a cell separation program that results in the dissolution of the septum assembled during cytokinesis between the 2 daughter cells, allowing them to become independent entities. Expression of the eng1(+) and agn1(+) genes, encoding the hydrolytic enzymes responsible for septum degradation, is activated at the end of each cell cycle by the transcription factor Ace2. Periodic ace2(+) expression is regulated by the transcriptional complex PBF (PCB Binding Factor), composed of the forkhead-like proteins Sep1 and Fkh2 and the MADS box-like protein Mbx1.

Removal of centrosomal PP1 by NIMA kinase unlocks the MPF feedback loop to promote mitotic commitment in S. pombe.

Background: Activation of the Cdk1/cyclin B complex, also known as mitosis-promoting factor (MPF), drives commitment to mitosis. Interphase MPF is inhibited through phosphorylation of Cdk1 by Wee1-related kinases. Because Cdc25 phosphatases remove this phosphate, Cdc25 activity is an essential part of the switch that drives cells into mitosis.

Ace2p controls the expression of genes required for cell separation in Schizosaccharomyces pombe.

Schizosaccharomyces pombe cells divide by medial fission through contraction of an actomyosin ring and deposition of a multilayered division septum that must be cleaved to release the two daughter cells. Here we describe the identification of seven genes (adg1(+), adg2(+), adg3(+), cfh4(+), agn1(+), eng1(+), and mid2(+)) whose expression is induced by the transcription factor Ace2p. The expression of all of these genes varied during the cell cycle, maximum transcription being observed during septation.