Transcription factor Atf1-dependent degradation of the mitotic cyclin Cdc13 is regulated by multiple factors in Schizosaccharomyces pombe

The bZIP transcription factor Atf1 is a key player in the transcriptional programme of Schizosaccharomyces pombe cell cycle. It also controls both expression and degradation of mitotic cyclin Cdc13. Temporal regulation of these opposing functions of Atf1 is critical for fidelity of cell division. Our investigations revealed that an increase in the activity of mitogen-activated protein kinase (MAPK) Spc1 during mitotic exit and the consequent phosphorylation of Atf1 along with the prevailing high activity of cyclin-dependent kinase Cdc2 regulate Cdc13 degradation. Our results also indicate the possibility of a complex interplay between Cdc2 inhibitory kinase Wee1, the anaphase-promoting complex and Atf1 during mitotic exit. These observations provide evidence of new regulatory mechanisms of mitotic exit.

Automated summary

The bZIP transcription factor Atf1 plays a crucial role in the transcriptional programme of the cell cycle in Schizosaccharomyces pombe. It regulates the expression and degradation of mitotic cyclin Cdc13, and the temporal regulation of these functions is important for accurate cell division. Our study reveals that the activity of mitogen-activated protein kinase Spc1, along with the phosphorylation of Atf1 and the high activity of cyclin-dependent kinase Cdc2, regulate the degradation of Cdc13 during mitotic exit. We also propose a potential complex interplay between Wee1 kinase, the anaphase-promoting complex, and Atf1 in mitotic exit.