Control of transcription during the cell cycle
The cell cycle is one of the most fundamental and important problems in biology. Accordingly, in most cells the cycle is controlled and orchestrated by a complex and multi-layered regulatory network. the polo kinase Cdc5p plays a particularly prominent role in controlling cell-cycle-dependent gene expression that is crucial for the execution of mitosis in the model eukaryote Saccharomyces cerevisiae. Until recently, little was known of how Cdc5p exerts temporal control over the transcription of cell cycle genes. Morgan and colleagues have now elucidated the molecular mechanism whereby Cdc5p regulates a particular cell cycle gene cluster (called the CLB2 cluster). Cdc5p is recruited to the CLB2 promoter at the appropriate time, where it targets a particular transcription factor complex (called Mcm1p-Fkh2p-Ndd1p) by direct phosphorylation of the Ndd1p component.
It was shown that this phosphorylation event is required for the normal temporal expression of cell-cycle-regulated genes during the G2 and M phases of the cell cycle. Furthermore, severe defects in cell division occured in the absence of phosphorylation, showing that polo kinase is required for the production of key mitotic regulators, in addition to its previously defined roles in various other mitotic events.
Darieva Z, Bulmer R, Pic-Taylor A, Doris KS, Geymonat M, Sedgwick SG, Morgan BA, Sharrocks AD. 2006. Polo kinase controls cell-cycle-dependent transcription by targeting a coactivator protein. Nature 444, 494-498.
