Regulation of S-phase transcription factors by Cdk1

Analysis of gene expression across the cell cycle from wild type cells, and cells expressing alleles of Yox1, Yhp1, Hcm1, and Tos4 that cannot be phosphorylated by Cdk1. Expression of S-phase and M/G1 transcripts are downregulated when phosphorylation of these factors is blocked, demonstrating that Cdk1 promotes expression of late cell cycle genes. These experiments are two-color hybridizations of RNA isolated from synchronized wild type (WT) or phosphomutant (4P) cells, compared to RNA from asyncrhonous wild type cells in mid-log phase. Wild type and mutant cells were synchronized in G1 phase, released into the cell cycle and samples collected at 15 minute intervals. Each time course was carried out in duplicate, the replicate experiment was performed as a dye swap.