Regulation of gene expression by Hcm1 in chronic LiCl stress

Gene expression was quantified in S. cerevisiae cells after 40 hours of LiCl treatment or control conditions. Cells expressing wild type (WT) Hcm1, a stable Hcm1 mutant (Hcm1-3N), or a consitutitvely active, phosphomimetic mutant (Hcm1-8E) were compared to allow the identification of genes whose expression depends upon dynamic phosphorylation of Hcm1. We found that dynamic phosphorylation of Hcm1 is required for expression of Hcm1 target genes in LiCl stress. Gene expression was measured in cells expressing wild type (WT) Hcm1, Hcm1-3N (3N) or Hcm1-8E (8E). Each strain was innoculated into both control medium and medium containing 150mM LiCl. After 24 hours of growth, saturated cultures were diluted into the same growth media. Samples were collected after an additional 16 hours (40 hours total of total growth) when cells were in logarithmic phase. Biological triplicate experiments were performed.