ABSTRACT: Affymetrix experiment performed on RNA isolated from Wild type, FHL1 deleted and FHL1,IFH1 double deleted strains. Data aquired in duplicate.,In S. cerevisiae the mRNAs from the 138 ribosomal protein (RP) genes are amongst the most abundant in the cell, and their transcription is regulated tightly so that they are the most prominent cluster in most transcriptome experiments. It has recently been observed that the proteins Fhl1p and Ifh1p are found almost exclusively at RP genes (Lee et al., Science, 298, 799-804, 2002;Jorgensen et al., Genes Dev, 18, 2491-2505 2004; Schawalder et al Nature in press; Rudra et al , EMBO J. submitted), and data suggests they are the true transcription factors.,This experiment utilizes Affymetrix arrays to measure the level of all mRNAs in cells with a deletion of FHL1 or of both FHL1 and IFH1, compared to the wild type strain, W303. Such mutant cells are viable but grow very slowly (Hermann-Le Denmat S. et al., Mol Cell Biol, 14, 2905-2913, 1994; Cherel and Thuriaux, Yeast, 11, 261-270, 1995). Total RNA was made from log phase cells, amplified according to conventional methods, and hybridized to the array. (Since the total RNA/cell of the mutants is only a fifth of the wt, each mutant required five times the number of cells to provide the same amount of RNA.) The experiment was carried out in duplicate and the six tables provide the raw data from the wt, W303, delFHL1, and delFHL1, delIFH1 strains.,Although we expected that the RP genes would be substantially reduced in these mutant cells, they are only slightly less abundant than normal in comparison to all other mRNAs! The interesting result is that the cells respond to a severe deficiency of ribosomes by reducing the level of nearly all mRNAs to match the capacity of the translational apparatus.
