EBP2 is a member of the yeast RRB regulon, a transcriptionally coregulatedset of genes that are required for ribosome and rRNA biosynthesis

In an effort to identify sets of yeast genes that are coregulated across va rious cellular transitions, gene expression data sets derived from yeast ce lls progressing through the cell cycle, sporulation, and diauxic shift were analyzed. A partitioning algorithm was used to divide each data set into 2 4 clusters of similar expression profiles, and the membership of the cluste rs was compared across the three experiments. A single cluster of 189 genes from the cell cycle experiment was found to share 65 genes with a cluster of 159 genes from the sporulation data set. Many of these genes were found to be clustered in the diauxic-shift experiment as well. The overlapping se t was enriched for genes required for rRNA biosynthesis and included genes encoding RNA helicases, subunits of RNA polymerases I and III, and rRNA pro cessing factors. A subset of the 65 genes was tested for expression by a qu antitative-relative reverse transcriptase PCR technique, and they were foun d to be coregulated after release from alpha factor arrest, heat shock, and tunicamycin treatment. Promoter scanning analysis revealed that the 65 gen es within this ribosome and rRNA biosynthesis (RRB) regulon were enriched f or two motifs: the 13-base GCGATGAGATGAG and the 11-base TGAAAAATTTT consen sus sequences. Both motifs were found to be important for promoting gene ex pression after release from alpha factor arrest in a test rRNA processing g ene (EBP2), which suggests that these consensus sequences may function broa dly in the regulation of a set of genes required for ribosome and rRNA bios ynthesis.