pho7+functions in additional stress responses. (A) Genes with a Pi- and pho7+-component based on microarray analysis were cross-referenced with a list of genes with pho7+ enrichment within 800 bp of the initial ATG (ChIP-Seq). The pie chart shows the GO Term enrichment for the identified genes as compared to a background model of all S. pombe transcripts. The boxed inset highlights a number of genes that were found in the small molecule catabolic process class, with those in bold serving as the initial targets for expression analysis. P-values for the enrichment against the background model are given. (B) The transmembrane transport category from A was expanded to identify specific ions whose transport is regulated by pho7+. Bold candidate genes served as initial target for expression analysis. (C) pho7+ cells were incubated in either normal (white) or stress (light gray) conditions, and the expression of the appropriate gene was measured by RT-qPCR. pho7Δ cells were also stressed (dark grey) to identify the level of pho7+-dependent regulation. Expression was normalized to act1+. Shown is the average of three biological replicates ± SE. (D) Heat map displaying the fold-change (log2 scale) for genes induced during stress in a pho7+-dependent manner. The top track in each sub-column compares expression in replete versus stress conditions for wild-type cells; the bottom track compares pho7+ to pho7Δ cells in the displayed stress (Pi: phosphate starvation, Fe: iron starvation, Cu: copper starvation, NaCl: osmotic shift, GE: carbon switch). Boxed regions identify genes that are induced in response to stress and require pho7+ for their stress response. Pie charts depict the percentage of genes responding to stress in a pho7+ independent manner (light grey), repressed by the loss of pho7+ but unaffected by stress (dark grey), and dependent on both (red).
Carter-O’Connell et al. BMC Genomics 2012 13:697 doi:10.1186/1471-2164-13-697