Figure 5

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. pho7 Δ 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 pho7 Δ 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).