Figure 3.

Greater enrichment of Hog1 induces stronger recruitment of RNA Pol II and determines transcriptional output. (a) A Venn diagram representing the overlap of Hog1-bound genes (Z-score > 4) and recruited RNA Pol II (Z-score > 6) with 320 representative genes that are up-regulated upon osmostress by more than three-fold. (b) Colocalization of Hog1 with RNA Pol II results in stronger binding of both to chromatin. The boxplot represents distribution of Z-score values of genes with Hog1 enrichment and RNA Pol II compared to those genes with RNA Pol II but without Hog1 association. (c) Positive correlation between Hog1, RNA Pol II binding and expression in response to stress. Each point in the three-dimensional graph represents the 144 genes (overlapping region from (a)); the x-axis represents binding of Hog1, the y-axis binding of Rbp1 (both as Z-score values) and the z-axis the expression as the fold change (FC) of a wild-type strain upon stress. (d) Gene expression is dependent on the duration and intensity of Hog1 binding to target genes. The dose-response expression of osmoresponsive genes was assayed by northern blot and probed for STL1 (left-hand panel). Association of tagged Hog1-HA (middle panel) and Rpb1 (right-hand panel) to the promoter region of STL1 was analyzed by ChIP. The results are shown as the fold induction of stressed against non-stressed (time zero) cultures.