Figure 4

Hog1 mediates major changes in chromatin structure to facilitate transcription of stress-responsive genes. (a) The distribution of nucleosomes referenced as reads/kilobase per million mapped reads (RPKM; transcription start site (TSS) ± 1 kb) of wild-type (wt; blue) and hog1 mutant (red) strains subjected (or not) to osmostress as indicated in the key. The plot represents the mean of reads in a group of 100 genes without transcription changes upon stress (upper panel), 100 genes that are induced in a Hog1-independent manner (middle panel) and 100 genes whose expression is induced upon osmostress depending on the SAPK (lower panel) (as in Figure 1d). The dotted black line marks the TSS. (b) The percentage of nucleosome occupancy in subsets from (a). Nucleosome occupancy was determined by averaging the TRPKs (trimmed mean of M values normalized read/kilobase density) from the 200 bp immediately downstream of the TSS. Average reads of non-stressed samples was used as maximum occupancy and as a reference for treated samples. **The statistical significance of the difference was assessed by a paired Student t-test of acceptance of equality at (P-value < 0.01) comparing the eviction of wild-type versus hog1 upon stress.