Genome-wide location analysis of the stress-activated MAP kinase Hog1 in yeast.

MAP kinase signal transduction pathways play a critical role in eukaryotic cells to unleash complex transcriptional programs to properly adapt to changing environments. The MAP kinase Hog1 upon activation is physically recruited to the chromatin of osmostress responsive genes. This allowed us to use in vivo chromatin immunoprecipitation in combination with microarrays (ChIP-Chip) to identify the transcriptional targets of Hog1 at the genomic scale. The ChIP-Chip method described here revealed that the stress-activated MAP kinase gets recruited to most of the osmoinducible genes. Interestingly Hog1 associates with both the 5' upstream and the 3' downstream sequences of stress genes. We confirmed by targeted ChIP at several stress genes that the MAP kinase crosslinks all over the transcribed regions in all cases tested. Taken together the genome-wide location analysis reported here is a powerful approach to determine the genomic binding patterns of an activated MAP kinase and will be of great interest to analyze other SAPKs under different environmental conditions.