CONICET | Buscador de Institutos y Recursos Humanos

Gene expression regulation by intracellular stimulus-activated protein kinases are essential for cell adaptation to environmental changes. The transcriptional induction of most genes whose transcription responds to salt stress is dependent on the association of the Hog1 kinase in stress-responsive genes that strongly correlates with chromatin remodeling and increased gene expression. Previously we described that PKA catalytic and regulatory subunits are associated with both coding regions and promoters of the several osmo-responsive genes in a stress dependent manner. Particularly, Tpk2 catalytic subunit activity regulates the chromatin remodelers Snf2 (SWI/SNF complex) and Arp8 (INO80 complex) association to promoters and coding regions to downregulate the gene expression during osmotic stress. Here, we focus on the interplay between PKA and Hog1 kinases on gene expression in response to osmotic stress. We tested for genetic interaction between TPK2 and HOG1 genes for cell survival to osmotic stress. While tpk2D mutant strain did not confer sensitivity to osmotic stress, hog1D mutant strain showed hypersensitivity to osmotic stress. The double mutant hog1Dtpk2D displayed high tolerance to salinity suggesting that both kinase has an opposite role in cell adaptation to osmotic stress. ChIP assays showed a correlation in the in vivo kinetic recruitment of Tpk2 and Hog1 to HSP42 coding region and RPS29B promoter region in response to osmotic stress, with a maximum at 5-10 minutes post-osmotic stress. We then analysed the nucleosome positioning at the promoter and coding region in the RPS29B gene by Micrococcal Nuclease (MNase) digestion of chromatin before and after stress in wild type. We found that osmotic stress, promotes an increase of compactness of the chromatin that correlated to down-regulation of RPS29B gene expression. Our results suggest that transient stress adaptive response could be regulated by opposite roles of Hog1 and PKA.