Osmotic Stress Signaling and Osmoadaptation in Yeasts

Abstract

The ability to adapt to altered availability of free water is a fundamental property of living cells. The principles underlying osmoadaptation are well conserved. The yeast Saccharomyces cerevisiae is an excellent model system with which to study the molecular biology and physiology of osmoadaptation. Upon a shift to high osmolarity, yeast cells rapidly stimulate a mitogen-activated protein (MAP) kinase cascade, the high-osmolarity glycerol (HOG) pathway, which orchestrates part of the transcriptional response. The dynamic operation of the HOG pathway has been well studied, and similar osmosensing pathways exist in other eukaryotes. Protein kinase A, which seems to mediate a response to diverse stress conditions, is also involved in the transcriptional response program. Expression changes after a shift to high osmolarity aim at adjusting metabolism and the production of cellular protectants. Accumulation of the osmolyte glycerol, which is also controlled by altering transmembrane glycerol transport, is of central importance. Upon a shift from high to low osmolarity, yeast cells stimulate a different MAP kinase cascade, the cell integrity pathway. The transcriptional program upon hypo-osmotic shock seems to aim at adjusting cell surface properties. Rapid export of glycerol is an important event in adaptation to low osmolarity. Osmoadaptation, adjustment of cell surface properties, and the control of cell morphogenesis, growth, and proliferation are highly coordinated processes. The Skn7p response regulator may be involved in coordinating these events. An integrated understanding of osmoadaptation requires not only knowledge of the function of many uncharacterized genes but also further insight into the time line of events, their interdependence, their dynamics, and their spatial organization as well as the importance of subtle effects

Integrative model of the response of yeast to osmotic shock

“…Even individual cells in multicellular organisms respond to osmotic changes, and strategies of cellular adaptation are conserved from bacteria to human 1 . The yeast Saccharomyces cerevisiae is a suitable model system to study osmoregulation and a substantial amount of information is available on osmotic shockinduced signal transduction, control of gene expression and accumulation of osmolytes 2 .…”

“…Central to yeast osmotic adaptation is the high osmolarity glycerol (HOG) signaling system 2,3 (Fig. 1).…”

Genome‐wide screen of Saccharomyces cerevisiae for killer toxin HM‐1 resistance

“…Fps1p participates in the efflux of glycerol to regulate the intracellular glycerol level together with glycerol production enzymes, which are stimulated by mitogen-activated protein kinase (MAPK) Hog1p and the HOG pathway (Hohmann, 2002;Luyten et al, 1995;Tamas et al, 1999). Fps1p is phosphorylated by Hog1p MAPK and is degraded in vacuoles under acetate stress; lack of Fps1p further activates the CWI pathway MAPK Slt2p (Beese et al, 2009;Davenport et al, 1995;Mollapour and Piper, 2007;Mollapour et al, 2009;Philips and Herskowitz, 1997;Tamas et al, 1999;Tong and Boone, 2006).…”

Information processing in the adaptation of Saccharomyces cerevisiae to osmotic stress: an analysis of the phosphorelay system

“…The cellular response of S. cerevisiae to osmotic stress from the environment has been and is still widely studied in Systems Biology (Posas et al 1996;Hohmann 2002;Schaber et al 2012;Baltanás et al 2013). This is partly due to the interesting motifs involved (MAPK cascade, crosstalk to other pathways, feedback mechanisms, etc.…”

“…Posas et al 1996;Hohmann 2002;Macia et al 2009;Patterson et al 2010) as well as a computational side (e.g. Klipp et al 2005;Muzzey and Ca 2009;Petelenz-Kurdziel et al 2013;Patel et al 2013).…”