Research ArticleCell Biology

MAPK feedback encodes a switch and timer for tunable stress adaptation in yeast

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Science Signaling  13 Jan 2015:
Vol. 8, Issue 359, pp. ra5
DOI: 10.1126/scisignal.2005774

One Pathway: Both a Switch and a Rheostat

Signaling pathways can mediate responses that are on or off, like a light switch, or can mediate responses that are graded, like a dimmer switch. English et al. explored the yeast response to osmotic stress, which is mediated by a mitogen-activated protein kinase cascade involving the kinase Hog1. Using a new method for quantifying the abundance of phosphorylated Hog1, which requires dual phosphorylation for activation, this kinase exhibited switchlike activation and then produced a graded duration of activity that reflected the intensity of the osmotic stress. Positive and negative feedback from Hog1 produced these dual behaviors. Genetic analysis indicated that several upstream components of the pathway contributed to the profile of Hog1 activity. Analysis of transcriptional and translational profiles of yeast exposed to persistent osmotic stress showed that the initial response triggered adaptive changes that enabled cell survival and later transcriptional changes enabled the cells to recover.