期刊
EMBO JOURNAL
卷 39, 期 5, 页码 -出版社
WILEY
DOI: 10.15252/embj.2019103444
关键词
HOG pathway; Hog1; MAP kinase; osmostress; signal transduction
资金
- JSPS [16H04761, 25440042, 16H06578, 17H06017, 19K06548, 17K15083, 24247034]
- Sumitomo Foundation [150075]
- Salt Science Research Foundation [1732]
- Japan Foundation for Applied Enzymology
- Mochida Memorial Foundation for Medical and Pharmaceutical Research
- Graduate Program for Leaders in Life Innovation from MEXT
- Grants-in-Aid for Scientific Research [16H04761, 17K15083, 17H06017, 25440042, 16H06578, 19K06548] Funding Source: KAKEN
The MAP kinase (MAPK) Hog1 is the central regulator of osmoadaptation in yeast. When cells are exposed to high osmolarity, the functionally redundant Sho1 and Sln1 osmosensors, respectively, activate the Ste11-Pbs2-Hog1 MAPK cascade and the Ssk2/Ssk22-Pbs2-Hog1 MAPK cascade. In a canonical MAPK cascade, a MAPK kinase kinase (MAP3K) activates a MAPK kinase (MAP2K) by phosphorylating two conserved Ser/Thr residues in the activation loop. Here, we report that the MAP3K Ste11 phosphorylates only one activating phosphorylation site (Thr-518) in Pbs2, whereas the MAP3Ks Ssk2/Ssk22 can phosphorylate both Ser-514 and Thr-518 under optimal osmostress conditions. Mono-phosphorylated Pbs2 cannot phosphorylate Hog1 unless the reaction between Pbs2 and Hog1 is enhanced by osmostress. The lack of the osmotic enhancement of the Pbs2-Hog1 reaction suppresses Hog1 activation by basal MAP3K activities and prevents pheromone-to-Hog1 crosstalk in the absence of osmostress. We also report that the rapid-and-transient Hog1 activation kinetics at mildly high osmolarities and the slow and prolonged activation kinetics at severely high osmolarities are both caused by a common feedback mechanism.
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