| Budget Amount *help |
¥17,550,000 (Direct Cost: ¥13,500,000、Indirect Cost: ¥4,050,000)
Fiscal Year 2018: ¥5,070,000 (Direct Cost: ¥3,900,000、Indirect Cost: ¥1,170,000)
Fiscal Year 2017: ¥5,720,000 (Direct Cost: ¥4,400,000、Indirect Cost: ¥1,320,000)
Fiscal Year 2016: ¥6,760,000 (Direct Cost: ¥5,200,000、Indirect Cost: ¥1,560,000)
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| Outline of Final Research Achievements |
The MAP kinase (MAPK) Hog1 is the central regulator of osmoadaptation in yeast. Upon high osmolarity, the Sho1 and Sln1 membrane-associated osmosensors, respectively, activate the Ste11-Pbs2-Hog1 MAPK cascade and the Ssk2/Ssk22-Pbs2-Hog1 MAPK cascade. Sho1 binds to several transmembrane proteins such as Opy2 to form an osmo-sensing protein complex for transduction of an activating signal. In this work, we identified two binding sites between Sho1 and Opy2, and found that the Sho1-Opy2 interaction enhances the signaling efficiency from Ste11 MAPKKK to Pbs2 MAPKK. In addition, we found that the Hog1 MAPK phosphorylation by Pbs2 MAPKK is enhanced by high osmolarity independently of the membrane-associated osmosensors. 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, which enable the yeast cells to respond appropriately to environmental stresses.
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