Quantitative phosphoproteomics reveals the role of the AMPK plant ortholog SnRK1 as a metabolic master regulator under energy deprivation

Ella Nukarinen, Thomas Nägele, Lorenzo Pedrotti, Bernhard Wurzinger, Andrea Mair, Ramona Landgraf, Frederik Boernke, Johannes Hanson, Markus Teige, Elena Baena-Gonzalez, Wolfgang Droege-Laser, Wolfram Weckwerth

Since years, research on SnRK1, the major cellular energy sensor in plants, has tried to define its role in energy signalling. However, these attempts were notoriously hampered by the lethality of a complete knockout of SnRK1. Therefore, we generated an inducible amiRNA:: SnRK1 alpha 2 in a snrk1 alpha 1 knock out background (snrk1 alpha 1/alpha 2) to abolish SnRK1 activity to understand major systemic functions of SnRK1 signalling under energy deprivation triggered by extended night treatment. We analysed the in vivo phosphoproteome, proteome and metabolome and found that activation of SnRK1 is essential for repression of high energy demanding cell processes such as protein synthesis. The most abundant effect was the constitutively high phosphorylation of ribosomal protein S6 (RPS6) in the snrk1 alpha 1/alpha 2 mutant. RPS6 is a major target of TOR signalling and its phosphorylation correlates with translation. Further evidence for an antagonistic SnRK1 and TOR crosstalk comparable to the animal system was demonstrated by the in vivo interaction of SnRK1 alpha 1 and RAPTOR1B in the cytosol and by phosphorylation of RAPTOR1B by SnRK1 alpha 1 in kinase assays. Moreover, changed levels of phosphorylation states of several chloroplastic proteins in the snrk1 alpha 1/alpha 2 mutant indicated an unexpected link to regulation of photosynthesis, the main energy source in plants.

Research Platform Vienna Metabolomics Center, Large-Instrument Facility for Mass Spectrometry in Life Sciences
External organisation(s)
Julius-Maximilians-Universität Würzburg, Universität Potsdam, Swedish University of Agricultural Sciences (SLU), Instituto Gulbenkian de Ciência, Leibniz-Institut für Gemüse- und Zierpflanzenbau Großbeeren/Erfurt e. V.
Scientific Reports
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Publication date
Peer reviewed
Austrian Fields of Science 2012
106037 Proteomics
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