TY - JOUR A1 - Nukarinen, Ella A1 - Nägele, Thomas A1 - Pedrotti, Lorenzo A1 - Wurzinger, Bernhard A1 - Mair, Andrea A1 - Landgraf, Ramona A1 - Börnke, Frederik A1 - Hanson, Johannes A1 - Teige, Markus A1 - Baena-Gonzalez, Elena A1 - Dröge-Laser, Wolfgang A1 - Weckwerth, Wolfram T1 - Quantitative phosphoproteomics reveals the role of the AMPK plant ortholog SnRK1 as a metabolic master regulator under energy deprivation JF - Scientific reports N2 - 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. Y1 - 2016 U6 - https://doi.org/10.1038/srep31697 SN - 2045-2322 VL - 6 SP - 10248 EP - 10252 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Üstün, Suayib A1 - Sheikh, Arsheed A1 - Gimenez-Ibanez, Selena A1 - Jones, Alexandra A1 - Ntoukakis, Vardis A1 - Börnke, Frederik T1 - The Proteasome Acts as a Hub for Plant Immunity and Is Targeted by Pseudomonas Type III Effectors JF - Plant physiology : an international journal devoted to physiology, biochemistry, cellular and molecular biology, biophysics and environmental biology of plants N2 - Recent evidence suggests that the ubiquitin-proteasome system is involved in several aspects of plant immunity and that a range of plant pathogens subvert the ubiquitin-proteasome system to enhance their virulence. Here, we show that proteasome activity is strongly induced during basal defense in Arabidopsis (Arabidopsis thaliana). Mutant lines of the proteasome subunits RPT2a and RPN12a support increased bacterial growth of virulent Pseudomonas syringae pv tomato DC3000 (Pst) and Pseudomonas syringae pv maculicola ES4326. Both proteasome subunits are required for pathogen-associated molecular pattern-triggered immunity responses. Analysis of bacterial growth after a secondary infection of systemic leaves revealed that the establishment of systemic acquired resistance (SAR) is impaired in proteasome mutants, suggesting that the proteasome also plays an important role in defense priming and SAR. In addition, we show that Pst inhibits proteasome activity in a type III secretion-dependent manner. A screen for type III effector proteins from Pst for their ability to interfere with proteasome activity revealed HopM1, HopAO1, HopA1, and HopG1 as putative proteasome inhibitors. Biochemical characterization of HopM1 by mass spectrometry indicates that HopM1 interacts with several E3 ubiquitin ligases and proteasome subunits. This supports the hypothesis that HopM1 associates with the proteasome, leading to its inhibition. Thus, the proteasome is an essential component of pathogen-associated molecular pattern-triggered immunity and SAR, which is targeted by multiple bacterial effectors. Y1 - 2016 U6 - https://doi.org/10.1104/pp.16.00808 SN - 0032-0889 SN - 1532-2548 VL - 172 SP - 1941 EP - 1958 PB - American Society of Plant Physiologists CY - Rockville ER -