Metabolomic, proteomic and biophysical analyses of  Arabidopsis thaliana cells exposed to a caesium stress. Influence of potassium supply

• Published in: Biochimie 2006-11, Vol.88 (11), p.1533-1547
• Main Authors: Le Lay, P., Isaure, M.-P., Sarry, J.-E., Kuhn, L., Fayard, B., Le Bail, J.-L., Bastien, O., Garin, J., Roby, C., Bourguignon, J.
• Format: Article
• Language: English
• Subjects: 2D gel electrophoresis; Arabidopsis - drug effects; Arabidopsis - growth & development; Arabidopsis - metabolism; Arabidopsis thaliana; Biochemistry, Molecular Biology; Caesium toxicity; Cell Division - drug effects; Cesium - pharmacokinetics; Cesium - toxicity; Cesium Radioisotopes - pharmacokinetics; Cesium Radioisotopes - toxicity; Chlorophyll - metabolism; Kinetics; Life Sciences; Magnetic Resonance Spectroscopy; mass spectrometry; metabolic NMR; Potassium - pharmacology; potassium depletion; Proteome; proteomics; synchrotron X-ray fluorescence microscopy
• ISSN: 0300-9084; 1638-6183
• DOI: 10.1016/j.biochi.2006.03.013

The incorporation and localisation of 133Cs in a plant cellular model and the metabolic response induced were analysed as a function of external K concentration using a multidisciplinary approach. Sucrose-fed photosynthetic Arabidopsis thaliana suspension cells, grown in a K-containing or K-depleted medium, were submitted to a 1 mM Cs stress. Cell growth, strongly diminished in absence of K, was not influenced by Cs. In contrast, the chlorophyll content, affected by a Cs stress superposed to K depletion, did not vary under the sole K depletion. The uptake of Cs was monitored in vivo using 133Cs NMR spectroscopy while the final K and Cs concentrations were determined using atomic absorption spectrometry. Cs absorption rate and final concentration increased in a K-depleted external medium; in vivo NMR revealed that intracellular Cs was distributed in two kinds of compartment. Synchrotron X-ray fluorescence microscopy indicated that one could be the chloroplasts. In parallel, the cellular response to the Cs stress was analysed using proteomic and metabolic profiling. Proteins up- and down-regulated in response to Cs, in presence of K + or not, were analysed by 2D gel electrophoresis and identified by mass spectrometry. No salient feature was detected excepting the overexpression of antioxidant enzymes, a common response of Arabidopsis cells stressed whether by Cs or by K-depletion. 13C and 31P NMR analysis of acid extracts showed that the metabolome impact of the Cs stress was also a function of the K nutrition. These analyses suggested that sugar metabolism and glycolytic fluxes were affected in a way depending upon the medium content in K +. Metabolic flux measurements using 13C labelling would be an elegant way to pursue on this line. Using our experimental system, a progressively stronger Cs stress might point out other specific responses elicited by Cs.