Identification of nickel-binding proteins in plants
Identification des protéines liant le nickel chez les plantes
Résumé
Nickel (Ni) is an essential micronutrient for most organisms. This cofactor plays a key role in maintaining protein structure, electron transfer functions, and catalytic reactions1. While several Ni-containing proteins have been reported in prokaryotes1, only a few proteins have been associated with Ni homeostasis in plants. The best characterised example is for the Ni metalloenzyme urease and its maturation factors2. Given that Ni is an essential micronutrient for plant and that some plant species can accumulate high concentrations of the metal when grown in Ni-rich soils, we hypothesize that additional Ni-binding proteins may exist. These proteins remain to be identified in plants, as well as most of molecular actors involved in the uptake, transport, and storage of this metallic element. Here, we developed a metalloproteomic approach aiming at identifying target proteins of Ni using Arabidopsis thaliana and the Ni-hyperaccumulator Noccaea caerulescens. First, the root and shoot soluble proteomes of plants grown hydroponically in the presence of Ni was fractionated using ion-exchange chromatography. Then, potential Ni-binding proteins were retained by affinity capture and the Ni content was determined by ICP-MS. My preliminary results demonstrate that Ni was associated with several chromatographic fractions, suggesting that several pools of proteins may bind Ni in vivo. The next step in this work will be to identify these potential Ni-binding proteins by tandem mass spectrometry. This identification process is an essential step towards a better understanding of the role of Ni in essential cellular processes and deciphering the molecular basis of Ni accumulation in plants.