Proteomic analysis of the ila2 mutant of Arabidopsis links translational regulation with photosynthesis, protein folding and ribosomal proteins

A key component of the conserved GCN (General Control Non-repressive) signalling pathway in plants is the ILITHYIA(ILA) protein, homologous to the yeast GCN1 protein. Similar to yeast and animals, ILA seems to be involved in the activation of the eIF2 alpha kinase GCN2, allowing protein arrest under stress conditions. Recently, it has been reported that, in plants, ILA could be also playing a role in development independent of GCN2. To gain insight into this new function of the ILA protein, we have performed proteomic analysis to identify differentially-expressed proteins in the strong loss-of-function allele of ILA (ila2). ila2 plants present a reduced expression of photosynthetic proteins, and an increased expression of the translational initiation factor eiF5A, ribosomal proteins and heat-shock proteins. These results open new hypothesis to understand the roles of this important translational regulator in plant tissues.