Characterisation of protein dual targeting to energy organelles in Arabidopsis thaliana

[Truncated abstract] Eukaryotic cells are defined by their containment of membrane bound compartments, termed organelles. The majority of proteins found within a particular organelle are encoded by genes in the nucleus, synthesised in the cytosol, and subsequently targeted to specific organelles. The traditional view of biology is that one gene gives rise to one protein, targeted to one location. However, in the past 15 years an increasing number of proteins have been found to be localised in more than one organelle, a phenomenon called dual targeting. In the model plant Arabidopsis thaliana, only a limited number of proteins have been identified to date as being dual targeted. The work carried out in studies I, II and III aimed to identify new dual targeted proteins in Arabidopsis. A list of candidate dual targeted proteins was defined by cross-referencing a number of publically available subcellular localisation datasets, generated by large scale proteomic studies. In addition, candidate genes were also identified by computational predictions, based on the protein amino acid sequences. A selection of proteins were then selected for targeting analysis by in vivo green fluorescent protein (GFP) tagging, results were then confirmed by either in vitro import assays or Western blot analysis. In this way, studies I, II, and III led to the identification of 12 new dual targeted proteins in Arabidopsis.