Genome-wide analysis of cytosolic and chloroplastic isoforms of glutathione reductase in plant cells

In recent years regarding the climate change and subsequent environmental stresses, there has been an increasing interest in finding and characterizing of new antioxidant enzymes. Glutathione reductase (GR) is an antioxidant enzyme with central role in maintaining the reduced glutathione pool during stress. So far, however, there has been little discussion on genome-wide analysis of this enzyme. In this study, different computational biology approaches (EST analysis, feature selection, and evolutionary analysis) were exploited to identify the key protein properties influencing on cytosolic and chloroplastic isoforms of glutathione reductase in plants. A specific targeting signal peptide was found in chloroplastic isoforms, while cytosolic isoforms carry a cytosolic domain. This domain may affect the biochemical properties of different GR isoforms. Moreover, specific its functionl motifs were discovered in cytosolic and chloroplastic isoforms implying a link between subcellular localization of GR and functional. Phylogenetic analysis of GR nucleotide and protein sequences showed that diversification of this gene family could be dated back to the early stage of plant evolution, possibly by duplication event before the divergence of monocot and dicot. A high degree of gene structure conservation of localized isoforms in the same subcellular compartment also reflects this process providing an evidence for a close relationship among proteins located in the same subcellular compartment. Study of glutathione reductase expression by EST analysis highlighted cytosolic isoforms as the main isoforrm responding to stress condition.