Proteome-scale study of copper-associated proteins of Aegilops tauschii

Copper (Cu), although required in trace amounts, is necessary for fundamental processes in plants, including photosynthesis, signalling, cell wall formation, and oxidative stress management. The current study presents a comprehensive, high-throughput bioinformatic characterisation of Copper-Associated Proteins (CAPs) in Aegilops tauschii (DD), the diploid D genome donor of bread wheat. The proteome of Ae. tauschii was investigated, and 62 copper-binding proteins (CBPs) and 32 copper transport proteins (CTPs) were shortlisted. Among these proteins, 10 were found to be common and thus predicted to perform dual functions. These proteins were shown to be rich in CHED amino acid residues, with histidine and cysteine being the most abundant in their binding pockets, suggesting their important roles in catalytic and redox activities. The proteins were found to belong mostly to the peptidase M1 family, the Plant serine/threonine kinase family, the copper amine oxidase superfamily, the multicopper oxidases, the laccases and the transferrin receptor proteins. The Gene Ontology study revealed their roles in copper ion binding (GO-MF), cellular and metabolic processes (GO-BP), and integral membrane and organelle components (GO-CC). Most of the proteins were predicted to be predominantly localised in the chloroplast (22.79%), the cell membrane (20.59%), and the cytoplasm (13.97%), suggesting roles in plant physiological and metabolic processes. KEGG and Reactome pathway-based studies also validated their involvement in plant responses to biotic and abiotic stress, revealing a cascade of signalling pathways. This report highlights the diverse roles of CAPs in plant physiology and could serve as potential markers for crop improvement programs.