Cloning, Expression and Functional Characterization of V. vinifera CAT2 Arginine Transporter

The amino acid membrane transporters of grape species take part in metabolic pathways that play crucial roles in nitrogen trafficking and in the synthesis of secondary metabolites. Therefore, identifying these amino acid transporters and defining their functional properties might have further applications in crop improvement and, hence, relevance to human nutrition. The <i>VvCAT2</i> (Cation Amino acid Transporter) transporter cDNA has been isolated and cloned into a specific plasmid for over-expression in <i>Escherichia coli</i>. The expressed protein, after purification by Ni²⁺-chelating chromatography, has been functionally characterized in an experimental model of proteoliposomes by measuring the uptake of radiolabeled compounds. Arginine was revealed to be the best substrate, confirming the role of CAT2 in nitrogen trafficking in plant cells and within sub-cellular spaces, given its plausible localization in vacuoles. The transporter activity is modulated by pH, osmotic imbalance and ATP. The transport kinetics have been measured. Overall, the obtained data indicate the capacity of <i>Vv</i>CAT2 in transporting arginine, making it a possible target for crop improvement with a relevance to human health.