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Updated: Aug 8, 2026
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Peptide-derived Method to Transport Genes and Proteins Across Cellular and Organellar Barriers in Plants
Published on: December 16, 2016
Proton-Peptide Co-Transport in Broad Bean Leaf Tissues
A. Jamai1, J. F. Chollet, S. Delrot
1Laboratoire de Physiologie et Biochimie Vegetales (A.J., S.D.), and Laboratoire de Synthese Organique et Organometallique (J.-F.C.), Unite Associee Centre National de la Recherche Scientifique 574, Universite de Poitiers, 25 Rue du Faubourg Saint-Cyprien, 86000 Poitiers, France.
Plant Physiology
|November 1, 1994
Summary
Researchers identified a proton-coupled peptide transporter in broad bean leaves. This transporter facilitates the uptake of dipeptides like glycyl-glycine (Gly-Gly) into mesophyll cells, suggesting a role in nitrogen transport.
Area of Science:
- Plant Physiology
- Molecular Transport
- Biochemistry
Background:
- Understanding nutrient transport in plants is crucial for optimizing crop yield and nitrogen utilization.
- Peptide transport systems in plant tissues, particularly in mature exporting leaves, are not fully elucidated.
- Glycyl-glycine (Gly-Gly) serves as a model dipeptide to investigate peptide uptake mechanisms.
Purpose of the Study:
- To characterize the transport mechanism of glycyl-glycine (Gly-Gly) in broad bean (Vicia faba L.) leaf discs.
- To identify the cellular localization and kinetic properties of the Gly-Gly transporter.
- To investigate the electrophysiological effects and substrate specificity of the identified transporter.
Main Methods:
- Uptake assays using radiolabeled [14C]glycyl-glycine ([14C]Gly-Gly) in broad bean leaf discs.
- pH measurements and metabolic inhibitor sensitivity tests to determine transport characteristics.
- Electrophysiological measurements (transmembrane potential) and competition assays with various peptides.
Main Results:
- Gly-Gly uptake occurred primarily in mesophyll cells, with kinetics indicating a saturable phase (apparent Michaelis constant of 16 mM).
- Transport was optimal at pH 6.0, sensitive to thiol reagents and metabolic inhibitors, and coupled with proton co-transport.
- Various di- and tripeptides inhibited Gly-Gly uptake, demonstrating broad substrate specificity, while glycine showed minimal inhibition.
Conclusions:
- Evidence supports the existence of a low-affinity, broad-specificity H+/peptide co-transporter in the plasma membrane of mesophyll cells.
- This transporter plays a potential role in the exchange of nitrogenous compounds within mature plant leaves.
- Further research is needed to determine the physiological significance and detailed electrophysiological mechanisms of this transporter.
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