Interaction of the neutral amino acid transporter ASCT2 with basic amino acids
| Autor: | Avner Schlessinger, Elias Ndaru, Christof Grewer, Rachel-Ann A. Garibsingh, Laura Zielewicz |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Amino Acid Transport System ASC
Stereochemistry Lysine Protonation Biochemistry Article Glutamine transport Substrate Specificity Serine Minor Histocompatibility Antigens 03 medical and health sciences 0302 clinical medicine Animals Humans Binding site Enzyme Inhibitors Molecular Biology 030304 developmental biology chemistry.chemical_classification Alanine 0303 health sciences Binding Sites Amino Acids Basic Aminobutyrates Cell Biology Amino acid Rats Molecular Docking Simulation Kinetics HEK293 Cells chemistry 030220 oncology & carcinogenesis Cysteine Protein Binding |
| Zdroj: | Biochem J |
| ISSN: | 1470-8728 |
| Popis: | Glutamine transport across cell membranes is performed by a variety of transporters, including the alanine serine cysteine transporter 2 (ASCT2). The substrate-binding site of ASCT2 was proposed to be specific for small amino acids with neutral side chains, excluding basic substrates such as lysine. A series of competitive inhibitors of ASCT2 with low µM affinity were developed previously, on the basis of the 2,4-diaminobutyric acid (DAB) scaffold with a potential positive charge in the side chain. Therefore, we tested whether basic amino acids with side chains shorter than lysine can interact with the ASCT2 binding site. Molecular docking of L-1,3-diaminopropionic acid (L-DAP) and L-DAB suggested that these compounds bind to ASCT2. Consistent with this prediction, L-DAP and L-DAB, but not ornithine, lysine or D-DAP, elicited currents when applied to ASCT2-expressing cells. The currents were carried by anions and showed the hallmark properties of ASCT2 currents induced by transported substrates. The L-DAP response could be eliminated by a competitive ASCT2 inhibitor, suggesting that binding occurs at the substrate binding site. The KM for L-DAP was weakly voltage dependent. Furthermore, the pH dependence of the L-DAP response showed that the compound can bind in several protonation states. Together, these results suggest that the ASCT2 binding site is able to recognize L-amino acids with short, basic side chains, such as the L-DAP derivative β-N-methylamino-l-Alanine (BMAA), a well-studied neurotoxin. Our results expand the substrate specificity of ASCT2 to include amino acid substrates with positively charged side chains. |
| Databáze: | OpenAIRE |
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