Asymmetry in inward- and outward-affinity constant of transport explain unidirectional lysine flux in Saccharomyces cerevisiae
| Autor: | Katja Luck, Tjeerd Pols, Joury S van 't Klooster, Stephanie J Ruiz, Bert Poolman, Ina L. Urbatsch, Frans Bianchi |
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| Přispěvatelé: | Enzymology |
| Rok vydání: | 2016 |
| Předmět: |
0301 basic medicine
Saccharomyces cerevisiae Proteins Saccharomyces cerevisiae Biological Transport Active SUBSTRATE-BINDING Vacuole Biology Models Biological Michaelis–Menten kinetics Article ACTIVE-TRANSPORT 03 medical and health sciences 0302 clinical medicine MOLECULAR-BASIS MASTER REGULATOR YEAST Ion transporter GENE-EXPRESSION chemistry.chemical_classification Multidisciplinary Chemiosmosis Lysine biology.organism_classification Amino acid AMINO-ACID Kinetics 030104 developmental biology RECONSTITUTION Renal disorders Radboud Institute for Molecular Life Sciences [Radboudumc 11] Biochemistry chemistry ESCHERICHIA-COLI Amino Acid Transport Systems Basic Efflux 030217 neurology & neurosurgery Lysine transport MEMBRANE-VESICLES |
| Zdroj: | Scientific Reports, 6 Scientific Reports, 6:31443, 1-13. Nature Publishing Group Scientific Reports |
| ISSN: | 2045-2322 |
| Popis: | The import of basic amino acids in Saccharomyces cerevisiae has been reported to be unidirectional, which is not typical of how secondary transporters work. Since studies of energy coupling and transport kinetics are complicated in vivo, we purified the major lysine transporter (Lyp1) of yeast and reconstituted the protein into lipid vesicles. We show that the Michaelis constant (KM) of transport from out-to-in is well in the millimolar range and at least 3 to 4-orders of magnitude higher than that of transport in the opposite direction, disfavoring the efflux of solute via Lyp1. We also find that at low values of the proton motive force, the transport by Lyp1 is comparatively slow. We benchmarked the properties of eukaryotic Lyp1 to that of the prokaryotic homologue LysP and find that LysP has a similar KM for transport from in-to-out and out-to-in, consistent with rapid influx and efflux. We thus explain the previously described unidirectional nature of lysine transport in S. cerevisiae by the extraordinary kinetics of Lyp1 and provide a mechanism and rationale for previous observations. The high asymmetry in transport together with secondary storage in the vacuole allow the cell to accumulate basic amino acids to very high levels. |
| Databáze: | OpenAIRE |
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