Yeast Trk1 Potassium Transporter Gradually Changes Its Affinity in Response to Both External and Internal Signals
Yeasts need a high intracellular concentration of potassium to grow. The main K<sup>+</sup> uptake system in <i>Saccharomyces cerevisiae</i> is the Trk1 transporter, a complex protein with four MPM helical membrane motifs. Trk1 has been shown to exist in low- or high-affinity...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-04-01
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| Series: | Journal of Fungi |
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| Online Access: | https://www.mdpi.com/2309-608X/8/5/432 |
| _version_ | 1797498726335381504 |
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| author | Jakub Masaryk Hana Sychrová |
| author_facet | Jakub Masaryk Hana Sychrová |
| author_sort | Jakub Masaryk |
| collection | DOAJ |
| description | Yeasts need a high intracellular concentration of potassium to grow. The main K<sup>+</sup> uptake system in <i>Saccharomyces cerevisiae</i> is the Trk1 transporter, a complex protein with four MPM helical membrane motifs. Trk1 has been shown to exist in low- or high-affinity modes, which reflect the availability of potassium in the environment. However, when and how the affinity changes, and whether the potassium availability is the only signal for the affinity switch, remains unknown. Here, we characterize the Trk1 kinetic parameters under various conditions and find that Trk1’s K<sub>T</sub> and V<sub>max</sub> change gradually. This gliding adjustment is rapid and precisely reflects the changes in the intracellular potassium content and membrane potential. A detailed characterization of the specific mutations in the P-helices of the MPM segments reveals that the presence of proline in the P-helix of the second and third MPM domain (F820P and L949P) does not affect the function of Trk1 in general, but rather specifically prevents the transporter’s transition to a high-affinity state. The analogous mutations in the two remaining MPM domains (L81P and L1115P) result in a mislocalized and inactive protein, highlighting the importance of the first and fourth P-helices in proper Trk1 folding and activity at the plasma membrane. |
| first_indexed | 2024-03-10T03:37:28Z |
| format | Article |
| id | doaj.art-4a34ae49b637486e93f2263b21d12dd2 |
| institution | Directory Open Access Journal |
| issn | 2309-608X |
| language | English |
| last_indexed | 2024-03-10T03:37:28Z |
| publishDate | 2022-04-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Journal of Fungi |
| spelling | doaj.art-4a34ae49b637486e93f2263b21d12dd22023-11-23T11:40:58ZengMDPI AGJournal of Fungi2309-608X2022-04-018543210.3390/jof8050432Yeast Trk1 Potassium Transporter Gradually Changes Its Affinity in Response to Both External and Internal SignalsJakub Masaryk0Hana Sychrová1Laboratory of Membrane Transport, Institute of Physiology, Czech Academy of Sciences, 142 20 Prague, Czech RepublicLaboratory of Membrane Transport, Institute of Physiology, Czech Academy of Sciences, 142 20 Prague, Czech RepublicYeasts need a high intracellular concentration of potassium to grow. The main K<sup>+</sup> uptake system in <i>Saccharomyces cerevisiae</i> is the Trk1 transporter, a complex protein with four MPM helical membrane motifs. Trk1 has been shown to exist in low- or high-affinity modes, which reflect the availability of potassium in the environment. However, when and how the affinity changes, and whether the potassium availability is the only signal for the affinity switch, remains unknown. Here, we characterize the Trk1 kinetic parameters under various conditions and find that Trk1’s K<sub>T</sub> and V<sub>max</sub> change gradually. This gliding adjustment is rapid and precisely reflects the changes in the intracellular potassium content and membrane potential. A detailed characterization of the specific mutations in the P-helices of the MPM segments reveals that the presence of proline in the P-helix of the second and third MPM domain (F820P and L949P) does not affect the function of Trk1 in general, but rather specifically prevents the transporter’s transition to a high-affinity state. The analogous mutations in the two remaining MPM domains (L81P and L1115P) result in a mislocalized and inactive protein, highlighting the importance of the first and fourth P-helices in proper Trk1 folding and activity at the plasma membrane.https://www.mdpi.com/2309-608X/8/5/432cation homeostasis<i>Saccharomyces cerevisiae</i>potassium uptakemembrane potential |
| spellingShingle | Jakub Masaryk Hana Sychrová Yeast Trk1 Potassium Transporter Gradually Changes Its Affinity in Response to Both External and Internal Signals Journal of Fungi cation homeostasis <i>Saccharomyces cerevisiae</i> potassium uptake membrane potential |
| title | Yeast Trk1 Potassium Transporter Gradually Changes Its Affinity in Response to Both External and Internal Signals |
| title_full | Yeast Trk1 Potassium Transporter Gradually Changes Its Affinity in Response to Both External and Internal Signals |
| title_fullStr | Yeast Trk1 Potassium Transporter Gradually Changes Its Affinity in Response to Both External and Internal Signals |
| title_full_unstemmed | Yeast Trk1 Potassium Transporter Gradually Changes Its Affinity in Response to Both External and Internal Signals |
| title_short | Yeast Trk1 Potassium Transporter Gradually Changes Its Affinity in Response to Both External and Internal Signals |
| title_sort | yeast trk1 potassium transporter gradually changes its affinity in response to both external and internal signals |
| topic | cation homeostasis <i>Saccharomyces cerevisiae</i> potassium uptake membrane potential |
| url | https://www.mdpi.com/2309-608X/8/5/432 |
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