Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Null trk1 trk2 mutants of Saccharomyces cerevisiae exhibit a low-affinity uptake of K+ and Rb+. We show that this low-affinity Rb+ uptake is mediated by several independent transporters, and that trk1Delta cells and especially trk1Delta trk2Delta cells are highly hyperpolarized. Differences in the membrane potentials were assessed for sensitivity to hygromycin B and by flow cytometric analyses of cellular DiOC6(3) fluorescence. On the basis of the latter analyses, it is proposed that Trk1p and Trk2p are involved in the control of the membrane potential, preventing excessive hyperpolarizations. K+ starvation and nitrogen starvation hyperpolarize both TRK1 TRK2 and trk1Delta trk2Delta cells, thus suggesting that other proteins, in addition to Trk1p and Trk2p, participate in the control of the membrane potential. The HAK1 K+ transporter from Schwanniomyces occidentalis suppresses the K+-defective transport of trk1Delta trk2Delta cells but not the high hyperpolarization, and the HKT1 K+ transporter from wheat suppresses both defects, in the presence of Na+. We discuss the mechanism involved in the control of the membrane potential by Trk1p and Trk2p and the causal relationship between the high membrane potential (negative inside) of trk1Delta trk2Delta cells and its ectopic transport of alkali cations.
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PMID:Ectopic potassium uptake in trk1 trk2 mutants of Saccharomyces cerevisiae correlates with a highly hyperpolarized membrane potential. 961 85

Saccharomyces cerevisiae wild-type (BY4741) and the corresponding mutant lacking the plasma membrane main potassium uptake systems (trk1,trk2) were used to analyze the consequences of K(+) starvation following a proteomic approach. In order to trigger high-affinity mode of potassium transport, cells were transferred to potassium-free medium. Protein profile was followed by two-dimensional (2-D) gels in samples taken at 0, 30, 60, 120, 180, and 300 min during starvation. We observed a general decrease of protein content during starvation that was especially drastic in the mutant strain as it was the case of an important number of proteins involved in glycolysis. On the contrary, we identified proteins related to stress response and alternative energetic metabolism that remained clearly present. Neural network-based analysis indicated that wild type was able to adapt much faster than the mutant to the stress process. We conclude that complete potassium starvation is a stressful process for yeast cells, especially for potassium transport mutants, and we propose that less stressing conditions should be used in order to study potassium homeostasis in yeast.
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PMID:Adaptation to potassium starvation of wild-type and K(+)-transport mutant (trk1,2) of Saccharomyces cerevisiae: 2-dimensional gel electrophoresis-based proteomic approach. 2295 24