Impact of the growth phase on the activity of multidrug resistance pumps and membrane potential of S. cerevisiae: effect of pump overproduction and carbon source.
The potentiometric fluorescence probe diS-C3(3) is expelled from S. cerevisiae by ABC pumps Pdr5 and Snq2 and can conveniently be used for studying their performance. The activity of these pumps in a strain with wild-type PDR1 allele was shown to drop sharply on glucose depletion from the medium and then again at the end of the diauxic shift when the cells are adapted to growth on respiratory substrates. The presence of the PDR1-3 allele causing pump overproduction prevented this second drop and the pump activity typical for diauxic cells was largely retained. Growth phase-dependent changes of membrane potential measured by the same probe in pump-free mutants included a Deltapsi drop in the late exponential and diauxic growth phase, indicating lowered activity of H+ -ATPase. Suppression of activity of both ABC pumps and H+ -ATPase obviously signifies cell transition to an energy-saving mode. Challenging respiration-adapted cells with glucose showed a novel feature of yeast ABC pumps--a strong dependence of pump activity on the type of the carbon source.
Institute of Physics, Charles University, Ke Karlovu 5, 12116 Prague 2, Czech Republic.
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R
Cadek
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K
Chládková
K
K
Sigler
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D
Gásková
D018528:ATP-Binding Cassette Transporters / Q000378:metabolism*; D002244:Carbon; D003470:Culture Media / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000378:metabolism; D004352:Drug Resistance, Microbial; D004734:Energy Metabolism; D005947:Glucose / Q000494:pharmacology; D008564:Membrane Potentials; D006180:Proton-Translocating ATPases / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000254:growth & development* / Q000378:metabolism / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors
D018528:ATP-Binding Cassette Transporters; D003470:Culture Media; D004268:DNA-Binding Proteins; C085480:PDR1 protein, S cerevisiae; C092438:PDR5 protein, S cerevisiae; C101797:SNQ2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C097077:YOR1 protein, S cerevisiae; D002244:Carbon; D006180:Proton-Translocating ATPases; D005947:Glucose