Activity of yeast multidrug resistance pumps during growth is controlled by carbon source and the composition of growth-depleted medium: DiS-C3(3) fluorescence assay.
Like other tested wild-type strains (DTXII and IL-125-2B), exponential glucose- and/or fructose-grown cells of Saccharomyces cerevisiae BY4742 exhibit the previously described high activity of Pdr5p and Snq2p pumps (measured as export of the potentiometric fluorescent probe diS-C3(3)). Upon saccharide depletion from the medium the pump activity in these cells, which differ from other strains in having a lower membrane potential, sharply drops to a very low level similar to that found in cells grown on ethanol or glycerol. This negligible pump activity in respiring cells thus appears to have a universal character. Addition of glucose or fructose to respiring BY4742 cells grown to low culture densities restores multidrug resistance pump activity due partly to pump synthesis in pre-existing cells and partly to the high pump activity of newly grown cells; no such pump activity boost occurs when the sugar is added to high-density cultures of ethanol-grown or post-diauxic glucose-grown cells, even if these cultures are diluted to low density by their original growth-depleted medium. A strong sugar-induced increase in pump activity is found solely if respiring cells from high-density cultures are resuspended in fresh YPD or YPE medium before sugar addition. Its absence in respiring cells suspended in growth-depleted medium reflects an as yet unidentified effect of the composition of the growth-exhausted medium (depletion of some components and/or accumulation of extracellular metabolites during yeast growth) on sugar-induced pump activity rise.
Malác
J
J
Charles University, Faculty of Mathematics and Physics, Institute of Physics, Ke Karlovu 5, 12116 Prague 2, Czech Republic.
Urbánková
E
E
Sigler
K
K
Gásková
D
D
D018528:ATP-Binding Cassette Transporters / Q000502:physiology*; D002232:Carbocyanines / Q000494:pharmacology*; D003470:Culture Media; D026141:Drug Resistance, Multiple, Fungal / Q000502:physiology*; D005632:Fructose / Q000494:pharmacology*; D005947:Glucose / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000254:growth & development* / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000502:physiology*
C091791:3,3'-dipropylthiacarbocyanine; D018528:ATP-Binding Cassette Transporters; D002232:Carbocyanines; D003470:Culture Media; C092438:PDR5 protein, S cerevisiae; C101797:SNQ2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D005632:Fructose; D005947:Glucose