Effect of killer toxin K1 on yeast membrane potential reported by the diS-C3(3) probe reflects strain-and physiological state-dependent variations |
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Authors: | M Eminger D Gá?ková B Brodská A Holoubek N Stadler K Sigler |
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Institution: | (1) Institute of Physics, Charles University, 121 16 Prague, Czech Republic;(2) Institute of Microbiology, Academy of Sciences of the Czech Republic, 142 20 Prague, Czech Republic;(3) Institute of Botany, University of Bonn, 53115 Bonn, Germany |
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Abstract: | The rate and extent of uptake of the fluorescent probe diS-C3(3) reporting on membrane potential inS. cerevisiae is affected by the strain under study, cell-growth phase, starvation and by the concentration of glucose both in the growth
medium and in the monitored cell suspension under non-growth conditions. Killer toxin K1 brings about changes in membrane
potential. In all types of cells tested,viz. in glucose-supplied stationary or exponential cells of the killer-sensitive strain S6/1 or a conventional strain RXII, or
in glucose-free exponential cells of both strains, both active and heat-inactivated toxin slow down the potential-dependent
uptake of diS-C3(3) into the cells. This may reflect “clogging” of pores in the cell wall that hinders, but does not prevent, probe passage
to the plasma membrane and its equilibration. The clogging effect of heat-inactivated toxin is stronger than that exerted
by active toxin. In susceptible cells,i.e. in exponential-phase glucose-supplied cells of the sensitive strain S6/1, this phase of probe uptake retardation is followed
by an irreversible red shift in probe fluorescence maximumλ
max indicating damage to membrane integrity and cell permeabilization. A similar fast red shift inλ
max signifying lethal cell damage was found in heat-killed or nystatin-treated cells. |
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