Response of catalase activity and membrane fluidity of aerobically grown Schizosaccharomyces pombe and Saccharomyces cerevisiae to aeration and, the presence of substrates

Abstract

Intracellular catalase (EC 1.11.1.6) activity of permeabilized aerobically grown cells of Schizosaccharomyces pombe was insensitive to cell aeration and inhibition of protein synthesis, and was only mildly enhanced by the presence of glucose and ethanol via de novo protein synthesis. By contrast, the intracellular catalase activity of Saccharomyces cerevisiae, which, in freshly harvested cells, was two to three times lower than that in Sch. pombe, increased on aeration without substrates or with ethanol and was inhibited on aeration with glucose following cell permeabilization. The enhanced intracellular activity was due to de novo protein synthesis while the inhibitory effect of glucose, absent in Sch. pombe, was caused by one of the major glucose metabolites, succinate. The intactcell catalase activity of both yeasts increased greatly during aeration. In Sacch. cerevisiae, this increase was again prevented by glucose. In parallel, export of catalase to the cell surface increased in both yeasts. This was especially conspicuous in Sch. pombe aerated in the presence of ethanol, and may represent a protective mechanism against the damaging effects of ethanol. The cell-surface-bound catalase activity was confirmed in isolated plasma membranes of both yeasts. The fluidity of the plasma membrane increased during aeration. This effect was further stimulated by the presence of glucose and to a lesser extent by ethanol. Both yeasts exhibited increased extracellular catalase activity during aeration which could not be caused entirely by cell lysis. In Sch. pombe this activity was strongly enhanced by the presence of ethanol.

Assessment of Membrane Fluidity in Individual Yeast Cells by Laurdan Generalised Polarisation and Multi-photon Scanning Fluorescence Microscopy

“…On the other hand, we believe that rather than fluidization, heat damage to membrane proteins impacts on membrane function. The latter theory is supported by data from a number of studies [6][7][8]. It is thought that heat responses are triggered by damaged cytosolic proteins, although membrane proteins may be more vulnerable since heat damage may involve oxygen-derived free radicals, which partition into membranes [9].…”

Induction of lipid peroxidation during heavy metal stress in Saccharomyces cerevisiae and influence of plasma membrane fatty acid unsaturation

“…Plasma membrane lipid order was determined by measuring steady-state fluorescence anisotropy in whole cells labeled with trimethylammonium diphenylhexatriene (TMA-DPH). The cationic probe TMA-DPH becomes anchored primarily at the plasma membrane of intact cells (7,17). TMA-DPH was added to S. cerevisiae cell suspensions (5 ϫ 10 7 cells ml Ϫ1 ; see above) from a 1 mM stock solution, prepared in concentrated dimethylformamide, to give a final concentration of 1 M. After 30 min of equilibration, when measurements had stabilized, Cd(NO 3 ) 2 was added to the cell suspensions.…”

“…TMA-DPH was excited with vertically polarized light at 360 nm, and the vertical and horizontal vectors of emitted light were measured at 450 nm. Membrane order was expressed as the order parameter S, which reflects the orderliness of membrane phospholipids: S ϭ (r/r 0 ) 0.5 (17), where r 0 is the theoretical limiting anisotropy (0.395 for TMA-DPH) in the absence of rotational motion and r is the steady-state anisotropy measured in the membrane. The effects of Cd 2ϩ on membrane order were determined by measuring S at intervals over 60 min.…”

Variations of two pools of glycogen and carbohydrate in Saccharomyces cerevisiae grown with various ethanol concentrations

“…-ATPase, resulting in increased membrane permeability of yeast [22]. Ethanol concentration above a threshold value of 4-6% (v/v) is responsible for induction of heat-shock proteins in yeast [23] and also affects membrane lipids by causing fluidization of plasma membrane as well as by increasing proportion of ergosterol [24]. In the present study an attempt was made to determine whether the level of insoluble glycogen varies in response to stress conditions created by ethanol.…”