STABILITY AND REFRACTORINESS OF THE HIGH CATALASE ACTIVITY IN THE OXIDATIVE-STRESS-RESISTANT FISSION YEAST SCHIZOSACCHAROMYCES-POMBE

Effect of oxygen and metabolic substrates (glucose, ethanol) on the ca talase activity of anaerobically grown Schizosaccharomyces pombe cells was assessed and compared with that of Saccharomyces cerevisiae in or der to determine the catalase activity regulation in S. pombe. In cont rast to S. cerevisiae, the total catalase activity of permeabilized S. pombe anaerobically grown cells is higher than that found in aerobica lly grown cells, is stable and constant under all circumstances (i.e. it is not induced by oxygen and/or substrates), and only a negligible part (3-5 %) of it is contributed by de novo protein synthesis during aeration with or without substrates. The patent catalase activity of i ntact cells rises 2-fold during 6-h aeration without substrate and 7-8 -fold in the presence of glucose or ethanol. The increase is not inhib ited by cycloheximide and is thus not due to de novo catalase synthesi s, but may reflect enhanced transport of catalase to the cell surface or a permeabilization of the plasma membrane during the aeration.