MAINTENANCE OF THE PEROXISOMAL COMPARTMENT IN GLUCOSE-REPRESSED AND ANAEROBICALLY GROWN SACCHAROMYCES-CEREVISIAE CELLS

According to the current model of peroxisome biogenesis, the inheritan ce of this compartment requires the growth and division of pre-existin g organelles followed by their distribution between mother and daughte r cells. However, no known peroxisomal functions are present nor requi red for Saccharomyces cerevisiae cells grown under glucose repression and in anaerobiosis and the peroxisomal compartment becomes virtually indistinguishable under such conditions. This raised the question of t he fate of this compartment in such cells. Is it maintained throughout prolonged growth under glucose repression or does it disappear from t he cell and then reassemble on demand? To study the maintenance of put atively functional peroxisomes in S. cerevisiae cells grown under cond itions of glucose repression and anaerobiosis, we applied the vector-m ediated overexpression of peroxisome matrix enzyme's catalase A and ac yl-CoA oxidase. Evidence is presented that in S cerevisiae the peroxis omal import machinery responsible for targeting of matrix enzymes into this compartment is preserved under glucose repression and in the abs ence of oxygen.