EXPRESSION OF PEP CARBOXYLASE FROM ESCHERICHIA-COLI COMPLEMENTS THE PHENOTYPIC EFFECTS OF PYRUVATE-CARBOXYLASE MUTATIONS IN SACCHAROMYCES-CEREVISIAE

We investigated the effects of the expression of the Escherichia coli ppc gene encoding PEP carboxylase in Saccharomyces cerevisiae mutants devoid of pyruvate carboxylase, Functional expression of the ppc gene restored the ability of the yeast mutants to grow in glucose-ammonium medium, Growth yield in this medium was the same in the transformed ye ast than in the wild type although the growth rate of the transformed yeast was slower. Growth in pyruvate was slowed down in the transforme d strain, likely due to a futile cycle produced by the simultaneous ac tion of PEP carboxykinase and PEP carboxylase. (C) 1997 Federation of European Biochemical Societies.