The regulation of phosphoenolpyruvate carboxykinase and the NADP-linked malic enzyme in Aspergillus nidulans

It has previously been suggested that the synthesis of phosphoenolpyruvate carboxykinase (EC 4.1.1.32)in A. nidulans is regulated by a repression-derepression mechanism involving a glycolytic intermediate, and not by induction. Results obtained using compounds that enter the tricarboxylic acid cycle via 2-oxoglutarate, and that can supply both a carbon and a nitrogen source for A. nidulans, suggest it is more likely that the synthesis of phosphoenolpyruvate carboxykinase is inducible, and only weakly regulated by carbon catabolite repression. A similar study of the regulation of the NADP-linked malic enzyme (EC 1.1.1.40)indicates that it too may be inducible.