Utilization of malate or aspartate by a yeast lacking malate enzyme

Summary Hansenula anomala, a yeast lacking malate enzyme, was able to grow in media containing malate or aspartate as sole carbon and energy sources. Both aspartate--ketoglutarate transaminase and pyruvate kinase activities changed their levels when the yeast was grown on different carbon sources. Pyruvate kinase activity was increased by fructose 1,6-diphosphate.These results indicate that in this yeast malate enzyme is not indispensable for the formation of pyruvate from malate or aspartate and that C₄ dicarboxylic acids may provide pyruvate through the combined action of phosphoenolpyruvate carboxykinase and pyruvate kinase. It is also concluded that aspartate--ketoglutarate transaminase and pyruvate kinase are under regulatory control in Hansenula anomala.