PYRUVATE METABOLISM IN SACCHAROMYCES-CEREVISIAE

In yeasts, pyruvate is located at a major junction of assimilatory and dissimilatory reactions as well as at the branch-point between respir atory dissimilation of sugars and alcoholic fermentation. This review deals with the enzymology, physiological function and regulation of th ree key reactions occurring at the pyruvate branch-point in the yeast Saccharomyces cerevisiae: (i) the direct oxidative decarboxylation of pyruvate to acetyl-CoA, catalysed by the pyruvate dehydrogenase comple x, (ii) decarboxylation of pyruvate to acetaldehyde, catalysed by pyru vate decarboxylase, and (iii) the anaplerotic carboxylation of pyruvat e to oxaloacetate, catalysed by pyruvate carboxylase. Special attentio n is devoted to physiological studies on S. cerevisiae strains in whic h structural genes encoding these key enzymes have been inactivated by gene disruption.