Pyruvate decarboxylase: An indispensable enzyme for growth of Saccharomyces cerevisiae on glucose

Abstract

In Saccharomyces cerevisiae, the structural genes PDC1, PDC5 and PDC6 each encode an active pyruvate decarboxylase. Replacement mutations in these genes were introduced in a homothallic wild‐type strain, using the dominant marker genes APT1 and Tn5ble. A pyruvate‐decarboxylase‐negative (Pdc−) mutant lacking all three PDC genes exhibited a three‐fold lower growth rate in complex medium with glucose than the isogenic wild‐type strain. Growth in batch cultures on complex and defined media with ethanol was not impaired in Pdc− strains. Furthermore, in ethanol‐limited chemostat cultures, the biomass yield of Pdc− and wild‐type S. cerevisiae were identical. However, Pdc− S. cerevisiae was unable to grow in batch cultures on a defined mineral medium with glucose as the sole carbon source. When aerobic, ethanol‐limited chemostat cultures (D = 0·10 h−1) were switched to a feed containing glucose as the sole carbon source, growth ceased after approximately 4 h and, consequently, the cultures washed out. The mutant was, however, able to grow in chemostat cultures on mixtures of glucose and small amounts of ethanol or acetate (5% on a carbon basis). No growth was observed when such cultures were used to inoculate batch cultures on glucose. Furthermore, when the mixed‐substrate cultures were switched to a feed containing glucose as the sole carbon source, wash‐out occurred. It is concluded that the mitochondrial pyruvate dehydrogenase complex cannot function as the sole source of acetyl‐CoA during growth of S. cerevisiae on glucose, neither in batch cultures nor in glucose‐limited chemostat cultures.

Cytosolic re-localization and optimization of valine synthesis and catabolism enables increased isobutanol production with the yeast Saccharomyces cerevisiae

“…This, however, would create new problems as pdc - mutants are known to become auxotrophic for cytosolic acetyl-CoA which is needed for e.g. lipid synthesis [44]. Moreover, whereas in glycolysis NADH is produced as a reduced cofactor, Ilv5 in the isobutanol pathway exclusively uses NADPH.…”

Reconstruction of cytosolic fumaric acid biosynthetic pathways in Saccharomyces cerevisiae

“…This goal can be achieved by disrupting or weakening the specific enzymes, such as pyruvate decarboxylase and alcohol dehydrogenase [8,24], or by manipulating the available concentration of thiamine that is required by pyruvate decarboxylase [25]. Meanwhile, increasing the direct oxidation of NADH, either by enhancing respiration via improvements in the dissolved oxygen content or by overexpressing an alternative oxidase [23], is also an effective approach to reduce ethanol production.…”

Engineered Trx2p industrial yeast strain protects glycolysis and fermentation proteins from oxidative carbonylation during biomass propagation

“…Dehydrated cells were inoculated (10 7 cells/mL) in YPGF and incubated at 30°C and 65 rpm for 5 h. Samples were collected at the end of incubation, and cell extracts were prepared using glass beads and assayed as described in the following references: alcohol dehydrogenase [54], enolase [55], pyruvate decarboxylase [56] and catalase [57]. …”