Propionate metabolism in Saccharomyces cerevisiae: implications for the metabolon hypothesis

Microbiology. 1994 Apr;140 ( Pt 4):717-22. doi: 10.1099/00221287-140-4-717.

Abstract

Aerobic, glucose-limited chemostat of Saccharomyces cerevisiae CBS 8066 co-metabolized propionate when this compound was added to the reservoir medium. Co-metabolism of propionate led to an increase of the biomass and protein yields. Attempts to grow S. cerevisiae on propionate as a sole source of carbon and energy were not successful. Activities of propionyl-CoA synthetase in cell-free extracts were sufficient to account for the rates of propionate consumption observed in the chemostat cultures. Activities of propionyl-CoA carboxylase, a key enzyme of the methylmalonyl-CoA pathway of propionate metabolism, were negligible. In contrast, activities of 2-methylcitrate synthase, a key enzyme activity of the 2-methylcitrate pathway of propionate metabolism, increased substantially with increasing propionate-to-glucose ratios in the reservoir media, and were sufficient to account for the propionate consumption rates observed in the chemostat cultures. This suggested that the 2-methylcitrate pathway is the major pathway of propionate metabolism in S. cerevisiae. In the literature, labelling patterns observed after incubation of this yeast with [3-13C]propionate have been interpreted as evidence for channelling of tricarboxylic acid (TCA) cycle intermediates, possibly as a consequence of the organization of TCA cycle enzymes in a metabolon. However, this interpretation of 13C-labelling patterns rested on the assumption that propionate metabolism in S. cerevisiae occurs via the methylmalonyl-CoA pathway. Since the distribution of 13C in alanine reported in the literature is fully compatible with a major role of the 2-methylcitrate pathway in propionate metabolism, it cannot be interpreted as evidence for the existence of a TCA cycle metabolon in S. cerevisiae.

MeSH terms

  • Acetate-CoA Ligase / metabolism
  • Carboxy-Lyases / metabolism
  • Citrates / metabolism
  • Energy Metabolism
  • Fungal Proteins / metabolism
  • Methylmalonyl-CoA Decarboxylase
  • Models, Biological*
  • Propionates / metabolism*
  • Saccharomyces cerevisiae / metabolism*

Substances

  • Citrates
  • Fungal Proteins
  • Propionates
  • 2-methylcitric acid
  • Carboxy-Lyases
  • Acetate-CoA Ligase
  • Methylmalonyl-CoA Decarboxylase
  • propionic acid