Mitochondrial respiration is required to provide amino acids during fermentative proliferation of fission yeast

Abstract

When glucose is available, many organisms repress mitochondrial respiration in favour of aerobic glycolysis, or fermentation in yeast, that suffices for ATP production. Fission yeast cells, however, rely partially on respiration for rapid proliferation under fermentative conditions. Here, we determined the limiting factors that require respiratory function during fermentation. When inhibiting the electron transport chain, supplementation with arginine was necessary and sufficient to restore rapid proliferation. Accordingly, a systematic screen for mutants growing poorly without arginine identified mutants defective in mitochondrial oxidative metabolism. Genetic or pharmacological inhibition of respiration triggered a drop in intracellular levels of arginine and amino acids derived from the Krebs cycle metabolite alpha‐ketoglutarate: glutamine, lysine and glutamic acid. Conversion of arginine into these amino acids was required for rapid proliferation when blocking the respiratory chain. The respiratory block triggered an immediate gene expression response diagnostic of TOR inhibition, which was muted by arginine supplementation or without the AMPK‐activating kinase Ssp1. The TOR‐controlled proteins featured biased composition of amino acids reflecting their shortage after respiratory inhibition. We conclude that respiration supports rapid proliferation in fermenting fission yeast cells by boosting the supply of Krebs cycle‐derived amino acids.

Amino Acids Whose Intracellular Levels Change Most During Aging Alter Chronological Life Span of Fission Yeast

“…We determined absolute concentrations of intracellular amino acids in nmol/6 × 10 7 cells ( Supplementary Table 1 ). The amino acid quantities, obtained from nondividing cells, differed from those previously reported for fission yeast which have been obtained from rapidly proliferating cells ( 20 , 24 ). At the onset of stationary phase, the total amino acid concentrations were lower in pka1Δ than in wild-type cells ( Figure 1B ).…”

Identification of Quinone Degradation as a Triggering Event for Intense Pulsed Light-Elicited Metabolic Changes in Escherichia coli by Metabolomic Fingerprinting

“…In fact, glutamate is the most abundant free amino acid in E. coli [ 37 ]. The studies on eukaryotic cells have shown that rapid decreases of intracellular amino acids, especially glutamate, occurred when the ETC was inhibited [ 38 , 39 ]. Glutamate catabolism was mainly catalyzed by aspartate transaminase (AST), which converts glutamate to α-ketoglutarate (AKG) via transamination with oxaloacetate, producing aspartate [ 40 ].…”

Multiple nutritional phenotypes of fission yeast mutants defective in genes encoding essential mitochondrial proteins

“…Thus, all isolated mutants may lose mitotic competence during G0 phase, or alternatively, may lose the capacity to exit from G0 phase upon replenishment of nitrogen. It is not surprising that mitochondria become essential under nitrogen starvation, as amino acid metabolism is quite active in mitochondria and mitochondrial respiration is important for synthesis of certain amino acids, such as arginine [ 11 ]. However, since none of the defective genes examined in this study are directly related to nutrient recycling, and since during nitrogen-depleted G0 phase, amino acid levels are thought to be maintained by recycling rather than synthesis, further studies are required to understand the mechanisms underlying the nutritional phenotypes.…”

“…Even in the presence of a respiratory poison (antimycin A), S. pombe cells can grow and divide at a reduced rate, if glucose concentrations are higher than 0.2% [ 11 , 12 ]. Respiratory activity thus appears to be optional for cell proliferation under conditions in which an adequate concentration of glucose is present, while it is important for synthesis of amino acids derived from the Krebs cycle metabolite α-ketoglutarate [ 11 ].…”

“…The fission yeast Schizosaccharomyces pombe belongs to a group of 'petite negative' yeasts, in which mitochondrial DNA is essential for viability, in contrast to the 'petite positive' budding yeast Saccharomyces cerevisiae, which can survive without mitochondrial DNA [7][8][9][10]. Even in the presence of a respiratory poison (antimycin A), S. pombe cells can grow and divide at a reduced rate, if glucose concentrations are higher than 0.2% [11,12]. Respiratory activity thus appears to be optional for cell proliferation under conditions in which an adequate concentration of glucose is present, while it is important for synthesis of amino acids derived from the Krebs cycle metabolite α-ketoglutarate [11].…”