Sodium and lithium exert differential effects on the central carbon metabolism of Debaryomyces hansenii through the glyoxylate shunt regulation

Francisco S. Ruiz-Pérez, Francisco J. Ruiz-Castilla, Carlos Leal, José L Martínez, José Ramos*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

Debaryomyces hansenii is a halotolerant/halophilic yeast usually found in salty environments. The yeast accumulated sodium at high concentrations, which improved growth in salty media. In contrast, lithium was toxic even at low concentrations and its presence prevented cell proliferation. To analyse the responses to both cations, metabolite levels, enzymatic activities and gene expression were determined, showing that NaCl and LiCl trigger different cellular responses. At high concentrations of NaCl (0.5 or 1.5 M) cells accumulated higher amounts of the intermediate metabolites glyoxylate and malate and, at the same time, the levels of intracellular oxoglutarate decreased. Additionally, 0.5 M NaCl increased the activity of the enzymes isocitrate lyase and malate synthase involved in the synthesis of glyoxylate and malate respectively and decreased the activity of isocitrate dehydrogenase. Moreover, transcription of the genes coding for isocitrate lyase and malate synthase was activated by NaCl. Also, cells accumulated phosphate upon NaCl exposure. None of these effects was provoked when LiCl (0.1 or 0.3 M) was used instead of NaCl. Lithium induced accumulation of higher amounts of oxoglutarate and decreased the concentrations of glyoxylate and malate to non-detectable levels. Cells incubated with lithium also showed higher activity of the isocitrate dehydrogenase and neither increased isocitrate lyase and malate synthase activities nor the transcription of the corresponding genes. In summary, we show that sodium, but not lithium, up regulates the shunt of the glyoxylic acid in D. hansenii and we propose that this is an important metabolic adaptation to thrive in salty environments.
Original languageEnglish
JournalYeast
Volume40
Issue number7
Pages (from-to)265-275
Number of pages11
ISSN0749-503X
DOIs
Publication statusPublished - 2023

Keywords

  • Glyoxylate shunt
  • Lithium
  • Salt tolerance
  • Sodium
  • Stress
  • Yeast

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