Aerobic physiology of redox-engineered Saccharomyces cerevisiae strains modified in the ammonium assimilation for increased NADPH availability

Maria Margarida M. dos Santos, G. Thygesen, P. Kotter, Lisbeth Olsson, Jens Nielsen

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    Recombinant strains altered in the ammonium assimilation pathways were constructed with the purpose of increasing NADPH availability. The NADPH-dependent glutamate dehydrogenase encoded by GDH1, which accounts for a major fraction of the NADPH consumption during growth on ammonium, was deleted, and alternative pathways for ammonium assimilation were overexpressed: GDH2 (NADH-consuming) or GLN1 and GLT1 (the GS-GOGAT system). The flux through the pentose phosphate pathway during aerobic growth on glucose decreased to about half that of the reference strain Saccharomyces cerevisiae CEN.KK113-7D, indicating a major redox alteration in the strains. The basic growth characteristics of the recombinant strains were not affected to a great extent, but the dilution rate at which the onset of aerobic fermentation occurred decreased, suggesting a relation between the onset of the Crabtree effect and the flux through the Embden-Meyerhof-Parnas pathway downstream of glucose 6-phosphate. No redox effect was observed in a strain containing a deletion of GLR1, encoding glutathione reductase, an enzyme that is NADPH-consuming.
    Original languageEnglish
    JournalFEMS Yeast Research
    Volume4
    Issue number1
    Pages (from-to)59-68
    ISSN1567-1356
    Publication statusPublished - 2003

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