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

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• 作者：Moreira dos Santos ; Margarida ; Thygesen ; Gerda ; Kö ; tter ; Peter ; Olsson ; Lisbeth ; Nielsen ; Jens
• 关键词：Saccharomyces cerevisiae ; Redox metabolism ; Ammonium assimilation ; Critical dilution rate ; Productostat ; Glutathione reductase ; Glutamate dehydrogenase ; Metabolic engineering
• 刊名：FEMS Yeast Research
• 出版年：2003
• 出版时间：October, 2003
• 年：2003
• 卷：4
• 期：1
• 页码：59-68
• 全文大小：318 K

文摘

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.PK113-7D, 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.