Redox engineering by ectopic expression of glutamate dehydrogenase genes links NADPH availability and NADH oxidation with cold growth in Saccharomyces cerevisiae.

摘要: Background: Cold stress reduces microbial growth and metabolism being relevant in industrial processes like wine making brewing. Knowledge on the cold transcriptional response of Saccharomyces cerevisiae suggests need a proper redox balance. Nevertheless, there are no direct evidence links between NAD(P) levels how engineering enzymatic reactions requiring may be used to modify performance strains at low temperature. Results: Recombinant S. modified for increased NADPH ‑ NADH‑dependent Gdh1 Gdh2 activity were tested A high‑copy number GDH2‑encoded glutamate dehydro‑ genase gene stimulated 15°C, while overexpression GDH1 had detrimental effects, difference likely caused by cofactor preferences. Indeed, neither Trp − character strains, which could affect syn‑ thesis NAD(P), nor changes oxidative susceptibility GDH2 account observed phenotypes. However, or reduced availability knock‑out GRE3, NADPH‑dependent aldose reductase gene, eliminated exacerbated cold‑growth defect YEpGDH1 cells. We also demonstrated that decreased capacity glycerol production impairs 15 but not 30°C 15°C‑grown baker’s yeast cells display higher fermentative than those cultivated 30°C. Thus, increasing NADH oxidation would help avoid perturbations induced fermentative/oxidative balance Finally, it is shown increases notably strain QA23 both standard medium synthetic grape must. Conclusions: Redox constraints limit temperatures below optimal. An adequate supply precursors as well level reducing equivalents form required growth. major limitation NAD + In this scenario, our results identify ammonium assimilation pathway target genetic improvement strains.