Impact of overexpressing NADH kinase on glucose and xylose metabolism in recombinant xylose-utilizing <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> |
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Authors: | Jin Hou Goutham N Vemuri Xiaoming Bao Lisbeth Olsson |
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Institution: | 1.Center for Microbial Biotechnology,Technical University of Denmark,Lyngby,Denmark;2.The State Key Laboratory of Microbial Technology, The College of Life Science,Shandong University,Jinan,People’s Republic of China;3.Industrial Biotechnology, Department of Chemical and Biological Engineering,Chalmers University of Technology,Gothenburg,Sweden;4.Systems Biology, Department of Chemical and Biological Engineering,Chalmers University of Technology,Gothenburg,Sweden |
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Abstract: | During growth of Saccharomyces cerevisiae on glucose, the redox cofactors NADH and NADPH are predominantly involved in catabolism and biosynthesis, respectively. A
deviation from the optimal level of these cofactors often results in major changes in the substrate uptake and biomass formation.
However, the metabolism of xylose by recombinant S. cerevisiae carrying xylose reductase and xylitol dehydrogenase from the fungal pathway requires both NADH and NADPH and creates cofactor
imbalance during growth on xylose. As one possible solution to overcoming this imbalance, the effect of overexpressing the
native NADH kinase (encoded by the POS5 gene) in xylose-consuming recombinant S. cerevisiae directed either into the cytosol or to the mitochondria was evaluated. The physiology of the NADH kinase containing strains
was also evaluated during growth on glucose. Overexpressing NADH kinase in the cytosol redirected carbon flow from CO2 to ethanol during aerobic growth on glucose and to ethanol and acetate during anaerobic growth on glucose. However, cytosolic
NADH kinase has an opposite effect during anaerobic metabolism of xylose consumption by channeling carbon flow from ethanol
to xylitol. In contrast, overexpressing NADH kinase in the mitochondria did not affect the physiology to a large extent. Overall,
although NADH kinase did not increase the rate of xylose consumption, we believe that it can provide an important source of
NADPH in yeast, which can be useful for metabolic engineering strategies where the redox fluxes are manipulated. |
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Keywords: | NADH kinase POS5 Saccharomyces cerevisiae NADPH Xylose |
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