Please note that we have stopped the regular imports of Gene Expression Omnibus (GEO) data into ArrayExpress. This may not be the latest version of this experiment.
E-GEOD-6277 - Transcription profiling of S. cerevisiae reveaks increasing nadh oxidation reduces overflow metabolism
Submitted on 14 November 2006, released on 14 June 2008, last updated on 27 March 2012
When the yeast Saccharomyces cerevisiae is subjected to increasing glycolytic fluxes under aerobic conditions, there is a threshold value of the glucose uptake rate at which the metabolism shifts from being purely respiratory to mixed respiratory and fermentative. This shift is characterized by ethanol production, a phenomenon known as the Crabtree effect due to its analogy with lactate overflow in cancer cells. It is well known that at high glycolytic fluxes there is glucose repression of respiratory pathways resulting in a decrease in the respiratory capacity. Despite many years of detailed studies on this subject, it is not known whether the onset of the Crabtree effect (or overflow metabolism) is due to a limited respiratory capacity or caused by glucose-mediated repression of respiration. We addressed this issue by increasing respiration in S. cerevisiae by introducing a heterologous alternative oxidase, and observed reduced aerobic ethanol formation. In contrast, increasing non-respiratory NADH oxidation by overexpression of a water-forming NADH oxidase reduced aerobic glycerol formation. The metabolic response to elevated alternative oxidase occurred predominantly in the mitochondria, while NADH oxidase affected genes that catalyze cytosolic reactions. Moreover, NADH oxidase restored the deficiency of cytosolic NADH dehydrogenases in S. cerevisiae. These results indicate that NADH oxidase localizes in the cytosol, while alternative oxidase is directed to the mitochondria. The onset of aerobic ethanol formation is demonstrated to be a consequence of an imbalance in mitochondrial redox balancing. In addition to answering fundamental physiological questions, our findings are relevant for all biomass derived applications of S. cerevisiae. Experiment Overall Design: Heterologous gene expression in chemostats using Affymetrix Yeast Genome 2.0 arrays. Total RNA extraction and sample preparation, hybridization was done according to the manufacturer's protocol.
transcription profiling by array, unknown experiment type
Increasing NADH oxidation reduces overflow metabolism in Saccharomyces cerevisiae. G N Vemuri, M A Eiteman, J E McEwen, L Olsson, J Nielsen. Proc Natl Acad Sci U S A 104(7):2402-7 (2007)