Temporal system‐level organization of the switch from glycolytic to gluconeogenic operation in yeast

“…1). At high glucose levels, yeast primarily ferments carbon via the PDH bypass rather than oxidize it via mitochondrial respiration, a well-documented phenomenon known as the Crabtree Effect (Zampar et al, 2013). Branching from central carbon metabolism, our reconstruction shows the metabolic route to our product: some of the acetaldehyde is converted to acetate, then acetyl-CoA, malonyl-CoA, and lastly fatty acyl-CoA and derived chemicals.…”

Section: Microscopymentioning

confidence: 99%

Engineering high-level production of fatty alcohols by Saccharomyces cerevisiae from lignocellulosic feedstocks

d’Espaux

Ghosh

Runguphan

et al. 2017

Metabolic Engineering

105

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A B S T R A C TFatty alcohols in the C12-C18 range are used in personal care products, lubricants, and potentially biofuels. These compounds can be produced from the fatty acid pathway by a fatty acid reductase (FAR), yet yields from the preferred industrial host Saccharomyces cerevisiae remain under 2% of the theoretical maximum from glucose. Here we improved titer and yield of fatty alcohols using an approach involving quantitative analysis of protein levels and metabolic flux, engineering enzyme level and localization, pull-push-block engineering of carbon flux, and cofactor balancing. We compared four heterologous FARs, finding highest activity and endoplasmic reticulum localization from a Mus musculus FAR. After screening an additional twenty-one single-gene edits, we identified increasing FAR expression; deleting competing reactions encoded by DGA1, HFD1, and ADH6; overexpressing a mutant acetyl-CoA carboxylase; limiting NADPH and carbon usage by the glutamate dehydrogenase encoded by GDH1; and overexpressing the Δ9-desaturase encoded by OLE1 as successful strategies to improve titer. Our final strain produced 1.2 g/L fatty alcohols in shake flasks, and 6.0 g/L in fed-batch fermentation, corresponding to~20% of the maximum theoretical yield from glucose, the highest titers and yields reported to date in S. cerevisiae. We further demonstrate high-level production from lignocellulosic feedstocks derived from ionic-liquid treated switchgrass and sorghum, reaching 0.7 g/L in shake flasks. Altogether, our work represents progress towards efficient and renewable microbial production of fatty acidderived products.

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“…In the presence of glucose, the cells operate in glycolytic mode and synthesize ethanol, whereas upon depletion of glucose, they use the alternate glucose sources by switching to gluconeogenesis. This wide-spread phenomenon termed the diauxic shift and is marked by the activation of the glyoxylate cycle (Zampar et al, 2013), and is under control of the cAMP repressor protein (Shimizu, 2013). Specific enzymes for this pathway have been shown to be upregulated in the stressed environment of biofilms in Cryptococcus neoformans (Santi et al, 2014).…”

Section: Figmentioning

confidence: 99%

A Network Biology Approach to Decipher Stress Response in Bacteria UsingEscherichia coliAs a Model

Nagar

Aggarwal

Joon

et al. 2016

OMICS: A Journal of Integrative Biology

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The development of drug-resistant pathogenic bacteria poses challenges to global health for their treatment and control. In this context, stress response enables bacterial populations to survive extreme perturbations in the environment but remains poorly understood. Specific modules are activated for unique stressors with few recognized global regulators. The phenomenon of cross-stress protection strongly suggests the presence of central proteins that control the diverse stress responses. In this work, Escherichia coli was used to model the bacterial stress response. A Protein-Protein Interaction Network was generated by integrating differentially expressed genes in eight stress conditions of pH, temperature, and antibiotics with relevant gene ontology terms. Topological analysis identified 24 central proteins. The well-documented role of 16 central proteins in stress indicates central control of the response, while the remaining eight proteins may have a novel role in stress response. Cluster analysis of the generated network implicated RNA binding, flagellar assembly, ABC transporters, and DNA repair as important processes during response to stress. Pathway analysis showed crosstalk of Two Component Systems with metabolic processes, oxidative phosphorylation, and ABC transporters. The results were further validated by analysis of an independent cross-stress protection dataset. This study also reports on the ways in which bacterial stress response can progress to biofilm formation. In conclusion, we suggest that drug targets or pathways disrupting bacterial stress responses can potentially be exploited to combat antibiotic tolerance and multidrug resistance in the future.

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Temporal system‐level organization of the switch from glycolytic to gluconeogenic operation in yeast

Abstract: Metabolome, proteome and physiology measurements were combined with mathematical modeling to unravel the temporal regulation of the metabolic fluxes during the diauxic shift in Saccharomyces cerevisiae.

Cited by 116 publications

References 62 publications

Regulation of Lactobacillus plantarum contamination on the carbohydrate and energy related metabolisms of Saccharomyces cerevisiae during bioethanol fermentation

Regulation of Lactobacillus plantarum contamination on the carbohydrate and energy related metabolisms of Saccharomyces cerevisiae during bioethanol fermentation

Engineering high-level production of fatty alcohols by Saccharomyces cerevisiae from lignocellulosic feedstocks

A Network Biology Approach to Decipher Stress Response in Bacteria UsingEscherichia coliAs a Model

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