scholarly journals Simulating Extracellular Glucose Signals Enhances Xylose Metabolism in Recombinant Saccharomyces cerevisiae

2020 ◽  
Vol 8 (1) ◽  
pp. 100 ◽  
Author(s):  
Meiling Wu ◽  
Hongxing Li ◽  
Shan Wei ◽  
Hongyu Wu ◽  
Xianwei Wu ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Metabolic Networks ◽  
Glucose Sensing ◽  
Biofuel Production ◽  
Xylose Utilization ◽  
High Concentration ◽  
Xylose Metabolism ◽  
Camp Phosphodiesterase ◽  
Xylose Consumption ◽  
Recombinant Saccharomyces Cerevisiae

Efficient utilization of both glucose and xylose from lignocellulosic biomass would be economically beneficial for biofuel production. Recombinant Saccharomyces cerevisiae strains with essential genes and metabolic networks for xylose metabolism can ferment xylose; however, the efficiency of xylose fermentation is much lower than that of glucose, the preferred carbon source of yeast. Implications from our previous work suggest that activation of the glucose sensing system may benefit xylose metabolism. Here, we show that deleting cAMP phosphodiesterase genes PDE1 and PDE2 increased PKA activity of strains, and consequently, increased xylose utilization. Compared to the wild type strain, the specific xylose consumption rate (rxylose) of the pde1Δ pde2Δ mutant strains increased by 50%; the specific ethanol-producing rate (rethanol) of the strain increased by 70%. We also show that HXT1 and HXT2 transcription levels slightly increased when xylose was present. We also show that HXT1 and HXT2 transcription levels slightly increased when xylose was present. Deletion of either RGT2 or SNF3 reduced expression of HXT1 in strains cultured in 1 g L−1 xylose, which suggests that xylose can bind both Snf3 and Rgt2 and slightly alter their conformations. Deletion of SNF3 significantly weakened the expression of HXT2 in the yeast cultured in 40 g L−1 xylose, while deletion of RGT2 did not weaken expression of HXT2, suggesting that S. cerevisiae mainly depends on Snf3 to sense a high concentration of xylose (40 g L−1). Finally, we show that deletion of Rgt1, increased rxylose by 24% from that of the control. Our findings indicate how S. cerevisiae may respond to xylose and this study provides novel targets for further engineering of xylose-fermenting strains.

scholarly journals Protein acetylation regulates xylose metabolism during adaptation of Saccharomyces cerevisiae

2021 ◽  
Author(s):  
Yong-Shui Tan ◽  
Li Wang ◽  
Ying-Ying Wang ◽  
Qi-En He ◽  
Zhen Zhu ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Fold Increase ◽  
The State ◽  
Confirmatory Test ◽  
Xylose Utilization ◽  
Protein Acetylation ◽  
Xylose Metabolism ◽  
Promising Alternative ◽  
Xylose Consumption ◽  
Synthetic Complete

Abstract Background Lignocellulosic biomass upgrading has become a promising alternative route to produce transportation fuels in response to energy security and environmental concerns. As the second most abundant polysaccharide in nature, hemicellulose mainly containing xylose is an important carbon source that can be used for the bioconversion to fuels and chemicals. However, the adaptation phenomena could appear and influence the bioconversion performance of xylose when Saccharomyces cerevisiae strain was transferred from the glucose to the xylose environment. Therefore, it is crucial to elucidate the mechanism of this adaptation phenomena, which can guide the strategy exploration to improve the efficiency of xylose utilization. Results In this study, xylose-utilizing strains had been constructed to effectively consume xylose. It is found that the second incubation of yYST218 strain in synthetic complete-xylose medium resulted in a 1.24-fold increase in xylose consumption ability as compared with the first incubation in synthetic complete-xylose medium. The results clearly showed that growing S. cerevisiae again in synthetic complete-xylose medium can significantly reduce the stagnation time and thus achieved a faster growth rate, by comparing the growth status of the strain in synthetic complete-xylose medium for the first and second time at the single-cell level through Microfluidic technology. Although these xylose-utilizing strains possessed different xylose metabolism pathways, they exhibited the “transient memory” phenomenon of xylose metabolism after changing the culture environment to synthetic complete-xylose medium, which named ‘xylose consumption memory (XCM)’ of S. cerevisiae in this study. According to the identification of protein acetylation, partial least squares analysis and the confirmatory test had verified that H4K5Ac affected the state of “XCM” in S. cerevisiae. Knockout of the acetylase-encoding genes GCN5 and HPA2 enhanced the “XCM” of the strain. Protein acetylation analysis suggested that xylose induced perturbation in S. cerevisiae stimulated the rapid adaptation of strains to xylose environment by regulating the level of acetylation. Conclusions All these results indicated protein acetylation modification is an important aspect that protein acetylation regulated the state of “XCM” in S. cerevisiae and thus determine the environmental adaptation of S. cerevisiae. Systematically exploiting the regulation approach of protein acetylation in S. cerevisiae could provide valuable insights into the adaptation phenomena of microorganisms in complex industrial environments.

scholarly journals Protein acetylation regulates xylose metabolism during adaptation of Saccharomyces cerevisiae

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Yong-Shui Tan ◽  
Li Wang ◽  
Ying-Ying Wang ◽  
Qi-En He ◽  
Zhi-Hua Liu ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Xylose Reductase ◽  
Xylose Isomerase ◽  
Xylose Utilization ◽  
Xylose Metabolism ◽  
Xylose Consumption ◽  
Synthetic Complete ◽  
Before And After ◽  
Genes Encoding ◽  
Fuels And Chemicals

Abstract Background As the second most abundant polysaccharide in nature, hemicellulose can be degraded to xylose as the feedstock for bioconversion to fuels and chemicals. To enhance xylose conversion, the engineered Saccharomyces cerevisiae with xylose metabolic pathway is usually adapted with xylose as the carbon source in the laboratory. However, the mechanism under the adaptation phenomena of the engineered strain is still unclear. Results In this study, xylose-utilizing S. cerevisiae was constructed and used for the adaptation study. It was found that xylose consumption rate increased 1.24-fold in the second incubation of the yYST12 strain in synthetic complete-xylose medium compared with the first incubation. The study figured out that it was observed at the single-cell level that the stagnation time for xylose utilization was reduced after adaptation with xylose medium in the microfluidic device. Such transient memory of xylose metabolism after adaptation with xylose medium, named “xylose consumption memory”, was observed in the strains with both xylose isomerase pathway and xylose reductase and xylitol dehydrogenase pathways. In further, the proteomic acetylation of the strains before and after adaptation was investigated, and it was revealed that H4K5 was one of the most differential acetylation sites related to xylose consumption memory of engineered S. cerevisiae. We tested 8 genes encoding acetylase or deacetylase, and it was found that the knockout of the GCN5 and HPA2 encoding acetylases enhanced the xylose consumption memory. Conclusions The behavior of xylose consumption memory in engineered S. cerevisiae can be successfully induced with xylose in the adaptation. H4K5Ac and two genes of GCN5 and HPA2 are related to xylose consumption memory of engineered S. cerevisiae during adaptation. This study provides valuable insights into the xylose adaptation of engineered S. cerevisiae.

scholarly journals Xylose utilization stimulates mitochondrial production of isobutanol and 2-methyl-1-butanol in Saccharomyces cerevisiae

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Yanfei Zhang ◽  
Stephan Lane ◽  
Jhong-Min Chen ◽  
Sarah K. Hammer ◽  
Jake Luttinger ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Biosynthetic Pathway ◽  
Xylose Isomerase ◽  
Biofuel Production ◽  
Mitochondrial Activity ◽  
Xylose Utilization ◽  
Gene Deletions ◽  
Theoretical Yield ◽  
Byproduct Formation ◽  
Branched Chain

Abstract Background Branched-chain higher alcohols (BCHAs), including isobutanol and 2-methyl-1-butanol, are promising advanced biofuels, superior to ethanol due to their higher energy density and better compatibility with existing gasoline infrastructure. Compartmentalizing the isobutanol biosynthetic pathway in yeast mitochondria is an effective way to produce BCHAs from glucose. However, to improve the sustainability of biofuel production, there is great interest in developing strains and processes to utilize lignocellulosic biomass, including its hemicellulose component, which is mostly composed of the pentose xylose. Results In this work, we rewired the xylose isomerase assimilation and mitochondrial isobutanol production pathways in the budding yeast Saccharomyces cerevisiae. We then increased the flux through these pathways by making gene deletions of BAT1, ALD6, and PHO13, to develop a strain (YZy197) that produces as much as 4 g/L of BCHAs (3.10 ± 0.18 g isobutanol/L and 0.91 ± 0.02 g 2-methyl-1-butanol/L) from xylose. This represents approximately a 28-fold improvement on the highest isobutanol titers obtained from xylose previously reported in yeast and the first report of 2-methyl-1-butanol produced from xylose. The yield of total BCHAs is 57.2 ± 5.2 mg/g xylose, corresponding to ~ 14% of the maximum theoretical yield. Respirometry experiments show that xylose increases mitochondrial activity by as much as 7.3-fold compared to glucose. Conclusions The enhanced levels of mitochondrial BCHA production achieved, even without disrupting ethanol byproduct formation, arise mostly from xylose activation of mitochondrial activity and are correlated with slow rates of sugar consumption.

scholarly journals Directed Evolution of Xylose Isomerase for Improved Xylose Catabolism and Fermentation in the Yeast Saccharomyces cerevisiae

2012 ◽  
Vol 78 (16) ◽  
pp. 5708-5716 ◽  
Author(s):  
Sun-Mi Lee ◽  
Taylor Jellison ◽  
Hal S. Alper
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Ethanol Production ◽  
Directed Evolution ◽  
Ethanol Yield ◽  
Xylose Isomerase ◽  
Mutant Enzyme ◽  
Xylose Utilization ◽  
Xylose Consumption ◽  
Content Type ◽  
Consumption Rates

ABSTRACTThe heterologous expression of a highly functional xylose isomerase pathway inSaccharomyces cerevisiaewould have significant advantages for ethanol yield, since the pathway bypasses cofactor requirements found in the traditionally used oxidoreductase pathways. However, nearly all reported xylose isomerase-based pathways inS. cerevisiaesuffer from poor ethanol productivity, low xylose consumption rates, and poor cell growth compared with an oxidoreductase pathway and, additionally, often require adaptive strain evolution. Here, we report on the directed evolution of thePiromycessp. xylose isomerase (encoded byxylA) for use in yeast. After three rounds of mutagenesis and growth-based screening, we isolated a variant containing six mutations (E15D, E114G, E129D, T142S, A177T, and V433I) that exhibited a 77% increase in enzymatic activity. When expressed in a minimally engineered yeast host containing agre3knockout andtal1andXKS1overexpression, the strain expressing this mutant enzyme improved its aerobic growth rate by 61-fold and both ethanol production and xylose consumption rates by nearly 8-fold. Moreover, the mutant enzyme enabled ethanol production by these yeasts under oxygen-limited fermentation conditions, unlike the wild-type enzyme. Under microaerobic conditions, the ethanol production rates of the strain expressing the mutant xylose isomerase were considerably higher than previously reported values for yeast harboring a xylose isomerase pathway and were also comparable to those of the strains harboring an oxidoreductase pathway. Consequently, this study shows the potential to evolve a xylose isomerase pathway for more efficient xylose utilization.

Regulation of Xylose Utilization in Recombinant Saccharomyces cerevisiae and Improvement of its Ethanol Production

2010 ◽  
Vol 150 ◽  
pp. 554-555
Author(s):  
Ji-Hye Han ◽  
Ju-Yong Park ◽  
Hyun Woo Kang ◽  
Gi-Wook Choi ◽  
Bong-Woo Chung ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Ethanol Production ◽  
Xylose Utilization ◽  
Recombinant Saccharomyces Cerevisiae

An improved method of xylose utilization by recombinant Saccharomyces cerevisiae

2012 ◽  
Vol 39 (10) ◽  
pp. 1477-1486 ◽  
Author(s):  
Tien-Yang Ma ◽  
Ting-Hsiang Lin ◽  
Teng-Chieh Hsu ◽  
Chiung-Fang Huang ◽  
Gia-Luen Guo ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Xylose Utilization ◽  
Improved Method ◽  
Recombinant Saccharomyces Cerevisiae

scholarly journals Combinatorial Design of a Highly Efficient Xylose-Utilizing Pathway in Saccharomyces cerevisiae for the Production of Cellulosic Biofuels

2012 ◽  
Vol 79 (3) ◽  
pp. 931-941 ◽  
Author(s):  
Byoungjin Kim ◽  
Jing Du ◽  
Dawn T. Eriksen ◽  
Huimin Zhao
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Metabolic Flux ◽  
Value Added ◽  
Major Product ◽  
Combinatorial Design ◽  
Biofuel Production ◽  
Pathway Engineering ◽  
Full Potential ◽  
Xylose Utilization ◽  
Highly Efficient

ABSTRACTBalancing the flux of a heterologous metabolic pathway by tuning the expression and properties of the pathway enzymes is difficult, but it is critical to realizing the full potential of microbial biotechnology. One prominent example is the metabolic engineering of aSaccharomyces cerevisiaestrain harboring a heterologous xylose-utilizing pathway for cellulosic-biofuel production, which remains a challenge even after decades of research. Here, we developed a combinatorial pathway-engineering approach to rapidly create a highly efficient xylose-utilizing pathway for ethanol production by exploring various combinations of enzyme homologues with different properties. A library of more than 8,000 xylose utilization pathways was generated using DNA assembler, followed by multitiered screening, which led to the identification of a number of strain-specific combinations of the enzymes for efficient conversion of xylose to ethanol. The balancing of metabolic flux through the xylose utilization pathway was demonstrated by a complete reversal of the major product from xylitol to ethanol with a similar yield and total by-product formation as low as 0.06 g/g xylose without compromising cell growth. The results also suggested that an optimal enzyme combination depends on not only the genotype/phenotype of the host strain, but also the sugar composition of the fermentation medium. This combinatorial approach should be applicable to any heterologous pathway and will be instrumental in the optimization of industrial production of value-added products.

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