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Procópio DP, Kendrick E, Goldbeck R, Damasio ARDL, Franco TT, Leak DJ, Jin YS, Basso TO. Xylo-Oligosaccharide Utilization by Engineered Saccharomyces cerevisiae to Produce Ethanol. Front Bioeng Biotechnol 2022; 10:825981. [PMID: 35242749 PMCID: PMC8886126 DOI: 10.3389/fbioe.2022.825981] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 01/18/2022] [Indexed: 11/26/2022] Open
Abstract
The engineering of xylo-oligosaccharide-consuming Saccharomyces cerevisiae strains is a promising approach for more effective utilization of lignocellulosic biomass and the development of economic industrial fermentation processes. Extending the sugar consumption range without catabolite repression by including the metabolism of oligomers instead of only monomers would significantly improve second-generation ethanol production This review focuses on different aspects of the action mechanisms of xylan-degrading enzymes from bacteria and fungi, and their insertion in S. cerevisiae strains to obtain microbial cell factories able of consume these complex sugars and convert them to ethanol. Emphasis is given to different strategies for ethanol production from both extracellular and intracellular xylo-oligosaccharide utilization by S. cerevisiae strains. The suitability of S. cerevisiae for ethanol production combined with its genetic tractability indicates that it can play an important role in xylan bioconversion through the heterologous expression of xylanases from other microorganisms.
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Affiliation(s)
- Dielle Pierotti Procópio
- Department of Chemical Engineering, Escola Politécnica, University of São Paulo, São Paulo, Brazil
| | - Emanuele Kendrick
- Department of Biology and Biochemistry, Faculty of Sciences, University of Bath, Bath, United Kingdom
| | - Rosana Goldbeck
- School of Food Engineering, University of Campinas, Campinas, Brazil
| | | | - Telma Teixeira Franco
- Interdisciplinary Center of Energy Planning, University of Campinas, Campinas, Brazil
- School of Chemical Engineering, University of Campinas, Campinas, Brazil
| | - David J. Leak
- Department of Biology and Biochemistry, Faculty of Sciences, University of Bath, Bath, United Kingdom
| | - Yong-Su Jin
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- Department of Food Science and Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Thiago Olitta Basso
- Department of Chemical Engineering, Escola Politécnica, University of São Paulo, São Paulo, Brazil
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Abstract
Glucose isomerase (GI, also known as xylose isomerase) reversibly isomerizes D-glucose and D-xylose to D-fructose and D-xylulose, respectively. GI plays an important role in sugar metabolism, fulfilling nutritional requirements in bacteria. In addition, GI is an important industrial enzyme for the production of high-fructose corn syrup and bioethanol. This review introduces the functions, structure, and applications of GI, in addition to presenting updated information on the characteristics of newly discovered GIs and structural information regarding the metal-binding active site of GI and its interaction with the inhibitor xylitol. This review provides an overview of recent advancements in the characterization and engineering of GI, as well as its industrial applications, and will help to guide future research in this field.
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Lee M, Rozeboom HJ, Keuning E, de Waal P, Janssen DB. Structure-based directed evolution improves S. cerevisiae growth on xylose by influencing in vivo enzyme performance. BIOTECHNOLOGY FOR BIOFUELS 2020; 13:5. [PMID: 31938040 PMCID: PMC6954610 DOI: 10.1186/s13068-019-1643-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 12/22/2019] [Indexed: 06/10/2023]
Abstract
BACKGROUND Efficient bioethanol production from hemicellulose feedstocks by Saccharomyces cerevisiae requires xylose utilization. Whereas S. cerevisiae does not metabolize xylose, engineered strains that express xylose isomerase can metabolize xylose by converting it to xylulose. For this, the type II xylose isomerase from Piromyces (PirXI) is used but the in vivo activity is rather low and very high levels of the enzyme are needed for xylose metabolism. In this study, we explore the use of protein engineering and in vivo selection to improve the performance of PirXI. Recently solved crystal structures were used to focus mutagenesis efforts. RESULTS We constructed focused mutant libraries of Piromyces xylose isomerase by substitution of second shell residues around the substrate- and metal-binding sites. Following library transfer to S. cerevisiae and selection for enhanced xylose-supported growth under aerobic and anaerobic conditions, two novel xylose isomerase mutants were obtained, which were purified and subjected to biochemical and structural analysis. Apart from a small difference in response to metal availability, neither the new mutants nor mutants described earlier showed significant changes in catalytic performance under various in vitro assay conditions. Yet, in vivo performance was clearly improved. The enzymes appeared to function suboptimally in vivo due to enzyme loading with calcium, which gives poor xylose conversion kinetics. The results show that better in vivo enzyme performance is poorly reflected in kinetic parameters for xylose isomerization determined in vitro with a single type of added metal. CONCLUSION This study shows that in vivo selection can identify xylose isomerase mutants with only minor changes in catalytic properties measured under standard conditions. Metal loading of xylose isomerase expressed in yeast is suboptimal and strongly influences kinetic properties. Metal uptake, distribution and binding to xylose isomerase are highly relevant for rapid xylose conversion and may be an important target for optimizing yeast xylose metabolism.
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Affiliation(s)
- Misun Lee
- Biochemical Laboratory, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Henriëtte J. Rozeboom
- Biochemical Laboratory, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Eline Keuning
- Biochemical Laboratory, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Paul de Waal
- DSM Biotechnology Center, Alexander Fleminglaan 1, 2613 AX Delft, The Netherlands
| | - Dick B. Janssen
- Biochemical Laboratory, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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Impact of CO 2/HCO 3 - Availability on Anaplerotic Flux in Pyruvate Dehydrogenase Complex-Deficient Corynebacterium glutamicum Strains. J Bacteriol 2019; 201:JB.00387-19. [PMID: 31358612 DOI: 10.1128/jb.00387-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 07/19/2019] [Indexed: 11/20/2022] Open
Abstract
The pyruvate dehydrogenase complex (PDHC) catalyzes the oxidative decarboxylation of pyruvate, yielding acetyl coenzyme A (acetyl-CoA) and CO2 The PDHC-deficient Corynebacterium glutamicum ΔaceE strain therefore lacks an important decarboxylation step in its central metabolism. Additional inactivation of pyc, encoding pyruvate carboxylase, resulted in a >15-h lag phase in the presence of glucose, while no growth defect was observed on gluconeogenetic substrates, such as acetate. Growth was successfully restored by deletion of ptsG, encoding the glucose-specific permease of the phosphotransferase system (PTS), thereby linking the observed phenotype to the increased sensitivity of the ΔaceE Δpyc strain to glucose catabolism. In this work, the ΔaceE Δpyc strain was used to systematically study the impact of perturbations of the intracellular CO2/HCO3 - pool on growth and anaplerotic flux. Remarkably, all measures leading to enhanced CO2/HCO3 - levels, such as external addition of HCO3 -, increasing the pH, or rerouting metabolic flux via the pentose phosphate pathway, at least partially eliminated the lag phase of the ΔaceE Δpyc strain on glucose medium. In accordance with these results, inactivation of the urease enzyme, lowering the intracellular CO2/HCO3 - pool, led to an even longer lag phase, accompanied by the excretion of l-valine and l-alanine. Transcriptome analysis, as well as an adaptive laboratory evolution experiment with the ΔaceE Δpyc strain, revealed the reduction of glucose uptake as a key adaptive measure to enhance growth on glucose-acetate mixtures. Taken together, our results highlight the significant impact of the intracellular CO2/HCO3 - pool on metabolic flux distribution, which becomes especially evident in engineered strains exhibiting low endogenous CO2 production rates, as exemplified by PDHC-deficient strains.IMPORTANCE CO2 is a ubiquitous product of cellular metabolism and an essential substrate for carboxylation reactions. The pyruvate dehydrogenase complex (PDHC) catalyzes a central metabolic reaction contributing to the intracellular CO2/HCO3 - pool in many organisms. In this study, we used a PDHC-deficient strain of Corynebacterium glutamicum, which additionally lacked pyruvate carboxylase (ΔaceE Δpyc). This strain featured a >15-h lag phase during growth on glucose-acetate mixtures. We used this strain to systematically assess the impact of alterations in the intracellular CO2/HCO3 - pool on growth in glucose-acetate medium. Remarkably, all measures enhancing CO2/HCO3 - levels successfully restored growth. These results emphasize the strong impact of the intracellular CO2/HCO3 - pool on metabolic flux, especially in strains exhibiting low endogenous CO2 production rates.
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Myers KS, Riley NM, MacGilvray ME, Sato TK, McGee M, Heilberger J, Coon JJ, Gasch AP. Rewired cellular signaling coordinates sugar and hypoxic responses for anaerobic xylose fermentation in yeast. PLoS Genet 2019; 15:e1008037. [PMID: 30856163 PMCID: PMC6428351 DOI: 10.1371/journal.pgen.1008037] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 03/21/2019] [Accepted: 02/20/2019] [Indexed: 01/08/2023] Open
Abstract
Microbes can be metabolically engineered to produce biofuels and biochemicals, but rerouting metabolic flux toward products is a major hurdle without a systems-level understanding of how cellular flux is controlled. To understand flux rerouting, we investigated a panel of Saccharomyces cerevisiae strains with progressive improvements in anaerobic fermentation of xylose, a sugar abundant in sustainable plant biomass used for biofuel production. We combined comparative transcriptomics, proteomics, and phosphoproteomics with network analysis to understand the physiology of improved anaerobic xylose fermentation. Our results show that upstream regulatory changes produce a suite of physiological effects that collectively impact the phenotype. Evolved strains show an unusual co-activation of Protein Kinase A (PKA) and Snf1, thus combining responses seen during feast on glucose and famine on non-preferred sugars. Surprisingly, these regulatory changes were required to mount the hypoxic response when cells were grown on xylose, revealing a previously unknown connection between sugar source and anaerobic response. Network analysis identified several downstream transcription factors that play a significant, but on their own minor, role in anaerobic xylose fermentation, consistent with the combinatorial effects of small-impact changes. We also discovered that different routes of PKA activation produce distinct phenotypes: deletion of the RAS/PKA inhibitor IRA2 promotes xylose growth and metabolism, whereas deletion of PKA inhibitor BCY1 decouples growth from metabolism to enable robust fermentation without division. Comparing phosphoproteomic changes across ira2Δ and bcy1Δ strains implicated regulatory changes linked to xylose-dependent growth versus metabolism. Together, our results present a picture of the metabolic logic behind anaerobic xylose flux and suggest that widespread cellular remodeling, rather than individual metabolic changes, is an important goal for metabolic engineering.
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Affiliation(s)
- Kevin S. Myers
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, WI, United States of America
| | - Nicholas M. Riley
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, United States of America
| | - Matthew E. MacGilvray
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI, United States of America
| | - Trey K. Sato
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, WI, United States of America
| | - Mick McGee
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, WI, United States of America
| | - Justin Heilberger
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, WI, United States of America
| | - Joshua J. Coon
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, United States of America
- Genome Center of Wisconsin, University of Wisconsin-Madison, Madison, WI, United States of America
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI, United States of America
- Morgridge Institute for Research, Madison, WI, United States of America
| | - Audrey P. Gasch
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, WI, United States of America
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI, United States of America
- Genome Center of Wisconsin, University of Wisconsin-Madison, Madison, WI, United States of America
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