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Inokuma K, Toyohara K, Hamada T, Kondo A, Hasunuma T. One-pot synthesis of cellobiose from sucrose using sucrose phosphorylase and cellobiose phosphorylase co-displaying Pichia pastoris as a reusable whole-cell biocatalyst. Sci Rep 2024; 14:18540. [PMID: 39122907 PMCID: PMC11315685 DOI: 10.1038/s41598-024-69676-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2024] [Accepted: 08/07/2024] [Indexed: 08/12/2024] Open
Abstract
Cellobiose has received increasing attention in various industrial sectors, ranging from food and feed to cosmetics. The development of large-scale cellobiose applications requires a cost-effective production technology as currently used methods based on cellulose hydrolysis are costly. Here, a one-pot synthesis of cellobiose from sucrose was conducted using a recombinant Pichia pastoris strain as a reusable whole-cell biocatalyst. Thermophilic sucrose phosphorylase from Bifidobacterium longum (BlSP) and cellobiose phosphorylase from Clostridium stercorarium (CsCBP) were co-displayed on the cell surface of P. pastoris via a glycosylphosphatidylinositol-anchoring system. Cells of the BlSP and CsCBP co-displaying P. pastoris strain were used as whole-cell biocatalysts to convert sucrose to cellobiose with commercial thermophilic xylose isomerase. Cellobiose productivity significantly improved with yeast cells grown on glycerol compared to glucose-grown cells. In one-pot bioconversion using glycerol-grown yeast cells, approximately 81.2 g/L of cellobiose was produced from 100 g/L of sucrose, corresponding to 81.2% of the theoretical maximum yield, within 24 h at 60 °C. Moreover, recombinant yeast cells maintained a cellobiose titer > 80 g/L, even after three consecutive cell-recycling one-pot bioconversion cycles. These results indicated that one-pot bioconversion using yeast cells displaying two phosphorylases as whole-cell catalysts is a promising approach for cost-effective cellobiose production.
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Affiliation(s)
- Kentaro Inokuma
- Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodai-Cho, Nada-Ku, Kobe, 657-8501, Japan
| | - Kiyotsuna Toyohara
- Iwakuni Research Center, TEIJIN Limited, 2-1 Hinode, Iwakuni, Yamagichi, 740-8511, Japan
| | - Tomoya Hamada
- Iwakuni Research Center, TEIJIN Limited, 2-1 Hinode, Iwakuni, Yamagichi, 740-8511, Japan
| | - Akihiko Kondo
- Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodai-Cho, Nada-Ku, Kobe, 657-8501, Japan
- Engineering Biology Research Center, Kobe University, 1-1 Rokkodai-Cho, Nada-Ku, Kobe, 657-8501, Japan
- Biomass Engineering Program, RIKEN, 1-7-22 Suehiro-Cho, Tsurumi-Ku, Yokohama, Kanagawa, 230-0045, Japan
| | - Tomohisa Hasunuma
- Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodai-Cho, Nada-Ku, Kobe, 657-8501, Japan.
- Engineering Biology Research Center, Kobe University, 1-1 Rokkodai-Cho, Nada-Ku, Kobe, 657-8501, Japan.
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2
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Sigg A, Klimacek M, Nidetzky B. Pushing the boundaries of phosphorylase cascade reaction for cellobiose production I: Kinetic model development. Biotechnol Bioeng 2024; 121:580-592. [PMID: 37983971 DOI: 10.1002/bit.28602] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 10/31/2023] [Accepted: 11/04/2023] [Indexed: 11/22/2023]
Abstract
One-pot cascade reactions of coupled disaccharide phosphorylases enable an efficient transglycosylation via intermediary α-d-glucose 1-phosphate (G1P). Such transformations have promising applications in the production of carbohydrate commodities, including the disaccharide cellobiose for food and feed use. Several studies have shown sucrose and cellobiose phosphorylase for cellobiose synthesis from sucrose, but the boundaries on transformation efficiency that result from kinetic and thermodynamic characteristics of the individual enzyme reactions are not known. Here, we assessed in a step-by-step systematic fashion the practical requirements of a kinetic model to describe cellobiose production at industrially relevant substrate concentrations of up to 600 mM sucrose and glucose each. Mechanistic initial-rate models of the two-substrate reactions of sucrose phosphorylase (sucrose + phosphate → G1P + fructose) and cellobiose phosphorylase (G1P + glucose → cellobiose + phosphate) were needed and additionally required expansion by terms of glucose inhibition, in particular a distinctive two-site glucose substrate inhibition of the cellobiose phosphorylase (from Cellulumonas uda). Combined with mass action terms accounting for the approach to equilibrium, the kinetic model gave an excellent fit and a robust prediction of the full reaction time courses for a wide range of enzyme activities as well as substrate concentrations, including the variable substoichiometric concentration of phosphate. The model thus provides the essential engineering tool to disentangle the highly interrelated factors of conversion efficiency in the coupled enzyme reaction; and it establishes the necessary basis of window of operation calculations for targeted optimizations toward different process tasks.
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Affiliation(s)
- Alexander Sigg
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Graz, Austria
| | - Mario Klimacek
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Graz, Austria
| | - Bernd Nidetzky
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Graz, Austria
- Austrian Centre of Industrial Biotechnology (ACIB), Graz, Austria
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3
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Zhang S, Ni D, Zhu Y, Xu W, Zhang W, Mu W. A comprehensive review on the properties, production, and applications of functional glucobioses. Crit Rev Food Sci Nutr 2023:1-14. [PMID: 37819266 DOI: 10.1080/10408398.2023.2261053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
Glucobiose is a range of disaccharides consisting of two glucose molecules, generally including trehalose, kojibiose, sophorose, nigerose, laminaribiose, maltose, cellobiose, isomaltose, and gentiobiose. The difference glycosidic bonds of two glucose molecules result in the diverse molecular structures, physiochemical properties and physiological functions of these glucobioses. Some glucobioses are abundant in nature but have unconspicuous roles on health like maltose, whereas some rare glucobioses display remarkable biological effects. It is unpractical process to extract these rare glucobioses from natural resources, while biological synthesis is a feasible approach. Recently, the production and application of glucobiose have attracted considerable attention. This review provides a comprehensive overview of glucobioses, including their natural sources and physicochemical properties like structure, sweetness, digestive performance, toxicology, and cariogenicity. Specific enzymes used for the production of various glucobioses and fermentation production processes are summarized. Additionally, their versatile functions and broad applications are also introduced.
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Affiliation(s)
- Shuqi Zhang
- State Key Laboratory of Food Science and Resoruces, Jiangnan University, Wuxi, Jiangsu, China
| | - Dawei Ni
- State Key Laboratory of Food Science and Resoruces, Jiangnan University, Wuxi, Jiangsu, China
| | - Yingying Zhu
- State Key Laboratory of Food Science and Resoruces, Jiangnan University, Wuxi, Jiangsu, China
| | - Wei Xu
- State Key Laboratory of Food Science and Resoruces, Jiangnan University, Wuxi, Jiangsu, China
| | - Wenli Zhang
- State Key Laboratory of Food Science and Resoruces, Jiangnan University, Wuxi, Jiangsu, China
| | - Wanmeng Mu
- State Key Laboratory of Food Science and Resoruces, Jiangnan University, Wuxi, Jiangsu, China
- International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, Jiangsu, China
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4
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Siedentop R, Dziennus M, Lütz S, Rosenthal K. Debottlenecking of an In Vitro Enzyme Cascade Using a Combined Model‐ and Experiment‐Based Approach. CHEM-ING-TECH 2023. [DOI: 10.1002/cite.202200170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Affiliation(s)
- Regine Siedentop
- TU Dortmund University Chair for Bioprocess Engineering, Department of Biochemical and Chemical Engineering Emil-Figge-Straße 66 44227 Dortmund Germany
| | - Marlon Dziennus
- TU Dortmund University Chair for Bioprocess Engineering, Department of Biochemical and Chemical Engineering Emil-Figge-Straße 66 44227 Dortmund Germany
| | - Stephan Lütz
- TU Dortmund University Chair for Bioprocess Engineering, Department of Biochemical and Chemical Engineering Emil-Figge-Straße 66 44227 Dortmund Germany
| | - Katrin Rosenthal
- Constructor University Department of Life Sciences and Chemistry Campus Ring 1 28759 Bremen Germany
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Qin Y, Li Q, Fan L, Ning X, Wei X, You C. Biomanufacturing by In Vitro Biotransformation (ivBT) Using Purified Cascade Multi-enzymes. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2023; 186:1-27. [PMID: 37455283 DOI: 10.1007/10_2023_231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/18/2023]
Abstract
In vitro biotransformation (ivBT) refers to the use of an artificial biological reaction system that employs purified enzymes for the one-pot conversion of low-cost materials into biocommodities such as ethanol, organic acids, and amino acids. Unshackled from cell growth and metabolism, ivBT exhibits distinct advantages compared with metabolic engineering, including but not limited to high engineering flexibility, ease of operation, fast reaction rate, high product yields, and good scalability. These characteristics position ivBT as a promising next-generation biomanufacturing platform. Nevertheless, challenges persist in the enhancement of bulk enzyme preparation methods, the acquisition of enzymes with superior catalytic properties, and the development of sophisticated approaches for pathway design and system optimization. In alignment with the workflow of ivBT development, this chapter presents a systematic introduction to pathway design, enzyme mining and engineering, system construction, and system optimization. The chapter also proffers perspectives on ivBT development.
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Affiliation(s)
- Yanmei Qin
- University of Chinese Academy of Sciences, Beijing, China
- In Vitro Synthetic Biology Center, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
| | - Qiangzi Li
- In Vitro Synthetic Biology Center, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
| | - Lin Fan
- University of Chinese Academy of Sciences, Beijing, China
- In Vitro Synthetic Biology Center, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
- University of Chinese Academy of Sciences Sino-Danish College, Beijing, China
| | - Xiao Ning
- University of Chinese Academy of Sciences, Beijing, China
- In Vitro Synthetic Biology Center, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
| | - Xinlei Wei
- In Vitro Synthetic Biology Center, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China.
- National Technology Innovation Center of Synthetic Biology, Tianjin, China.
| | - Chun You
- In Vitro Synthetic Biology Center, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China.
- National Technology Innovation Center of Synthetic Biology, Tianjin, China.
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Schwaiger KN, Voit A, Wiltschi B, Nidetzky B. Engineering cascade biocatalysis in whole cells for bottom-up synthesis of cello-oligosaccharides: flux control over three enzymatic steps enables soluble production. Microb Cell Fact 2022; 21:61. [PMID: 35397553 PMCID: PMC8994397 DOI: 10.1186/s12934-022-01781-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 03/24/2022] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Soluble cello-oligosaccharides (COS, β-1,4-D-gluco-oligosaccharides with degree of polymerization DP 2-6) have been receiving increased attention in different industrial sectors, from food and feed to cosmetics. Development of large-scale COS applications requires cost-effective technologies for their production. Cascade biocatalysis by the three enzymes sucrose-, cellobiose- and cellodextrin phosphorylase is promising because it enables bottom-up synthesis of COS from expedient substrates such as sucrose and glucose. A whole-cell-derived catalyst that incorporates the required enzyme activities from suitable co-expression would represent an important step towards making the cascade reaction fit for production. Multi-enzyme co-expression to reach distinct activity ratios is challenging in general, but it requires special emphasis for the synthesis of COS. Only a finely tuned balance between formation and elongation of the oligosaccharide precursor cellobiose results in the desired COS. RESULTS Here, we show the integration of cellodextrin phosphorylase into a cellobiose-producing whole-cell catalyst. We arranged the co-expression cassettes such that their expression levels were upregulated. The most effective strategy involved a custom vector design that placed the coding sequences for cellobiose phosphorylase (CbP), cellodextrin phosphorylase (CdP) and sucrose phosphorylase (ScP) in a tricistron in the given order. The expression of the tricistron was controlled by the strong T7lacO promoter and strong ribosome binding sites (RBS) for each open reading frame. The resulting whole-cell catalyst achieved a recombinant protein yield of 46% of total intracellular protein in an optimal ScP:CbP:CdP activity ratio of 10:2.9:0.6, yielding an overall activity of 315 U/g dry cell mass. We demonstrated that bioconversion catalyzed by a semi-permeabilized whole-cell catalyst achieved an industrial relevant COS product titer of 125 g/L and a space-time yield of 20 g/L/h. With CbP as the cellobiose providing enzyme, flux into higher oligosaccharides (DP ≥ 6) was prevented and no insoluble products were formed after 6 h of conversion. CONCLUSIONS A whole-cell catalyst for COS biosynthesis was developed. The coordinated co-expression of the three biosynthesis enzymes balanced the activities of the individual enzymes such that COS production was maximized. With the flux control set to minimize the share of insolubles in the product, the whole-cell synthesis shows a performance with respect to yield, productivity, product concentration and quality that is promising for industrial production.
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Affiliation(s)
- Katharina N. Schwaiger
- grid.432147.70000 0004 0591 4434ACIB-Austrian Centre of Industrial Biotechnology, Krenngasse 37, 8010 Graz, Austria
| | - Alena Voit
- grid.432147.70000 0004 0591 4434ACIB-Austrian Centre of Industrial Biotechnology, Krenngasse 37, 8010 Graz, Austria
| | - Birgit Wiltschi
- grid.432147.70000 0004 0591 4434ACIB-Austrian Centre of Industrial Biotechnology, Krenngasse 37, 8010 Graz, Austria
| | - Bernd Nidetzky
- grid.432147.70000 0004 0591 4434ACIB-Austrian Centre of Industrial Biotechnology, Krenngasse 37, 8010 Graz, Austria ,grid.410413.30000 0001 2294 748XInstitute of Biotechnology and Biochemical Engineering, NAWI Graz, Graz University of Technology, Petersgasse 12, 8010 Graz, Austria
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7
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Chen X, Wang F, Yu Q, Liu S, Wang W, Zhang Y, Wang Z, Yuan Z. One pot cascade biosynthesis of d-allulose from d-glucose and its kinetic modelling. Chem Eng Sci 2022. [DOI: 10.1016/j.ces.2021.117167] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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8
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Wang L, Zheng P, Hu M, Tao Y. OUP accepted manuscript. J Ind Microbiol Biotechnol 2022; 49:6548896. [PMID: 35289917 PMCID: PMC9142195 DOI: 10.1093/jimb/kuac008] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 02/20/2022] [Indexed: 11/14/2022]
Abstract
Cellobiose, a natural disaccharide, attracts extensive attention as a potential functional food/feed additive. In this study, we present an inorganic phosphate (Pi) self-sufficient biotransformation system to produce cellobiose by co-expressing sucrose phosphorylase (SP) and cellobiose phosphorylase (CBP). The Bifidobacterium adolescentis SP (BASP) and Cellvibrio gilvus CBP (CGCBP) were co-expressed in Escherichia coli. Escherichia coli cells containing BASP and CGCBP were used as whole-cell catalysts to convert sucrose and glucose to cellobiose. The effects of reaction pH, temperature, Pi concentration, and substrate concentration were investigated. In the optimum biotransformation conditions, 800 mM cellobiose was produced from 1.0 M sucrose, 1.0 M glucose, and 50 mM Pi, within 12 hr. The by-product fructose and residual substrate (sucrose and glucose) were efficiently removed by treatment with yeast, to help purify the product cellobiose. The wider applicability of this Pi self-sufficiency strategy was demonstrated in the production of laminaribiose by co-expressing SP and laminaribiose phosphorylase. This study suggests that the Pi self-sufficiency strategy through co-expressing two phosphorylases has the advantage of great flexibility for enhanced production of cellobiose (or laminaribiose).
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Affiliation(s)
- Lei Wang
- Correspondence should be addressed to: Lei Wang, E-mail:
| | - Peng Zheng
- Chinese Academy of Sciences Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China
| | - Meirong Hu
- Chinese Academy of Sciences Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yong Tao
- Correspondence should be addressed to: Yong Tao, E-mail:
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9
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Bulmer GS, de Andrade P, Field RA, van Munster JM. Recent advances in enzymatic synthesis of β-glucan and cellulose. Carbohydr Res 2021; 508:108411. [PMID: 34392134 PMCID: PMC8425183 DOI: 10.1016/j.carres.2021.108411] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 07/21/2021] [Accepted: 07/22/2021] [Indexed: 01/07/2023]
Abstract
Bottom-up synthesis of β-glucans such as callose, fungal β-(1,3)(1,6)-glucan and cellulose, can create the defined compounds that are needed to perform fundamental studies on glucan properties and develop applications. With the importance of β-glucans and cellulose in high-profile fields such as nutrition, renewables-based biotechnology and materials science, the enzymatic synthesis of such relevant carbohydrates and their derivatives has attracted much attention. Here we review recent developments in enzymatic synthesis of β-glucans and cellulose, with a focus on progress made over the last five years. We cover the different types of biocatalysts employed, their incorporation in cascades, the exploitation of enzyme promiscuity and their engineering, and reaction conditions affecting the production as well as in situ self-assembly of (non)functionalised glucans. The recent achievements in the application of glycosyl transferases and β-1,4- and β-1,3-glucan phosphorylases demonstrate the high potential and versatility of these biocatalysts in glucan synthesis in both industrial and academic contexts.
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Affiliation(s)
- Gregory S Bulmer
- Department of Chemistry and Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, UK
| | - Peterson de Andrade
- Department of Chemistry and Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, UK
| | - Robert A Field
- Department of Chemistry and Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, UK
| | - Jolanda M van Munster
- Department of Chemistry and Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, UK; Scotland's Rural College, Edinburgh, UK.
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10
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Getting the Most Out of Enzyme Cascades: Strategies to Optimize In Vitro Multi-Enzymatic Reactions. Catalysts 2021. [DOI: 10.3390/catal11101183] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In vitro enzyme cascades possess great benefits, such as their synthetic capabilities for complex molecules, no need for intermediate isolation, and the shift of unfavorable equilibria towards the products. Their performance, however, can be impaired by, for example, destabilizing or inhibitory interactions between the cascade components or incongruous reaction conditions. The optimization of such systems is therefore often inevitable but not an easy task. Many parameters such as the design of the synthesis route, the choice of enzymes, reaction conditions, or process design can alter the performance of an in vitro enzymatic cascade. Many strategies to tackle this complex task exist, ranging from experimental to in silico approaches and combinations of both. This review collates examples of various optimization strategies and their success. The feasibility of optimization goals, the influence of certain parameters and the usage of algorithm-based optimizations are discussed.
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11
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Schelch S, Eibinger M, Gross Belduma S, Petschacher B, Kuballa J, Nidetzky B. Engineering analysis of multienzyme cascade reactions for 3'-sialyllactose synthesis. Biotechnol Bioeng 2021; 118:4290-4304. [PMID: 34289079 PMCID: PMC9290085 DOI: 10.1002/bit.27898] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 06/29/2021] [Accepted: 07/18/2021] [Indexed: 11/06/2022]
Abstract
Sialo‐oligosaccharides are important products of emerging biotechnology for complex carbohydrates as nutritional ingredients. Cascade bio‐catalysis is central to the development of sialo‐oligosaccharide production systems, based on isolated enzymes or whole cells. Multienzyme transformations have been established for sialo‐oligosaccharide synthesis from expedient substrates, but systematic engineering analysis for the optimization of such transformations is lacking. Here, we show a mathematical modeling‐guided approach to 3ʹ‐sialyllactose (3SL) synthesis from N‐acetyl‐
d‐neuraminic acid (Neu5Ac) and lactose in the presence of cytidine 5ʹ‐triphosphate, via the reactions of cytidine 5ʹ‐monophosphate‐Neu5Ac synthetase and α2,3‐sialyltransferase. The Neu5Ac was synthesized in situ from N‐acetyl‐
d‐mannosamine using the reversible reaction with pyruvate by Neu5Ac lyase or the effectively irreversible reaction with phosphoenolpyruvate by Neu5Ac synthase. We show through comprehensive time‐course study by experiment and modeling that, due to kinetic rather than thermodynamic advantages of the synthase reaction, the 3SL yield was increased (up to 75%; 10.4 g/L) and the initial productivity doubled (15 g/L/h), compared with synthesis based on the lyase reaction. We further show model‐based optimization to minimize the total loading of protein (saving: up to 43%) while maintaining a suitable ratio of the individual enzyme activities to achieve 3SL target yield (61%–75%; 7–10 g/L) and overall productivity (3–5 g/L/h). Collectively, our results reveal the principal factors of enzyme cascade efficiency for 3SL synthesis and highlight the important role of engineering analysis to make multienzyme‐catalyzed transformations fit for oligosaccharide production.
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Affiliation(s)
- Sabine Schelch
- Austrian Centre of Industrial Biotechnology, Graz, Austria.,Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Graz, Austria
| | - Manuel Eibinger
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Graz, Austria
| | - Stefanie Gross Belduma
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Graz, Austria
| | - Barbara Petschacher
- Austrian Centre of Industrial Biotechnology, Graz, Austria.,Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Graz, Austria
| | | | - Bernd Nidetzky
- Austrian Centre of Industrial Biotechnology, Graz, Austria.,Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Graz, Austria
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12
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Sun S, You C. Disaccharide phosphorylases: Structure, catalytic mechanisms and directed evolution. Synth Syst Biotechnol 2021; 6:23-31. [PMID: 33665389 PMCID: PMC7896129 DOI: 10.1016/j.synbio.2021.01.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 01/13/2021] [Accepted: 01/31/2021] [Indexed: 12/16/2022] Open
Abstract
Disaccharide phosphorylases (DSPs) are carbohydrate-active enzymes with outstanding potential for the biocatalytic conversion of common table sugar into products with attractive properties. They are modular enzymes that form active homo-oligomers. From a mechanistic as well as a structural point of view, they are similar to glycoside hydrolases or glycosyltransferases. As the majority of DSPs show strict stereo- and regiospecificities, these enzymes were used to synthesize specific disaccharides. Currently, protein engineering of DSPs is pursued in different laboratories to broaden the donor and acceptor substrate specificities or improve the industrial particularity of naturally existing enzymes, to eventually generate a toolbox of new catalysts for glycoside synthesis. Herein we review the characteristics and classifications of reported DSPs and the glycoside products that they have been used to synthesize.
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Affiliation(s)
- Shangshang Sun
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin, 300308, People’s Republic of China
| | - Chun You
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin, 300308, People’s Republic of China
- University of Chinese Academy of Sciences, 19A Yuquan Road, Shijingshan District, Beijing, 100049, People’s Republic of China
- National Technology Innovation Center of Synthetic Biology, Tianjin, 300308, People’s Republic of China
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13
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Sun S, Wei X, Zhou X, You C. Construction of an Artificial In Vitro Synthetic Enzymatic Platform for Upgrading Low-Cost Starch to Value-Added Disaccharides. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2021; 69:302-314. [PMID: 33371670 DOI: 10.1021/acs.jafc.0c06936] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Disaccharides are valuable oligosaccharides with an increasing demand in the food, cosmetic, and pharmaceutical industries. Disaccharides can be manufactured by extraction from the acid hydrolysate of plant-derived substrates, but this method has several issues, such as the difficulty in accessing natural substrates, laborious product separation processes, and troublesome wastewater treatment. A chemical synthesis using glucose was developed for producing disaccharides, but this approach suffers from a low product yield due to the low specificity and requires tedious protection and deprotection processes. In this study, we adopted an artificial strategy for producing a variety of value-added disaccharides from low-cost starch through the construction of an in vitro synthetic enzymatic platform: two enzymes worked in parallel to convert starch to glucose and glucose 1-phosphate, and these two intermediates were subsequently condensed together to a disaccharide by a disaccharide phosphorylase. Several disaccharides, such as laminaribiose, cellobiose, trehalose, and sophorose, were produced successfully from starch with the yields of more than 80% with the help of kinetic mathematical models to predict the optimal reaction conditions, exhibiting great potential in an industrial scale. This study provided a promising alternative to reform the mode of disaccharide manufacturing.
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Affiliation(s)
- Shangshang Sun
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin 300308, People's Republic of China
| | - Xinlei Wei
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin 300308, People's Republic of China
| | - Xigui Zhou
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin 300308, People's Republic of China
| | - Chun You
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin 300308, People's Republic of China
- University of Chinese Academy of Sciences, 19A Yuquan Road, Shijingshan District, Beijing 100049, People's Republic of China
- National Technology Innovation Center of Synthetic Biology, Tianjin 300308, People's Republic of China
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14
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Bacterial sialyltransferases and their use in biocatalytic cascades for sialo-oligosaccharide production. Biotechnol Adv 2020; 44:107613. [DOI: 10.1016/j.biotechadv.2020.107613] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 08/13/2020] [Accepted: 08/13/2020] [Indexed: 12/17/2022]
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15
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Nidetzky B, Zhong C. Phosphorylase-catalyzed bottom-up synthesis of short-chain soluble cello-oligosaccharides and property-tunable cellulosic materials. Biotechnol Adv 2020; 51:107633. [PMID: 32966861 DOI: 10.1016/j.biotechadv.2020.107633] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 08/23/2020] [Accepted: 09/06/2020] [Indexed: 12/13/2022]
Abstract
Cellulose-based materials are produced industrially in countless varieties via top-down processing of natural lignocellulose substrates. By contrast, cellulosic materials are only rarely prepared via bottom up synthesis and oligomerization-induced self-assembly of cellulose chains. Building up a cellulose chain via precision polymerization is promising, however, for it offers tunability and control of the final chemical structure. Synthetic cellulose derivatives with programmable material properties might thus be obtained. Cellodextrin phosphorylase (CdP; EC 2.4.1.49) catalyzes iterative β-1,4-glycosylation from α-d-glucose 1-phosphate, with the ability to elongate a diversity of acceptor substrates, including cellobiose, d-glucose and a range of synthetic glycosides having non-sugar aglycons. Depending on the reaction conditions leading to different degrees of polymerization (DP), short-chain soluble cello-oligosaccharides (COS) or insoluble cellulosic materials are formed. Here, we review the characteristics of CdP as bio-catalyst for synthetic applications and show advances in the enzymatic production of COS and reducing end-modified, tailored cellulose materials. Recent studies reveal COS as interesting dietary fibers that could provide a selective prebiotic effect. The bottom-up synthesized celluloses involve chains of DP ≥ 9, as precipitated in solution, and they form ~5 nm thick sheet-like crystalline structures of cellulose allomorph II. Solvent conditions and aglycon structures can direct the cellulose chain self-assembly towards a range of material architectures, including hierarchically organized networks of nanoribbons, or nanorods as well as distorted nanosheets. Composite materials are also formed. The resulting materials can be useful as property-tunable hydrogels and feature site-specific introduction of functional and chemically reactive groups. Therefore, COS and cellulose obtained via bottom-up synthesis can expand cellulose applications towards product classes that are difficult to access via top-down processing of natural materials.
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Affiliation(s)
- Bernd Nidetzky
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Petersgasse 12, Graz 8010, Austria; Austrian Centre of Industrial Biotechnology (acib), Krenngasse 37, Graz 8010, Austria.
| | - Chao Zhong
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Petersgasse 12, Graz 8010, Austria
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16
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Schwaiger KN, Voit A, Dobiašová H, Luley C, Wiltschi B, Nidetzky B. Plasmid Design for Tunable Two-Enzyme Co-Expression Promotes Whole-Cell Production of Cellobiose. Biotechnol J 2020; 15:e2000063. [PMID: 32668097 DOI: 10.1002/biot.202000063] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 06/16/2020] [Indexed: 12/30/2022]
Abstract
Catalyst development for biochemical cascade reactions often follows a "whole-cell-approach" in which a single microbial cell is made to express all required enzyme activities. Although attractive in principle, the approach can encounter limitations when efficient overall flux necessitates precise balancing between activities. This study shows an effective integration of major design strategies from synthetic biology to a coherent development of plasmid vectors, enabling tunable two-enzyme co-expression in E. coli, for whole-cell-production of cellobiose. An efficient transformation of sucrose and glucose into cellobiose by a parallel (countercurrent) cascade of disaccharide phosphorylases requires the enzyme co-expression to cope with large differences in specific activity of cellobiose phosphorylase (14 U mg-1 ) and sucrose phosphorylase (122 U mg-1 ). Mono- and bicistronic co-expression strategies controlling transcription, transcription-translation coupling or plasmid replication are analyzed for effect on activity and stable producibility of the whole-cell-catalyst. A key role of bom (basis of mobility) for plasmid stability dependent on the ori is reported and the importance of RBS (ribosome binding site) strength is demonstrated. Whole cell catalysts show high specific rates (460 µmol cellobiose min-1 g-1 dry cells) and performance metrics (30 g L-1 ; ∼82% yield; 3.8 g L-1 h-1 overall productivity) promising for cellobiose production.
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Affiliation(s)
- Katharina N Schwaiger
- ACIB-Austrian Centre of Industrial Biotechnology, Krenngasse 37, 8010, Graz, Austria
| | - Alena Voit
- ACIB-Austrian Centre of Industrial Biotechnology, Krenngasse 37, 8010, Graz, Austria
| | - Hana Dobiašová
- ACIB-Austrian Centre of Industrial Biotechnology, Krenngasse 37, 8010, Graz, Austria
| | - Christiane Luley
- ACIB-Austrian Centre of Industrial Biotechnology, Krenngasse 37, 8010, Graz, Austria
| | - Birgit Wiltschi
- ACIB-Austrian Centre of Industrial Biotechnology, Krenngasse 37, 8010, Graz, Austria
| | - Bernd Nidetzky
- ACIB-Austrian Centre of Industrial Biotechnology, Krenngasse 37, 8010, Graz, Austria.,Institute of Biotechnology and Biochemical Engineering, TU Graz, NAWI Graz, Petersgasse 12, 8010, Graz, Austria
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17
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Using enzyme cascades in biocatalysis: Highlight on transaminases and carboxylic acid reductases. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2020; 1868:140322. [DOI: 10.1016/j.bbapap.2019.140322] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 11/07/2019] [Accepted: 11/08/2019] [Indexed: 12/21/2022]
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18
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Zhong C, Duić B, Bolivar JM, Nidetzky B. Three‐Enzyme Phosphorylase Cascade Immobilized on Solid Support for Biocatalytic Synthesis of Cello−oligosaccharides. ChemCatChem 2020. [DOI: 10.1002/cctc.201901964] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Chao Zhong
- Institute of Biotechnology and Biochemical EngineeringGraz University of Technology, NAWI Graz Petersgasse 12 8010 Graz Austria
| | - Božidar Duić
- Institute of Biotechnology and Biochemical EngineeringGraz University of Technology, NAWI Graz Petersgasse 12 8010 Graz Austria
| | - Juan M. Bolivar
- Institute of Biotechnology and Biochemical EngineeringGraz University of Technology, NAWI Graz Petersgasse 12 8010 Graz Austria
| | - Bernd Nidetzky
- Institute of Biotechnology and Biochemical EngineeringGraz University of Technology, NAWI Graz Petersgasse 12 8010 Graz Austria
- Austrian Centre of Industrial Biotechnology Petersgasse 14 8010 Graz Austria
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19
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Česnik M, Sudar M, Hernández K, Charnock S, Vasić-Rački Đ, Clapés P, Findrik Blažević Z. Cascade enzymatic synthesis of l-homoserine – mathematical modelling as a tool for process optimisation and design. REACT CHEM ENG 2020. [DOI: 10.1039/c9re00453j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mathematical modelling enabled cascade reaction optimisation; 100% increase in product concentration and 18% increase in volume productivity compared to previous work.
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Affiliation(s)
- M. Česnik
- University of Zagreb
- Faculty of Chemical Engineering and Technology
- HR-10000 Zagreb
- Croatia
| | - M. Sudar
- University of Zagreb
- Faculty of Chemical Engineering and Technology
- HR-10000 Zagreb
- Croatia
| | - K. Hernández
- Institute of Advanced Chemistry of Catalonia
- Biological Chemistry Department
- Biotransformation and Bioactive Molecules Group
- 08034 Barcelona
- Spain
| | | | - Đ. Vasić-Rački
- University of Zagreb
- Faculty of Chemical Engineering and Technology
- HR-10000 Zagreb
- Croatia
| | - P. Clapés
- Institute of Advanced Chemistry of Catalonia
- Biological Chemistry Department
- Biotransformation and Bioactive Molecules Group
- 08034 Barcelona
- Spain
| | - Z. Findrik Blažević
- University of Zagreb
- Faculty of Chemical Engineering and Technology
- HR-10000 Zagreb
- Croatia
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20
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Zhong C, Nidetzky B. Three-Enzyme Phosphorylase Cascade for Integrated Production of Short-Chain Cellodextrins. Biotechnol J 2019; 15:e1900349. [PMID: 31677345 DOI: 10.1002/biot.201900349] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 09/26/2019] [Indexed: 01/28/2023]
Abstract
Cellodextrins are linear β-1,4-gluco-oligosaccharides that are soluble in water up to a degree of polymerization (DP) of ≈6. Soluble cellodextrins have promising applications as nutritional ingredients. A DP-controlled, bottom-up synthesis from expedient substrates is desired for their bulk production. Here, a three-enzyme glycoside phosphorylase cascade is developed for the conversion of sucrose and glucose into short-chain (soluble) cellodextrins (DP range 3-6). The cascade reaction involves iterative β-1,4-glucosylation of glucose from α-glucose 1-phosphate (αGlc1-P) donor that is formed in situ from sucrose and phosphate. With final concentration and yield of the soluble cellodextrins set as targets for biocatalytic synthesis, three major factors of reaction efficiency are identified and partly optimized: the ratio of enzyme activity, the ratio of sucrose and glucose, and the phosphate concentration used. The efficient use of the phosphate/αGlc1-P shuttle for cellodextrin production is demonstrated and the soluble product at 40 g L-1 is obtained under near-complete utilization of the donor substrate offered (88 mol% from 200 mm sucrose). The productivity is 16 g (L h)-1 . Through a simple two-step route, the soluble cellodextrins are recovered from the reaction mixture in ≥95% purity and ≈92% yield. Overall, this study provides the basis for their integrated production.
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Affiliation(s)
- Chao Zhong
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 12, NAWI Graz, 8010, Graz, Austria
| | - Bernd Nidetzky
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 12, NAWI Graz, 8010, Graz, Austria.,Austrian Centre of Industrial Biotechnology, Petersgasse 14, 8010, Graz, Austria
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21
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Petroll K, Kopp D, Care A, Bergquist PL, Sunna A. Tools and strategies for constructing cell-free enzyme pathways. Biotechnol Adv 2018; 37:91-108. [PMID: 30521853 DOI: 10.1016/j.biotechadv.2018.11.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 10/22/2018] [Accepted: 11/20/2018] [Indexed: 12/12/2022]
Abstract
Single enzyme systems or engineered microbial hosts have been used for decades but the notion of assembling multiple enzymes into cell-free synthetic pathways is a relatively new development. The extensive possibilities that stem from this synthetic concept makes it a fast growing and potentially high impact field for biomanufacturing fine and platform chemicals, pharmaceuticals and biofuels. However, the translation of individual single enzymatic reactions into cell-free multi-enzyme pathways is not trivial. In reality, the kinetics of an enzyme pathway can be very inadequate and the production of multiple enzymes can impose a great burden on the economics of the process. We examine here strategies for designing synthetic pathways and draw attention to the requirements of substrates, enzymes and cofactor regeneration systems for improving the effectiveness and sustainability of cell-free biocatalysis. In addition, we comment on methods for the immobilisation of members of a multi-enzyme pathway to enhance the viability of the system. Finally, we focus on the recent development of integrative tools such as in silico pathway modelling and high throughput flux analysis with the aim of reinforcing their indispensable role in the future of cell-free biocatalytic pathways for biomanufacturing.
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Affiliation(s)
- Kerstin Petroll
- Department of Molecular Sciences, Macquarie University, Sydney, Australia
| | - Dominik Kopp
- Department of Molecular Sciences, Macquarie University, Sydney, Australia
| | - Andrew Care
- Department of Molecular Sciences, Macquarie University, Sydney, Australia; Biomolecular Discovery and Design Research Centre, Macquarie University, Sydney, Australia
| | - Peter L Bergquist
- Department of Molecular Sciences, Macquarie University, Sydney, Australia; Department of Molecular Medicine & Pathology, University of Auckland, Auckland, New Zealand
| | - Anwar Sunna
- Department of Molecular Sciences, Macquarie University, Sydney, Australia; Biomolecular Discovery and Design Research Centre, Macquarie University, Sydney, Australia.
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22
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Affiliation(s)
- Yifei Zhang
- Department of Biomedical
Engineering, Columbia University, New York, New York 10027, United States
| | - Henry Hess
- Department of Biomedical
Engineering, Columbia University, New York, New York 10027, United States
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23
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Zhong C, You C, Wei P, Zhang YHP. Thermal Cycling Cascade Biocatalysis of myo-Inositol Synthesis from Sucrose. ACS Catal 2017. [DOI: 10.1021/acscatal.7b01929] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Chao Zhong
- Biological
Systems Engineering Department, Virginia Tech, 304 Seitz Hall, Blacksburg, Virginia 24061, United States
- College
of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, People’s Republic of China
| | - Chun You
- Tianjin
Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West Seventh Avenue, Tianjin Airport Economic
Area, Tianjin 300308, People’s Republic of China
| | - Ping Wei
- College
of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, People’s Republic of China
| | - Yi-Heng Percival Zhang
- Biological
Systems Engineering Department, Virginia Tech, 304 Seitz Hall, Blacksburg, Virginia 24061, United States
- Tianjin
Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West Seventh Avenue, Tianjin Airport Economic
Area, Tianjin 300308, People’s Republic of China
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24
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Milker S, Fink MJ, Oberleitner N, Ressmann AK, Bornscheuer UT, Mihovilovic MD, Rudroff F. Kinetic Modeling of an Enzymatic Redox Cascade In Vivo Reveals Bottlenecks Caused by Cofactors. ChemCatChem 2017. [DOI: 10.1002/cctc.201700573] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Sofia Milker
- Institute of Applied Chemistry; TU Wien; Getreidemarkt 9/163-OC 1060 Vienna Austria
| | - Michael J. Fink
- Department of Chemistry and Chemical Biology; Harvard University; 12 Oxford St Cambridge MA 02138 USA
| | - Nikolin Oberleitner
- Institute of Applied Chemistry; TU Wien; Getreidemarkt 9/163-OC 1060 Vienna Austria
| | - Anna K. Ressmann
- Institute of Applied Chemistry; TU Wien; Getreidemarkt 9/163-OC 1060 Vienna Austria
| | - Uwe T. Bornscheuer
- Institute of Biochemistry, Dept. of Biotechnology & Enzyme Catalysis; Greifswald University; Felix-Hausdorff-Str. 4 17489 Greifswald Germany
| | - Marko D. Mihovilovic
- Institute of Applied Chemistry; TU Wien; Getreidemarkt 9/163-OC 1060 Vienna Austria
| | - Florian Rudroff
- Institute of Applied Chemistry; TU Wien; Getreidemarkt 9/163-OC 1060 Vienna Austria
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25
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In vitro metabolic engineering for the production of α-ketoglutarate. Metab Eng 2017; 40:5-13. [PMID: 28238759 DOI: 10.1016/j.ymben.2017.02.011] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 02/16/2017] [Accepted: 02/21/2017] [Indexed: 11/23/2022]
Abstract
α-Ketoglutarate (aKG) represents a central intermediate of cell metabolism. It is used for medical treatments and as a chemical building block. Enzymatic cascade reactions have the potential to sustainably synthesize this natural product. Here we report a systems biocatalysis approach for an in vitro reaction set-up to produce aKG from glucuronate using the oxidative pathway of uronic acids. Because of two dehydrations, a decarboxylation, and reaction conditions favoring oxidation, the pathway is driven thermodynamically towards complete product formation. The five enzymes (including one for cofactor recycling) were first investigated individually to define optimal reaction conditions for the cascade reaction. Then, the kinetic parameters were determined under these conditions and the inhibitory effects of substrate, intermediates, and product were evaluated. As cofactor supply is critical for the cascade reaction, various set-ups were tested: increasing concentrations of the recycling enzyme, different initial NAD+ concentrations, as well as the use of a bubble reactor for faster oxygen diffusion. Finally, we were able to convert 10gL-1 glucuronate with 92% yield of aKG within 5h. The maximum productivity of 2.8gL-1 h-1 is the second highest reported in the biotechnological synthesis of aKG.
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