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Liu ZX, Gao YD, Yang LC. Biocatalytic Hydrogen-Borrowing Cascade in Organic Synthesis. JACS AU 2024; 4:877-892. [PMID: 38559715 PMCID: PMC10976568 DOI: 10.1021/jacsau.4c00026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 02/26/2024] [Accepted: 02/27/2024] [Indexed: 04/04/2024]
Abstract
Biocatalytic hydrogen borrowing represents an environmentally friendly and highly efficient synthetic method. This innovative approach involves converting various substrates into high-value-added products, typically via a one-pot, two/three-step sequence encompassing dehydrogenation (intermediate transformation) and hydrogenation processes employing the hydride shuffling between NAD(P)+ and NAD(P)H. Represented key transformations in hydrogen borrowing include stereoisomer conversion within alcohols, conversion between alcohols and amines, conversion of allylic alcohols to saturated carbonyl counterparts, and α,β-unsaturated aldehydes to saturated carboxylic acids, etc. The direct transformation methodology and environmentally benign characteristics of hydrogen borrowing have contributed to its advancements in fine chemical synthesis or drug developments. Over the past decades, the hydrogen borrowing strategy in biocatalysis has led to the creation of diverse catalytic systems, demonstrating substantial potential for straightforward synthesis as well as asymmetric transformations. This perspective serves as a detailed exposition of the recent advancements in biocatalytic reactions employing the hydrogen borrowing strategy. It provides insights into the potential of this approach for future development, shedding light on its promising prospects in the field of biocatalysis.
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Affiliation(s)
- Zong-Xiao Liu
- State Key Laboratory of Bioactive Substance
and Function of Natural Medicines, Institute
of Materia Medica, Chinese Academy of Medical Sciences & Peking
Union Medical College, 100050 Beijing, P. R. China
| | - Ya-Dong Gao
- State Key Laboratory of Bioactive Substance
and Function of Natural Medicines, Institute
of Materia Medica, Chinese Academy of Medical Sciences & Peking
Union Medical College, 100050 Beijing, P. R. China
| | - Li-Cheng Yang
- State Key Laboratory of Bioactive Substance
and Function of Natural Medicines, Institute
of Materia Medica, Chinese Academy of Medical Sciences & Peking
Union Medical College, 100050 Beijing, P. R. China
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2
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Abstract
A number of self-sufficient hydride transfer processes have been reported in biocatalysis, with a common feature being the dependence on nicotinamide as a cofactor. This cofactor is provided in catalytic amounts and serves as a hydride shuttle to connect two or more enzymatic redox events, usually ensuring overall redox neutrality. Creative systems were designed to produce synthetic sequences characterized by high hydride economy, typically going in hand with excellent atom economy. Several redox enzymes have been successfully combined in one-pot one-step to allow functionalization of a large variety of molecules while preventing by-product formation. This review analyzes and classifies the various strategies, with a strong focus on efficiency, which is evaluated here in terms of the hydride economy and measured by the turnover number of the nicotinamide cofactor(s). The review ends with a critical evaluation of the reported systems and highlights areas where further improvements might be desirable.
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Affiliation(s)
- Erika Tassano
- Department of Chemistry, University of Graz, Heinrichstrasse 28, 8010, Graz, Austria.
| | - Mélanie Hall
- Department of Chemistry, University of Graz, Heinrichstrasse 28, 8010, Graz, Austria.
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Peng F, Ou X, Zhao Y, Zong M, Lou W. Highly selective resolution of racemic 1‐phenyl‐1,2‐ethanediol by a novel strain
Kurthia gibsonii
SC
0312. Lett Appl Microbiol 2019; 68:446-454. [DOI: 10.1111/lam.13123] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 01/16/2019] [Accepted: 01/22/2019] [Indexed: 11/29/2022]
Affiliation(s)
- F. Peng
- Laboratory of Applied Biocatalysis School of Food Science and Engineering South China University of Technology Guangzhou China
- Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety South China University of Technology Guangzhou China
| | - X.‐Y. Ou
- Laboratory of Applied Biocatalysis School of Food Science and Engineering South China University of Technology Guangzhou China
- Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety South China University of Technology Guangzhou China
| | - Y. Zhao
- Laboratory of Applied Biocatalysis School of Food Science and Engineering South China University of Technology Guangzhou China
- Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety South China University of Technology Guangzhou China
| | - M.‐H. Zong
- Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety South China University of Technology Guangzhou China
| | - W.‐Y. Lou
- Laboratory of Applied Biocatalysis School of Food Science and Engineering South China University of Technology Guangzhou China
- Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety South China University of Technology Guangzhou China
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Asplund-Samuelsson J, Janasch M, Hudson EP. Thermodynamic analysis of computed pathways integrated into the metabolic networks of E. coli and Synechocystis reveals contrasting expansion potential. Metab Eng 2017; 45:223-236. [PMID: 29278749 DOI: 10.1016/j.ymben.2017.12.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 12/04/2017] [Accepted: 12/20/2017] [Indexed: 01/09/2023]
Abstract
Introducing biosynthetic pathways into an organism is both reliant on and challenged by endogenous biochemistry. Here we compared the expansion potential of the metabolic network in the photoautotroph Synechocystis with that of the heterotroph E. coli using the novel workflow POPPY (Prospecting Optimal Pathways with PYthon). First, E. coli and Synechocystis metabolomic and fluxomic data were combined with metabolic models to identify thermodynamic constraints on metabolite concentrations (NET analysis). Then, thousands of automatically constructed pathways were placed within each network and subjected to a network-embedded variant of the max-min driving force analysis (NEM). We found that the networks had different capabilities for imparting thermodynamic driving forces toward certain compounds. Key metabolites were constrained differently in Synechocystis due to opposing flux directions in glycolysis and carbon fixation, the forked tri-carboxylic acid cycle, and photorespiration. Furthermore, the lysine biosynthesis pathway in Synechocystis was identified as thermodynamically constrained, impacting both endogenous and heterologous reactions through low 2-oxoglutarate levels. Our study also identified important yet poorly covered areas in existing metabolomics data and provides a reference for future thermodynamics-based engineering in Synechocystis and beyond. The POPPY methodology represents a step in making optimal pathway-host matches, which is likely to become important as the practical range of host organisms is diversified.
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Affiliation(s)
- Johannes Asplund-Samuelsson
- Science for Life Laboratory, School of Biotechnology, KTH Royal Institute of Technology, P-Box 1031, 171 21 Solna, Sweden.
| | - Markus Janasch
- Science for Life Laboratory, School of Biotechnology, KTH Royal Institute of Technology, P-Box 1031, 171 21 Solna, Sweden.
| | - Elton P Hudson
- Science for Life Laboratory, School of Biotechnology, KTH Royal Institute of Technology, P-Box 1031, 171 21 Solna, Sweden.
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5
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Li J, Zhang R, Xu Y, Xiao R, Li K, Liu H, Jiang J, Zhou X, Li L, Zhou L, Gu Y. Ala258Phe substitution in Bacillus sp. YX-1 glucose dehydrogenase improves its substrate preference for xylose. Process Biochem 2017. [DOI: 10.1016/j.procbio.2017.03.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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6
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Ying H, Tao S, Wang J, Ma W, Chen K, Wang X, Ouyang P. Expanding metabolic pathway for de novo biosynthesis of the chiral pharmaceutical intermediate L-pipecolic acid in Escherichia coli. Microb Cell Fact 2017; 16:52. [PMID: 28347340 PMCID: PMC5369227 DOI: 10.1186/s12934-017-0666-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 03/21/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The six-carbon circular non-proteinogenic compound L-pipecolic acid is an important chiral drug intermediate with many applications in the pharmaceutical industry. In the present study, we developed a metabolically engineered strain of Escherichia coli for the overproduction of L-pipecolic acid from glucose. RESULTS The metabolic pathway from L-lysine to L-pipecolic acid was constructed initially by introducing lysine cyclodeaminase (LCD). Next, L-lysine metabolic flux from glucose was amplified by the plasmid-based overexpression of dapA, lysC, and lysA under the control of the strong trc promoter to increase the biosynthetic pool of the precursor L-lysine. Additionally, since the catalytic efficiency of the key enzyme LCD is limited by the cofactor NAD+, the intracellular pyridine nucleotide concentration was rebalanced by expressing the pntAB gene encoding the transhydrogenase, which elevated the proportion of LCD with bound NAD+ and enhanced L-pipecolic acid production significantly. Further, optimization of Fe2+ and surfactant in the fermentation process resulted in 5.33 g/L L-pipecolic acid, with a yield of 0.13 g/g of glucose via fed-batch cultivation. CONCLUSIONS We expanded the metabolic pathway for the synthesis of the chiral pharmaceutical intermediate L-pipecolic acid in E. coli. Using the engineered E. coli, a fast and efficient fermentative production of L-pipecolic acid was achieved. This strategy could be applied to the biosynthesis of other commercially and industrially important chiral compounds containing piperidine rings.
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Affiliation(s)
- Hanxiao Ying
- State Key Laboratory of Materials Oriented Chemical Engineering, Nanjing, 211816, People's Republic of China.,College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211816, People's Republic of China
| | - Sha Tao
- State Key Laboratory of Materials Oriented Chemical Engineering, Nanjing, 211816, People's Republic of China.,College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211816, People's Republic of China
| | - Jing Wang
- State Key Laboratory of Materials Oriented Chemical Engineering, Nanjing, 211816, People's Republic of China.,College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211816, People's Republic of China
| | - Weichao Ma
- State Key Laboratory of Materials Oriented Chemical Engineering, Nanjing, 211816, People's Republic of China.,College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211816, People's Republic of China
| | - Kequan Chen
- State Key Laboratory of Materials Oriented Chemical Engineering, Nanjing, 211816, People's Republic of China. .,College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211816, People's Republic of China.
| | - Xin Wang
- State Key Laboratory of Materials Oriented Chemical Engineering, Nanjing, 211816, People's Republic of China.,College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211816, People's Republic of China
| | - Pingkai Ouyang
- State Key Laboratory of Materials Oriented Chemical Engineering, Nanjing, 211816, People's Republic of China.,College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211816, People's Republic of China
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Sudhakara S, Chadha A. A carbonyl reductase from Candida parapsilosis ATCC 7330: substrate selectivity and enantiospecificity. Org Biomol Chem 2017; 15:4165-4171. [DOI: 10.1039/c7ob00340d] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A purified carbonyl reductase (SRED) asymmetrically reduces ketones and α-ketoesters to (S)-alcohols with a potential application in the synthesis of industrially important chiral molecules.
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Affiliation(s)
- Sneha Sudhakara
- Laboratory of Bioorganic Chemistry
- Department of Biotechnology
- Indian Institute of Technology Madras
- Chennai 600 036
- India
| | - Anju Chadha
- Laboratory of Bioorganic Chemistry
- Department of Biotechnology
- Indian Institute of Technology Madras
- Chennai 600 036
- India
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8
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Candida parapsilosis: A versatile biocatalyst for organic oxidation-reduction reactions. Bioorg Chem 2016; 68:187-213. [DOI: 10.1016/j.bioorg.2016.08.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 08/08/2016] [Accepted: 08/10/2016] [Indexed: 11/22/2022]
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9
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Zhang R, Wang L, Xu Y, Liang H, Zhou X, Jiang J, Li Y, Xiao R, Ni Y. In situ expression of (R)-carbonyl reductase rebalancing an asymmetric pathway improves stereoconversion efficiency of racemic mixture to (S)-phenyl-1,2-ethanediol in Candida parapsilosis CCTCC M203011. Microb Cell Fact 2016; 15:143. [PMID: 27534936 PMCID: PMC4989518 DOI: 10.1186/s12934-016-0539-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 08/03/2016] [Indexed: 12/05/2022] Open
Abstract
Background Candida parapsilosis (R)-carbonyl reductase (RCR) and (S)-carbonyl reductase (SCR) are involved in the stereoconversion of racemic (R,S)-1-phenyl-1,2-ethanediol (PED) to its (S)-isomer. RCR catalyzes (R)-PED to 2-hydroxyacetophenone (2-HAP), and SCR catalyzes 2-HAP to (S)-PED. However, the stereoconversion efficiency of racemic mixture to (S)-PED is not high because of an activity imbalance between RCR and SCR, with RCR performing at a lower rate than SCR. To realize the efficient preparation of racemic mixture to (S)-PED, an in situ expression of RCR and a two-stage control strategy were introduced to rebalance the RCR- and SCR-mediated pathways. Results An in situ expression plasmid pCP was designed and RCR was successfully expressed in C. parapsilosis. With respect to wild-type, recombinant C. parapsilosis/pCP-RCR exhibited over four-fold higher activity for catalyzing racemic (R,S)-PED to 2-HAP, while maintained the activity for catalyzing 2-HAP to (S)-PED. The ratio of kcat/KM for SCR catalyzing (R)-PED and RCR catalyzing 2-HAP was about 1.0, showing the good balance between the functions of SCR and RCR. Based on pH and temperature preferences of RCR and SCR, a two-stage control strategy was devised, where pH and temperature were initially set at 5.0 and 30 °C for RCR rapidly catalyzing racemic PED to 2-HAP, and then adjusted to 4.5 and 35 °C for SCR transforming 2-HAP to (S)-PED. Using these strategies, the recombinant C. parapsilosis/pCP-RCR catalyzed racemic PED to its (S)-isomer with an optical purity of 98.8 % and a yield of 48.4 %. Most notably, the biotransformation duration was reduced from 48 to 13 h. Conclusions We established an in situ expression system for RCR in C. parapsilosis to rebalance the functions between RCR and SCR. Then we designed a two-stage control strategy based on pH and temperature preferences of RCR and SCR, better rebalancing RCR and SCR-mediated chiral biosynthesis pathways. This work demonstrates a method to improve chiral biosyntheses via in situ expression of rate-limiting enzyme and a multi-stage control strategy to rebalance asymmetric pathways. Electronic supplementary material The online version of this article (doi:10.1186/s12934-016-0539-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Rongzhen Zhang
- Key Laboratory of Industrial Biotechnology of Ministry of Education and School of Biotechnology, Jiangnan University, Wuxi, 214122, People's Republic of China. .,National Key Laboratory for Food Science, Jiangnan University, Wuxi, 214122, People's Republic of China. .,School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, People's Republic of China.
| | - Lei Wang
- Key Laboratory of Industrial Biotechnology of Ministry of Education and School of Biotechnology, Jiangnan University, Wuxi, 214122, People's Republic of China
| | - Yan Xu
- Key Laboratory of Industrial Biotechnology of Ministry of Education and School of Biotechnology, Jiangnan University, Wuxi, 214122, People's Republic of China. .,National Key Laboratory for Food Science, Jiangnan University, Wuxi, 214122, People's Republic of China. .,School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, People's Republic of China.
| | - Hongbo Liang
- Key Laboratory of Industrial Biotechnology of Ministry of Education and School of Biotechnology, Jiangnan University, Wuxi, 214122, People's Republic of China
| | - Xiaotian Zhou
- Key Laboratory of Industrial Biotechnology of Ministry of Education and School of Biotechnology, Jiangnan University, Wuxi, 214122, People's Republic of China
| | - Jiawei Jiang
- Key Laboratory of Industrial Biotechnology of Ministry of Education and School of Biotechnology, Jiangnan University, Wuxi, 214122, People's Republic of China
| | - Yaohui Li
- Key Laboratory of Industrial Biotechnology of Ministry of Education and School of Biotechnology, Jiangnan University, Wuxi, 214122, People's Republic of China
| | - Rong Xiao
- Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, NJ, 08854, USA
| | - Ye Ni
- Key Laboratory of Industrial Biotechnology of Ministry of Education and School of Biotechnology, Jiangnan University, Wuxi, 214122, People's Republic of China
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10
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Redesigning alcohol dehydrogenases/reductases for more efficient biosynthesis of enantiopure isomers. Biotechnol Adv 2015; 33:1671-84. [DOI: 10.1016/j.biotechadv.2015.08.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 08/11/2015] [Accepted: 08/12/2015] [Indexed: 11/20/2022]
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11
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Zhang R, Zhang B, Xu Y, Li Y, Li M, Liang H, Xiao R. Efficicent (R)-phenylethanol production with enantioselectivity-alerted (S)-carbonyl reductase II and NADPH regeneration. PLoS One 2013; 8:e83586. [PMID: 24358299 PMCID: PMC3866161 DOI: 10.1371/journal.pone.0083586] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 11/13/2013] [Indexed: 11/19/2022] Open
Abstract
The NADPH-dependent (S)-carbonyl reductaseII from Candida parapsilosis catalyzes acetophenone to chiral phenylethanol in a very low yield of 3.2%. Site-directed mutagenesis was used to design two mutants Ala220Asp and Glu228Ser, inside or adjacent to the substrate-binding pocket. Both mutations caused a significant enantioselectivity shift toward (R)-phenylethanol in the reduction of acetophenone. The variant E228S produced (R)-phenylethanol with an optical purity above 99%, in 80.2% yield. The E228S mutation resulted in a 4.6-fold decrease in the K M value, but nearly 5-fold and 21-fold increases in the k cat and k cat/K M values with respect to the wild type. For NADPH regeneration, Bacillus sp. YX-1 glucose dehydrogenase was introduced into the (R)-phenylethanol pathway. A coexpression system containing E228S and glucose dehydrogenase was constructed. The system was optimized by altering the coding gene order on the plasmid and using the Shine-Dalgarno sequence and the aligned spacing sequence as a linker between them. The presence of glucose dehydrogenase increased the NADPH concentration slightly and decreased NADP(+) pool 2- to 4-fold; the NADPH/NADP(+) ratio was improved 2- to 5-fold. The recombinant Escherichia coli/pET-MS-SD-AS-G, with E228S located upstream and glucose dehydrogenase downstream, showed excellent performance, giving (R)-phenylethanol of an optical purity of 99.5 % in 92.2% yield in 12 h in the absence of an external cofactor. When 0.06 mM NADP(+) was added at the beginning of the reaction, the reaction duration was reduced to 1 h. Optimization of the coexpression system stimulated an over 30-fold increase in the yield of (R)-phenylethanol, and simultaneously reduced the reaction time 48-fold compared with the wild-type enzyme. This report describes possible mechanisms for alteration of the enantiopreferences of carbonyl reductases by site mutation, and cofactor rebalancing pathways for efficient chiral alcohols production.
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Affiliation(s)
- Rongzhen Zhang
- Key Laboratory of Industrial Biotechnology of Ministry of Education & School of Biotechnology, Jiangnan University, Wuxi, P. R. China
- National Key Laboratory for Food Science, Jiangnan University, Wuxi, P. R. China
| | - Botao Zhang
- Key Laboratory of Industrial Biotechnology of Ministry of Education & School of Biotechnology, Jiangnan University, Wuxi, P. R. China
- Tianjin Institute of Industrial Biotechnology, The Chinese Academy of Sciences, Tianjin, P. R. China
| | - Yan Xu
- Key Laboratory of Industrial Biotechnology of Ministry of Education & School of Biotechnology, Jiangnan University, Wuxi, P. R. China
- National Key Laboratory for Food Science, Jiangnan University, Wuxi, P. R. China
| | - Yaohui Li
- Key Laboratory of Industrial Biotechnology of Ministry of Education & School of Biotechnology, Jiangnan University, Wuxi, P. R. China
- National Key Laboratory for Food Science, Jiangnan University, Wuxi, P. R. China
| | - Ming Li
- Key Laboratory of Industrial Biotechnology of Ministry of Education & School of Biotechnology, Jiangnan University, Wuxi, P. R. China
- National Key Laboratory for Food Science, Jiangnan University, Wuxi, P. R. China
| | - Hongbo Liang
- Key Laboratory of Industrial Biotechnology of Ministry of Education & School of Biotechnology, Jiangnan University, Wuxi, P. R. China
- National Key Laboratory for Food Science, Jiangnan University, Wuxi, P. R. China
| | - Rong Xiao
- Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, New Jersey, United States of America
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Engineering NAD+ availability for Escherichia coli whole-cell biocatalysis: a case study for dihydroxyacetone production. Microb Cell Fact 2013; 12:103. [PMID: 24209782 PMCID: PMC3831814 DOI: 10.1186/1475-2859-12-103] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 11/05/2013] [Indexed: 01/29/2023] Open
Abstract
Background Whole-cell redox biocatalysis has been intensively explored for the production of valuable compounds because excellent selectivity is routinely achieved. Although the cellular cofactor level, redox state and the corresponding enzymatic activity are expected to have major effects on the performance of the biocatalysts, our ability remains limited to predict the outcome upon variation of those factors as well as the relationship among them. Results In order to investigate the effects of cofactor availability on whole-cell redox biocatalysis, we devised recombinant Escherichia coli strains for the production of dihydroxyacetone (DHA) catalyzed by the NAD+-dependent glycerol dehydrogenase (GldA). In this model system, a water-forming NAD+ oxidase (NOX) and a NAD+ transporter (NTT4) were also co-expressed for cofactor regeneration and extracellular NAD+ uptake, respectively. We found that cellular cofactor level, NAD+/NADH ratio and NOX activity were not only strain-dependent, but also growth condition-dependent, leading to significant differences in specific DHA titer among different whole-cell biocatalysts. The host E. coli DH5α had the highest DHA specific titer of 0.81 g/gDCW with the highest NAD+/NADH ratio of 6.7 and NOX activity of 3900 U. The biocatalyst had a higher activity when induced with IPTG at 37°C for 8 h compared with those at 30°C for 8 h and 18 h. When cells were transformed with the ntt4 gene, feeding NAD+ during the cell culture stage increased cellular NAD(H) level by 1.44 fold and DHA specific titer by 1.58 fold to 2.13 g/gDCW. Supplementing NAD+ during the biotransformation stage was also beneficial to cellular NAD(H) level and DHA production, and the highest DHA productivity reached 0.76 g/gDCW/h. Cellular NAD(H) level, NAD+/NADH ratio, and NOX and GldA activity dropped over time during the biotransformation process. Conclusions High NAD+/NADH ratio driving by NOX was very important for DHA production. Once cofactor was efficiently cycled, high cellular NAD(H) level was also beneficial for whole-cell redox biocatalysis. Our results indicated that NAD+ transporter could be applied to manipulate redox cofactor level for biocatalysis. Moreover, we suggested that genetically designed redox transformation should be carefully profiled for further optimizing whole-cell biocatalysis.
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He YC, Ma CL, Zhang X, Li L, Xu JH, Wu MX. Highly enantioselective oxidation of racemic phenyl-1,2-ethanediol to optically pure (R)-(-)-mandelic acid by a newly isolated Brevibacterium lutescens CCZU12-1. Appl Microbiol Biotechnol 2013; 97:7185-94. [PMID: 23760530 DOI: 10.1007/s00253-013-4989-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 05/06/2013] [Accepted: 05/07/2013] [Indexed: 01/06/2023]
Abstract
Enantioselective oxidation of racemic phenyl-1,2-ethanediol into (R)-(-)-mandelic acid by a newly isolated Brevibacterium lutescens CCZU12-1 was demonstrated. It was found that optically active (R)-(-)-mandelic acid (e.e.p > 99.9 %) is produced leaving the other enantiomer (S)-(+)-phenyl-1,2-ethanediol intact. Using fed-batch method, a total of 172.9 mM (R)-(-)-mandelic acid accumulated in the reaction mixture after the seventh feed. Moreover, oxidation of phenyl-1,2-ethanediol using calcium alginate-entrapped resting cells was carried out in the aqueous system, and efficient biocatalyst recycling was achieved as a result of cell immobilization in calcium alginate, with a product-to-biocatalyst ratio of 27.94 g (R)-(-)-mandelic acid g⁻¹ dry cell weight cell after 16 cycles of repeated use.
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Affiliation(s)
- Yu-Cai He
- Laboratory of Biochemical Engineering, College of Pharmaceutical and Life Sciences, Changzhou University, Changzhou 213164, China.
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