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Zhao M, Zhu Y, Wang H, Zhang W, Mu W. Recent advances on N-acetylneuraminic acid: Physiological roles, applications, and biosynthesis. Synth Syst Biotechnol 2023; 8:509-519. [PMID: 37502821 PMCID: PMC10369400 DOI: 10.1016/j.synbio.2023.06.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2023] [Revised: 06/22/2023] [Accepted: 06/27/2023] [Indexed: 07/29/2023] Open
Abstract
N-Acetylneuraminic acid (Neu5Ac), the most common type of Sia, generally acts as the terminal sugar in cell surface glycans, glycoconjugates, oligosaccharides, lipo-oligosaccharides, and polysaccharides, thus exerting numerous physiological functions. The extensive applications of Neu5Ac in the food, cosmetic, and pharmaceutical industries make large-scale production of this chemical desirable. Biosynthesis which is associated with important application potential and environmental friendliness has become an indispensable approach for large-scale synthesis of Neu5Ac. In this review, the physiological roles of Neu5Ac was first summarized in detail. Second, the safety evaluation, regulatory status, and applications of Neu5Ac were discussed. Third, enzyme-catalyzed preparation, whole-cell biocatalysis, and microbial de novo synthesis of Neu5Ac were comprehensively reviewed. In addition, we discussed the main challenges of Neu5Ac de novo biosynthesis, such as screening and engineering of key enzymes, identifying exporters of intermediates and Neu5Ac, and balancing cell growth and biosynthesis. The corresponding strategies and systematic strategies were proposed to overcome these challenges and facilitate Neu5Ac industrial-scale production.
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Affiliation(s)
- Mingli Zhao
- State Key Laboratory of Food Science and Resources, Jiangnan University, Wuxi, Jiangsu, 214122, PR China
| | - Yingying Zhu
- State Key Laboratory of Food Science and Resources, Jiangnan University, Wuxi, Jiangsu, 214122, PR China
| | - Hao Wang
- Bloomage Biotechnology Corp., Ltd., Jinan, Shandong, 250010, PR China
| | - Wenli Zhang
- State Key Laboratory of Food Science and Resources, Jiangnan University, Wuxi, Jiangsu, 214122, PR China
| | - Wanmeng Mu
- State Key Laboratory of Food Science and Resources, Jiangnan University, Wuxi, Jiangsu, 214122, PR China
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2
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Peng S, Chu Z, Lu J, Li D, Wang Y, Yang S, Zhang Y. Overexpression of chaperones GroEL/ES from Escherichia coli enhances indigo biotransformation production of cytochrome P450 BM3 mutant. Biotechnol Lett 2023:10.1007/s10529-023-03397-5. [PMID: 37243776 DOI: 10.1007/s10529-023-03397-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Revised: 04/08/2023] [Accepted: 05/11/2023] [Indexed: 05/29/2023]
Abstract
The self-sufficient cytochrome P450 BM3 mutant (A74G/F87V/D168H/L188Q) can serve as a biocatalyst for whole-cell catalysis process of indigo. Nevertheless, the bioconversion yield of indigo is generally low under normal cultivation conditions (37 °C, 250 rpm). In this study, a recombinant E. coli BL21(DE3) strain was constructed to co-express the P450 BM3 mutant gene and GroEL/ES genes to investigate whether GroEL/ES can promote the indigo bioconversion yield in E. coli. The results revealed that the GroEL/ES system could significantly increase the indigo bioconversion yield, and the indigo bioconversion yield of the strain co-expressing P450 BM3 mutant and GroEL/ES was about 21-fold that of the strain only expressing the P450 BM3 mutant. In addition, the P450 BM3 enzyme content and in vitro indigo bioconversion yield were determined to explore the underlying mechanism for the improvement of indigo bioconversion yield. The results revealed that GroEL/ES did not increase indigo bioconversion yield by increasing the content of P450 BM3 enzyme and its enzymatic transformation efficiency. Moreover, GroEL/ES could improve the intracellular nicotinamide adenine dinucleotide phosphate (NADPH)/NADP+ ratio. Given that NADPH is an important coenzyme in the catalytic process of indigo, the underlying mechanism for the improvement of indigo bioconversion yield is probably related to an increase in the intracellular NADPH/NADP+ ratio.
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Affiliation(s)
- Shuaiying Peng
- Department of Biological Sciences and Biotechnology, Jiangxi Agricultural University, NO.1101 Fangzhimin Avenue, Nanchang, 330045, China.
| | - Zhongmei Chu
- Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, NO.500 Caobao Road, Shanghai, 200233, China
| | - Jianfeng Lu
- Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, NO.500 Caobao Road, Shanghai, 200233, China
| | - Dongxiao Li
- Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, NO.500 Caobao Road, Shanghai, 200233, China
| | - Yonghong Wang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China
| | - Shengli Yang
- Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, NO.500 Caobao Road, Shanghai, 200233, China
| | - Yi Zhang
- Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, NO.500 Caobao Road, Shanghai, 200233, China.
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Mital S, Christie G, Dikicioglu D. Recombinant expression of insoluble enzymes in Escherichia coli: a systematic review of experimental design and its manufacturing implications. Microb Cell Fact 2021; 20:208. [PMID: 34717620 PMCID: PMC8557517 DOI: 10.1186/s12934-021-01698-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 10/22/2021] [Indexed: 02/06/2023] Open
Abstract
Recombinant enzyme expression in Escherichia coli is one of the most popular methods to produce bulk concentrations of protein product. However, this method is often limited by the inadvertent formation of inclusion bodies. Our analysis systematically reviews literature from 2010 to 2021 and details the methods and strategies researchers have utilized for expression of difficult to express (DtE), industrially relevant recombinant enzymes in E. coli expression strains. Our review identifies an absence of a coherent strategy with disparate practices being used to promote solubility. We discuss the potential to approach recombinant expression systematically, with the aid of modern bioinformatics, modelling, and ‘omics’ based systems-level analysis techniques to provide a structured, holistic approach. Our analysis also identifies potential gaps in the methods used to report metadata in publications and the impact on the reproducibility and growth of the research in this field.
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Affiliation(s)
- Suraj Mital
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS, UK
| | - Graham Christie
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS, UK
| | - Duygu Dikicioglu
- Department of Biochemical Engineering, University College London, London, WC1E 6BT, UK.
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Obst F, Mertz M, Mehner PJ, Beck A, Castiglione K, Richter A, Voit B, Appelhans D. Enzymatic Synthesis of Sialic Acids in Microfluidics to Overcome Cross-Inhibitions and Substrate Supply Limitations. ACS APPLIED MATERIALS & INTERFACES 2021; 13:49433-49444. [PMID: 34612033 DOI: 10.1021/acsami.1c12307] [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: 05/19/2023]
Abstract
Multienzymatic cascade reactions are a powerful strategy for straightforward and highly specific synthesis of complex materials, such as active substances in drugs. Cross-inhibitions and incompatible reaction steps, however, often limit enzymatic activity and thus the conversion. Such limitations occur, e.g., in the enzymatic synthesis of the biologically active sialic acid cytidine monophosphate N-acetylneuraminic acid (CMP-Neu5Ac). We addressed this challenge by developing a confinement and compartmentalization concept of hydrogel-immobilized enzymes for improving the efficiency of the enzyme cascade reaction. The three enzymes required for the synthesis of CMP-Neu5Ac, namely, N-acyl-d-glucosamine 2-epimerase (AGE), N-acetylneuraminate lyase (NAL), and CMP-sialic acid synthetase (CSS), were immobilized into bulk hydrogels and microstructured hydrogel-enzyme-dot arrays, which were then integrated into microfluidic devices. To overcome the cytidine triphosphate (CTP) cross-inhibition of AGE and NAL, only a low CTP concentration was applied and continuously conveyed through the device. In a second approach, the enzymes were compartmentalized in separate reaction chambers of the microfluidic device to completely avoid cross-inhibitions and enable the use of higher substrate concentrations. Immobilization efficiencies of up to 25% and pronounced long-term activity of the immobilized enzymes for several weeks were realized. Moreover, immobilized enzymes were less sensitive to inhibition and the substrate-channeling effect between immobilized enzymes promoted the overall conversion in the trienzymatic cascade reaction. Based on this, CMP-Neu5Ac was successfully synthesized by immobilized enzymes in noncompartmentalized and compartmentalized microfluidic devices. This study demonstrates the high potential of immobilizing enzymes in (compartmentalized) microfluidic devices to perform multienzymatic cascade reactions despite cross-inhibitions under continuous flow conditions. Due to the ease of enzyme immobilization in hydrogels, this concept is likely applicable for many cascade reactions with or without cross-inhibition characteristics.
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Affiliation(s)
- Franziska Obst
- Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, 01069 Dresden, Germany
- Organische Chemie der Polymere, Technische Universität Dresden, Mommsenstraße 4, 01062 Dresden, Germany
| | - Michael Mertz
- Lehrstuhl für Bioverfahrenstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Paul-Gordan-Straße 3, 91052 Erlangen, Germany
| | - Philipp J Mehner
- Institut für Halbleiter- und Mikrosystemtechnik, Technische Universität Dresden, Nöthnitzer Straße 64, 01187 Dresden, Germany
| | - Anthony Beck
- Institut für Halbleiter- und Mikrosystemtechnik, Technische Universität Dresden, Nöthnitzer Straße 64, 01187 Dresden, Germany
| | - Kathrin Castiglione
- Lehrstuhl für Bioverfahrenstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Paul-Gordan-Straße 3, 91052 Erlangen, Germany
| | - Andreas Richter
- Institut für Halbleiter- und Mikrosystemtechnik, Technische Universität Dresden, Nöthnitzer Straße 64, 01187 Dresden, Germany
| | - Brigitte Voit
- Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, 01069 Dresden, Germany
- Organische Chemie der Polymere, Technische Universität Dresden, Mommsenstraße 4, 01062 Dresden, Germany
| | - Dietmar Appelhans
- Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, 01069 Dresden, Germany
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Fatima K, Naqvi F, Younas H. A Review: Molecular Chaperone-mediated Folding, Unfolding and Disaggregation of Expressed Recombinant Proteins. Cell Biochem Biophys 2021; 79:153-174. [PMID: 33634426 DOI: 10.1007/s12013-021-00970-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 02/01/2021] [Indexed: 12/26/2022]
Abstract
The advancements in biotechnology over time have led to an increase in the demand of pure, soluble and functionally active proteins. Recombinant protein production has thus been employed to obtain high expression of purified proteins in bulk. E. coli is considered as the most desirable host for recombinant protein production due to its inexpensive and fast cultivation, simple nutritional requirements and known genetics. Despite all these benefits, recombinant protein production often comes with drawbacks, such as, the most common being the formation of inclusion bodies due to improper protein folding. Consequently, this can lead to the loss of the structure-function relationship of a protein. Apart from various strategies, one major strategy to resolve this issue is the use of molecular chaperones that act as folding modulators for proteins. Molecular chaperones assist newly synthesized, aggregated or misfolded proteins to fold into their native conformations. Chaperones have been widely used to improve the expression of various proteins which are otherwise difficult to produce in E. coli. Here, we discuss the structure, function, and role of major E. coli molecular chaperones in recombinant technology such as trigger factor, GroEL, DnaK and ClpB.
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Affiliation(s)
- Komal Fatima
- Department of Biochemistry, Kinnaird College for Women, Lahore, Punjab, Pakistan
| | - Fatima Naqvi
- Department of Biochemistry, Kinnaird College for Women, Lahore, Punjab, Pakistan
| | - Hooria Younas
- Department of Biochemistry, Kinnaird College for Women, Lahore, Punjab, Pakistan.
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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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7
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Gao X, Zhang F, Wu M, Wu Z, Shang G. Production of N-Acetyl-d-neuraminic Acid by Whole Cells Expressing Bacteroides thetaiotaomicron N-Acetyl-d-glucosamine 2-Epimerase and Escherichia coli N-Acetyl-d-neuraminic Acid Aldolase. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2019; 67:6285-6291. [PMID: 31117501 DOI: 10.1021/acs.jafc.9b01839] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
N-Acetyl-d-neuraminic acid (Neu5Ac) is a potential baby nutrient and the key precursor of antiflu medicine Zanamivir. The Neu5Ac chemoenzymatic synthesis consists of N-acetyl-d-glucosamine epimerase (AGE)-catalyzed epimerization of N-acetyl-d-glucosamine (GlcNAc) to N-acetyl-d-mannosamine (ManNAc) and aldolase-catalyzed condensation between ManNAc and pyruvate. Herein, we cloned and characterized BT0453, a novel AGE, from a human gut symbiont Bacteroides thetaiotaomicron. BT0453 shows the highest soluble fraction among the AGEs tested. With GlcNAc and sodium pyruvate as substrates, Neu5Ac production by coupling whole cells expressing BT0453 and Escherichia coli N-acetyl-d-neuraminic acid aldolase was explored. After 36 h, a 53.6% molar yield, 3.6 g L-1 h-1 productivity and 42.9 mM titer of Neu5Ac were obtained. Furthermore, for the first time, the T7- BT0453-T7- nanA polycistronic unit was integrated into the E. coli genome, generating a chromosome-based biotransformation system. BT0453 protein engineering and metabolic engineering studies hold potential for the industrial production of Neu5Ac.
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Affiliation(s)
- Xinyue Gao
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences , Nanjing Normal University , Nanjing 210023 , China
| | - Feifei Zhang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences , Nanjing Normal University , Nanjing 210023 , China
| | - Meng Wu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences , Nanjing Normal University , Nanjing 210023 , China
| | - Zhixin Wu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences , Nanjing Normal University , Nanjing 210023 , China
| | - Guangdong Shang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences , Nanjing Normal University , Nanjing 210023 , China
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8
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Halsør MJH, Rothweiler U, Altermark B, Raeder ILU. The crystal structure of the N-acetylglucosamine 2-epimerase from Nostoc sp. KVJ10 reveals the true dimer. Acta Crystallogr D Struct Biol 2019; 75:90-100. [PMID: 30644848 PMCID: PMC6333288 DOI: 10.1107/s2059798318017047] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 11/30/2018] [Indexed: 11/12/2022] Open
Abstract
N-Acetylglucosamine 2-epimerases (AGEs) catalyze the interconversion of N-acetylglucosamine and N-acetylmannosamine. They can be used to perform the first step in the synthesis of sialic acid from N-acetylglucosamine, which makes the need for efficient AGEs a priority. This study presents the structure of the AGE from Nostoc sp. KVJ10 collected in northern Norway, referred to as nAGE10. It is the third AGE structure to be published to date, and the first one in space group P42212. The nAGE10 monomer folds as an (α/α)6 barrel in a similar manner to that of the previously published AGEs, but the crystal did not contain the dimers that have previously been reported. The previously proposed `back-to-back' assembly involved the face of the AGE monomer where the barrel helices are connected by small loops. Instead, a `front-to-front' dimer was found in nAGE10 involving the long loops that connect the barrel helices at this end. This assembly is also present in the other AGE structures, but was attributed to crystal packing, even though the `front' interface areas are larger and are more conserved than the `back' interface areas. In addition, the front-to-front association allows a better explanation of the previously reported observations considering surface cysteines. Together, these results indicate that the `front-to-front' dimer is the most probable biological assembly for AGEs.
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Affiliation(s)
- Marie-Josée Haglund Halsør
- The Norwegian Structural Biology Centre (NorStruct), Department of Chemistry, UiT – The Arctic University of Norway, 9037 Tromsø, Norway
| | - Ulli Rothweiler
- The Norwegian Structural Biology Centre (NorStruct), Department of Chemistry, UiT – The Arctic University of Norway, 9037 Tromsø, Norway
| | - Bjørn Altermark
- The Norwegian Structural Biology Centre (NorStruct), Department of Chemistry, UiT – The Arctic University of Norway, 9037 Tromsø, Norway
| | - Inger Lin Uttakleiv Raeder
- The Norwegian Structural Biology Centre (NorStruct), Department of Chemistry, UiT – The Arctic University of Norway, 9037 Tromsø, Norway
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Poschenrieder ST, Klermund L, Langer B, Castiglione K. Determination of Permeability Coefficients of Polymersomal Membranes for Hydrophilic Molecules. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:6011-6020. [PMID: 28509557 DOI: 10.1021/acs.langmuir.6b04598] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Polymer vesicles, so-called polymersomes, can be applied as carrier-systems and universal reaction compartments, due to the possibility to encapsulate guest molecules. Compared to common lipid vesicles, polymersomes show an increased stability and decreased membrane permeability. Control of the mass transport across the membrane is necessary for any application, requiring the precise knowledge of the permeability. So far, data on permeability coefficients of polymersomal membranes are scarce because commonly applied release assays are confronted with the challenge of high detection limits and alternative methods developed so far are either restricted to the use of a certain permeating molecule or rely on the use of nuclear magnetic resonance measurements. In contrast, an influx assay that is broadly applicable to hydrophilic molecules and does not involve specialized equipment was developed in this work, which is based on the passive diffusion of compounds into initially empty vesicles. The method is valid for hydrophilic molecules that show no membrane retention and, thus, do not accumulate within the membrane. Using this method, the permeability of polymersomes made of poly(2-methyloxazoline)15-poly(dimethylsiloxane)68-poly(2-methyloxazoline)15 for seven model compounds was investigated under varying conditions. Permeability coefficients as low as 1.9 × 10-14 cm s-1 could be measured.
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Affiliation(s)
- Sarah T Poschenrieder
- Institute of Biochemical Engineering, Technical University of Munich , Boltzmannstraße 15, 85748 Garching, Germany
| | - Ludwig Klermund
- Institute of Biochemical Engineering, Technical University of Munich , Boltzmannstraße 15, 85748 Garching, Germany
| | - Bettina Langer
- Institute of Biochemical Engineering, Technical University of Munich , Boltzmannstraße 15, 85748 Garching, Germany
| | - Kathrin Castiglione
- Institute of Biochemical Engineering, Technical University of Munich , Boltzmannstraße 15, 85748 Garching, Germany
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Schmideder A, Schottroff F, Klermund L, Castiglione K, Weuster-Botz D. Studies on the enzymatic synthesis of N-acetylneuraminic acid with continuously operated enzyme membrane reactors on a milliliter scale. Biochem Eng J 2017. [DOI: 10.1016/j.bej.2016.12.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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11
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N-acetylglucosamine 2-Epimerase from Pedobacter heparinus: First Experimental Evidence of a Deprotonation/Reprotonation Mechanism. Catalysts 2016. [DOI: 10.3390/catal6120212] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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12
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Klermund L, Riederer A, Hunger A, Castiglione K. Protein engineering of a bacterial N-acyl-d-glucosamine 2-epimerase for improved stability under process conditions. Enzyme Microb Technol 2016; 87-88:70-8. [PMID: 27178797 DOI: 10.1016/j.enzmictec.2016.04.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 04/07/2016] [Accepted: 04/11/2016] [Indexed: 01/29/2023]
Abstract
Enzymatic cascade reactions, i.e. the combination of several enzyme reactions in one pot without isolation of intermediates, have great potential for the establishment of sustainable chemical processes. However, many cascade reactions suffer from cross-inhibitions and enzyme inactivation by components of the reaction system. This study focuses on the two-step enzymatic synthesis of N-acetylneuraminic acid (Neu5Ac) using an N-acyl-d-glucosamine 2-epimerase from Anabaena variabilis ATCC 29413 (AvaAGE) in combination with an N-acetylneuraminate lyase (NAL) from Escherichia coli. AvaAGE epimerizes N-acetyl-d-glucosamine (GlcNAc) to N-acetyl-d-mannosamine (ManNAc), which then reacts with pyruvate in a NAL-catalyzed aldol condensation to form Neu5Ac. However, AvaAGE is inactivated by high pyruvate concentrations, which are used to push the NAL reaction toward the product side. A biphasic inactivation was observed in the presence of 50-800mM pyruvate resulting in activity losses of the AvaAGE of up to 60% within the first hour. Site-directed mutagenesis revealed that pyruvate modifies one of the four lysine residues in the ATP-binding site of AvaAGE. Because ATP is an allosteric activator of the epimerase and the binding of the nucleotide is crucial for its catalytic properties, saturation mutagenesis at position K160 was performed to identify the most compatible amino acid exchanges. The best variants, K160I, K160N and K160L, showed no inactivation by pyruvate, but significantly impaired kinetic parameters. For example, depending on the mutant, the turnover number kcat was reduced by 51-68% compared with the wild-type enzyme. A mechanistic model of the Neu5Ac synthesis was established, which can be used to select the AvaAGE variant that is most favorable for a given process condition. The results show that mechanistic models can greatly facilitate the choice of the right enzyme for an enzymatic cascade reaction with multiple cross-inhibitions and inactivation phenomena.
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Affiliation(s)
- Ludwig Klermund
- Institute of Biochemical Engineering, Technische Universität München, Boltzmannstr. 15, 85748 Garching, Germany
| | - Amelie Riederer
- Institute of Biochemical Engineering, Technische Universität München, Boltzmannstr. 15, 85748 Garching, Germany
| | - Annique Hunger
- Institute of Biochemical Engineering, Technische Universität München, Boltzmannstr. 15, 85748 Garching, Germany
| | - Kathrin Castiglione
- Institute of Biochemical Engineering, Technische Universität München, Boltzmannstr. 15, 85748 Garching, Germany.
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