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Zhang L, Zhou R, Fu X, Zhang G, Zhang L, Zhou SF, Jiang W. Specific coenzyme preference switching for an aldo-keto reductase that synthesizes the chiral intermediate of duloxetine. Enzyme Microb Technol 2023; 171:110326. [PMID: 37717530 DOI: 10.1016/j.enzmictec.2023.110326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Revised: 09/07/2023] [Accepted: 09/11/2023] [Indexed: 09/19/2023]
Abstract
The synthesis of chiral intermediates for the traditional antidepressant duloxetine has gained significant attention as the number of depressed patients continues to grow. S-N, N-Dimethyl-3-hydroxy-3-(2-thienyl)-1-propanamide (S-DHTP) is a critical intermediate in the synthesis of duloxetine, and the chemical synthesis process is complex and environmentally unfriendly. Reduced nicotinamide adenine dinucleotide phosphate (NADPH) is a major cost driver in the biocatalytic production of S-DHTP from N, N-Dimethyl-3-keto-3-(2-thienyl)-1-propanamide (DKTP). Here, we successfully modified the coenzyme preference of an aldo-keto reductase (AKR7-2-1) to use the cheaper reduced nicotinamide adenine dinucleotide (NADH) through a coenzyme preference modification approach. We utilized protein engineering to create a superior mutant, Y53F, which increased the coenzyme specificity of AKR7-2-1 by 875-fold and improved its thermal stability, enhancing its potential for industrial applications. Molecular dynamics simulations were performed to demonstrate the effect of mutations at key sites on the protein, revealing the altered coenzyme preference and increased thermal stability from structural and energetic changes. This study validates the viability of the coenzyme preference modification strategy for aldo-keto reductase, offering valuable insights for fellow researchers and guiding future investigations.
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Affiliation(s)
- Lingzhi Zhang
- College of Chemical Engineering, Huaqiao University, Xiamen 361021, Fujian Province, PR China
| | - Rui Zhou
- College of Chemical Engineering, Huaqiao University, Xiamen 361021, Fujian Province, PR China
| | - Xiaoli Fu
- College of Chemical Engineering, Huaqiao University, Xiamen 361021, Fujian Province, PR China
| | - Guangya Zhang
- College of Chemical Engineering, Huaqiao University, Xiamen 361021, Fujian Province, PR China
| | - Lijuan Zhang
- State Key Laboratory of Microbial Technology, Shandong University, No. 72 Binhai Road, Qingdao 266237, PR China
| | - Shu-Feng Zhou
- College of Chemical Engineering, Huaqiao University, Xiamen 361021, Fujian Province, PR China.
| | - Wei Jiang
- College of Chemical Engineering, Huaqiao University, Xiamen 361021, Fujian Province, PR China.
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2
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Trottmann F, Ishida K, Ishida-Ito M, Kries H, Groll M, Hertweck C. Pathogenic bacteria remodel central metabolic enzyme to build a cyclopropanol warhead. Nat Chem 2022; 14:884-890. [PMID: 35906404 PMCID: PMC9359912 DOI: 10.1038/s41557-022-01005-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 06/20/2022] [Indexed: 11/09/2022]
Abstract
Bacteria of the Burkholderia pseudomallei (BP) group pose a global health threat, causing the infectious diseases melioidosis, a common cause of pneumonia and sepsis, and glanders, a contagious zoonosis. A trait of BP bacteria is a conserved gene cluster coding for the biosynthesis of polyketides (malleicyprols) with a reactive cyclopropanol unit that is critical for virulence. Enzymes building this warhead represent ideal targets for antivirulence strategies but the biochemical basis of cyclopropanol formation is unknown. Here we describe the formation of the malleicyprol warhead. We show that BurG, an unusual NAD+-dependent member of the ketol-acid reductoisomerase family, constructs the strained cyclopropanol ring. Biochemical assays and a suite of eight crystal structures of native and mutated BurG with bound analogues and inhibitors provide snapshots of each step of the complex reaction mechanism, involving a concealed oxidoreduction and a C-S bond cleavage. Our findings illustrate a remarkable case of neofunctionalisation, where a biocatalyst from central metabolism has been evolutionarily repurposed for warhead production in pathogens.
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Affiliation(s)
- Felix Trottmann
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute (Leibniz-HKI), Jena, Germany
| | - Keishi Ishida
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute (Leibniz-HKI), Jena, Germany
| | - Mie Ishida-Ito
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute (Leibniz-HKI), Jena, Germany
| | - Hajo Kries
- Junior Research Group Biosynthetic Design of Natural Products, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute (Leibniz-HKI), Jena, Germany
| | - Michael Groll
- Center for Protein Assemblies, Chemistry Department, Technical University Munich, Garching, Germany.
| | - Christian Hertweck
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute (Leibniz-HKI), Jena, Germany. .,Faculty of Biological Sciences, Friedrich Schiller University Jena, Jena, Germany.
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Lemaire ON, Müller MC, Kahnt J, Wagner T. Structural Rearrangements of a Dodecameric Ketol-Acid Reductoisomerase Isolated from a Marine Thermophilic Methanogen. Biomolecules 2021; 11:1679. [PMID: 34827677 PMCID: PMC8615647 DOI: 10.3390/biom11111679] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 11/05/2021] [Accepted: 11/08/2021] [Indexed: 11/30/2022] Open
Abstract
Ketol-acid reductoisomerase (KARI) orchestrates the biosynthesis of branched-chain amino acids, an elementary reaction in prototrophic organisms as well as a valuable process in biotechnology. Bacterial KARIs belonging to class I organise as dimers or dodecamers and were intensively studied to understand their remarkable specificity towards NADH or NADPH, but also to develop antibiotics. Here, we present the first structural study on a KARI natively isolated from a methanogenic archaea. The dodecameric structure of 0.44-MDa was obtained in two different conformations, an open and close state refined to a resolution of 2.2-Å and 2.1-Å, respectively. These structures illustrate the conformational movement required for substrate and coenzyme binding. While the close state presents the complete NADP bound in front of a partially occupied Mg2+-site, the Mg2+-free open state contains a tartrate at the nicotinamide location and a bound NADP with the adenine-nicotinamide protruding out of the active site. Structural comparisons show a very high conservation of the active site environment and detailed analyses point towards few specific residues required for the dodecamerisation. These residues are not conserved in other dodecameric KARIs that stabilise their trimeric interface differently, suggesting that dodecamerisation, the cellular role of which is still unknown, might have occurred several times in the evolution of KARIs.
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Affiliation(s)
- Olivier Nicolas Lemaire
- Microbial Metabolism Research Group, Max Planck Institute for Marine Microbiology, Celsiusstraße 1, 28359 Bremen, Germany; (O.N.L.); (M.-C.M.)
| | - Marie-Caroline Müller
- Microbial Metabolism Research Group, Max Planck Institute for Marine Microbiology, Celsiusstraße 1, 28359 Bremen, Germany; (O.N.L.); (M.-C.M.)
| | - Jörg Kahnt
- Core Facility for Mass Spectrometry & Proteomics, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Straße 10, 35043 Marburg, Germany;
| | - Tristan Wagner
- Microbial Metabolism Research Group, Max Planck Institute for Marine Microbiology, Celsiusstraße 1, 28359 Bremen, Germany; (O.N.L.); (M.-C.M.)
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4
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Sawada K, Koyano H, Yamamoto N, Yamada T. The effects of vegetable pickling conditions on the dynamics of microbiota and metabolites. PeerJ 2021; 9:e11123. [PMID: 33868815 PMCID: PMC8034358 DOI: 10.7717/peerj.11123] [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: 12/23/2020] [Accepted: 02/26/2021] [Indexed: 01/04/2023] Open
Abstract
Background Salting is a traditional procedure for producing pickled vegetables. Salting can be used as a pretreatment, for safe lactic acid fermentation and for salt stock preparation. This study aimed to provide valuable knowledge to improve pickle production by investigating the dynamics of microbiota and metabolites during the pretreatment and salt stock preparation processes, which have previously been overlooked. The differences in these process conditions would be expected to change the microbiota and consequently influence the content of metabolites in pickles. Methods Samples, collected from eight commercial pickle manufacturers in Japan, consisted of the initial raw materials, pickled vegetables and used brine. The microbiota were analyzed by 16S rRNA sequencing and the metabolites quantified by liquid chromatograph-mass spectrometry. Statistical analyses helped to identify any significant differences between samples from the initial raw materials, pretreatment process and salt stock preparation process groups. Results Under pretreatment conditions, aerobic and facultative anaerobic bacteria were predominant, including Vibrio, a potentially undesirable genus for pickle production. Under salt stock preparation conditions, the presence of halophilic bacteria, Halanaerobium, suggested their involvement in the increase in pyruvate derivatives such as branched-chain amino acids (BCAA). PICRUSt analysis indicated that the enhanced production of BCAA in salt stock was caused not by quantitative but by qualitative differences in the biosynthetic pathway of BCAA in the microbiota. Conclusion The differences in the microbiota between pretreatment and previously studied lactic acid fermentation processes emphasized the importance of anaerobic conditions and low pH under moderate salinity conditions for assuring safe pickle production. The results from the salt stock preparation process suggested that the Halanaerobium present may provide a key enzyme in the BCAA biosynthetic pathway which prefers NADH as a coenzyme. This feature can enhance BCAA production under anaerobic conditions where NADH is in excess. The effects shown in this study will be important for adjusting pickling conditions by changing the abundance of bacteria to improve the quality of pickled vegetables.
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Affiliation(s)
- Kazunori Sawada
- Innovation Division, Gurunavi, Inc., Chiyoda-ku, Tokyo, Japan
| | - Hitoshi Koyano
- School of Life Science and Technology, Tokyo Institute of Technology, Meguro-ku, Tokyo, Japan
| | - Nozomi Yamamoto
- School of Life Science and Technology, Tokyo Institute of Technology, Meguro-ku, Tokyo, Japan
| | - Takuji Yamada
- School of Life Science and Technology, Tokyo Institute of Technology, Meguro-ku, Tokyo, Japan
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5
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Liang YF, Long ZX, Zhang YJ, Luo CY, Yan LT, Gao WY, Li H. The chemical mechanisms of the enzymes in the branched-chain amino acids biosynthetic pathway and their applications. Biochimie 2021; 184:72-87. [PMID: 33607240 DOI: 10.1016/j.biochi.2021.02.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 02/04/2021] [Accepted: 02/10/2021] [Indexed: 12/27/2022]
Abstract
l-Valine, l-isoleucine, and l-leucine are three key proteinogenic amino acids, and they are also the essential amino acids required for mammalian growth, possessing important and to some extent, special physiological and biological functions. Because of the branched structures in their carbon chains, they are also named as branched-chain amino acids (BCAAs). This review will highlight the advance in studies of the enzymes involved in the biosynthetic pathway of BCAAs, concentrating on their chemical mechanisms and applications in screening herbicides and antibacterial agents. The uses of some of these enzymes in lab scale organic synthesis are also discussed.
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Affiliation(s)
- Yan-Fei Liang
- College of Life Sciences, National Engineering Research Center for Miniaturized Detection Systems, Northwest University, Xi'an, 710069, China
| | - Zi-Xian Long
- College of Life Sciences, National Engineering Research Center for Miniaturized Detection Systems, Northwest University, Xi'an, 710069, China
| | - Ya-Jian Zhang
- College of Life Sciences, National Engineering Research Center for Miniaturized Detection Systems, Northwest University, Xi'an, 710069, China
| | - Cai-Yun Luo
- College of Life Sciences, National Engineering Research Center for Miniaturized Detection Systems, Northwest University, Xi'an, 710069, China
| | - Le-Tian Yan
- College of Life Sciences, National Engineering Research Center for Miniaturized Detection Systems, Northwest University, Xi'an, 710069, China
| | - Wen-Yun Gao
- College of Life Sciences, National Engineering Research Center for Miniaturized Detection Systems, Northwest University, Xi'an, 710069, China.
| | - Heng Li
- College of Life Sciences, National Engineering Research Center for Miniaturized Detection Systems, Northwest University, Xi'an, 710069, China.
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6
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Zabel BE, Gerdes S, Evans KC, Nedveck D, Singles SK, Volk B, Budinoff C. Strain-specific strategies of 2'-fucosyllactose, 3-fucosyllactose, and difucosyllactose assimilation by Bifidobacterium longum subsp. infantis Bi-26 and ATCC 15697. Sci Rep 2020; 10:15919. [PMID: 32985563 PMCID: PMC7522266 DOI: 10.1038/s41598-020-72792-z] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 09/02/2020] [Indexed: 02/07/2023] Open
Abstract
Human milk provides essential nutrients for infant nutrition. A large proportion of human milk is composed of human milk oligosaccharides (HMOs), which are resistant to digestion by the infant. Instead, HMOs act as a bioactive and prebiotic enriching HMO-utilizing bacteria and cause systematic changes in the host. Several species of Bifidobacterium have been shown to utilize HMOs by conserved, as well as species-specific pathways, but less work has been done to study variation within species or sub-species. B. longum subsp. infantis is a prevalent species in the breast-fed infant gut and the molecular mechanisms of HMO utilization for the type strain B. longum subsp. infantis ATCC 15697 (type strain) have been well characterized. We used growth, transcriptomic, and metabolite analysis to characterize key differences in the utilization of 2'FL, 3FL and DFL (FLs) between B. longum subsp. infantis Bi-26 (Bi-26) and the type strain. Bi-26 grows faster, produces unique metabolites, and has a distinct global gene transcription response to FLs compared to the type strain. Taken together the findings demonstrate major strain specific adaptations in Bi-26 to efficient utilization of FLs.
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Affiliation(s)
- Bryan E Zabel
- Genomics and Microbiome Science, DuPont Nutrition and Biosciences, Madison, WI, USA.
| | - Svetlana Gerdes
- Genomics and Microbiome Science, DuPont Nutrition and Biosciences, Madison, WI, USA
| | - Kara C Evans
- Genomics and Microbiome Science, DuPont Nutrition and Biosciences, Madison, WI, USA
| | - Derek Nedveck
- Genomics and Microbiome Science, DuPont Nutrition and Biosciences, Madison, WI, USA
| | | | - Barbara Volk
- Advanced Analytical, DuPont Nutrition and Biosciences, Wilmington, DE, USA
| | - Charles Budinoff
- Genomics and Microbiome Science, DuPont Nutrition and Biosciences, Madison, WI, USA
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7
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Crystal Structure of IlvC, a Ketol-Acid Reductoisomerase, from Streptococcus Pneumoniae. CRYSTALS 2019. [DOI: 10.3390/cryst9110551] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Biosynthesis of branched-chain amino acids (BCAAs), including isoleucine, leucine and valine, is required for survival and virulence of a bacterial pathogen such as Streptococcus pneumoniae. IlvC, a ketol-acid reductoisomerase (E.C. 1.1.1.86) with NADP(H) and Mg2+ as cofactors from the pathogenic Streptococcus pneumoniae (SpIlvC), catalyzes the second step in the BCAA biosynthetic pathway. To elucidate the structural basis for the IlvC-mediated reaction, we determined the crystal structure of SpIlvC at 1.69 Å resolution. The crystal structure of SpIlvC contains an asymmetric dimer in which one subunit is in apo-form and the other in NADP(H) and Mg2+-bound form. Crystallographic analysis combined with an activity assay and small-angle X-ray scattering suggested that SpIlvC retains dimeric arrangement in solution and that D83 in the NADP(H) binding site and E195 in the Mg2+ binding site are the most critical in the catalytic activity of SpIlvC. Crystal structures of SpIlvC mutants (R49E, D83G, D191G and E195S) revealed local conformational changes only in the NADP(H) binding site. Taken together, our results establish the molecular mechanism for understanding functions of SpIlvC in pneumococcal growth and virulence.
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8
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Yu MJ, Wu J, Chen SL. Mechanism and Inhibitor Exploration with Binuclear Mg Ketol-Acid Reductoisomerase: Targeting the Biosynthetic Pathway of Branched-Chain Amino Acids. Chembiochem 2019; 21:381-391. [PMID: 31309701 DOI: 10.1002/cbic.201900363] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Indexed: 01/01/2023]
Abstract
Binuclear Mg ketol-acid reductoisomerase (KARI), which converts (S)-2-acetolactate into (R)-2,3-dihydroxyisovalerate, is responsible for the second step of the biosynthesis of branched-chain amino acids in plants and microorganisms and thus serves as a key inhibition target potentially without effects on mammals. Here, through the use of density functional calculations and a chemical model, the KARI-catalyzed reaction has been demonstrated to include the initial deprotonation of the substrate C2 hydroxy group, bridged by the two Mg ions, alkyl migration from the C2-alkoxide carbon atom to the C3-carbonyl carbon atom, and hydride transfer from a nicotinamide adenine dinucleotide phosphate [NAD(P)H] cofactor to C2. A dead-end mechanism with a hydride transferred to the C3 carbonyl group has been ruled out. The nucleophilicity (migratory aptitude) of the migrating carbon atom and the provision of additional negative charge to the di-Mg coordination sphere have significant effects on the steps of alkyl migration and hydride transfer, respectively. Other important mechanistic characteristics are also revealed. Inspired by the mechanism, an inhibitor (2-carboxylate-lactic acid) was designed and predicted by barrier analysis to be effective in inactivating KARI, hence probably enriching the antifungal and antibacterial library. Two types of slow substrate analogues (2-trihalomethyl acetolactic acids and 2-glutaryl lactic acid) were also found.
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Affiliation(s)
- Ming-Jia Yu
- Key Laboratory of Cluster Science of the Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, P. R. China
| | - Jue Wu
- Key Laboratory of Cluster Science of the Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, P. R. China
| | - Shi-Lu Chen
- Key Laboratory of Cluster Science of the Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, P. R. China
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Deb SS, Reshamwala SMS, Lali AM. Activation of alternative metabolic pathways diverts carbon flux away from isobutanol formation in an engineered Escherichia coli strain. Biotechnol Lett 2019; 41:823-836. [PMID: 31093837 DOI: 10.1007/s10529-019-02683-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Accepted: 05/02/2019] [Indexed: 12/12/2022]
Abstract
OBJECTIVE Metabolic engineering efforts are guided by identifying gene targets for overexpression and/or deletion. Isobutanol, a biofuel candidate, is biosynthesized using the valine biosynthesis pathway and enzymes of the Ehrlich pathway. Most reported studies for isobutanol production in Escherichia coli employ multicopy plasmids, an approach that suffers from disadvantages such as plasmid instability, increased metabolic burden, and use of antibiotics to maintain selection pressure. Cofactor imbalance is another issue that may limit production of isobutanol, as two enzymes of the pathway utilize NADPH as a cofactor. RESULTS To address these issues, we constructed E. coli strains with chromosomally-integrated, codon-optimized isobutanol pathway genes (ilvGM, ilvC, kivd, adh) selected on the basis of their cofactor preferences. Genes involved in diverting pyruvate flux toward fermentation byproducts were deleted. Metabolite analyses of the constructed strains revealed extracellular accumulation of significant amounts of isobutyraldehyde, a pathway intermediate, and the overflow metabolites 2,3-butanediol and acetol. CONCLUSIONS These results demonstrate that the genetic modifications carried out led to activation of alternative pathways that diverted carbon flux toward formation of unwanted metabolites. The present study highlights how precursor metabolites can be metabolized through enzymatic routes that have not been considered important in previous studies due to the different strategies employed therein. The insights gained from the present study will allow rational genetic modification of host cells for production of metabolites of interest.
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Affiliation(s)
- Shalini S Deb
- DBT-ICT Centre for Energy Biosciences, Institute of Chemical Technology, Nathatlal Parekh Marg, Matunga (East), Mumbai, Maharashtra, 400019, India
| | - Shamlan M S Reshamwala
- DBT-ICT Centre for Energy Biosciences, Institute of Chemical Technology, Nathatlal Parekh Marg, Matunga (East), Mumbai, Maharashtra, 400019, India.
| | - Arvind M Lali
- DBT-ICT Centre for Energy Biosciences, Institute of Chemical Technology, Nathatlal Parekh Marg, Matunga (East), Mumbai, Maharashtra, 400019, India
- Department of Chemical Engineering, Institute of Chemical Technology, Nathatlal Parekh Marg, Matunga (East), Mumbai, Maharashtra, 400019, India
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Mähler C, Kratzl F, Vogel M, Vinnenberg S, Weuster‐Botz D, Castiglione K. Loop Swapping as a Potent Approach to Increase Ene Reductase Activity with Nicotinamide Adenine Dinucleotide (NADH). Adv Synth Catal 2019. [DOI: 10.1002/adsc.201900073] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Christoph Mähler
- Technical University of MunichInstitute of Biochemical Engineering Boltzmannstr. 15 D-85748 Garching Germany
| | - Franziska Kratzl
- Technical University of MunichInstitute of Biochemical Engineering Boltzmannstr. 15 D-85748 Garching Germany
| | - Melina Vogel
- Technical University of MunichInstitute of Biochemical Engineering Boltzmannstr. 15 D-85748 Garching Germany
| | - Stefan Vinnenberg
- Technical University of MunichInstitute of Biochemical Engineering Boltzmannstr. 15 D-85748 Garching Germany
| | - Dirk Weuster‐Botz
- Technical University of MunichInstitute of Biochemical Engineering Boltzmannstr. 15 D-85748 Garching Germany
| | - Kathrin Castiglione
- Friedrich-Alexander-University Erlangen-NürnbergInstitute of Bioprocess Engineering Paul-Gordan-Str. 3 D-91052 Erlangen Germany
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11
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Chen CY, Chang YC, Lin BL, Lin KF, Huang CH, Hsieh DL, Ko TP, Tsai MD. Use of Cryo-EM To Uncover Structural Bases of pH Effect and Cofactor Bispecificity of Ketol-Acid Reductoisomerase. J Am Chem Soc 2019; 141:6136-6140. [DOI: 10.1021/jacs.9b01354] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Chin-Yu Chen
- Department of Life Sciences, National Central University, Taoyuan 32001, Taiwan
| | | | | | - Kuan-Fu Lin
- Department of Life Sciences, National Central University, Taoyuan 32001, Taiwan
| | - Chun-Hsiang Huang
- Experimental Facility Division, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Dong-Lin Hsieh
- Department of Life Sciences, National Central University, Taoyuan 32001, Taiwan
| | | | - Ming-Daw Tsai
- Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan
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12
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Wu W, Zhang Y, Liu D, Chen Z. Efficient mining of natural NADH-utilizing dehydrogenases enables systematic cofactor engineering of lysine synthesis pathway of Corynebacterium glutamicum. Metab Eng 2018; 52:77-86. [PMID: 30458240 DOI: 10.1016/j.ymben.2018.11.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 10/22/2018] [Accepted: 11/16/2018] [Indexed: 12/01/2022]
Abstract
Increasing the availability of NADPH is commonly used to improve lysine production by Corynebacterium glutamicum since 4 mol of NADPH are required for the synthesis of 1 mol of lysine. Alternatively, engineering of enzymes in lysine synthesis pathway to utilize NADH directly can also be explored for cofactor balance during lysine overproduction. To achieve such a goal, enzyme mining was used in this study to quickly identify a full set of NADH-utilizing dehydrogenases, namely aspartate dehydrogenase from Pseudomonas aeruginosa (PaASPDH), aspartate-semialdehyde dehydrogenase from Tistrella mobilis (TmASADH), dihydrodipicolinate reductase from Escherichia coli (EcDHDPR), and diaminopimelate dehydrogenase from Pseudothermotoga thermarum (PtDAPDH). This allowed us to systematically perturb cofactor utilization of lysine synthesis pathway of C. glutamicum for the first time. Individual overexpression of PaASPDH, TmASADH, EcDHDPR, and PtDAPDH in C. glutamicum LC298, a basic lysine producer, increased the production of lysine by 30.7%, 32.4%, 17.4%, and 36.8%, respectively. Combinatorial replacement of NADPH-dependent dehydrogenases in C. glutamicum ATCC 21543, a lysine hyperproducer, also resulted in significantly improved lysine production. The highest increase of lysine production (30.7%) was observed for a triple-mutant strain (27.7 g/L, 0.35 g/g glucose) expressing PaASPDH, TmASADH, and EcDHDPR. A quadruple-mutant strain expressing all of the four NADH-utilizing enzymes allowed high lysine production (24.1 g/L, 0.30 g/g glucose) almost independent of the oxidative pentose phosphate pathway. Collectively, our results demonstrated that a combination of enzyme mining and cofactor engineering was a highly efficient approach to improve lysine production. Similar strategies can be applied for the production of other amino acids or their derivatives.
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Affiliation(s)
- Wenjun Wu
- Key Laboratory of Industrial Biocatalysis (Ministry of Education), Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
| | - Ye Zhang
- Key Laboratory of Industrial Biocatalysis (Ministry of Education), Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
| | - Dehua Liu
- Key Laboratory of Industrial Biocatalysis (Ministry of Education), Department of Chemical Engineering, Tsinghua University, Beijing 100084, China; Tsinghua Innovation Center in Dongguan, Dongguan 523808, China; Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, China
| | - Zhen Chen
- Key Laboratory of Industrial Biocatalysis (Ministry of Education), Department of Chemical Engineering, Tsinghua University, Beijing 100084, China; Tsinghua Innovation Center in Dongguan, Dongguan 523808, China; Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, China.
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13
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NADH/NADPH bi-cofactor-utilizing and thermoactive ketol-acid reductoisomerase from Sulfolobus acidocaldarius. Sci Rep 2018; 8:7176. [PMID: 29739976 PMCID: PMC5940873 DOI: 10.1038/s41598-018-25361-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 04/19/2018] [Indexed: 11/13/2022] Open
Abstract
Ketol-acid reductoisomerase (KARI) is a bifunctional enzyme in the second step of branched-chain amino acids biosynthetic pathway. Most KARIs prefer NADPH as a cofactor. However, KARI with a preference for NADH is desirable in industrial applications including anaerobic fermentation for the production of branched-chain amino acids or biofuels. Here, we characterize a thermoacidophilic archaeal Sac-KARI from Sulfolobus acidocaldarius and present its crystal structure at a 1.75-Å resolution. By comparison with other holo-KARI structures, one sulphate ion is observed in each binding site for the 2′-phosphate of NADPH, implicating its NADPH preference. Sac-KARI has very high affinity for NADPH and NADH, with KM values of 0.4 μM for NADPH and 6.0 μM for NADH, suggesting that both are good cofactors at low concentrations although NADPH is favoured over NADH. Furthermore, Sac-KARI can catalyze 2(S)-acetolactate (2S-AL) with either cofactor from 25 to 60 °C, but the enzyme has higher activity by using NADPH. In addition, the catalytic activity of Sac-KARI increases significantly with elevated temperatures and reaches an optimum at 60 °C. Bi-cofactor utilization and the thermoactivity of Sac-KARI make it a potential candidate for use in metabolic engineering or industrial applications under anaerobic or harsh conditions.
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14
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Chánique AM, Parra LP. Protein Engineering for Nicotinamide Coenzyme Specificity in Oxidoreductases: Attempts and Challenges. Front Microbiol 2018; 9:194. [PMID: 29491854 PMCID: PMC5817062 DOI: 10.3389/fmicb.2018.00194] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 01/29/2018] [Indexed: 01/10/2023] Open
Abstract
Oxidoreductases are ubiquitous enzymes that catalyze an extensive range of chemical reactions with great specificity, efficiency, and selectivity. Most oxidoreductases are nicotinamide cofactor-dependent enzymes with a strong preference for NADP or NAD. Because these coenzymes differ in stability, bioavailability and costs, the enzyme preference for a specific coenzyme is an important issue for practical applications. Different approaches for the manipulation of coenzyme specificity have been reported, with different degrees of success. Here we present various attempts for the switching of nicotinamide coenzyme preference in oxidoreductases by protein engineering. This review covers 103 enzyme engineering studies from 82 articles and evaluates the accomplishments in terms of coenzyme specificity and catalytic efficiency compared to wild type enzymes of different classes. We analyzed different protein engineering strategies and related them with the degree of success in inverting the cofactor specificity. In general, catalytic activity is compromised when coenzyme specificity is reversed, however when switching from NAD to NADP, better results are obtained. In most of the cases, rational strategies were used, predominantly with loop exchange generating the best results. In general, the tendency of removing acidic residues and incorporating basic residues is the strategy of choice when trying to change specificity from NAD to NADP, and vice versa. Computational strategies and algorithms are also covered as helpful tools to guide protein engineering strategies. This mini review aims to give a general introduction to the topic, giving an overview of tools and information to work in protein engineering for the reversal of coenzyme specificity.
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Affiliation(s)
- Andrea M Chánique
- Department of Chemical and Bioprocesses Engineering, School of Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Loreto P Parra
- Department of Chemical and Bioprocesses Engineering, School of Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile.,Schools of Engineering, Medicine and Biological Sciences, Institute for Biological and Medical Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile
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15
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Balke K, Beier A, Bornscheuer UT. Hot spots for the protein engineering of Baeyer-Villiger monooxygenases. Biotechnol Adv 2018; 36:247-263. [DOI: 10.1016/j.biotechadv.2017.11.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 11/15/2017] [Accepted: 11/17/2017] [Indexed: 10/18/2022]
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16
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Wu W, Zhang Y, Huang J, Wu Y, Liu D, Chen Z. Discovery of a Potentially New Subfamily of ELFV Dehydrogenases Effective for l
-Arginine Deamination by Enzyme Mining. Biotechnol J 2017; 13. [DOI: 10.1002/biot.201700305] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 09/11/2017] [Accepted: 10/09/2017] [Indexed: 11/05/2022]
Affiliation(s)
- Wenjun Wu
- Institute of Applied Chemistry, Department of Chemical Engineering; Tsinghua University; Beijing 100084 China
| | - Ye Zhang
- Institute of Applied Chemistry, Department of Chemical Engineering; Tsinghua University; Beijing 100084 China
| | - Jinhai Huang
- Institute of Applied Chemistry, Department of Chemical Engineering; Tsinghua University; Beijing 100084 China
| | - Yao Wu
- Institute of Applied Chemistry, Department of Chemical Engineering; Tsinghua University; Beijing 100084 China
| | - Dehua Liu
- Institute of Applied Chemistry, Department of Chemical Engineering; Tsinghua University; Beijing 100084 China
- Tsinghua Innovation Center in Dongguan; Dongguan 523808 China
| | - Zhen Chen
- Institute of Applied Chemistry, Department of Chemical Engineering; Tsinghua University; Beijing 100084 China
- Tsinghua Innovation Center in Dongguan; Dongguan 523808 China
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17
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You C, Huang R, Wei X, Zhu Z, Zhang YHP. Protein engineering of oxidoreductases utilizing nicotinamide-based coenzymes, with applications in synthetic biology. Synth Syst Biotechnol 2017; 2:208-218. [PMID: 29318201 PMCID: PMC5655348 DOI: 10.1016/j.synbio.2017.09.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2017] [Revised: 09/08/2017] [Accepted: 09/22/2017] [Indexed: 01/01/2023] Open
Abstract
Two natural nicotinamide-based coenzymes (NAD and NADP) are indispensably required by the vast majority of oxidoreductases for catabolism and anabolism, respectively. Most NAD(P)-dependent oxidoreductases prefer one coenzyme as an electron acceptor or donor to the other depending on their different metabolic roles. This coenzyme preference associated with coenzyme imbalance presents some challenges for the construction of high-efficiency in vivo and in vitro synthetic biology pathways. Changing the coenzyme preference of NAD(P)-dependent oxidoreductases is an important area of protein engineering, which is closely related to product-oriented synthetic biology projects. This review focuses on the methodology of nicotinamide-based coenzyme engineering, with its application in improving product yields and decreasing production costs. Biomimetic nicotinamide-containing coenzymes have been proposed to replace natural coenzymes because they are more stable and less costly than natural coenzymes. Recent advances in the switching of coenzyme preference from natural to biomimetic coenzymes are also covered in this review. Engineering coenzyme preferences from natural to biomimetic coenzymes has become an important direction for coenzyme engineering, especially for in vitro synthetic pathways and in vivo bioorthogonal redox pathways.
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Affiliation(s)
- 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
| | - Rui Huang
- Biological Systems Engineering Department, Virginia Tech, 304 Seitz Hall, Blacksburg, VA 24061, USA
| | - 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
| | - Zhiguang Zhu
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin, 300308, People's Republic of China
| | - Yi-Heng Percival Zhang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin, 300308, People's Republic of China.,Biological Systems Engineering Department, Virginia Tech, 304 Seitz Hall, Blacksburg, VA 24061, USA
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18
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Cahn JKB, Werlang CA, Baumschlager A, Brinkmann-Chen S, Mayo SL, Arnold FH. A General Tool for Engineering the NAD/NADP Cofactor Preference of Oxidoreductases. ACS Synth Biol 2017; 6:326-333. [PMID: 27648601 DOI: 10.1021/acssynbio.6b00188] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The ability to control enzymatic nicotinamide cofactor utilization is critical for engineering efficient metabolic pathways. However, the complex interactions that determine cofactor-binding preference render this engineering particularly challenging. Physics-based models have been insufficiently accurate and blind directed evolution methods too inefficient to be widely adopted. Building on a comprehensive survey of previous studies and our own prior engineering successes, we present a structure-guided, semirational strategy for reversing enzymatic nicotinamide cofactor specificity. This heuristic-based approach leverages the diversity and sensitivity of catalytically productive cofactor binding geometries to limit the problem to an experimentally tractable scale. We demonstrate the efficacy of this strategy by inverting the cofactor specificity of four structurally diverse NADP-dependent enzymes: glyoxylate reductase, cinnamyl alcohol dehydrogenase, xylose reductase, and iron-containing alcohol dehydrogenase. The analytical components of this approach have been fully automated and are available in the form of an easy-to-use web tool: Cofactor Specificity Reversal-Structural Analysis and Library Design (CSR-SALAD).
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Affiliation(s)
- Jackson K. B. Cahn
- Division of Chemistry and Chemical Engineering, and ‡Division of Biology and Biological
Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Caroline A. Werlang
- Division of Chemistry and Chemical Engineering, and ‡Division of Biology and Biological
Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Armin Baumschlager
- Division of Chemistry and Chemical Engineering, and ‡Division of Biology and Biological
Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Sabine Brinkmann-Chen
- Division of Chemistry and Chemical Engineering, and ‡Division of Biology and Biological
Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Stephen L. Mayo
- Division of Chemistry and Chemical Engineering, and ‡Division of Biology and Biological
Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Frances H. Arnold
- Division of Chemistry and Chemical Engineering, and ‡Division of Biology and Biological
Engineering, California Institute of Technology, Pasadena, California 91125, United States
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19
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Chen H, Zhu Z, Huang R, Zhang YHP. Coenzyme Engineering of a Hyperthermophilic 6-Phosphogluconate Dehydrogenase from NADP + to NAD + with Its Application to Biobatteries. Sci Rep 2016; 6:36311. [PMID: 27805055 PMCID: PMC5090862 DOI: 10.1038/srep36311] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 10/13/2016] [Indexed: 01/30/2023] Open
Abstract
Engineering the coenzyme specificity of redox enzymes plays an important role in metabolic engineering, synthetic biology, and biocatalysis, but it has rarely been applied to bioelectrochemistry. Here we develop a rational design strategy to change the coenzyme specificity of 6-phosphogluconate dehydrogenase (6PGDH) from a hyperthermophilic bacterium Thermotoga maritima from its natural coenzyme NADP+ to NAD+. Through amino acid-sequence alignment of NADP+- and NAD+-preferred 6PGDH enzymes and computer-aided substrate-coenzyme docking, the key amino acid residues responsible for binding the phosphate group of NADP+ were identified. Four mutants were obtained via site-directed mutagenesis. The best mutant N32E/R33I/T34I exhibited a ~6.4 × 104-fold reversal of the coenzyme selectivity from NADP+ to NAD+. The maximum power density and current density of the biobattery catalyzed by the mutant were 0.135 mW cm−2 and 0.255 mA cm−2, ~25% higher than those obtained from the wide-type 6PGDH-based biobattery at the room temperature. By using this 6PGDH mutant, the optimal temperature of running the biobattery was as high as 65 °C, leading to a high power density of 1.75 mW cm−2. This study demonstrates coenzyme engineering of a hyperthermophilic 6PGDH and its application to high-temperature biobatteries.
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Affiliation(s)
- Hui Chen
- Biological Systems Engineering Department, Virginia Tech, 304 Seitz Hall, Blacksburg, Virginia 24061, USA
| | - Zhiguang Zhu
- Cell Free Bioinnovations Inc. 1800 Kraft Drive, Suite 222, Blacksburg, VA 24060, USA.,Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin 300308, China
| | - Rui Huang
- Biological Systems Engineering Department, Virginia Tech, 304 Seitz Hall, Blacksburg, Virginia 24061, USA
| | - Yi-Heng Percival Zhang
- Biological Systems Engineering Department, Virginia Tech, 304 Seitz Hall, Blacksburg, Virginia 24061, USA.,Cell Free Bioinnovations Inc. 1800 Kraft Drive, Suite 222, Blacksburg, VA 24060, USA.,Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin 300308, China
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20
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Discovery of a regioselectivity switch in nitrating P450s guided by molecular dynamics simulations and Markov models. Nat Chem 2016; 8:419-25. [PMID: 27102675 PMCID: PMC4843824 DOI: 10.1038/nchem.2474] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 02/03/2016] [Indexed: 12/22/2022]
Abstract
The dynamic motions of protein structural elements, particularly flexible loops, are intimately linked with diverse aspects of enzyme catalysis. Engineering of these loop regions can alter protein stability, substrate binding, and even dramatically impact enzyme function. When these flexible regions are structurally unresolvable, computational reconstruction in combination with large-scale molecular dynamics simulations can be used to guide the engineering strategy. Here, we present a collaborative approach consisting of both experiment and computation that led to the discovery of a single mutation in the F/G loop of the nitrating cytochrome P450 TxtE that simultaneously controls loop dynamics and completely shifts the enzyme's regioselectivity from the C4 to the C5 position of L-tryptophan. Furthermore, we find that this loop mutation is naturally present in a subset of homologous nitrating P450s and confirm that these uncharacterized enzymes exclusively produce 5-nitro-L-tryptophan, a previously unknown biosynthetic intermediate.
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21
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Cahn JKB, Brinkmann-Chen S, Buller AR, Arnold FH. Artificial domain duplication replicates evolutionary history of ketol-acid reductoisomerases. Protein Sci 2015; 25:1241-8. [PMID: 26644020 DOI: 10.1002/pro.2852] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 12/01/2015] [Indexed: 11/11/2022]
Abstract
The duplication of protein structural domains has been proposed as a common mechanism for the generation of new protein folds. A particularly interesting case is the class II ketol-acid reductoisomerase (KARI), which putatively arose from an ancestral class I KARI by duplication of the C-terminal domain and corresponding loss of obligate dimerization. As a result, the class II enzymes acquired a deeply embedded figure-of-eight knot. To test this evolutionary hypothesis we constructed a novel class II KARI by duplicating the C-terminal domain of a hyperthermostable class I KARI. The new protein is monomeric, as confirmed by gel filtration and X-ray crystallography, and has the deeply knotted class II KARI fold. Surprisingly, its catalytic activity is nearly unchanged from the parent KARI. This provides strong evidence in support of domain duplication as the mechanism for the evolution of the class II KARI fold and demonstrates the ability of domain duplication to generate topological novelty in a function-neutral manner.
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Affiliation(s)
- Jackson K B Cahn
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, 91125
| | - Sabine Brinkmann-Chen
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, 91125
| | - Andrew R Buller
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, 91125
| | - Frances H Arnold
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, 91125
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22
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Enhancing the light-driven production of D-lactate by engineering cyanobacterium using a combinational strategy. Sci Rep 2015; 5:9777. [PMID: 25940225 PMCID: PMC4419521 DOI: 10.1038/srep09777] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 03/19/2015] [Indexed: 11/28/2022] Open
Abstract
It is increasingly attractive to engineer cyanobacteria for bulk production of chemicals from CO2. However, cofactor bias of cyanobacteria is different from bacteria that prefer NADH, which hampers cyanobacterial strain engineering. In this study, the key enzyme d-lactate dehydrogenase (LdhD) from Lactobacillus bulgaricus ATCC11842 was engineered to reverse its favored cofactor from NADH to NADPH. Then, the engineered enzyme was introduced into Synechococcus elongatus PCC7942 to construct an efficient light-driven system that produces d-lactic acid from CO2. Mutation of LdhD drove a fundamental shift in cofactor preference towards NADPH, and increased d-lactate productivity by over 3.6-fold. We further demonstrated that introduction of a lactic acid transporter and bubbling CO2-enriched air also enhanced d-lactate productivity. Using this combinational strategy, increased d-lactate concentration and productivity were achieved. The present strategy may also be used to engineer cyanobacteria for producing other useful chemicals.
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23
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Cofactor specificity motifs and the induced fit mechanism in class I ketol-acid reductoisomerases. Biochem J 2015; 468:475-84. [PMID: 25849365 DOI: 10.1042/bj20150183] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 04/07/2015] [Indexed: 11/17/2022]
Abstract
Although most sequenced members of the industrially important ketol-acid reductoisomerase (KARI) family are class I enzymes, structural studies to date have focused primarily on the class II KARIs, which arose through domain duplication. In the present study, we present five new crystal structures of class I KARIs. These include the first structure of a KARI with a six-residue β2αB (cofactor specificity determining) loop and an NADPH phosphate-binding geometry distinct from that of the seven- and 12-residue loops. We also present the first structures of naturally occurring KARIs that utilize NADH as cofactor. These results show insertions in the specificity loops that confounded previous attempts to classify them according to loop length. Lastly, we explore the conformational changes that occur in class I KARIs upon binding of cofactor and metal ions. The class I KARI structures indicate that the active sites close upon binding NAD(P)H, similar to what is observed in the class II KARIs of rice and spinach and different from the opening of the active site observed in the class II KARI of Escherichia coli. This conformational change involves a decrease in the bending of the helix that runs between the domains and a rearrangement of the nicotinamide-binding site.
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