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Beck SW, Ye DY, Hwang HG, Jung GY. Stepwise Flux Optimization for Enhanced GABA Production from Acetate in Escherichia coli. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:10420-10427. [PMID: 38657224 DOI: 10.1021/acs.jafc.4c01198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Strategic allocation of metabolic flux is essential for achieving a higher production performance in genetically engineered organisms. Flux optimization between cell growth and chemical production has led to the establishment of cost-effective chemical production methods in microbial cell factories. This effect is amplified when utilizing a low-cost carbon source. γ-Aminobutyric acid (GABA), crucial in pharmaceuticals and biodegradable polymers, can be efficiently produced from acetate, a cost-effective substrate. However, a balanced distribution of acetate-derived flux is essential for optimizing the production without hindering growth. In this study, we demonstrated GABA production from acetate using Escherichia coli by focusing on optimizing the metabolic flux at isocitrate and α-ketoglutarate nodes. Through a series of flux optimizations, the final strain produced 2.54 g/L GABA from 5.91 g/L acetate in 24 h (0.43 g/g yield). These findings suggest that delicate flux balancing with the application of a cheap substrate can contribute to cost-effective production of GABA.
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Affiliation(s)
- Sun Woo Beck
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, Republic of Korea
| | - Dae-Yeol Ye
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, Republic of Korea
| | - Hyun Gyu Hwang
- Institute of Environmental and Energy Technology, Pohang University of Science and Technology, 77 Cheongam - Ro, Nam-Gu, Pohang, Gyeongbuk 37673, Republic of Korea
| | - Gyoo Yeol Jung
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, Republic of Korea
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, Republic of Korea
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2
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Ellington AJ, Reisch CR. Generating Single Nucleotide Point Mutations in E. coli with the No-SCAR System. Methods Mol Biol 2022; 2479:119-133. [PMID: 35583736 DOI: 10.1007/978-1-0716-2233-9_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Genetic manipulation of microbial genomes is highly relevant for studying biological systems and the development of biotechnologies. In E. coli, λ-Red recombineering is one of the most widely used gene-editing methods, enabling site-specific insertions, deletions, and point mutations of any genomic locus. The no-SCAR system combines λ-Red recombineering with CRISPR/Cas9 for programmable selection of recombinant cells. Recombineering results in the transient production of heteroduplex DNA, as only one strand of DNA is initially altered, leaving the mismatched bases susceptible to repair by the host methyl-directed mismatch repair (MMR) system and reduces the efficiency of generating single nucleotide point mutations. Here we describe a method, where expression of cas9 and the MMR-inhibiting mutLE32K variant are independently controlled by anhydrotetracycline- and cumate-inducible promoters from the pCas9CyMutL plasmid. Thus, MMR is selectively inhibited until recombinant cells have undergone replication and the desired mutation is permanently incorporated. By transiently inhibiting MMR, the accumulation of off-target mutations typically associated with MMR-deficient cell types is minimized. Methods for designing the editing template and sgRNA, cloning of the sgRNA, induction of λ-Red and MutLE32K, the transformation of editing oligo, and induction of Cas9 for mutant selection are detailed within.
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Affiliation(s)
- Adam J Ellington
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Science, University of Florida, Gainesville, FL, USA
| | - Christopher R Reisch
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Science, University of Florida, Gainesville, FL, USA.
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3
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Fels U, Gevaert K, Van Damme P. Bacterial Genetic Engineering by Means of Recombineering for Reverse Genetics. Front Microbiol 2020; 11:548410. [PMID: 33013782 PMCID: PMC7516269 DOI: 10.3389/fmicb.2020.548410] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 08/14/2020] [Indexed: 12/11/2022] Open
Abstract
Serving a robust platform for reverse genetics enabling the in vivo study of gene functions primarily in enterobacteriaceae, recombineering -or recombination-mediated genetic engineering-represents a powerful and relative straightforward genetic engineering tool. Catalyzed by components of bacteriophage-encoded homologous recombination systems and only requiring short ∼40–50 base homologies, the targeted and precise introduction of modifications (e.g., deletions, knockouts, insertions and point mutations) into the chromosome and other episomal replicons is empowered. Furthermore, by its ability to make use of both double- and single-stranded linear DNA editing substrates (e.g., PCR products or oligonucleotides, respectively), lengthy subcloning of specific DNA sequences is circumvented. Further, the more recent implementation of CRISPR-associated endonucleases has allowed for more efficient screening of successful recombinants by the selective purging of non-edited cells, as well as the creation of markerless and scarless mutants. In this review we discuss various recombineering strategies to promote different types of gene modifications, how they are best applied, and their possible pitfalls.
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Affiliation(s)
- Ursula Fels
- Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium.,VIB-UGent Center for Medical Biotechnology, Ghent, Belgium
| | - Kris Gevaert
- VIB-UGent Center for Medical Biotechnology, Ghent, Belgium.,Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
| | - Petra Van Damme
- Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium
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4
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Abbasi MN, Fu J, Bian X, Wang H, Zhang Y, Li A. Recombineering for Genetic Engineering of Natural Product Biosynthetic Pathways. Trends Biotechnol 2020; 38:715-728. [PMID: 31973879 DOI: 10.1016/j.tibtech.2019.12.018] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 12/11/2019] [Accepted: 12/12/2019] [Indexed: 01/21/2023]
Abstract
Microbial genomes encode many cryptic and uncharacterized biosynthetic gene clusters (BGCs). Exploiting this unexplored genetic wealth to discover microbial novel natural products (NPs) remains a challenging issue. We review homologous recombination (HR)-based recombineering, mediated by the recombinases RecE/RecT from Rac prophage and Redα/Redβ from lambda phage, which has developed into a highly inclusive tool for direct cloning of large DNA up to 100 kb, seamless mutation, multifragment assembly, and heterologous expression of microbial NP BGCs. Its utilization in the refactoring, engineering, and functional expression of long BGCs for NP biosynthesis makes it easy to elucidate NP-producing potential in microbes. This review also highlights various applications of recombineering in NP-derived drug discovery.
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Affiliation(s)
- Muhammad Nazeer Abbasi
- Helmholtz International Lab for Anti-Infectives, Shandong University-Helmholtz Institute of Biotechnology, State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, PR China
| | - Jun Fu
- Helmholtz International Lab for Anti-Infectives, Shandong University-Helmholtz Institute of Biotechnology, State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, PR China
| | - Xiaoying Bian
- Helmholtz International Lab for Anti-Infectives, Shandong University-Helmholtz Institute of Biotechnology, State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, PR China
| | - Hailong Wang
- Helmholtz International Lab for Anti-Infectives, Shandong University-Helmholtz Institute of Biotechnology, State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, PR China.
| | - Youming Zhang
- Helmholtz International Lab for Anti-Infectives, Shandong University-Helmholtz Institute of Biotechnology, State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, PR China.
| | - Aiying Li
- Helmholtz International Lab for Anti-Infectives, Shandong University-Helmholtz Institute of Biotechnology, State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, PR China.
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5
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Abstract
Recombineering inserts PCR products into DNA using homologous recombination. A pair of short homology arms (50 base pairs) on the ends of a PCR cassette target the cassette to its intended location. These homology arms can be easily introduced as 5' primer overhangs during the PCR reaction. The flexibility to choose almost any pair of homology arms enables the precise modification of virtually any DNA for purposes of sequence deletion, replacement, insertion, or point mutation. Recombineering often offers significant advantages relative to previous homologous recombination methods that require the construction of cassettes with large homology arms, and relative to traditional cloning methods that become intractable for large plasmids or DNA sequences. However, the tremendous number of variables, options, and pitfalls that can be encountered when designing and performing a recombineering protocol for the first time introduce barriers that can make recombineering a challenging technique for new users to adopt. This article focuses on three recombineering protocols we have found to be particularly robust, providing a detailed guide for choosing the simplest recombineering method for a given application and for performing and troubleshooting experiments. © 2019 by John Wiley & Sons, Inc.
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Affiliation(s)
- Louis J Papa
- Massachusetts Institute of Technology, Department of Chemistry, Cambridge, Massachusetts
| | - Matthew D Shoulders
- Massachusetts Institute of Technology, Department of Chemistry, Cambridge, Massachusetts
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6
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Freed EF, Pines G, Eckert CA, Gill RT. Trackable Multiplex Recombineering (TRMR) and Next-Generation Genome Design Technologies: Modifying Gene Expression inE. coliby Inserting Synthetic DNA Cassettes and Molecular Barcodes. Synth Biol (Oxf) 2018. [DOI: 10.1002/9783527688104.ch2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2023] Open
Affiliation(s)
- Emily F. Freed
- Biosciences Center, National Renewable Energy Laboratory; 15013 Denver West Parkway Golden CO 80401 USA
| | - Gur Pines
- University of Colorado; Chemical and Biological Engineering; 3415 Colorado Ave Boulder CO 80303 USA
- University of Colorado; Renewable and Sustainable Energy Institute; 4001 Discovery Dr Boulder CO 80303 USA
| | - Carrie A. Eckert
- Biosciences Center, National Renewable Energy Laboratory; 15013 Denver West Parkway Golden CO 80401 USA
- University of Colorado; Renewable and Sustainable Energy Institute; 4001 Discovery Dr Boulder CO 80303 USA
| | - Ryan T. Gill
- University of Colorado; Chemical and Biological Engineering; 3415 Colorado Ave Boulder CO 80303 USA
- University of Colorado; Renewable and Sustainable Energy Institute; 4001 Discovery Dr Boulder CO 80303 USA
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Noh MH, Lim HG, Woo SH, Song J, Jung GY. Production of itaconic acid from acetate by engineering acid-tolerant Escherichia coli
W. Biotechnol Bioeng 2017; 115:729-738. [DOI: 10.1002/bit.26508] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 11/10/2017] [Accepted: 11/30/2017] [Indexed: 12/23/2022]
Affiliation(s)
- Myung Hyun Noh
- Department of Chemical Engineering; Pohang University of Science and Technology; Nam-Gu Pohang Gyeongbuk Korea
| | - Hyun Gyu Lim
- Department of Chemical Engineering; Pohang University of Science and Technology; Nam-Gu Pohang Gyeongbuk Korea
| | - Sung Hwa Woo
- Department of Chemical Engineering; Pohang University of Science and Technology; Nam-Gu Pohang Gyeongbuk Korea
| | - Jinyi Song
- Department of Chemical Engineering; Pohang University of Science and Technology; Nam-Gu Pohang Gyeongbuk Korea
| | - Gyoo Yeol Jung
- Department of Chemical Engineering; Pohang University of Science and Technology; Nam-Gu Pohang Gyeongbuk Korea
- School of Interdisciplinary Bioscience and Bioengineering; Pohang University of Science and Technology; Nam-Gu Pohang Gyeongbuk Korea
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8
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Higgins SA, Ouonkap SVY, Savage DF. Rapid and Programmable Protein Mutagenesis Using Plasmid Recombineering. ACS Synth Biol 2017; 6:1825-1833. [PMID: 28707884 DOI: 10.1021/acssynbio.7b00112] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Comprehensive and programmable protein mutagenesis is critical for understanding structure-function relationships and improving protein function. There is thus a need for robust and unbiased molecular biological approaches for the construction of the requisite comprehensive protein libraries. Here we demonstrate that plasmid recombineering is a simple and robust in vivo method for the generation of protein mutants for both comprehensive library generation as well as programmable targeting of sequence space. Using the fluorescent protein iLOV as a model target, we build a complete mutagenesis library and find it to be specific and comprehensive, detecting 99.8% of our intended mutations. We then develop a thermostability screen and utilize our comprehensive mutation data to rapidly construct a targeted and multiplexed library that identifies significantly improved variants, thus demonstrating rapid protein engineering in a simple protocol.
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Affiliation(s)
- Sean A. Higgins
- Department
of Molecular and Cell Biology, and ‡Department of Chemistry, UC Berkeley, Berkeley, California 94720, United States
| | - Sorel V. Y. Ouonkap
- Department
of Molecular and Cell Biology, and ‡Department of Chemistry, UC Berkeley, Berkeley, California 94720, United States
| | - David F. Savage
- Department
of Molecular and Cell Biology, and ‡Department of Chemistry, UC Berkeley, Berkeley, California 94720, United States
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9
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Noh MH, Lim HG, Park S, Seo SW, Jung GY. Precise flux redistribution to glyoxylate cycle for 5-aminolevulinic acid production in Escherichia coli. Metab Eng 2017; 43:1-8. [DOI: 10.1016/j.ymben.2017.07.006] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 07/01/2017] [Accepted: 07/20/2017] [Indexed: 12/20/2022]
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10
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Ye W, Li J, Han R, Xu G, Dong J, Ni Y. Engineering coenzyme A-dependent pathway from Clostridium saccharobutylicum in Escherichia coli for butanol production. BIORESOURCE TECHNOLOGY 2017; 235:140-148. [PMID: 28365341 DOI: 10.1016/j.biortech.2017.03.085] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 03/13/2017] [Accepted: 03/14/2017] [Indexed: 06/07/2023]
Abstract
Clostridium saccharobutylicum has been proved to be efficient in butanol fermentation from various feedstocks. Whereas, lack of genetic manipulation system has severely hindered the engineering of C. saccharobutylicum for more extensive applications. In this study, recombinant Escherichia coli harboring heterologous coenzyme A-dependent pathway from C. saccharobutylicum DSM 13864 was constructed, which consisted of solventogenic pathway genes: acetoacetyl-CoA thiolase (thlA), aldehyde/alcohol dehydrogenase (adhE2) and bcs-operon (crt-bcd1-etfB2-fixB2-hbd). Then, a butanol titer of 67mg/L was attained. After replacing thlA with acetyl-CoA acetyltransferase (atoB) from E. coli and deleting the competitive branch genes lactate dehydrogenase (ldhA), aldehyde/alcohol dehydrogenase (adhE1) and fumarate reductase (frdBC), the butanol titer was successfully improved for 3.8-fold (254mg/L). Under the optimum fermentation conditions, the final butanol titer reached 584mg/L after 120h. This result demonstrates the feasibility of adapting CoA-dependent solventogenic pathway from C. saccharobutylicum in E. coli for butanol synthesis.
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Affiliation(s)
- Weihua Ye
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Jin Li
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Ruizhi Han
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Guochao Xu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Jinjun Dong
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Ye Ni
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China.
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11
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Kwak DH, Lim HG, Yang J, Seo SW, Jung GY. Synthetic redesign of Escherichia coli for cadaverine production from galactose. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:20. [PMID: 28127401 PMCID: PMC5251296 DOI: 10.1186/s13068-017-0707-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 01/11/2017] [Indexed: 05/05/2023]
Abstract
BACKGROUND With increasing concerns over the environment, biological production of cadaverine has been suggested as an alternative route to replace polyamides generated from the petroleum-based process. For an ideal bioprocess, cadaverine should be produced with high yield and productivity from various sugars abundant in biomass. However, most microorganisms are not able to efficiently metabolize other biomass-derived sugars as fast as glucose. This results in reduced growth rate and low carbon flux toward the production of desired bio-chemicals. Thus, redesign of microorganisms is necessary for utilizing those carbon sources with enhanced carbon flux and product formation. RESULTS In this study, we engineered Escherichia coli to produce cadaverine with rapid assimilation of galactose, a promising future feedstock. To achieve this, genes related to the metabolic pathway were maximally expressed to amplify the flux toward cadaverine production via synthetic expression cassettes consisting of predictive and quantitative genetic parts (promoters, 5'-untranslated regions, and terminators). Furthermore, the feedback inhibition of metabolic enzymes and degradation/re-uptake pathways was inactivated to robustly produce cadaverine. Finally, the resultant strain, DHK4, produced 8.80 g/L cadaverine with high yield (0.170 g/g) and productivity (0.293 g/L/h) during fed-batch fermentation, which was similar to or better than the previous glucose fermentation. CONCLUSIONS Taken together, synthetic redesign of a microorganism with predictive and quantitative genetic parts is a prerequisite for converting sugars from abundant biomass into desired platform chemicals. This is the first report to produce cadaverine from galactose. Moreover, the yield (0.170 g/g) was the highest among engineered E. coli systems.
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Affiliation(s)
- Dong Hun Kwak
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673 South Korea
| | - Hyun Gyu Lim
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673 South Korea
| | - Jina Yang
- School of Chemical and Biological Engineering, Institute of Chemical Process, Seoul National University, 1 Gwanak-Ro, Gwanak-Gu, Seoul, 08826 South Korea
| | - Sang Woo Seo
- School of Chemical and Biological Engineering, Institute of Chemical Process, Seoul National University, 1 Gwanak-Ro, Gwanak-Gu, Seoul, 08826 South Korea
| | - Gyoo Yeol Jung
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673 South Korea
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673 South Korea
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12
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Lim JH, Jung GY. A simple method to control glycolytic flux for the design of an optimal cell factory. BIOTECHNOLOGY FOR BIOFUELS 2017. [PMID: 28649279 PMCID: PMC5480111 DOI: 10.1186/s13068-017-0847-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
BACKGROUND A microbial cell factory with high yield and productivity are prerequisites for an economically feasible bio-based chemical industry. However, cell factories that show a kinetic imbalance between glycolysis and product formation pathways are not optimal. Glycolysis activity is highly robust for survival in nature, but is not optimized for chemical production. RESULTS Here, we propose a novel approach to balance glycolytic activity with the product formation capacity by precisely controlling expression level of ptsG (encoded glucose transporter) through UTR engineering. For various heterologous pathways with different maximum production rates, e.g., n-butanol, butyrate, and 2,3-butanediol, glycolytic fluxes could be successfully modulated to maximize yield and productivity, while minimizing by-product formation in Escherichia coli. CONCLUSIONS These results support the application of this simple method to explore the maximum yield and productivity when designing optimal cell factories for value-added products in the fields of metabolic engineering and synthetic biology.
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Affiliation(s)
- Jae Hyung Lim
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673 Korea
| | - Gyoo Yeol Jung
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673 Korea
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673 Korea
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13
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Lim HG, Noh MH, Jeong JH, Park S, Jung GY. Optimum Rebalancing of the 3-Hydroxypropionic Acid Production Pathway from Glycerol in Escherichia coli. ACS Synth Biol 2016; 5:1247-1255. [PMID: 27056171 DOI: 10.1021/acssynbio.5b00303] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
3-Hydroxypropionic acid (3-HP) can be biologically produced from glycerol by two consecutive enzymatic reactions, dehydration of glycerol to 3-hydroxypropionaldehyde (3-HPA) and oxidation of 3-HPA. The pathway has been proved efficient, but imbalance between the rates of the two enzymatic reactions often results in the accumulation of the toxic 3-HPA, which severely reduces cell viability and 3-HP production. In this study, we used UTR engineering to maximally increase the activities of glycerol dehydratase (GDHt) and aldehyde dehydrogenase (ALDH) for the high conversion of glycerol to 3-HP. Thereafter, the activity of GDHt was precisely controlled to avoid the accumulation of 3-HPA by varying expression of dhaB1, a gene encoding a main subunit of GDHt. The optimally balanced E. coli HGL_DBK4 showed a substantially enhanced 3-HP titer and productivity compared with the parental strain. The yield on glycerol, 0.97 g 3-HP/g glycerol, in a fed-batch experiment, was the highest ever reported.
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Affiliation(s)
- Hyun Gyu Lim
- Department
of Chemical Engineering and School of Interdisciplinary Bioscience
and Bioengineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, Korea
| | - Myung Hyun Noh
- Department
of Chemical Engineering and School of Interdisciplinary Bioscience
and Bioengineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, Korea
| | - Jun Hong Jeong
- Department
of Chemical Engineering and School of Interdisciplinary Bioscience
and Bioengineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, Korea
| | - Sunghoon Park
- School
of Chemical and Biomolecular Engineering, Pusan National University, 2 Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan 46241, Korea
| | - Gyoo Yeol Jung
- Department
of Chemical Engineering and School of Interdisciplinary Bioscience
and Bioengineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, Korea
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14
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Abstract
The bacteriophage λ Red homologous recombination system has been studied over the past 50 years as a model system to define the mechanistic details of how organisms exchange DNA segments that share extended regions of homology. The λ Red system proved useful as a system to study because recombinants could be easily generated by co-infection of genetically marked phages. What emerged from these studies was the recognition that replication of phage DNA was required for substantial Red-promoted recombination in vivo, and the critical role that double-stranded DNA ends play in allowing the Red proteins access to the phage DNA chromosomes. In the past 16 years, however, the λ Red recombination system has gained a new notoriety. When expressed independently of other λ functions, the Red system is able to promote recombination of linear DNA containing limited regions of homology (∼50 bp) with the Escherichia coli chromosome, a process known as recombineering. This review explains how the Red system works during a phage infection, and how it is utilized to make chromosomal modifications of E. coli with such efficiency that it changed the nature and number of genetic manipulations possible, leading to advances in bacterial genomics, metabolic engineering, and eukaryotic genetics.
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Affiliation(s)
- Kenan C Murphy
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA 01605
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15
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Pines G, Freed EF, Winkler JD, Gill RT. Bacterial Recombineering: Genome Engineering via Phage-Based Homologous Recombination. ACS Synth Biol 2015; 4:1176-85. [PMID: 25856528 DOI: 10.1021/acssynbio.5b00009] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The ability to specifically modify bacterial genomes in a precise and efficient manner is highly desired in various fields, ranging from molecular genetics to metabolic engineering and synthetic biology. Much has changed from the initial realization that phage-derived genes may be employed for such tasks to today, where recombineering enables complex genetic edits within a genome or a population. Here, we review the major developments leading to recombineering becoming the method of choice for in situ bacterial genome editing while highlighting the various applications of recombineering in pushing the boundaries of synthetic biology. We also present the current understanding of the mechanism of recombineering. Finally, we discuss in detail issues surrounding recombineering efficiency and future directions for recombineering-based genome editing.
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Affiliation(s)
- Gur Pines
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Emily F. Freed
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - James D. Winkler
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Ryan T. Gill
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
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16
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Kim SC, Min BE, Hwang HG, Seo SW, Jung GY. Pathway optimization by re-design of untranslated regions for L-tyrosine production in Escherichia coli. Sci Rep 2015; 5:13853. [PMID: 26346938 PMCID: PMC4561953 DOI: 10.1038/srep13853] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 08/07/2015] [Indexed: 01/17/2023] Open
Abstract
L-tyrosine is a commercially important compound in the food, pharmaceutical, chemical, and cosmetic industries. Although several attempts have been made to improve L-tyrosine production, translation-level expression control and carbon flux rebalancing around phosphoenolpyruvate (PEP) node still remain to be achieved for optimizing the pathway. Here, we demonstrate pathway optimization by altering gene expression levels for L-tyrosine production in Escherichia coli. To optimize the L-tyrosine biosynthetic pathway, a synthetic constitutive promoter and a synthetic 5′-untranslated region (5′-UTR) were introduced for each gene of interest to allow for control at both transcription and translation levels. Carbon flux rebalancing was achieved by controlling the expression level of PEP synthetase using UTR Designer. The L-tyrosine productivity of the engineered E. coli strain was increased through pathway optimization resulting in 3.0 g/L of L-tyrosine titer, 0.0354 g L-tyrosine/h/g DCW of productivity, and 0.102 g L-tyrosine/g glucose yield. Thus, this work demonstrates that pathway optimization by 5′-UTR redesign is an effective strategy for the development of efficient L-tyrosine-producing bacteria.
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Affiliation(s)
- Seong Cheol Kim
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 790-784, Korea
| | - Byung Eun Min
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 790-784, Korea
| | - Hyun Gyu Hwang
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 790-784, Korea
| | - Sang Woo Seo
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 790-784, Korea
| | - Gyoo Yeol Jung
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 790-784, Korea.,Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 790-784, Korea
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17
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Reddy TR, Kelsall EJ, Fevat LMS, Munson SE, Cowley SM. Differential requirements of singleplex and multiplex recombineering of large DNA constructs. PLoS One 2015; 10:e0125533. [PMID: 25954970 PMCID: PMC4425527 DOI: 10.1371/journal.pone.0125533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 03/16/2015] [Indexed: 11/18/2022] Open
Abstract
Recombineering is an in vivo genetic engineering technique involving homologous recombination mediated by phage recombination proteins. The use of recombineering methodology is not limited by size and sequence constraints and therefore has enabled the streamlined construction of bacterial strains and multi-component plasmids. Recombineering applications commonly utilize singleplex strategies and the parameters are extensively tested. However, singleplex recombineering is not suitable for the modification of several loci in genome recoding and strain engineering exercises, which requires a multiplex recombineering design. Defining the main parameters affecting multiplex efficiency especially the insertion of multiple large genes is necessary to enable efficient large-scale modification of the genome. Here, we have tested different recombineering operational parameters of the lambda phage Red recombination system and compared singleplex and multiplex recombineering of large gene sized DNA cassettes. We have found that optimal multiplex recombination required long homology lengths in excess of 120 bp. However, efficient multiplexing was possible with only 60 bp of homology. Multiplex recombination was more limited by lower amounts of DNA than singleplex recombineering and was greatly enhanced by use of phosphorothioate protection of DNA. Exploring the mechanism of multiplexing revealed that efficient recombination required co-selection of an antibiotic marker and the presence of all three Red proteins. Building on these results, we substantially increased multiplex efficiency using an ExoVII deletion strain. Our findings elucidate key differences between singleplex and multiplex recombineering and provide important clues for further improving multiplex recombination efficiency.
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Affiliation(s)
- Thimma R. Reddy
- Department of Biochemistry, University of Leicester, Leicester, LE1 9HN, United Kingdom
| | - Emma J. Kelsall
- Department of Biochemistry, University of Leicester, Leicester, LE1 9HN, United Kingdom
| | - Léna M. S. Fevat
- Center for Fisheries, Environment and Aquaculture Sciences, Lowestoft, NR33 0HT, United Kingdom
| | - Sarah E. Munson
- ES Cell Facility, Center for Core Biotechnology Services, Leicester, LE1 9HN, United Kingdom
| | - Shaun M. Cowley
- Department of Biochemistry, University of Leicester, Leicester, LE1 9HN, United Kingdom
- * E-mail:
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18
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Reddy TR, Fevat LMS, Munson SE, Stewart AF, Cowley SM. Lambda red mediated gap repair utilizes a novel replicative intermediate in Escherichia coli. PLoS One 2015; 10:e0120681. [PMID: 25803509 PMCID: PMC4372340 DOI: 10.1371/journal.pone.0120681] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 02/05/2015] [Indexed: 11/19/2022] Open
Abstract
The lambda phage Red recombination system can mediate efficient homologous recombination in Escherichia coli, which is the basis of the DNA engineering technique termed recombineering. Red mediated insertion of DNA requires DNA replication, involves a single-stranded DNA intermediate and is more efficient on the lagging strand of the replication fork. Lagging strand recombination has also been postulated to explain the Red mediated repair of gapped plasmids by an Okazaki fragment gap filling model. Here, we demonstrate that gap repair involves a different strand independent mechanism. Gap repair assays examining the strand asymmetry of recombination did not show a lagging strand bias. Directly testing an ssDNA plasmid showed lagging strand recombination is possible but dsDNA plasmids did not employ this mechanism. Insertional recombination combined with gap repair also did not demonstrate preferential lagging strand bias, supporting a different gap repair mechanism. The predominant recombination route involved concerted insertion and subcloning though other routes also operated at lower frequencies. Simultaneous insertion of DNA resulted in modification of both strands and was unaffected by mutations to DNA polymerase I, responsible for Okazaki fragment maturation. The lower efficiency of an alternate Red mediated ends-in recombination pathway and the apparent lack of a Holliday junction intermediate suggested that gap repair does not involve a different Red recombination pathway. Our results may be explained by a novel replicative intermediate in gap repair that does not involve a replication fork. We exploited these observations by developing a new recombineering application based on concerted insertion and gap repair, termed SPI (subcloning plus insertion). SPI selected against empty vector background and selected for correct gap repair recombinants. We used SPI to simultaneously insert up to four different gene cassettes in a single recombineering reaction. Consequently, our findings have important implications for the understanding of E. coli replication and Red recombination.
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Affiliation(s)
- Thimma R. Reddy
- Department of Biochemistry, University of Leicester, Leicester, United Kingdom
| | - Léna M. S. Fevat
- Center for Fisheries, Environment and Aquaculture Sciences, Lowestoft, United Kingdom
| | - Sarah E. Munson
- ES Cell Facility, Centre for Core Biotechnology Services, University of Leicester, Leicester, United Kingdom
| | - A. Francis Stewart
- Genomics, BioInnovationsZentrum, Technische Universitaet Dresden, Dresden, Germany
| | - Shaun M. Cowley
- Department of Biochemistry, University of Leicester, Leicester, United Kingdom
- * E-mail:
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19
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Lim HG, Lim JH, Jung GY. Modular design of metabolic network for robust production of n-butanol from galactose-glucose mixtures. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:137. [PMID: 26347006 PMCID: PMC4559943 DOI: 10.1186/s13068-015-0327-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 08/25/2015] [Indexed: 05/15/2023]
Abstract
BACKGROUND Refactoring microorganisms for efficient production of advanced biofuel such as n-butanol from a mixture of sugars in the cheap feedstock is a prerequisite to achieve economic feasibility in biorefinery. However, production of biofuel from inedible and cheap feedstock is highly challenging due to the slower utilization of biomass-driven sugars, arising from complex assimilation pathway, difficulties in amplification of biosynthetic pathways for heterologous metabolite, and redox imbalance caused by consuming intracellular reducing power to produce quite reduced biofuel. Even with these problems, the microorganisms should show robust production of biofuel to obtain industrial feasibility. Thus, refactoring microorganisms for efficient conversion is highly desirable in biofuel production. RESULTS In this study, we engineered robust Escherichia coli to accomplish high production of n-butanol from galactose-glucose mixtures via the design of modular pathway, an efficient and systematic way, to reconstruct the entire metabolic pathway with many target genes. Three modular pathways designed using the predictable genetic elements were assembled for efficient galactose utilization, n-butanol production, and redox re-balancing to robustly produce n-butanol from a sugar mixture of galactose and glucose. Specifically, the engineered strain showed dramatically increased n-butanol production (3.3-fold increased to 6.2 g/L after 48-h fermentation) compared to the parental strain (1.9 g/L) in galactose-supplemented medium. Moreover, fermentation with mixtures of galactose and glucose at various ratios from 2:1 to 1:2 confirmed that our engineered strain was able to robustly produce n-butanol regardless of sugar composition with simultaneous utilization of galactose and glucose. CONCLUSIONS Collectively, modular pathway engineering of metabolic network can be an effective approach in strain development for optimal biofuel production with cost-effective fermentable sugars. To the best of our knowledge, this study demonstrated the first and highest n-butanol production from galactose in E. coli. Moreover, robust production of n-butanol with sugar mixtures with variable composition would facilitate the economic feasibility of the microbial process using a mixture of sugars from cheap biomass in the near future.
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Affiliation(s)
- Hyun Gyu Lim
- />Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Pohang, 37673 Gyeongbuk Korea
| | - Jae Hyung Lim
- />School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Pohang, 37673 Gyeongbuk Korea
| | - Gyoo Yeol Jung
- />Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Pohang, 37673 Gyeongbuk Korea
- />School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Pohang, 37673 Gyeongbuk Korea
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20
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Abstract
Clustered regularly interspaced palindromic repeats (CRISPRs) and the CRISPR-associated (Cas) nuclease protect bacteria and archeae from foreign DNA by site-specific cleavage of incoming DNA. Type-II CRISPR–Cas systems, such as the Streptococcus pyogenes CRISPR–Cas9 system, can be adapted such that Cas9 can be guided to a user-defined site in the chromosome to introduce double-stranded breaks. Here we have developed and optimized CRISPR–Cas9 function in the lactic acid bacterium Lactobacillus reuteri ATCC PTA 6475. We established proof-of-concept showing that CRISPR–Cas9 selection combined with single-stranded DNA (ssDNA) recombineering is a realistic approach to identify at high efficiencies edited cells in a lactic acid bacterium. We show for three independent targets that subtle changes in the bacterial genome can be recovered at efficiencies ranging from 90 to 100%. By combining CRISPR–Cas9 and recombineering, we successfully applied codon saturation mutagenesis in the L. reuteri chromosome. Also, CRISPR–Cas9 selection is critical to identify low-efficiency events such as oligonucleotide-mediated chromosome deletions. This also means that CRISPR–Cas9 selection will allow identification of recombinant cells in bacteria with low recombineering efficiencies, eliminating the need for ssDNA recombineering optimization procedures. We envision that CRISPR–Cas genome editing has the potential to change the landscape of genome editing in lactic acid bacteria, and other Gram-positive bacteria.
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Affiliation(s)
- Jee-Hwan Oh
- Department of Food Science, 1605 Linden Dr, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jan-Peter van Pijkeren
- Department of Food Science, 1605 Linden Dr, University of Wisconsin-Madison, Madison, WI 53706, USA
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21
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Mechanism of homologous recombination and implications for aging-related deletions in mitochondrial DNA. Microbiol Mol Biol Rev 2014; 77:476-96. [PMID: 24006472 DOI: 10.1128/mmbr.00007-13] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Homologous recombination is a universal process, conserved from bacteriophage to human, which is important for the repair of double-strand DNA breaks. Recombination in mitochondrial DNA (mtDNA) was documented more than 4 decades ago, but the underlying molecular mechanism has remained elusive. Recent studies have revealed the presence of a Rad52-type recombination system of bacteriophage origin in mitochondria, which operates by a single-strand annealing mechanism independent of the canonical RecA/Rad51-type recombinases. Increasing evidence supports the notion that, like in bacteriophages, mtDNA inheritance is a coordinated interplay between recombination, repair, and replication. These findings could have profound implications for understanding the mechanism of mtDNA inheritance and the generation of mtDNA deletions in aging cells.
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22
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Lim JH, Seo SW, Kim SY, Jung GY. Model-driven rebalancing of the intracellular redox state for optimization of a heterologous n-butanol pathway in Escherichia coli. Metab Eng 2013; 20:56-62. [DOI: 10.1016/j.ymben.2013.09.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Revised: 08/07/2013] [Accepted: 09/11/2013] [Indexed: 12/23/2022]
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23
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Lim JH, Seo SW, Kim SY, Jung GY. Refactoring redox cofactor regeneration for high-yield biocatalysis of glucose to butyric acid in Escherichia coli. BIORESOURCE TECHNOLOGY 2013; 135:568-73. [PMID: 23127832 DOI: 10.1016/j.biortech.2012.09.091] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2012] [Revised: 09/23/2012] [Accepted: 09/25/2012] [Indexed: 05/20/2023]
Abstract
In this study, the native redox cofactor regeneration system in Escherichia coli was engineered for the production of butyric acid. The synthetic butyrate pathway, which regenerates NAD(+) from NADH using butyrate as the only final electron acceptor, enabled high-yield production of butyric acid from glucose (83.4% of the molar theoretical yield). The high selectivity for butyrate, with a butyrate/acetate ratio of 41, suggests dramatically improved industrial potential for the production of butyric acid from nonnative hosts compared to the native producers (Clostridium species). Furthermore, this strategy could be broadly utilized for the production of various other useful chemicals in the fields of metabolic engineering and synthetic biology.
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Affiliation(s)
- Jae Hyung Lim
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Nam-gu, Pohang, Gyeongbuk 790-784, South Korea
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24
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Mbantenkhu M, Wierzbicki S, Wang X, Guo S, Wilkens S, Chen XJ. A short carboxyl-terminal tail is required for single-stranded DNA binding, higher-order structural organization, and stability of the mitochondrial single-stranded annealing protein Mgm101. Mol Biol Cell 2013; 24:1507-18. [PMID: 23536705 PMCID: PMC3655812 DOI: 10.1091/mbc.e13-01-0006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Mgm101 is a Rad52-type single-stranded annealing protein (SSAP) required for mitochondrial DNA (mtDNA) repair and maintenance. Structurally, Mgm101 forms large oligomeric rings. Here we determine the function(s) of a 32-amino acid carboxyl-terminal tail (Mgm101(238-269)) conserved in the Mgm101 family of proteins. Mutagenic analysis shows that Lys-253, Trp-257, Arg-259, and Tyr-268 are essential for mtDNA maintenance. Mutations in Lys-251, Arg-252, Lys-260, and Tyr-266 affect mtDNA stability at 37°C and under oxidative stress. The Y268A mutation severely affects single-stranded DNA (ssDNA) binding without altering the ring structure. Mutations in the Lys-251-Arg-252-Lys-253 positive triad also affect ssDNA binding. Moreover, the C-tail alone is sufficient to mediate ssDNA binding. Finally, we find that the W257A and R259A mutations dramatically affect the conformation and oligomeric state of Mgm101. These structural alterations correlate with protein degradation in vivo. The data thus indicate that the C-tail of Mgm101, likely displayed on the ring surface, is required for ssDNA binding, higher-order structural organization, and protein stability. We speculate that an initial electrostatic and base-stacking interaction with ssDNA could remodel ring organization. This may facilitate the formation of nucleoprotein filaments competent for mtDNA repair. These findings could have broad implications for understanding how SSAPs promote DNA repair and genome maintenance.
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Affiliation(s)
- MacMillan Mbantenkhu
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, NY 13210, USA
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25
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Boyle NR, Reynolds TS, Evans R, Lynch M, Gill RT. Recombineering to homogeneity: extension of multiplex recombineering to large-scale genome editing. Biotechnol J 2013; 8:515-22. [PMID: 23436787 DOI: 10.1002/biot.201200237] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Revised: 12/17/2012] [Accepted: 01/22/2013] [Indexed: 11/08/2022]
Abstract
Recombineering has been an essential tool for genetic engineering in microbes for many years and has enabled faster, more efficient engineering than previous techniques. There have been numerous studies that focus on improving recombineering efficiency, which can be divided into three main areas: (i) optimizing the oligo used for recombineering to enhance replication fork annealing and limit proofreading; (ii) mechanisms to modify the replisome itself, enabling an increased rate of annealing; and (iii) multiplexing recombineering targets and automation. These efforts have increased the efficiency of recombineering several hundred-fold. One area that has received far less attention is the problem of multiple chromosomes, which effectively decrease efficiency on a chromosomal basis, resulting in more sectored colonies, which require longer outgrowth to obtain clonal populations. Herein, we describe the problem of multiple chromosomes, discuss calculations predicting how many generations are needed to obtain a pure colony, and how changes in experimental procedure or genetic background can minimize the effect of multiple chromosomes.
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Affiliation(s)
- Nanette R Boyle
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO, USA
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26
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Nardozzi JD, Wang X, Mbantenkhu M, Wilkens S, Chen XJ. A properly configured ring structure is critical for the function of the mitochondrial DNA recombination protein, Mgm101. J Biol Chem 2012; 287:37259-68. [PMID: 22948312 PMCID: PMC3481324 DOI: 10.1074/jbc.m112.389965] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 08/11/2012] [Indexed: 11/06/2022] Open
Abstract
Mgm101 is a Rad52-type recombination protein of bacteriophage origin required for the repair and maintenance of mitochondrial DNA (mtDNA). It forms large oligomeric rings of ∼14-fold symmetry that catalyze the annealing of single-stranded DNAs in vitro. In this study, we investigated the structural elements that contribute to this distinctive higher order structural organization and examined its functional implications. A pair of vicinal cysteines, Cys-216 and Cys-217, was found to be essential for mtDNA maintenance. Mutations to the polar serine, the negatively charged aspartic and glutamic acids, and the hydrophobic amino acid alanine all destabilize mtDNA in vivo. The alanine mutants have an increased propensity of forming macroscopic filaments. In contrast, mutations to aspartic acid drastically destabilize the protein and result in unstructured aggregates with severely reduced DNA binding activity. Interestingly, the serine mutants partially disassemble the Mgm101 rings into smaller oligomers. In the case of the C216S mutant, a moderate increase in DNA binding activity was observed. By using small angle x-ray scattering analysis, we found that Mgm101 forms rings of ∼200 Å diameter in solution, consistent with the structure previously established by transmission electron microscopy. We also found that the C216A/C217A double mutant tends to form broken rings, which likely provide free ends for seeding the growth of the super-stable but functionally defective filaments. Taken together, our data underscore the importance of a delicately maintained ring structure critical for Mgm101 activity. We discuss a potential role of Cys-216 and Cys-217 in regulating Mgm101 function and the repair of damaged mtDNA under stress conditions.
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Affiliation(s)
- Jonathan D. Nardozzi
- From the Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, New York 13210
| | - Xiaowen Wang
- From the Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, New York 13210
| | - MacMillan Mbantenkhu
- From the Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, New York 13210
| | - Stephan Wilkens
- From the Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, New York 13210
| | - Xin Jie Chen
- From the Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, New York 13210
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27
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Abstract
The homologous recombination systems of linear double-stranded (ds)DNA bacteriophages are required for the generation of genetic diversity, the repair of dsDNA breaks, and the formation of concatemeric chromosomes, the immediate precursor to packaging. These systems have been studied for decades as a means to understand the basic principles of homologous recombination. From the beginning, it was recognized that these recombinases are linked intimately to the mechanisms of phage DNA replication. In the last decade, however, investigators have exploited these recombination systems as tools for genetic engineering of bacterial chromosomes, bacterial artificial chromosomes, and plasmids. This recombinational engineering technology has been termed "recombineering" and offers a new paradigm for the genetic manipulation of bacterial chromosomes, which is far more efficient than the classical use of nonreplicating integration vectors for gene replacement. The phage λ Red recombination system, in particular, has been used to construct gene replacements, deletions, insertions, inversions, duplications, and single base pair changes in the Escherichia coli chromosome. This chapter discusses the components of the recombination systems of λ, rac prophage, and phage P22 and properties of single-stranded DNA annealing proteins from these and other phage that have been instrumental for the development of this technology. The types of genetic manipulations that can be made are described, along with proposed mechanisms for both double-stranded DNA- and oligonucleotide-mediated recombineering events. Finally, the impact of this technology to such diverse fields as bacterial pathogenesis, metabolic engineering, and mouse genomics is discussed.
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Affiliation(s)
- Kenan C Murphy
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA, USA.
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28
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Schumacher AJ, Mohni KN, Kan Y, Hendrickson EA, Stark JM, Weller SK. The HSV-1 exonuclease, UL12, stimulates recombination by a single strand annealing mechanism. PLoS Pathog 2012; 8:e1002862. [PMID: 22912580 PMCID: PMC3415443 DOI: 10.1371/journal.ppat.1002862] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Accepted: 07/01/2012] [Indexed: 11/19/2022] Open
Abstract
Production of concatemeric DNA is an essential step during HSV infection, as the packaging machinery must recognize longer-than-unit-length concatemers; however, the mechanism by which they are formed is poorly understood. Although it has been proposed that the viral genome circularizes and rolling circle replication leads to the formation of concatemers, several lines of evidence suggest that HSV DNA replication involves recombination-dependent replication reminiscent of bacteriophages λ and T4. Similar to λ, HSV-1 encodes a 5′-to-3′ exonuclease (UL12) and a single strand annealing protein [SSAP (ICP8)] that interact with each other and can perform strand exchange in vitro. By analogy with λ phage, HSV may utilize viral and/or cellular recombination proteins during DNA replication. At least four double strand break repair pathways are present in eukaryotic cells, and HSV-1 is known to manipulate several components of these pathways. Chromosomally integrated reporter assays were used to measure the repair of double strand breaks in HSV-infected cells. Single strand annealing (SSA) was increased in HSV-infected cells, while homologous recombination (HR), non-homologous end joining (NHEJ) and alternative non-homologous end joining (A-NHEJ) were decreased. The increase in SSA was abolished when cells were infected with a viral mutant lacking UL12. Moreover, expression of UL12 alone caused an increase in SSA, which was completely eliminated when a UL12 mutant lacking exonuclease activity was expressed. UL12-mediated stimulation of SSA was decreased in cells lacking the cellular SSAP, Rad52, and could be restored by coexpressing the viral SSAP, ICP8, indicating that an SSAP is also required. These results demonstrate that UL12 can specifically stimulate SSA and that either ICP8 or Rad52 can function as an SSAP. We suggest that SSA is the homology-mediated repair pathway utilized during HSV infection. The repair of DNA damage is essential to maintain genomic stability. Cells have at least four distinct DNA repair pathways, and defects in any of them can lead to tumor formation and cancer progression. Herpes Simplex Virus-1 (HSV-1) manipulates components of the host DNA repair pathways. In this paper we showed that DNA repair by the single strand annealing (SSA) pathway was increased during HSV infection and that other pathways were inhibited. We also show that a viral nuclease in conjunction with either a viral or cellular single strand annealing protein can stimulate the SSA pathway. We suggest that viral DNA synthesis occurs via an SSAdependent mechanism that is reminiscent of that used by bacterial viruses such as λ. Interestingly, λ has evolved an SSA-mediated repair mechanism to exchange genetic information that has also been used to enhance gene targeting in bacteria. It is thus possible that HSV proteins could be similarly used as tools to stimulate gene targeting in human cells leading to more effective strategies for gene therapy. Furthermore, the diversity of HSV reported in human populations, combined with the high rate of genetic exchange during infection, suggests that SSA may play a role in viral evolution and pathogenesis.
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Affiliation(s)
- April J. Schumacher
- Molecular, Microbial and Structural Biology Department, University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Kareem N. Mohni
- Molecular, Microbial and Structural Biology Department, University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Yinan Kan
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, Minnesota, United States of America
| | - Eric A. Hendrickson
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, Minnesota, United States of America
| | - Jeremy M. Stark
- Department of Cancer Biology, Beckman Research Institute of the City of Hope, Duarte, California, United States of America
| | - Sandra K. Weller
- Molecular, Microbial and Structural Biology Department, University of Connecticut Health Center, Farmington, Connecticut, United States of America
- * E-mail:
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29
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Cho HS, Seo SW, Kim YM, Jung GY, Park JM. Engineering glyceraldehyde-3-phosphate dehydrogenase for switching control of glycolysis in Escherichia coli. Biotechnol Bioeng 2012; 109:2612-9. [PMID: 22528318 DOI: 10.1002/bit.24532] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Revised: 03/20/2012] [Accepted: 04/13/2012] [Indexed: 11/06/2022]
Abstract
Glycolysis has evolved to be a highly robust mechanism for maintaining the cellular metabolism of living organisms. However, relevant modifications of glycolytic activity are required to intentionally modulate cellular phenotypes. Here, we designed a platform that allows switching control of glycolysis in Escherichia coli in response to an environmental signal, in this case, temperature. This system functions by regulating the expression of gapA, which encodes glyceraldehyde-3-phosphate dehydrogenase (GAPDH), one of the key glycolytic enzymes. Because a very low level of gapA expression is capable of maintaining cellular physiology, we also modified GAPDH through directed evolution to provide sensitive regulation of glycolytic activity. The switching control of glycolysis was successfully demonstrated by regulating the expression of engineered gapA through changes in temperature. This system offers potential control over the cell's central carbon-metabolism switch, providing the ability to perform reprogrammed tasks with desired timing depending on environmental signals.
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Affiliation(s)
- Han-Saem Cho
- Department of Chemical Engineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Nam-gu, Pohang, Gyeong-buk 790-784, South Korea
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30
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Lambda red recombineering in Escherichia coli occurs through a fully single-stranded intermediate. Genetics 2010; 186:791-9. [PMID: 20813883 DOI: 10.1534/genetics.110.120782] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The phage lambda-derived Red recombination system is a powerful tool for making targeted genetic changes in Escherichia coli, providing a simple and versatile method for generating insertion, deletion, and point mutations on chromosomal, plasmid, or BAC targets. However, despite the common use of this system, the detailed mechanism by which lambda Red mediates double-stranded DNA recombination remains uncertain. Current mechanisms posit a recombination intermediate in which both 5' ends of double-stranded DNA are recessed by λ exonuclease, leaving behind 3' overhangs. Here, we propose an alternative in which lambda exonuclease entirely degrades one strand, while leaving the other strand intact as single-stranded DNA. This single-stranded intermediate then recombines via beta recombinase-catalyzed annealing at the replication fork. We support this by showing that single-stranded gene insertion cassettes are recombinogenic and that these cassettes preferentially target the lagging strand during DNA replication. Furthermore, a double-stranded DNA cassette containing multiple internal mismatches shows strand-specific mutations cosegregating roughly 80% of the time. These observations are more consistent with our model than with previously proposed models. Finally, by using phosphorothioate linkages to protect the lagging-targeting strand of a double-stranded DNA cassette, we illustrate how our new mechanistic knowledge can be used to enhance lambda Red recombination frequency. The mechanistic insights revealed by this work may facilitate further improvements to the versatility of lambda Red recombination.
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Maresca M, Erler A, Fu J, Friedrich A, Zhang Y, Stewart AF. Single-stranded heteroduplex intermediates in lambda Red homologous recombination. BMC Mol Biol 2010; 11:54. [PMID: 20670401 PMCID: PMC2918612 DOI: 10.1186/1471-2199-11-54] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Accepted: 07/29/2010] [Indexed: 11/28/2022] Open
Abstract
Background The Red proteins of lambda phage mediate probably the simplest and most efficient homologous recombination reactions yet described. However the mechanism of dsDNA recombination remains undefined. Results Here we show that the Red proteins can act via full length single stranded intermediates to establish single stranded heteroduplexes at the replication fork. We created asymmetrically digestible dsDNA substrates by exploiting the fact that Redα exonuclease activity requires a 5' phosphorylated end, or is blocked by phosphothioates. Using these substrates, we found that the most efficient configuration for dsDNA recombination occurred when the strand that can prime Okazaki-like synthesis contained both homology regions on the same ssDNA molecule. Furthermore, we show that Red recombination requires replication of the target molecule. Conclusions Hence we propose a new model for dsDNA recombination, termed 'beta' recombination, based on the formation of ssDNA heteroduplexes at the replication fork. Implications of the model were tested using (i) an in situ assay for recombination, which showed that recombination generated mixed wild type and recombinant colonies; and (ii) the predicted asymmetries of the homology arms, which showed that recombination is more sensitive to non-homologies attached to 5' than 3' ends. Whereas beta recombination can generate deletions in target BACs of at least 50 kb at about the same efficiency as small deletions, the converse event of insertion is very sensitive to increasing size. Insertions up to 3 kb are most efficiently achieved using beta recombination, however at greater sizes, an alternative Red-mediated mechanism(s) appears to be equally efficient. These findings define a new intermediate in homologous recombination, which also has practical implications for recombineering with the Red proteins.
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Affiliation(s)
- Marcello Maresca
- Technische Universität Dresden, BioInnovationsZentrum, Dresden, Germany
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