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Zhou H, Zhang Y, Long CP, Xia X, Xue Y, Ma Y, Antoniewicz MR, Tao Y, Lin B. A citric acid cycle-deficient Escherichia coli as an efficient chassis for aerobic fermentations. Nat Commun 2024; 15:2372. [PMID: 38491007 PMCID: PMC10943122 DOI: 10.1038/s41467-024-46655-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 03/05/2024] [Indexed: 03/18/2024] Open
Abstract
Tricarboxylic acid cycle (TCA cycle) plays an important role for aerobic growth of heterotrophic bacteria. Theoretically, eliminating TCA cycle would decrease carbon dissipation and facilitate chemicals biosynthesis. Here, we construct an E. coli strain without a functional TCA cycle that can serve as a versatile chassis for chemicals biosynthesis. We first use adaptive laboratory evolution to recover aerobic growth in minimal medium of TCA cycle-deficient E. coli. Inactivation of succinate dehydrogenase is a key event in the evolutionary trajectory. Supply of succinyl-CoA is identified as the growth limiting factor. By replacing endogenous succinyl-CoA dependent enzymes, we obtain an optimized TCA cycle-deficient E. coli strain. As a proof of concept, the strain is engineered for high-yield production of four separate products. This work enhances our understanding of the role of the TCA cycle in E. coli metabolism and demonstrates the advantages of using TCA cycle-deficient E. coli strain for biotechnological applications.
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Affiliation(s)
- Hang Zhou
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Yiwen Zhang
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Christopher P Long
- Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark, DE, 19716, USA
| | - Xuesen Xia
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, 510006, China
| | - Yanfen Xue
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China
| | - Yanhe Ma
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China.
| | - Maciek R Antoniewicz
- Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark, DE, 19716, USA.
- Department of Chemical Engineering, University of Michigan, Ann Arbor, MI, USA.
| | - Yong Tao
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China.
- University of Chinese Academy of Sciences, 100049, Beijing, China.
| | - Baixue Lin
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China.
- University of Chinese Academy of Sciences, 100049, Beijing, China.
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2
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Kulakowski S, Banerjee D, Scown CD, Mukhopadhyay A. Improving microbial bioproduction under low-oxygen conditions. Curr Opin Biotechnol 2023; 84:103016. [PMID: 37924688 DOI: 10.1016/j.copbio.2023.103016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 09/17/2023] [Accepted: 10/07/2023] [Indexed: 11/06/2023]
Abstract
Microbial bioconversion provides access to a wide range of sustainably produced chemicals and commodities. However, industrial-scale bioproduction process operations are preferred to be anaerobic due to the cost associated with oxygen transfer. Anaerobic bioconversion generally offers limited substrate utilization profiles, lower product yields, and reduced final product diversity compared with aerobic processes. Bioproduction under conditions of reduced oxygen can overcome the limitations of fully aerobic and anaerobic bioprocesses, but many microbial hosts are not developed for low-oxygen bioproduction. Here, we describe advances in microbial strain engineering involving the use of redox cofactor engineering, genome-scale metabolic modeling, and functional genomics to enable improved bioproduction processes under low oxygen and provide a viable path for scaling these bioproduction systems to industrial scales.
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Affiliation(s)
- Shawn Kulakowski
- Joint BioEnergy Institute, Emeryville, CA 94608, USA; Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Deepanwita Banerjee
- Joint BioEnergy Institute, Emeryville, CA 94608, USA; Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Corinne D Scown
- Joint BioEnergy Institute, Emeryville, CA 94608, USA; Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Energy Analysis and Environmental Impacts Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Aindrila Mukhopadhyay
- Joint BioEnergy Institute, Emeryville, CA 94608, USA; Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Environmental Genomics & Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
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3
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TeSlaa T, Ralser M, Fan J, Rabinowitz JD. The pentose phosphate pathway in health and disease. Nat Metab 2023; 5:1275-1289. [PMID: 37612403 PMCID: PMC11251397 DOI: 10.1038/s42255-023-00863-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 07/12/2023] [Indexed: 08/25/2023]
Abstract
The pentose phosphate pathway (PPP) is a glucose-oxidizing pathway that runs in parallel to upper glycolysis to produce ribose 5-phosphate and nicotinamide adenine dinucleotide phosphate (NADPH). Ribose 5-phosphate is used for nucleotide synthesis, while NADPH is involved in redox homoeostasis as well as in promoting biosynthetic processes, such as the synthesis of tetrahydrofolate, deoxyribonucleotides, proline, fatty acids and cholesterol. Through NADPH, the PPP plays a critical role in suppressing oxidative stress, including in certain cancers, in which PPP inhibition may be therapeutically useful. Conversely, PPP-derived NADPH also supports purposeful cellular generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) for signalling and pathogen killing. Genetic deficiencies in the PPP occur relatively commonly in the committed pathway enzyme glucose-6-phosphate dehydrogenase (G6PD). G6PD deficiency typically manifests as haemolytic anaemia due to red cell oxidative damage but, in severe cases, also results in infections due to lack of leucocyte oxidative burst, highlighting the dual redox roles of the pathway in free radical production and detoxification. This Review discusses the PPP in mammals, covering its roles in biochemistry, physiology and disease.
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Affiliation(s)
- Tara TeSlaa
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA.
| | - Markus Ralser
- Department of Biochemistry, Charité Universitätsmedizin, Berlin, Germany
- The Wellcome Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Jing Fan
- Morgride Institute for Research, Madison, WI, USA
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Joshua D Rabinowitz
- Lewis Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA.
- Department of Chemistry, Princeton University, Princeton, NJ, USA.
- Ludwig Institute for Cancer Research, Princeton Branch, Princeton, NJ, USA.
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4
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Poladyan A, Trchounian K, Paloyan A, Minasyan E, Aghekyan H, Iskandaryan M, Khoyetsyan L, Aghayan S, Tsaturyan A, Antranikian G. Valorization of whey-based side streams for microbial biomass, molecular hydrogen, and hydrogenase production. Appl Microbiol Biotechnol 2023:10.1007/s00253-023-12609-x. [PMID: 37289241 DOI: 10.1007/s00253-023-12609-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 05/18/2023] [Accepted: 05/19/2023] [Indexed: 06/09/2023]
Abstract
Side streams of the dairy industry are a suitable nutrient source for cultivating microorganisms, producing enzymes, and high-value chemical compounds. The heterotrophic Escherichia coli and chemolithoautotroph Ralstonia eutropha are of major biotechnological interest. R. eutropha is a model organism for producing O2-tolerant [NiFe]-hydrogenases (Hyds) (biocatalysts), and E. coli has found widespread use as an expression platform for producing recombinant proteins, molecular hydrogen (H2), and other valuable products. Aiming at developing suitable cultivation media from side streams of the dairy industry, the pre-treatment (filtration, dilution, and pH adjustment) of cheese (sweet) whey (SW) and curd (acid) whey (AW), with and without the use of ß-glucosidase, has been performed. Growth parameters (oxidation-reduction potential (ORP), pH changes, specific growth rate, biomass formation) of E. coli BW25113 and R. eutropha H16 type strains were monitored during cultivation on filtered and non-filtered SW and AW at 37 °C, pH 7.5 and 30 °C, pH 7.0, respectively. Along with microbial growth, measurements of pH and ORP indicated good fermentative growth. Compared to growth on fructose-nitrogen minimal salt medium (control), a maximum cell yield (OD600 4.0) and H2-oxidizing Hyd activity were achieved in the stationary growth phase for R. eutropha. Hyd-3-dependent H2 production by E. coli utilizing whey as a growth substrate was demonstrated. Moreover, good biomass production and prolonged H2 yields of ~ 5 mmol/L and cumulative H2 ~ 94 mL g/L dry whey (DW) (ß-glucosidase-treated) were observed during the cultivation of the engineered E. coli strain. These results open new avenues for effective whey treatment using thermostable β-glucosidase and confirm whey as an economically viable commodity for biomass and biocatalyst production. KEY POINTS: • Archaeal thermostable β-glucosidase isolated from the metagenome of a hydrothermal spring was used for lactose hydrolysis in whey. • Hydrogenase enzyme activity was induced during the growth of Ralstonia eutropha H16 on whey. • Enhanced biomass and H2 production was shown in a genetically modified strain of Escherichia coli.
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Affiliation(s)
- Anna Poladyan
- Department of Biochemistry, Microbiology, and Biotechnology, Yerevan State University, Yerevan, Armenia, 1 A. Manoukian Str, 0025, Yerevan, Armenia.
- Research Institute of Biology, Biology Faculty, Yerevan State University, 0025, Yerevan, Armenia.
| | - Karen Trchounian
- Department of Biochemistry, Microbiology, and Biotechnology, Yerevan State University, Yerevan, Armenia, 1 A. Manoukian Str, 0025, Yerevan, Armenia
- Research Institute of Biology, Biology Faculty, Yerevan State University, 0025, Yerevan, Armenia
| | - Ani Paloyan
- SPC "Armbiotechnology" NAS RA, Yerevan, Armenia
| | - Ela Minasyan
- Institute of Pharmacy, Yerevan State University, 0025, Yerevan, Armenia
| | - Hayarpi Aghekyan
- Department of Biochemistry, Microbiology, and Biotechnology, Yerevan State University, Yerevan, Armenia, 1 A. Manoukian Str, 0025, Yerevan, Armenia
- Research Institute of Biology, Biology Faculty, Yerevan State University, 0025, Yerevan, Armenia
| | - Meri Iskandaryan
- Department of Biochemistry, Microbiology, and Biotechnology, Yerevan State University, Yerevan, Armenia, 1 A. Manoukian Str, 0025, Yerevan, Armenia
- Research Institute of Biology, Biology Faculty, Yerevan State University, 0025, Yerevan, Armenia
| | | | - Sargis Aghayan
- Research Institute of Biology, Biology Faculty, Yerevan State University, 0025, Yerevan, Armenia
| | - Avetis Tsaturyan
- SPC "Armbiotechnology" NAS RA, Yerevan, Armenia
- Institute of Pharmacy, Yerevan State University, 0025, Yerevan, Armenia
| | - Garabed Antranikian
- Hamburg University of Technology, Institute of Technical Biocatalysis, Hamburg, Germany
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5
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Zhang Y, Yun J, Zabed HM, Dou Y, Zhang G, Zhao M, Taherzadeh MJ, Ragauskas A, Qi X. High-level co-production of 3-hydroxypropionic acid and 1,3-propanediol from glycerol: Metabolic engineering and process optimization. BIORESOURCE TECHNOLOGY 2023; 369:128438. [PMID: 36470488 DOI: 10.1016/j.biortech.2022.128438] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Revised: 11/30/2022] [Accepted: 12/01/2022] [Indexed: 06/17/2023]
Abstract
3-Hydroxypropionic acid (3-HP) and 1,3-propanediol (1,3-PDO) are value-added chemicals with versatile applications in the chemical, pharmaceutical, and food industries. Nevertheless, sustainable production of 3-HP and 1,3-PDO is often limited by the lack of efficient strains and suitable fermentation configurations. Herein, attempts have been made to improve the co-production of both metabolites through metabolic engineering of Escherichia coli and process optimization. First, the 3-HP and 1,3-PDO co-biosynthetic pathways were recruited and optimized in E. coli, followed by coupling the pathways to the transhydrogenase-mediated cofactor regeneration systems that increased cofactor availability and product synthesis. Next, pathway rebalancing and block of by-product formation significantly improved 3-HP and 1,3-PDO net titer. Subsequently, glycerol flux toward 3-HP and 1,3-PDO synthesis was maximized by removing metabolic repression and fine-tuning the glycerol oxidation pathway. Lastly, the combined fermentation process optimization and two-stage pH-controlled fed-batch fermentation co-produced 140.50 g/L 3-HP and 1,3-PDO, with 0.85 mol/mol net yield.
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Affiliation(s)
- Yufei Zhang
- School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, Jiangsu, PR China
| | - Junhua Yun
- School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, Jiangsu, PR China
| | - Hossain M Zabed
- School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, Jiangsu, PR China
| | - Yuan Dou
- School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, Jiangsu, PR China
| | - Guoyan Zhang
- School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, Jiangsu, PR China
| | - Mei Zhao
- School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, Jiangsu, PR China
| | | | - Arthur Ragauskas
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN 37996, USA; Joint Institute for Biological Sciences, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA; Center for Renewable Carbon, Department of Forestry, Wildlife and Fisheries, The University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Xianghui Qi
- School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, Jiangsu, PR China.
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6
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Experimental Evolution Reveals Unifying Systems-Level Adaptations but Diversity in Driving Genotypes. mSystems 2022; 7:e0016522. [PMID: 36226969 PMCID: PMC9765567 DOI: 10.1128/msystems.00165-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Genotype-fitness maps of evolution have been well characterized for biological components, such as RNA and proteins, but remain less clear for systems-level properties, such as those of metabolic and transcriptional regulatory networks. Here, we take multi-omics measurements of 6 different E. coli strains throughout adaptive laboratory evolution (ALE) to maximal growth fitness. The results show the following: (i) convergence in most overall phenotypic measures across all strains, with the notable exception of divergence in NADPH production mechanisms; (ii) conserved transcriptomic adaptations, describing increased expression of growth promoting genes but decreased expression of stress response and structural components; (iii) four groups of regulatory trade-offs underlying the adjustment of transcriptome composition; and (iv) correlates that link causal mutations to systems-level adaptations, including mutation-pathway flux correlates and mutation-transcriptome composition correlates. We thus show that fitness landscapes for ALE can be described with two layers of causation: one based on system-level properties (continuous variables) and the other based on mutations (discrete variables). IMPORTANCE Understanding the mechanisms of microbial adaptation will help combat the evolution of drug-resistant microbes and enable predictive genome design. Although experimental evolution allows us to identify the causal mutations underlying microbial adaptation, it remains unclear how causal mutations enable increased fitness and is often explained in terms of individual components (i.e., enzyme rate) as opposed to biological systems (i.e., pathways). Here, we find that causal mutations in E. coli are linked to systems-level changes in NADPH balance and expression of stress response genes. These systems-level adaptation patterns are conserved across diverse E. coli strains and thus identify cofactor balance and proteome reallocation as dominant constraints governing microbial adaptation.
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7
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King E, Maxel S, Zhang Y, Kenney KC, Cui Y, Luu E, Siegel JB, Weiss GA, Luo R, Li H. Orthogonal glycolytic pathway enables directed evolution of noncanonical cofactor oxidase. Nat Commun 2022; 13:7282. [PMID: 36435948 PMCID: PMC9701214 DOI: 10.1038/s41467-022-35021-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 11/15/2022] [Indexed: 11/28/2022] Open
Abstract
Noncanonical cofactor biomimetics (NCBs) such as nicotinamide mononucleotide (NMN+) provide enhanced scalability for biomanufacturing. However, engineering enzymes to accept NCBs is difficult. Here, we establish a growth selection platform to evolve enzymes to utilize NMN+-based reducing power. This is based on an orthogonal, NMN+-dependent glycolytic pathway in Escherichia coli which can be coupled to any reciprocal enzyme to recycle the ensuing reduced NMN+. With a throughput of >106 variants per iteration, the growth selection discovers a Lactobacillus pentosus NADH oxidase variant with ~10-fold increase in NMNH catalytic efficiency and enhanced activity for other NCBs. Molecular modeling and experimental validation suggest that instead of directly contacting NCBs, the mutations optimize the enzyme's global conformational dynamics to resemble the WT with the native cofactor bound. Restoring the enzyme's access to catalytically competent conformation states via deep navigation of protein sequence space with high-throughput evolution provides a universal route to engineer NCB-dependent enzymes.
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Affiliation(s)
- Edward King
- Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, CA, 92697, USA
| | - Sarah Maxel
- Department Chemical and Biomolecular Engineering University of California Irvine, Irvine, CA, 92697, USA
| | - Yulai Zhang
- Department Chemical and Biomolecular Engineering University of California Irvine, Irvine, CA, 92697, USA
| | - Karissa C Kenney
- Department of Chemistry, University of California Irvine, Irvine, CA, 92697, USA
| | - Youtian Cui
- Genome Center, University of California Davis, Davis, CA, 95616, USA
| | - Emma Luu
- Genome Center, University of California Davis, Davis, CA, 95616, USA
| | - Justin B Siegel
- Genome Center, University of California Davis, Davis, CA, 95616, USA
- Department of Chemistry, Molecular Medicine University of California, Davis, Davis, CA, USA
- Department of Biochemistry and Molecular Medicine University of California, Davis, Davis, CA, USA
| | - Gregory A Weiss
- Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, CA, 92697, USA
- Department of Chemistry, University of California Irvine, Irvine, CA, 92697, USA
- Department of Pharmaceutical Sciences, University of California Irvine, Irvine, CA, 92697, USA
| | - Ray Luo
- Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, CA, 92697, USA
- Department Chemical and Biomolecular Engineering University of California Irvine, Irvine, CA, 92697, USA
- Department Materials Science and Engineering, University of California Irvine, Irvine, CA, 92697, USA
- Department of Biomedical Engineering, University of California Irvine, Irvine, CA, 92697, USA
| | - Han Li
- Department Chemical and Biomolecular Engineering University of California Irvine, Irvine, CA, 92697, USA.
- Department of Biomedical Engineering, University of California Irvine, Irvine, CA, 92697, USA.
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8
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Kim YE, Cho KH, Bang I, Kim CH, Ryu YS, Kim Y, Choi EM, Nong LK, Kim D, Lee SK. Characterization of an Entner-Doudoroff pathway-activated Escherichia coli. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2022; 15:120. [PMID: 36352474 PMCID: PMC9648032 DOI: 10.1186/s13068-022-02219-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 10/26/2022] [Indexed: 06/16/2023]
Abstract
BACKGROUND Escherichia coli have both the Embden-Meyerhof-Parnas pathway (EMPP) and Entner-Doudoroff pathway (EDP) for glucose breakdown, while the EDP primarily remains inactive for glucose metabolism. However, EDP is a more favorable route than EMPP for the production of certain products. RESULTS EDP was activated by deleting the pfkAB genes in conjunction with subsequent adaptive laboratory evolution (ALE). The evolved strains acquired mutations in transcriptional regulatory genes for glycolytic process (crp, galR, and gntR) and in glycolysis-related genes (gnd, ptsG, and talB). The genotypic, transcriptomic and phenotypic analyses of those mutations deepen our understanding of their beneficial effects on cellulosic biomass bio-conversion. On top of these scientific understandings, we further engineered the strain to produce higher level of lycopene and 3-hydroxypropionic acid. CONCLUSIONS These results indicate that the E. coli strain has innate capability to use EDP in lieu of EMPP for glucose metabolism, and this versatility can be harnessed to further engineer E. coli for specific biotechnological applications.
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Affiliation(s)
- Ye Eun Kim
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Kyung Hyun Cho
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Ina Bang
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Chang Hee Kim
- Department of Biomedical Engineering, UNIST, Ulsan, 44919, Republic of Korea
| | - Young Shin Ryu
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Yuchan Kim
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Eun Mi Choi
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Linh Khanh Nong
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Donghyuk Kim
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea.
- Department of Biomedical Engineering, UNIST, Ulsan, 44919, Republic of Korea.
| | - Sung Kuk Lee
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea.
- Department of Biomedical Engineering, UNIST, Ulsan, 44919, Republic of Korea.
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9
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Jindal S, Iyer MS, Jyoti P, Masakapalli SK, Venkatesh KV. Mutants lacking global regulators, fis and arcA, in Escherichia coli enhanced growth fitness under acetate metabolism by pathway reprogramming. Appl Microbiol Biotechnol 2022; 106:3231-3243. [PMID: 35416487 DOI: 10.1007/s00253-022-11890-6] [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: 08/13/2021] [Revised: 03/20/2022] [Accepted: 03/21/2022] [Indexed: 11/25/2022]
Abstract
Global regulatory transcription factors play a significant role in controlling microbial metabolism under genetic and environmental perturbations. A system-level effect of carbon sources such as acetate on microbial metabolism under disrupted global regulators has not been well established. Acetate is one of the major substrates available in various nutrient niches such as the mammalian gut and a keto diet. A substantial amount of acetate gets secreted in aerobic metabolism. Therefore, investigating the study on acetate metabolism is highly significant. It is known that the global regulators fis and arcA regulate acetate uptake genes in E. coli under glucose conditions. This study deciphered the growth and flux distribution of E. coli transcription regulatory knockouts Δfis, ΔarcA and double deletion mutant, ΔarcAΔfis under acetate using 13C-metabolic flux analysis (MFA), which has not been investigated before. We observed that the mutants exhibited an expeditious growth rate (~ 1.2-1.6-fold) with a proportionate increase in acetate uptake rates compared to the wild type. 13C-MFA displayed the distinct metabolic reprogramming of intracellular fluxes via the TCA cycle, anaplerotic pathway and gluconeogenesis, which conferred an advantage of a faster growth rate with better carbon usage in all the mutants. This resulted in higher metabolic fluxes through the TCA cycle (~ 18-90%), lower gluconeogenesis (~ 15-35%) and higher CO2 and ATP production with the proportional increase in growth rate. The study reveals a novel insight by stating the sub-optimality of the wild-type strain grown under acetate substrate aerobically. These mutant strains efficiently oxidize acetate, thus acting as potential candidates for the biosynthesis of isoprenoids, biofuels, vitamins and various pharmaceutical products.Key Points• Mutants exhibited a better balance between energy and precursor synthesis than WT.• Leveraged in the unravelling of regulatory control under various nutrient shifts.• Metabolic readjustment resulted in optimal biomass requirement and faster growth.
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Affiliation(s)
- Shikha Jindal
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Mahesh S Iyer
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Poonam Jyoti
- BioX Center, School of Basic Sciences, Indian Institute of Technology Mandi, Kamand, 175075, India
| | - Shyam Kumar Masakapalli
- BioX Center, School of Basic Sciences, Indian Institute of Technology Mandi, Kamand, 175075, India.
| | - K V Venkatesh
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.
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10
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Toya Y, Hirono-Hara Y, Hirayama H, Kamata K, Tanaka R, Sano M, Kitamura S, Otsuka K, Abe-Yoshizumi R, Tsunoda SP, Kikukawa H, Kandori H, Shimizu H, Matsuda F, Ishii J, Hara KY. Optogenetic reprogramming of carbon metabolism using light-powering microbial proton pump systems. Metab Eng 2022; 72:227-236. [PMID: 35346842 DOI: 10.1016/j.ymben.2022.03.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 03/06/2022] [Accepted: 03/23/2022] [Indexed: 12/27/2022]
Abstract
In microbial fermentative production, ATP regeneration, while crucial for cellular processes, conflicts with efficient target chemical production because ATP regeneration exhausts essential carbon sources also required for target chemical biosynthesis. To wrestle with this dilemma, we harnessed the power of microbial rhodopsins with light-driven proton pumping activity to supplement with ATP, thereby facilitating the bioproduction of various chemicals. We first demonstrated a photo-driven ATP supply and redistribution of metabolic carbon flows to target chemical synthesis by installing already-known delta rhodopsin (dR) in Escherichia coli. In addition, we identified novel rhodopsins with higher proton pumping activities than dR, and created an engineered cell for in vivo self-supply of the rhodopsin-activator, all-trans-retinal. Our concept exploiting the light-powering ATP supplier offers a potential increase in carbon use efficiency for microbial productions through metabolic reprogramming.
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Affiliation(s)
- Yoshihiro Toya
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Yoko Hirono-Hara
- Department of Environmental and Life Sciences, School of Food and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Hidenobu Hirayama
- Engineering Biology Research Center, Kobe University, 1-1 Rokkodai, Nada, Kobe, Hyogo, 657-8501, Japan
| | - Kentaro Kamata
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Ryo Tanaka
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Mikoto Sano
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Sayaka Kitamura
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Kensuke Otsuka
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Rei Abe-Yoshizumi
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, Aichi, 466-8555, Japan; OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya, Aichi, 466-8555, Japan
| | - Satoshi P Tsunoda
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, Aichi, 466-8555, Japan; OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya, Aichi, 466-8555, Japan
| | - Hiroshi Kikukawa
- Department of Environmental and Life Sciences, School of Food and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan; Graduate Division of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, Aichi, 466-8555, Japan; OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya, Aichi, 466-8555, Japan
| | - Hiroshi Shimizu
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Fumio Matsuda
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Jun Ishii
- Engineering Biology Research Center, Kobe University, 1-1 Rokkodai, Nada, Kobe, Hyogo, 657-8501, Japan; Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodai, Nada, Kobe, Hyogo, 657-8501, Japan
| | - Kiyotaka Y Hara
- Department of Environmental and Life Sciences, School of Food and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan; Graduate Division of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan.
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11
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Wilkes RA, Waldbauer J, Aristilde L. Analogous Metabolic Decoupling in Pseudomonas putida and Comamonas testosteroni Implies Energetic Bypass to Facilitate Gluconeogenic Growth. mBio 2021; 12:e0325921. [PMID: 34903058 PMCID: PMC8669468 DOI: 10.1128/mbio.03259-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 11/04/2021] [Indexed: 11/30/2022] Open
Abstract
Gluconeogenic carbon metabolism is not well understood, especially within the context of flux partitioning between energy generation and biomass production, despite the importance of gluconeogenic carbon substrates in natural and engineered carbon processing. Here, using multiple omics approaches, we elucidate the metabolic mechanisms that facilitate gluconeogenic fast-growth phenotypes in Pseudomonas putida and Comamonas testosteroni, two Proteobacteria species with distinct metabolic networks. In contrast to the genetic constraint of C. testosteroni, which lacks the enzymes required for both sugar uptake and a complete oxidative pentose phosphate (PP) pathway, sugar metabolism in P. putida is known to generate surplus NADPH by relying on the oxidative PP pathway within its characteristic cyclic connection between the Entner-Doudoroff (ED) and Embden-Meyerhoff-Parnas (EMP) pathways. Remarkably, similar to the genome-based metabolic decoupling in C. testosteroni, our 13C-fluxomics reveals an inactive oxidative PP pathway and disconnected EMP and ED pathways in P. putida during gluconeogenic feeding, thus requiring transhydrogenase reactions to supply NADPH for anabolism in both species by leveraging the high tricarboxylic acid cycle flux during gluconeogenic growth. Furthermore, metabolomics and proteomics analyses of both species during gluconeogenic feeding, relative to glycolytic feeding, demonstrate a 5-fold depletion in phosphorylated metabolites and the absence of or up to a 17-fold decrease in proteins of the PP and ED pathways. Such metabolic remodeling, which is reportedly lacking in Escherichia coli exhibiting a gluconeogenic slow-growth phenotype, may serve to minimize futile carbon cycling while favoring the gluconeogenic metabolic regime in relevant proteobacterial species. IMPORTANCE Glycolytic metabolism of sugars is extensively studied in the Proteobacteria, but gluconeogenic carbon sources (e.g., organic acids, amino acids, aromatics) that feed into the tricarboxylic acid (TCA) cycle are widely reported to produce a fast-growth phenotype, particularly in species with biotechnological relevance. Much remains unknown about the importance of glycolysis-associated pathways in the metabolism of gluconeogenic carbon substrates. Here, we demonstrate that two distinct proteobacterial species, through genetic constraints or metabolic regulation at specific metabolic nodes, bypass the oxidative PP pathway during gluconeogenic growth and avoid unnecessary carbon fluxes by depleting protein investment into connected glycolysis pathways. Both species can leverage instead the high TCA cycle flux during gluconeogenic feeding to meet NADPH demand. Importantly, lack of a complete oxidative pentose phosphate pathway is a widespread metabolic trait in Proteobacteria with a gluconeogenic carbon preference, thus highlighting the important relevance of our findings toward elucidating the metabolic architecture in these bacteria.
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Affiliation(s)
- Rebecca A. Wilkes
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, New York, USA
- Department of Civil and Environmental Engineering, Northwestern University, Evanston, Illinois, USA
| | - Jacob Waldbauer
- Department of the Geophysical Sciences, University of Chicago, Chicago, Illinois, USA
| | - Ludmilla Aristilde
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, New York, USA
- Department of Civil and Environmental Engineering, Northwestern University, Evanston, Illinois, USA
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12
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Microbial protein cell factories fight back? Trends Biotechnol 2021; 40:576-590. [PMID: 34924209 DOI: 10.1016/j.tibtech.2021.10.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 10/01/2021] [Accepted: 10/01/2021] [Indexed: 01/26/2023]
Abstract
The biopharmaceutical market is growing faster than ever, with two production systems competing for market dominance: mammalian cells and microorganisms. In recent years, based on the rise of antibody-based therapies, new biotherapeutic approvals have favored mammalian hosts. However, not only has extensive research elevated our understanding of microbes to new levels, but emerging therapeutic molecules also facilitate their use; thus, is it time for microbes to fight back? In this review, we answer this timely question by cross-comparing four microbial production hosts and examining the innovations made to both their secretion and post-translational modification (PTM) capabilities. Furthermore, we discuss the impact of tools, such as omics and systems biology, as well as alternative production systems and emerging biotherapeutics.
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13
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Pyridoxal and α-ketoglutarate independently improve function of Saccharomyces cerevisiae Thi5 in the metabolic network of Salmonella enterica. J Bacteriol 2021; 204:e0045021. [PMID: 34662241 DOI: 10.1128/jb.00450-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microbial metabolism is often considered modular, but metabolic engineering studies have shown that transferring pathways, or modules, between organisms is not always straightforward. The Thi5-dependent pathway(s) for synthesis of the pyrimidine moiety of thiamine from Saccharomyces cerevisiae and Legionella pneumophila functioned differently when incorporated into the metabolic network of Salmonella enterica. Function of Thi5 from Saccharomyces cerevisiae (ScThi5) required modification of the underlying metabolic network, while LpThi5 functioned with the native network. Here we probe the metabolic requirements for heterologous function of ScThi5 and report a strong genetic and physiological evidence for a connection between alpha-ketoglutarate (αKG) levels and ScThi5 function. The connection was built with two classes of genetic suppressors linked to metabolic flux or metabolite pool changes. Further, direct modulation of nitrogen assimilation through nutritional or genetic modification implicated αKG levels in Thi5 function. Exogenous pyridoxal similarly improved ScThi5 function in S. enterica. Finally, directly increasing αKG and PLP with supplementation improved function of both ScThi5 and relevant variants of Thi5 from Legionella pneumophila (LpThi5). The data herein suggest structural differences between ScThi5 and LpThi5 impact their level of function in vivo and implicate αKG in supporting function of the Thi5 pathway when placed in the heterologous metabolic network of S. enterica. IMPORTANCE Thiamine biosynthesis is a model metabolic node that has been used to extend our understanding of metabolic network structure and individual enzyme function. The requirements for in vivo function of the Thi5-dependent pathway found in Legionella and yeast are poorly characterized. Here we suggest that αKG modulates function of the Thi5 pathway in S. enterica and provide evidence that structural variation between ScThi5 and LpThi5 contribute to their functional differences in a Salmonella enterica host.
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14
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Han JH, Jung ST, Oh MK. Improved Yield of Recombinant Protein via Flagella Regulator Deletion in Escherichia coli. Front Microbiol 2021; 12:655072. [PMID: 33790884 PMCID: PMC8005581 DOI: 10.3389/fmicb.2021.655072] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 02/22/2021] [Indexed: 11/13/2022] Open
Abstract
Protein production requires a significant amount of intracellular energy. Eliminating the flagella has been proposed to help Escherichia coli improve protein production by reducing energy consumption. In this study, the gene encoding a subunit of FlhC, a master regulator of flagella assembly, was deleted to reduce the expression of flagella-related genes. FlhC knockout in the ptsG-deleted strain triggered significant growth retardation with increased ATP levels and a higher NADPH/NADP+ ratio. Metabolic flux analysis using a 13C-labeled carbon substrate showed increased fluxes toward the pentose phosphate and tricarboxylic acid cycle pathways in the flhC- and ptsG-deleted strains. Introduction of a high copy number plasmid or overexpression of the recombinant protein in this strain restored growth rate without increasing glucose consumption. These results suggest that the metabolic burden caused by flhC deletion was resolved by recombinant protein production. The recombinant enhanced green fluorescent protein yield per glucose consumption increased 1.81-fold in the flhC mutant strain. Thus, our study demonstrates that high-yield production of the recombinant protein was achieved with reduced flagella formation.
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Affiliation(s)
- Jae-Ho Han
- Department of Chemical and Biological Engineering, Korea University, Seoul, South Korea
| | - Sang Taek Jung
- BK21 Graduate Program, Department of Biomedical Sciences, College of Medicine, Korea University, Seoul, South Korea
| | - Min-Kyu Oh
- Department of Chemical and Biological Engineering, Korea University, Seoul, South Korea
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15
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Lee C, Klockgether J, Fischer S, Trcek J, Tümmler B, Römling U. Why? - Successful Pseudomonas aeruginosa clones with a focus on clone C. FEMS Microbiol Rev 2021; 44:740-762. [PMID: 32990729 PMCID: PMC7685784 DOI: 10.1093/femsre/fuaa029] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 07/12/2020] [Indexed: 12/20/2022] Open
Abstract
The environmental species Pseudomonas aeruginosa thrives in a variety of habitats. Within the epidemic population structure of P. aeruginosa, occassionally highly successful clones that are equally capable to succeed in the environment and the human host arise. Framed by a highly conserved core genome, individual members of successful clones are characterized by a high variability in their accessory genome. The abundance of successful clones might be funded in specific features of the core genome or, although not mutually exclusive, in the variability of the accessory genome. In clone C, one of the most predominant clones, the plasmid pKLC102 and the PACGI-1 genomic island are two ubiquitous accessory genetic elements. The conserved transmissible locus of protein quality control (TLPQC) at the border of PACGI-1 is a unique horizontally transferred compository element, which codes predominantly for stress-related cargo gene products such as involved in protein homeostasis. As a hallmark, most TLPQC xenologues possess a core genome equivalent. With elevated temperature tolerance as a characteristic of clone C strains, the unique P. aeruginosa and clone C specific disaggregase ClpG is a major contributor to tolerance. As other successful clones, such as PA14, do not encode the TLPQC locus, ubiquitous denominators of success, if existing, need to be identified.
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Affiliation(s)
- Changhan Lee
- Department of Microbiology, Tumor and Cell Biology, Biomedicum C8, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Jens Klockgether
- Clinic for Paediatric Pneumology, Allergology and Neonatology, Clinical Research Group 'Pseudomonas Genomics', Hannover Medical School, D-30625 Hannover, Germany
| | - Sebastian Fischer
- Clinic for Paediatric Pneumology, Allergology and Neonatology, Clinical Research Group 'Pseudomonas Genomics', Hannover Medical School, D-30625 Hannover, Germany
| | - Janja Trcek
- Faculty of Natural Sciences and Mathematics, Department of Biology, University of Maribor, Maribor, 2000, Slovenia
| | - Burkhard Tümmler
- Clinic for Paediatric Pneumology, Allergology and Neonatology, Clinical Research Group 'Pseudomonas Genomics', Hannover Medical School, D-30625 Hannover, Germany
| | - Ute Römling
- Department of Microbiology, Tumor and Cell Biology, Biomedicum C8, Karolinska Institutet, SE-171 77 Stockholm, Sweden
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16
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Daloso DDM, Williams TCR. Current Challenges in Plant Systems Biology. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1346:155-170. [DOI: 10.1007/978-3-030-80352-0_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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17
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Mitigation of host cell mutations and regime shift during microbial fermentation: a perspective from flux memory. Curr Opin Biotechnol 2020; 66:227-235. [DOI: 10.1016/j.copbio.2020.08.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 08/01/2020] [Accepted: 08/12/2020] [Indexed: 12/19/2022]
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18
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Antoniewicz MR. A guide to metabolic flux analysis in metabolic engineering: Methods, tools and applications. Metab Eng 2020; 63:2-12. [PMID: 33157225 DOI: 10.1016/j.ymben.2020.11.002] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 10/28/2020] [Accepted: 11/01/2020] [Indexed: 12/22/2022]
Abstract
The field of metabolic engineering is primarily concerned with improving the biological production of value-added chemicals, fuels and pharmaceuticals through the design, construction and optimization of metabolic pathways, redirection of intracellular fluxes, and refinement of cellular properties relevant for industrial bioprocess implementation. Metabolic network models and metabolic fluxes are central concepts in metabolic engineering, as was emphasized in the first paper published in this journal, "Metabolic fluxes and metabolic engineering" (Metabolic Engineering, 1: 1-11, 1999). In the past two decades, a wide range of computational, analytical and experimental approaches have been developed to interrogate the capabilities of biological systems through analysis of metabolic network models using techniques such as flux balance analysis (FBA), and quantify metabolic fluxes using constrained-based modeling approaches such as metabolic flux analysis (MFA) and more advanced experimental techniques based on the use of stable-isotope tracers, i.e. 13C-metabolic flux analysis (13C-MFA). In this review, we describe the basic principles of metabolic flux analysis, discuss current best practices in flux quantification, highlight potential pitfalls and alternative approaches in the application of these tools, and give a broad overview of pragmatic applications of flux analysis in metabolic engineering practice.
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Affiliation(s)
- Maciek R Antoniewicz
- Department of Chemical Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Michigan, Ann Arbor, MI, 48109, USA.
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19
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Schober AF, Mathis AD, Ingle C, Park JO, Chen L, Rabinowitz JD, Junier I, Rivoire O, Reynolds KA. A Two-Enzyme Adaptive Unit within Bacterial Folate Metabolism. Cell Rep 2020; 27:3359-3370.e7. [PMID: 31189117 DOI: 10.1016/j.celrep.2019.05.030] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 04/05/2019] [Accepted: 05/09/2019] [Indexed: 11/29/2022] Open
Abstract
Enzyme function and evolution are influenced by the larger context of a metabolic pathway. Deleterious mutations or perturbations in one enzyme can often be compensated by mutations to others. We used comparative genomics and experiments to examine evolutionary interactions with the essential metabolic enzyme dihydrofolate reductase (DHFR). Analyses of synteny and co-occurrence across bacterial species indicate that DHFR is coupled to thymidylate synthase (TYMS) but relatively independent from the rest of folate metabolism. Using quantitative growth rate measurements and forward evolution in Escherichia coli, we demonstrate that the two enzymes adapt as a relatively independent unit in response to antibiotic stress. Metabolomic profiling revealed that TYMS activity must not exceed DHFR activity to prevent the depletion of reduced folates and the accumulation of the intermediate dihydrofolate. Comparative genomics analyses identified >200 gene pairs with similar statistical signatures of modular co-evolution, suggesting that cellular pathways may be decomposable into small adaptive units.
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Affiliation(s)
- Andrew F Schober
- The Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Andrew D Mathis
- The Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Christine Ingle
- The Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Junyoung O Park
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA; Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Li Chen
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA; Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
| | - Joshua D Rabinowitz
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA; Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
| | - Ivan Junier
- Centre National de la Recherche Scientifique, Université Grenoble Alpes, TIMC-IMAG, F-38000 Grenoble, France
| | - Olivier Rivoire
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, PSL Research University, F-75005 Paris, France
| | - Kimberly A Reynolds
- The Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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20
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Phaneuf PV, Yurkovich JT, Heckmann D, Wu M, Sandberg TE, King ZA, Tan J, Palsson BO, Feist AM. Causal mutations from adaptive laboratory evolution are outlined by multiple scales of genome annotations and condition-specificity. BMC Genomics 2020; 21:514. [PMID: 32711472 PMCID: PMC7382830 DOI: 10.1186/s12864-020-06920-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 07/17/2020] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND Adaptive Laboratory Evolution (ALE) has emerged as an experimental approach to discover mutations that confer phenotypic functions of interest. However, the task of finding and understanding all beneficial mutations of an ALE experiment remains an open challenge for the field. To provide for better results than traditional methods of ALE mutation analysis, this work applied enrichment methods to mutations described by a multiscale annotation framework and a consolidated set of ALE experiment conditions. A total of 25,321 unique genome annotations from various sources were leveraged to describe multiple scales of mutated features in a set of 35 Escherichia coli based ALE experiments. These experiments totalled 208 independent evolutions and 2641 mutations. Additionally, mutated features were statistically associated across a total of 43 unique experimental conditions to aid in deconvoluting mutation selection pressures. RESULTS Identifying potentially beneficial, or key, mutations was enhanced by seeking coding and non-coding genome features significantly enriched by mutations across multiple ALE replicates and scales of genome annotations. The median proportion of ALE experiment key mutations increased from 62%, with only small coding and non-coding features, to 71% with larger aggregate features. Understanding key mutations was enhanced by considering the functions of broader annotation types and the significantly associated conditions for key mutated features. The approaches developed here were used to find and characterize novel key mutations in two ALE experiments: one previously unpublished with Escherichia coli grown on glycerol as a carbon source and one previously published with Escherichia coli tolerized to high concentrations of L-serine. CONCLUSIONS The emergent adaptive strategies represented by sets of ALE mutations became more clear upon observing the aggregation of mutated features across small to large scale genome annotations. The clarification of mutation selection pressures among the many experimental conditions also helped bring these strategies to light. This work demonstrates how multiscale genome annotation frameworks and data-driven methods can help better characterize ALE mutations, and thus help elucidate the genotype-to-phenotype relationship of the studied organism.
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Affiliation(s)
- Patrick V Phaneuf
- Bioinformatics and Systems Biology Program, University of California, San Diego, La Jolla, CA, 92093, USA
| | | | - David Heckmann
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Muyao Wu
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Troy E Sandberg
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Zachary A King
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Justin Tan
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Bernhard O Palsson
- Bioinformatics and Systems Biology Program, University of California, San Diego, La Jolla, CA, 92093, USA.,Department of Bioengineering, University of California, San Diego, La Jolla, CA, 92093, USA.,Department of Pediatrics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.,Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Building 220, Kemitorvet, 2800, Kgs. Lyngby, Denmark
| | - Adam M Feist
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, 92093, USA. .,Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Building 220, Kemitorvet, 2800, Kgs. Lyngby, Denmark.
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21
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Kramer L, Le X, Rodriguez M, Wilson MA, Guo J, Niu W. Engineering Carboxylic Acid Reductase (CAR) through a Whole-Cell Growth-Coupled NADPH Recycling Strategy. ACS Synth Biol 2020; 9:1632-1637. [PMID: 32589835 DOI: 10.1021/acssynbio.0c00290] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Rapid evolution of enzyme activities is often hindered by the lack of efficient and affordable methods to identify beneficial mutants. We report the development of a new growth-coupled selection method for evolving NADPH-consuming enzymes based on the recycling of this redox cofactor. The method relies on a genetically modified Escherichia coli strain, which overaccumulates NADPH. This method was applied to the engineering of a carboxylic acid reductase (CAR) for improved catalytic activities on 2-methoxybenzoate and adipate. Mutant enzymes with up to 17-fold improvement in catalytic efficiency were identified from single-site saturated mutagenesis libraries. Obtained mutants were successfully applied to whole-cell conversions of adipate into 1,6-hexanediol, a C6 monomer commonly used in polymer industry.
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Affiliation(s)
- Levi Kramer
- Department of Chemical & Biomolecular Engineering, University of Nebraska—Lincoln, Lincoln, Nebraska 68588, United States
| | - Xuan Le
- Department of Chemical & Biomolecular Engineering, University of Nebraska—Lincoln, Lincoln, Nebraska 68588, United States
| | - Marisa Rodriguez
- Department of Chemical & Biomolecular Engineering, University of Nebraska—Lincoln, Lincoln, Nebraska 68588, United States
| | - Mark A. Wilson
- Department of Biochemistry, University of Nebraska—Lincoln, Lincoln, Nebraska 68588, United States
| | - Jiantao Guo
- Department of Chemistry, University of Nebraska—Lincoln, Lincoln, Nebraska 68588, United States
| | - Wei Niu
- Department of Chemical & Biomolecular Engineering, University of Nebraska—Lincoln, Lincoln, Nebraska 68588, United States
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22
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Nguyen AD, Nam G, Kim D, Lee EY. Metabolic role of pyrophosphate-linked phosphofructokinase pfk for C1 assimilation in Methylotuvimicrobium alcaliphilum 20Z. Microb Cell Fact 2020; 19:131. [PMID: 32546161 PMCID: PMC7298851 DOI: 10.1186/s12934-020-01382-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 05/30/2020] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Methanotrophs is a promising biocatalyst in biotechnological applications with their ability to utilize single carbon (C1) feedstock to produce high-value compounds. Understanding the behavior of biological networks of methanotrophic bacteria in different parameters is vital to systems biology and metabolic engineering. Interestingly, methanotrophic bacteria possess the pyrophosphate-dependent 6-phosphofructokinase (PPi-PFK) instead of the ATP-dependent 6-phosphofructokinase, indicating their potentials to serve as promising model for investigation the role of inorganic pyrophosphate (PPi) and PPi-dependent glycolysis in bacteria. Gene knockout experiments along with global-omics approaches can be used for studying gene functions as well as unraveling regulatory networks that rely on the gene product. RESULTS In this study, we performed gene knockout and RNA-seq experiments in Methylotuvimicrobium alcaliphilum 20Z to investigate the functional roles of PPi-PFK in C1 metabolism when cells were grown on methane and methanol, highlighting its metabolic importance in C1 assimilation in M. alcaliphilum 20Z. We further conducted adaptive laboratory evolution (ALE) to investigate regulatory architecture in pfk knockout strain. Whole-genome resequencing and RNA-seq approaches were performed to characterize the genetic and metabolic responses of adaptation to pfk knockout. A number of mutations, as well as gene expression profiles, were identified in pfk ALE strain to overcome insufficient C1 assimilation pathway which limits the growth in the unevolved strain. CONCLUSIONS This study first revealed the regulatory roles of PPi-PFK on C1 metabolism and then provided novel insights into mechanism of adaptation to the loss of this major metabolic enzyme as well as an improved basis for future strain design in type I methanotrophs.
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Affiliation(s)
- Anh Duc Nguyen
- Department of Chemical Engineering, Kyung Hee University, Yongin-si, Gyeonggi-do, 17104, South Korea
| | - Gayoung Nam
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, South Korea
| | - Donghyuk Kim
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, South Korea.
| | - Eun Yeol Lee
- Department of Chemical Engineering, Kyung Hee University, Yongin-si, Gyeonggi-do, 17104, South Korea.
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23
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Phaneuf PV, Gosting D, Palsson BO, Feist AM. ALEdb 1.0: a database of mutations from adaptive laboratory evolution experimentation. Nucleic Acids Res 2020; 47:D1164-D1171. [PMID: 30357390 PMCID: PMC6323966 DOI: 10.1093/nar/gky983] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 10/08/2018] [Indexed: 11/27/2022] Open
Abstract
Adaptive Laboratory Evolution (ALE) has emerged as an experimental approach to discover causal mutations that confer desired phenotypic functions. ALE not only represents a controllable experimental approach to systematically discover genotype-phenotype relationships, but also allows for the revelation of the series of genetic alterations required to acquire the new phenotype. Numerous ALE studies have been published, providing a strong impetus for developing databases to warehouse experimental evolution information and make it retrievable for large-scale analysis. Here, the first step towards establishing this resource is presented: ALEdb (http://aledb.org). This initial release contains over 11 000 mutations that have been discovered from eleven ALE publications. ALEdb (i) is a web-based platform that comprehensively reports on ALE acquired mutations and their conditions, (ii) reports key mutations using previously established trends, (iii) enables a search-driven workflow to enhance user mutation functional analysis through mutation cross-reference, (iv) allows exporting of mutation query results for custom analysis, (v) includes a bibliome describing the databased experiment publications and (vi) contains experimental evolution mutations from multiple model organisms. Thus, ALEdb is an informative platform which will become increasingly revealing as the number of reported ALE experiments and identified mutations continue to expand.
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Affiliation(s)
- Patrick V Phaneuf
- Bioinformatics and Systems Biology Program, University of California, San Diego, La Jolla, CA 92093, USA
| | - Dennis Gosting
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Bernhard O Palsson
- Bioinformatics and Systems Biology Program, University of California, San Diego, La Jolla, CA 92093, USA.,Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA.,Department of Pediatrics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.,Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Building 220, Kemitorvet, 2800 Kgs. Lyngby, Denmark
| | - Adam M Feist
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA.,Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Building 220, Kemitorvet, 2800 Kgs. Lyngby, Denmark
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24
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LaBar T, Phoebe Hsieh YY, Fumasoni M, Murray AW. Evolutionary Repair Experiments as a Window to the Molecular Diversity of Life. Curr Biol 2020; 30:R565-R574. [PMID: 32428498 PMCID: PMC7295036 DOI: 10.1016/j.cub.2020.03.046] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Comparative genomics reveals an unexpected diversity in the molecular mechanisms underlying conserved cellular functions, such as DNA replication and cytokinesis. However, the genetic bases and evolutionary processes underlying this 'molecular diversity' remain to be explained. Here, we review a tool to generate alternative mechanisms for conserved cellular functions and test hypotheses concerning the generation of molecular diversity - evolutionary repair experiments, in which laboratory microbial populations adapt in response to a genetic perturbation. We summarize the insights gained from evolutionary repair experiments, the spectrum and dynamics of compensatory mutations, and the alternative molecular mechanisms used to repair perturbed cellular functions. We relate these experiments to the modifications of conserved functions that have occurred outside the laboratory. We end by proposing strategies to improve evolutionary repair experiments as a tool to explore the molecular diversity of life.
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Affiliation(s)
- Thomas LaBar
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
| | - Yu-Ying Phoebe Hsieh
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Marco Fumasoni
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
| | - Andrew W Murray
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
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25
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Ferreira S, Pereira R, Wahl SA, Rocha I. Metabolic engineering strategies for butanol production in Escherichia coli. Biotechnol Bioeng 2020; 117:2571-2587. [PMID: 32374413 DOI: 10.1002/bit.27377] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 04/03/2020] [Accepted: 05/04/2020] [Indexed: 11/06/2022]
Abstract
The global market of butanol is increasing due to its growing applications as solvent, flavoring agent, and chemical precursor of several other compounds. Recently, the superior properties of n-butanol as a biofuel over ethanol have stimulated even more interest. (Bio)butanol is natively produced together with ethanol and acetone by Clostridium species through acetone-butanol-ethanol fermentation, at noncompetitive, low titers compared to petrochemical production. Different butanol production pathways have been expressed in Escherichia coli, a more accessible host compared to Clostridium species, to improve butanol titers and rates. The bioproduction of butanol is here reviewed from a historical and theoretical perspective. All tested rational metabolic engineering strategies in E. coli to increase butanol titers are reviewed: manipulation of central carbon metabolism, elimination of competing pathways, cofactor balancing, development of new pathways, expression of homologous enzymes, consumption of different substrates, and molecular biology strategies. The progress in the field of metabolic modeling and pathway generation algorithms and their potential application to butanol production are also summarized here. The main goals are to gather all the strategies, evaluate the respective progress obtained, identify, and exploit the outstanding challenges.
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Affiliation(s)
- Sofia Ferreira
- CEB-Centre of Biological Engineering, University of Minho, Campus de Gualtar, Braga, Portugal.,Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB-NOVA), Oeiras, Portugal
| | - Rui Pereira
- SilicoLife Lda, Braga, Portugal.,Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - S A Wahl
- Department of Biotechnology, Delft University of Technology, Delft, The Netherlands
| | - Isabel Rocha
- CEB-Centre of Biological Engineering, University of Minho, Campus de Gualtar, Braga, Portugal.,Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB-NOVA), Oeiras, Portugal
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26
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Attaran E, Berim A, Killiny N, Beyenal H, Gang DR, Omsland A. Controlled replication of 'Candidatus Liberibacter asiaticus' DNA in citrus leaf discs. Microb Biotechnol 2020; 13:747-759. [PMID: 31958876 PMCID: PMC7111093 DOI: 10.1111/1751-7915.13531] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 12/10/2019] [Accepted: 12/14/2019] [Indexed: 12/13/2022] Open
Abstract
'Candidatus Liberibacter asiaticus' is a fastidious bacterium and a putative agent of citrus greening disease (a.k.a., huanglongbing, HLB), a significant agricultural disease that affects citrus fruit quality and tree health. In citrus, 'Ca. L. asiaticus' is phloem limited. Lack of culture tools to study 'Ca. L. asiaticus' complicates analysis of this important organism. To improve understanding of 'Ca. L. asiaticus'-host interactions including parameters that affect 'Ca. L. asiaticus' replication, methods suitable for screening pathogen responses to physicochemical and nutritional variables are needed. We describe a leaf disc-based culture assay that allows highly selective measurement of changes in 'Ca. L. asiaticus' DNA within plant tissue incubated under specific physicochemical and nutritional conditions. qPCR analysis targeting the hypothetical gene CD16-00155 (strain A4) allowed selective quantification of 'Ca. L. asiaticus' DNA content within infected tissue. 'Ca. L. asiaticus' DNA replication was observed in response to glucose exclusively under microaerobic conditions, and the antibiotic amikacin further enhanced 'Ca. L. asiaticus' DNA replication. Metabolite profiling revealed a moderate impact of 'Ca. L. asiaticus' on the ability of leaf tissue to metabolize and respond to glucose.
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Affiliation(s)
- Elham Attaran
- Paul G. Allen School for Global Animal HealthWashington State UniversityPullmanWAUSA
| | - Anna Berim
- Institute of Biological ChemistryWashington State UniversityPullmanWAUSA
| | - Nabil Killiny
- Plant Pathology DepartmentCitrus Research and Education CenterUniversity of FloridaLake AlfredFLUSA
| | - Haluk Beyenal
- Gene and Linda Voiland School of Chemical Engineering and BioengineeringWashington State UniversityPullmanWAUSA
| | - David R. Gang
- Institute of Biological ChemistryWashington State UniversityPullmanWAUSA
| | - Anders Omsland
- Paul G. Allen School for Global Animal HealthWashington State UniversityPullmanWAUSA
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27
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Matsuoka Y, Kurata H. Computer-Aided Rational Design of Efficient NADPH Production System by Escherichia coli pgi Mutant Using a Mixture of Glucose and Xylose. Front Bioeng Biotechnol 2020; 8:277. [PMID: 32318559 PMCID: PMC7154054 DOI: 10.3389/fbioe.2020.00277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 03/16/2020] [Indexed: 12/02/2022] Open
Abstract
Lignocellulosic biomass can be hydrolyzed into two major sugars of glucose and xylose, and thus the strategy for the efficient consumption of both sugars is highly desirable. NADPH is the essential molecule for the production of industrially important value-added chemicals, and thus its availability is quite important. Escherichia coli mutant lacking the pgi gene encoding phosphoglucose isomerase (Pgi) has been preferentially used to overproduce the NADPH. However, there exists a disadvantage that the cell growth rate becomes low for the mutant grown on glucose. This limits the efficient NADPH production, and therefore, it is quite important to investigate how addition of different carbon source such as xylose (other than glucose) effectively improves the NADPH production. In this study, we have developed a kinetic model to propose an efficient NADPH production system using E. coli pgi-knockout mutant with a mixture of glucose and xylose. The proposed system adds xylose to glucose medium to recover the suppressed growth of the pgi mutant, and determines the xylose content to maximize the NADPH productivity. Finally, we have designed a mevalonate (MVA) production system by implementing ArcA overexpression into the pgi-knockout mutant using a mixture of glucose and xylose. In addition to NADPH overproduction, the accumulation of acetyl-CoA (AcCoA) is necessary for the efficient MVA production. In the present study, therefore, we considered to overexpress ArcA, where ArcA overexpression suppresses the TCA cycle, causing the overflow of AcCoA, a precursor of MVA. We predicted the xylose content that maximizes the MVA production. This approach demonstrates the possibility of a great progress in the computer-aided rational design of the microbial cell factories for useful metabolite production.
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Affiliation(s)
- Yu Matsuoka
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, Iizuka, Japan
| | - Hiroyuki Kurata
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, Iizuka, Japan.,Biomedical Informatics R&D Center, Kyushu Institute of Technology, Iizuka, Japan
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28
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Contextual Flexibility in Pseudomonas aeruginosa Central Carbon Metabolism during Growth in Single Carbon Sources. mBio 2020; 11:mBio.02684-19. [PMID: 32184246 PMCID: PMC7078475 DOI: 10.1128/mbio.02684-19] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic human pathogen that is well known for causing infections in the airways of people with cystic fibrosis. Although it is clear that P. aeruginosa is metabolically well adapted to life in the CF lung, little is currently known about how the organism metabolizes the nutrients available in the airways. In this work, we used a combination of gene expression and isotope tracer (“fluxomic”) analyses to find out exactly where the input carbon goes during growth on two CF-relevant carbon sources, acetate and glycerol (derived from the breakdown of lung surfactant). We found that carbon is routed (“fluxed”) through very different pathways during growth on these substrates and that this is accompanied by an unexpected remodeling of the cell’s electron transfer pathways. Having access to this “blueprint” is important because the metabolism of P. aeruginosa is increasingly being recognized as a target for the development of much-needed antimicrobial agents. Pseudomonas aeruginosa is an opportunistic human pathogen, particularly noted for causing infections in the lungs of people with cystic fibrosis (CF). Previous studies have shown that the gene expression profile of P. aeruginosa appears to converge toward a common metabolic program as the organism adapts to the CF airway environment. However, we still have only a limited understanding of how these transcriptional changes impact metabolic flux at the systems level. To address this, we analyzed the transcriptome, proteome, and fluxome of P. aeruginosa grown on glycerol or acetate. These carbon sources were chosen because they are the primary breakdown products of an airway surfactant, phosphatidylcholine, which is known to be a major carbon source for P. aeruginosa in CF airways. We show that the fluxes of carbon throughout central metabolism are radically different among carbon sources. For example, the newly recognized “EDEMP cycle” (which incorporates elements of the Entner-Doudoroff [ED] pathway, the Embden-Meyerhof-Parnas [EMP] pathway, and the pentose phosphate [PP] pathway) plays an important role in supplying NADPH during growth on glycerol. In contrast, the EDEMP cycle is attenuated during growth on acetate, and instead, NADPH is primarily supplied by the reaction catalyzed by isocitrate dehydrogenase(s). Perhaps more importantly, our proteomic and transcriptomic analyses revealed a global remodeling of gene expression during growth on the different carbon sources, with unanticipated impacts on aerobic denitrification, electron transport chain architecture, and the redox economy of the cell. Collectively, these data highlight the remarkable metabolic plasticity of P. aeruginosa; that plasticity allows the organism to seamlessly segue between different carbon sources, maximizing the energetic yield from each.
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29
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Schramm T, Lempp M, Beuter D, Sierra SG, Glatter T, Link H. High-throughput enrichment of temperature-sensitive argininosuccinate synthetase for two-stage citrulline production in E. coli. Metab Eng 2020; 60:14-24. [PMID: 32179161 PMCID: PMC7225747 DOI: 10.1016/j.ymben.2020.03.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 03/03/2020] [Accepted: 03/08/2020] [Indexed: 12/20/2022]
Abstract
Controlling metabolism of engineered microbes is important to modulate cell growth and production during a bioprocess. For example, external parameters such as light, chemical inducers, or temperature can act on metabolism of production strains by changing the abundance or activity of enzymes. Here, we created temperature-sensitive variants of an essential enzyme in arginine biosynthesis of Escherichia coli (argininosuccinate synthetase, ArgG) and used them to dynamically control citrulline overproduction and growth of E. coli. We show a method for high-throughput enrichment of temperature-sensitive ArgG variants with a fluorescent TIMER protein and flow cytometry. With 90 of the thus derived ArgG variants, we complemented an ArgG deletion strain showing that 90% of the strains exhibit temperature-sensitive growth and 69% of the strains are auxotrophic for arginine at 42 °C and prototrophic at 30 °C. The best temperature-sensitive ArgG variant enabled precise and tunable control of cell growth by temperature changes. Expressing this variant in a feedback-dysregulated E. coli strain allowed us to realize a two-stage bioprocess: a 33 °C growth-phase for biomass accumulation and a 39 °C stationary-phase for citrulline production. With this two-stage strategy, we produced 3 g/L citrulline during 45 h cultivation in a 1-L bioreactor. These results show that temperature-sensitive enzymes can be created en masse and that they may function as metabolic valves in engineered bacteria. Method to enrich temperature-sensitive enzymes en masse. Temperature-sensitive enzymes function as metabolic valve. Temperature controlled two-stage production of citrulline.
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Affiliation(s)
- Thorben Schramm
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 16, 35043, Marburg, Germany
| | - Martin Lempp
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 16, 35043, Marburg, Germany
| | - Dominik Beuter
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 16, 35043, Marburg, Germany
| | - Silvia González Sierra
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 16, 35043, Marburg, Germany
| | - Timo Glatter
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 16, 35043, Marburg, Germany
| | - Hannes Link
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 16, 35043, Marburg, Germany.
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30
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Bennett RK, Dillon M, Gerald Har JR, Agee A, von Hagel B, Rohlhill J, Antoniewicz MR, Papoutsakis ET. Engineering Escherichia coli for methanol-dependent growth on glucose for metabolite production. Metab Eng 2020; 60:45-55. [PMID: 32179162 DOI: 10.1016/j.ymben.2020.03.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Revised: 02/25/2020] [Accepted: 03/08/2020] [Indexed: 02/05/2023]
Abstract
Synthetic methylotrophy aims to engineer methane and methanol utilization pathways in platform hosts like Escherichia coli for industrial bioprocessing of natural gas and biogas. While recent attempts to engineer synthetic methanol auxotrophs have proved successful, these studies focused on scarce and expensive co-substrates. Here, we engineered E. coli for methanol-dependent growth on glucose, an abundant and inexpensive co-substrate, via deletion of glucose 6-phosphate isomerase (pgi), phosphogluconate dehydratase (edd), and ribose 5-phosphate isomerases (rpiAB). Since the parental strain did not exhibit methanol-dependent growth on glucose in minimal medium, we first achieved methanol-dependent growth via amino acid supplementation and used this medium to evolve the strain for methanol-dependent growth in glucose minimal medium. The evolved strain exhibited a maximum growth rate of 0.15 h-1 in glucose minimal medium with methanol, which is comparable to that of other synthetic methanol auxotrophs. Whole genome sequencing and 13C-metabolic flux analysis revealed the causative mutations in the evolved strain. A mutation in the phosphotransferase system enzyme I gene (ptsI) resulted in a reduced glucose uptake rate to maintain a one-to-one molar ratio of substrate utilization. Deletion of the e14 prophage DNA region resulted in two non-synonymous mutations in the isocitrate dehydrogenase (icd) gene, which reduced TCA cycle carbon flux to maintain the internal redox state. In high cell density glucose fed-batch fermentation, methanol-dependent acetone production resulted in 22% average carbon labeling of acetone from 13C-methanol, which far surpasses that of the previous best (2.4%) found with methylotrophic E. coli Δpgi. This study addresses the need to identify appropriate co-substrates for engineering synthetic methanol auxotrophs and provides a basis for the next steps toward industrial one-carbon bioprocessing.
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Affiliation(s)
- R Kyle Bennett
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, USA; The Delaware Biotechnology Institute, University of Delaware, Newark, DE, USA.
| | - Michael Dillon
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, USA; The Delaware Biotechnology Institute, University of Delaware, Newark, DE, USA.
| | - Jie Ren Gerald Har
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, USA.
| | - Alec Agee
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, USA; The Delaware Biotechnology Institute, University of Delaware, Newark, DE, USA.
| | - Bryan von Hagel
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, USA; The Delaware Biotechnology Institute, University of Delaware, Newark, DE, USA.
| | - Julia Rohlhill
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, USA; The Delaware Biotechnology Institute, University of Delaware, Newark, DE, USA.
| | - Maciek R Antoniewicz
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, USA.
| | - Eleftherios T Papoutsakis
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, USA; The Delaware Biotechnology Institute, University of Delaware, Newark, DE, USA.
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31
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To TL, Cuadros AM, Shah H, Hung WHW, Li Y, Kim SH, Rubin DHF, Boe RH, Rath S, Eaton JK, Piccioni F, Goodale A, Kalani Z, Doench JG, Root DE, Schreiber SL, Vafai SB, Mootha VK. A Compendium of Genetic Modifiers of Mitochondrial Dysfunction Reveals Intra-organelle Buffering. Cell 2019; 179:1222-1238.e17. [PMID: 31730859 PMCID: PMC7053407 DOI: 10.1016/j.cell.2019.10.032] [Citation(s) in RCA: 84] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 09/12/2019] [Accepted: 10/23/2019] [Indexed: 12/18/2022]
Abstract
Mitochondrial dysfunction is associated with a spectrum of human conditions, ranging from rare, inborn errors of metabolism to the aging process. To identify pathways that modify mitochondrial dysfunction, we performed genome-wide CRISPR screens in the presence of small-molecule mitochondrial inhibitors. We report a compendium of chemical-genetic interactions involving 191 distinct genetic modifiers, including 38 that are synthetic sick/lethal and 63 that are suppressors. Genes involved in glycolysis (PFKP), pentose phosphate pathway (G6PD), and defense against lipid peroxidation (GPX4) scored high as synthetic sick/lethal. A surprisingly large fraction of suppressors are pathway intrinsic and encode mitochondrial proteins. A striking example of such "intra-organelle" buffering is the alleviation of a chemical defect in complex V by simultaneous inhibition of complex I, which benefits cells by rebalancing redox cofactors, increasing reductive carboxylation, and promoting glycolysis. Perhaps paradoxically, certain forms of mitochondrial dysfunction may best be buffered with "second site" inhibitors to the organelle.
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Affiliation(s)
- Tsz-Leung To
- Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
| | | | - Hardik Shah
- Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Massachusetts General Hospital, Boston, MA 02114, USA, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Wendy H W Hung
- Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
| | - Yang Li
- Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Massachusetts General Hospital, Boston, MA 02114, USA, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Sharon H Kim
- Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Massachusetts General Hospital, Boston, MA 02114, USA, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Daniel H F Rubin
- Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Massachusetts General Hospital, Boston, MA 02114, USA, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Ryan H Boe
- Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
| | - Sneha Rath
- Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Massachusetts General Hospital, Boston, MA 02114, USA, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - John K Eaton
- Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
| | | | - Amy Goodale
- Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
| | - Zohra Kalani
- Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
| | - John G Doench
- Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
| | - David E Root
- Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
| | - Stuart L Schreiber
- Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Massachusetts General Hospital, Boston, MA 02114, USA, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Scott B Vafai
- Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
| | - Vamsi K Mootha
- Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Massachusetts General Hospital, Boston, MA 02114, USA, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA.
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32
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St. John PC, Strutz J, Broadbelt LJ, Tyo KEJ, Bomble YJ. Bayesian inference of metabolic kinetics from genome-scale multiomics data. PLoS Comput Biol 2019; 15:e1007424. [PMID: 31682600 PMCID: PMC6855570 DOI: 10.1371/journal.pcbi.1007424] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 11/14/2019] [Accepted: 09/19/2019] [Indexed: 12/13/2022] Open
Abstract
Modern biological tools generate a wealth of data on metabolite and protein concentrations that can be used to help inform new strain designs. However, learning from these data to predict how a cell will respond to genetic changes, a key need for engineering, remains challenging. A promising technique for leveraging omics measurements in metabolic modeling involves the construction of kinetic descriptions of the enzymatic reactions that occur within a cell. Parameterizing these models from biological data can be computationally difficult, since methods must also quantify the uncertainty in model parameters resulting from the observed data. While the field of Bayesian inference offers a wide range of methods for efficiently estimating distributions in parameter uncertainty, such techniques are poorly suited to traditional kinetic models due to their complex rate laws and resulting nonlinear dynamics. In this paper, we employ linear-logarithmic kinetics to simplify the calculation of steady-state flux distributions and enable efficient sampling and inference methods. We demonstrate that detailed information on the posterior distribution of parameters can be obtained efficiently at a variety of problem scales, including nearly genome-scale kinetic models trained on multiomics datasets. These results allow modern Bayesian machine learning tools to be leveraged in understanding biological data and in developing new, efficient strain designs.
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Affiliation(s)
- Peter C. St. John
- Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado, United States of America
| | - Jonathan Strutz
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois, United States of America
| | - Linda J. Broadbelt
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois, United States of America
| | - Keith E. J. Tyo
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois, United States of America
| | - Yannick J. Bomble
- Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado, United States of America
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33
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Jung HM, Im DK, Lim JH, Jung GY, Oh MK. Metabolic perturbations in mutants of glucose transporters and their applications in metabolite production in Escherichia coli. Microb Cell Fact 2019; 18:170. [PMID: 31601271 PMCID: PMC6786474 DOI: 10.1186/s12934-019-1224-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 09/29/2019] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Most microorganisms have evolved to maximize growth rate, with rapid consumption of carbon sources from the surroundings. However, fast growing phenotypes usually feature secretion of organic compounds. For example, E. coli mainly produced acetate in fast growing condition such as glucose rich and aerobic condition, which is troublesome for metabolic engineering because acetate causes acidification of surroundings, growth inhibition and decline of production yield. The overflow metabolism can be alleviated by reducing glucose uptake rate. RESULTS As glucose transporters or their subunits were knocked out in E. coli, the growth and glucose uptake rates decreased and biomass yield was improved. Alteration of intracellular metabolism caused by the mutations was investigated with transcriptome analysis and 13C metabolic flux analysis (13C MFA). Various transcriptional and metabolic perturbations were identified in the sugar transporter mutants. Transcription of genes related to glycolysis, chemotaxis, and flagella synthesis was downregulated, and that of gluconeogenesis, Krebs cycle, alternative transporters, quorum sensing, and stress induced proteins was upregulated in the sugar transporter mutants. The specific production yields of value-added compounds (enhanced green fluorescent protein, γ-aminobutyrate, lycopene) were improved significantly in the sugar transporter mutants. CONCLUSIONS The elimination of sugar transporter resulted in alteration of global gene expression and redirection of carbon flux distribution, which was purposed to increase energy yield and recycle carbon sources. When the pathways for several valuable compounds were introduced to mutant strains, specific yield of them were highly improved. These results showed that controlling the sugar uptake rate is a good strategy for ameliorating metabolite production.
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Affiliation(s)
- Hwi-Min Jung
- Department of Chemical and Biological Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841 South Korea
| | - Dae-Kyun Im
- Department of Chemical and Biological Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841 South Korea
| | - Jae Hyung Lim
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673 South Korea
| | - Gyoo Yeol Jung
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673 South Korea
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673 South Korea
| | - Min-Kyu Oh
- Department of Chemical and Biological Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841 South Korea
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Rodrigues JV, Shakhnovich EI. Adaptation to mutational inactivation of an essential gene converges to an accessible suboptimal fitness peak. eLife 2019; 8:50509. [PMID: 31573512 PMCID: PMC6828540 DOI: 10.7554/elife.50509] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 09/30/2019] [Indexed: 12/14/2022] Open
Abstract
The mechanisms of adaptation to inactivation of essential genes remain unknown. Here we inactivate E. coli dihydrofolate reductase (DHFR) by introducing D27G,N,F chromosomal mutations in a key catalytic residue with subsequent adaptation by an automated serial transfer protocol. The partial reversal G27- > C occurred in three evolutionary trajectories. Conversely, in one trajectory for D27G and in all trajectories for D27F,N strains adapted to grow at very low metabolic supplement (folAmix) concentrations but did not escape entirely from supplement auxotrophy. Major global shifts in metabolome and proteome occurred upon DHFR inactivation, which were partially reversed in adapted strains. Loss-of-function mutations in two genes, thyA and deoB, ensured adaptation to low folAmix by rerouting the 2-Deoxy-D-ribose-phosphate metabolism from glycolysis towards synthesis of dTMP. Multiple evolutionary pathways of adaptation converged to a suboptimal solution due to the high accessibility to loss-of-function mutations that block the path to the highest, yet least accessible, fitness peak. Predicting how viruses and bacteria evolve remains a challenge. The ability to anticipate when and how bacteria might develop drug resistance would make treating life-threatening diseases easier and could potentially help prevent drug resistance altogether. Studying bacterial evolution under different conditions and cataloguing all possible DNA mutations that allow these bacteria to survive are crucial steps in predicting the appearance of drug resistance. Studies have revealed that bacteria can adapt to sources of stress, such as antibiotics, in different ways – each involving mutations in distinct genes. However, not all the mutations provide the same benefits to the organism, and the factors that influence how bacteria will adapt are unclear. Now, Rodrigues and Shakhnovich have used a new approach to push the adaptation ability of the bacterium Escherichia coli to the limit. First, they genetically engineered different E. coli strains by introducing distinct mutations to an enzyme the bacterium needs to make DNA. These mutations make the resulting strains dependent on external molecules to synthesize new DNA. Next, the cells were grown in conditions where the supply of these DNA precursors was progressively decreased, forcing them to adapt. The obvious way for bacteria to adapt to these conditions would be to ‘revert’ the mutations that Rodrigues and Shakhnovich introduced in the first place. By using this approach, Rodrigues and Shakhnovich were able to test how often the obvious evolutionary solution happens compared with presumably less-preferred alternative routes. In rare cases, a specific mutation did restore the activity of the enzyme that enabled DNA synthesis. However, in most cases the bacteria found a different evolutionary solution whereby they all adapt to the decrease in external DNA precursors in the same way, but not by reverting the original mutation. Instead, further mutations disrupt the activity of two metabolic genes, allowing the cells to use the external DNA precursors more efficiently, and keep building DNA. These cells are therefore able to survive even when the levels of the external DNA components are very low, but they will die in the complete absence of these precursor molecules. This evolutionary solution leads to a non-optimal effect: mutations that restore the activity of the original enzyme, which are the best solution when the two metabolic genes are intact, are no longer as effective. This finding represents a clear example of interactions between genes determining evolutionary outcomes. Rodrigues and Shakhnovich showed that, since it is more likely for a random mutation to disrupt a gene than to revert a previous mutation, adaptations that are less-than-optimal but still work might predominate simply because they happen faster. Understanding why certain evolutionary adaptations prevail is an important step in predicting evolution and may lead to breakthroughs in many areas. For example, if scientists can identify mutations likely to make bacteria resistant to drugs, it may be possible to act proactively against the bacterial strains that carry those mutations. Eventually, if the factors that lead to specific adaptations are known, it may be possible to exploit this knowledge to create weaknesses in the bacteria’s own defences.
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Affiliation(s)
- João V Rodrigues
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
| | - Eugene I Shakhnovich
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
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35
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Long CP, Antoniewicz MR. Metabolic flux responses to deletion of 20 core enzymes reveal flexibility and limits of E. coli metabolism. Metab Eng 2019; 55:249-257. [DOI: 10.1016/j.ymben.2019.08.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 08/03/2019] [Accepted: 08/03/2019] [Indexed: 02/08/2023]
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36
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Long CP, Antoniewicz MR. High-resolution 13C metabolic flux analysis. Nat Protoc 2019; 14:2856-2877. [PMID: 31471597 DOI: 10.1038/s41596-019-0204-0] [Citation(s) in RCA: 113] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 06/03/2019] [Indexed: 02/07/2023]
Abstract
Precise quantification of metabolic pathway fluxes in biological systems is of major importance in guiding efforts in metabolic engineering, biotechnology, microbiology, human health, and cell culture. 13C metabolic flux analysis (13C-MFA) is the predominant technique used for determining intracellular fluxes. Here, we present a protocol for 13C-MFA that incorporates recent advances in parallel labeling experiments, isotopic labeling measurements, and statistical analysis, as well as best practices developed through decades of experience. Experimental design to ensure that fluxes are estimated with the highest precision is an integral part of the protocol. The protocol is based on growing microbes in two (or more) parallel cultures with 13C-labeled glucose tracers, followed by gas chromatography-mass spectrometry (GC-MS) measurements of isotopic labeling of protein-bound amino acids, glycogen-bound glucose, and RNA-bound ribose. Fluxes are then estimated using software for 13C-MFA, such as Metran, followed by comprehensive statistical analysis to determine the goodness of fit and calculate confidence intervals of fluxes. The presented protocol can be completed in 4 d and quantifies metabolic fluxes with a standard deviation of ≤2%, a substantial improvement over previous implementations. The presented protocol is exemplified using an Escherichia coli ΔtpiA case study with full supporting data, providing a hands-on opportunity to step through a complex troubleshooting scenario. Although applications to prokaryotic microbial systems are emphasized, this protocol can be easily adjusted for application to eukaryotic organisms.
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Affiliation(s)
- Christopher P Long
- Metabolic Engineering and Systems Biology Laboratory, Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, USA.,Ginkgo Bioworks, Boston, MA, USA
| | - Maciek R Antoniewicz
- Metabolic Engineering and Systems Biology Laboratory, Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, USA.
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Shimizu K, Matsuoka Y. Redox rebalance against genetic perturbations and modulation of central carbon metabolism by the oxidative stress regulation. Biotechnol Adv 2019; 37:107441. [PMID: 31472206 DOI: 10.1016/j.biotechadv.2019.107441] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 08/04/2019] [Accepted: 08/23/2019] [Indexed: 12/11/2022]
Abstract
The micro-aerophilic organisms and aerobes as well as yeast and higher organisms have evolved to gain energy through respiration (via oxidative phosphorylation), thereby enabling them to grow much faster than anaerobes. However, during respiration, reactive oxygen species (ROSs) are inherently (inevitably) generated, and threaten the cell's survival. Therefore, living organisms (or cells) must furnish the potent defense systems to keep such ROSs at harmless level, where the cofactor balance plays crucial roles. Namely, NADH is the source of energy generation (catabolism) in the respiratory chain reactions, through which ROSs are generated, while NADPH plays important roles not only for the cell synthesis (anabolism) but also for detoxifying ROSs. Therefore, the cell must rebalance the redox ratio by modulating the fluxes of the central carbon metabolism (CCM) by regulating the multi-level regulation machinery upon genetic perturbations and the change in the growth conditions. Here, we discuss about how aerobes accomplish such cofactor homeostasis against redox perturbations. In particular, we consider how single-gene mutants (including pgi, pfk, zwf, gnd and pyk mutants) modulate their metabolisms in relation to cofactor rebalance (and also by adaptive laboratory evolution). We also discuss about how the overproduction of NADPH (by the pathway gene mutation) can be utilized for the efficient production of useful value-added chemicals such as medicinal compounds, polyhydroxyalkanoates, and amino acids, all of which require NADPH in their synthetic pathways. We then discuss about the metabolic responses against oxidative stress, where αketoacids play important roles not only for the coordination between catabolism and anabolism, but also for detoxifying ROSs by non-enzymatic reactions, as well as for reducing the production of ROSs by repressing the activities of the TCA cycle and respiration (via carbon catabolite repression). Thus, we discuss about the mechanisms (basic strategies) that modulate the metabolism from respiration to respiro-fermentative metabolism causing overflow, based on the role of Pyk activity, affecting the NADPH production at the oxidative pentose phosphate (PP) pathway, and the roles of αketoacids for the change in the source of energy generation from the oxidative phosphorylation to the substrate level phosphorylation.
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Affiliation(s)
- Kazuyuki Shimizu
- Kyushu institute of Technology, Iizuka, Fukuoka 820-8502, Japan; Institute of Advanced Biosciences, Keio university, Tsuruoka, Yamagata 997-0017, Japan.
| | - Yu Matsuoka
- Kyushu institute of Technology, Iizuka, Fukuoka 820-8502, Japan.
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Antoniewicz MR. Synthetic methylotrophy: Strategies to assimilate methanol for growth and chemicals production. Curr Opin Biotechnol 2019; 59:165-174. [PMID: 31437746 DOI: 10.1016/j.copbio.2019.07.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Revised: 07/12/2019] [Accepted: 07/17/2019] [Indexed: 11/29/2022]
Abstract
Methanol is an attractive and broadly available substrate for large-scale bioproduction of fuels and chemicals. It contains more energy and electrons per carbon than carbohydrates and can be cheaply produced from natural gas. Synthetic methylotrophy refers to the development of non-native methylotrophs such as Escherichia coli and Corynebacterium glutamicum to utilize methanol as a carbon source. Here, we discuss recent advances in engineering these industrial hosts to assimilate methanol for growth and chemicals production through the introduction of the ribulose monophosphate (RuMP) cycle. In addition, we present novel strategies based on flux coupling and adaptive laboratory evolution to engineer new strains that can grow exclusively on methanol.
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Affiliation(s)
- Maciek R Antoniewicz
- Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark DE 19716, USA.
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Sandberg TE, Salazar MJ, Weng LL, Palsson BO, Feist AM. The emergence of adaptive laboratory evolution as an efficient tool for biological discovery and industrial biotechnology. Metab Eng 2019; 56:1-16. [PMID: 31401242 DOI: 10.1016/j.ymben.2019.08.004] [Citation(s) in RCA: 251] [Impact Index Per Article: 50.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 08/01/2019] [Accepted: 08/05/2019] [Indexed: 12/21/2022]
Abstract
Harnessing the process of natural selection to obtain and understand new microbial phenotypes has become increasingly possible due to advances in culturing techniques, DNA sequencing, bioinformatics, and genetic engineering. Accordingly, Adaptive Laboratory Evolution (ALE) experiments represent a powerful approach both to investigate the evolutionary forces influencing strain phenotypes, performance, and stability, and to acquire production strains that contain beneficial mutations. In this review, we summarize and categorize the applications of ALE to various aspects of microbial physiology pertinent to industrial bioproduction by collecting case studies that highlight the multitude of ways in which evolution can facilitate the strain construction process. Further, we discuss principles that inform experimental design, complementary approaches such as computational modeling that help maximize utility, and the future of ALE as an efficient strain design and build tool driven by growing adoption and improvements in automation.
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Affiliation(s)
- Troy E Sandberg
- Department of Bioengineering, University of California, San Diego, CA, 92093, USA
| | - Michael J Salazar
- Department of Bioengineering, University of California, San Diego, CA, 92093, USA
| | - Liam L Weng
- Department of Bioengineering, University of California, San Diego, CA, 92093, USA
| | - Bernhard O Palsson
- Department of Bioengineering, University of California, San Diego, CA, 92093, USA; Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800, Lyngby, Denmark
| | - Adam M Feist
- Department of Bioengineering, University of California, San Diego, CA, 92093, USA; Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800, Lyngby, Denmark.
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40
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Wang J, Zhang R, Zhang Y, Yang Y, Lin Y, Yan Y. Developing a pyruvate-driven metabolic scenario for growth-coupled microbial production. Metab Eng 2019; 55:191-200. [PMID: 31348998 DOI: 10.1016/j.ymben.2019.07.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 07/17/2019] [Accepted: 07/20/2019] [Indexed: 11/17/2022]
Abstract
Microbial-based chemical synthesis serves as a promising approach for sustainable production of industrially important products. However, limited production performance caused by metabolic burden or genetic variations poses one of the major challenges in achieving an economically viable biomanufacturing process. To address this issue, one superior strategy is to couple the product synthesis with cellular growth, which renders production obligatory for cell survival. Here we create a pyruvate-driven metabolic scenario in engineered Escherichia coli for growth-coupled bioproduction, with which we demonstrate its application in boosting production of anthranilate and its derivatives. Deletion of a minimal set of endogenous pyruvate-releasing pathways engenders anthranilate synthesis as the salvage route for pyruvate generation to support cell growth, concomitant with simultaneous anthranilate production. Further introduction of native and non-native downstream pathways affords production enhancement of two anthranilate-derived high-value products including L-tryptophan and cis, cis-muconic acid from different carbon sources. The work reported here presents a new growth-coupled strategy with demonstrated feasibility for promoting microbial production.
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Affiliation(s)
- Jian Wang
- School of Chemical, Materials and Biomedical Engineering, College of Engineering, The University of Georgia, Athens, GA, 30602, USA
| | - Ruihua Zhang
- School of Chemical, Materials and Biomedical Engineering, College of Engineering, The University of Georgia, Athens, GA, 30602, USA
| | - Yan Zhang
- School of Chemical, Materials and Biomedical Engineering, College of Engineering, The University of Georgia, Athens, GA, 30602, USA
| | - Yaping Yang
- School of Chemical, Materials and Biomedical Engineering, College of Engineering, The University of Georgia, Athens, GA, 30602, USA
| | - Yuheng Lin
- BiotecEra Inc., 220 Riverbend Rd., Athens, GA, 30602, USA
| | - Yajun Yan
- School of Chemical, Materials and Biomedical Engineering, College of Engineering, The University of Georgia, Athens, GA, 30602, USA.
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41
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Noda S, Mori Y, Oyama S, Kondo A, Araki M, Shirai T. Reconstruction of metabolic pathway for isobutanol production in Escherichia coli. Microb Cell Fact 2019; 18:124. [PMID: 31319852 PMCID: PMC6637570 DOI: 10.1186/s12934-019-1171-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Accepted: 07/02/2019] [Indexed: 01/10/2023] Open
Abstract
Background The microbial production of useful fuels and chemicals has been widely studied. In several cases, glucose is used as the raw material, and almost all microbes adopt the Embden–Meyerhof (EM) pathway to degrade glucose into compounds of interest. Recently, the Entner–Doudoroff (ED) pathway has been gaining attention as an alternative strategy for microbial production. Results In the present study, we attempted to apply the ED pathway for isobutanol production in Escherichia coli because of the complete redox balance involved. First, we generated ED pathway-dependent isobutanol-producing E. coli. Thereafter, the inactivation of the genes concerning organic acids as the byproducts was performed to improve the carbon flux to isobutanol from glucose. Finally, the expression of the genes concerning the ED pathway was modified. Conclusions The optimized isobutanol-producing E. coli produced 15.0 g/L of isobutanol as the final titer, and the yield from glucose was 0.37 g/g (g-glucose/g-isobutanol). Electronic supplementary material The online version of this article (10.1186/s12934-019-1171-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Shuhei Noda
- Center for Sustainable Resource Science, RIKEN, 1-7-22, Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan
| | - Yutaro Mori
- Center for Sustainable Resource Science, RIKEN, 1-7-22, Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan
| | - Sachiko Oyama
- Center for Sustainable Resource Science, RIKEN, 1-7-22, Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan
| | - Akihiko Kondo
- Center for Sustainable Resource Science, RIKEN, 1-7-22, Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan.,Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan
| | - Michihiro Araki
- Graduate School of Medicine, Kyoto University, 54 Kawahara-cho, Syogoin, Sakyo-ku, Kyoto, 606-8507, Japan
| | - Tomokazu Shirai
- Center for Sustainable Resource Science, RIKEN, 1-7-22, Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan.
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42
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Kamiura R, Toya Y, Matsuda F, Shimizu H. Theophylline-inducible riboswitch accurately regulates protein expression at low level in Escherichia coli. Biotechnol Lett 2019; 41:743-751. [PMID: 30953309 DOI: 10.1007/s10529-019-02672-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Accepted: 03/31/2019] [Indexed: 12/11/2022]
Abstract
OBJECTIVES Fine-tuning of enzyme expression at low levels is an important challenge for metabolic engineers. Here, theophylline-inducible riboswitch for translational regulation was evaluated. The background expression, translation rate, and time delay for its induction was reported. RESULTS To evaluate the effect of the amount of mRNA on its translation rate, transcription of the riboswitch RNA with red fluorescent protein (RFP) was controlled by the lac system with addition of isopropyl β-D-1-thiogalactopyranoside in Escherichia coli. Regardless of the amount of riboswitch mRNA, the translation of RFP was completely suppressed without theophylline during both growth and stationary phases. Furthermore, a strong positive correlation between theophylline concentration (0 to 1 mM) and specific RFP production rate was observed. The specific RFP production rate with the riboswitch was approximately 2.3% of that without the riboswitch. Furthermore, 60 min of time delay for RFP expression was observed after adding theophylline during the stationary phase. CONCLUSION Theophylline-inducible riboswitch precisely controls protein translation at low expression levels with significantly low background expression. It can emerge as a powerful tool for fine tuning of enzyme expression.
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Affiliation(s)
- Rikuto Kamiura
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Yoshihiro Toya
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka, 565-0871, Japan.
| | - Fumio Matsuda
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Hiroshi Shimizu
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka, 565-0871, Japan.
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Nadeem MS, Razeeth M, Choudhry HMZ, Anwar F, Zamzami MA, Murtaza BN, Al-Abbasi FAM, Khan MI, Shakoori AR. LC-MS/MS-based metabolic profiling of Escherichia coli under heterologous gene expression stress. J Cell Biochem 2019; 121:125-134. [PMID: 31232490 DOI: 10.1002/jcb.28962] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Accepted: 04/24/2019] [Indexed: 11/09/2022]
Abstract
Escherichia coli is frequently exploited for genetic manipulations and heterologous gene expression studies. We have evaluated the metabolic profile of E. coli strain BL21 (DE3) RIL CodonPlus after genetic modifications and subjecting to the production of recombinant protein. Three genetically variable E. coli cell types were studied, normal cells (susceptible to antibiotics) cultured in simple LB medium, cells harboring ampicillin-resistant plasmid pET21a (+), grown under antibiotic stress, and cells having recombinant plasmid pET21a (+) ligated with bacterial lactate dehydrogenase gene grown under ampicillin and standard isopropyl thiogalactoside (IPTG)-induced gene expression conditions. A total of 592 metabolites were identified through liquid chromatography-mass spectrometry/mass spectrometry analysis, feature and peak detection using XCMS and CAMERA followed by precursor identification by METLIN-based procedures. Overall, 107 metabolites were found differentially regulated among genetically modified cells. Quantitative analysis has shown a significant modulation in DHNA-CoA, p-aminobenzoic acid, and citrulline levels, indicating an alteration in vitamin K, folic acid biosynthesis, and urea cycle of E. coli cells during heterologous gene expression. Modulations in energy metabolites including NADH, AMP, ADP, ATP, carbohydrate, terpenoids, fatty acid metabolites, diadenosine tetraphosphate (Ap4A), and l-carnitine advocate major metabolic rearrangements. Our study provides a broader insight into the metabolic adaptations of bacterial cells during gene manipulation experiments that can be prolonged to improve the yield of heterologous gene products and concomitant production of valuable biomolecules.
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Affiliation(s)
- Muhammad S Nadeem
- Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Mohammed Razeeth
- Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Hani M Z Choudhry
- Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia.,Cancer Metabolism and Epigenetic Unit, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Firoz Anwar
- Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Mazin A Zamzami
- Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia.,Cancer Metabolism and Epigenetic Unit, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Bibi N Murtaza
- Department of Zoology, Kinnaird College for Women, Lahore, Pakistan
| | - Fahad A M Al-Abbasi
- Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Mohammad I Khan
- Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia.,Cancer Metabolism and Epigenetic Unit, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Abdul R Shakoori
- School of Biological Sciences, University of the Punjab, Lahore, Pakistan.,Department of Biochemistry, Faculty of Life Sciences, Lahore, Pakistan
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Fernández‐Cabezón L, Cros A, Nikel PI. Evolutionary Approaches for Engineering Industrially Relevant Phenotypes in Bacterial Cell Factories. Biotechnol J 2019; 14:e1800439. [DOI: 10.1002/biot.201800439] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Revised: 04/08/2019] [Indexed: 12/12/2022]
Affiliation(s)
- Lorena Fernández‐Cabezón
- The Novo Nordisk Foundation Center for BiosustainabilityTechnical University of Denmark 2800 Kongens Lyngby Denmark
| | - Antonin Cros
- The Novo Nordisk Foundation Center for BiosustainabilityTechnical University of Denmark 2800 Kongens Lyngby Denmark
| | - Pablo I. Nikel
- The Novo Nordisk Foundation Center for BiosustainabilityTechnical University of Denmark 2800 Kongens Lyngby Denmark
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Diaz CA, Bennett RK, Papoutsakis ET, Antoniewicz MR. Deletion of four genes in Escherichia coli enables preferential consumption of xylose and secretion of glucose. Metab Eng 2019; 52:168-177. [DOI: 10.1016/j.ymben.2018.12.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Revised: 11/28/2018] [Accepted: 12/06/2018] [Indexed: 12/13/2022]
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Thommes M, Wang T, Zhao Q, Paschalidis IC, Segrè D. Designing Metabolic Division of Labor in Microbial Communities. mSystems 2019; 4:e00263-18. [PMID: 30984871 PMCID: PMC6456671 DOI: 10.1128/msystems.00263-18] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 03/15/2019] [Indexed: 12/19/2022] Open
Abstract
Microbes face a trade-off between being metabolically independent and relying on neighboring organisms for the supply of some essential metabolites. This balance of conflicting strategies affects microbial community structure and dynamics, with important implications for microbiome research and synthetic ecology. A "gedanken" (thought) experiment to investigate this trade-off would involve monitoring the rise of mutual dependence as the number of metabolic reactions allowed in an organism is increasingly constrained. The expectation is that below a certain number of reactions, no individual organism would be able to grow in isolation and cross-feeding partnerships and division of labor would emerge. We implemented this idealized experiment using in silico genome-scale models. In particular, we used mixed-integer linear programming to identify trade-off solutions in communities of Escherichia coli strains. The strategies that we found revealed a large space of opportunities in nuanced and nonintuitive metabolic division of labor, including, for example, splitting the tricarboxylic acid (TCA) cycle into two separate halves. The systematic computation of possible solutions in division of labor for 1-, 2-, and 3-strain consortia resulted in a rich and complex landscape. This landscape displayed a nonlinear boundary, indicating that the loss of an intracellular reaction was not necessarily compensated for by a single imported metabolite. Different regions in this landscape were associated with specific solutions and patterns of exchanged metabolites. Our approach also predicts the existence of regions in this landscape where independent bacteria are viable but are outcompeted by cross-feeding pairs, providing a possible incentive for the rise of division of labor. IMPORTANCE Understanding how microbes assemble into communities is a fundamental open issue in biology, relevant to human health, metabolic engineering, and environmental sustainability. A possible mechanism for interactions of microbes is through cross-feeding, i.e., the exchange of small molecules. These metabolic exchanges may allow different microbes to specialize in distinct tasks and evolve division of labor. To systematically explore the space of possible strategies for division of labor, we applied advanced optimization algorithms to computational models of cellular metabolism. Specifically, we searched for communities able to survive under constraints (such as a limited number of reactions) that would not be sustainable by individual species. We found that predicted consortia partition metabolic pathways in ways that would be difficult to identify manually, possibly providing a competitive advantage over individual organisms. In addition to helping understand diversity in natural microbial communities, our approach could assist in the design of synthetic consortia.
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Affiliation(s)
- Meghan Thommes
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, USA
- Biological Design Center, Boston University, Boston, Massachusetts, USA
| | - Taiyao Wang
- Division of Systems Engineering, Boston University, Boston, Massachusetts, USA
| | - Qi Zhao
- Division of Systems Engineering, Boston University, Boston, Massachusetts, USA
| | - Ioannis C. Paschalidis
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, USA
- Department of Electrical and Computer Engineering, Boston University, Boston, Massachusetts, USA
- Division of Systems Engineering, Boston University, Boston, Massachusetts, USA
| | - Daniel Segrè
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, USA
- Biological Design Center, Boston University, Boston, Massachusetts, USA
- Department of Biology, Boston University, Boston, Massachusetts, USA
- Department of Physics, Boston University, Boston, Massachusetts, USA
- Bioinformatics Program, Boston University, Boston, Massachusetts, USA
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Dinh HV, King ZA, Palsson BO, Feist AM. Identification of growth-coupled production strains considering protein costs and kinetic variability. Metab Eng Commun 2018; 7:e00080. [PMID: 30370222 PMCID: PMC6199775 DOI: 10.1016/j.mec.2018.e00080] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 09/25/2018] [Accepted: 10/07/2018] [Indexed: 12/13/2022] Open
Abstract
Conversion of renewable biomass to useful molecules in microbial cell factories can be approached in a rational and systematic manner using constraint-based reconstruction and analysis. Filtering for high confidence in silico designs is critical because in vivo construction and testing of strains is expensive and time consuming. As such, a workflow was devised to analyze the robustness of growth-coupled production when considering the biosynthetic costs of the proteome and variability in enzyme kinetic parameters using a genome-scale model of metabolism and gene expression (ME-model). A collection of 2632 unfiltered knockout designs in Escherichia coli was evaluated by the workflow. A ME-model was used in the workflow to test the designs' growth-coupled production in addition to a less complex genome-scale metabolic model (M-model). The workflow identified 634 M-model growth-coupled designs which met the filtering criteria and 42 robust designs, which met growth-coupled production criteria using both M and ME-models. Knockouts were found to follow a pattern of controlling intermediate metabolite consumption such as pyruvate consumption and high flux subsystems such as glycolysis. Kinetic parameter sampling using the ME-model revealed how enzyme efficiency and pathway tradeoffs can affect growth-coupled production phenotypes.
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Affiliation(s)
- Hoang V. Dinh
- Department of Bioengineering, University of California, San Diego, 9500 Gilman Drive #0412, La Jolla, CA 92093-0412, USA
| | - Zachary A. King
- Department of Bioengineering, University of California, San Diego, 9500 Gilman Drive #0412, La Jolla, CA 92093-0412, USA
| | - Bernhard O. Palsson
- Department of Bioengineering, University of California, San Diego, 9500 Gilman Drive #0412, La Jolla, CA 92093-0412, USA
- Department of Pediatrics, University of California, San Diego, 9500 Gilman Drive #0412, La Jolla, CA 92093-0412, USA
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Building 220, DK-2800 Kongens, Lyngby, Denmark
| | - Adam M. Feist
- Department of Bioengineering, University of California, San Diego, 9500 Gilman Drive #0412, La Jolla, CA 92093-0412, USA
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Building 220, DK-2800 Kongens, Lyngby, Denmark
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How adaptive evolution reshapes metabolism to improve fitness: recent advances and future outlook. Curr Opin Chem Eng 2018; 22:209-215. [PMID: 30613467 DOI: 10.1016/j.coche.2018.11.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Adaptive laboratory evolution (ALE) has emerged as a powerful tool in basic microbial research and strain development. In the context of metabolic science and engineering, it has been applied to study gene knockout responses, expand substrate ranges, improve tolerance to process conditions, and to improve productivity via designed growth coupling. In recent years, advancements in ALE methods and systems biology measurement technologies, particularly genome sequencing and 13C metabolic flux analysis (13C-MFA), have enabled detailed study of the mechanisms and dynamics of evolving metabolism. In this review, we discuss a range of studies that have applied flux analysis to adaptively evolved strains, as well as modeling frameworks developed to predict and interpret evolved fluxes. These efforts link mutations to fitness-enhanced phenotypes, identify bottlenecks and approaches to resolve them, and address systems concepts such as optimality.
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Escherichia coli as a host for metabolic engineering. Metab Eng 2018; 50:16-46. [DOI: 10.1016/j.ymben.2018.04.008] [Citation(s) in RCA: 181] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Revised: 04/11/2018] [Accepted: 04/12/2018] [Indexed: 12/21/2022]
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50
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Increasing carbon source uptake rates to improve chemical productivity in metabolic engineering. Curr Opin Biotechnol 2018; 53:254-263. [DOI: 10.1016/j.copbio.2018.06.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 05/22/2018] [Accepted: 06/13/2018] [Indexed: 11/24/2022]
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