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Yin L, Zhou Y, Ding N, Fang Y. Recent Advances in Metabolic Engineering for the Biosynthesis of Phosphoenol Pyruvate-Oxaloacetate-Pyruvate-Derived Amino Acids. Molecules 2024; 29:2893. [PMID: 38930958 PMCID: PMC11206799 DOI: 10.3390/molecules29122893] [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: 04/27/2024] [Revised: 06/06/2024] [Accepted: 06/11/2024] [Indexed: 06/28/2024] Open
Abstract
The phosphoenol pyruvate-oxaloacetate-pyruvate-derived amino acids (POP-AAs) comprise native intermediates in cellular metabolism, within which the phosphoenol pyruvate-oxaloacetate-pyruvate (POP) node is the switch point among the major metabolic pathways existing in most living organisms. POP-AAs have widespread applications in the nutrition, food, and pharmaceutical industries. These amino acids have been predominantly produced in Escherichia coli and Corynebacterium glutamicum through microbial fermentation. With the rapid increase in market requirements, along with the global food shortage situation, the industrial production capacity of these two bacteria has encountered two bottlenecks: low product conversion efficiency and high cost of raw materials. Aiming to push forward the update and upgrade of engineered strains with higher yield and productivity, this paper presents a comprehensive summarization of the fundamental strategy of metabolic engineering techniques around phosphoenol pyruvate-oxaloacetate-pyruvate node for POP-AA production, including L-tryptophan, L-tyrosine, L-phenylalanine, L-valine, L-lysine, L-threonine, and L-isoleucine. Novel heterologous routes and regulation methods regarding the carbon flux redistribution in the POP node and the formation of amino acids should be taken into consideration to improve POP-AA production to approach maximum theoretical values. Furthermore, an outlook for future strategies of low-cost feedstock and energy utilization for developing amino acid overproducers is proposed.
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Affiliation(s)
- Lianghong Yin
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou 311300, China; (L.Y.); (Y.Z.)
- Zhejiang Provincial Key Laboratory of Resources Protection and Innovation of Traditional Chinese Medicine, Zhejiang A&F University, Hangzhou 311300, China
| | - Yanan Zhou
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou 311300, China; (L.Y.); (Y.Z.)
- Zhejiang Provincial Key Laboratory of Resources Protection and Innovation of Traditional Chinese Medicine, Zhejiang A&F University, Hangzhou 311300, China
| | - Nana Ding
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou 311300, China; (L.Y.); (Y.Z.)
- Zhejiang Provincial Key Laboratory of Resources Protection and Innovation of Traditional Chinese Medicine, Zhejiang A&F University, Hangzhou 311300, China
| | - Yu Fang
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou 311300, China; (L.Y.); (Y.Z.)
- Zhejiang Provincial Key Laboratory of Resources Protection and Innovation of Traditional Chinese Medicine, Zhejiang A&F University, Hangzhou 311300, China
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Wang Y, Bai Y, Zeng Q, Jiang Z, Liu Y, Wang X, Liu X, Liu C, Min W. Recent advances in the metabolic engineering and physiological opportunities for microbial synthesis of L-aspartic acid family amino acids: A review. Int J Biol Macromol 2023; 253:126916. [PMID: 37716660 DOI: 10.1016/j.ijbiomac.2023.126916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 09/10/2023] [Accepted: 09/13/2023] [Indexed: 09/18/2023]
Abstract
L-aspartic acid, L-threonine, L-isoleucine, l-lysine, and L-methionine constitute the l-aspartate amino acids (AFAAs). Except for L-aspartic acid, these are essential amino acids that cannot be synthesized by humans or animals themselves. E. coli and C. glutamicum are the main model organisms for AFAA production. It is necessary to reconstitute microbial cell factories and the physiological state of industrial fermentation cells for in-depth research into strains with higher AFAA production levels and optimal growth states. Considering that the anabolic pathways of the AFAAs and engineering modifications have rarely been reviewed in the latest progress, this work reviews the central metabolic pathways of two strains and strategies for the metabolic engineering of AFAA synthetic pathways. The challenges posed by microbial physiology in AFAA production and possible strategies to address them, as well as future research directions for constructing strains with high AFAA production levels, are discussed in this review article.
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Affiliation(s)
- Yusheng Wang
- College of Food Science and Engineering, Jilin Agricultural University, Changchun 130118, PR China
| | - Yunlong Bai
- College of Food Science and Engineering, Jilin Agricultural University, Changchun 130118, PR China
| | - Qi Zeng
- College of Food Science and Engineering, Jilin Agricultural University, Changchun 130118, PR China
| | - Zeyuan Jiang
- College of Food Science and Engineering, Jilin Agricultural University, Changchun 130118, PR China
| | - Yuzhe Liu
- College of Food Science and Engineering, Jilin Agricultural University, Changchun 130118, PR China
| | - Xiyan Wang
- College of Food Science and Engineering, Jilin Agricultural University, Changchun 130118, PR China
| | - Xiaoting Liu
- College of Food Science and Engineering, Jilin Agricultural University, Changchun 130118, PR China
| | - Chunlei Liu
- College of Food Science and Engineering, Jilin Agricultural University, Changchun 130118, PR China.
| | - Weihong Min
- College of Food Science and Engineering, Jilin Agricultural University, Changchun 130118, PR China.
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3
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Göttl VL, Schmitt I, Braun K, Peters-Wendisch P, Wendisch VF, Henke NA. CRISPRi-Library-Guided Target Identification for Engineering Carotenoid Production by Corynebacterium glutamicum. Microorganisms 2021; 9:670. [PMID: 33805131 PMCID: PMC8064071 DOI: 10.3390/microorganisms9040670] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 03/19/2021] [Accepted: 03/21/2021] [Indexed: 01/24/2023] Open
Abstract
Corynebacterium glutamicum is a prominent production host for various value-added compounds in white biotechnology. Gene repression by dCas9/clustered regularly interspaced short palindromic repeats (CRISPR) interference (CRISPRi) allows for the identification of target genes for metabolic engineering. In this study, a CRISPRi-based library for the repression of 74 genes of C. glutamicum was constructed. The chosen genes included genes encoding enzymes of glycolysis, the pentose phosphate pathway, and the tricarboxylic acid cycle, regulatory genes, as well as genes of the methylerythritol phosphate and carotenoid biosynthesis pathways. As expected, CRISPRi-mediated repression of the carotenogenesis repressor gene crtR resulted in increased pigmentation and cellular content of the native carotenoid pigment decaprenoxanthin. CRISPRi screening identified 14 genes that affected decaprenoxanthin biosynthesis when repressed. Carotenoid biosynthesis was significantly decreased upon CRISPRi-mediated repression of 11 of these genes, while repression of 3 genes was beneficial for decaprenoxanthin production. Largely, but not in all cases, deletion of selected genes identified in the CRISPRi screen confirmed the pigmentation phenotypes obtained by CRISPRi. Notably, deletion of pgi as well as of gapA improved decaprenoxanthin levels 43-fold and 9-fold, respectively. The scope of the designed library to identify metabolic engineering targets, transfer of gene repression to stable gene deletion, and limitations of the approach were discussed.
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Affiliation(s)
| | | | | | | | - Volker F. Wendisch
- Genetics of Prokaryotes, Faculty of Biology & CeBiTec, Bielefeld University, 33615 Bielefeld, Germany; (V.L.G.); (I.S.); (K.B.); (P.P.-W.); (N.A.H.)
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A Genome-Scale Metabolic Model of Anabaena 33047 to Guide Genetic Modifications to Overproduce Nylon Monomers. Metabolites 2021; 11:metabo11030168. [PMID: 33804103 PMCID: PMC7999273 DOI: 10.3390/metabo11030168] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 03/04/2021] [Accepted: 03/11/2021] [Indexed: 11/17/2022] Open
Abstract
Nitrogen fixing-cyanobacteria can significantly improve the economic feasibility of cyanobacterial production processes by eliminating the requirement for reduced nitrogen. Anabaena sp. ATCC 33047 is a marine, heterocyst forming, nitrogen fixing cyanobacteria with a very short doubling time of 3.8 h. We developed a comprehensive genome-scale metabolic (GSM) model, iAnC892, for this organism using annotations and content obtained from multiple databases. iAnC892 describes both the vegetative and heterocyst cell types found in the filaments of Anabaena sp. ATCC 33047. iAnC892 includes 953 unique reactions and accounts for the annotation of 892 genes. Comparison of iAnC892 reaction content with the GSM of Anabaena sp. PCC 7120 revealed that there are 109 reactions including uptake hydrogenase, pyruvate decarboxylase, and pyruvate-formate lyase unique to iAnC892. iAnC892 enabled the analysis of energy production pathways in the heterocyst by allowing the cell specific deactivation of light dependent electron transport chain and glucose-6-phosphate metabolizing pathways. The analysis revealed the importance of light dependent electron transport in generating ATP and NADPH at the required ratio for optimal N2 fixation. When used alongside the strain design algorithm, OptForce, iAnC892 recapitulated several of the experimentally successful genetic intervention strategies that over produced valerolactam and caprolactam precursors.
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Lu L, Mao Y, Kou M, Cui Z, Jin B, Chang Z, Wang Z, Ma H, Chen T. Engineering central pathways for industrial-level (3R)-acetoin biosynthesis in Corynebacterium glutamicum. Microb Cell Fact 2020; 19:102. [PMID: 32398078 PMCID: PMC7216327 DOI: 10.1186/s12934-020-01363-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Accepted: 05/05/2020] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Acetoin, especially the optically pure (3S)- or (3R)-enantiomer, is a high-value-added bio-based platform chemical and important potential pharmaceutical intermediate. Over the past decades, intense efforts have been devoted to the production of acetoin through green biotechniques. However, efficient and economical methods for the production of optically pure acetoin enantiomers are rarely reported. Previously, we systematically engineered the GRAS microorganism Corynebacterium glutamicum to efficiently produce (3R)-acetoin from glucose. Nevertheless, its yield and average productivity were still unsatisfactory for industrial bioprocesses. RESULTS In this study, cellular carbon fluxes in the acetoin producer CGR6 were further redirected toward acetoin synthesis using several metabolic engineering strategies, including blocking anaplerotic pathways, attenuating key genes of the TCA cycle and integrating additional copies of the alsSD operon into the genome. Among them, the combination of attenuation of citrate synthase and inactivation of phosphoenolpyruvate carboxylase showed a significant synergistic effect on acetoin production. Finally, the optimal engineered strain CGS11 produced a titer of 102.45 g/L acetoin with a yield of 0.419 g/g glucose at a rate of 1.86 g/L/h in a 5 L fermenter. The optical purity of the resulting (3R)-acetoin surpassed 95%. CONCLUSION To the best of our knowledge, this is the highest titer of highly enantiomerically enriched (3R)-acetoin, together with a competitive product yield and productivity, achieved in a simple, green processes without expensive additives or substrates. This process therefore opens the possibility to achieve easy, efficient, economical and environmentally-friendly production of (3R)-acetoin via microbial fermentation in the near future.
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Affiliation(s)
- Lingxue Lu
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering of Ministry of Education, SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China
| | - Yufeng Mao
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
| | - Mengyun Kou
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering of Ministry of Education, SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China
| | - Zhenzhen Cui
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering of Ministry of Education, SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China
| | - Biao Jin
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering of Ministry of Education, SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China
| | - Zhishuai Chang
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering of Ministry of Education, SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China
| | - Zhiwen Wang
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering of Ministry of Education, SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China
| | - Hongwu Ma
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
| | - Tao Chen
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering of Ministry of Education, SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.
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Increasing L-homoserine production in Escherichia coli by engineering the central metabolic pathways. J Biotechnol 2020; 314-315:1-7. [DOI: 10.1016/j.jbiotec.2020.03.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 03/07/2020] [Accepted: 03/25/2020] [Indexed: 01/05/2023]
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7
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Xu JZ, Wu ZH, Gao SJ, Zhang W. Rational modification of tricarboxylic acid cycle for improving L-lysine production in Corynebacterium glutamicum. Microb Cell Fact 2018; 17:105. [PMID: 29981572 PMCID: PMC6035423 DOI: 10.1186/s12934-018-0958-z] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 07/02/2018] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Oxaloacetate (OAA) and L-glutamate are essential precursors for the biosynthesis of L-lysine. Reasonable control of all potentially rate-limiting steps, including the precursors supply rate, is of vital importance to maximize the efficiency of L-lysine fermentation process. RESULTS In this paper, we have rationally engineered the tricarboxylic acid (TCA) cycle that increased the carbon yield (from 36.18 to 59.65%), final titer (from 14.47 ± 0.41 to 23.86 ± 2.16 g L-1) and productivity (from 0.30 to 0.50 g L-1 h-1) of L-lysine by Corynebacterium glutamicum in shake-flask fermentation because of improving the OAA and L-glutamate availability. To do this, the phosphoenolpyruvate-pyruvate-oxaloacetate (PEP-pyruvate-OAA) node's genes ppc and pyc were inserted in the genes pck and odx loci, the P1 promoter of the TCA cycle's gene gltA was deleted, and the nature promoter of glutamate dehydrogenase-coding gene gdh was replaced by Ptac-M promoter that resulted in the final engineered strain C. glutamicum JL-69Ptac-M gdh. Furthermore, the suitable addition of biotin accelerates the L-lysine production in strain JL-69Ptac-M gdh because it elastically adjusts the carbon flux for cell growth and precursor supply. The final strain JL-69Ptac-M gdh could produce 181.5 ± 11.74 g L-1 of L-lysine with a productivity of 3.78 g L-1 h-1 and maximal specific production rate (qLys, max.) of 0.73 ± 0.16 g g-1 h-1 in fed-batch culture during adding 2.4 mg L-1 biotin with four times. CONCLUSIONS Our results reveal that sufficient biomass, OAA and L-glutamate are equally important in the development of L-lysine high-yielding strain, and it is the first time to verify that fed-batch biotin plays a positive role in improving L-lysine production.
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Affiliation(s)
- Jian-Zhong Xu
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800# Lihu Road, Wuxi, 214122 People’s Republic of China
| | - Ze-Hua Wu
- Research and Development Department, Shandong Shouguang Juneng Golden Corn Co., Ltd., 1199# Xinxing Street, Shouguang, 262700 People’s Republic of China
| | - Shi-Jun Gao
- Research and Development Department, Shandong Shouguang Juneng Golden Corn Co., Ltd., 1199# Xinxing Street, Shouguang, 262700 People’s Republic of China
| | - Weiguo Zhang
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800# Lihu Road, Wuxi, 214122 People’s Republic of China
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Abstract
One of the greatest sources of metabolic and enzymatic diversity are microorganisms. In recent years, emerging recombinant DNA and genomic techniques have facilitated the development of new efficient expression systems, modification of biosynthetic pathways leading to new metabolites by metabolic engineering, and enhancement of catalytic properties of enzymes by directed evolution. Complete sequencing of industrially important microbial genomes is taking place very rapidly, and there are already hundreds of genomes sequenced. Functional genomics and proteomics are major tools used in the search for new molecules and development of higher-producing strains.
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Affiliation(s)
| | - Sergio Sánchez
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México, CDMX, México
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Li Y, Wei H, Wang T, Xu Q, Zhang C, Fan X, Ma Q, Chen N, Xie X. Current status on metabolic engineering for the production of l-aspartate family amino acids and derivatives. BIORESOURCE TECHNOLOGY 2017; 245:1588-1602. [PMID: 28579173 DOI: 10.1016/j.biortech.2017.05.145] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 05/20/2017] [Accepted: 05/22/2017] [Indexed: 06/07/2023]
Abstract
The l-aspartate amino acids (AFAAs) are constituted of l-aspartate, l-lysine, l-methionine, l-threonine and l-isoleucine. Except for l-aspartate, AFAAs are essential amino acids that cannot be synthesized by humans and most farm animals, and thus possess wide applications in food, animal feed, pharmaceutical and cosmetics industries. To date, a number of amino acids, including AFAAs have been industrially produced by microbial fermentation. However, the overall metabolic and regulatory mechanisms of the synthesis of AFAAs and the recent progress on strain construction have rarely been reviewed. Aiming to promote the establishment of strains of Corynebacterium glutamicum and Escherichia coli, the two industrial amino acids producing bacteria, that are capable of producing high titers of AFAAs and derivatives, this paper systematically summarizes the current progress on metabolic engineering manipulations in both central metabolic pathways and AFAA synthesis pathways based on the category of the five-word strain breeding strategies: enter, flow, moderate, block and exit.
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Affiliation(s)
- Yanjun Li
- National and Local United Engineering Lab of Metabolic Control Fermentation Technology, Tianjin University of Science and Technology, Tianjin 300457, China; Key Laboratory of Microbial Engineering of China Light Industry, Tianjin University of Science and Technology, Tianjin 300457, China; College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, China
| | - Hongbo Wei
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, China
| | - Ting Wang
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, China
| | - Qingyang Xu
- National and Local United Engineering Lab of Metabolic Control Fermentation Technology, Tianjin University of Science and Technology, Tianjin 300457, China; Key Laboratory of Microbial Engineering of China Light Industry, Tianjin University of Science and Technology, Tianjin 300457, China; College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, China
| | - Chenglin Zhang
- National and Local United Engineering Lab of Metabolic Control Fermentation Technology, Tianjin University of Science and Technology, Tianjin 300457, China; Key Laboratory of Microbial Engineering of China Light Industry, Tianjin University of Science and Technology, Tianjin 300457, China; College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, China
| | - Xiaoguang Fan
- National and Local United Engineering Lab of Metabolic Control Fermentation Technology, Tianjin University of Science and Technology, Tianjin 300457, China; Key Laboratory of Microbial Engineering of China Light Industry, Tianjin University of Science and Technology, Tianjin 300457, China; College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, China
| | - Qian Ma
- National and Local United Engineering Lab of Metabolic Control Fermentation Technology, Tianjin University of Science and Technology, Tianjin 300457, China; Key Laboratory of Microbial Engineering of China Light Industry, Tianjin University of Science and Technology, Tianjin 300457, China; College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, China
| | - Ning Chen
- National and Local United Engineering Lab of Metabolic Control Fermentation Technology, Tianjin University of Science and Technology, Tianjin 300457, China; Key Laboratory of Microbial Engineering of China Light Industry, Tianjin University of Science and Technology, Tianjin 300457, China; College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, China
| | - Xixian Xie
- National and Local United Engineering Lab of Metabolic Control Fermentation Technology, Tianjin University of Science and Technology, Tianjin 300457, China; Key Laboratory of Microbial Engineering of China Light Industry, Tianjin University of Science and Technology, Tianjin 300457, China; College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, China.
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Boosting Anaplerotic Reactions by Pyruvate Kinase Gene Deletion and Phosphoenolpyruvate Carboxylase Desensitization for Glutamic Acid and Lysine Production in Corynebacterium glutamicum. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2016; 159:181-198. [DOI: 10.1007/10_2016_31] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/13/2023]
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11
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Pyruvate kinase deletion as an effective phenotype to enhance lysine production in Corynebacterium glutamicum ATCC13032: Redirecting the carbon flow to a precursor metabolite. J Biosci Bioeng 2016; 122:160-7. [DOI: 10.1016/j.jbiosc.2015.12.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2015] [Revised: 12/11/2015] [Accepted: 12/28/2015] [Indexed: 01/30/2023]
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12
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Cleto S, Jensen JVK, Wendisch VF, Lu TK. Corynebacterium glutamicum Metabolic Engineering with CRISPR Interference (CRISPRi). ACS Synth Biol 2016; 5:375-85. [PMID: 26829286 PMCID: PMC4877668 DOI: 10.1021/acssynbio.5b00216] [Citation(s) in RCA: 179] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
![]()
Corynebacterium
glutamicum is an important organism for the
industrial production
of amino acids. Metabolic pathways in this organism are usually engineered
by conventional methods such as homologous recombination, which depends
on rare double-crossover events. To facilitate the mapping of gene
expression levels to metabolic outputs, we applied CRISPR interference
(CRISPRi) technology using deactivated Cas9 (dCas9) to repress genes
in C. glutamicum. We then determined the effects
of target repression on amino acid titers. Single-guide RNAs directing
dCas9 to specific targets reduced expression of pgi and pck up to 98%, and of pyk up
to 97%, resulting in titer enhancement ratios of l-lysine
and l-glutamate production comparable to levels achieved
by gene deletion. This approach for C. glutamicum metabolic engineering, which only requires 3 days, indicates that
CRISPRi can be used for quick and efficient metabolic pathway remodeling
without the need for gene deletions or mutations and subsequent selection.
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Affiliation(s)
- Sara Cleto
- Department of Electrical Engineering & Computer Science and Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
- MIT Synthetic Biology Center, 500 Technology Square, Cambridge, Massachusetts 02139, United States
| | - Jaide VK Jensen
- Department of Electrical Engineering & Computer Science and Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
- MIT Synthetic Biology Center, 500 Technology Square, Cambridge, Massachusetts 02139, United States
- Genetics
of Prokaryotes, Faculty of Biology and CeBiTec, Bielefeld University, 33615 Bielefeld, Germany
| | - Volker F. Wendisch
- Genetics
of Prokaryotes, Faculty of Biology and CeBiTec, Bielefeld University, 33615 Bielefeld, Germany
| | - Timothy K. Lu
- Department of Electrical Engineering & Computer Science and Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
- MIT Synthetic Biology Center, 500 Technology Square, Cambridge, Massachusetts 02139, United States
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13
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Lysine Fermentation: History and Genome Breeding. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2016; 159:73-102. [DOI: 10.1007/10_2016_27] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Single-Domain Peptidyl-Prolyl cis/trans Isomerase FkpA from Corynebacterium glutamicum Improves the Biomass Yield at Increased Growth Temperatures. Appl Environ Microbiol 2015; 81:7839-50. [PMID: 26341203 DOI: 10.1128/aem.02113-15] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 08/30/2015] [Indexed: 12/15/2022] Open
Abstract
Peptidyl-prolyl cis/trans isomerases (PPIases) catalyze the rate-limiting protein folding step at peptidyl bonds preceding proline residues and were found to be involved in several biological processes, including gene expression, signal transduction, and protein secretion. Representative enzymes were found in almost all sequenced genomes, including Corynebacterium glutamicum, a facultative anaerobic Gram-positive and industrial workhorse for the production of amino acids. In C. glutamicum, a predicted single-domain FK-506 (tacrolimus) binding protein (FKBP)-type PPIase (FkpA) is encoded directly downstream of gltA, which encodes citrate synthase (CS). This gene cluster is also present in other Actinobacteria. Here we carried out in vitro and in vivo experiments to study the function and influence of predicted FkpA in C. glutamicum. In vitro, FkpA indeed shows typical PPIase activity with artificial substrates and is inhibited by FK-506. Furthermore, FkpA delays the aggregation of CS, which is also inhibited by FK-506. Surprisingly, FkpA has a positive effect on the activity and temperature range of CS in vitro. Deletion of fkpA causes a 50% reduced biomass yield compared to that of the wild type when grown at 37°C, whereas there is only a 10% reduced biomass yield at the optimal growth temperature of 30°C accompanied by accumulation of 7 mM l-glutamate and 22 mM 2-oxoglutarate. Thus, FkpA may be exploited for improved product formation in biotechnical processes. Comparative transcriptome analysis revealed 69 genes which exhibit ≥2-fold mRNA level changes in C. glutamicum ΔfkpA, giving insight into the transcriptional response upon mild heat stress when FkpA is absent.
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15
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Transcriptional Regulation by the Short-Chain Fatty Acyl Coenzyme A Regulator (ScfR) PccR Controls Propionyl Coenzyme A Assimilation by Rhodobacter sphaeroides. J Bacteriol 2015; 197:3048-56. [PMID: 26170412 DOI: 10.1128/jb.00402-15] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 07/07/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Propionyl coenzyme A (propionyl-CoA) assimilation by Rhodobacter sphaeroides proceeds via the methylmalonyl-CoA pathway. The activity of the key enzyme of the pathway, propionyl-CoA carboxylase (PCC), was upregulated 20-fold during growth with propionate compared to growth with succinate. Because propionyl-CoA is an intermediate in acetyl-CoA assimilation via the ethylmalonyl-CoA pathway, acetate growth also requires the methylmalonyl-CoA pathway. PCC activities were upregulated 8-fold in extracts of acetate-grown cells compared to extracts of succinate-grown cells. The upregulation of PCC activities during growth with propionate or acetate corresponded to increased expression of the pccB gene, which encodes a subunit of PCC. PccR (RSP_2186) was identified to be a transcriptional regulator required for the upregulation of pccB transcript levels and, consequently, PCC activity: growth substrate-dependent regulation was lost when pccR was inactivated by an in-frame deletion. In the pccR mutant, lacZ expression from a 215-bp plasmid-borne pccB upstream fragment including 27 bp of the pccB coding region was also deregulated. A loss of regulation as a result of mutations in the conserved motifs TTTGCAAA-X4-TTTGCAAA in the presence of PccR allowed the prediction of a possible operator site. PccR, together with homologs from other organisms, formed a distinct clade within the family of short-chain fatty acyl coenzyme A regulators (ScfRs) defined here. Some members from other clades within the ScfR family have previously been shown to be involved in regulating acetyl-CoA assimilation by the glyoxylate bypass (RamB) or propionyl-CoA assimilation by the methylcitrate cycle (MccR). IMPORTANCE Short-chain acyl-CoAs are intermediates in essential biosynthetic and degradative pathways. The regulation of their accumulation is crucial for appropriate cellular function. This work identifies a regulator (PccR) that prevents the accumulation of propionyl-CoA by controlling expression of the gene encoding propionyl-CoA carboxylase, which is responsible for propionyl-CoA consumption by Rhodobacter sphaeroides. Many other Proteobacteria and Actinomycetales contain one or several PccR homologs that group into distinct clades on the basis of the pathway of acyl-CoA metabolism that they control. Furthermore, an upstream analysis of genes encoding PccR homologs allows the prediction of conserved binding motifs for these regulators. Overall, this study evaluates a single regulator of propionyl-CoA assimilation while expanding the knowledge of the regulation of short-chain acyl-CoAs in many bacterial species.
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Methylotrophy in the thermophilic Bacillus methanolicus, basic insights and application for commodity production from methanol. Appl Microbiol Biotechnol 2014; 99:535-51. [PMID: 25431011 DOI: 10.1007/s00253-014-6224-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 11/07/2014] [Accepted: 11/08/2014] [Indexed: 01/28/2023]
Abstract
Using methanol as an alternative non-food feedstock for biotechnological production offers several advantages in line with a methanol-based bioeconomy. The Gram-positive, facultative methylotrophic and thermophilic bacterium Bacillus methanolicus is one of the few described microbial candidates with a potential for the conversion of methanol to value-added products. Its capabilities of producing and secreting the commercially important amino acids L-glutamate and L-lysine to high concentrations at 50 °C have been demonstrated and make B. methanolicus a promising target to develop cell factories for industrial-scale production processes. B. methanolicus uses the ribulose monophosphate cycle for methanol assimilation and represents the first example of plasmid-dependent methylotrophy. Recent genome sequencing of two physiologically different wild-type B. methanolicus strains, MGA3 and PB1, accompanied with transcriptome and proteome analyses has generated fundamental new insight into the metabolism of the species. In addition, multiple key enzymes representing methylotrophic and biosynthetic pathways have been biochemically characterized. All this, together with establishment of improved tools for gene expression, has opened opportunities for systems-level metabolic engineering of B. methanolicus. Here, we summarize the current status of its metabolism and biochemistry, available genetic tools, and its potential use in respect to overproduction of amino acids.
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Kohlstedt M, Sappa PK, Meyer H, Maaß S, Zaprasis A, Hoffmann T, Becker J, Steil L, Hecker M, van Dijl JM, Lalk M, Mäder U, Stülke J, Bremer E, Völker U, Wittmann C. Adaptation ofBacillus subtiliscarbon core metabolism to simultaneous nutrient limitation and osmotic challenge: a multi-omics perspective. Environ Microbiol 2014; 16:1898-917. [DOI: 10.1111/1462-2920.12438] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 02/18/2014] [Indexed: 01/24/2023]
Affiliation(s)
- Michael Kohlstedt
- Institute of Systems Biotechnology; Saarland University; Campus A1 5 66123 Saarbrücken Germany
- Institute of Biochemical Engineering; Braunschweig University of Technology; Braunschweig Germany
| | - Praveen K. Sappa
- Interfaculty Institute of Genetics and Functional Genomics; Department Functional Genomics; University Medicine Greifswald; Germany
| | - Hanna Meyer
- Institutes of Biochemistry; Ernst-Moritz-Arndt-University Greifswald; Greifswald Germany
| | - Sandra Maaß
- Microbiology; Ernst-Moritz-Arndt-University Greifswald; Greifswald Germany
| | - Adrienne Zaprasis
- Department of Biology; Laboratory of Microbiology; Philipps-University Marburg; Marburg Germany
| | - Tamara Hoffmann
- Department of Biology; Laboratory of Microbiology; Philipps-University Marburg; Marburg Germany
| | - Judith Becker
- Institute of Systems Biotechnology; Saarland University; Campus A1 5 66123 Saarbrücken Germany
- Institute of Biochemical Engineering; Braunschweig University of Technology; Braunschweig Germany
| | - Leif Steil
- Interfaculty Institute of Genetics and Functional Genomics; Department Functional Genomics; University Medicine Greifswald; Germany
| | - Michael Hecker
- Microbiology; Ernst-Moritz-Arndt-University Greifswald; Greifswald Germany
| | - Jan Maarten van Dijl
- Department of Medical Microbiology; University of Groningen; University Medical Center Groningen; Groningen The Netherlands
| | - Michael Lalk
- Institutes of Biochemistry; Ernst-Moritz-Arndt-University Greifswald; Greifswald Germany
| | - Ulrike Mäder
- Interfaculty Institute of Genetics and Functional Genomics; Department Functional Genomics; University Medicine Greifswald; Germany
| | - Jörg Stülke
- Department for General Microbiology; Georg-August-University Göttingen; Göttingen Germany
| | - Erhard Bremer
- Department of Biology; Laboratory of Microbiology; Philipps-University Marburg; Marburg Germany
| | - Uwe Völker
- Interfaculty Institute of Genetics and Functional Genomics; Department Functional Genomics; University Medicine Greifswald; Germany
| | - Christoph Wittmann
- Institute of Systems Biotechnology; Saarland University; Campus A1 5 66123 Saarbrücken Germany
- Institute of Biochemical Engineering; Braunschweig University of Technology; Braunschweig Germany
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Metabolic engineering of Corynebacterium glutamicum for 2-ketoisocaproate production. Appl Microbiol Biotechnol 2013; 98:297-311. [DOI: 10.1007/s00253-013-5310-2] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Revised: 09/30/2013] [Accepted: 10/01/2013] [Indexed: 10/26/2022]
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van Ooyen J, Noack S, Bott M, Eggeling L. Proline addition increases the efficiency of l-lysine production byCorynebacterium glutamicum. Eng Life Sci 2013. [DOI: 10.1002/elsc.201200187] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Affiliation(s)
- Jan van Ooyen
- Institute of Bio- and Geosciences; Biotechnology, Forschungszentrum Jülich GmbH; Jülich Germany
| | - Stephan Noack
- Institute of Bio- and Geosciences; Biotechnology, Forschungszentrum Jülich GmbH; Jülich Germany
| | - Michael Bott
- Institute of Bio- and Geosciences; Biotechnology, Forschungszentrum Jülich GmbH; Jülich Germany
| | - Lothar Eggeling
- Institute of Bio- and Geosciences; Biotechnology, Forschungszentrum Jülich GmbH; Jülich Germany
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Bott M, Eikmanns BJ. TCA Cycle and Glyoxylate Shunt of Corynebacterium glutamicum. CORYNEBACTERIUM GLUTAMICUM 2013. [DOI: 10.1007/978-3-642-29857-8_10] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Abstract
Microorganisms are one of the greatest sources of metabolic and enzymatic diversity. In recent years, emerging recombinant DNA and genomic techniques have facilitated the development of new efficient expression systems, modification of biosynthetic pathways leading to new metabolites by metabolic engineering, and enhancement of catalytic properties of enzymes by directed evolution. Complete sequencing of industrially important microbial genomes is taking place very rapidly and there are already hundreds of genomes sequenced. Functional genomics and proteomics are major tools used in the search for new molecules and development of higher-producing strains.
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Plassmeier J, Persicke M, Pühler A, Sterthoff C, Rückert C, Kalinowski J. Molecular characterization of PrpR, the transcriptional activator of propionate catabolism in Corynebacterium glutamicum. J Biotechnol 2012; 159:1-11. [DOI: 10.1016/j.jbiotec.2011.09.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Revised: 08/25/2011] [Accepted: 09/06/2011] [Indexed: 10/17/2022]
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van Ooyen J, Noack S, Bott M, Reth A, Eggeling L. Improved L-lysine production with Corynebacterium glutamicum and systemic insight into citrate synthase flux and activity. Biotechnol Bioeng 2012; 109:2070-81. [DOI: 10.1002/bit.24486] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 02/15/2012] [Accepted: 02/22/2012] [Indexed: 01/25/2023]
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Baumgart M, Mustafi N, Krug A, Bott M. Deletion of the aconitase gene in Corynebacterium glutamicum causes strong selection pressure for secondary mutations inactivating citrate synthase. J Bacteriol 2011; 193:6864-73. [PMID: 21984793 PMCID: PMC3232852 DOI: 10.1128/jb.05465-11] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2011] [Accepted: 10/03/2011] [Indexed: 01/29/2023] Open
Abstract
The aconitase gene acn of Corynebacterium glutamicum is regulated by four transcriptional regulators, indicating that the synthesis of this enzyme is carefully controlled. To understand the causes for this elaborate regulation, the properties of the Δacn-1 deletion mutant were analyzed in detail. The mutant was glutamate auxotrophic in glucose minimal medium, showed a strong growth defect, and secreted large amounts of acetate. None of these phenotypes could be complemented by plasmid-encoded aconitase, suggesting the presence of a secondary mutation. In fact, a point mutation within the gltA gene encoding citrate synthase was identified that caused the instability of the protein and an almost complete lack of its enzymatic activity. Subsequently, 27 further, independent Δacn clones were isolated, and 15 of them were found to contain distinct mutations in gltA, causing the loss of citrate synthase activity. A similar result was observed for mutants lacking the isocitrate dehydrogenase gene icd. In this case, 8 of 24 Δicd clones contained additional mutations in gltA. Indirect evidence was obtained that elevated intracellular citrate concentrations could be the cause of this selection pressure. Accordingly, the careful control of aconitase synthesis might have evolved due to the necessity to avoid inhibitory cytoplasmic citrate levels on the one hand and to prevent the excessive synthesis of an oxygen-sensitive protein requiring both iron and sulfur on the other hand.
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Affiliation(s)
- Meike Baumgart
- Institut für Bio- und Geowissenschaften, IBG-1: Biotechnologie, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Nurije Mustafi
- Institut für Bio- und Geowissenschaften, IBG-1: Biotechnologie, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Andreas Krug
- Institut für Bio- und Geowissenschaften, IBG-1: Biotechnologie, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Michael Bott
- Institut für Bio- und Geowissenschaften, IBG-1: Biotechnologie, Forschungszentrum Jülich, D-52425 Jülich, Germany
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van Ooyen J, Emer D, Bussmann M, Bott M, Eikmanns BJ, Eggeling L. Citrate synthase in Corynebacterium glutamicum is encoded by two gltA transcripts which are controlled by RamA, RamB, and GlxR. J Biotechnol 2011; 154:140-8. [DOI: 10.1016/j.jbiotec.2010.07.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 01/18/2010] [Accepted: 07/01/2010] [Indexed: 11/15/2022]
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Baumgart M, Bott M. Biochemical characterisation of aconitase from Corynebacterium glutamicum. J Biotechnol 2011; 154:163-70. [DOI: 10.1016/j.jbiotec.2010.07.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Accepted: 07/01/2010] [Indexed: 10/19/2022]
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Schröder J, Tauch A. Transcriptional regulation of gene expression inCorynebacterium glutamicum: the role of global, master and local regulators in the modular and hierarchical gene regulatory network. FEMS Microbiol Rev 2010; 34:685-737. [DOI: 10.1111/j.1574-6976.2010.00228.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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Klaffl S, Eikmanns BJ. Genetic and functional analysis of the soluble oxaloacetate decarboxylase from Corynebacterium glutamicum. J Bacteriol 2010; 192:2604-12. [PMID: 20233922 PMCID: PMC2863558 DOI: 10.1128/jb.01678-09] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Accepted: 03/07/2010] [Indexed: 11/20/2022] Open
Abstract
Soluble, divalent cation-dependent oxaloacetate decarboxylases (ODx) catalyze the irreversible decarboxylation of oxaloacetate to pyruvate and CO(2). Although these enzymes have been characterized in different microorganisms, the genes that encode them have not been identified, and their functions have been only poorly analyzed so far. In this study, we purified a soluble ODx from wild-type C. glutamicum about 65-fold and used matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) analysis and peptide mass fingerprinting for identification of the corresponding odx gene. Inactivation and overexpression of odx led to an absence of ODx activity and to a 30-fold increase in ODx specific activity, respectively; these findings unequivocally confirmed that this gene encodes a soluble ODx. Transcriptional analysis of odx indicated that there is a leaderless transcript that is organized in an operon together with a putative S-adenosylmethionine-dependent methyltransferase gene. Biochemical analysis of ODx revealed that the molecular mass of the native enzyme is about 62 +/- 1 kDa and that the enzyme is composed of two approximately 29-kDa homodimeric subunits and has a K(m) for oxaloacetate of 1.4 mM and a V(max) of 201 micromol of oxaloacetate converted per min per mg of protein, resulting in a k(cat) of 104 s(-1). Introduction of plasmid-borne odx into a pyruvate kinase-deficient C. glutamicum strain restored growth of this mutant on acetate, indicating that a high level of ODx activity redirects the carbon flux from oxaloacetate to pyruvate in vivo. Consistently, overexpression of the odx gene in an L-lysine-producing strain of C. glutamicum led to accumulation of less L-lysine. However, inactivation of the odx gene did not improve L-lysine production under the conditions tested.
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Affiliation(s)
- Simon Klaffl
- Institute of Microbiology and Biotechnology, University of Ulm, D-89069 Ulm, Germany
| | - Bernhard J. Eikmanns
- Institute of Microbiology and Biotechnology, University of Ulm, D-89069 Ulm, Germany
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Carbohydrate metabolism in Corynebacterium glutamicum and applications for the metabolic engineering of l-lysine production strains. Appl Microbiol Biotechnol 2010; 86:1313-22. [DOI: 10.1007/s00253-010-2537-z] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 03/03/2010] [Accepted: 03/03/2010] [Indexed: 11/27/2022]
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Adrio JL, Demain AL. Recombinant organisms for production of industrial products. Bioeng Bugs 2009; 1:116-31. [PMID: 21326937 DOI: 10.4161/bbug.1.2.10484] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Revised: 10/30/2009] [Accepted: 11/02/2009] [Indexed: 11/19/2022] Open
Abstract
A revolution in industrial microbiology was sparked by the discoveries of ther double-stranded structure of DNA and the development of recombinant DNA technology. Traditional industrial microbiology was merged with molecular biology to yield improved recombinant processes for the industrial production of primary and secondary metabolites, protein biopharmaceuticals and industrial enzymes. Novel genetic techniques such as metabolic engineering, combinatorial biosynthesis and molecular breeding techniques and their modifications are contributing greatly to the development of improved industrial processes. In addition, functional genomics, proteomics and metabolomics are being exploited for the discovery of novel valuable small molecules for medicine as well as enzymes for catalysis. The sequencing of industrial microbal genomes is being carried out which bodes well for future process improvement and discovery of new industrial products.
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Affiliation(s)
- Jose-Luis Adrio
- NeuronBioPharma, S.A., Parque Tecnologico de Ciencias de la Salud, Edificio BIC, Armilla, Granada, Spain
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Acetohydroxyacid synthase, a novel target for improvement of L-lysine production by Corynebacterium glutamicum. Appl Environ Microbiol 2008; 75:419-27. [PMID: 19047397 DOI: 10.1128/aem.01844-08] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The influence of acetohydroxy acid synthase (AHAS) on L-lysine production by Corynebacterium glutamicum was investigated. An AHAS with a deleted C-terminal domain in the regulatory subunit IlvN was engineered by truncating the ilvN gene. Compared to the wild-type AHAS, the newly constructed enzyme showed altered kinetic properties, i.e., (i) an about twofold-lower K(m) for the substrate pyruvate and an about fourfold-lower V(max); (ii) a slightly increased K(m) for the substrate alpha-ketobutyrate with an about twofold-lower V(max); and (iii) insensitivity against the inhibitors L-valine, L-isoleucine, and L-leucine (10 mM each). Introduction of the modified AHAS into the L-lysine producers C. glutamicum DM1729 and DM1933 increased L-lysine formation by 43% (30 mM versus 21 mM) and 36% (51 mM versus 37 mM), respectively, suggesting that decreased AHAS activity is linked to increased L-lysine formation. Complete inactivation of the AHAS in C. glutamicum DM1729 and DM1933 by deletion of the ilvB gene, encoding the catalytic subunit of AHAS, led to L-valine, L-isoleucine, and L-leucine auxotrophy and to further-improved L-lysine production. In batch fermentations, C. glutamicum DM1729 Delta ilvB produced about 85% more L-lysine (70 mM versus 38 mM) and showed an 85%-higher substrate-specific product yield (0.180 versus 0.098 mol C/mol C) than C. glutamicum DM1729. Comparative transcriptome analysis of C. glutamicum DM1729 and C. glutamicum DM1729 Delta ilvB indicated transcriptional differences for about 50 genes, although not for those encoding enzymes involved in the L-lysine biosynthetic pathway.
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