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Rajpurohit H, Eiteman MA. Citrate synthase variants improve yield of acetyl-CoA derived 3-hydroxybutyrate in Escherichia coli. Microb Cell Fact 2024; 23:173. [PMID: 38867236 PMCID: PMC11167817 DOI: 10.1186/s12934-024-02444-8] [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: 02/11/2024] [Accepted: 05/29/2024] [Indexed: 06/14/2024] Open
Abstract
BACKGROUND The microbial chiral product (R)-3-hydroxybutyrate (3-HB) is a gateway to several industrial and medical compounds. Acetyl-CoA is the key precursor for 3-HB, and several native pathways compete with 3-HB production. The principal competing pathway in wild-type Escherichia coli for acetyl-CoA is mediated by citrate synthase (coded by gltA), which directs over 60% of the acetyl-CoA into the tricarboxylic acid cycle. Eliminating citrate synthase activity (deletion of gltA) prevents growth on glucose as the sole carbon source. In this study, an alternative approach is used to generate an increased yield of 3-HB: citrate synthase activity is reduced but not eliminated by targeted substitutions in the chromosomally expressed enzyme. RESULTS Five E. coli GltA variants were examined for 3-HB production via heterologous overexpression of a thiolase (phaA) and NADPH-dependent acetoacetyl-CoA reductase (phaB) from Cupriavidus necator. In shake flask studies, four variants showed nearly 5-fold greater 3-HB yield compared to the wild-type, although pyruvate accumulated. Overexpression of either native thioesterases TesB or YciA eliminated pyruvate formation, but diverted acetyl-CoA towards acetate formation. Overexpression of pantothenate kinase similarly decreased pyruvate formation but did not improve 3-HB yield. Controlled batch studies at the 1.25 L scale demonstrated that the GltA[A267T] variant produced the greatest 3-HB titer of 4.9 g/L with a yield of 0.17 g/g. In a phosphate-starved repeated batch process, E. coli ldhA poxB pta-ackA gltA::gltA[A267T] generated 15.9 g/L 3-HB (effective concentration of 21.3 g/L with dilution) with yield of 0.16 g/g from glucose as the sole carbon source. CONCLUSIONS This study demonstrates that GltA variants offer a means to affect the generation of acetyl-CoA derived products. This approach should benefit a wide range of acetyl-CoA derived biochemical products in E. coli and other microbes. Enhancing substrate affinity of the introduced pathway genes like thiolase towards acetyl-CoA will likely further increase the flux towards 3-HB while reducing pyruvate and acetate accumulation.
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Affiliation(s)
| | - Mark A Eiteman
- School of Chemical, Materials and Biomedical Engineering, Athens, GA, USA.
- Department of Microbiology, University of Georgia, Athens, GA, 30602, USA.
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2
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Sheng LL, Cai YM, Li Y, Huang SL, Sheng JZ. Advancements in heparosan production through metabolic engineering and improved fermentation. Carbohydr Polym 2024; 331:121881. [PMID: 38388039 DOI: 10.1016/j.carbpol.2024.121881] [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: 11/26/2023] [Revised: 01/25/2024] [Accepted: 01/26/2024] [Indexed: 02/24/2024]
Abstract
Heparin is one of the most widely used natural drugs, and has been the preferred anticoagulant and antithrombotic agent in the clinical setting for nearly a century. Heparin also shows increasing therapeutic potential for treating inflammation, cancer, and microbial and viral diseases, including COVID-19. With advancements in synthetic biology, heparin production through microbial engineering of heparosan offers a cost-effective and scalable alternative to traditional extraction from animal tissues. Heparosan serves as the starting carbon backbone for the chemoenzymatic synthesis of bioengineered heparin, possessing a chain length that is critically important for the production of heparin-based therapeutics with specific molecular weight (MW) distributions. Recent advancements in metabolic engineering of microbial cell factories have resulted in high-yield heparosan production. This review systematically analyzes the key modules involved in microbial heparosan biosynthesis and the latest metabolic engineering strategies for enhancing production, regulating MW, and optimizing the fermentation scale-up of heparosan. It also discusses future studies, remaining challenges, and prospects in the field.
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Affiliation(s)
- Li-Li Sheng
- Key Laboratory of Chemical Biology of Natural Products, Ministry of Education, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan 250012, China
| | - Yi-Min Cai
- Key Laboratory of Chemical Biology of Natural Products, Ministry of Education, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan 250012, China
| | - Yi Li
- Key Laboratory of Chemical Biology of Natural Products, Ministry of Education, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan 250012, China
| | - Si-Ling Huang
- Bloomage BioTechnology Corp., Ltd., Jinan 250010, China
| | - Ju-Zheng Sheng
- Key Laboratory of Chemical Biology of Natural Products, Ministry of Education, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan 250012, China; The State Key Laboratory of Microbial Technology, Shandong University, Qingdao 250100, China.
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3
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Lu C, Ramalho TP, Bisschops MMM, Wijffels RH, Martins Dos Santos VAP, Weusthuis RA. Crossing bacterial boundaries: The carbon catabolite repression system Crc-Hfq of Pseudomonas putida KT2440 as a tool to control translation in E. coli. N Biotechnol 2023; 77:20-29. [PMID: 37348756 DOI: 10.1016/j.nbt.2023.06.004] [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: 05/02/2023] [Revised: 06/05/2023] [Accepted: 06/19/2023] [Indexed: 06/24/2023]
Abstract
As a global regulatory mechanism, carbon catabolite repression allows bacteria and eukaryal microbes to preferentially utilize certain substrates from a mixture of carbon sources. The mechanism varies among different species. In Pseudomonas spp., it is mainly mediated by the Crc-Hfq complex which binds to the 5' region of the target mRNAs, thereby inhibiting their translation. This molecular mechanism enables P. putida to rapidly adjust and fine-tune gene expression in changing environments. Hfq is an RNA-binding protein that is ubiquitous and highly conserved in bacterial species. Considering the characteristics of Hfq, and the widespread use and rapid response of Crc-Hfq in P. putida, this complex has the potential to become a general toolbox for post-transcriptional multiplex regulation. In this study, we demonstrate for the first time that transplanting the pseudomonal catabolite repression protein, Crc, into E. coli causes multiplex gene repression. Under the control of Crc, the production of a diester and its precursors was significantly reduced. The effects of Crc introduction on cell growth in both minimal and rich media were evaluated. Two potential factors - off-target effects and Hfq-sequestration - could explain negative effects on cell growth. Simultaneous reduction of off-targeting and increased sequestration of Hfq by the introduction of the small RNA CrcZ, indicated that Hfq sequestration plays a more prominent role in the negative side-effects. This suggests that the negative growth effect can be mitigated by well-controlled expression of Hfq. This study reveals the feasibility of controlling gene expression using heterologous regulation systems.
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Affiliation(s)
- Chunzhe Lu
- Bioprocess Engineering, Wageningen University and Research, 6700AA Wageningen, The Netherlands.
| | - Tiago P Ramalho
- Bioprocess Engineering, Wageningen University and Research, 6700AA Wageningen, The Netherlands
| | - Markus M M Bisschops
- Bioprocess Engineering, Wageningen University and Research, 6700AA Wageningen, The Netherlands
| | - Rene H Wijffels
- Bioprocess Engineering, Wageningen University and Research, 6700AA Wageningen, The Netherlands; Faculty of Biosciences and Aquaculture, Nord University, N-8049 Bodø, Norway
| | - Vitor A P Martins Dos Santos
- Bioprocess Engineering, Wageningen University and Research, 6700AA Wageningen, The Netherlands; Lifeglimmer GmbH, Berlin, Germany
| | - Ruud A Weusthuis
- Bioprocess Engineering, Wageningen University and Research, 6700AA Wageningen, The Netherlands
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4
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Kim J, Lee TS. Enhancing isoprenol production by systematically tuning metabolic pathways using CRISPR interference in E. coli. Front Bioeng Biotechnol 2023; 11:1296132. [PMID: 38026852 PMCID: PMC10659101 DOI: 10.3389/fbioe.2023.1296132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 10/16/2023] [Indexed: 12/01/2023] Open
Abstract
Regulation of metabolic gene expression is crucial for maximizing bioproduction titers. Recent engineering tools including CRISPR/Cas9, CRISPR interference (CRISPRi), and CRISPR activation (CRISPRa) have enabled effective knock-out, knock-down, and overexpression of endogenous pathway genes, respectively, for advanced strain engineering. CRISPRi in particular has emerged as a powerful tool for gene repression through the use of a deactivated Cas9 (dCas9) protein and target guide RNA (gRNA). By constructing gRNA arrays, CRISPRi has the capacity for multiplexed gene downregulation across multiple orthogonal pathways for enhanced bioproduction titers. In this study, we harnessed CRISPRi to downregulate 32 essential and non-essential genes in E. coli strains heterologously expressing either the original mevalonate pathway or isopentenyl diphosphate (IPP) bypass pathway for isoprenol biosynthesis. Isoprenol remains a candidate bioproduct both as a drop-in blend additive and as a precursor for the high-performance sustainable aviation fuel, 1,4-dimethylcyclooctane (DMCO). Of the 32 gRNAs targeting genes associated with isoprenol biosynthesis, a subset was found to vastly improve product titers. Construction of a multiplexed gRNA library based on single guide RNA (sgRNA) performance enabled simultaneous gene repression, yielding a 3 to 4.5-fold increase in isoprenol titer (1.82 ± 0.19 g/L) on M9-MOPS minimal medium. We then scaled the best performing CRISPRi strain to 2-L fed-batch cultivation and demonstrated translatable titer improvements, ultimately obtaining 12.4 ± 1.3 g/L isoprenol. Our strategy further establishes CRISPRi as a powerful tool for tuning metabolic flux in production hosts and that titer improvements are readily scalable with potential for applications in industrial bioproduction.
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Affiliation(s)
- Jinho Kim
- Joint BioEnergy Institute, Emeryville, CA, United States
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Taek Soon Lee
- Joint BioEnergy Institute, Emeryville, CA, United States
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
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Feng Q, Ning X, Qin L, Li J, Li C. Quantitative and modularized CRISPR/dCas9-dCpf1 dual function system in Saccharomyces cerevisiae. Front Bioeng Biotechnol 2023; 11:1218832. [PMID: 38026848 PMCID: PMC10666755 DOI: 10.3389/fbioe.2023.1218832] [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] [Received: 05/08/2023] [Accepted: 10/05/2023] [Indexed: 12/01/2023] Open
Abstract
Introduction: Both CRISPR/dCas9 and CRISPR/dCpf1 genome editing systems have shown exciting promises in modulating yeast cell metabolic pathways. However, each system has its deficiencies to overcome. In this study, to achieve a compensatory effect, we successfully constructed a dual functional CRISPR activation/inhibition (CRISPRa/i) system based on Sp-dCas9 and Fn-dCpf1 proteins, along with their corresponding complementary RNAs. Methods: We validated the high orthogonality and precise quantity targeting of selected yeast promoters. Various activating effector proteins (VP64, p65, Rta, and VP64-p65-Rta) and inhibiting effector proteins (KRAB, MeCP2, and KRAB-MeCP2), along with RNA scaffolds of MS2, PP7 and crRNA arrays were implemented in different combinations to investigate quantitative promoter strength. In the CRISPR/dCas9 system, the regulation rate ranged from 81.9% suppression to 627% activation in the mCherry gene reporter system. Studies on crRNA point mutations and crRNA arrays were conducted in the CRISPR/dCpf1 system, with the highest transcriptional inhibitory rate reaching up to 530% higher than the control. Furthermore, the orthogonal CRISPR/dCas9-dCpf1 inhibition system displayed distinct dual functions, simultaneously regulating the mCherry gene by dCas9/gRNA (54.6% efficiency) and eGFP gene by dCpf1/crRNA (62.4% efficiency) without signal crosstalk. Results and discussion: Finally, we established an engineered yeast cell factory for β-carotene production using the CRISPR/dCas9-dCpf1 bifunctional system to achieve targeted modulation of both heterologous and endogenous metabolic pathways in Saccharomyces cerevisiae. The system includes an activation module of CRISPRa/dCas9 corresponding to a gRNA-protein complex library of 136 plasmids, and an inhibition module of CRISPRi/dCpf1 corresponding to a small crRNA array library. Results show that this CRISPR/dCas9-dCpf1 bifunctional orthogonal system is more quantitatively effective and expandable for simultaneous CRISPRa/i network control compared to single-guide edition, demonstrating higher potential of future application in yeast biotechnology.
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Affiliation(s)
- Qing Feng
- Key Laboratory of Medical Molecule Science and Pharmaceutics Engineering, School of Chemistry and Chemical Engineering, Ministry of Industry and Information Technology, Beijing Institute of Technology, Beijing, China
| | - Xiaoyu Ning
- Key Laboratory of Medical Molecule Science and Pharmaceutics Engineering, School of Chemistry and Chemical Engineering, Ministry of Industry and Information Technology, Beijing Institute of Technology, Beijing, China
| | - Lei Qin
- Key Lab for Industrial Biocatalysis, Department of Chemical Engineering, Ministry of Education, Tsinghua University, Beijing, China
| | - Jun Li
- Key Laboratory of Medical Molecule Science and Pharmaceutics Engineering, School of Chemistry and Chemical Engineering, Ministry of Industry and Information Technology, Beijing Institute of Technology, Beijing, China
| | - Chun Li
- Key Lab for Industrial Biocatalysis, Department of Chemical Engineering, Ministry of Education, Tsinghua University, Beijing, China
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6
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Huang T, Ma Y. Advances in biosynthesis of higher alcohols in Escherichia coli. World J Microbiol Biotechnol 2023; 39:125. [PMID: 36941474 DOI: 10.1007/s11274-023-03580-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 03/13/2023] [Indexed: 03/23/2023]
Abstract
In recent years, the development of green energy to replace fossil fuels has been the focus of research. Higher alcohols are important biofuels and chemicals. The production of higher alcohols in microbes has gained attention due to its environmentally friendly character. Higher alcohols have been synthesized in model microorganism Escherichia coli, and the production has reached the gram level through enhancement of metabolic flow, the balance of reducing power and the optimization of fermentation processes. Sustainable bio-higher alcohols production is expected to replace fossil fuels as a green and renewable energy source. Therefore, this review summarizes the latest developments in producing higher alcohols (C3-C6) by E. coli, elucidate the main bottlenecks limiting the biosynthesis of higher alcohols, and proposes potential engineering strategies of improving the production of biological higher alcohols. This review would provide a theoretical basis for further research on higher alcohols production by E. coli.
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Affiliation(s)
- Tong Huang
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, People's Republic of China
| | - Yuanyuan Ma
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, People's Republic of China.
- School of Marin Science and Technology, Tianjin University, Tianjin, 300072, China.
- R&D Center for Petrochemical Technology, Tianjin University, Tianjin, 300072, China.
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7
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Metabolic Engineering of Microorganisms to Produce Pyruvate and Derived Compounds. Molecules 2023; 28:molecules28031418. [PMID: 36771084 PMCID: PMC9919917 DOI: 10.3390/molecules28031418] [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] [Received: 01/09/2023] [Revised: 01/27/2023] [Accepted: 01/29/2023] [Indexed: 02/05/2023] Open
Abstract
Pyruvate is a hub of various endogenous metabolic pathways, including glycolysis, TCA cycle, amino acid, and fatty acid biosynthesis. It has also been used as a precursor for pyruvate-derived compounds such as acetoin, 2,3-butanediol (2,3-BD), butanol, butyrate, and L-alanine biosynthesis. Pyruvate and derivatives are widely utilized in food, pharmaceuticals, pesticides, feed additives, and bioenergy industries. However, compounds such as pyruvate, acetoin, and butanol are often chemically synthesized from fossil feedstocks, resulting in declining fossil fuels and increasing environmental pollution. Metabolic engineering is a powerful tool for producing eco-friendly chemicals from renewable biomass resources through microbial fermentation. Here, we review and systematically summarize recent advances in the biosynthesis pathways, regulatory mechanisms, and metabolic engineering strategies for pyruvate and derivatives. Furthermore, the establishment of sustainable industrial synthesis platforms based on alternative substrates and new tools to produce these compounds is elaborated. Finally, we discuss the potential difficulties in the current metabolic engineering of pyruvate and derivatives and promising strategies for constructing efficient producers.
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8
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Kolasinliler G, Aagre MM, Akkale C, Kaya HB. The use of CRISPR-Cas-based systems in bacterial cell factories. Biochem Eng J 2023. [DOI: 10.1016/j.bej.2023.108880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2023]
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9
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Yeom J, Park JS, Jung SW, Lee S, Kwon H, Yoo SM. High-throughput genetic engineering tools for regulating gene expression in a microbial cell factory. Crit Rev Biotechnol 2023; 43:82-99. [PMID: 34957867 DOI: 10.1080/07388551.2021.2007351] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
With the rapid advances in biotechnological tools and strategies, microbial cell factory-constructing strategies have been established for the production of value-added compounds. However, optimizing the tradeoff between the biomass, yield, and titer remains a challenge in microbial production. Gene regulation is necessary to optimize and control metabolic fluxes in microorganisms for high-production performance. Various high-throughput genetic engineering tools have been developed for achieving rational gene regulation and genetic perturbation, diversifying the cellular phenotype and enhancing bioproduction performance. In this paper, we review the current high-throughput genetic engineering tools for gene regulation. In particular, technological approaches used in a diverse range of genetic tools for constructing microbial cell factories are introduced, and representative applications of these tools are presented. Finally, the prospects for high-throughput genetic engineering tools for gene regulation are discussed.
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Affiliation(s)
- Jinho Yeom
- School of Integrative Engineering, Chung-Ang University, Seoul, Republic of Korea
| | - Jong Seong Park
- School of Integrative Engineering, Chung-Ang University, Seoul, Republic of Korea
| | - Seung-Woon Jung
- School of Integrative Engineering, Chung-Ang University, Seoul, Republic of Korea
| | - Sumin Lee
- School of Integrative Engineering, Chung-Ang University, Seoul, Republic of Korea
| | - Hyukjin Kwon
- School of Integrative Engineering, Chung-Ang University, Seoul, Republic of Korea
| | - Seung Min Yoo
- School of Integrative Engineering, Chung-Ang University, Seoul, Republic of Korea
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10
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Nadolinskaia NI, Goncharenko AV. CRISPR Interference in Regulation of Bacterial Gene Expression. Mol Biol 2022. [DOI: 10.1134/s0026893322060139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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11
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Luo J, Efimova E, Volke DC, Santala V, Santala S. Engineering cell morphology by CRISPR interference in Acinetobacter baylyi ADP1. Microb Biotechnol 2022; 15:2800-2818. [PMID: 36005297 DOI: 10.1111/1751-7915.14133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 07/29/2022] [Accepted: 08/08/2022] [Indexed: 11/26/2022] Open
Abstract
Microbial production of intracellular compounds can be engineered by redirecting the carbon flux towards products and increasing the cell size. Potential engineering strategies include exploiting clustered regularly interspaced short palindromic repeats interference (CRISPRi)-based tools for controlling gene expression. Here, we applied CRISPRi for engineering Acinetobacter baylyi ADP1, a model bacterium for synthesizing intracellular storage lipids, namely wax esters. We first established an inducible CRISPRi system for strain ADP1, which enables tightly controlled repression of target genes. We then targeted the glyoxylate shunt to redirect carbon flow towards wax esters. Second, we successfully employed CRISPRi for modifying cell morphology by repressing ftsZ, an essential gene required for cell division, in combination with targeted knock-outs to generate significantly enlarged filamentous or spherical cells respectively. The engineered cells sustained increased wax ester production metrics, demonstrating the potential of cell morphology engineering in the production of intracellular lipids.
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Affiliation(s)
- Jin Luo
- Faculty of Engineering and Natural Sciences, Tampere University, Tampere, Finland
| | - Elena Efimova
- Faculty of Engineering and Natural Sciences, Tampere University, Tampere, Finland
| | - Daniel Christoph Volke
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Ville Santala
- Faculty of Engineering and Natural Sciences, Tampere University, Tampere, Finland
| | - Suvi Santala
- Faculty of Engineering and Natural Sciences, Tampere University, Tampere, Finland
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12
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Wang HD, Xu JZ, Zhang WG. Metabolic engineering of Escherichia coli for efficient production of L-arginine. Appl Microbiol Biotechnol 2022; 106:5603-5613. [PMID: 35931894 DOI: 10.1007/s00253-022-12109-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 07/15/2022] [Accepted: 07/27/2022] [Indexed: 11/02/2022]
Abstract
As an important semi-essential amino acid, L-arginine (L-Arg) has important application prospects in medicine and health care. However, it remains a challenge to efficiently produce L-Arg by Escherichia coli (E. coli). In the present study, we obtained an E. coli A1 with L-Arg accumulation ability, and carried out a series of metabolic engineering on it, and finally obtained an E. coli strain A7 with high L-Arg production ability. First, genome analysis of strain A1 was performed to explore the related genes affecting L-Arg accumulation. We found that gene speC and gene speF played an important role in the accumulation of L-Arg. Second, we used two strategies to solve the feedback inhibition of the L-Arg pathway in E. coli. One was the combination of a mutation of the gene argA and the deletion of the gene argR, and the other was the combination of a heterologous insertion of the gene argJ and the deletion of the gene argR. The combination of exogenous argJ gene insertion and argR gene deletion achieved higher titer accumulation with less impact on strain growth. Finally, we inserted the gene cluster argCJBDF of Corynebacterium glutamicum (C. glutamicum) to enhance the metabolic flux of the L-Arg pathway in E. coli. The final strain obtained 70.1 g/L L-Arg in a 5-L bioreactor, with a yield of 0.326 g/g glucose and a productivity of 1.17 g/(L· h). This was the highest level of L-Arg production by E. coli ever reported. Collectively, our findings provided valuable insights into the possibility of the industrial production of L-Arg by E. coli. KEY POINTS: • Genetic background of E. coli A1 genome analysis. • Heterologous argJ substitution of argA mutation promoted excessive accumulation of L-Arg in E. coli A1. • The overexpression of L-Arg synthesis gene cluster argCJBDF of Corynebacterium glutamicum (C. glutamate) promoted the accumulation of L-Arg, and 70.1 g/L L-Arg was finally obtained in fed-batch fermentation.
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Affiliation(s)
- Hai-De Wang
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1,800# Lihu Road, 214122, WuXi, People's Republic of China
| | - Jian-Zhong Xu
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1,800# Lihu Road, 214122, WuXi, People's Republic of China.
| | - Wei-Guo Zhang
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1,800# Lihu Road, 214122, WuXi, People's Republic of China.
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13
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Wu Q, Cui L, Liu Y, Li R, Dai M, Xia Z, Wu M. CRISPR-Cas systems target endogenous genes to impact bacterial physiology and alter mammalian immune responses. MOLECULAR BIOMEDICINE 2022; 3:22. [PMID: 35854035 PMCID: PMC9296731 DOI: 10.1186/s43556-022-00084-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Accepted: 05/25/2022] [Indexed: 11/26/2022] Open
Abstract
CRISPR-Cas systems are an immune defense mechanism that is widespread in archaea and bacteria against invasive phages or foreign genetic elements. In the last decade, CRISPR-Cas systems have been a leading gene-editing tool for agriculture (plant engineering), biotechnology, and human health (e.g., diagnosis and treatment of cancers and genetic diseases), benefitted from unprecedented discoveries of basic bacterial research. However, the functional complexity of CRISPR systems is far beyond the original scope of immune defense. CRISPR-Cas systems are implicated in influencing the expression of physiology and virulence genes and subsequently altering the formation of bacterial biofilm, drug resistance, invasive potency as well as bacterial own physiological characteristics. Moreover, increasing evidence supports that bacterial CRISPR-Cas systems might intriguingly influence mammalian immune responses through targeting endogenous genes, especially those relating to virulence; however, unfortunately, their underlying mechanisms are largely unclear. Nevertheless, the interaction between bacterial CRISPR-Cas systems and eukaryotic cells is complex with numerous mysteries that necessitate further investigation efforts. Here, we summarize the non-canonical functions of CRISPR-Cas that potentially impact bacterial physiology, pathogenicity, antimicrobial resistance, and thereby altering the courses of mammalian immune responses.
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Affiliation(s)
- Qun Wu
- Department of Pediatrics, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
- Department of Biomedical Sciences, School of Medicine and Health Sciences University of North Dakota, Grand Forks, North Dakota, 58203-9037, USA
| | - Luqing Cui
- Department of Biomedical Sciences, School of Medicine and Health Sciences University of North Dakota, Grand Forks, North Dakota, 58203-9037, USA
- The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, Hubei, 430070, P. R. China
| | - Yingying Liu
- Department of Biomedical Sciences, School of Medicine and Health Sciences University of North Dakota, Grand Forks, North Dakota, 58203-9037, USA
| | - Rongpeng Li
- Key Laboratory of Biotechnology for Medicinal Plants of Jiangsu Province, School of Life Sciences, Jiangsu Normal University, Xuzhou, 221116, China
| | - Menghong Dai
- The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, Hubei, 430070, P. R. China.
| | - Zhenwei Xia
- Department of Pediatrics, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
| | - Min Wu
- Department of Biomedical Sciences, School of Medicine and Health Sciences University of North Dakota, Grand Forks, North Dakota, 58203-9037, USA.
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14
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Parsaeimehr A, Ebirim RI, Ozbay G. CRISPR-Cas technology a new era in genomic engineering. BIOTECHNOLOGY REPORTS 2022; 34:e00731. [PMID: 35686011 PMCID: PMC9171425 DOI: 10.1016/j.btre.2022.e00731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 04/08/2022] [Accepted: 04/10/2022] [Indexed: 11/01/2022]
Abstract
CRISPR-Cas systems offer a flexible and easy-to-use molecular platform to precisely modify and control organisms' genomes in a variety of fields, from agricultural biotechnology to therapeutics. With CRISPR technology, crop genomes can be precisely edited in a shorter and more efficient approach compared to traditional breeding or classic mutagenesis. CRISPR-Cas system can be used to manage the fermentation process by addressing phage resistance, antimicrobial activity, and genome editing. CRISPR-Cas technology has opened up a new era in gene therapy and other therapeutic fields and given hope to thousands of patients with genetic diseases. Anti-CRISPR molecules are powerful tools for regulating the CRISPR-Cas systems.
The CRISPR-Cas systems have offered a flexible, easy-to-use platform to precisely modify and control the genomes of organisms in various fields, ranging from agricultural biotechnology to therapeutics. This system is extensively used in the study of infectious, progressive, and life-threatening genetic diseases for the improvement of quality and quantity of major crops and in the development of sustainable methods for the generation of biofuels. As CRISPR-Cas technology continues to evolve, it is becoming more controllable and precise with the addition of molecular regulators, which will provide benefits for everyone and save many lives. Studies on the constant growth of CRISPR technology are important due to its rapid development. In this paper, we present the current applications and progress of CRISPR-Cas genome editing systems in several fields of research, we further highlight the applications of anti-CRISPR molecules to regulate CRISPR-Cas gene editing systems, and we discuss ethical considerations in CRISPR-Cas applications.
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15
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Engineering E. coli to synthesize butanol. Biochem Soc Trans 2022; 50:867-876. [PMID: 35356968 DOI: 10.1042/bst20211009] [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: 11/04/2021] [Revised: 02/22/2022] [Accepted: 03/15/2022] [Indexed: 11/17/2022]
Abstract
Biobutanol is gaining much attention as a potential biofuel due to its superior properties over ethanol. Butanol has been naturally produced via acetone-butanol-ethanol (ABE) fermentation by many Clostridium species, which are not very user-friendly bacteria. Therefore, to improve butanol titers and yield, various butanol synthesis pathways have been engineered in Escherichia coli, a much more robust and convenient host than Clostridium species. This review mainly focuses on the biosynthesis of n-butanol in engineered E. coli with an emphasis on efficient enzymes for butanol production in E. coli, butanol competing pathways, and genome engineering of E. coli for butanol production. In addition, the use of alternate strategies for butanol biosynthesis/enhancement, alternate substrates for the low cost of butanol production, and genetic improvement for butanol tolerance in E. coli have also been discussed.
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16
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Hai-De W, Shuai L, Bing-Bing W, Jie L, Jian-Zhong X, Wei-Guo Z. Metabolic engineering of Escherichia coli for efficient production of l-arginine. ADVANCES IN APPLIED MICROBIOLOGY 2022; 122:127-150. [PMID: 37085192 DOI: 10.1016/bs.aambs.2022.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
As a semi-essential amino acid, l-arginine (l-Arg) plays an important role in food, health care, and medical treatment. At present, the main method of producing l-Arg is the use of microbial fermentation. Therefore, the selection and breeding of high-efficiency microbial strains is the top priority. To continuously improve the l-Arg production performance of the strains, a series of metabolic engineering strategies have been tried to transform the strains. The production of l-Arg by metabolically engineered Corynebacterium glutamicum (C. glutamicum) reached a relatively high level. Escherichia coli (E. coli), as a strain with great potential for l-Arg production, also has a large number of research strategies aimed at screening effective E. coli for producing l-Arg. E. coli also has a number of advantages over C. glutamicum in producing l-Arg. Therefore, it is of great significance to screen out excellent and stable E. coli to produce l-Arg. Here, based on recent research results, we review the metabolic pathways of l-Arg production in E. coli, the research progress of l-Arg production in E. coli, and various regulatory strategies implemented in E. coli.
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17
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Backes N, Phillips GJ. Repurposing CRISPR-Cas Systems as Genetic Tools for the Enterobacteriales. EcoSal Plus 2021; 9:eESP00062020. [PMID: 34125584 PMCID: PMC11163844 DOI: 10.1128/ecosalplus.esp-0006-2020] [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: 03/15/2021] [Accepted: 03/22/2021] [Indexed: 11/20/2022]
Abstract
Over the last decade, the study of CRISPR-Cas systems has progressed from a newly discovered bacterial defense mechanism to a diverse suite of genetic tools that have been applied across all domains of life. While the initial applications of CRISPR-Cas technology fulfilled a need to more precisely edit eukaryotic genomes, creative "repurposing" of this adaptive immune system has led to new approaches for genetic analysis of microorganisms, including improved gene editing, conditional gene regulation, plasmid curing and manipulation, and other novel uses. The main objective of this review is to describe the development and current state-of-the-art use of CRISPR-Cas techniques specifically as it is applied to members of the Enterobacteriales. While many of the applications covered have been initially developed in Escherichia coli, we also highlight the potential, along with the limitations, of this technology for expanding the availability of genetic tools in less-well-characterized non-model species, including bacterial pathogens.
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Affiliation(s)
- Nicholas Backes
- Department of Veterinary Microbiology, Iowa State University, Ames, Iowa, USA
| | - Gregory J. Phillips
- Department of Veterinary Microbiology, Iowa State University, Ames, Iowa, USA
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18
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Banu JR, Kumar G, Chattopadhyay I. Management of microbial enzymes for biofuels and biogas production by using metagenomic and genome editing approaches. 3 Biotech 2021; 11:429. [PMID: 34603908 DOI: 10.1007/s13205-021-02962-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Accepted: 08/04/2021] [Indexed: 12/16/2022] Open
Abstract
Non-renewable fossil fuels such as bitumen, coal, natural gas, oil shale, and petroleum are depleting over the world owing to unrestricted consumption. Biofuels such as biodiesel, biobutanol, bioethanol, and biogas are considered an eco-friendly and cost-effective alternatives of fossil fuels. For energy sustainability, the production of advanced biofuels is required. The advancement of genetic and metabolic engineering in microbial cells played a significant contribution to biofuels overproduction. Essential approaches such as next-generation sequencing technologies and CRISPR/Cas9-mediated genome editing of microbial cells are required for the mass manufacture of biofuels globally. Advanced "omics" approaches are used to construct effective microorganisms for biofuels manufacturing. A new investigation is required to augment the production of lignocellulosic-based biofuels with minimal use of energy. Advanced areas of metabolic engineering are introduced in the manufacture of biofuels by the use of engineered microbial strains. Genetically modified microorganisms are used for the production of biofuels in large quantities at a low-cost.
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Affiliation(s)
- J Rajesh Banu
- Department of Life Sciences, Central University of Tamil Nadu, Thiruvarur, Tamilnadu India
| | - Gopalakrishnan Kumar
- Faculty of Science and Technology, Institute of Chemistry, Bioscience and Environmental Engineering, University of Stavanger, Forus, Box 8600, 4036 Stavanger, Norway
| | - Indranil Chattopadhyay
- Department of Life Sciences, Central University of Tamil Nadu, Thiruvarur, Tamilnadu India
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19
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Karlson CKS, Mohd-Noor SN, Nolte N, Tan BC. CRISPR/dCas9-Based Systems: Mechanisms and Applications in Plant Sciences. PLANTS 2021; 10:plants10102055. [PMID: 34685863 PMCID: PMC8540305 DOI: 10.3390/plants10102055] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 09/20/2021] [Accepted: 09/27/2021] [Indexed: 12/26/2022]
Abstract
RNA-guided genomic transcriptional regulation tools, namely clustered regularly interspaced short palindromic repeats interference (CRISPRi) and CRISPR-mediated gene activation (CRISPRa), are a powerful technology for gene functional studies. Deriving from the CRISPR/Cas9 system, both systems consist of a catalytically dead Cas9 (dCas9), a transcriptional effector and a single guide RNA (sgRNA). This type of dCas9 is incapable to cleave DNA but retains its ability to specifically bind to DNA. The binding of the dCas9/sgRNA complex to a target gene results in transcriptional interference. The CRISPR/dCas9 system has been explored as a tool for transcriptional modulation and genome imaging. Despite its potential applications and benefits, the challenges and limitations faced by the CRISPR/dCas9 system include the off-target effects, protospacer adjacent motif (PAM) sequence requirements, efficient delivery methods and the CRISPR/dCas9-interfered crops being labeled as genetically modified organisms in several countries. This review highlights the progression of CRISPR/dCas9 technology as well as its applications and potential challenges in crop improvement.
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Affiliation(s)
- Chou Khai Soong Karlson
- Center for Research in Biotechnology for Agriculture (CEBAR), Universiti Malaya, Kuala Lumpur 50603, Malaysia;
| | - Siti Nurfadhlina Mohd-Noor
- Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, Bangi 43600, Malaysia;
| | - Nadja Nolte
- Department of Plant Sciences, Wageningen University & Research, Droevendaalsesteeg 4, 6708 PB Wageningen, The Netherlands;
| | - Boon Chin Tan
- Center for Research in Biotechnology for Agriculture (CEBAR), Universiti Malaya, Kuala Lumpur 50603, Malaysia;
- Correspondence: ; Tel.: +60-3-7967-7982
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20
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Genome-scale target identification in Escherichia coli for high-titer production of free fatty acids. Nat Commun 2021; 12:4976. [PMID: 34404790 PMCID: PMC8371096 DOI: 10.1038/s41467-021-25243-w] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 07/29/2021] [Indexed: 12/17/2022] Open
Abstract
To construct a superior microbial cell factory for chemical synthesis, a major challenge is to fully exploit cellular potential by identifying and engineering beneficial gene targets in sophisticated metabolic networks. Here, we take advantage of CRISPR interference (CRISPRi) and omics analyses to systematically identify beneficial genes that can be engineered to promote free fatty acids (FFAs) production in Escherichia coli. CRISPRi-mediated genetic perturbation enables the identification of 30 beneficial genes from 108 targets related to FFA metabolism. Then, omics analyses of the FFAs-overproducing strains and a control strain enable the identification of another 26 beneficial genes that are seemingly irrelevant to FFA metabolism. Combinatorial perturbation of four beneficial genes involving cellular stress responses results in a recombinant strain ihfAL−-aidB+-ryfAM−-gadAH−, producing 30.0 g L−1 FFAs in fed-batch fermentation, the maximum titer in E. coli reported to date. Our findings are of help in rewiring cellular metabolism and interwoven intracellular processes to facilitate high-titer production of biochemicals. Identification of gene targets is one of the major challenges to construct superior microbial cell factory for chemical synthesis. Here, the authors employ CRISPRi and omics analyses for genome-scale target genes identification for high-titer production of free fatty acids in E. coli.
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21
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Luo ZW, Ahn JH, Chae TU, Choi SY, Park SY, Choi Y, Kim J, Prabowo CPS, Lee JA, Yang D, Han T, Xu H, Lee SY. Metabolic Engineering of
Escherichia
coli. Metab Eng 2021. [DOI: 10.1002/9783527823468.ch11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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22
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Lee H, Baek JI, Lee JY, Jeong J, Kim H, Lee DH, Kim DM, Lee SG. Syntrophic co-culture of a methanotroph and heterotroph for the efficient conversion of methane to mevalonate. Metab Eng 2021; 67:285-292. [PMID: 34298134 DOI: 10.1016/j.ymben.2021.07.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 06/07/2021] [Accepted: 07/18/2021] [Indexed: 10/20/2022]
Abstract
As the bioconversion of methane becomes increasingly important for bio-industrial and environmental applications, methanotrophs have received much attention for their ability to convert methane under ambient conditions. This includes the extensive reporting of methanotroph engineering for the conversion of methane to biochemicals. To further increase methane usability, we demonstrated a highly flexible and efficient modular approach based on a synthetic consortium of methanotrophs and heterotrophs mimicking the natural methane ecosystem to produce mevalonate (MVA) from methane. In the methane-conversion module, we used Methylococcus capsulatus Bath as a highly efficient methane biocatalyst and optimized the culture conditions for the production of high amounts of organic acids. In the MVA-synthesis module, we used Escherichia coli SBA01, an evolved strain with high organic acid tolerance and utilization ability, to convert organic acids to MVA. Using recombinant E. coli SBA01 possessing genes for the MVA pathway, 61 mg/L (0.4 mM) of MVA was successfully produced in 48 h without any addition of nutrients except methane. Our platform exhibited high stability and reproducibility with regard to cell growth and MVA production. We believe that this versatile system can be easily extended to many other value-added processes and has a variety of potential applications.
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Affiliation(s)
- Hyewon Lee
- Synthetic Biology and Bioengineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Republic of Korea
| | - Ji In Baek
- Synthetic Biology and Bioengineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Republic of Korea; Department of Chemical Engineering and Applied Chemistry, Chungnam National University, 99 Daehak-ro, 34134, Republic of Korea
| | - Jin-Young Lee
- Synthetic Biology and Bioengineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Republic of Korea
| | - Jiyeong Jeong
- Synthetic Biology and Bioengineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Republic of Korea
| | - Haseong Kim
- Synthetic Biology and Bioengineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Republic of Korea
| | - Dae-Hee Lee
- Synthetic Biology and Bioengineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Republic of Korea; Department of Biosystems and Bioengineering, KRIBB School of Biotechnology, University of Science & Technology (UST), Daejeon, 34113, Republic of Korea
| | - Dong-Myung Kim
- Department of Chemical Engineering and Applied Chemistry, Chungnam National University, 99 Daehak-ro, 34134, Republic of Korea
| | - Seung-Goo Lee
- Synthetic Biology and Bioengineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Republic of Korea; Department of Biosystems and Bioengineering, KRIBB School of Biotechnology, University of Science & Technology (UST), Daejeon, 34113, Republic of Korea.
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23
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Recent advances in tuning the expression and regulation of genes for constructing microbial cell factories. Biotechnol Adv 2021; 50:107767. [PMID: 33974979 DOI: 10.1016/j.biotechadv.2021.107767] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 04/29/2021] [Accepted: 05/05/2021] [Indexed: 12/14/2022]
Abstract
To overcome environmental problems caused by the use of fossil resources, microbial cell factories have become a promising technique for the sustainable and eco-friendly development of valuable products from renewable resources. Constructing microbial cell factories with high titers, yields, and productivity requires a balance between growth and production; to this end, tuning gene expression and regulation is necessary to optimise and precisely control complicated metabolic fluxes. In this article, we review the current trends and advances in tuning gene expression and regulation and consider their engineering at each of the three stages of gene regulation: genomic, mRNA, and protein. In particular, the technological approaches utilised in a diverse range of genetic-engineering-based tools for the construction of microbial cell factories are reviewed and representative applications of these strategies are presented. Finally, the prospects for strategies and systems for tuning gene expression and regulation are discussed.
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24
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Zhang R, Xu W, Shao S, Wang Q. Gene Silencing Through CRISPR Interference in Bacteria: Current Advances and Future Prospects. Front Microbiol 2021; 12:635227. [PMID: 33868193 PMCID: PMC8044314 DOI: 10.3389/fmicb.2021.635227] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 02/24/2021] [Indexed: 11/30/2022] Open
Abstract
Functional genetic screening is an important method that has been widely used to explore the biological processes and functional annotation of genetic elements. CRISPR/Cas (Clustered regularly interspaced short palindromic repeat sequences/CRISPR-associated protein) is the newest tool in the geneticist’s toolbox, allowing researchers to edit a genome with unprecedented ease, accuracy, and high-throughput. Most recently, CRISPR interference (CRISPRi) has been developed as an emerging technology that exploits the catalytically inactive Cas9 (dCas9) and single-guide RNA (sgRNA) to repress sequence-specific genes. In this review, we summarized the characteristics of the CRISPRi system, such as programmable, highly efficient, and specific. Moreover, we demonstrated its applications in functional genetic screening and highlighted its potential to dissect the underlying mechanism of pathogenesis. The recent development of the CRISPRi system will provide a high-throughput, practical, and efficient tool for the discovery of functionally important genes in bacteria.
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Affiliation(s)
- Riyu Zhang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Wensheng Xu
- Laboratory of Agricultural Product Detection and Control of Spoilage Organisms and Pesticide Residue, Faculty of Food Science and Engineering, Beijing University of Agriculture, Beijing, China
| | - Shuai Shao
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Qiyao Wang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China.,Shanghai Collaborative Innovation Center for Biomanufacturing Technology, Shanghai, China.,Shanghai Engineering Research Center of Maricultured Animal Vaccines, Shanghai, China
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25
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Panich J, Fong B, Singer SW. Metabolic Engineering of Cupriavidus necator H16 for Sustainable Biofuels from CO 2. Trends Biotechnol 2021; 39:412-424. [PMID: 33518389 DOI: 10.1016/j.tibtech.2021.01.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 01/05/2021] [Accepted: 01/06/2021] [Indexed: 02/08/2023]
Abstract
Decelerating global warming is one of the predominant challenges of our time and will require conversion of CO2 to usable products and commodity chemicals. Of particular interest is the production of fuels, because the transportation sector is a major source of CO2 emissions. Here, we review recent technological advances in metabolic engineering of the hydrogen-oxidizing bacterium Cupriavidus necator H16, a chemolithotroph that naturally consumes CO2 to generate biomass. We discuss recent successes in biofuel production using this organism, and the implementation of electrolysis/artificial photosynthesis approaches that enable growth of C. necator using renewable electricity and CO2. Last, we discuss prospects of improving the nonoptimal growth of C. necator in ambient concentrations of CO2.
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Affiliation(s)
- Justin Panich
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
| | - Bonnie Fong
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Steven W Singer
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
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26
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Miscevic D, Mao JY, Kefale T, Abedi D, Moo-Young M, Perry Chou C. Strain engineering for high-level 5-aminolevulinic acid production in Escherichia coli. Biotechnol Bioeng 2020; 118:30-42. [PMID: 32860420 DOI: 10.1002/bit.27547] [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] [Received: 03/06/2020] [Revised: 08/19/2020] [Accepted: 08/26/2020] [Indexed: 12/16/2022]
Abstract
Herein, we report the development of a microbial bioprocess for high-level production of 5-aminolevulinic acid (5-ALA), a valuable non-proteinogenic amino acid with multiple applications in medical, agricultural, and food industries, using Escherichia coli as a cell factory. We first implemented the Shemin (i.e., C4) pathway for heterologous 5-ALA biosynthesis in E. coli. To reduce, but not to abolish, the carbon flux toward essential tetrapyrrole/porphyrin biosynthesis, we applied clustered regularly interspersed short palindromic repeats interference (CRISPRi) to repress hemB expression, leading to extracellular 5-ALA accumulation. We then applied metabolic engineering strategies to direct more dissimilated carbon flux toward the key precursor of succinyl-CoA for enhanced 5-ALA biosynthesis. Using these engineered E. coli strains for bioreactor cultivation, we successfully demonstrated high-level 5-ALA biosynthesis from glycerol (~30 g L-1 ) under both microaerobic and aerobic conditions, achieving up to 5.95 g L-1 (36.9% of the theoretical maximum yield) and 6.93 g L-1 (50.9% of the theoretical maximum yield) 5-ALA, respectively. This study represents one of the most effective bio-based production of 5-ALA from a structurally unrelated carbon to date, highlighting the importance of integrated strain engineering and bioprocessing strategies to enhance bio-based production.
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Affiliation(s)
- Dragan Miscevic
- Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada
| | - Ju-Yi Mao
- Department of Bioscience and Biotechnology, National Taiwan Ocean University, Keelung, Canada
| | - Teshager Kefale
- Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada.,Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
| | - Daryoush Abedi
- Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada.,Department of Drug & Food Control, Tehran University of Medical Sciences, Tehran, Iran
| | - Murray Moo-Young
- Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada
| | - C Perry Chou
- Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada
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27
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Liu Z, Dong H, Cui Y, Cong L, Zhang D. Application of different types of CRISPR/Cas-based systems in bacteria. Microb Cell Fact 2020; 19:172. [PMID: 32883277 PMCID: PMC7470686 DOI: 10.1186/s12934-020-01431-z] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Accepted: 08/25/2020] [Indexed: 12/26/2022] Open
Abstract
As important genome editing tools, CRISPR/Cas systems, especially those based on type II Cas9 and type V Cas12a, are widely used in genetic and metabolic engineering of bacteria. However, the intrinsic toxicity of Cas9 and Cas12a-mediated CRISPR/Cas tools can lead to cell death in some strains, which led to the development of endogenous type I and III CRISPR/Cas systems. However, these systems are hindered by complicated development and limited applications. Thus, further development and optimization of CRISPR/Cas systems is needed. Here, we briefly summarize the mechanisms of different types of CRISPR/Cas systems as genetic manipulation tools and compare their features to provide a reference for selecting different CRISPR/Cas tools. Then, we show the use of CRISPR/Cas technology for bacterial strain evolution and metabolic engineering, including genome editing, gene expression regulation and the base editor tool. Finally, we offer a view of future directions for bacterial CRISPR/Cas technology.
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Affiliation(s)
- Zhenquan Liu
- School of Biological Engineering, Dalian Polytechnic University, Dalian, 116034, People's Republic of China.,Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China.,Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, People's Republic of China
| | - Huina Dong
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China.,Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, People's Republic of China
| | - Yali Cui
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China.,Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, People's Republic of China
| | - Lina Cong
- School of Biological Engineering, Dalian Polytechnic University, Dalian, 116034, People's Republic of China.
| | - Dawei Zhang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China. .,Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, People's Republic of China. .,University of Chinese Academy of Sciences, Beijing, 100049, China.
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28
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Li Q, Zhao P, Yin H, Liu Z, Zhao H, Tian P. CRISPR interference-guided modulation of glucose pathways to boost aconitic acid production in Escherichia coli. Microb Cell Fact 2020; 19:174. [PMID: 32883305 PMCID: PMC7470443 DOI: 10.1186/s12934-020-01435-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 08/27/2020] [Indexed: 12/26/2022] Open
Abstract
Background One major mission of microbial breeding is high-level production of desired metabolites. Overproduction of intermediate metabolites in core pathways is challenging as it may impair cell growth and viability. Results Here we report that aconitic acid, an intermediate metabolite in tricarboxylic acid (TCA) cycle, can be overproduced by an engineered CRISPR interference (CRISPRi) system in Escherichia coli. This CRISPRi system was designed to simultaneously target pyruvate kinase (PK) and isocitrate dehydrogenase (IDH), two enzymes in glycolytic pathway and TCA cycle, respectively. Reverse transcription and quantitative PCR and enzyme activity assays showed that this engineered CRISPRi system significantly repressed the genes encoding IDH and PK, resulting in simultaneous reduction in the activities of IDH and PK. In shake-flask and fed-batch cultivation, this CRISPRi strain produced 60-fold (362.80 ± 22.05 mg/L) and 15-fold (623.80 ± 20.05 mg/L) of aconitic acid relative to the control strain, respectively. In addition, this two-target CRISPRi strain maintained low levels of acetate and lactate, two problematic byproducts. Conclusions This work demonstrates that CRISPRi system can improve aconitic acid production by coordinating glycolysis and TCA cycle. This study provides insights for high-level production of the intermediate metabolites in central pathways.
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Affiliation(s)
- Qingyang Li
- School of Food Science and Engineering, South China University of Technology, Guangzhou, 510641, China
| | - Peng Zhao
- College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Hang Yin
- School of Food Science and Engineering, South China University of Technology, Guangzhou, 510641, China
| | - Zhaonan Liu
- College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Haifeng Zhao
- School of Food Science and Engineering, South China University of Technology, Guangzhou, 510641, China
| | - Pingfang Tian
- College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, 100029, China.
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29
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Hashemi A. CRISPR-Cas9/CRISPRi tools for cell factory construction in E. coli. World J Microbiol Biotechnol 2020; 36:96. [PMID: 32583135 DOI: 10.1007/s11274-020-02872-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Accepted: 06/19/2020] [Indexed: 12/26/2022]
Abstract
The innovative CRISPR-Cas based genome editing technology provides some functionality and advantages such as the high efficiency and specificity as well as ease of handling. Both aspects of the CRISPR-Cas9 system including genetic engineering and gene regulation are advantageously applicable to the construction of microbial cell factories. As one of the most extensively used cell factories, E. coli has been engineered to produce various high value-added chemical compounds such as pharmaceuticals, biochemicals, and biofuels. Therefore, to improve the production of valuable metabolites, many investigations have been performed by focusing on CRISPR-Cas- based metabolic engineering of this host. In the current review, the biology underlying CRISPR-Cas9 system was briefly explained and then the applications of CRISPR-Cas9/CRISPRi tools were considered for cell factory construction in E. coli.
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Affiliation(s)
- Atieh Hashemi
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Shahid Beheshti University of Medical Sciences, No. 2660, Vali-e-Asr Ave, Tehran, Iran.
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30
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Engineered citrate synthase alters Acetate Accumulation in Escherichia coli. Metab Eng 2020; 61:171-180. [PMID: 32569710 DOI: 10.1016/j.ymben.2020.06.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 05/24/2020] [Accepted: 06/10/2020] [Indexed: 12/15/2022]
Abstract
Metabolic engineering is used to improve titers, yields and generation rates for biochemical products in host microbes such as Escherichia coli. A wide range of biochemicals are derived from the central carbon metabolite acetyl-CoA, and the largest native drain of acetyl-CoA in most microbes including E. coli is entry into the tricarboxylic acid (TCA) cycle via citrate synthase (coded by the gltA gene). Since the pathway to any biochemical derived from acetyl-CoA must ultimately compete with citrate synthase, a reduction in citrate synthase activity should facilitate the increased formation of products derived from acetyl-CoA. To test this hypothesis, we integrated into E. coli C ΔpoxB twenty-eight citrate synthase variants having specific point mutations that were anticipated to reduce citrate synthase activity. These variants were assessed in shake flasks for growth and the production of acetate, a model product derived from acetyl-CoA. Mutations in citrate synthase at residues W260, A267 and V361 resulted in the greatest acetate yields (approximately 0.24 g/g glucose) compared to the native citrate synthase (0.05 g/g). These variants were further examined in controlled batch and continuous processes. The results provide important insights on improving the production of compounds derived from acetyl-CoA.
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Brito LF, Schultenkämper K, Passaglia LMP, Wendisch VF. CRISPR interference-based gene repression in the plant growth promoter Paenibacillus sonchi genomovar Riograndensis SBR5. Appl Microbiol Biotechnol 2020; 104:5095-5106. [PMID: 32274563 PMCID: PMC7229006 DOI: 10.1007/s00253-020-10571-6] [Citation(s) in RCA: 8] [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: 02/10/2020] [Revised: 03/11/2020] [Accepted: 03/20/2020] [Indexed: 12/16/2022]
Abstract
Gene repression using the endonucleolytically deactivated dCas9 protein and sgRNAs (CRISPR interference or CRISPRi) is a useful approach to study gene functions. Here, we established CRISPRi in Paenibacillus sonchi genomovar Riograndensis SBR5, a plant growth promoting bacterium. CRISPRi system with sgRNAs targeting SBR5 endogenous genes spo0A, yaaT and ydjJ and plasmid-borne gfpUV was constructed and analyzed. Flow cytometry analysis revealed a significant decrease of reporter protein GFPUV signal in P. sonchi strains expressing gfpUV sgRNA in comparison with non-targeting controls. CRISPRi-based repression of chromosomal genes for regulation of sporulation spo0A and yaaT decreased sporulation and increased biofilm formation in SBR5. Repression of the sorbitol catabolic gene ydjJ revealed decreased specific activity of YdjJ in crude cell extracts and reduced biomass formation from sorbitol in growth experiments. Our work on CRISPRi-based gene repression serves as basis for gene function studies of the plant growth promoter P. sonchi SBR5. To our knowledge, the present study presents the first tool for gene repression established in Paenibacillus species.Key points• CRISPRi toward gene repression was applied for the first time in Paenibacillus.• CRISPRi of spo0A and yaaT depleted spores and increased biofilms in SBR5.• CRISPRi-based ydjJ repression decreased specific activity of sorbitol dehydrogenase.
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Affiliation(s)
- Luciana F Brito
- Genetics of Prokaryotes, Faculty of Biology and CeBiTec, Bielefeld University, Bielefeld, Germany
- Department of Biotechnology and Food Science, NTNU, Norwegian University of Science and Technology, Trondheim, Norway
| | - Kerstin Schultenkämper
- Genetics of Prokaryotes, Faculty of Biology and CeBiTec, Bielefeld University, Bielefeld, Germany
| | - Luciane M P Passaglia
- Department of Genetics UFRGS, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Volker F Wendisch
- Genetics of Prokaryotes, Faculty of Biology and CeBiTec, Bielefeld University, Bielefeld, Germany.
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Flux controlling technology for central carbon metabolism for efficient microbial bio-production. Curr Opin Biotechnol 2020; 64:169-174. [PMID: 32485613 DOI: 10.1016/j.copbio.2020.04.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 01/27/2020] [Accepted: 04/20/2020] [Indexed: 11/22/2022]
Abstract
Syntheses of many commodities that are produced using microorganisms require cofactors such as ATP and NAD(P)H. Thus, optimization of the flux distribution in central carbon metabolism, which plays a key role in cofactor regeneration, is critical for enhancing the production of the target compounds. Since the intracellular and extracellular conditions change over time in the fermentation process, dynamic control of the metabolic system for maintaining the cellular state appropriately is necessary. Here, we review techniques for detecting the intracellular metabolic state with fluorescent sensors and controlling the flux of central carbon metabolism with optogenetic tools, as well as present a prospect of bio-production processes for fine-tuning the flux distribution.
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CRISPRi/dCpf1-mediated dynamic metabolic switch to enhance butenoic acid production in Escherichia coli. Appl Microbiol Biotechnol 2020; 104:5385-5393. [DOI: 10.1007/s00253-020-10610-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Revised: 03/10/2020] [Accepted: 04/05/2020] [Indexed: 10/24/2022]
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McCarty NS, Graham AE, Studená L, Ledesma-Amaro R. Multiplexed CRISPR technologies for gene editing and transcriptional regulation. Nat Commun 2020; 11:1281. [PMID: 32152313 PMCID: PMC7062760 DOI: 10.1038/s41467-020-15053-x] [Citation(s) in RCA: 226] [Impact Index Per Article: 56.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Accepted: 02/17/2020] [Indexed: 12/18/2022] Open
Abstract
Multiplexed CRISPR technologies, in which numerous gRNAs or Cas enzymes are expressed at once, have facilitated powerful biological engineering applications, vastly enhancing the scope and efficiencies of genetic editing and transcriptional regulation. In this review, we discuss multiplexed CRISPR technologies and describe methods for the assembly, expression and processing of synthetic guide RNA arrays in vivo. Applications that benefit from multiplexed CRISPR technologies, including cellular recorders, genetic circuits, biosensors, combinatorial genetic perturbations, large-scale genome engineering and the rewiring of metabolic pathways, are highlighted. We also offer a glimpse of emerging challenges and emphasize experimental considerations for future studies.
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Affiliation(s)
- Nicholas S McCarty
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Alicia E Graham
- Department of Bioengineering and Imperial College Centre for Synthetic Biology, Imperial College London, London, UK
| | - Lucie Studená
- Department of Bioengineering and Imperial College Centre for Synthetic Biology, Imperial College London, London, UK
| | - Rodrigo Ledesma-Amaro
- Department of Bioengineering and Imperial College Centre for Synthetic Biology, Imperial College London, London, UK.
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Kim B, Kim HJ, Lee SJ. Regulation of Microbial Metabolic Rates Using CRISPR Interference With Expanded PAM Sequences. Front Microbiol 2020; 11:282. [PMID: 32184769 PMCID: PMC7058998 DOI: 10.3389/fmicb.2020.00282] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 02/07/2020] [Indexed: 12/20/2022] Open
Abstract
Genome-editing CRISPR/Cas9 technology has led to the development of artificial transcriptional repressors, also known as CRISPR interference (CRISPRi). The deactivated Cas9 (dCas9) protein guided by crRNA can specifically bind to target DNA sequences, including promoters and operators, without DNA cleavage. Protospacer adjacent motif (PAM) sequence dependence may be disadvantageous in the design of target-specific CRISPRi, as the PAM sequence is essential for DNA cleavage by the CRISPR/Cas9 system. We constructed a chromosomally integrated dCas9 system (ΔaraBAD:dcas9) in Escherichia coli under the control of the L-arabinose-inducible P BAD promoter. Plasmids carrying various crRNAs with target sequences specific for the gal promoter (-10 region), and the galETK structural genes in the gal operon, were transformed into dCas9-expressing E. coli. Cellular growth and/or galactose metabolic rates were monitored in the presence or absence of gratuitous L-arabinose. D-galactose consumption and cell growth rates were partially retarded by targeting transcriptional elongation but were fully inhibited by targeting transcriptional initiation. Moreover, RT-qPCR analysis showed that CRISPRi with several modified PAM sequences can repress the transcription of target DNAs. These results indicate that cellular metabolic rates and cell growth can be controlled by targeting structural genes or regulatory regions using CRISPRi; also, a loose PAM sequence dependence can expand the DNA targets of CRISPRi.
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Affiliation(s)
- Bumjoon Kim
- Department of Systems Biotechnology, Chung-Ang University, Anseong, South Korea
| | - Hyun Ju Kim
- Department of Systems Biotechnology, Chung-Ang University, Anseong, South Korea
| | - Sang Jun Lee
- Department of Systems Biotechnology, Chung-Ang University, Anseong, South Korea
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36
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Building cell factories for the production of advanced fuels. Biochem Soc Trans 2020; 47:1701-1714. [PMID: 31803925 DOI: 10.1042/bst20190168] [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: 07/18/2019] [Revised: 11/13/2019] [Accepted: 11/15/2019] [Indexed: 12/31/2022]
Abstract
Synthetic biology-based engineering strategies are being extensively employed for microbial production of advanced fuels. Advanced fuels, being comparable in energy efficiency and properties to conventional fuels, have been increasingly explored as they can be directly incorporated into the current fuel infrastructure without the need for reconstructing the pre-existing set-up rendering them economically viable. Multiple metabolic engineering approaches have been used for rewiring microbes to improve existing or develop newly programmed cells capable of efficient fuel production. The primary challenge in using these approaches is improving the product yield for the feasibility of the commercial processes. Some of the common roadblocks towards enhanced fuel production include - limited availability of flux towards precursors and desired pathways due to presence of competing pathways, limited cofactor and energy supply in cells, the low catalytic activity of pathway enzymes, obstructed product transport, and poor tolerance of host cells for end products. Consequently, despite extensive studies on the engineering of microbial hosts, the costs of industrial-scale production of most of these heterologously produced fuel compounds are still too high. Though considerable progress has been made towards successfully producing some of these biofuels, a substantial amount of work needs to be done for improving the titers of others. In this review, we have summarized the different engineering strategies that have been successfully used for engineering pathways into commercial hosts for the production of advanced fuels and different approaches implemented for tuning host strains and pathway enzymes for scaling up production levels.
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Schultenkämper K, Brito LF, Wendisch VF. Impact of CRISPR interference on strain development in biotechnology. Biotechnol Appl Biochem 2020; 67:7-21. [DOI: 10.1002/bab.1901] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 02/13/2020] [Indexed: 12/17/2022]
Affiliation(s)
| | - Luciana F. Brito
- Department of Biotechnology and Food ScienceNTNUNorwegian University of Science and Technology Trondheim Norway
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Establishment and application of multiplexed CRISPR interference system in Bacillus licheniformis. Appl Microbiol Biotechnol 2019; 104:391-403. [PMID: 31745574 DOI: 10.1007/s00253-019-10230-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 10/22/2019] [Accepted: 10/30/2019] [Indexed: 12/14/2022]
Abstract
Bacillus licheniformis has been regarded as an outstanding microbial cell factory for the production of biochemicals and enzymes. Due to lack of genetic tools to repress gene expression, metabolic engineering and gene function elucidation are limited in this microbe. In this study, an integrated CRISPR interference (CRISPRi) system was constructed in B. licheniformis. Several endogenous genes, including yvmC, cypX, alsD, pta, ldh, and essential gene rpsC, were severed as the targets to test this CRISPRi system, and the repression efficiencies were ranged from 45.02 to 94.00%. Moreover, the multiple genes were simultaneously repressed with high efficiency using this CRISPRi system. As a case study, the genes involved in by-product synthetic and L-valine degradation pathways were selected as the silence targets to redivert metabolic flux toward L-valine synthesis. Repression of acetolactate decarboxylase (alsD) and leucine dehydrogenase (bcd) led to 90.48% and 80.09 % increases in L-valine titer, respectively. Compared with the control strain DW9i△leuA (1.47 g/L and 1.79 g/L), the L-valine titers of combinatorial strain DW9i△leuA/pHYi-alsD-bcd were increased by 1.27-fold and 2.89-fold, respectively, in flask and bioreactor. Collectively, this work provides a feasible approach for multiplex metabolic engineering and functional genome studies of B. licheniformis.
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Sander T, Wang CY, Glatter T, Link H. CRISPRi-Based Downregulation of Transcriptional Feedback Improves Growth and Metabolism of Arginine Overproducing E. coli. ACS Synth Biol 2019; 8:1983-1990. [PMID: 31429546 DOI: 10.1021/acssynbio.9b00183] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Removing transcriptional feedback regulation of metabolic pathways is a classical approach to enhance overproduction of chemicals in microbes. However, disrupting transcriptional regulation can have broad physiological consequences that decrease cellular growth and productivity. Here, we compared downregulation and deletion of the transcriptional repressor ArgR in arginine overproducing Escherichia coli. Different levels of ArgR downregulation were achieved with CRISPR interference (CRISPRi) and resulted in 2-times higher growth rates compared to deletion of ArgR, while specific arginine production was similar (∼2 mmol gDW-1 h-1). Metabolomics and proteomics data revealed that poor growth of the ArgR deletion strain was caused by a limitation of pyrimidine nucleotide biosynthesis, because a 17-fold overexpression of ornithine carbamoyltransferase (ArgI) perturbed the arginine-pyrimidine branch point. These results demonstrate that overexpression of enzymes in an engineered pathway can impair metabolism of the host, especially in the case of branch-point enzymes. Thus, balancing enzyme levels is important to optimize industrial microbes, and CRISPRi of a transcription factor is a versatile tool for this purpose.
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Affiliation(s)
- Timur Sander
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Chun Ying Wang
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Timo Glatter
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Hannes Link
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
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40
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Establishment and application of CRISPR interference to affect sporulation, hydrogen peroxide detoxification, and mannitol catabolism in the methylotrophic thermophile Bacillus methanolicus. Appl Microbiol Biotechnol 2019; 103:5879-5889. [DOI: 10.1007/s00253-019-09907-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 05/07/2019] [Accepted: 05/08/2019] [Indexed: 11/30/2022]
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41
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Jung HR, Yang SY, Moon YM, Choi TR, Song HS, Bhatia SK, Gurav R, Kim EJ, Kim BG, Yang YH. Construction of Efficient Platform Escherichia coli Strains for Polyhydroxyalkanoate Production by Engineering Branched Pathway. Polymers (Basel) 2019; 11:polym11030509. [PMID: 30960493 PMCID: PMC6473851 DOI: 10.3390/polym11030509] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 03/05/2019] [Accepted: 03/11/2019] [Indexed: 02/07/2023] Open
Abstract
Polyhydroxyalkanoate (PHA) is a potential substitute for petroleum-based plastics and can be produced by many microorganisms, including recombinant Escherichia coli. For efficient conversion of substrates and maximum PHA production, we performed multiple engineering of branched pathways in E. coli. We deleted four genes (pflb, ldhA, adhE, and fnr), which contributed to the formation of byproducts, using the CRISPR/Cas9 system and overexpressed pntAB, which catalyzes the interconversion of NADH and NADPH. The constructed strain, HR002, showed accumulation of acetyl-CoA and decreased levels of byproducts, resulting in dramatic increases in cell growth and PHA content. Thus, we demonstrated the effects of multiple engineering for redirecting carbon flux into PHA production without any concerns regarding simultaneous deletion.
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Affiliation(s)
- Hye-Rim Jung
- Department of Biological Engineering, College of Engineering, Konkuk University, 120, Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea.
| | - Su-Yeon Yang
- Department of Biological Engineering, College of Engineering, Konkuk University, 120, Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea.
| | - Yu-Mi Moon
- Department of Biological Engineering, College of Engineering, Konkuk University, 120, Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea.
| | - Tae-Rim Choi
- Department of Biological Engineering, College of Engineering, Konkuk University, 120, Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea.
| | - Hun-Suk Song
- Department of Biological Engineering, College of Engineering, Konkuk University, 120, Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea.
| | - Shashi Kant Bhatia
- Department of Biological Engineering, College of Engineering, Konkuk University, 120, Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea.
- Institute for Ubiquitous Information Technology and Applications (CBRU), Konkuk University, Seoul 05029, Korea.
| | - Ranjit Gurav
- Department of Biological Engineering, College of Engineering, Konkuk University, 120, Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea.
| | - Eun-Jung Kim
- Institute of Molecular Biology and Genetics, Seoul National University, Seoul 08826, Korea.
| | - Byung-Gee Kim
- Institute of Molecular Biology and Genetics, Seoul National University, Seoul 08826, Korea.
- School of Chemical and Biological Engineering, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul 08826, Korea.
| | - Yung-Hun Yang
- Department of Biological Engineering, College of Engineering, Konkuk University, 120, Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea.
- Institute for Ubiquitous Information Technology and Applications (CBRU), Konkuk University, Seoul 05029, Korea.
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42
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Fernandes LGV, Guaman LP, Vasconcellos SA, Heinemann MB, Picardeau M, Nascimento ALTO. Gene silencing based on RNA-guided catalytically inactive Cas9 (dCas9): a new tool for genetic engineering in Leptospira. Sci Rep 2019; 9:1839. [PMID: 30755626 PMCID: PMC6372684 DOI: 10.1038/s41598-018-37949-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 12/10/2018] [Indexed: 12/15/2022] Open
Abstract
Leptospirosis is a worldwide zoonosis caused by pathogenic bacteria of the genus Leptospira, which also includes free-living saprophyte strains. Many aspects of leptospiral basic biology and virulence mechanisms remain unexplored mainly due to the lack of effective genetic tools available for these bacteria. Recently, the type II CRISPR/Cas system from Streptococcus pyogenes has been widely used as an efficient genome engineering tool in bacteria by inducing double-strand breaks (DSBs) in the desired genomic targets caused by an RNA-guided DNA endonuclease called Cas9, and the DSB repair associated machinery. In the present work, plasmids expressing heterologous S. pyogenes Cas9 in L. biflexa cells were generated, and the enzyme could be expressed with no apparent toxicity to leptospiral cells. However, L. biflexa cells were unable to repair RNA-guided Cas9-induced DSBs. Thus, we used a catalytically dead Cas9 (dCas9) to obtain gene silencing rather than disruption, in a strategy called CRISPR interference (CRISPRi). We demonstrated complete gene silencing in L. biflexa cells when both dCas9 and single-guide RNA (sgRNA) targeting the coding strand of the β-galactosidase gene were expressed simultaneously. Furthermore, when the system was applied for silencing the dnaK gene, no colonies were recovered, indicating that DnaK protein is essential in Leptospira. In addition, flagellar motor switch FliG gene silencing resulted in reduced bacterial motility. To the best of our knowledge, this is the first work applying the CRISPRi system in Leptospira and spirochetes in general, expanding the tools available for understanding leptospiral biology.
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Affiliation(s)
- L G V Fernandes
- Laboratório Especial de Desenvolvimento de Vacinas, Instituto Butantan, Avenida Vital Brasil, 1500, 05503-900, Sao Paulo, SP, Brazil.
| | - L P Guaman
- Universidad Tecnológica Equinoccial, Centro de Investigación Biomédica, Facultad de Ciencias de la Salud Eugenio Espejo, Avenida Mariscal Sucre y Mariana de Jesús. Campus Occidental, 170105, Quito, Ecuador
| | - S A Vasconcellos
- Laboratório de Zoonoses Bacterianas do VPS, Faculdade de Medicina Veterinária e Zootecnia, USP, Avenida Prof. Dr. Orlando Marques de Paiva, 87, 05508-270, Sao Paulo, SP, Brazil
| | - Marcos B Heinemann
- Laboratório de Zoonoses Bacterianas do VPS, Faculdade de Medicina Veterinária e Zootecnia, USP, Avenida Prof. Dr. Orlando Marques de Paiva, 87, 05508-270, Sao Paulo, SP, Brazil
| | - M Picardeau
- Institut Pasteur, Biology of Spirochetes Unit, 25 rue du Dr Roux, 75723, Paris, France
| | - A L T O Nascimento
- Laboratório Especial de Desenvolvimento de Vacinas, Instituto Butantan, Avenida Vital Brasil, 1500, 05503-900, Sao Paulo, SP, Brazil.
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Sung L, Wu M, Lin M, Hsu M, Truong VA, Shen C, Tu Y, Hwang K, Tu A, Chang Y, Hu Y. Combining orthogonal CRISPR and CRISPRi systems for genome engineering and metabolic pathway modulation in
Escherichia coli. Biotechnol Bioeng 2019; 116:1066-1079. [DOI: 10.1002/bit.26915] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2018] [Revised: 12/07/2018] [Accepted: 01/06/2019] [Indexed: 12/26/2022]
Affiliation(s)
- Li‐Yu Sung
- Department of Chemical EngineeringNational Tsing Hua UniversityHsinchu Taiwan
| | - Meng‐Ying Wu
- Department of Chemical EngineeringNational Tsing Hua UniversityHsinchu Taiwan
| | - Mei‐Wei Lin
- Department of Chemical EngineeringNational Tsing Hua UniversityHsinchu Taiwan
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research InstituteHsinchu Taiwan
| | - Mu‐Nung Hsu
- Department of Chemical EngineeringNational Tsing Hua UniversityHsinchu Taiwan
| | - Vu Anh Truong
- Department of Chemical EngineeringNational Tsing Hua UniversityHsinchu Taiwan
| | - Chih‐Che Shen
- Department of Chemical EngineeringNational Tsing Hua UniversityHsinchu Taiwan
| | - Yi Tu
- Department of Life ScienceNational Taiwan UniversityTaipei Taiwan
| | | | - An‐Pang Tu
- Chang Chun Petrochemical GroupTaipei Taiwan
| | - Yu‐Han Chang
- College of Medicine, Chang Gung UniversityTaoyuan Taiwan
- Department of Orthopaedic SurgeryChang Gung Memorial HospitalLinkou Taiwan
| | - Yu‐Chen Hu
- Department of Chemical EngineeringNational Tsing Hua UniversityHsinchu Taiwan
- Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua UniversityHsinchu Taiwan
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44
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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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45
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Yao R, Liu D, Jia X, Zheng Y, Liu W, Xiao Y. CRISPR-Cas9/Cas12a biotechnology and application in bacteria. Synth Syst Biotechnol 2018; 3:135-149. [PMID: 30345399 PMCID: PMC6190536 DOI: 10.1016/j.synbio.2018.09.004] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 09/24/2018] [Accepted: 09/25/2018] [Indexed: 12/26/2022] Open
Abstract
CRISPR-Cas technologies have greatly reshaped the biology field. In this review, we discuss the CRISPR-Cas with a particular focus on the associated technologies and applications of CRISPR-Cas9 and CRISPR-Cas12a, which have been most widely studied and used. We discuss the biological mechanisms of CRISPR-Cas as immune defense systems, recently-discovered anti-CRISPR-Cas systems, and the emerging Cas variants (such as xCas9 and Cas13) with unique characteristics. Then, we highlight various CRISPR-Cas biotechnologies, including nuclease-dependent genome editing, CRISPR gene regulation (including CRISPR interference/activation), DNA/RNA base editing, and nucleic acid detection. Last, we summarize up-to-date applications of the biotechnologies for synthetic biology and metabolic engineering in various bacterial species.
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Affiliation(s)
- Ruilian Yao
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Di Liu
- Department of Biomass Science and Conversion Technology, Sandia National Laboratories, Livermore, CA 94551, USA
| | - Xiao Jia
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Yuan Zheng
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Wei Liu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Yi Xiao
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
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46
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Arazoe T, Kondo A, Nishida K. Targeted Nucleotide Editing Technologies for Microbial Metabolic Engineering. Biotechnol J 2018; 13:e1700596. [PMID: 29862665 DOI: 10.1002/biot.201700596] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 05/15/2018] [Indexed: 12/31/2022]
Abstract
Since the emergence of programmable RNA-guided nucleases based on clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) systems, genome editing technologies have become a simplified and versatile tool for genome editing in various organisms and cell types. Although genome editing enables efficient genome manipulations, such as gene disruptions, gene knockins, and chromosomal translocations via DNA double-strand break (DSB) repair in eukaryotes, DSBs induced by the CRISPR/Cas system are lethal or severely toxic to many microorganisms. Therefore, in many prokaryotes, including industrially useful microbes, the CRISPR/Cas system is often used as a negative selection component in combination with recombineering or other related strategies. Novel and revolutionary technologies have been recently developed to re-write targeted nucleotides (C:G to T:A and A:T to G:C) without DSBs and donor DNA templates. These technologies rely on the recruitment of deaminases at specific target loci using the nuclease-deficient CRISPR/Cas system. Here, the authors review and compare CRISPR-based genome editing, current base editing platforms and their spectra. The authors discuss how these technologies can be applied in various aspects of microbial metabolic engineering to overcome barriers to cellular regulation in prokaryotes.
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Affiliation(s)
- Takayuki Arazoe
- Department of Applied Biological Science, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba, 278-8510, Japan
| | - Akihiko Kondo
- Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, Hyogo, 657-8501, Japan
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, Hyogo, 657-8501, Japan
| | - Keiji Nishida
- Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, Hyogo, 657-8501, Japan
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Tarasava K, Oh EJ, Eckert CA, Gill RT. CRISPR-Enabled Tools for Engineering Microbial Genomes and Phenotypes. Biotechnol J 2018; 13:e1700586. [DOI: 10.1002/biot.201700586] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Revised: 05/09/2018] [Indexed: 12/26/2022]
Affiliation(s)
- Katia Tarasava
- Chemical and Biological Engineering, University of Colorado; Boulder CO USA
- Renewable and Sustainable Energy Institute, University of Colorado; Boulder CO USA
| | - Eun Joong Oh
- Renewable and Sustainable Energy Institute, University of Colorado; Boulder CO USA
| | - Carrie A. Eckert
- Renewable and Sustainable Energy Institute, University of Colorado; Boulder CO USA
- Biosciences Center, National Renewable Energy Laboratory; Golden CO USA
| | - Ryan T. Gill
- Chemical and Biological Engineering, University of Colorado; Boulder CO USA
- Renewable and Sustainable Energy Institute, University of Colorado; Boulder CO USA
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48
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Zhao Y, Li L, Zheng G, Jiang W, Deng Z, Wang Z, Lu Y. CRISPR/dCas9-Mediated Multiplex Gene Repression in Streptomyces. Biotechnol J 2018; 13:e1800121. [PMID: 29862648 DOI: 10.1002/biot.201800121] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2018] [Revised: 05/28/2018] [Indexed: 12/13/2022]
Abstract
Streptomycetes are Gram-positive bacteria with the capacity to produce copious bioactive secondary metabolites, which are the main source of medically and industrially relevant drugs. However, genetic manipulation of Streptomyces strains is much more difficult than other model microorganisms like Escherichia coli and Saccharomyces cerevisiae. Recently, CRISPR/Cas9 or dCas9-mediated genetic manipulation tools have been developed and facilitated Streptomyces genome editing. However, till now, CRISPR/dCas9-based interference system (CRISPRi) is only designed to repress single gene expression. Herein, the authors developed a novel CRISPRi system for multiplex gene repression in the model strain Streptomyces coelicolor. In this system, the integrative plasmid pSET152 is used as the backbone for the expression of the dCas9/sgRNA complex and both dCas9 and sgRNAs are designed to be under the control of constitutive promoters. Using the integrative CRISPRi system, the authors achieved efficient repression of multiple genes simultaneously; the mRNA levels of four targets are reduced to 2-32% of the control. Furthermore, it is successfully employed for functional gene screening, and an orphan response regulator (RR) (encoded by SCO2013) containing an RNA-binding ANTAR domain is identified being involved in bacterial growth. Collectively, this integrative CRISPRi system is very effective for multiplex gene repression in S. coelicolor, which could be extended to other Streptomyces strains for functional gene screening as well as for metabolic engineering.
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Affiliation(s)
- Yawei Zhao
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200030, China.,College of Life and Environmental Science, Shanghai Normal University, Shanghai 200234, China
| | - Lei Li
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences (CAS), Shanghai 200032, China
| | - Guosong Zheng
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences (CAS), Shanghai 200032, China
| | - Weihong Jiang
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences (CAS), Shanghai 200032, China
| | - Zixin Deng
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200030, China
| | - Zhijun Wang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200030, China
| | - Yinhua Lu
- College of Life and Environmental Science, Shanghai Normal University, Shanghai 200234, China
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49
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Zhang B, Yu M, Wei WP, Ye BC. Optimization of ʟ-ornithine production in recombinant Corynebacterium glutamicum S9114 by cg3035 overexpression and manipulating the central metabolic pathway. Microb Cell Fact 2018; 17:91. [PMID: 29898721 PMCID: PMC6001011 DOI: 10.1186/s12934-018-0940-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 06/08/2018] [Indexed: 11/25/2022] Open
Abstract
Background ʟ-Ornithine is an important amino acid with broad applications in pharmaceutical and food industries. Despite lagging ʟ-ornithine productivity and cost reduction, microbial fermentation is a promising route for sustainable ʟ-ornithine production and thus development of robust microbial strains with high stability and productivity is essential. Results Previously, we systematically developed a new strain, SO1 originate from Corynebacterium glutamicum S9114, for ʟ-ornithine production. In this work, overexpression of cg3035 encoding N-acetylglutamate synthase (NAGS) using a plasmid or by inserting a strong Ptac promoter into the chromosome was found to increase ʟ-ornithine production in the engineered C. glutamicum SO1. The genome-based cg3035 modulated strain was further engineered by attenuating the expression of pta and cat, inserting a strong Peftu promoter in the upstream region of glycolytic enzymes such as pfkA, gap, and pyk, and redirecting carbon flux to the pentose phosphate pathway. The final strain with all the exploratory metabolic engineering manipulations produced 32.3 g/L of ʟ-ornithine, a yield of 0.395 g ornithine per g glucose, which was 35.7% higher than that produced by the original strain (23.8 g/L). Conclusion These results clearly demonstrated that enhancing the expression of NAGS promoted ʟ-ornithine production and provide a promising alternative systematic blueprint for developing ʟ-ornithine-producing C. glutamicum strains. Electronic supplementary material The online version of this article (10.1186/s12934-018-0940-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Bin Zhang
- Laboratory of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China
| | - Miao Yu
- Laboratory of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China
| | - Wen-Ping Wei
- Laboratory of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China
| | - Bang-Ce Ye
- Laboratory of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China. .,Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou, 310014, Zhejiang, China.
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50
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Cho S, Choe D, Lee E, Kim SC, Palsson B, Cho BK. High-Level dCas9 Expression Induces Abnormal Cell Morphology in Escherichia coli. ACS Synth Biol 2018; 7:1085-1094. [PMID: 29544049 DOI: 10.1021/acssynbio.7b00462] [Citation(s) in RCA: 109] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Along with functional advances in the use of CRISPR/Cas9 for genome editing, endonuclease-deficient Cas9 (dCas9) has provided a versatile molecular tool for exploring gene functions. In principle, differences in cell phenotypes that result from the RNA-guided modulation of transcription levels by dCas9 are critical for inferring with gene function; however, the effect of intracellular dCas9 expression on bacterial morphology has not been systematically elucidated. Here, we observed unexpected morphological changes in Escherichia coli mediated by dCas9, which were then characterized using RNA sequencing (RNA-Seq) and chromatin immunoprecipitation sequencing (ChIP-Seq). Growth rates were severely decreased, to approximately 50% of those of wild type cells, depending on the expression levels of dCas9. Cell shape was changed to abnormal filamentous morphology, indicating that dCas9 affects bacterial cell division. RNA-Seq revealed that 574 genes were differentially transcribed in the presence of high expression levels of dCas9. Genes associated with cell division were upregulated, which was consistent with the observed atypical morphologies. In contrast, 221 genes were downregulated, and these mostly encoded proteins located in the cell membrane. Further, ChIP-Seq results showed that dCas9 directly binds upstream of 37 genes without single-guide RNA, including fimA, which encodes bacterial fimbriae. These results support the fact that dCas9 has critical effects on cell division as well as inner and outer membrane structure. Thus, to precisely understand gene functions using dCas9-driven transcriptional modulation, the regulation of intracellular levels of dCas9 is pivotal to avoid unexpected morphological changes in E. coli.
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Affiliation(s)
- Suhyung Cho
- Department of Biological Sciences and KI for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea
| | - Donghui Choe
- Department of Biological Sciences and KI for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea
| | - Eunju Lee
- Department of Biological Sciences and KI for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea
| | - Sun Chang Kim
- Department of Biological Sciences and KI for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea
- Intelligent Synthetic Biology Center, Daejeon 305-701, Republic of Korea
| | - Bernhard Palsson
- Department of Bioengineering, University of California San Diego, La Jolla, California 92122, United States
- Department of Pediatrics, University of California San Diego, La Jolla, California 92122, United States
| | - Byung-Kwan Cho
- Department of Biological Sciences and KI for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea
- Intelligent Synthetic Biology Center, Daejeon 305-701, Republic of Korea
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