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Kim G, Kim HJ, Kim K, Kim HJ, Yang J, Seo SW. Tunable translation-level CRISPR interference by dCas13 and engineered gRNA in bacteria. Nat Commun 2024; 15:5319. [PMID: 38909033 PMCID: PMC11193725 DOI: 10.1038/s41467-024-49642-x] [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: 11/15/2023] [Accepted: 06/13/2024] [Indexed: 06/24/2024] Open
Abstract
Although CRISPR-dCas13, the RNA-guided RNA-binding protein, was recently exploited as a translation-level gene expression modulator, it has still been difficult to precisely control the level due to the lack of detailed characterization. Here, we develop a synthetic tunable translation-level CRISPR interference (Tl-CRISPRi) system based on the engineered guide RNAs that enable precise and predictable down-regulation of mRNA translation. First, we optimize the Tl-CRISPRi system for specific and multiplexed repression of genes at the translation level. We also show that the Tl-CRISPRi system is more suitable for independently regulating each gene in a polycistronic operon than the transcription-level CRISPRi (Tx-CRISPRi) system. We further engineer the handle structure of guide RNA for tunable and predictable repression of various genes in Escherichia coli and Vibrio natriegens. This tunable Tl-CRISPRi system is applied to increase the production of 3-hydroxypropionic acid (3-HP) by 14.2-fold via redirecting the metabolic flux, indicating the usefulness of this system for the flux optimization in the microbial cell factories based on the RNA-targeting machinery.
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Affiliation(s)
- Giho Kim
- School of Chemical and Biological Engineering, Seoul National University, Seoul, Republic of Korea
| | - Ho Joon Kim
- School of Chemical and Biological Engineering, Seoul National University, Seoul, Republic of Korea
| | - Keonwoo Kim
- School of Chemical and Biological Engineering, Seoul National University, Seoul, Republic of Korea
| | - Hyeon Jin Kim
- Interdisciplinary Program in Bioengineering, Seoul National University, Seoul, South Korea
| | - Jina Yang
- Department of Chemical Engineering, Jeju National University, Jeju-si, South Korea
| | - Sang Woo Seo
- School of Chemical and Biological Engineering, Seoul National University, Seoul, Republic of Korea.
- Interdisciplinary Program in Bioengineering, Seoul National University, Seoul, South Korea.
- Institute of Chemical Processes, Seoul National University, Seoul, South Korea.
- Bio-MAX Institute, Seoul National University, Seoul, South Korea.
- Institute of Bio Engineering, Seoul National University, Seoul, South Korea.
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2
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Jung YJ, Park KH, Jang TY, Yoo SM. Gene expression regulation by modulating Hfq expression in coordination with tailor-made sRNA-based knockdown in Escherichia coli. J Biotechnol 2024; 388:1-10. [PMID: 38616040 DOI: 10.1016/j.jbiotec.2024.04.007] [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: 02/26/2024] [Revised: 04/04/2024] [Accepted: 04/11/2024] [Indexed: 04/16/2024]
Abstract
The tailor-made synthetic sRNA-based gene expression knockdown system has demonstrated its efficacy in achieving pathway balancing in microbes, facilitating precise target gene repression and fine-tuned control of gene expression. This system operates under a competitive mode of gene regulation, wherein the tailor-made synthetic sRNA shares the intrinsic intracellular Hfq protein with other RNAs. The limited intracellular Hfq amount has the potential to become a constraining factor in the post-transcription regulation of sRNAs. To enhance the efficiency of the tailor-made sRNA gene expression regulation platform, we introduced an Hfq expression level modulation-coordinated sRNA-based gene knockdown system. This system comprises tailor-made sRNA expression cassettes that produce varying Hfq expression levels using different strength promoters. Modulating the expression levels of Hfq significantly improved the repressing capacity of sRNA, as evidenced by evaluations with four fluorescence proteins. In order to validate the practical application of this system, we applied the Hfq-modulated sRNA-based gene knockdown cassette to Escherichia coli strains producing 5-aminolevulinic acid and L-tyrosine. Diversifying the expression levels of metabolic enzymes through this cassette resulted in substantial increases of 74.6% in 5-aminolevulinic acid and 144% in L-tyrosine production. Tailor-made synthetic sRNA-based gene expression knockdown system, coupled with Hfq copy modulation, exhibits potential for optimizing metabolic fluxes through biosynthetic pathways, thereby enhancing the production yields of bioproducts.
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Affiliation(s)
- Yu Jung Jung
- School of Integrative Engineering, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 06974, Republic of Korea
| | - Keun Ha Park
- School of Integrative Engineering, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 06974, Republic of Korea
| | - Tae Yeong Jang
- School of Integrative Engineering, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 06974, Republic of Korea
| | - Seung Min Yoo
- School of Integrative Engineering, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 06974, Republic of Korea.
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3
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Stibelman AY, Sariles AY, Takahashi MK. Beyond membrane permeability: A role for the small RNA MicF in regulation of chromosome replication and partitioning. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.22.590647. [PMID: 38712278 PMCID: PMC11071386 DOI: 10.1101/2024.04.22.590647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Small regulatory RNAs (sRNA) have been shown to play a large role in the management of stress responses in Escherichia coli and other bacteria. sRNAs act post-transcriptionally on target mRNA through an imperfect base pairing mechanism to regulate downstream protein expression. The imperfect base pairing allows a single sRNA to bind and regulate a variety mRNA targets which can form intricate regulatory networks that connect different physiological processes for the cell's response. Upon exposure to antimicrobials and superoxide generating agents, the MicF sRNA in E. coli has been shown to regulate a small set of genes involved in the management of membrane permeability. Currently, it is unknown whether MicF acts on other processes to mediate the response to these agents. Using an sRNA interaction prediction tool, we identified genes in E. coli that are potentially regulated by MicF. Through subsequent analysis using a sfGFP-based reporter-gene fusion, we have validated two novel targets of MicF regulation: SeqA, a negative modulator of DNA replication, and ObgE, a GTPase crucial for chromosome partitioning. Importantly, the interaction between MicF and these target mRNAs is contingent upon the presence of the RNA chaperone protein, Hfq. Furthermore, our findings affirm the role of MicF's conserved 5' seed pairing region in initiating these regulatory interactions. Our study suggests that, beyond its established role in membrane permeability management, MicF exerts control over chromosome dynamics in response to distinct environmental cues, implicating a more multifaceted regulatory function in bacterial stress adaptation.
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4
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Zhang Y, Wang X, Odesanmi C, Hu Q, Li D, Tang Y, Liu Z, Mi J, Liu S, Wen T. Model-guided metabolic rewiring to bypass pyruvate oxidation for pyruvate derivative synthesis by minimizing carbon loss. mSystems 2024; 9:e0083923. [PMID: 38315666 PMCID: PMC10949502 DOI: 10.1128/msystems.00839-23] [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: 08/09/2023] [Accepted: 01/08/2024] [Indexed: 02/07/2024] Open
Abstract
Engineering microbial hosts to synthesize pyruvate derivatives depends on blocking pyruvate oxidation, thereby causing severe growth defects in aerobic glucose-based bioprocesses. To decouple pyruvate metabolism from cell growth to improve pyruvate availability, a genome-scale metabolic model combined with constraint-based flux balance analysis, geometric flux balance analysis, and flux variable analysis was used to identify genetic targets for strain design. Using translation elements from a ~3,000 cistronic library to modulate fxpK expression in a bicistronic cassette, a bifido shunt pathway was introduced to generate three molecules of non-pyruvate-derived acetyl-CoA from one molecule of glucose, bypassing pyruvate oxidation and carbon dioxide generation. The dynamic control of flux distribution by T7 RNAP-mediated synthetic small RNA decoupled pyruvate catabolism from cell growth. Adaptive laboratory evolution and multi-omics analysis revealed that a mutated isocitrate dehydrogenase functioned as a metabolic switch to activate the glyoxylate shunt as the only C4 anaplerotic pathway to generate malate from two molecules of acetyl-CoA input and bypass two decarboxylation reactions in the tricarboxylic acid cycle. A chassis strain for pyruvate derivative synthesis was constructed to reduce carbon loss by using the glyoxylate shunt as the only C4 anaplerotic pathway and the bifido shunt as a non-pyruvate-derived acetyl-CoA synthetic pathway and produced 22.46, 27.62, and 6.28 g/L of l-leucine, l-alanine, and l-valine by a controlled small RNA switch, respectively. Our study establishes a novel metabolic pattern of glucose-grown bacteria to minimize carbon loss under aerobic conditions and provides valuable insights into cell design for manufacturing pyruvate-derived products.IMPORTANCEBio-manufacturing from biomass-derived carbon sources using microbes as a cell factory provides an eco-friendly alternative to petrochemical-based processes. Pyruvate serves as a crucial building block for the biosynthesis of industrial chemicals; however, it is different to improve pyruvate availability in vivo due to the coupling of pyruvate-derived acetyl-CoA with microbial growth and energy metabolism via the oxidative tricarboxylic acid cycle. A genome-scale metabolic model combined with three algorithm analyses was used for strain design. Carbon metabolism was reprogrammed using two genetic control tools to fine-tune gene expression. Adaptive laboratory evolution and multi-omics analysis screened the growth-related regulatory targets beyond rational design. A novel metabolic pattern of glucose-grown bacteria is established to maintain growth fitness and minimize carbon loss under aerobic conditions for the synthesis of pyruvate-derived products. This study provides valuable insights into the design of a microbial cell factory for synthetic biology to produce industrial bio-products of interest.
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Affiliation(s)
- Yun Zhang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Xueliang Wang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Christianah Odesanmi
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Qitiao Hu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Dandan Li
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Yuan Tang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Zhe Liu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Jie Mi
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Shuwen Liu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Tingyi Wen
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
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Wang L, Hou J, Yang K, Yu H, Zhang B, Liu Z, Zheng Y. Development of synthetic small regulatory RNA for Rhodococcus erythropolis. Biotechnol J 2024; 19:e2400022. [PMID: 38528342 DOI: 10.1002/biot.202400022] [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: 01/09/2024] [Revised: 02/21/2024] [Accepted: 02/29/2024] [Indexed: 03/27/2024]
Abstract
Rhodococci have been regarded as ideal chassis for biotransformation, biodegradation, and biosynthesis for their unique environmental persistence and robustness. However, most species of Rhodococcus are still difficult to metabolically engineer due to the lack of genetic tools and techniques. In this study, synthetic sRNA strategy was exploited for gene repression in R. erythropolis XP. The synthetic sRNA based on the RhlS scaffold from Pseudomonas aeruginosa functions better in repressing sfgfp expression than those based on E. coli MicC, SgrS, and P. aeruginosa PrrF1-2 scaffold. The RhlS-based sRNAs were applied to study the influence of sulfur metabolism on biodesulfurization (BDS) efficiency in R. erythropolis XP and successfully identified two genes involved in sulfur metabolism that affect the BDS efficiency significantly. The RhlS-based synthetic sRNAs show promise in the metabolic engineering of Rhodococcus and promote the industrial applications of Rhodococcus in environmental remediation and biosynthesis.
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Affiliation(s)
- Lijuan Wang
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang, P.R. China
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, P.R. China
| | - Jie Hou
- School of Life Sciences and Medicine, Shandong University of Technology, Zibo, P.R. China
| | - Kun Yang
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang, P.R. China
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, P.R. China
| | - Haonan Yu
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang, P.R. China
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, P.R. China
| | - Bo Zhang
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang, P.R. China
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, P.R. China
| | - Zhiqiang Liu
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang, P.R. China
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, P.R. China
| | - Yuguo Zheng
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang, P.R. China
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, P.R. China
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6
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Velazquez Sanchez AK, Klopprogge B, Zimmermann KH, Ignatova Z. Tailored Synthetic sRNAs Dynamically Tune Multilayer Genetic Circuits. ACS Synth Biol 2023; 12:2524-2535. [PMID: 37595156 DOI: 10.1021/acssynbio.2c00614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/20/2023]
Abstract
Predictable and controllable tuning of genetic circuits to regulate gene expression, including modulation of existing circuits or constructs without the need for redesign or rebuilding, is a persistent challenge in synthetic biology. Here, we propose rationally designed new small RNAs (sRNAs) that dynamically modulate gene expression of genetic circuits with a broad range (high, medium, and low) of repression. We designed multiple multilayer genetic circuits in which the variable effector element is a transcription factor (TF) controlling downstream the production of a reporter protein. The sRNAs target TFs instead of a reporter gene, and harnessing the intrinsic RNA-interference pathway in E. coli allowed for a wide range of expression modulation of the reporter protein, including the most difficult to achieve dynamic switch to an OFF state. The synthetic sRNAs are expressed independently of the circuit(s), thus allowing for repression without modifying the circuit itself. Our work provides a frame for achieving independent modulation of gene expression and dynamic and modular control of the multilayer genetic circuits by only including an independent control circuit expressing synthetic sRNAs, without altering the structure of existing genetic circuits.
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Affiliation(s)
- Ana K Velazquez Sanchez
- Biochemistry and Molecular Biology, Department of Chemistry, University of Hamburg, 20146 Hamburg, Germany
| | - Bjarne Klopprogge
- Biochemistry and Molecular Biology, Department of Chemistry, University of Hamburg, 20146 Hamburg, Germany
| | - Karl-Heinz Zimmermann
- Algebraic Engineering, Institute of Embedded Systems, Hamburg University of Technology, 21073 Hamburg, Germany
| | - Zoya Ignatova
- Biochemistry and Molecular Biology, Department of Chemistry, University of Hamburg, 20146 Hamburg, Germany
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7
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Wang X, N MPA, Jeon HJ, He J, Lim HM. Identification of a Rho-Dependent Termination Site In Vivo Using Synthetic Small RNA. Microbiol Spectr 2023; 11:e0395022. [PMID: 36651730 PMCID: PMC9927376 DOI: 10.1128/spectrum.03950-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 01/02/2023] [Indexed: 01/19/2023] Open
Abstract
Rho promotes Rho-dependent termination (RDT) at the Rho-dependent terminator, producing a variable-length region without secondary structure at the 3' end of mRNA. Determining the exact RDT site in vivo is challenging, because the 3' end of mRNA is rapidly removed after RDT by 3'-to-5' exonuclease processing. Here, we applied synthetic small RNA (sysRNA) to identify the RDT region in vivo by exploiting its complementary base-pairing ability to target mRNA. Through the combined analyses of rapid amplification of cDNA 3' ends, primer extension, and capillary electrophoresis, we could precisely map and quantify mRNA 3' ends. We found that complementary double-stranded RNA (dsRNA) formed between sysRNA and mRNA was efficiently cleaved by RNase III in the middle of the dsRNA region. The formation of dsRNA appeared to protect the cleaved RNA 3' ends from rapid degradation by 3'-to-5' exonuclease, thereby stabilizing the mRNA 3' end. We further verified that the signal intensity at the 3' end was positively correlated with the amount of mRNA. By constructing a series of sysRNAs with close target sites and comparing the difference in signal intensity at the 3' end of wild-type and Rho-impaired strains, we finally identified a region of increased mRNA expression within the 21-bp range, which was determined as the RDT region. Our results demonstrated the ability to use sysRNA as a novel tool to identify RDT regions in vivo and expand the range of applications of sysRNA. IMPORTANCE sysRNA, which was formerly widely employed, has steadily lost popularity as more novel techniques for suppressing gene expression come into existence because of issues such as unstable inhibition effect and low inhibition efficiency. However, it remains an interesting topic as a regulatory tool due to its ease of design and low metabolic burden on cells. Here, for the first time, we discovered a new method to identify RDT regions in vivo using sysRNA. This new feature is important because since the discovery of the Rho protein in 1969, specific identification of RDT sites in vivo has been difficult due to the rapid processing of RNA 3' ends by exonucleases, and sysRNA might provide a new approach to address this challenge.
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Affiliation(s)
- Xun Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, People’s Republic of China
| | - Monford Paul Abishek N
- Department of Biological Sciences, College of Biological Sciences and Biotechnology, Chungnam National University, Daejeon, Republic of Korea
| | - Heung Jin Jeon
- Department of Biological Sciences, College of Biological Sciences and Biotechnology, Chungnam National University, Daejeon, Republic of Korea
- Infection Control Convergence Research Center, Chungnam National University College of Medicine, Daejeon, Republic of Korea
| | - Jin He
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, People’s Republic of China
| | - Heon M. Lim
- Department of Biological Sciences, College of Biological Sciences and Biotechnology, Chungnam National University, Daejeon, Republic of Korea
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8
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Engineering Microorganisms to Produce Bio-Based Monomers: Progress and Challenges. FERMENTATION-BASEL 2023. [DOI: 10.3390/fermentation9020137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Bioplastics are polymers made from sustainable bio-based feedstocks. While the potential of producing bio-based monomers in microbes has been investigated for decades, their economic feasibility is still unsatisfactory compared with petroleum-derived methods. To improve the overall synthetic efficiency of microbial cell factories, three main strategies were summarized in this review: firstly, implementing approaches to improve the microbial utilization ability of cheap and abundant substrates; secondly, developing methods at enzymes, pathway, and cellular levels to enhance microbial production performance; thirdly, building technologies to enhance microbial pH, osmotic, and metabolites stress tolerance. Moreover, the challenges of, and some perspectives on, exploiting microorganisms as efficient cell factories for producing bio-based monomers are also discussed.
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9
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Wang Y, Yin G, Weng H, Zhang L, Du G, Chen J, Kang Z. Gene knockdown by structure defined single-stem loop small non-coding RNAs with programmable regulatory activities. Synth Syst Biotechnol 2022; 8:86-96. [PMID: 36582457 PMCID: PMC9761848 DOI: 10.1016/j.synbio.2022.11.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 11/22/2022] [Accepted: 11/22/2022] [Indexed: 12/02/2022] Open
Abstract
Gene regulation by trans-acting small RNAs (sRNAs) has considerable advantages over other gene regulation strategies. However, synthetic sRNAs mainly take natural sRNAs (MicC or SgrS) as backbones and comprise three functional elements folding into two or more stem-loop structures: an mRNA base pairing region, an Hfq-binding structure, and a rho-independent terminator. Due to limited numbers of natural sRNAs and complicated backbone structures, synthetic sRNAs suffer from low activity programmability and poor structural modularity. Moreover, natural sRNA backbone sequences may increase the possibility of unwanted recombination. Here, we present a bottom-up approach for creating structure defined single-stem loop small non-coding RNAs (ssl-sRNAs), which contain a standardized scaffold of a 7 bp-stem-4 nt-loop-polyU-tail and a 24 nt basing pairing region covering the first eight codons. Particularly, ssl-sRNA requires no independent Hfq-binding structure, as the polyU tail fulfills the roles of binding Hfq. A thermodynamic-based scoring model and a web server sslRNAD (http://www.kangzlab.cn/) were developed for automated design of ssl-sRNAs with well-defined structures and programmable activities. ssl-sRNAs displayed weak polar effects when regulating polycistronic mRNAs. The ssl-sRNA designed by sslRNAD showed regulatory activities in both Escherichia coli and Bacillus subtilis. A streamlined workflow was developed for the construction of customized ssl-sRNA and ssl-sRNA libraries. As examples, the E. coli cell morphology was easily modified and new target genes of ergothioneine biosynthesis were quickly identified with ssl-sRNAs. ssl-sRNA and its designer sslRNAD enable researchers to rapidly design sRNAs for knocking down target genes.
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Affiliation(s)
- Yang Wang
- The Science Center for Future Foods, Jiangnan University, Wuxi, 214122, China,The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China,The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China
| | - Guobin Yin
- The Science Center for Future Foods, Jiangnan University, Wuxi, 214122, China,The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Huanjiao Weng
- The Science Center for Future Foods, Jiangnan University, Wuxi, 214122, China,The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Luyao Zhang
- The Science Center for Future Foods, Jiangnan University, Wuxi, 214122, China
| | - Guocheng Du
- The Science Center for Future Foods, Jiangnan University, Wuxi, 214122, China,The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China,The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China
| | - Jian Chen
- The Science Center for Future Foods, Jiangnan University, Wuxi, 214122, China,The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China,The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China
| | - Zhen Kang
- The Science Center for Future Foods, Jiangnan University, Wuxi, 214122, China,The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China,The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China,Corresponding author. The Science Center for Future Foods, Jiangnan University, Wuxi, 214122, China.
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10
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Wang LJ, Jiang XR, Hou J, Wang CH, Chen GQ. Engineering Halomonas bluephagenesis via small regulatory RNAs. Metab Eng 2022; 73:58-69. [PMID: 35738548 DOI: 10.1016/j.ymben.2022.06.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 05/05/2022] [Accepted: 06/17/2022] [Indexed: 12/25/2022]
Abstract
Halomonas bluephagenesis, a robust and contamination-resistant microorganism has been developed as a chassis for "Next Generation Industrial Biotechnology". The non-model H. bluephagenesis requires efficient tools to fine-tune its metabolic fluxes for enhanced production phenotypes. Here we report a highly efficient gene expression regulation system (PrrF1-2-HfqPa) in H. bluephagenesis, small regulatory RNA (sRNA) PrrF1 scaffold from Pseudomonas aeruginosa and a target-binding sequence that downregulate gene expression, and its cognate P. aeruginosa Hfq (HfqPa), recruited by the scaffold to facilitate the hybridization of sRNA and the target mRNA. The PrrF1-2-HfqPa system targeting prpC in H. bluephagenesis helps increase 3-hydroxyvalerate fraction in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) to 21 mol% compared to 3.1 mol% of the control. This sRNA system repressed phaP1 and minD simultaneously, resulting in large polyhydroxybutyrate granules. Further, an sRNA library targeting 30 genes was employed for large-scale target identification to increase mevalonate production. This work expands the study on using an sRNA system not based on Escherichia coli MicC/SgrS-Hfq to repress gene expression, providing a framework to exploit new powerful genome engineering tools based on other sRNAs.
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Affiliation(s)
- Li-Juan Wang
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014, China; Shandong Provincial Research Center for Bioinformatic Engineering and Technology, School of Life Sciences, Shandong University of Technology, Zibo, 255049, China
| | - Xiao-Ran Jiang
- MOE Key Lab of Bioinformatics, School of Life Sciences, Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, 100084, China; Center for Synthetic and Systems Biology, Tsinghua University, Beijing, 100084, China
| | - Jie Hou
- Shandong Provincial Research Center for Bioinformatic Engineering and Technology, School of Life Sciences, Shandong University of Technology, Zibo, 255049, China
| | - Cong-Han Wang
- Shandong Provincial Research Center for Bioinformatic Engineering and Technology, School of Life Sciences, Shandong University of Technology, Zibo, 255049, China
| | - Guo-Qiang Chen
- MOE Key Lab of Bioinformatics, School of Life Sciences, Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, 100084, China; Center for Synthetic and Systems Biology, Tsinghua University, Beijing, 100084, China; MOE Key Laboratory for Industrial Biocatalysis, Dept Chemical Engineering, Tsinghua University, Beijing, 100084, China.
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11
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Li Y, Mensah EO, Fordjour E, Bai J, Yang Y, Bai Z. Recent advances in high-throughput metabolic engineering: Generation of oligonucleotide-mediated genetic libraries. Biotechnol Adv 2022; 59:107970. [PMID: 35550915 DOI: 10.1016/j.biotechadv.2022.107970] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 04/05/2022] [Accepted: 05/04/2022] [Indexed: 02/07/2023]
Abstract
The preparation of genetic libraries is an essential step to evolve microorganisms and study genotype-phenotype relationships by high-throughput screening/selection. As the large-scale synthesis of oligonucleotides becomes easy, cheap, and high-throughput, numerous novel strategies have been developed in recent years to construct high-quality oligo-mediated libraries, leveraging state-of-art molecular biology tools for genome editing and gene regulation. This review presents an overview of recent advances in creating and characterizing in vitro and in vivo genetic libraries, based on CRISPR/Cas, regulatory RNAs, and recombineering, primarily for Escherichia coli and Saccharomyces cerevisiae. These libraries' applications in high-throughput metabolic engineering, strain evolution and protein engineering are also discussed.
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Affiliation(s)
- Ye Li
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi 214122, China.
| | - Emmanuel Osei Mensah
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Eric Fordjour
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Jing Bai
- School of Chemistry and Life Sciences, Suzhou University of Science and Technology, Suzhou 215009, China
| | - Yankun Yang
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Zhonghu Bai
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi 214122, China.
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12
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Yeom J, Park JS, Jeon YM, Song BS, Yoo SM. Synthetic fused sRNA for the simultaneous repression of multiple genes. Appl Microbiol Biotechnol 2022; 106:2517-2527. [PMID: 35291022 DOI: 10.1007/s00253-022-11867-5] [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: 01/22/2022] [Revised: 03/03/2022] [Accepted: 03/05/2022] [Indexed: 11/02/2022]
Abstract
Efficient control over multiple gene expression still presents a major challenge. Synthetic sRNA enables targeted gene expression control in trans without directly modifying the chromosome, but its use to simultaneously target multiple genes can often cause cell growth defects because of the need for additional energy for transcription and lowering of their repression efficiency by limiting the amount of Hfq protein. To address these limitations, we present fusion sRNA (fsRNA) that simultaneously regulates the translation of multiple genes efficiently. It is constructed by linking the mRNA-binding modules for multiple targeted genes in one sRNA scaffold via one-pot generation using overlap extension PCR. The repression capacity of fsRNA was demonstrated by the construction of sRNAs to target four endogenous genes: caiF, hybG, ytfR and minD in Escherichia coli. Their cross-reactivity and the effect on cell growth were also investigated. As practical applications, we applied fsRNA to violacein- and protocatechuic acid-producing strains, resulting in increases of 13% violacein and 81% protocatechuic acid, respectively. The developed fsRNA-mediated multiple gene expression regulation system thus enables rapid and efficient development of optimised cell factories for valuable chemicals without cell growth defects and limiting cellular resources.Key points• Synthetic fusion sRNA (fsRNA)-based system was constructed for the repression of multiple target genes.• fsRNA repressed multiple genes by only expressing a single sRNA while minimising the cellular burden.• The application of fsRNA showed the increased production titers of violacein (13%) and protocatechuic acid (81%).
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Affiliation(s)
- Jinho Yeom
- School of Integrative Engineering, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Jong Seong Park
- School of Integrative Engineering, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Yong Min Jeon
- School of Integrative Engineering, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Beom Seop Song
- School of Integrative Engineering, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Seung Min Yoo
- School of Integrative Engineering, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea.
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13
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Zhu LP, Song SZ, Yang S. Gene repression using synthetic small regulatory RNA in Methylorubrum extorquens. J Appl Microbiol 2021; 131:2861-2875. [PMID: 34021964 DOI: 10.1111/jam.15159] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 05/07/2021] [Accepted: 05/18/2021] [Indexed: 12/11/2022]
Abstract
AIM Genetic tools are a prerequisite for engineering cell factories for synthetic biology and biotechnology. Methylorubrum extorquens is an important platform for a future one-carbon (C1) bioeconomy, but its application is currently limited by the availability of genetic tools. Small regulatory RNA (sRNA) is an important regulatory factor in bacteria and has been applied for gene repression in several strains. This study aimed to construct a synthetic sRNA system based on the MicC scaffold and the chaperone Hfq to control gene expression in M. extorquens. METHODS AND RESULTS Initially, the exogenous lacZ gene was transposed into the M. extorquens chromosome as a reporter, and corresponding β-galactosidase was measured to assess the knockdown efficiency of lacZ. A synthetic sRNA containing a 24-nt antisense RNA targeting lacZ and an Escherichia coli MicC scaffold were constructed, and different Hfqs from E. coli, M. extorquens AM1 and PA1 were further identified. The results showed that the expression of endogenous hfqs from the chromosome in M. extorquens strains was inadequate, and only when it was overexpressed via the plasmid did the colonies show a colour change and a corresponding decrease in β-galactosidase expression. More specifically, M. extorquens strains with overexpressing their own Hfq showed the best gene repression efficiency. Furthermore, this E. coli MicC scaffold and AM1 Hfq system were combined to knock down crtI gene expression in AM1, leading to an 86% decrease in carotenoid production (0·09 mg g-1 ) compared to that (0·65 mg g-1 ) in the wild-type strain. CONCLUSION A functional synthetic sRNA system combined with E. coli MicC and endogenous Hfq was constructed in M. extorquens strains, which was able to interfere with the target crtI gene and reduce carotenoid production. SIGNIFICANCE AND IMPACT OF THE STUDY The synthetic sRNA system reported in this study provides a genetic tool for the manipulation of M. extorquens. The present findings might be helpful for achieving high-throughput gene knockdown expression.
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Affiliation(s)
- L-P Zhu
- Shandong Province Key Laboratory of Applied Mycology, Qingdao International Center on Microbes Utilizing Biogas, and School of Life Sciences, Qingdao Agricultural University, Qingdao, China
| | - S-Z Song
- Shandong Province Key Laboratory of Applied Mycology, Qingdao International Center on Microbes Utilizing Biogas, and School of Life Sciences, Qingdao Agricultural University, Qingdao, China
| | - S Yang
- Shandong Province Key Laboratory of Applied Mycology, Qingdao International Center on Microbes Utilizing Biogas, and School of Life Sciences, Qingdao Agricultural University, Qingdao, China.,Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin University, Tianjin, China
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14
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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: 22] [Impact Index Per Article: 7.3] [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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15
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Escherichia coli as a platform microbial host for systems metabolic engineering. Essays Biochem 2021; 65:225-246. [PMID: 33956149 DOI: 10.1042/ebc20200172] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 04/12/2021] [Accepted: 04/14/2021] [Indexed: 12/19/2022]
Abstract
Bio-based production of industrially important chemicals and materials from non-edible and renewable biomass has become increasingly important to resolve the urgent worldwide issues including climate change. Also, bio-based production, instead of chemical synthesis, of food ingredients and natural products has gained ever increasing interest for health benefits. Systems metabolic engineering allows more efficient development of microbial cell factories capable of sustainable, green, and human-friendly production of diverse chemicals and materials. Escherichia coli is unarguably the most widely employed host strain for the bio-based production of chemicals and materials. In the present paper, we review the tools and strategies employed for systems metabolic engineering of E. coli. Next, representative examples and strategies for the production of chemicals including biofuels, bulk and specialty chemicals, and natural products are discussed, followed by discussion on materials including polyhydroxyalkanoates (PHAs), proteins, and nanomaterials. Lastly, future perspectives and challenges remaining for systems metabolic engineering of E. coli are discussed.
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16
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Fujita S, Tsumori Y, Makino Y, Saito M, Kawano M. Development of multiplexing gene silencing system using conditionally induced polycistronic synthetic antisense RNAs in Escherichia coli. Biochem Biophys Res Commun 2021; 556:163-170. [PMID: 33845307 DOI: 10.1016/j.bbrc.2021.03.152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 03/28/2021] [Indexed: 11/16/2022]
Abstract
Although efficient methods of gene silencing have been established in eukaryotes, many different techniques are still used in bacteria due to the lack of a standardized tool. Here, we developed a convenient and efficient method to downregulate the expression of a specific gene using ∼140 nucleotide RNA with a 24-nucleotide antisense region from an arabinose-inducible expression plasmid by taking Escherichia coli lacZ and phoA genes encoding β-galactosidase and alkaline phosphatase, respectively, as target genes to evaluate the model. We examined the antisense RNA (asRNA) design, including targeting position, uORF stability elements at the 5'-end, and Hfq-binding module at the 3'-end, and inducer amount required to obtain effective experimental conditions for gene silencing. Furthermore, we constructed multiplexed dual-acting asRNA genes in the plasmid, which were transcribed as polycistronic RNA and were able to knockdown multiple target genes simultaneously. We observed the highest inhibition level of 98.6% when lacZ was targeted using the pMKN104 asRNA expression plasmid, containing a five times stronger PBAD -10 promoter sequence with no requirement of the Hfq protein for repression. These features allow the system to be utilized as an asRNA expression platform in many bacteria, besides E. coli, for gene regulation.
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Affiliation(s)
- Shouta Fujita
- Laboratory of Gene Regulation Study, Department of Applied Life Sciences, Niigata University of Pharmacy and Applied Life Sciences, Niigata, Japan
| | - Yutaka Tsumori
- Laboratory of Gene Regulation Study, Department of Applied Life Sciences, Niigata University of Pharmacy and Applied Life Sciences, Niigata, Japan
| | - Yuko Makino
- Laboratory of Gene Regulation Study, Department of Applied Life Sciences, Niigata University of Pharmacy and Applied Life Sciences, Niigata, Japan
| | - Mineki Saito
- Department of Microbiology, Kawasaki Medical School, Kurashiki, Japan
| | - Mitsuoki Kawano
- Department of Human Nutrition, Faculty of Contemporary Life Science, Chugokugakuen University, Okayama, Japan.
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17
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Ren J, Lee HM, Thai TD, Na D. Identification of a cytosine methyltransferase that improves transformation efficiency in Methylomonas sp. DH-1. BIOTECHNOLOGY FOR BIOFUELS 2020; 13:200. [PMID: 33372613 PMCID: PMC7720504 DOI: 10.1186/s13068-020-01846-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Accepted: 11/30/2020] [Indexed: 05/10/2023]
Abstract
BACKGROUND Industrial biofuels and other value-added products can be produced from metabolically engineered microorganisms. Methylomonas sp. DH-1 is a candidate platform for bioconversion that uses methane as a carbon source. Although several genetic engineering techniques have been developed to work with Methylomonas sp. DH-1, the genetic manipulation of plasmids remains difficult because of the restriction-modification (RM) system present in the bacteria. Therefore, the RM system in Methylomonas sp. DH-1 must be identified to improve the genetic engineering prospects of this microorganism. RESULTS We identified a DNA methylation site, TGGCCA, and its corresponding cytosine methyltransferase for the first time in Methylomonas sp. DH-1 through whole-genome bisulfite sequencing. The methyltransferase was confirmed to methylate the fourth nucleotide of TGGCCA. In general, methylated plasmids exhibited better transformation efficiency under the protection of the RM system than non-methylated plasmids did. As expected, when we transformed Methylomonas sp. DH-1 with plasmid DNA harboring the psy gene, the metabolic flux towards carotenoid increased. The methyltransferase-treated plasmid exhibited an increase in transformation efficiency of 2.5 × 103 CFU/μg (124%). The introduced gene increased the production of carotenoid by 26%. In addition, the methyltransferase-treated plasmid harboring anti-psy sRNA gene exhibited an increase in transformation efficiency by 70% as well. The production of carotenoid was decreased by 40% when the psy gene was translationally repressed by anti-psy sRNA. CONCLUSIONS Plasmid DNA methylated by the discovered cytosine methyltransferase from Methylomonas sp. DH-1 had a higher transformation efficiency than non-treated plasmid DNA. The RM system identified in this study may facilitate the plasmid-based genetic manipulation of methanotrophs.
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Affiliation(s)
- Jun Ren
- Department of Biomedical Engineering, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Hyang-Mi Lee
- Department of Biomedical Engineering, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Thi Duc Thai
- Department of Biomedical Engineering, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Dokyun Na
- Department of Biomedical Engineering, Chung-Ang University, Seoul, 06974, Republic of Korea.
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Sohn YJ, Kim HT, Jo SY, Song HM, Baritugo KA, Pyo J, Choi JI, Joo JC, Park SJ. Recent Advances in Systems Metabolic Engineering Strategies for the Production of Biopolymers. BIOTECHNOL BIOPROC E 2020. [DOI: 10.1007/s12257-019-0508-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Synthetic small regulatory RNAs in microbial metabolic engineering. Appl Microbiol Biotechnol 2020; 105:1-12. [PMID: 33201273 DOI: 10.1007/s00253-020-10971-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Revised: 10/15/2020] [Accepted: 10/21/2020] [Indexed: 02/06/2023]
Abstract
Small regulatory RNAs (sRNAs) finely control gene expression in prokaryotes and synthetic sRNA has become a useful high-throughput approach to tackle current challenges in metabolic engineering because of its many advantages compared to conventional gene knockouts. In this review, we first focus on the modular structures of sRNAs and rational design strategies of synthetic sRNAs on the basis of their modular structures. The wide applications of synthetic sRNAs in bacterial metabolic engineering, with or without the aid of heterogeneously expressed Hfq protein, were also covered. In addition, we give attention to the improvements in implementing synthetic sRNAs, which make the synthetic sRNA strategy universally applicable in metabolic engineering and synthetic biology. KEY POINTS: • Synthetic sRNAs can be rationally designed based on modular structures of natural sRNAs. • Synthetic sRNAs were widely used for metabolic engineering in various microorganisms. • Several technological improvements made the synthetic sRNA strategy more applicable.
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Development of a DNA double-strand break-free base editing tool in Corynebacterium glutamicum for genome editing and metabolic engineering. Metab Eng Commun 2020; 11:e00135. [PMID: 32577397 PMCID: PMC7300154 DOI: 10.1016/j.mec.2020.e00135] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 05/15/2020] [Accepted: 05/24/2020] [Indexed: 12/26/2022] Open
Abstract
As a traditional amino acid producing bacterium, Corynebacterium glutamicum is a platform strain for production of various fine chemicals. Based on the CRISPR (Clustered regularly interspaced short palindromic repeats)-Cas9 system, gene editing tools that enable base conversion in the genome of C. glutamicum have been developed. However, some problems such as genomic instability caused by DNA double-strand break (DSB) and off-target effects need to be solved. In this study, a DSB-free single nucleotide genome editing system was developed by construction of a bi-directional base conversion tool TadA-dCas9-AID. This system includes cytosine base editors (CBEs): activation-induced cytidine deaminase (AID) and adenine deaminase (ABEs): tRNA adenosine deaminase (TadA), which can specifically target the gene through a 20-nt single guide RNA (sgRNA) and achieve the base conversion of C-T, C-G and A-G in the 28-bp editing window upstream of protospacer adjacent motif. Finally, as a proof-of-concept demonstration, the system was used to construct a mutant library of zwf gene in C. glutamicum S9114 genome to improve the production of a typical nutraceutical N-acetylglucosamine (GlcNAc). The GlcNAc titer of the mutant strain K293R was increased by 31.9% to 9.1 g/L in shake flask. Here, the developed bases conversion tool TadA-dCas9-AID does not need DNA double-strand break and homologous template, and is effective for genome editing and metabolic engineering in C. glutamicum. A DNA double-strand break-free base editing tool was developed in Corynebacterium glutamicum S9114, which can produce diverse single base mutations. The base editing tool can be used for base mutations on genome and metabolic engineering of C. glutamicum S9114. High efficiency 20N target sequence linking strategy was developed. The base editing tool is used to increase the titer of GlcNAc.
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21
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Kato Y. Extremely Low Leakage Expression Systems Using Dual Transcriptional-Translational Control for Toxic Protein Production. Int J Mol Sci 2020; 21:ijms21030705. [PMID: 31973139 PMCID: PMC7037476 DOI: 10.3390/ijms21030705] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 12/25/2019] [Accepted: 01/19/2020] [Indexed: 02/01/2023] Open
Abstract
Expression systems for highly toxic protein genes must be conditional and suppress leakage expression to almost zero because even faint leakage expression may kill host cells, inhibit host growth, and cause loss of plasmids containing the toxic protein genes. The most widely used conditional expression systems are controlled only at the transcriptional level, and complete suppression of leakage expression is challenging. Recent progress on translational control has enabled construction of dual transcriptional-translational control systems in which leakage expression is strongly suppressed. This review summarizes the principles, features, and practical examples of dual transcriptional-translational control systems in bacteria, and provides future perspectives on these systems.
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Affiliation(s)
- Yusuke Kato
- Division of Biotechnology, Institute of Agrobiological Sciences, National Agriculture and Food Research Organization (NARO), Oowashi 1-2, Tsukuba, Ibaraki 305-8634, Japan
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