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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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2
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Buson F, Gao Y, Wang B. Genetic Parts and Enabling Tools for Biocircuit Design. ACS Synth Biol 2024; 13:697-713. [PMID: 38427821 DOI: 10.1021/acssynbio.3c00691] [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: 03/03/2024]
Abstract
Synthetic biology aims to engineer biological systems for customized tasks through the bottom-up assembly of fundamental building blocks, which requires high-quality libraries of reliable, modular, and standardized genetic parts. To establish sets of parts that work well together, synthetic biologists created standardized part libraries in which every component is analyzed in the same metrics and context. Here we present a state-of-the-art review of the currently available part libraries for designing biocircuits and their gene expression regulation paradigms at transcriptional, translational, and post-translational levels in Escherichia coli. We discuss the necessary facets to integrate these parts into complex devices and systems along with the current efforts to catalogue and standardize measurement data. To better display the range of available parts and to facilitate part selection in synthetic biology workflows, we established biopartsDB, a curated database of well-characterized and useful genetic part and device libraries with detailed quantitative data validated by the published literature.
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Affiliation(s)
- Felipe Buson
- College of Chemical and Biological Engineering & ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 310058, China
- School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FF, U.K
| | - Yuanli Gao
- College of Chemical and Biological Engineering & ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 310058, China
- School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FF, U.K
| | - Baojun Wang
- College of Chemical and Biological Engineering & ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 310058, China
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3
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De Marchi D, Shaposhnikov R, Gobaa S, Pastorelli D, Batt G, Magni P, Pasotti L. Design and Model-Driven Analysis of Synthetic Circuits with the Staphylococcus aureus Dead-Cas9 (sadCas9) as a Programmable Transcriptional Regulator in Bacteria. ACS Synth Biol 2024; 13:763-780. [PMID: 38374729 DOI: 10.1021/acssynbio.3c00541] [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: 02/21/2024]
Abstract
Synthetic circuit design is crucial for engineering microbes that process environmental cues and provide biologically relevant outputs. To reliably scale-up circuit complexity, the availability of parts toolkits is central. Streptococcus pyogenes (sp)-derived CRISPR interference/dead-Cas9 (CRISPRi/spdCas9) is widely adopted for implementing programmable regulations in synthetic circuits, and alternative CRISPRi systems will further expand our toolkits of orthogonal components. Here, we showcase the potential of CRISPRi using the engineered dCas9 from Staphylococcus aureus (sadCas9), not previously used in bacterial circuits, that is attractive for its low size and high specificity. We designed a collection of ∼20 increasingly complex circuits and variants in Escherichia coli, including circuits with static function like one-/two-input logic gates (NOT, NAND), circuits with dynamic behavior like incoherent feedforward loops (iFFLs), and applied sadCas9 to fix a T7 polymerase-based cascade. Data demonstrated specific and efficient target repression (100-fold) and qualitatively successful functioning for all circuits. Other advantageous features included low sadCas9-borne cell load and orthogonality with spdCas9. However, different circuit variants showed quantitatively unexpected and previously unreported steady-state responses: the dynamic range, switch point, and slope of NOT/NAND gates changed for different output promoters, and a multiphasic behavior was observed in iFFLs, differing from the expected bell-shaped or sigmoidal curves. Model analysis explained the observed curves by complex interplays among components, due to reporter gene-borne cell load and regulator competition. Overall, CRISPRi/sadCas9 successfully expanded the available toolkit for bacterial engineering. Analysis of our circuit collection depicted the impact of generally neglected effects modulating the shape of component dose-response curves, to avoid drawing wrong conclusions on circuit functioning.
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Affiliation(s)
- Davide De Marchi
- Department of Electrical, Computer and Biomedical Engineering, University of Pavia, via Ferrata 5, 27100 Pavia, Italy
- Centre for Health Technologies, University of Pavia, via Ferrata 5, 27100 Pavia, Italy
| | - Roman Shaposhnikov
- Department of Electrical, Computer and Biomedical Engineering, University of Pavia, via Ferrata 5, 27100 Pavia, Italy
- Centre for Health Technologies, University of Pavia, via Ferrata 5, 27100 Pavia, Italy
| | - Samy Gobaa
- Institut Pasteur, Université Paris Cité, Biomaterials and Microfluidics Core Facility, 28 Rue du Docteur Roux, 75015 Paris, France
| | - Daniele Pastorelli
- Department of Electrical, Computer and Biomedical Engineering, University of Pavia, via Ferrata 5, 27100 Pavia, Italy
- Centre for Health Technologies, University of Pavia, via Ferrata 5, 27100 Pavia, Italy
| | - Gregory Batt
- Institut Pasteur, Inria, Université Paris Cité, 28 rue du Docteur Roux, 75015 Paris, France
| | - Paolo Magni
- Department of Electrical, Computer and Biomedical Engineering, University of Pavia, via Ferrata 5, 27100 Pavia, Italy
- Centre for Health Technologies, University of Pavia, via Ferrata 5, 27100 Pavia, Italy
| | - Lorenzo Pasotti
- Department of Electrical, Computer and Biomedical Engineering, University of Pavia, via Ferrata 5, 27100 Pavia, Italy
- Centre for Health Technologies, University of Pavia, via Ferrata 5, 27100 Pavia, Italy
- Institut Pasteur, Inria, Université Paris Cité, 28 rue du Docteur Roux, 75015 Paris, France
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4
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Meier D, Rauch C, Wagner M, Klemm P, Blumenkamp P, Müller R, Ellenberger E, Karia KM, Vecchione S, Serrania J, Lechner M, Fritz G, Goesmann A, Becker A. A MoClo-Compatible Toolbox of ECF Sigma Factor-Based Regulatory Switches for Proteobacterial Chassis. BIODESIGN RESEARCH 2024; 6:0025. [PMID: 38384496 PMCID: PMC10880074 DOI: 10.34133/bdr.0025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 12/04/2023] [Indexed: 02/23/2024] Open
Abstract
The construction of complex synthetic gene circuits with predetermined and reliable output depends on orthogonal regulatory parts that do not inadvertently interfere with the host machinery or with other circuit components. Previously, extracytoplasmic function sigma factors (ECFs), a diverse group of alternative sigma factors with distinct promoter specificities, were shown to have great potential as context-independent regulators, but so far, they have only been used in a few model species. Here, we show that the alphaproteobacterium Sinorhizobium meliloti, which has been proposed as a plant-associated bacterial chassis for synthetic biology, has a similar phylogenetic ECF acceptance range as the gammaproteobacterium Escherichia coli. A common set of orthogonal ECF-based regulators that can be used in both bacterial hosts was identified and used to create 2-step delay circuits. The genetic circuits were implemented in single copy in E. coli by chromosomal integration using an established method that utilizes bacteriophage integrases. In S. meliloti, we demonstrated the usability of single-copy pABC plasmids as equivalent carriers of the synthetic circuits. The circuits were either implemented on a single pABC or modularly distributed on 3 such plasmids. In addition, we provide a toolbox containing pABC plasmids compatible with the Golden Gate (MoClo) cloning standard and a library of basic parts that enable the construction of ECF-based circuits in S. meliloti and in E. coli. This work contributes to building a context-independent and species-overarching ECF-based toolbox for synthetic biology applications.
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Affiliation(s)
- Doreen Meier
- Center for Synthetic Microbiology (SYNMIKRO) and Department of Biology,
Philipps-Universität Marburg, Marburg, Germany
| | - Christian Rauch
- Center for Synthetic Microbiology (SYNMIKRO) and Department of Biology,
Philipps-Universität Marburg, Marburg, Germany
| | - Marcel Wagner
- Center for Synthetic Microbiology (SYNMIKRO) and Department of Biology,
Philipps-Universität Marburg, Marburg, Germany
| | - Paul Klemm
- Center for Synthetic Microbiology (SYNMIKRO) and Department of Biology,
Philipps-Universität Marburg, Marburg, Germany
| | - Patrick Blumenkamp
- Bioinformatics and Systems Biology,
Justus-Liebig-Universität Giessen, Giessen, Germany
| | - Raphael Müller
- Bioinformatics and Systems Biology,
Justus-Liebig-Universität Giessen, Giessen, Germany
| | - Eric Ellenberger
- Center for Synthetic Microbiology (SYNMIKRO) and Department of Biology,
Philipps-Universität Marburg, Marburg, Germany
| | - Kinnari M. Karia
- Center for Synthetic Microbiology (SYNMIKRO) and Department of Biology,
Philipps-Universität Marburg, Marburg, Germany
| | - Stefano Vecchione
- Center for Synthetic Microbiology (SYNMIKRO) and Department of Biology,
Philipps-Universität Marburg, Marburg, Germany
| | - Javier Serrania
- Center for Synthetic Microbiology (SYNMIKRO) and Department of Biology,
Philipps-Universität Marburg, Marburg, Germany
| | - Marcus Lechner
- Center for Synthetic Microbiology (SYNMIKRO) and Department of Biology,
Philipps-Universität Marburg, Marburg, Germany
| | - Georg Fritz
- The University of Western Australia, School of Molecular Sciences, Perth, Australia
| | - Alexander Goesmann
- Bioinformatics and Systems Biology,
Justus-Liebig-Universität Giessen, Giessen, Germany
| | - Anke Becker
- Center for Synthetic Microbiology (SYNMIKRO) and Department of Biology,
Philipps-Universität Marburg, Marburg, Germany
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5
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Stone A, Youssef A, Rijal S, Zhang R, Tian XJ. Context-dependent redesign of robust synthetic gene circuits. Trends Biotechnol 2024:S0167-7799(24)00003-9. [PMID: 38320912 DOI: 10.1016/j.tibtech.2024.01.003] [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: 11/02/2023] [Revised: 01/10/2024] [Accepted: 01/11/2024] [Indexed: 02/08/2024]
Abstract
Cells provide dynamic platforms for executing exogenous genetic programs in synthetic biology, resulting in highly context-dependent circuit performance. Recent years have seen an increasing interest in understanding the intricacies of circuit-host relationships, their influence on the synthetic bioengineering workflow, and in devising strategies to alleviate undesired effects. We provide an overview of how emerging circuit-host interactions, such as growth feedback and resource competition, impact both deterministic and stochastic circuit behaviors. We also emphasize control strategies for mitigating these unwanted effects. This review summarizes the latest advances and the current state of host-aware and resource-aware design of synthetic gene circuits.
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Affiliation(s)
- Austin Stone
- School of Biological and Health System Engineering, Arizona State University, Tempe, AZ 85281, USA
| | - Abdelrahaman Youssef
- School of Biological and Health System Engineering, Arizona State University, Tempe, AZ 85281, USA
| | - Sadikshya Rijal
- School of Biological and Health System Engineering, Arizona State University, Tempe, AZ 85281, USA
| | - Rong Zhang
- School of Biological and Health System Engineering, Arizona State University, Tempe, AZ 85281, USA
| | - Xiao-Jun Tian
- School of Biological and Health System Engineering, Arizona State University, Tempe, AZ 85281, USA.
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6
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Larsson EM, Murray RM, Newman DK. Engineering the Soil Bacterium Pseudomonas synxantha 2-79 into a Ratiometric Bioreporter for Phosphorus Limitation. ACS Synth Biol 2024; 13:384-393. [PMID: 38165130 DOI: 10.1021/acssynbio.3c00642] [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: 01/03/2024]
Abstract
Microbial bioreporters hold promise for addressing challenges in medical and environmental applications. However, the difficulty in ensuring their stable persistence and function within the target environment remains a challenge. One strategy is to integrate information about the host strain and target environment into the design-build-test cycle of the bioreporter itself. Here, we present a case study for such an environmentally motivated design process by engineering the wheat commensal bacterium Pseudomonas synxantha 2-79 into a ratiometric bioreporter for phosphorus limitation. Comparative analysis showed that an exogenous P-responsive promoter outperformed its native counterparts. This reporter can selectively sense and report phosphorus limitation at plant-relevant concentrations of 25-100 μM without cross-activation from carbon or nitrogen limitation or high cell densities. Its performance is robust over a field-relevant pH range (5.8-8), and it responds only to inorganic phosphorus, even in the presence of common soil organic P. Finally, we used fluorescein-calibrated flow cytometry to assess whether the reporter's performance in shaken liquid culture predicts its performance in soil, finding that although the reporter is still functional at the bulk level, its variability in performance increases when grown in a soil slurry as compared to planktonic culture, with a fraction of the population not expressing the reporter proteins. Together, our environmentally aware design process provides an example of how laboratory bioengineering efforts can generate microbes with a greater promise to function reliably in their applied contexts.
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Affiliation(s)
- Elin M Larsson
- Division of Biology and Bioengineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Richard M Murray
- Division of Biology and Bioengineering, California Institute of Technology, Pasadena, California 91125, United States
- Control and Dynamical Systems, California Institute of Technology, Pasadena, California 91125, United States
| | - Dianne K Newman
- Division of Biology and Bioengineering, California Institute of Technology, Pasadena, California 91125, United States
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, United States
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7
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Moon S, Saboe A, Smanski MJ. Using design of experiments to guide genetic optimization of engineered metabolic pathways. J Ind Microbiol Biotechnol 2024; 51:kuae010. [PMID: 38490746 PMCID: PMC10981448 DOI: 10.1093/jimb/kuae010] [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: 12/12/2023] [Accepted: 03/14/2024] [Indexed: 03/17/2024]
Abstract
Design of experiments (DoE) is a term used to describe the application of statistical approaches to interrogate the impact of many variables on the performance of a multivariate system. It is commonly used for process optimization in fields such as chemical engineering and material science. Recent advances in the ability to quantitatively control the expression of genes in biological systems open up the possibility to apply DoE for genetic optimization. In this review targeted to genetic and metabolic engineers, we introduce several approaches in DoE at a high level and describe instances wherein these were applied to interrogate or optimize engineered genetic systems. We discuss the challenges of applying DoE and propose strategies to mitigate these challenges. ONE-SENTENCE SUMMARY This is a review of literature related to applying Design of Experiments for genetic optimization.
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Affiliation(s)
- Seonyun Moon
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, St Paul, MN 55108, USA
- Biotechnology Institute, University of Minnesota, St Paul, MN 55108, USA
| | - Anna Saboe
- Biotechnology Institute, University of Minnesota, St Paul, MN 55108, USA
| | - Michael J Smanski
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, St Paul, MN 55108, USA
- Biotechnology Institute, University of Minnesota, St Paul, MN 55108, USA
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8
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Wu Y, Li Y, Zhang Y, Liu Y, Li J, Du G, Lv X, Liu L. Efficient Protein Expression and Biosynthetic Gene Cluster Regulation in Bacillus subtilis Driven by a T7-BOOST System. ACS Synth Biol 2023; 12:3328-3339. [PMID: 37885173 DOI: 10.1021/acssynbio.3c00331] [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: 10/28/2023]
Abstract
Bacillus subtilis is a generally recognized as safe microorganism that is widely used for protein expression and chemical production, but has a limited number of genetic regulatory components compared with the Gram-negative model microorganism Escherichia coli. In this study, a two-module plug-and-play T7-based optimized output strategy for transcription (T7-BOOST) systems with low leakage expression and a wide dynamic range was constructed based on the inducible promoters Phy-spank and PxylA. The first T7 RNA polymerase-driven module was seamlessly integrated into the genome based on the CRISPR/Cpf1 system, while the second expression control module was introduced into low, medium, and high copy plasmids for characterization. As a proof of concept, the T7-BOOST systems were successfully employed for whole-cell catalysis production of γ-aminobutyric acid (109.8 g/L with a 98.0% conversion rate), expression of human αS1 casein and human lactoferrin, and regulation of exogenous lycopene biosynthetic gene cluster and endogenous riboflavin biosynthetic gene cluster. Overall, the T7-BOOST system serves as a stringent, controllable, and effective tool for regulating gene expression in B. subtilis.
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Affiliation(s)
- Yaokang Wu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China
| | - Yang Li
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China
| | - Yuting Zhang
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China
| | - Yanfeng Liu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China
- Baima Future Foods Research Institute, Nanjing 211225, China
| | - Jianghua Li
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China
- Baima Future Foods Research Institute, Nanjing 211225, China
| | - Guocheng Du
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China
- Baima Future Foods Research Institute, Nanjing 211225, China
| | - Xueqin Lv
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China
- Baima Future Foods Research Institute, Nanjing 211225, China
| | - Long Liu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China
- Baima Future Foods Research Institute, Nanjing 211225, China
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9
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Lammens EM, Putzeys L, Boon M, Lavigne R. Sourcing Phage-Encoded Terminators Using ONT-cappable-seq for SynBio Applications in Pseudomonas. ACS Synth Biol 2023; 12:1415-1423. [PMID: 37092882 DOI: 10.1021/acssynbio.3c00101] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Efficient transcriptional terminators are essential for the performance of genetic circuitry in microbial SynBio hosts. In recent years, several libraries of characterized strong terminators have become available for model organisms such as Escherichia coli. Conversely, terminator libraries for nonmodel species remain scarce, and individual terminators are often ported over from model systems, leading to unpredictable performance in their new hosts. In this work, we mined the genomes of Pseudomonas infecting phages LUZ7 and LUZ100 for transcriptional terminators utilizing the full-length RNA sequencing technique "ONT-cappable-seq" and validated these terminators in three Gram-negative hosts using a terminator trap assay. Based on these results, we present nine terminators for E. coli, Pseudomonas putida, and Pseudomonas aeruginosa, which outperform current reference terminators. Among these, terminator LUZ7 T50 displays potent bidirectional activity. These data further support that bacteriophages, as evolutionary-adapted natural predators of the targeted bacteria, provide a valuable source of microbial SynBio parts.
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Affiliation(s)
- Eveline-Marie Lammens
- Laboratory of Gene Technology, Department of Biosystems, KU Leuven, 3001 Leuven, Belgium
| | - Leena Putzeys
- Laboratory of Gene Technology, Department of Biosystems, KU Leuven, 3001 Leuven, Belgium
| | - Maarten Boon
- Laboratory of Gene Technology, Department of Biosystems, KU Leuven, 3001 Leuven, Belgium
| | - Rob Lavigne
- Laboratory of Gene Technology, Department of Biosystems, KU Leuven, 3001 Leuven, Belgium
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10
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Lammens EM, Feyaerts N, Kerremans A, Boon M, Lavigne R. Assessing the Orthogonality of Phage-Encoded RNA Polymerases for Tailored Synthetic Biology Applications in Pseudomonas Species. Int J Mol Sci 2023; 24:ijms24087175. [PMID: 37108338 PMCID: PMC10138996 DOI: 10.3390/ijms24087175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 03/27/2023] [Accepted: 03/27/2023] [Indexed: 04/29/2023] Open
Abstract
The phage T7 RNA polymerase (RNAP) and lysozyme form the basis of the widely used pET expression system for recombinant expression in the biotechnology field and as a tool in microbial synthetic biology. Attempts to transfer this genetic circuitry from Escherichia coli to non-model bacterial organisms with high potential have been restricted by the cytotoxicity of the T7 RNAP in the receiving hosts. We here explore the diversity of T7-like RNAPs mined directly from Pseudomonas phages for implementation in Pseudomonas species, thus relying on the co-evolution and natural adaptation of the system towards its host. By screening and characterizing different viral transcription machinery using a vector-based system in P. putida., we identified a set of four non-toxic phage RNAPs from phages phi15, PPPL-1, Pf-10, and 67PfluR64PP, showing a broad activity range and orthogonality to each other and the T7 RNAP. In addition, we confirmed the transcription start sites of their predicted promoters and improved the stringency of the phage RNAP expression systems by introducing and optimizing phage lysozymes for RNAP inhibition. This set of viral RNAPs expands the adaption of T7-inspired circuitry towards Pseudomonas species and highlights the potential of mining tailored genetic parts and tools from phages for their non-model host.
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Affiliation(s)
- Eveline-Marie Lammens
- Laboratory of Gene Technology, Department of Biosystems, KU Leuven, Kasteelpark Arenberg 21 Box 2462, 3001 Leuven, Belgium
| | - Nathalie Feyaerts
- Laboratory of Gene Technology, Department of Biosystems, KU Leuven, Kasteelpark Arenberg 21 Box 2462, 3001 Leuven, Belgium
| | - Alison Kerremans
- Laboratory of Gene Technology, Department of Biosystems, KU Leuven, Kasteelpark Arenberg 21 Box 2462, 3001 Leuven, Belgium
| | - Maarten Boon
- Laboratory of Gene Technology, Department of Biosystems, KU Leuven, Kasteelpark Arenberg 21 Box 2462, 3001 Leuven, Belgium
| | - Rob Lavigne
- Laboratory of Gene Technology, Department of Biosystems, KU Leuven, Kasteelpark Arenberg 21 Box 2462, 3001 Leuven, Belgium
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11
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Bennett EM, Murray JW, Isalan M. Engineering Nitrogenases for Synthetic Nitrogen Fixation: From Pathway Engineering to Directed Evolution. BIODESIGN RESEARCH 2023; 5:0005. [PMID: 37849466 PMCID: PMC10521693 DOI: 10.34133/bdr.0005] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 12/24/2022] [Indexed: 10/19/2023] Open
Abstract
Globally, agriculture depends on industrial nitrogen fertilizer to improve crop growth. Fertilizer production consumes fossil fuels and contributes to environmental nitrogen pollution. A potential solution would be to harness nitrogenases-enzymes capable of converting atmospheric nitrogen N2 to NH3 in ambient conditions. It is therefore a major goal of synthetic biology to engineer functional nitrogenases into crop plants, or bacteria that form symbiotic relationships with crops, to support growth and reduce dependence on industrially produced fertilizer. This review paper highlights recent work toward understanding the functional requirements for nitrogenase expression and manipulating nitrogenase gene expression in heterologous hosts to improve activity and oxygen tolerance and potentially to engineer synthetic symbiotic relationships with plants.
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Affiliation(s)
- Emily M. Bennett
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - James W. Murray
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Mark Isalan
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
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12
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Gambill L, Staubus A, Mo KW, Ameruoso A, Chappell J. A split ribozyme that links detection of a native RNA to orthogonal protein outputs. Nat Commun 2023; 14:543. [PMID: 36725852 PMCID: PMC9892565 DOI: 10.1038/s41467-023-36073-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 01/13/2023] [Indexed: 02/03/2023] Open
Abstract
Individual RNA remains a challenging signal to synthetically transduce into different types of cellular information. Here, we describe Ribozyme-ENabled Detection of RNA (RENDR), a plug-and-play strategy that uses cellular transcripts to template the assembly of split ribozymes, triggering splicing reactions that generate orthogonal protein outputs. To identify split ribozymes that require templating for splicing, we use laboratory evolution to evaluate the activities of different split variants of the Tetrahymena thermophila ribozyme. The best design delivers a 93-fold dynamic range of splicing with RENDR controlling fluorescent protein production in response to an RNA input. We further resolve a thermodynamic model to guide RENDR design, show how input signals can be transduced into diverse outputs, demonstrate portability across different bacteria, and use RENDR to detect antibiotic-resistant bacteria. This work shows how transcriptional signals can be monitored in situ and converted into different types of biochemical information using RNA synthetic biology.
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Affiliation(s)
- Lauren Gambill
- PhD Program in Systems, Synthetic, and Physical Biology, Rice University, Houston, TX, 77005, USA
| | - August Staubus
- Department of Biosciences, Rice University, Houston, TX, 77005, USA
| | - Kim Wai Mo
- Department of Biosciences, Rice University, Houston, TX, 77005, USA
| | - Andrea Ameruoso
- Department of Biosciences, Rice University, Houston, TX, 77005, USA
| | - James Chappell
- PhD Program in Systems, Synthetic, and Physical Biology, Rice University, Houston, TX, 77005, USA. .,Department of Biosciences, Rice University, Houston, TX, 77005, USA. .,Department of Bioengineering, Rice University, Houston, TX, 77005, USA.
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13
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Sun Y, Zhang F, Li L, Chen K, Wang S, Ouyang Q, Luo C. Two-Layered Microfluidic Devices for High-Throughput Dynamic Analysis of Synthetic Gene Circuits in E. coli. ACS Synth Biol 2022; 11:3954-3965. [PMID: 36283074 DOI: 10.1021/acssynbio.2c00307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Escherichia coli is a common chassis for synthetic gene circuit studies. In addition to the dose-response of synthetic gene circuits, the analysis of dynamic responses is also an important part of the future design of more complicated synthetic systems. Recently, microfluidic-based methods have been widely used for the analysis of gene expression dynamics. Here, we established a two-layered microfluidic platform for the systematic characterization of synthetic gene circuits (eight strains in eight different culture environments could be observed simultaneously with a 5 min time resolution). With this platform, both dose responses and dynamic responses with a high temporal resolution could be easily derived for further analysis. A controlled environment ensures the stability of the bacterial growth rate, excluding changes in gene expression dynamics caused by changes of the growth dilution rate. The precise environmental switch and automatic micrograph shooting ensured that there was nearly no time lag between the inducer addition and the data recording. We studied four four-node incoherent-feedforward-loop (IFFL) networks with different operators using this device. The experimental results showed that as the effect of inhibition increased, two of the IFFL networks generated pulselike dynamic gene expressions in the range of the inducer concentrations, which was different from the dynamics of the two other circuits with only a simple pattern of rising to the platform. Through fitting the dose-response curves and the dynamic response curves, corresponding parameters were derived and introduced to a simple model that could qualitatively explain the generation of pulse dynamics.
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Affiliation(s)
- Yanhong Sun
- The State Key Laboratory for Artificial Microstructures and Mesoscopic Physics School of Physics, Peking University, Beijing100871, China
| | - Fengyu Zhang
- School of Life Sciences and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing100871, China
| | - Lusi Li
- Academy of Advanced Interdisciplinary Studies, Peking University, Beijing100871, China
| | - Kaiyue Chen
- Wenzhou Institute University of Chinese Academy of Sciences, Wenzhou, Zhejiang325001, China
| | - Shujing Wang
- The State Key Laboratory for Artificial Microstructures and Mesoscopic Physics School of Physics, Peking University, Beijing100871, China
| | - Qi Ouyang
- The State Key Laboratory for Artificial Microstructures and Mesoscopic Physics School of Physics, Peking University, Beijing100871, China.,Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing100871, China
| | - Chunxiong Luo
- The State Key Laboratory for Artificial Microstructures and Mesoscopic Physics School of Physics, Peking University, Beijing100871, China.,Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing100871, China.,Wenzhou Institute University of Chinese Academy of Sciences, Wenzhou, Zhejiang325001, China
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14
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Senda N, Enomoto T, Kihara K, Yamashiro N, Takagi N, Kiga D, Nishida H. Development of an expression-tunable multiple protein synthesis system in cell-free reactions using T7-promoter-variant series. SYNTHETIC BIOLOGY (OXFORD, ENGLAND) 2022; 7:ysac029. [PMID: 36591595 PMCID: PMC9791696 DOI: 10.1093/synbio/ysac029] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 11/01/2022] [Accepted: 11/24/2022] [Indexed: 11/27/2022]
Abstract
New materials with a low environmental load are expected to be generated through synthetic biology. To widely utilize this technology, it is important to create cells with designed biological functions and to control the expression of multiple enzymes. In this study, we constructed a cell-free evaluation system for multiple protein expression, in which synthesis is controlled by T7 promoter variants. The expression of a single protein using the T7 promoter variants showed the expected variety in expression levels, as previously reported. We then examined the expression levels of multiple proteins that are simultaneously produced in a single well to determine whether they can be predicted from the promoter activity values, which were defined from the isolated protein expression levels. When the sum of messenger ribonucleic acid (mRNA) species is small, the experimental protein expression levels can be predicted from the promoter activities (graphical abstract (a)) due to low competition for ribosomes. In other words, by using combinations of T7 promoter variants, we successfully developed a cell-free multiple protein synthesis system with tunable expression. In the presence of large amounts of mRNA, competition for ribosomes becomes an issue (graphical abstract (b)). Accordingly, the translation level of each protein cannot be directly predicted from the promoter activities and is biased by the strength of the ribosome binding site (RBS); a weaker RBS is more affected by competition. Our study provides information regarding the regulated expression of multiple enzymes in synthetic biology.
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Affiliation(s)
| | - Toshihiko Enomoto
- Department of Electrical Engineering and Bioscience, Waseda University, Shinjuku, Tokyo, Japan
| | - Kenta Kihara
- Department of Electrical Engineering and Bioscience, Waseda University, Shinjuku, Tokyo, Japan
| | - Naoki Yamashiro
- Department of Electrical Engineering and Bioscience, Waseda University, Shinjuku, Tokyo, Japan
| | - Naosato Takagi
- Department of Electrical Engineering and Bioscience, Waseda University, Shinjuku, Tokyo, Japan
| | - Daisuke Kiga
- Department of Electrical Engineering and Bioscience, Waseda University, Shinjuku, Tokyo, Japan
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15
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Plasmids for Controlled and Tunable High-Level Expression in E. coli. Appl Environ Microbiol 2022; 88:e0093922. [PMID: 36342148 PMCID: PMC9680613 DOI: 10.1128/aem.00939-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Genetic systems for protein overexpression are required tools in microbiological and biochemical research. Ideally, these systems include standardized genetic parts with predictable behavior, enabling the construction of stable expression systems in the host organism.
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16
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Zhang ZX, Nong FT, Wang YZ, Yan CX, Gu Y, Song P, Sun XM. Strategies for efficient production of recombinant proteins in Escherichia coli: alleviating the host burden and enhancing protein activity. Microb Cell Fact 2022; 21:191. [PMID: 36109777 PMCID: PMC9479345 DOI: 10.1186/s12934-022-01917-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 09/08/2022] [Indexed: 11/13/2022] Open
Abstract
Escherichia coli, one of the most efficient expression hosts for recombinant proteins (RPs), is widely used in chemical, medical, food and other industries. However, conventional expression strains are unable to effectively express proteins with complex structures or toxicity. The key to solving this problem is to alleviate the host burden associated with protein overproduction and to enhance the ability to accurately fold and modify RPs at high expression levels. Here, we summarize the recently developed optimization strategies for the high-level production of RPs from the two aspects of host burden and protein activity. The aim is to maximize the ability of researchers to quickly select an appropriate optimization strategy for improving the production of RPs.
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17
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De Wannemaeker L, Bervoets I, De Mey M. Unlocking the bacterial domain for industrial biotechnology applications using universal parts and tools. Biotechnol Adv 2022; 60:108028. [PMID: 36031082 DOI: 10.1016/j.biotechadv.2022.108028] [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: 03/10/2022] [Revised: 07/29/2022] [Accepted: 08/16/2022] [Indexed: 11/02/2022]
Abstract
Synthetic biology can play a major role in the development of sustainable industrial biotechnology processes. However, the development of economically viable production processes is currently hampered by the limited availability of host organisms that can be engineered for a specific production process. To date, standard hosts such as Escherichia coli and Saccharomyces cerevisiae are often used as starting points for process development since parts and tools allowing their engineering are readily available. However, their suboptimal metabolic background or impaired performance at industrial scale for a desired production process, can result in increased costs associated with process development and/or disappointing production titres. Building a universal and portable gene expression system allowing genetic engineering of hosts across the bacterial domain would unlock the bacterial domain for industrial biotechnology applications in a highly standardized manner and doing so, render industrial biotechnology processes more competitive compared to the current polluting chemical processes. This review gives an overview of a selection of bacterial hosts highly interesting for industrial biotechnology based on both their metabolic and process optimization properties. Moreover, the requirements and progress made so far to enable universal, standardized, and portable gene expression across the bacterial domain is discussed.
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Affiliation(s)
- Lien De Wannemaeker
- Centre for Synthetic Biology (CSB), Ghent University, Coupure links 653, 9000 Ghent, Belgium
| | - Indra Bervoets
- Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium
| | - Marjan De Mey
- Centre for Synthetic Biology (CSB), Ghent University, Coupure links 653, 9000 Ghent, Belgium.
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18
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Pandi A, Diehl C, Yazdizadeh Kharrazi A, Scholz SA, Bobkova E, Faure L, Nattermann M, Adam D, Chapin N, Foroughijabbari Y, Moritz C, Paczia N, Cortina NS, Faulon JL, Erb TJ. A versatile active learning workflow for optimization of genetic and metabolic networks. Nat Commun 2022; 13:3876. [PMID: 35790733 PMCID: PMC9256728 DOI: 10.1038/s41467-022-31245-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Accepted: 06/10/2022] [Indexed: 11/13/2022] Open
Abstract
Optimization of biological networks is often limited by wet lab labor and cost, and the lack of convenient computational tools. Here, we describe METIS, a versatile active machine learning workflow with a simple online interface for the data-driven optimization of biological targets with minimal experiments. We demonstrate our workflow for various applications, including cell-free transcription and translation, genetic circuits, and a 27-variable synthetic CO2-fixation cycle (CETCH cycle), improving these systems between one and two orders of magnitude. For the CETCH cycle, we explore 1025 conditions with only 1,000 experiments to yield the most efficient CO2-fixation cascade described to date. Beyond optimization, our workflow also quantifies the relative importance of individual factors to the performance of a system identifying unknown interactions and bottlenecks. Overall, our workflow opens the way for convenient optimization and prototyping of genetic and metabolic networks with customizable adjustments according to user experience, experimental setup, and laboratory facilities. Optimization of biological networks is often limited by wet lab labor and cost, and the lack of convenient computational tools. Here, aimed at democratization and standardization, the authors describe METIS, a modular and versatile active machine learning workflow with a simple online interface for the optimization of biological target functions with minimal experimental datasets.
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Affiliation(s)
- Amir Pandi
- Department of Biochemistry & Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany.
| | - Christoph Diehl
- Department of Biochemistry & Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | | | - Scott A Scholz
- Department of Biochemistry & Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Elizaveta Bobkova
- Department of Biochemistry & Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Léon Faure
- Micalis Institute, INRAE, AgroParisTech, University of Paris-Saclay, Jouy-en-Josas, France
| | - Maren Nattermann
- Department of Biochemistry & Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - David Adam
- Department of Biochemistry & Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Nils Chapin
- Department of Biochemistry & Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Yeganeh Foroughijabbari
- Department of Biochemistry & Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Charles Moritz
- Department of Biochemistry & Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Nicole Paczia
- Core Facility for Metabolomics and Small Molecule Mass Spectrometry, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Niña Socorro Cortina
- Department of Biochemistry & Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany.,LiVeritas Biosciences, Inc., 432N Canal St.; Ste. 20, South San Francisco, CA, 94080, USA
| | - Jean-Loup Faulon
- Micalis Institute, INRAE, AgroParisTech, University of Paris-Saclay, Jouy-en-Josas, France.,Genomique Metabolique, Genoscope, Institut Francois Jacob, CEA, CNRS, Univ Evry, University of Paris-Saclay, Evry, France.,Manchester Institute of Biotechnology, SYNBIOCHEM center, School of Chemistry, The University of Manchester, Manchester, UK
| | - Tobias J Erb
- Department of Biochemistry & Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany. .,SYNMIKRO Center of Synthetic Microbiology, Marburg, Germany.
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19
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Sáez Moreno D, Udi Q, Azeredo J, Domingues L. Towards T7 RNA polymerase (T7RNAP)-based expression system in yeast: challenges and opportunities. Bioengineered 2022; 13:14947-14959. [PMID: 37105766 DOI: 10.1080/21655979.2023.2180579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023] Open
Abstract
During the last decades, we have witnessed unprecedented advances in biological engineering and synthetic biology. These disciplines aim to take advantage of gene pathway regulation and gene expression in different organisms, to enable cells to perform desired functions. Yeast has been widely utilized as a model for the study of eukaryotic protein expression while bacteriophage T7RNAP and its promoter constitute the preferred system for prokaryotic protein expression (such as pET-based expression systems). The ability to integrate a T7RNAP-based expression system in yeast could allow for a better understanding of gene regulation in eukaryotic cells, and potentially increase the efficiency and processivity of yeast as an expression system. However, the attempts for the creation of such a system have been unsuccessful to date. This review aims to: (i) summarize the efforts that, for many years, have been devoted to the creation of a T7RNAP-based yeast expression system and ii) provide an overview of the latest advances in knowledge of eukaryotic transcription and translation that could lead to the construction of a successful T7RNAP expression system in yeast. The completion of this new expression system would allow to further expand the toolkit of yeast in synthetic biology and ultimately contribute to boost yeast usage as a key cell factory in sustainable biorefinery and circular economy.
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Affiliation(s)
- David Sáez Moreno
- CEB-Centre of Biological Engineering, University of Minho, 4710-057, Braga, Portugal
- LABBELS-Associate Laboratory, 4835-198, Guimarães, Braga, Portugal
| | - Qimron Udi
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Joana Azeredo
- CEB-Centre of Biological Engineering, University of Minho, 4710-057, Braga, Portugal
- LABBELS-Associate Laboratory, 4835-198, Guimarães, Braga, Portugal
| | - Lucília Domingues
- CEB-Centre of Biological Engineering, University of Minho, 4710-057, Braga, Portugal
- LABBELS-Associate Laboratory, 4835-198, Guimarães, Braga, Portugal
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20
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Novel switchable ECF sigma factor transcription system for improving thaxtomin A production in Streptomyces. Synth Syst Biotechnol 2022; 7:972-981. [PMID: 35756964 PMCID: PMC9194655 DOI: 10.1016/j.synbio.2022.05.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Revised: 05/30/2022] [Accepted: 05/31/2022] [Indexed: 11/23/2022] Open
Abstract
The application of the valuable natural product thaxtomin A, a potent bioherbicide from the potato scab pathogenic Streptomyces strains, has been greatly hindered by the low yields from its native producers. Here, we developed an orthogonal transcription system, leveraging extra-cytoplasmic function (ECF) sigma (σ) factor 17 (ECF17) and its cognate promoter Pecf17, to express the thaxtomin gene cluster and improve the production of thaxtomin A. The minimal Pecf17 promoter was determined, and a Pecf17 promoter library with a wide range of strengths was constructed. Furthermore, a cumate inducible system was developed for precise temporal control of the ECF17 transcription system in S. venezuelae ISP5230. Theoretically, the switchable ECF17 transcription system could reduce the unwanted influences from host and alleviate the burdens introduced by overexpression of heterologous genes. The yield of thaxtomin A was significantly improved to 202.1 ± 15.3 μ g/mL using the switchable ECF17 transcription system for heterologous expression of the thaxtomin gene cluster in S. venezuelae ISP5230. Besides, the applicability of this transcription system was also tested in Streptomyces albus J1074, and the titer of thaxtomin A was raised to as high as 239.3 ± 30.6 μg/mL. Therefore, the inducible ECF17 transcription system could serve as a complement of the generally used transcription systems based on strong native constitutive promoters and housekeeping σ factors for the heterologous expression of valuable products in diverse Streptomyces hosts.
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21
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Sulser S, Vucicevic A, Bellini V, Moritz R, Delavat F, Sentchilo V, Carraro N, van der Meer JR. A bistable prokaryotic differentiation system underlying development of conjugative transfer competence. PLoS Genet 2022; 18:e1010286. [PMID: 35763548 PMCID: PMC9286271 DOI: 10.1371/journal.pgen.1010286] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 07/15/2022] [Accepted: 06/08/2022] [Indexed: 12/21/2022] Open
Abstract
The mechanisms and impact of horizontal gene transfer processes to distribute gene functions with potential adaptive benefit among prokaryotes have been well documented. In contrast, little is known about the life-style of mobile elements mediating horizontal gene transfer, whereas this is the ultimate determinant for their transfer fitness. Here, we investigate the life-style of an integrative and conjugative element (ICE) within the genus Pseudomonas that is a model for a widespread family transmitting genes for xenobiotic compound metabolism and antibiotic resistances. Previous work showed bimodal ICE activation, but by using single cell time-lapse microscopy coupled to combinations of chromosomally integrated single copy ICE promoter-driven fluorescence reporters, RNA sequencing and mutant analysis, we now describe the complete regulon leading to the arisal of differentiated dedicated transfer competent cells. The regulon encompasses at least three regulatory nodes and five (possibly six) further conserved gene clusters on the ICE that all become expressed under stationary phase conditions. Time-lapse microscopy indicated expression of two regulatory nodes (i.e., bisR and alpA-bisDC) to precede that of the other clusters. Notably, expression of all clusters except of bisR was confined to the same cell subpopulation, and was dependent on the same key ICE regulatory factors. The ICE thus only transfers from a small fraction of cells in a population, with an estimated proportion of between 1.7–4%, which express various components of a dedicated transfer competence program imposed by the ICE, and form the centerpiece of ICE conjugation. The components mediating transfer competence are widely conserved, underscoring their selected fitness for efficient transfer of this class of mobile elements. Horizontal gene transfer processes among prokaryotes have raised wide interest, which is attested by broad public health concern of rapid spread of antibiotic resistances. However, we typically take for granted that horizontal transfer is the result of some underlying spontaneous low frequency event, but this is not necessarily the case. As we show here, mobile genetic elements from the class of integrative and conjugative elements (ICEs) impose a coordinated program on the host cell in order to transfer, leading to an exclusive differentiated set of transfer competent cells. We base our conclusions on single cell microscopy studies to compare the rare activation of ICE promoters in individual cells in bacterial populations, and on mutant and RNA-seq analysis to show their dependency on ICE factors. This is an important finding because it implies that conjugation itself is subject to natural selection, which would lead to selection of fitter elements that transfer better or become more widespread.
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Affiliation(s)
- Sandra Sulser
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Andrea Vucicevic
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Veronica Bellini
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Roxane Moritz
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - François Delavat
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Vladimir Sentchilo
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Nicolas Carraro
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Jan Roelof van der Meer
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
- * E-mail:
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22
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Soudier P, Rodriguez Pinzon D, Reif-Trauttmansdorff T, Hijazi H, Cherrière M, Goncalves Pereira C, Blaise D, Pispisa M, Saint-Julien A, Hamlet W, Nguevo M, Gomes E, Belkhelfa S, Niarakis A, Kushwaha M, Grigoras I. Toehold switch based biosensors for sensing the highly trafficked rosewood Dalbergia maritima. Synth Syst Biotechnol 2022; 7:791-801. [PMID: 35415278 PMCID: PMC8976095 DOI: 10.1016/j.synbio.2022.03.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 02/28/2022] [Accepted: 03/14/2022] [Indexed: 01/05/2023] Open
Abstract
Nucleic acid sensing is a 3 decades old but still challenging area of application for different biological sub-domains, from pathogen detection to single cell transcriptomics analysis. The many applications of nucleic acid detection and identification are mostly carried out by PCR techniques, sequencing, and their derivatives used at large scale. However, these methods’ limitations on speed, cost, complexity and specificity have motivated the development of innovative detection methods among which nucleic acid biosensing technologies seem promising. Toehold switches are a particular class of RNA sensing devices relying on a conformational switch of secondary structure induced by the pairing of the detected trigger RNA with a de novo designed synthetic sensing mRNA molecule. Here we describe a streamlined methodology enabling the development of such a sensor for the RNA-mediated detection of an endangered plant species in a cell-free reaction system. We applied this methodology to help identify the rosewood Dalbergia maritima, a highly trafficked wood, whose protection is limited by the capacity of the authorities to distinguish protected logs from other unprotected but related species. The streamlined pipeline presented in this work is a versatile framework enabling cheap and rapid development of new sensors for custom RNA detection.
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23
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Putzeys L, Boon M, Lammens EM, Kuznedelov K, Severinov K, Lavigne R. Development of ONT-cappable-seq to unravel the transcriptional landscape of Pseudomonas phages. Comput Struct Biotechnol J 2022; 20:2624-2638. [PMID: 35685363 PMCID: PMC9163698 DOI: 10.1016/j.csbj.2022.05.034] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 05/16/2022] [Accepted: 05/16/2022] [Indexed: 11/28/2022] Open
Affiliation(s)
- Leena Putzeys
- Department of Biosystems, Laboratory of Gene Technology, KU Leuven, Leuven 3001, Belgium
| | - Maarten Boon
- Department of Biosystems, Laboratory of Gene Technology, KU Leuven, Leuven 3001, Belgium
| | - Eveline-Marie Lammens
- Department of Biosystems, Laboratory of Gene Technology, KU Leuven, Leuven 3001, Belgium
| | | | | | - Rob Lavigne
- Department of Biosystems, Laboratory of Gene Technology, KU Leuven, Leuven 3001, Belgium
- Corresponding author.
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24
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Chee WKD, Yeoh JW, Dao VL, Poh CL. Highly Reversible Tunable Thermal-Repressible Split-T7 RNA Polymerases (Thermal-T7RNAPs) for Dynamic Gene Regulation. ACS Synth Biol 2022; 11:921-937. [PMID: 35089710 DOI: 10.1021/acssynbio.1c00545] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Temperature is a physical cue that is easy to apply, allowing cellular behaviors to be controlled in a contactless and dynamic manner via heat-inducible/repressible systems. However, existing heat-repressible systems are limited in number, rely on thermal sensitive mRNA or transcription factors that function at low temperatures, lack tunability, suffer delays, and are overly complex. To provide an alternative mode of thermal regulation, we developed a library of compact, reversible, and tunable thermal-repressible split-T7 RNA polymerase systems (Thermal-T7RNAPs), which fused temperature-sensitive domains of Tlpa protein with split-T7RNAP to enable direct thermal control of the T7RNAP activity between 30 and 42 °C. We generated a large mutant library with varying thermal performances via an automated screening framework to extend temperature tunability. Lastly, using the mutants, novel thermal logic circuitry was implemented to regulate cell growth and achieve active thermal control of the cell proportions within co-cultures. Overall, this technology expanded avenues for thermal control in biotechnology applications.
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Affiliation(s)
- Wai Kit David Chee
- Department of Biomedical Engineering, College of Design and Engineering, National University of Singapore, 4 Engineering Drive 3, 117583 Singapore
- NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), National University of Singapore, 28 Medical Drive, 117456 Singapore
| | - Jing Wui Yeoh
- Department of Biomedical Engineering, College of Design and Engineering, National University of Singapore, 4 Engineering Drive 3, 117583 Singapore
- NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), National University of Singapore, 28 Medical Drive, 117456 Singapore
| | - Viet Linh Dao
- Department of Biomedical Engineering, College of Design and Engineering, National University of Singapore, 4 Engineering Drive 3, 117583 Singapore
- NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), National University of Singapore, 28 Medical Drive, 117456 Singapore
| | - Chueh Loo Poh
- Department of Biomedical Engineering, College of Design and Engineering, National University of Singapore, 4 Engineering Drive 3, 117583 Singapore
- NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), National University of Singapore, 28 Medical Drive, 117456 Singapore
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25
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Lammens EM, Boon M, Grimon D, Briers Y, Lavigne R. SEVAtile: a standardised DNA assembly method optimised for Pseudomonas. Microb Biotechnol 2021; 15:370-386. [PMID: 34651450 PMCID: PMC8719830 DOI: 10.1111/1751-7915.13922] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 07/29/2021] [Accepted: 09/01/2021] [Indexed: 11/25/2022] Open
Abstract
To meet the needs of synthetic biologists, DNA assembly methods have transformed from simple 'cut-and-paste' procedures to highly advanced, standardised assembly techniques. Implementing these standardised DNA assembly methods in biotechnological research conducted in non-model hosts, including Pseudomonas putida and Pseudomonas aeruginosa, could greatly benefit reproducibility and predictability of experimental results. SEVAtile is a Type IIs-based assembly approach, which enables the rapid and standardised assembly of genetic parts - or tiles - to create genetic circuits in the established SEVA-vector backbone. Contrary to existing DNA assembly methods, SEVAtile is an easy and straightforward method, which is compatible with any vector, both SEVA- and non-SEVA. To prove the efficiency of the SEVAtile method, a three-vector system was successfully generated to independently co-express three different proteins in P. putida and P. aeruginosa. More specifically, one of the vectors, pBGDes, enables genomic integration of assembled circuits in the Tn7 landing site, while self-replicatory vectors pSTDesX and pSTDesR enable inducible expression from the XylS/Pm and RhaRS/PrhaB expression systems, respectively. Together, we hope these vector systems will support research in both the microbial SynBio and Pseudomonas field.
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Affiliation(s)
- Eveline-Marie Lammens
- Department of Biosystems, Laboratory of Gene Technology, KULeuven, Kasteelpark Arenberg 21 Box 2462, Leuven, 3001, Belgium
| | - Maarten Boon
- Department of Biosystems, Laboratory of Gene Technology, KULeuven, Kasteelpark Arenberg 21 Box 2462, Leuven, 3001, Belgium
| | - Dennis Grimon
- Laboratory of Applied Biotechnology, Department of Biotechnology, Ghent University, Valentin Vaerwyckweg 1, Gent, 9000, Belgium
| | - Yves Briers
- Laboratory of Applied Biotechnology, Department of Biotechnology, Ghent University, Valentin Vaerwyckweg 1, Gent, 9000, Belgium
| | - Rob Lavigne
- Department of Biosystems, Laboratory of Gene Technology, KULeuven, Kasteelpark Arenberg 21 Box 2462, Leuven, 3001, Belgium
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26
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Zhu T, Yao D, Li D, Xu H, Jia S, Bi C, Cai J, Zhu X, Zhang X. Multiple strategies for metabolic engineering of Escherichia coli for efficient production of glycolate. Biotechnol Bioeng 2021; 118:4699-4707. [PMID: 34491579 DOI: 10.1002/bit.27934] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 08/20/2021] [Accepted: 08/27/2021] [Indexed: 01/12/2023]
Abstract
Glycolate is a bulk chemical with wide applications in the textile, food processing, and pharmaceutical industries. Glycolate can be produced from glucose via the glycolysis and glyoxylate shunt pathways, followed by reduction to glycolate. However, two problems limit the productivity and yield of glycolate when using glucose as the sole carbon source. The first is a cofactor imbalance in the production of glycolate from glucose via the glycolysis pathway, since NADPH is required for glycolate production, while glycolysis generates NADH. To rectify this imbalance, the NADP+ -dependent glyceraldehyde 3-phosphate dehydrogenase GapC from Clostridium acetobutylicum was introduced to generate NADPH instead of NADH in the oxidation of glyceraldehyde 3-phosphate during glycolysis. The soluble transhydrogenase SthA was further eliminated to conserve NADPH by blocking its conversion into NADH. The second problem is an unfavorable carbon flux distribution between the tricarboxylic acid cycle and the glyoxylate shunt. To solve this problem, isocitrate dehydrogenase (ICDH) was eliminated to increase the carbon flux of glyoxylate and thereby improve the glycolate titer. After engineering through the integration of gapC, combined with the inactivation of ICDH, SthA, and by-product pathways, as well as the upregulation of the two key enzymes isocitrate lyase (encoding by aceA), and glyoxylate reductase (encoding by ycdW), the glycolate titer increased to 5.3 g/L with a yield of 1.89 mol/mol glucose. Moreover, an optimized fed-batch fermentation reached a titer of 41 g/L with a yield of 1.87 mol/mol glucose after 60 h.
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Affiliation(s)
- Tong Zhu
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China.,Tianjin Institute of Industrial Biotechnology, Chinese of Academy of Sciences, Tianjin, China.,Key Laboratory of Systems Microbial Biotechnology, Chinese of Academy of Sciences, Tianjin, China
| | - Die Yao
- Tianjin Institute of Industrial Biotechnology, Chinese of Academy of Sciences, Tianjin, China.,Key Laboratory of Systems Microbial Biotechnology, Chinese of Academy of Sciences, Tianjin, China.,Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Di Li
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China.,Tianjin Institute of Industrial Biotechnology, Chinese of Academy of Sciences, Tianjin, China.,Key Laboratory of Systems Microbial Biotechnology, Chinese of Academy of Sciences, Tianjin, China
| | - Hongtao Xu
- Tianjin Institute of Industrial Biotechnology, Chinese of Academy of Sciences, Tianjin, China.,Key Laboratory of Systems Microbial Biotechnology, Chinese of Academy of Sciences, Tianjin, China
| | - Shiru Jia
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Changhao Bi
- Tianjin Institute of Industrial Biotechnology, Chinese of Academy of Sciences, Tianjin, China.,Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Jun Cai
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Xinna Zhu
- Tianjin Institute of Industrial Biotechnology, Chinese of Academy of Sciences, Tianjin, China.,Key Laboratory of Systems Microbial Biotechnology, Chinese of Academy of Sciences, Tianjin, China
| | - Xueli Zhang
- Tianjin Institute of Industrial Biotechnology, Chinese of Academy of Sciences, Tianjin, China.,Key Laboratory of Systems Microbial Biotechnology, Chinese of Academy of Sciences, Tianjin, China
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27
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Dhakal D, Chen M, Luesch H, Ding Y. Heterologous production of cyanobacterial compounds. J Ind Microbiol Biotechnol 2021; 48:6119914. [PMID: 33928376 PMCID: PMC8210676 DOI: 10.1093/jimb/kuab003] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 11/17/2020] [Indexed: 12/29/2022]
Abstract
Cyanobacteria produce a plethora of compounds with unique chemical structures and diverse biological activities. Importantly, the increasing availability of cyanobacterial genome sequences and the rapid development of bioinformatics tools have unraveled the tremendous potential of cyanobacteria in producing new natural products. However, the discovery of these compounds based on cyanobacterial genomes has progressed slowly as the majority of their corresponding biosynthetic gene clusters (BGCs) are silent. In addition, cyanobacterial strains are often slow-growing, difficult for genetic engineering, or cannot be cultivated yet, limiting the use of host genetic engineering approaches for discovery. On the other hand, genetically tractable hosts such as Escherichia coli, Actinobacteria, and yeast have been developed for the heterologous expression of cyanobacterial BGCs. More recently, there have been increased interests in developing model cyanobacterial strains as heterologous production platforms. Herein, we present recent advances in the heterologous production of cyanobacterial compounds in both cyanobacterial and noncyanobacterial hosts. Emerging strategies for BGC assembly, host engineering, and optimization of BGC expression are included for fostering the broader applications of synthetic biology tools in the discovery of new cyanobacterial natural products.
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Affiliation(s)
- Dipesh Dhakal
- Department of Medicinal Chemistry, Center for Natural Products, Drug Discovery and Development, University of Florida, Gainesville, FL 31610, USA
| | - Manyun Chen
- Department of Medicinal Chemistry, Center for Natural Products, Drug Discovery and Development, University of Florida, Gainesville, FL 31610, USA
| | - Hendrik Luesch
- Department of Medicinal Chemistry, Center for Natural Products, Drug Discovery and Development, University of Florida, Gainesville, FL 31610, USA
| | - Yousong Ding
- Department of Medicinal Chemistry, Center for Natural Products, Drug Discovery and Development, University of Florida, Gainesville, FL 31610, USA
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28
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Becker K, Meyer A, Roberts TM, Panke S. Plasmid replication based on the T7 origin of replication requires a T7 RNAP variant and inactivation of ribonuclease H. Nucleic Acids Res 2021; 49:8189-8198. [PMID: 34255845 PMCID: PMC8373140 DOI: 10.1093/nar/gkab596] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Revised: 06/22/2021] [Accepted: 07/09/2021] [Indexed: 01/09/2023] Open
Abstract
T7 RNA polymerase (RNAP) is a valuable tool in biotechnology, basic research and synthetic biology due to its robust, efficient and selective transcription of genes. Here, we expand the scope of T7 RNAP to include plasmid replication. We present a novel type of plasmid, termed T7 ori plasmids that replicate, in an engineered Escherichia coli, with a T7 phage origin as the sole origin of replication. We find that while the T7 replication proteins; T7 DNA polymerase, T7 single-stranded binding proteins and T7 helicase-primase are dispensable for replication, T7 RNAP is required, although dependent on a T7 RNAP variant with reduced activity. We also find that T7 RNAP-dependent replication of T7 ori plasmids requires the inactivation of cellular ribonuclease H. We show that the system is portable among different plasmid architectures and ribonuclease H-inactivated E. coli strains. Finally, we find that the copy number of T7 ori plasmids can be tuned based on the induction level of RNAP. Altogether, this study assists in the choice of an optimal genetic tool by providing a novel plasmid that requires T7 RNAP for replication.
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Affiliation(s)
- Katja Becker
- Department of Biosystems Science and Engineering, ETH Zurich, Basel 4058, Switzerland
| | - Andreas Meyer
- Department of Biosystems Science and Engineering, ETH Zurich, Basel 4058, Switzerland.,FGen GmbH, Basel 4057, Switzerland
| | | | - Sven Panke
- Department of Biosystems Science and Engineering, ETH Zurich, Basel 4058, Switzerland
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29
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MacDonald IC, Seamons TR, Emmons JC, Javdan SB, Deans TL. Enhanced regulation of prokaryotic gene expression by a eukaryotic transcriptional activator. Nat Commun 2021; 12:4109. [PMID: 34226549 PMCID: PMC8257575 DOI: 10.1038/s41467-021-24434-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 06/17/2021] [Indexed: 11/23/2022] Open
Abstract
Expanding the genetic toolbox for prokaryotic synthetic biology is a promising strategy for enhancing the dynamic range of gene expression and enabling new engineered applications for research and biomedicine. Here, we reverse the current trend of moving genetic parts from prokaryotes to eukaryotes and demonstrate that the activating eukaryotic transcription factor QF and its corresponding DNA-binding sequence can be moved to E. coli to introduce transcriptional activation, in addition to tight off states. We further demonstrate that the QF transcription factor can be used in genetic devices that respond to low input levels with robust and sustained output signals. Collectively, we show that eukaryotic gene regulator elements are functional in prokaryotes and establish a versatile and broadly applicable approach for constructing genetic circuits with complex functions. These genetic tools hold the potential to improve biotechnology applications for medical science and research. Expanded toolkits for prokaryotic synthetic biology can enhance the dynamic range of gene expression. Here the authors move the eukaryotic transcription factor QF into E. coli and integrate it into genetic devices.
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Affiliation(s)
- I Cody MacDonald
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, USA
| | - Travis R Seamons
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, USA
| | - Jonathan C Emmons
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, USA
| | - Shwan B Javdan
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, USA
| | - Tara L Deans
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, USA.
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30
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Wang Y, Li Q, Tian P, Tan T. Charting the landscape of RNA polymerases to unleash their potential in strain improvement. Biotechnol Adv 2021; 54:107792. [PMID: 34216775 DOI: 10.1016/j.biotechadv.2021.107792] [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: 02/16/2021] [Revised: 05/28/2021] [Accepted: 06/26/2021] [Indexed: 11/19/2022]
Abstract
One major mission of microbial cell factory is overproduction of desired chemicals. To this end, it is necessary to orchestrate enzymes that affect metabolic fluxes. However, only modification of a small number of enzymes in most cases cannot maximize desired metabolites, and global regulation is required. Of myriad enzymes influencing global regulation, RNA polymerase (RNAP) may be the most versatile enzyme in biological realm because it not only serves as the workhorse of central dogma but also participates in a plethora of biochemical events. In fact, recent years have witnessed extensive exploitation of RNAPs for phenotypic engineering. While a few impressive reviews showcase the structures and functionalities of RNAPs, this review not only summarizes the state-of-the-art advance in the structures of RNAPs but also points out their enormous potentials in metabolic engineering and synthetic biology. This review aims to provide valuable insights for strain improvement.
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Affiliation(s)
- Ye Wang
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, PR China
| | - Qingyang Li
- School of Food Science and Engineering, South China University of Technology, Guangzhou 510641, PR China
| | - Pingfang Tian
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, PR China.
| | - Tianwei Tan
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, PR China
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31
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Schnabel T, Sattely E. Engineering Posttranslational Regulation of Glutamine Synthetase for Controllable Ammonia Production in the Plant Symbiont Azospirillum brasilense. Appl Environ Microbiol 2021; 87:e0058221. [PMID: 33962983 PMCID: PMC8231714 DOI: 10.1128/aem.00582-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 04/27/2021] [Indexed: 11/20/2022] Open
Abstract
Nitrogen requirements for modern agriculture far exceed the levels of bioavailable nitrogen in most arable soils. As a result, the addition of nitrogen fertilizer is necessary to sustain productivity and yields, especially for cereal crops, the planet's major calorie suppliers. Given the unsustainability of industrial fertilizer production and application, engineering biological nitrogen fixation directly at the roots of plants has been a grand challenge for biotechnology. Here, we designed and tested a potentially broadly applicable metabolic engineering strategy for the overproduction of ammonia in the diazotrophic symbiont Azospirillum brasilense. Our approach is based on an engineered unidirectional adenylyltransferase (uAT) that posttranslationally modifies and deactivates glutamine synthetase (GS), a key regulator of nitrogen metabolism in the cell. We show that this circuit can be controlled inducibly, and we leveraged the inherent self-contained nature of our posttranslational approach to demonstrate that multicopy redundancy can improve strain evolutionary stability. uAT-engineered Azospirillum is capable of producing ammonia at rates of up to 500 μM h-1 unit of OD600 (optical density at 600 nm)-1. We demonstrated that when grown in coculture with the model monocot Setaria viridis, these strains increase the biomass and chlorophyll content of plants up to 54% and 71%, respectively, relative to the wild type (WT). Furthermore, we rigorously demonstrated direct transfer of atmospheric nitrogen to extracellular ammonia and then plant biomass using isotopic labeling: after 14 days of cocultivation with engineered uAT strains, 9% of chlorophyll nitrogen in Setaria seedlings was derived from diazotrophically fixed dinitrogen, whereas no nitrogen was incorporated in plants cocultivated with WT controls. This rational design for tunable ammonia overproduction is modular and flexible, and we envision that it could be deployable in a consortium of nitrogen-fixing symbiotic diazotrophs for plant fertilization. IMPORTANCE Nitrogen is the most limiting nutrient in modern agriculture. Free-living diazotrophs, such as Azospirillum, are common colonizers of cereal grasses and have the ability to fix nitrogen but natively do not release excess ammonia. Here, we used a rational engineering approach to generate ammonia-excreting strains of Azospirillum. Our design features posttranslational control of highly conserved central metabolism, enabling tunability and flexibility of circuit placement. We found that our strains promote the growth and health of the model grass S. viridis and rigorously demonstrated that in comparison to WT controls, our engineered strains can transfer nitrogen from 15N2 gas to plant biomass. Unlike previously reported ammonia-producing mutants, our rationally designed approach easily lends itself to further engineering opportunities and has the potential to be broadly deployable.
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Affiliation(s)
- Tim Schnabel
- Department of Bioengineering, Stanford University, Stanford, California, USA
| | - Elizabeth Sattely
- Department of Chemical Engineering, Stanford University and HHMI, Stanford, California, USA
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32
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Zhao P, Tian P. Biosynthesis pathways and strategies for improving 3-hydroxypropionic acid production in bacteria. World J Microbiol Biotechnol 2021; 37:117. [PMID: 34128152 DOI: 10.1007/s11274-021-03091-6] [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: 03/13/2021] [Accepted: 06/08/2021] [Indexed: 12/01/2022]
Abstract
3-Hydroxypropionic acid (3-HP) represents an economically important platform compound from which a panel of bulk chemicals can be derived. Compared with petroleum-dependent chemical synthesis, bioproduction of 3-HP has attracted more attention due to utilization of renewable biomass. This review outlines bacterial production of 3-HP, covering aspects of host strains (e.g., Escherichia coli and Klebsiella pneumoniae), metabolic pathways, key enzymes, and hurdles hindering high-level production. Inspired by the state-of-the-art advances in metabolic engineering and synthetic biology, we come up with protocols to overcome the hurdles constraining 3-HP production. The protocols range from rewiring of metabolic networks, alleviation of metabolite toxicity, to dynamic control of cell size and density. Especially, this review highlights the substantial contribution of microbial growth to 3-HP production, as we recognize the synchronization between cell growth and 3-HP formation. Accordingly, we summarize the following growth-promoting strategies: (i) optimization of fermentation conditions; (ii) construction of gene circuits to alleviate feedback inhibition; (iii) recruitment of RNA polymerases to overexpress key enzymes which in turn boost cell growth and 3-HP production. Lastly, we propose metabolic engineering approaches to simplify downstream separation and purification. Overall, this review aims to portray a picture of bacterial production of 3-HP.
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Affiliation(s)
- Peng Zhao
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, 100029, People's Republic of China
| | - Pingfang Tian
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, 100029, People's Republic of China.
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33
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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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34
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Kim J, Quijano JF, Kim J, Yeung E, Murray RM. Synthetic logic circuits using RNA aptamer against T7 RNA polymerase. Biotechnol J 2021; 17:e2000449. [PMID: 33813787 DOI: 10.1002/biot.202000449] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 03/05/2021] [Accepted: 03/30/2021] [Indexed: 12/23/2022]
Abstract
Recent advances in nucleic acids engineering introduced several RNA-based regulatory components for synthetic gene circuits, expanding the toolsets to engineer organisms. In this work, we designed genetic circuits implementing an RNA aptamer previously described to have the capability of binding to the T7 RNA polymerase and inhibiting its activity in vitro. We first demonstrated the utility of the RNA aptamer in combination with programmable synthetic transcription networks in vitro. As a step to quickly assess the feasibility of aptamer functions in vivo, we tested the aptamer and its sequence variants in the cell-free expression system, verifying the aptamer functionality in the cell-free testbed. The expression of aptamer in E. coli demonstrated control over GFP expression driven by T7 RNA polymerase, indicating its ability to serve as building blocks for logic circuits and transcriptional cascades. This work elucidates the potential of T7 RNA polymerase aptamer as regulators for synthetic biological circuits and metabolic engineering.
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Affiliation(s)
- Jongmin Kim
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk, Republic of Korea.,Department of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
| | - Juan F Quijano
- Department of Biological Sciences, Columbia University, New York, New York, USA
| | - Jeongwon Kim
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk, Republic of Korea
| | - Enoch Yeung
- Department of Control and Dynamical Systems, California Institute of Technology, Pasadena, California, USA.,Department of Mechanical Engineering, University of California, Santa Barbara, California, USA
| | - Richard M Murray
- Department of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA.,Department of Control and Dynamical Systems, California Institute of Technology, Pasadena, California, USA
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35
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Yong C, Gyorgy A. Stability and Robustness of Unbalanced Genetic Toggle Switches in the Presence of Scarce Resources. Life (Basel) 2021; 11:271. [PMID: 33805212 PMCID: PMC8064337 DOI: 10.3390/life11040271] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 03/17/2021] [Accepted: 03/19/2021] [Indexed: 12/24/2022] Open
Abstract
While the vision of synthetic biology is to create complex genetic systems in a rational fashion, system-level behaviors are often perplexing due to the context-dependent dynamics of modules. One major source of context-dependence emerges due to the limited availability of shared resources, coupling the behavior of disconnected components. Motivated by the ubiquitous role of toggle switches in genetic circuits ranging from controlling cell fate differentiation to optimizing cellular performance, here we reveal how their fundamental dynamic properties are affected by competition for scarce resources. Combining a mechanistic model with nullcline-based stability analysis and potential landscape-based robustness analysis, we uncover not only the detrimental impacts of resource competition, but also how the unbalancedness of the switch further exacerbates them. While in general both of these factors undermine the performance of the switch (by pushing the dynamics toward monostability and increased sensitivity to noise), we also demonstrate that some of the unwanted effects can be alleviated by strategically optimized resource competition. Our results provide explicit guidelines for the context-aware rational design of toggle switches to mitigate our reliance on lengthy and expensive trial-and-error processes, and can be seamlessly integrated into the computer-aided synthesis of complex genetic systems.
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Affiliation(s)
- Chentao Yong
- Department of Chemical and Biological Engineering, New York University, New York, NY 10003, USA;
| | - Andras Gyorgy
- Department of Electrical and Computer Engineering, New York University Abu Dhabi, Abu Dhabi 129188, United Arab Emirates
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36
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Zhang Y, Ding W, Wang Z, Zhao H, Shi S. Development of Host-Orthogonal Genetic Systems for Synthetic Biology. Adv Biol (Weinh) 2021; 5:e2000252. [PMID: 33729696 DOI: 10.1002/adbi.202000252] [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: 09/03/2020] [Revised: 11/18/2020] [Indexed: 12/17/2022]
Abstract
The construction of a host-orthogonal genetic system can not only minimize the impact of host-specific nuances on fine-tuning of gene expression, but also expand cellular functions such as in vivo continuous evolution of genes based on an error-prone DNA polymerase. It represents an emerging powerful approach for making biology easier to engineer. In this review, the recent advances are described on the design of genetic systems that can be stably inherited in the host cells and are responsible for important biological processes including DNA replication, RNA transcription, protein translation, and gene regulation. Their applications in synthetic biology are summarized and the future challenges and opportunities are discussed in developing such systems.
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Affiliation(s)
- Yang Zhang
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China
| | - Wentao Ding
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China.,Key Laboratory of Food Nutrition and Safety (Tianjin University of Science and Technology) Ministry of Education, College of Food Engineering and Biotechnology, Tianjin University of Science and Technology, No. 29, 13th Avenue, TEDA, Tianjin, 300457, P. R. China
| | - Zhihui Wang
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China
| | - Huimin Zhao
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Shuobo Shi
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China
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37
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Stargardt P, Striedner G, Mairhofer J. Tunable expression rate control of a growth-decoupled T7 expression system by L-arabinose only. Microb Cell Fact 2021; 20:27. [PMID: 33522916 PMCID: PMC7852362 DOI: 10.1186/s12934-021-01512-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 01/07/2021] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Precise regulation of gene expression is of utmost importance for the production of complex membrane proteins (MP), enzymes or other proteins toxic to the host cell. In this article we show that genes under control of a normally Isopropyl β-D-1-thiogalactopyranoside (IPTG)-inducible PT7-lacO promoter can be induced solely with L-arabinose in a newly constructed Escherichia coli expression host BL21-AI<gp2>, a strain based on the recently published approach of bacteriophage inspired growth-decoupled recombinant protein production. RESULTS Here, we show that BL21-AI<gp2> is able to precisely regulate protein production rates on a cellular level in an L-arabinose concentration-dependent manner and simultaneously allows for reallocation of metabolic resources due to L-arabinose induced growth decoupling by the phage derived inhibitor peptide Gp2. We have successfully characterized the system under relevant fed-batch like conditions in microscale cultivation (800 µL) and generated data proofing a relevant increase in specific yields for 6 different Escherichia coli derived MP-GFP fusion proteins by using online-GFP signals, FACS analysis, SDS-PAGE and western blotting. CONCLUSIONS In all cases tested, BL21-AI<gp2> outperformed the parental strain BL21-AI, operated in growth-associated production mode. Specific MP-GFP fusion proteins yields have been improved up to 2.7-fold. Therefore, this approach allows for fine tuning of MP production or expression of multi-enzyme pathways where e.g. particular stoichiometries have to be met to optimize product flux.
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Affiliation(s)
| | - Gerald Striedner
- Department of Biotechnology, University of Natural Resources and Life Sciences (BOKU), Muthgasse 18, 1190, Vienna, Austria
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38
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Costello A, Badran AH. Synthetic Biological Circuits within an Orthogonal Central Dogma. Trends Biotechnol 2021; 39:59-71. [PMID: 32586633 PMCID: PMC7746572 DOI: 10.1016/j.tibtech.2020.05.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 05/28/2020] [Accepted: 05/29/2020] [Indexed: 12/16/2022]
Abstract
Synthetic biology strives to reliably control cellular behavior, typically in the form of user-designed interactions of biological components to produce a predetermined output. Engineered circuit components are frequently derived from natural sources and are therefore often hampered by inadvertent interactions with host machinery, most notably within the host central dogma. Reliable and predictable gene circuits require the targeted reduction or elimination of these undesirable interactions to mitigate negative consequences on host fitness and develop context-independent bioactivities. Here, we review recent advances in biological orthogonalization, namely the insulation of researcher-dictated bioactivities from host processes, with a focus on systematic developments that may culminate in the creation of an orthogonal central dogma and novel cellular functions.
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Affiliation(s)
- Alan Costello
- Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA
| | - Ahmed H Badran
- Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA.
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39
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Sakono M, Hayakawa R. Repressor-Like On-Off Regulation of Protein Expression by the DNA-Binding Transcription Activator-Like Effector in T7 Promoter-Based Cell-Free Protein Synthesis. Chembiochem 2020; 22:888-893. [PMID: 33085169 DOI: 10.1002/cbic.202000591] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Revised: 10/21/2020] [Indexed: 01/24/2023]
Abstract
The aim of this study was to develop a transcription activator-like effector (TALE)-based technology to regulate protein synthesis in cell-free systems. We attempted to regulate the T7 promoter system, which has no natural mechanism of expression control, and sought to arbitrarily induce protein expression through the formation and dissociation of TALE and target DNA complexes. Protein synthesis was performed in a cell-free system in the presence of TALE, which recognized and bound to a sequence upstream of the T7 promoter, and protein expression was suppressed by approximately 80 % compared to in the absence of TALE. This suggests that masking part of the promoter region strongly suppresses protein synthesis. Additionally, competitive inhibition of TALE binding to the target DNA template led to protein synthesis levels that were equivalent to the levels in the absence of TALE. Our results demonstrate that DNA recognition by TALE can regulate the expression of the T7 promoter system.
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Affiliation(s)
- Masafumi Sakono
- Department of Applied Chemistry Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama, 930-8555, Japan
| | - Ryoto Hayakawa
- Department of Applied Chemistry Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama, 930-8555, Japan
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40
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Van Brempt M, Clauwaert J, Mey F, Stock M, Maertens J, Waegeman W, De Mey M. Predictive design of sigma factor-specific promoters. Nat Commun 2020; 11:5822. [PMID: 33199691 PMCID: PMC7670410 DOI: 10.1038/s41467-020-19446-w] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 10/13/2020] [Indexed: 02/07/2023] Open
Abstract
To engineer synthetic gene circuits, molecular building blocks are developed which can modulate gene expression without interference, mutually or with the host's cell machinery. As the complexity of gene circuits increases, automated design tools and tailored building blocks to ensure perfect tuning of all components in the network are required. Despite the efforts to develop prediction tools that allow forward engineering of promoter transcription initiation frequency (TIF), such a tool is still lacking. Here, we use promoter libraries of E. coli sigma factor 70 (σ70)- and B. subtilis σB-, σF- and σW-dependent promoters to construct prediction models, capable of both predicting promoter TIF and orthogonality of the σ-specific promoters. This is achieved by training a convolutional neural network with high-throughput DNA sequencing data from fluorescence-activated cell sorted promoter libraries. This model functions as the base of the online promoter design tool (ProD), providing tailored promoters for tailored genetic systems.
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Affiliation(s)
- Maarten Van Brempt
- Centre for Synthetic Biology (CSB), Department of Biotechnology, Ghent University, 9000, Ghent, Belgium
| | - Jim Clauwaert
- KERMIT, Department of Data Analysis and Mathematical Modelling, Ghent University, 9000, Ghent, Belgium
| | - Friederike Mey
- Centre for Synthetic Biology (CSB), Department of Biotechnology, Ghent University, 9000, Ghent, Belgium
| | - Michiel Stock
- KERMIT, Department of Data Analysis and Mathematical Modelling, Ghent University, 9000, Ghent, Belgium
| | - Jo Maertens
- Centre for Synthetic Biology (CSB), Department of Biotechnology, Ghent University, 9000, Ghent, Belgium
| | - Willem Waegeman
- KERMIT, Department of Data Analysis and Mathematical Modelling, Ghent University, 9000, Ghent, Belgium
| | - Marjan De Mey
- Centre for Synthetic Biology (CSB), Department of Biotechnology, Ghent University, 9000, Ghent, Belgium.
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Chen X, Zhang C, Lindley ND. Metabolic Engineering Strategies for Sustainable Terpenoid Flavor and Fragrance Synthesis. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2020; 68:10252-10264. [PMID: 31865696 DOI: 10.1021/acs.jafc.9b06203] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Terpenoids derived from plant material are widely applied in the flavor and fragrance industry. Traditional extraction methods are unsustainable, but microbial synthesis offers a promising solution to attain efficient production of natural-identical terpenoids. Overproduction of terpenoids in microbes requires careful balancing of the synthesis pathway constituents within the constraints of host cell metabolism. Advances in metabolic engineering have greatly facilitated overcoming the challenges of achieving high titers, rates, and yields (TRYs). The review summarizes recent development in the molecular biology toolbox to achieve high TRYs for terpenoid biosynthesis, mainly in the two industrial platform microorganisms: Escherichia coli and Saccharomyces cerevisiae. The biosynthetic pathways, including alternative pathway designs, are briefly introduced, followed by recently developed methodologies used for pathway, genome, and strain optimization. Integrated applications of these tools are important to achieve high "TRYs" of terpenoid production and pave the way for translating laboratory research into successful commercial manufacturing.
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Affiliation(s)
- Xixian Chen
- Biotransformation Innovation Platform, Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Singapore 138673
| | - Congqiang Zhang
- Biotransformation Innovation Platform, Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Singapore 138673
| | - Nicholas D Lindley
- Biotransformation Innovation Platform, Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Singapore 138673
- TBI, Université de Toulouse, CNRS, INRA, INSA,31077 Toulouse, France
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42
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Yu Y, Shao M, Li D, Fan F, Xu H, Lu F, Bi C, Zhu X, Zhang X. Construction of a carbon-conserving pathway for glycolate production by synergetic utilization of acetate and glucose in Escherichia coli. Metab Eng 2020; 61:152-159. [PMID: 32531344 DOI: 10.1016/j.ymben.2020.06.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 05/05/2020] [Accepted: 06/01/2020] [Indexed: 12/18/2022]
Abstract
Glycolate is a bulk chemical which has been widely used in textile, food processing, and pharmaceutical industries. Glycolate can be produced from sugars by microbial fermentation. However, when using glucose as the sole carbon source, the theoretical maximum carbon molar yield of glycolate is 0.67 mol/mol due to the loss of carbon as CO2. In this study, a synergetic system for simultaneous utilization of acetate and glucose was designed to increase the carbon yield. The main function of glucose is to provide NADPH while acetate to provide the main carbon backbone for glycolate production. Theoretically, 1 glucose and 5 acetate can produce 6 glycolate, and the carbon molar yield can be increased to 0.75 mol/mol. The whole synthetic pathway was divided into two modules, one for converting acetate to glycolate and another to utilize glucose to provide NADPH. After engineering module I through activation of acs, gltA, aceA and ycdW, glycolate titer increased from 0.07 to 2.16 g/L while glycolate yields increased from 0.04 to 0.35 mol/mol-acetate and from 0.03 to 1.04 mol/mol-glucose. Module II was then engineered to increase NADPH supply. Through deletion of pfkA, pfkB, ptsI and sthA genes as well as upregulating zwf, pgl and tktA, glycolate titer increased from 2.16 to 4.86 g/L while glycolate yields increased from 0.35 to 0.82 mol/mol-acetate and from 1.04 to 6.03 mol/mol-glucose. The activities of AceA and YcdW were further increased to pull the carbon flux to glycolate, which increased glycolate yield from 0.82 to 0.92 mol/mol-acetate. Fed-batch fermentation of the final strain NZ-Gly303 produced 73.3 g/L glycolate with a productivity of 1.04 g/(L·h). The acetate to glycolate yield was 0.85 mol/mol (1.08 g/g), while glucose to glycolate yield was 6.1 mol/mol (2.58 g/g). The total carbon molar yield was 0.60 mol/mol, which reached 80% of the theoretical value.
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Affiliation(s)
- Yong Yu
- University of Chinese Academy of Sciences, Beijing, 100049, 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, China
| | - Mengyao Shao
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China; Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China; College of Biotechnology, Tianjin University of Sciences and Technology, Tianjin, 300457, China
| | - Di Li
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China; Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China; College of Biotechnology, Tianjin University of Sciences and Technology, Tianjin, 300457, China
| | - Feiyu Fan
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China; Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
| | - Hongtao Xu
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China; Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
| | - Fuping Lu
- College of Biotechnology, Tianjin University of Sciences and Technology, Tianjin, 300457, China
| | - Changhao Bi
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China; Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
| | - Xinna Zhu
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China; Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China.
| | - Xueli 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, China.
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43
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Zhao P, Ren M, Ge X, Tian P, Tan T. Development of orthogonal T7 expression system in
Klebsiella pneumoniae. Biotechnol Bioeng 2020; 117:2446-2459. [DOI: 10.1002/bit.27434] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 05/10/2020] [Accepted: 05/17/2020] [Indexed: 11/11/2022]
Affiliation(s)
- Peng Zhao
- Beijing Key Laboratory of Bioprocess, College of Life Science and TechnologyBeijing University of Chemical Technology Beijing China
| | - Minrui Ren
- Beijing Key Laboratory of Bioprocess, College of Life Science and TechnologyBeijing University of Chemical Technology Beijing China
| | - Xizhen Ge
- College of Biochemical EngineeringBeijing Union University Beijing China
| | - Pingfang Tian
- Beijing Key Laboratory of Bioprocess, College of Life Science and TechnologyBeijing University of Chemical Technology Beijing China
| | - Tianwei Tan
- Beijing Key Laboratory of Bioprocess, College of Life Science and TechnologyBeijing University of Chemical Technology Beijing China
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44
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Tan SI, Ng IS. New Insight into Plasmid-Driven T7 RNA Polymerase in Escherichia coli and Use as a Genetic Amplifier for a Biosensor. ACS Synth Biol 2020; 9:613-622. [PMID: 32142603 DOI: 10.1021/acssynbio.9b00466] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
T7 RNA polymerase (T7RNAP) and T7 promoter are powerful genetic components, thus a plasmid-driven T7 (PDT7) genetic circuit could be broadly applied for synthetic biology. However, the limited knowledge of the toxicity and instability of such a system still restricts its application. Herein, we constructed 16 constitutive genetic circuts of PDT7 and investigated the orthogonal effects in toxicity and instability. The T7 toxicity was elucidated from the construction processes and cell growth characterization, showing the importance of optimal orthogonality for PDT7. Besides, a protein analysis was performed to validate how the T7 system affected cell metabolism and led to the instability. The application of constitutive PDT7 in functional protein expressions, including carbonic anhydrase, lysine decarboxylase, and 5-ALA synthetase was demonstrated. Furthermore, PDT7 working as a genetic amplifier had been designed for E. coli cell-based biosensors, which illustrated the opportunities in the future of PDT7 used in synthetic biology.
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Affiliation(s)
- Shih-I Tan
- Department of Chemical Engineering, National Cheng Kung University, Tainan, 70101, Taiwan
| | - I-Son Ng
- Department of Chemical Engineering, National Cheng Kung University, Tainan, 70101, Taiwan
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45
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Kopniczky MB, Canavan C, McClymont DW, Crone MA, Suckling L, Goetzmann B, Siciliano V, MacDonald JT, Jensen K, Freemont PS. Cell-Free Protein Synthesis as a Prototyping Platform for Mammalian Synthetic Biology. ACS Synth Biol 2020; 9:144-156. [PMID: 31899623 DOI: 10.1021/acssynbio.9b00437] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The field of mammalian synthetic biology is expanding quickly, and technologies for engineering large synthetic gene circuits are increasingly accessible. However, for mammalian cell engineering, traditional tissue culture methods are slow and cumbersome, and are not suited for high-throughput characterization measurements. Here we have utilized mammalian cell-free protein synthesis (CFPS) assays using HeLa cell extracts and liquid handling automation as an alternative to tissue culture and flow cytometry-based measurements. Our CFPS assays take a few hours, and we have established optimized protocols for small-volume reactions using automated acoustic liquid handling technology. As a proof-of-concept, we characterized diverse types of genetic regulation in CFPS, including T7 constitutive promoter variants, internal ribosomal entry sites (IRES) constitutive translation-initiation sequence variants, CRISPR/dCas9-mediated transcription repression, and L7Ae-mediated translation repression. Our data shows simple regulatory elements for use in mammalian cells can be quickly prototyped in a CFPS model system.
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Affiliation(s)
- Margarita B. Kopniczky
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London SW7 2AZ, U.K
| | - Caoimhe Canavan
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London SW7 2AZ, U.K
| | - David W. McClymont
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London SW7 2AZ, U.K
- London Biofoundry, Imperial College Translation & Innovation Hub, White City Campus, 80 Wood Lane, London W12 0BZ, U.K
| | - Michael A. Crone
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London SW7 2AZ, U.K
- UK Dementia Research Institute Care Research and Technology Centre, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0NN, U.K
| | - Lorna Suckling
- London Biofoundry, Imperial College Translation & Innovation Hub, White City Campus, 80 Wood Lane, London W12 0BZ, U.K
| | - Bruno Goetzmann
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London SW7 2AZ, U.K
| | - Velia Siciliano
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London SW7 2AZ, U.K
| | - James T. MacDonald
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London SW7 2AZ, U.K
| | - Kirsten Jensen
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London SW7 2AZ, U.K
- London Biofoundry, Imperial College Translation & Innovation Hub, White City Campus, 80 Wood Lane, London W12 0BZ, U.K
- UK Dementia Research Institute Care Research and Technology Centre, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0NN, U.K
| | - Paul S. Freemont
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London SW7 2AZ, U.K
- London Biofoundry, Imperial College Translation & Innovation Hub, White City Campus, 80 Wood Lane, London W12 0BZ, U.K
- UK Dementia Research Institute Care Research and Technology Centre, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0NN, U.K
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46
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Ryu MH, Zhang J, Toth T, Khokhani D, Geddes BA, Mus F, Garcia-Costas A, Peters JW, Poole PS, Ané JM, Voigt CA. Control of nitrogen fixation in bacteria that associate with cereals. Nat Microbiol 2019; 5:314-330. [DOI: 10.1038/s41564-019-0631-2] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 11/04/2019] [Indexed: 12/23/2022]
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47
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Chou LYT, Shih WM. In Vitro Transcriptional Regulation via Nucleic-Acid-Based Transcription Factors. ACS Synth Biol 2019; 8:2558-2565. [PMID: 31574217 DOI: 10.1021/acssynbio.9b00242] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Cells execute complex transcriptional programs by deploying distinct protein regulatory assemblies that interact with cis-regulatory elements throughout the genome. Using concepts from DNA nanotechnology, we synthetically recapitulated this feature in in vitro gene networks actuated by T7 RNA polymerase (RNAP). Our approach involves engineering nucleic acid hybridization interactions between a T7 RNAP site-specifically functionalized with single-stranded DNA (ssDNA), templates displaying cis-regulatory ssDNA domains, and auxiliary nucleic acid assemblies acting as artificial transcription factors (TFs). By relying on nucleic acid hybridization, de novo regulatory assemblies can be computationally designed to emulate features of protein-based TFs, such as cooperativity and combinatorial binding, while offering unique advantages such as programmability, chemical stability, and scalability. We illustrate the use of nucleic acid TFs to implement transcriptional logic, cascading, feedback, and multiplexing. This framework will enable rapid prototyping of increasingly complex in vitro genetic devices for applications such as portable diagnostics, bioanalysis, and the design of adaptive materials.
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Affiliation(s)
- Leo Y. T. Chou
- Dana-Farber Cancer Institute, Boston, Massachusetts 02215, United States
- Wyss Institute of Biologically Inspired Engineering at Harvard University, Boston, Massachusetts 02215, United States
| | - William M. Shih
- Dana-Farber Cancer Institute, Boston, Massachusetts 02215, United States
- Wyss Institute of Biologically Inspired Engineering at Harvard University, Boston, Massachusetts 02215, United States
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48
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HamediRad M, Chao R, Weisberg S, Lian J, Sinha S, Zhao H. Towards a fully automated algorithm driven platform for biosystems design. Nat Commun 2019; 10:5150. [PMID: 31723141 PMCID: PMC6853954 DOI: 10.1038/s41467-019-13189-z] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Accepted: 10/24/2019] [Indexed: 12/16/2022] Open
Abstract
Large-scale data acquisition and analysis are often required in the successful implementation of the design, build, test, and learn (DBTL) cycle in biosystems design. However, it has long been hindered by experimental cost, variability, biases, and missed insights from traditional analysis methods. Here, we report the application of an integrated robotic system coupled with machine learning algorithms to fully automate the DBTL process for biosystems design. As proof of concept, we have demonstrated its capacity by optimizing the lycopene biosynthetic pathway. This fully-automated robotic platform, BioAutomata, evaluates less than 1% of possible variants while outperforming random screening by 77%. A paired predictive model and Bayesian algorithm select experiments which are performed by Illinois Biological Foundry for Advanced Biomanufacturing (iBioFAB). BioAutomata excels with black-box optimization problems, where experiments are expensive and noisy and the success of the experiment is not dependent on extensive prior knowledge of biological mechanisms. Existing efforts have been focused on one of the elements in the automation of the design, build, test, and learn (DBTL) cycle for biosystems design. Here, the authors integrate a robotic system with machine learning algorithms to fully automate the DBTL cycle and apply it in optimizing the lycopene biosynthetic pathway.
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Affiliation(s)
- Mohammad HamediRad
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.,LifeFoundry Inc., 60 Hazelwood Dr., Champaign, IL, 61820, USA
| | - Ran Chao
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.,LifeFoundry Inc., 60 Hazelwood Dr., Champaign, IL, 61820, USA
| | - Scott Weisberg
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Jiazhang Lian
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.,Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, 310027, Hangzhou, China
| | - Saurabh Sinha
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA. .,Department of Computer Science, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
| | - Huimin Zhao
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA. .,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA. .,Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA. .,Departments of Chemistry and Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
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49
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Gale GAR, Schiavon Osorio AA, Mills LA, Wang B, Lea-Smith DJ, McCormick AJ. Emerging Species and Genome Editing Tools: Future Prospects in Cyanobacterial Synthetic Biology. Microorganisms 2019; 7:E409. [PMID: 31569579 PMCID: PMC6843473 DOI: 10.3390/microorganisms7100409] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Revised: 09/22/2019] [Accepted: 09/24/2019] [Indexed: 12/19/2022] Open
Abstract
Recent advances in synthetic biology and an emerging algal biotechnology market have spurred a prolific increase in the availability of molecular tools for cyanobacterial research. Nevertheless, work to date has focused primarily on only a small subset of model species, which arguably limits fundamental discovery and applied research towards wider commercialisation. Here, we review the requirements for uptake of new strains, including several recently characterised fast-growing species and promising non-model species. Furthermore, we discuss the potential applications of new techniques available for transformation, genetic engineering and regulation, including an up-to-date appraisal of current Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR associated protein (CRISPR/Cas) and CRISPR interference (CRISPRi) research in cyanobacteria. We also provide an overview of several exciting molecular tools that could be ported to cyanobacteria for more advanced metabolic engineering approaches (e.g., genetic circuit design). Lastly, we introduce a forthcoming mutant library for the model species Synechocystis sp. PCC 6803 that promises to provide a further powerful resource for the cyanobacterial research community.
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Affiliation(s)
- Grant A R Gale
- Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, UK.
- Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh EH9 3BF, UK.
- Institute of Quantitative Biology, Biochemistry and Biotechnology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FF, UK.
| | - Alejandra A Schiavon Osorio
- Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, UK.
- Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh EH9 3BF, UK.
| | - Lauren A Mills
- School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK.
| | - Baojun Wang
- Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh EH9 3BF, UK.
- Institute of Quantitative Biology, Biochemistry and Biotechnology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FF, UK.
| | - David J Lea-Smith
- School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK.
| | - Alistair J McCormick
- Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, UK.
- Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh EH9 3BF, UK.
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50
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Bervoets I, Charlier D. Diversity, versatility and complexity of bacterial gene regulation mechanisms: opportunities and drawbacks for applications in synthetic biology. FEMS Microbiol Rev 2019; 43:304-339. [PMID: 30721976 PMCID: PMC6524683 DOI: 10.1093/femsre/fuz001] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 01/21/2019] [Indexed: 12/15/2022] Open
Abstract
Gene expression occurs in two essential steps: transcription and translation. In bacteria, the two processes are tightly coupled in time and space, and highly regulated. Tight regulation of gene expression is crucial. It limits wasteful consumption of resources and energy, prevents accumulation of potentially growth inhibiting reaction intermediates, and sustains the fitness and potential virulence of the organism in a fluctuating, competitive and frequently stressful environment. Since the onset of studies on regulation of enzyme synthesis, numerous distinct regulatory mechanisms modulating transcription and/or translation have been discovered. Mostly, various regulatory mechanisms operating at different levels in the flow of genetic information are used in combination to control and modulate the expression of a single gene or operon. Here, we provide an extensive overview of the very diverse and versatile bacterial gene regulatory mechanisms with major emphasis on their combined occurrence, intricate intertwinement and versatility. Furthermore, we discuss the potential of well-characterized basal expression and regulatory elements in synthetic biology applications, where they may ensure orthogonal, predictable and tunable expression of (heterologous) target genes and pathways, aiming at a minimal burden for the host.
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Affiliation(s)
- Indra Bervoets
- Research Group of Microbiology, Department of Bioengineering Sciences, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
| | - Daniel Charlier
- Research Group of Microbiology, Department of Bioengineering Sciences, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
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