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Duan J, Yuan B, Jia F, Li X, Chen C, Li G. Development of an Efficient and Seamless Genetic Manipulation Method for Xenorhabdus and Its Application for Enhancing the Production of Fabclavines. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:274-283. [PMID: 38109418 DOI: 10.1021/acs.jafc.3c04136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2023]
Abstract
Xenorhabdus can produce numerous natural products, but their development has been hampered by the lack of a seamless genetic manipulation method. In this study, we compared several lethal genes and determined the sacB gene as the most effective counter-selection marker and then established a dual selection/counter-selection system by integrating neo and sacB genes into one cassette. This provides an efficient and seamless genetic manipulation method for Xenorhabdus. Using this method, DNA fragments ranging from 205 to 47,788 bp in length were seamlessly knocked out or replaced with impressively high positive rates of 80 to 100% in Xenorhabdus budapestensis XBD8. In addition, the method was successfully applied with good efficiency (45-100%) in Xenorhabdus nematophila CB6. To further validate the method, different constitutive promoters were used to replace the native fclC promoter in a batch experiment. The positivity rate remained consistently high, at 46.3%. In comparison to WT XBD8, the recombinant strain MX14 demonstrated a significant increase in the production of fabclavine 7 and fabclavine 8 by 4.97-fold and 3.22-fold, respectively, while the overall production of fabclavines was enhanced by 3.52-fold.
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Affiliation(s)
- Jiaqi Duan
- State Key Laboratory for Biology of Plant Diseases and Insect Pests/Key Laboratory of Control of Biological Hazard Factors (Plant Origin) for Agri-Product Quality and Safety, Ministry of Agriculture, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Baoming Yuan
- State Key Laboratory for Biology of Plant Diseases and Insect Pests/Key Laboratory of Control of Biological Hazard Factors (Plant Origin) for Agri-Product Quality and Safety, Ministry of Agriculture, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Fenglian Jia
- State Key Laboratory for Biology of Plant Diseases and Insect Pests/Key Laboratory of Control of Biological Hazard Factors (Plant Origin) for Agri-Product Quality and Safety, Ministry of Agriculture, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Xiaohui Li
- State Key Laboratory for Biology of Plant Diseases and Insect Pests/Key Laboratory of Control of Biological Hazard Factors (Plant Origin) for Agri-Product Quality and Safety, Ministry of Agriculture, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Chang Chen
- State Key Laboratory for Biology of Plant Diseases and Insect Pests/Key Laboratory of Control of Biological Hazard Factors (Plant Origin) for Agri-Product Quality and Safety, Ministry of Agriculture, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
- Beijing Green Agricultural Science and Technology Group Co., Ltd, Beijing 100193, China
| | - Guangyue Li
- State Key Laboratory for Biology of Plant Diseases and Insect Pests/Key Laboratory of Control of Biological Hazard Factors (Plant Origin) for Agri-Product Quality and Safety, Ministry of Agriculture, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
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2
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Wu Y, Zhu L, Zhang Y, Xu W. Multidimensional Applications and Challenges of Riboswitches in Biosensing and Biotherapy. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2304852. [PMID: 37658499 DOI: 10.1002/smll.202304852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 08/15/2023] [Indexed: 09/03/2023]
Abstract
Riboswitches have received significant attention over the last two decades for their multiple functionalities and great potential for applications in various fields. This article highlights and reviews the recent advances in biosensing and biotherapy. These fields involve a wide range of applications, such as food safety detection, environmental monitoring, metabolic engineering, live cell imaging, wearable biosensors, antibacterial drug targets, and gene therapy. The discovery, origin, and optimization of riboswitches are summarized to help readers better understand their multidimensional applications. Finally, this review discusses the multidimensional challenges and development of riboswitches in order to further expand their potential for novel applications.
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Affiliation(s)
- Yifan Wu
- Key Laboratory of Precision Nutrition and Food Quality, Beijing Laboratory for Food Quality and Safety, Department of Nutrition and Health, China Agricultural University, Beijing, 100191, China
| | - Longjiao Zhu
- Key Laboratory of Precision Nutrition and Food Quality, Beijing Laboratory for Food Quality and Safety, Department of Nutrition and Health, China Agricultural University, Beijing, 100191, China
| | - Yangzi Zhang
- Key Laboratory of Precision Nutrition and Food Quality, Beijing Laboratory for Food Quality and Safety, Department of Nutrition and Health, China Agricultural University, Beijing, 100191, China
| | - Wentao Xu
- Key Laboratory of Precision Nutrition and Food Quality, Beijing Laboratory for Food Quality and Safety, Department of Nutrition and Health, China Agricultural University, Beijing, 100191, China
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3
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Feng H, Li F, Wang T, Xing XH, Zeng AP, Zhang C. Deep-learning-assisted Sort-Seq enables high-throughput profiling of gene expression characteristics with high precision. SCIENCE ADVANCES 2023; 9:eadg5296. [PMID: 37939173 PMCID: PMC10631719 DOI: 10.1126/sciadv.adg5296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 10/06/2023] [Indexed: 11/10/2023]
Abstract
Owing to the nondeterministic and nonlinear nature of gene expression, the steady-state intracellular protein abundance of a clonal population forms a distribution. The characteristics of this distribution, including expression strength and noise, are closely related to cellular behavior. However, quantitative description of these characteristics has so far relied on arrayed methods, which are time-consuming and labor-intensive. To address this issue, we propose a deep-learning-assisted Sort-Seq approach (dSort-Seq) in this work, enabling high-throughput profiling of expression properties with high precision. We demonstrated the validity of dSort-Seq for large-scale assaying of the dose-response relationships of biosensors. In addition, we comprehensively investigated the contribution of transcription and translation to noise production in Escherichia coli, from which we found that the expression noise is strongly coupled with the mean expression level. We also found that the transcriptional interference caused by overlapping RpoD-binding sites contributes to noise production, which suggested the existence of a simple and feasible noise control strategy in E. coli.
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Affiliation(s)
- Huibao Feng
- MOE Key Laboratory for Industrial Biocatalysis, Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
| | - Fan Li
- MOE Key Laboratory for Industrial Biocatalysis, Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
| | - Tianmin Wang
- Tsinghua-Peking Center for Life Sciences, School of Medicine, Tsinghua University, Beijing 100084, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xin-hui Xing
- MOE Key Laboratory for Industrial Biocatalysis, Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
- Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
| | - An-ping Zeng
- Institute of Bioprocess and Biosystems Engineering, Hamburg University of Technology, Hamburg 21073, Germany
- Center of Synthetic Biology and Integrated Bioengineering, School of Engineering, Westlake University, Hangzhou 310024, China
| | - Chong Zhang
- MOE Key Laboratory for Industrial Biocatalysis, Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
- Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, China
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4
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Xiang Y, Chen R, Shi F, Lai W. Exploring L-isoleucine riboswitches for enhancing 4-hydroxyisoleucine production in Corynebacterium glutamicum. Biotechnol Lett 2023; 45:1169-1181. [PMID: 37395871 DOI: 10.1007/s10529-023-03407-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 05/27/2023] [Accepted: 06/10/2023] [Indexed: 07/04/2023]
Abstract
OBJECTIVES To explore an L-isoleucine (Ile)-induced biosensor for down-regulation of Ile synthesis pathway and enhancement of 4-hydroxyisoleucine (4-HIL) production in Corynebacterium glutamicum SN01. RESULTS Four Ile-induced riboswitches (IleRSN) with different strength were screened from mutation library based on TPP riboswitch. Firstly, IleRSN were integrated into the chromosome of strain SN01 immediately upstream of ilvA gene. The 4-HIL titer of strains carrying PtacM-driven IleRS1 or IleRS3 (14.09 ± 1.07, 15.20 ± 0.93 g 4-HIL L-1) were similar with control strain S-D5I (15.73 ± 2.66 g 4-HIL L-1). Then, another copy of IleRS3-ilvA was integrated downstream of the chromosomal cg0963 gene in SN01-derived strain D-RS with down-regulated L-lysine (Lys) biosynthesis. The Ile supply and 4-HIL titer increased in ilvA two-copy strains KIRSA-3-D5I and KIRSA-3-9I, and Ile concentration was maintained less than 35 mmol L-1 under the control of IleRS3 during fermentation. The resulting strain KIRSA-3-9I produced 22.46 ± 0.96 g 4-HIL L-1. CONCLUSION The screened IleRS was effective in the dynamic down-regulation of Ile synthesis pathway in C. glutamicum, and IleRSN with different strength can be applied in various conditions.
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Affiliation(s)
- Youhe Xiang
- State Key Laboratory of Food Science and Resources, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Rui Chen
- State Key Laboratory of Food Science and Resources, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Feng Shi
- State Key Laboratory of Food Science and Resources, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China.
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China.
- International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, 214122, China.
| | - Wenmei Lai
- State Key Laboratory of Food Science and Resources, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
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5
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Xu J, Hou J, Ding M, Wang Z, Chen T. Riboswitches, from cognition to transformation. Synth Syst Biotechnol 2023; 8:357-370. [PMID: 37325181 PMCID: PMC10265488 DOI: 10.1016/j.synbio.2023.05.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 05/20/2023] [Accepted: 05/25/2023] [Indexed: 06/17/2023] Open
Abstract
Riboswitches are functional RNA elements that regulate gene expression by directly detecting metabolites. Twenty years have passed since it was first discovered, researches on riboswitches are becoming increasingly standardized and refined, which could significantly promote people's cognition of RNA function as well. Here, we focus on some representative orphan riboswitches, enumerate the structural and functional transformation and artificial design of riboswitches including the coupling with ribozymes, hoping to attain a comprehensive understanding of riboswitch research.
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Affiliation(s)
- Jingdong Xu
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300350, China
- Frontier Science Center for Synthetic Biology, Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin, 300350, China
- Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300350, China
| | - Junyuan Hou
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300350, China
- Frontier Science Center for Synthetic Biology, Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin, 300350, China
- Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300350, China
| | - Mengnan Ding
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300350, China
- Frontier Science Center for Synthetic Biology, Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin, 300350, China
- Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300350, China
| | - Zhiwen Wang
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300350, China
- Frontier Science Center for Synthetic Biology, Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin, 300350, China
- Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300350, China
| | - Tao Chen
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300350, China
- Frontier Science Center for Synthetic Biology, Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin, 300350, China
- Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300350, China
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6
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Mao C, Mao Y, Zhu X, Chen G, Feng C. Synthetic biology-based bioreactor and its application in biochemical analysis. Crit Rev Anal Chem 2023:1-18. [PMID: 36803337 DOI: 10.1080/10408347.2023.2180319] [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: 02/22/2023]
Abstract
In the past few years, synthetic biologists have established some biological elements and bioreactors composed of nucleotides under the guidance of engineering methods. Following the concept of engineering, the common bioreactor components in recent years are introduced and compared. At present, biosensors based on synthetic biology have been applied to water pollution monitoring, disease diagnosis, epidemiological monitoring, biochemical analysis and other detection fields. In this paper, the biosensor components based on synthetic bioreactors and reporters are reviewed. In addition, the applications of biosensors based on cell system and cell-free system in the detection of heavy metal ions, nucleic acid, antibiotics and other substances are presented. Finally, the bottlenecks faced by biosensors and the direction of optimization are also discussed.
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Affiliation(s)
- Changqing Mao
- Center for Molecular Recognition and Biosensing, School of Life Sciences, Shanghai University, Shanghai, P. R. China
| | - Yichun Mao
- Center for Molecular Recognition and Biosensing, School of Life Sciences, Shanghai University, Shanghai, P. R. China
| | - Xiaoli Zhu
- Department of Clinical Laboratory Medicine, Shanghai Tenth People's Hospital of Tongji University, Shanghai, P. R. China
| | - Guifang Chen
- Center for Molecular Recognition and Biosensing, School of Life Sciences, Shanghai University, Shanghai, P. R. China
- Shanghai Engineering Research Center of Organ Repair, Shanghai University, Shanghai, P. R. China
| | - Chang Feng
- Center for Molecular Recognition and Biosensing, School of Life Sciences, Shanghai University, Shanghai, P. R. China
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7
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Dong X, Qi S, Khan IM, Sun Y, Zhang Y, Wang Z. Advances in riboswitch-based biosensor as food samples detection tool. Compr Rev Food Sci Food Saf 2023; 22:451-472. [PMID: 36511082 DOI: 10.1111/1541-4337.13077] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 10/09/2022] [Accepted: 10/25/2022] [Indexed: 12/14/2022]
Abstract
Food safety has always been a hot issue of social concern, and biosensing has been widely used in the field of food safety detection. Compared with traditional aptamer-based biosensors, aptamer-based riboswitch biosensing represents higher precision and programmability. A riboswitch is an elegant example of controlling gene expression, where the target is coupled to the aptamer domain, resulting in a conformational change in the downstream expression domain and determining the signal output. Riboswitch-based biosensing can be extensively applied to the portable real-time detection of food samples. The numerous key features of riboswitch-based biosensing emphasize their sustainability, renewable, and testing, which promises to transform engineering applications in the field of food safety. This review covers recent developments in riboswitch-based biosensors. The brief history, definition, and modular design (regulatory mode, reporter, and expression platform) of riboswitch-based biosensors are explained for better insight into the design and construction. We summarize recent advances in various riboswitch-based biosensors involving theophylline, malachite green, tetracycline, neomycin, fluoride, thrombin, naringenin, ciprofloxacin, and paromomycin, aiming to provide general guidance for the design of riboswitch-based biosensors. Finally, the challenges and prospects are also summarized as a way forward stratagem and signs of progress.
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Affiliation(s)
- Xiaoze Dong
- State Key Laboratory of Food Science and Technology, International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, China
| | - Shuo Qi
- State Key Laboratory of Food Science and Technology, International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, China
| | - Imran Mahmood Khan
- State Key Laboratory of Food Science and Technology, International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, China
| | - Yuhan Sun
- State Key Laboratory of Food Science and Technology, International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, China
| | - Yin Zhang
- Key Laboratory of Meat Processing of Sichuan, Chengdu University, Chengdu, China
| | - Zhouping Wang
- State Key Laboratory of Food Science and Technology, International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, China.,School of Food Science and Technology, Jiangnan University, Wuxi, China.,Key Laboratory of Meat Processing of Sichuan, Chengdu University, Chengdu, China.,National Engineering Research Center for Functional Food, Jiangnan University, Wuxi, China.,Collaborative innovation center of food safety and quality control in Jiangsu Province, Food, Jiangnan University, Wuxi, China
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8
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Wu Y, Zhu L, Li S, Chu H, Wang X, Xu W. High content design of riboswitch biosensors: All-around rational module-by-module design. Biosens Bioelectron 2022; 220:114887. [DOI: 10.1016/j.bios.2022.114887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 09/27/2022] [Accepted: 11/03/2022] [Indexed: 11/11/2022]
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9
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Zhou S, Alper HS, Zhou J, Deng Y. Intracellular biosensor-based dynamic regulation to manipulate gene expression at the spatiotemporal level. Crit Rev Biotechnol 2022; 43:646-663. [PMID: 35450502 DOI: 10.1080/07388551.2022.2040415] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The use of intracellular, biosensor-based dynamic regulation strategies to regulate and improve the production of useful compounds have progressed significantly over previous decades. By employing such an approach, it is possible to simultaneously realize high productivity and optimum growth states. However, industrial fermentation conditions contain a mixture of high- and low-performance non-genetic variants, as well as young and aged cells at all growth phases. Such significant individual variations would hinder the precise controlling of metabolic flux at the single-cell level to achieve high productivity at the macroscopic population level. Intracellular biosensors, as the regulatory centers of metabolic networks, can real-time sense intra- and extracellular conditions and, thus, could be synthetically adapted to balance the biomass formation and overproduction of compounds by individual cells. Herein, we highlight advances in the designing and engineering approaches to intracellular biosensors. Then, the spatiotemporal properties of biosensors associated with the distribution of inducers are compared. Also discussed is the use of such biosensors to dynamically control the cellular metabolic flux. Such biosensors could achieve single-cell regulation or collective regulation goals, depending on whether or not the inducer distribution is only intracellular.
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Affiliation(s)
- Shenghu Zhou
- National Engineering Laboratory for Cereal Fermentation Technology (NELCF), Jiangnan University, Wuxi, Jiangsu, China.,Jiangsu Provincial Research Center for Bioactive Product Processing Technology, Jiangnan University, Wuxi, Jiangsu, China
| | - Hal S Alper
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, USA.,McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Jingwen Zhou
- National Engineering Laboratory for Cereal Fermentation Technology (NELCF), Jiangnan University, Wuxi, Jiangsu, China.,Jiangsu Provincial Research Center for Bioactive Product Processing Technology, Jiangnan University, Wuxi, Jiangsu, China
| | - Yu Deng
- National Engineering Laboratory for Cereal Fermentation Technology (NELCF), Jiangnan University, Wuxi, Jiangsu, China.,Jiangsu Provincial Research Center for Bioactive Product Processing Technology, Jiangnan University, Wuxi, Jiangsu, China
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10
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Engineering of Synthetic Transcriptional Switches in Yeast. Life (Basel) 2022; 12:life12040557. [PMID: 35455048 PMCID: PMC9030632 DOI: 10.3390/life12040557] [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: 03/02/2022] [Revised: 03/31/2022] [Accepted: 04/03/2022] [Indexed: 02/04/2023] Open
Abstract
Transcriptional switches can be utilized for many purposes in synthetic biology, including the assembly of complex genetic circuits to achieve sophisticated cellular systems and the construction of biosensors for real-time monitoring of intracellular metabolite concentrations. Although to date such switches have mainly been developed in prokaryotes, those for eukaryotes are increasingly being reported as both rational and random engineering technologies mature. In this review, we describe yeast transcriptional switches with different modes of action and how to alter their properties. We also discuss directed evolution technologies for the rapid and robust construction of yeast transcriptional switches.
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11
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Tabuchi T, Yokobayashi Y. High-throughput screening of cell-free riboswitches by fluorescence-activated droplet sorting. Nucleic Acids Res 2022; 50:3535-3550. [PMID: 35253887 PMCID: PMC8989549 DOI: 10.1093/nar/gkac152] [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: 01/26/2022] [Revised: 02/15/2022] [Accepted: 02/20/2022] [Indexed: 11/14/2022] Open
Abstract
Cell-free systems that display complex functions without using living cells are emerging as new platforms to test our understanding of biological systems as well as for practical applications such as biosensors and biomanufacturing. Those that use cell-free protein synthesis (CFPS) systems to enable genetically programmed protein synthesis have relied on genetic regulatory components found or engineered in living cells. However, biological constraints such as cell permeability, metabolic stability, and toxicity of signaling molecules prevent development of cell-free devices using living cells even if cell-free systems are not subject to such constraints. Efforts to engineer regulatory components directly in CFPS systems thus far have been based on low-throughput experimental approaches, limiting the availability of basic components to build cell-free systems with diverse functions. Here, we report a high-throughput screening method to engineer cell-free riboswitches that respond to small molecules. Droplet-sorting of riboswitch variants in a CFPS system rapidly identified cell-free riboswitches that respond to compounds that are not amenable to bacterial screening methods. Finally, we used a histamine riboswitch to demonstrate chemical communication between cell-sized droplets.
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Affiliation(s)
- Takeshi Tabuchi
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
| | - Yohei Yokobayashi
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
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12
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Xu X, Rao ZM, Xu JZ, Zhang WG. Enhancement of l-Pipecolic Acid Production by Dynamic Control of Substrates and Multiple Copies of the pipA Gene in the Escherichia coli Genome. ACS Synth Biol 2022; 11:760-769. [PMID: 35073050 DOI: 10.1021/acssynbio.1c00467] [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: 11/30/2022]
Abstract
l-Pipecolic acid is an important rigid cyclic nonprotein amino acid, which is obtained through the conversion of l-lysine catalyzed by l-lysine cyclodeaminase (LCD). To directly produce l-pipecolic acid from glucose by microbial fermentation, in this study, a recombinant Escherichia coli strain with high efficiency of l-pipecolic acid production was constructed. This study involves the dynamic regulation of the substrate concentration and the expression level of the l-lysine cyclodeaminase-coding gene pipA. In terms of substrate concentration, we adopted the l-lysine riboswitch to dynamically regulate the expression of lysP and lysO genes. As a result, the l-pipecolic acid yield was increased about 1.8-fold as compared with the control. In addition, we used chemically inducible chromosomal evolution (CIChE) to realize the presence of multiple copies of the pipA gene on the genome. The resultant E. coli strain XQ-11-4 produced 61 ± 3.4 g/L l-pipecolic acid with a productivity of 1.02 ± 0.06 g/(L·h) and a glucose conversion efficiency (α) of 29.6% in fermentation. This is the first report that discovered multiple copies of pipA gene expression on the genome that improves the efficiency of l-pipecolic acid production in an l-lysine high-producing strain, and these results give us new insight for constructing the other valuable biochemicals derived from l-lysine.
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Affiliation(s)
- Xin Xu
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800# Lihu Road, Wuxi 214122, People’s Republic of China
| | - Zhi-Ming Rao
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800# Lihu Road, Wuxi 214122, People’s Republic of China
- National Engineering Laboratory for Cereal Fermentation Technology (NELCF), Jiangnan University, 1800# Lihu Road, Wuxi 214122, People’s Republic of China
| | - Jian-Zhong Xu
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800# Lihu Road, Wuxi 214122, People’s Republic of China
| | - Wei-Guo Zhang
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800# Lihu Road, Wuxi 214122, People’s Republic of China
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13
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Miller CA, Ho JML, Bennett MR. Strategies for Improving Small-Molecule Biosensors in Bacteria. BIOSENSORS 2022; 12:bios12020064. [PMID: 35200325 PMCID: PMC8869690 DOI: 10.3390/bios12020064] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 01/14/2022] [Accepted: 01/18/2022] [Indexed: 05/03/2023]
Abstract
In recent years, small-molecule biosensors have become increasingly important in synthetic biology and biochemistry, with numerous new applications continuing to be developed throughout the field. For many biosensors, however, their utility is hindered by poor functionality. Here, we review the known types of mechanisms of biosensors within bacterial cells, and the types of approaches for optimizing different biosensor functional parameters. Discussed approaches for improving biosensor functionality include methods of directly engineering biosensor genes, considerations for choosing genetic reporters, approaches for tuning gene expression, and strategies for incorporating additional genetic modules.
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Affiliation(s)
- Corwin A. Miller
- Department of Biosciences, Rice University MS-140, 6100 Main St., Houston, TX 77005, USA; (C.A.M.); (J.M.L.H.)
| | - Joanne M. L. Ho
- Department of Biosciences, Rice University MS-140, 6100 Main St., Houston, TX 77005, USA; (C.A.M.); (J.M.L.H.)
| | - Matthew R. Bennett
- Department of Biosciences, Rice University MS-140, 6100 Main St., Houston, TX 77005, USA; (C.A.M.); (J.M.L.H.)
- Department of Bioengineering, Rice University MS-140, 6100 Main St., Houston, TX 77005, USA
- Correspondence:
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14
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Kim M, Jang S, Jung GY. Development of Synthetic Riboswitches to Guide the Evolution of Metabolite Production in Microorganisms. Methods Mol Biol 2022; 2518:135-155. [PMID: 35666444 DOI: 10.1007/978-1-0716-2421-0_9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The untranslated region (UTR) of prokaryotic mRNA contains riboswitches, which are gene regulating modules. Riboswitches can be used as biosensors to regulate the expression of a gene or an operon depending on the intracellular level of a target molecule and consequently modulate the cellular responses. In evolutionary engineering, riboswitch-based biosensors have been widely applied for high-throughput screening or selection of target phenotypes. Evolutionary approaches can overcome the limitations of rational approaches in metabolic engineering. Previous studies have reported synthetic riboswitches equipped with novel aptamers and marker genes based on a deep understanding of the operation mechanism of the riboswitch. Here, we introduce the development process of novel synthetic riboswitches for applications in metabolic engineering.
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Affiliation(s)
- Minsun Kim
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang, Gyeongbuk, Korea
| | - Sungho Jang
- Department of Bioengineering and Nano-Bioengineering, Incheon National University, Incheon, Korea
- Division of Bioengineering, College of Life Sciences and Bioengineering, Incheon National University, Incheon, Korea
- Research Center for Bio Materials & Process Development, Incheon National University, Incheon, Korea
| | - Gyoo Yeol Jung
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang, Gyeongbuk, Korea.
- Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, Gyeongbuk, Korea.
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15
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Koklu A, Ohayon D, Wustoni S, Druet V, Saleh A, Inal S. Organic Bioelectronic Devices for Metabolite Sensing. Chem Rev 2021; 122:4581-4635. [PMID: 34610244 DOI: 10.1021/acs.chemrev.1c00395] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Electrochemical detection of metabolites is essential for early diagnosis and continuous monitoring of a variety of health conditions. This review focuses on organic electronic material-based metabolite sensors and highlights their potential to tackle critical challenges associated with metabolite detection. We provide an overview of the distinct classes of organic electronic materials and biorecognition units used in metabolite sensors, explain the different detection strategies developed to date, and identify the advantages and drawbacks of each technology. We then benchmark state-of-the-art organic electronic metabolite sensors by categorizing them based on their application area (in vitro, body-interfaced, in vivo, and cell-interfaced). Finally, we share our perspective on using organic bioelectronic materials for metabolite sensing and address the current challenges for the devices and progress to come.
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Affiliation(s)
- Anil Koklu
- King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering (BESE), Organic Bioelectronics Laboratory, Thuwal 23955-6900, Saudi Arabia
| | - David Ohayon
- King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering (BESE), Organic Bioelectronics Laboratory, Thuwal 23955-6900, Saudi Arabia
| | - Shofarul Wustoni
- King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering (BESE), Organic Bioelectronics Laboratory, Thuwal 23955-6900, Saudi Arabia
| | - Victor Druet
- King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering (BESE), Organic Bioelectronics Laboratory, Thuwal 23955-6900, Saudi Arabia
| | - Abdulelah Saleh
- King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering (BESE), Organic Bioelectronics Laboratory, Thuwal 23955-6900, Saudi Arabia
| | - Sahika Inal
- King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering (BESE), Organic Bioelectronics Laboratory, Thuwal 23955-6900, Saudi Arabia
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16
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Tickner ZJ, Farzan M. Riboswitches for Controlled Expression of Therapeutic Transgenes Delivered by Adeno-Associated Viral Vectors. Pharmaceuticals (Basel) 2021; 14:ph14060554. [PMID: 34200913 PMCID: PMC8230432 DOI: 10.3390/ph14060554] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 05/28/2021] [Accepted: 06/04/2021] [Indexed: 11/16/2022] Open
Abstract
Vectors developed from adeno-associated virus (AAV) are powerful tools for in vivo transgene delivery in both humans and animal models, and several AAV-delivered gene therapies are currently approved for clinical use. However, AAV-mediated gene therapy still faces several challenges, including limited vector packaging capacity and the need for a safe, effective method for controlling transgene expression during and after delivery. Riboswitches, RNA elements which control gene expression in response to ligand binding, are attractive candidates for regulating expression of AAV-delivered transgene therapeutics because of their small genomic footprints and non-immunogenicity compared to protein-based expression control systems. In addition, the ligand-sensing aptamer domains of many riboswitches can be exchanged in a modular fashion to allow regulation by a variety of small molecules, proteins, and oligonucleotides. Riboswitches have been used to regulate AAV-delivered transgene therapeutics in animal models, and recently developed screening and selection methods allow rapid isolation of riboswitches with novel ligands and improved performance in mammalian cells. This review discusses the advantages of riboswitches in the context of AAV-delivered gene therapy, the subsets of riboswitch mechanisms which have been shown to function in human cells and animal models, recent progress in riboswitch isolation and optimization, and several examples of AAV-delivered therapeutic systems which might be improved by riboswitch regulation.
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Affiliation(s)
- Zachary J. Tickner
- Department of Immunology and Microbiology, the Scripps Research Institute, Jupiter, FL 33458, USA;
- Correspondence:
| | - Michael Farzan
- Department of Immunology and Microbiology, the Scripps Research Institute, Jupiter, FL 33458, USA;
- Emmune, Inc., Jupiter, FL 33458, USA
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17
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Abstract
One of the most prominent features of genetically encoded biosensors (GEBs) is their evolvability-the ability to invent new sensory functions using mutations. Among the GEBs, the transcription factor-based biosensors (TF-biosensors) is the focus of this review. We also discuss how this class of sensors can be highly evolvable and how we can exploit it. With an established platform for directed evolution, researchers can create, or evolve, new TF-biosensors. Directed evolution experiments have revealed the TF-biosensors' evolvability, which is based partially on their characteristic physicochemical properties.
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Affiliation(s)
- Daisuke Umeno
- Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba University
| | - Yuki Kimura
- Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba University
| | - Shigeko Kawai-Noma
- Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba University
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18
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Tominaga M, Nozaki K, Umeno D, Ishii J, Kondo A. Robust and flexible platform for directed evolution of yeast genetic switches. Nat Commun 2021; 12:1846. [PMID: 33758180 PMCID: PMC7988172 DOI: 10.1038/s41467-021-22134-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 02/26/2021] [Indexed: 01/31/2023] Open
Abstract
A wide repertoire of genetic switches has accelerated prokaryotic synthetic biology, while eukaryotic synthetic biology has lagged in the model organism Saccharomyces cerevisiae. Eukaryotic genetic switches are larger and more complex than prokaryotic ones, complicating the rational design and evolution of them. Here, we present a robust workflow for the creation and evolution of yeast genetic switches. The selector system was designed so that both ON- and OFF-state selection of genetic switches is completed solely by liquid handling, and it enabled parallel screen/selection of different motifs with different selection conditions. Because selection threshold of both ON- and OFF-state selection can be flexibly tuned, the desired selection conditions can be rapidly pinned down for individual directed evolution experiments without a prior knowledge either on the library population. The system's utility was demonstrated using 20 independent directed evolution experiments, yielding genetic switches with elevated inducer sensitivities, inverted switching behaviours, sensory functions, and improved signal-to-noise ratio (>100-fold induction). The resulting yeast genetic switches were readily integrated, in a plug-and-play manner, into an AND-gated carotenoid biosynthesis pathway.
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Affiliation(s)
- Masahiro Tominaga
- grid.31432.370000 0001 1092 3077Graduate School of Science, Technology and Innovation, Kobe University, Kobe, Japan
| | - Kenta Nozaki
- grid.31432.370000 0001 1092 3077Graduate School of Science, Technology and Innovation, Kobe University, Kobe, Japan
| | - Daisuke Umeno
- grid.136304.30000 0004 0370 1101Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Chiba University, Chiba, Japan
| | - Jun Ishii
- grid.31432.370000 0001 1092 3077Graduate School of Science, Technology and Innovation, Kobe University, Kobe, Japan ,grid.31432.370000 0001 1092 3077Engineering Biology Research Center, Kobe University, Kobe, Japan
| | - Akihiko Kondo
- grid.31432.370000 0001 1092 3077Graduate School of Science, Technology and Innovation, Kobe University, Kobe, Japan ,grid.31432.370000 0001 1092 3077Engineering Biology Research Center, Kobe University, Kobe, Japan ,grid.31432.370000 0001 1092 3077Department of Chemical Science and Engineering, Faculty of Engineering, Kobe University, Kobe, Japan ,grid.7597.c0000000094465255Center for Sustainable Resource Science, RIKEN, Yokohama, Japan
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19
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Wang Z, Doshi A, Chowdhury R, Wang Y, Maranas CD, Cirino PC. Engineering sensitivity and specificity of AraC-based biosensors responsive to triacetic acid lactone and orsellinic acid. Protein Eng Des Sel 2020; 33:5993570. [DOI: 10.1093/protein/gzaa027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 10/01/2020] [Accepted: 10/09/2020] [Indexed: 11/14/2022] Open
Abstract
Abstract
We previously described the design of triacetic acid lactone (TAL) biosensor ‘AraC-TAL1’, based on the AraC regulatory protein. Although useful as a tool to screen for enhanced TAL biosynthesis, this variant shows elevated background (leaky) expression, poor sensitivity and relaxed inducer specificity, including responsiveness to orsellinic acid (OA). More sensitive biosensors specific to either TAL or OA can aid in the study and engineering of polyketide synthases that produce these and similar compounds. In this work, we employed a TetA-based dual-selection to isolate new TAL-responsive AraC variants showing reduced background expression and improved TAL sensitivity. To improve TAL specificity, OA was included as a ‘decoy’ ligand during negative selection, resulting in the isolation of a TAL biosensor that is inhibited by OA. Finally, to engineer OA-specific AraC variants, the iterative protein redesign and optimization computational framework was employed, followed by 2 rounds of directed evolution, resulting in a biosensor with 24-fold improved OA/TAL specificity, relative to AraC-TAL1.
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Affiliation(s)
- Zhiqing Wang
- Department of Chemical and Biomolecular Engineering, University of Houston, 4726 Calhoun Rd, Houston, TX 77204-4004 Houston, TX, USA
| | - Aarti Doshi
- Department of Biology and Biochemistry, University of Houston, 3507 Cullen Blvd, Houston, TX 77204-5008 Houston, TX, USA
| | - Ratul Chowdhury
- Department of Chemical and Biomedical Engineering, Penn State University, University Park, PA 16802-4400 PA, USA
| | - Yixi Wang
- Department of Chemical and Biomolecular Engineering, University of Houston, 4726 Calhoun Rd, Houston, TX 77204-4004 Houston, TX, USA
| | - Costas D Maranas
- Department of Chemical and Biomedical Engineering, Penn State University, University Park, PA 16802-4400 PA, USA
| | - Patrick C Cirino
- Department of Chemical and Biomolecular Engineering, University of Houston, 4726 Calhoun Rd, Houston, TX 77204-4004 Houston, TX, USA
- Department of Biology and Biochemistry, University of Houston, 3507 Cullen Blvd, Houston, TX 77204-5008 Houston, TX, USA
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20
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Tan S, Shi F, Liu H, Yu X, Wei S, Fan Z, Li Y. Dynamic Control of 4-Hydroxyisoleucine Biosynthesis by Modified l-Isoleucine Biosensor in Recombinant Corynebacterium glutamicum. ACS Synth Biol 2020; 9:2378-2389. [PMID: 32813974 DOI: 10.1021/acssynbio.0c00127] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
4-Hydroxyisoleucine (4-HIL), a promising drug for treating diabetes, can be synthesized from the self-produced l-isoleucine (Ile) by expressing the Ile dioxygenase gene ido in Corynebacterium glutamicum. However, the requirement of three substrates, Ile, α-ketoglutarate (α-KG), and O2, makes such de novo biosynthesis difficult to be fulfilled effectively under static engineering conditions. In this study, dynamic control of 4-HIL biosynthesis by the Ile biosensor Lrp-PbrnFE was researched. The native PbrnFE promoter of natural Ile biosensor was still weak even under Ile induction. Through tetA dual genetic selection, several modified stronger PbrnFEN promoters were obtained from the synthetic library of the Ile biosensor. Dynamic regulation of ido expression by modified Ile biosensors increased the 4-HIL titer from 24.7 mM to 28.9-74.4 mM. The best strain ST04 produced even a little more 4-HIL than the static strain SN02 overexpressing ido by the strong PtacM promoter (69.7 mM). Further dynamic modulation of α-KG supply in ST04 by expressing different PbrnFEN-controlled odhI decreased the 4-HIL production but increased the l-glutamate or Ile accumulation. However, synergistic modulation of α-KG supply and O2 supply in ST04 by different combinations of PbrnFEN-odhI and PbrnFEN-vgb improved the 4-HIL production significantly, and the highest titer (135.3 mM) was obtained in ST17 strain regulating all the three genes by PbrnFE7. This titer was higher than those of all the static metabolic engineered C. glutamicum strains ever constructed. Therefore, dynamic regulation by modified Ile biosensor is a predominant strategy for enhancing 4-HIL de novo biosynthesis in C. glutamicum.
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Affiliation(s)
- Shuyu Tan
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Feng Shi
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
- International Joint Laboratory on Food Safety, Jiangnan University, Wuxi 214122, China
| | - Haiyan Liu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Xinping Yu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Shuyu Wei
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Zhengyu Fan
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Yongfu Li
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, China
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21
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In vivo evolutionary engineering of riboswitch with high-threshold for N-acetylneuraminic acid production. Metab Eng 2020; 59:36-43. [PMID: 31954846 DOI: 10.1016/j.ymben.2020.01.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 11/26/2019] [Accepted: 01/04/2020] [Indexed: 11/22/2022]
Abstract
Riboswitches with desired properties, such as sensitivity, threshold, dynamic range, is important for its application. However, the property change of a natural riboswitch is difficult due to the lack of the understanding of aptamer ligand binding properties and a proper screening method for both rational and irrational design. In this study, an effective method to change the threshold of riboswitch was established in vivo based on growth coupled screening by combining both positive and negative selections. The feasibility of the method was verified by the model library. Using this method, an N-acetylneuraminic acid (NeuAc) riboswitch was evolved and modified riboswitches with high threshold and large dynamic range were obtained. Then, using a new NeuAc riboswitch, both ribosome binding sites and key gene in NeuAc biosynthesis pathway were optimized. The highest NeuAc production of 14.32 g/l that has been reported using glucose as sole carbon source was obtained.
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22
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Zhou L, Ren J, Li Z, Nie J, Wang C, Zeng AP. Characterization and Engineering of a Clostridium Glycine Riboswitch and Its Use To Control a Novel Metabolic Pathway for 5-Aminolevulinic Acid Production in Escherichia coli. ACS Synth Biol 2019; 8:2327-2335. [PMID: 31550137 DOI: 10.1021/acssynbio.9b00137] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A riboswitch, a regulatory RNA that controls gene expression by specifically binding a ligand, is an attractive genetic element for the control of conditional gene expression and metabolic pathways. In this study, we identified a glycine riboswitch located in the 5'-untranslated regions of a glycine:proton symporter gene in Clostridium pasteurianum. The glycine riboswitch is shown to contain two tandem aptamers and to function as an activator of expression of genes fused to its expression platform. Results of singlet aptamer experiments indicated that aptamer-2 has a much higher impact on regulating gene expression than aptamer-1. Further, we successfully obtained synthetic glycine-OFF riboswitches using a dual selection approach, and one of them repressed gene expression up to 10.2-fold with an improved dynamic range. The specific glycine-OFF riboswitch can function as an independent repressor in the presence of glycine, and its repression mechanism is inferred from predicted secondary structure. The selected glycine-OFF riboswitch was used to dynamically control the biosynthesis of 5-aminolevulinic acid (5-ALA) in Escherichia coli with an unnatural 5-ALA synthetic pathway, in which glycine plays a key role. It is demonstrated that the use of a synthetic Clostridium glycine-OFF riboswitch can lead to a significant increase (11%) of 5-ALA in E. coli harboring an unnatural biosynthetic pathway.
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Affiliation(s)
- Libang Zhou
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering , Beijing University of Chemical Technology , North Third Ring Road 15 , Chaoyang District, Beijing 100029 , China
- College of Food Science and Technology , Nanjing Agricultural University , Weigang 1 , Nanjing 210095 , PR China
| | - Jie Ren
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering , Beijing University of Chemical Technology , North Third Ring Road 15 , Chaoyang District, Beijing 100029 , China
| | - Zhidong Li
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering , Beijing University of Chemical Technology , North Third Ring Road 15 , Chaoyang District, Beijing 100029 , China
| | - Jinglei Nie
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering , Beijing University of Chemical Technology , North Third Ring Road 15 , Chaoyang District, Beijing 100029 , China
| | - Chuang Wang
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering , Beijing University of Chemical Technology , North Third Ring Road 15 , Chaoyang District, Beijing 100029 , China
| | - An-Ping Zeng
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering , Beijing University of Chemical Technology , North Third Ring Road 15 , Chaoyang District, Beijing 100029 , China
- Institute of Bioprocess and Biosystems Engineering , Hamburg University of Technology , Denickestrasse 15 , D-21073 Hamburg , Germany
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23
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Chen J, Vestergaard M, Shen J, Solem C, Dufva M, Jensen PR. Droplet-based microfluidics as a future tool for strain improvement in lactic acid bacteria. FEMS Microbiol Lett 2019. [DOI: 10.1093/femsle/fny258s] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
ABSTRACTStrain development is frequently used to improve the performance and functionality of industrially important microbes. As traditional mutagenesis screen is especially utilized by the food industry to improve strains used in food fermentation, high-throughput and cost-effective screening tools are important in mutant selection. The emerging droplet-based microfluidics technology miniaturizes the volume for cell cultivation and phenotype interrogation down to the picoliter scales, which facilitates screening of microbes for improved phenotypical properties tremendously. In this mini review, we present recent application of the droplet-based microfluidics in microbial strain improvement with a focus on its potential use in the screening of lactic acid bacteria.
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Affiliation(s)
- Jun Chen
- National Food Institute, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Mike Vestergaard
- National Food Institute, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Jing Shen
- National Food Institute, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Christian Solem
- National Food Institute, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Martin Dufva
- Department of Micro- and Nanotechnology, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Peter Ruhdal Jensen
- National Food Institute, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
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24
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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: 87] [Impact Index Per Article: 17.4] [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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25
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Jang S, Jang S, Im DK, Kang TJ, Oh MK, Jung GY. Artificial Caprolactam-Specific Riboswitch as an Intracellular Metabolite Sensor. ACS Synth Biol 2019; 8:1276-1283. [PMID: 31074964 DOI: 10.1021/acssynbio.8b00452] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Caprolactam is a monomer used for the synthesis of nylon-6, and a recombinant microbial strain for biobased production of nylon-6 was recently developed. An intracellular biosensor for caprolactam can facilitate high-throughput metabolic engineering of recombinant microbial strains. Because of the mixed production of caprolactam and valerolactam in the recombinant strain, a caprolactam biosensor should be highly specific for caprolactam. However, a highly specific caprolactam sensor has not been reported. Here, we developed an artificial riboswitch that specifically responds to caprolactam. This riboswitch was prepared using a coupled in vitro- in vivo selection strategy with a heterogeneous pool of RNA aptamers obtained from in vitro selection to construct a riboswitch library used in in vivo selection. The caprolactam riboswitch successfully discriminated caprolactam from valerolactam. Moreover, the riboswitch was activated by 3.36-fold in the presence of 50 mM caprolactam. This riboswitch enabled caprolactam-dependent control of cell growth, which will be useful for improving caprolactam production and is a valuable tool for metabolic engineering.
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Affiliation(s)
- Sungyeon Jang
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, Korea
| | - Sungho Jang
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, Korea
| | - Dae-Kyun Im
- Department of Chemical and Biological Engineering, Korea University, 145 Anam-Ro, Seongbuk-Gu, Seoul 02841, Korea
| | - Taek Jin Kang
- Department of Chemical and Biochemical Engineering, Dongguk University-Seoul, 30 Pildong-Ro 1-Gil, Jung-Gu, Seoul 04620, Korea
| | - Min-Kyu Oh
- Department of Chemical and Biological Engineering, Korea University, 145 Anam-Ro, Seongbuk-Gu, Seoul 02841, Korea
| | - Gyoo Yeol Jung
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, Korea
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, Korea
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26
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Buerger J, Gronenberg LS, Genee HJ, Sommer MOA. Wiring cell growth to product formation. Curr Opin Biotechnol 2019; 59:85-92. [PMID: 30928842 DOI: 10.1016/j.copbio.2019.02.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 01/24/2019] [Accepted: 02/19/2019] [Indexed: 01/07/2023]
Abstract
Microbial cell factories offer new and sustainable production routes for high-value chemicals. However, identification of high producers within a library of clones remains a challenge. When product formation is coupled to growth, millions of metabolic variants can be effectively interrogated by growth selection, dramatically increasing the throughput of strain evaluation. While growth-coupled selections for cell factories have a long history of success based on metabolite auxotrophies and toxic antimetabolites, such methods are generally restricted to molecules native to their host metabolism. New synthetic biology tools offer the opportunity to rewire cellular metabolism to depend on specific and non-native products for growth.
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Affiliation(s)
- Josi Buerger
- Biosyntia ApS, DK-2100 Copenhagen OE, Denmark; Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | | | | | - Morten O A Sommer
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark.
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27
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Dwidar M, Yokobayashi Y. Riboswitch Signal Amplification by Controlling Plasmid Copy Number. ACS Synth Biol 2019; 8:245-250. [PMID: 30682247 DOI: 10.1021/acssynbio.8b00454] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Riboswitches are cis-acting RNA devices in mRNAs that control gene expression in response to chemical inputs. As RNA aptamers that recognize diverse classes of molecules can be isolated by in vitro selection, synthetic riboswitches hold promise for various applications in synthetic biology. One of the major drawbacks of riboswitches, however, is their limited dynamic range. A high level of gene expression in the OFF state (leakage) is also a common problem. To address these challenges, we designed and constructed a dual-riboswitch plasmid in which two genes are controlled by theophylline-activated riboswitches. One riboswitch controls the gene of interest, and another riboswitch controls RepL, a phage-derived replication protein that regulates the plasmid copy number. This single-plasmid system afforded an ON/OFF ratio as high as 3900. Furthermore, we used the system to control CRISPR interference (CRISPRi) targeting endogenous genes, and successfully observed expected phenotypic changes in Escherichia coli.
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Affiliation(s)
- Mohammed Dwidar
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904 0495, Japan
| | - Yohei Yokobayashi
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904 0495, Japan
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Page K, Shaffer J, Lin S, Zhang M, Liu JM. Engineering Riboswitches in Vivo Using Dual Genetic Selection and Fluorescence-Activated Cell Sorting. ACS Synth Biol 2018; 7:2000-2006. [PMID: 30119599 DOI: 10.1021/acssynbio.8b00099] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Riboswitches, noncoding RNAs that bind a small molecule effector to control gene expression at the level of transcription or translation, are uniquely suited to meet challenges in synthetic biology. To expand the limited set of existing riboswitches, we developed a riboswitch discovery platform that couples dual genetic selection and fluorescence-activated cell sorting to identify novel riboswitches from a 108 random-sequence library in which the aptamer domain of the ThiM#2 riboswitch was replaced with an N40 sequence. In a proof-of-principle validation, we identified novel riboswitches for the small molecule theophylline. Our best riboswitch (Hit 3-5) displays 2.3-fold activation of downstream gene expression in the presence of theophylline. Random mutagenesis of Hit 3-5, coupled with selections and screens, afforded improved riboswitches displaying nearly 3-fold activation. To the best of our knowledge, this is the first report of in vivo directed evolution of an aptamer domain to generate a functional riboswitch.
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Affiliation(s)
- Katharine Page
- Department of Chemistry, Pomona College, 645 N. College Avenue, Claremont, California 91711, United States
| | - Jeremy Shaffer
- Department of Chemistry, Pomona College, 645 N. College Avenue, Claremont, California 91711, United States
| | - Samuel Lin
- Department of Chemistry, Pomona College, 645 N. College Avenue, Claremont, California 91711, United States
| | - Mark Zhang
- Department of Chemistry, Pomona College, 645 N. College Avenue, Claremont, California 91711, United States
| | - Jane M. Liu
- Department of Chemistry, Pomona College, 645 N. College Avenue, Claremont, California 91711, United States
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29
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Jang S, Jang S, Noh MH, Lim HG, Jung GY. Novel Hybrid Input Part Using Riboswitch and Transcriptional Repressor for Signal Inverting Amplifier. ACS Synth Biol 2018; 7:2199-2204. [PMID: 30092633 DOI: 10.1021/acssynbio.8b00213] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Genetic circuits are composed of input, logic, and output parts. Construction of complex circuits for practical applications requires numerous tunable genetic parts. However, the limited diversity and complicated tuning methods used for the input parts hinders the scalability of genetic circuits. Therefore, a new type of input part is required that responds to diverse signals and enables easy tuning. Here, we developed RNA-protein hybrid input parts that combine a riboswitch and orthogonal transcriptional repressors. The hybrid inputs successfully regulated the transcription of an output in response to the input signal detected by the riboswitch and resulted in signal inversion because of the expression of transcriptional repressors. Dose-response parameters including fold-change and half-maximal effective concentration were easily modulated and amplified simply by changing the promoter strength. Furthermore, the hybrid input detected both exogenous and endogenous signals, indicating potential applications in metabolite sensing. This hybrid input part could be highly extensible considering the rich variety of components.
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Affiliation(s)
- Sungyeon Jang
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, Korea
| | - Sungho Jang
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, Korea
| | - Myung Hyun Noh
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, Korea
| | - Hyun Gyu Lim
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, Korea
| | - Gyoo Yeol Jung
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, Korea
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, Korea
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30
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Kent R, Halliwell S, Young K, Swainston N, Dixon N. Rationalizing Context-Dependent Performance of Dynamic RNA Regulatory Devices. ACS Synth Biol 2018; 7:1660-1668. [PMID: 29928800 DOI: 10.1021/acssynbio.8b00041] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The ability of RNA to sense, regulate, and store information is an attractive attribute for a variety of functional applications including the development of regulatory control devices for synthetic biology. RNA folding and function is known to be highly context sensitive, which limits the modularity and reuse of RNA regulatory devices to control different heterologous sequences and genes. We explored the cause and effect of sequence context sensitivity for translational ON riboswitches located in the 5' UTR, by constructing and screening a library of N-terminal synonymous codon variants. By altering the N-terminal codon usage we were able to obtain RNA devices with a broad range of functional performance properties (ON, OFF, fold-change). Linear regression and calculated metrics were used to rationalize the major determining features leading to optimal riboswitch performance, and to identify multiple interactions between the explanatory metrics. Finally, partial least squared (PLS) analysis was employed in order to understand the metrics and their respective effect on performance. This PLS model was shown to provide good explanation of our library. This study provides a novel multivariant analysis framework to rationalize the codon context performance of allosteric RNA-devices. The framework will also serve as a platform for future riboswitch context engineering endeavors.
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Affiliation(s)
- Ross Kent
- Manchester Institute of Biotechnology, School of Chemistry, University of Manchester, Manchester, M13 9PL, United Kingdom
| | - Samantha Halliwell
- Manchester Institute of Biotechnology, School of Chemistry, University of Manchester, Manchester, M13 9PL, United Kingdom
| | - Kate Young
- Manchester Institute of Biotechnology, School of Chemistry, University of Manchester, Manchester, M13 9PL, United Kingdom
| | - Neil Swainston
- Manchester Institute of Biotechnology, School of Chemistry, University of Manchester, Manchester, M13 9PL, United Kingdom
| | - Neil Dixon
- Manchester Institute of Biotechnology, School of Chemistry, University of Manchester, Manchester, M13 9PL, United Kingdom
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31
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The evolving interface between synthetic biology and functional metagenomics. Nat Chem Biol 2018; 14:752-759. [DOI: 10.1038/s41589-018-0100-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 06/13/2018] [Indexed: 12/15/2022]
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Harbaugh SV, Martin JA, Weinstein J, Ingram G, Kelley-Loughnane N. Screening and selection of artificial riboswitches. Methods 2018; 143:77-89. [PMID: 29778645 DOI: 10.1016/j.ymeth.2018.05.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 05/14/2018] [Accepted: 05/15/2018] [Indexed: 01/04/2023] Open
Abstract
Synthetic riboswitches are engineered to regulate gene expression in response to a variety of non-endogenous small molecules, and a challenge to select this engineered response requires robust screening tools. A new synthetic riboswitch can be created by linking an in vitro-selected aptamer library with a randomized expression platform followed by in vivo selection and screening. In order to determine response to analyte, we developed a dual-color reporter comprising elements of the E. coli fimbriae phase variation system: recombinase FimE controlled by a synthetic riboswitch and an invertible DNA segment (fimS) containing a constitutively active promoter placed between two fluorescent protein genes. Without an analyte, the fluorescent reporter constitutively expressed green fluorescent protein (GFPa1). Addition of the analyte initiated translation of fimE causing unidirectional inversion of the fimS segment and constitutive expression of red fluorescent protein (mKate2). The dual color reporter system can be used to select and to optimize artificial riboswitches in E. coli cells. In this work, the enriched library of aptamers incorporated into the riboswitch architecture reduces the sequence search space by offering a higher percentage of potential ligand binders. The study was designed to produce structure switching aptamers, a necessary feature for riboswitch function and efficiently quantify this function using the dual color reporter system.
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Affiliation(s)
- Svetlana V Harbaugh
- Airman Systems Directorate, 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson AFB, OH 45433, United States
| | - Jennifer A Martin
- Airman Systems Directorate, 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson AFB, OH 45433, United States
| | - Jenna Weinstein
- Airman Systems Directorate, 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson AFB, OH 45433, United States
| | - Grant Ingram
- Airman Systems Directorate, 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson AFB, OH 45433, United States
| | - Nancy Kelley-Loughnane
- Airman Systems Directorate, 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson AFB, OH 45433, United States.
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Yokobayashi Y. Small Molecule-Responsive RNA Switches (Bacteria): Important Element of Programming Gene Expression in Response to Environmental Signals in Bacteria. Synth Biol (Oxf) 2018. [DOI: 10.1002/9783527688104.ch9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Yohei Yokobayashi
- Okinawa Institute of Science and Technology Graduate University; Nucleic Acid Chemistry and Engineering Unit Onna-son; Okinawa 9040415 Japan
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34
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Seok JY, Yang J, Choi SJ, Lim HG, Choi UJ, Kim KJ, Park S, Yoo TH, Jung GY. Directed evolution of the 3-hydroxypropionic acid production pathway by engineering aldehyde dehydrogenase using a synthetic selection device. Metab Eng 2018; 47:113-120. [PMID: 29545147 DOI: 10.1016/j.ymben.2018.03.009] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 03/09/2018] [Accepted: 03/09/2018] [Indexed: 12/30/2022]
Abstract
3-Hydroxypropionic acid (3-HP) is an important platform chemical, and biological production of 3-HP from glycerol as a carbon source using glycerol dehydratase (GDHt) and aldehyde dehydrogenase (ALDH) has been revealed to be effective because it involves a relatively simple metabolic pathway and exhibits higher yield and productivity than other biosynthetic pathways. Despite the successful attempts of 3-HP production from glycerol, the biological process suffers from problems arising from low activity and inactivation of the two enzymes. To apply the directed evolutionary approach to engineer the 3-HP production system, we constructed a synthetic selection device using a 3-HP-responsive transcription factor and developed a selection approach for screening 3-HP-producing microorganisms. The method was applied to an ALDH library, specifically aldehyde-binding site library of alpha-ketoglutaric semialdehyde dehydrogenase (KGSADH). Only two serial cultures resulted in enrichment of strains showing increased 3-HP production, and an isolated KGSADH variant enzyme exhibited a 2.79-fold higher catalytic efficiency toward its aldehyde substrate than the wild-type one. This approach will provide the simple and efficient tool to engineer the pathway enzymes in metabolic engineering.
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Affiliation(s)
- Joo Yeon Seok
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, Republic of Korea
| | - Jina Yang
- School of Chemical and Biological Engineering, Institute of Chemical Process, Seoul National University, 1 Gwanak-Ro, Gwanak-Gu, Seoul 08826, Republic of Korea
| | - Sang Jin Choi
- Department of Molecular Science and Technology, Ajou University, 206 Worldcup-Ro, Yeongtong-Gu, Suwon 16499, Republic of Korea
| | - Hyun Gyu Lim
- Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, Republic of Korea
| | - Un Jong Choi
- Department of Molecular Science and Technology, Ajou University, 206 Worldcup-Ro, Yeongtong-Gu, Suwon 16499, Republic of Korea
| | - Kyung-Jin Kim
- School of Life Sciences, KNU Creative BioResearch Group, Kyungpook National University, Daehak-Ro 80, Buk-Ku, Daegu 702-701, Republic of Korea
| | - Sunghoon Park
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), UNIST-Gil 50, Eonyang-Eup, Ulju-Gun, Ulsan 449419, Republic of Korea
| | - Tae Hyeon Yoo
- Department of Molecular Science and Technology, Ajou University, 206 Worldcup-Ro, Yeongtong-Gu, Suwon 16499, Republic of Korea.
| | - Gyoo Yeol Jung
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, Republic of Korea; Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, Republic of Korea.
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35
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Jang S, Jang S, Xiu Y, Kang TJ, Lee SH, Koffas MAG, Jung GY. Development of Artificial Riboswitches for Monitoring of Naringenin In Vivo. ACS Synth Biol 2017; 6:2077-2085. [PMID: 28749656 DOI: 10.1021/acssynbio.7b00128] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Microbial strains are considered promising hosts for production of flavonoids because of their rapid growth rate and suitability for large-scale manufacturing. However, productivity and titer of current recombinant strains still do not meet the requirements of industrial processes. Genetically encoded biosensors have been applied for high-throughput screening or dynamic regulation of biosynthetic pathways for enhancing the performance of microbial strains that produce valuable chemicals. Currently, few protein sensor-regulators for flavonoids exist. Unlike the protein-based trans-regulating controllers, riboswitches can respond to their ligands faster and eliminate off-target effects. Here, we developed artificial riboswitches that activate gene expression in response to naringenin, an important flavonoid. RNA aptamers for naringenin were developed using SELEX and cloned upstream of a dual selectable marker gene to construct a riboswitch library. Two in vivo selection routes were applied separately to the library by supplementing naringenin at two different concentrations during enrichments to modulate the operational ranges of the riboswitches. The selected riboswitches were responsive to naringenin and activated gene expression up to 2.91-fold. Operational ranges of the riboswitches were distinguished on the basis of their selection route. Additionally, the specificity of the riboswitches was assessed, and their applicability as dynamic regulators was confirmed. Collectively, the naringenin riboswitches reported in this work will be valuable tools in metabolic engineering of microorganisms for the production of flavonoids.
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Affiliation(s)
- Sungho Jang
- Department
of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673, Korea
| | - Sungyeon Jang
- Department
of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673, Korea
| | - Yu Xiu
- Department
of Chemical and Biological Engineering, Center for Biotechnology and
Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
- State
Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
- Beijing
Key Laboratory of Bioactive Substances and Functional Food, Beijing Union University, Beijing 100191, China
| | - Taek Jin Kang
- Department
of Chemical and Biochemical Engineering, Dongguk University, 30 Pildong-ro 1-gil, Jung-gu, Seoul, 04620, Korea
| | - Sang-Hyeup Lee
- Department
of Life Chemistry, Catholic University of Daegu, Hayang-ro 13-13,
Hayang-eup, Gyeongsan, Gyeongbuk 38430, Korea
| | - Mattheos A. G. Koffas
- Department
of Chemical and Biological Engineering, Center for Biotechnology and
Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
- Department
of Biological Sciences, Center for Biotechnology and Interdisciplinary
Studies, Rensselaer Polytechnic Institutee, Troy, New York 12180, United States
| | - Gyoo Yeol Jung
- Department
of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673, Korea
- School
of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673, Korea
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36
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Dwidar M, Yokobayashi Y. Controlling Bdellovibrio bacteriovorus Gene Expression and Predation Using Synthetic Riboswitches. ACS Synth Biol 2017; 6:2035-2041. [PMID: 28812884 DOI: 10.1021/acssynbio.7b00171] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Bdellovibrio bacteriovorus is a predatory bacterium that feeds on Gram-negative bacteria including a wide range of pathogens and thus has potential applications as a biocontrol agent. Owing to its unique life cycle, however, there are limited tools that enable genetic manipulation of B. bacteriovorus. This work describes our first steps toward engineering the predatory bacterium for practical applications by developing basic genetic parts to control gene expression. Specifically, we evaluated four robust promoters that are active during the attack phase of B. bacteriovorus. Subsequently, we tested several synthetic riboswitches that have been reported to function in Escherichia coli, and identified theophylline-activated riboswitches that function in B. bacteriovorus. Finally, we inserted the riboswitch into the bacterial chromosome to regulate expression of the flagellar sigma factor fliA, which was previously predicted to be essential for predation, and observed that the engineered strain shows a faster predation kinetics in the presence of theophylline.
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Affiliation(s)
- Mohammed Dwidar
- Nucleic Acid Chemistry and
Engineering Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904 0495, Japan
| | - Yohei Yokobayashi
- Nucleic Acid Chemistry and
Engineering Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904 0495, Japan
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37
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Jang S, Jang S, Yang J, Seo SW, Jung GY. RNA-based dynamic genetic controllers: development strategies and applications. Curr Opin Biotechnol 2017; 53:1-11. [PMID: 29132120 PMCID: PMC7126020 DOI: 10.1016/j.copbio.2017.10.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 10/11/2017] [Accepted: 10/16/2017] [Indexed: 12/25/2022]
Abstract
Unique properties of RNA lead to the development of RNA-based dynamic genetic controllers. Natural riboswitches are re-engineered to detect new molecules. RNA-based regulatory mechanisms are exploited to construct novel dynamic RNA controllers. Computational methods and in vitro–in vivo selection enable de novo design of dynamic RNA controllers. Dynamic RNA controllers are utilized for metabolic engineering and synthetic biology.
Dynamic regulation of gene expression in response to various molecules is crucial for both basic science and practical applications. RNA is considered an attractive material for creating dynamic genetic controllers because of its specific binding to ligands, structural flexibility, programmability, and small size. Here, we review recent advances in strategies for developing RNA-based dynamic controllers and applications. First, we describe studies that re-engineered natural riboswitches to generate new dynamic controllers. Next, we summarize RNA-based regulatory mechanisms that have been exploited to build novel artificial dynamic controllers. We also discuss computational methods and high-throughput selection approaches for de novo design of dynamic RNA controllers. Finally, we explain applications of dynamic RNA controllers for metabolic engineering and synthetic biology.
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Affiliation(s)
- Sungho Jang
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673, Republic of Korea
| | - Sungyeon Jang
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673, Republic of Korea
| | - Jina Yang
- School of Chemical and Biological Engineering, Institute of Chemical Process, Seoul National University, 1, Gwanak-ro, Gwanak-Gu, Seoul 08826, Republic of Korea
| | - Sang Woo Seo
- School of Chemical and Biological Engineering, Institute of Chemical Process, Seoul National University, 1, Gwanak-ro, Gwanak-Gu, Seoul 08826, Republic of Korea.
| | - Gyoo Yeol Jung
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673, Republic of Korea; School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673, Republic of Korea.
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38
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Jang S, Jung GY. Systematic optimization of L-tryptophan riboswitches for efficient monitoring of the metabolite in Escherichia coli. Biotechnol Bioeng 2017; 115:266-271. [PMID: 28892124 DOI: 10.1002/bit.26448] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 08/11/2017] [Accepted: 09/08/2017] [Indexed: 12/31/2022]
Abstract
Riboswitches form a class of genetically encoded sensor-regulators and are considered as promising tools for monitoring various metabolites. Functional parameters of a riboswitch, like dynamic or operational range, should be optimized before the riboswitch is implemented in a specific application for monitoring the target molecule efficiently. However, optimization of a riboswitch was not straightforward and required detailed studies owing to its complex sequence-function relationship. Here, we present three approaches for tuning and optimization of functional parameters of a riboswitch using an artificial L-tryptophan riboswitch as an example. First, the constitutive expression level was adjusted to control the dynamic range of an L-tryptophan riboswitch. The dynamic range increased as the constitutive expression level increased. Then, the function of a riboswitch-encoded protein was utilized to connect the regulatory response of the riboswitch to another outcome for amplifying the dynamic range. Riboswitch-mediated control of the host cell growth enabled the amplification of the riboswitch response. Finally, L-tryptophan aptamers with different dissociation constants were employed to alter the operational range of the riboswitch. The dose-response curve was shifted towards higher L-tryptophan concentrations when an aptamer with higher dissociation constant was employed. All strategies were effective in modifying the distinct functional parameters of the L-tryptophan riboswitch, and they could be easily applied to optimization of other riboswitches owing to their simplicity.
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Affiliation(s)
- Sungho Jang
- Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, Gyeongbuk, Korea
| | - Gyoo Yeol Jung
- Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, Gyeongbuk, Korea.,School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang, Gyeongbuk, Korea
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39
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Findeiß S, Etzel M, Will S, Mörl M, Stadler PF. Design of Artificial Riboswitches as Biosensors. SENSORS 2017; 17:s17091990. [PMID: 28867802 PMCID: PMC5621056 DOI: 10.3390/s17091990] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 08/23/2017] [Accepted: 08/25/2017] [Indexed: 12/11/2022]
Abstract
RNA aptamers readily recognize small organic molecules, polypeptides, as well as other nucleic acids in a highly specific manner. Many such aptamers have evolved as parts of regulatory systems in nature. Experimental selection techniques such as SELEX have been very successful in finding artificial aptamers for a wide variety of natural and synthetic ligands. Changes in structure and/or stability of aptamers upon ligand binding can propagate through larger RNA constructs and cause specific structural changes at distal positions. In turn, these may affect transcription, translation, splicing, or binding events. The RNA secondary structure model realistically describes both thermodynamic and kinetic aspects of RNA structure formation and refolding at a single, consistent level of modelling. Thus, this framework allows studying the function of natural riboswitches in silico. Moreover, it enables rationally designing artificial switches, combining essentially arbitrary sensors with a broad choice of read-out systems. Eventually, this approach sets the stage for constructing versatile biosensors.
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Affiliation(s)
- Sven Findeiß
- Bioinformatics Group, Department of Computer Science, and Interdisciplinary Center for Bioinformatics, University Leipzig, Härtelstraße 16-18, 04107 Leipzig, Germany.
- Faculty of Computer Science, Research Group Bioinformatics and Computational Biology, University of Vienna, Währingerstraße 29, A-1090 Vienna, Austria.
- Faculty of Chemistry, Department of Theoretical Chemistry, University of Vienna, Währingerstraße 17, A-1090 Vienna, Austria.
| | - Maja Etzel
- Institute for Biochemistry, Leipzig University, Brüderstraße 34, 04103 Leipzig, Germany.
| | - Sebastian Will
- Bioinformatics Group, Department of Computer Science, and Interdisciplinary Center for Bioinformatics, University Leipzig, Härtelstraße 16-18, 04107 Leipzig, Germany.
- Faculty of Chemistry, Department of Theoretical Chemistry, University of Vienna, Währingerstraße 17, A-1090 Vienna, Austria.
- Institute for Biochemistry, Leipzig University, Brüderstraße 34, 04103 Leipzig, Germany.
| | - Mario Mörl
- Institute for Biochemistry, Leipzig University, Brüderstraße 34, 04103 Leipzig, Germany.
| | - Peter F Stadler
- Bioinformatics Group, Department of Computer Science, and Interdisciplinary Center for Bioinformatics, University Leipzig, Härtelstraße 16-18, 04107 Leipzig, Germany.
- Faculty of Chemistry, Department of Theoretical Chemistry, University of Vienna, Währingerstraße 17, A-1090 Vienna, Austria.
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, 04103 Leipzig, Germany.
- Max Planck Institute for Mathematics in the Sciences, Inselstraße 22, 04103 Leipzig, Germany.
- Fraunhofer Institute for Cell Therapy and Immunology, Perlickstrasse 1, 04103 Leipzig, Germany.
- Center for RNA in Technology and Health, University of Copenhagen, Grønnegårdsvej 3, 1870 Frederiksberg , Denmark.
- Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501, USA.
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40
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Yang P, Wang J, Pang Q, Zhang F, Wang J, Wang Q, Qi Q. Pathway optimization and key enzyme evolution of N-acetylneuraminate biosynthesis using an in vivo aptazyme-based biosensor. Metab Eng 2017; 43:21-28. [PMID: 28780284 DOI: 10.1016/j.ymben.2017.08.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Revised: 07/18/2017] [Accepted: 08/01/2017] [Indexed: 10/19/2022]
Abstract
N-acetylneuraminate (NeuAc) biosynthesis has drawn much attention owing to its wide applications in many aspects. Previously, we engineered for the first time an artificial NeuAc biosynthetic pathway in Escherichia coli using glucose as sole substrate. However, rigorous requirements for the flux and cofactor balance make subsequent strain improvement rather difficult. In this study, an in vivo NeuAc biosensor was designed and applied for genetic screening the mutant library of NeuAc producer. Its NeuAc responsive manner was demonstrated using sfgfp as a reporter and a Ni2+-based selection system was developed to couple the cell growth with in vivo NeuAc concentration. Employing this selection system, the NeuAc biosynthesis pathway was optimized and the key enzyme NeuAc synthase was evolved, which improved the titer by 34% and 23%, respectively. The final strain produced up to 8.31g/L NeuAc in minimal medium using glucose as sole carbon source. This work demonstrated the effectiveness of NeuAc biosensor in genetic screening and great potential in metabolic engineering of other organisms.
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Affiliation(s)
- Peng Yang
- State Key Laboratory of Microbial Technology, National Glycoengineering Center, Shandong University, Jinan 250100, People's Republic of China
| | - Jing Wang
- State Key Laboratory of Microbial Technology, National Glycoengineering Center, Shandong University, Jinan 250100, People's Republic of China
| | - Qingxiao Pang
- State Key Laboratory of Microbial Technology, National Glycoengineering Center, Shandong University, Jinan 250100, People's Republic of China
| | - Fengyu Zhang
- State Key Laboratory of Microbial Technology, National Glycoengineering Center, Shandong University, Jinan 250100, People's Republic of China
| | - Junshu Wang
- State Key Laboratory of Microbial Technology, National Glycoengineering Center, Shandong University, Jinan 250100, People's Republic of China
| | - Qian Wang
- State Key Laboratory of Microbial Technology, National Glycoengineering Center, Shandong University, Jinan 250100, People's Republic of China.
| | - Qingsheng Qi
- State Key Laboratory of Microbial Technology, National Glycoengineering Center, Shandong University, Jinan 250100, People's Republic of China.
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41
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Ryu YS, Chandran SP, Kim K, Lee SK. Oligo- and dsDNA-mediated genome editing using a tetA dual selection system in Escherichia coli. PLoS One 2017; 12:e0181501. [PMID: 28719630 PMCID: PMC5515457 DOI: 10.1371/journal.pone.0181501] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 07/03/2017] [Indexed: 12/26/2022] Open
Abstract
The ability to precisely and seamlessly modify a target genome is needed for metabolic engineering and synthetic biology techniques aimed at creating potent biosystems. Herein, we report on a promising method in Escherichia coli that relies on the insertion of an optimized tetA dual selection cassette followed by replacement of the same cassette with short, single-stranded DNA (oligos) or long, double-stranded DNA and the isolation of recombinant strains by negative selection using NiCl2. This method could be rapidly and successfully used for genome engineering, including deletions, insertions, replacements, and point mutations, without inactivation of the methyl-directed mismatch repair (MMR) system and plasmid cloning. The method we describe here facilitates positive genome-edited recombinants with selection efficiencies ranging from 57 to 92%. Using our method, we increased lycopene production (3.4-fold) by replacing the ribosome binding site (RBS) of the rate-limiting gene (dxs) in the 1-deoxy-D-xylulose-5-phosphate (DXP) biosynthesis pathway with a strong RBS. Thus, this method could be used to achieve scarless, proficient, and targeted genome editing for engineering E. coli strains.
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Affiliation(s)
- Young Shin Ryu
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
| | - Sathesh-Prabu Chandran
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
| | - Kyungchul Kim
- School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
| | - Sung Kuk Lee
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
- School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
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42
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Enabling tools for high-throughput detection of metabolites: Metabolic engineering and directed evolution applications. Biotechnol Adv 2017; 35:950-970. [PMID: 28723577 DOI: 10.1016/j.biotechadv.2017.07.005] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 06/07/2017] [Accepted: 07/11/2017] [Indexed: 12/21/2022]
Abstract
Within the Design-Build-Test Cycle for strain engineering, rapid product detection and selection strategies remain challenging and limit overall throughput. Here we summarize a wide variety of modalities that transduce chemical concentrations into easily measured absorbance, luminescence, and fluorescence signals. Specifically, we cover protein-based biosensors (including transcription factors), nucleic acid-based biosensors, coupled enzyme reactions, bioorthogonal chemistry, and fluorescent and chromogenic dyes and substrates as modalities for detection. We focus on the use of these methods for strain engineering and enzyme discovery and conclude with remarks on the current and future state of biosensor development for application in the metabolic engineering field.
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43
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Hallberg ZF, Su Y, Kitto RZ, Hammond MC. Engineering and In Vivo Applications of Riboswitches. Annu Rev Biochem 2017; 86:515-539. [PMID: 28375743 DOI: 10.1146/annurev-biochem-060815-014628] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Riboswitches are common gene regulatory units mostly found in bacteria that are capable of altering gene expression in response to a small molecule. These structured RNA elements consist of two modular subunits: an aptamer domain that binds with high specificity and affinity to a target ligand and an expression platform that transduces ligand binding to a gene expression output. Significant progress has been made in engineering novel aptamer domains for new small molecule inducers of gene expression. Modified expression platforms have also been optimized to function when fused with both natural and synthetic aptamer domains. As this field expands, the use of these privileged scaffolds has permitted the development of tools such as RNA-based fluorescent biosensors. In this review, we summarize the methods that have been developed to engineer new riboswitches and highlight applications of natural and synthetic riboswitches in enzyme and strain engineering, in controlling gene expression and cellular physiology, and in real-time imaging of cellular metabolites and signals.
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Affiliation(s)
- Zachary F Hallberg
- Department of Chemistry, University of California, Berkeley, California 94720;
| | - Yichi Su
- Department of Chemistry, University of California, Berkeley, California 94720;
| | - Rebekah Z Kitto
- Department of Chemistry, University of California, Berkeley, California 94720;
| | - Ming C Hammond
- Department of Chemistry, University of California, Berkeley, California 94720; .,Department of Molecular and Cell Biology, University of California, Berkeley, California 94720
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44
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Vigar JRJ, Wieden HJ. Engineering bacterial translation initiation - Do we have all the tools we need? Biochim Biophys Acta Gen Subj 2017; 1861:3060-3069. [PMID: 28315412 DOI: 10.1016/j.bbagen.2017.03.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 03/03/2017] [Accepted: 03/10/2017] [Indexed: 01/17/2023]
Abstract
BACKGROUND Reliable tools that allow precise and predictable control over gene expression are critical for the success of nearly all bioengineering applications. Translation initiation is the most regulated phase during protein biosynthesis, and is therefore a promising target for exerting control over gene expression. At the translational level, the copy number of a protein can be fine-tuned by altering the interaction between the translation initiation region of an mRNA and the ribosome. These interactions can be controlled by modulating the mRNA structure using numerous approaches, including small molecule ligands, RNAs, or RNA-binding proteins. A variety of naturally occurring regulatory elements have been repurposed, facilitating advances in synthetic gene regulation strategies. The pursuit of a comprehensive understanding of mechanisms governing translation initiation provides the framework for future engineering efforts. SCOPE OF REVIEW Here we outline state-of-the-art strategies used to predictably control translation initiation in bacteria. We also discuss current limitations in the field and future goals. MAJOR CONCLUSIONS Due to its function as the rate-determining step, initiation is the ideal point to exert effective translation regulation. Several engineering tools are currently available to rationally design the initiation characteristics of synthetic mRNAs. However, improvements are required to increase the predictability, effectiveness, and portability of these tools. GENERAL SIGNIFICANCE Predictable and reliable control over translation initiation will allow greater predictability when designing, constructing, and testing genetic circuits. The ability to build more complex circuits predictably will advance synthetic biology and contribute to our fundamental understanding of the underlying principles of these processes. "This article is part of a Special Issue entitled "Biochemistry of Synthetic Biology - Recent Developments" Guest Editor: Dr. Ilka Heinemann and Dr. Patrick O'Donoghue.
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Affiliation(s)
- Justin R J Vigar
- Alberta RNA Research and Training Institute, Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive West, Lethbridge, Alberta T1K 3M4, Canada
| | - Hans-Joachim Wieden
- Alberta RNA Research and Training Institute, Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive West, Lethbridge, Alberta T1K 3M4, Canada.
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45
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Etzel M, Mörl M. Synthetic Riboswitches: From Plug and Pray toward Plug and Play. Biochemistry 2017; 56:1181-1198. [PMID: 28206750 DOI: 10.1021/acs.biochem.6b01218] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In synthetic biology, metabolic engineering, and gene therapy, there is a strong demand for orthogonal or externally controlled regulation of gene expression. Here, RNA-based regulatory devices represent a promising emerging alternative to proteins, allowing a fast and direct control of gene expression, as no synthesis of regulatory proteins is required. Besides programmable ribozyme elements controlling mRNA stability, regulatory RNA structures in untranslated regions are highly interesting for engineering approaches. Riboswitches are especially well suited, as they show a modular composition of sensor and response elements, allowing a free combination of different modules in a plug-and-play-like mode. The sensor or aptamer domain specifically interacts with a trigger molecule as a ligand, modulating the activity of the adjacent response domain that controls the expression of the genes located downstream, in most cases at the level of transcription or translation. In this review, we discuss the recent advances and strategies for designing such synthetic riboswitches based on natural or artificial components and readout systems, from trial-and-error approaches to rational design strategies. As the past several years have shown dramatic development in this fascinating field of research, we can give only a limited overview of the basic riboswitch design principles that is far from complete, and we apologize for not being able to consider every successful and interesting approach described in the literature.
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Affiliation(s)
- Maja Etzel
- Institute for Biochemistry, Leipzig University , Brüderstrasse 34, 04103 Leipzig, Germany
| | - Mario Mörl
- Institute for Biochemistry, Leipzig University , Brüderstrasse 34, 04103 Leipzig, Germany
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46
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Shin KS, Kim S, Lee SK. Improvement of free fatty acid production using a mutant acyl-CoA thioesterase I with high specific activity in Escherichia coli. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:208. [PMID: 27761152 PMCID: PMC5053343 DOI: 10.1186/s13068-016-0622-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 09/24/2016] [Indexed: 06/06/2023]
Abstract
BACKGROUND Microbial production of oleochemicals has been actively studied in the last decade. Free fatty acids (FFAs) could be converted into a variety of molecules such as industrial products, consumer products, and fuels. FFAs have been produced in metabolically engineered Escherichia coli cells expressing a signal sequence-deficient acyl-CoA thioesterase I ('TesA). Nonetheless, increasing the expression level of 'TesA seems not to be an appropriate approach to scale up FFA production because a certain ratio of each component including fatty acid synthase and 'TesA is required for optimal production of FFAs. Thus, the catalytic activity of 'TesA should be rationally engineered instead of merely increasing the enzyme expression level to enhance the production of FFAs. RESULTS In this study, we constructed a sensing system with a fusion protein of tetracycline resistance protein and red fluorescent protein (RFP) under the control of a FadR-responsive promoter to select the desired mutants. Fatty acid-dependent growth and RFP expression allowed for selection of FFA-overproducing cells. A 'TesA mutant that produces a twofold greater amount of FFAs was isolated from an error-prone PCR mutant library of E. coli 'TesA. Its kinetic analysis revealed that substitution of Arg64 with Cys64 in the enzyme causes an approximately twofold increase in catalytic activity. CONCLUSIONS Because the expression of 'TesA in E. coli for the production of oleochemicals is almost an indispensable process, the proposed engineering approach has a potential to enhance the production of oleochemicals. The use of the catalytically active mutant 'TesAR64C should accelerate the manufacture of FFA-derived chemicals and fuels.
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Affiliation(s)
- Kwang Soo Shin
- School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919 Republic of Korea
| | - Sangwoo Kim
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919 Republic of Korea
| | - Sung Kuk Lee
- School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919 Republic of Korea
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919 Republic of Korea
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47
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Functional mining of transporters using synthetic selections. Nat Chem Biol 2016; 12:1015-1022. [DOI: 10.1038/nchembio.2189] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 07/28/2016] [Indexed: 12/11/2022]
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48
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Rogers JK, Taylor ND, Church GM. Biosensor-based engineering of biosynthetic pathways. Curr Opin Biotechnol 2016; 42:84-91. [PMID: 26998575 DOI: 10.1016/j.copbio.2016.03.005] [Citation(s) in RCA: 163] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 02/21/2016] [Accepted: 03/03/2016] [Indexed: 01/18/2023]
Abstract
Biosynthetic pathways provide an enzymatic route from inexpensive renewable resources to valuable metabolic products such as pharmaceuticals and plastics. Designing these pathways is challenging due to the complexities of biology. Advances in the design and construction of genetic variants has enabled billions of cells, each possessing a slightly different metabolic design, to be rapidly generated. However, our ability to measure the quality of these designs lags by several orders of magnitude. Recent research has enabled cells to report their own success in chemical production through the use of genetically encoded biosensors. A new engineering discipline is emerging around the creation and application of biosensors. Biosensors, implemented in selections and screens to identify productive cells, are paving the way for a new era of biotechnological progress.
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Affiliation(s)
- Jameson K Rogers
- Wyss Institute for Biologically Inspired Engineering Harvard University, 3 Blackfan Circle, Boston, MA 02115, USA
| | - Noah D Taylor
- Wyss Institute for Biologically Inspired Engineering Harvard University, 3 Blackfan Circle, Boston, MA 02115, USA
| | - George M Church
- Wyss Institute for Biologically Inspired Engineering Harvard University, 3 Blackfan Circle, Boston, MA 02115, USA.
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49
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McKeague M, Wong RS, Smolke CD. Opportunities in the design and application of RNA for gene expression control. Nucleic Acids Res 2016; 44:2987-99. [PMID: 26969733 PMCID: PMC4838379 DOI: 10.1093/nar/gkw151] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 02/29/2016] [Indexed: 12/15/2022] Open
Abstract
The past decade of synthetic biology research has witnessed numerous advances in the development of tools and frameworks for the design and characterization of biological systems. Researchers have focused on the use of RNA for gene expression control due to its versatility in sensing molecular ligands and the relative ease by which RNA can be modeled and designed compared to proteins. We review the recent progress in the field with respect to RNA-based genetic devices that are controlled through small molecule and protein interactions. We discuss new approaches for generating and characterizing these devices and their underlying components. We also highlight immediate challenges, future directions and recent applications of synthetic RNA devices in engineered biological systems.
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Affiliation(s)
- Maureen McKeague
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Remus S Wong
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Christina D Smolke
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
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50
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Hoffmann SA, Kruse SM, Arndt KM. Long-range transcriptional interference in E. coli used to construct a dual positive selection system for genetic switches. Nucleic Acids Res 2016; 44:e95. [PMID: 26932362 PMCID: PMC4889929 DOI: 10.1093/nar/gkw125] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 02/21/2016] [Indexed: 11/29/2022] Open
Abstract
We have investigated transcriptional interference between convergent genes in E. coli and demonstrate substantial interference for inter-promoter distances of as far as 3 kb. Interference can be elicited by both strong σ70 dependent and T7 promoters. In the presented design, a strong promoter driving gene expression of a ‘forward’ gene interferes with the expression of a ‘reverse’ gene by a weak promoter. This arrangement allows inversely correlated gene expression without requiring further regulatory components. Thus, modulation of the activity of the strong promoter alters expression of both the forward and the reverse gene. We used this design to develop a dual selection system for conditional operator site binding, allowing positive selection both for binding and for non-binding to DNA. This study demonstrates the utility of this novel system using the Lac repressor as a model protein for conditional DNA binding, and spectinomycin and chloramphenicol resistance genes as positive selection markers in liquid culture. Randomized LacI libraries were created and subjected to subsequent dual selection, but mispairing IPTG and selection cues in respect to the wild-type LacI response, allowing the isolation of a LacI variant with a reversed IPTG response within three rounds of library generation and dual selection.
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Affiliation(s)
- Stefan A Hoffmann
- Molecular Biotechnology, Institute for Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
| | - Sabrina M Kruse
- Molecular Biotechnology, Institute for Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
| | - Katja M Arndt
- Molecular Biotechnology, Institute for Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
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