1
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Zhao Y, Wang S. Experimental and biophysical modeling of transcription and translation dynamics in bacterial- and mammalian-based cell-free expression systems. SLAS Technol 2024; 29:100036. [PMID: 35231628 DOI: 10.1016/j.slast.2022.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 01/25/2022] [Accepted: 02/15/2022] [Indexed: 11/20/2022]
Abstract
Cell-free expression (CFE) systems have been used extensively in systems and synthetic biology as a promising platform for manufacturing proteins and chemicals. Currently, the most widely used CFE system is in vitro protein transcription and translation platform. As the rapidly increased applications and uses, it is crucial to have a standard biophysical model for quantitative studies of gene circuits, which will provide a fundamental understanding of basic working mechanisms of CFE systems. Current modeling approaches mainly focus on the characterization of E. coli-based CFE systems, a computational model that can be utilized for both bacterial- and mammalian-based CFE has not been investigated. Here, we developed a simple ODE (ordinary differential equation)-based biophysical model to simulate transcription and translation dynamics for both bacterial- and mammalian- based CFE systems. The key parameters were estimated and adjusted based on experimental results. We next tested four gene circuits to characterize kinetic dynamics of transcription and translation in E. coli- and HeLa-based CFE systems. The real-time transcription and translation were monitored using Broccoli aptamer, double stranded locked nucleic acid (dsLNA) probe and fluorescent protein. We demonstrated the difference of kinetic dynamics for transcription and translation in both systems, which will provide valuable information for quantitative genomic and proteomic studies. This simple biophysical model and the experimental data for both E. coli- and HeLa-based CFE will be useful for researchers that are interested in genetic engineering and CFE bio-manufacturing.
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Affiliation(s)
- Yuwen Zhao
- Department of Chemistry, Chemical and Biomedical Engineering, Tagliatela College of Engineering, University of New Haven, West Haven, CT, 06516, United States; Department of Biomedical Engineering, Lehigh University, Bethlehem, PA, 18015, United States
| | - Shue Wang
- Department of Chemistry, Chemical and Biomedical Engineering, Tagliatela College of Engineering, University of New Haven, West Haven, CT, 06516, United States.
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2
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Lee KH, Song J, Kim S, Han SR, Lee SW. Real-time monitoring strategies for optimization of in vitro transcription and quality control of RNA. Front Mol Biosci 2023; 10:1229246. [PMID: 37771458 PMCID: PMC10523567 DOI: 10.3389/fmolb.2023.1229246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 08/16/2023] [Indexed: 09/30/2023] Open
Abstract
RNA-based therapeutics and vaccines are opening up new avenues for modern medicine. To produce these useful RNA-based reagents, in vitro transcription (IVT) is an important reaction that primarily determines the yield and quality of the product. Therefore, IVT condition should be well optimized to achieve high yield and purity of transcribed RNAs. To this end, real-time monitoring of RNA production during IVT, which allows for fine tuning of the condition, would be required. Currently, light-up RNA aptamer and fluorescent dye pairs are considered as useful strategies to monitor IVT in real time. Fluorophore-labeled antisense probe-based methods can also be used for real-time IVT monitoring. In addition, a high-performance liquid chromatography (HPLC)-based method that can monitor IVT reagent consumption has been developed as a powerful tool to monitor IVT reaction in near real-time. This mini-review briefly introduces some strategies and examples for real-time IVT monitoring and discusses pros and cons of IVT monitoring methods.
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Affiliation(s)
| | - Jaehwi Song
- R&D Center, Rznomics Inc., Seongnam, Republic of Korea
| | | | | | - Seong-Wook Lee
- R&D Center, Rznomics Inc., Seongnam, Republic of Korea
- Department of Bioconvergence Engineering, Research Institute of Advanced Omics, Dankook University, Yongin, Republic of Korea
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3
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Zhang F, Wang Y, Wang X, Dong H, Chen M, Du N, Wang H, Hu W, Zhang K, Gu L. RT-IVT method allows multiplex real-time quantification of in vitro transcriptional mRNA production. Commun Biol 2023; 6:453. [PMID: 37095292 PMCID: PMC10124930 DOI: 10.1038/s42003-023-04830-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 04/11/2023] [Indexed: 04/26/2023] Open
Abstract
For the past 30 years, in vitro transcription (IVT) technology has been extensively used for RNA production or for basic transcriptional mechanism research. However, methods for mRNA quantification still need to be improved. In this study, we designed a RT-IVT method using binary fluorescence quencher (BFQ) probes and the PBCV-1 DNA ligase to quantify mRNA production in real-time by fluorescence resonance energy transfer (FRET) and RNA-splinted DNA ligation. Compared with existing methods, the RT-IVT method is inexpensive and non-radioactive, and can detect mRNA production in unpurified systems in real-time and shows high sensitivity and selectivity. The activity of T7 RNA polymerase and Escherichia coli RNA polymerase holoenzyme was then characterized with this method. We then multiplexed the real-time mRNA quantification for three T7 promoters on a RT-PCR thermocycler by using BFQ probes with different colored fluorophores that were specific for each target. Ultimately, we created an inexpensive multiplexed method to quantify mRNA production in real-time, and future research could use these methods to measure the affinity of transcriptional repressors to their target DNA sequence.
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Affiliation(s)
- Fengyu Zhang
- State Key Laboratory of Microbial Technology, Shandong University, 72 Binhai Road, 266237, Qingdao, China
| | - Yipeng Wang
- State Key Laboratory of Microbial Technology, Shandong University, 72 Binhai Road, 266237, Qingdao, China
| | - Xiaomeng Wang
- State Key Laboratory of Microbial Technology, Shandong University, 72 Binhai Road, 266237, Qingdao, China
| | - Hongjie Dong
- Shandong Institute of Parasitic Diseases, Shandong First Medical University & Shandong Academy of Medical Sciences, 11 Taibaizhong Road, 272033, Jining, China
| | - Min Chen
- State Key Laboratory of Microbial Technology, Shandong University, 72 Binhai Road, 266237, Qingdao, China
| | - Ning Du
- Institute of Ecology and Biodiversity, School of Life Sciences, Shandong University, 72 Binhai Road, 266237, Qingdao, China
| | - Hongwei Wang
- State Key Laboratory of Microbial Technology, Shandong University, 72 Binhai Road, 266237, Qingdao, China
| | - Wei Hu
- State Key Laboratory of Microbial Technology, Shandong University, 72 Binhai Road, 266237, Qingdao, China
| | - Kundi Zhang
- State Key Laboratory of Microbial Technology, Shandong University, 72 Binhai Road, 266237, Qingdao, China.
| | - Lichuan Gu
- State Key Laboratory of Microbial Technology, Shandong University, 72 Binhai Road, 266237, Qingdao, China.
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4
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Chung S, Lee CM, Zhang M. Advances in nanoparticle-based mRNA delivery for liver cancer and liver-associated infectious diseases. NANOSCALE HORIZONS 2022; 8:10-28. [PMID: 36260016 PMCID: PMC11144305 DOI: 10.1039/d2nh00289b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The liver is a vital organ that functions to detoxify the body. Liver cancer and infectious diseases such as influenza and malaria can fatally compromise liver function. mRNA delivery is a relatively new means of therapeutic treatment which enables expression of tumor or pathogenic antigens, and elicits immune responses for therapeutic or prophylactic effect. Novel nanoparticles with unique biological properties serving as mRNA carriers have allowed mRNA-based therapeutics to become more clinically viable and relevant. In this review, we highlight recent progress in development of nanoparticle-based mRNA delivery systems for treatment of various liver diseases. First, we present developments in nanoparticle systems used to deliver mRNAs, with specific focus on enhanced cellular uptake and endosomal escape achieved through the use of these nanoparticles. To provide context for diseases that target the liver, we provide an overview of the function and structure of the liver, as well as the role of the immune system in the liver. Then, mRNA-based therapeutic approaches for addressing HCC are highlighted. We also discuss nanoparticle-based mRNA vaccines for treating hepatotropic infectious diseases. Finally, we present current challenges in the clinical translation of nanoparticle-based mRNA delivery systems and provide outlooks for their utilization in treating liver-related diseases.
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Affiliation(s)
- Seokhwan Chung
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, USA.
| | - Chan Mi Lee
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, USA.
| | - Miqin Zhang
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, USA.
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5
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Gonzales D, Yandrapalli N, Robinson T, Zechner C, Tang TYD. Cell-Free Gene Expression Dynamics in Synthetic Cell Populations. ACS Synth Biol 2022; 11:205-215. [PMID: 35057626 PMCID: PMC8787815 DOI: 10.1021/acssynbio.1c00376] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Indexed: 11/29/2022]
Abstract
The ability to build synthetic cellular populations from the bottom-up provides the groundwork to realize minimal living tissues comprising single cells which can communicate and bridge scales into multicellular systems. Engineered systems made of synthetic micron-sized compartments and integrated reaction networks coupled with mathematical modeling can facilitate the design and construction of complex and multiscale chemical systems from the bottom-up. Toward this goal, we generated populations of monodisperse liposomes encapsulating cell-free expression systems (CFESs) using double-emulsion microfluidics and quantified transcription and translation dynamics within individual synthetic cells of the population using a fluorescent Broccoli RNA aptamer and mCherry protein reporter. CFE dynamics in bulk reactions were used to test different coarse-grained resource-limited gene expression models using model selection to obtain transcription and translation rate parameters by likelihood-based parameter estimation. The selected model was then applied to quantify cell-free gene expression dynamics in populations of synthetic cells. In combination, our experimental and theoretical approaches provide a statistically robust analysis of CFE dynamics in bulk and monodisperse synthetic cell populations. We demonstrate that compartmentalization of CFESs leads to different transcription and translation rates compared to bulk CFE and show that this is due to the semipermeable lipid membrane that allows the exchange of materials between the synthetic cells and the external environment.
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Affiliation(s)
- David
T. Gonzales
- Max
Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
- Center
for Systems Biology Dresden, 01307 Dresden, Germany
| | | | - Tom Robinson
- Max
Planck Institute of Colloids and Interfaces, 14476 Potsdam, Germany
| | - Christoph Zechner
- Max
Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
- Center
for Systems Biology Dresden, 01307 Dresden, Germany
- Physics
of Life, Cluster of Excellence, TU Dresden, 01603 Dresden, Germany
| | - T-Y. Dora Tang
- Max
Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
- Center
for Systems Biology Dresden, 01307 Dresden, Germany
- Physics
of Life, Cluster of Excellence, TU Dresden, 01603 Dresden, Germany
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6
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Chushak Y, Harbaugh S, Zimlich K, Alfred B, Chávez J, Kelley-Loughnane N. Characterization of synthetic riboswitch in cell-free protein expression systems. RNA Biol 2021; 18:1727-1738. [PMID: 33427029 DOI: 10.1080/15476286.2020.1868149] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
Riboswitches are RNA-based regulatory elements that utilize ligand-induced structural changes in the 5'-untranslated region of mRNA to regulate the expression of associated genes. The majority of synthetic riboswitches have been selected and tested in cell-based systems. Cell-free protein expression systems (CFPS) have several advantages for the development and testing of synthetic riboswitches, including eliminating interactions with complex cellular networks, and the decoupling of transcription and translation processes. To gain a better understanding of the riboswitch regulatory mechanism, to allow for more efficient riboswitch optimization and use for biosensing applications, we studied the performance of a theophylline-responsive synthetic riboswitch coupled with the superfolder green fluorescent protein (sfGFP) reporter gene in E. coli cellular extract and PURE cell-free systems. To monitor the mRNA dynamics, a malachite green aptamer sequence was added to the 3'-untranslated region of sfGFP mRNA. Performance of the theophylline riboswitch was compared with a constitutively expressed sfGFP (control). Transcription dynamics of the riboswitch mRNA was very similar to the transcription of the control mRNA for all theophylline concentrations tested in both E. coli extract and PURE CFPS. However, sfGFP expression in the riboswitch construct was one order of magnitude lower, even at the highest concentration of theophylline. A mathematical model of riboswitch activation governed by the kinetic trapping mechanism was developed. Two factors - a reduced fraction of mRNA in the 'ON' state and a considerably lower translation initiation rate in the riboswitch - contribute to the much lower level of protein expression in the theophylline riboswitch compared to the control construct.
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Affiliation(s)
- Yaroslav Chushak
- Air Force Research Laboratory, Henry M Jackson Foundation, Dayton, USA.,711 Human Performance Wing, Air Force Research Laboratory, Dayton, OH, USA
| | - Svetlana Harbaugh
- 711 Human Performance Wing, Air Force Research Laboratory, Dayton, OH, USA
| | - Kathryn Zimlich
- Air Force Research Laboratory, Henry M Jackson Foundation, Dayton, USA.,711 Human Performance Wing, Air Force Research Laboratory, Dayton, OH, USA
| | - Bryan Alfred
- 711 Human Performance Wing, Air Force Research Laboratory, Dayton, OH, USA
| | - Jorge Chávez
- 711 Human Performance Wing, Air Force Research Laboratory, Dayton, OH, USA
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7
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Laohakunakorn N, Lavickova B, Swank Z, Laurent J, Maerkl SJ. Steady-State Cell-Free Gene Expression with Microfluidic Chemostats. Methods Mol Biol 2021; 2229:189-203. [PMID: 33405223 DOI: 10.1007/978-1-0716-1032-9_9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cell-free synthetic biology offers an approach to building and testing gene circuits in a simplified environment free from the complexity of a living cell. Recent advances in microfluidic devices allowed cell-free reactions to run under nonequilibrium, steady-state conditions enabling the implementation of dynamic gene regulatory circuits in vitro. In this chapter, we present a detailed protocol to fabricate a microfluidic chemostat device which enables such an operation, detailing essential steps in photolithography, soft lithography, and hardware setup.
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Affiliation(s)
- Nadanai Laohakunakorn
- School of Biological Sciences, Institute of Quantitative Biology, Biochemistry and Biotechnology, University of Edinburgh, Edinburgh, UK
| | - Barbora Lavickova
- Institute of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Zoe Swank
- Institute of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Julie Laurent
- Institute of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Sebastian J Maerkl
- Institute of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
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8
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Abstract
Cell-free systems are a widely used research tool in systems and synthetic biology and a promising platform for manufacturing of proteins and chemicals. In the past, cell-free biology was primarily used to better understand fundamental biochemical processes. Notably, E. coli cell-free extracts were used in the 1960s to decipher the sequencing of the genetic code. Since then, the transcription and translation capabilities of cell-free systems have been repeatedly optimized to improve energy efficiency and product yield. Today, cell-free systems, in combination with the rise of synthetic biology, have taken on a new role as a promising technology for just-in-time manufacturing of therapeutically important biologics and high-value small molecules. They have also been implemented at an industrial scale for the production of antibodies and cytokines. In this review, we discuss the evolution of cell-free technologies, in particular advancements in extract preparation, cell-free protein synthesis, and cell-free metabolic engineering applications. We then conclude with a discussion of the mathematical modeling of cell-free systems. Mathematical modeling of cell-free processes could be critical to addressing performance bottlenecks and estimating the costs of cell-free manufactured products.
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9
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Laohakunakorn N, Grasemann L, Lavickova B, Michielin G, Shahein A, Swank Z, Maerkl SJ. Bottom-Up Construction of Complex Biomolecular Systems With Cell-Free Synthetic Biology. Front Bioeng Biotechnol 2020; 8:213. [PMID: 32266240 PMCID: PMC7105575 DOI: 10.3389/fbioe.2020.00213] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 03/03/2020] [Indexed: 12/16/2022] Open
Abstract
Cell-free systems offer a promising approach to engineer biology since their open nature allows for well-controlled and characterized reaction conditions. In this review, we discuss the history and recent developments in engineering recombinant and crude extract systems, as well as breakthroughs in enabling technologies, that have facilitated increased throughput, compartmentalization, and spatial control of cell-free protein synthesis reactions. Combined with a deeper understanding of the cell-free systems themselves, these advances improve our ability to address a range of scientific questions. By mastering control of the cell-free platform, we will be in a position to construct increasingly complex biomolecular systems, and approach natural biological complexity in a bottom-up manner.
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Affiliation(s)
- Nadanai Laohakunakorn
- School of Biological Sciences, Institute of Quantitative Biology, Biochemistry, and Biotechnology, University of Edinburgh, Edinburgh, United Kingdom
| | - Laura Grasemann
- School of Engineering, Institute of Bioengineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Barbora Lavickova
- School of Engineering, Institute of Bioengineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Grégoire Michielin
- School of Engineering, Institute of Bioengineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Amir Shahein
- School of Engineering, Institute of Bioengineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Zoe Swank
- School of Engineering, Institute of Bioengineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Sebastian J. Maerkl
- School of Engineering, Institute of Bioengineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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10
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Silverman AD, Karim AS, Jewett MC. Cell-free gene expression: an expanded repertoire of applications. Nat Rev Genet 2019; 21:151-170. [DOI: 10.1038/s41576-019-0186-3] [Citation(s) in RCA: 246] [Impact Index Per Article: 49.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/07/2019] [Indexed: 12/24/2022]
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11
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Wick S, Walsh DI, Bobrow J, Hamad-Schifferli K, Kong DS, Thorsen T, Mroszczyk K, Carr PA. PERSIA for Direct Fluorescence Measurements of Transcription, Translation, and Enzyme Activity in Cell-Free Systems. ACS Synth Biol 2019; 8:1010-1025. [PMID: 30920800 PMCID: PMC6830305 DOI: 10.1021/acssynbio.8b00450] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Quantification of biology's central dogma (transcription and translation) is pursued by a variety of methods. Direct, immediate, and ongoing quantification of these events is difficult to achieve. Common practice is to use fluorescent or luminescent proteins to report indirectly on prior cellular events, such as turning on a gene in a genetic circuit. We present an alternative approach, PURExpress-ReAsH-Spinach In-vitro Analysis (PERSIA). PERSIA provides information on the production of RNA and protein during cell-free reactions by employing short RNA and peptide tags. Upon synthesis, these tags yield quantifiable fluorescent signal without interfering with other biochemical events. We demonstrate the applicability of PERSIA in measuring cell-free transcription, translation, and other enzymatic activity in a variety of applications: from sequence-structure-function studies, to genetic code engineering, to testing antiviral drug resistance.
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Affiliation(s)
- Scott Wick
- MIT Lincoln Laboratory , Lexington , Massachusetts 02421 , United States
| | - David I Walsh
- MIT Lincoln Laboratory , Lexington , Massachusetts 02421 , United States
| | - Johanna Bobrow
- MIT Lincoln Laboratory , Lexington , Massachusetts 02421 , United States
| | - Kimberly Hamad-Schifferli
- Department of Engineering , University of Massachusetts Boston , Boston , Massachusetts 02125 , United States
| | - David S Kong
- MIT Media Lab , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| | - Todd Thorsen
- MIT Lincoln Laboratory , Lexington , Massachusetts 02421 , United States
| | - Keri Mroszczyk
- MIT Lincoln Laboratory , Lexington , Massachusetts 02421 , United States
| | - Peter A Carr
- MIT Lincoln Laboratory , Lexington , Massachusetts 02421 , United States
- Synthetic Biology Center at MIT , Cambridge , Massachusetts 02139 , United States
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12
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Doerr A, de Reus E, van Nies P, van der Haar M, Wei K, Kattan J, Wahl A, Danelon C. Modelling cell-free RNA and protein synthesis with minimal systems. Phys Biol 2019; 16:025001. [DOI: 10.1088/1478-3975/aaf33d] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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13
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Xiang Y, Dalchau N, Wang B. Scaling up genetic circuit design for cellular computing: advances and prospects. NATURAL COMPUTING 2018; 17:833-853. [PMID: 30524216 PMCID: PMC6244767 DOI: 10.1007/s11047-018-9715-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Synthetic biology aims to engineer and redesign biological systems for useful real-world applications in biomanufacturing, biosensing and biotherapy following a typical design-build-test cycle. Inspired from computer science and electronics, synthetic gene circuits have been designed to exhibit control over the flow of information in biological systems. Two types are Boolean logic inspired TRUE or FALSE digital logic and graded analog computation. Key principles for gene circuit engineering include modularity, orthogonality, predictability and reliability. Initial circuits in the field were small and hampered by a lack of modular and orthogonal components, however in recent years the library of available parts has increased vastly. New tools for high throughput DNA assembly and characterization have been developed enabling rapid prototyping, systematic in situ characterization, as well as automated design and assembly of circuits. Recently implemented computing paradigms in circuit memory and distributed computing using cell consortia will also be discussed. Finally, we will examine existing challenges in building predictable large-scale circuits including modularity, context dependency and metabolic burden as well as tools and methods used to resolve them. These new trends and techniques have the potential to accelerate design of larger gene circuits and result in an increase in our basic understanding of circuit and host behaviour.
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Affiliation(s)
- Yiyu Xiang
- School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3FF UK
- Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh, EH9 3JR UK
| | | | - Baojun Wang
- School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3FF UK
- Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh, EH9 3JR UK
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14
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Wang S, Majumder S, Emery NJ, Liu AP. Simultaneous monitoring of transcription and translation in mammalian cell-free expression in bulk and in cell-sized droplets. Synth Biol (Oxf) 2018; 3:ysy005. [PMID: 30003145 PMCID: PMC6034425 DOI: 10.1093/synbio/ysy005] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 03/24/2018] [Accepted: 04/17/2018] [Indexed: 12/17/2022] Open
Abstract
Transcription and translation are two critical processes during eukaryotic gene expression that regulate cellular activities. The development of mammalian cell-free expression (CFE) systems provides a platform for studying these two critical processes in vitro for bottom-up synthetic biology applications such as construction of an artificial cell. Moreover, real-time monitoring of the dynamics of synthesized mRNA and protein is key to characterize and optimize gene circuits before implementing in living cells or in artificial cells. However, there are few tools for measurement of mRNA and protein dynamics in mammalian CFE systems. Here, we developed a locked nucleic acid (LNA) probe for monitoring transcription in a HeLa-based CFE system in real-time. By using this LNA probe in conjunction with a fluorescent reporter protein, we were able to simultaneously monitor mRNA and protein dynamics in bulk reactions and cell-sized single-emulsion droplets. We found rapid production of mRNA transcripts that decreased over time as protein production ensued in bulk reactions. Our results also showed that transcription in cell-sized droplets has different dynamics compared to the transcription in bulk reactions. The use of this LNA probe in conjunction with fluorescent proteins in HeLa-based mammalian CFE system provides a versatile in vitro platform for studying mRNA dynamics for bottom-up synthetic biology applications.
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Affiliation(s)
- Shue Wang
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Sagardip Majumder
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Nicholas J Emery
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA.,Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Allen P Liu
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA.,Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA.,Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI, USA.,Biophysics Program, University of Michigan, Ann Arbor, MI, USA
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15
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Senoussi A, Lee Tin Wah J, Shimizu Y, Robert J, Jaramillo A, Findeiss S, Axmann IM, Estevez-Torres A. Quantitative Characterization of Translational Riboregulators Using an in Vitro Transcription-Translation System. ACS Synth Biol 2018; 7:1269-1278. [PMID: 29617125 DOI: 10.1021/acssynbio.7b00387] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Riboregulators are short RNA sequences that, upon binding to a ligand, change their secondary structure and influence the expression rate of a downstream gene. They constitute an attractive alternative to transcription factors for building synthetic gene regulatory networks because they can be engineered de novo. However, riboregulators are generally designed in silico and tested in vivo, which provides little quantitative information about their performances, thus hindering the improvement of design algorithms. Here we show that a cell-free transcription-translation (TX-TL) system provides valuable information about the performances of in silico designed riboregulators. We first propose a simple model that provides a quantitative definition of the dynamic range of a riboregulator. We further characterize two types of translational riboregulators composed of a cis-repressed (cr) and a trans-activating (ta) strand. At the DNA level we demonstrate that high concentrations of taDNA poisoned the activator until total shut off, in agreement with our model, and that relative dynamic ranges of riboregulators determined in vitro are in agreement with published in vivo data. At the RNA level, we show that this approach provides a fast and simple way to measure dissociation constants of functional riboregulators, in contrast to standard mobility-shift assays. Our method opens the route for using cell-free TX-TL systems for the quantitative characterization of functional riboregulators in order to improve their design in silico.
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Affiliation(s)
- Anis Senoussi
- Sorbonne Université and CNRS, Laboratoire Jean Perrin, F-75005, Paris, France
| | | | - Yoshihiro Shimizu
- Laboratory for Cell-Free Protein Synthesis, RIKEN Quantitative Biology Center, Osaka 565-0874, Japan
| | - Jérôme Robert
- Sorbonne Université and CNRS, Laboratoire Jean Perrin, F-75005, Paris, France
| | - Alfonso Jaramillo
- Warwick Integrative Synthetic Biology Centre and School of Life Sciences, University of Warwick, CV4 7AL, Coventry, U.K
- CNRS Laboratoire iSSB, Université Paris-Saclay, Université d’ Évry and CEA, DRF, IG, Genoscope, F-91000 Évry, France
- Institute for Integrative Systems Biology, University of Valencia-CSIC, 46980 Paterna, Spain
| | - Sven Findeiss
- Dept. Computer Science and ICB, University Leipzig, D-04107 Leipzig, Germany
- University of Vienna, Faculties of Computer Science and Chemistry, Dept. of Theoretical Chemistry, A-1090 Vienna, Austria
| | - Ilka M. Axmann
- Institute for Synthetic Microbiology and CEPLAS, Heinrich Heine University Düsseldorf, D-40225 Düsseldorf, Germany
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16
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Rapid acquisition and model-based analysis of cell-free transcription-translation reactions from nonmodel bacteria. Proc Natl Acad Sci U S A 2018; 115:E4340-E4349. [PMID: 29666238 PMCID: PMC5948957 DOI: 10.1073/pnas.1715806115] [Citation(s) in RCA: 109] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Native cell-free transcription-translation systems offer a rapid route to characterize the regulatory elements (promoters, transcription factors) for gene expression from nonmodel microbial hosts, which can be difficult to assess through traditional in vivo approaches. One such host, Bacillus megaterium, is a giant Gram-positive bacterium with potential biotechnology applications, although many of its regulatory elements remain uncharacterized. Here, we have developed a rapid automated platform for measuring and modeling in vitro cell-free reactions and have applied this to B. megaterium to quantify a range of ribosome binding site variants and previously uncharacterized endogenous constitutive and inducible promoters. To provide quantitative models for cell-free systems, we have also applied a Bayesian approach to infer ordinary differential equation model parameters by simultaneously using time-course data from multiple experimental conditions. Using this modeling framework, we were able to infer previously unknown transcription factor binding affinities and quantify the sharing of cell-free transcription-translation resources (energy, ribosomes, RNA polymerases, nucleotides, and amino acids) using a promoter competition experiment. This allows insights into resource limiting-factors in batch cell-free synthesis mode. Our combined automated and modeling platform allows for the rapid acquisition and model-based analysis of cell-free transcription-translation data from uncharacterized microbial cell hosts, as well as resource competition within cell-free systems, which potentially can be applied to a range of cell-free synthetic biology and biotechnology applications.
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17
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Moore SJ, MacDonald JT, Freemont PS. Cell-free synthetic biology for in vitro prototype engineering. Biochem Soc Trans 2017; 45:785-791. [PMID: 28620040 PMCID: PMC5473021 DOI: 10.1042/bst20170011] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 03/24/2017] [Accepted: 03/31/2017] [Indexed: 12/21/2022]
Abstract
Cell-free transcription-translation is an expanding field in synthetic biology as a rapid prototyping platform for blueprinting the design of synthetic biological devices. Exemplar efforts include translation of prototype designs into medical test kits for on-site identification of viruses (Zika and Ebola), while gene circuit cascades can be tested, debugged and re-designed within rapid turnover times. Coupled with mathematical modelling, this discipline lends itself towards the precision engineering of new synthetic life. The next stages of cell-free look set to unlock new microbial hosts that remain slow to engineer and unsuited to rapid iterative design cycles. It is hoped that the development of such systems will provide new tools to aid the transition from cell-free prototype designs to functioning synthetic genetic circuits and engineered natural product pathways in living cells.
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Affiliation(s)
- Simon J Moore
- Department of Medicine, Centre for Synthetic Biology and Innovation, South Kensington Campus, London, U.K
| | - James T MacDonald
- Department of Medicine, Centre for Synthetic Biology and Innovation, South Kensington Campus, London, U.K
| | - Paul S Freemont
- Department of Medicine, Centre for Synthetic Biology and Innovation, South Kensington Campus, London, U.K.
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18
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Perez JG, Stark JC, Jewett MC. Cell-Free Synthetic Biology: Engineering Beyond the Cell. Cold Spring Harb Perspect Biol 2016; 8:cshperspect.a023853. [PMID: 27742731 DOI: 10.1101/cshperspect.a023853] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cell-free protein synthesis (CFPS) technologies have enabled inexpensive and rapid recombinant protein expression. Numerous highly active CFPS platforms are now available and have recently been used for synthetic biology applications. In this review, we focus on the ability of CFPS to expand our understanding of biological systems and its applications in the synthetic biology field. First, we outline a variety of CFPS platforms that provide alternative and complementary methods for expressing proteins from different organisms, compared with in vivo approaches. Next, we review the types of proteins, protein complexes, and protein modifications that have been achieved using CFPS systems. Finally, we introduce recent work on genetic networks in cell-free systems and the use of cell-free systems for rapid prototyping of in vivo networks. Given the flexibility of cell-free systems, CFPS holds promise to be a powerful tool for synthetic biology as well as a protein production technology in years to come.
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Affiliation(s)
- Jessica G Perez
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208-3120.,Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois 60208-3120
| | - Jessica C Stark
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208-3120.,Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois 60208-3120
| | - Michael C Jewett
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208-3120.,Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois 60208-3120.,Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, Illinois 60611-3068.,Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, Illinois 60611-2875
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19
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Zhang L, Tripathi A. Archaeal RNA ligase from thermoccocus kodakarensis for template dependent ligation. RNA Biol 2016; 14:36-44. [PMID: 27715457 DOI: 10.1080/15476286.2016.1239688] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Nicking-sealing RNA ligases play a significant biological role in host defense and cellular repair, and have become an important molecular tool in biomedical engineering. Due to the propensity for RNA to form secondary structures, RNA modifying enzymes with elevated optimum temperatures are highly desired. Current characterized double stranded RNA ligases, such as the bacteriophage T4 RNA ligase 2, while possessing good template dependency, are not active at elevated temperatures. The few characterized RNA ligases from thermophiles exhibit high template independency. We synthesize and characterize here, KOD RNA ligase (KOD1Rnl), a thermostable and template dependent RNA ligase from the archaeon, Thermoccocus Kodakarensis. We disclose that a 13 time reduction in template independent ligation can be achieved with the addition of a single stranded DNase, such as RecJ. We also elucidate the effects of the presence of blood proteins on the activity of KOD1Rnl. Template dependent and thermostable RNA ligases, such as KOD RNA ligase, can be utilized in RNA detection, modification and sequencing.
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Affiliation(s)
- Lei Zhang
- a Center for Biomedical Engineering, School of Engineering, Brown University , Providence , RI , USA
| | - Anubhav Tripathi
- a Center for Biomedical Engineering, School of Engineering, Brown University , Providence , RI , USA
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20
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Maddalena LLD, Niederholtmeyer H, Turtola M, Swank ZN, Belogurov GA, Maerkl SJ. GreA and GreB Enhance Expression of Escherichia coli RNA Polymerase Promoters in a Reconstituted Transcription-Translation System. ACS Synth Biol 2016; 5:929-35. [PMID: 27186988 DOI: 10.1021/acssynbio.6b00017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cell-free environments are becoming viable alternatives for implementing biological networks in synthetic biology. The reconstituted cell-free expression system (PURE) allows characterization of genetic networks under defined conditions but its applicability to native bacterial promoters and endogenous genetic networks is limited due to the poor transcription rate of Escherichia coli RNA polymerase in this minimal system. We found that addition of transcription elongation factors GreA and GreB to the PURE system increased transcription rates of E. coli RNA polymerase from sigma factor 70 promoters up to 6-fold and enhanced the performance of a genetic network. Furthermore, we reconstituted activation of natural E. coli promoters controlling flagella biosynthesis by the transcriptional activator FlhDC and sigma factor 28. Addition of GreA/GreB to the PURE system allows efficient expression from natural and synthetic E. coli promoters and characterization of their regulation in minimal and defined reaction conditions, making the PURE system more broadly applicable to study genetic networks and bottom-up synthetic biology.
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Affiliation(s)
- Lea L. de Maddalena
- Institute
of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Henrike Niederholtmeyer
- Institute
of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Matti Turtola
- Department
of Biochemistry, University of Turku, FI-20014 Turku, Finland
| | - Zoe N. Swank
- Institute
of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | | | - Sebastian J. Maerkl
- Institute
of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
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21
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Takahashi MK, Hayes CA, Chappell J, Sun ZZ, Murray RM, Noireaux V, Lucks JB. Characterizing and prototyping genetic networks with cell-free transcription–translation reactions. Methods 2015; 86:60-72. [DOI: 10.1016/j.ymeth.2015.05.020] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 05/20/2015] [Accepted: 05/21/2015] [Indexed: 02/07/2023] Open
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22
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Fritz BR, Jamil OK, Jewett MC. Implications of macromolecular crowding and reducing conditions for in vitro ribosome construction. Nucleic Acids Res 2015; 43:4774-84. [PMID: 25897121 PMCID: PMC4482083 DOI: 10.1093/nar/gkv329] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 03/31/2015] [Indexed: 12/11/2022] Open
Abstract
In vitro construction of Escherichia coli ribosomes could elucidate a deeper understanding of these complex molecular machines and make possible the production of synthetic variants with new functions. Toward this goal, we recently developed an integrated synthesis, assembly and translation (iSAT) system that allows for co-activation of ribosomal RNA (rRNA) transcription and ribosome assembly, mRNA transcription and protein translation without intact cells. Here, we discovered that macromolecular crowding and reducing agents increase overall iSAT protein synthesis; the combination of 6% w/v Ficoll 400 and 2 mM DTBA yielded approximately a five-fold increase in overall iSAT protein synthesis activity. By utilizing a fluorescent RNA aptamer, fluorescent reporter proteins and ribosome sedimentation analysis, we showed that crowding agents increase iSAT yields by enhancing translation while reducing agents increase rRNA transcription and ribosome assembly. Finally, we showed that iSAT ribosomes possess ∼70% of the protein synthesis activity of in vivo-assembled E. coli ribosomes. This work improves iSAT protein synthesis through the addition of crowding and reducing agents, provides a thorough understanding of the effect of these additives within the iSAT system and demonstrates how iSAT allows for manipulation and analysis of ribosome biogenesis in the context of an in vitro transcription-translation system.
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Affiliation(s)
- Brian R Fritz
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA
| | - Osman K Jamil
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA
| | - Michael C Jewett
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA Interdisciplinary Biological Sciences Graduate Program, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA Northwestern Institute on Complex Systems, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA Simpson Querrey Institute, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA Chemistry of Life Processes Institute, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA
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23
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van Nies P, Canton AS, Nourian Z, Danelon C. Monitoring mRNA and Protein Levels in Bulk and in Model Vesicle-Based Artificial Cells. Methods Enzymol 2015; 550:187-214. [DOI: 10.1016/bs.mie.2014.10.048] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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24
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Siegal-Gaskins D, Tuza ZA, Kim J, Noireaux V, Murray RM. Gene circuit performance characterization and resource usage in a cell-free "breadboard". ACS Synth Biol 2014; 3:416-25. [PMID: 24670245 DOI: 10.1021/sb400203p] [Citation(s) in RCA: 137] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The many successes of synthetic biology have come in a manner largely different from those in other engineering disciplines; in particular, without well-characterized and simplified prototyping environments to play a role analogous to wind-tunnels in aerodynamics and breadboards in electrical engineering. However, as the complexity of synthetic circuits increases, the benefits--in cost savings and design cycle time--of a more traditional engineering approach can be significant. We have recently developed an in vitro "breadboard" prototyping platform based on E. coli cell extract that allows biocircuits to operate in an environment considerably simpler than, but functionally similar to, in vivo. The simplicity of this system makes it a promising tool for rapid biocircuit design and testing, as well as for probing fundamental aspects of gene circuit operation normally masked by cellular complexity. In this work, we characterize the cell-free breadboard using real-time and simultaneous measurements of transcriptional and translational activities of a small set of reporter genes and a transcriptional activation cascade. We determine the effects of promoter strength, gene concentration, and nucleoside triphosphate concentration on biocircuit properties, and we isolate the specific contributions of essential biomolecular resources-core RNA polymerase and ribosomes-to overall performance. Importantly, we show how limits on resources, particularly those involved in translation, are manifested as reduced expression in the presence of orthogonal genes that serve as additional loads on the system.
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Affiliation(s)
- Dan Siegal-Gaskins
- Division
of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Zoltan A. Tuza
- Faculty
of Information Technology, Pazmany Peter Catholic University, 1088 Budapest, Hungary
| | - Jongmin Kim
- Division
of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Vincent Noireaux
- School
of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Richard M. Murray
- Division
of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, United States
- Department
of Control and Dynamical Systems, California Institute of Technology, Pasadena, California 91125, United States
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25
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Brophy JAN, Voigt CA. Principles of genetic circuit design. Nat Methods 2014; 11:508-20. [PMID: 24781324 DOI: 10.1038/nmeth.2926] [Citation(s) in RCA: 568] [Impact Index Per Article: 56.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 03/18/2014] [Indexed: 12/17/2022]
Abstract
Cells navigate environments, communicate and build complex patterns by initiating gene expression in response to specific signals. Engineers seek to harness this capability to program cells to perform tasks or create chemicals and materials that match the complexity seen in nature. This Review describes new tools that aid the construction of genetic circuits. Circuit dynamics can be influenced by the choice of regulators and changed with expression 'tuning knobs'. We collate the failure modes encountered when assembling circuits, quantify their impact on performance and review mitigation efforts. Finally, we discuss the constraints that arise from circuits having to operate within a living cell. Collectively, better tools, well-characterized parts and a comprehensive understanding of how to compose circuits are leading to a breakthrough in the ability to program living cells for advanced applications, from living therapeutics to the atomic manufacturing of functional materials.
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Affiliation(s)
- Jennifer A N Brophy
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Christopher A Voigt
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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26
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Smith MT, Wilding KM, Hunt JM, Bennett AM, Bundy BC. The emerging age of cell-free synthetic biology. FEBS Lett 2014; 588:2755-61. [PMID: 24931378 DOI: 10.1016/j.febslet.2014.05.062] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Revised: 05/29/2014] [Accepted: 05/30/2014] [Indexed: 01/16/2023]
Abstract
The engineering of and mastery over biological parts has catalyzed the emergence of synthetic biology. This field has grown exponentially in the past decade. As increasingly more applications of synthetic biology are pursued, more challenges are encountered, such as delivering genetic material into cells and optimizing genetic circuits in vivo. An in vitro or cell-free approach to synthetic biology simplifies and avoids many of the pitfalls of in vivo synthetic biology. In this review, we describe some of the innate features that make cell-free systems compelling platforms for synthetic biology and discuss emerging improvements of cell-free technologies. We also select and highlight recent and emerging applications of cell-free synthetic biology.
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Affiliation(s)
- Mark Thomas Smith
- Department of Chemical Engineering, Brigham Young University, Provo, UT, USA
| | - Kristen M Wilding
- Department of Chemical Engineering, Brigham Young University, Provo, UT, USA
| | - Jeremy M Hunt
- Department of Chemical Engineering, Brigham Young University, Provo, UT, USA
| | - Anthony M Bennett
- Department of Chemical Engineering, Brigham Young University, Provo, UT, USA
| | - Bradley C Bundy
- Department of Chemical Engineering, Brigham Young University, Provo, UT, USA.
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27
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Iyer S, Karig DK, Norred SE, Simpson ML, Doktycz MJ. Multi-input regulation and logic with T7 promoters in cells and cell-free systems. PLoS One 2013; 8:e78442. [PMID: 24194933 PMCID: PMC3806817 DOI: 10.1371/journal.pone.0078442] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Accepted: 09/10/2013] [Indexed: 11/21/2022] Open
Abstract
Engineered gene circuits offer an opportunity to harness biological systems for biotechnological and biomedical applications. However, reliance on native host promoters for the construction of circuit elements, such as logic gates, can make the implementation of predictable, independently functioning circuits difficult. In contrast, T7 promoters offer a simple orthogonal expression system for use in a variety of cellular backgrounds and even in cell-free systems. Here we develop a T7 promoter system that can be regulated by two different transcriptional repressors for the construction of a logic gate that functions in cells and in cell-free systems. We first present LacI repressible T7lacO promoters that are regulated from a distal lac operator site for repression. We next explore the positioning of a tet operator site within the T7lacO framework to create T7 promoters that respond to tet and lac repressors and realize an IMPLIES gate. Finally, we demonstrate that these dual input sensitive promoters function in an E. coli cell-free protein expression system. Our results expand the utility of T7 promoters in cell based as well as cell-free synthetic biology applications.
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Affiliation(s)
- Sukanya Iyer
- Graduate Program in Genome Science and Technology, University of Tennessee, Knoxville, Knoxville, Tennessee, United States of America
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States of America
| | - David K. Karig
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States of America
| | - S. Elizabeth Norred
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Knoxville, Tennessee, United States of America
| | - Michael L. Simpson
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States of America
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Knoxville, Tennessee, United States of America
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, Knoxville, Tennessee, United States of America
| | - Mitchel J. Doktycz
- Graduate Program in Genome Science and Technology, University of Tennessee, Knoxville, Knoxville, Tennessee, United States of America
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States of America
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States of America
- * E-mail:
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28
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Abstract
Living cells maintain a steady state of biochemical reaction rates by exchanging energy and matter with the environment. These exchanges usually do not occur in in vitro systems, which consequently go to chemical equilibrium. This in turn has severely constrained the complexity of biological networks that can be implemented in vitro. We developed nanoliter-scale microfluidic reactors that exchange reagents at dilution rates matching those of dividing bacteria. In these reactors we achieved transcription and translation at steady state for 30 h and implemented diverse regulatory mechanisms on the transcriptional, translational, and posttranslational levels, including RNA polymerases, transcriptional repression, translational activation, and proteolysis. We constructed and implemented an in vitro genetic oscillator and mapped its phase diagram showing that steady-state conditions were necessary to produce oscillations. This reactor-based approach will allow testing of whether fundamental limits exist to in vitro network complexity.
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