1
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Clark L, Voigt CA, Jewett MC. Establishing a High-Yield Chloroplast Cell-Free System for Prototyping Genetic Parts. ACS Synth Biol 2024. [PMID: 39023433 DOI: 10.1021/acssynbio.4c00111] [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: 07/20/2024]
Abstract
Plastid engineering offers the potential to carry multigene traits in plants; however, it requires reliable genetic parts to balance expression. The difficulty of chloroplast transformation and slow plant growth makes it challenging to build plants just to characterize genetic parts. To address these limitations, we developed a high-yield cell-free system from Nicotiana tabacum chloroplast extracts for prototyping genetic parts. Our cell-free system uses combined transcription and translation driven by T7 RNA polymerase and works with plasmid or linear template DNA. To develop our system, we optimized lysis, extract preparation procedures (e.g., runoff reaction, centrifugation, and dialysis), and the physiochemical reaction conditions. Our cell-free system can synthesize 34 ± 1 μg/mL luciferase in batch reactions and 60 ± 4 μg/mL in semicontinuous reactions. We apply our batch reaction system to test a library of 103 ribosome binding site (RBS) variants and rank them based on cell-free gene expression. We observe a 1300-fold dynamic range of luciferase expression when normalized by maximum mRNA expression, as assessed by the malachite green aptamer. We also find that the observed normalized gene expression in chloroplast extracts and the predictions made by the RBS Calculator are correlated. We anticipate that chloroplast cell-free systems will increase the speed and reliability of building genetic systems in plant chloroplasts for diverse applications.
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Affiliation(s)
- Lauren Clark
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Chemistry of Life Processes Institute, Evanston, Illinois 60208, United States
- Center for Synthetic Biology, Northwestern University, Evanston, Illinois 60208, United States
| | - Christopher A Voigt
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Michael C Jewett
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Chemistry of Life Processes Institute, Evanston, Illinois 60208, United States
- Center for Synthetic Biology, Northwestern University, Evanston, Illinois 60208, United States
- Robert H. Lurie Comprehensive Cancer Center, Chicago, Illinois 60611, United States
- Simpson Querrey Institute, Northwestern University, Chicago, Illinois 60611, United States
- Department of Bioengineering, Stanford University, Stanford, California 94305, United States
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2
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Adams JME, Moulding PB, El-Halfawy OM. Polyamine-Mediated Sensitization of Klebsiella pneumoniae to Macrolides through a Dual Mode of Action. ACS Infect Dis 2024; 10:2183-2195. [PMID: 38695481 DOI: 10.1021/acsinfecdis.4c00157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2024]
Abstract
Chemicals bacteria encounter at the infection site could shape their stress and antibiotic responses; such effects are typically undetected under standard lab conditions. Polyamines are small molecules typically overproduced by the host during infection and have been shown to alter bacterial stress responses. We sought to determine the effect of polyamines on the antibiotic response of Klebsiella pneumoniae, a Gram-negative priority pathogen. Interestingly, putrescine and other natural polyamines sensitized K. pneumoniae to azithromycin, a macrolide protein translation inhibitor typically used for Gram-positive bacteria. This synergy was further potentiated in the physiological buffer, bicarbonate. Chemical genomic screens suggested a dual mechanism, whereby putrescine acts at the membrane and ribosome levels. Putrescine permeabilized the outer membrane of K. pneumoniae (NPN and β-lactamase assays) and the inner membrane (Escherichia coli β-galactosidase assays). Chemically and genetically perturbing membranes led to a loss of putrescine-azithromycin synergy. Putrescine also inhibited protein synthesis in an E. coli-derived cell-free protein expression assay simultaneously monitoring transcription and translation. Profiling the putrescine-azithromycin synergy against a combinatorial array of antibiotics targeting various ribosomal sites suggested that putrescine acts as tetracyclines targeting the 30S ribosomal acceptor site. Next, exploiting the natural polyamine-azithromycin synergy, we screened a polyamine analogue library for azithromycin adjuvants, discovering four azithromycin synergists with activity starting from the low micromolar range and mechanisms similar to putrescine. This work sheds light on the bacterial antibiotic responses under conditions more reflective of those at the infection site and provides a new strategy to extend the macrolide spectrum to drug-resistant K. pneumoniae.
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Affiliation(s)
- Joshua M E Adams
- Department of Chemistry and Biochemistry, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada
| | - Peri B Moulding
- Department of Chemistry and Biochemistry, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada
| | - Omar M El-Halfawy
- Department of Chemistry and Biochemistry, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada
- Department of Microbiology and Immunology, Faculty of Pharmacy, Alexandria University, Alexandria, 21521, Egypt
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3
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Phillips EA, Silverman AD, Joneja A, Liu M, Brown C, Carlson P, Coticchia C, Shytle K, Larsen A, Goyal N, Cai V, Huang J, Hickey JE, Ryan E, Acheampong J, Ramesh P, Collins JJ, Blake WJ. Detection of viral RNAs at ambient temperature via reporter proteins produced through the target-splinted ligation of DNA probes. Nat Biomed Eng 2023; 7:1571-1582. [PMID: 37142844 PMCID: PMC10727988 DOI: 10.1038/s41551-023-01028-y] [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: 07/11/2022] [Accepted: 03/25/2023] [Indexed: 05/06/2023]
Abstract
Nucleic acid assays are not typically deployable in point-of-care settings because they require costly and sophisticated equipment for the control of the reaction temperature and for the detection of the signal. Here we report an instrument-free assay for the accurate and multiplexed detection of nucleic acids at ambient temperature. The assay, which we named INSPECTR (for internal splint-pairing expression-cassette translation reaction), leverages the target-specific splinted ligation of DNA probes to generate expression cassettes that can be flexibly designed for the cell-free synthesis of reporter proteins, with enzymatic reporters allowing for a linear detection range spanning four orders of magnitude and peptide reporters (which can be mapped to unique targets) enabling highly multiplexed visual detection. We used INSPECTR to detect a panel of five respiratory viral targets in a single reaction via a lateral-flow readout and ~4,000 copies of viral RNA via additional ambient-temperature rolling circle amplification of the expression cassette. Leveraging synthetic biology to simplify workflows for nucleic acid diagnostics may facilitate their broader applicability at the point of care.
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Affiliation(s)
| | | | | | | | - Carl Brown
- Sherlock Biosciences, Watertown, MA, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA
| | | | | | | | | | | | | | | | | | - Emily Ryan
- Sherlock Biosciences, Watertown, MA, USA
| | | | | | - James J Collins
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA
- Institute for Medical Engineering and Science, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Abdul Latif Jameel Clinic for Machine Learning in Health, Massachusetts Institute of Technology, Cambridge, MA, USA
- College of Arts and Sciences, Harvard University, Cambridge, MA, USA
- Synthetic Biology Center, Massachusetts Institute of Technology, Cambridge, MA, USA
- Harvard-MIT Program in Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - William J Blake
- Sherlock Biosciences, Watertown, MA, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA
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4
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Piorino F, Styczynski MP. Complex Dependence of Escherichia coli-based Cell-Free Expression on Sonication Energy During Lysis. ACS Synth Biol 2023; 12:3131-3136. [PMID: 37725792 PMCID: PMC10594866 DOI: 10.1021/acssynbio.3c00312] [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: 05/18/2023] [Indexed: 09/21/2023]
Abstract
Cell lysis─by sonication or bead beating, for example─is a key step in preparing extracts for cell-free expression systems. To create high protein-production capacity extracts, standard practice is to lyse cells sufficiently to thoroughly disrupt the membrane and thus extract expression machinery but without degrading that machinery. Here, we investigate the impact of different sonication energy inputs on the protein-production capacity of Escherichia coli extracts. While the existence of operator-specific optimal sonication energy inputs is widely known, our findings show that the sonication energy input that yields maximal protein output from a given expression template may depend on plasmid concentration, transcriptional and translational features (e.g., promoter), and other expression vector components (e.g., origin of replication). These results indicate that sonication protocols cannot be standardized to a single optimum, suggest strategies for improving protein yields, and more broadly highlight the need for better metrics and protocols for characterizing cell extracts.
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Affiliation(s)
- Fernanda Piorino
- School of Chemical & Biomolecular
Engineering, Georgia Institute of Technology, 311 Ferst Drive NW, Atlanta, Georgia 30332-0100, United States
| | - Mark P. Styczynski
- School of Chemical & Biomolecular
Engineering, Georgia Institute of Technology, 311 Ferst Drive NW, Atlanta, Georgia 30332-0100, United States
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5
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Piorino F, Patterson AT, Han Y, Styczynski MP. Plasmid Crosstalk in Cell-Free Expression Systems. ACS Synth Biol 2023; 12:2843-2856. [PMID: 37756020 PMCID: PMC10594874 DOI: 10.1021/acssynbio.3c00412] [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: 07/07/2023] [Indexed: 09/28/2023]
Abstract
Although cell-free protein expression has been widely used for the synthesis of single proteins, cell-free synthetic biology has rapidly expanded to new, more complex applications. One such application is the prototyping or implementation of complex genetic networks involving the expression of multiple proteins at precise ratios, often from different plasmids. However, expression of multiple proteins from multiple plasmids may inadvertently result in unexpected, off-target changes to the levels of the proteins being expressed, a phenomenon termed plasmid crosstalk. Here, we show that the effects of plasmid crosstalk─even at the qualitative level of increases vs decreases in protein expression─depend on the concentration of plasmids in the reaction and the type of transcriptional machinery involved in the expression. This crosstalk can have a significant impact on genetic circuitry function and even interpretation of simple experimental results and thus should be taken into consideration during the development of cell-free applications.
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Affiliation(s)
- Fernanda Piorino
- School
of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive NW, Atlanta, Georgia 30332-0100, United States
| | - Alexandra T. Patterson
- School
of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive NW, Atlanta, Georgia 30332-0100, United States
| | - Yue Han
- School
of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive NW, Atlanta, Georgia 30332-0100, United States
| | - Mark P. Styczynski
- School
of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive NW, Atlanta, Georgia 30332-0100, United States
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6
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Maerkl SJ. On biochemical constructors and synthetic cells. Interface Focus 2023; 13:20230014. [PMID: 37577005 PMCID: PMC10415740 DOI: 10.1098/rsfs.2023.0014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 05/30/2023] [Indexed: 08/15/2023] Open
Abstract
Is it possible to build life? More specifically, is it possible to create a living synthetic cell from inanimate building blocks? This question precipitated into one of the most significant grand challenges in biochemistry and synthetic biology, with several large research consortia forming around this endeavour in Europe (European Synthetic Cell Initiative), the USA (Build-a-Cell Initiative) and Japan (Japanese Society for Cell Synthesis Research). The mature field of biochemistry, the advent of synthetic biology in the early 2000s, and the burgeoning field of cell-free synthetic biology made it feasible to tackle this grand challenge.
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Affiliation(s)
- Sebastian J. Maerkl
- Institute of Bioengineering, School of Engineering, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Vaud, Switzerland
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7
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Zhang XE, Liu C, Dai J, Yuan Y, Gao C, Feng Y, Wu B, Wei P, You C, Wang X, Si T. Enabling technology and core theory of synthetic biology. SCIENCE CHINA. LIFE SCIENCES 2023; 66:1742-1785. [PMID: 36753021 PMCID: PMC9907219 DOI: 10.1007/s11427-022-2214-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 10/04/2022] [Indexed: 02/09/2023]
Abstract
Synthetic biology provides a new paradigm for life science research ("build to learn") and opens the future journey of biotechnology ("build to use"). Here, we discuss advances of various principles and technologies in the mainstream of the enabling technology of synthetic biology, including synthesis and assembly of a genome, DNA storage, gene editing, molecular evolution and de novo design of function proteins, cell and gene circuit engineering, cell-free synthetic biology, artificial intelligence (AI)-aided synthetic biology, as well as biofoundries. We also introduce the concept of quantitative synthetic biology, which is guiding synthetic biology towards increased accuracy and predictability or the real rational design. We conclude that synthetic biology will establish its disciplinary system with the iterative development of enabling technologies and the maturity of the core theory.
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Affiliation(s)
- Xian-En Zhang
- Faculty of Synthetic Biology, Shenzhen Institute of Advanced Technology, Shenzhen, 518055, China.
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Chenli Liu
- Faculty of Synthetic Biology, Shenzhen Institute of Advanced Technology, Shenzhen, 518055, China.
- Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China.
| | - Junbiao Dai
- Faculty of Synthetic Biology, Shenzhen Institute of Advanced Technology, Shenzhen, 518055, China.
- Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China.
| | - Yingjin Yuan
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.
| | - Caixia Gao
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Yan Feng
- State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, 200240, China.
| | - Bian Wu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Ping Wei
- Faculty of Synthetic Biology, Shenzhen Institute of Advanced Technology, Shenzhen, 518055, China.
- Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China.
| | - Chun You
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China.
| | - Xiaowo Wang
- Ministry of Education Key Laboratory of Bioinformatics; Center for Synthetic and Systems Biology; Bioinformatics Division, Beijing National Research Center for Information Science and Technology; Department of Automation, Tsinghua University, Beijing, 100084, China.
| | - Tong Si
- Faculty of Synthetic Biology, Shenzhen Institute of Advanced Technology, Shenzhen, 518055, China.
- Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China.
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8
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Stano P, Gentili PL, Damiano L, Magarini M. A Role for Bottom-Up Synthetic Cells in the Internet of Bio-Nano Things? Molecules 2023; 28:5564. [PMID: 37513436 PMCID: PMC10385758 DOI: 10.3390/molecules28145564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 06/29/2023] [Accepted: 07/18/2023] [Indexed: 07/30/2023] Open
Abstract
The potential role of bottom-up Synthetic Cells (SCs) in the Internet of Bio-Nano Things (IoBNT) is discussed. In particular, this perspective paper focuses on the growing interest in networks of biological and/or artificial objects at the micro- and nanoscale (cells and subcellular parts, microelectrodes, microvessels, etc.), whereby communication takes place in an unconventional manner, i.e., via chemical signaling. The resulting "molecular communication" (MC) scenario paves the way to the development of innovative technologies that have the potential to impact biotechnology, nanomedicine, and related fields. The scenario that relies on the interconnection of natural and artificial entities is briefly introduced, highlighting how Synthetic Biology (SB) plays a central role. SB allows the construction of various types of SCs that can be designed, tailored, and programmed according to specific predefined requirements. In particular, "bottom-up" SCs are briefly described by commenting on the principles of their design and fabrication and their features (in particular, the capacity to exchange chemicals with other SCs or with natural biological cells). Although bottom-up SCs still have low complexity and thus basic functionalities, here, we introduce their potential role in the IoBNT. This perspective paper aims to stimulate interest in and discussion on the presented topics. The article also includes commentaries on MC, semantic information, minimal cognition, wetware neuromorphic engineering, and chemical social robotics, with the specific potential they can bring to the IoBNT.
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Affiliation(s)
- Pasquale Stano
- Department of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento, 73100 Lecce, Italy
| | - Pier Luigi Gentili
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Luisa Damiano
- Department of Communication, Arts and Media, IULM University, 20143 Milan, Italy
| | - Maurizio Magarini
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, 20133 Milan, Italy
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9
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Bayer T, Hänel L, Husarcikova J, Kunzendorf A, Bornscheuer UT. In Vivo Detection of Low Molecular Weight Platform Chemicals and Environmental Contaminants by Genetically Encoded Biosensors. ACS OMEGA 2023; 8:23227-23239. [PMID: 37426270 PMCID: PMC10324065 DOI: 10.1021/acsomega.3c01741] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 06/08/2023] [Indexed: 07/11/2023]
Abstract
Genetically encoded biosensor systems operating in living cells are versatile, cheap, and transferable tools for the detection and quantification of a broad range of small molecules. This review presents state-of-the-art biosensor designs and assemblies, featuring transcription factor-, riboswitch-, and enzyme-coupled devices, highly engineered fluorescent probes, and emerging two-component systems. Importantly, (bioinformatic-assisted) strategies to resolve contextual issues, which cause biosensors to miss performance criteria in vivo, are highlighted. The optimized biosensing circuits can be used to monitor chemicals of low molecular mass (<200 g mol-1) and physicochemical properties that challenge conventional chromatographical methods with high sensitivity. Examples herein include but are not limited to formaldehyde, formate, and pyruvate as immediate products from (synthetic) pathways for the fixation of carbon dioxide (CO2), industrially important derivatives like small- and medium-chain fatty acids and biofuels, as well as environmental toxins such as heavy metals or reactive oxygen and nitrogen species. Lastly, this review showcases biosensors capable of assessing the biosynthesis of platform chemicals from renewable resources, the enzymatic degradation of plastic waste, or the bioadsorption of highly toxic chemicals from the environment. These applications offer new biosensor-based manufacturing, recycling, and remediation strategies to tackle current and future environmental and socioeconomic challenges including the wastage of fossil fuels, the emission of greenhouse gases like CO2, and the pollution imposed on ecosystems and human health.
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10
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Wagner L, Jules M, Borkowski O. What remains from living cells in bacterial lysate-based cell-free systems. Comput Struct Biotechnol J 2023; 21:3173-3182. [PMID: 37333859 PMCID: PMC10275740 DOI: 10.1016/j.csbj.2023.05.025] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 05/23/2023] [Accepted: 05/23/2023] [Indexed: 06/20/2023] Open
Abstract
Because they mimic cells while offering an accessible and controllable environment, lysate-based cell-free systems (CFS) have emerged as valuable biotechnology tools for synthetic biology. Historically used to uncover fundamental mechanisms of life, CFS are nowadays used for a multitude of purposes, including protein production and prototyping of synthetic circuits. Despite the conservation of fundamental functions in CFS like transcription and translation, RNAs and certain membrane-embedded or membrane-bound proteins of the host cell are lost when preparing the lysate. As a result, CFS largely lack some essential properties of living cells, such as the ability to adapt to changing conditions, to maintain homeostasis and spatial organization. Regardless of the application, shedding light on the black-box of the bacterial lysate is necessary to fully exploit the potential of CFS. Most measurements of the activity of synthetic circuits in CFS and in vivo show significant correlations because these only require processes that are preserved in CFS, like transcription and translation. However, prototyping circuits of higher complexity that require functions that are lost in CFS (cell adaptation, homeostasis, spatial organization) will not show such a good correlation with in vivo conditions. Both for prototyping circuits of higher complexity and for building artificial cells, the cell-free community has developed devices to reconstruct cellular functions. This mini-review compares bacterial CFS to living cells, focusing on functional and cellular process differences and the latest developments in restoring lost functions through complementation of the lysate or device engineering.
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11
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Vezeau GE, Gadila LR, Salis HM. Automated design of protein-binding riboswitches for sensing human biomarkers in a cell-free expression system. Nat Commun 2023; 14:2416. [PMID: 37105971 PMCID: PMC10140043 DOI: 10.1038/s41467-023-38098-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 04/13/2023] [Indexed: 04/29/2023] Open
Abstract
Cell-free genetically encoded biosensors have been developed to detect small molecules and nucleic acids, but they have yet to be reliably engineered to detect proteins. Here we develop an automated platform to convert protein-binding RNA aptamers into riboswitch sensors that operate within low-cost cell-free assays. We demonstrate the platform by engineering 35 protein-sensing riboswitches for human monomeric C-reactive protein, human interleukin-32γ, and phage MS2 coat protein. The riboswitch sensors regulate output expression levels by up to 16-fold with input protein concentrations within the human serum range. We identify two distinct mechanisms governing riboswitch-mediated regulation of translation rates and leverage computational analysis to refine the protein-binding aptamer regions, improving design accuracy. Overall, we expand the cell-free sensor toolbox and demonstrate how computational design is used to develop protein-sensing riboswitches with future applications as low-cost medical diagnostics.
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Affiliation(s)
- Grace E Vezeau
- Department of Agricultural and Biological Engineering, Pennsylvania State University, University Park, PA, 16802, USA
| | - Lipika R Gadila
- Department of Chemical Engineering, Pennsylvania State University, University Park, PA, 16802, USA
| | - Howard M Salis
- Department of Agricultural and Biological Engineering, Pennsylvania State University, University Park, PA, 16802, USA.
- Department of Chemical Engineering, Pennsylvania State University, University Park, PA, 16802, USA.
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA, 16802, USA.
- Huck Institute Bioinformatics and Genomics Graduate Program, Pennsylvania State University, University Park, PA, 16802, USA.
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12
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Hartmann D, Chowdhry R, Smith JM, Booth MJ. Orthogonal Light-Activated DNA for Patterned Biocomputing within Synthetic Cells. J Am Chem Soc 2023; 145:9471-9480. [PMID: 37125650 PMCID: PMC10161232 DOI: 10.1021/jacs.3c02350] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Cell-free gene expression is a vital research tool to study biological systems in defined minimal environments and has promising applications in biotechnology. Developing methods to control DNA templates for cell-free expression will be important for precise regulation of complex biological pathways and use with synthetic cells, particularly using remote, nondamaging stimuli such as visible light. Here, we have synthesized blue light-activatable DNA parts that tightly regulate cell-free RNA and protein synthesis. We found that this blue light-activated DNA could initiate expression orthogonally to our previously generated ultraviolet (UV) light-activated DNA, which we used to generate a dual-wavelength light-controlled cell-free AND-gate. By encapsulating these orthogonal light-activated DNAs into synthetic cells, we used two overlapping patterns of blue and UV light to provide precise spatiotemporal control over the logic gate. Our blue and UV orthogonal light-activated DNAs will open the door for precise control of cell-free systems in biology and medicine.
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Affiliation(s)
- Denis Hartmann
- Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K
| | - Razia Chowdhry
- Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K
| | - Jefferson M Smith
- Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K
| | - Michael J Booth
- Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K
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13
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Yue K, Li Y, Cao M, Shen L, Gu J, Kai L. Bottom-Up Synthetic Biology Using Cell-Free Protein Synthesis. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2023; 185:1-20. [PMID: 37526707 DOI: 10.1007/10_2023_232] [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: 08/02/2023]
Abstract
Technical advances in biotechnology have greatly accelerated the development of bottom-up synthetic biology. Unlike top-down approaches, bottom-up synthetic biology focuses on the construction of a minimal cell from scratch and the application of these principles to solve challenges. Cell-free protein synthesis (CFPS) systems provide minimal machinery for transcription and translation, from either a fractionated cell lysate or individual purified protein elements, thus speeding up the development of synthetic cell projects. In this review, we trace the history of the cell-free technique back to the first in vitro fermentation experiment using yeast cell lysate. Furthermore, we summarized progresses of individual cell mimicry modules, such as compartmentalization, gene expression regulation, energy regeneration and metabolism, growth and division, communication, and motility. Finally, current challenges and future perspectives on the field are outlined.
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Affiliation(s)
- Ke Yue
- School of Life Sciences, Jiangsu Normal University, Xuzhou, China
| | - Yingqiu Li
- School of Life Sciences, Jiangsu Normal University, Xuzhou, China
| | - Mengjiao Cao
- School of Life Sciences, Jiangsu Normal University, Xuzhou, China
| | - Lulu Shen
- School of Life Sciences, Jiangsu Normal University, Xuzhou, China
| | - Jingsheng Gu
- School of Life Sciences, Jiangsu Normal University, Xuzhou, China
| | - Lei Kai
- School of Life Sciences, Jiangsu Normal University, Xuzhou, China.
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14
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Patterson AT, Styczynski MP. Rapid and Finely-Tuned Expression for Deployable Sensing Applications. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2023; 186:141-161. [PMID: 37316621 DOI: 10.1007/10_2023_223] [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: 06/16/2023]
Abstract
Organisms from across the tree of life have evolved highly efficient mechanisms for sensing molecules of interest using biomolecular machinery that can in turn be quite valuable for the development of biosensors. However, purification of such machinery for use in in vitro biosensors is costly, while the use of whole cells as in vivo biosensors often leads to long sensor response times and unacceptable sensitivity to the chemical makeup of the sample. Cell-free expression systems overcome these weaknesses by removing the requirements associated with maintaining living sensor cells, allowing for increased function in toxic environments and rapid sensor readout at a production cost that is often more reasonable than purification. Here, we focus on the challenge of implementing cell-free protein expression systems that meet the stringent criteria required for them to serve as the basis for field-deployable biosensors. Fine-tuning expression to meet these requirements can be achieved through careful selection of the sensing and output elements, as well as through optimization of reaction conditions via tuning of DNA/RNA concentrations, lysate preparation methods, and buffer conditions. Through careful sensor engineering, cell-free systems can continue to be successfully used for the production of tightly regulated, rapidly expressing genetic circuits for biosensors.
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Affiliation(s)
- Alexandra T Patterson
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Mark P Styczynski
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, USA.
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15
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Mathur D, Thakur M, Díaz SA, Susumu K, Stewart MH, Oh E, Walper SA, Medintz IL. Hybrid Nucleic Acid-Quantum Dot Assemblies as Multiplexed Reporter Platforms for Cell-Free Transcription Translation-Based Biosensors. ACS Synth Biol 2022; 11:4089-4102. [PMID: 36441919 PMCID: PMC9829448 DOI: 10.1021/acssynbio.2c00394] [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: 11/29/2022]
Abstract
Cell-free synthetic biology has emerged as a valuable tool for the development of rapid, portable biosensors that can be readily transported in the freeze-dried form to the point of need eliminating cold chain requirements. One of the challenges associated with cell-free sensors is the ability to simultaneously detect multiple analytes within a single reaction due to the availability of a limited set of fluorescent and colorimetric reporters. To potentially provide multiplexing capabilities to cell-free biosensors, we designed a modular semiconductor quantum dot (QD)-based reporter platform that is plugged in downstream of the transcription-translation functionality in the cell-free reaction and which converts enzymatic activity in the reaction into distinct optical signals. We demonstrate proof of concept by converting restriction enzyme activity, utilized as our prototypical sensing output, into optical changes across several distinct spectral output channels that all use a common excitation wavelength. These hybrid Förster resonance energy transfer (FRET)-based QD peptide PNA-DNA-Dye reporters (QD-PDDs) are completely self-assembled and consist of differentially emissive QD donors paired to a dye-acceptor displayed on a unique DNA encoding a given enzyme's cleavage site. Three QD-based PDDs, independently activated by the enzymes BamHI, EcoRI, and NcoI, were prototyped in mixed enzyme assays where all three demonstrated the ability to convert enzymatic activity into fluorescent output. Simultaneous monitoring of each of the three paired QD-donor dye-acceptor spectral channels in cell-free biosensing reactions supplemented with added linear genes encoding each enzyme confirmed robust multiplexing capabilities for at least two enzymes when co-expressed. The modular QD-PDDs are easily adapted to respond to other restriction enzymes or even proteases if desired.
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Affiliation(s)
| | | | - Sebastián A. Díaz
- Center for Bio/Molecular Science and Engineering Code 6900, U.S. Naval Research Laboratory, Washington 20375, United States
| | - Kimihiro Susumu
- Jacobs Corporation, Hanover, Maryland 21076, United States; Optical Sciences Division Code 5600, U.S. Naval Research Laboratory, Washington 20375, United States
| | - Michael H. Stewart
- Optical Sciences Division Code 5600, U.S. Naval Research Laboratory, Washington 20375, United States
| | - Eunkeu Oh
- Optical Sciences Division Code 5600, U.S. Naval Research Laboratory, Washington 20375, United States
| | - Scott A. Walper
- Center for Bio/Molecular Science and Engineering Code 6900, U.S. Naval Research Laboratory, Washington 20375, United States
| | - Igor L. Medintz
- Center for Bio/Molecular Science and Engineering Code 6900, U.S. Naval Research Laboratory, Washington 20375, United States
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16
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Senda N, Enomoto T, Kihara K, Yamashiro N, Takagi N, Kiga D, Nishida H. Development of an expression-tunable multiple protein synthesis system in cell-free reactions using T7-promoter-variant series. SYNTHETIC BIOLOGY (OXFORD, ENGLAND) 2022; 7:ysac029. [PMID: 36591595 PMCID: PMC9791696 DOI: 10.1093/synbio/ysac029] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 11/01/2022] [Accepted: 11/24/2022] [Indexed: 11/27/2022]
Abstract
New materials with a low environmental load are expected to be generated through synthetic biology. To widely utilize this technology, it is important to create cells with designed biological functions and to control the expression of multiple enzymes. In this study, we constructed a cell-free evaluation system for multiple protein expression, in which synthesis is controlled by T7 promoter variants. The expression of a single protein using the T7 promoter variants showed the expected variety in expression levels, as previously reported. We then examined the expression levels of multiple proteins that are simultaneously produced in a single well to determine whether they can be predicted from the promoter activity values, which were defined from the isolated protein expression levels. When the sum of messenger ribonucleic acid (mRNA) species is small, the experimental protein expression levels can be predicted from the promoter activities (graphical abstract (a)) due to low competition for ribosomes. In other words, by using combinations of T7 promoter variants, we successfully developed a cell-free multiple protein synthesis system with tunable expression. In the presence of large amounts of mRNA, competition for ribosomes becomes an issue (graphical abstract (b)). Accordingly, the translation level of each protein cannot be directly predicted from the promoter activities and is biased by the strength of the ribosome binding site (RBS); a weaker RBS is more affected by competition. Our study provides information regarding the regulated expression of multiple enzymes in synthetic biology.
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Affiliation(s)
| | - Toshihiko Enomoto
- Department of Electrical Engineering and Bioscience, Waseda University, Shinjuku, Tokyo, Japan
| | - Kenta Kihara
- Department of Electrical Engineering and Bioscience, Waseda University, Shinjuku, Tokyo, Japan
| | - Naoki Yamashiro
- Department of Electrical Engineering and Bioscience, Waseda University, Shinjuku, Tokyo, Japan
| | - Naosato Takagi
- Department of Electrical Engineering and Bioscience, Waseda University, Shinjuku, Tokyo, Japan
| | - Daisuke Kiga
- Department of Electrical Engineering and Bioscience, Waseda University, Shinjuku, Tokyo, Japan
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17
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Bi H, Zhao C, Zhang Y, Zhang X, Xue B, Li C, Wang S, Yang X, Li C, Qiu Z, Wang J, Shen Z. IVT cell-free biosensors for tetracycline and macrolide detection based on allosteric transcription factors (aTFs). ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2022; 14:4545-4554. [PMID: 36314439 DOI: 10.1039/d2ay01316a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
In recent years, the issue of food safety has received a lot of attention. The Food and Drug Administration (FDA) prescribes the antibiotic's maximum residue limit (MRL) in food production. The standard detection methods of antibiotics are liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) and high-performance liquid chromatography (HPLC), with complex operations and precision instruments. In this study, allosteric transcription factor (aTF)-based in vitro transcription (IVT) cell-free biosensors were developed for tetracyclines and macrolides with nucleic acid sequence-based amplification (NASBA). Characterization of binding and dissociation processes between aTF and DNA was carried out by BIAcore assay and electrophoretic mobility shift assay (EMSA). BIAcore was innovatively used to directly observe the real-time process of binding and dissociation of aTF with DNA. The biosensors produce more fluorescence RNA when target antibiotics are added to the three-way junction dimeric Broccoli (3WJdB). Four tetracyclines and two macrolides were quantified in the 0.5-15 μM range, while erythromycin and clarithromycin were detected over a range of 0.1-15 μM. NASBA, commonly used for viral detection, was used to amplify 3WJdB RNA generated by IVT, which greatly increased the LOD for tetracyclines and macrolides to 0.01 μM. The use of biosensors in milk samples demonstrated their on-site detection performance. Overall, our proposed biosensors are simple, rapid, selective, and sensitive, with the potential for field application.
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Affiliation(s)
- Huaixiu Bi
- College of Food Science and Technology, Shanghai Ocean University, Shanghai 201306, China.
- Department of Hygienic Toxicology and Environmental Hygiene, Tianjin Institute of Environmental and Operational Medicine, Tianjin 300050, China.
| | - Chen Zhao
- Department of Hygienic Toxicology and Environmental Hygiene, Tianjin Institute of Environmental and Operational Medicine, Tianjin 300050, China.
| | - Yongkang Zhang
- Department of Hygienic Toxicology and Environmental Hygiene, Tianjin Institute of Environmental and Operational Medicine, Tianjin 300050, China.
| | - Xi Zhang
- Department of Hygienic Toxicology and Environmental Hygiene, Tianjin Institute of Environmental and Operational Medicine, Tianjin 300050, China.
| | - Bin Xue
- Department of Hygienic Toxicology and Environmental Hygiene, Tianjin Institute of Environmental and Operational Medicine, Tianjin 300050, China.
| | - Chenyu Li
- Department of Hygienic Toxicology and Environmental Hygiene, Tianjin Institute of Environmental and Operational Medicine, Tianjin 300050, China.
| | - Shang Wang
- Department of Hygienic Toxicology and Environmental Hygiene, Tianjin Institute of Environmental and Operational Medicine, Tianjin 300050, China.
| | - Xiaobo Yang
- Department of Hygienic Toxicology and Environmental Hygiene, Tianjin Institute of Environmental and Operational Medicine, Tianjin 300050, China.
| | - Chao Li
- Department of Hygienic Toxicology and Environmental Hygiene, Tianjin Institute of Environmental and Operational Medicine, Tianjin 300050, China.
| | - Zhigang Qiu
- Department of Hygienic Toxicology and Environmental Hygiene, Tianjin Institute of Environmental and Operational Medicine, Tianjin 300050, China.
| | - Jingfeng Wang
- Department of Hygienic Toxicology and Environmental Hygiene, Tianjin Institute of Environmental and Operational Medicine, Tianjin 300050, China.
| | - Zhiqiang Shen
- College of Food Science and Technology, Shanghai Ocean University, Shanghai 201306, China.
- Department of Hygienic Toxicology and Environmental Hygiene, Tianjin Institute of Environmental and Operational Medicine, Tianjin 300050, China.
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18
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Csibra E, Stan GB. Absolute protein quantification using fluorescence measurements with FPCountR. Nat Commun 2022; 13:6600. [PMID: 36329019 PMCID: PMC9633595 DOI: 10.1038/s41467-022-34232-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 10/19/2022] [Indexed: 11/06/2022] Open
Abstract
This paper presents a generalisable method for the calibration of fluorescence readings on microplate readers, in order to convert arbitrary fluorescence units into absolute units. FPCountR relies on the generation of bespoke fluorescent protein (FP) calibrants, assays to determine protein concentration and activity, and a corresponding analytical workflow. We systematically characterise the assay protocols for accuracy, sensitivity and simplicity, and describe an 'ECmax' assay that outperforms the others and even enables accurate calibration without requiring the purification of FPs. To obtain cellular protein concentrations, we consider methods for the conversion of optical density to either cell counts or alternatively to cell volumes, as well as examining how cells can interfere with protein counting via fluorescence quenching, which we quantify and correct for the first time. Calibration across different instruments, disparate filter sets and mismatched gains is demonstrated to yield equivalent results. It also reveals that mCherry absorption at 600 nm does not confound cell density measurements unless expressed to over 100,000 proteins per cell. FPCountR is presented as pair of open access tools (protocol and R package) to enable the community to use this method, and ultimately to facilitate the quantitative characterisation of synthetic microbial circuits.
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Affiliation(s)
- Eszter Csibra
- grid.7445.20000 0001 2113 8111Department of Bioengineering, Imperial College Centre for Synthetic Biology (IC-CSynB), Imperial College London, London, SW7 2AY UK
| | - Guy-Bart Stan
- grid.7445.20000 0001 2113 8111Department of Bioengineering, Imperial College Centre for Synthetic Biology (IC-CSynB), Imperial College London, London, SW7 2AY UK
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19
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Liyanagedera SBW, Williams J, Wheatley JP, Biketova AY, Hasan M, Sagona AP, Purdy KJ, Puxty RJ, Feher T, Kulkarni V. SpyPhage: A Cell-Free TXTL Platform for Rapid Engineering of Targeted Phage Therapies. ACS Synth Biol 2022; 11:3330-3342. [PMID: 36194543 DOI: 10.1021/acssynbio.2c00244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The past decade has seen the emergence of multidrug resistant pathogens as a leading cause of death worldwide, reigniting interest in the field of phage therapy. Modern advances in the genetic engineering of bacteriophages have enabled several useful results including host range alterations, constitutive lytic growth, and control over phage replication. However, the slow licensing process of genetically modified organisms clearly inhibits the rapid therapeutic application of novel engineered variants necessary to fight mutant pathogens that emerge throughout the course of a pandemic. As a solution to this problem, we propose the SpyPhage system where a "scaffold" bacteriophage is engineered to incorporate a SpyTag moiety on its capsid head to enable rapid postsynthetic modification of their surfaces with SpyCatcher-fused therapeutic proteins. As a proof of concept, through CRISPR/Cas-facilitated phage engineering and whole genome assembly, we targeted a SpyTag capsid fusion to K1F, a phage targeting the pathogenic strain Escherichia coli K1. We demonstrate for the first time the cell-free assembly and decoration of the phage surface with two alternative fusion proteins, SpyCatcher-mCherry-EGF and SpyCatcher-mCherry-Rck, both of which facilitate the endocytotic uptake of the phages by a urinary bladder epithelial cell line. Overall, our work presents a cell-free phage production pipeline for the generation of multiple phenotypically distinct phages with a single underlying "scaffold" genotype. These phages could become the basis of next-generation phage therapies where the knowledge-based engineering of numerous phage variants would be quickly achievable without the use of live bacteria or the need to repeatedly license novel genetic alterations.
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Affiliation(s)
| | - Joshua Williams
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Joseph P Wheatley
- School of Engineering, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Alona Yu Biketova
- Institute of Biochemistry, Eötvös Lóránd Research Network, Szeged Biological Research Centre, Szeged 6726, Hungary.,Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond TW9 3AE, United Kingdom
| | - Muhammad Hasan
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Antonia P Sagona
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Kevin J Purdy
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Richard J Puxty
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Tamas Feher
- Institute of Biochemistry, Eötvös Lóránd Research Network, Szeged Biological Research Centre, Szeged 6726, Hungary
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20
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Zhang Y, Zhao C, Bi H, Zhang X, Xue B, Li C, Wang S, Yang X, Qiu Z, Wang J, Shen Z. A cell-free paper-based biosensor dependent on allosteric transcription factors (aTFs) for on-site detection of harmful metals Hg 2+ and Pb 2+ in water. JOURNAL OF HAZARDOUS MATERIALS 2022; 438:129499. [PMID: 35816794 DOI: 10.1016/j.jhazmat.2022.129499] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 06/16/2022] [Accepted: 06/27/2022] [Indexed: 06/15/2023]
Abstract
Water quality monitoring requires a reliable and practical on-site detection method for heavy metal ions. Combining an in vitro transcription (IVT) technology with allosteric transcription factors (aTFs), we developed a cell-free paper-based biosensor for on-site detection of Hg2+ and Pb2+ in water. Suitable aTFs screened using surface plasmon resonance (SPR) were employed for building biosensors. ATFs could disassociate from DNA due to their specific affinity to metal ions, and fluorescent RNA was transcribed as a signal. The developed biosensor could quantitatively detect Hg2+ in a linear dynamic range of 0.5-500 nM and Pb2+ in a 1-250 nM range in a 1 h period. The LOD of the biosensor was 0.5 nM for Hg2+ and 0.1 nM for Pb2+. The recoveries ranged from 91.09% to 123.24% for actual water samples detection. Furthermore, freeze-drying was used to create a paper-based biosensor that could detect Hg2+ and Pb2+ simultaneously on-site. This research presents a useful technique for various heavy metal ion detections.
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Affiliation(s)
- Yongkang Zhang
- Tianjin Institute of Environmental and Operational Medicine, Tianjin 300050, China
| | - Chen Zhao
- Tianjin Institute of Environmental and Operational Medicine, Tianjin 300050, China; Key Laboratory of Risk Assessment and Control for Environment & Food Safety, Tianjin 300050, China
| | - Huaixiu Bi
- Tianjin Institute of Environmental and Operational Medicine, Tianjin 300050, China; College of Food Science and Technology, Shanghai Ocean University, Shanghai 201306, China
| | - Xi Zhang
- Tianjin Institute of Environmental and Operational Medicine, Tianjin 300050, China
| | - Bin Xue
- Tianjin Institute of Environmental and Operational Medicine, Tianjin 300050, China
| | - Chenyu Li
- Tianjin Institute of Environmental and Operational Medicine, Tianjin 300050, China
| | - Shang Wang
- Key Laboratory of Risk Assessment and Control for Environment & Food Safety, Tianjin 300050, China
| | - Xiaobo Yang
- Key Laboratory of Risk Assessment and Control for Environment & Food Safety, Tianjin 300050, China
| | - Zhigang Qiu
- Key Laboratory of Risk Assessment and Control for Environment & Food Safety, Tianjin 300050, China
| | - Jingfeng Wang
- Key Laboratory of Risk Assessment and Control for Environment & Food Safety, Tianjin 300050, China.
| | - Zhiqiang Shen
- Tianjin Institute of Environmental and Operational Medicine, Tianjin 300050, China.
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21
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Rhea KA, McDonald ND, Cole SD, Noireaux V, Lux MW, Buckley PE. Variability in cell-free expression reactions can impact qualitative genetic circuit characterization. Synth Biol (Oxf) 2022; 7:ysac011. [PMID: 35966404 PMCID: PMC9365049 DOI: 10.1093/synbio/ysac011] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 06/24/2022] [Accepted: 08/01/2022] [Indexed: 09/21/2023] Open
Abstract
Cell-free expression systems provide a suite of tools that are used in applications from sensing to biomanufacturing. One of these applications is genetic circuit prototyping, where the lack of cloning is required and a high degree of control over reaction components and conditions enables rapid testing of design candidates. Many studies have shown utility in the approach for characterizing genetic regulation elements, simple genetic circuit motifs, protein variants or metabolic pathways. However, variability in cell-free expression systems is a known challenge, whether between individuals, laboratories, instruments, or batches of materials. While the issue of variability has begun to be quantified and explored, little effort has been put into understanding the implications of this variability. For genetic circuit prototyping, it is unclear when and how significantly variability in reaction activity will impact qualitative assessments of genetic components, e.g. relative activity between promoters. Here, we explore this question by assessing DNA titrations of seven genetic circuits of increasing complexity using reaction conditions that ostensibly follow the same protocol but vary by person, instrument and material batch. Although the raw activities vary widely between the conditions, by normalizing within each circuit across conditions, reasonably consistent qualitative performance emerges for the simpler circuits. For the most complex case involving expression of three proteins, we observe a departure from this qualitative consistency, offering a provisional cautionary line where normal variability may disrupt reliable reuse of prototyping results. Our results also suggest that a previously described closed loop controller circuit may help to mitigate such variability, encouraging further work to design systems that are robust to variability. Graphical Abstract.
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Affiliation(s)
- Katherine A Rhea
- US Army Combat Capabilities Development Command Chemical Biological Center, Aberdeen Proving Ground, MD, USA
| | - Nathan D McDonald
- US Army Combat Capabilities Development Command Chemical Biological Center, Aberdeen Proving Ground, MD, USA
| | - Stephanie D Cole
- US Army Combat Capabilities Development Command Chemical Biological Center, Aberdeen Proving Ground, MD, USA
| | - Vincent Noireaux
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, USA
| | - Matthew W Lux
- US Army Combat Capabilities Development Command Chemical Biological Center, Aberdeen Proving Ground, MD, USA
| | - Patricia E Buckley
- US Army Combat Capabilities Development Command Chemical Biological Center, Aberdeen Proving Ground, MD, USA
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22
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Copeland CE, Kim J, Copeland PL, Heitmeier CJ, Kwon YC. Characterizing a New Fluorescent Protein for a Low Limit of Detection Sensing in the Cell-Free System. ACS Synth Biol 2022; 11:2800-2810. [PMID: 35850511 PMCID: PMC9396652 DOI: 10.1021/acssynbio.2c00180] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cell-free protein synthesis-based biosensors have been developed as highly accurate, low-cost biosensors. However, since most biomarkers exist at low concentrations in various types of biopsies, the biosensor's dynamic range must be increased in the system to achieve low limits of detection necessary while deciphering from higher background signals. Many attempts to increase the dynamic range have relied on amplifying the input signal from the analyte, which can lead to complications of false positives. In this study, we aimed to increase the protein synthesis capability of the cell-free protein synthesis system and the output signal of the reporter protein to achieve a lower limit of detection. We utilized a new fluorescent protein, mNeonGreen, which produces a higher output than those commonly used in cell-free biosensors. Optimizations of DNA sequence and the subsequent cell-free protein synthesis reaction conditions allowed characterizing protein expression variability by given DNA template types, reaction environment, and storage additives that cause the greatest time constraint on designing the cell-free biosensor. Finally, we characterized the fluorescence kinetics of mNeonGreen compared to the commonly used reporter protein, superfolder green fluorescent protein. We expect that this finely tuned cell-free protein synthesis platform with the new reporter protein can be used with sophisticated synthetic gene circuitry networks to increase the dynamic range of a cell-free biosensor to reach lower detection limits and reduce the false-positive proportion.
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Affiliation(s)
- Caroline E Copeland
- Department of Biological and Agricultural Engineering, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Jeehye Kim
- Department of Biological and Agricultural Engineering, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Pearce L Copeland
- Department of Biological and Agricultural Engineering, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Chloe J Heitmeier
- Department of Biological and Agricultural Engineering, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Yong-Chan Kwon
- Department of Biological and Agricultural Engineering, Louisiana State University, Baton Rouge, Louisiana 70803, United States.,Louisiana State University Agricultural Center, Baton Rouge, Louisiana 70803, United States
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23
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Harbaugh SV, Silverman AD, Chushak YG, Zimlich K, Wolfe M, Thavarajah W, Jewett MC, Lucks JB, Chávez JL. Engineering a Synthetic Dopamine-Responsive Riboswitch for In Vitro Biosensing. ACS Synth Biol 2022; 11:2275-2283. [PMID: 35775197 DOI: 10.1021/acssynbio.1c00560] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The detection of chemicals using natural allosteric transcription factors is a powerful strategy for point-of-use molecular sensing, particularly using fieldable cell-free gene expression (CFE) systems. However, the reliance of detection schemes on characterized protein-based sensors limits the number of measurable analytes. One alternative solution to this issue is to develop new sensors by generating RNA aptamers against the target analyte and then incorporating them directly into a riboswitch scaffold for ligand-inducible genetic control of a reporter protein. However, this strategy has not generated more than a handful of successful portable cell-free molecular sensors. To address this gap, here we convert dopamine-binding aptamers into functional dopamine-sensing riboswitches that regulate gene expression in a freeze-dried CFE reaction. We then develop an assay for direct detection and semi-quantification of dopamine in human urine. We anticipate that this work will be broadly applicable for converting many in vitro-generated RNA aptamers into fieldable molecular diagnostics.
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Affiliation(s)
- Svetlana V Harbaugh
- 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States
| | - Adam D Silverman
- Sherlock Biosciences, Boston, Massachusetts 02135, United States
| | - Yaroslav G Chushak
- 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States.,Henry M. Jackson Foundation, Dayton, Ohio 45433, United States
| | - Kathryn Zimlich
- 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States.,Henry M. Jackson Foundation, Dayton, Ohio 45433, United States
| | - Monica Wolfe
- 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States.,UES, Inc., Dayton, Ohio 45432, United States
| | - Walter Thavarajah
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States.,Center for Synthetic Biology, Northwestern University, Evanston, Illinois 60208, United States
| | - Michael C Jewett
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States.,Center for Synthetic Biology, Northwestern University, Evanston, Illinois 60208, United States.,Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, Illinois 60208, United States.,International Institute of Nanotechnology, Northwestern University, Evanston, Illinois 60208, United States
| | - Julius B Lucks
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States.,Center for Synthetic Biology, Northwestern University, Evanston, Illinois 60208, United States.,Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, Illinois 60208, United States.,International Institute of Nanotechnology, Northwestern University, Evanston, Illinois 60208, United States
| | - Jorge L Chávez
- 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States
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24
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A microfluidic optimal experimental design platform for forward design of cell-free genetic networks. Nat Commun 2022; 13:3626. [PMID: 35750678 PMCID: PMC9232554 DOI: 10.1038/s41467-022-31306-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 06/14/2022] [Indexed: 12/20/2022] Open
Abstract
Cell-free protein synthesis has been widely used as a “breadboard” for design of synthetic genetic networks. However, due to a severe lack of modularity, forward engineering of genetic networks remains challenging. Here, we demonstrate how a combination of optimal experimental design and microfluidics allows us to devise dynamic cell-free gene expression experiments providing maximum information content for subsequent non-linear model identification. Importantly, we reveal that applying this methodology to a library of genetic circuits, that share common elements, further increases the information content of the data resulting in higher accuracy of model parameters. To show modularity of model parameters, we design a pulse decoder and bistable switch, and predict their behaviour both qualitatively and quantitatively. Finally, we update the parameter database and indicate that network topology affects parameter estimation accuracy. Utilizing our methodology provides us with more accurate model parameters, a necessity for forward engineering of complex genetic networks. Characterization of cell-free genetic networks is inherently difficult. Here the authors use optimal experimental design and microfluidics to improve characterization, demonstrating modularity and predictability of parts in applied test cases.
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25
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van der Linden AJ, Pieters PA, Bartelds MW, Nathalia BL, Yin P, Huck WTS, Kim J, de Greef TFA. DNA Input Classification by a Riboregulator-Based Cell-Free Perceptron. ACS Synth Biol 2022; 11:1510-1520. [PMID: 35381174 PMCID: PMC9016768 DOI: 10.1021/acssynbio.1c00596] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The ability to recognize molecular patterns is essential for the continued survival of biological organisms, allowing them to sense and respond to their immediate environment. The design of synthetic gene-based classifiers has been explored previously; however, prior strategies have focused primarily on DNA strand-displacement reactions. Here, we present a synthetic in vitro transcription and translation (TXTL)-based perceptron consisting of a weighted sum operation (WSO) coupled to a downstream thresholding function. We demonstrate the application of toehold switch riboregulators to construct a TXTL-based WSO circuit that converts DNA inputs into a GFP output, the concentration of which correlates to the input pattern and the corresponding weights. We exploit the modular nature of the WSO circuit by changing the output protein to the Escherichia coli σ28-factor, facilitating the coupling of the WSO output to a downstream reporter network. The subsequent introduction of a σ28 inhibitor enabled thresholding of the WSO output such that the expression of the downstream reporter protein occurs only when the produced σ28 exceeds this threshold. In this manner, we demonstrate a genetically implemented perceptron capable of binary classification, i.e., the expression of a single output protein only when the desired minimum number of inputs is exceeded.
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Affiliation(s)
- Ardjan J. van der Linden
- Laboratory of Chemical Biology and Institute for Complex Molecular Systems, Department of Biomedical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
- Computational Biology Group, Department of Biomedical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
| | - Pascal A. Pieters
- Laboratory of Chemical Biology and Institute for Complex Molecular Systems, Department of Biomedical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
- Computational Biology Group, Department of Biomedical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
| | - Mart W. Bartelds
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, The Netherlands
| | - Bryan L. Nathalia
- Computational Biology Group, Department of Biomedical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
| | - Peng Yin
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts 02115, United States
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Wilhelm T. S. Huck
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, The Netherlands
| | - Jongmin Kim
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, Republic of Korea
| | - Tom F. A. de Greef
- Laboratory of Chemical Biology and Institute for Complex Molecular Systems, Department of Biomedical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
- Computational Biology Group, Department of Biomedical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, The Netherlands
- Center for Living Technologies, Eindhoven-Wageningen-Utrecht Alliance, 3584 CB Utrecht, The Netherlands
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26
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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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27
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Beabout K, Bernhards CB, Thakur M, Turner KB, Cole SD, Walper SA, Chávez JL, Lux MW. Optimization of Heavy Metal Sensors Based on Transcription Factors and Cell-Free Expression Systems. ACS Synth Biol 2021; 10:3040-3054. [PMID: 34723503 DOI: 10.1021/acssynbio.1c00331] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Many bacterial mechanisms for highly specific and sensitive detection of heavy metals and other hazards have been reengineered to serve as sensors. In some cases, these sensors have been implemented in cell-free expression systems, enabling easier design optimization and deployment in low-resource settings through lyophilization. Here, we apply the advantages of cell-free expression systems to optimize sensors based on three separate bacterial response mechanisms for arsenic, cadmium, and mercury. We achieved detection limits below the World Health Organization-recommended levels for arsenic and mercury and below the short-term US Military Exposure Guideline levels for all three. The optimization of each sensor was approached differently, leading to observations useful for the development of future sensors: (1) there can be a strong dependence of specificity on the particular cell-free expression system used, (2) tuning of relative concentrations of the sensing and reporter elements improves sensitivity, and (3) sensor performance can vary significantly with linear vs plasmid DNA. In addition, we show that simply combining DNA for the three sensors into a single reaction enables detection of each target heavy metal without any further optimization. This combined approach could lead to sensors that detect a range of hazards at once, such as a panel of water contaminants or all known variants of a target virus. For low-resource settings, such "all-hazard" sensors in a cheap, easy-to-use format could have high utility.
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Affiliation(s)
- Kathryn Beabout
- UES, Inc., Dayton, Ohio 45432, United States
- Air Force Research Laboratory, 711th Human Performance Wing, Wright-Patterson Air Force Base, Dayton, Ohio 45433, United States
| | - Casey B. Bernhards
- Excet, Inc., 6225 Brandon Avenue #360, Springfield, Virginia 22150, United States
- U.S. Army Combat Capabilities Development Command Chemical Biological Center, 8198 Blackhawk Road, Aberdeen Proving Ground, Maryland 21010, United States
| | - Meghna Thakur
- Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375, United States
- College of Science, George Mason University, Fairfax, Virginia 22030, United States
| | - Kendrick B. Turner
- Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375, United States
| | - Stephanie D. Cole
- U.S. Army Combat Capabilities Development Command Chemical Biological Center, 8198 Blackhawk Road, Aberdeen Proving Ground, Maryland 21010, United States
| | - Scott A. Walper
- Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375, United States
| | - Jorge L. Chávez
- Air Force Research Laboratory, 711th Human Performance Wing, Wright-Patterson Air Force Base, Dayton, Ohio 45433, United States
| | - Matthew W. Lux
- U.S. Army Combat Capabilities Development Command Chemical Biological Center, 8198 Blackhawk Road, Aberdeen Proving Ground, Maryland 21010, United States
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28
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29
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Gyorgy A. Context-Dependent Stability and Robustness of Genetic Toggle Switches with Leaky Promoters. Life (Basel) 2021; 11:life11111150. [PMID: 34833026 PMCID: PMC8624834 DOI: 10.3390/life11111150] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 10/21/2021] [Accepted: 10/26/2021] [Indexed: 01/22/2023] Open
Abstract
Multistable switches are ubiquitous building blocks in both systems and synthetic biology. Given their central role, it is thus imperative to understand how their fundamental properties depend not only on the tunable biophysical properties of the switches themselves, but also on their genetic context. To this end, we reveal in this article how these factors shape the essential characteristics of toggle switches implemented using leaky promoters such as their stability and robustness to noise, both at single-cell and population levels. In particular, our results expose the roles that competition for scarce transcriptional and translational resources, promoter leakiness, and cell-to-cell heterogeneity collectively play. For instance, the interplay between protein expression from leaky promoters and the associated cost of relying on shared cellular resources can give rise to tristable dynamics even in the absence of positive feedback. Similarly, we demonstrate that while promoter leakiness always acts against multistability, resource competition can be leveraged to counteract this undesirable phenomenon. Underpinned by a mechanistic model, our results thus enable the context-aware rational design of multistable genetic switches that are directly translatable to experimental considerations, and can be further leveraged during the synthesis of large-scale genetic systems using computer-aided biodesign automation platforms.
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Affiliation(s)
- Andras Gyorgy
- Division of Engineering, New York University Abu Dhabi, Abu Dhabi P.O. Box 129188, United Arab Emirates
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30
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Vezeau GE, Salis HM. Tuning Cell-Free Composition Controls the Time Delay, Dynamics, and Productivity of TX-TL Expression. ACS Synth Biol 2021; 10:2508-2519. [PMID: 34498860 DOI: 10.1021/acssynbio.1c00136] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The composition of cell-free expression systems (TX-TL) is adjusted by adding macromolecular crowding agents and salts. However, the effects of these cosolutes on the dynamics of individual gene expression processes have not been quantified. Here, we carry out kinetic mRNA and protein level measurements on libraries of genetic constructs using the common cosolutes PEG-8000, Ficoll-400, and magnesium glutamate. By combining these measurements with biophysical modeling, we show that cosolutes have differing effects on transcription initiation, translation initiation, and translation elongation rates with trade-offs between time delays, expression tunability, and maximum expression productivity. We also confirm that biophysical models can predict translation initiation rates in TX-TL using Escherichia coli lysate. We discuss how cosolute composition can be tuned to maximize performance across different cell-free applications, including biosensing, diagnostics, and biomanufacturing.
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Affiliation(s)
- Grace E. Vezeau
- Department of Biological Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Howard M. Salis
- Department of Biological Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States
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31
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Arce A, Guzman Chavez F, Gandini C, Puig J, Matute T, Haseloff J, Dalchau N, Molloy J, Pardee K, Federici F. Decentralizing Cell-Free RNA Sensing With the Use of Low-Cost Cell Extracts. Front Bioeng Biotechnol 2021; 9:727584. [PMID: 34497801 PMCID: PMC8419261 DOI: 10.3389/fbioe.2021.727584] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 08/06/2021] [Indexed: 11/13/2022] Open
Abstract
Cell-free gene expression systems have emerged as a promising platform for field-deployed biosensing and diagnostics. When combined with programmable toehold switch-based RNA sensors, these systems can be used to detect arbitrary RNAs and freeze-dried for room temperature transport to the point-of-need. These sensors, however, have been mainly implemented using reconstituted PURE cell-free protein expression systems that are difficult to source in the Global South due to their high commercial cost and cold-chain shipping requirements. Based on preliminary demonstrations of toehold sensors working on lysates, we describe the fast prototyping of RNA toehold switch-based sensors that can be produced locally and reduce the cost of sensors by two orders of magnitude. We demonstrate that these in-house cell lysates provide sensor performance comparable to commercial PURE cell-free systems. We further optimize these lysates with a CRISPRi strategy to enhance the stability of linear DNAs by knocking-down genes responsible for linear DNA degradation. This enables the direct use of PCR products for fast screening of new designs. As a proof-of-concept, we develop novel toehold sensors for the plant pathogen Potato Virus Y (PVY), which dramatically reduces the yield of this important staple crop. The local implementation of low-cost cell-free toehold sensors could enable biosensing capacity at the regional level and lead to more decentralized models for global surveillance of infectious disease.
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Affiliation(s)
- Anibal Arce
- ANID – Millennium Science Initiative Program – Millennium Institute for Integrative Biology (iBio), Santiago, Chile
- Schools of Engineering, Institute for Biological and Medical Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
- Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Santiago, Chile
| | | | - Chiara Gandini
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, United Kingdom
| | - Juan Puig
- ANID – Millennium Science Initiative Program – Millennium Institute for Integrative Biology (iBio), Santiago, Chile
- Schools of Engineering, Institute for Biological and Medical Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Tamara Matute
- ANID – Millennium Science Initiative Program – Millennium Institute for Integrative Biology (iBio), Santiago, Chile
- Schools of Engineering, Institute for Biological and Medical Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Jim Haseloff
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | | | - Jenny Molloy
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, United Kingdom
| | - Keith Pardee
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON, Canada
| | - Fernán Federici
- ANID – Millennium Science Initiative Program – Millennium Institute for Integrative Biology (iBio), Santiago, Chile
- Schools of Engineering, Institute for Biological and Medical Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
- Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Santiago, Chile
- FONDAP Center for Genome Regulation, Santiago, Chile
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32
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33
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Nishio T, Yoshikawa Y, Yoshikawa K, Sato SI. Longer DNA exhibits greater potential for cell-free gene expression. Sci Rep 2021; 11:11739. [PMID: 34083658 PMCID: PMC8175755 DOI: 10.1038/s41598-021-91243-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Accepted: 05/24/2021] [Indexed: 12/17/2022] Open
Abstract
Cell-free gene expression systems have been valuable tools for understanding how transcription/translation can be regulated in living cells. Many studies have investigated the determining factors that affect gene expression. Here we report the effect of the length of linearized reporter DNAs encoding the firefly luciferase gene so as to exclude the influence of supercoiling. It is found that longer DNA molecules exhibit significantly greater potency in gene expression; for example, the expression level for DNA with 25.7 kbp is 1000-times higher than that for DNA of 1.7 kbp. AFM observation of the DNA conformation indicates that longer DNA takes shrunken conformation with a higher segment density in the reaction mixture for gene expression, in contrast to the stiff conformation of shorter DNA. We propose an underlying mechanism for the favorable effect of longer DNA on gene expression in terms of the enhancement of access of RNA polymerase to the shrunken conformation. It is expected that the enhancement of gene expression efficiency with a shrunken DNA conformation would also be a rather general mechanism in living cellular environments.
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Affiliation(s)
- Takashi Nishio
- Faculty of Life and Medical Sciences, Doshisha University, Kyoto, 610-0394, Japan
| | - Yuko Yoshikawa
- Faculty of Life and Medical Sciences, Doshisha University, Kyoto, 610-0394, Japan
| | - Kenichi Yoshikawa
- Faculty of Life and Medical Sciences, Doshisha University, Kyoto, 610-0394, Japan
| | - Shin-Ichi Sato
- Institute for Chemical Research, Kyoto University, Kyoto, 611-0011, Japan.
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34
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Kim J, Quijano JF, Kim J, Yeung E, Murray RM. Synthetic logic circuits using RNA aptamer against T7 RNA polymerase. Biotechnol J 2021; 17:e2000449. [PMID: 33813787 DOI: 10.1002/biot.202000449] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 03/05/2021] [Accepted: 03/30/2021] [Indexed: 12/23/2022]
Abstract
Recent advances in nucleic acids engineering introduced several RNA-based regulatory components for synthetic gene circuits, expanding the toolsets to engineer organisms. In this work, we designed genetic circuits implementing an RNA aptamer previously described to have the capability of binding to the T7 RNA polymerase and inhibiting its activity in vitro. We first demonstrated the utility of the RNA aptamer in combination with programmable synthetic transcription networks in vitro. As a step to quickly assess the feasibility of aptamer functions in vivo, we tested the aptamer and its sequence variants in the cell-free expression system, verifying the aptamer functionality in the cell-free testbed. The expression of aptamer in E. coli demonstrated control over GFP expression driven by T7 RNA polymerase, indicating its ability to serve as building blocks for logic circuits and transcriptional cascades. This work elucidates the potential of T7 RNA polymerase aptamer as regulators for synthetic biological circuits and metabolic engineering.
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Affiliation(s)
- Jongmin Kim
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk, Republic of Korea.,Department of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
| | - Juan F Quijano
- Department of Biological Sciences, Columbia University, New York, New York, USA
| | - Jeongwon Kim
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk, Republic of Korea
| | - Enoch Yeung
- Department of Control and Dynamical Systems, California Institute of Technology, Pasadena, California, USA.,Department of Mechanical Engineering, University of California, Santa Barbara, California, USA
| | - Richard M Murray
- Department of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA.,Department of Control and Dynamical Systems, California Institute of Technology, Pasadena, California, USA
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35
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Collins SP, Rostain W, Liao C, Beisel CL. Sequence-independent RNA sensing and DNA targeting by a split domain CRISPR-Cas12a gRNA switch. Nucleic Acids Res 2021; 49:2985-2999. [PMID: 33619539 PMCID: PMC7968991 DOI: 10.1093/nar/gkab100] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 01/13/2021] [Accepted: 02/04/2021] [Indexed: 12/11/2022] Open
Abstract
CRISPR technologies increasingly require spatiotemporal and dosage control of nuclease activity. One promising strategy involves linking nuclease activity to a cell's transcriptional state by engineering guide RNAs (gRNAs) to function only after complexing with a ‘trigger’ RNA. However, standard gRNA switch designs do not allow independent selection of trigger and guide sequences, limiting gRNA switch application. Here, we demonstrate the modular design of Cas12a gRNA switches that decouples selection of these sequences. The 5′ end of the Cas12a gRNA is fused to two distinct and non-overlapping domains: one base pairs with the gRNA repeat, blocking formation of a hairpin required for Cas12a recognition; the other hybridizes to the RNA trigger, stimulating refolding of the gRNA repeat and subsequent gRNA-dependent Cas12a activity. Using a cell-free transcription-translation system and Escherichia coli, we show that designed gRNA switches can respond to different triggers and target different DNA sequences. Modulating the length and composition of the sensory domain altered gRNA switch performance. Finally, gRNA switches could be designed to sense endogenous RNAs expressed only under specific growth conditions, rendering Cas12a targeting activity dependent on cellular metabolism and stress. Our design framework thus further enables tethering of CRISPR activities to cellular states.
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Affiliation(s)
- Scott P Collins
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695, USA
| | - William Rostain
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ Evry, Université Paris-Saclay, 91057 Évry, France
| | - Chunyu Liao
- Helmholtz Institute for RNA-based Infection Research (HIRI)/Helmholtz Centre for Infection Research (HZI), Josef-Schneider-Str. 2/D15, 97080 Würzburg, Germany
| | - Chase L Beisel
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695, USA.,Helmholtz Institute for RNA-based Infection Research (HIRI)/Helmholtz Centre for Infection Research (HZI), Josef-Schneider-Str. 2/D15, 97080 Würzburg, Germany.,Medical Faculty, University of Würzburg, 97080 Würzburg, Germany
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36
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Yong C, Gyorgy A. Stability and Robustness of Unbalanced Genetic Toggle Switches in the Presence of Scarce Resources. Life (Basel) 2021; 11:271. [PMID: 33805212 PMCID: PMC8064337 DOI: 10.3390/life11040271] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 03/17/2021] [Accepted: 03/19/2021] [Indexed: 12/24/2022] Open
Abstract
While the vision of synthetic biology is to create complex genetic systems in a rational fashion, system-level behaviors are often perplexing due to the context-dependent dynamics of modules. One major source of context-dependence emerges due to the limited availability of shared resources, coupling the behavior of disconnected components. Motivated by the ubiquitous role of toggle switches in genetic circuits ranging from controlling cell fate differentiation to optimizing cellular performance, here we reveal how their fundamental dynamic properties are affected by competition for scarce resources. Combining a mechanistic model with nullcline-based stability analysis and potential landscape-based robustness analysis, we uncover not only the detrimental impacts of resource competition, but also how the unbalancedness of the switch further exacerbates them. While in general both of these factors undermine the performance of the switch (by pushing the dynamics toward monostability and increased sensitivity to noise), we also demonstrate that some of the unwanted effects can be alleviated by strategically optimized resource competition. Our results provide explicit guidelines for the context-aware rational design of toggle switches to mitigate our reliance on lengthy and expensive trial-and-error processes, and can be seamlessly integrated into the computer-aided synthesis of complex genetic systems.
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Affiliation(s)
- Chentao Yong
- Department of Chemical and Biological Engineering, New York University, New York, NY 10003, USA;
| | - Andras Gyorgy
- Department of Electrical and Computer Engineering, New York University Abu Dhabi, Abu Dhabi 129188, United Arab Emirates
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37
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Swank Z, Maerkl SJ. CFPU: A Cell-Free Processing Unit for High-Throughput, Automated In Vitro Circuit Characterization in Steady-State Conditions. BIODESIGN RESEARCH 2021; 2021:2968181. [PMID: 37849954 PMCID: PMC10521719 DOI: 10.34133/2021/2968181] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Accepted: 02/24/2021] [Indexed: 10/19/2023] Open
Abstract
Forward engineering synthetic circuits are at the core of synthetic biology. Automated solutions will be required to facilitate circuit design and implementation. Circuit design is increasingly being automated with design software, but innovations in experimental automation are lagging behind. Microfluidic technologies made it possible to perform in vitro transcription-translation (tx-tl) reactions with increasing throughput and sophistication, enabling screening and characterization of individual circuit elements and complete circuit designs. Here, we developed an automated microfluidic cell-free processing unit (CFPU) that extends high-throughput screening capabilities to a steady-state reaction environment, which is essential for the implementation and analysis of more complex and dynamic circuits. The CFPU contains 280 chemostats that can be individually programmed with DNA circuits. Each chemostat is periodically supplied with tx-tl reagents, giving rise to sustained, long-term steady-state conditions. Using microfluidic pulse width modulation (PWM), the device is able to generate tx-tl reagent compositions in real time. The device has higher throughput, lower reagent consumption, and overall higher functionality than current chemostat devices. We applied this technology to map transcription factor-based repression under equilibrium conditions and implemented dynamic gene circuits switchable by small molecules. We expect the CFPU to help bridge the gap between circuit design and experimental automation for in vitro development of synthetic gene circuits.
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Affiliation(s)
- Zoe Swank
- Institute of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne, Switzerland
| | - Sebastian J. Maerkl
- Institute of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne, Switzerland
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38
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A Relationship between NTP and Cell Extract Concentration for Cell-Free Protein Expression. Life (Basel) 2021; 11:life11030237. [PMID: 33805612 PMCID: PMC7999496 DOI: 10.3390/life11030237] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 03/10/2021] [Accepted: 03/11/2021] [Indexed: 01/29/2023] Open
Abstract
The cell-free protein synthesis (CFPS) that synthesizes mRNA and protein from a template DNA has been featured as an important tool to emulate living systems in vitro. However, an obstacle to emulate living cells by CFPS is the loss of activity in the case of usage of high concentration cell extracts. In this study, we found that a high concentration of NTP which inhibits in the case of lower concentration cell extract restored the loss of CFPS activity using high concentration cell extracts. The NTP restoration was independent of the energy regeneration system used, and NTP derivatives also restored the levels of CFPS using a high concentration cell extract. Experiments using dialysis mode of CFPS showed that continuous exchange of small molecule reduced levels of NTP requirement and improved reaction speed of CFPS using the high concentration of cell extract. These findings contribute to the development of a method to understand the condition of living cells by in vitro emulation, and are expected to lead to the achievement of the reconstitution of living cells from biomolecule mixtures.
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39
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Singhal V, Tuza ZA, Sun ZZ, Murray RM. A MATLAB toolbox for modeling genetic circuits in cell-free systems. Synth Biol (Oxf) 2021; 6:ysab007. [PMID: 33981862 PMCID: PMC8102020 DOI: 10.1093/synbio/ysab007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 12/07/2020] [Accepted: 12/23/2020] [Indexed: 01/19/2023] Open
Abstract
We introduce a MATLAB-based simulation toolbox, called txtlsim, for an Escherichia coli-based Transcription-Translation (TX-TL) system. This toolbox accounts for several cell-free-related phenomena, such as resource loading, consumption and degradation, and in doing so, models the dynamics of TX-TL reactions for the entire duration of solution phase batch-mode experiments. We use a Bayesian parameter inference approach to characterize the reaction rate parameters associated with the core transcription, translation and mRNA degradation mechanics of the toolbox, allowing it to reproduce constitutive mRNA and protein-expression trajectories. We demonstrate the use of this characterized toolbox in a circuit behavior prediction case study for an incoherent feed-forward loop.
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Affiliation(s)
- Vipul Singhal
- Spatial and Single Cell Systems Domain, Genome Institute of Singapore, 60 Biopolis St, 138672, Singapore
| | - Zoltan A Tuza
- Department of Bioengineering, Imperial College London, Exhibition Rd, South Kensington, SW7 2BU, London, UK
| | - Zachary Z Sun
- Tierra Bioscienes, 1933 Davis St #223, 94577, CA, USA
| | - Richard M Murray
- Control and Dynamical Systems and Biology and Biological Engineering, California Institute of Technology, 1200 E California Blvd, 91125, CA, USA
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40
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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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41
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Abstract
One of the fundamental properties of engineered large-scale complex systems is modularity. In synthetic biology, genetic parts exhibit context-dependent behavior. Here, we describe and quantify a major source of such behavior: retroactivity. In particular, we provide a step-by-step guide for characterizing retroactivity to restore the modular description of genetic modules. Additionally, we also discuss how retroactivity can be leveraged to quantify and maximize robustness to perturbations due to interconnection of genetic modules.
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Affiliation(s)
- Andras Gyorgy
- New York University Abu Dhabi, Abu Dhabi, United Arab Emirates.
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42
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Lavickova B, Laohakunakorn N, Maerkl SJ. A partially self-regenerating synthetic cell. Nat Commun 2020; 11:6340. [PMID: 33311509 PMCID: PMC7733450 DOI: 10.1038/s41467-020-20180-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 11/16/2020] [Indexed: 01/16/2023] Open
Abstract
Self-regeneration is a fundamental function of all living systems. Here we demonstrate partial molecular self-regeneration in a synthetic cell. By implementing a minimal transcription-translation system within microfluidic reactors, the system is able to regenerate essential protein components from DNA templates and sustain synthesis activity for over a day. By quantitating genotype-phenotype relationships combined with computational modeling we find that minimizing resource competition and optimizing resource allocation are both critically important for achieving robust system function. With this understanding, we achieve simultaneous regeneration of multiple proteins by determining the required DNA ratios necessary for sustained self-regeneration. This work introduces a conceptual and experimental framework for the development of a self-replicating synthetic cell.
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Affiliation(s)
- Barbora Lavickova
- Institute of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Nadanai Laohakunakorn
- Institute of Quantitative Biology, Biochemistry, and Biotechnology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Sebastian J Maerkl
- Institute of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
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43
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Dopp JL, Reuel NF. Simple, functional, inexpensive cell extract for in vitro prototyping of proteins with disulfide bonds. Biochem Eng J 2020. [DOI: 10.1016/j.bej.2020.107790] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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44
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Benítez-Mateos AI, Zeballos N, Comino N, Moreno de Redrojo L, Randelovic T, López-Gallego F. Microcompartmentalized Cell-Free Protein Synthesis in Hydrogel μ-Channels. ACS Synth Biol 2020; 9:2971-2978. [PMID: 33170665 DOI: 10.1021/acssynbio.0c00462] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The rapid demand for protein-based molecules has stimulated much research on cell-free protein synthesis (CFPS); however, there are still many challenges in terms of cost-efficiency, process intensification, and sustainability. Herein, we describe the microcompartmentalization of CFPS of superfolded green fluorescent protein (sGFP) in alginate hydrogels, which were casted into a μ-channel device. CFPS was optimized for the microcompartmentalized environment and characterized in terms of synthesis yield. To extend the scope of this technology, the use of other biocompatible materials (collagen, laponite, and agarose) was explored. In addition, the diffusion of sGFP from the hydrogel microenvironment to the bulk was demonstrated, opening a promising opportunity for concurrent synthesis and delivery of proteins. Finally, we provide an application for this system: the CFPS of enzymes. The present design of the hydrogel μ-channel device may enhance the potential application of microcompartmentalized CFPS in biosensing, bioprototyping, and therapeutic development.
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Affiliation(s)
- Ana I. Benítez-Mateos
- Heterogeneous Biocatalysis Laboratory, CICbiomaGUNE, Paseo Miramón 182. Edificio empresarial “C”, 20014 San Sebastián, Spain
- Heterogeneous Biocatalysis Laboratory, Instituto de Síntesis Química y Catálisis Homogénea (iSQCH), CSIC-Universidad de Zaragoza, C/Pedro Cerbuna 12, 50009 Zaragoza, Spain
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Nicoll Zeballos
- Heterogeneous Biocatalysis Laboratory, CICbiomaGUNE, Paseo Miramón 182. Edificio empresarial “C”, 20014 San Sebastián, Spain
| | - Natalia Comino
- Heterogeneous Biocatalysis Laboratory, CICbiomaGUNE, Paseo Miramón 182. Edificio empresarial “C”, 20014 San Sebastián, Spain
| | - Lucía Moreno de Redrojo
- Heterogeneous Biocatalysis Laboratory, Instituto de Síntesis Química y Catálisis Homogénea (iSQCH), CSIC-Universidad de Zaragoza, C/Pedro Cerbuna 12, 50009 Zaragoza, Spain
| | - Teodora Randelovic
- Tissue MicroEnvironment (TME) Lab, Institute for Health Research Aragón (IISA), Avda. San Juan Bosco 13, 50009 Zaragoza, Spain
- Aragon Institute of Engineering Research (I3A), University of Zaragoza, Mariano Escuillor s/n, 50018 Zaragoza, Spain
| | - Fernando López-Gallego
- Heterogeneous Biocatalysis Laboratory, CICbiomaGUNE, Paseo Miramón 182. Edificio empresarial “C”, 20014 San Sebastián, Spain
- Heterogeneous Biocatalysis Laboratory, Instituto de Síntesis Química y Catálisis Homogénea (iSQCH), CSIC-Universidad de Zaragoza, C/Pedro Cerbuna 12, 50009 Zaragoza, Spain
- IKERBASQUE, Basque Foundation for Science, 48009 Bilbao, Spain
- ARAID, Aragon Foundation for Science, 50009 Zaragoza, Spain
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45
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Müller J, Siemann-Herzberg M, Takors R. Modeling Cell-Free Protein Synthesis Systems-Approaches and Applications. Front Bioeng Biotechnol 2020; 8:584178. [PMID: 33195146 PMCID: PMC7655533 DOI: 10.3389/fbioe.2020.584178] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 09/29/2020] [Indexed: 01/03/2023] Open
Abstract
In vitro systems are ideal setups to investigate the basic principles of biochemical reactions and subsequently the bricks of life. Cell-free protein synthesis (CFPS) systems mimic the transcription and translation processes of whole cells in a controlled environment and allow the detailed study of single components and reaction networks. In silico studies of CFPS systems help us to understand interactions and to identify limitations and bottlenecks in those systems. Black-box models laid the foundation for understanding the production and degradation dynamics of macromolecule components such as mRNA, ribosomes, and proteins. Subsequently, more sophisticated models revealed shortages in steps such as translation initiation and tRNA supply and helped to partially overcome these limitations. Currently, the scope of CFPS modeling has broadened to various applications, ranging from the screening of kinetic parameters to the stochastic analysis of liposome-encapsulated CFPS systems and the assessment of energy supply properties in combination with flux balance analysis (FBA).
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Affiliation(s)
| | | | - Ralf Takors
- Institute of Biochemical Engineering, University of Stuttgart, Stuttgart, Germany
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46
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Marucci L, Barberis M, Karr J, Ray O, Race PR, de Souza Andrade M, Grierson C, Hoffmann SA, Landon S, Rech E, Rees-Garbutt J, Seabrook R, Shaw W, Woods C. Computer-Aided Whole-Cell Design: Taking a Holistic Approach by Integrating Synthetic With Systems Biology. Front Bioeng Biotechnol 2020; 8:942. [PMID: 32850764 PMCID: PMC7426639 DOI: 10.3389/fbioe.2020.00942] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 07/21/2020] [Indexed: 01/03/2023] Open
Abstract
Computer-aided design (CAD) for synthetic biology promises to accelerate the rational and robust engineering of biological systems. It requires both detailed and quantitative mathematical and experimental models of the processes to (re)design biology, and software and tools for genetic engineering and DNA assembly. Ultimately, the increased precision in the design phase will have a dramatic impact on the production of designer cells and organisms with bespoke functions and increased modularity. CAD strategies require quantitative models of cells that can capture multiscale processes and link genotypes to phenotypes. Here, we present a perspective on how whole-cell, multiscale models could transform design-build-test-learn cycles in synthetic biology. We show how these models could significantly aid in the design and learn phases while reducing experimental testing by presenting case studies spanning from genome minimization to cell-free systems. We also discuss several challenges for the realization of our vision. The possibility to describe and build whole-cells in silico offers an opportunity to develop increasingly automatized, precise and accessible CAD tools and strategies.
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Affiliation(s)
- Lucia Marucci
- Department of Engineering Mathematics, University of Bristol, Bristol, United Kingdom.,School of Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom.,Bristol Centre for Synthetic Biology (BrisSynBio), University of Bristol, Bristol, United Kingdom
| | - Matteo Barberis
- Systems Biology, School of Biosciences and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom.,Centre for Mathematical and Computational Biology, CMCB, University of Surrey, Guildford, United Kingdom.,Synthetic Systems Biology and Nuclear Organization, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, Netherlands
| | - Jonathan Karr
- Icahn Institute for Data Science and Genomic Technology, Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Oliver Ray
- Department of Computer Science, University of Bristol, Bristol, United Kingdom
| | - Paul R Race
- Bristol Centre for Synthetic Biology (BrisSynBio), University of Bristol, Bristol, United Kingdom.,School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Miguel de Souza Andrade
- Brazilian Agricultural Research Corporation/National Institute of Science and Technology - Synthetic Biology, Brasília, Brazil.,Department of Cell Biology, Institute of Biological Sciences, University of Brasília, Brasília, Brazil
| | - Claire Grierson
- Bristol Centre for Synthetic Biology (BrisSynBio), University of Bristol, Bristol, United Kingdom.,School of Biological Sciences, University of Bristol, Bristol, United Kingdom
| | - Stefan Andreas Hoffmann
- Manchester Institute of Biotechnology, The University of Manchester, Manchester, United Kingdom
| | - Sophie Landon
- Department of Engineering Mathematics, University of Bristol, Bristol, United Kingdom.,Bristol Centre for Synthetic Biology (BrisSynBio), University of Bristol, Bristol, United Kingdom
| | - Elibio Rech
- Brazilian Agricultural Research Corporation/National Institute of Science and Technology - Synthetic Biology, Brasília, Brazil
| | - Joshua Rees-Garbutt
- Bristol Centre for Synthetic Biology (BrisSynBio), University of Bristol, Bristol, United Kingdom.,School of Biological Sciences, University of Bristol, Bristol, United Kingdom
| | - Richard Seabrook
- Elizabeth Blackwell Institute for Health Research (EBI), University of Bristol, Bristol, United Kingdom
| | - William Shaw
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Christopher Woods
- Bristol Centre for Synthetic Biology (BrisSynBio), University of Bristol, Bristol, United Kingdom.,School of Chemistry, University of Bristol, Bristol, United Kingdom
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47
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Laohakunakorn N. Cell-Free Systems: A Proving Ground for Rational Biodesign. Front Bioeng Biotechnol 2020; 8:788. [PMID: 32793570 PMCID: PMC7393481 DOI: 10.3389/fbioe.2020.00788] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 06/22/2020] [Indexed: 11/13/2022] Open
Abstract
Cell-free gene expression systems present an alternative approach to synthetic biology, where biological gene expression is harnessed inside non-living, in vitro biochemical reactions. Taking advantage of a plethora of recent experimental innovations, they easily overcome certain challenges for computer-aided biological design. For instance, their open nature renders all their components directly accessible, greatly facilitating model construction and validation. At the same time, these systems present their own unique difficulties, such as limited reaction lifetimes and lack of homeostasis. In this Perspective, I propose that cell-free systems are an ideal proving ground to test rational biodesign strategies, as demonstrated by a small but growing number of examples of model-guided, forward engineered cell-free biosystems. It is likely that advances gained from this approach will contribute to our efforts to more reliably and systematically engineer both cell-free as well as living cellular systems for useful applications.
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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
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48
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Jung JK, Alam KK, Verosloff MS, Capdevila DA, Desmau M, Clauer PR, Lee JW, Nguyen PQ, Pastén PA, Matiasek SJ, Gaillard JF, Giedroc DP, Collins JJ, Lucks JB. Cell-free biosensors for rapid detection of water contaminants. Nat Biotechnol 2020; 38:1451-1459. [PMID: 32632301 PMCID: PMC7718425 DOI: 10.1038/s41587-020-0571-7] [Citation(s) in RCA: 163] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 05/19/2020] [Indexed: 12/23/2022]
Abstract
Lack of access to safe drinking water is a global problem, and methods to reliably and easily detect contaminants could be transformative. We report the development of a cell-free in vitro transcription system that uses RNA Output Sensors Activated by Ligand Induction (ROSALIND) to detect contaminants in water. A combination of highly processive RNA polymerases, allosteric protein transcription factors and synthetic DNA transcription templates regulates the synthesis of a fluorescence-activating RNA aptamer. The presence of a target contaminant induces the transcription of the aptamer, and a fluorescent signal is produced. We apply ROSALIND to detect a range of water contaminants, including antibiotics, small molecules and metals. We also show that adding RNA circuitry can invert responses, reduce crosstalk and improve sensitivity without protein engineering. The ROSALIND system can be freeze-dried for easy storage and distribution, and we apply it in the field to test municipal water supplies, demonstrating its potential use for monitoring water quality.
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Affiliation(s)
- Jaeyoung K Jung
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL, USA.,Center for Synthetic Biology, Northwestern University, Evanston, IL, USA.,Center for Water Research, Northwestern University, Evanston, IL, USA
| | - Khalid K Alam
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL, USA.,Center for Synthetic Biology, Northwestern University, Evanston, IL, USA.,Center for Water Research, Northwestern University, Evanston, IL, USA
| | - Matthew S Verosloff
- Center for Synthetic Biology, Northwestern University, Evanston, IL, USA.,Center for Water Research, Northwestern University, Evanston, IL, USA.,Interdisciplinary Biological Sciences Graduate Program, Northwestern University, Evanston, IL, USA
| | | | - Morgane Desmau
- Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL, USA
| | - Phillip R Clauer
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Jeong Wook Lee
- Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, Republic of Korea
| | - Peter Q Nguyen
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA
| | - Pablo A Pastén
- Departmento de Ingeniería Hidráulica y Ambiental, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Desarrollo Urbano Sustentable, Santiago, Chile
| | - Sandrine J Matiasek
- Department of Geological and Environmental Sciences, California State University, Chico, Chico, CA, USA.,Center for Water and the Environment, California State University, Chico, Chico, CA, USA
| | - Jean-François Gaillard
- Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL, USA
| | - David P Giedroc
- Department of Chemistry, Indiana University, Bloomington, IN, USA.,Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
| | - James J Collins
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.,Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA.,Institute for Medical Engineering & Science, Massachusetts Institute of Technology, Cambridge, MA, USA.,Synthetic Biology Center, Massachusetts Institute of Technology, Cambridge, MA, USA.,Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Julius B Lucks
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL, USA. .,Center for Synthetic Biology, Northwestern University, Evanston, IL, USA. .,Center for Water Research, Northwestern University, Evanston, IL, USA. .,Interdisciplinary Biological Sciences Graduate Program, Northwestern University, Evanston, IL, USA.
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49
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Development of a clostridia-based cell-free system for prototyping genetic parts and metabolic pathways. Metab Eng 2020; 62:95-105. [PMID: 32540392 DOI: 10.1016/j.ymben.2020.06.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 05/15/2020] [Accepted: 06/07/2020] [Indexed: 02/04/2023]
Abstract
Gas fermentation by autotrophic bacteria, such as clostridia, offers a sustainable path to numerous bioproducts from a range of local, highly abundant, waste and low-cost feedstocks, such as industrial flue gases or syngas generated from biomass or municipal waste. Unfortunately, designing and engineering clostridia remains laborious and slow. The ability to prototype individual genetic part function, gene expression patterns, and biosynthetic pathway performance in vitro before implementing designs in cells could help address these bottlenecks by speeding up design. Unfortunately, a high-yielding cell-free gene expression (CFE) system from clostridia has yet to be developed. Here, we report the development and optimization of a high-yielding (236 ± 24 μg/mL) batch CFE platform from the industrially relevant anaerobe, Clostridium autoethanogenum. A key feature of the platform is that both circular and linear DNA templates can be applied directly to the CFE reaction to program protein synthesis. We demonstrate the ability to prototype gene expression, and quantitatively map aerobic cell-free metabolism in lysates from this system. We anticipate that the C. autoethanogenum CFE platform will not only expand the protein synthesis toolkit for synthetic biology, but also serve as a platform in expediting the screening and prototyping of gene regulatory elements in non-model, industrially relevant microbes.
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50
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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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