1
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Jensen D, Ruiz Manzano A, Rector M, Tomko E, Record M, Galburt E. High-throughput, fluorescent-aptamer-based measurements of steady-state transcription rates for the Mycobacterium tuberculosis RNA polymerase. Nucleic Acids Res 2023; 51:e99. [PMID: 37739412 PMCID: PMC10602862 DOI: 10.1093/nar/gkad761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 08/04/2023] [Accepted: 09/11/2023] [Indexed: 09/24/2023] Open
Abstract
The first step in gene expression is the transcription of DNA sequences into RNA. Regulation at the level of transcription leads to changes in steady-state concentrations of RNA transcripts, affecting the flux of downstream functions and ultimately cellular phenotypes. Changes in transcript levels are routinely followed in cellular contexts via genome-wide sequencing techniques. However, in vitro mechanistic studies of transcription have lagged with respect to throughput. Here, we describe the use of a real-time, fluorescent-aptamer-based method to quantitate steady-state transcription rates of the Mycobacterium tuberculosis RNA polymerase. We present clear controls to show that the assay specifically reports on promoter-dependent, full-length RNA transcription rates that are in good agreement with the kinetics determined by gel-resolved, α-32P NTP incorporation experiments. We illustrate how the time-dependent changes in fluorescence can be used to measure regulatory effects of nucleotide concentrations and identity, RNAP and DNA concentrations, transcription factors, and antibiotics. Our data showcase the ability to easily perform hundreds of parallel steady-state measurements across varying conditions with high precision and reproducibility to facilitate the study of the molecular mechanisms of bacterial transcription.
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Affiliation(s)
- Drake Jensen
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO 63108, USA
| | - Ana Ruiz Manzano
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO 63108, USA
| | - Maxwell Rector
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Eric J Tomko
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO 63108, USA
| | - M Thomas Record
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Eric A Galburt
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO 63108, USA
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2
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Hiroshima Y, Kido JI, Kido R, Yoshida K, Bando M, Kajimoto K, Yumoto H, Shinohara Y. β-defensin 2 synthesized by a cell-free protein synthesis system and encapsulated in liposomes inhibits adhesion of Porphyromonas gingivalis to oral epithelial cells. Odontology 2023; 111:830-838. [PMID: 36745267 DOI: 10.1007/s10266-023-00789-x] [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: 06/27/2022] [Accepted: 01/29/2023] [Indexed: 02/07/2023]
Abstract
β-defensin 2 (BD-2), an antimicrobial peptide (AMP), is expressed by oral epithelial cells and plays an important role in innate immunity of the oral cavity. Cell-free protein synthesis (CFPS) systems have been studied for the synthesis of various proteins, however, the synthesis of BD-2 by a CFPS system has not been extensively explored. Liposomes have been developed as tools for drug delivery. A delivery of liposome-encapsulated AMP to oral epithelium may be useful to prevent oral infectious diseases. In the present study, we investigated the antimicrobial activity of the BD-2 protein, artificially synthesized using a CFPS system and encapsulated in liposomes. BD-2 protein was artificially synthesized using template DNA and a reconstituted CFPS system and was identified by western blotting. Bilayer liposomes were prepared using 1,2-dioleoyl-sn-glycero-3-phospho-choline and 3-sn-phosphatidylcholine from egg yolk. The artificially synthesized BD-2 was encapsulated in liposomes, collected by ultrafiltration, and detected by western blotting. Human oral epithelial cells were cultured with the liposome-encapsulated BD-2 and the concentration of BD-2 in the cell lysate of the culture with the synthesized BD-2 was higher than that of the control cultures. The antimicrobial activity of the synthesized BD-2 was investigated by an adhesion assay of Porphyromonas gingivalis to oral epithelial cells. The artificially synthesized BD-2 and its liposome significantly inhibited adhesion of P. gingivalis to oral epithelial cells. These results suggest that artificially synthesized BD-2 and liposome-encapsulated BD-2 show antimicrobial activity and can potentially play a role in oral healthcare for periodontal diseases.
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Affiliation(s)
- Yuka Hiroshima
- Department of Oral Microbiology, Tokushima University, 3-18-15, Kuramoto, Tokushima, 770-8504, Japan.
| | - Jun-Ichi Kido
- Department of Periodontology and Endodontology, Tokushima University, Tokushima, Japan
| | - Rie Kido
- Department of Periodontology and Endodontology, Tokushima University, Tokushima, Japan
| | - Kaya Yoshida
- Department of Oral Healthcare Education, Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
| | - Mika Bando
- Department of Periodontology and Endodontology, Tokushima University, Tokushima, Japan
| | - Kazuaki Kajimoto
- Health and Medical Research Institute, National Institute of Advanced Industrial Science and Technology, Tokyo, Japan
| | - Hiromichi Yumoto
- Department of Periodontology and Endodontology, Tokushima University, Tokushima, Japan
| | - Yasuo Shinohara
- Institute of Advanced Medical Sciences, Tokushima University, Tokushima, Japan
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3
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Bains J, Qureshi N, Ceylan B, Wacker A, Schwalbe H. Cell-free transcription-translation system: a dual read-out assay to characterize riboswitch function. Nucleic Acids Res 2023; 51:e82. [PMID: 37409574 PMCID: PMC10450168 DOI: 10.1093/nar/gkad574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 05/27/2023] [Accepted: 07/04/2023] [Indexed: 07/07/2023] Open
Abstract
Cell-free protein synthesis assays have become a valuable tool to understand transcriptional and translational processes. Here, we established a fluorescence-based coupled in vitro transcription-translation assay as a read-out system to simultaneously quantify mRNA and protein levels. We utilized the well-established quantification of the expression of shifted green fluorescent protein (sGFP) as a read-out of protein levels. In addition, we determined mRNA quantities using a fluorogenic Mango-(IV) RNA aptamer that becomes fluorescent upon binding to the fluorophore thiazole orange (TO). We utilized a Mango-(IV) RNA aptamer system comprising four subsequent Mango-(IV) RNA aptamer elements with improved sensitivity by building Mango arrays. The design of this reporter assay resulted in a sensitive read-out with a high signal-to-noise ratio, allowing us to monitor transcription and translation time courses in cell-free assays with continuous monitoring of fluorescence changes as well as snapshots of the reaction. Furthermore, we applied this dual read-out assay to investigate the function of thiamine-sensing riboswitches thiM and thiC from Escherichia coli and the adenine-sensing riboswitch ASW from Vibrio vulnificus and pbuE from Bacillus subtilis, which represent transcriptional and translational on- and off-riboswitches, respectively. This approach enabled a microplate-based application, a valuable addition to the toolbox for high-throughput screening of riboswitch function.
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Affiliation(s)
- Jasleen Kaur Bains
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University, Frankfurt am Main, Hesse 60438, Germany
| | - Nusrat Shahin Qureshi
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University, Frankfurt am Main, Hesse 60438, Germany
| | - Betül Ceylan
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University, Frankfurt am Main, Hesse 60438, Germany
| | - Anna Wacker
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University, Frankfurt am Main, Hesse 60438, Germany
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University, Frankfurt am Main, Hesse 60438, Germany
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4
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Kido JI, Hiroshima Y, Kido R, Yoshida K, Inagaki Y, Naruishi K, Kajimoto K, Kataoka M, Shinohara Y, Yumoto H. Lipocalin 2, synthesized using a cell-free protein synthesis system and encapsulated into liposomes, inhibits the adhesion of Porphyromonas gingivalis to human oral epithelial cells. J Periodontal Res 2023; 58:262-273. [PMID: 36579753 DOI: 10.1111/jre.13088] [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: 06/24/2022] [Revised: 12/08/2022] [Accepted: 12/13/2022] [Indexed: 12/30/2022]
Abstract
BACKGROUND AND OBJECTIVE Lipocalin 2 (LCN2), a glycoprotein expressed in epithelial cells and leukocytes, has an antibacterial effect and plays a role in innate immunity. The delivery of LCN2 encapsulated in liposomes to oral epithelium may be useful to prevent oral infectious diseases. This study aimed to investigate the inhibitory effect of LCN2, artificially synthesized using a cell-free protein synthesis (CFPS) system, on the adhesion of Porphyromonas gingivalis to oral epithelial cells in order to approach oral healthcare using LCN2. METHODS LCN 2 was synthesized using a CFPS system and assayed by Western blotting, mass spectrometry and enzyme-linked immunosorbent assay (ELISA). The bilayer liposomes were prepared by the spontaneous transfer method using 1,2-dioleoyl-sn-glycero-3 phosphocholine (DOPC), 3-sn-phosphatidylcholine from Egg Yolk (Egg-PC), and 1,2-dioleoyl-sn-glycero-3 phosphoethanolamine (DOPE). The cellular and medium fractions derived from the culture of oral epithelial cells with liposome-encapsulated LCN2 were assayed by Western blotting and ELISA. The effect of the synthesized LCN2 on adhesion of the labeled P. gingivalis to oral epithelial cells was investigated as an evaluation of its antibacterial activity. RESULTS The synthesized LCN2 protein was identified by Western blotting; its amino acid sequence was similar to that of recombinant LCN2 protein. The additions of DOPE and octa-arginine in the outer lipid-layer components of liposome significantly increased the delivery of liposomes to epithelial cells. When oral epithelial cells were cultured with the synthesized and liposome-encapsulated LCN2, LCN2 was identified in the cellular and medium fractions by Western blotting and its concentration in the cellular fraction from the culture with the synthesized LCN2 was significantly higher than that of a template DNA-free protein. The synthesized LCN2 and liposome-encapsulated LCN2 significantly inhibited the adhesion of P. gingivalis to oral epithelial cells compared with template DNA-free protein. CONCLUSION LCN2 was artificially synthesized by a CFPS system, encapsulated in liposomes, and delivered to oral epithelial cells, and demonstrated an antibacterial action against P. gingivalis. This approach may become a useful model for oral healthcare.
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Affiliation(s)
- Jun-Ichi Kido
- Department of Periodontology and Endodontology, Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
| | - Yuka Hiroshima
- Department of Oral Microbiology, Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
| | - Rie Kido
- Department of Periodontology and Endodontology, Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
| | - Kaya Yoshida
- Department of Oral Healthcare Education, Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
| | - Yuji Inagaki
- Department of Periodontology and Endodontology, Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
| | - Koji Naruishi
- Department of Periodontology and Endodontology, Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
| | - Kazuaki Kajimoto
- Health and Medical Research Institute, National Institute of Advanced Industrial, Science and Technology, Tokushima, Japan
| | - Masatoshi Kataoka
- Health and Medical Research Institute, National Institute of Advanced Industrial, Science and Technology, Tokushima, Japan
| | - Yasuo Shinohara
- Institute of Advanced Medical Sciences, Tokushima University, Tokushima, Japan
| | - Hiromichi Yumoto
- Department of Periodontology and Endodontology, Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
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5
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Jensen D, Manzano AR, Rector M, Tomko EJ, Record MT, Galburt EA. High-throughput, fluorescent-aptamer-based measurements of steady-state transcription rates for Mycobacterium tuberculosis RNA polymerase. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.13.532464. [PMID: 36993414 PMCID: PMC10054983 DOI: 10.1101/2023.03.13.532464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
The first step in gene expression is the transcription of DNA sequences into RNA. Regulation at the level of transcription leads to changes in steady-state concentrations of RNA transcripts, affecting the flux of downstream functions and ultimately cellular phenotypes. Changes in transcript levels are routinely followed in cellular contexts via genome-wide sequencing techniques. However, in vitro mechanistic studies of transcription have lagged with respect to throughput. Here, we describe the use of a real-time, fluorescent-aptamer-based method to quantitate steady-state transcription rates of the Mycobacterium tuberculosis RNA polymerase. We present clear controls to show that the assay specifically reports on promoter-dependent, full-length RNA transcription rates that are in good agreement with the kinetics determined by gel-resolved, α- 32 P NTP incorporation experiments. We illustrate how the time-dependent changes in fluorescence can be used to measure regulatory effects of nucleotide concentrations and identity, RNAP and DNA concentrations, transcription factors, and antibiotics. Our data showcase the ability to easily perform hundreds of parallel steady-state measurements across varying conditions with high precision and reproducibility to facilitate the study of the molecular mechanisms of bacterial transcription. Significance Statement RNA polymerase transcription mechanisms have largely been determined from in vitro kinetic and structural biology methods. In contrast to the limited throughput of these approaches, in vivo RNA sequencing provides genome-wide measurements but lacks the ability to dissect direct biochemical from indirect genetic mechanisms. Here, we present a method that bridges this gap, permitting high-throughput fluorescence-based measurements of in vitro steady-state transcription kinetics. We illustrate how an RNA-aptamer-based detection system can be used to generate quantitative information on direct mechanisms of transcriptional regulation and discuss the far-reaching implications for future applications.
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Affiliation(s)
- Drake Jensen
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO, 63108, USA
| | - Ana Ruiz Manzano
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO, 63108, USA
| | - Maxwell Rector
- Department of Biochemistry, University of Wisconsin, Madison, WI, 53706, USA
| | - Eric J. Tomko
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO, 63108, USA
| | - M. Thomas Record
- Department of Biochemistry, University of Wisconsin, Madison, WI, 53706, USA
| | - Eric A. Galburt
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO, 63108, USA
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6
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Chauhan G, Norred SE, Dabbs RM, Caveney PM, George JKV, Collier CP, Simpson ML, Abel SM. Crowding-Induced Spatial Organization of Gene Expression in Cell-Sized Vesicles. ACS Synth Biol 2022; 11:3733-3742. [PMID: 36260840 DOI: 10.1021/acssynbio.2c00336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Cell-free protein synthesis is an important tool for studying gene expression and harnessing it for applications. In cells, gene expression is regulated in part by the spatial organization of transcription and translation. Unfortunately, current cell-free approaches are unable to control the organization of molecular components needed for gene expression, which limits the ability to probe and utilize its effects. Here, we show, using complementary computational and experimental approaches, that macromolecular crowding can be used to control the spatial organization and translational efficiency of gene expression in cell-sized vesicles. Computer simulations and imaging experiments reveal that, as crowding is increased, DNA plasmids become localized at the inner surface of vesicles. Ribosomes, in contrast, remain uniformly distributed, demonstrating that crowding can be used to differentially organize components of gene expression. We further carried out cell-free protein synthesis reactions in cell-sized vesicles and quantified mRNA and protein abundance. At sufficiently high levels of crowding, we observed localization of mRNA near vesicle surfaces, a decrease in translational efficiency and protein abundance, and anomalous scaling of protein abundance as a function of vesicle size. These results are consistent with high levels of crowding causing altered spatial organization and slower diffusion. Our work demonstrates a straightforward way to control the organization of gene expression in cell-sized vesicles and provides insight into the spatial regulation of gene expression in cells.
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Affiliation(s)
- Gaurav Chauhan
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Knoxville, Tennessee37996, United States
| | - S Elizabeth Norred
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States.,Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville and Oak Ridge National Laboratory, Knoxville, Tennessee37996, United States
| | - Rosemary M Dabbs
- Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville and Oak Ridge National Laboratory, Knoxville, Tennessee37996, United States
| | - Patrick M Caveney
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States.,Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville and Oak Ridge National Laboratory, Knoxville, Tennessee37996, United States
| | - John K Vincent George
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States.,Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville and Oak Ridge National Laboratory, Knoxville, Tennessee37996, United States
| | - C Patrick Collier
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
| | - Michael L Simpson
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States.,Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville and Oak Ridge National Laboratory, Knoxville, Tennessee37996, United States
| | - Steven M Abel
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Knoxville, Tennessee37996, United States
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7
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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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8
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In vitro synthesis of 32 translation-factor proteins from a single template reveals impaired ribosomal processivity. Sci Rep 2021; 11:1898. [PMID: 33479285 PMCID: PMC7820420 DOI: 10.1038/s41598-020-80827-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 12/24/2020] [Indexed: 12/20/2022] Open
Abstract
The Protein synthesis Using Recombinant Elements (PURE) system enables transcription and translation of a DNA template from purified components. Therefore, the PURE system-catalyzed generation of RNAs and proteins constituting the PURE system itself represents a major challenge toward a self-replicating minimal cell. In this work, we show that all translation factors (except elongation factor Tu) and 20 aminoacyl-tRNA synthetases can be expressed in the PURE system from a single plasmid encoding 32 proteins in 30 cistrons. Cell-free synthesis of all 32 proteins is confirmed by quantitative mass spectrometry-based proteomic analysis using isotopically labeled amino acids. We find that a significant fraction of the gene products consists of proteins missing their C-terminal ends. The per-codon processivity loss that we measure lies between 1.3 × 10-3 and 13.2 × 10-3, depending on the expression conditions, the version of the PURE system, and the coding sequence. These values are 5 to 50 times higher than those measured in vivo in E. coli. With such an impaired processivity, a considerable fraction of the biosynthesis capacity of the PURE system is wasted, posing an unforeseen challenge toward the development of a self-regenerating PURE system.
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9
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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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10
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Drachuk I, Harbaugh S, Chávez JL, Kelley-Loughnane N. Improving the Activity of DNA-Encoded Sensing Elements through Confinement in Silk Microcapsules. ACS APPLIED MATERIALS & INTERFACES 2020; 12:48329-48339. [PMID: 33064462 DOI: 10.1021/acsami.0c13713] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Assembling synthetic bioparts into simplified artificial cells holds tremendous promise for advancing studies into the synthesis, biosensing, and delivery of biomolecules. Currently, the most successful techniques for encapsulation of the transcription-translation machinery exploit compartmentalization in liposomal vesicles. However, improvements to these methods may increase permeability to polar molecules, functionalization of the membrane with biologically active elements, and encapsulation efficiency. Microcapsules prepared via templated layer-by-layer (LbL) assembly using natural polymers have the potential to resolve some of the hurdles associated with liposomes. Here, we introduce a design for immobilizing DNA templates encoding translationally activated riboswitches and RNA aptamers into microcapsules prepared from regenerated silk fibroin protein. Adjusting several key parameters such as the presence of a polymer primer, concentration of silk protein, and DNA loadings during LbL assembly resulted in biocompatible, semipermeable, DNA-laden microcapsules. To preserve bioactivity, DNA was immobilized inside of the capsule membrane, which not only promoted stability during long-term storage at ambient conditions but also improved output response from spatially confined DNA-encoded sensing elements (SEs). Multiple copies of mRNA and GFPa1 protein were synthesized upon activation with specific analytes during in vitro transcription/translation reactions, demonstrating that selective permeability of silk microcapsules was essential for the diffusion of components of the cell-free system inside of the capsules. Further functionalization of capsule shells with gold nanoparticles (AuNPs) and antibodies (IgG) demonstrated the applicability of microcompartmentalized colloidal objects carrying SEs for remote sensing and/or targeted delivery. In the future, multifunctional, biocompatible silk-based microcapsules loaded with different RNA sensors can help advance the design of multiplexed biosensors tracking multiple biomarkers in complex media.
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Affiliation(s)
- Irina Drachuk
- UES Inc., Dayton, Ohio 45432, United States
- 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson AFB, Dayton, Ohio 45433, United States
| | - Svetlana Harbaugh
- 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson AFB, Dayton, Ohio 45433, United States
| | - Jorge L Chávez
- 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson AFB, Dayton, Ohio 45433, United States
| | - Nancy Kelley-Loughnane
- 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson AFB, Dayton, Ohio 45433, United States
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Dayton, Ohio 45433, United States
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11
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Stano P. Gene Expression Inside Liposomes: From Early Studies to Current Protocols. Chemistry 2019; 25:7798-7814. [DOI: 10.1002/chem.201806445] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Indexed: 12/26/2022]
Affiliation(s)
- Pasquale Stano
- Department of Biological and Environmental Sciences and Technologies (DiSTeBA)University of Salento, Ecotekne 73100 Lecce Italy
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12
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Blanken D, van Nies P, Danelon C. Quantitative imaging of gene-expressing liposomes reveals rare favorable phenotypes. Phys Biol 2019; 16:045002. [PMID: 30978176 DOI: 10.1088/1478-3975/ab0c62] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The biosynthesis of proteins from genomic DNA is a universal process in every living organism. Building a synthetic cell using separate biological parts hence implies to reconstitute a minimal gene expression apparatus and to compartmentalize it in a cell-mimicking environment. Previous studies have demonstrated that the PURE (Protein synthesis Using Recombinant Elements) system could be functionally encapsulated inside lipid vesicles. However, quantitative insights on functional consequences of spatial confinement of PURE system reactions remain scarce, which has hampered the full exploitation of gene-expressing liposomes as the fundamental unit to build an artificial cell. We report on direct imaging of tens of thousands of gene-expressing liposomes per sample allowing us to assess sub-population features in a statistically relevant manner. Both the vesicle size (diameter <10 μm) and lipid composition (mixture of phospholipids with zwitterionic and negatively charged headgroups, including cardiolipin) are compatible with the properties of bacterial cells. Therefore, our liposomes provide a suitable chassis to host the Escherichia coli-derived PURE translation machinery and other bacterial processes in future developments. The potential of high-content imaging to identify rare phenotypes is demonstrated by the fact that a subset of the liposome population exhibits a remarkably high yield of synthesized protein or a prolonged expression lifespan that surpasses the performance of ensemble liposome-averaged and bulk reactions. Among the three commercial PURE systems tested, PUREfrex2.0 offers the most favorable phenotypes displaying both high yield and long protein synthesis lifespan. Moreover, probing membrane permeability reveals a large heterogeneity amongst liposomes. In situ expression and membrane embedding of the pore-forming connexin leads to a characteristic permeability time profile, while increasing the fraction of permeable liposomes in the population. We see diversity in gene expression dynamics and membrane permeability as an opportunity to complement a rational design approach aiming at further implementing biological functions in liposome-based synthetic cells.
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Affiliation(s)
- Duco Blanken
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, van der Maasweg 9, 2629 HZ, Delft, The Netherlands
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13
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Doerr A, de Reus E, van Nies P, van der Haar M, Wei K, Kattan J, Wahl A, Danelon C. Modelling cell-free RNA and protein synthesis with minimal systems. Phys Biol 2019; 16:025001. [DOI: 10.1088/1478-3975/aaf33d] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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14
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Fernández C, Giraldo R. Modulation of the Aggregation of the Prion-like Protein RepA-WH1 by Chaperones in a Cell-Free Expression System and in Cytomimetic Lipid Vesicles. ACS Synth Biol 2018; 7:2087-2093. [PMID: 30125497 DOI: 10.1021/acssynbio.8b00283] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The accumulation of aggregated forms of proteins as toxic species is associated with fatal diseases such as amyloid proteinopathies. With the purpose of deconstructing the molecular mechanisms of these type of diseases through a Synthetic Biology approach, we are working with a model bacterial prion-like protein, RepA-WH1, expressed in a cell-free system. Our findings show that the Hsp70 chaperone from Escherichia coli, together with its Hsp40 and nucleotide exchange factor cochaperones, modulates the aggregation of the prion-like protein in the cell-free system. Moreover, we observe the same effect by reconstructing the aggregation process inside lipid vesicles. Chaperones reduce the number of aggregates formed, matching previous findings in vivo. We expect that the in vitro approach reported here will help to achieve better understanding and control of amyloid proteinopathies.
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Affiliation(s)
- Cristina Fernández
- Department of Cellular and Molecular Biology , Centro de Investigaciones Biológicas-CSIC , Madrid, E28040 , Spain
| | - Rafael Giraldo
- Department of Cellular and Molecular Biology , Centro de Investigaciones Biológicas-CSIC , Madrid, E28040 , Spain
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15
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Altamura E, Carrara P, D'Angelo F, Mavelli F, Stano P. Extrinsic stochastic factors (solute partition) in gene expression inside lipid vesicles and lipid-stabilized water-in-oil droplets: a review. Synth Biol (Oxf) 2018; 3:ysy011. [PMID: 32995519 PMCID: PMC7445889 DOI: 10.1093/synbio/ysy011] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 06/18/2018] [Accepted: 06/21/2018] [Indexed: 11/13/2022] Open
Abstract
The encapsulation of transcription-translation (TX-TL) machinery inside lipid vesicles and water-in-oil droplets leads to the construction of cytomimetic systems (often called 'synthetic cells') for synthetic biology and origins-of-life research. A number of recent reports have shown that protein synthesis inside these microcompartments is highly diverse in terms of rate and amount of synthesized protein. Here, we discuss the role of extrinsic stochastic effects (i.e. solute partition phenomena) as relevant factors contributing to this pattern. We evidence and discuss cases where between-compartment diversity seems to exceed the expected theoretical values. The need of accurate determination of solute content inside individual vesicles or droplets is emphasized, aiming at validating or rejecting the predictions calculated from the standard fluctuations theory. At the same time, we promote the integration of experiments and stochastic modeling to reveal the details of solute encapsulation and intra-compartment reactions.
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Affiliation(s)
- Emiliano Altamura
- Chemistry Department, University of Bari, Via E. Orabona 4, I-70126, Bari, Italy
| | - Paolo Carrara
- Department of Sciences, Roma Tre University, Viale G. Marconi 446, I-00146, Rome, Italy
| | - Francesca D'Angelo
- Department of Sciences, Roma Tre University, Viale G. Marconi 446, I-00146, Rome, Italy
| | - Fabio Mavelli
- Chemistry Department, University of Bari, Via E. Orabona 4, I-70126, Bari, Italy
| | - Pasquale Stano
- Department of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento, Ecotekne, I-73100, Lecce, Italy
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16
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Wang S, Majumder S, Emery NJ, Liu AP. Simultaneous monitoring of transcription and translation in mammalian cell-free expression in bulk and in cell-sized droplets. Synth Biol (Oxf) 2018; 3:ysy005. [PMID: 30003145 PMCID: PMC6034425 DOI: 10.1093/synbio/ysy005] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 03/24/2018] [Accepted: 04/17/2018] [Indexed: 12/17/2022] Open
Abstract
Transcription and translation are two critical processes during eukaryotic gene expression that regulate cellular activities. The development of mammalian cell-free expression (CFE) systems provides a platform for studying these two critical processes in vitro for bottom-up synthetic biology applications such as construction of an artificial cell. Moreover, real-time monitoring of the dynamics of synthesized mRNA and protein is key to characterize and optimize gene circuits before implementing in living cells or in artificial cells. However, there are few tools for measurement of mRNA and protein dynamics in mammalian CFE systems. Here, we developed a locked nucleic acid (LNA) probe for monitoring transcription in a HeLa-based CFE system in real-time. By using this LNA probe in conjunction with a fluorescent reporter protein, we were able to simultaneously monitor mRNA and protein dynamics in bulk reactions and cell-sized single-emulsion droplets. We found rapid production of mRNA transcripts that decreased over time as protein production ensued in bulk reactions. Our results also showed that transcription in cell-sized droplets has different dynamics compared to the transcription in bulk reactions. The use of this LNA probe in conjunction with fluorescent proteins in HeLa-based mammalian CFE system provides a versatile in vitro platform for studying mRNA dynamics for bottom-up synthetic biology applications.
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Affiliation(s)
- Shue Wang
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Sagardip Majumder
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Nicholas J Emery
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA.,Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Allen P Liu
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA.,Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA.,Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI, USA.,Biophysics Program, University of Michigan, Ann Arbor, MI, USA
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17
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Norred SE, Caveney PM, Chauhan G, Collier LK, Collier CP, Abel SM, Simpson ML. Macromolecular Crowding Induces Spatial Correlations That Control Gene Expression Bursting Patterns. ACS Synth Biol 2018; 7:1251-1258. [PMID: 29687993 DOI: 10.1021/acssynbio.8b00139] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Recent superresolution microscopy studies in E. coli demonstrate that the cytoplasm has highly variable local concentrations where macromolecular crowding plays a central role in establishing membrane-less compartmentalization. This spatial inhomogeneity significantly influences molecular transport and association processes central to gene expression. Yet, little is known about how macromolecular crowding influences gene expression bursting-the episodic process where mRNA and proteins are produced in bursts. Here, we simultaneously measured mRNA and protein reporters in cell-free systems, showing that macromolecular crowding decoupled the well-known relationship between fluctuations in the protein population (noise) and mRNA population statistics. Crowded environments led to a 10-fold increase in protein noise even though there were only modest changes in the mRNA population and fluctuations. Instead, cell-like macromolecular crowding created an inhomogeneous spatial distribution of mRNA ("spatial noise") that led to large variability in the protein production burst size. As a result, the mRNA spatial noise created large temporal fluctuations in the protein population. These results highlight the interplay between macromolecular crowding, spatial inhomogeneities, and the resulting dynamics of gene expression, and provide insights into using these organizational principles in both cell-based and cell-free synthetic biology.
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Affiliation(s)
- S Elizabeth Norred
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
- Bredesen Center for Interdisciplinary Research and Graduate Education , University of Tennessee Knoxville and Oak Ridge National Laboratory , Knoxville , Tennessee 37996 , United States
| | - Patrick M Caveney
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
- Bredesen Center for Interdisciplinary Research and Graduate Education , University of Tennessee Knoxville and Oak Ridge National Laboratory , Knoxville , Tennessee 37996 , United States
| | - Gaurav Chauhan
- Chemical and Biomolecular Engineering Department , University of Tennessee Knoxville , Knoxville , Tennessee 37996 , United States
| | - Lauren K Collier
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - C Patrick Collier
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Steven M Abel
- Chemical and Biomolecular Engineering Department , University of Tennessee Knoxville , Knoxville , Tennessee 37996 , United States
| | - Michael L Simpson
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
- Bredesen Center for Interdisciplinary Research and Graduate Education , University of Tennessee Knoxville and Oak Ridge National Laboratory , Knoxville , Tennessee 37996 , United States
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18
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van Nies P, Westerlaken I, Blanken D, Salas M, Mencía M, Danelon C. Self-replication of DNA by its encoded proteins in liposome-based synthetic cells. Nat Commun 2018; 9:1583. [PMID: 29679002 PMCID: PMC5910420 DOI: 10.1038/s41467-018-03926-1] [Citation(s) in RCA: 103] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 03/22/2018] [Indexed: 12/31/2022] Open
Abstract
Replication of DNA-encoded information and its conversion into functional proteins are universal properties of life. In an effort toward the construction of a synthetic minimal cell, we implement here the DNA replication machinery of the Φ29 virus in a cell-free gene expression system. Amplification of a linear DNA template by self-encoded, de novo synthesized Φ29 proteins is demonstrated. Complete information transfer is confirmed as the copied DNA can serve as a functional template for gene expression, which can be seen as an autocatalytic DNA replication cycle. These results show how the central dogma of molecular biology can be reconstituted and form a cycle in vitro. Finally, coupled DNA replication and gene expression is compartmentalized inside phospholipid vesicles providing the chassis for evolving functions in a prospective synthetic cell relying on the extant biology.
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Affiliation(s)
- Pauline van Nies
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, van der Maasweg 9, Delft, 2629 HZ, The Netherlands
| | - Ilja Westerlaken
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, van der Maasweg 9, Delft, 2629 HZ, The Netherlands
| | - Duco Blanken
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, van der Maasweg 9, Delft, 2629 HZ, The Netherlands
| | - Margarita Salas
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Universidad Autónoma, Canto Blanco, Madrid, 28049, Spain
| | - Mario Mencía
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Universidad Autónoma, Canto Blanco, Madrid, 28049, Spain
| | - Christophe Danelon
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, van der Maasweg 9, Delft, 2629 HZ, The Netherlands.
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19
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20
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Bouhedda F, Autour A, Ryckelynck M. Light-Up RNA Aptamers and Their Cognate Fluorogens: From Their Development to Their Applications. Int J Mol Sci 2017; 19:ijms19010044. [PMID: 29295531 PMCID: PMC5795994 DOI: 10.3390/ijms19010044] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 12/14/2017] [Accepted: 12/15/2017] [Indexed: 12/31/2022] Open
Abstract
An RNA-based fluorogenic module consists of a light-up RNA aptamer able to specifically interact with a fluorogen to form a fluorescent complex. Over the past decade, significant efforts have been devoted to the development of such modules, which now cover the whole visible spectrum, as well as to their engineering to serve in a wide range of applications. In this review, we summarize the different strategies used to develop each partner (the fluorogen and the light-up RNA aptamer) prior to giving an overview of their applications that range from live-cell RNA imaging to the set-up of high-throughput drug screening pipelines. We then conclude with a critical discussion on the current limitations of these modules and how combining in vitro selection with screening approaches may help develop even better molecules.
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Affiliation(s)
- Farah Bouhedda
- Architecture et Réactivité de l'ARN, CNRS, Université de Strasbourg, UPR 9002, F-67000 Strasbourg, France.
| | - Alexis Autour
- Architecture et Réactivité de l'ARN, CNRS, Université de Strasbourg, UPR 9002, F-67000 Strasbourg, France.
| | - Michael Ryckelynck
- Architecture et Réactivité de l'ARN, CNRS, Université de Strasbourg, UPR 9002, F-67000 Strasbourg, France.
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21
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Deshpande S, Birnie A, Dekker C. On-chip density-based purification of liposomes. BIOMICROFLUIDICS 2017; 11:034106. [PMID: 28529672 PMCID: PMC5422205 DOI: 10.1063/1.4983174] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 04/26/2017] [Indexed: 05/05/2023]
Abstract
Due to their cell membrane-mimicking properties, liposomes have served as a versatile research tool in science, from membrane biophysics and drug delivery systems to bottom-up synthetic cells. We recently reported a novel microfluidic method, Octanol-assisted Liposome Assembly (OLA), to form cell-sized, monodisperse, unilamellar liposomes with excellent encapsulation efficiency. Although OLA provides crucial advantages over alternative methods, it suffers from the presence of 1-octanol droplets, an inevitable by-product of the production process. These droplets can adversely affect the system regarding liposome stability, channel clogging, and imaging quality. In this paper, we report a density-based technique to separate the liposomes from droplets, integrated on the same chip. We show that this method can yield highly pure (>95%) liposome samples. We also present data showing that a variety of other separation techniques (based on size or relative permittivity) were unsuccessful. Our density-based separation approach favourably decouples the production and separation module, thus allowing freshly prepared liposomes to be used for downstream on-chip experimentation. This simple separation technique will make OLA a more versatile and widely applicable tool.
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Affiliation(s)
- Siddharth Deshpande
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Anthony Birnie
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Cees Dekker
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
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22
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Detection of human immunodeficiency virus RNAs in living cells using Spinach RNA aptamers. Virus Res 2016; 228:141-146. [PMID: 27914932 DOI: 10.1016/j.virusres.2016.11.031] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 10/28/2016] [Accepted: 11/23/2016] [Indexed: 12/22/2022]
Abstract
Many techniques currently used to measure HIV RNA production in cells suffer from limitations that include high background signal or the potential to destroy cellular context. Fluorophore-binding RNA aptamers offer the potential for visualizing RNAs directly in living cells with minimal cellular perturbation. We inserted a sequence encoding a fluorophore-binding RNA aptamer, known as Spinach, into the HIV genome such that predicted RNA secondary structures in both Spinach and HIV were preserved. Chimeric HIV-Spinach RNAs were functionally validated in vitro by testing their ability to enhance the fluorescence of a conditional fluorophore (DFHBI), which specifically binds Spinach. Fluorescence microscopy and PCR were used to verify expression of HIV-Spinach RNAs in human cells. HIV-1 gag RNA production and fluorescence were measured by qPCR and fluorometry, respectively. HIV-Spinach RNAs were fluorometrically detectable in vitro and were transcribed in human cell lines and primary cells, with both spliced and unspliced species detected by PCR. HIV-Spinach RNAs were visible by fluorescence microscopy in living cells, although signal was reproducibly weak. Cells expressing HIV-Spinach RNAs were capable of producing fluorometrically detectable virions, although detection of single viral particles was not possible. In summary, we have investigated a novel method for detecting HIV RNAs in living cells using the Spinach RNA aptamer. Despite the limitations of the present aptamer/fluorophore combination, this is the first application of this technology to an infectious disease and provides a foundation for future research into improved methods for studying HIV expression.
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23
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Bose S, Chakrabarty S, Ghosh D. Effect of Solvation on Electron Detachment and Excitation Energies of a Green Fluorescent Protein Chromophore Variant. J Phys Chem B 2016; 120:4410-20. [DOI: 10.1021/acs.jpcb.6b03723] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Samik Bose
- Physical
and Materials Chemistry
Division, CSIR-National Chemical Laboratory, Pune 411008, India
| | - Suman Chakrabarty
- Physical
and Materials Chemistry
Division, CSIR-National Chemical Laboratory, Pune 411008, India
| | - Debashree Ghosh
- Physical
and Materials Chemistry
Division, CSIR-National Chemical Laboratory, Pune 411008, India
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24
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Abstract
RNAs have highly complex and dynamic cellular localization patterns. Technologies for imaging RNA in living cells are important for uncovering their function and regulatory pathways. One approach for imaging RNA involves genetically encoding fluorescent RNAs using RNA mimics of green fluorescent protein (GFP). These mimics are RNA aptamers that bind fluorophores resembling those naturally found in GFP and activate their fluorescence. These RNA-fluorophore complexes, including Spinach, Spinach2, and Broccoli, can be used to tag RNAs and to image their localization in living cells. In this article, we describe the generation and optimization of these aptamers, along with strategies for expanding the spectral properties of their associated RNA-fluorophore complexes. We also discuss the structural basis for the fluorescence and photophysical properties of Spinach, and we describe future prospects for designing enhanced RNA-fluorophore complexes with enhanced photostability and increased sensitivity.
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Affiliation(s)
- Mingxu You
- Department of Pharmacology, Weill Medical College, Cornell University, New York, New York 10065; ,
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25
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Chan V, Novakowski SK, Law S, Klein-Bosgoed C, Kastrup CJ. Controlled Transcription of Exogenous mRNA in Platelets Using Protocells. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201506500] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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26
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Chan V, Novakowski SK, Law S, Klein-Bosgoed C, Kastrup CJ. Controlled Transcription of Exogenous mRNA in Platelets Using Protocells. Angew Chem Int Ed Engl 2015; 54:13590-3. [PMID: 26368852 DOI: 10.1002/anie.201506500] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Indexed: 12/15/2022]
Abstract
Transcribing exogenous RNA in eukaryotic cells requires delivering DNA to their nuclei and changing their genome. Nuclear delivery is often inefficient, limiting the potential scope of gene therapy and synthetic biology. These challenges may be overcome by techniques that allow for extranucleate transcription within eukaryotic cells. Protocells have been developed that enable transcription inside of liposomes; however, it has not yet been demonstrated whether this technology can be extended for use within eukaryotic cells. Here we show RNA-synthesizing nanoliposomes allow transcription of exogenous RNA inside anucleate cells. To accomplish this, components of transcription were encapsulated into liposomes and delivered to platelets. These liposomes were capable of light-induced transcription in platelets, providing proof-of-concept that protocell technology can be adapted for use within mammalian cells.
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Affiliation(s)
- Vivienne Chan
- Michael Smith Laboratories, University of British Columbia (Canada).,Biochemistry and Molecular Biology, University of British Columbia (Canada).,Centre for Blood Research, University of British Columbia (Canada)
| | - Stefanie K Novakowski
- Michael Smith Laboratories, University of British Columbia (Canada).,Biochemistry and Molecular Biology, University of British Columbia (Canada).,Centre for Blood Research, University of British Columbia (Canada)
| | - Simon Law
- Biochemistry and Molecular Biology, University of British Columbia (Canada).,Centre for Blood Research, University of British Columbia (Canada)
| | - Christa Klein-Bosgoed
- Centre for Blood Research, University of British Columbia (Canada).,Pathology and Laboratory Medicine, University of British Columbia (Canada)
| | - Christian J Kastrup
- Michael Smith Laboratories, University of British Columbia (Canada). .,Biochemistry and Molecular Biology, University of British Columbia (Canada). .,Centre for Blood Research, University of British Columbia (Canada).
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27
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Meyer AJ, Garry DJ, Hall B, Byrom MM, McDonald HG, Yang X, Yin YW, Ellington AD. Transcription yield of fully 2'-modified RNA can be increased by the addition of thermostabilizing mutations to T7 RNA polymerase mutants. Nucleic Acids Res 2015. [PMID: 26209133 PMCID: PMC4551944 DOI: 10.1093/nar/gkv734] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
On average, mutations are deleterious to proteins. Mutations conferring new function to a protein often come at the expense of protein folding or stability, reducing overall activity. Over the years, a panel of T7 RNA polymerases have been designed or evolved to accept nucleotides with modified ribose moieties. These modified RNAs have proven useful, especially in vivo, but the transcriptional yields tend to be quite low. Here we show that mutations previously shown to increase the thermal tolerance of T7 RNA polymerase can increase the activity of mutants with expanded substrate range. The resulting polymerase mutants can be used to generate 2'-O-methyl modified RNA with yields much higher than enzymes currently employed.
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Affiliation(s)
- Adam J Meyer
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Daniel J Garry
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Bradley Hall
- Altermune Technologies, LLC, Irvine, CA 92606, USA
| | - Michelle M Byrom
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Hannah G McDonald
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Xu Yang
- Department of Pharmacology and Toxicology, Sealy Center for Structural Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Y Whitney Yin
- Department of Pharmacology and Toxicology, Sealy Center for Structural Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Andrew D Ellington
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX 78712, USA Center for Systems & Synthetic Biology, University of Texas at Austin, Austin, TX 78712, USA
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28
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Hilaire MR, Abaskharon RM, Gai F. Biomolecular Crowding Arising from Small Molecules, Molecular Constraints, Surface Packing, and Nano-Confinement. J Phys Chem Lett 2015; 6:2546-53. [PMID: 26266732 PMCID: PMC4610718 DOI: 10.1021/acs.jpclett.5b00957] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The effect of macromolecular crowding on the structure, dynamics, and reactivity of biomolecules is well established and the relevant research has been extensively reviewed. Herein, we focus our discussion on crowding effects arising from small cosolvent molecules and densely packed surface conditions. In addition, we highlight recent efforts that capitalize on the excluded volume effect for various tailored biochemical and biophysical applications. Specifically, we discuss how a targeted increase in local mass density can be exploited to gain insight into the folding dynamics of the protein of interest and how confinement via reverse micelles can be used to study a range of biophysical questions, from protein hydration dynamics to amyloid formation.
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Affiliation(s)
| | | | - Feng Gai
- To whom correspondence should be addressed; ; Phone: 215-573-6256; Fax: 215-573-2112
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29
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Mavelli F, Marangoni R, Stano P. A Simple Protein Synthesis Model for the PURE System Operation. Bull Math Biol 2015; 77:1185-212. [PMID: 25911591 DOI: 10.1007/s11538-015-0082-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 04/07/2015] [Indexed: 11/24/2022]
Abstract
The encapsulation of transcription-translation (TX-TL) cell-free machinery inside lipid vesicles (liposomes) is a key element in synthetic cell technology. The PURE system is a TX-TL kit composed of well-characterized parts, whose concentrations are fine tunable, which works according to a modular architecture. For these reasons, the PURE system perfectly fulfils the requirements of synthetic biology and is widely used for constructing synthetic cells. In this work, we present a simplified mathematical model to simulate the PURE system operations. Based on Michaelis-Menten kinetics and differential equations, the model describes protein synthesis dynamics by using 9 chemical species, 6 reactions and 16 kinetic parameters. The model correctly predicts the time course for messenger RNA and protein production and allows quantitative predictions. By means of this model, it is possible to foresee how the PURE system species affect the mechanism of proteins synthesis and therefore help in understanding scenarios where the concentration of the PURE system components has been modified purposely or as a result of stochastic fluctuations (for example after random encapsulation inside vesicles). The model also makes the determination of response coefficients for all species involved in the TX-TL mechanism possible and allows for scrutiny on how chemical energy is consumed by the three PURE system modules (transcription, translation and aminoacylation).
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Affiliation(s)
- Fabio Mavelli
- Chemistry Department, University of Bari, Via Orabona 4, Bari, Italy,
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30
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Elani Y, Law RV, Ces O. Protein synthesis in artificial cells: using compartmentalisation for spatial organisation in vesicle bioreactors. Phys Chem Chem Phys 2015; 17:15534-7. [DOI: 10.1039/c4cp05933f] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Spatially segregated in vitro protein expression in a vesicle-based artificial cell, with different proteins synthesised in defined vesicle regions.
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Affiliation(s)
- Yuval Elani
- Department of Chemistry
- Imperial College London
- UK
- Institute of Chemical Biology
- Imperial College London
| | - Robert V. Law
- Department of Chemistry
- Imperial College London
- UK
- Institute of Chemical Biology
- Imperial College London
| | - Oscar Ces
- Department of Chemistry
- Imperial College London
- UK
- Institute of Chemical Biology
- Imperial College London
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van Nies P, Canton AS, Nourian Z, Danelon C. Monitoring mRNA and Protein Levels in Bulk and in Model Vesicle-Based Artificial Cells. Methods Enzymol 2015; 550:187-214. [DOI: 10.1016/bs.mie.2014.10.048] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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de Souza TP, Fahr A, Luisi PL, Stano P. Spontaneous Encapsulation and Concentration of Biological Macromolecules in Liposomes: An Intriguing Phenomenon and Its Relevance in Origins of Life. J Mol Evol 2014; 79:179-92. [DOI: 10.1007/s00239-014-9655-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 11/10/2014] [Indexed: 12/31/2022]
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Nourian Z, Scott A, Danelon C. Toward the assembly of a minimal divisome. SYSTEMS AND SYNTHETIC BIOLOGY 2014; 8:237-47. [PMID: 25136386 PMCID: PMC4127181 DOI: 10.1007/s11693-014-9150-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 04/15/2014] [Accepted: 04/17/2014] [Indexed: 11/24/2022]
Abstract
The construction of an irreducible minimal cell having all essential attributes of a living system is one of the biggest challenges facing synthetic biology. One ubiquitous task accomplished by any living systems is the division of the cell envelope. Hence, the assembly of an elementary, albeit sufficient, molecular machinery that supports compartment division, is a crucial step towards the realization of self-reproducing artificial cells. Looking backward to the molecular nature of possible ancestral, supposedly more rudimentary, cell division systems may help to identify a minimal divisome. In light of a possible evolutionary pathway of division mechanisms from simple lipid vesicles toward modern life, we define two approaches for recapitulating division in primitive cells: the membrane deforming protein route and the lipid biosynthesis route. Having identified possible proteins and working mechanisms participating in membrane shape alteration, we then discuss how they could be integrated into the construction framework of a programmable minimal cell relying on gene expression inside liposomes. The protein synthesis using recombinant elements (PURE) system, a reconstituted minimal gene expression system, is conceivably the most versatile synthesis platform. As a first step towards the de novo synthesis of a divisome, we showed that the N-BAR domain protein produced from its gene could assemble onto the outer surface of liposomes and sculpt the membrane into tubular structures. We finally discuss the remaining challenges for building up a self-reproducing minimal cell, in particular the coupling of the division machinery with volume expansion and genome replication.
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Affiliation(s)
- Zohreh Nourian
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - Andrew Scott
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - Christophe Danelon
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
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Siegal-Gaskins D, Tuza ZA, Kim J, Noireaux V, Murray RM. Gene circuit performance characterization and resource usage in a cell-free "breadboard". ACS Synth Biol 2014; 3:416-25. [PMID: 24670245 DOI: 10.1021/sb400203p] [Citation(s) in RCA: 137] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The many successes of synthetic biology have come in a manner largely different from those in other engineering disciplines; in particular, without well-characterized and simplified prototyping environments to play a role analogous to wind-tunnels in aerodynamics and breadboards in electrical engineering. However, as the complexity of synthetic circuits increases, the benefits--in cost savings and design cycle time--of a more traditional engineering approach can be significant. We have recently developed an in vitro "breadboard" prototyping platform based on E. coli cell extract that allows biocircuits to operate in an environment considerably simpler than, but functionally similar to, in vivo. The simplicity of this system makes it a promising tool for rapid biocircuit design and testing, as well as for probing fundamental aspects of gene circuit operation normally masked by cellular complexity. In this work, we characterize the cell-free breadboard using real-time and simultaneous measurements of transcriptional and translational activities of a small set of reporter genes and a transcriptional activation cascade. We determine the effects of promoter strength, gene concentration, and nucleoside triphosphate concentration on biocircuit properties, and we isolate the specific contributions of essential biomolecular resources-core RNA polymerase and ribosomes-to overall performance. Importantly, we show how limits on resources, particularly those involved in translation, are manifested as reduced expression in the presence of orthogonal genes that serve as additional loads on the system.
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Affiliation(s)
- Dan Siegal-Gaskins
- Division
of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Zoltan A. Tuza
- Faculty
of Information Technology, Pazmany Peter Catholic University, 1088 Budapest, Hungary
| | - Jongmin Kim
- Division
of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Vincent Noireaux
- School
of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Richard M. Murray
- Division
of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, United States
- Department
of Control and Dynamical Systems, California Institute of Technology, Pasadena, California 91125, United States
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