1
|
Bartelds MW, García-Blay Ó, Verhagen PGA, Wubbolts EJ, van Sluijs B, Heus HA, de Greef TFA, Huck WTS, Hansen MMK. Noise Minimization in Cell-Free Gene Expression. ACS Synth Biol 2023; 12:2217-2225. [PMID: 37478000 PMCID: PMC10443034 DOI: 10.1021/acssynbio.3c00174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Indexed: 07/23/2023]
Abstract
Biochemical reactions that involve small numbers of molecules are accompanied by a degree of inherent randomness that results in noisy reaction outcomes. In synthetic biology, the ability to minimize noise particularly during the reconstitution of future synthetic protocells is an outstanding challenge to secure robust and reproducible behavior. Here we show that by encapsulation of a bacterial cell-free gene expression system in water-in-oil droplets, in vitro-synthesized MazF reduces cell-free gene expression noise >2-fold. With stochastic simulations we identify that this noise minimization acts through both increased degradation and the autoregulatory feedback of MazF. Specifically, we find that the expression of MazF enhances the degradation rate of mRNA up to 18-fold in a sequence-dependent manner. This sequence specificity of MazF would allow targeted noise control, making it ideal to integrate into synthetic gene networks. Therefore, including MazF production in synthetic biology can significantly minimize gene expression noise, impacting future design principles of more complex cell-free gene circuits.
Collapse
Affiliation(s)
- Mart W. Bartelds
- Institute
for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Óscar García-Blay
- Institute
for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Pieter G. A. Verhagen
- Institute
for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Elise J. Wubbolts
- Institute
for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Bob van Sluijs
- Institute
for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Hans A. Heus
- Institute
for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Tom F. A. de Greef
- Institute
for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
- Laboratory
of Chemical Biology, Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
- Institute
for Complex Molecular Systems, Eindhoven
University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
- Computational
Biology Group, Department of Biomedical Engineering, Eindhoven University of Technology,
P.O. Box 513, 5600 MB Eindhoven, The Netherlands
- Center
for Living Technologies, Eindhoven-Wageningen-Utrecht
Alliance, 5600 MB Eindhoven, The Netherlands
| | - Wilhelm T. S. Huck
- Institute
for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Maike M. K. Hansen
- Institute
for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| |
Collapse
|
2
|
Yue K, Chen J, Li Y, Kai L. Advancing synthetic biology through cell-free protein synthesis. Comput Struct Biotechnol J 2023; 21:2899-2908. [PMID: 37216017 PMCID: PMC10196276 DOI: 10.1016/j.csbj.2023.05.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 05/03/2023] [Accepted: 05/03/2023] [Indexed: 05/24/2023] Open
Abstract
The rapid development of synthetic biology has enabled the production of compounds with revolutionary improvements in biotechnology. DNA manipulation tools have expedited the engineering of cellular systems for this purpose. Nonetheless, the inherent constraints of cellular systems persist, imposing an upper limit on mass and energy conversion efficiencies. Cell-free protein synthesis (CFPS) has demonstrated its potential to overcome these inherent constraints and has been instrumental in the further advancement of synthetic biology. Via the removal of the cell membranes and redundant parts of cells, CFPS has provided flexibility in directly dissecting and manipulating the Central Dogma with rapid feedback. This mini-review summarizes recent achievements of the CFPS technique and its application to a wide range of synthetic biology projects, such as minimal cell assembly, metabolic engineering, and recombinant protein production for therapeutics, as well as biosensor development for in vitro diagnostics. In addition, current challenges and future perspectives in developing a generalized cell-free synthetic biology are outlined.
Collapse
Affiliation(s)
- Ke Yue
- School of Life Sciences, Jiangsu Normal University, Xuzhou 22116, China
| | - Junyu Chen
- School of Life Sciences, Jiangsu Normal University, Xuzhou 22116, China
| | - Yingqiu Li
- School of Life Sciences, Jiangsu Normal University, Xuzhou 22116, China
| | - Lei Kai
- School of Life Sciences, Jiangsu Normal University, Xuzhou 22116, China
| |
Collapse
|
3
|
Cho E, Lu Y. Compartmentalizing Cell-Free Systems: Toward Creating Life-Like Artificial Cells and Beyond. ACS Synth Biol 2020; 9:2881-2901. [PMID: 33095011 DOI: 10.1021/acssynbio.0c00433] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Building an artificial cell is a research area that is rigorously studied in the field of synthetic biology. It has brought about much attention with the aim of ultimately constructing a natural cell-like structure. In particular, with the more mature cell-free platforms and various compartmentalization methods becoming available, achieving this aim seems not far away. In this review, we discuss the various types of artificial cells capable of hosting several cellular functions. Different compartmental boundaries and the mature and evolving technologies that are used for compartmentalization are examined, and exciting recent advances that overcome or have the potential to address current challenges are discussed. Ultimately, we show how compartmentalization and cell-free systems have, and will, come together to fulfill the goal to assemble a fully synthetic cell that displays functionality and complexity as advanced as that in nature. The development of such artificial cell systems will offer insight into the fundamental study of evolutionary biology and the sea of applications as a result. Although several challenges remain, emerging technologies such as artificial intelligence also appear to help pave the way to address them and achieve the ultimate goal.
Collapse
Affiliation(s)
- Eunhee Cho
- Key Lab of Industrial Biocatalysis, Ministry of Education, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
| | - Yuan Lu
- Key Lab of Industrial Biocatalysis, Ministry of Education, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
| |
Collapse
|
4
|
Vibhute MA, Schaap MH, Maas RJM, Nelissen FHT, Spruijt E, Heus HA, Hansen MMK, Huck WTS. Transcription and Translation in Cytomimetic Protocells Perform Most Efficiently at Distinct Macromolecular Crowding Conditions. ACS Synth Biol 2020; 9:2797-2807. [PMID: 32976714 PMCID: PMC7573978 DOI: 10.1021/acssynbio.0c00330] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
![]()
The formation of
cytomimetic protocells that capture the physicochemical
aspects of living cells is an important goal in bottom-up synthetic
biology. Here, we recreated the crowded cytoplasm in liposome-based
protocells and studied the kinetics of cell-free gene expression in
these crowded containers. We found that diffusion of key components
is affected not only by macromolecular crowding but also by enzymatic
activity in the protocell. Surprisingly, size-dependent diffusion
in crowded conditions yielded two distinct maxima for protein synthesis,
reflecting the differential impact of crowding on transcription and
translation. Our experimental data show, for the first time, that
macromolecular crowding induces a switch from reaction to diffusion
control and that this switch depends on the sizes of the macromolecules
involved. These results highlight the need to control the physical
environment in the design of synthetic cells.
Collapse
Affiliation(s)
- Mahesh A. Vibhute
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Mark H. Schaap
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Roel J. M. Maas
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Frank H. T. Nelissen
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Evan Spruijt
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Hans A. Heus
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Maike M. K. Hansen
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Wilhelm T. S. Huck
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| |
Collapse
|
5
|
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.
Collapse
Affiliation(s)
- Nadanai Laohakunakorn
- School of Biological Sciences, Institute of Quantitative Biology, Biochemistry, and Biotechnology, University of Edinburgh, Edinburgh, United Kingdom
| |
Collapse
|
6
|
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.
Collapse
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
| |
Collapse
|
7
|
Prangemeier T, Lehr FX, Schoeman RM, Koeppl H. Microfluidic platforms for the dynamic characterisation of synthetic circuitry. Curr Opin Biotechnol 2020; 63:167-176. [PMID: 32172160 DOI: 10.1016/j.copbio.2020.02.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 01/31/2020] [Accepted: 02/03/2020] [Indexed: 01/28/2023]
Abstract
Generating novel functionality from well characterised synthetic parts and modules lies at the heart of synthetic biology. Ideally, circuitry is rationally designed in silico with quantitatively predictive models to predetermined design specifications. Synthetic circuits are intrinsically stochastic, often dynamically modulated and set in a dynamic fluctuating environment within a living cell. To build more complex circuits and to gain insight into context effects, intrinsic noise and transient performance, characterisation techniques that resolve both heterogeneity and dynamics are required. Here we review recent advances in both in vitro and in vivo microfluidic technologies that are suitable for the characterisation of synthetic circuitry, modules and parts.
Collapse
Affiliation(s)
- Tim Prangemeier
- Centre for Synthetic Biology, Department of Electrical Engineering and Information Technology, Department of Biology, Technische Universität Darmstadt, Germany
| | - François-Xavier Lehr
- Centre for Synthetic Biology, Department of Electrical Engineering and Information Technology, Department of Biology, Technische Universität Darmstadt, Germany
| | - Rogier M Schoeman
- Centre for Synthetic Biology, Department of Electrical Engineering and Information Technology, Department of Biology, Technische Universität Darmstadt, Germany
| | - Heinz Koeppl
- Centre for Synthetic Biology, Department of Electrical Engineering and Information Technology, Department of Biology, Technische Universität Darmstadt, Germany.
| |
Collapse
|
8
|
Lehr FX, Hanst M, Vogel M, Kremer J, Göringer HU, Suess B, Koeppl H. Cell-Free Prototyping of AND-Logic Gates Based on Heterogeneous RNA Activators. ACS Synth Biol 2019; 8:2163-2173. [PMID: 31393707 DOI: 10.1021/acssynbio.9b00238] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
RNA-based devices controlling gene expression bear great promise for synthetic biology, as they offer many advantages such as short response times and light metabolic burden compared to protein-circuits. However, little work has been done regarding their integration to multilevel regulated circuits. In this work, we combined a variety of small transcriptional activator RNAs (STARs) and toehold switches to build highly effective AND-gates. To characterize the components and their dynamic range, we used an Escherichia coli (E. coli) cell-free transcription-translation (TX-TL) system dispensed via nanoliter droplets. We analyzed a prototype gate in vitro as well as in silico, employing parametrized ordinary differential equations (ODEs), for which parameters were inferred via parallel tempering, a Markov chain Monte Carlo (MCMC) method. On the basis of this analysis, we created nine additional AND-gates and tested them in vitro. The functionality of the gates was found to be highly dependent on the concentration of the activating RNA for either the STAR or the toehold switch. All gates were successfully implemented in vivo, offering a dynamic range comparable to the level of protein circuits. This study shows the potential of a rapid prototyping approach for RNA circuit design, using cell-free systems in combination with a model prediction.
Collapse
Affiliation(s)
- François-Xavier Lehr
- Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - Maleen Hanst
- Department of Electrical Engineering, Technische Universität Darmstadt, 64283 Darmstadt, Germany
| | - Marc Vogel
- Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - Jennifer Kremer
- Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - H. Ulrich Göringer
- Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - Beatrix Suess
- Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - Heinz Koeppl
- Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany
- Department of Electrical Engineering, Technische Universität Darmstadt, 64283 Darmstadt, Germany
| |
Collapse
|
9
|
Izri Z, Garenne D, Noireaux V, Maeda YT. Gene Expression in on-Chip Membrane-Bound Artificial Cells. ACS Synth Biol 2019; 8:1705-1712. [PMID: 31268305 DOI: 10.1021/acssynbio.9b00247] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Artificial cells made of molecular components and lipid membrane are emerging platforms to characterize living systems properties. Cell-free transcription-translation (TXTL) offers advantages for the bottom-up synthesis of cellular reactors. Yet, scaling up their design within well-defined geometries remains challenging. We present a microfluidic device hosting TXTL reactions of a reporter gene in thousands of microwells separated from an external buffer by a phospholipid membrane. In the presence of nutrients in the buffer, microreactors are stable beyond 24 h and yield a few mg/mL of proteins. Nutrients in the external solution feed the TXTL reaction at the picoliter scale via passive transport across the phospholipid membrane of each microfluidic well, despite the absence of pores. Replacing nutrients with an inert polymer and fatty acids at an isotonic concentration reduces microreactors efficiency, and a significant fraction yields no protein. This emphasizes the crucial role of the membrane for designing cell-free TXTL microreactors as efficient artificial cells.
Collapse
Affiliation(s)
- Ziane Izri
- Department of Physics , Kyushu University , Fukuoka , 819-0395 , Japan
| | - David Garenne
- School of Physics and Astronomy , University of Minnesota , Minneapolis , Minnesota 55455 United States
| | - Vincent Noireaux
- School of Physics and Astronomy , University of Minnesota , Minneapolis , Minnesota 55455 United States
| | - Yusuke T Maeda
- Department of Physics , Kyushu University , Fukuoka , 819-0395 , Japan
| |
Collapse
|
10
|
Yue K, Zhu Y, Kai L. Cell-Free Protein Synthesis: Chassis toward the Minimal Cell. Cells 2019; 8:cells8040315. [PMID: 30959805 PMCID: PMC6523147 DOI: 10.3390/cells8040315] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 04/01/2019] [Accepted: 04/04/2019] [Indexed: 11/16/2022] Open
Abstract
The quest for a minimal cell not only sheds light on the fundamental principles of life but also brings great advances in related applied fields such as general biotechnology. Minimal cell projects came from the study of a plausible route to the origin of life. Later on, research extended and also referred to the construction of artificial cells, or even more broadly, as in vitro synthetic biology. The cell-free protein synthesis (CFPS) techniques harness the central cellular activity of transcription/translation in an open environment, providing the framework for multiple cellular processes assembling. Therefore, CFPS systems have become the first choice in the construction of the minimal cell. In this review, we focus on the recent advances in the quantitative analysis of CFPS and on its advantage for addressing the bottom-up assembly of a minimal cell and illustrate the importance of systemic chassis behavior, such as stochasticity under a compartmentalized micro-environment.
Collapse
Affiliation(s)
- Ke Yue
- The Key Laboratory of Biotechnology for Medicinal Plants of Jiangsu Province, School of Life Sciences, Jiangsu Normal University, Shanghai Road 101, Xuzhou 221116, China.
| | - Yiyong Zhu
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing 210095, China.
| | - Lei Kai
- The Key Laboratory of Biotechnology for Medicinal Plants of Jiangsu Province, School of Life Sciences, Jiangsu Normal University, Shanghai Road 101, Xuzhou 221116, China.
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, D-82152 Martinsried, Germany.
| |
Collapse
|
11
|
Gregorio NE, Levine MZ, Oza JP. A User's Guide to Cell-Free Protein Synthesis. Methods Protoc 2019; 2:E24. [PMID: 31164605 PMCID: PMC6481089 DOI: 10.3390/mps2010024] [Citation(s) in RCA: 126] [Impact Index Per Article: 25.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 03/05/2019] [Accepted: 03/06/2019] [Indexed: 02/06/2023] Open
Abstract
Cell-free protein synthesis (CFPS) is a platform technology that provides new opportunities for protein expression, metabolic engineering, therapeutic development, education, and more. The advantages of CFPS over in vivo protein expression include its open system, the elimination of reliance on living cells, and the ability to focus all system energy on production of the protein of interest. Over the last 60 years, the CFPS platform has grown and diversified greatly, and it continues to evolve today. Both new applications and new types of extracts based on a variety of organisms are current areas of development. However, new users interested in CFPS may find it challenging to implement a cell-free platform in their laboratory due to the technical and functional considerations involved in choosing and executing a platform that best suits their needs. Here we hope to reduce this barrier to implementing CFPS by clarifying the similarities and differences amongst cell-free platforms, highlighting the various applications that have been accomplished in each of them, and detailing the main methodological and instrumental requirement for their preparation. Additionally, this review will help to contextualize the landscape of work that has been done using CFPS and showcase the diversity of applications that it enables.
Collapse
Affiliation(s)
- Nicole E Gregorio
- Center for Applications in Biotechnology, California Polytechnic State University, San Luis Obispo, CA 93407, USA.
- Department of Chemistry and Biochemistry, California Polytechnic State University, San Luis Obispo, CA 93407, USA.
| | - Max Z Levine
- Center for Applications in Biotechnology, California Polytechnic State University, San Luis Obispo, CA 93407, USA.
- Department of Biological Sciences, California Polytechnic State University, San Luis Obispo, CA 93407, USA.
| | - Javin P Oza
- Center for Applications in Biotechnology, California Polytechnic State University, San Luis Obispo, CA 93407, USA.
- Department of Chemistry and Biochemistry, California Polytechnic State University, San Luis Obispo, CA 93407, USA.
| |
Collapse
|
12
|
Shojaeian M, Lehr FX, Göringer HU, Hardt S. On-Demand Production of Femtoliter Drops in Microchannels and Their Use as Biological Reaction Compartments. Anal Chem 2019; 91:3484-3491. [DOI: 10.1021/acs.analchem.8b05063] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
|
13
|
Kai L, Schwille P. Cell-Free Protein Synthesis and Its Perspectives for Assembling Cells from the Bottom-Up. ACTA ACUST UNITED AC 2019; 3:e1800322. [PMID: 32648712 DOI: 10.1002/adbi.201800322] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 01/14/2019] [Indexed: 12/20/2022]
Abstract
The underlying idea of synthetic biology is that biological reactions/modules/systems can be precisely engineered and controlled toward desired products. Numerous efforts in the past decades in deciphering the complexity of biological systems in vivo have led to a variety of tools for synthetic biology, especially based on recombinant DNA. However, one generic limitation of all living systems is that the vast majority of energy input is dedicated to maintain the system as a whole, rather than the small part of interest. Cell-free synthetic biology is aiming at exactly this fundamental limitation, providing the next level of flexibility for engineering and designing biological systems in vitro. New technology has continuously inspired cell-free biology and extended its applications, including gene circuits, spatiotemporally controlled pathways, coactivated catalysts systems, and rationally designed multienzyme pathways, in particular, minimal cell construction. In the context of this special issue, discussing work being carried out in the "MaxSynBio" consortium, the advances in characterizing stochasticity and dynamics of cell-free protein synthesis within cell-sized compartments, as well as the molecular crowding effect, are discussed. The organization of spatial heterogeneity is the key prerequisite for achieving hierarchy and stepwise assembly of minimal cells from the bottom-up.
Collapse
Affiliation(s)
- Lei Kai
- School of Life Sciences, Jiangsu Normal University, Shanghai Road 101, 221116, Xuzhou, P. R. China.,Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, D-82152, Martinsried, Germany
| | - Petra Schwille
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, D-82152, Martinsried, Germany
| |
Collapse
|
14
|
Beppu K, Izri Z, Maeda YT, Sakamoto R. Geometric Effect for Biological Reactors and Biological Fluids. Bioengineering (Basel) 2018; 5:E110. [PMID: 30551608 PMCID: PMC6316181 DOI: 10.3390/bioengineering5040110] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 12/07/2018] [Accepted: 12/10/2018] [Indexed: 01/21/2023] Open
Abstract
As expressed "God made the bulk; the surface was invented by the devil" by W. Pauli, the surface has remarkable properties because broken symmetry in surface alters the material properties. In biological systems, the smallest functional and structural unit, which has a functional bulk space enclosed by a thin interface, is a cell. Cells contain inner cytosolic soup in which genetic information stored in DNA can be expressed through transcription (TX) and translation (TL). The exploration of cell-sized confinement has been recently investigated by using micron-scale droplets and microfluidic devices. In the first part of this review article, we describe recent developments of cell-free bioreactors where bacterial TX-TL machinery and DNA are encapsulated in these cell-sized compartments. Since synthetic biology and microfluidics meet toward the bottom-up assembly of cell-free bioreactors, the interplay between cellular geometry and TX-TL advances better control of biological structure and dynamics in vitro system. Furthermore, biological systems that show self-organization in confined space are not limited to a single cell, but are also involved in the collective behavior of motile cells, named active matter. In the second part, we describe recent studies where collectively ordered patterns of active matter, from bacterial suspensions to active cytoskeleton, are self-organized. Since geometry and topology are vital concepts to understand the ordered phase of active matter, a microfluidic device with designed compartments allows one to explore geometric principles behind self-organization across the molecular scale to cellular scale. Finally, we discuss the future perspectives of a microfluidic approach to explore the further understanding of biological systems from geometric and topological aspects.
Collapse
Affiliation(s)
- Kazusa Beppu
- Department of Physics, Kyushu University, Fukuoka 819-0395, Japan.
| | - Ziane Izri
- Department of Physics, Kyushu University, Fukuoka 819-0395, Japan.
| | - Yusuke T Maeda
- Department of Physics, Kyushu University, Fukuoka 819-0395, Japan.
| | - Ryota Sakamoto
- Department of Physics, Kyushu University, Fukuoka 819-0395, Japan.
| |
Collapse
|
15
|
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.
Collapse
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
| |
Collapse
|
16
|
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: 25] [Impact Index Per Article: 4.2] [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.
Collapse
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
| |
Collapse
|
17
|
Schoborg JA, Jewett MC. Cell-Free Protein Synthesis: An Emerging Technology for Understanding, Harnessing, and Expanding the Capabilities of Biological Systems. Synth Biol (Oxf) 2018. [DOI: 10.1002/9783527688104.ch15] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Jennifer A. Schoborg
- Department of Chemical and Biological Engineering; Northwestern University, 2145 Sheridan Road, Evanston, IL; 60208-3120 USA
- Chemistry of Life Processes Institute; 2170 Campus Drive, Evanston, IL; 60208-3120 USA
| | - Michael C. Jewett
- Department of Chemical and Biological Engineering; Northwestern University, 2145 Sheridan Road, Evanston, IL; 60208-3120 USA
- Chemistry of Life Processes Institute; 2170 Campus Drive, Evanston, IL; 60208-3120 USA
- Robert H. Lurie Comprehensive Cancer Center; Northwestern University, 676 N. St Clair St; Suite 1200 Chicago IL 60611-3068 USA
- Simpson Querrey Institute; Northwestern University; 303 E. Superior St; Suite 11-131, Chicago IL 60611-2875 USA
- Center for Synthetic Biology; Northwestern University, 2145 Sheridan Road; Evanston IL 60208-3120 USA
| |
Collapse
|
18
|
Karig DK, Bessling S, Thielen P, Zhang S, Wolfe J. Preservation of protein expression systems at elevated temperatures for portable therapeutic production. J R Soc Interface 2018; 14:rsif.2016.1039. [PMID: 28446704 PMCID: PMC5414909 DOI: 10.1098/rsif.2016.1039] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 04/04/2017] [Indexed: 12/23/2022] Open
Abstract
Many biotechnology capabilities are limited by stringent storage needs of reagents, largely prohibiting use outside of specialized laboratories. Focusing on a large class of protein-based biotechnology applications, we address this issue by developing a method for preserving cell-free protein expression systems for months above room temperature. Our approach realizes unprecedented long-term stability at elevated temperatures by leveraging the sugar alcohol trehalose, a simple, low-cost, open-air drying step, and strategic separation of reaction components during drying. The resulting preservation capacity enables efficient production of a wide range of on-demand proteins under adverse conditions, for instance during emergency outbreaks or in remote locations. To demonstrate application potential, we use cell-free reagents subjected to months of exposure at 37°C and atmospheric conditions to produce sufficient concentrations of a pyocin protein to kill Pseudomonas aeruginosa, a troublesome pathogen for traumatic and burn wound injuries. Our work makes possible new biotechnology applications that demand ruggedness and scalability.
Collapse
Affiliation(s)
- David K Karig
- Research and Exploratory Development Department, Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA .,Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Seneca Bessling
- Research and Exploratory Development Department, Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - Peter Thielen
- Research and Exploratory Development Department, Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - Sherry Zhang
- Research and Exploratory Development Department, Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - Joshua Wolfe
- Research and Exploratory Development Department, Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| |
Collapse
|
19
|
Cell-free protein synthesis in micro compartments: building a minimal cell from biobricks. N Biotechnol 2017; 39:199-205. [DOI: 10.1016/j.nbt.2017.06.014] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 05/10/2017] [Accepted: 06/30/2017] [Indexed: 12/16/2022]
|
20
|
Chizzolini F, Forlin M, Yeh Martín N, Berloffa G, Cecchi D, Mansy SS. Cell-Free Translation Is More Variable than Transcription. ACS Synth Biol 2017; 6:638-647. [PMID: 28100049 DOI: 10.1021/acssynbio.6b00250] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Although RNA synthesis can be reliably controlled with different T7 transcriptional promoters during cell-free gene expression with the PURE system, protein synthesis remains largely unaffected. To better control protein levels, we investigated a series of ribosome binding sites (RBSs). Although RBS strength did strongly affect protein synthesis, the RBS sequence could explain less than half of the variability of the data. Protein expression was found to depend on other factors besides the strength of the RBS, including the GC content of the coding sequence. The complexity of protein synthesis in comparison to RNA synthesis was observed by the higher degree of variability associated with protein expression. This variability was also observed in an E. coli cell extract-based system. However, the coefficient of variation was larger with E. coli RNA polymerase than with T7 RNA polymerase, consistent with the increased complexity of E. coli RNA polymerase.
Collapse
Affiliation(s)
- Fabio Chizzolini
- Center for Integrative Biology (CIBIO), University of Trento , via Sommarive 9, 38123 Povo TN, Italy
| | - Michele Forlin
- Center for Integrative Biology (CIBIO), University of Trento , via Sommarive 9, 38123 Povo TN, Italy
| | - Noël Yeh Martín
- Center for Integrative Biology (CIBIO), University of Trento , via Sommarive 9, 38123 Povo TN, Italy
| | - Giuliano Berloffa
- Center for Integrative Biology (CIBIO), University of Trento , via Sommarive 9, 38123 Povo TN, Italy
| | - Dario Cecchi
- Center for Integrative Biology (CIBIO), University of Trento , via Sommarive 9, 38123 Povo TN, Italy
| | - Sheref S Mansy
- Center for Integrative Biology (CIBIO), University of Trento , via Sommarive 9, 38123 Povo TN, Italy
| |
Collapse
|
21
|
Caveney PM, Norred SE, Chin CW, Boreyko JB, Razooky BS, Retterer ST, Collier CP, Simpson ML. Resource Sharing Controls Gene Expression Bursting. ACS Synth Biol 2017; 6:334-343. [PMID: 27690390 DOI: 10.1021/acssynbio.6b00189] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Episodic gene expression, with periods of high expression separated by periods of no expression, is a pervasive biological phenomenon. This bursty pattern of expression draws from a finite reservoir of expression machinery in a highly time variant way, i.e., requiring no resources most of the time but drawing heavily on them during short intense bursts, that intimately links expression bursting and resource sharing. Yet, most recent investigations have focused on specific molecular mechanisms intrinsic to the bursty behavior of individual genes, while little is known about the interplay between resource sharing and global expression bursting behavior. Here, we confine Escherichia coli cell extract in both cell-sized microfluidic chambers and lipid-based vesicles to explore how resource sharing influences expression bursting. Interestingly, expression burst size, but not burst frequency, is highly sensitive to the size of the shared transcription and translation resource pools. The intriguing implication of these results is that expression bursts are more readily amplified than initiated, suggesting that burst formation occurs through positive feedback or cooperativity. When extrapolated to prokaryotic cells, these results suggest that large translational bursts may be correlated with large transcriptional bursts. This correlation is supported by recently reported transcription and translation bursting studies in E. coli. The results reported here demonstrate a strong intimate link between global expression burst patterns and resource sharing, and they suggest that bursting plays an important role in optimizing the use of limited, shared expression resources.
Collapse
Affiliation(s)
- Patrick M. Caveney
- Bredesen
Center, University of Tennessee, Knoxville, Tennessee 37996-2010, United States
- Center
for Nanophase Materials Sciences, Oak Ridge National Laboratory, Bethel Valley Road, Oak Ridge, Tennessee 37831, United States
| | - S. Elizabeth Norred
- Bredesen
Center, University of Tennessee, Knoxville, Tennessee 37996-2010, United States
- Center
for Nanophase Materials Sciences, Oak Ridge National Laboratory, Bethel Valley Road, Oak Ridge, Tennessee 37831, United States
| | - Charles W. Chin
- Bredesen
Center, University of Tennessee, Knoxville, Tennessee 37996-2010, United States
- Center
for Nanophase Materials Sciences, Oak Ridge National Laboratory, Bethel Valley Road, Oak Ridge, Tennessee 37831, United States
| | - Jonathan B. Boreyko
- Bredesen
Center, University of Tennessee, Knoxville, Tennessee 37996-2010, United States
- Center
for Nanophase Materials Sciences, Oak Ridge National Laboratory, Bethel Valley Road, Oak Ridge, Tennessee 37831, United States
- Department
of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Brandon S. Razooky
- Center
for Nanophase Materials Sciences, Oak Ridge National Laboratory, Bethel Valley Road, Oak Ridge, Tennessee 37831, United States
- Laboratory
of Immune Cell Epigenetics and Signaling, The Rockefeller University, New
York, New York 10065, United States
| | - Scott T. Retterer
- Bredesen
Center, University of Tennessee, Knoxville, Tennessee 37996-2010, United States
- Center
for Nanophase Materials Sciences, Oak Ridge National Laboratory, Bethel Valley Road, Oak Ridge, Tennessee 37831, United States
- Biosciences
Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - C. Patrick Collier
- Center
for Nanophase Materials Sciences, Oak Ridge National Laboratory, Bethel Valley Road, Oak Ridge, Tennessee 37831, United States
| | - Michael L. Simpson
- Bredesen
Center, University of Tennessee, Knoxville, Tennessee 37996-2010, United States
- Center
for Nanophase Materials Sciences, Oak Ridge National Laboratory, Bethel Valley Road, Oak Ridge, Tennessee 37831, United States
- Joint
Institute
for Biological Sciences, University of Tennessee−Knoxville and Oak Ridge National Laboratory, Bethel Valley Road, Oak Ridge, Tennessee 37831, United States
| |
Collapse
|
22
|
Küchler A, Yoshimoto M, Luginbühl S, Mavelli F, Walde P. Enzymatic reactions in confined environments. NATURE NANOTECHNOLOGY 2016; 11:409-20. [PMID: 27146955 DOI: 10.1038/nnano.2016.54] [Citation(s) in RCA: 473] [Impact Index Per Article: 59.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 03/04/2016] [Indexed: 05/17/2023]
Abstract
Within each biological cell, surface- and volume-confined enzymes control a highly complex network of chemical reactions. These reactions are efficient, timely, and spatially defined. Efforts to transfer such appealing features to in vitro systems have led to several successful examples of chemical reactions catalysed by isolated and immobilized enzymes. In most cases, these enzymes are either bound or adsorbed to an insoluble support, physically trapped in a macromolecular network, or encapsulated within compartments. Advanced applications of enzymatic cascade reactions with immobilized enzymes include enzymatic fuel cells and enzymatic nanoreactors, both for in vitro and possible in vivo applications. In this Review, we discuss some of the general principles of enzymatic reactions confined on surfaces, at interfaces, and inside small volumes. We also highlight the similarities and differences between the in vivo and in vitro cases and attempt to critically evaluate some of the necessary future steps to improve our fundamental understanding of these systems.
Collapse
Affiliation(s)
- Andreas Küchler
- Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, CH-8093 Zürich, Switzerland
| | - Makoto Yoshimoto
- Department of Applied Molecular Bioscience, Yamaguchi University, Tokiwadai 2-16-1, Ube 755-8611, Japan
| | - Sandra Luginbühl
- Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, CH-8093 Zürich, Switzerland
| | - Fabio Mavelli
- Chemistry Department, University 'Aldo Moro', Via Orabona 4, 70125 Bari, Italy
| | - Peter Walde
- Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, CH-8093 Zürich, Switzerland
| |
Collapse
|
23
|
Abstract
There is a growing need to enhance our capabilities in medical and environmental diagnostics. Synthetic biologists have begun to focus their biomolecular engineering approaches toward this goal, offering promising results that could lead to the development of new classes of inexpensive, rapidly deployable diagnostics. Many conventional diagnostics rely on antibody-based platforms that, although exquisitely sensitive, are slow and costly to generate and cannot readily confront rapidly emerging pathogens or be applied to orphan diseases. Synthetic biology, with its rational and short design-to-production cycles, has the potential to overcome many of these limitations. Synthetic biology devices, such as engineered gene circuits, bring new capabilities to molecular diagnostics, expanding the molecular detection palette, creating dynamic sensors, and untethering reactions from laboratory equipment. The field is also beginning to move toward in vivo diagnostics, which could provide near real-time surveillance of multiple pathological conditions. Here, we describe current efforts in synthetic biology, focusing on the translation of promising technologies into pragmatic diagnostic tools and platforms.
Collapse
|
24
|
Hansen MMK, Meijer LHH, Spruijt E, Maas RJM, Rosquelles MV, Groen J, Heus HA, Huck WTS. Macromolecular crowding creates heterogeneous environments of gene expression in picolitre droplets. NATURE NANOTECHNOLOGY 2016; 11:191-7. [PMID: 26501750 PMCID: PMC4740931 DOI: 10.1038/nnano.2015.243] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 09/15/2015] [Indexed: 05/02/2023]
Abstract
Understanding the dynamics of complex enzymatic reactions in highly crowded small volumes is crucial for the development of synthetic minimal cells. Compartmentalized biochemical reactions in cell-sized containers exhibit a degree of randomness due to the small number of molecules involved. However, it is unknown how the physical environment contributes to the stochastic nature of multistep enzymatic processes. Here, we present a robust method to quantify gene expression noise in vitro using droplet microfluidics. We study the changes in stochasticity in the cell-free gene expression of two genes compartmentalized within droplets as a function of DNA copy number and macromolecular crowding. We find that decreased diffusion caused by a crowded environment leads to the spontaneous formation of heterogeneous microenvironments of mRNA as local production rates exceed the diffusion rates of macromolecules. This heterogeneity leads to a higher probability of the molecular machinery staying in the same microenvironment, directly increasing the system's stochasticity.
Collapse
Affiliation(s)
- Maike M K Hansen
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Lenny H H Meijer
- Eindhoven University of Technology, Institute for Complex Molecular Systems and Computational Biology Group, Eindhoven 5600 MB, The Netherlands
| | - Evan Spruijt
- ESPCI ParisTech, Laboratoire de Physique et Mécanique des Milieux Hétérogènes, UMR 7636 du CNRS, Paris 75005, France
| | - Roel J M Maas
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Marta Ventosa Rosquelles
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Joost Groen
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Hans A Heus
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Wilhelm T S Huck
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| |
Collapse
|
25
|
Abstract
Protein noise measurements are increasingly used to elucidate biophysical parameters. Unfortunately noise analyses are often at odds with directly measured parameters. Here we show that these inconsistencies arise from two problematic analytical choices: (i) the assumption that protein translation rate is invariant for different proteins of different abundances, which has inadvertently led to (ii) the assumption that a large constitutive extrinsic noise sets the low noise limit in gene expression. While growing evidence suggests that transcriptional bursting may set the low noise limit, variability in translational bursting has been largely ignored. We show that genome-wide systematic variation in translational efficiency can–and in the case of E. coli does–control the low noise limit in gene expression. Therefore constitutive extrinsic noise is small and only plays a role in the absence of a systematic variation in translational efficiency. These results show the existence of two distinct expression noise patterns: (1) a global noise floor uniformly imposed on all genes by expression bursting; and (2) high noise distributed to only a select group of genes.
Collapse
|
26
|
Nishimura K, Tsuru S, Suzuki H, Yomo T. Stochasticity in gene expression in a cell-sized compartment. ACS Synth Biol 2015; 4:566-76. [PMID: 25280237 DOI: 10.1021/sb500249g] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The gene expression in a clonal cell population fluctuates significantly, and its relevance to various cellular functions is under intensive debate. A fundamental question is whether the fluctuation is a consequence of the complexity and redundancy in living cells or an inevitable attribute of the minute microreactor nature of cells. To answer this question, we constructed an artificial cell, which consists of only necessary components for the gene expression (in vitro transcription and translation system) and its boundary as a microreactor (cell-sized lipid vesicle), and investigated the gene expression noise. The variation in the expression of two fluorescent proteins was decomposed into the components that were correlated and uncorrelated between the two proteins using a method similar to the one used by Elowitz and co-workers to analyze the expression noise in E. coli. The observed fluctuation was compared with a theoretical model that expresses the amplitude of noise as a function of the average number of intermediate molecules and products. With the assumption that the transcripts are partly active, the theoretical model was able to well describe the noise in the artificial system. Furthermore, the same measurement for E. coli cells harboring an identical plasmid revealed that the E. coli exhibited a similar level of expression noise. Our results demonstrated that the level of fluctuation found in bacterial cells is mostly an intrinsic property that arises even in a primitive form of the cell.
Collapse
Affiliation(s)
- Kazuya Nishimura
- Department
of Bioinformatic Engineering, Graduate School of Information Science
and Technology, Osaka University, Yamadaoka 1-5, Suita, Osaka 565-0871, Japan
- Quantitative Biology
Center (QBiC), Riken, Fuedai 6-2-3, Suita, Osaka 565-0874, Japan
| | - Saburo Tsuru
- Department
of Bioinformatic Engineering, Graduate School of Information Science
and Technology, Osaka University, Yamadaoka 1-5, Suita, Osaka 565-0871, Japan
| | - Hiroaki Suzuki
- Faculty
of Science and Engineering, Chuo University, Kasuga 1-13-27, Bunkyo-ku, Tokyo 112-8551, Japan
- Exploratory
Research for Advanced Technology (ERATO), Japan Science and Technology Agency, Yamadaoka 1-5, Suita, Osaka 565-0871, Japan
| | - Tetsuya Yomo
- Department
of Bioinformatic Engineering, Graduate School of Information Science
and Technology, Osaka University, Yamadaoka 1-5, Suita, Osaka 565-0871, Japan
- Exploratory
Research for Advanced Technology (ERATO), Japan Science and Technology Agency, Yamadaoka 1-5, Suita, Osaka 565-0871, Japan
- Department
of Frontier Biosciences, Graduate School of Frontier Biosciences, Osaka University, Yamadaoka 1-5, Suita, Osaka 565-0871, Japan
| |
Collapse
|
27
|
Norred SE, Caveney PM, Retterer ST, Boreyko JB, Fowlkes JD, Collier CP, Simpson ML. Sealable femtoliter chamber arrays for cell-free biology. J Vis Exp 2015:52616. [PMID: 25867144 PMCID: PMC4401254 DOI: 10.3791/52616] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Cell-free systems provide a flexible platform for probing specific networks of biological reactions isolated from the complex resource sharing (e.g., global gene expression, cell division) encountered within living cells. However, such systems, used in conventional macro-scale bulk reactors, often fail to exhibit the dynamic behaviors and efficiencies characteristic of their living micro-scale counterparts. Understanding the impact of internal cell structure and scale on reaction dynamics is crucial to understanding complex gene networks. Here we report a microfabricated device that confines cell-free reactions in cellular scale volumes while allowing flexible characterization of the enclosed molecular system. This multilayered poly(dimethylsiloxane) (PDMS) device contains femtoliter-scale reaction chambers on an elastomeric membrane which can be actuated (open and closed). When actuated, the chambers confine Cell-Free Protein Synthesis (CFPS) reactions expressing a fluorescent protein, allowing for the visualization of the reaction kinetics over time using time-lapse fluorescent microscopy. Here we demonstrate how this device may be used to measure the noise structure of CFPS reactions in a manner that is directly analogous to those used to characterize cellular systems, thereby enabling the use of noise biology techniques used in cellular systems to characterize CFPS gene circuits and their interactions with the cell-free environment.
Collapse
Affiliation(s)
- Sarah Elizabeth Norred
- Bredesen Center, University of Tennessee, Knoxville; Center for Nanophase Materials Sciences, Oak Ridge National Laboratory
| | - Patrick M Caveney
- Bredesen Center, University of Tennessee, Knoxville; Center for Nanophase Materials Sciences, Oak Ridge National Laboratory
| | - Scott T Retterer
- Bredesen Center, University of Tennessee, Knoxville; Center for Nanophase Materials Sciences, Oak Ridge National Laboratory
| | - Jonathan B Boreyko
- Bredesen Center, University of Tennessee, Knoxville; Center for Nanophase Materials Sciences, Oak Ridge National Laboratory
| | - Jason D Fowlkes
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory; Department of Materials Science and Engineering, University of Tennessee, Knoxville
| | | | - Michael L Simpson
- Bredesen Center, University of Tennessee, Knoxville; Center for Nanophase Materials Sciences, Oak Ridge National Laboratory; Department of Materials Science and Engineering, University of Tennessee, Knoxville;
| |
Collapse
|
28
|
Lewis DD, Villarreal FD, Wu F, Tan C. Synthetic biology outside the cell: linking computational tools to cell-free systems. Front Bioeng Biotechnol 2014; 2:66. [PMID: 25538941 PMCID: PMC4260521 DOI: 10.3389/fbioe.2014.00066] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 11/23/2014] [Indexed: 12/22/2022] Open
Abstract
As mathematical models become more commonly integrated into the study of biology, a common language for describing biological processes is manifesting. Many tools have emerged for the simulation of in vivo synthetic biological systems, with only a few examples of prominent work done on predicting the dynamics of cell-free synthetic systems. At the same time, experimental biologists have begun to study dynamics of in vitro systems encapsulated by amphiphilic molecules, opening the door for the development of a new generation of biomimetic systems. In this review, we explore both in vivo and in vitro models of biochemical networks with a special focus on tools that could be applied to the construction of cell-free expression systems. We believe that quantitative studies of complex cellular mechanisms and pathways in synthetic systems can yield important insights into what makes cells different from conventional chemical systems.
Collapse
Affiliation(s)
- Daniel D. Lewis
- Integrative Genetics and Genomics, University of California Davis, Davis, CA, USA
- Department of Biomedical Engineering, University of California Davis, Davis, CA, USA
| | | | - Fan Wu
- Department of Biomedical Engineering, University of California Davis, Davis, CA, USA
| | - Cheemeng Tan
- Department of Biomedical Engineering, University of California Davis, Davis, CA, USA
| |
Collapse
|
29
|
Brophy JAN, Voigt CA. Principles of genetic circuit design. Nat Methods 2014; 11:508-20. [PMID: 24781324 DOI: 10.1038/nmeth.2926] [Citation(s) in RCA: 584] [Impact Index Per Article: 58.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 03/18/2014] [Indexed: 12/17/2022]
Abstract
Cells navigate environments, communicate and build complex patterns by initiating gene expression in response to specific signals. Engineers seek to harness this capability to program cells to perform tasks or create chemicals and materials that match the complexity seen in nature. This Review describes new tools that aid the construction of genetic circuits. Circuit dynamics can be influenced by the choice of regulators and changed with expression 'tuning knobs'. We collate the failure modes encountered when assembling circuits, quantify their impact on performance and review mitigation efforts. Finally, we discuss the constraints that arise from circuits having to operate within a living cell. Collectively, better tools, well-characterized parts and a comprehensive understanding of how to compose circuits are leading to a breakthrough in the ability to program living cells for advanced applications, from living therapeutics to the atomic manufacturing of functional materials.
Collapse
Affiliation(s)
- Jennifer A N Brophy
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Christopher A Voigt
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| |
Collapse
|
30
|
Smith MT, Wilding KM, Hunt JM, Bennett AM, Bundy BC. The emerging age of cell-free synthetic biology. FEBS Lett 2014; 588:2755-61. [PMID: 24931378 DOI: 10.1016/j.febslet.2014.05.062] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Revised: 05/29/2014] [Accepted: 05/30/2014] [Indexed: 01/16/2023]
Abstract
The engineering of and mastery over biological parts has catalyzed the emergence of synthetic biology. This field has grown exponentially in the past decade. As increasingly more applications of synthetic biology are pursued, more challenges are encountered, such as delivering genetic material into cells and optimizing genetic circuits in vivo. An in vitro or cell-free approach to synthetic biology simplifies and avoids many of the pitfalls of in vivo synthetic biology. In this review, we describe some of the innate features that make cell-free systems compelling platforms for synthetic biology and discuss emerging improvements of cell-free technologies. We also select and highlight recent and emerging applications of cell-free synthetic biology.
Collapse
Affiliation(s)
- Mark Thomas Smith
- Department of Chemical Engineering, Brigham Young University, Provo, UT, USA
| | - Kristen M Wilding
- Department of Chemical Engineering, Brigham Young University, Provo, UT, USA
| | - Jeremy M Hunt
- Department of Chemical Engineering, Brigham Young University, Provo, UT, USA
| | - Anthony M Bennett
- Department of Chemical Engineering, Brigham Young University, Provo, UT, USA
| | - Bradley C Bundy
- Department of Chemical Engineering, Brigham Young University, Provo, UT, USA.
| |
Collapse
|
31
|
Wu F, Tan C. The engineering of artificial cellular nanosystems using synthetic biology approaches. WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY 2014; 6:369-83. [PMID: 24668724 DOI: 10.1002/wnan.1265] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Revised: 02/05/2014] [Accepted: 02/08/2014] [Indexed: 12/26/2022]
Abstract
Artificial cellular systems are minimal systems that mimic certain properties of natural cells, including signaling pathways, membranes, and metabolic pathways. These artificial cells (or protocells) can be constructed following a synthetic biology approach by assembling biomembranes, synthetic gene circuits, and cell-free expression systems. As artificial cells are built from bottom-up using minimal and a defined number of components, they are more amenable to predictive mathematical modeling and engineered controls when compared with natural cells. Indeed, artificial cells have been implemented as drug delivery machineries and in situ protein expression systems. Furthermore, artificial cells have been used as biomimetic systems to unveil new insights into functions of natural cells, which are otherwise difficult to investigate owing to their inherent complexity. It is our vision that the development of artificial cells would bring forth parallel advancements in synthetic biology, cell-free systems, and in vitro systems biology. For further resources related to this article, please visit the WIREs website. Conflict of interests: The authors declare that they have no competing financial interests.
Collapse
Affiliation(s)
- Fan Wu
- Department of Biomedical Engineering, University of California Davis, Davis, CA, USA
| | | |
Collapse
|
32
|
Abstract
Living cells maintain a steady state of biochemical reaction rates by exchanging energy and matter with the environment. These exchanges usually do not occur in in vitro systems, which consequently go to chemical equilibrium. This in turn has severely constrained the complexity of biological networks that can be implemented in vitro. We developed nanoliter-scale microfluidic reactors that exchange reagents at dilution rates matching those of dividing bacteria. In these reactors we achieved transcription and translation at steady state for 30 h and implemented diverse regulatory mechanisms on the transcriptional, translational, and posttranslational levels, including RNA polymerases, transcriptional repression, translational activation, and proteolysis. We constructed and implemented an in vitro genetic oscillator and mapped its phase diagram showing that steady-state conditions were necessary to produce oscillations. This reactor-based approach will allow testing of whether fundamental limits exist to in vitro network complexity.
Collapse
|