This work was funded by the National Institute of General Medical Sciences 1U01GM110714-01 and Department of Energy DE-FG02-02ER63445. The authors would like to thank Dr. Richard Kohman, Dr. Jenny Tam, and Dr. Edgar Goluch for helpful advice on constructing the protocol section of this manuscript.

<ol>
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L., D&#237;az, E., Carmona, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Speeding+up+bioproduction+of+selenium+nanoparticles+by+using+Vibrio+natriegens+as+microbial+factory.">Speeding up bioproduction of selenium nanoparticles by using Vibrio natriegens as microbial factory.</a> Scientific Reports. 7 (1), 16046 (2017).</li><li>Aiyar, S. E., Gaal, T., Gourse, R. 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Coli RNA polymerase and sigma factor 70.</a> Journal of Biological Engineering. 4, 8 (2010).</li><li>Sitaraman, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+cell-free+protein+synthesis+system.">A novel cell-free protein synthesis system.</a> Journal of Biotechnology. 110 (3), 257-263 (2004).</li><li>Sun, Z. Z., Yeung, E., Hayes, C. A., Noireaux, V., Murray, R. 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DJW, NO, and GMC have filed a patent related to this work.

This protocol has been optimized for wild-type V. natriegens and bacterial growth media comprised of LB supplemented with V2 salts (Table of Materials). Other strains of V. natriegens can be similarly cultured to generate crude cell extracts for cell-free reactions; however, their use requires additional optimization of this protocol. Additionally, this cell-free protein expression system has been optimized using 3-phosphoglyceric acid (3-PGA) as the primary energy regeneration source. Other energy regeneration sources may be used; however, optimization of reagents and calibration will likely be required to obtain high yielding protein expression10,11.
Specific attention to several critical steps in this protocol will ensure maximal extract productivity for high-yielding cell-free protein production. First, crude cell extract must be prepared from V. natriegens cell cultures harvested in a mid-exponential phase of growth; protein yield is maximal when cultures reach an OD600 = 1.0 &#177; 0.2. While cell-free protein production is possible from cells harvested at a range of optical densities, we have previously found that cells harvested in an exponential state of growth yield significantly more protein9. The observed effects of optical density on crude cell extract performance are consistent with those reported for other cell-free expression systems derived from cells grown in batch culture conditions1. Because V. natriegens grows at a rapid rate, it is critical to closely monitor cultures&#8217; optical densities. In general, it is expected that V. natriegens cultures should reproducibly reach an OD600 of 1.0 within 1&#8722;1.5 h using this protocol; however, individual growth conditions such as the use of baffled versus non-baffled flasks, which affects aeration, or air versus water incubation, which affects the rate and stability of incubation temperature, may alter growth time. Furthermore, it is generally recommended to culture at least 250 mL of V. natriegens in a 1 L baffled flask to ensure a large cell pellet at harvest for easy manipulation and transfer. This greatly improves the success of crude cell extract preparation as well as increases the total volume of extract produced from a pellet. When using smaller scale preparation, culture conditions and reagents can be adjusted appropriately. For large-scale fermentation, further optimization of culture conditions may be required. Finally, to ensure high protein yield, it is critical that cell pellets are processed immediately after harvesting, or within 1&#8722;2 days of storing at -80 &#176;C.
The proper lysis of the cell pellet by pulse sonication is critical to the success of cell-free protein expression and is often the most difficult aspect of this protocol for new users. Typically, a well lysed pellet will yield a significant volume of liquid extract that is free of debris. The extract should be slightly viscous but can be easily pipetted when aliquoting into storage tubes before flash freezing in liquid nitrogen. Figure 3 depicts a representation of a well lysed pellet (Figure 3A) in comparison to a poorly lysed pellet (Figure 3B) after the post lysis centrifugation step. A major indication of complete cell lysis is a crude cell extract total protein concentration &#62; 20 mg/mL as determined by a total protein assay (step 2.13). Over-sonication or excessive heating of the crude cell extract will damage the cellular machinery, which cannot be determined without performing a cell-free reaction. Thus, it is highly beneficial to test extract efficiency with a control reaction before dedicating significant time and effort to downstream protein expression applications. While additional optimization may be necessary for different sonication equipment, the pulse sonication steps described have been highly reproducible in our hands.
The use of linear DNA template derived from PCR amplification, restriction enzyme digest, or commercial gene synthesis can significantly increase the capacity for high-throughput and rapid protein production in cell-free expression systems24. While protein production from PCR amplified linear template has been demonstrated, the yield of these reactions are approximately 13.5-fold lower compared to reactions using plasmid DNA template at equimolar ratios9. This is primarily due to the instability of the linear DNA template which is likely degraded by endogenous nucleases present in V. natriegens crude cell extract. While lambda phage protein GamS has been previously used to protect Linear DNA template24,25, it was found to be incompatible with V. natriegens extracts9. Additionally, while increasing the concentration of linear DNA template may allow for a higher protein yield, its fast degradation in crude cell extract will still be a major problem.
A solution to overcoming linear DNA template degradation may be to supplement cell-free reactions with mRNA template generated from in vitro transcription of linear DNA. On the other hand, the use of an RNase inhibitor offers significant protection against mRNA transcript degradation and appreciable protein yields can be obtained in the 10 &#956;L cell-free reaction format (Figure 5A,B). Cloning of linear DNA into a circular template through TA ligation, TOPO cloning, Golden Gate assembly, or other recombination methods may be used to circumvent template degradation. Nevertheless, further approaches for inhibition of nuclease activity will be necessary for efficient protein expression using linear DNA template.
To date, several different approaches have been proposed for preparation of crude extract for cell-free protein expression9,10,11,26. In developing this protocol, we sought to maximize user accessibility, reduce overall cost, and minimize time-consuming steps. For example, a high protein yield is achieved using a simple two-step sonication-centrifugation process, and does not require cell homogenizers, lengthy dialysis steps or run-off reaction. It is simple to execute in a short period of time and does not require high level of laboratory expertise. Thus, it can help facilitate cell-free expression as a standard for translational academic research and industrial process design.
This protocol expands the toolkit available for investigation and utility of V. natriegens, a non-model organism with unique biological properties. Higher protein yield can be achieved by employing semi- or fully-continuous cell-free reactions, to allow for energy regeneration, resupplying of amino acids, and the removal of waste products3,5,27. Furthermore, the engineering of wild-type V. natriegens to produce DNAse- or RNAse-deficient strains, removal of deleterious and competing metabolic pathways, and expression of additional tRNAs could greatly enhance the production of proteins in this system28,29. As we unravel the biology underlying its rapid growth, further development of V. natriegens cell-free systems may accelerate bioproduction capabilities and enable robust expression of therapeutic peptides, small molecules, and synthetic materials.

Cell-free protein synthesis is a versatile and cost-effective method for the expression of valuable proteins or peptides1,2,3,4. Historically, cell-free protein synthesis has been performed using Escherichia coli expression systems; however, there has been a recent surge in using alternative, non-model organisms with novel properties as chassis for cell-free expression5,6,7,8,9,10,11,12. Organisms with unique metabolic profiles are prime candidates as alternatives to E. coli cell-free systems. For example, the marine bacterium Vibrio natriegens is the fastest growing of all known organisms with an observed doubling time of less than 10 min13. This has garnered V. natriegens considerable attention as an emerging microbial host for research and biotechnology14,15,16,17,18. Given that the rapid growth rate of V. natriegens has been linked to high rates of protein synthesis and metabolic efficiency19,20,21, harnessing its cellular machinery for cell-free synthesis may significantly expand the toolkit for rapid protein production and high-throughput screening.
Recently, a cell-free V. natriegens expression system has been demonstrated which is capable of producing super folder GFP (sfGFP) at concentrations of &#62; 260 &#956;g/mL in 3 h with a T7 promoter9. The overall aim of developing this method was to provide users with a highly accessible, cost-efficient, reproducible, and high-yielding cell-free protein expression system that can be prepared using common lab equipment in a short amount of time. This protocol utilizes 1 L cultures in shake flasks, cell lysis by pulse sonication, and small-scale batch reactions in a 96- or 384-well format to maximize parallelization and screening throughput. A long, sustained protein expression is made possible by supplementation of 3-phosphoglyceric acid (3-PGA) as an energy source8,22,23. Upon successfully completing this protocol, a user will have the capability to express a desired protein or set of proteins in a cell-free format using V. natriegens crude cell extract.
Starting from a glycerol stock, V. natriegens crude cell extracts are prepared from cells harvested at an optical density at 600 nm (OD600) of 1.0. A 1 L culture will yield approximately 2&#8722;3 mL of extract, which is sufficient for more than 800 cell-free reactions at 25% crude cell extract. Proteins can be expressed using plasmid DNA, linear DNA, or mRNA template; however, linear DNA template degradation by endogenous nucleases remains a major drawback when using wild type V. natriegens cell-free system9. Starting from V. natriegens cultures, protein useable for downstream applications can be achieved by a single user in 1&#8722;2 full days.

<table>
	<tbody>
		<tr>
			<td>15 mL Tubes</td>
			<td>Corning</td>
			<td>352196</td>
			<td></td>
		</tr>
		<tr>
			<td>2 mL Tubes</td>
			<td>Eppendorf</td>
			<td>22363352</td>
			<td></td>
		</tr>
		<tr>
			<td>384-well Black Assay Plates</td>
			<td>Corning</td>
			<td>3544</td>
			<td></td>
		</tr>
		<tr>
			<td>384-well PCR Plates</td>
			<td>Eppendorf</td>
			<td>951020702</td>
			<td></td>
		</tr>
		<tr>
			<td>50 mL Tubes</td>
			<td>Corning</td>
			<td>352070</td>
			<td></td>
		</tr>
		<tr>
			<td>96-well PCR Plates</td>
			<td>Eppendorf</td>
			<td>30129300</td>
			<td></td>
		</tr>
		<tr>
			<td>Adenosine 3&#39;,5&#39;-cyclic monophosphate sodium salt monohydrate</td>
			<td>Sigma</td>
			<td>A6885</td>
			<td></td>
		</tr>
		<tr>
			<td>Adenosine 5&#39;-triphosphate - 100 mM</td>
			<td>NEB</td>
			<td>N0450L</td>
			<td></td>
		</tr>
		<tr>
			<td>Applied Biosystems Veriti 384-well Thermocycler</td>
			<td>ThermoFisher</td>
			<td>4388444</td>
			<td></td>
		</tr>
		<tr>
			<td>Assay Plate Adhesives</td>
			<td>BioRad</td>
			<td>MSB1001</td>
			<td></td>
		</tr>
		<tr>
			<td>&#946;-Nicotinamide adenine dinucleotide hydrate (NAD)</td>
			<td>Sigma/Roche</td>
			<td>10127965001</td>
			<td></td>
		</tr>
		<tr>
			<td>Coenzyme A hydrate</td>
			<td>Sigma</td>
			<td>C4283</td>
			<td></td>
		</tr>
		<tr>
			<td>Cytidine 5&#39;-triphosphate - 100 mM</td>
			<td>NEB</td>
			<td>N0450L</td>
			<td></td>
		</tr>
		<tr>
			<td>D-(-)-3-Phosphoglyceric acid disodium salt (3-PGA)</td>
			<td>Sigma</td>
			<td>P8877</td>
			<td></td>
		</tr>
		<tr>
			<td>Dewar Flask - 4L</td>
			<td>ThermoScientific</td>
			<td>10-194-100C</td>
			<td></td>
		</tr>
		<tr>
			<td>DL-Dithiothreitol solution - 1 M</td>
			<td>Sigma</td>
			<td>42816</td>
			<td></td>
		</tr>
		<tr>
			<td>Folinic acid calcium salt hydrate</td>
			<td>Sigma</td>
			<td>47612</td>
			<td></td>
		</tr>
		<tr>
			<td>Glacial Acetic Acid</td>
			<td>Sigma</td>
			<td>A6283</td>
			<td></td>
		</tr>
		<tr>
			<td>Guanosine 5&#39;-triphosphate - 100 mM</td>
			<td>NEB</td>
			<td>N0450L</td>
			<td></td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>Sigma</td>
			<td>H3375</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Glutamic acid hemimagnesium salt tetrahydrate</td>
			<td>Sigma</td>
			<td>49605</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Glutamic acid potassium salt monohydrate</td>
			<td>Sigma</td>
			<td>G1149</td>
			<td></td>
		</tr>
		<tr>
			<td>LB Broth (Miller)</td>
			<td>Sigma</td>
			<td>L3522</td>
			<td></td>
		</tr>
		<tr>
			<td>Magnesium chloride (MgCl2)</td>
			<td>Sigma</td>
			<td>M8266</td>
			<td></td>
		</tr>
		<tr>
			<td>Plasmid pJL1-sfGFP</td>
			<td>Addgene</td>
			<td>69496</td>
			<td></td>
		</tr>
		<tr>
			<td>Plasmid Plus Maxi kit</td>
			<td>Qiagen</td>
			<td>12963</td>
			<td></td>
		</tr>
		<tr>
			<td>Poly(ethylene glycol) (PEG)-8000</td>
			<td>Sigma</td>
			<td>89510</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium chloride (KCl)</td>
			<td>Sigma</td>
			<td>P9333</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium hydroxide Pellets</td>
			<td>Sigma/Roche</td>
			<td>1050121000</td>
			<td></td>
		</tr>
		<tr>
			<td>Q125 Sonicator and CL-18 probe with a &#8539;-inch tip</td>
			<td>Qsonica</td>
			<td>4422</td>
			<td></td>
		</tr>
		<tr>
			<td>RNA Clean and Concentrator Kit</td>
			<td>Zymo</td>
			<td>R1013</td>
			<td></td>
		</tr>
		<tr>
			<td>RNase Inhibitor, Murine</td>
			<td>NEB</td>
			<td>M0314</td>
			<td></td>
		</tr>
		<tr>
			<td>RTS Amino Acid Sampler</td>
			<td>Biotechrabbit</td>
			<td>BR1401801</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium chloride (NaCl)</td>
			<td>Sigma</td>
			<td>S7653</td>
			<td></td>
		</tr>
		<tr>
			<td>Spermidine</td>
			<td>Sigma</td>
			<td>S0266</td>
			<td></td>
		</tr>
		<tr>
			<td>T7 RNA Polymerase</td>
			<td>NEB</td>
			<td>M0251</td>
			<td></td>
		</tr>
		<tr>
			<td>Tris Solution (pH 8.0) - 1 M</td>
			<td>Invitrogen</td>
			<td>AM9856</td>
			<td></td>
		</tr>
		<tr>
			<td>tRNA from E. coli MRE 600</td>
			<td>Sigma/Roche</td>
			<td>10109541001</td>
			<td></td>
		</tr>
		<tr>
			<td>Uridine 5&#39;-triphosphate - 100 mM</td>
			<td>NEB</td>
			<td>N0450L</td>
			<td></td>
		</tr>
		<tr>
			<td>Vibrio natriegens (Wild-type) Lyophilized Stock</td>
			<td>ATCC</td>
			<td>14048</td>
			<td></td>
		</tr>
	</tbody>
</table>

cell-free protein expression using the rapidly growing bacterium vibrio natriegens

The marine bacterium Vibrio natriegens has garnered considerable attention as an emerging microbial host for biotechnology due to its fast growth rate. A general protocol is described for the preparation of V. natriegens crude cell extracts using common laboratory equipment. This high yielding protocol has been specifically optimized for user accessibility and reduced cost. Cell-free protein synthesis (CFPS) can be carried out in small scale 10 &#956;L batch reactions in either a 96- or 384-well format and reproducibly yields concentrations of &#62; 260 &#956;g/mL super folder GFP (sfGFP) within 3 h. Overall, crude cell extract preparation and CFPS can be achieved in 1&#8722;2 full days by a single user. This protocol can be easily integrated into existing protein synthesis pipelines to facilitate advances in bio-production and synthetic biology applications.

Watch this Scientific Journal Video about Cell-free Protein Expression Using the Rapidly Growing Bacterium Vibrio natriegens at JoVE.com

Cell-free Protein Expression Using the Rapidly Growing Bacterium Vibrio natriegens

Cell-free expression systems are powerful and cost-efficient tools for the high-throughput synthesis and screening of important proteins. Here, we describe the preparation of cell-free protein expression system using Vibrio natriegens for the rapid protein production using plasmid DNA, linear DNA, and mRNA template.

Cell-free Protein Expression Using the Rapidly Growing Bacterium Vibrio natriegens

The marine bacterium Vibrio natriegens has garnered considerable attention as an emerging microbial host for biotechnology due to its fast growth rate. A ...

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Research

JoVE Journal

Bioengineering

17.2K Views.  Harvard Medical School. Cell-free expression systems are powerful and cost-efficient tools for the high-throughput synthesis and screening of important proteins. Here, we describe the preparation of cell-free protein expression system using Vibrio natriegens for the rapid protein production using plasmid DNA, linear DNA, and mRNA template.

Video: Cell-free Protein Expression Using the Rapidly Growing Bacterium Vibrio natriegens

High-throughput Protein Expression Generator Using a Microfluidic Platform

Rapidly increasing fields, such as systems biology, require the development and implementation of new technologies, enabling high-throughput and high-fidelity measurements of large systems. Microfluidics promises to fulfill many of these requirements, such as performing high-throughput screening experiments on-chip, encompassing biochemical, biophysical, and cell-based assays1. Since the early days of microfluidics devices, this field has drastically evolved, leading to the development of microfluidic large-scale integration2,3. This technology allows for the integration of thousands of micromechanical valves on a single device with a postage-sized footprint (Figure 1). We have developed a high-throughput microfluidic platform for generating in vitro expression of protein arrays (Figure 2) named PING (Protein Interaction Network Generator). These arrays can serve as a template for many experiments such as protein-protein 4, protein-RNA5 or protein-DNA6 interactions.
The device consist of thousands of reaction chambers, which are individually programmed using a microarrayer. Aligning of these printed microarrays to microfluidics devices programs each chamber with a single spot eliminating potential contamination or cross-reactivity Moreover, generating microarrays using standard microarray spotting techniques is also very modular, allowing for the arraying of proteins7, DNA8, small molecules, and even colloidal suspensions. The potential impact of microfluidics on biological sciences is significant. A number of microfluidics based assays have already provided novel insights into the structure and function of biological systems, and the field of microfluidics will continue to impact biology.

We present a microfluidic approach for the expression of protein arrays. The device consists of thousands of reaction chambers controlled by micro-mechanical valves. The microfluidic device is mated to a microarray-printed gene library. These genes are then transcribed and translated on-chip, resulting in a protein array ready for experimental use.

Rapidly increasing fields, such as systems biology, require the development and implementation of new technologies, enabling high-throughput and ...

Characterization of Complex Systems Using the Design of Experiments Approach: Transient Protein Expression in Tobacco as a Case Study

Plants provide multiple benefits for the production of biopharmaceuticals including low costs, scalability, and safety. Transient expression offers the additional advantage of short development and production times, but expression levels can vary significantly between batches thus giving rise to regulatory concerns in the context of good manufacturing practice. We used a design of experiments (DoE) approach to determine the impact of major factors such as regulatory elements in the expression construct, plant growth and development parameters, and the incubation conditions during expression, on the variability of expression between batches. We tested plants expressing a model anti-HIV monoclonal antibody (2G12) and a fluorescent marker protein (DsRed). We discuss the rationale for selecting certain properties of the model and identify its potential limitations. The general approach can easily be transferred to other problems because the principles of the model are broadly applicable: knowledge-based parameter selection, complexity reduction by splitting the initial problem into smaller modules, software-guided setup of optimal experiment combinations and step-wise design augmentation. Therefore, the methodology is not only useful for characterizing protein expression in plants but also for the investigation of other complex systems lacking a mechanistic description. The predictive equations describing the interconnectivity between parameters can be used to establish mechanistic models for other complex systems.

We describe a design of experiments approach that can be used to determine and model the influence of transgene regulatory elements, plant growth and development parameters, and incubation conditions on the transient expression of monoclonal antibodies and reporter proteins in plants.

Plants provide multiple benefits for the production of biopharmaceuticals including low costs, scalability, and safety. Transient expression offers the ...

Studying Protein Function and the Role of Altered Protein Expression by Antibody Interference and Three-dimensional Reconstructions

A strict management of protein expression is not only essential to every organism alive, but also an important strategy to investigate protein functions in cellular models. Therefore, recent research invented different tools to target protein expression in mammalian cell lines or even animal models, including RNA and antibody interference. While the first strategy has gathered much attention during the past two decades, peptides &#160;mediating a translocation of antibody cargos across cellular membranes and into cells, obtained much less interest. In this publication, we provide a detailed protocol how to utilize a peptide carrier named Chariot in human embryonic kidney cells as well as in primary hippocampal neurons to perform antibody interference experiments and further illustrate the application of three-dimensional reconstructions in analyzing protein function. Our findings suggest that Chariot is, probably due to its nuclear localization signal, particularly well-suited to target proteins residing in the soma and the nucleus. Remarkably, when applying Chariot to primary hippocampal cultures, the reagent turned out to be surprisingly well accepted by dissociated neurons.

Controlling protein expression is not only essential to every organism alive, but also an important strategy to investigate protein functions in cellular models. The protocol presented shows the application of antibody interference in mammalian cells including primary hippocampal neurons and demonstrates the use of three-dimensional reconstructions in studying protein function.

A strict management of protein expression is not only essential to every organism alive, but also an important strategy to investigate protein functions ...

Synthesis of Infectious Bacteriophages in an E. coli-based Cell-free Expression System

A new generation of cell-free transcription-translation (TXTL) systems, engineered to have a greater versatility and modularity, provide novel capabilities to perform basic and applied sciences in test tube reactions. Over the past decade, cell-free TXTL has become a powerful technique for a broad range of novel multidisciplinary research areas related to quantitative and synthetic biology. The new TXTL platforms are particularly useful to construct and interrogate biochemical systems through the execution of synthetic or natural gene circuits. In vitro TXTL has proven convenient to rapidly prototype regulatory elements and biological networks as well as to recapitulate molecular self-assembly mechanisms found in living systems. In this article, we describe how infectious bacteriophages, such as MS2 (RNA), &#934;&#935;174 (ssDNA), and T7 (dsDNA), are entirely synthesized from their genome in one-pot reactions using an all Escherichia coli, cell-free TXTL system. Synthesis of the three coliphages is quantified using the plaque assay. We show how the yield of synthesized phage depends on the biochemical settings of the reactions. Molecular crowding, emulated through a controlled concentration of PEG 8000, affects the amount of synthesized phages by orders of magnitudes. We also describe how to amplify the phages and how to purify their genomes. The set of protocols and results presented in this work should be of interest to multidisciplinary researchers involved in cell-free synthetic biology and bioengineering.

Synthesis of Infectious Bacteriophages in an E. coli-based Cell-free Expression System

A new generation of cell-free transcription-translation platforms has been engineered to construct biochemical systems in vitro through the execution of gene circuits. In this article, we describe how bacteriophages, such as MS2, &#934;&#935;174, and T7, are synthesized from their genome using an all E. coli cell-free TXTL system.

A new generation of cell-free transcription-translation (TXTL) systems, engineered to have a greater versatility and modularity, provide novel ...

A Multilayer Microfluidic Platform for the Conduction of Prolonged Cell-Free Gene Expression

The limitations of cell-based synthetic biology are becoming increasingly apparent as researchers aim to develop larger and more complex synthetic genetic regulatory circuits. The analysis of synthetic genetic regulatory networks in vivo is time consuming and suffers from a lack of environmental control, with exogenous synthetic components interacting with host processes resulting in undesired behavior. To overcome these issues, cell-free characterization of novel circuitry is becoming more prevalent. In vitro transcription and translation (IVTT) mixtures allow the regulation of the experimental environment and can be optimized for each unique system. The protocols presented here detail the fabrication of a multilayer microfluidic device that can be utilized to sustain IVTT reactions for prolonged durations. In contrast to batch reactions, where resources are depleted over time and (by-) products accumulate, the use of microfluidic devices allows the replenishment of resources as well as the removal of reaction products. In this manner, the cellular environment is emulated by maintaining an out-of-equilibrium environment in which the dynamic behavior of gene circuits can be investigated over extended periods of time. To fully exploit the multilayer microfluidic device, hardware and software have been integrated to automate the IVTT reactions. By combining IVTT reactions with the microfluidic platform presented here, it becomes possible to comprehensively analyze complex network behaviors, furthering our understanding of the mechanisms that regulate cellular processes.

The fabrication process of a PDMS-based, multilayer, microfluidic device that allows in vitro transcription and translation (IVTT) reactions to be performed over prolonged periods is described. Furthermore, a comprehensive overview of the hardware and software required to automate and maintain these reactions for prolonged durations is provided.

The limitations of cell-based synthetic biology are becoming increasingly apparent as researchers aim to develop larger and more complex synthetic genetic ...

High-Throughput Identification of Resistance to Pseudomonas syringae pv. Tomato in Tomato using Seedling Flood Assay

Tomato is an agronomically important crop that can be infected by Pseudomonas syringae, a Gram-negative bacterium, resulting in bacterial speck disease. The tomato-P. syringae pv. tomato pathosystem is widely used to dissect the genetic basis of plant innate responses and disease resistance. While disease was successfully managed for many decades through the introduction of the Pto/Prf gene cluster from Solanum pimpinellifolium into cultivated tomato, race 1 strains of P. syringae have evolved to overcome resistance conferred by the Pto/Prf gene cluster and occur worldwide.
Wild tomato species are important reservoirs of natural diversity in pathogen recognition, because they evolved in diverse environments with different pathogen pressures. In typical screens for disease resistance in wild tomato, adult plants are used, which can limit the number of plants that can be screened due to their extended growth time and greater growth space requirements. We developed a method to screen 10-day-old tomato seedlings for resistance, which minimizes plant growth time and growth chamber space, allows a rapid turnover of plants, and allows large sample sizes to be tested. Seedling outcomes of survival or death can be treated as discrete phenotypes or on a resistance scale defined by amount of new growth in surviving seedlings after flooding. This method has been optimized to screen 10-day-old tomato seedlings for resistance to two P. syringae strains and can easily be adapted to other P. syringae strains.

High-Throughput Identification of Resistance to Pseudomonas syringae pv. Tomato in Tomato using Seedling Flood Assay

The seedling flood assay facilitates rapid screening of wild tomato accessions for the resistance to the Pseudomonas syringae bacterium. This assay, used in conjunction with the seedling bacterial growth assay, can assist in further characterizing the underlying resistance to the bacterium, and can be used to screen mapping populations to determine the genetic basis of resistance.

Tomato is an agronomically important crop that can be infected by Pseudomonas syringae, a Gram-negative bacterium, resulting in bacterial speck disease. ...

Preparing Protein Producing Synthetic Cells using Cell Free Bacterial Extracts, Liposomes and Emulsion Transfer

The bottom-up assembly approach for construction of synthetic cells is an effective tool for isolating and investigating cellular processes in a cell mimicking environment. Furthermore, the development of cell-free expression systems has demonstrated the ability to reconstitute the protein production, transcription and translation processes (DNA&#8594;RNA&#8594;protein) in a controlled manner, harnessing synthetic biology. Here we describe a protocol for preparing a cell-free expression system, including the production of a potent bacterial lysate and encapsulating this lysate inside cholesterol-rich lipid-based giant unilamellar vesicles (GUVs) (i.e., stable liposomes), to form synthetic cells. The protocol describes the methods for preparing the components of the synthetic cells including the production of active bacterial lysates, followed by a detailed step-by-step preparation of the synthetic cells based on a water-in-oil emulsion transfer method. These facilitate the production of millions of synthetic cells in a simple and affordable manner with a high versatility for producing different types of proteins. The obtained synthetic cells can be used to investigate protein/RNA production and activity in an isolated environment, in directed evolution, and also as a controlled drug delivery platform for on-demand production of therapeutic proteins inside the body.

This protocol describes the method, materials, equipment and steps for bottom-up preparation of RNA and protein producing synthetic cells. The inner aqueous compartment of the synthetic cells contained the S30 bacterial lysate encapsulated within a lipid bilayer (i.e., stable liposomes), using a water-in-oil emulsion transfer method.

The bottom-up assembly approach for construction of synthetic cells is an effective tool for isolating and investigating cellular processes in a cell ...

Rapid, Enzymatic Methods for Amplification of Minimal, Linear Templates for Protein Prototyping using Cell-Free Systems

This protocol describes the design of a minimal DNA template and the steps for enzymatic amplification, enabling rapid prototyping of assayable proteins in less than 24 h using cell-free expression. After receiving DNA from a vendor, the gene fragment is PCR-amplified, cut, circularized, and cryo-banked. A small amount of the banked DNA is then diluted and amplified significantly (up to 106x) using isothermal rolling circle amplification (RCA). RCA can yield microgram quantities of the minimal expression template from picogram levels of starting material (mg levels if all starting synthetic fragment is used). In this work, a starting amount of 20 pg resulted in 4 &#181;g of the final product. The resulting RCA product (concatemer of the minimal template) can be added directly to a cell-free reaction with no purification steps. Due to this method being entirely PCR-based, it may enable future high-throughput screening efforts when coupled with automated liquid handling systems.

The study describes a protocol for creating large (&#181;g-mg) quantities of DNA for protein screening campaigns from synthetic gene fragments without cloning or using living cells. The minimal template is enzymatically digested and circularized and then amplified using isothermal rolling circle amplification. Cell-free expression reactions could be performed with the unpurified product.

This protocol describes the design of a minimal DNA template and the steps for enzymatic amplification, enabling rapid prototyping of assayable proteins ...

From Cells to Cell-Free Protein Synthesis within 24 Hours Using Cell-Free Autoinduction Workflow

Cell-free protein synthesis (CFPS) has grown as a biotechnology platform that captures transcription and translation machinery in vitro. Numerous developments have made the CFPS platform more accessible to new users and have expanded the range of applications. For lysate based CFPS systems, cell extracts can be generated from a variety of organisms, harnessing the unique biochemistry of that host to augment protein synthesis. Within the last 20 years, Escherichia coli (E. coli) has become one of the most widely used organisms for supporting CFPS due to its affordability and versatility. Despite numerous key advances, the workflow for E. coli cell extract preparation has remained a key bottleneck for new users to implement CFPS for their applications. The extract preparation workflow is time-intensive and requires technical expertise to achieve reproducible results. To overcome these barriers, we previously reported the development of a 24 hour cell-free autoinduction (CFAI) workflow that reduces user input and technical expertise required. The CFAI workflow minimizes the labor and technical skill required to generate cell extracts while also increasing the total quantities of cell extracts obtained. Here we describe that workflow in a step-by-step manner to improve access and support the broad implementation of E. coli based CFPS.

This work describes the preparation of cell extract from Escherichia coli (E. coli) followed by cell-free protein synthesis (CFPS) reactions in under 24 hours. Explanation of the cell-free autoinduction (CFAI) protocol details improvements made to reduce researcher oversight and increase quantities of cell extract obtained.

Cell-free protein synthesis (CFPS) has grown as a biotechnology platform that captures transcription and translation machinery in vitro. Numerous ...

Cell-Free Protein Synthesis from Exonuclease-Deficient Cellular Extracts Utilizing Linear DNA Templates

Cell-free protein synthesis (CFPS) has recently become very popular in the field of synthetic biology due to its numerous advantages. Using linear DNA templates for CFPS will further enable the technology to reach its full potential, decreasing the experimental time by eliminating the steps of cloning, transformation, and plasmid extraction. Linear DNA can be rapidly and easily amplified by PCR to obtain high concentrations of the template, avoiding potential in vivo expression toxicity. However, linear DNA templates are rapidly degraded by exonucleases that are naturally present in the cell extracts. There are several strategies that have been proposed to tackle this problem, such as adding nuclease inhibitors or chemical modification of linear DNA ends for protection. All these strategies cost extra time and resources and are yet to obtain near-plasmid levels of protein expression. A detailed protocol for an alternative strategy is presented here for using linear DNA templates for CFPS. By using cell extracts from exonuclease-deficient knockout cells, linear DNA templates remain intact without requiring any end-modifications. We present the preparation steps of cell lysate from Escherichia coli BL21 Rosetta2 &#916;recBCD strain by sonication lysis and buffer calibration for Mg-glutamate (Mg-glu) and K-glutamate (K-glu) specifically for linear DNA. This method is able to achieve protein expression levels comparable to that from plasmid DNA in E. coli CFPS.

Presented here is a protocol for the preparation and buffer calibration of cell extracts from exonuclease V knockout strains of Escherichia coli BL21 Rosetta2 (&#916;recBCD and &#916;recB). This is a fast, easy, and direct approach for expression in cell-free protein synthesis systems using linear DNA templates.

Cell-free protein synthesis (CFPS) has recently become very popular in the field of synthetic biology due to its numerous advantages. Using linear DNA ...