1
|
Müller J, Siemann-Herzberg M, Takors R. Modeling Cell-Free Protein Synthesis Systems-Approaches and Applications. Front Bioeng Biotechnol 2020; 8:584178. [PMID: 33195146 PMCID: PMC7655533 DOI: 10.3389/fbioe.2020.584178] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 09/29/2020] [Indexed: 01/03/2023] Open
Abstract
In vitro systems are ideal setups to investigate the basic principles of biochemical reactions and subsequently the bricks of life. Cell-free protein synthesis (CFPS) systems mimic the transcription and translation processes of whole cells in a controlled environment and allow the detailed study of single components and reaction networks. In silico studies of CFPS systems help us to understand interactions and to identify limitations and bottlenecks in those systems. Black-box models laid the foundation for understanding the production and degradation dynamics of macromolecule components such as mRNA, ribosomes, and proteins. Subsequently, more sophisticated models revealed shortages in steps such as translation initiation and tRNA supply and helped to partially overcome these limitations. Currently, the scope of CFPS modeling has broadened to various applications, ranging from the screening of kinetic parameters to the stochastic analysis of liposome-encapsulated CFPS systems and the assessment of energy supply properties in combination with flux balance analysis (FBA).
Collapse
Affiliation(s)
| | | | - Ralf Takors
- Institute of Biochemical Engineering, University of Stuttgart, Stuttgart, Germany
| |
Collapse
|
2
|
A protocell with fusion and division. Biochem Soc Trans 2019; 47:1909-1919. [PMID: 31819942 DOI: 10.1042/bst20190576] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 11/12/2019] [Accepted: 11/25/2019] [Indexed: 11/17/2022]
Abstract
A protocell is a synthetic form of cellular life that is constructed from phospholipid vesicles and used to understand the emergence of life from a nonliving chemical network. To be considered 'living', a protocell should be capable of self-proliferation, which includes successive growth and division processes. The growth of protocells can be achieved via vesicle fusion approaches. In this review, we provide a brief overview of recent research on the formation of a protocell, fusion and division processes of the protocell, and encapsulation of a defined chemical network such as the genetic material. We also provide some perspectives on the challenges and future developments of synthetic protocell research.
Collapse
|
3
|
Blanken D, van Nies P, Danelon C. Quantitative imaging of gene-expressing liposomes reveals rare favorable phenotypes. Phys Biol 2019; 16:045002. [PMID: 30978176 DOI: 10.1088/1478-3975/ab0c62] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The biosynthesis of proteins from genomic DNA is a universal process in every living organism. Building a synthetic cell using separate biological parts hence implies to reconstitute a minimal gene expression apparatus and to compartmentalize it in a cell-mimicking environment. Previous studies have demonstrated that the PURE (Protein synthesis Using Recombinant Elements) system could be functionally encapsulated inside lipid vesicles. However, quantitative insights on functional consequences of spatial confinement of PURE system reactions remain scarce, which has hampered the full exploitation of gene-expressing liposomes as the fundamental unit to build an artificial cell. We report on direct imaging of tens of thousands of gene-expressing liposomes per sample allowing us to assess sub-population features in a statistically relevant manner. Both the vesicle size (diameter <10 μm) and lipid composition (mixture of phospholipids with zwitterionic and negatively charged headgroups, including cardiolipin) are compatible with the properties of bacterial cells. Therefore, our liposomes provide a suitable chassis to host the Escherichia coli-derived PURE translation machinery and other bacterial processes in future developments. The potential of high-content imaging to identify rare phenotypes is demonstrated by the fact that a subset of the liposome population exhibits a remarkably high yield of synthesized protein or a prolonged expression lifespan that surpasses the performance of ensemble liposome-averaged and bulk reactions. Among the three commercial PURE systems tested, PUREfrex2.0 offers the most favorable phenotypes displaying both high yield and long protein synthesis lifespan. Moreover, probing membrane permeability reveals a large heterogeneity amongst liposomes. In situ expression and membrane embedding of the pore-forming connexin leads to a characteristic permeability time profile, while increasing the fraction of permeable liposomes in the population. We see diversity in gene expression dynamics and membrane permeability as an opportunity to complement a rational design approach aiming at further implementing biological functions in liposome-based synthetic cells.
Collapse
Affiliation(s)
- Duco Blanken
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, van der Maasweg 9, 2629 HZ, Delft, The Netherlands
| | | | | |
Collapse
|
4
|
Fanti A, Gammuto L, Mavelli F, Stano P, Marangoni R. Do protocells preferentially retain macromolecular solutes upon division/fragmentation? A study based on the extrusion of POPC giant vesicles. Integr Biol (Camb) 2019; 10:6-17. [PMID: 29230464 DOI: 10.1039/c7ib00138j] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
A key process of protocell behaviour is their recursive growth and division. In order to be sustainable, the latter must be characterized by an even and homogeneous partition of the solute molecules initially present in the parent protocell among the daughter ones. Here we have investigated, by means of an artificial division model (extrusion of giant lipid vesicles) and confocal microscopy, the fate of solutes when a large vesicle fragments into many smaller vesicles. Solutes of low- and high-molecular weight such as pyranine, calcein, albumin-FITC, dextran-FITC and carbonic anhydrase have been employed. Although the vesicle extrusion brings about a release of their inner content in the environment, the results shown in this initial report indicate that macromolecules can be partially retained when compared with low-molecular weight ones. Results are discussed from the viewpoint of the life cycle of primitive cells. In particular, the findings suggest that a similar mechanism operating during the critical step of vesicle growth-division could have contributed to primitive evolution.
Collapse
Affiliation(s)
- Alessio Fanti
- Biology Department, University of Pisa, Via Derna 1, I-56126 Pisa, Italy.
| | | | | | | | | |
Collapse
|
5
|
Chandra Kaushik A, Wang YJ, Wang X, Kumar A, Singh SP, Pan CT, Shiue YL, Wei DQ. Evaluation of anti-EGFR-iRGD recombinant protein with GOLD nanoparticles: synergistic effect on antitumor efficiency using optimized deep neural networks. RSC Adv 2019; 9:19261-19270. [PMID: 35519377 PMCID: PMC9065452 DOI: 10.1039/c9ra01975h] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 06/13/2019] [Indexed: 12/11/2022] Open
Abstract
NP screening through a deep learning approach against Anti-EGFR and validation through docking with AuNP. Biochemical pathway and simulation of AuNP with Anti-EGFR and further implementation in biological circuits.
Collapse
Affiliation(s)
- Aman Chandra Kaushik
- The State Key Laboratory of Microbial Metabolism
- School of Life Sciences and Biotechnology
- Shanghai Jiao Tong University
- Shanghai
- China
| | - Yan-Jing Wang
- The State Key Laboratory of Microbial Metabolism
- School of Life Sciences and Biotechnology
- Shanghai Jiao Tong University
- Shanghai
- China
| | - Xiangeng Wang
- The State Key Laboratory of Microbial Metabolism
- School of Life Sciences and Biotechnology
- Shanghai Jiao Tong University
- Shanghai
- China
| | - Ajay Kumar
- Institute of Biomedical Sciences
- National Sun Yat-Sen University
- Kaohsiung City 804
- Taiwan
- Department of Mechanical and Electro-Mechanical Engineering
| | - Satya P. Singh
- School of Electrical and Electronic Engineering
- Nanyang Technological University
- Singapore
| | - Cheng-Tang Pan
- Department of Mechanical and Electro-Mechanical Engineering
- National Sun Yat-sen University
- Kaohsiung City 804
- Taiwan
- Institute of Medical Science and Technology
| | - Yow-Ling Shiue
- Institute of Biomedical Sciences
- National Sun Yat-Sen University
- Kaohsiung City 804
- Taiwan
| | - Dong-Qing Wei
- The State Key Laboratory of Microbial Metabolism
- School of Life Sciences and Biotechnology
- Shanghai Jiao Tong University
- Shanghai
- China
| |
Collapse
|
6
|
Stano P. Is Research on "Synthetic Cells" Moving to the Next Level? Life (Basel) 2018; 9:E3. [PMID: 30587790 PMCID: PMC6463193 DOI: 10.3390/life9010003] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 12/20/2018] [Accepted: 12/21/2018] [Indexed: 12/15/2022] Open
Abstract
"Synthetic cells" research focuses on the construction of cell-like models by using solute-filled artificial microcompartments with a biomimetic structure. In recent years this bottom-up synthetic biology area has considerably progressed, and the field is currently experiencing a rapid expansion. Here we summarize some technical and theoretical aspects of synthetic cells based on gene expression and other enzymatic reactions inside liposomes, and comment on the most recent trends. Such a tour will be an occasion for asking whether times are ripe for a sort of qualitative jump toward novel SC prototypes: is research on "synthetic cells" moving to a next level?
Collapse
Affiliation(s)
- Pasquale Stano
- Department of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento; Ecotekne-S.P. Lecce-Monteroni, I-73100 Lecce, Italy.
| |
Collapse
|
7
|
Liu CC, Lin CC, Hsiao YC, Wang PJ, Yu JS. Proteomic characterization of six Taiwanese snake venoms: Identification of species-specific proteins and development of a SISCAPA-MRM assay for cobra venom factors. J Proteomics 2018; 187:59-68. [DOI: 10.1016/j.jprot.2018.06.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 05/28/2018] [Accepted: 06/13/2018] [Indexed: 01/07/2023]
|
8
|
Mavelli F, Stano P. Experiments on and Numerical Modeling of the Capture and Concentration of Transcription-Translation Machinery inside Vesicles. ARTIFICIAL LIFE 2015; 21:445-463. [PMID: 26545162 DOI: 10.1162/artl_a_00187] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Synthetic or semi-synthetic minimal cells are those cell-like artificial compartments that are based on the encapsulation of molecules inside lipid vesicles (liposomes). Synthetic cells are currently used as primitive cell models and are very promising tools for future biotechnology. Despite the recent experimental advancements and sophistication reached in this field, the complete elucidation of many fundamental physical aspects still poses experimental and theoretical challenges. The interplay between solute capture and vesicle formation is one of the most intriguing ones. In a series of studies, we have reported that when vesicles spontaneously form in a dilute solution of proteins, ribosomes, or ribo-peptidic complexes, then, contrary to statistical predictions, it is possible to find a small fraction of liposomes (<1%) that contain a very large number of solutes, so that their local (intravesicular) concentrations largely exceed the expected value. More recently, we have demonstrated that this effect (spontaneous crowding) operates also on multimolecular mixtures, and can drive the synthesis of proteins inside vesicles, whereas the same reaction does not proceed at a measurable rate in the external bulk phase. Here we firstly introduce and discuss these already published observations. Then, we present a computational investigation of the encapsulation of transcription-translation (TX-TL) machinery inside vesicles, based on a minimal protein synthesis model and on different solute partition functions. Results show that experimental data are compatible with an entrapment model that follows a power law rather than a Gaussian distribution. The results are discussed from the viewpoint of origin of life, highlighting open questions and possible future research directions.
Collapse
|
9
|
Walde P, Umakoshi H, Stano P, Mavelli F. Emergent properties arising from the assembly of amphiphiles. Artificial vesicle membranes as reaction promoters and regulators. Chem Commun (Camb) 2015; 50:10177-97. [PMID: 24921467 DOI: 10.1039/c4cc02812k] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
This article deals with artificial vesicles and their membranes as reaction promoters and regulators. Among the various molecular assemblies which can form in an aqueous medium from amphiphilic molecules, vesicle systems are unique. Vesicles compartmentalize the aqueous solution in which they exist, independent on whether the vesicles are biological vesicles (existing in living systems) or whether they are artificial vesicles (formed in vitro from natural or synthetic amphiphiles). After the formation of artificial vesicles, their aqueous interior (the endovesicular volume) may become - or may be made - chemically different from the external medium (the exovesicular solution), depending on how the vesicles are prepared. The existence of differences between endo- and exovesicular composition is one of the features on the basis of which biological vesicles contribute to the complex functioning of living organisms. Furthermore, artificial vesicles can be formed from mixtures of amphiphiles in such a way that the vesicle membranes become molecularly, compositionally and organizationally highly complex, similarly to the lipidic matrix of biological membranes. All the various properties of artificial vesicles as membranous compartment systems emerge from molecular assembly as these properties are not present in the individual molecules the system is composed of. One particular emergent property of vesicle membranes is their possible functioning as promoters and regulators of chemical reactions caused by the localization of reaction components, and possibly catalysts, within or on the surface of the membranes. This specific feature is reviewed and highlighted with a few selected examples which range from the promotion of decarboxylation reactions, the selective binding of DNA or RNA to suitable vesicle membranes, and the reactivation of fragmented enzymes to the regulation of the enzymatic synthesis of polymers. Such type of emergent properties of vesicle membranes may have been important for the prebiological evolution of protocells, the hypothetical compartment systems preceding the first cells in those chemical and physico-chemical processes that led to the origin of life.
Collapse
Affiliation(s)
- Peter Walde
- Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, CH-8093 Zürich, Switzerland.
| | | | | | | |
Collapse
|
10
|
Paradisi P, Allegrini P, Chiarugi D. A renewal model for the emergence of anomalous solute crowding in liposomes. BMC SYSTEMS BIOLOGY 2015; 9 Suppl 3:S7. [PMID: 26051120 PMCID: PMC4464207 DOI: 10.1186/1752-0509-9-s3-s7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
A fundamental evolutionary step in the onset of living cells is thought to be the spontaneous formation of lipid vesicles (liposomes) in the pre-biotic mixture. Even though it is well known that hydrophobic forces drive spontaneous liposome formation in aqueous solutions, how the components of the earliest biochemical pathways were trapped and concentrated in the forming vesicles is an issue that still needs to be clarified. In recent years, some authors carried out a set of experiments where a unexpectedly high amount of solutes were found in a small number of liposomes, spontaneously formed in aqueous solution. A great number of empty liposomes were found in the same experiments and the global observed behavior was that of a distribution of solute particles into liposomes in agreement with a inverse power-law function rather than with the expected Poisson distribution. The chemical and physical mechanisms leading to the observed "anomalous solute crowding" are still unclear, but the non-Poisson power-law behavior is associated with some cooperative behavior with strong non-linear interactions in the biochemical processes occurring in the solution. For tackling this issue we propose a model grounding on the Cox's theory of renewal point processes, which many authors consider to play a central role in the description of complex cooperative systems. Starting from two very basic hypotheses and the renewal assumption, we derive a model reproducing the behavior outlined above. In particular, we show that the assumption of a "cooperative" interaction between the solute molecules and the forming liposomes is sufficient for the emergence of the observed power-law behavior. Even though our approach does not provide experimental evidences of the chemical and physical bases of the solute crowding, it suggests promising directions for experimental research and it also provide a first theoretical prediction that could possibly be tested in future experimental investigations.
Collapse
|
11
|
Mavelli F, Marangoni R, Stano P. A Simple Protein Synthesis Model for the PURE System Operation. Bull Math Biol 2015; 77:1185-212. [PMID: 25911591 DOI: 10.1007/s11538-015-0082-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 04/07/2015] [Indexed: 11/24/2022]
Abstract
The encapsulation of transcription-translation (TX-TL) cell-free machinery inside lipid vesicles (liposomes) is a key element in synthetic cell technology. The PURE system is a TX-TL kit composed of well-characterized parts, whose concentrations are fine tunable, which works according to a modular architecture. For these reasons, the PURE system perfectly fulfils the requirements of synthetic biology and is widely used for constructing synthetic cells. In this work, we present a simplified mathematical model to simulate the PURE system operations. Based on Michaelis-Menten kinetics and differential equations, the model describes protein synthesis dynamics by using 9 chemical species, 6 reactions and 16 kinetic parameters. The model correctly predicts the time course for messenger RNA and protein production and allows quantitative predictions. By means of this model, it is possible to foresee how the PURE system species affect the mechanism of proteins synthesis and therefore help in understanding scenarios where the concentration of the PURE system components has been modified purposely or as a result of stochastic fluctuations (for example after random encapsulation inside vesicles). The model also makes the determination of response coefficients for all species involved in the TX-TL mechanism possible and allows for scrutiny on how chemical energy is consumed by the three PURE system modules (transcription, translation and aminoacylation).
Collapse
Affiliation(s)
- Fabio Mavelli
- Chemistry Department, University of Bari, Via Orabona 4, Bari, Italy,
| | | | | |
Collapse
|
12
|
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
|
13
|
de Souza TP, Fahr A, Luisi PL, Stano P. Spontaneous Encapsulation and Concentration of Biological Macromolecules in Liposomes: An Intriguing Phenomenon and Its Relevance in Origins of Life. J Mol Evol 2014; 79:179-92. [DOI: 10.1007/s00239-014-9655-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 11/10/2014] [Indexed: 12/31/2022]
|
14
|
Okano T, Matsuura T, Suzuki H, Yomo T. Cell-free protein synthesis in a microchamber revealed the presence of an optimum compartment volume for high-order reactions. ACS Synth Biol 2014; 3:347-52. [PMID: 23991849 DOI: 10.1021/sb400087e] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The application of microelectromechanical systems (MEMS) to chemistry and biochemistry allows various reactions to be performed in microscale compartments. Here, we aimed to use the glass microchamber to study the compartment size dependency of the protein synthesis, one of the most important reactions in the cell. By encapsulating the cell-free protein synthesis system with different reaction orders in femtoliter microchambers, chamber size dependency of the reaction initiated with a constant copy number of DNA was investigated. We were able to observe the properties specific to the high order reactions in microcompartments with high precision and found the presence of an optimum compartment volume for a high-order reaction using real biological molecules.
Collapse
Affiliation(s)
- Taiji Okano
- Exploratory Research
for Advanced Technology, Japan Science and Technology Agency, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Tomoaki Matsuura
- Exploratory Research
for Advanced Technology, Japan Science and Technology Agency, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan
- Department
of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita,
Osaka 565-0871, Japan
| | - Hiroaki Suzuki
- Exploratory Research
for Advanced Technology, Japan Science and Technology Agency, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan
- Department
of Precision Mechanics, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan
| | - Tetsuya Yomo
- Exploratory Research
for Advanced Technology, Japan Science and Technology Agency, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan
- Department
of Bioinformatic Engineering, Graduate School of Information
Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan
- Graduate School
of Frontier Biosciences, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan
| |
Collapse
|
15
|
Martini L, Mansy SS. Measuring riboswitch activity in vitro and in artificial cells with purified transcription-translation machinery. Methods Mol Biol 2014; 1111:153-164. [PMID: 24549618 DOI: 10.1007/978-1-62703-755-6_11] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We present a simple method to measure the real-time activity of riboswitches with purified components in vitro and inside of artificial cells. Typically, riboswitch activity is measured in vivo by exploiting β-galactosidase encoding constructs with a putative riboswitch sequence in the untranslated region. Additional in vitro characterization often makes use of in-line probing to explore conformational changes induced by ligand binding to the mRNA or analyses of transcript lengths in the presence and absence of ligand. However, riboswitches ultimately control protein levels and often times require accessory factors. Therefore, an in vitro system capable of monitoring protein production with fully defined components that can be supplemented with accessory factors would greatly aid riboswitch studies. Herein we present a system that is amenable to such analyses. Further, since the described system can be easily reconstituted within compartments to build artificial, cellular mimics with sensing capability, protocols are provided for building sense-response systems within water-in-oil emulsion compartments and lipid vesicles. Only standard laboratory equipment and commercially available material are exploited for the described assays, including DNA, purified transcription-translation machinery, i.e., the PURE system, and a spectrofluorometer.
Collapse
|
16
|
Spencer AC, Torre P, Mansy SS. The encapsulation of cell-free transcription and translation machinery in vesicles for the construction of cellular mimics. J Vis Exp 2013:e51304. [PMID: 24192867 PMCID: PMC3948186 DOI: 10.3791/51304] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
As interest shifts from individual molecules to systems of molecules, an increasing number of laboratories have sought to build from the bottom up cellular mimics that better represent the complexity of cellular life. To date there are a number of paths that could be taken to build compartmentalized cellular mimics, including the exploitation of water-in-oil emulsions, microfluidic devices, and vesicles. Each of the available options has specific advantages and disadvantages. For example, water-in-oil emulsions give high encapsulation efficiency but do not mimic well the permeability barrier of living cells. The primary advantage of the methods described herein is that they are all easy and cheap to implement. Transcription-translation machinery is encapsulated inside of phospholipid vesicles through a process that exploits common instrumentation, such as a centrifugal evaporator and an extruder. Reactions are monitored by fluorescence spectroscopy. The protocols can be adapted for recombinant protein expression, the construction of cellular mimics, the exploration of the minimum requirements for cellular life, or the assembly of genetic circuitry.
Collapse
Affiliation(s)
- Amy C Spencer
- Centre for Integrative Biology, University of Trento
| | | | | |
Collapse
|
17
|
Calviello L, Stano P, Mavelli F, Luisi PL, Marangoni R. Quasi-cellular systems: stochastic simulation analysis at nanoscale range. BMC Bioinformatics 2013; 14 Suppl 7:S7. [PMID: 23815522 PMCID: PMC3633058 DOI: 10.1186/1471-2105-14-s7-s7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND The wet-lab synthesis of the simplest forms of life (minimal cells) is a challenging aspect in modern synthetic biology. Quasi-cellular systems able to produce proteins directly from DNA can be obtained by encapsulating the cell-free transcription/translation system PURESYSTEM(PS) in liposomes. It is possible to detect the intra-vesicle protein production using DNA encoding for GFP and monitoring the fluorescence emission over time. The entrapment of solutes in small-volume liposomes is a fundamental open problem. Stochastic simulation is a valuable tool in the study of biochemical reaction at nanoscale range. QDC (Quick Direct-Method Controlled), a stochastic simulation software based on the well-known Gillespie's SSA algorithm, was used. A suitable model formally describing the PS reactions network was developed, to predict, from inner species concentrations (very difficult to measure in small-volumes), the resulting fluorescence signal (experimentally observable). RESULTS Thanks to suitable features specific of QDC, we successfully formalized the dynamical coupling between the transcription and translation processes that occurs in the real PS, thus bypassing the concurrent-only environment of Gillespie's algorithm. Simulations were firstly performed for large liposomes (2.67µm of diameter) entrapping the PS to synthetize GFP. By varying the initial concentrations of the three main classes of molecules involved in the PS (DNA, enzymes, consumables), we were able to stochastically simulate the time-course of GFP-production. The sigmoid fit of the GFP-production curves allowed us to extract three quantitative parameters which are significantly dependent on the various initial states. Then we extended this study for small-volume liposomes (575 nm of diameter), where it is more complex to infer the intra-vesicle composition, due to the expected anomalous entrapment phenomena. We identified almost two extreme states that are forecasted to give rise to significantly different experimental observables. CONCLUSIONS The present work is the first one describing in the detail the stochastic behavior of the PS. Thanks to our results, an experimental approach is now possible, aimed at recording the GFP production kinetics in very small micro-emulsion droplets or liposomes, and inferring, by using the simulation as a reverse-engineering procedure, the internal solutes distribution, and shed light on the still unknown forces driving the entrapment phenomenon.
Collapse
Affiliation(s)
- Lorenzo Calviello
- Dipartimento di Informatica, Università di Pisa, L.go B. Pontecorvo 3, 56127 Pisa, Italy
| | - Pasquale Stano
- Dipartimento di Biologia, Università di Roma III, Via G. Marconi 446, 00146 Roma, Italy
| | - Fabio Mavelli
- Dipartimento di Chimica, Università di Bari, Via E. Orabona 4, 70121 Bari, Italy
| | - Pier Luigi Luisi
- Dipartimento di Biologia, Università di Roma III, Via G. Marconi 446, 00146 Roma, Italy
| | - Roberto Marangoni
- Dipartimento di Informatica, Università di Pisa, L.go B. Pontecorvo 3, 56127 Pisa, Italy
- Istituto di Biofisica del CNR, Via G. Moruzzi 1, 56124 Pisa, Italy
| |
Collapse
|
18
|
Nourian Z, Danelon C. Linking genotype and phenotype in protein synthesizing liposomes with external supply of resources. ACS Synth Biol 2013; 2:186-93. [PMID: 23656477 DOI: 10.1021/sb300125z] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Reconstituting an elementary gene expression system inside self-assembled lipid vesicles to mimic the cellular synthesis machinery is at the core of the development of a minimal cell following a bottom-up synthetic biology approach. The ability to operate the expression of multiple genes in a controlled manner and to generate the output proteins with predictable dynamics in liposomes relies on the link between genotype and phenotype. Here, we established this link in surface-tethered liposomes producing proteins from a linear DNA template using a reconstituted transcription/translation/aminoacylation apparatus fuelled by external supply of feedstock. The amounts of entrapped DNA molecules and synthesized proteins were visualized by fluorescence confocal microscopy in individual vesicles. We showed that there exists no linear correlation between the amount of encapsulated genes and the level of output proteins, which is a consequence of the compositional heterogeneity between liposomes due to the low-copy number of some constituents, as well as interfacing differences with the nutrient-containing environment. In order to decouple gene activity from those sources of variability and, thus, infer the probabilistic occupancy of transcriptionally active genes in protein synthesizing liposomes, we developed a dual gene expression assay consisting of the production of two fluorescent reporter proteins of distinguishable colors from two different DNA templates. The stochastic color-coding of the vesicles was analyzed and compared to the color pattern expected from a Poisson distribution of encapsulated genes. Unexpectedly, we found that the apparent number of transcriptionally active DNA molecules in liposomes corresponds only to ca. 10% of the bulk concentration. We believe that our study provides new insights about the relationship between the genotype and phenotype in protein synthesizing liposomes, which is of primary importance toward the construction of a programmable artificial cell implemented with regulatory gene networks of predictable dynamics.
Collapse
Affiliation(s)
- Zohreh Nourian
- Department of Bionanoscience,
Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628
CJ, Delft, The Netherlands
| | - Christophe Danelon
- Department of Bionanoscience,
Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628
CJ, Delft, The Netherlands
| |
Collapse
|
19
|
Stano P, Luisi PL. Semi-synthetic minimal cells: origin and recent developments. Curr Opin Biotechnol 2013; 24:633-8. [PMID: 23374484 DOI: 10.1016/j.copbio.2013.01.002] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 12/19/2012] [Accepted: 01/03/2013] [Indexed: 10/27/2022]
Abstract
The notion of minimal cells refers to cellular structures that contain the minimal and sufficient complexity to still be defined as living, or at least capable to display the most important features of biological cells. Here we briefly describe the laboratory construction of minimal cells, a project within the broader field of synthetic biology. In particular we discuss the advancements in the preparation of semi-synthetic cells based on the encapsulation of biochemicals inside liposomes, illustrating from the one hand the origin of this research and the most recent developments; and from the other the difficulties and limits of the approach. The role of physicochemical understandings is greatly emphasized.
Collapse
Affiliation(s)
- Pasquale Stano
- Biology Department, University of Roma Tre, Viale G. Marconi 446, I-00146 Rome, Italy
| | | |
Collapse
|
20
|
Romano P, Helmer-Citterich M. Bioinformatics in Italy: BITS2011, the Eighth Annual Meeting of the Italian Society of Bioinformatics. BMC Bioinformatics 2012; 13 Suppl 4:I1. [PMID: 22536954 PMCID: PMC3314567 DOI: 10.1186/1471-2105-13-s4-i1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The BITS2011 meeting, held in Pisa on June 20-22, 2011, brought together more than 120 Italian researchers working in the field of Bioinformatics, as well as students in Bioinformatics, Computational Biology, Biology, Computer Sciences, and Engineering, representing a landscape of Italian bioinformatics research. This preface provides a brief overview of the meeting and introduces the peer-reviewed manuscripts that were accepted for publication in this Supplement.
Collapse
|
21
|
de Souza TP, Stano P, Steiniger F, D'Aguanno E, Altamura E, Fahr A, Luisi PL. Encapsulation of ferritin, ribosomes, and ribo-peptidic complexes inside liposomes: insights into the origin of metabolism. ORIGINS LIFE EVOL B 2012; 42:421-8. [PMID: 23080007 DOI: 10.1007/s11084-012-9303-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Accepted: 08/22/2012] [Indexed: 10/27/2022]
Abstract
Here we summarize the main results of our latest investigation on the spontaneous encapsulation of proteins (ferritin) and ribosomes inside lipid vesicles. We show that when vesicles form in a solution containing some macromolecules (even at low concentration), in contrast to the expectations, a few but measurable number of vesicles is able to capture a very high number of solutes, up to 60 times the external concentration. We also show preliminary evidences on the encapsulation of additional solutes (ribo-peptidic complexes, fluorescent proteins and enzymes), and shortly present our current approach aimed at exploiting this phenomenon. In particular, we would like to reveal how the formation of compartments can trigger effective intra-vesicle reactions starting from diluted solutions. Although the mechanistic details for this phenomenon are still missing, we claim that these new evidences are highly relevant for the origin of the first functional cells in primitive times.
Collapse
Affiliation(s)
- Tereza Pereira de Souza
- Institut für Pharmazie, Friedrich Schiller Universität Jena, Lessingstrasse 8, 07743 Jena, Germany
| | | | | | | | | | | | | |
Collapse
|