1
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Feng B, Hu W, Duan Y, Li Z. A flexible 'plug and play' bicistronic construct and its application in the screening of protein expression system in Escherichia coli. J Microbiol Methods 2024; 221:106928. [PMID: 38583783 DOI: 10.1016/j.mimet.2024.106928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 04/02/2024] [Accepted: 04/04/2024] [Indexed: 04/09/2024]
Abstract
The bicistronic expression system that utilizes fluorescent reporters has been demonstrated to be a straightforward method for detecting recombinant protein expression levels, particularly when compared to polyacrylamide gel electrophoresis and immunoblot analysis, which are tedious and labor-intensive. However, existing bicistronic reporter systems are less capable of quantitative measurement due to the lag in reporter expression and its negative impact on target protein. In this work, a plug and play bicistronic construct using mCherry as reporter was applied in the screening of optimal replicon and promoter for Sortase expression in Escherichia coli (E. coli). The bicistronic construct allowed the reporter gene and target open reading frame (ORF) to be co-transcribed under the same promoter, resulting in a highly positive quantitative correlation between the expression titer of Sortase and the fluorescent intensity (R2 > 0.97). With the correlation model, the titer of target protein can be quantified by noninvasively measuring the fluorescent intensity. On top of this, the expression of reporter has no significant effect on the yield of target protein, thus favoring a plug and play design for removing reporter gene to generate a plain plasmid for industrial use.
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Affiliation(s)
- Binbin Feng
- Microbial and Viral Platform, WuXi Biologics (Hangzhou FTZ) Co., Ltd, #9, 388 of No.16 street, Baiyang Avenue, Hangzhou Free Trade Zone, Hangzhou, Zhejiang Province, China
| | - Weiwei Hu
- Microbial and Viral Platform, WuXi Biologics (Hangzhou FTZ) Co., Ltd, #9, 388 of No.16 street, Baiyang Avenue, Hangzhou Free Trade Zone, Hangzhou, Zhejiang Province, China
| | - Yingyi Duan
- Microbial and Viral Platform, WuXi Biologics (Hangzhou FTZ) Co., Ltd, #9, 388 of No.16 street, Baiyang Avenue, Hangzhou Free Trade Zone, Hangzhou, Zhejiang Province, China.
| | - Zhaopeng Li
- Microbial and Viral Platform, WuXi Biologics (Hangzhou FTZ) Co., Ltd, #9, 388 of No.16 street, Baiyang Avenue, Hangzhou Free Trade Zone, Hangzhou, Zhejiang Province, China.
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2
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Giannantoni L, Bardini R, Savino A, Di Carlo S. Biology System Description Language (BiSDL): a modeling language for the design of multicellular synthetic biological systems. BMC Bioinformatics 2024; 25:166. [PMID: 38664639 PMCID: PMC11046772 DOI: 10.1186/s12859-024-05782-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Accepted: 04/12/2024] [Indexed: 04/28/2024] Open
Abstract
BACKGROUND The Biology System Description Language (BiSDL) is an accessible, easy-to-use computational language for multicellular synthetic biology. It allows synthetic biologists to represent spatiality and multi-level cellular dynamics inherent to multicellular designs, filling a gap in the state of the art. Developed for designing and simulating spatial, multicellular synthetic biological systems, BiSDL integrates high-level conceptual design with detailed low-level modeling, fostering collaboration in the Design-Build-Test-Learn cycle. BiSDL descriptions directly compile into Nets-Within-Nets (NWNs) models, offering a unique approach to spatial and hierarchical modeling in biological systems. RESULTS BiSDL's effectiveness is showcased through three case studies on complex multicellular systems: a bacterial consortium, a synthetic morphogen system and a conjugative plasmid transfer process. These studies highlight the BiSDL proficiency in representing spatial interactions and multi-level cellular dynamics. The language facilitates the compilation of conceptual designs into detailed, simulatable models, leveraging the NWNs formalism. This enables intuitive modeling of complex biological systems, making advanced computational tools more accessible to a broader range of researchers. CONCLUSIONS BiSDL represents a significant step forward in computational languages for synthetic biology, providing a sophisticated yet user-friendly tool for designing and simulating complex biological systems with an emphasis on spatiality and cellular dynamics. Its introduction has the potential to transform research and development in synthetic biology, allowing for deeper insights and novel applications in understanding and manipulating multicellular systems.
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Affiliation(s)
- Leonardo Giannantoni
- Department of Control and Computer Engineering, Polytechnic University of Turin, Corso Duca degli Abruzzi, 24, 100129, Turin, TO, Italy
| | - Roberta Bardini
- Department of Control and Computer Engineering, Polytechnic University of Turin, Corso Duca degli Abruzzi, 24, 100129, Turin, TO, Italy.
| | - Alessandro Savino
- Department of Control and Computer Engineering, Polytechnic University of Turin, Corso Duca degli Abruzzi, 24, 100129, Turin, TO, Italy
| | - Stefano Di Carlo
- Department of Control and Computer Engineering, Polytechnic University of Turin, Corso Duca degli Abruzzi, 24, 100129, Turin, TO, Italy
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3
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Hamrick GS, Maddamsetti R, Son HI, Wilson ML, Davis HM, You L. Programming Dynamic Division of Labor Using Horizontal Gene Transfer. ACS Synth Biol 2024; 13:1142-1151. [PMID: 38568420 DOI: 10.1021/acssynbio.3c00615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
The metabolic engineering of microbes has broad applications, including biomanufacturing, bioprocessing, and environmental remediation. The introduction of a complex, multistep pathway often imposes a substantial metabolic burden on the host cell, restraining the accumulation of productive biomass and limiting pathway efficiency. One strategy to alleviate metabolic burden is the division of labor (DOL) in which different subpopulations carry out different parts of the pathway and work together to convert a substrate into a final product. However, the maintenance of different engineered subpopulations is challenging due to competition and convoluted interstrain population dynamics. Through modeling, we show that dynamic division of labor (DDOL), which we define as the DOL between indiscrete populations capable of dynamic and reversible interchange, can overcome these limitations and enable the robust maintenance of burdensome, multistep pathways. We propose that DDOL can be mediated by horizontal gene transfer (HGT) and use plasmid genomics to uncover evidence that DDOL is a strategy utilized by natural microbial communities. Our work suggests that bioengineers can harness HGT to stabilize synthetic metabolic pathways in microbial communities, enabling the development of robust engineered systems for deployment in a variety of contexts.
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Affiliation(s)
- Grayson S Hamrick
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, United States
- Center for Quantitative Biodesign, Duke University, Durham, North Carolina 27708, United States
- Center for Biomolecular and Tissue Engineering, Duke University, Durham, North Carolina 27708, United States
| | - Rohan Maddamsetti
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, United States
- Center for Quantitative Biodesign, Duke University, Durham, North Carolina 27708, United States
| | - Hye-In Son
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, United States
- Center for Quantitative Biodesign, Duke University, Durham, North Carolina 27708, United States
| | - Maggie L Wilson
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, United States
- Center for Quantitative Biodesign, Duke University, Durham, North Carolina 27708, United States
| | - Harris M Davis
- Center for Quantitative Biodesign, Duke University, Durham, North Carolina 27708, United States
| | - Lingchong You
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, United States
- Center for Quantitative Biodesign, Duke University, Durham, North Carolina 27708, United States
- Center for Biomolecular and Tissue Engineering, Duke University, Durham, North Carolina 27708, United States
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina 27708, United States
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4
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Radde N, Mortensen GA, Bhat D, Shah S, Clements JJ, Leonard SP, McGuffie MJ, Mishler DM, Barrick JE. Measuring the burden of hundreds of BioBricks defines an evolutionary limit on constructability in synthetic biology. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.08.588465. [PMID: 38645188 PMCID: PMC11030366 DOI: 10.1101/2024.04.08.588465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
Engineered DNA will slow the growth of a host cell if it redirects limiting resources or otherwise interferes with homeostasis. Populations of engineered cells can rapidly become dominated by "escape mutants" that evolve to alleviate this burden by inactivating the intended function. Synthetic biologists working with bacteria rely on genetic parts and devices encoded on plasmids, but the burden of different engineered DNA sequences is rarely characterized. We measured how 301 BioBricks on high-copy plasmids affected the growth rate of Escherichia coli . Of these, 59 (19.6%) negatively impacted growth. The burden imposed by engineered DNA is commonly associated with diverting ribosomes or other gene expression factors away from producing endogenous genes that are essential for cellular replication. In line with this expectation, BioBricks exhibiting burden were more likely to contain highly active constitutive promoters and strong ribosome binding sites. By monitoring how much each BioBrick reduced expression of a chromosomal GFP reporter, we found that the burden of most, but not all, BioBricks could be wholly explained by diversion of gene expression resources. Overall, no BioBricks reduced the growth rate of E. coli by >45%, which agreed with a population genetic model that predicts such plasmids should be "unclonable" because escape mutants will take over during growth of a bacterial colony or small laboratory culture from a transformed cell. We made this model available as an interactive web tool for synthetic biology education and added our burden measurements to the iGEM Registry descriptions of each BioBrick.
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5
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Snoeck S, Guidi C, De Mey M. "Metabolic burden" explained: stress symptoms and its related responses induced by (over)expression of (heterologous) proteins in Escherichia coli. Microb Cell Fact 2024; 23:96. [PMID: 38555441 PMCID: PMC10981312 DOI: 10.1186/s12934-024-02370-9] [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: 12/01/2023] [Accepted: 03/18/2024] [Indexed: 04/02/2024] Open
Abstract
BACKGROUND Engineering bacterial strains to redirect the metabolism towards the production of a specific product has enabled the development of industrial biotechnology. However, rewiring the metabolism can have severe implications for a microorganism, rendering cells with stress symptoms such as a decreased growth rate, impaired protein synthesis, genetic instability and an aberrant cell size. On an industrial scale, this is reflected in processes that are not economically viable. MAIN TEXT In literature, most stress symptoms are attributed to "metabolic burden", however the actual triggers and stress mechanisms involved are poorly understood. Therefore, in this literature review, we aimed to get a better insight in how metabolic engineering affects Escherichia coli and link the observed stress symptoms to its cause. Understanding the possible implications that chosen engineering strategies have, will help to guide the reader towards optimising the envisioned process more efficiently. CONCLUSION This review addresses the gap in literature and discusses the triggers and effects of stress mechanisms that can be activated when (over)expressing (heterologous) proteins in Escherichia coli. It uncovers that the activation of the different stress mechanisms is complex and that many are interconnected. The reader is shown that care has to be taken when (over)expressing (heterologous) proteins as the cell's metabolism is tightly regulated.
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Affiliation(s)
- Sofie Snoeck
- Department of Biotechnology, Centre for Synthetic Biology, Coupure Links 653, Gent, 9000, Belgium
| | - Chiara Guidi
- Department of Biotechnology, Centre for Synthetic Biology, Coupure Links 653, Gent, 9000, Belgium
| | - Marjan De Mey
- Department of Biotechnology, Centre for Synthetic Biology, Coupure Links 653, Gent, 9000, Belgium.
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6
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De Marchi D, Shaposhnikov R, Gobaa S, Pastorelli D, Batt G, Magni P, Pasotti L. Design and Model-Driven Analysis of Synthetic Circuits with the Staphylococcus aureus Dead-Cas9 (sadCas9) as a Programmable Transcriptional Regulator in Bacteria. ACS Synth Biol 2024; 13:763-780. [PMID: 38374729 DOI: 10.1021/acssynbio.3c00541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2024]
Abstract
Synthetic circuit design is crucial for engineering microbes that process environmental cues and provide biologically relevant outputs. To reliably scale-up circuit complexity, the availability of parts toolkits is central. Streptococcus pyogenes (sp)-derived CRISPR interference/dead-Cas9 (CRISPRi/spdCas9) is widely adopted for implementing programmable regulations in synthetic circuits, and alternative CRISPRi systems will further expand our toolkits of orthogonal components. Here, we showcase the potential of CRISPRi using the engineered dCas9 from Staphylococcus aureus (sadCas9), not previously used in bacterial circuits, that is attractive for its low size and high specificity. We designed a collection of ∼20 increasingly complex circuits and variants in Escherichia coli, including circuits with static function like one-/two-input logic gates (NOT, NAND), circuits with dynamic behavior like incoherent feedforward loops (iFFLs), and applied sadCas9 to fix a T7 polymerase-based cascade. Data demonstrated specific and efficient target repression (100-fold) and qualitatively successful functioning for all circuits. Other advantageous features included low sadCas9-borne cell load and orthogonality with spdCas9. However, different circuit variants showed quantitatively unexpected and previously unreported steady-state responses: the dynamic range, switch point, and slope of NOT/NAND gates changed for different output promoters, and a multiphasic behavior was observed in iFFLs, differing from the expected bell-shaped or sigmoidal curves. Model analysis explained the observed curves by complex interplays among components, due to reporter gene-borne cell load and regulator competition. Overall, CRISPRi/sadCas9 successfully expanded the available toolkit for bacterial engineering. Analysis of our circuit collection depicted the impact of generally neglected effects modulating the shape of component dose-response curves, to avoid drawing wrong conclusions on circuit functioning.
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Affiliation(s)
- Davide De Marchi
- Department of Electrical, Computer and Biomedical Engineering, University of Pavia, via Ferrata 5, 27100 Pavia, Italy
- Centre for Health Technologies, University of Pavia, via Ferrata 5, 27100 Pavia, Italy
| | - Roman Shaposhnikov
- Department of Electrical, Computer and Biomedical Engineering, University of Pavia, via Ferrata 5, 27100 Pavia, Italy
- Centre for Health Technologies, University of Pavia, via Ferrata 5, 27100 Pavia, Italy
| | - Samy Gobaa
- Institut Pasteur, Université Paris Cité, Biomaterials and Microfluidics Core Facility, 28 Rue du Docteur Roux, 75015 Paris, France
| | - Daniele Pastorelli
- Department of Electrical, Computer and Biomedical Engineering, University of Pavia, via Ferrata 5, 27100 Pavia, Italy
- Centre for Health Technologies, University of Pavia, via Ferrata 5, 27100 Pavia, Italy
| | - Gregory Batt
- Institut Pasteur, Inria, Université Paris Cité, 28 rue du Docteur Roux, 75015 Paris, France
| | - Paolo Magni
- Department of Electrical, Computer and Biomedical Engineering, University of Pavia, via Ferrata 5, 27100 Pavia, Italy
- Centre for Health Technologies, University of Pavia, via Ferrata 5, 27100 Pavia, Italy
| | - Lorenzo Pasotti
- Department of Electrical, Computer and Biomedical Engineering, University of Pavia, via Ferrata 5, 27100 Pavia, Italy
- Centre for Health Technologies, University of Pavia, via Ferrata 5, 27100 Pavia, Italy
- Institut Pasteur, Inria, Université Paris Cité, 28 rue du Docteur Roux, 75015 Paris, France
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7
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Glass DS, Bren A, Vaisbourd E, Mayo A, Alon U. A synthetic differentiation circuit in Escherichia coli for suppressing mutant takeover. Cell 2024; 187:931-944.e12. [PMID: 38320549 PMCID: PMC10882425 DOI: 10.1016/j.cell.2024.01.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 11/27/2023] [Accepted: 01/16/2024] [Indexed: 02/08/2024]
Abstract
Differentiation is crucial for multicellularity. However, it is inherently susceptible to mutant cells that fail to differentiate. These mutants outcompete normal cells by excessive self-renewal. It remains unclear what mechanisms can resist such mutant expansion. Here, we demonstrate a solution by engineering a synthetic differentiation circuit in Escherichia coli that selects against these mutants via a biphasic fitness strategy. The circuit provides tunable production of synthetic analogs of stem, progenitor, and differentiated cells. It resists mutations by coupling differentiation to the production of an essential enzyme, thereby disadvantaging non-differentiating mutants. The circuit selected for and maintained a positive differentiation rate in long-term evolution. Surprisingly, this rate remained constant across vast changes in growth conditions. We found that transit-amplifying cells (fast-growing progenitors) underlie this environmental robustness. Our results provide insight into the stability of differentiation and demonstrate a powerful method for engineering evolutionarily stable multicellular consortia.
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Affiliation(s)
- David S Glass
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel.
| | - Anat Bren
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Elizabeth Vaisbourd
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Avi Mayo
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Uri Alon
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel.
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8
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Stone A, Youssef A, Rijal S, Zhang R, Tian XJ. Context-dependent redesign of robust synthetic gene circuits. Trends Biotechnol 2024:S0167-7799(24)00003-9. [PMID: 38320912 DOI: 10.1016/j.tibtech.2024.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 01/10/2024] [Accepted: 01/11/2024] [Indexed: 02/08/2024]
Abstract
Cells provide dynamic platforms for executing exogenous genetic programs in synthetic biology, resulting in highly context-dependent circuit performance. Recent years have seen an increasing interest in understanding the intricacies of circuit-host relationships, their influence on the synthetic bioengineering workflow, and in devising strategies to alleviate undesired effects. We provide an overview of how emerging circuit-host interactions, such as growth feedback and resource competition, impact both deterministic and stochastic circuit behaviors. We also emphasize control strategies for mitigating these unwanted effects. This review summarizes the latest advances and the current state of host-aware and resource-aware design of synthetic gene circuits.
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Affiliation(s)
- Austin Stone
- School of Biological and Health System Engineering, Arizona State University, Tempe, AZ 85281, USA
| | - Abdelrahaman Youssef
- School of Biological and Health System Engineering, Arizona State University, Tempe, AZ 85281, USA
| | - Sadikshya Rijal
- School of Biological and Health System Engineering, Arizona State University, Tempe, AZ 85281, USA
| | - Rong Zhang
- School of Biological and Health System Engineering, Arizona State University, Tempe, AZ 85281, USA
| | - Xiao-Jun Tian
- School of Biological and Health System Engineering, Arizona State University, Tempe, AZ 85281, USA.
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9
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Huang Y, Wipat A, Bacardit J. Transcriptional biomarker discovery toward building a load stress reporting system for engineered Escherichia coli strains. Biotechnol Bioeng 2024; 121:355-365. [PMID: 37807718 PMCID: PMC10953381 DOI: 10.1002/bit.28567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 09/15/2023] [Accepted: 09/25/2023] [Indexed: 10/10/2023]
Abstract
Foreign proteins are produced by introducing synthetic constructs into host bacteria for biotechnology applications. This process can cause resource competition between synthetic circuits and host cells, placing a metabolic burden on the host cells which may result in load stress and detrimental physiological changes. Consequently, the host bacteria can experience slow growth, and the synthetic system may suffer from suboptimal function. To help in the detection of bacterial load stress, we developed machine-learning strategies to select a minimal number of genes that could serve as biomarkers for the design of load stress reporters. We identified pairs of biomarkers that showed discriminative capacity to detect the load stress states induced in 41 engineered Escherichia coli strains.
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Affiliation(s)
- Yiming Huang
- Interdisciplinary Computing and Complex BioSystems GroupNewcastle UniversityNewcastle upon TyneUK
| | - Anil Wipat
- Interdisciplinary Computing and Complex BioSystems GroupNewcastle UniversityNewcastle upon TyneUK
| | - Jaume Bacardit
- Interdisciplinary Computing and Complex BioSystems GroupNewcastle UniversityNewcastle upon TyneUK
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10
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Arbel-Groissman M, Menuhin-Gruman I, Naki D, Bergman S, Tuller T. Fighting the battle against evolution: designing genetically modified organisms for evolutionary stability. Trends Biotechnol 2023; 41:1518-1531. [PMID: 37442714 DOI: 10.1016/j.tibtech.2023.06.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 06/10/2023] [Accepted: 06/16/2023] [Indexed: 07/15/2023]
Abstract
Synthetic biology has made significant progress in many areas, but a major challenge that has received limited attention is the evolutionary stability of synthetic constructs made of heterologous genes. The expression of these constructs in microorganisms, that is, production of proteins that are not necessary for the organism, is a metabolic burden, leading to a decrease in relative fitness and make the synthetic constructs unstable over time. This is a significant concern for the synthetic biology community, particularly when it comes to bringing this technology out of the laboratory. In this review, we discuss the issue of evolutionary stability in synthetic biology and review the available tools to address this challenge.
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Affiliation(s)
- Matan Arbel-Groissman
- Shmunis School of Biomedicine and Cancer Research, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Itamar Menuhin-Gruman
- School of Mathematical Sciences, The Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Doron Naki
- Shmunis School of Biomedicine and Cancer Research, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Shaked Bergman
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Tamir Tuller
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv 6997801, Israel; The Sagol School of Neuroscience, Tel-Aviv University, Tel Aviv 6997801, Israel.
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11
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Hamrick GS, Maddamsetti R, Son HI, Wilson ML, Davis HM, You L. Programming dynamic division of labor using horizontal gene transfer. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.03.560696. [PMID: 37873187 PMCID: PMC10592921 DOI: 10.1101/2023.10.03.560696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
The metabolic engineering of microbes has broad applications, including in biomanufacturing, bioprocessing, and environmental remediation. The introduction of a complex, multi-step pathway often imposes a substantial metabolic burden on the host cell, restraining the accumulation of productive biomass and limiting pathway efficiency. One strategy to alleviate metabolic burden is division of labor (DOL), in which different subpopulations carry out different parts of the pathway and work together to convert a substrate into a final product. However, the maintenance of different engineered subpopulations is challenging due to competition and convoluted inter-strain population dynamics. Through modeling, we show that dynamic division of labor (DDOL) mediated by horizontal gene transfer (HGT) can overcome these limitations and enable the robust maintenance of burdensome, multi-step pathways. We also use plasmid genomics to uncover evidence that DDOL is a strategy utilized by natural microbial communities. Our work suggests that bioengineers can harness HGT to stabilize synthetic metabolic pathways in microbial communities, enabling the development of robust engineered systems for deployment in a variety of contexts.
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12
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Henrion L, Martinez JA, Vandenbroucke V, Delvenne M, Telek S, Zicler A, Grünberger A, Delvigne F. Fitness cost associated with cell phenotypic switching drives population diversification dynamics and controllability. Nat Commun 2023; 14:6128. [PMID: 37783690 PMCID: PMC10545768 DOI: 10.1038/s41467-023-41917-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 09/23/2023] [Indexed: 10/04/2023] Open
Abstract
Isogenic cell populations can cope with stress conditions by switching to alternative phenotypes. Even if it can lead to increased fitness in a natural context, this feature is typically unwanted for a range of applications (e.g., bioproduction, synthetic biology, and biomedicine) where it tends to make cellular response unpredictable. However, little is known about the diversification profiles that can be adopted by a cell population. Here, we characterize the diversification dynamics for various systems (bacteria and yeast) and for different phenotypes (utilization of alternative carbon sources, general stress response and more complex development patterns). Our results suggest that the diversification dynamics and the fitness cost associated with cell switching are coupled. To quantify the contribution of the switching cost on population dynamics, we design a stochastic model that let us reproduce the dynamics observed experimentally and identify three diversification regimes, i.e., constrained (at low switching cost), dispersed (at medium and high switching cost), and bursty (for very high switching cost). Furthermore, we use a cell-machine interface called Segregostat to demonstrate that different levels of control can be applied to these diversification regimes, enabling applications involving more precise cellular responses.
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Affiliation(s)
- Lucas Henrion
- Terra Research and Teaching Centre, Microbial Processes and Interactions (MiPI), Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
| | - Juan Andres Martinez
- Terra Research and Teaching Centre, Microbial Processes and Interactions (MiPI), Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
| | - Vincent Vandenbroucke
- Terra Research and Teaching Centre, Microbial Processes and Interactions (MiPI), Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
| | - Mathéo Delvenne
- Terra Research and Teaching Centre, Microbial Processes and Interactions (MiPI), Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
| | - Samuel Telek
- Terra Research and Teaching Centre, Microbial Processes and Interactions (MiPI), Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
| | - Andrew Zicler
- Terra Research and Teaching Centre, Microbial Processes and Interactions (MiPI), Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
| | - Alexander Grünberger
- Microsystems in Bioprocess Engineering, Institute of Process Engineering in Life Sciences, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Frank Delvigne
- Terra Research and Teaching Centre, Microbial Processes and Interactions (MiPI), Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium.
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13
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Arcidiacono S, Spangler JR, Litteral V, Doherty LA, Stamps B, Walper S, Goodson M, Soares JW. In Vitro Fermentation Evaluation of Engineered Sense and Respond Probiotics in Polymicrobial Communities. ACS Biomater Sci Eng 2023; 9:5176-5185. [PMID: 37642529 DOI: 10.1021/acsbiomaterials.3c00630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Synthetic biology provides a means of engineering tailored functions into probiotic bacteria. Of particular interest is introducing microbial sense and response functions; however, techniques for testing in physiologically relevant environments, such as those for the intended use, are still lacking. Typically, engineered probiotics are developed and tested in monoculture or in simplified cocultures still within ideal environments. In vitro fermentation models using simplified microbial communities now allow us to simulate engineered organism behavior, specifically organism persistence and intended functionality, within more physiologically relevant, tailored microbial communities. Here, probiotic bacteria Escherichia coli Nissle and Lactobacillus plantarum engineered with sense and response functionalities were evaluated for the ability to persist and function without adverse impact on commensal bacteria within simplified polymicrobial communities with increasing metabolic competition that simulate gut microbe community dynamics. Probiotic abundance and plasmid stability, measured by viability qPCR, decreased for engineered E. coli Nissle relative to monocultures as metabolic competition increased; functional output was not affected. For engineered L. plantarum, abundance and plasmid stability were not adversely impacted; however, functional output was decreased universally as metabolic competition was introduced. For both organisms, adverse effects on select commensals were not evident. Testing engineered probiotics in more physiologically relevant in vitro test beds can provide critical knowledge for circuit design feedback and functional validation prior to the transition to more costly and time-consuming higher-fidelity testing in animal or human studies.
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Affiliation(s)
- Steven Arcidiacono
- Soldier Effectiveness Directorate, US Army DEVCOM Soldier Center, Natick, Massachusetts 01760, United States
| | - Joseph R Spangler
- Center for Bio/Molecular Science & Engineering, US Naval Research Laboratory, Washington, D.C.20375, United States
| | - Vaughn Litteral
- UES Inc, US Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States
| | - Laurel A Doherty
- Soldier Effectiveness Directorate, US Army DEVCOM Soldier Center, Natick, Massachusetts 01760, United States
| | - Blake Stamps
- 711th Human Performance Wing, US Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States
| | - Scott Walper
- Center for Bio/Molecular Science & Engineering, US Naval Research Laboratory, Washington, D.C.20375, United States
| | - Michael Goodson
- 711th Human Performance Wing, US Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States
| | - Jason W Soares
- Soldier Effectiveness Directorate, US Army DEVCOM Soldier Center, Natick, Massachusetts 01760, United States
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14
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Bragdon MDJ, Patel N, Chuang J, Levien E, Bashor CJ, Khalil AS. Cooperative assembly confers regulatory specificity and long-term genetic circuit stability. Cell 2023; 186:3810-3825.e18. [PMID: 37552983 PMCID: PMC10528910 DOI: 10.1016/j.cell.2023.07.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 05/17/2023] [Accepted: 07/10/2023] [Indexed: 08/10/2023]
Abstract
A ubiquitous feature of eukaryotic transcriptional regulation is cooperative self-assembly between transcription factors (TFs) and DNA cis-regulatory motifs. It is thought that this strategy enables specific regulatory connections to be formed in gene networks between otherwise weakly interacting, low-specificity molecular components. Here, using synthetic gene circuits constructed in yeast, we find that high regulatory specificity can emerge from cooperative, multivalent interactions among artificial zinc-finger-based TFs. We show that circuits "wired" using the strategy of cooperative TF assembly are effectively insulated from aberrant misregulation of the host cell genome. As we demonstrate in experiments and mathematical models, this mechanism is sufficient to rescue circuit-driven fitness defects, resulting in genetic and functional stability of circuits in long-term continuous culture. Our naturally inspired approach offers a simple, generalizable means for building high-fidelity, evolutionarily robust gene circuits that can be scaled to a wide range of host organisms and applications.
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Affiliation(s)
- Meghan D J Bragdon
- Biological Design Center, Boston University, Boston, MA 02215, USA; Program in Molecular Biology, Cell Biology and Biochemistry, Boston University, Boston, MA 02215, USA
| | - Nikit Patel
- Biological Design Center, Boston University, Boston, MA 02215, USA; Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
| | - James Chuang
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Ethan Levien
- Department of Mathematics, Dartmouth College, Hanover, NH 03755, USA
| | - Caleb J Bashor
- Department of Bioengineering, Rice University, Houston, TX 77030, USA; Department of Biosciences, Rice University, Houston, TX 77030, USA
| | - Ahmad S Khalil
- Biological Design Center, Boston University, Boston, MA 02215, USA; Program in Molecular Biology, Cell Biology and Biochemistry, Boston University, Boston, MA 02215, USA; Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA; Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA.
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15
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Triassi AJ, Fields BD, Monahan CE, Means JM, Park Y, Doosthosseini H, Padmakumar JP, Isabella VM, Voigt CA. Redesign of an Escherichia coli Nissle treatment for phenylketonuria using insulated genomic landing pads and genetic circuits to reduce burden. Cell Syst 2023; 14:512-524.e12. [PMID: 37348465 DOI: 10.1016/j.cels.2023.05.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 01/18/2023] [Accepted: 05/19/2023] [Indexed: 06/24/2023]
Abstract
To build therapeutic strains, Escherichia coli Nissle (EcN) have been engineered to express antibiotics, toxin-degrading enzymes, immunoregulators, and anti-cancer chemotherapies. For efficacy, the recombinant genes need to be highly expressed, but this imposes a burden on the cell, and plasmids are difficult to maintain in the body. To address these problems, we have developed landing pads in the EcN genome and genetic circuits to control therapeutic gene expression. These tools were applied to EcN SYNB1618, undergoing clinical trials as a phenylketonuria treatment. The pathway for converting phenylalanine to trans-cinnamic acid was moved to a landing pad under the control of a circuit that keeps the pathway off during storage. The resulting strain (EcN SYN8784) achieved higher activity than EcN SYNB1618, reaching levels near when the pathway is carried on a plasmid. This work demonstrates a simple system for engineering EcN that aids quantitative strain design for therapeutics.
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Affiliation(s)
- Alexander J Triassi
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Brandon D Fields
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | | | | | - Yongjin Park
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Hamid Doosthosseini
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jai P Padmakumar
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | | | - Christopher A Voigt
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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16
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Di Blasi R, Pisani M, Tedeschi F, Marbiah MM, Polizzi K, Furini S, Siciliano V, Ceroni F. Resource-aware construct design in mammalian cells. Nat Commun 2023; 14:3576. [PMID: 37328476 PMCID: PMC10275982 DOI: 10.1038/s41467-023-39252-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 06/06/2023] [Indexed: 06/18/2023] Open
Abstract
Resource competition can be the cause of unintended coupling between co-expressed genetic constructs. Here we report the quantification of the resource load imposed by different mammalian genetic components and identify construct designs with increased performance and reduced resource footprint. We use these to generate improved synthetic circuits and optimise the co-expression of transfected cassettes, shedding light on how this can be useful for bioproduction and biotherapeutic applications. This work provides the scientific community with a framework to consider resource demand when designing mammalian constructs to achieve robust and optimised gene expression.
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Affiliation(s)
- Roberto Di Blasi
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London, UK
- Imperial College Centre for Synthetic Biology, South Kensington Campus, London, UK
| | - Mara Pisani
- Synthetic and Systems Biology lab for Biomedicine, Instituto Italiano di Tecnologia-IIT, Largo Barsanti e Matteucci, Naples, Italy
- Open University affiliated centre, Milton Keynes, UK
| | - Fabiana Tedeschi
- Synthetic and Systems Biology lab for Biomedicine, Instituto Italiano di Tecnologia-IIT, Largo Barsanti e Matteucci, Naples, Italy
- University of Naples Federico II, Naples, Italy
| | - Masue M Marbiah
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London, UK
- Imperial College Centre for Synthetic Biology, South Kensington Campus, London, UK
| | - Karen Polizzi
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London, UK
- Imperial College Centre for Synthetic Biology, South Kensington Campus, London, UK
| | - Simone Furini
- Department of Electrical, Electronic and Information Engineering ″Guglielmo Marconi", University of Bologna, Cesena, Italy
| | - Velia Siciliano
- Synthetic and Systems Biology lab for Biomedicine, Instituto Italiano di Tecnologia-IIT, Largo Barsanti e Matteucci, Naples, Italy
| | - Francesca Ceroni
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London, UK.
- Imperial College Centre for Synthetic Biology, South Kensington Campus, London, UK.
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17
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Ingram D, Stan GB. Modelling genetic stability in engineered cell populations. Nat Commun 2023; 14:3471. [PMID: 37308512 DOI: 10.1038/s41467-023-38850-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 05/19/2023] [Indexed: 06/14/2023] Open
Abstract
Predicting the evolution of engineered cell populations is a highly sought-after goal in biotechnology. While models of evolutionary dynamics are far from new, their application to synthetic systems is scarce where the vast combination of genetic parts and regulatory elements creates a unique challenge. To address this gap, we here-in present a framework that allows one to connect the DNA design of varied genetic devices with mutation spread in a growing cell population. Users can specify the functional parts of their system and the degree of mutation heterogeneity to explore, after which our model generates host-aware transition dynamics between different mutation phenotypes over time. We show how our framework can be used to generate insightful hypotheses across broad applications, from how a device's components can be tweaked to optimise long-term protein yield and genetic shelf life, to generating new design paradigms for gene regulatory networks that improve their functionality.
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Affiliation(s)
- Duncan Ingram
- Centre of Excellence in Synthetic Biology and Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Guy-Bart Stan
- Centre of Excellence in Synthetic Biology and Department of Bioengineering, Imperial College London, London, United Kingdom.
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18
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Kong LW, Shi W, Tian XJ, Lai YC. Effects of growth feedback on gene circuits: A dynamical understanding. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.06.543915. [PMID: 37333159 PMCID: PMC10274713 DOI: 10.1101/2023.06.06.543915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
The successful integration of engineered gene circuits into host cells remains a significant challenge in synthetic biology due to circuit-host interactions, such as growth feedback, where the circuit influences cell growth and vice versa. Understanding the dynamics of circuit failures and identifying topologies resilient to growth feedback are crucial for both fundamental and applied research. Utilizing transcriptional regulation circuits with adaptation as a paradigm, we systematically study 435 distinct topological structures and uncover six categories of failures. Three dynamical mechanisms of circuit failures are identified: continuous deformation of the response curve, strengthened or induced oscillations, and sudden switching to coexisting attractors. Our extensive computations also uncover a scaling law between a circuit robustness measure and the strength of growth feedback. Despite the negative effects of growth feedback on the majority of circuit topologies, we identify a few circuits that maintain optimal performance as designed, a feature important for applications.
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19
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Wagner L, Jules M, Borkowski O. What remains from living cells in bacterial lysate-based cell-free systems. Comput Struct Biotechnol J 2023; 21:3173-3182. [PMID: 37333859 PMCID: PMC10275740 DOI: 10.1016/j.csbj.2023.05.025] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 05/23/2023] [Accepted: 05/23/2023] [Indexed: 06/20/2023] Open
Abstract
Because they mimic cells while offering an accessible and controllable environment, lysate-based cell-free systems (CFS) have emerged as valuable biotechnology tools for synthetic biology. Historically used to uncover fundamental mechanisms of life, CFS are nowadays used for a multitude of purposes, including protein production and prototyping of synthetic circuits. Despite the conservation of fundamental functions in CFS like transcription and translation, RNAs and certain membrane-embedded or membrane-bound proteins of the host cell are lost when preparing the lysate. As a result, CFS largely lack some essential properties of living cells, such as the ability to adapt to changing conditions, to maintain homeostasis and spatial organization. Regardless of the application, shedding light on the black-box of the bacterial lysate is necessary to fully exploit the potential of CFS. Most measurements of the activity of synthetic circuits in CFS and in vivo show significant correlations because these only require processes that are preserved in CFS, like transcription and translation. However, prototyping circuits of higher complexity that require functions that are lost in CFS (cell adaptation, homeostasis, spatial organization) will not show such a good correlation with in vivo conditions. Both for prototyping circuits of higher complexity and for building artificial cells, the cell-free community has developed devices to reconstruct cellular functions. This mini-review compares bacterial CFS to living cells, focusing on functional and cellular process differences and the latest developments in restoring lost functions through complementation of the lysate or device engineering.
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20
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Gyorgy A, Menezes A, Arcak M. A blueprint for a synthetic genetic feedback optimizer. Nat Commun 2023; 14:2554. [PMID: 37137895 PMCID: PMC10156725 DOI: 10.1038/s41467-023-37903-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 04/05/2023] [Indexed: 05/05/2023] Open
Abstract
Biomolecular control enables leveraging cells as biomanufacturing factories. Despite recent advancements, we currently lack genetically encoded modules that can be deployed to dynamically fine-tune and optimize cellular performance. Here, we address this shortcoming by presenting the blueprint of a genetic feedback module to optimize a broadly defined performance metric by adjusting the production and decay rate of a (set of) regulator species. We demonstrate that the optimizer can be implemented by combining available synthetic biology parts and components, and that it can be readily integrated with existing pathways and genetically encoded biosensors to ensure its successful deployment in a variety of settings. We further illustrate that the optimizer successfully locates and tracks the optimum in diverse contexts when relying on mass action kinetics-based dynamics and parameter values typical in Escherichia coli.
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Affiliation(s)
- Andras Gyorgy
- Division of Engineering, New York University Abu Dhabi, Abu Dhabi, UAE.
| | - Amor Menezes
- Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL, USA
| | - Murat Arcak
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA, USA
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21
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Montagud-Martínez R, Márquez-Costa R, Rodrigo G. Programmable regulation of translation by harnessing the CRISPR-Cas13 system. Chem Commun (Camb) 2023; 59:2616-2619. [PMID: 36757178 DOI: 10.1039/d3cc00058c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The ability to control protein expression at both the transcriptional and post-transcriptional levels is instrumental for the cell to integrate multiple molecular signals and then reach high operational sophistication. Although challenging, fully artificial regulations at different levels are required for boosting systems and synthetic biology. Here, we report the development of a novel framework to regulate translation by repurposing the CRISPR-Cas13 immune system, which uses an RNA-guided ribonuclease. By exploiting a cell-free expression system for prototyping gene regulatory structures, our results demonstrate that CRISPR-dCas13a ribonucleoproteins (d means catalytically dead) can be programmed to repress or activate translation initiation. The performance assessment of the engineered systems also revealed guide RNA design principles. Moreover, we show that the system can work in vivo. This development complements the ability to regulate transcription with other CRISPR-Cas systems and offers potential applications.
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Affiliation(s)
- Roser Montagud-Martínez
- Institute for Integrative Systems Biology (I2SysBio), CSIC - University of Valencia, 46980, Paterna, Spain.
| | - Rosa Márquez-Costa
- Institute for Integrative Systems Biology (I2SysBio), CSIC - University of Valencia, 46980, Paterna, Spain.
| | - Guillermo Rodrigo
- Institute for Integrative Systems Biology (I2SysBio), CSIC - University of Valencia, 46980, Paterna, Spain.
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22
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Heieck K, Arnold ND, Brück TB. Metabolic stress constrains microbial L-cysteine production in Escherichia coli by accelerating transposition through mobile genetic elements. Microb Cell Fact 2023; 22:10. [PMID: 36642733 PMCID: PMC9841684 DOI: 10.1186/s12934-023-02021-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 01/09/2023] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND L-cysteine is an essential chemical building block in the pharmaceutical-, cosmetic-, food and agricultural sector. Conventionally, L-cysteine production relies on the conversion of keratinous biomass mediated by hydrochloric acid. Today, fermentative production based on recombinant E. coli, where L-cysteine production is streamlined and facilitated by synthetic plasmid constructs, is an alternative process at industrial scale. However, metabolic stress and the resulting production escape mechanisms in evolving populations are severely limiting factors during industrial biomanufacturing. We emulate high generation numbers typically reached in industrial fermentation processes with Escherichia coli harbouring L-cysteine production plasmid constructs. So far no genotypic and phenotypic alterations in early and late L-cysteine producing E. coli populations have been studied. RESULTS In a comparative experimental design, the E. coli K12 production strain W3110 and the reduced genome strain MDS42, almost free of insertion sequences, were used as hosts. Data indicates that W3110 populations acquire growth fitness at the expense of L-cysteine productivity within 60 generations, while production in MDS42 populations remains stable. For the first time, the negative impact of predominantly insertion sequence family 3 and 5 transposases on L-cysteine production is reported, by combining differential transcriptome analysis with NGS based deep plasmid sequencing. Furthermore, metabolic clustering of differentially expressed genes supports the hypothesis, that metabolic stress induces rapid propagation of plasmid rearrangements, leading to reduced L-cysteine yields in evolving populations over industrial fermentation time scales. CONCLUSION The results of this study implicate how selective deletion of insertion sequence families could be a new route for improving industrial L-cysteine or even general amino acid production using recombinant E. coli hosts. Instead of using minimal genome strains, a selective deletion of certain IS families could offer the benefits of adaptive laboratory evolution (ALE) while maintaining enhanced L-cysteine production stability.
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Affiliation(s)
- Kevin Heieck
- grid.6936.a0000000123222966Technische Universität München, Lichtenbergstraße 4, 85748 Garching, Germany
| | - Nathanael David Arnold
- grid.6936.a0000000123222966Technische Universität München, Lichtenbergstraße 4, 85748 Garching, Germany
| | - Thomas Bartholomäus Brück
- grid.6936.a0000000123222966Technische Universität München, Lichtenbergstraße 4, 85748 Garching, Germany
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23
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Genomically mined acoustic reporter genes for real-time in vivo monitoring of tumors and tumor-homing bacteria. Nat Biotechnol 2023:10.1038/s41587-022-01581-y. [PMID: 36593411 DOI: 10.1038/s41587-022-01581-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 10/20/2022] [Indexed: 01/03/2023]
Abstract
Ultrasound allows imaging at a much greater depth than optical methods, but existing genetically encoded acoustic reporters for in vivo cellular imaging have been limited by poor sensitivity, specificity and in vivo expression. Here we describe two acoustic reporter genes (ARGs)-one for use in bacteria and one for use in mammalian cells-identified through a phylogenetic screen of candidate gas vesicle gene clusters from diverse bacteria and archaea that provide stronger ultrasound contrast, produce non-linear signals distinguishable from background tissue and have stable long-term expression. Compared to their first-generation counterparts, these improved bacterial and mammalian ARGs produce 9-fold and 38-fold stronger non-linear contrast, respectively. Using these new ARGs, we non-invasively imaged in situ tumor colonization and gene expression in tumor-homing therapeutic bacteria, tracked the progression of tumor gene expression and growth in a mouse model of breast cancer, and performed gene-expression-guided needle biopsies of a genetically mosaic tumor, demonstrating non-invasive access to dynamic biological processes at centimeter depth.
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24
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Abstract
Future applications of synthetic biology will rely on deploying engineered cells outside of lab environments for long periods of time. Currently, a significant roadblock to this application is the potential for deactivating mutations in engineered genes. A recently developed method to protect engineered coding sequences from mutation is called Constraining Adaptive Mutations using Engineered Overlapping Sequences (CAMEOS). In this chapter we provide a workflow for utilizing CAMEOS to create synthetic overlaps between two genes, one essential (infA) and one non-essential (aroB), to protect the non-essential gene from mutation and loss of protein function. In this workflow we detail the methods to collect large numbers of related protein sequences, produce multiple sequence alignments (MSAs), use the MSAs to generate hidden Markov models and Markov random field models, and finally generate a library of overlapping coding sequences through CAMEOS scripts. To assist practitioners with basic coding skills to try out the CAMEOS method, we have created a virtual machine containing all the required packages already installed that can be downloaded and run locally.
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Affiliation(s)
- Dominic Y Logel
- School of Natural Sciences, Macquarie University, Sydney, NSW, Australia
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW, Australia
| | - Paul R Jaschke
- School of Natural Sciences, Macquarie University, Sydney, NSW, Australia.
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW, Australia.
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25
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Stone A, Ryan J, Tang X, Tian XJ. Negatively Competitive Incoherent Feedforward Loops Mitigate Winner-Take-All Resource Competition. ACS Synth Biol 2022; 11:3986-3995. [PMID: 36355441 DOI: 10.1021/acssynbio.2c00318] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The effects of host resource limitations on the function of synthetic gene circuits have gained significant attention over the past years. Hosts, having evolved resource capacities optimal for their own genome, have been repeatedly demonstrated to suffer from the added burden of synthetic genetic programs, which may in return pose deleterious effects on the circuit's function. Three resource controller archetypes have been proposed previously to mitigate resource distribution problems in dynamic circuits: the local controller, the global controller, and a "negatively competitive" regulatory (NCR) controller that utilizes synthetic competition to combat resource competition. The dynamics of negative feedback forms of these controllers have been previously investigated, and here we extend the analysis of these resource allocation strategies to the incoherent feedforward loop (iFFL) topology. We demonstrate that the three iFFL controllers can attenuate Winner-Take-All resource competition between two bistable switches. We uncover that the parameters associated with the synthetic competition in the NCR iFFL controller are paramount to its increased efficacy over the local controller type, while the global controllers demonstrate to be relatively ineffectual. Interestingly, unlike the negative feedback counterpart topologies, iFFL controllers exhibit a unique coupling of switch activation thresholds which we term the "coactivation threshold shift" effect. Finally, we demonstrate that a nearly fully orthogonal set of bistable switches could be achieved by pairing an NCR controller with an appropriate level of controller resource consumption.
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Affiliation(s)
- Austin Stone
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona85281, United States
| | - Jordan Ryan
- Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, Louisiana70803, United States
| | - Xun Tang
- Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, Louisiana70803, United States
| | - Xiao-Jun Tian
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona85281, United States
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26
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Chemla Y, Dorfan Y, Yannai A, Meng D, Cao P, Glaven S, Gordon DB, Elbaz J, Voigt CA. Parallel engineering of environmental bacteria and performance over years under jungle-simulated conditions. PLoS One 2022; 17:e0278471. [PMID: 36516154 PMCID: PMC9750038 DOI: 10.1371/journal.pone.0278471] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Accepted: 11/15/2022] [Indexed: 12/15/2022] Open
Abstract
Engineered bacteria could perform many functions in the environment, for example, to remediate pollutants, deliver nutrients to crops or act as in-field biosensors. Model organisms can be unreliable in the field, but selecting an isolate from the thousands that naturally live there and genetically manipulating them to carry the desired function is a slow and uninformed process. Here, we demonstrate the parallel engineering of isolates from environmental samples by using the broad-host-range XPORT conjugation system (Bacillus subtilis mini-ICEBs1) to transfer a genetic payload to many isolates in parallel. Bacillus and Lysinibacillus species were obtained from seven soil and water samples from different locations in Israel. XPORT successfully transferred a genetic function (reporter expression) into 25 of these isolates. They were then screened to identify the best-performing chassis based on the expression level, doubling time, functional stability in soil, and environmentally-relevant traits of its closest annotated reference species, such as the ability to sporulate and temperature tolerance. From this library, we selected Bacillus frigoritolerans A3E1, re-introduced it to soil, and measured function and genetic stability in a contained environment that replicates jungle conditions. After 21 months of storage, the engineered bacteria were viable, could perform their function, and did not accumulate disruptive mutations.
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Affiliation(s)
- Yonatan Chemla
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Yuval Dorfan
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Adi Yannai
- School of Molecular Cell Biology & Biotechnology, Faculty of Life Science, Tel Aviv University, Tel Aviv, Israel
| | - Dechuan Meng
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Paul Cao
- The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
| | - Sarah Glaven
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington, DC, United States of America
| | - D. Benjamin Gordon
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
| | - Johann Elbaz
- School of Molecular Cell Biology & Biotechnology, Faculty of Life Science, Tel Aviv University, Tel Aviv, Israel
| | - Christopher A. Voigt
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
- * E-mail:
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27
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Huang Y, Sinha N, Wipat A, Bacardit J. A knowledge integration strategy for the selection of a robust multi-stress biomarkers panel for Bacillus subtilis. Synth Syst Biotechnol 2022; 8:97-106. [PMID: 36605706 PMCID: PMC9794971 DOI: 10.1016/j.synbio.2022.12.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 11/29/2022] [Accepted: 12/11/2022] [Indexed: 12/15/2022] Open
Abstract
One challenge in the engineering of biological systems is to be able to recognise the cellular stress states of bacterial hosts, as these stress states can lead to suboptimal growth and lower yields of target products. To enable the design of genetic circuits for reporting or mitigating the stress states, it is important to identify a relatively reduced set of gene biomarkers that can reliably indicate relevant cellular growth states in bacteria. Recent advances in high-throughput omics technologies have enhanced the identification of molecular biomarkers specific states in bacteria, motivating computational methods that can identify robust biomarkers for experimental characterisation and verification. Focused on identifying gene expression biomarkers to sense various stress states in Bacillus subtilis, this study aimed to design a knowledge integration strategy for the selection of a robust biomarker panel that generalises on external datasets and experiments. We developed a recommendation system that ranks the candidate biomarker panels based on complementary information from machine learning model, gene regulatory network and co-expression network. We identified a recommended biomarker panel showing high stress sensing power for a variety of conditions both in the dataset used for biomarker identification (mean f1-score achieved at 0.99), as well as in a range of independent datasets (mean f1-score achieved at 0.98). We discovered a significant correlation between stress sensing power and evaluation metrics such as the number of associated regulators in a B. subtilis gene regulatory network (GRN) and the number of associated modules in a B. subtilis co-expression network (CEN). GRNs and CENs provide information relevant to the diversity of biological processes encoded by biomarker genes. We demonstrate that quantitatively relating meaningful evaluation metrics with stress sensing power has the potential for recognising biomarkers that show better sensitivity and robustness to an extended set of stress conditions and enable a more reliable biomarker panel selection.
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Affiliation(s)
- Yiming Huang
- Interdisciplinary Computing and Complex BioSystems (ICOS) Group, School of Computing, Newcastle University, UK,Corresponding authors.
| | - Nishant Sinha
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, USA
| | - Anil Wipat
- Interdisciplinary Computing and Complex BioSystems (ICOS) Group, School of Computing, Newcastle University, UK
| | - Jaume Bacardit
- Interdisciplinary Computing and Complex BioSystems (ICOS) Group, School of Computing, Newcastle University, UK,Corresponding authors.
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Sri Wahyu Effendi S, Lin JY, Ng IS. Simultaneous carbon dioxide sequestration and utilization for cadaverine production using dual promoters in engineered Escherichia coli strains. BIORESOURCE TECHNOLOGY 2022; 363:127980. [PMID: 36137445 DOI: 10.1016/j.biortech.2022.127980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 09/10/2022] [Accepted: 09/12/2022] [Indexed: 06/16/2023]
Abstract
Human carbonic anhydrase II (hCAII) is a rapid-acting zinc-metalloenzyme that catalyzes CO2 hydration reversibly, with encouraging applications in carbon capture, sequestration, and utilization (CCSU). However, biocatalyst durability is a major challenge. Herein, hCAII is emphasized in 4 different Escherichia coli strains and designated under dual promoters from sigma factor 70 (σ70) and heat shock protein (HSP70A) to suppress the usage of inducer and stimulate activity in heat environments. As a result, hCAII under high-efficient dual promoters regulation retained high residual activity in CO2 biomineralization of 68.8 % after 4 cycles at 40 °C. Moreover, co-expression of CAC9 with lysine decarboxylase (CadA) simultaneously sequestered CO2 release up to 95.7 % and increased cadaverine titer from 18.0 to 36.7 g/L by using E. coli MG1655. The remnant biomass from cadaverine synthesis sustained converting CO2 to 57.9 mg-CaCO3. Thus, the dual promoters design demonstrated the promising potential for CCSU through simultaneous CO2 utilization and cadaverine synthesis.
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Affiliation(s)
| | - Jia-Yi Lin
- Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan
| | - I-Son Ng
- Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan.
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29
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Lee TA, Steel H. Cybergenetic control of microbial community composition. Front Bioeng Biotechnol 2022; 10:957140. [PMID: 36277404 PMCID: PMC9582452 DOI: 10.3389/fbioe.2022.957140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 09/20/2022] [Indexed: 11/13/2022] Open
Abstract
The use of bacterial communities in bioproduction instead of monocultures has potential advantages including increased productivity through division of labour, ability to utilise cheaper substrates, and robustness against perturbations. A key challenge in the application of engineered bacterial communities is the ability to reliably control the composition of the community in terms of its constituent species. This is crucial to prevent faster growing species from outcompeting others with a lower relative fitness, and to ensure that all species are present at an optimal ratio during different steps in a biotechnological process. In contrast to purely biological approaches such as synthetic quorum sensing circuits or paired auxotrophies, cybergenetic control techniques - those in which computers interface with living cells-are emerging as an alternative approach with many advantages. The community composition is measured through methods such as fluorescence intensity or flow cytometry, with measured data fed real-time into a computer. A control action is computed using a variety of possible control algorithms and then applied to the system, with actuation taking the form of chemical (e.g., inducers, nutrients) or physical (e.g., optogenetic, mechanical) inputs. Subsequent changes in composition are then measured and the cycle repeated, maintaining or driving the system to a desired state. This review discusses recent and future developments in methods for implementing cybergenetic control systems, contrasts their capabilities with those of traditional biological methods of population control, and discusses future directions and outstanding challenges for the field.
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30
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Moschner C, Wedd C, Bakshi S. The context matrix: Navigating biological complexity for advanced biodesign. Front Bioeng Biotechnol 2022; 10:954707. [PMID: 36082163 PMCID: PMC9445834 DOI: 10.3389/fbioe.2022.954707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 06/29/2022] [Indexed: 12/05/2022] Open
Abstract
Synthetic biology offers many solutions in healthcare, production, sensing and agriculture. However, the ability to rationally engineer synthetic biosystems with predictable and robust functionality remains a challenge. A major reason is the complex interplay between the synthetic genetic construct, its host, and the environment. Each of these contexts contains a number of input factors which together can create unpredictable behaviours in the engineered biosystem. It has become apparent that for the accurate assessment of these contextual effects a more holistic approach to design and characterisation is required. In this perspective article, we present the context matrix, a conceptual framework to categorise and explore these contexts and their net effect on the designed synthetic biosystem. We propose the use and community-development of the context matrix as an aid for experimental design that simplifies navigation through the complex design space in synthetic biology.
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Jadhav P, Chen Y, Butzin N, Buceta J, Urchueguía A. Bacterial degrons in synthetic circuits. Open Biol 2022; 12:220180. [PMID: 35975648 PMCID: PMC9382460 DOI: 10.1098/rsob.220180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bacterial proteases are a promising post-translational regulation strategy in synthetic circuits because they recognize specific amino acid degradation tags (degrons) that can be fine-tuned to modulate the degradation levels of tagged proteins. For this reason, recent efforts have been made in the search for new degrons. Here we review the up-to-date applications of degradation tags for circuit engineering in bacteria. In particular, we pay special attention to the effects of degradation bottlenecks in synthetic oscillators and introduce mathematical approaches to study queueing that enable the quantitative modelling of proteolytic queues.
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Affiliation(s)
- Prajakta Jadhav
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD, USA
| | - Yanyan Chen
- Program for Computational and Systems Biology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Nicholas Butzin
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD, USA
| | - Javier Buceta
- Institute for Integrative Systems Biology (I2SysBio, CSIC-UV), Paterna, Valencia 46980, Spain
| | - Arantxa Urchueguía
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD, USA.,Institute for Integrative Systems Biology (I2SysBio, CSIC-UV), Paterna, Valencia 46980, Spain
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32
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Abstract
The invention of the Fourier integral in the 19th century laid the foundation for modern spectral analysis methods. This integral decomposes a temporal signal into its frequency components, providing deep insights into its generating process. While this idea has precipitated several scientific and technological advances, its impact has been fairly limited in cell biology, largely due to the difficulties in connecting the underlying noisy intracellular networks to the frequency content of observed single-cell trajectories. Here we develop a spectral theory and computational methodologies tailored specifically to the computation and analysis of frequency spectra of noisy intracellular networks. Specifically, we develop a method to compute the frequency spectrum for general nonlinear networks, and for linear networks we present a decomposition that expresses the frequency spectrum in terms of its sources. Several examples are presented to illustrate how our results provide frequency-based methods for the design and analysis of noisy intracellular networks. The invention of the Fourier integral in the 19th century laid the foundation for modern spectral analysis methods. Here the authors develop frequency-based methods for analyzing the reaction mechanisms within living cells from distinctively noisy single-cell output trajectories and present forward engineering of synthetic oscillators and controllers.
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33
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Bongaerts N, Edoo Z, Abukar AA, Song X, Sosa-Carrillo S, Haggenmueller S, Savigny J, Gontier S, Lindner AB, Wintermute EH. Low-cost anti-mycobacterial drug discovery using engineered E. coli. Nat Commun 2022; 13:3905. [PMID: 35798732 PMCID: PMC9262897 DOI: 10.1038/s41467-022-31570-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 06/23/2022] [Indexed: 12/29/2022] Open
Abstract
Whole-cell screening for Mycobacterium tuberculosis (Mtb) inhibitors is complicated by the pathogen's slow growth and biocontainment requirements. Here we present a synthetic biology framework for assaying Mtb drug targets in engineered E. coli. We construct Target Essential Surrogate E. coli (TESEC) in which an essential metabolic enzyme is deleted and replaced with an Mtb-derived functional analog, linking bacterial growth to the activity of the target enzyme. High throughput screening of a TESEC model for Mtb alanine racemase (Alr) revealed benazepril as a targeted inhibitor, a result validated in whole-cell Mtb. In vitro biochemical assays indicated a noncompetitive mechanism unlike that of clinical Alr inhibitors. We establish the scalability of TESEC for drug discovery by characterizing TESEC strains for four additional targets.
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Affiliation(s)
- Nadine Bongaerts
- Université Paris Cité, Inserm, System Engineering and Evolution Dynamics, Paris, France.,CRI, Paris, France
| | - Zainab Edoo
- Sorbonne Université, Université Paris Cité, Inserm, Centre de Recherche des Cordeliers (CRC), Paris, France
| | - Ayan A Abukar
- Université Paris Cité, Inserm, System Engineering and Evolution Dynamics, Paris, France.,CRI, Paris, France
| | - Xiaohu Song
- Université Paris Cité, Inserm, System Engineering and Evolution Dynamics, Paris, France.,CRI, Paris, France
| | - Sebastián Sosa-Carrillo
- Université Paris Cité, Inserm, System Engineering and Evolution Dynamics, Paris, France.,Institut Pasteur, Inria de Paris, Université Paris Cité, InBio, Paris, France
| | - Sarah Haggenmueller
- Université Paris Cité, Inserm, System Engineering and Evolution Dynamics, Paris, France.,CRI, Paris, France
| | - Juline Savigny
- Université Paris Cité, Inserm, System Engineering and Evolution Dynamics, Paris, France.,CRI, Paris, France
| | - Sophie Gontier
- Université Paris Cité, Inserm, System Engineering and Evolution Dynamics, Paris, France.,CRI, Paris, France
| | - Ariel B Lindner
- Université Paris Cité, Inserm, System Engineering and Evolution Dynamics, Paris, France. .,CRI, Paris, France.
| | - Edwin H Wintermute
- Université Paris Cité, Inserm, System Engineering and Evolution Dynamics, Paris, France. .,CRI, Paris, France.
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Guan Y, Chen X, Shao B, Ji X, Xiang Y, Jiang G, Xu L, Lin Z, Ouyang Q, Lou C. Mitigating Host Burden of Genetic Circuits by Engineering Autonegatively Regulated Parts and Improving Functional Prediction. ACS Synth Biol 2022; 11:2361-2371. [PMID: 35772024 DOI: 10.1021/acssynbio.2c00073] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Mitigating unintended interferences between circuits and host cells is key to realize applications of synthetic regulatory systems both for bacteria and mammalian cells. Here, we demonstrated that growth burden and circuit dysregulation occurred in a concentration-dependent manner for specific transcription factors (CymR*/CymR) in E.coli, and direct negative feedback modules were able to control the concentration of CymR*/CymR, mitigate growth burden, and restore circuit functions. A quantitative design scheme was developed for circuits embedded with autorepression modules. Four key parameters were theoretically identified to determine the performance of autoregulated switches and were experimentally modified by fine-tuning promoter architectures and cooperativity. Using this strategy, we synthesized a number of switches and demonstrated its improvement of product titers and host growth controlling the complex deoxyviolacein biosynthesis pathway. Furthermore, we restored functions of a dysregulated multilayer NOR gate by integrating autorepression modules. Our work provides a blueprint for engineering host-adaptable synthetic systems.
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Affiliation(s)
- Ying Guan
- Department of Chemical Engineering, Tsinghua University, Beijing 100871, China.,Center for Quantitative Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Physics, Peking University, Beijing 100871, China
| | - Xinmao Chen
- Center for Quantitative Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Physics, Peking University, Beijing 100871, China
| | - Bin Shao
- Center for Quantitative Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Physics, Peking University, Beijing 100871, China
| | - Xiangyu Ji
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.,College of Life Science, University of Chinese Academy of Science, Beijing 100149, China
| | - Yanhui Xiang
- Center for Cell and Gene Circuit Design, CAS Key Laboratory of Quantitative Engineering Biology, Guangdong Provincial Key Laboratory of Synthetic Genomics, Shenzhen Key Laboratory of Synthetic Genomics, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Guoqiang Jiang
- Department of Chemical Engineering, Tsinghua University, Beijing 100871, China
| | - Lina Xu
- National Protein Science Facility, Tsinghua University, Beijing 100871, China
| | - Zhanglin Lin
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Qi Ouyang
- Center for Quantitative Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Physics, Peking University, Beijing 100871, China
| | - Chunbo Lou
- Center for Cell and Gene Circuit Design, CAS Key Laboratory of Quantitative Engineering Biology, Guangdong Provincial Key Laboratory of Synthetic Genomics, Shenzhen Key Laboratory of Synthetic Genomics, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.,College of Life Science, University of Chinese Academy of Science, Beijing 100149, China
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35
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Atkinson E, Tuza Z, Perrino G, Stan GB, Ledesma-Amaro R. Resource-aware whole-cell model of division of labour in a microbial consortium for complex-substrate degradation. Microb Cell Fact 2022; 21:115. [PMID: 35698129 PMCID: PMC9195437 DOI: 10.1186/s12934-022-01842-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 05/30/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Low-cost sustainable feedstocks are essential for commercially viable biotechnologies. These feedstocks, often derived from plant or food waste, contain a multitude of different complex biomolecules which require multiple enzymes to hydrolyse and metabolise. Current standard biotechnology uses monocultures in which a single host expresses all the proteins required for the consolidated bioprocess. However, these hosts have limited capacity for expressing proteins before growth is impacted. This limitation may be overcome by utilising division of labour (DOL) in a consortium, where each member expresses a single protein of a longer degradation pathway. RESULTS Here, we model a two-strain consortium, with one strain expressing an endohydrolase and a second strain expressing an exohydrolase, for cooperative degradation of a complex substrate. Our results suggest that there is a balance between increasing expression to enhance degradation versus the burden that higher expression causes. Once a threshold of burden is reached, the consortium will consistently perform better than an equivalent single-cell monoculture. CONCLUSIONS We demonstrate that resource-aware whole-cell models can be used to predict the benefits and limitations of using consortia systems to overcome burden. Our model predicts the region of expression where DOL would be beneficial for growth on starch, which will assist in making informed design choices for this, and other, complex-substrate degradation pathways.
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Affiliation(s)
- Eliza Atkinson
- Department of Bioengineering and Imperial College Centre for Synthetic Biology, Imperial College London, London, SW72AZ, UK
| | - Zoltan Tuza
- Department of Bioengineering and Imperial College Centre for Synthetic Biology, Imperial College London, London, SW72AZ, UK
| | - Giansimone Perrino
- Department of Bioengineering and Imperial College Centre for Synthetic Biology, Imperial College London, London, SW72AZ, UK
| | - Guy-Bart Stan
- Department of Bioengineering and Imperial College Centre for Synthetic Biology, Imperial College London, London, SW72AZ, UK.
| | - Rodrigo Ledesma-Amaro
- Department of Bioengineering and Imperial College Centre for Synthetic Biology, Imperial College London, London, SW72AZ, UK.
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36
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Yang SC, Ting WW, Ng IS. Effective whole cell biotransformation of arginine to a four-carbon diamine putrescine using engineered Escherichia coli. Biochem Eng J 2022. [DOI: 10.1016/j.bej.2022.108502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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37
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Davenport BI, Tica J, Isalan M. Reducing metabolic burden in the PACEmid evolver system by remastering high-copy phagemid vectors. ENGINEERING BIOLOGY 2022; 6:50-61. [PMID: 36969104 PMCID: PMC9996709 DOI: 10.1049/enb2.12021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 04/07/2022] [Accepted: 04/20/2022] [Indexed: 01/12/2023] Open
Abstract
Orthogonal or non-cross-reacting transcription factors are used in synthetic biology as components of genetic circuits. Brödel et al. (2016) engineered 12 such cIλ transcription factor variants using a directed evolution 'PACEmid' system. The variants operate as dual activator/repressors and expand gene circuit construction possibilities. However, the high-copy phagemid vectors carrying the cIλ variants imposed high metabolic burden upon cells. Here, the authors 'remaster' the phagemid backbones to relieve their burden substantially, exhibited by a recovery in Escherichia coli growth. The remastered phagemids' ability to function within the PACEmid evolver system is maintained, as is the cIλ transcription factors' activity within these vectors. The low-burden phagemid versions are more suitable for use in PACEmid experiments and synthetic gene circuits; the authors have, therefore, replaced the original high-burden phagemids on the Addgene repository. The authors' work emphasises the importance of understanding metabolic burden and incorporating it into design steps in future synthetic biology ventures.
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Affiliation(s)
- Beth India Davenport
- Department of Life SciencesImperial College LondonSouth Kensington CampusLondonUK
| | - Jure Tica
- Department of Life SciencesImperial College LondonSouth Kensington CampusLondonUK
| | - Mark Isalan
- Department of Life SciencesImperial College LondonSouth Kensington CampusLondonUK
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38
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Calabrese L, Grilli J, Osella M, Kempes CP, Lagomarsino MC, Ciandrini L. Protein degradation sets the fraction of active ribosomes at vanishing growth. PLoS Comput Biol 2022; 18:e1010059. [PMID: 35500024 PMCID: PMC9098079 DOI: 10.1371/journal.pcbi.1010059] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 05/12/2022] [Accepted: 03/26/2022] [Indexed: 11/19/2022] Open
Abstract
Growing cells adopt common basic strategies to achieve optimal resource allocation under limited resource availability. Our current understanding of such “growth laws” neglects degradation, assuming that it occurs slowly compared to the cell cycle duration. Here we argue that this assumption cannot hold at slow growth, leading to important consequences. We propose a simple framework showing that at slow growth protein degradation is balanced by a fraction of “maintenance” ribosomes. Consequently, active ribosomes do not drop to zero at vanishing growth, but as growth rate diminishes, an increasing fraction of active ribosomes performs maintenance. Through a detailed analysis of compiled data, we show that the predictions of this model agree with data from E. coli and S. cerevisiae. Intriguingly, we also find that protein degradation increases at slow growth, which we interpret as a consequence of active waste management and/or recycling. Our results highlight protein turnover as an underrated factor for our understanding of growth laws across kingdoms. The idea that simple quantitative relationships relate cell physiology to cellular composition dates back to the 1950s, but the recent years saw a leap in our understanding of such “growth laws”, with relevant implications regarding the interdependence between growth, metabolism and biochemical networks. However, recent works on nutrient-limited growth mainly focused on laboratory conditions that are favourable to growth. Thus, our current mathematical understanding of the growth laws neglects protein degradation, under the argument that it occurs slowly compared to the timescale of the cell cycle. Instead, at slow growth the timescales of mass loss from protein degradation and dilution become comparable. In this work, we propose that protein degradation shapes the quantitative relationships between ribosome allocation and growth rate, and determines a fraction of ribosomes that do not contribute to growth and need to remain active to balance degradation.
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Affiliation(s)
- Ludovico Calabrese
- IFOM Foundation, FIRC Institute for Molecular Oncology, Milan, Italy
- * E-mail: (LCa); (MCL); (LCi)
| | - Jacopo Grilli
- Quantitative Life Sciences section, The Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy
| | - Matteo Osella
- Dipartimento di Fisica, Università di Torino and INFN, Turin, Italy
- INFN sezione di Torino, Turin, Italy
| | | | - Marco Cosentino Lagomarsino
- IFOM Foundation, FIRC Institute for Molecular Oncology, Milan, Italy
- Dipartimento di Fisica, Università degli Studi di Milano, Milan, Italy
- INFN sezione di Milano, Milan, Italy
- * E-mail: (LCa); (MCL); (LCi)
| | - Luca Ciandrini
- CBS (Centre de Biologie Structurale), Université de Montpellier, CNRS, INSERM, Montpellier, France
- * E-mail: (LCa); (MCL); (LCi)
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van der Linden AJ, Pieters PA, Bartelds MW, Nathalia BL, Yin P, Huck WTS, Kim J, de Greef TFA. DNA Input Classification by a Riboregulator-Based Cell-Free Perceptron. ACS Synth Biol 2022; 11:1510-1520. [PMID: 35381174 PMCID: PMC9016768 DOI: 10.1021/acssynbio.1c00596] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The ability to recognize molecular patterns is essential for the continued survival of biological organisms, allowing them to sense and respond to their immediate environment. The design of synthetic gene-based classifiers has been explored previously; however, prior strategies have focused primarily on DNA strand-displacement reactions. Here, we present a synthetic in vitro transcription and translation (TXTL)-based perceptron consisting of a weighted sum operation (WSO) coupled to a downstream thresholding function. We demonstrate the application of toehold switch riboregulators to construct a TXTL-based WSO circuit that converts DNA inputs into a GFP output, the concentration of which correlates to the input pattern and the corresponding weights. We exploit the modular nature of the WSO circuit by changing the output protein to the Escherichia coli σ28-factor, facilitating the coupling of the WSO output to a downstream reporter network. The subsequent introduction of a σ28 inhibitor enabled thresholding of the WSO output such that the expression of the downstream reporter protein occurs only when the produced σ28 exceeds this threshold. In this manner, we demonstrate a genetically implemented perceptron capable of binary classification, i.e., the expression of a single output protein only when the desired minimum number of inputs is exceeded.
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Affiliation(s)
- Ardjan J. van der Linden
- Laboratory of Chemical Biology and Institute for Complex Molecular Systems, Department of Biomedical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
- Computational Biology Group, Department of Biomedical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
| | - Pascal A. Pieters
- Laboratory of Chemical Biology and Institute for Complex Molecular Systems, Department of Biomedical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
- Computational Biology Group, Department of Biomedical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
| | - Mart W. Bartelds
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, The Netherlands
| | - Bryan L. Nathalia
- Computational Biology Group, Department of Biomedical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
| | - Peng Yin
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts 02115, United States
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Wilhelm T. S. Huck
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, The Netherlands
| | - Jongmin Kim
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, Republic of Korea
| | - Tom F. A. de Greef
- Laboratory of Chemical Biology and Institute for Complex Molecular Systems, Department of Biomedical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
- Computational Biology Group, Department of Biomedical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, The Netherlands
- Center for Living Technologies, Eindhoven-Wageningen-Utrecht Alliance, 3584 CB Utrecht, The Netherlands
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40
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Schwaiger KN, Voit A, Wiltschi B, Nidetzky B. Engineering cascade biocatalysis in whole cells for bottom-up synthesis of cello-oligosaccharides: flux control over three enzymatic steps enables soluble production. Microb Cell Fact 2022; 21:61. [PMID: 35397553 PMCID: PMC8994397 DOI: 10.1186/s12934-022-01781-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 03/24/2022] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Soluble cello-oligosaccharides (COS, β-1,4-D-gluco-oligosaccharides with degree of polymerization DP 2-6) have been receiving increased attention in different industrial sectors, from food and feed to cosmetics. Development of large-scale COS applications requires cost-effective technologies for their production. Cascade biocatalysis by the three enzymes sucrose-, cellobiose- and cellodextrin phosphorylase is promising because it enables bottom-up synthesis of COS from expedient substrates such as sucrose and glucose. A whole-cell-derived catalyst that incorporates the required enzyme activities from suitable co-expression would represent an important step towards making the cascade reaction fit for production. Multi-enzyme co-expression to reach distinct activity ratios is challenging in general, but it requires special emphasis for the synthesis of COS. Only a finely tuned balance between formation and elongation of the oligosaccharide precursor cellobiose results in the desired COS. RESULTS Here, we show the integration of cellodextrin phosphorylase into a cellobiose-producing whole-cell catalyst. We arranged the co-expression cassettes such that their expression levels were upregulated. The most effective strategy involved a custom vector design that placed the coding sequences for cellobiose phosphorylase (CbP), cellodextrin phosphorylase (CdP) and sucrose phosphorylase (ScP) in a tricistron in the given order. The expression of the tricistron was controlled by the strong T7lacO promoter and strong ribosome binding sites (RBS) for each open reading frame. The resulting whole-cell catalyst achieved a recombinant protein yield of 46% of total intracellular protein in an optimal ScP:CbP:CdP activity ratio of 10:2.9:0.6, yielding an overall activity of 315 U/g dry cell mass. We demonstrated that bioconversion catalyzed by a semi-permeabilized whole-cell catalyst achieved an industrial relevant COS product titer of 125 g/L and a space-time yield of 20 g/L/h. With CbP as the cellobiose providing enzyme, flux into higher oligosaccharides (DP ≥ 6) was prevented and no insoluble products were formed after 6 h of conversion. CONCLUSIONS A whole-cell catalyst for COS biosynthesis was developed. The coordinated co-expression of the three biosynthesis enzymes balanced the activities of the individual enzymes such that COS production was maximized. With the flux control set to minimize the share of insolubles in the product, the whole-cell synthesis shows a performance with respect to yield, productivity, product concentration and quality that is promising for industrial production.
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Affiliation(s)
- Katharina N. Schwaiger
- grid.432147.70000 0004 0591 4434ACIB-Austrian Centre of Industrial Biotechnology, Krenngasse 37, 8010 Graz, Austria
| | - Alena Voit
- grid.432147.70000 0004 0591 4434ACIB-Austrian Centre of Industrial Biotechnology, Krenngasse 37, 8010 Graz, Austria
| | - Birgit Wiltschi
- grid.432147.70000 0004 0591 4434ACIB-Austrian Centre of Industrial Biotechnology, Krenngasse 37, 8010 Graz, Austria
| | - Bernd Nidetzky
- grid.432147.70000 0004 0591 4434ACIB-Austrian Centre of Industrial Biotechnology, Krenngasse 37, 8010 Graz, Austria ,grid.410413.30000 0001 2294 748XInstitute of Biotechnology and Biochemical Engineering, NAWI Graz, Graz University of Technology, Petersgasse 12, 8010 Graz, Austria
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41
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Abstract
In-cell structural biology aims at extracting structural information about proteins or nucleic acids in their native, cellular environment. This emerging field holds great promise and is already providing new facts and outlooks of interest at both fundamental and applied levels. NMR spectroscopy has important contributions on this stage: It brings information on a broad variety of nuclei at the atomic scale, which ensures its great versatility and uniqueness. Here, we detail the methods, the fundamental knowledge, and the applications in biomedical engineering related to in-cell structural biology by NMR. We finally propose a brief overview of the main other techniques in the field (EPR, smFRET, cryo-ET, etc.) to draw some advisable developments for in-cell NMR. In the era of large-scale screenings and deep learning, both accurate and qualitative experimental evidence are as essential as ever to understand the interior life of cells. In-cell structural biology by NMR spectroscopy can generate such a knowledge, and it does so at the atomic scale. This review is meant to deliver comprehensive but accessible information, with advanced technical details and reflections on the methods, the nature of the results, and the future of the field.
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Affiliation(s)
- Francois-Xavier Theillet
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
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42
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Casas A, Bultelle M, Motraghi C, Kitney R. PASIV: A Pooled Approach-Based Workflow to Overcome Toxicity-Induced Design of Experiments Failures and Inefficiencies. ACS Synth Biol 2022; 11:1272-1291. [PMID: 35261238 PMCID: PMC8938949 DOI: 10.1021/acssynbio.1c00562] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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We present here a
newly developed workflow—which we have
called PASIV—designed to provide a solution to a practical
problem with design of experiments (DoE) methodology: i.e., what can
be done if the scoping phase of the DoE cycle is severely hampered
by burden and toxicity issues (caused by either the metabolite or
an intermediary), making it unreliable or impossible to proceed to
the screening phase? PASIV—standing for pooled approach, screening,
identification, and visualization—was designed so the (viable)
region of interest can be made to appear through an interplay between
biology and software. This was achieved by combining multiplex construction
in a pooled approach (one-pot reaction) with a viability assay and
with a range of bioinformatics tools (including a novel construct
matching tool). PASIV was tested on the exemplar of the lycopene pathway—under
stressful constitutive expression—yielding a region of interest
with comparatively stronger producers.
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Affiliation(s)
- Alexis Casas
- Department of Bioengineering, Imperial College London, Exhibition Road, London SW7 2BX, United Kingdom
| | - Matthieu Bultelle
- Department of Bioengineering, Imperial College London, Exhibition Road, London SW7 2BX, United Kingdom
| | - Charles Motraghi
- Department of Bioengineering, Imperial College London, Exhibition Road, London SW7 2BX, United Kingdom
| | - Richard Kitney
- Department of Bioengineering, Imperial College London, Exhibition Road, London SW7 2BX, United Kingdom
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43
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Goetz H, Stone A, Zhang R, Lai Y, Tian X. Double-edged role of resource competition in gene expression noise and control. ADVANCED GENETICS (HOBOKEN, N.J.) 2022; 3:2100050. [PMID: 35989723 PMCID: PMC9390979 DOI: 10.1002/ggn2.202100050] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
Despite extensive investigation demonstrating that resource competition can significantly alter the deterministic behaviors of synthetic gene circuits, it remains unclear how resource competition contributes to the gene expression noise and how this noise can be controlled. Utilizing a two-gene circuit as a prototypical system, we uncover a surprising double-edged role of resource competition in gene expression noise: competition decreases noise through introducing a resource constraint but generates its own type of noise which we name as "resource competitive noise." Utilization of orthogonal resources enables retainment of the noise reduction conferred by resource constraint while removing the added resource competitive noise. The noise reduction effects are studied using three negative feedback types: negatively competitive regulation (NCR), local, and global controllers, each having four placement architectures in the protein biosynthesis pathway (mRNA or protein inhibition on transcription or translation). Our results show that both local and NCR controllers with mRNA-mediated inhibition are efficacious at reducing noise, with NCR controllers demonstrating a superior noise-reduction capability. We also find that combining feedback controllers with orthogonal resources can improve the local controllers. This work provides deep insights into the origin of stochasticity in gene circuits with resource competition and guidance for developing effective noise control strategies.
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Affiliation(s)
- Hanah Goetz
- School for Engineering of Matter, Transport and EnergyArizona State UniversityTempeAZ85287USA
| | - Austin Stone
- School of Biological and Health Systems EngineeringArizona State UniversityTempeAZ85287USA
| | - Rong Zhang
- School of Biological and Health Systems EngineeringArizona State UniversityTempeAZ85287USA
| | - Ying‐Cheng Lai
- School of Electrical, Computer and Energy EngineeringArizona State UniversityTempeAZ85287USA
- Department of PhysicsArizona State UniversityTempeAZ85287USA
| | - Xiao‐Jun Tian
- School of Biological and Health Systems EngineeringArizona State UniversityTempeAZ85287USA
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44
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Autotrophic lactate production from H2 + CO2 using recombinant and fluorescent FAST-tagged Acetobacterium woodii strains. Appl Microbiol Biotechnol 2022; 106:1447-1458. [PMID: 35092454 PMCID: PMC8882112 DOI: 10.1007/s00253-022-11770-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 12/23/2021] [Accepted: 01/07/2022] [Indexed: 12/12/2022]
Abstract
AbstractLactate has various uses as industrial platform chemical, poly-lactic acid precursor or feedstock for anaerobic co-cultivations. The aim of this study was to construct and characterise Acetobacterium woodii strains capable of autotrophic lactate production. Therefore, the lctBCD genes, encoding the native Lct dehydrogenase complex, responsible for lactate consumption, were knocked out. Subsequently, a gene encoding a d-lactate dehydrogenase (LDHD) originating from Leuconostoc mesenteroides was expressed in A. woodii, either under the control of the anhydrotetracycline-inducible promoter Ptet or under the lactose-inducible promoter PbgaL. Moreover, LDHD was N-terminally fused to the oxygen-independent fluorescence-activating and absorption-shifting tag (FAST) and expressed in respective A. woodii strains. Cells that produced the LDHD fusion protein were capable of lactate production of up to 18.8 mM in autotrophic batch experiments using H2 + CO2 as energy and carbon source. Furthermore, cells showed a clear and bright fluorescence during exponential growth, as well as in the stationary phase after induction, mediated by the N-terminal FAST. Flow cytometry at the single-cell level revealed phenotypic heterogeneities for cells expressing the FAST-tagged LDHD fusion protein. This study shows that FAST provides a new reporter tool to quickly analyze gene expression over the course of growth experiments of A. woodii. Consequently, fluorescence-based reporters allow for faster and more targeted optimization of production strains.Key points
•Autotrophic lactate production was achieved with A. woodii.
•FAST functions as fluorescent marker protein in A. woodii.
•Fluorescence measurements on single-cell level revealed population heterogeneity.
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45
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Verma BK, Mannan AA, Zhang F, Oyarzún DA. Trade-Offs in Biosensor Optimization for Dynamic Pathway Engineering. ACS Synth Biol 2022; 11:228-240. [PMID: 34968029 DOI: 10.1021/acssynbio.1c00391] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Recent progress in synthetic biology allows the construction of dynamic control circuits for metabolic engineering. This technology promises to overcome many challenges encountered in traditional pathway engineering, thanks to its ability to self-regulate gene expression in response to bioreactor perturbations. The central components in these control circuits are metabolite biosensors that read out pathway signals and actuate enzyme expression. However, the construction of metabolite biosensors is a major bottleneck for strain design, and a key challenge is to understand the relation between biosensor dose-response curves and pathway performance. Here we employ multiobjective optimization to quantify performance trade-offs that arise in the design of metabolite biosensors. Our approach reveals strategies for tuning dose-response curves along an optimal trade-off between production flux and the cost of an increased expression burden on the host. We explore properties of control architectures built in the literature and identify their advantages and caveats in terms of performance and robustness to growth conditions and leaky promoters. We demonstrate the optimality of a control circuit for glucaric acid production in Escherichia coli, which has been shown to increase the titer by 2.5-fold as compared to static designs. Our results lay the groundwork for the automated design of control circuits for pathway engineering, with applications in the food, energy, and pharmaceutical sectors.
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Affiliation(s)
- Babita K. Verma
- School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, U.K
| | - Ahmad A. Mannan
- Warwick Integrative Synthetic Biology Centre, School of Engineering, University of Warwick, Coventry CV4 7AL, U.K
| | - Fuzhong Zhang
- Department of Energy, Environmental & Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Diego A. Oyarzún
- School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, U.K
- School of Informatics, The University of Edinburgh, Edinburgh EH8 9AB, U.K
- The Alan Turing Institute, London, NW1 2DB, U.K
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46
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Shallom D, Naiger D, Weiss S, Tuller T. Accelerating Whole-Cell Simulations of mRNA Translation Using a Dedicated Hardware. ACS Synth Biol 2021; 10:3489-3506. [PMID: 34813269 PMCID: PMC8689694 DOI: 10.1021/acssynbio.1c00415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In recent years, intracellular biophysical simulations have been used with increasing frequency not only for answering basic scientific questions but also in the field of synthetic biology. However, since these models include networks of interaction between millions of components, they are extremely time-consuming and cannot run easily on parallel computers. In this study, we demonstrate for the first time a novel approach addressing this challenge by using a dedicated hardware designed specifically to simulate such processes. As a proof of concept, we specifically focus on mRNA translation, which is the process consuming most of the energy in the cell. We design a hardware that simulates translation in Escherichia coli and Saccharomyces cerevisiae for thousands of mRNAs and ribosomes, which is in orders of magnitude faster than a similar software solution. With the sharp increase in the amount of genomic data available today and the complexity of the corresponding models inferred from them, we believe that the strategy suggested here will become common and can be used among others for simulating entire cells with all gene expression steps.
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Affiliation(s)
- David Shallom
- School of Electrical Engineering, Tel Aviv University, Tel Aviv 69978, Israel
| | - Danny Naiger
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv 69978, Israel
| | - Shlomo Weiss
- School of Electrical Engineering, Tel Aviv University, Tel Aviv 69978, Israel
| | - Tamir Tuller
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv 69978, Israel
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47
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Chen T, Ali Al-Radhawi M, Voigt CA, Sontag ED. A synthetic distributed genetic multi-bit counter. iScience 2021; 24:103526. [PMID: 34917900 PMCID: PMC8666654 DOI: 10.1016/j.isci.2021.103526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 09/30/2021] [Accepted: 11/23/2021] [Indexed: 11/12/2022] Open
Abstract
A design for genetically encoded counters is proposed via repressor-based circuits. An N-bit counter reads sequences of input pulses and displays the total number of pulses, modulo 2N. The design is based on distributed computation with specialized cell types allocated to specific tasks. This allows scalability and bypasses constraints on the maximal number of circuit genes per cell due to toxicity or failures due to resource limitations. The design starts with a single-bit counter. The N-bit counter is then obtained by interconnecting (using diffusible chemicals) a set of N single-bit counters and connector modules. An optimization framework is used to determine appropriate gate parameters and to compute bounds on admissible pulse widths and relaxation (inter-pulse) times, as well as to guide the construction of novel gates. This work can be viewed as a step toward obtaining circuits that are capable of finite automaton computation in analogy to digital central processing units. A single-bit counter is designed for a repressor-based genetic circuit A scalable multi-bit counter is enabled by distributing the design across cells A computational optimization framework is proposed to guide the design
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Affiliation(s)
- Tianchi Chen
- Department of Bioengineering, Northeastern University, Boston, MA 02115, USA
| | - M Ali Al-Radhawi
- Department of Electrical and Computer Engineering, Northeastern University, Boston, MA 02115, USA
| | - Christopher A Voigt
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Eduardo D Sontag
- Department of Bioengineering, Northeastern University, Boston, MA 02115, USA.,Department of Electrical and Computer Engineering, Northeastern University, Boston, MA 02115, USA.,Laboratory of Systems Pharmacology, Program in Therapeutic Science, Harvard Medical School, Boston, MA 02115, USA
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48
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Goosens VJ, Walker KT, Aragon SM, Singh A, Senthivel VR, Dekker L, Caro-Astorga J, Buat MLA, Song W, Lee KY, Ellis T. Komagataeibacter Tool Kit (KTK): A Modular Cloning System for Multigene Constructs and Programmed Protein Secretion from Cellulose Producing Bacteria. ACS Synth Biol 2021; 10:3422-3434. [PMID: 34767345 DOI: 10.1021/acssynbio.1c00358] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Bacteria proficient at producing cellulose are an attractive synthetic biology host for the emerging field of Engineered Living Materials (ELMs). Species from the Komagataeibacter genus produce high yields of pure cellulose materials in a short time with minimal resources, and pioneering work has shown that genetic engineering in these strains is possible and can be used to modify the material and its production. To accelerate synthetic biology progress in these bacteria, we introduce here the Komagataeibacter tool kit (KTK), a standardized modular cloning system based on Golden Gate DNA assembly that allows DNA parts to be combined to build complex multigene constructs expressed in bacteria from plasmids. Working in Komagataeibacter rhaeticus, we describe basic parts for this system, including promoters, fusion tags, and reporter proteins, before showcasing how the assembly system enables more complex designs. Specifically, we use KTK cloning to reformat the Escherichia coli curli amyloid fiber system for functional expression in K. rhaeticus, and go on to modify it as a system for programming protein secretion from the cellulose producing bacteria. With this toolkit, we aim to accelerate modular synthetic biology in these bacteria, and enable more rapid progress in the emerging ELMs community.
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Affiliation(s)
- Vivianne J. Goosens
- Imperial College Centre for Synthetic Biology, Imperial College London, London SW7 2AZ, U.K
- Department of Bioengineering, Imperial College London, London SW7 2AZ, U.K
| | - Kenneth T. Walker
- Imperial College Centre for Synthetic Biology, Imperial College London, London SW7 2AZ, U.K
- Department of Bioengineering, Imperial College London, London SW7 2AZ, U.K
| | - Silvia M. Aragon
- Imperial College Centre for Synthetic Biology, Imperial College London, London SW7 2AZ, U.K
- Department of Life Sciences, Imperial College London, London SW7 2AZ, U.K
| | - Amritpal Singh
- Imperial College Centre for Synthetic Biology, Imperial College London, London SW7 2AZ, U.K
- Department of Bioengineering, Imperial College London, London SW7 2AZ, U.K
| | - Vivek R. Senthivel
- Imperial College Centre for Synthetic Biology, Imperial College London, London SW7 2AZ, U.K
- Department of Bioengineering, Imperial College London, London SW7 2AZ, U.K
| | - Linda Dekker
- Imperial College Centre for Synthetic Biology, Imperial College London, London SW7 2AZ, U.K
- Department of Life Sciences, Imperial College London, London SW7 2AZ, U.K
| | - Joaquin Caro-Astorga
- Imperial College Centre for Synthetic Biology, Imperial College London, London SW7 2AZ, U.K
- Department of Bioengineering, Imperial College London, London SW7 2AZ, U.K
| | | | - Wenzhe Song
- Department of Aeronautics, Imperial College London, London SW7 2AZ, U.K
| | - Koon-Yang Lee
- Department of Aeronautics, Imperial College London, London SW7 2AZ, U.K
| | - Tom Ellis
- Imperial College Centre for Synthetic Biology, Imperial College London, London SW7 2AZ, U.K
- Department of Bioengineering, Imperial College London, London SW7 2AZ, U.K
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49
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Principles of synthetic biology. Essays Biochem 2021; 65:791-811. [PMID: 34693448 PMCID: PMC8578974 DOI: 10.1042/ebc20200059] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 09/05/2021] [Accepted: 09/24/2021] [Indexed: 12/18/2022]
Abstract
In synthetic biology, biological cells and processes are dismantled and reassembled to make novel systems that do useful things. Designs are encoded by deoxyribonucleic acid (DNA); DNA makes biological (bio-)parts; bioparts are combined to make devices; devices are built into biological systems. Computers are used at all stages of the Design-Build-Test-Learn cycle, from mathematical modelling through to the use of robots for the automation of assembly and experimentation. Synthetic biology applies engineering principles of standardisation, modularity, and abstraction, enabling fast prototyping and the ready exchange of designs between synthetic biologists working around the world. Like toy building blocks, compatible modular designs enable bioparts to be combined and optimised easily; biopart specifications are shared in open registries. Synthetic biology is made possible due to major advances in DNA sequencing and synthesis technologies, and through knowledge gleaned in the field of systems biology. Systems biology aims to understand biology across scales, from the molecular and cellular, up to tissues and organisms, and describes cells as complex information-processing systems. By contrast, synthetic biology seeks to design and build its own systems. Applications of synthetic biology are wide-ranging but include impacting healthcare to improve diagnosis and make better treatments for disease; it seeks to improve the environment by finding novel ways to clean up pollution, make industrial processes for chemical synthesis sustainable, and remove the need for damaging farming practices by making better fertilisers. Synthetic biology has the potential to change the way we live and help us to protect the future of our planet.
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50
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Gyorgy A. Context-Dependent Stability and Robustness of Genetic Toggle Switches with Leaky Promoters. Life (Basel) 2021; 11:life11111150. [PMID: 34833026 PMCID: PMC8624834 DOI: 10.3390/life11111150] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 10/21/2021] [Accepted: 10/26/2021] [Indexed: 01/22/2023] Open
Abstract
Multistable switches are ubiquitous building blocks in both systems and synthetic biology. Given their central role, it is thus imperative to understand how their fundamental properties depend not only on the tunable biophysical properties of the switches themselves, but also on their genetic context. To this end, we reveal in this article how these factors shape the essential characteristics of toggle switches implemented using leaky promoters such as their stability and robustness to noise, both at single-cell and population levels. In particular, our results expose the roles that competition for scarce transcriptional and translational resources, promoter leakiness, and cell-to-cell heterogeneity collectively play. For instance, the interplay between protein expression from leaky promoters and the associated cost of relying on shared cellular resources can give rise to tristable dynamics even in the absence of positive feedback. Similarly, we demonstrate that while promoter leakiness always acts against multistability, resource competition can be leveraged to counteract this undesirable phenomenon. Underpinned by a mechanistic model, our results thus enable the context-aware rational design of multistable genetic switches that are directly translatable to experimental considerations, and can be further leveraged during the synthesis of large-scale genetic systems using computer-aided biodesign automation platforms.
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Affiliation(s)
- Andras Gyorgy
- Division of Engineering, New York University Abu Dhabi, Abu Dhabi P.O. Box 129188, United Arab Emirates
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