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Hartig AM, Dai W, Zhang K, Kapoor K, Rottinghaus AG, Moon TS, Parker KM. Influence of Environmental Conditions on the Escape Rates of Biocontained Genetically Engineered Microbes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:22657-22667. [PMID: 39668804 PMCID: PMC11750180 DOI: 10.1021/acs.est.4c10893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2024]
Abstract
The development of genetically engineered microbes (GEMs) has resulted in an urgent need to control their persistence in the environment. The use of biocontainment such as kill switches is a critical approach to prevent the unintended proliferation of GEMs; however, the effectiveness of kill switches─reported as escape rates, i.e., the ratio of the number of viable microbes when the kill switch is triggered relative to the number when it is not triggered─is typically assessed under laboratory conditions that do not resemble environmental conditions under which biocontainment must perform. In this study, we discovered that the escape rate of an Escherichia coli GEM biocontained with a CRISPR-based kill switch triggered by anhydrotetracycline (aTc) increased by 3-4 orders of magnitude when deployed in natural surface waters as compared to rich laboratory media. We identified that environmental conditions (e.g., pH, nutrient levels) may contribute to elevated escape rates in multiple ways, including by altering the chemical speciation of the kill switch trigger to reduce its uptake and providing limited nutrients required for the kill switch to function. Our study demonstrated that conditions in the intended environment must be considered in order to design effective GEM biocontainment strategies.
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Affiliation(s)
- Anna M. Hartig
- Department of Energy, Environmental, and Chemical Engineering, Washington University in St. Louis, St. Louis Missouri 63130, United States
| | - Wentao Dai
- Department of Energy, Environmental, and Chemical Engineering, Washington University in St. Louis, St. Louis Missouri 63130, United States
| | - Ke Zhang
- Department of Energy, Environmental, and Chemical Engineering, Washington University in St. Louis, St. Louis Missouri 63130, United States
| | - Krisha Kapoor
- Department of Energy, Environmental, and Chemical Engineering, Washington University in St. Louis, St. Louis Missouri 63130, United States
| | - Austin G. Rottinghaus
- Department of Energy, Environmental, and Chemical Engineering, Washington University in St. Louis, St. Louis Missouri 63130, United States
| | - Tae Seok Moon
- Department of Energy, Environmental, and Chemical Engineering, Washington University in St. Louis, St. Louis Missouri 63130, United States
- Division of Biology and Biomedical Sciences, Washington University in St. Louis, St. Louis Missouri 63130, United States
- Synthetic Biology Group, J. Craig Venter Institute, La Jolla, California 92037, United States
| | - Kimberly M. Parker
- Department of Energy, Environmental, and Chemical Engineering, Washington University in St. Louis, St. Louis Missouri 63130, United States
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Foo GW, Leichthammer CD, Saita IM, Lukas ND, Batko IZ, Heinrichs DE, Edgell DR. Intein-based thermoregulated meganucleases for containment of genetic material. Nucleic Acids Res 2024; 52:2066-2077. [PMID: 38180814 PMCID: PMC10899782 DOI: 10.1093/nar/gkad1247] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 12/13/2023] [Accepted: 12/18/2023] [Indexed: 01/07/2024] Open
Abstract
Limiting the spread of synthetic genetic information outside of the intended use is essential for applications where biocontainment is critical. In particular, biocontainment of engineered probiotics and plasmids that are excreted from the mammalian gastrointestinal tract is needed to prevent escape and acquisition of genetic material that could confer a selective advantage to microbial communities. Here, we built a simple and lightweight biocontainment system that post-translationally activates a site-specific DNA endonuclease to degrade DNA at 18°C and not at higher temperatures. We constructed an orthogonal set of temperature-sensitive meganucleases (TSMs) by inserting the yeast VMA1 L212P temperature-sensitive intein into the coding regions of LAGLIDADG homing endonucleases. We showed that the TSMs eliminated plasmids carrying the cognate TSM target site from laboratory strains of Escherichia coli at the permissive 18°C but not at higher restrictive temperatures. Plasmid elimination is dependent on both TSM endonuclease activity and intein splicing. TSMs eliminated plasmids from E. coli Nissle 1917 after passage through the mouse gut when fecal resuspensions were incubated at 18°C but not at 37°C. Collectively, our data demonstrates the potential of thermoregulated meganucleases as a means of restricting engineered plasmids and probiotics to the mammalian gut.
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Affiliation(s)
- Gary W Foo
- Department of Biochemistry, Schulich School of Medicine and Dentistry, London, Ontario N6A 5C1, Canada
| | | | - Ibrahim M Saita
- Department of Biochemistry, Schulich School of Medicine and Dentistry, London, Ontario N6A 5C1, Canada
| | - Nicholas D Lukas
- Department of Biochemistry, Schulich School of Medicine and Dentistry, London, Ontario N6A 5C1, Canada
| | - Izabela Z Batko
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, London, Ontario N6A 5C1, Canada
| | - David E Heinrichs
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, London, Ontario N6A 5C1, Canada
| | - David R Edgell
- Department of Biochemistry, Schulich School of Medicine and Dentistry, London, Ontario N6A 5C1, Canada
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Liu H, Zhang L, Wang W, Hu H, Ouyang X, Xu P, Tang H. An Intelligent Synthetic Bacterium for Chronological Toxicant Detection, Biodegradation, and Its Subsequent Suicide. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2304318. [PMID: 37705081 PMCID: PMC10625131 DOI: 10.1002/advs.202304318] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 08/24/2023] [Indexed: 09/15/2023]
Abstract
Modules, toolboxes, and synthetic biology systems may be designed to address environmental bioremediation. However, weak and decentralized functional modules require complex control. To address this issue, an integrated system for toxicant detection and biodegradation, and subsequent suicide in chronological order without exogenous inducers is constructed. Salicylic acid, a typical pollutant in industrial wastewater, is selected as an example to demonstrate this design. Biosensors are optimized by regulating the expression of receptors and reporters to get 2-fold sensitivity and 6-fold maximum output. Several stationary phase promoters are compared, and promoter Pfic is chosen to express the degradation enzyme. Two concepts for suicide circuits are developed, with the toxin/antitoxin circuit showing potent lethality. The three modules are coupled in a stepwise manner. Detection and biodegradation, and suicide are sequentially completed with partial attenuation compared to pre-integration, except for biodegradation, being improved by the replacements of ribosome binding site. Finally, a long-term stability test reveals that the engineered strain maintained its function for ten generations. The study provides a novel concept for integrating and controlling functional modules that can accelerate the transition of synthetic biology from conceptual to practical applications.
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Affiliation(s)
- Huan Liu
- State Key Laboratory of Microbial MetabolismJoint International Research Laboratory of Metabolic and Developmental Sciences, and School of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiP. R. China
| | - Lige Zhang
- State Key Laboratory of Microbial MetabolismJoint International Research Laboratory of Metabolic and Developmental Sciences, and School of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiP. R. China
| | - Weiwei Wang
- State Key Laboratory of Microbial MetabolismJoint International Research Laboratory of Metabolic and Developmental Sciences, and School of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiP. R. China
| | - Haiyang Hu
- State Key Laboratory of Microbial MetabolismJoint International Research Laboratory of Metabolic and Developmental Sciences, and School of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiP. R. China
| | - Xingyu Ouyang
- State Key Laboratory of Microbial MetabolismJoint International Research Laboratory of Metabolic and Developmental Sciences, and School of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiP. R. China
| | - Ping Xu
- State Key Laboratory of Microbial MetabolismJoint International Research Laboratory of Metabolic and Developmental Sciences, and School of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiP. R. China
| | - Hongzhi Tang
- State Key Laboratory of Microbial MetabolismJoint International Research Laboratory of Metabolic and Developmental Sciences, and School of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiP. R. China
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4
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McMullen JG, Lennon JT. Mark-recapture of microorganisms. Environ Microbiol 2023; 25:150-157. [PMID: 36310117 DOI: 10.1111/1462-2920.16267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 10/27/2022] [Indexed: 01/21/2023]
Affiliation(s)
| | - Jay T Lennon
- Department of Biology, Indiana University, Bloomington, Indiana, USA
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Zhu X, Zhaoyang Zhang, Bin Jia, Yuan Y. Current advances of biocontainment strategy in synthetic biology. Chin J Chem Eng 2022. [DOI: 10.1016/j.cjche.2022.07.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Abstract
The use of dyes dates to ancient times and has increased due to population and industrial growth, leading to the rise of synthetic dyes. These pollutants are of great environmental impact and azo dyes deserve special attention due their widespread use and challenging degradation. Among the biological solutions developed to mitigate this issue, bacteria are highlighted for being versatile organisms, which can be applied as single organism cultures, microbial consortia, in bioreactors, acting in the detoxification of azo dyes breakage by-products and have the potential to combine biodegradation with the production of products of economic interest. These characteristics go hand in hand with the ability of various strains to act under various chemical and physical parameters, such as a wide range of pH, salinity, and temperature, with good performance under industry, and environmental, relevant conditions. This review encompasses studies with promising results related to the use of bacteria in the bioremediation of environments contaminated with azo dyes in the most diverse techniques and parameters, both in environmental and laboratory samples, also addressing their mechanisms and the legislation involving these dyes around the world, showcasing the importance of bacterial bioremediation, specialty in a scenario in an ever-increasing pursuit for sustainable production.
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Kim K, Choe D, Song Y, Kang M, Lee SG, Lee DH, Cho BK. Engineering Bacteroides thetaiotaomicron to produce non-native butyrate based on a genome-scale metabolic model-guided design. Metab Eng 2021; 68:174-186. [PMID: 34655791 DOI: 10.1016/j.ymben.2021.10.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Revised: 10/04/2021] [Accepted: 10/09/2021] [Indexed: 12/29/2022]
Abstract
Bacteroides thetaiotaomicron represents a major symbiont of the human gut microbiome that is increasingly viewed as a promising candidate strain for microbial therapeutics. Here, we engineer B. thetaiotaomicron for heterologous production of non-native butyrate as a proof-of-concept biochemical at therapeutically relevant concentrations. Since B. thetaiotaomicron is not a natural producer of butyrate, we heterologously expressed a butyrate biosynthetic pathway in the strain, which led to the production of butyrate at the final concentration of 12 mg/L in a rich medium. Further optimization of butyrate production was achieved by a round of metabolic engineering guided by an expanded genome-scale metabolic model (GEM) of B. thetaiotaomicron. The in silico knock-out simulation of the expanded model showed that pta and ldhD were the potent knock-out targets to enhance butyrate production. The maximum titer and specific productivity of butyrate in the pta-ldhD double knockout mutant increased by nearly 3.4 and 4.8 folds, respectively. To our knowledge, this is the first engineering attempt that enabled butyrate production from a non-butyrate producing commensal B. thetaiotaomicron. The study also highlights that B. thetaiotaomicron can serve as an effective strain for live microbial therapeutics in human.
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Affiliation(s)
- Kangsan Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea
| | - Donghui Choe
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea
| | - Yoseb Song
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea
| | - Minjeong Kang
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea
| | - Seung-Goo Lee
- Synthetic Biology & Bioengineering Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, 34141, Republic of Korea
| | - Dae-Hee Lee
- Synthetic Biology & Bioengineering Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, 34141, Republic of Korea
| | - Byung-Kwan Cho
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea; KAIST Institute for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea.
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Stirling F, Silver PA. Controlling the Implementation of Transgenic Microbes: Are We Ready for What Synthetic Biology Has to Offer? Mol Cell 2020; 78:614-623. [PMID: 32442504 PMCID: PMC7307494 DOI: 10.1016/j.molcel.2020.03.034] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 03/24/2020] [Accepted: 03/26/2020] [Indexed: 12/13/2022]
Abstract
Synthetic biology has promised and delivered on an impressive array of applications based on genetically modified microorganisms. While novel biotechnology undoubtedly offers benefits, like all new technology, precautions should be considered during implementation to reduce the risk of both known and unknown adverse effects. To achieve containment of transgenic microorganisms, confidence to a near-scientific certainty that they cannot transfer their transgenic genes to other organisms, and that they cannot survive to propagate in unintended environments, is a priority. Here, we present an in-depth summary of biological containment systems for micro-organisms published to date, including the production of a genetic firewall through genome recoding and physical containment of microbes using auxotrophies, regulation of essential genes, and expression of toxic genes. The level of containment required to consider a transgenic organism suitable for deployment is discussed, as well as standards of practice for developing new containment systems.
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Affiliation(s)
- Finn Stirling
- Department of Systems Biology, Harvard Medical School, 200 Longwood Avenue, Warren Alpert 536, Boston, MA 02115, USA; Wyss Institute for Biologically Inspired Engineering, Harvard University, 3 Blackfan Circle, 5th Floor, Boston, MA 02115, USA
| | - Pamela A Silver
- Department of Systems Biology, Harvard Medical School, 200 Longwood Avenue, Warren Alpert 536, Boston, MA 02115, USA; Wyss Institute for Biologically Inspired Engineering, Harvard University, 3 Blackfan Circle, 5th Floor, Boston, MA 02115, USA.
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Li Q, Li J, Kang KL, Wu YJ. A safety type of genetically engineered bacterium that degrades chemical pesticides. AMB Express 2020; 10:33. [PMID: 32072335 PMCID: PMC7028883 DOI: 10.1186/s13568-020-00967-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 02/03/2020] [Indexed: 11/10/2022] Open
Abstract
Chemical pesticides are used widely and their residues are found in the environment. Pesticide pollution has become a global problem. To find an economical, effective and safety way to degrade residues of pesticides in environment, we constructed a genetically engineered bacterium (GEB) having the ability to degrade pesticides, emit green fluorescence and has a containment system by using a dual plasmid expression system. One plasmid contains the genes of enhanced green fluorescent protein (EGFP) and carboxylesterase B1 (CarE B1), which were cloned downstream of lambda PL promoter and expressed constitutively. The gene of CarE B1 encodes an insect-detoxifying enzyme possessing the degradability to organochloride pesticides, organophosphorus pesticides, carbamates, and pyrethoid insecticides. The other is the conditional suicide plasmid for containment system, in which the lethal gene used was the nuclease gene of Serratia marcescens without the leader-coding sequence and was placed downstream of T7 promoter. The GEB has wide prospects of application on cleanup of pesticide residues with its degradability to several pesticides and containment system.
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Song T, Wang F, Xiong S, Jiang H. Surface display of organophosphorus-degrading enzymes on the recombinant spore of Bacillus subtilis. Biochem Biophys Res Commun 2019; 510:13-19. [PMID: 30660365 DOI: 10.1016/j.bbrc.2018.12.077] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 12/11/2018] [Indexed: 12/17/2022]
Abstract
Organophosphorus-degrading enzymes show high hydrolysis efficiency and provide an environmentally friendly solution to the pollution of organophosphorus compound. However, poor enzyme stability and tedious purification process have limited practical applications. Spore-based display system can provide many advantages, such as safety, low cost, easy preparation and high resistance to harsh conditions. Recently, we have constituted the recombinant spore displaying organophosphorus hydrolase and organophosphorus acid anhydrolase. In the spore display systems, recombinant spores could be reliably produced and normal sporulation was not affected; the activities of recombinant spores were 15.81 and 10.67 U/mg spores (dry weight) respectively; furthermore, the recombinant spores exhibited significantly enhanced resistance to various harsh conditions compared to free-form enzymes. These results indicated that the spore display could contribute to the practical application of organophosphorus-degrading enzymes and provide a promising solution to bioremediation of organophosphorus compounds.
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Affiliation(s)
- Tianyu Song
- Research Institute of Chemical Defense, Academy of Military Sciences, Beijing, 102205, PR China; State Key Laboratory of NBC Protection for Civilian, Academy of Military Sciences, Beijing, 102205, PR China
| | - Fuli Wang
- State Key Laboratory of NBC Protection for Civilian, Academy of Military Sciences, Beijing, 102205, PR China
| | - Shanshan Xiong
- Research Institute of Chemical Defense, Academy of Military Sciences, Beijing, 102205, PR China; State Key Laboratory of NBC Protection for Civilian, Academy of Military Sciences, Beijing, 102205, PR China
| | - Hui Jiang
- Research Institute of Chemical Defense, Academy of Military Sciences, Beijing, 102205, PR China; State Key Laboratory of NBC Protection for Civilian, Academy of Military Sciences, Beijing, 102205, PR China.
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Clark RL, Gordon GC, Bennett NR, Lyu H, Root TW, Pfleger BF. High-CO 2 Requirement as a Mechanism for the Containment of Genetically Modified Cyanobacteria. ACS Synth Biol 2018; 7:384-391. [PMID: 29320853 DOI: 10.1021/acssynbio.7b00377] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
As researchers engineer cyanobacteria for biotechnological applications, we must consider potential environmental release of these organisms. Previous theoretical work has considered cyanobacterial containment through elimination of the CO2-concentrating mechanism (CCM) to impose a high-CO2 requirement (HCR), which could be provided in the cultivation environment but not in the surroundings. In this work, we experimentally implemented an HCR containment mechanism in Synechococcus sp. strain PCC7002 (PCC7002) through deletion of carboxysome shell proteins and showed that this mechanism contained cyanobacteria in a 5% CO2 environment. We considered escape through horizontal gene transfer (HGT) and reduced the risk of HGT escape by deleting competence genes. We showed that the HCR containment mechanism did not negatively impact the performance of a strain of PCC7002 engineered for L-lactate production. We showed through coculture experiments of HCR strains with ccm-containing strains that this HCR mechanism reduced the frequency of escape below the NIH recommended limit for recombinant organisms of one escape event in 108 CFU.
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Affiliation(s)
- Ryan L. Clark
- Department
of Chemical and Biological Engineering, University of Wisconsin − Madison, 1415 Engineering Drive, Madison, Wisconsin 53706, United States
| | - Gina C. Gordon
- Department
of Chemical and Biological Engineering, University of Wisconsin − Madison, 1415 Engineering Drive, Madison, Wisconsin 53706, United States
- Microbiology
Doctoral Training Program, University of Wisconsin − Madison, 1550 Linden Drive, Madison, Wisconsin 53706, United States
| | - Nathaniel R. Bennett
- Department
of Chemical and Biological Engineering, University of Wisconsin − Madison, 1415 Engineering Drive, Madison, Wisconsin 53706, United States
| | - Haoxiang Lyu
- Department
of Chemical and Biological Engineering, University of Wisconsin − Madison, 1415 Engineering Drive, Madison, Wisconsin 53706, United States
| | - Thatcher W. Root
- Department
of Chemical and Biological Engineering, University of Wisconsin − Madison, 1415 Engineering Drive, Madison, Wisconsin 53706, United States
| | - Brian F. Pfleger
- Department
of Chemical and Biological Engineering, University of Wisconsin − Madison, 1415 Engineering Drive, Madison, Wisconsin 53706, United States
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12
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Abstract
Accurate incorporation of nonstandard amino acids (nsAAs) is central for genetic code expansion to increase the chemical diversity of proteins. However, aminoacyl-tRNA synthetases are polyspecific and facilitate incorporation of multiple nsAAs. We investigated and repurposed a natural protein degradation pathway, the N-end rule pathway, to devise an innovative system for rapid assessment of the accuracy of nsAA incorporation. Using this tool to monitor incorporation of the nsAA biphenylalanine allowed the identification of tyrosyl-tRNA synthetase (TyrRS) variants with improved amino acid specificity. The evolved TyrRS variants enhanced our ability to contain unwanted proliferation of genetically modified organisms. This posttranslational proofreading system will aid the evolution of orthogonal translation systems for specific incorporation of diverse nsAAs. Incorporation of nonstandard amino acids (nsAAs) leads to chemical diversification of proteins, which is an important tool for the investigation and engineering of biological processes. However, the aminoacyl-tRNA synthetases crucial for this process are polyspecific in regard to nsAAs and standard amino acids. Here, we develop a quality control system called “posttranslational proofreading” to more accurately and rapidly evaluate nsAA incorporation. We achieve this proofreading by hijacking a natural pathway of protein degradation known as the N-end rule, which regulates the lifespan of a protein based on its amino-terminal residue. We find that proteins containing certain desired N-terminal nsAAs have much longer half-lives compared with those proteins containing undesired amino acids. We use the posttranslational proofreading system to further evolve a Methanocaldococcus jannaschii tyrosyl-tRNA synthetase (TyrRS) variant and a tRNATyr species for improved specificity of the nsAA biphenylalanine in vitro and in vivo. Our newly evolved biphenylalanine incorporation machinery enhances the biocontainment and growth of genetically engineered Escherichia coli strains that depend on biphenylalanine incorporation. Finally, we show that our posttranslational proofreading system can be designed for incorporation of other nsAAs by rational engineering of the ClpS protein, which mediates the N-end rule. Taken together, our posttranslational proofreading system for in vivo protein sequence verification presents an alternative paradigm for molecular recognition of amino acids and is a major advance in our ability to accurately expand the genetic code.
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Arora AK, Douglas AE. Hype or opportunity? Using microbial symbionts in novel strategies for insect pest control. JOURNAL OF INSECT PHYSIOLOGY 2017; 103:10-17. [PMID: 28974456 DOI: 10.1016/j.jinsphys.2017.09.011] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 09/28/2017] [Accepted: 09/29/2017] [Indexed: 06/07/2023]
Abstract
All insects, including pest species, are colonized by microorganisms, variously located in the gut and within insect tissues. Manipulation of these microbial partners can reduce the pest status of insects, either by modifying insect traits (e.g. altering the host range or tolerance of abiotic conditions, reducing insect competence to vector disease agents) or by reducing fitness. Strategies utilizing heterologous microorganisms (i.e. derived from different insect species) and genetically-modified microbial symbionts are under development, particularly in relation to insect vectors of human disease agents. There is also the potential to target microorganisms absolutely required by the insect, resulting in insect mortality or suppression of insect growth or fecundity. This latter approach is particularly valuable for insect pests that depend on nutrients from symbiotic microorganisms to supplement their nutritionally-inadequate diet, e.g. insects feeding through the life cycle on vertebrate blood (cimicid bugs, anopluran lice, tsetse flies), plant sap (whiteflies, aphids, psyllids, planthoppers, leafhoppers/sharpshooters) and sound wood (various xylophagous beetles and some termites). Further research will facilitate implementation of these novel insect pest control strategies, particularly to ensure specificity of control agents to the pest insect without dissemination of bio-active compounds, novel microorganisms or their genes into the wider environment.
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Affiliation(s)
- Arinder K Arora
- Department of Entomology, Cornell University, Ithaca, NY 14853, USA
| | - Angela E Douglas
- Department of Entomology, Cornell University, Ithaca, NY 14853, USA; Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA.
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14
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Improving Fab' fragment retention in an autonucleolytic Escherichia coli strain by swapping periplasmic nuclease translocation signal from OmpA to DsbA. Biotechnol Lett 2017; 39:1865-1873. [PMID: 28875244 PMCID: PMC5674116 DOI: 10.1007/s10529-017-2425-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 08/22/2017] [Indexed: 12/27/2022]
Abstract
Objectives To reduce unwanted Fab’ leakage from an autonucleolytic Escherichia coli strain, which co-expresses OmpA-signalled Staphylococcal nuclease and Fab’ fragment in the periplasm, by substituting in Serratial nuclease and the DsbA periplasm translocation signal as alternatives. Results We attempted to genetically fuse a nuclease from Serratia marcescens to the OmpA signal peptide but plasmid construction failed, possibly due to toxicity of the resultant nuclease. Combining Serratial nuclease to the DsbA signal peptide was successful. The strain co-expressing this nuclease and periplasmic Fab’ grew in complex media and exhibited nuclease activity detectable by DNAse agar plate but its growth in defined medium was retarded. Fab’ coexpression with Staphylococcal nuclease fused to the DsbA signal peptide resulted in cells exhibiting nuclease activity and growth in defined medium. In cultivation to high cell density in a 5 l bioreactor, DsbA-fused Staphylococcal nuclease co-expression coincided with reduced Fab’ leakage relative to the original autonucleolytic Fab’ strain with OmpA-fused staphylococcal nuclease. Conclusions We successfully rescued Fab’ leakage back to acceptable levels and established a basis for future investigation of the linkage between periplasmic nuclease expression and leakage of co-expressed periplasmic Fab’ fragment to the surrounding growth media.
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15
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Sola-Oladokun B, Culligan EP, Sleator RD. Engineered Probiotics: Applications and Biological Containment. Annu Rev Food Sci Technol 2017; 8:353-370. [PMID: 28125354 DOI: 10.1146/annurev-food-030216-030256] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Bioengineered probiotics represent the next generation of whole cell-mediated biotherapeutics. Advances in synthetic biology, genome engineering, and DNA sequencing and synthesis have enabled scientists to design and develop probiotics with increased stress tolerance and the ability to target specific pathogens and their associated toxins, as well as to mediate targeted delivery of vaccines, drugs, and immunomodulators directly to host cells. Herein, we review the most significant advances in the development of this field. We discuss the critical issue of biological containment and consider the role of synthetic biology in the design and construction of the probiotics of the future.
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Affiliation(s)
- Babasola Sola-Oladokun
- Department of Biological Sciences, Cork Institute of Technology, Bishopstown, Cork, Ireland; , ,
| | - Eamonn P Culligan
- Department of Biological Sciences, Cork Institute of Technology, Bishopstown, Cork, Ireland; , ,
| | - Roy D Sleator
- Department of Biological Sciences, Cork Institute of Technology, Bishopstown, Cork, Ireland; , , .,APC Microbiome Institute, University College Cork, Cork, Ireland
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Abstract
Active containment systems are a major tool for reducing the uncertainty associated with the introduction of monocultures, genetically engineered or not, into target habitats for a large number of biotechnological applications (e.g., bioremediation, bioleaching, biopesticides, biofuels, biotransformations, live vaccines, etc.). While biological containment reduces the survival of the introduced organism outside the target habitat and/or upon completion of the projected task, gene containment strategies reduce the lateral spread of the key genetic determinants to indigenous microorganisms. In fundamental research, suicide circuits become relevant tools to address the role of gene transfer, mainly plasmid transfer, in evolution and how this transfer contributes to genome plasticity and to the rapid adaptation of microbial communities to environmental changes. Many lethal functions and regulatory circuits have been used and combined to design efficient containment systems. As many new genomes are being sequenced, novel lethal genes and regulatory elements are available, e.g., new toxin-antitoxin modules, and they could be used to increase further the current containment efficiencies and to expand containment to other organisms. Although the current containment systems can increase the predictability of genetically modified organisms in the environment, containment will never be absolute, due to the existence of mutations that lead to the appearance of surviving subpopulations. In this sense, orthogonal systems (xenobiology) appear to be the solution for setting a functional genetic firewall that will allow absolute containment of recombinant organisms.
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Alizadeh AA, Hamzeh-Mivehroud M, Dastmalchi S. Production and Purification of a Novel Anti-TNF-α Single Chain Fragment Variable Antibody. Adv Pharm Bull 2015; 5:667-72. [PMID: 26793614 DOI: 10.15171/apb.2015.091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 10/31/2015] [Accepted: 11/01/2015] [Indexed: 01/05/2023] Open
Abstract
PURPOSE TNF-α is an inflammatory cytokine with a key role in initiation of inflammatory responses. Anti-TNF-α antibodies are being used in clinic for the purpose of diagnosis and treatment due to their high specificity. The objective of the current study was to express and purify an anti-TNF-α scFv antibody identified by phage display technology. METHODS The DNA coding sequence of the identified scFv was cloned into pET28a vector and the corresponding protein was expressed as 6×His tagged using E.coli BL21 (DE3) pLysS expression system followed by affinity purification on Ni-Sepharose affinity column. RESULTS The J44 scFv antibody was cloned into the expression vector and successfully expressed and purified. The purity of the scFv fraction was confirmed using SDS-PAGE analysis. Western blotting technique was used to detect expression of 6×His tagged protein. CONCLUSION In the current study an anti-TNF-α scFv antibody was successfully expressed in bacterial expression system and purified on affinity column. The purified protein can be used in different in vitro and in vivo experiments in order to elucidate its functionality.
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Affiliation(s)
- Ali Akbar Alizadeh
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran. ; Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran. ; Students Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran. ; School of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Maryam Hamzeh-Mivehroud
- Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran. ; Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran. ; School of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Siavoush Dastmalchi
- Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran. ; School of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
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Caliando BJ, Voigt CA. Targeted DNA degradation using a CRISPR device stably carried in the host genome. Nat Commun 2015; 6:6989. [PMID: 25988366 PMCID: PMC4479009 DOI: 10.1038/ncomms7989] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 03/20/2015] [Indexed: 12/13/2022] Open
Abstract
Once an engineered organism completes its task, it is useful to degrade the associated DNA to reduce environmental release and protect intellectual property. Here we present a genetically encoded device (DNAi) that responds to a transcriptional input and degrades user-defined DNA. This enables engineered regions to be obscured when the cell enters a new environment. DNAi is based on type-IE CRISPR biochemistry and a synthetic CRISPR array defines the DNA target(s). When the input is on, plasmid DNA is degraded 10(8)-fold. When the genome is targeted, this causes cell death, reducing viable cells by a factor of 10(8). Further, the CRISPR nuclease can direct degradation to specific genomic regions (for example, engineered or inserted DNA), which could be used to complicate recovery and sequencing efforts. DNAi can be stably carried in an engineered organism, with no impact on cell growth, plasmid stability or DNAi inducibility even after passaging for >2 months.
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Affiliation(s)
- Brian J. Caliando
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
| | - Christopher A. Voigt
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
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Mandell DJ, Lajoie MJ, Mee MT, Takeuchi R, Kuznetsov G, Norville JE, Gregg CJ, Stoddard BL, Church GM. Biocontainment of genetically modified organisms by synthetic protein design. Nature 2015; 518:55-60. [PMID: 25607366 DOI: 10.1038/nature14121] [Citation(s) in RCA: 289] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 11/26/2014] [Indexed: 12/22/2022]
Abstract
Genetically modified organisms (GMOs) are increasingly deployed at large scales and in open environments. Genetic biocontainment strategies are needed to prevent unintended proliferation of GMOs in natural ecosystems. Existing biocontainment methods are insufficient because they impose evolutionary pressure on the organism to eject the safeguard by spontaneous mutagenesis or horizontal gene transfer, or because they can be circumvented by environmentally available compounds. Here we computationally redesign essential enzymes in the first organism possessing an altered genetic code (Escherichia coli strain C321.ΔA) to confer metabolic dependence on non-standard amino acids for survival. The resulting GMOs cannot metabolically bypass their biocontainment mechanisms using known environmental compounds, and they exhibit unprecedented resistance to evolutionary escape through mutagenesis and horizontal gene transfer. This work provides a foundation for safer GMOs that are isolated from natural ecosystems by a reliance on synthetic metabolites.
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Affiliation(s)
- Daniel J Mandell
- Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Marc J Lajoie
- 1] Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA [2] Program in Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Michael T Mee
- 1] Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA [2] Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215, USA
| | - Ryo Takeuchi
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| | - Gleb Kuznetsov
- Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Julie E Norville
- Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Christopher J Gregg
- Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Barry L Stoddard
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| | - George M Church
- 1] Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA [2] Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts 02115, USA
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Moe-Behrens GHG, Davis R, Haynes KA. Preparing synthetic biology for the world. Front Microbiol 2013; 4:5. [PMID: 23355834 PMCID: PMC3554958 DOI: 10.3389/fmicb.2013.00005] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 01/04/2013] [Indexed: 11/21/2022] Open
Abstract
Synthetic Biology promises low-cost, exponentially scalable products and global health solutions in the form of self-replicating organisms, or “living devices.” As these promises are realized, proof-of-concept systems will gradually migrate from tightly regulated laboratory or industrial environments into private spaces as, for instance, probiotic health products, food, and even do-it-yourself bioengineered systems. What additional steps, if any, should be taken before releasing engineered self-replicating organisms into a broader user space? In this review, we explain how studies of genetically modified organisms lay groundwork for the future landscape of biosafety. Early in the design process, biological engineers are anticipating potential hazards and developing innovative tools to mitigate risk. Here, we survey lessons learned, ongoing efforts to engineer intrinsic biocontainment, and how different stakeholders in synthetic biology can act to accomplish best practices for biosafety.
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Yang T, Yang L, Chai W, Li R, Xie J, Niu B. A strategy for high-level expression of a single-chain variable fragment against TNFα by subcloning antibody variable regions from the phage display vector pCANTAB 5E into pBV220. Protein Expr Purif 2011; 76:109-14. [DOI: 10.1016/j.pep.2010.10.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Revised: 10/08/2010] [Accepted: 10/08/2010] [Indexed: 10/18/2022]
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