1
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Chung KP, Loiacono FV, Neupert J, Wu M, Bock R. An RNA thermometer in the chloroplast genome of Chlamydomonas facilitates temperature-controlled gene expression. Nucleic Acids Res 2023; 51:11386-11400. [PMID: 37855670 PMCID: PMC10639063 DOI: 10.1093/nar/gkad816] [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: 07/31/2023] [Revised: 09/01/2023] [Accepted: 09/20/2023] [Indexed: 10/20/2023] Open
Abstract
Riboregulators such as riboswitches and RNA thermometers provide simple, protein-independent tools to control gene expression at the post-transcriptional level. In bacteria, RNA thermometers regulate protein synthesis in response to temperature shifts. Thermometers outside of the bacterial world are rare, and in organellar genomes, no RNA thermometers have been identified to date. Here we report the discovery of an RNA thermometer in a chloroplast gene of the unicellular green alga Chlamydomonas reinhardtii. The thermometer, residing in the 5' untranslated region of the psaA messenger RNA forms a hairpin-type secondary structure that masks the Shine-Dalgarno sequence at 25°C. At 40°C, melting of the secondary structure increases accessibility of the Shine-Dalgarno sequence to initiating ribosomes, thus enhancing protein synthesis. By targeted nucleotide substitutions and transfer of the thermometer into Escherichia coli, we show that the secondary structure is necessary and sufficient to confer the thermometer properties. We also demonstrate that the thermometer provides a valuable tool for inducible transgene expression from the Chlamydomonas plastid genome, in that a simple temperature shift of the algal culture can greatly increase recombinant protein yields.
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Affiliation(s)
- Kin Pan Chung
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Department Organelle Biology, Biotechnology and Molecular Ecophysiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - F Vanessa Loiacono
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Department Organelle Biology, Biotechnology and Molecular Ecophysiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Juliane Neupert
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Department Organelle Biology, Biotechnology and Molecular Ecophysiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Mengting Wu
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Department Organelle Biology, Biotechnology and Molecular Ecophysiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Ralph Bock
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Department Organelle Biology, Biotechnology and Molecular Ecophysiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
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2
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Ashraf F, Khan MA, Ahmed N, Umar M, Khan MI, Akram M, Bhatti R, Malik K. Development of transgenic algae strain expressing CTB-M2e fusion gene an approach towards the development of a universal edible vaccine in algae. J Biotechnol 2023; 374:31-37. [PMID: 37481211 DOI: 10.1016/j.jbiotec.2023.07.004] [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: 12/27/2022] [Revised: 07/14/2023] [Accepted: 07/17/2023] [Indexed: 07/24/2023]
Abstract
Avian Influenza, the most studied virus, is of high concern due to its zoonotic pandemic potential. In recent years, several influenza vaccines have been used with the broad goal of managing and in certain cases, eliminating the disease. The matrix 2 extracellular domain (M2e), is one of the key targets of the universal influenza vaccine, a liner peptide that is conserved throughout all influenza A subtypes virus. Many recombinant influenza proteins have been expressed in yeast and plants for vaccine development. A remarkable development has been made in the field of biotechnology to explore the potential of microalga as an expression host. In this study, we designed a fusion gene code for M2e peptide and CTB protein as M2e's natural form has a low level of immunogenicity. The fusion gene was cloned in the Chloroplast transformation vector pSRSapI and expressed in the TN72 mutant strain of Chlamydomonas reinhardii. The expression of the targeted protein was confirmed by ECL western blot analysis. A GM1-ELISA was carried out to detect the affinity of fusion protein for GM1 monosialoganglioside and the significant P-value is lower than 0.05. Immunogenicity assay on chicken detected the anti-M2e bodies in chicken serum. This study gives evidence of therapeutic protein production through algae chloroplast and a stable, selection free and low cost oral delivery for universal vaccine against influenza A virus.
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Affiliation(s)
- Fareeha Ashraf
- Center of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan.
| | - Mohsin Ahmad Khan
- Center of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Nadeem Ahmed
- Center of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Muhammad Umar
- Center of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Muhammad Islam Khan
- Center of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Maham Akram
- Center of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Rashid Bhatti
- Center of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Kausar Malik
- Center of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
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3
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Jackson HO, Taunt HN, Mordaka PM, Kumari S, Smith AG, Purton S. CpPosNeg: A positive-negative selection strategy allowing multiple cycles of marker-free engineering of the Chlamydomonas plastome. Biotechnol J 2022; 17:e2200088. [PMID: 35509114 DOI: 10.1002/biot.202200088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 04/19/2022] [Accepted: 04/23/2022] [Indexed: 02/02/2023]
Abstract
The chloroplast represents an attractive compartment for light-driven biosynthesis of recombinant products, and advanced synthetic biology tools are available for engineering the chloroplast genome ( = plastome) of several algal and plant species. However, producing commercial lines will likely require several plastome manipulations. This presents issues with respect to selectable markers, since there are a limited number available, they can be used only once in a serial engineering strategy, and it is undesirable to retain marker genes for antibiotic resistance in the final transplastome. To address these problems, we have designed a rapid iterative selection system, known as CpPosNeg, for the green microalga Chlamydomonas reinhardtii that allows creation of marker-free transformants starting from wild-type strains. The system employs a dual marker encoding a fusion protein of E. coli aminoglycoside adenyltransferase (AadA: conferring spectinomycin resistance) and a variant of E. coli cytosine deaminase (CodA: conferring sensitivity to 5-fluorocytosine). Initial selection on spectinomycin allows stable transformants to be established and driven to homoplasmy. Subsequent selection on 5-fluorocytosine results in rapid loss of the dual marker through intramolecular recombination between the 3'UTR of the marker and the 3'UTR of the introduced transgene. We demonstrate the versatility of the CpPosNeg system by serial introduction of reporter genes into the plastome.
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Affiliation(s)
- Harry O Jackson
- Department of Structural and Molecular Biology, University College London, London, UK
| | - Henry N Taunt
- Department of Structural and Molecular Biology, University College London, London, UK
| | - Paweł M Mordaka
- Department of Plant Sciences, University of Cambridge, Cambridge, UK
| | - Sujata Kumari
- DBT-ICT Centre for Energy Biosciences, Institute of Chemical Technology, Mumbai, India
| | - Alison G Smith
- Department of Plant Sciences, University of Cambridge, Cambridge, UK
| | - Saul Purton
- Department of Structural and Molecular Biology, University College London, London, UK
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4
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Harnessing the Algal Chloroplast for Heterologous Protein Production. Microorganisms 2022; 10:microorganisms10040743. [PMID: 35456794 PMCID: PMC9025058 DOI: 10.3390/microorganisms10040743] [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: 03/04/2022] [Revised: 03/24/2022] [Accepted: 03/28/2022] [Indexed: 02/04/2023] Open
Abstract
Photosynthetic microbes are gaining increasing attention as heterologous hosts for the light-driven, low-cost production of high-value recombinant proteins. Recent advances in the manipulation of unicellular algal genomes offer the opportunity to establish engineered strains as safe and viable alternatives to conventional heterotrophic expression systems, including for their use in the feed, food, and biopharmaceutical industries. Due to the relatively small size of their genomes, algal chloroplasts are excellent targets for synthetic biology approaches, and are convenient subcellular sites for the compartmentalized accumulation and storage of products. Different classes of recombinant proteins, including enzymes and peptides with therapeutical applications, have been successfully expressed in the plastid of the model organism Chlamydomonas reinhardtii, and of a few other species, highlighting the emerging potential of transplastomic algal biotechnology. In this review, we provide a unified view on the state-of-the-art tools that are available to introduce protein-encoding transgenes in microalgal plastids, and discuss the main (bio)technological bottlenecks that still need to be addressed to develop robust and sustainable green cell biofactories.
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5
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Lu Y, Gu X, Lin H, Melis A. Engineering microalgae: transition from empirical design to programmable cells. Crit Rev Biotechnol 2021; 41:1233-1256. [PMID: 34130561 DOI: 10.1080/07388551.2021.1917507] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Domesticated microalgae hold great promise for the sustainable provision of various bioresources for human domestic and industrial consumption. Efforts to exploit their potential are far from being fully realized due to limitations in the know-how of microalgal engineering. The associated technologies are not as well developed as those for heterotrophic microbes, cyanobacteria, and plants. However, recent studies on microalgal metabolic engineering, genome editing, and synthetic biology have immensely helped to enhance transformation efficiencies and are bringing new insights into this field. Therefore, this article, summarizes recent developments in microalgal biotechnology and examines the prospects for generating specialty and commodity products through the processes of metabolic engineering and synthetic biology. After a brief examination of empirical engineering methods and vector design, this article focuses on quantitative transformation cassette design, elaborates on target editing methods and emerging digital design of algal cellular metabolism to arrive at high yields of valuable products. These advances have enabled a transition of manners in microalgal engineering from single-gene and enzyme-based metabolic engineering to systems-level precision engineering, from cells created with genetically modified (GM) tags to that without GM tags, and ultimately from proof of concept to tangible industrial applications. Finally, future trends are proposed in microalgal engineering, aiming to establish individualized transformation systems in newly identified species for strain-specific specialty and commodity products, while developing sophisticated universal toolkits in model algal species.
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Affiliation(s)
- Yandu Lu
- State Key Laboratory of Marine Resource Utilization in the South China Sea, College of Oceanology, Hainan University, Haikou, China.,Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA
| | - Xinping Gu
- State Key Laboratory of Marine Resource Utilization in the South China Sea, College of Oceanology, Hainan University, Haikou, China
| | - Hanzhi Lin
- Institute of Marine & Environmental Technology, Center for Environmental Science, University of Maryland, College Park, MD, USA
| | - Anastasios Melis
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA
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6
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Jackson HO, Taunt HN, Mordaka PM, Smith AG, Purton S. The Algal Chloroplast as a Testbed for Synthetic Biology Designs Aimed at Radically Rewiring Plant Metabolism. FRONTIERS IN PLANT SCIENCE 2021; 12:708370. [PMID: 34630459 PMCID: PMC8497815 DOI: 10.3389/fpls.2021.708370] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 08/10/2021] [Indexed: 05/04/2023]
Abstract
Sustainable and economically viable support for an ever-increasing global population requires a paradigm shift in agricultural productivity, including the application of biotechnology to generate future crop plants. Current genetic engineering approaches aimed at enhancing the photosynthetic efficiency or composition of the harvested tissues involve relatively simple manipulations of endogenous metabolism. However, radical rewiring of central metabolism using new-to-nature pathways, so-called "synthetic metabolism", may be needed to really bring about significant step changes. In many cases, this will require re-programming the metabolism of the chloroplast, or other plastids in non-green tissues, through a combination of chloroplast and nuclear engineering. However, current technologies for sophisticated chloroplast engineering ("transplastomics") of plants are limited to just a handful of species. Moreover, the testing of metabolic rewiring in the chloroplast of plant models is often impractical given their obligate phototrophy, the extended time needed to create stable non-chimeric transplastomic lines, and the technical challenges associated with regeneration of whole plants. In contrast, the unicellular green alga, Chlamydomonas reinhardtii is a facultative heterotroph that allows for extensive modification of chloroplast function, including non-photosynthetic designs. Moreover, chloroplast engineering in C. reinhardtii is facile, with the ability to generate novel lines in a matter of weeks, and a well-defined molecular toolbox allows for rapid iterations of the "Design-Build-Test-Learn" (DBTL) cycle of modern synthetic biology approaches. The recent development of combinatorial DNA assembly pipelines for designing and building transgene clusters, simple methods for marker-free delivery of these clusters into the chloroplast genome, and the pre-existing wealth of knowledge regarding chloroplast gene expression and regulation in C. reinhardtii further adds to the versatility of transplastomics using this organism. Herein, we review the inherent advantages of the algal chloroplast as a simple and tractable testbed for metabolic engineering designs, which could then be implemented in higher plants.
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Affiliation(s)
- Harry O. Jackson
- Department of Structural and Molecular Biology, University College London, London, United Kingdom
| | - Henry N. Taunt
- Department of Structural and Molecular Biology, University College London, London, United Kingdom
| | - Pawel M. Mordaka
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Alison G. Smith
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Saul Purton
- Department of Structural and Molecular Biology, University College London, London, United Kingdom
- *Correspondence: Saul Purton
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7
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Kumar G, Shekh A, Jakhu S, Sharma Y, Kapoor R, Sharma TR. Bioengineering of Microalgae: Recent Advances, Perspectives, and Regulatory Challenges for Industrial Application. Front Bioeng Biotechnol 2020; 8:914. [PMID: 33014997 PMCID: PMC7494788 DOI: 10.3389/fbioe.2020.00914] [Citation(s) in RCA: 84] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 07/15/2020] [Indexed: 01/14/2023] Open
Abstract
Microalgae, due to their complex metabolic capacity, are being continuously explored for nutraceuticals, pharmaceuticals, and other industrially important bioactives. However, suboptimal yield and productivity of the bioactive of interest in local and robust wild-type strains are of perennial concerns for their industrial applications. To overcome such limitations, strain improvement through genetic engineering could play a decisive role. Though the advanced tools for genetic engineering have emerged at a greater pace, they still remain underused for microalgae as compared to other microorganisms. Pertaining to this, we reviewed the progress made so far in the development of molecular tools and techniques, and their deployment for microalgae strain improvement through genetic engineering. The recent availability of genome sequences and other omics datasets form diverse microalgae species have remarkable potential to guide strategic momentum in microalgae strain improvement program. This review focuses on the recent and significant improvements in the omics resources, mutant libraries, and high throughput screening methodologies helpful to augment research in the model and non-model microalgae. Authors have also summarized the case studies on genetically engineered microalgae and highlight the opportunities and challenges that are emerging from the current progress in the application of genome-editing to facilitate microalgal strain improvement. Toward the end, the regulatory and biosafety issues in the use of genetically engineered microalgae in commercial applications are described.
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Affiliation(s)
- Gulshan Kumar
- Agricultural Biotechnology Division, National Agri-Food Biotechnology Institute (NABI), Sahibzada Ajit Singh Nagar, India
| | - Ajam Shekh
- Plant Cell Biotechnology Department, CSIR-Central Food Technological Research Institute (CFTRI), Mysuru, India
| | - Sunaina Jakhu
- Agricultural Biotechnology Division, National Agri-Food Biotechnology Institute (NABI), Sahibzada Ajit Singh Nagar, India
| | - Yogesh Sharma
- Agricultural Biotechnology Division, National Agri-Food Biotechnology Institute (NABI), Sahibzada Ajit Singh Nagar, India
| | - Ritu Kapoor
- Agricultural Biotechnology Division, National Agri-Food Biotechnology Institute (NABI), Sahibzada Ajit Singh Nagar, India
| | - Tilak Raj Sharma
- Division of Crop Science, Indian Council of Agricultural Research, New Delhi, India
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8
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Larrea-Alvarez M, Purton S. Multigenic engineering of the chloroplast genome in the green alga Chlamydomonas reinhardtii. MICROBIOLOGY (READING, ENGLAND) 2020; 166:510-515. [PMID: 32250732 PMCID: PMC7376270 DOI: 10.1099/mic.0.000910] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 03/11/2020] [Indexed: 12/25/2022]
Abstract
The chloroplast of microalgae such as Chlamydomonas reinhardtii represents an attractive chassis for light-driven production of novel recombinant proteins and metabolites. Methods for the introduction and expression of transgenes in the chloroplast genome (=plastome) of C. reinhardtii are well-established and over 100 different proteins have been successfully produced. However, in almost all reported cases the complexity of the genetic engineering is low, and typically involves introduction into the plastome of just a single transgene together with a selectable marker. In order to exploit fully the potential of the algal chassis it is necessary to establish methods for multigenic engineering in which many transgenes can be stably incorporated into the plastome. This would allow the synthesis of multi-subunit proteins and the introduction into the chloroplast of whole new metabolic pathways. In this short communication we report a proof-of-concept study involving both a combinatorial and serial approach, with the goal of synthesizing five different test proteins in the C. reinhardtii chloroplast. Analysis of the various transgenic lines confirmed the successful integration of the transgenes and accumulation of the gene products. However, the work also highlights an issue of genetic instability when using the same untranslated region for each of the transgenes. Our findings therefore help to define appropriate strategies for robust multigenic engineering of the algal chloroplast.
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Affiliation(s)
- Marco Larrea-Alvarez
- Algal Research Group, Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, UK
- Present address: School of Biological Sciences and Engineering. Yachay-Tech University Hacienda San José, Urcuquí-Imbabura, Ecuador
| | - Saul Purton
- Algal Research Group, Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, UK
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9
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Kim SY, Kim KW, Kwon YM, Kim JYH. mCherry Protein as an In Vivo Quantitative Reporter of Gene Expression in the Chloroplast of Chlamydomonas reinhardtii. Mol Biotechnol 2020; 62:297-305. [PMID: 32185599 DOI: 10.1007/s12033-020-00249-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Microalgal chloroplasts have a substantial potential as a sustainable alternative to conventional hosts for recombinant protein production, due to their photosynthetic ability. However, realization of microalgal chloroplast as a platform for the production of recombinant proteins has suffered from difficulties in genetic manipulation and development of molecular tools, including reporter proteins. Here, we investigated the suitability of a fluorescent protein, mCherry, as a reporter for quantitative in vivo monitoring of gene expression in the chloroplast of Chlamydomonas reinhardtii. By analyzing cell growth, the fluorescence intensity of a mCherry-expressing strain, as well as auto-fluorescence, under different photoautotrophic culture conditions, we demonstrated a strong correlation between the fluorescence intensity of mCherry expressed in the chloroplast and its protein expression level. In addition, we found that the supply of CO2 and light energy can be an important factor for the synthesis of recombinant proteins in the microalgal chloroplast. Our results identified mCherry as a reliable and quantitative reporter for the study of gene expression in chloroplasts, which is essential for the biotechnological application of microalgal chloroplasts and for improved production of valuable recombinant proteins.
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Affiliation(s)
- Sun Young Kim
- Department of Applied Research, National Marine Biodiversity Institute of Korea, Jangsan-ro 101-75, Seocheon-gun, Chungcheongnam-do, 33662, South Korea
| | - Kyung Woo Kim
- Department of Applied Research, National Marine Biodiversity Institute of Korea, Jangsan-ro 101-75, Seocheon-gun, Chungcheongnam-do, 33662, South Korea
| | - Yong Min Kwon
- Department of Applied Research, National Marine Biodiversity Institute of Korea, Jangsan-ro 101-75, Seocheon-gun, Chungcheongnam-do, 33662, South Korea
| | - Jaoon Young Hwan Kim
- Department of Applied Research, National Marine Biodiversity Institute of Korea, Jangsan-ro 101-75, Seocheon-gun, Chungcheongnam-do, 33662, South Korea.
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10
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Ding Y, Vara Prasad CVNS, Wang B. Glycosylation on Unprotected or Partially Protected Acceptors. European J Org Chem 2020. [DOI: 10.1002/ejoc.201901675] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Yili Ding
- Life Science Department; Foshan University; 528000 Foshan Guangdong China
| | | | - Bingyun Wang
- Life Science Department; Foshan University; 528000 Foshan Guangdong China
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11
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Abstract
Microalgae are unicellular organisms that act as the crucial primary producers all over the world, typically found in marine and freshwater environments. Most of them can live photo-autotrophically, reproduce rapidly, and accumulate biomass in a short period efficiently. To adapt to the uninterrupted change of the environment, they evolve and differentiate continuously. As a result, some of them evolve special abilities such as toleration of extreme environment, generation of sophisticated structure to adapt to the environment, and avoid predators. Microalgae are believed to be promising bioreactors because of their high lipid and pigment contents. Genetic engineering technologies have given revolutions in the microalgal industry, which decoded the secrets of microalgal genes, express recombinant genes in microalgal genomes, and largely soar the accumulation of interested components in transgenic microalgae. However, owing to several obstructions, the industry of transgenic microalgae is still immature. Here, we provide an overview to emphasize the advantage and imperfection of the existing transgenic microalgal bioreactors.
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Affiliation(s)
- Zhi-Cong Liang
- College of Food Science and Engineering, South China University of Technology, Guangzhou, China
| | - Ming-Hua Liang
- College of Food Science and Engineering, South China University of Technology, Guangzhou, China
| | - Jian-Guo Jiang
- College of Food Science and Engineering, South China University of Technology, Guangzhou, China
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12
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Kong F, Yamaoka Y, Ohama T, Lee Y, Li-Beisson Y. Molecular Genetic Tools and Emerging Synthetic Biology Strategies to Increase Cellular Oil Content in Chlamydomonas reinhardtii. PLANT & CELL PHYSIOLOGY 2019; 60:1184-1196. [PMID: 30715500 DOI: 10.1093/pcp/pcz022] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 01/18/2019] [Indexed: 05/26/2023]
Abstract
Microalgae constitute a highly diverse group of eukaryotic and photosynthetic microorganisms that have developed extremely efficient systems for harvesting and transforming solar energy into energy-rich molecules such as lipids. Although microalgae are considered to be one of the most promising platforms for the sustainable production of liquid oil, the oil content of these organisms is naturally low, and algal oil production is currently not economically viable. Chlamydomonas reinhardtii (Chlamydomonas) is an established algal model due to its fast growth, high transformation efficiency, and well-understood physiology and to the availability of detailed genome information and versatile molecular tools for this organism. In this review, we summarize recent advances in the development of genetic manipulation tools for Chlamydomonas, from gene delivery methods to state-of-the-art genome-editing technologies and fluorescent dye-based high-throughput mutant screening approaches. Furthermore, we discuss practical strategies and toolkits that enhance transgene expression, such as choice of expression vector and background strain. We then provide examples of how advanced genetic tools have been used to increase oil content in Chlamydomonas. Collectively, the current literature indicates that microalgal oil content can be increased by overexpressing key enzymes that catalyze lipid biosynthesis, blocking lipid degradation, silencing metabolic pathways that compete with lipid biosynthesis and modulating redox state. The tools and knowledge generated through metabolic engineering studies should pave the way for developing a synthetic biological approach to enhance lipid productivity in microalgae.
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Affiliation(s)
- Fantao Kong
- Department of Integrative Bioscience & Biotechnology, Pohang University of Science and Technology, Pohang, Korea
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, China
| | - Yasuyo Yamaoka
- Department of Integrative Bioscience & Biotechnology, Pohang University of Science and Technology, Pohang, Korea
| | - Takeshi Ohama
- School of Environmental Science and Engineering, Kochi University of Technology (KUT), Tosayamada, Kochi, Japan
| | - Youngsook Lee
- Department of Integrative Bioscience & Biotechnology, Pohang University of Science and Technology, Pohang, Korea
- Department of Life Science, Pohang University of Science and Technology, Pohang, Korea
| | - Yonghua Li-Beisson
- Aix-Marseille Univ., CEA, CNRS, BIAM, UMR7265, CEA Cadarache, Saint-Paul-lez Durance F, France
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13
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Kwon YM, Kim KW, Choi TY, Kim SY, Kim JYH. Manipulation of the microalgal chloroplast by genetic engineering for biotechnological utilization as a green biofactory. World J Microbiol Biotechnol 2018; 34:183. [PMID: 30478596 DOI: 10.1007/s11274-018-2567-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 11/23/2018] [Indexed: 12/16/2022]
Abstract
The chloroplast is an essential organelle in microalgae for conducting photosynthesis, thus enabling the photoautotrophic growth of microalgae. In addition to photosynthesis, the chloroplast is capable of various biochemical processes for the synthesis of proteins, lipids, carbohydrates, and terpenoids. Due to these attractive characteristics, there has been increasing interest in the biotechnological utilization of microalgal chloroplast as a sustainable alternative to the conventional production platforms used in industrial biotechnology. Since the first demonstration of microalgal chloroplast transformation, significant development has occurred over recent decades in the manipulation of microalgal chloroplasts through genetic engineering. In the present review, we describe the advantages of the microalgal chloroplast as a production platform for various bioproducts, including recombinant proteins and high-value metabolites, features of chloroplast genetic systems, and the development of transformation methods, which represent important factors for gene expression in the chloroplast. Furthermore, we address the expression of various recombinant proteins in the microalgal chloroplast through genetic engineering, including reporters, biopharmaceutical proteins, and industrial enzymes. Finally, we present many efforts and achievements in the production of high-value metabolites in the microalgal chloroplast through metabolic engineering. Based on these efforts and advances, the microalgal chloroplast represents an economically viable and sustainable platform for biotechnological applications in the near future.
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Affiliation(s)
- Yong Min Kwon
- Department of Applied Research, National Marine Biodiversity Institute of Korea, Jangsan-ro 101-75, Seocheon, Chungcheongnamdo, 33662, Republic of Korea
| | - Kyung Woo Kim
- Department of Applied Research, National Marine Biodiversity Institute of Korea, Jangsan-ro 101-75, Seocheon, Chungcheongnamdo, 33662, Republic of Korea
| | - Tae-Young Choi
- Department of Genetic Resources Research, National Marine Biodiversity Institute of Korea, Jangsan-ro 101-75, Seocheon, Chungcheongnamdo, 33662, Republic of Korea
| | - Sun Young Kim
- Department of Applied Research, National Marine Biodiversity Institute of Korea, Jangsan-ro 101-75, Seocheon, Chungcheongnamdo, 33662, Republic of Korea
| | - Jaoon Young Hwan Kim
- Department of Applied Research, National Marine Biodiversity Institute of Korea, Jangsan-ro 101-75, Seocheon, Chungcheongnamdo, 33662, Republic of Korea.
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14
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Dyo YM, Purton S. The algal chloroplast as a synthetic biology platform for production of therapeutic proteins. Microbiology (Reading) 2018; 164:113-121. [DOI: 10.1099/mic.0.000599] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Affiliation(s)
- Yuliya M. Dyo
- Molecular Research of Microalgae Laboratory, M. A. Ajtkhozhin Institute of Molecular Biology and Biochemistry, Almaty, Kazakhstan
- Department of Biotechnology, Kazakh National Research Technology University, Almaty, Kazakhstan
| | - Saul Purton
- Algal Research Group, Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, UK
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Taunt HN, Stoffels L, Purton S. Green biologics: The algal chloroplast as a platform for making biopharmaceuticals. Bioengineered 2017; 9:48-54. [PMID: 28892417 PMCID: PMC5972929 DOI: 10.1080/21655979.2017.1377867] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Most commercial production of recombinant pharmaceutical proteins involves the use of mammalian cell lines, E. coli or yeast as the expression host. However, recent work has demonstrated the potential of eukaryotic microalgae as platforms for light-driven synthesis of such proteins. Expression in the algal chloroplast is particularly attractive since this organelle contains a minimal genome suitable for rapid engineering using synthetic biology approaches; with transgenes precisely targeted to specific genomic loci and amenable to high-level, regulated and stable expression. Furthermore, proteins can be tightly contained and bio-encapsulated in the chloroplast allowing accumulation of proteins otherwise toxic to the host, and opening up possibilities for low-cost, oral delivery of biologics. In this commentary we illustrate the technology with recent examples of hormones, protein antibiotics and immunotoxins successfully produced in the algal chloroplast, and highlight possible future applications.
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Affiliation(s)
- Henry N Taunt
- a Algenuity, Eden Laboratory , Stewartby , United Kingdom
| | - Laura Stoffels
- b Algal Research Group, Institute of Structural and Molecular Biology , University College London , Gower Street , London , United Kingdom
| | - Saul Purton
- b Algal Research Group, Institute of Structural and Molecular Biology , University College London , Gower Street , London , United Kingdom
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16
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Stoffels L, Taunt HN, Charalambous B, Purton S. Synthesis of bacteriophage lytic proteins against Streptococcus pneumoniae in the chloroplast of Chlamydomonas reinhardtii. PLANT BIOTECHNOLOGY JOURNAL 2017; 15:1130-1140. [PMID: 28160380 PMCID: PMC5552482 DOI: 10.1111/pbi.12703] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 01/06/2017] [Accepted: 01/29/2017] [Indexed: 05/12/2023]
Abstract
There is a pressing need to develop novel antibacterial agents given the widespread antibiotic resistance among pathogenic bacteria and the low specificity of the drugs available. Endolysins are antibacterial proteins that are produced by bacteriophage-infected cells to digest the bacterial cell wall for phage progeny release at the end of the lytic cycle. These highly efficient enzymes show a considerable degree of specificity for the target bacterium of the phage. Furthermore, the emergence of resistance against endolysins appears to be rare as the enzymes have evolved to target molecules in the cell wall that are essential for bacterial viability. Taken together, these factors make recombinant endolysins promising novel antibacterial agents. The chloroplast of the green unicellular alga Chlamydomonas reinhardtii represents an attractive platform for production of therapeutic proteins in general, not least due to the availability of established techniques for foreign gene expression, a lack of endotoxins or potentially infectious agents in the algal host, and low cost of cultivation. The chloroplast is particularly well suited to the production of endolysins as it mimics the native bacterial expression environment of these proteins while being devoid of their cell wall target. In this study, the endolysins Cpl-1 and Pal, specific to the major human pathogen Streptococcus pneumoniae, were produced in the C. reinhardtii chloroplast. The antibacterial activity of cell lysates and the isolated endolysins was demonstrated against different serotypes of S. pneumoniae, including clinical isolates and total recombinant protein yield was quantified at ~1.3 mg/g algal dry weight.
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Affiliation(s)
- Laura Stoffels
- Algal Biotechnology GroupInstitute of Structural and Molecular BiologyUniversity College LondonLondonUK
| | - Henry N. Taunt
- Algal Biotechnology GroupInstitute of Structural and Molecular BiologyUniversity College LondonLondonUK
- Present address:
AlgenuityEden LaboratoryBroadmead RoadStewartbyUK
| | - Bambos Charalambous
- Research Department of InfectionUniversity College London Medical SchoolLondonUK
| | - Saul Purton
- Algal Biotechnology GroupInstitute of Structural and Molecular BiologyUniversity College LondonLondonUK
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17
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Faè M, Accossato S, Cella R, Fontana F, Goldschmidt-Clermont M, Leelavathi S, Reddy VS, Longoni P. Comparison of transplastomic Chlamydomonas reinhardtii and Nicotiana tabacum expression system for the production of a bacterial endoglucanase. Appl Microbiol Biotechnol 2017; 101:4085-4092. [PMID: 28190097 DOI: 10.1007/s00253-017-8164-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 01/23/2017] [Accepted: 01/27/2017] [Indexed: 11/28/2022]
Abstract
The bulk production of recombinant enzymes by either prokaryotic or eukaryotic organisms might contribute to replace environmentally non-friendly chemistry-based industrial processes with enzyme-based biocatalysis, provided the cost of enzyme production is low. In this context, it is worth noting that the production of recombinant proteins by photosynthetic organisms offer both eukaryotic (nuclear) and prokaryotic (chloroplast) alternatives, along with the advantage of an autotrophic nutrition. Compared to nuclear transformation, chloroplast transformation generally allows a higher level of accumulation of the recombinant protein of interest. Furthermore, among the photosynthetic organisms, there is a choice of using either multicellular or unicellular ones. Tobacco, being a non-food and non-feed plant, has been considered as a good choice for producing enzymes with applications in technical industry, using a transplastomic approach. Also, unicellular green algae, in particular Chlamydomonas reinhardtii, have been proposed as candidate organisms for the production of recombinant proteins. In the light of the different features of these two transplastomic systems, we decided to make a direct comparison of the efficiency of production of a bacterial endoglucanase. With respect to the amount obtained, 14 mg g-1 of biomass fresh weight equivalent to 8-10% of the total protein content and estimated production cost, 1.5-2€ kg-1, tobacco proved to be far more favorable for bulk enzyme production when compared to C. reinhardtii which accumulated this endoglucanase at 0.003% of the total protein.
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Affiliation(s)
- Matteo Faè
- Department of Biology and Biotechnology, University of Pavia, Via Ferrata 9, 27100, Pavia, Italy
| | - Sonia Accossato
- Department of Biology and Biotechnology, University of Pavia, Via Ferrata 9, 27100, Pavia, Italy
- Laboratory of Plant Physiology, University of Neuchâtel, Rue Emilie-Argand 11, CH-2000, Neuchâtel, Switzerland
| | - Rino Cella
- Department of Biology and Biotechnology, University of Pavia, Via Ferrata 9, 27100, Pavia, Italy
| | - Fabrizia Fontana
- Department of Botany and Plant Biology, University of Geneva, 30 Quai Ernest Ansermet, Sciences III, CH-1211, Genève, Switzerland
| | - Michel Goldschmidt-Clermont
- Department of Botany and Plant Biology, University of Geneva, 30 Quai Ernest Ansermet, Sciences III, CH-1211, Genève, Switzerland
| | - Sadhu Leelavathi
- Plant Transformation Group, International Center for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Vanga Siva Reddy
- Plant Transformation Group, International Center for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Paolo Longoni
- Department of Botany and Plant Biology, University of Geneva, 30 Quai Ernest Ansermet, Sciences III, CH-1211, Genève, Switzerland.
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Specht EA, Karunanithi PS, Gimpel JA, Ansari WS, Mayfield SP. Host Organisms: Algae. Ind Biotechnol (New Rochelle N Y) 2016. [DOI: 10.1002/9783527807796.ch16] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Affiliation(s)
- Elizabeth A. Specht
- University of California; California Center for Algae Biotechnology; Division of Biological Sciences; 9500 Gilman Drive San Diego, La Jolla CA 92093 USA
| | - Prema S. Karunanithi
- University of California; California Center for Algae Biotechnology; Division of Biological Sciences; 9500 Gilman Drive San Diego, La Jolla CA 92093 USA
| | - Javier A. Gimpel
- Centre for Biotechnology and Bioengineering; Department of Chemical Engineering and Biotechnology, Universidad de Chile; 851 Beaucheff Santiago USA
| | - William S. Ansari
- University of California; California Center for Algae Biotechnology; Division of Biological Sciences; 9500 Gilman Drive San Diego, La Jolla CA 92093 USA
| | - Stephen P. Mayfield
- University of California; California Center for Algae Biotechnology; Division of Biological Sciences; 9500 Gilman Drive San Diego, La Jolla CA 92093 USA
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Nielsen AZ, Mellor SB, Vavitsas K, Wlodarczyk AJ, Gnanasekaran T, Perestrello Ramos H de Jesus M, King BC, Bakowski K, Jensen PE. Extending the biosynthetic repertoires of cyanobacteria and chloroplasts. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2016; 87:87-102. [PMID: 27005523 DOI: 10.1111/tpj.13173] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 03/16/2016] [Accepted: 03/18/2016] [Indexed: 05/20/2023]
Abstract
Chloroplasts in plants and algae and photosynthetic microorganisms such as cyanobacteria are emerging hosts for sustainable production of valuable biochemicals, using only inorganic nutrients, water, CO2 and light as inputs. In the past decade, many bioengineering efforts have focused on metabolic engineering and synthetic biology in the chloroplast or in cyanobacteria for the production of fuels, chemicals and complex, high-value bioactive molecules. Biosynthesis of all these compounds can be performed in photosynthetic organelles/organisms by heterologous expression of the appropriate pathways, but this requires optimization of carbon flux and reducing power, and a thorough understanding of regulatory pathways. Secretion or storage of the compounds produced can be exploited for the isolation or confinement of the desired compounds. In this review, we explore the use of chloroplasts and cyanobacteria as biosynthetic compartments and hosts, and we estimate the levels of production to be expected from photosynthetic hosts in light of the fraction of electrons and carbon that can potentially be diverted from photosynthesis. The supply of reducing power, in the form of electrons derived from the photosynthetic light reactions, appears to be non-limiting, but redirection of the fixed carbon via precursor molecules presents a challenge. We also discuss the available synthetic biology tools and the need to expand the molecular toolbox to facilitate cellular reprogramming for increased production yields in both cyanobacteria and chloroplasts.
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Affiliation(s)
- Agnieszka Zygadlo Nielsen
- Copenhagen Plant Science Center, VILLUM Research Center for Plant Plasticity, Center for Synthetic Biology 'bioSYNergy', Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark
| | - Silas Busck Mellor
- Copenhagen Plant Science Center, VILLUM Research Center for Plant Plasticity, Center for Synthetic Biology 'bioSYNergy', Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark
| | - Konstantinos Vavitsas
- Copenhagen Plant Science Center, VILLUM Research Center for Plant Plasticity, Center for Synthetic Biology 'bioSYNergy', Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark
| | - Artur Jacek Wlodarczyk
- Copenhagen Plant Science Center, VILLUM Research Center for Plant Plasticity, Center for Synthetic Biology 'bioSYNergy', Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark
| | - Thiyagarajan Gnanasekaran
- Copenhagen Plant Science Center, VILLUM Research Center for Plant Plasticity, Center for Synthetic Biology 'bioSYNergy', Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark
| | - Maria Perestrello Ramos H de Jesus
- Copenhagen Plant Science Center, VILLUM Research Center for Plant Plasticity, Center for Synthetic Biology 'bioSYNergy', Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark
| | - Brian Christopher King
- Copenhagen Plant Science Center, VILLUM Research Center for Plant Plasticity, Center for Synthetic Biology 'bioSYNergy', Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark
| | - Kamil Bakowski
- Copenhagen Plant Science Center, VILLUM Research Center for Plant Plasticity, Center for Synthetic Biology 'bioSYNergy', Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark
| | - Poul Erik Jensen
- Copenhagen Plant Science Center, VILLUM Research Center for Plant Plasticity, Center for Synthetic Biology 'bioSYNergy', Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark
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20
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Wannathong T, Waterhouse JC, Young REB, Economou CK, Purton S. New tools for chloroplast genetic engineering allow the synthesis of human growth hormone in the green alga Chlamydomonas reinhardtii. Appl Microbiol Biotechnol 2016; 100:5467-77. [PMID: 26887319 PMCID: PMC4875957 DOI: 10.1007/s00253-016-7354-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 01/18/2016] [Accepted: 01/23/2016] [Indexed: 01/09/2023]
Abstract
In recent years, there has been an increasing interest in the exploitation of microalgae in industrial biotechnology. Potentially, these phototrophic eukaryotes could be used for the low-cost synthesis of valuable recombinant products such as bioactive metabolites and therapeutic proteins. The algal chloroplast in particular represents an attractive target for such genetic engineering, both because it houses major metabolic pathways and because foreign genes can be targeted to specific loci within the chloroplast genome, resulting in high-level, stable expression. However, routine methods for chloroplast genetic engineering are currently available only for one species-Chlamydomonas reinhardtii-and even here, there are limitations to the existing technology, including the need for an expensive biolistic device for DNA delivery, the lack of robust expression vectors, and the undesirable use of antibiotic resistance markers. Here, we describe a new strain and vectors for targeted insertion of transgenes into a neutral chloroplast locus that (i) allow scar-less fusion of a transgenic coding sequence to the promoter/5'UTR element of the highly expressed endogenous genes psaA or atpA, (ii) employ the endogenous gene psbH as an effective but benign selectable marker, and (iii) ensure the successful integration of the transgene construct in all transformant lines. Transformation is achieved by a simple and cheap method of agitation of a DNA/cell suspension with glass beads, with selection based on the phototrophic rescue of a cell wall-deficient ΔpsbH strain. We demonstrate the utility of these tools in the creation of a transgenic line that produces high levels of functional human growth hormone.
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Affiliation(s)
- Thanyanan Wannathong
- Department of Biology, Faculty of Science, Silpakorn University, Nakornpathom, 73000, Thailand
| | - Janet C Waterhouse
- Algal Research Group, Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Rosanna E B Young
- Algal Research Group, Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Chloe K Economou
- Algal Research Group, Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Saul Purton
- Algal Research Group, Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, UK.
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21
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Young REB, Purton S. Codon reassignment to facilitate genetic engineering and biocontainment in the chloroplast of Chlamydomonas reinhardtii. PLANT BIOTECHNOLOGY JOURNAL 2016; 14:1251-60. [PMID: 26471875 PMCID: PMC5102678 DOI: 10.1111/pbi.12490] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 09/08/2015] [Accepted: 09/13/2015] [Indexed: 05/18/2023]
Abstract
There is a growing interest in the use of microalgae as low-cost hosts for the synthesis of recombinant products such as therapeutic proteins and bioactive metabolites. In particular, the chloroplast, with its small, genetically tractable genome (plastome) and elaborate metabolism, represents an attractive platform for genetic engineering. In Chlamydomonas reinhardtii, none of the 69 protein-coding genes in the plastome uses the stop codon UGA, therefore this spare codon can be exploited as a useful synthetic biology tool. Here, we report the assignment of the codon to one for tryptophan and show that this can be used as an effective strategy for addressing a key problem in chloroplast engineering: namely, the assembly of expression cassettes in Escherichia coli when the gene product is toxic to the bacterium. This problem arises because the prokaryotic nature of chloroplast promoters and ribosome-binding sites used in such cassettes often results in transgene expression in E. coli, and is a potential issue when cloning genes for metabolic enzymes, antibacterial proteins and integral membrane proteins. We show that replacement of tryptophan codons with the spare codon (UGG→UGA) within a transgene prevents functional expression in E. coli and in the chloroplast, and that co-introduction of a plastidial trnW gene carrying a modified anticodon restores function only in the latter by allowing UGA readthrough. We demonstrate the utility of this system by expressing two genes known to be highly toxic to E. coli and discuss its value in providing an enhanced level of biocontainment for transplastomic microalgae.
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Affiliation(s)
- Rosanna E B Young
- Algal Research Group, Institute of Structural and Molecular Biology, University College London, London, UK
| | - Saul Purton
- Algal Research Group, Institute of Structural and Molecular Biology, University College London, London, UK
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22
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Scranton MA, Ostrand JT, Georgianna DR, Lofgren SM, Li D, Ellis RC, Carruthers DN, Dräger A, Masica DL, Mayfield SP. Synthetic promoters capable of driving robust nuclear gene expression in the green alga Chlamydomonas reinhardtii. ALGAL RES 2016. [DOI: 10.1016/j.algal.2016.02.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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23
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Gimpel JA, Henríquez V, Mayfield SP. In Metabolic Engineering of Eukaryotic Microalgae: Potential and Challenges Come with Great Diversity. Front Microbiol 2015; 6:1376. [PMID: 26696985 PMCID: PMC4678203 DOI: 10.3389/fmicb.2015.01376] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 11/20/2015] [Indexed: 12/03/2022] Open
Abstract
The great phylogenetic diversity of microalgae is corresponded by a wide arrange of interesting and useful metabolites. Nonetheless metabolic engineering in microalgae has been limited, since specific transformation tools must be developed for each species for either the nuclear or chloroplast genomes. Microalgae as production platforms for metabolites offer several advantages over plants and other microorganisms, like the ability of GMO containment and reduced costs in culture media, respectively. Currently, microalgae have proved particularly well suited for the commercial production of omega-3 fatty acids and carotenoids. Therefore most metabolic engineering strategies have been developed for these metabolites. Microalgal biofuels have also drawn great attention recently, resulting in efforts for improving the production of hydrogen and photosynthates, particularly triacylglycerides. Metabolic pathways of microalgae have also been manipulated in order to improve photosynthetic growth under specific conditions and for achieving trophic conversion. Although these pathways are not strictly related to secondary metabolites, the synthetic biology approaches could potentially be translated to this field and will also be discussed.
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Affiliation(s)
- Javier A Gimpel
- Chemical and Biotechnology Engineering Department, Centre for Biotechnology and Bioengineering, Universidad de Chile Santiago, Chile
| | - Vitalia Henríquez
- Instituto de Biología, Pontificia Universidad Católica de Valparaíso Valparaiso, Chile
| | - Stephen P Mayfield
- Division of Biological Sciences, California Center for Algae Biotechnology, University of California, San Diego La Jolla, CA, USA
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Gangl D, Zedler JAZ, Rajakumar PD, Martinez EMR, Riseley A, Włodarczyk A, Purton S, Sakuragi Y, Howe CJ, Jensen PE, Robinson C. Biotechnological exploitation of microalgae. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:6975-90. [PMID: 26400987 DOI: 10.1093/jxb/erv426] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Microalgae are a diverse group of single-cell photosynthetic organisms that include cyanobacteria and a wide range of eukaryotic algae. A number of microalgae contain high-value compounds such as oils, colorants, and polysaccharides, which are used by the food additive, oil, and cosmetic industries, among others. They offer the potential for rapid growth under photoautotrophic conditions, and they can grow in a wide range of habitats. More recently, the development of genetic tools means that a number of species can be transformed and hence used as cell factories for the production of high-value chemicals or recombinant proteins. In this article, we review exploitation use of microalgae with a special emphasis on genetic engineering approaches to develop cell factories, and the use of synthetic ecology approaches to maximize productivity. We discuss the success stories in these areas, the hurdles that need to be overcome, and the potential for expanding the industry in general.
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Affiliation(s)
- Doris Gangl
- Centre for Molecular Processing, School of Biosciences, University of Kent, Canterbury CT2 7NJ, UK
| | - Julie A Z Zedler
- Centre for Molecular Processing, School of Biosciences, University of Kent, Canterbury CT2 7NJ, UK
| | - Priscilla D Rajakumar
- Institute of Structural & Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Erick M Ramos Martinez
- Copenhagen Plant Science Centre, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Copenhagen, Denmark
| | - Anthony Riseley
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
| | - Artur Włodarczyk
- Copenhagen Plant Science Centre, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Copenhagen, Denmark
| | - Saul Purton
- Institute of Structural & Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Yumiko Sakuragi
- Copenhagen Plant Science Centre, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Copenhagen, Denmark
| | - Christopher J Howe
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
| | - Poul Erik Jensen
- Copenhagen Plant Science Centre, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Copenhagen, Denmark
| | - Colin Robinson
- Centre for Molecular Processing, School of Biosciences, University of Kent, Canterbury CT2 7NJ, UK
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Scranton MA, Ostrand JT, Fields FJ, Mayfield SP. Chlamydomonas as a model for biofuels and bio-products production. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 82:523-531. [PMID: 25641390 PMCID: PMC5531182 DOI: 10.1111/tpj.12780] [Citation(s) in RCA: 141] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 01/08/2015] [Accepted: 01/12/2015] [Indexed: 05/18/2023]
Abstract
Developing renewable energy sources is critical to maintaining the economic growth of the planet while protecting the environment. First generation biofuels focused on food crops like corn and sugarcane for ethanol production, and soybean and palm for biodiesel production. Second generation biofuels based on cellulosic ethanol produced from terrestrial plants, has received extensive funding and recently pilot facilities have been commissioned, but to date output of fuels from these sources has fallen well short of what is needed. Recent research and pilot demonstrations have highlighted the potential of algae as one of the most promising sources of sustainable liquid transportation fuels. Algae have also been established as unique biofactories for industrial, therapeutic, and nutraceutical co-products. Chlamydomonas reinhardtii's long established role in the field of basic research in green algae has paved the way for understanding algal metabolism and developing genetic engineering protocols. These tools are now being utilized in C. reinhardtii and in other algal species for the development of strains to maximize biofuels and bio-products yields from the lab to the field.
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26
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Barrera DJ, Rosenberg JN, Chiu JG, Chang YN, Debatis M, Ngoi SM, Chang JT, Shoemaker CB, Oyler GA, Mayfield SP. Algal chloroplast produced camelid VH H antitoxins are capable of neutralizing botulinum neurotoxin. PLANT BIOTECHNOLOGY JOURNAL 2015; 13:117-24. [PMID: 25229405 PMCID: PMC4620920 DOI: 10.1111/pbi.12244] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 06/11/2014] [Accepted: 07/16/2014] [Indexed: 05/18/2023]
Abstract
We have produced three antitoxins consisting of the variable domains of camelid heavy chain-only antibodies (VH H) by expressing the genes in the chloroplast of green algae. These antitoxins accumulate as soluble proteins capable of binding and neutralizing botulinum neurotoxin. Furthermore, they accumulate at up to 5% total soluble protein, sufficient expression to easily produce these antitoxins at scale from algae. The genes for the three different antitoxins were transformed into Chlamydomonas reinhardtii chloroplasts and their products purified from algae lysates and assayed for in vitro biological activity using toxin protection assays. The produced antibody domains bind to botulinum neurotoxin serotype A (BoNT/A) with similar affinities as camelid antibodies produced in Escherichia coli, and they are similarly able to protect primary rat neurons from intoxication by BoNT/A. Furthermore, the camelid antibodies were produced in algae without the use of solubilization tags commonly employed in E. coli. These camelid antibody domains are potent antigen-binding proteins and the heterodimer fusion protein containing two VH H domains was capable of neutralizing BoNT/A at near equimolar concentrations with the toxin. Intact antibody domains were detected in the gastrointestinal (GI) tract of mice treated orally with antitoxin-producing microalgae. These findings support the use of orally delivered antitoxins produced in green algae as a novel treatment for botulism.
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Affiliation(s)
- Daniel J Barrera
- Division of Biological Sciences, The California Center for Algae Biotechnology, UC-San Diego, La Jolla, CA, USA
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27
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Specht EA, Mayfield SP. Algae-based oral recombinant vaccines. Front Microbiol 2014; 5:60. [PMID: 24596570 PMCID: PMC3925837 DOI: 10.3389/fmicb.2014.00060] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 01/30/2014] [Indexed: 11/25/2022] Open
Abstract
Recombinant subunit vaccines are some of the safest and most effective vaccines available, but their high cost and the requirement of advanced medical infrastructure for administration make them impractical for many developing world diseases. Plant-based vaccines have shifted that paradigm by paving the way for recombinant vaccine production at agricultural scale using an edible host. However, enthusiasm for “molecular pharming” in food crops has waned in the last decade due to difficulty in developing transgenic crop plants and concerns of contaminating the food supply. Microalgae could be poised to become the next candidate in recombinant subunit vaccine production, as they present several advantages over terrestrial crop plant-based platforms including scalable and contained growth, rapid transformation, easily obtained stable cell lines, and consistent transgene expression levels. Algae have been shown to accumulate and properly fold several vaccine antigens, and efforts are underway to create recombinant algal fusion proteins that can enhance antigenicity for effective orally delivered vaccines. These approaches have the potential to revolutionize the way subunit vaccines are made and delivered – from costly parenteral administration of purified protein, to an inexpensive oral algae tablet with effective mucosal and systemic immune reactivity.
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Affiliation(s)
- Elizabeth A Specht
- California Center for Algae Biotechnology, University of California at San Diego La Jolla, CA, USA
| | - Stephen P Mayfield
- California Center for Algae Biotechnology, University of California at San Diego La Jolla, CA, USA
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Production of anti-cancer immunotoxins in algae: Ribosome inactivating proteins as fusion partners. Biotechnol Bioeng 2013; 110:2826-35. [DOI: 10.1002/bit.24966] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 05/03/2013] [Accepted: 05/24/2013] [Indexed: 12/27/2022]
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