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Gionfriddo M, Rhodes T, Whitney SM. Perspectives on improving crop Rubisco by directed evolution. Semin Cell Dev Biol 2024; 155:37-47. [PMID: 37085353 DOI: 10.1016/j.semcdb.2023.04.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 04/14/2023] [Accepted: 04/15/2023] [Indexed: 04/23/2023]
Abstract
Rubisco catalyses the entry of almost all CO2 into the biosphere and is often the rate-limiting step in plant photosynthesis and growth. Its notoriety as the most abundant protein on Earth stems from the slow and error-prone catalytic properties that require plants, cyanobacteria, algae and photosynthetic bacteria to produce it in high amounts. Efforts to improve the CO2-fixing properties of plant Rubisco has been spurred on by the discovery of more effective isoforms in some algae with the potential to significantly improve crop productivity. Incompatibilities between the protein folding machinery of leaf and algae chloroplasts have, so far, prevented efforts to transplant these more effective Rubisco variants into plants. There is therefore increasing interest in improving Rubisco catalysis by directed (laboratory) evolution. Here we review the advances being made in, and the ongoing challenges with, improving the solubility and/or carboxylation activity of differing non-plant Rubisco lineages. We provide perspectives on new opportunities for the directed evolution of crop Rubiscos and the existing plant transformation capabilities available to evaluate the extent to which Rubisco activity improvements can benefit agricultural productivity.
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Affiliation(s)
- Matteo Gionfriddo
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia; Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - Timothy Rhodes
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
| | - Spencer M Whitney
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia.
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2
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Yang Q, Xin C, Xiao QS, Lin YT, Li L, Zhao JL. Codon usage bias in chloroplast genes implicate adaptive evolution of four ginger species. FRONTIERS IN PLANT SCIENCE 2023; 14:1304264. [PMID: 38169692 PMCID: PMC10758403 DOI: 10.3389/fpls.2023.1304264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 12/01/2023] [Indexed: 01/05/2024]
Abstract
Codon usage bias (CUB) refers to different codons exhibiting varying frequencies of usage in the genome. Studying CUB is crucial for understanding genome structure, function, and evolutionary processes. Herein, we investigated the codon usage patterns and influencing factors of protein-coding genes in the chloroplast genomes of four sister genera (monophyletic Roscoea and Cautleya, and monophyletic Pommereschea and Rhynchanthus) from the Zingiberaceae family with contrasting habitats in southwestern China. These genera exhibit distinct habitats, providing a unique opportunity to explore the adaptive evolution of codon usage. We conducted a comprehensive analysis of nucleotide composition and codon usage on protein-coding genes in the chloroplast genomes. The study focused on understanding the relationship between codon usage and environmental adaptation, with a particular emphasis on genes associated with photosynthesis. Nucleotide composition analysis revealed that the overall G/C content of the coding genes was ˂ 48%, indicating an enrichment of A/T bases. Additionally, synonymous and optimal codons were biased toward ending with A/U bases. Natural selection is the primary factor influencing CUB characteristics, particularly photosynthesis-associated genes. We observed differential gene expressions related to light adaptation among sister genera inhabiting different environments. Certain codons were favored under specific conditions, possibly contributing to gene expression regulation in particular environments. This study provides insights into the adaptive evolution of these sister genera by analyzing CUB and offers theoretical assistance for understanding gene expression and regulation. In addition, the data support the relationship between RNA editing and CUB, and the findings shed light on potential research directions for investigating adaptive evolution.
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Affiliation(s)
- Qian Yang
- Ministry of Education Key Laboratory for Transboundary Ecosecurity of Southwest China, Yunnan Key Laboratory of Plant Reproductive Adaptation and Evolutionary Ecology and Centre for Invasion Biology, Institute of Biodiversity, School of Ecology and Environmental Science, Yunnan University, Kunming, Yunnan, China
| | - Cheng Xin
- School of Life Sciences, Zhengzhou University, Zhengzhou, China
| | - Qing-Song Xiao
- Ministry of Education Key Laboratory for Transboundary Ecosecurity of Southwest China, Yunnan Key Laboratory of Plant Reproductive Adaptation and Evolutionary Ecology and Centre for Invasion Biology, Institute of Biodiversity, School of Ecology and Environmental Science, Yunnan University, Kunming, Yunnan, China
| | - Ya-Ting Lin
- Ministry of Education Key Laboratory for Transboundary Ecosecurity of Southwest China, Yunnan Key Laboratory of Plant Reproductive Adaptation and Evolutionary Ecology and Centre for Invasion Biology, Institute of Biodiversity, School of Ecology and Environmental Science, Yunnan University, Kunming, Yunnan, China
| | - Li Li
- Ministry of Education Key Laboratory for Transboundary Ecosecurity of Southwest China, Yunnan Key Laboratory of Plant Reproductive Adaptation and Evolutionary Ecology and Centre for Invasion Biology, Institute of Biodiversity, School of Ecology and Environmental Science, Yunnan University, Kunming, Yunnan, China
| | - Jian-Li Zhao
- Ministry of Education Key Laboratory for Transboundary Ecosecurity of Southwest China, Yunnan Key Laboratory of Plant Reproductive Adaptation and Evolutionary Ecology and Centre for Invasion Biology, Institute of Biodiversity, School of Ecology and Environmental Science, Yunnan University, Kunming, Yunnan, China
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3
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Zhou Y, Gunn LH, Birch R, Andersson I, Whitney SM. Grafting Rhodobacter sphaeroides with red algae Rubisco to accelerate catalysis and plant growth. NATURE PLANTS 2023; 9:978-986. [PMID: 37291398 DOI: 10.1038/s41477-023-01436-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Accepted: 05/10/2023] [Indexed: 06/10/2023]
Abstract
Improving the carboxylation properties of Rubisco has primarily arisen from unforeseen amino acid substitutions remote from the catalytic site. The unpredictability has frustrated rational design efforts to enhance plant Rubisco towards the prized growth-enhancing carboxylation properties of red algae Griffithsia monilis GmRubisco. To address this, we determined the crystal structure of GmRubisco to 1.7 Å. Three structurally divergent domains were identified relative to the red-type bacterial Rhodobacter sphaeroides RsRubisco that, unlike GmRubisco, are expressed in Escherichia coli and plants. Kinetic comparison of 11 RsRubisco chimaeras revealed that incorporating C329A and A332V substitutions from GmRubisco Loop 6 (corresponding to plant residues 328 and 331) into RsRubisco increased the carboxylation rate (kcatc) by 60%, the carboxylation efficiency in air by 22% and the CO2/O2 specificity (Sc/o) by 7%. Plastome transformation of this RsRubisco Loop 6 mutant into tobacco enhanced photosynthesis and growth up to twofold over tobacco producing wild-type RsRubisco. Our findings demonstrate the utility of RsRubisco for the identification and in planta testing of amino acid grafts from algal Rubisco that can enhance the enzyme's carboxylase potential.
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Affiliation(s)
- Yu Zhou
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Laura H Gunn
- Laboratory of Molecular Biophysics, Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Rosemary Birch
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Inger Andersson
- Laboratory of Molecular Biophysics, Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
- Norwegian College of Fisheries Sciences, UiT Arctic University of Norway, Tromsø, Norway
- Institute of Biotechnology, Academy of Sciences of the Czech Republic, Biocev, Vestec, Czech Republic
| | - Spencer M Whitney
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia.
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4
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Chen T, Hojka M, Davey P, Sun Y, Dykes GF, Zhou F, Lawson T, Nixon PJ, Lin Y, Liu LN. Engineering α-carboxysomes into plant chloroplasts to support autotrophic photosynthesis. Nat Commun 2023; 14:2118. [PMID: 37185249 PMCID: PMC10130085 DOI: 10.1038/s41467-023-37490-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 03/17/2023] [Indexed: 05/17/2023] Open
Abstract
The growth in world population, climate change, and resource scarcity necessitate a sustainable increase in crop productivity. Photosynthesis in major crops is limited by the inefficiency of the key CO2-fixing enzyme Rubisco, owing to its low carboxylation rate and poor ability to discriminate between CO2 and O2. In cyanobacteria and proteobacteria, carboxysomes function as the central CO2-fixing organelles that elevate CO2 levels around encapsulated Rubisco to enhance carboxylation. There is growing interest in engineering carboxysomes into crop chloroplasts as a potential route for improving photosynthesis and crop yields. Here, we generate morphologically correct carboxysomes in tobacco chloroplasts by transforming nine carboxysome genetic components derived from a proteobacterium. The chloroplast-expressed carboxysomes display a structural and functional integrity comparable to native carboxysomes and support autotrophic growth and photosynthesis of the transplastomic plants at elevated CO2. Our study provides proof-of-concept for a route to engineering fully functional CO2-fixing modules and entire CO2-concentrating mechanisms into chloroplasts to improve crop photosynthesis and productivity.
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Affiliation(s)
- Taiyu Chen
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, UK
- National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research, Huazhong Agricultural University, 430070, Wuhan, China
| | - Marta Hojka
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Philip Davey
- School of Life Sciences, University of Essex, Colchester, CO4 4SQ, UK
| | - Yaqi Sun
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, UK
| | - Gregory F Dykes
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, UK
| | - Fei Zhou
- National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research, Huazhong Agricultural University, 430070, Wuhan, China
| | - Tracy Lawson
- School of Life Sciences, University of Essex, Colchester, CO4 4SQ, UK
| | - Peter J Nixon
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Yongjun Lin
- National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research, Huazhong Agricultural University, 430070, Wuhan, China.
| | - Lu-Ning Liu
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, UK.
- College of Marine Life Sciences, and Frontiers Science Center for Deep Ocean Multispheres and Earth System, Ocean University of China, 266003, Qingdao, China.
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5
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Pan Y, Cao Y, Chai Y, Meng X, Wang M, Wang G, Guo S. Identification of photosynthetic parameters for superior yield of two super hybrid rice varieties: A cross-scale study from leaf to canopy. FRONTIERS IN PLANT SCIENCE 2023; 14:1110257. [PMID: 36866365 PMCID: PMC9971572 DOI: 10.3389/fpls.2023.1110257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 02/01/2023] [Indexed: 06/18/2023]
Abstract
Enhancing photosynthetic capacity is widely accepted as critical to advancing crop yield. Therefore, identifying photosynthetic parameters positively related to biomass accumulation in elite cultivars is the major focus of current rice research. In this work, we assessed leaf photosynthetic performance, canopy photosynthesis, and yield attributes of super hybrid rice cultivars Y-liangyou 3218 (YLY3218) and Y-liangyou 5867 (YLY5867) at tillering stage and flowering stage, using inbred super rice cultivars Zhendao11(ZD11) and Nanjing 9108 (NJ9108) as control. A diurnal canopy photosynthesis model was applied to estimate the influence of key environmental factors, canopy attributes, and canopy nitrogen status on daily aboveground biomass increment (AMDAY). Results showed that primarily the light-saturated photosynthetic rate at tillering stage contributed to the advancing yield and biomass of super hybrid rice in comparison to inbred super rice, and the light-saturated photosynthetic rate between them was similar at flowering stage. At tillering stage, the higher CO2 diffusion capacity, together with higher biochemical capacity (i.e., maximum carboxylation rate of Rubisco, maximum electron transport rate (J max), and triose phosphate utilization rate) favored leaf photosynthesis of super hybrid rice. Similarly, AMDAY in super hybrid rice was higher than inbred super rice at tillering stage, and comparable at flowering stage partially due to increased canopy nitrogen concentration (SLNave) of inbred super rice. At tillering stage, model simulation revealed that replacement of J max and g m in inbred super rice by super hybrid rice always had a positive effect on AMDAY, and the averaged AMDAY increment was 5.7% and 3.4%, respectively. Simultaneously, the 20% enhancement of total canopy nitrogen concentration through the improvement of SLNave (TNC-SLNave) resulted in the highest AMDAY across cultivars, with an average increase of 11.2%. In conclusion, the advancing yield performance of YLY3218 and YLY5867 was due to the higher J max and g m at tillering stage, and TCN-SLNave is a promising target for future super rice breeding programs.
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Affiliation(s)
- Yonghui Pan
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Yiwen Cao
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Yixiao Chai
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Xusheng Meng
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Min Wang
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Guanjun Wang
- Center of Agricultural Green Development Promotion, Fuyang, Anhui, China
| | - Shiwei Guo
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, Jiangsu, China
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6
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Jin K, Chen G, Yang Y, Zhang Z, Lu T. Strategies for manipulating Rubisco and creating photorespiratory bypass to boost C 3 photosynthesis: Prospects on modern crop improvement. PLANT, CELL & ENVIRONMENT 2023; 46:363-378. [PMID: 36444099 DOI: 10.1111/pce.14500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 11/25/2022] [Accepted: 11/26/2022] [Indexed: 06/16/2023]
Abstract
Photosynthesis is a process that uses solar energy to fix CO2 in the air and converts it into sugar, and ultimately powers almost all life activities on the earth. C3 photosynthesis is the most common form of photosynthesis in crops. Current efforts of increasing crop yields in response to growing global food requirement are mostly focused on improving C3 photosynthesis. In this review, we summarized the strategies of C3 photosynthesis improvement in terms of Rubisco properties and photorespiratory limitation. Potential engineered targets include Rubisco subunits and their catalytic sites, Rubisco assembly chaperones, and Rubisco activase. In addition, we reviewed multiple photorespiratory bypasses built by strategies of synthetic biology to reduce the release of CO2 and ammonia and minimize energy consumption by photorespiration. The potential strategies are suggested to enhance C3 photosynthesis and boost crop production.
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Affiliation(s)
- Kaining Jin
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, P. R. China
- Department of Plant Sciences, Centre for Crop Systems Analysis, Wageningen University & Research, Wageningen, The Netherlands
| | - Guoxin Chen
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, P. R. China
| | - Yirong Yang
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, P. R. China
| | - Zhiguo Zhang
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, P. R. China
| | - Tiegang Lu
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, P. R. China
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7
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Buck S, Rhodes T, Gionfriddo M, Skinner T, Yuan D, Birch R, Kapralov MV, Whitney SM. Escherichia coli expressing chloroplast chaperones as a proxy to test heterologous Rubisco production in leaves. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:664-676. [PMID: 36322613 DOI: 10.1093/jxb/erac435] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 10/31/2022] [Indexed: 06/16/2023]
Abstract
Rubisco is a fundamental enzyme in photosynthesis and therefore for life. Efforts to improve plant Rubisco performance have been hindered by the enzymes' complex chloroplast biogenesis requirements. New Synbio approaches, however, now allow the production of some plant Rubisco isoforms in Escherichia coli. While this enhances opportunities for catalytic improvement, there remain limitations in the utility of the expression system. Here we generate, optimize, and test a robust Golden Gate cloning E. coli expression system incorporating the protein folding machinery of tobacco chloroplasts. By comparing the expression of different plant Rubiscos in both E. coli and plastome-transformed tobacco, we show that the E. coli expression system can accurately predict high level Rubisco production in chloroplasts but poorly forecasts the biogenesis potential of isoforms with impaired production in planta. We reveal that heterologous Rubisco production in E. coli and tobacco plastids poorly correlates with Rubisco large subunit phylogeny. Our findings highlight the need to fully understand the factors governing Rubisco biogenesis if we are to deliver an efficient, low-cost screening tool that can accurately emulate chloroplast expression.
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Affiliation(s)
- Sally Buck
- ARC Centre of Excellence in Translational Photosynthesis, Australian National University, Canberra 2000, Australia
| | - Tim Rhodes
- ARC Centre of Excellence in Translational Photosynthesis, Australian National University, Canberra 2000, Australia
| | - Matteo Gionfriddo
- ARC Centre of Excellence in Translational Photosynthesis, Australian National University, Canberra 2000, Australia
| | - Tanya Skinner
- ARC Centre of Excellence in Translational Photosynthesis, Australian National University, Canberra 2000, Australia
| | - Ding Yuan
- ARC Centre of Excellence in Translational Photosynthesis, Australian National University, Canberra 2000, Australia
| | - Rosemary Birch
- ARC Centre of Excellence in Translational Photosynthesis, Australian National University, Canberra 2000, Australia
| | - Maxim V Kapralov
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
| | - Spencer M Whitney
- ARC Centre of Excellence in Translational Photosynthesis, Australian National University, Canberra 2000, Australia
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8
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Badger MR, Sharwood RE. Rubisco, the imperfect winner: it's all about the base. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:562-580. [PMID: 36412307 DOI: 10.1093/jxb/erac458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 11/20/2022] [Indexed: 06/16/2023]
Abstract
Rubisco catalysis is complex and includes an activation step through the formation of a carbamate at the conserved active site lysine residue and the formation of a highly reactive enediol that is the key to its catalytic reaction. The formation of this enediol is both the basis of its success and its Achilles' heel, creating imperfections to its catalytic efficiency. While Rubisco originally evolved in an atmosphere of high CO2, the earth's multiple oxidation events provided challenges to Rubisco through the fixation of O2 that competes with CO2 at the active site. Numerous catalytic screens across the Rubisco superfamily have identified significant variation in catalytic properties that have been linked to large and small subunit sequences. Despite this, we still have a rudimentary understanding of Rubisco's catalytic mechanism and how the evolution of kinetic properties has occurred. This review identifies the lysine base that functions both as an activator and a proton abstractor to create the enediol as a key to understanding how Rubisco may optimize its kinetic properties. The ways in which Rubisco and its partners have overcome catalytic and activation imperfections and thrived in a world of high O2, low CO2, and variable climatic regimes is remarkable.
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Affiliation(s)
- Murray R Badger
- Research School of Biology, Building 134 Linnaeus Way, Canberra ACT, 2601, Australia
| | - Robert E Sharwood
- Hawkesbury Institute for the Environment, Western Sydney University, Bourke St, Richmond, NSW, 2753, Australia
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9
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Manning T, Birch R, Stevenson T, Nugent G, Whitney S. Bacterial Form II Rubisco can support wild-type growth and productivity in Solanum tuberosum cv. Desiree (potato) under elevated CO 2. PNAS NEXUS 2023; 2:pgac305. [PMID: 36743474 PMCID: PMC9896143 DOI: 10.1093/pnasnexus/pgac305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Accepted: 12/22/2022] [Indexed: 02/05/2023]
Abstract
The last decade has seen significant advances in the development of approaches for improving both the light harvesting and carbon fixation pathways of photosynthesis by nuclear transformation, many involving multigene synthetic biology approaches. As efforts to replicate these accomplishments from tobacco into crops gather momentum, similar diversification is needed in the range of transgenic options available, including capabilities to modify crop photosynthesis by chloroplast transformation. To address this need, here we describe the first transplastomic modification of photosynthesis in a crop by replacing the native Rubisco in potato with the faster, but lower CO2-affinity and poorer CO2/O2 specificity Rubisco from the bacterium Rhodospirillum rubrum. High level production of R. rubrum Rubisco in the potRr genotype (8 to 10 µmol catalytic sites m2) allowed it to attain wild-type levels of productivity, including tuber yield, in air containing 0.5% (v/v) CO2. Under controlled environment growth at 25°C and 350 µmol photons m2 PAR, the productivity and leaf biochemistry of wild-type potato at 0.06%, 0.5%, or 1.5% (v/v) CO2 and potRr at 0.5% or 1.5% (v/v) CO2 were largely indistinguishable. These findings suggest that increasing the scope for enhancing productivity gains in potato by improving photosynthate production will necessitate improvement to its sink-potential, consistent with current evidence productivity gains by eCO2 fertilization for this crop hit a ceiling around 560 to 600 ppm CO2.
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Affiliation(s)
- Tahnee Manning
- School of Science, RMIT University, Bundoora, VIC 3083, Australia
| | - Rosemary Birch
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton, ACT 0200, Australia
| | - Trevor Stevenson
- School of Science, RMIT University, Bundoora, VIC 3083, Australia
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10
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Sharwood RE, Quick WP, Sargent D, Estavillo GM, Silva-Perez V, Furbank RT. Mining for allelic gold: finding genetic variation in photosynthetic traits in crops and wild relatives. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:3085-3108. [PMID: 35274686 DOI: 10.1093/jxb/erac081] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 02/28/2022] [Indexed: 06/14/2023]
Abstract
Improvement of photosynthetic traits in crops to increase yield potential and crop resilience has recently become a major breeding target. Synthetic biology and genetic technologies offer unparalleled opportunities to create new genetics for photosynthetic traits driven by existing fundamental knowledge. However, large 'gene bank' collections of germplasm comprising historical collections of crop species and their relatives offer a wealth of opportunities to find novel allelic variation in the key steps of photosynthesis, to identify new mechanisms and to accelerate genetic progress in crop breeding programmes. Here we explore the available genetic resources in food and fibre crops, strategies to selectively target allelic variation in genes underpinning key photosynthetic processes, and deployment of this variation via gene editing in modern elite material.
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Affiliation(s)
- Robert E Sharwood
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
- ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - W Paul Quick
- ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, Australian National University, Canberra, ACT, Australia
- International Rice Research Institute, Los Baños, Laguna, Philippines
| | - Demi Sargent
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | | | | | - Robert T Furbank
- ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, Australian National University, Canberra, ACT, Australia
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11
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Lin MT, Orr DJ, Worrall D, Parry MAJ, Carmo-Silva E, Hanson MR. A procedure to introduce point mutations into the Rubisco large subunit gene in wild-type plants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 106:876-887. [PMID: 33576096 DOI: 10.1111/tpj.15196] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 01/22/2021] [Accepted: 02/07/2021] [Indexed: 06/12/2023]
Abstract
Photosynthetic inefficiencies limit the productivity and sustainability of crop production and the resilience of agriculture to future societal and environmental challenges. Rubisco is a key target for improvement as it plays a central role in carbon fixation during photosynthesis and is remarkably inefficient. Introduction of mutations to the chloroplast-encoded Rubisco large subunit rbcL is of particular interest for improving the catalytic activity and efficiency of the enzyme. However, manipulation of rbcL is hampered by its location in the plastome, with many species recalcitrant to plastome transformation, and by the plastid's efficient repair system, which can prevent effective maintenance of mutations introduced with homologous recombination. Here we present a system where the introduction of a number of silent mutations into rbcL within the model plant Nicotiana tabacum facilitates simplified screening via additional restriction enzyme sites. This system was used to successfully generate a range of transplastomic lines from wild-type N. tabacum with stable point mutations within rbcL in 40% of the transformants, allowing assessment of the effect of these mutations on Rubisco assembly and activity. With further optimization the approach offers a viable way forward for mutagenic testing of Rubisco function in planta within tobacco and modification of rbcL in other crops where chloroplast transformation is feasible. The transformation strategy could also be applied to introduce point mutations in other chloroplast-encoded genes.
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Affiliation(s)
- Myat T Lin
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14850, USA
| | - Douglas J Orr
- Lancaster Environment Centre, Lancaster University, Library Avenue, Lancaster, LA1 4YQ, UK
| | - Dawn Worrall
- Lancaster Environment Centre, Lancaster University, Library Avenue, Lancaster, LA1 4YQ, UK
| | - Martin A J Parry
- Lancaster Environment Centre, Lancaster University, Library Avenue, Lancaster, LA1 4YQ, UK
| | - Elizabete Carmo-Silva
- Lancaster Environment Centre, Lancaster University, Library Avenue, Lancaster, LA1 4YQ, UK
| | - Maureen R Hanson
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14850, USA
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12
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Whitney SM, Sharwood RE. Rubisco Engineering by Plastid Transformation and Protocols for Assessing Expression. Methods Mol Biol 2021; 2317:195-214. [PMID: 34028770 DOI: 10.1007/978-1-0716-1472-3_10] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The assimilation of CO2 within chloroplasts is catalyzed by the bifunctional enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase, Rubisco. Within higher plants the Rubisco large subunit gene, rbcL, is encoded in the plastid genome, while the Rubisco small subunit gene, RbcS is coded in the nucleus by a multigene family. Rubisco is considered a poor catalyst due to its slow turnover rate and its additional fixation of O2 that can result in wasteful loss of carbon through the energy requiring photorespiratory cycle. Improving the carboxylation efficiency and CO2/O2 selectivity of Rubisco within higher plants has been a long term goal which has been greatly advanced in recent times using plastid transformation techniques. Here we present experimental methodologies for efficiently engineering Rubisco in the plastids of a tobacco master line and analyzing leaf Rubisco content.
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Affiliation(s)
- Spencer M Whitney
- Plant Sciences, Research School of Biology, College of Science, The Australian National University, Acton, ACT, Australia.
| | - Robert E Sharwood
- Plant Sciences, Research School of Biology, College of Science, The Australian National University, Acton, ACT, Australia
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13
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Gunn LH, Martin Avila E, Birch R, Whitney SM. The dependency of red Rubisco on its cognate activase for enhancing plant photosynthesis and growth. Proc Natl Acad Sci U S A 2020; 117:25890-25896. [PMID: 32989135 PMCID: PMC7568259 DOI: 10.1073/pnas.2011641117] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Plant photosynthesis and growth are often limited by the activity of the CO2-fixing enzyme Rubisco. The broad kinetic diversity of Rubisco in nature is accompanied by differences in the composition and compatibility of the ancillary proteins needed for its folding, assembly, and metabolic regulation. Variations in the protein folding needs of catalytically efficient red algae Rubisco prevent their production in plants. Here, we show this impediment does not extend to Rubisco from Rhodobacter sphaeroides (RsRubisco)-a red-type Rubisco able to assemble in plant chloroplasts. In transplastomic tobRsLS lines expressing a codon optimized Rs-rbcLS operon, the messenger RNA (mRNA) abundance was ∼25% of rbcL transcript and RsRubisco ∼40% the Rubisco content in WT tobacco. To mitigate the low activation status of RsRubisco in tobRsLS (∼23% sites active under ambient CO2), the metabolic repair protein RsRca (Rs-activase) was introduced via nuclear transformation. RsRca production in the tobRsLS::X progeny matched endogenous tobacco Rca levels (∼1 µmol protomer·m2) and enhanced RsRubisco activation to 75% under elevated CO2 (1%, vol/vol) growth. Accordingly, the rate of photosynthesis and growth in the tobRsLS::X lines were improved >twofold relative to tobRsLS. Other tobacco lines producing RsRubisco containing alternate diatom and red algae S-subunits were nonviable as CO2-fixation rates (kcatc) were reduced >95% and CO2/O2 specificity impaired 30-50%. We show differences in hybrid and WT RsRubisco biogenesis in tobacco correlated with assembly in Escherichia coli advocating use of this bacterium to preevaluate the kinetic and chloroplast compatibility of engineered RsRubisco, an isoform amenable to directed evolution.
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Affiliation(s)
- Laura H Gunn
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
| | - Elena Martin Avila
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
| | - Rosemary Birch
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
| | - Spencer M Whitney
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
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14
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Evans JR, Lawson T. From green to gold: agricultural revolution for food security. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:2211-2215. [PMID: 32251509 DOI: 10.1093/jxb/eraa110] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Affiliation(s)
- John R Evans
- ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, The Australian National University, Canberra, ACT, Australia
| | - Tracy Lawson
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, UK
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15
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Batista-Silva W, da Fonseca-Pereira P, Martins AO, Zsögön A, Nunes-Nesi A, Araújo WL. Engineering Improved Photosynthesis in the Era of Synthetic Biology. PLANT COMMUNICATIONS 2020; 1:100032. [PMID: 33367233 PMCID: PMC7747996 DOI: 10.1016/j.xplc.2020.100032] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 01/20/2020] [Accepted: 02/08/2020] [Indexed: 05/08/2023]
Abstract
Much attention has been given to the enhancement of photosynthesis as a strategy for the optimization of crop productivity. As traditional plant breeding is most likely reaching a plateau, there is a timely need to accelerate improvements in photosynthetic efficiency by means of novel tools and biotechnological solutions. The emerging field of synthetic biology offers the potential for building completely novel pathways in predictable directions and, thus, addresses the global requirements for higher yields expected to occur in the 21st century. Here, we discuss recent advances and current challenges of engineering improved photosynthesis in the era of synthetic biology toward optimized utilization of solar energy and carbon sources to optimize the production of food, fiber, and fuel.
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Affiliation(s)
- Willian Batista-Silva
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais 36570-900, Brazil
| | - Paula da Fonseca-Pereira
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais 36570-900, Brazil
| | | | - Agustín Zsögön
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais 36570-900, Brazil
| | - Adriano Nunes-Nesi
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais 36570-900, Brazil
| | - Wagner L. Araújo
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais 36570-900, Brazil
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16
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Busch FA. Photorespiration in the context of Rubisco biochemistry, CO 2 diffusion and metabolism. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 101:919-939. [PMID: 31910295 DOI: 10.1111/tpj.14674] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 12/20/2019] [Accepted: 01/03/2020] [Indexed: 05/11/2023]
Abstract
Photorespiratory metabolism is essential for plants to maintain functional photosynthesis in an oxygen-containing environment. Because the oxygenation reaction of Rubisco is followed by the loss of previously fixed carbon, photorespiration is often considered a wasteful process and considerable efforts are aimed at minimizing the negative impact of photorespiration on the plant's carbon uptake. However, the photorespiratory pathway has also many positive aspects, as it is well integrated within other metabolic processes, such as nitrogen assimilation and C1 metabolism, and it is important for maintaining the redox balance of the plant. The overall effect of photorespiratory carbon loss on the net CO2 fixation of the plant is also strongly influenced by the physiology of the leaf related to CO2 diffusion. This review outlines the distinction between Rubisco oxygenation and photorespiratory CO2 release as a basis to evaluate the costs and benefits of photorespiration.
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Affiliation(s)
- Florian A Busch
- Research School of Biology and ARC Centre of Excellence for Translational Photosynthesis, Australian National University, Acton, ACT, 2601, Australia
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17
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Conlan B, Birch R, Kelso C, Holland S, De Souza AP, Long SP, Beck JL, Whitney SM. BSD2 is a Rubisco-specific assembly chaperone, forms intermediary hetero-oligomeric complexes, and is nonlimiting to growth in tobacco. PLANT, CELL & ENVIRONMENT 2019; 42:1287-1301. [PMID: 30375663 DOI: 10.1111/pce.13473] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 09/30/2018] [Accepted: 10/22/2018] [Indexed: 05/28/2023]
Abstract
The folding and assembly of Rubisco large and small subunits into L8 S8 holoenzyme in chloroplasts involves many auxiliary factors, including the chaperone BSD2. Here we identify apparent intermediary Rubisco-BSD2 assembly complexes in the model C3 plant tobacco. We show BSD2 and Rubisco content decrease in tandem with leaf age with approximately half of the BSD2 in young leaves (~70 nmol BSD2 protomer.m2 ) stably integrated in putative intermediary Rubisco complexes that account for <0.2% of the L8 S8 pool. RNAi-silencing BSD2 production in transplastomic tobacco producing bacterial L2 Rubisco had no effect on leaf photosynthesis, cell ultrastructure, or plant growth. Genetic crossing the same RNAi-bsd2 alleles into wild-type tobacco however impaired L8 S8 Rubisco production and plant growth, indicating the only critical function of BSD2 is in Rubisco biogenesis. Agrobacterium mediated transient expression of tobacco, Arabidopsis, or maize BSD2 reinstated Rubisco biogenesis in BSD2-silenced tobacco. Overexpressing BSD2 in tobacco chloroplasts however did not alter Rubisco content, activation status, leaf photosynthesis rate, or plant growth in the field or in the glasshouse at 20°C or 35°C. Our findings indicate BSD2 functions exclusively in Rubisco biogenesis, can efficiently facilitate heterologous plant Rubisco assembly, and is produced in amounts nonlimiting to tobacco growth.
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Affiliation(s)
- Brendon Conlan
- Research School of Biology, The Australian National University, Acton, Australian Capital Territory, Australia
| | - Rosemary Birch
- Research School of Biology, The Australian National University, Acton, Australian Capital Territory, Australia
| | - Celine Kelso
- School of Chemistry, Molecular Horizons, University of Wollongong, New South Wales, Australia
| | - Sophie Holland
- Research School of Biology, The Australian National University, Acton, Australian Capital Territory, Australia
| | - Amanda P De Souza
- Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois, USA
| | - Stephen P Long
- Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois, USA
- Lancaster Environment Centre, Lancaster University, Lancaster, UK
| | - Jennifer L Beck
- School of Chemistry, Molecular Horizons, University of Wollongong, New South Wales, Australia
| | - Spencer M Whitney
- Research School of Biology, The Australian National University, Acton, Australian Capital Territory, Australia
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18
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South PF, Cavanagh AP, Lopez-Calcagno PE, Raines CA, Ort DR. Optimizing photorespiration for improved crop productivity. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2018; 60:1217-1230. [PMID: 30126060 DOI: 10.1111/jipb.12709] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 08/14/2018] [Indexed: 05/24/2023]
Abstract
In C3 plants, photorespiration is an energy-expensive process, including the oxygenation of ribulose-1,5-bisphosphate (RuBP) by ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) and the ensuing multi-organellar photorespiratory pathway required to recycle the toxic byproducts and recapture a portion of the fixed carbon. Photorespiration significantly impacts crop productivity through reducing yields in C3 crops by as much as 50% under severe conditions. Thus, reducing the flux through, or improving the efficiency of photorespiration has the potential of large improvements in C3 crop productivity. Here, we review an array of approaches intended to engineer photorespiration in a range of plant systems with the goal of increasing crop productivity. Approaches include optimizing flux through the native photorespiratory pathway, installing non-native alternative photorespiratory pathways, and lowering or even eliminating Rubisco-catalyzed oxygenation of RuBP to reduce substrate entrance into the photorespiratory cycle. Some proposed designs have been successful at the proof of concept level. A plant systems-engineering approach, based on new opportunities available from synthetic biology to implement in silico designs, holds promise for further progress toward delivering more productive crops to farmer's fields.
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Affiliation(s)
- Paul F South
- Global Change and Photosynthesis Research Unit, United States Department of Agriculture/Agricultural Research Service, Urbana, IL 61801, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, IL 61801, USA
| | - Amanda P Cavanagh
- Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, IL 61801, USA
| | | | - Christine A Raines
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Donald R Ort
- Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, IL 61801, USA
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801, USA
- Department of Plant Biology, University of Illinois, Urbana, IL 61801, USA
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19
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Esland L, Larrea-Alvarez M, Purton S. Selectable Markers and Reporter Genes for Engineering the Chloroplast of Chlamydomonas reinhardtii. BIOLOGY 2018; 7:E46. [PMID: 30309004 PMCID: PMC6315944 DOI: 10.3390/biology7040046] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 10/02/2018] [Accepted: 10/03/2018] [Indexed: 02/07/2023]
Abstract
Chlamydomonas reinhardtii is a model alga of increasing interest as a cell factory for the production of valuable compounds, including therapeutic proteins and bioactive metabolites. Expression of foreign genes in the chloroplast is particularly advantageous as: (i) accumulation of product in this sub-cellular compartment minimises potential toxicity to the rest of the cell; (ii) genes can integrate at specific loci of the chloroplast genome (plastome) by homologous recombination; (iii) the high ploidy of the plastome and the high-level expression of chloroplast genes can be exploited to achieve levels of recombinant protein as high as 5% total cell protein; (iv) the lack of any gene silencing mechanisms in the chloroplast ensures stable expression of transgenes. However, the generation of C. reinhardtii chloroplast transformants requires efficient methods of selection, and ideally methods for subsequent marker removal. Additionally, the use of reporter genes is critical to achieving a comprehensive understanding of gene expression, thereby informing experimental design for recombinant applications. This review discusses currently available selection and reporter systems for chloroplast engineering in C. reinhardtii, as well as those used for chloroplast engineering in higher plants and other microalgae, and looks to the future in terms of possible new markers and reporters that will further advance the C. reinhardtii chloroplast as an expression platform.
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Affiliation(s)
- Lola Esland
- Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
| | - Marco Larrea-Alvarez
- School of Biological Sciences and Engineering, Yachay-Tech University, Hacienda San José, Urcuquí-Imbabura 100650, Ecuador.
| | - Saul Purton
- Institute of Structural & Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK.
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20
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Long BM, Hee WY, Sharwood RE, Rae BD, Kaines S, Lim YL, Nguyen ND, Massey B, Bala S, von Caemmerer S, Badger MR, Price GD. Carboxysome encapsulation of the CO 2-fixing enzyme Rubisco in tobacco chloroplasts. Nat Commun 2018; 9:3570. [PMID: 30177711 PMCID: PMC6120970 DOI: 10.1038/s41467-018-06044-0] [Citation(s) in RCA: 141] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 08/12/2018] [Indexed: 12/30/2022] Open
Abstract
A long-term strategy to enhance global crop photosynthesis and yield involves the introduction of cyanobacterial CO2-concentrating mechanisms (CCMs) into plant chloroplasts. Cyanobacterial CCMs enable relatively rapid CO2 fixation by elevating intracellular inorganic carbon as bicarbonate, then concentrating it as CO2 around the enzyme Rubisco in specialized protein micro-compartments called carboxysomes. To date, chloroplastic expression of carboxysomes has been elusive, requiring coordinated expression of almost a dozen proteins. Here we successfully produce simplified carboxysomes, isometric with those of the source organism Cyanobium, within tobacco chloroplasts. We replace the endogenous Rubisco large subunit gene with cyanobacterial Form-1A Rubisco large and small subunit genes, along with genes for two key α-carboxysome structural proteins. This minimal gene set produces carboxysomes, which encapsulate the introduced Rubisco and enable autotrophic growth at elevated CO2. This result demonstrates the formation of α-carboxysomes from a reduced gene set, informing the step-wise construction of fully functional α-carboxysomes in chloroplasts.
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Affiliation(s)
- Benedict M Long
- Realizing Increased Photosynthetic Efficiency (RIPE), The Australian National University, 134 Linnaeus Way, Acton, ACT, 2601, Australia.
| | - Wei Yih Hee
- Realizing Increased Photosynthetic Efficiency (RIPE), The Australian National University, 134 Linnaeus Way, Acton, ACT, 2601, Australia
| | - Robert E Sharwood
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton, ACT, 2601, Australia
| | - Benjamin D Rae
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton, ACT, 2601, Australia
| | - Sarah Kaines
- Realizing Increased Photosynthetic Efficiency (RIPE), The Australian National University, 134 Linnaeus Way, Acton, ACT, 2601, Australia
| | - Yi-Leen Lim
- Realizing Increased Photosynthetic Efficiency (RIPE), The Australian National University, 134 Linnaeus Way, Acton, ACT, 2601, Australia
| | - Nghiem D Nguyen
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton, ACT, 2601, Australia
| | - Baxter Massey
- Realizing Increased Photosynthetic Efficiency (RIPE), The Australian National University, 134 Linnaeus Way, Acton, ACT, 2601, Australia
| | - Soumi Bala
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton, ACT, 2601, Australia
| | - Susanne von Caemmerer
- Realizing Increased Photosynthetic Efficiency (RIPE), The Australian National University, 134 Linnaeus Way, Acton, ACT, 2601, Australia
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton, ACT, 2601, Australia
| | - Murray R Badger
- Realizing Increased Photosynthetic Efficiency (RIPE), The Australian National University, 134 Linnaeus Way, Acton, ACT, 2601, Australia
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton, ACT, 2601, Australia
| | - G Dean Price
- Realizing Increased Photosynthetic Efficiency (RIPE), The Australian National University, 134 Linnaeus Way, Acton, ACT, 2601, Australia
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton, ACT, 2601, Australia
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21
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Abstract
Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), a ∼530 kDa complex of 8 large (RbcL) and 8 small subunits (RbcS), mediates the fixation of atmospheric CO2 into usable sugars during photosynthesis. Despite its fundamental role, Rubisco is a remarkably inefficient enzyme and thus is produced by plants in huge amounts. It has long been a key target for bioengineering with the goal to increase crop yields. However, such efforts have been hampered by the complex requirement of Rubisco biogenesis for molecular chaperones. Recent studies have identified an array of auxiliary factors needed for the folding and assembly of the Rubisco subunits. The folding of plant RbcL subunits is mediated by the cylindrical chloroplast chaperonin, Cpn60, and its cofactor Cpn20. Folded RbcL requires a number of additional Rubisco specific assembly chaperones, including RbcX, Rubisco accumulation factors 1 (Raf1) and 2 (Raf2), and the Bundle sheath defective-2 (BSD2), to mediate the assembly of the RbcL8 intermediate complex. Incorporation of the RbcS and displacement of the assembly factors generates the active holoenzyme. An Escherichia coli strain expressing the chloroplast chaperonin and auxiliary factors now allows the expression of functional plant Rubisco, paving the way for Rubisco engineering by large scale mutagenesis. Here, we review our current understanding on how these chaperones cooperate to produce one of the most important enzymes in nature.
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Affiliation(s)
- Robert H Wilson
- Department of Cellular Biochemistry , Max Planck Institute of Biochemistry , Am Klopferspitz 18 , 82152 Martinsried , Germany
| | - Manajit Hayer-Hartl
- Department of Cellular Biochemistry , Max Planck Institute of Biochemistry , Am Klopferspitz 18 , 82152 Martinsried , Germany
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22
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Wilson RH, Martin-Avila E, Conlan C, Whitney SM. An improved Escherichia coli screen for Rubisco identifies a protein-protein interface that can enhance CO 2-fixation kinetics. J Biol Chem 2018; 293:18-27. [PMID: 28986448 PMCID: PMC5766918 DOI: 10.1074/jbc.m117.810861] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 09/28/2017] [Indexed: 01/03/2023] Open
Abstract
An overarching goal of photosynthesis research is to identify how components of the process can be improved to benefit crop productivity, global food security, and renewable energy storage. Improving carbon fixation has mostly focused on enhancing the CO2 fixing enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). This grand challenge has mostly proved ineffective because of catalytic mechanism constraints and required chaperone complementarity that hinder Rubisco biogenesis in alternative hosts. Here we refashion Escherichia coli metabolism by expressing a phosphoribulokinase-neomycin phosphotransferase fusion protein to produce a high-fidelity, high-throughput Rubisco-directed evolution (RDE2) screen that negates false-positive selection. Successive evolution rounds using the plant-like Te-Rubisco from the cyanobacterium Thermosynechococcus elongatus BP1 identified two large subunit and six small subunit mutations that improved carboxylation rate, efficiency, and specificity. Structural analysis revealed the amino acids clustered in an unexplored subunit interface of the holoenzyme. To study its effect on plant growth, the Te-Rubisco was transformed into tobacco by chloroplast transformation. As previously seen for Synechocccus PCC6301 Rubisco, the specialized folding and assembly requirements of Te-Rubisco hinder its heterologous expression in leaf chloroplasts. Our findings suggest that the ongoing efforts to improve crop photosynthesis by integrating components of a cyanobacteria CO2-concentrating mechanism will necessitate co-introduction of the ancillary molecular components required for Rubisco biogenesis.
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Affiliation(s)
- Robert H Wilson
- Research School of Biology, Australian National University, Acton, Australian Capital Territory 2601, Australia
| | - Elena Martin-Avila
- Research School of Biology, Australian National University, Acton, Australian Capital Territory 2601, Australia
| | - Carly Conlan
- Research School of Biology, Australian National University, Acton, Australian Capital Territory 2601, Australia
| | - Spencer M Whitney
- Research School of Biology, Australian National University, Acton, Australian Capital Territory 2601, Australia.
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23
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Orr DJ, Pereira AM, da Fonseca Pereira P, Pereira-Lima ÍA, Zsögön A, Araújo WL. Engineering photosynthesis: progress and perspectives. F1000Res 2017; 6:1891. [PMID: 29263782 PMCID: PMC5658708 DOI: 10.12688/f1000research.12181.1] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/27/2017] [Indexed: 12/11/2022] Open
Abstract
Photosynthesis is the basis of primary productivity on the planet. Crop breeding has sustained steady improvements in yield to keep pace with population growth increases. Yet these advances have not resulted from improving the photosynthetic process
per se but rather of altering the way carbon is partitioned within the plant. Mounting evidence suggests that the rate at which crop yields can be boosted by traditional plant breeding approaches is wavering, and they may reach a “yield ceiling” in the foreseeable future. Further increases in yield will likely depend on the targeted manipulation of plant metabolism. Improving photosynthesis poses one such route, with simulations indicating it could have a significant transformative influence on enhancing crop productivity. Here, we summarize recent advances of alternative approaches for the manipulation and enhancement of photosynthesis and their possible application for crop improvement.
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Affiliation(s)
- Douglas J Orr
- Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK
| | - Auderlan M Pereira
- Max-Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil.,Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Paula da Fonseca Pereira
- Max-Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil.,Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Ítalo A Pereira-Lima
- Max-Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil.,Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Agustin Zsögön
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Wagner L Araújo
- Max-Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil.,Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
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24
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Gu J, Zhou Z, Li Z, Chen Y, Wang Z, Zhang H, Yang J. Photosynthetic Properties and Potentials for Improvement of Photosynthesis in Pale Green Leaf Rice under High Light Conditions. FRONTIERS IN PLANT SCIENCE 2017; 8:1082. [PMID: 28676818 PMCID: PMC5476740 DOI: 10.3389/fpls.2017.01082] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Accepted: 06/06/2017] [Indexed: 05/24/2023]
Abstract
Light is the driving force of plant growth, providing the energy required for photosynthesis. However, photosynthesis is also vulnerable to light-induced damage caused by the production of reactive oxygen species (ROS). Plants have therefore evolved various protective mechanisms such as non-photochemical quenching (NPQ) to dissipate excessively absorbed solar energy as heat; however, photoinhibition and NPQ represent a significant loss in solar energy and photosynthetic efficiency, which lowers the yield potential in crops. To estimate light capture and light energy conversion in rice, a genotype with pale green leaves (pgl) and a normally pigmented control (Z802) were subjected to high (HL) and low light (LL). Chlorophyll content, light absorption, chloroplast micrographs, abundance of light-harvesting complex (LHC) binding proteins, electron transport rates (ETR), photochemical and non-photochemical quenching, and generation of ROS were subsequently examined. Pgl had a smaller size of light-harvesting chlorophyll antenna and absorbed less photons than Z802. NPQ and the generation of ROS were also low, while photosystem II efficiency and ETR were high, resulting in improved photosynthesis and less photoinhibition in pgl than Z802. Chlorophyll synthesis and solar conversion efficiency were higher in pgl under HL compared to LL treatment, while Z802 showed an opposite trend due to the high level of photoinhibition under HL. In Z802, excessive absorption of solar energy not only increased the generation of ROS and NPQ, but also exacerbated the effects of increases in temperature, causing midday depression in photosynthesis. These results suggest that photosynthesis and yield potential in rice could be enhanced by truncated light-harvesting chlorophyll antenna size.
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Affiliation(s)
- Junfei Gu
- Jiangsu Key Laboratory of Crop Genetics and Physiology/Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou UniversityYangzhou, China
| | - Zhenxiang Zhou
- Jiangsu Key Laboratory of Crop Genetics and Physiology/Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou UniversityYangzhou, China
| | - Zhikang Li
- Jiangsu Key Laboratory of Crop Genetics and Physiology/Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou UniversityYangzhou, China
| | - Ying Chen
- Jiangsu Key Laboratory of Crop Genetics and Physiology/Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou UniversityYangzhou, China
| | - Zhiqin Wang
- Jiangsu Key Laboratory of Crop Genetics and Physiology/Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou UniversityYangzhou, China
| | - Hao Zhang
- Jiangsu Key Laboratory of Crop Genetics and Physiology/Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou UniversityYangzhou, China
| | - Jianchang Yang
- Jiangsu Key Laboratory of Crop Genetics and Physiology/Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou UniversityYangzhou, China
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Mueller-Cajar O. The Diverse AAA+ Machines that Repair Inhibited Rubisco Active Sites. Front Mol Biosci 2017; 4:31. [PMID: 28580359 PMCID: PMC5437159 DOI: 10.3389/fmolb.2017.00031] [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] [Received: 03/17/2017] [Accepted: 04/29/2017] [Indexed: 11/13/2022] Open
Abstract
Gaseous carbon dioxide enters the biosphere almost exclusively via the active site of the enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco). This highly conserved catalyst has an almost universal propensity to non-productively interact with its substrate ribulose 1,5-bisphosphate, leading to the formation of dead-end inhibited complexes. In diverse autotrophic organisms this tendency has been counteracted by the recruitment of dedicated AAA+ (ATPases associated with various cellular activities) proteins that all use the energy of ATP hydrolysis to remodel inhibited Rubisco active sites leading to release of the inhibitor. Three evolutionarily distinct classes of these Rubisco activases (Rcas) have been discovered so far. Green and red-type Rca are mostly found in photosynthetic eukaryotes of the green and red plastid lineage respectively, whereas CbbQO is associated with chemoautotrophic bacteria. Ongoing mechanistic studies are elucidating how the various motors are utilizing both similar and contrasting strategies to ultimately perform their common function of cracking the inhibited Rubisco active site. The best studied mechanism utilized by red-type Rca appears to involve transient threading of the Rubisco large subunit C-terminal peptide, reminiscent of the action performed by Clp proteases. As well as providing a fascinating example of convergent molecular evolution, Rca proteins can be considered promising crop-improvement targets. Approaches aiming to replace Rubisco in plants with improved enzymes will need to ensure the presence of a compatible Rca protein. The thermolability of the Rca protein found in crop plants provides an opportunity to fortify photosynthesis against high temperature stress. Photosynthesis also appears to be limited by Rca when light conditions are fluctuating. Synthetic biology strategies aiming to enhance the autotrophic CO2 fixation machinery will need to take into consideration the requirement for Rubisco activases as well as their properties.
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Affiliation(s)
- Oliver Mueller-Cajar
- School of Biological Sciences, Nanyang Technological UniversitySingapore, Singapore
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Bracher A, Whitney SM, Hartl FU, Hayer-Hartl M. Biogenesis and Metabolic Maintenance of Rubisco. ANNUAL REVIEW OF PLANT BIOLOGY 2017; 68:29-60. [PMID: 28125284 DOI: 10.1146/annurev-arplant-043015-111633] [Citation(s) in RCA: 133] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) mediates the fixation of atmospheric CO2 in photosynthesis by catalyzing the carboxylation of the 5-carbon sugar ribulose-1,5-bisphosphate (RuBP). Rubisco is a remarkably inefficient enzyme, fixing only 2-10 CO2 molecules per second. Efforts to increase crop yields by bioengineering Rubisco remain unsuccessful, owing in part to the complex cellular machinery required for Rubisco biogenesis and metabolic maintenance. The large subunit of Rubisco requires the chaperonin system for folding, and recent studies have shown that assembly of hexadecameric Rubisco is mediated by specific assembly chaperones. Moreover, Rubisco function can be inhibited by a range of sugar-phosphate ligands, including RuBP. Metabolic repair depends on remodeling of Rubisco by the ATP-dependent Rubisco activase and hydrolysis of inhibitory sugar phosphates by specific phosphatases. Here, we review our present understanding of the structure and function of these auxiliary factors and their utilization in efforts to engineer more catalytically efficient Rubisco enzymes.
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Affiliation(s)
- Andreas Bracher
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany ; , ,
| | - Spencer M Whitney
- Research School of Biology, Australian National University, Acton, Australian Capital Territory 2601, Australia;
| | - F Ulrich Hartl
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany ; , ,
| | - Manajit Hayer-Hartl
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany ; , ,
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Sharwood RE. Engineering chloroplasts to improve Rubisco catalysis: prospects for translating improvements into food and fiber crops. THE NEW PHYTOLOGIST 2017; 213:494-510. [PMID: 27935049 DOI: 10.1111/nph.14351] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 09/10/2016] [Indexed: 05/19/2023]
Abstract
494 I. 495 II. 496 III. 496 IV. 499 V. 499 VI. 501 VII. 501 VIII. 502 IX. 505 X. 506 507 References 507 SUMMARY: The uncertainty of future climate change is placing pressure on cropping systems to continue to provide stable increases in productive yields. To mitigate future climates and the increasing threats against global food security, new solutions to manipulate photosynthesis are required. This review explores the current efforts available to improve carbon assimilation within plant chloroplasts by engineering Rubisco, which catalyzes the rate-limiting step of CO2 fixation. Fixation of CO2 and subsequent cycling of 3-phosphoglycerate through the Calvin cycle provides the necessary carbohydrate building blocks for maintaining plant growth and yield, but has to compete with Rubisco oxygenation, which results in photorespiration that is energetically wasteful for plants. Engineering improvements in Rubisco is a complex challenge and requires an understanding of chloroplast gene regulatory pathways, and the intricate nature of Rubisco catalysis and biogenesis, to transplant more efficient forms of Rubisco into crops. In recent times, major advances in Rubisco engineering have been achieved through improvement of our knowledge of Rubisco synthesis and assembly, and identifying amino acid catalytic switches in the L-subunit responsible for improvements in catalysis. Improving the capacity of CO2 fixation in crops such as rice will require further advances in chloroplast bioengineering and Rubisco biogenesis.
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Affiliation(s)
- Robert E Sharwood
- ARC Center of Excellence for Translational Photosynthesis, Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia
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Sharwood RE, Ghannoum O, Kapralov MV, Gunn LH, Whitney SM. Temperature responses of Rubisco from Paniceae grasses provide opportunities for improving C 3 photosynthesis. NATURE PLANTS 2016; 2:16186. [PMID: 27892943 DOI: 10.1038/nplants.2016.186] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 10/27/2016] [Indexed: 05/03/2023]
Abstract
Enhancing the catalytic properties of the CO2-fixing enzyme Rubisco is a target for improving agricultural crop productivity. Here, we reveal extensive diversity in the kinetic response between 10 and 37 °C by Rubisco from C3 and C4 species within the grass tribe Paniceae. The CO2 fixation rate (kcatc) for Rubisco from the C4 grasses with nicotinamide adenine dinucleotide (NAD) phosphate malic enzyme (NADP-ME) and phosphoenolpyruvate carboxykinase (PCK) photosynthetic pathways was twofold greater than the kcatc of Rubisco from NAD-ME species across all temperatures. The declining response of CO2/O2 specificity with increasing temperature was less pronounced for PCK and NADP-ME Rubisco, which would be advantageous in warmer climates relative to the NAD-ME grasses. Modelled variation in the temperature kinetics of Paniceae C3 Rubisco and PCK Rubisco differentially stimulated C3 photosynthesis relative to tobacco above and below 25 °C under current and elevated CO2. Amino acid substitutions in the large subunit that could account for the catalytic variation among Paniceae Rubisco are identified; however, incompatibilities with Paniceae Rubisco biogenesis in tobacco hindered their mutagenic testing by chloroplast transformation. Circumventing these bioengineering limitations is critical to tailoring the properties of crop Rubisco to suit future climates.
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Affiliation(s)
- Robert E Sharwood
- Research School of Biology, Australian National University, Canberra Australian Capital Territory 2601, Australia
- ARC Centre of Excellence for Translational Photosynthesis, Australian National University, Canberra Australian Capital Territory 2601, Australia
| | - Oula Ghannoum
- ARC Centre of Excellence for Translational Photosynthesis, Australian National University, Canberra Australian Capital Territory 2601, Australia
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales 2753, Australia
| | - Maxim V Kapralov
- School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool L3 3AF, UK
| | - Laura H Gunn
- Research School of Biology, Australian National University, Canberra Australian Capital Territory 2601, Australia
| | - Spencer M Whitney
- Research School of Biology, Australian National University, Canberra Australian Capital Territory 2601, Australia
- ARC Centre of Excellence for Translational Photosynthesis, Australian National University, Canberra Australian Capital Territory 2601, Australia
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Martin Avila E, Gisby MF, Day A. Seamless editing of the chloroplast genome in plants. BMC PLANT BIOLOGY 2016; 16:168. [PMID: 27474038 PMCID: PMC4966725 DOI: 10.1186/s12870-016-0857-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 07/20/2016] [Indexed: 05/13/2023]
Abstract
BACKGROUND Gene editing technologies enable the precise insertion of favourable mutations and performance enhancing trait genes into chromosomes whilst excluding all excess DNA from modified genomes. The technology gives rise to a new class of biotech crops which is likely to have widespread applications in agriculture. Despite progress in the nucleus, the seamless insertions of point mutations and non-selectable foreign genes into the organelle genomes of crops have not been described. The chloroplast genome is an attractive target to improve photosynthesis and crop performance. Current chloroplast genome engineering technologies for introducing point mutations into native chloroplast genes leave DNA scars, such as the target sites for recombination enzymes. Seamless editing methods to modify chloroplast genes need to address reversal of site-directed point mutations by template mediated repair with the vast excess of wild type chloroplast genomes that are present early in the transformation process. RESULTS Using tobacco, we developed an efficient two-step method to edit a chloroplast gene by replacing the wild type sequence with a transient intermediate. This was resolved to the final edited gene by recombination between imperfect direct repeats. Six out of 11 transplastomic plants isolated contained the desired intermediate and at the second step this was resolved to the edited chloroplast gene in five of six plants tested. Maintenance of a single base deletion mutation in an imperfect direct repeat of the native chloroplast rbcL gene showed the limited influence of biased repair back to the wild type sequence. The deletion caused a frameshift, which replaced the five C-terminal amino acids of the Rubisco large subunit with 16 alternative residues resulting in a ~30-fold reduction in its accumulation. We monitored the process in vivo by engineering an overlapping gusA gene downstream of the edited rbcL gene. Translational coupling between the overlapping rbcL and gusA genes resulted in relatively high GUS accumulation (~0.5 % of leaf protein). CONCLUSIONS Editing chloroplast genomes using transient imperfect direct repeats provides an efficient method for introducing point mutations into chloroplast genes. Moreover, we describe the first synthetic operon allowing expression of a downstream overlapping gene by translational coupling in chloroplasts. Overlapping genes provide a new mechanism for co-ordinating the translation of foreign proteins in chloroplasts.
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Affiliation(s)
- Elena Martin Avila
- Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT UK
- Present address: Research School of Biology, The Australian National University, Acton, ACT 2601 Australia
| | - Martin F. Gisby
- Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT UK
| | - Anil Day
- Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT UK
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Friesen PC, Sage RF. Photosynthetic responses to chilling in a chilling-tolerant and chilling-sensitive Miscanthus hybrid. PLANT, CELL & ENVIRONMENT 2016; 39:1420-1431. [PMID: 26714623 DOI: 10.1111/pce.12699] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 11/13/2015] [Accepted: 12/16/2015] [Indexed: 06/05/2023]
Abstract
Miscanthus is a C4 perennial grass being developed for bioenergy production in temperate regions where chilling events are common. To evaluate chilling effects on Miscanthus, we assessed the processes controlling net CO2 assimilation rate (A) in Miscanthus x giganteus (M161) and a chilling-sensitive Miscanthus hybrid (M115) before and after a chilling treatment of 12/5 °C. The temperature response of A and maximum Rubisco activity in vitro were identical below 20 °C in chilled and unchilled M161, demonstrating Rubisco capacity limits or co-limits A at cooler temperatures. By contrast, A in M115 decreased at all measurement temperatures after growth at 12/5 °C. Rubisco activity in vitro declined in proportion to the reduction in A in chilled M115 plants, indicating Rubisco capacity is responsible in part for the decline in A. Pyruvate orthophosphate dikinase activities were also reduced by the chilling treatment when assayed at 28 °C, indicating this enzyme may also contribute to the reduction in A in M115. The maximum extractable activities of PEPCase and NADP-ME remained largely unchanged after chilling. The carboxylation efficiency of the C4 cycle was depressed in both genotypes to a similar extent after chilling. ΦP :ΦCO2 remained unchanged in both genotypes indicating the C3 and C4 cycles decline equivalently upon chilling.
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Affiliation(s)
- P C Friesen
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, M5S 3B2, Canada
| | - R F Sage
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, M5S 3B2, Canada
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31
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Sharwood RE, Ghannoum O, Whitney SM. Prospects for improving CO2 fixation in C3-crops through understanding C4-Rubisco biogenesis and catalytic diversity. CURRENT OPINION IN PLANT BIOLOGY 2016; 31:135-42. [PMID: 27131319 DOI: 10.1016/j.pbi.2016.04.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 03/30/2016] [Accepted: 04/04/2016] [Indexed: 05/09/2023]
Abstract
By operating a CO2 concentrating mechanism, C4-photosynthesis offers highly successful solutions to remedy the inefficiency of the CO2-fixing enzyme Rubisco. C4-plant Rubisco has characteristically evolved faster carboxylation rates with low CO2 affinity. Owing to high CO2 concentrations in bundle sheath chloroplasts, faster Rubisco enhances resource use efficiency in C4 plants by reducing the energy and carbon costs associated with photorespiration and lowering the nitrogen investment in Rubisco. Here, we show that C4-Rubisco from some NADP-ME species, such as maize, are also of potential benefit to C3-photosynthesis under current and future atmospheric CO2 pressures. Realizing this bioengineering endeavour necessitates improved understanding of the biogenesis requirements and catalytic variability of C4-Rubisco, as well as the development of transformation capabilities to engineer Rubisco in a wider variety of food and fibre crops.
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Affiliation(s)
- Robert E Sharwood
- ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, Australian National University, 134 Linnaeus Way, Acton, ACT 2601, Australia.
| | - Oula Ghannoum
- ARC Centre of Excellence for Translational Photosynthesis, Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia
| | - Spencer M Whitney
- ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, Australian National University, 134 Linnaeus Way, Acton, ACT 2601, Australia
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32
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Long BM, Rae BD, Rolland V, Förster B, Price GD. Cyanobacterial CO2-concentrating mechanism components: function and prospects for plant metabolic engineering. CURRENT OPINION IN PLANT BIOLOGY 2016; 31:1-8. [PMID: 26999306 DOI: 10.1016/j.pbi.2016.03.002] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 02/25/2016] [Accepted: 03/02/2016] [Indexed: 05/21/2023]
Abstract
Global population growth is projected to outpace plant-breeding improvements in major crop yields within decades. To ensure future food security, multiple creative efforts seek to overcome limitations to crop yield. Perhaps the greatest limitation to increased crop yield is photosynthetic inefficiency, particularly in C3 crop plants. Recently, great strides have been made toward crop improvement by researchers seeking to introduce the cyanobacterial CO2-concentrating mechanism (CCM) into plant chloroplasts. This strategy recognises the C3 chloroplast as lacking a CCM, and being a primordial cyanobacterium at its essence. Hence the collection of solute transporters, enzymes, and physical structures that make cyanobacterial CO2-fixation so efficient are viewed as a natural source of genetic material for C3 chloroplast improvement. Also we highlight recent outstanding research aimed toward the goal of introducing a cyanobacterial CCM into C3 chloroplasts and consider future research directions.
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Affiliation(s)
- Benedict M Long
- ARC Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, ACT 2601, Australia.
| | - Benjamin D Rae
- ARC Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - Vivien Rolland
- ARC Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - Britta Förster
- ARC Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - G Dean Price
- ARC Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
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33
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Wilson RH, Alonso H, Whitney SM. Evolving Methanococcoides burtonii archaeal Rubisco for improved photosynthesis and plant growth. Sci Rep 2016; 6:22284. [PMID: 26926260 PMCID: PMC4772096 DOI: 10.1038/srep22284] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 02/10/2016] [Indexed: 11/28/2022] Open
Abstract
In photosynthesis Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) catalyses the often rate limiting CO2-fixation step in the Calvin cycle. This makes Rubisco both the gatekeeper for carbon entry into the biosphere and a target for functional improvement to enhance photosynthesis and plant growth. Encumbering the catalytic performance of Rubisco is its highly conserved, complex catalytic chemistry. Accordingly, traditional efforts to enhance Rubisco catalysis using protracted "trial and error" protein engineering approaches have met with limited success. Here we demonstrate the versatility of high throughput directed (laboratory) protein evolution for improving the carboxylation properties of a non-photosynthetic Rubisco from the archaea Methanococcoides burtonii. Using chloroplast transformation in the model plant Nicotiana tabacum (tobacco) we confirm the improved forms of M. burtonii Rubisco increased photosynthesis and growth relative to tobacco controls producing wild-type M. burtonii Rubisco. Our findings indicate continued directed evolution of archaeal Rubisco offers new potential for enhancing leaf photosynthesis and plant growth.
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Affiliation(s)
- Robert H. Wilson
- Research School of Biology, The Australian National University, Acton, Australian Capital Territory 2601, Australia
| | - Hernan Alonso
- Research School of Biology, The Australian National University, Acton, Australian Capital Territory 2601, Australia
| | - Spencer M. Whitney
- Research School of Biology, The Australian National University, Acton, Australian Capital Territory 2601, Australia
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Carmo-Silva E, Scales JC, Madgwick PJ, Parry MAJ. Optimizing Rubisco and its regulation for greater resource use efficiency. PLANT, CELL & ENVIRONMENT 2015; 38:1817-32. [PMID: 25123951 DOI: 10.1111/pce.12425] [Citation(s) in RCA: 187] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 08/01/2014] [Accepted: 08/03/2014] [Indexed: 05/19/2023]
Abstract
Rubisco catalyses the carboxylation of ribulose-1,5-bisphosphate (RuBP), enabling net CO2 assimilation in photosynthesis. The properties and regulation of Rubisco are not optimal for biomass production in current and projected future environments. Rubisco is relatively inefficient, and large amounts of the enzyme are needed to support photosynthesis, requiring large investments in nitrogen. The competing oxygenation of RuBP by Rubisco decreases photosynthetic efficiency. Additionally, Rubisco is inhibited by some sugar phosphates and depends upon interaction with Rubisco activase (Rca) to be reactivated. Rca activity is modulated by the chloroplast redox status and ADP/ATP ratios, thereby mediating Rubisco activation and photosynthetic induction in response to irradiance. The extreme thermal sensitivity of Rca compromises net CO2 assimilation at moderately high temperatures. Given its central role in carbon assimilation, the improvement of Rubisco function and regulation is tightly linked with irradiance, nitrogen and water use efficiencies. Although past attempts have had limited success, novel technologies and an expanding knowledge base make the challenge of improving Rubisco activity in crops an achievable goal. Strategies to optimize Rubisco and its regulation are addressed in relation to their potential to improve crop resource use efficiency and climate resilience of photosynthesis.
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Affiliation(s)
| | - Joanna C Scales
- Plant Biology and Crop Science, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK
| | - Pippa J Madgwick
- Plant Biology and Crop Science, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK
| | - Martin A J Parry
- Plant Biology and Crop Science, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK
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35
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Whitney SM, Birch R, Kelso C, Beck JL, Kapralov MV. Improving recombinant Rubisco biogenesis, plant photosynthesis and growth by coexpressing its ancillary RAF1 chaperone. Proc Natl Acad Sci U S A 2015; 112:3564-9. [PMID: 25733857 PMCID: PMC4371954 DOI: 10.1073/pnas.1420536112] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Enabling improvements to crop yield and resource use by enhancing the catalysis of the photosynthetic CO2-fixing enzyme Rubisco has been a longstanding challenge. Efforts toward realization of this goal have been greatly assisted by advances in understanding the complexities of Rubisco's biogenesis in plastids and the development of tailored chloroplast transformation tools. Here we generate transplastomic tobacco genotypes expressing Arabidopsis Rubisco large subunits (AtL), both on their own (producing tob(AtL) plants) and with a cognate Rubisco accumulation factor 1 (AtRAF1) chaperone (producing tob(AtL-R1) plants) that has undergone parallel functional coevolution with AtL. We show AtRAF1 assembles as a dimer and is produced in tob(AtL-R1) and Arabidopsis leaves at 10-15 nmol AtRAF1 monomers per square meter. Consistent with a postchaperonin large (L)-subunit assembly role, the AtRAF1 facilitated two to threefold improvements in the amount and biogenesis rate of hybrid L8(A)S8(t) Rubisco [comprising AtL and tobacco small (S) subunits] in tob(AtL-R1) leaves compared with tob(AtL), despite >threefold lower steady-state Rubisco mRNA levels in tob(AtL-R1). Accompanying twofold increases in photosynthetic CO2-assimilation rate and plant growth were measured for tob(AtL-R1) lines. These findings highlight the importance of ancillary protein complementarity during Rubisco biogenesis in plastids, the possible constraints this has imposed on Rubisco adaptive evolution, and the likely need for such interaction specificity to be considered when optimizing recombinant Rubisco bioengineering in plants.
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Affiliation(s)
- Spencer M Whitney
- Research School of Biology, Australian National University, Acton, ACT 2601, Australia; and
| | - Rosemary Birch
- Research School of Biology, Australian National University, Acton, ACT 2601, Australia; and
| | - Celine Kelso
- School of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Jennifer L Beck
- School of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Maxim V Kapralov
- Research School of Biology, Australian National University, Acton, ACT 2601, Australia; and
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36
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Galmés J, Kapralov MV, Copolovici LO, Hermida-Carrera C, Niinemets Ü. Temperature responses of the Rubisco maximum carboxylase activity across domains of life: phylogenetic signals, trade-offs, and importance for carbon gain. PHOTOSYNTHESIS RESEARCH 2015; 123:183-201. [PMID: 25515770 DOI: 10.1007/s11120-014-0067-8] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 12/09/2014] [Indexed: 05/09/2023]
Abstract
Temperature response of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) catalytic properties directly determines the CO2 assimilation capacity of photosynthetic organisms as well as their survival in environments with different thermal conditions. Despite unquestionable importance of Rubisco, the comprehensive analysis summarizing temperature responses of Rubisco traits across lineages of carbon-fixing organisms is lacking. Here, we present a review of the temperature responses of Rubisco carboxylase specific activity (c(cat)(c)) within and across domains of life. In particular, we consider the variability of temperature responses, and their ecological, physiological, and evolutionary controls. We observed over two-fold differences in the energy of activation (ΔH(a)) among different groups of photosynthetic organisms, and found significant differences between C3 plants from cool habitats, C3 plants from warm habitats and C4 plants. According to phylogenetically independent contrast analysis, ΔH(a) was not related to the species optimum growth temperature (T growth), but was positively correlated with Rubisco specificity factor (S(c/o)) across all organisms. However, when only land plants were analyzed, ΔH(a) was positively correlated with both T(growth) and S(c/o), indicating different trends for these traits in plants versus unicellular aquatic organisms, such as algae and bacteria. The optimum temperature (T(opt)) for k(cat)(c) correlated with S(c/o) for land plants and for all organisms pooled, but the effect of T growth on T(opt) was driven by species phylogeny. The overall phylogenetic signal was significant for all analyzed parameters, stressing the importance of considering the evolutionary framework and accounting for shared ancestry when deciphering relationships between Rubisco kinetic parameters. We argue that these findings have important implications for improving global photosynthesis models.
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Affiliation(s)
- J Galmés
- Research Group in Plant Biology Under Mediterranean Conditions, Department of Biology, Universitat de les Illes Balears, Carretera de Valldemossa km 7.5, 07122, Palma, Illes Balears, Spain,
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37
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Galmés J, Conesa MÀ, Díaz-Espejo A, Mir A, Perdomo JA, Niinemets U, Flexas J. Rubisco catalytic properties optimized for present and future climatic conditions. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2014; 226:61-70. [PMID: 25113451 DOI: 10.1016/j.plantsci.2014.01.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 12/06/2013] [Accepted: 01/20/2014] [Indexed: 05/19/2023]
Abstract
Because of its catalytic inefficiencies, Rubisco is the most obvious target for improvement to enhance the photosynthetic capacity of plants. Two hypotheses are tested in the present work: (1) existing Rubiscos have optimal kinetic properties to maximize photosynthetic carbon assimilation in existing higher plants; (2) current knowledge allows proposal of changes to kinetic properties to make Rubiscos more suited to changed conditions in chloroplasts that are likely to occur with climate change. The catalytic mechanism of Rubisco results in higher catalytic rates of carboxylation being associated with decreased affinity for CO2, so that selection for different environments involves a trade-off between these two properties. The simulations performed in this study confirm that the optimality of Rubisco kinetics depends on the species and the environmental conditions. In particular, environmental drivers affecting the CO2 availability for carboxylation (Cc) or directly shifting the photosynthetic limitations between Rubisco and RuBP regeneration determine to what extend Rubisco kinetics are optimally suited to maximize CO2 assimilation rate. In general, modeled values for optimal kinetic reflect the predominant environmental conditions currently encountered by the species in the field. Under future climatic conditions, photosynthetic CO2 assimilation will be limited by RuBP-regeneration, especially in the absence of water stress, the largest rise in [CO2] and the lowest increases in temperature. Under these conditions, the model predicts that optimal Rubisco should have high Sc/o and low kcat(c).
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Affiliation(s)
- J Galmés
- Research Group in Plant Biology under Mediterranean Conditions, Department of Biology, Universitat de les Illes Balears, Carretera de Valldemossa km 7.5, 07122 Palma, Illes Balears, Spain.
| | - M À Conesa
- Research Group in Plant Biology under Mediterranean Conditions, Department of Biology, Universitat de les Illes Balears, Carretera de Valldemossa km 7.5, 07122 Palma, Illes Balears, Spain
| | - A Díaz-Espejo
- Irrigation and Crop Ecophysiology Group, Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS, CSIC), Avenida Reina Mercedes 10, 41012 Sevilla, Spain
| | - A Mir
- Computational Biology and Bioinformatics Research Group, Department of Mathematics and Computer Science, Universitat de les Illes Balears, Carretera de Valldemossa km 7.5, 07122 Palma, Illes Balears, Spain
| | - J A Perdomo
- Research Group in Plant Biology under Mediterranean Conditions, Department of Biology, Universitat de les Illes Balears, Carretera de Valldemossa km 7.5, 07122 Palma, Illes Balears, Spain
| | - U Niinemets
- Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 1, Tartu 51014, Estonia
| | - J Flexas
- Research Group in Plant Biology under Mediterranean Conditions, Department of Biology, Universitat de les Illes Balears, Carretera de Valldemossa km 7.5, 07122 Palma, Illes Balears, Spain
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Sharwood RE, Whitney SM. Correlating Rubisco catalytic and sequence diversity within C3 plants with changes in atmospheric CO2 concentrations. PLANT, CELL & ENVIRONMENT 2014; 37:1981-1984. [PMID: 24934767 DOI: 10.1111/pce.12386] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 06/10/2014] [Indexed: 06/03/2023]
Affiliation(s)
- Robert E Sharwood
- Research School of Biology, Australian National University, Canberra, ACT, 0200, Australia
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Pengelly JJL, Förster B, von Caemmerer S, Badger MR, Price GD, Whitney SM. Transplastomic integration of a cyanobacterial bicarbonate transporter into tobacco chloroplasts. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:3071-80. [PMID: 24965541 PMCID: PMC4071830 DOI: 10.1093/jxb/eru156] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Improving global yields of agricultural crops is a complex challenge with evidence indicating benefits in productivity are achieved by enhancing photosynthetic carbon assimilation. Towards improving rates of CO2 capture within leaf chloroplasts, this study shows the versatility of plastome transformation for expressing the Synechococcus PCC7002 BicA bicarbonate transporter within tobacco plastids. Fractionation of chloroplast membranes from transplastomic tob(BicA) lines showed that ~75% of the BicA localized to the thylakoid membranes and ~25% to the chloroplast envelope. BicA levels were highest in young emerging tob(BicA) leaves (0.12 μmol m(-2), ≈7mg m(-2)) accounting for ~0.1% (w/w) of the leaf protein. In these leaves, the molar amount of BicA was 16-fold lower than the abundant thylakoid photosystem II D1 protein (~1.9 μmol m(-2)) which was comparable to the 9:1 molar ratio of D1:BicA measured in air-grown Synechococcus PCC7002 cells. The BicA produced had no discernible effect on chloroplast ultrastructure, photosynthetic CO2-assimilation rates, carbon isotope discrimination, or growth of the tob(BicA) plants, implying that the bicarbonate transporter had little or no activity. These findings demonstrate the utility of plastome transformation for targeting bicarbonate transporter proteins into the chloroplast membranes without impeding growth or plastid ultrastructure. This study establishes the span of experimental measurements required to verify heterologous bicarbonate transporter function and location in chloroplasts and underscores the need for more detailed understanding of BicA structure and function to identify solutions for enabling its activation and operation in leaf chloroplasts.
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Affiliation(s)
- J J L Pengelly
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
| | - B Förster
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
| | - S von Caemmerer
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
| | - M R Badger
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
| | - G D Price
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
| | - S M Whitney
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
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Whitney SM, Sharwood RE. Plastid transformation for Rubisco engineering and protocols for assessing expression. Methods Mol Biol 2014; 1132:245-62. [PMID: 24599858 DOI: 10.1007/978-1-62703-995-6_15] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The assimilation of CO2 within chloroplasts is catalyzed by the bi-functional enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase, Rubisco. Within higher plants the Rubisco large subunit gene, rbcL, is encoded in the plastid genome, while the Rubisco small subunit gene, RbcS is coded in the nucleus by a multi-gene family. Rubisco is considered a poor catalyst due to its slow turnover rate and its additional fixation of O2 that can result in wasteful loss of carbon through the energy requiring photorespiratory cycle. Improving the carboxylation efficiency and CO2/O2 selectivity of Rubisco within higher plants has been a long-term goal which has been greatly advanced in recent times using plastid transformation techniques. Here we present experimental methodologies for efficiently engineering Rubisco in the plastids of a tobacco master-line and analyzing leaf Rubisco content.
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Affiliation(s)
- Spencer M Whitney
- College of Medicine, Biology and Ecology, Research School of Biology, The Australian National University, Canberra, ACT, Australia
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41
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Gu J, Yin X, Stomph TJ, Struik PC. Can exploiting natural genetic variation in leaf photosynthesis contribute to increasing rice productivity? A simulation analysis. PLANT, CELL & ENVIRONMENT 2014; 37:22-34. [PMID: 23937619 DOI: 10.1111/pce.12173] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Revised: 07/22/2013] [Accepted: 07/24/2013] [Indexed: 05/05/2023]
Abstract
Rice productivity can be limited by available photosynthetic assimilates from leaves. However, the lack of significant correlation between crop yield and leaf photosynthetic rate (A) is noted frequently. Engineering for improved leaf photosynthesis has been argued to yield little increase in crop productivity because of complicated constraints and feedback mechanisms when moving up from leaf to crop level. Here we examined the extent to which natural genetic variation in A can contribute to increasing rice productivity. Using the mechanistic model GECROS, we analysed the impact of genetic variation in A on crop biomass production, based on the quantitative trait loci for various photosynthetic components within a rice introgression line population. We showed that genetic variation in A of 25% can be scaled up equally to crop level, resulting in an increase in biomass of 22-29% across different locations and years. This was probably because the genetic variation in A resulted not only from Rubisco (ribulose 1,5-bisphosphate carboxylase/oxygenase)-limited photosynthesis but also from electron transport-limited photosynthesis; as a result, photosynthetic rates could be improved for both light-saturated and light-limited leaves in the canopy. Rice productivity could be significantly improved by mining the natural variation in existing germ-plasm, especially the variation in parameters determining light-limited photosynthesis.
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Affiliation(s)
- Junfei Gu
- Department of Plant Sciences, Centre for Crop Systems Analysis, Wageningen University, PO Box 430, 6700 AK, Wageningen, The Netherlands
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Moroney JV, Jungnick N, Dimario RJ, Longstreth DJ. Photorespiration and carbon concentrating mechanisms: two adaptations to high O2, low CO2 conditions. PHOTOSYNTHESIS RESEARCH 2013; 117:121-31. [PMID: 23771683 DOI: 10.1007/s11120-013-9865-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2013] [Accepted: 05/27/2013] [Indexed: 05/19/2023]
Abstract
This review presents an overview of the two ways that cyanobacteria, algae, and plants have adapted to high O2 and low CO2 concentrations in the environment. First, the process of photorespiration enables photosynthetic organisms to recycle phosphoglycolate formed by the oxygenase reaction catalyzed by ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Second, there are a number of carbon concentrating mechanisms that increase the CO2 concentration around Rubisco which increases the carboxylase reaction enhancing CO2 fixation. This review also presents possibilities for the beneficial modification of these processes with the goal of improving future crop yields.
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Affiliation(s)
- James V Moroney
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA,
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Parry MAJ, Andralojc PJ, Scales JC, Salvucci ME, Carmo-Silva AE, Alonso H, Whitney SM. Rubisco activity and regulation as targets for crop improvement. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:717-30. [PMID: 23162118 DOI: 10.1093/jxb/ers336] [Citation(s) in RCA: 232] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Rubisco (ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase) enables net carbon fixation through the carboxylation of RuBP. However, some characteristics of Rubisco make it surprisingly inefficient and compromise photosynthetic productivity. For example, Rubisco catalyses a wasteful reaction with oxygen that leads to the release of previously fixed CO(2) and NH(3) and the consumption of energy during photorespiration. Furthermore, Rubisco is slow and large amounts are needed to support adequate photosynthetic rates. Consequently, Rubisco has been studied intensively as a prime target for manipulations to 'supercharge' photosynthesis and improve both productivity and resource use efficiency. The catalytic properties of Rubiscos from diverse sources vary considerably, suggesting that changes in turnover rate, affinity, or specificity for CO(2) can be introduced to improve Rubisco performance in specific crops and environments. While attempts to manipulate plant Rubisco by nuclear transformation have had limited success, modifying its catalysis by targeted changes to its catalytic large subunit via chloroplast transformation have been much more successful. However, this technique is still in need of development for most major food crops including maize, wheat, and rice. Other bioengineering approaches for improving Rubisco performance include improving the activity of its ancillary protein, Rubisco activase, in addition to modulating the synthesis and degradation of Rubisco's inhibitory sugar phosphate ligands. As the rate-limiting step in carbon assimilation, even modest improvements in the overall performance of Rubisco pose a viable pathway for obtaining significant gains in plant yield, particularly under stressful environmental conditions.
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Affiliation(s)
- Martin A J Parry
- Plant Biology and Crop Science, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK.
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Hanson MR, Gray BN, Ahner BA. Chloroplast transformation for engineering of photosynthesis. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:731-42. [PMID: 23162121 DOI: 10.1093/jxb/ers325] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Many efforts are underway to engineer improvements in photosynthesis to meet the challenges of increasing demands for food and fuel in rapidly changing environmental conditions. Various transgenes have been introduced into either the nuclear or plastid genomes in attempts to increase photosynthetic efficiency. We examine the current knowledge of the critical features that affect levels of expression of plastid transgenes and protein accumulation in transplastomic plants, such as promoters, 5' and 3' untranslated regions, RNA-processing sites, translation signals and amino acid sequences that affect protein turnover. We review the prior attempts to manipulate the properties of ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco) through plastid transformation. We illustrate how plastid operons could be created for expression of the multiple genes needed to introduce new pathways or enzymes to enhance photosynthetic rates or reduce photorespiration. We describe here the past accomplishments and future prospects for manipulating plant enzymes and pathways to enhance carbon assimilation through plastid transformation.
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Affiliation(s)
- Maureen R Hanson
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA.
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45
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Venkatesh J, Park SW. Plastid genetic engineering in Solanaceae. PROTOPLASMA 2012; 249:981-99. [PMID: 22395455 PMCID: PMC3459085 DOI: 10.1007/s00709-012-0391-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Accepted: 02/21/2012] [Indexed: 05/23/2023]
Abstract
Plastid genetic engineering has come of age, becoming today an attractive alternative approach for the expression of foreign genes, as it offers several advantages over nuclear transformants. Significant progress has been made in plastid genetic engineering in tobacco and other Solanaceae plants, through the use of improved regeneration procedures and transformation vectors with efficient promoters and untranslated regions. Many genes encoding for industrially important proteins and vaccines, as well as genes conferring important agronomic traits, have been stably integrated and expressed in the plastid genome. Despite these advances, it remains a challenge to achieve marked levels of plastid transgene expression in non-green tissues. In this review, we summarize the basic requirements of plastid genetic engineering and discuss the current status, limitations, and the potential of plastid transformation for expanding future studies relating to Solanaceae plants.
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Affiliation(s)
- Jelli Venkatesh
- Department of Molecular Biotechnology, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul, 143-701 Republic of Korea
| | - Se Won Park
- Department of Molecular Biotechnology, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul, 143-701 Republic of Korea
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Rosenthal DM, Locke AM, Khozaei M, Raines CA, Long SP, Ort DR. Over-expressing the C(3) photosynthesis cycle enzyme Sedoheptulose-1-7 Bisphosphatase improves photosynthetic carbon gain and yield under fully open air CO(2) fumigation (FACE). BMC PLANT BIOLOGY 2011; 11:123. [PMID: 21884586 PMCID: PMC3185276 DOI: 10.1186/1471-2229-11-123] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Accepted: 08/31/2011] [Indexed: 05/18/2023]
Abstract
BACKGROUND Biochemical models predict that photosynthesis in C(3) plants is most frequently limited by the slower of two processes, the maximum capacity of the enzyme Rubisco to carboxylate RuBP (V(c,max)), or the regeneration of RuBP via electron transport (J). At current atmospheric [CO(2)] levels Rubisco is not saturated; consequently, elevating [CO(2)] increases the velocity of carboxylation and inhibits the competing oxygenation reaction which is also catalyzed by Rubisco. In the future, leaf photosynthesis (A) should be increasingly limited by RuBP regeneration, as [CO(2)] is predicted to exceed 550 ppm by 2050. The C(3) cycle enzyme sedoheptulose-1,7 bisphosphatase (SBPase, EC 3.1.3.17) has been shown to exert strong metabolic control over RuBP regeneration at light saturation. RESULTS We tested the hypothesis that tobacco transformed to overexpressing SBPase will exhibit greater stimulation of A than wild type (WT) tobacco when grown under field conditions at elevated [CO(2)] (585 ppm) under fully open air fumigation. Growth under elevated [CO(2)] stimulated instantaneous A and the diurnal photosynthetic integral (A') more in transformants than WT. There was evidence of photosynthetic acclimation to elevated [CO(2)] via downregulation of V(c,max) in both WT and transformants. Nevertheless, greater carbon assimilation and electron transport rates (J and J(max)) for transformants led to greater yield increases than WT at elevated [CO(2)] compared to ambient grown plants. CONCLUSION These results provide proof of concept that increasing content and activity of a single photosynthesis enzyme can enhance carbon assimilation and yield of C(3) crops grown at [CO(2)] expected by the middle of the 21st century.
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Affiliation(s)
- David M Rosenthal
- Global Change and Photosynthesis Research Unit, United States Department of Agriculture, Institute for Genomic Biology, 1206 West Gregory Drive, Urbana, IL, 61801, USA
| | - Anna M Locke
- Department of Plant Biology, Institute for Genomic Biology, 1206 West Gregory Drive, University of Illinois, Urbana, IL, 61801, USA
| | - Mahdi Khozaei
- Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK, CO43SQ. Current address: Department of Biology, University of Isfahan, Iran
| | - Christine A Raines
- Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO43SQ, UK
| | - Stephen P Long
- Department of Plant Biology and Crop Sciences, Institute for Genomic Biology, 1206 West Gregory Drive, University of Illinois, Urbana, IL, 61801, USA
| | - Donald R Ort
- Global Change and Photosynthesis Research Unit, United States Department of Agriculture, Institute for Genomic Biology, 1206 West Gregory Drive, Urbana, IL, 61801, USA; Department of Plant Biology and Crop Sciences, University of Illinois, Urbana, IL, 61801, USA
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49
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Whitney SM, Sharwood RE, Orr D, White SJ, Alonso H, Galmés J. Isoleucine 309 acts as a C4 catalytic switch that increases ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) carboxylation rate in Flaveria. Proc Natl Acad Sci U S A 2011; 108:14688-93. [PMID: 21849620 PMCID: PMC3167554 DOI: 10.1073/pnas.1109503108] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Improving global yields of important agricultural crops is a complex challenge. Enhancing yield and resource use by engineering improvements to photosynthetic carbon assimilation is one potential solution. During the last 40 million years C(4) photosynthesis has evolved multiple times, enabling plants to evade the catalytic inadequacies of the CO(2)-fixing enzyme, ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco). Compared with their C(3) ancestors, C(4) plants combine a faster rubisco with a biochemical CO(2)-concentrating mechanism, enabling more efficient use of water and nitrogen and enhanced yield. Here we show the versatility of plastome manipulation in tobacco for identifying sequences in C(4)-rubisco that can be transplanted into C(3)-rubisco to improve carboxylation rate (V(C)). Using transplastomic tobacco lines expressing native and mutated rubisco large subunits (L-subunits) from Flaveria pringlei (C(3)), Flaveria floridana (C(3)-C(4)), and Flaveria bidentis (C(4)), we reveal that Met-309-Ile substitutions in the L-subunit act as a catalytic switch between C(4) ((309)Ile; faster V(C), lower CO(2) affinity) and C(3) ((309)Met; slower V(C), higher CO(2) affinity) catalysis. Application of this transplastomic system permits further identification of other structural solutions selected by nature that can increase rubisco V(C) in C(3) crops. Coengineering a catalytically faster C(3) rubisco and a CO(2)-concentrating mechanism within C(3) crop species could enhance their efficiency in resource use and yield.
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Affiliation(s)
- Spencer M Whitney
- Research School of Biology, Australian National University, Canberra ACT 2601, Australia.
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Suárez R, Miró M, Cerdà V, Perdomo JA, Galmés J. Automated flow-based anion-exchange method for high-throughput isolation and real-time monitoring of RuBisCO in plant extracts. Talanta 2011; 84:1259-66. [PMID: 21641435 DOI: 10.1016/j.talanta.2011.01.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 01/01/2011] [Accepted: 01/12/2011] [Indexed: 11/17/2022]
Abstract
In this work, a miniaturized, completely enclosed multisyringe-flow system is proposed for high-throughput purification of RuBisCO from Triticum aestivum extracts. The automated method capitalizes on the uptake of the target protein at 4°C onto Q-Sepharose Fast Flow strong anion-exchanger packed in a cylindrical microcolumn (105 × 4 mm) followed by a stepwise ionic-strength gradient elution (0-0.8 mol/L NaCl) to eliminate concomitant extract components and retrieve highly purified RuBisCO. The manifold is furnished downstream with a flow-through diode-array UV/vis spectrophotometer for real-time monitoring of the column effluent at the protein-specific wavelength of 280 nm to detect the elution of RuBisCO. Quantitation of RuBisCO and total soluble proteins in the eluate fractions were undertaken using polyacrylamide gel electrophoresis (PAGE) and the spectrophotometric Bradford assay, respectively. A comprehensive investigation of the effect of distinct concentration gradients on the isolation of RuBisCO and experimental conditions (namely, type of resin, column dimensions and mobile-phase flow rate) upon column capacity and analyte breakthrough was effected. The assembled set-up was aimed to critically ascertain the efficiency of preliminary batchwise pre-treatments of crude plant extracts (viz., polyethylenglycol (PEG) precipitation, ammonium sulphate precipitation and sucrose gradient centrifugation) in terms of RuBisCO purification and absolute recovery prior to automated anion-exchange column separation. Under the optimum physical and chemical conditions, the flow-through column system is able to admit crude plant extracts and gives rise to RuBisCO purification yields better than 75%, which might be increased up to 96 ± 9% with a prior PEG fractionation followed by sucrose gradient step.
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Affiliation(s)
- Ruth Suárez
- Department of Chemistry, University of the Balearic Islands, Carretera de Valldemossa km 7.5, E-07122 Palma de Mallorca, Illes Balears, Spain
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