201
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Hauser T, Popilka L, Hartl FU, Hayer-Hartl M. Role of auxiliary proteins in Rubisco biogenesis and function. NATURE PLANTS 2015; 1:15065. [PMID: 27250005 DOI: 10.1038/nplants.2015.65] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Accepted: 04/20/2015] [Indexed: 05/05/2023]
Abstract
Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) catalyses the conversion of atmospheric CO2 into organic compounds during photosynthesis. Despite its pivotal role in plant metabolism, Rubisco is an inefficient enzyme and has therefore been a key target in bioengineering efforts to improve crop yields. Much has been learnt about the complex cellular machinery involved in Rubisco assembly and metabolic repair over recent years. The simple form of Rubisco found in certain bacteria and dinoflagellates comprises two large subunits, and generally requires the chaperonin system for folding. However, the evolution of hexadecameric Rubisco, which comprises eight large and eight small subunits, from its dimeric precursor has rendered Rubisco in most plants, algae, cyanobacteria and proteobacteria dependent on an array of additional factors. These auxiliary factors include several chaperones for assembly as well as ATPases of the AAA+ family for functional maintenance. An integrated view of the pathways underlying Rubisco biogenesis and repair will pave the way for efforts to improve the enzyme with the goal of increasing crop yields.
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Affiliation(s)
- Thomas Hauser
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Leonhard Popilka
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - F Ulrich Hartl
- 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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202
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203
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Nybo SE, Khan NE, Woolston BM, Curtis WR. Metabolic engineering in chemolithoautotrophic hosts for the production of fuels and chemicals. Metab Eng 2015; 30:105-120. [PMID: 25959019 DOI: 10.1016/j.ymben.2015.04.008] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 04/06/2015] [Accepted: 04/29/2015] [Indexed: 12/19/2022]
Abstract
The ability of autotrophic organisms to fix CO2 presents an opportunity to utilize this 'greenhouse gas' as an inexpensive substrate for biochemical production. Unlike conventional heterotrophic microorganisms that consume carbohydrates and amino acids, prokaryotic chemolithoautotrophs have evolved the capacity to utilize reduced chemical compounds to fix CO2 and drive metabolic processes. The use of chemolithoautotrophic hosts as production platforms has been renewed by the prospect of metabolically engineered commodity chemicals and fuels. Efforts such as the ARPA-E electrofuels program highlight both the potential and obstacles that chemolithoautotrophic biosynthetic platforms provide. This review surveys the numerous advances that have been made in chemolithoautotrophic metabolic engineering with a focus on hydrogen oxidizing bacteria such as the model chemolithoautotrophic organism (Ralstonia), the purple photosynthetic bacteria (Rhodobacter), and anaerobic acetogens. Two alternative strategies of microbial chassis development are considered: (1) introducing or enhancing autotrophic capabilities (carbon fixation, hydrogen utilization) in model heterotrophic organisms, or (2) improving tools for pathway engineering (transformation methods, promoters, vectors etc.) in native autotrophic organisms. Unique characteristics of autotrophic growth as they relate to bioreactor design and process development are also discussed in the context of challenges and opportunities for genetic manipulation of organisms as production platforms.
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Affiliation(s)
- S Eric Nybo
- Department of Pharmaceutical Sciences, College of Pharmacy, Ferris State University, Big Rapids, MI, United States
| | - Nymul E Khan
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, United States
| | - Benjamin M Woolston
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Wayne R Curtis
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, United States.
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204
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Varshney P, Mikulic P, Vonshak A, Beardall J, Wangikar PP. Extremophilic micro-algae and their potential contribution in biotechnology. BIORESOURCE TECHNOLOGY 2015; 184:363-372. [PMID: 25443670 DOI: 10.1016/j.biortech.2014.11.040] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Revised: 11/05/2014] [Accepted: 11/07/2014] [Indexed: 05/18/2023]
Abstract
Micro-algae have potential as sustainable sources of energy and products and alternative mode of agriculture. However, their mass cultivation is challenging due to low survival under harsh outdoor conditions and competition from other, undesired, species. Extremophilic micro-algae have a role to play by virtue of their ability to grow under acidic or alkaline pH, high temperature, light, CO2 level and metal concentration. In this review, we provide several examples of potential biotechnological applications of extremophilic micro-algae and the ranges of tolerated extremes. We also discuss the adaptive mechanisms of tolerance to these extremes. Analysis of phylogenetic relationship of the reported extremophiles suggests certain groups of the Kingdom Protista to be more tolerant to extremophilic conditions than other taxa. While extremophilic microalgae are beginning to be explored, much needs to be done in terms of the physiology, molecular biology, metabolic engineering and outdoor cultivation trials before their true potential is realized.
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Affiliation(s)
- Prachi Varshney
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India; School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia; IIT Bombay Monash Research Academy, CSE Building, 2nd Floor, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Paulina Mikulic
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Avigad Vonshak
- Jacob Blaustein Institutes for Desert Research, Ben Gurion University, Sede Boqer Campus, 84990, Israel
| | - John Beardall
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Pramod P Wangikar
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
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205
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Kupriyanova EV, Samylina OS. CO2-concentrating mechanism and its traits in haloalkaliphilic cyanobacteria. Microbiology (Reading) 2015. [DOI: 10.1134/s0026261715010075] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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206
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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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207
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Sekar N, Ramasamy RP. Recent advances in photosynthetic energy conversion. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C-PHOTOCHEMISTRY REVIEWS 2015. [DOI: 10.1016/j.jphotochemrev.2014.09.004] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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208
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Zhang Y, Zhang H, Zou ZR, Liu Y, Hu XH. Deciphering the protective role of spermidine against saline-alkaline stress at physiological and proteomic levels in tomato. PHYTOCHEMISTRY 2015; 110:13-21. [PMID: 25579998 DOI: 10.1016/j.phytochem.2014.12.021] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 11/23/2014] [Accepted: 12/16/2014] [Indexed: 05/20/2023]
Abstract
In this research, the protective effect of spermidine (Spd) in mitigating saline-alkaline stress in tomato (Solanum lycopersicum L.) at physiological and proteomic levels were examined. The results showed that saline-alkaline stress induced accumulation of H2O2 and O2(-*), and increased the activities of antioxidase (SOD, CAT, and POD). Spermidine efficiently alleviated the inhibitory role of saline-alkaline on plant growth and inhibited saline-alkaline stress-induced H2O2 and O2(-*) accumulation. Proteomics investigations of the leaves of tomato seedlings, responding to a 75 mM saline-alkaline solution and 0.25 mM Spd, were performed. Maps of the proteome of leaf extracts were obtained by two-dimensional gel electrophoresis. An average of 49, 47 and 34 spots, which appeared repeatedly and that significantly altered the relative amounts of polypeptides by more than twofold, were detected for seedlings treated with saline-alkaline solution (S) compared to normal solution (CK), saline-alkaline plus spermidine (MS) compared to CK, or S versus MS, respectively. Thirty-nine of these proteins were identified by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry and were classified into five functional categories, including energy and metabolism, signal transduction, amino acid metabolism, protein metabolism, and stress-defense response. Proteomics analysis coupled with bioinformatics indicated that Spd treatment helps tomato seedlings combat saline-alkaline stress by modulating the defense mechanism of plants and activating cellular detoxification, which protect plants from oxidative damage induced by saline-alkaline stress.
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Affiliation(s)
- Yi Zhang
- College of Horticulture, Northwest Agricultural & Forestry University, Yangling, Shaanxi 712100, China; Key Laboratory of Protected Horticultural Engineering in Northwest, Ministry of Agriculture, Northwest Agricultural & Forestry University, Yangling, Shaanxi 712100, China; College of Horticulture, Shanxi Agricultural University, Taigu, Shanxi 030801, China
| | - Hao Zhang
- College of Horticulture, Northwest Agricultural & Forestry University, Yangling, Shaanxi 712100, China; Key Laboratory of Protected Horticultural Engineering in Northwest, Ministry of Agriculture, Northwest Agricultural & Forestry University, Yangling, Shaanxi 712100, China
| | - Zhi-Rong Zou
- College of Horticulture, Northwest Agricultural & Forestry University, Yangling, Shaanxi 712100, China; Key Laboratory of Protected Horticultural Engineering in Northwest, Ministry of Agriculture, Northwest Agricultural & Forestry University, Yangling, Shaanxi 712100, China
| | - Yi Liu
- College of Horticulture, Northwest Agricultural & Forestry University, Yangling, Shaanxi 712100, China; Key Laboratory of Protected Horticultural Engineering in Northwest, Ministry of Agriculture, Northwest Agricultural & Forestry University, Yangling, Shaanxi 712100, China
| | - Xiao-Hui Hu
- College of Horticulture, Northwest Agricultural & Forestry University, Yangling, Shaanxi 712100, China; Key Laboratory of Protected Horticultural Engineering in Northwest, Ministry of Agriculture, Northwest Agricultural & Forestry University, Yangling, Shaanxi 712100, China.
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209
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Bloom AJ. Photorespiration and nitrate assimilation: a major intersection between plant carbon and nitrogen. PHOTOSYNTHESIS RESEARCH 2015; 123:117-28. [PMID: 25366830 DOI: 10.1007/s11120-014-0056-y] [Citation(s) in RCA: 126] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 10/27/2014] [Indexed: 05/22/2023]
Abstract
C3 carbon fixation has a bad reputation, primarily because it is associated with photorespiration, a biochemical pathway thought to waste a substantial amount of the carbohydrate produced in a plant. This review presents evidence collected over nearly a century that (1) Rubisco when associated with Mn(2+) generates additional reductant during photorespiration, (2) this reductant participates in the assimilation of nitrate into protein, and (3) this nitrate assimilation facilitates the use of a nitrogen source that other organisms tend to avoid. This phenomenon explains the continued dominance of C3 plants during the past 23 million years of low CO2 atmospheres as well as the decline in plant protein concentrations as atmospheric CO2 rises.
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Affiliation(s)
- Arnold J Bloom
- Department of Plant Sciences, University of California at Davis, Davis, USA,
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210
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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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211
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Durão P, Aigner H, Nagy P, Mueller-Cajar O, Hartl FU, Hayer-Hartl M. Opposing effects of folding and assembly chaperones on evolvability of Rubisco. Nat Chem Biol 2015; 11:148-55. [PMID: 25558973 DOI: 10.1038/nchembio.1715] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 10/27/2014] [Indexed: 12/29/2022]
Abstract
Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) catalyzes the fixation of CO2 in photosynthesis. Despite its pivotal role, Rubisco is an inefficient enzyme and thus is a key target for directed evolution. Rubisco biogenesis depends on auxiliary factors, including the GroEL/ES-type chaperonin for folding and the chaperone RbcX for assembly. Here we performed directed evolution of cyanobacterial form I Rubisco using a Rubisco-dependent Escherichia coli strain. Overexpression of GroEL/ES enhanced Rubisco solubility and tended to expand the range of permissible mutations. In contrast, the specific assembly chaperone RbcX had a negative effect on evolvability by preventing a subset of mutants from forming holoenzyme. Mutation F140I in the large Rubisco subunit, isolated in the absence of RbcX, increased carboxylation efficiency approximately threefold without reducing CO2 specificity. The F140I mutant resulted in a ∼55% improved photosynthesis rate in Synechocystis PCC6803. The requirement of specific biogenesis factors downstream of chaperonin may have retarded the natural evolution of Rubisco.
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Affiliation(s)
- Paulo Durão
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Harald Aigner
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Péter Nagy
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Oliver Mueller-Cajar
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - F Ulrich Hartl
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Manajit Hayer-Hartl
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
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212
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Vitillo JG. Magnesium-based systems for carbon dioxide capture, storage and recycling: from leaves to synthetic nanostructured materials. RSC Adv 2015. [DOI: 10.1039/c5ra02835c] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Magnesium is used as leitmotif in this review in order to explore the systems involved in natural and artificial CO2 cycles.
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Affiliation(s)
- Jenny G. Vitillo
- Department of Science and High Technology
- Università dell'Insubria
- 22100 Como
- Italy
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213
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Feiz L, Williams-Carrier R, Belcher S, Montano M, Barkan A, Stern DB. A protein with an inactive pterin-4a-carbinolamine dehydratase domain is required for Rubisco biogenesis in plants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 80:862-9. [PMID: 25279696 DOI: 10.1111/tpj.12686] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 09/15/2014] [Accepted: 09/17/2014] [Indexed: 05/13/2023]
Abstract
Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) plays a critical role in sustaining life by catalysis of carbon fixation in the Calvin-Benson pathway. Incomplete knowledge of the assembly pathway of chloroplast Rubisco has hampered efforts to fully delineate the enzyme's properties, or seek improved catalytic characteristics via directed evolution. Here we report that a Mu transposon insertion in the Zea mays (maize) gene encoding a chloroplast dimerization co-factor of hepatocyte nuclear factor 1 (DCoH)/pterin-4α-carbinolamine dehydratases (PCD)-like protein is the causative mutation in a seedling-lethal, Rubisco-deficient mutant named Rubisco accumulation factor 2 (raf2-1). In raf2 mutants newly synthesized Rubisco large subunit accumulates in a high-molecular weight complex, the formation of which requires a specific chaperonin 60-kDa isoform. Analogous observations had been made previously with maize mutants lacking the Rubisco biogenesis proteins RAF1 and BSD2. Chemical cross-linking of maize leaves followed by immunoprecipitation with antibodies to RAF2, RAF1 or BSD2 demonstrated co-immunoprecipitation of each with Rubisco small subunit, and to a lesser extent, co-immunoprecipitation with Rubisco large subunit. We propose that RAF2, RAF1 and BSD2 form transient complexes with the Rubisco small subunit, which in turn assembles with the large subunit as it is released from chaperonins.
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Affiliation(s)
- Leila Feiz
- Boyce Thompson Institute for Plant Research, Cornell University, Tower Road, Ithaca, NY, 14853, USA
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214
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Reijnders MJ, van Heck RG, Lam CM, Scaife MA, Santos VAMD, Smith AG, Schaap PJ. Green genes: bioinformatics and systems-biology innovations drive algal biotechnology. Trends Biotechnol 2014; 32:617-26. [DOI: 10.1016/j.tibtech.2014.10.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 09/30/2014] [Accepted: 10/01/2014] [Indexed: 01/18/2023]
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215
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Singh J, Pandey P, James D, Chandrasekhar K, Achary VMM, Kaul T, Tripathy BC, Reddy MK. Enhancing C3 photosynthesis: an outlook on feasible interventions for crop improvement. PLANT BIOTECHNOLOGY JOURNAL 2014; 12:1217-30. [PMID: 25196090 DOI: 10.1111/pbi.12246] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 07/14/2014] [Accepted: 07/20/2014] [Indexed: 05/05/2023]
Abstract
Despite the declarations and collective measures taken to eradicate hunger at World Food Summits, food security remains one of the biggest issues that we are faced with. The current scenario could worsen due to the alarming increase in world population, further compounded by adverse climatic conditions, such as increase in atmospheric temperature, unforeseen droughts and decreasing soil moisture, which will decrease crop yield even further. Furthermore, the projected increase in yields of C3 crops as a result of increasing atmospheric CO2 concentrations is much less than anticipated. Thus, there is an urgent need to increase crop productivity beyond existing yield potentials to address the challenge of food security. One of the domains of plant biology that promises hope in overcoming this problem is study of C3 photosynthesis. In this review, we have examined the potential bottlenecks of C3 photosynthesis and the strategies undertaken to overcome them. The targets considered for possible intervention include RuBisCO, RuBisCO activase, Calvin-Benson-Bassham cycle enzymes, CO2 and carbohydrate transport, and light reactions among many others. In addition, other areas which promise scope for improvement of C3 photosynthesis, such as mining natural genetic variations, mathematical modelling for identifying new targets, installing efficient carbon fixation and carbon concentrating mechanisms have been touched upon. Briefly, this review intends to shed light on the recent advances in enhancing C3 photosynthesis for crop improvement.
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Affiliation(s)
- Jitender Singh
- Plant Molecular Biology Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India; School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
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216
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Joshi J, Mueller-Cajar O, Tsai YCC, Hartl FU, Hayer-Hartl M. Role of small subunit in mediating assembly of red-type form I Rubisco. J Biol Chem 2014; 290:1066-74. [PMID: 25371207 DOI: 10.1074/jbc.m114.613091] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is the key enzyme involved in photosynthetic carbon fixation, converting atmospheric CO2 to organic compounds. Form I Rubisco is a cylindrical complex composed of eight large (RbcL) subunits that are capped by four small subunits (RbcS) at the top and four at the bottom. Form I Rubiscos are phylogenetically divided into green- and red-type. Some red-type enzymes have catalytically superior properties. Thus, understanding their folding and assembly is of considerable biotechnological interest. Folding of the green-type RbcL subunits in cyanobacteria is mediated by the GroEL/ES chaperonin system, and assembly to holoenzyme requires specialized chaperones such as RbcX and RAF1. Here, we show that the red-type RbcL subunits in the proteobacterium Rhodobacter sphaeroides also fold with GroEL/ES. However, assembly proceeds in a chaperone-independent manner. We find that the C-terminal β-hairpin extension of red-type RbcS, which is absent in green-type RbcS, is critical for efficient assembly. The β-hairpins of four RbcS subunits form an eight-stranded β-barrel that protrudes into the central solvent channel of the RbcL core complex. The two β-barrels stabilize the complex through multiple interactions with the RbcL subunits. A chimeric green-type RbcS carrying the C-terminal β-hairpin renders the assembly of a cyanobacterial Rubisco independent of RbcX. Our results may facilitate the engineering of crop plants with improved growth properties expressing red-type Rubisco.
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Affiliation(s)
- Jidnyasa Joshi
- From the Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Oliver Mueller-Cajar
- From the Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Yi-Chin C Tsai
- From the Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - F Ulrich Hartl
- From the Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Manajit Hayer-Hartl
- From the Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
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217
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Lin MT, Occhialini A, Andralojc PJ, Parry MAJ, Hanson MR. A faster Rubisco with potential to increase photosynthesis in crops. Nature 2014; 513:547-50. [PMID: 25231869 PMCID: PMC4176977 DOI: 10.1038/nature13776] [Citation(s) in RCA: 269] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 08/14/2014] [Indexed: 01/20/2023]
Abstract
In photosynthetic organisms, D-ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is the major enzyme assimilating atmospheric CO2 into the biosphere. Owing to the wasteful oxygenase activity and slow turnover of Rubisco, the enzyme is among the most important targets for improving the photosynthetic efficiency of vascular plants. It has been anticipated that introducing the CO2-concentrating mechanism (CCM) from cyanobacteria into plants could enhance crop yield. However, the complex nature of Rubisco's assembly has made manipulation of the enzyme extremely challenging, and attempts to replace it in plants with the enzymes from cyanobacteria and red algae have not been successful. Here we report two transplastomic tobacco lines with functional Rubisco from the cyanobacterium Synechococcus elongatus PCC7942 (Se7942). We knocked out the native tobacco gene encoding the large subunit of Rubisco by inserting the large and small subunit genes of the Se7942 enzyme, in combination with either the corresponding Se7942 assembly chaperone, RbcX, or an internal carboxysomal protein, CcmM35, which incorporates three small subunit-like domains. Se7942 Rubisco and CcmM35 formed macromolecular complexes within the chloroplast stroma, mirroring an early step in the biogenesis of cyanobacterial β-carboxysomes. Both transformed lines were photosynthetically competent, supporting autotrophic growth, and their respective forms of Rubisco had higher rates of CO2 fixation per unit of enzyme than the tobacco control. These transplastomic tobacco lines represent an important step towards improved photosynthesis in plants and will be valuable hosts for future addition of the remaining components of the cyanobacterial CCM, such as inorganic carbon transporters and the β-carboxysome shell proteins.
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Affiliation(s)
- Myat T Lin
- 1] Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, USA [2]
| | - Alessandro Occhialini
- 1] Plant Biology and Crop Science, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK [2]
| | - P John Andralojc
- Plant Biology and Crop Science, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK
| | - Martin A J Parry
- Plant Biology and Crop Science, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK
| | - Maureen R Hanson
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, USA
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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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219
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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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220
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Flexas J, Carriquí M, Coopman RE, Gago J, Galmés J, Martorell S, Morales F, Diaz-Espejo A. Stomatal and mesophyll conductances to CO₂ in different plant groups: underrated factors for predicting leaf photosynthesis responses to climate change? PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2014; 226:41-8. [PMID: 25113449 DOI: 10.1016/j.plantsci.2014.06.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2013] [Revised: 06/08/2014] [Accepted: 06/13/2014] [Indexed: 05/25/2023]
Abstract
The climate change conditions predicted for the end of the current century are expected to have an impact on the performance of plants under natural conditions. The variables which are foreseen to have a larger effect are increased CO2 concentration and temperature. Although it is generally considered CO2 assimilation rate could be increased by the increasing levels of CO2, it has been reported in previous studies that acclimation to high CO2 results in reductions of physiological parameters involved in photosynthesis, like the maximum carboxylation rate (Vc,max), stomatal conductance (gs) and mesophyll conductance to CO2 (gm). On the one hand, most of the previous modeling efforts have neglected the potential role played by the acclimation of gm to high CO2 and temperature. On the other hand, the effect of climate change on plant clades other than angiosperms, like ferns, has received little attention, and there are no studies evaluating the potential impact of increasing CO2 and temperature on these species. In this study we predicted responses of several representative species among angiosperms, gymnosperms and ferns to increasing CO2 and temperature. Our results show that species with lower photosynthetic capacity - such as some ferns and gymnosperms - would be proportionally more favored under these foreseen environmental conditions. The main reason for this difference is the lower diffusion limitation imposed by gs and gm in plants having high capacity for photosynthesis among the angiosperms, which reduces the positive effect of increasing CO2. However, this apparent advantage of low-diffusion species would be canceled if the two conductances - gs and gm - acclimate and are down regulated to high CO2, which is basically unknown, especially for gymnosperms and ferns. Hence, for a better understanding of different plant responses to future climate, studies are urged in which the actual photosynthetic response/acclimation to increased CO2 and temperature of ferns, gymnosperms and other under-evaluated plant groups is assessed.
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Affiliation(s)
- Jaume Flexas
- Research Group on Plant Biology under Mediterranean Conditions, Departament de Biologia, Universitat de les Illes Balears, Carretera de Valldemossa Km 7.5, 07122 Palma de Mallorca, Illes Balears, Spain.
| | - Marc Carriquí
- Research Group on Plant Biology under Mediterranean Conditions, Departament de Biologia, Universitat de les Illes Balears, Carretera de Valldemossa Km 7.5, 07122 Palma de Mallorca, Illes Balears, Spain
| | - Rafael E Coopman
- Laboratorio de Ecofisiología para la Conservación de Bosques, Instituto de Conservación, Biodiversidad y Territorio, Facultad de Ciencias Forestales y Recursos Naturales, Universidad Austral de Chile, Casilla 567, Valdivia, Chile
| | - Jorge Gago
- Applied Plant and Soil Biology, Faculty of Biology, University of Vigo, 36310 Vigo, Spain
| | - Jeroni Galmés
- Research Group on Plant Biology under Mediterranean Conditions, Departament de Biologia, Universitat de les Illes Balears, Carretera de Valldemossa Km 7.5, 07122 Palma de Mallorca, Illes Balears, Spain
| | - Sebastià Martorell
- Research Group on Plant Biology under Mediterranean Conditions, Departament de Biologia, Universitat de les Illes Balears, Carretera de Valldemossa Km 7.5, 07122 Palma de Mallorca, Illes Balears, Spain
| | - Fermín Morales
- Estación Experimental de Aula Dei (EEAD), CSIC, Dpto. Nutrición Vegetal, Apdo. 13034, E-50080 Zaragoza, Spain
| | - Antonio Diaz-Espejo
- Irrigation and Crop Ecophysiology Group, Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS, CSIC), Avenida Reina Mercedes 10, 41012 Sevilla, Spain
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221
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Galmés J, Kapralov MV, Andralojc PJ, Conesa MÀ, Keys AJ, Parry MAJ, Flexas J. Expanding knowledge of the Rubisco kinetics variability in plant species: environmental and evolutionary trends. PLANT, CELL & ENVIRONMENT 2014; 37:1989-2001. [PMID: 24689692 DOI: 10.1111/pce.12335] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 03/19/2014] [Accepted: 03/22/2014] [Indexed: 05/18/2023]
Abstract
The present study characterizes the kinetic properties of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) from 28 terrestrial plant species, representing different phylogenetic lineages, environmental adaptations and photosynthetic mechanisms. Our findings confirm that past atmospheric CO(2)/O(2) ratio changes and present environmental pressures have influenced Rubisco kinetics. One evolutionary adaptation to a decreasing atmospheric CO(2)/O(2) ratio has been an increase in the affinity of Rubisco for CO(2) (Kc falling), and a consequent decrease in the velocity of carboxylation (kcat (c)), which in turn has been ameliorated by an increase in the proportion of leaf protein accounted by Rubisco. The trade-off between K(c) and k(cat)(c) was not universal among the species studied and deviations from this relationship occur in extant forms of Rubisco. In species adapted to particular environments, including carnivorous plants, crassulacean acid metabolism species and C(3) plants from aquatic and arid habitats, Rubisco has evolved towards increased efficiency, as demonstrated by a higher k(cat)(c)/K(c) ratio. This variability in kinetics was related to the amino acid sequence of the Rubisco large subunit. Phylogenetic analysis identified 13 residues under positive selection during evolution towards specific Rubisco kinetic parameters. This crucial information provides candidate amino acid replacements, which could be implemented to optimize crop photosynthesis under a range of environmental conditions.
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Affiliation(s)
- Jeroni Galmés
- Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears, Palma, Spain
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222
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Improving the sunlight-to-biomass conversion efficiency in microalgal biofactories. J Biotechnol 2014; 201:28-42. [PMID: 25160918 DOI: 10.1016/j.jbiotec.2014.08.021] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 07/31/2014] [Accepted: 08/18/2014] [Indexed: 12/31/2022]
Abstract
Microalgae represent promising organisms for the sustainable production of commodities, chemicals or fuels. Future use of such systems, however, requires increased productivity of microalgal mass cultures in order to reach an economic viability for microalgae-based production schemes. The efficiency of sunlight-to-biomass conversion that can be observed in bulk cultures is generally far lower (35-80%) than the theoretical maximum, because energy losses occur at multiple steps during the light-driven conversion of carbon dioxide to organic carbon. The light-harvesting system is a major source of energy losses and thus a prime target for strain engineering. Truncation of the light-harvesting antenna in the algal model organism Chlamydomonas reinhardtii was shown to be an effective way of increasing culture productivity at least under saturating light conditions. Furthermore engineering of the Calvin-Benson cycle or the creation of photorespiratory bypasses in A. thaliana proved to be successful in terms of achieving higher biomass productivities. An efficient generation of novel microalgal strains with improved sunlight conversion efficiencies by targeted engineering in the future will require an expanded molecular toolkit. In the meantime random mutagenesis coupled to high-throughput screening for desired phenotypes can be used to provide engineered microalgae.
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223
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Zibareva IV, Parmon VN. Identification of “hot spots” of the science of catalysis: bibliometric and thematic analysis of nowaday reviews and monographs. Russ Chem Bull 2014. [DOI: 10.1007/s11172-013-0329-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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224
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Lin MT, Occhialini A, Andralojc JP, Devonshire J, Hines KM, Parry MAJ, Hanson MR. β-Carboxysomal proteins assemble into highly organized structures in Nicotiana chloroplasts. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 79:1-12. [PMID: 24810513 PMCID: PMC4080790 DOI: 10.1111/tpj.12536] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2014] [Accepted: 04/15/2014] [Indexed: 05/18/2023]
Abstract
The photosynthetic efficiency of C3 plants suffers from the reaction of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) with O2 instead of CO2 , leading to the costly process of photorespiration. Increasing the concentration of CO2 around Rubisco is a strategy used by photosynthetic prokaryotes such as cyanobacteria for more efficient incorporation of inorganic carbon. Engineering the cyanobacterial CO2 -concentrating mechanism, the carboxysome, into chloroplasts is an approach to enhance photosynthesis or to compartmentalize other biochemical reactions to confer new capabilities on transgenic plants. We have chosen to explore the possibility of producing β-carboxysomes from Synechococcus elongatus PCC7942, a model freshwater cyanobacterium. Using the agroinfiltration technique, we have transiently expressed multiple β-carboxysomal proteins (CcmK2, CcmM, CcmL, CcmO and CcmN) in Nicotiana benthamiana with fusions that target these proteins into chloroplasts, and that provide fluorescent labels for visualizing the resultant structures. By confocal and electron microscopic analysis, we have observed that the shell proteins of the β-carboxysome are able to assemble in plant chloroplasts into highly organized assemblies resembling empty microcompartments. We demonstrate that a foreign protein can be targeted with a 17-amino-acid CcmN peptide to the shell proteins inside chloroplasts. Our experiments establish the feasibility of introducing carboxysomes into chloroplasts for the potential compartmentalization of Rubisco or other proteins.
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Affiliation(s)
- Myat T. Lin
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853 USA
| | | | - John P. Andralojc
- Plant Biology and Crop Science, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK
| | - Jean Devonshire
- Plant Biology and Crop Science, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK
| | - Kevin M. Hines
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853 USA
| | - Martin A. J. Parry
- Plant Biology and Crop Science, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK
| | - Maureen R. Hanson
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853 USA
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225
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von Caemmerer S, Tazoe Y, Evans JR, Whitney SM. Exploiting transplastomically modified Rubisco to rapidly measure natural diversity in its carbon isotope discrimination using tuneable diode laser spectroscopy. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:3759-67. [PMID: 24687980 PMCID: PMC4085952 DOI: 10.1093/jxb/eru036] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Carbon isotope discrimination (Δ) during C3 photosynthesis is dominated by the fractionation occurring during CO2-fixation by the enzyme Rubisco. While knowing the fractionation by enzymes is pivotal to fully understanding plant carbon metabolism, little is known about variation in the discrimination factor of Rubisco (b) as it is difficult to measure using existing in vitro methodologies. Tuneable diode laser absorption spectroscopy has improved the ability to make rapid measurements of Δ concurrently with photosynthetic gas exchange. This study used this technique to estimate b in vivo in five tobacco (Nicotiana tabacum L. cv Petit Havana [N,N]) genotypes expressing alternative Rubisco isoforms. For transplastomic tobacco producing Rhodospirillum rubrum Rubisco b was 23.8±0.7‰, while Rubisco containing the large subunit Leu-335-Val mutation had a b-value of 13.9±0.7‰. These values were significantly less than that for Rubisco from wild-type tobacco (b=29‰), a C3 species. Transplastomic tobacco producing chimeric Rubisco comprising tobacco Rubisco small subunits and the catalytic large subunits from either the C4 species Flaveria bidentis or the C3-C4 species Flaveria floridana had b-values of 27.8±0.8 and 28.6±0.6‰, respectively. These values were not significantly different from tobacco Rubisco.
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Affiliation(s)
- Susanne von Caemmerer
- Research School of Biology, The Australian National University, Canberra ACT 0200, Australia
| | - Youshi Tazoe
- Research School of Biology, The Australian National University, Canberra ACT 0200, Australia
| | - John R Evans
- Research School of Biology, The Australian National University, Canberra ACT 0200, Australia
| | - Spencer M Whitney
- Research School of Biology, The Australian National University, Canberra ACT 0200, Australia
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226
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Janssen PJD, Lambreva MD, Plumeré N, Bartolucci C, Antonacci A, Buonasera K, Frese RN, Scognamiglio V, Rea G. Photosynthesis at the forefront of a sustainable life. Front Chem 2014; 2:36. [PMID: 24971306 PMCID: PMC4054791 DOI: 10.3389/fchem.2014.00036] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Accepted: 05/25/2014] [Indexed: 11/13/2022] Open
Abstract
The development of a sustainable bio-based economy has drawn much attention in recent years, and research to find smart solutions to the many inherent challenges has intensified. In nature, perhaps the best example of an authentic sustainable system is oxygenic photosynthesis. The biochemistry of this intricate process is empowered by solar radiation influx and performed by hierarchically organized complexes composed by photoreceptors, inorganic catalysts, and enzymes which define specific niches for optimizing light-to-energy conversion. The success of this process relies on its capability to exploit the almost inexhaustible reservoirs of sunlight, water, and carbon dioxide to transform photonic energy into chemical energy such as stored in adenosine triphosphate. Oxygenic photosynthesis is responsible for most of the oxygen, fossil fuels, and biomass on our planet. So, even after a few billion years of evolution, this process unceasingly supports life on earth, and probably soon also in outer-space, and inspires the development of enabling technologies for a sustainable global economy and ecosystem. The following review covers some of the major milestones reached in photosynthesis research, each reflecting lasting routes of innovation in agriculture, environmental protection, and clean energy production.
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Affiliation(s)
- Paul J. D. Janssen
- Molecular and Cellular Biology - Unit of Microbiology, Institute for Environment, Health and Safety, Belgian Nuclear Research Centre SCK•CENMol, Belgium
| | - Maya D. Lambreva
- Institute of Crystallography, National Research Council of ItalyRome, Italy
| | - Nicolas Plumeré
- Center for Electrochemical Sciences-CES, Ruhr-Universität BochumBochum, Germany
| | - Cecilia Bartolucci
- Institute of Crystallography, National Research Council of ItalyRome, Italy
| | - Amina Antonacci
- Institute of Crystallography, National Research Council of ItalyRome, Italy
| | - Katia Buonasera
- Institute of Crystallography, National Research Council of ItalyRome, Italy
| | - Raoul N. Frese
- Division of Physics and Astronomy, Department of Biophysics, VU University AmsterdamAmsterdam, Netherlands
| | | | - Giuseppina Rea
- Institute of Crystallography, National Research Council of ItalyRome, Italy
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227
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Mettler T, Mühlhaus T, Hemme D, Schöttler MA, Rupprecht J, Idoine A, Veyel D, Pal SK, Yaneva-Roder L, Winck FV, Sommer F, Vosloh D, Seiwert B, Erban A, Burgos A, Arvidsson S, Schönfelder S, Arnold A, Günther M, Krause U, Lohse M, Kopka J, Nikoloski Z, Mueller-Roeber B, Willmitzer L, Bock R, Schroda M, Stitt M. Systems Analysis of the Response of Photosynthesis, Metabolism, and Growth to an Increase in Irradiance in the Photosynthetic Model Organism Chlamydomonas reinhardtii. THE PLANT CELL 2014; 26:2310-2350. [PMID: 24894045 PMCID: PMC4114937 DOI: 10.1105/tpc.114.124537] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2014] [Revised: 04/17/2014] [Accepted: 05/06/2014] [Indexed: 05/18/2023]
Abstract
We investigated the systems response of metabolism and growth after an increase in irradiance in the nonsaturating range in the algal model Chlamydomonas reinhardtii. In a three-step process, photosynthesis and the levels of metabolites increased immediately, growth increased after 10 to 15 min, and transcript and protein abundance responded by 40 and 120 to 240 min, respectively. In the first phase, starch and metabolites provided a transient buffer for carbon until growth increased. This uncouples photosynthesis from growth in a fluctuating light environment. In the first and second phases, rising metabolite levels and increased polysome loading drove an increase in fluxes. Most Calvin-Benson cycle (CBC) enzymes were substrate-limited in vivo, and strikingly, many were present at higher concentrations than their substrates, explaining how rising metabolite levels stimulate CBC flux. Rubisco, fructose-1,6-biosphosphatase, and seduheptulose-1,7-bisphosphatase were close to substrate saturation in vivo, and flux was increased by posttranslational activation. In the third phase, changes in abundance of particular proteins, including increases in plastidial ATP synthase and some CBC enzymes, relieved potential bottlenecks and readjusted protein allocation between different processes. Despite reasonable overall agreement between changes in transcript and protein abundance (R2 = 0.24), many proteins, including those in photosynthesis, changed independently of transcript abundance.
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Affiliation(s)
- Tabea Mettler
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Timo Mühlhaus
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Dorothea Hemme
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | | | - Jens Rupprecht
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Adam Idoine
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Daniel Veyel
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Sunil Kumar Pal
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Liliya Yaneva-Roder
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Flavia Vischi Winck
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam-Golm, Germany
| | - Frederik Sommer
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Daniel Vosloh
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Bettina Seiwert
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Alexander Erban
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Asdrubal Burgos
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Samuel Arvidsson
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam-Golm, Germany
| | | | - Anne Arnold
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Manuela Günther
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Ursula Krause
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Marc Lohse
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Joachim Kopka
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Zoran Nikoloski
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Bernd Mueller-Roeber
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam-Golm, Germany
| | - Lothar Willmitzer
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Ralph Bock
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Michael Schroda
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Mark Stitt
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
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228
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Lea-Smith DJ, Bombelli P, Dennis JS, Scott SA, Smith AG, Howe CJ. Phycobilisome-Deficient Strains of Synechocystis sp. PCC 6803 Have Reduced Size and Require Carbon-Limiting Conditions to Exhibit Enhanced Productivity. PLANT PHYSIOLOGY 2014; 165:705-714. [PMID: 24760817 PMCID: PMC4044857 DOI: 10.1104/pp.114.237206] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 04/17/2014] [Indexed: 05/21/2023]
Abstract
Reducing excessive light harvesting in photosynthetic organisms may increase biomass yields by limiting photoinhibition and increasing light penetration in dense cultures. The cyanobacterium Synechocystis sp. PCC 6803 harvests light via the phycobilisome, which consists of an allophycocyanin core and six radiating rods, each with three phycocyanin (PC) discs. Via targeted gene disruption and alterations to the promoter region, three mutants with two (pcpcT→C) and one (ΔCpcC1C2:pcpcT→C) PC discs per rod or lacking PC (olive) were generated. Photoinhibition and chlorophyll levels decreased upon phycobilisome reduction, although greater penetration of white light was observed only in the PC-deficient mutant. In all strains cultured at high cell densities, most light was absorbed by the first 2 cm of the culture. Photosynthesis and respiration rates were also reduced in the ΔCpcC1C2:pcpcT→C and olive mutants. Cell size was smaller in the pcpcT→C and olive strains. Growth and biomass accumulation were similar between the wild-type and pcpcT→C under a variety of conditions. Growth and biomass accumulation of the olive mutant were poorer in carbon-saturated cultures but improved in carbon-limited cultures at higher light intensities, as they did in the ΔCpcC1C2:pcpcT→C mutant. This study shows that one PC disc per rod is sufficient for maximal light harvesting and biomass accumulation, except under conditions of high light and carbon limitation, and two or more are sufficient for maximal oxygen evolution. To our knowledge, this study is the first to measure light penetration in bulk cultures of cyanobacteria and offers important insights into photobioreactor design.
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Affiliation(s)
- David J Lea-Smith
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom (D.J.L.-S., P.B., C.J.H.);Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 3RA, United Kingdom (J.S.D.);Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom (S.A.S.); andDepartment of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom (A.G.S.)
| | - Paolo Bombelli
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom (D.J.L.-S., P.B., C.J.H.);Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 3RA, United Kingdom (J.S.D.);Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom (S.A.S.); andDepartment of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom (A.G.S.)
| | - John S Dennis
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom (D.J.L.-S., P.B., C.J.H.);Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 3RA, United Kingdom (J.S.D.);Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom (S.A.S.); andDepartment of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom (A.G.S.)
| | - Stuart A Scott
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom (D.J.L.-S., P.B., C.J.H.);Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 3RA, United Kingdom (J.S.D.);Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom (S.A.S.); andDepartment of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom (A.G.S.)
| | - Alison G Smith
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom (D.J.L.-S., P.B., C.J.H.);Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 3RA, United Kingdom (J.S.D.);Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom (S.A.S.); andDepartment of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom (A.G.S.)
| | - Christopher J Howe
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom (D.J.L.-S., P.B., C.J.H.);Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 3RA, United Kingdom (J.S.D.);Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom (S.A.S.); andDepartment of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom (A.G.S.)
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229
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Advances in the Production of High-Value Products by Microalgae. Ind Biotechnol (New Rochelle N Y) 2014. [DOI: 10.1089/ind.2013.0039] [Citation(s) in RCA: 168] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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230
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Cai Z, Liu G, Zhang J, Li Y. Development of an activity-directed selection system enabled significant improvement of the carboxylation efficiency of Rubisco. Protein Cell 2014; 5:552-62. [PMID: 24870149 PMCID: PMC4085280 DOI: 10.1007/s13238-014-0072-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 04/23/2014] [Indexed: 12/16/2022] Open
Abstract
Photosynthetic CO2 fixation is the ultimate source of organic carbon on earth and thus is essential for crop production and carbon sequestration. Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) catalyzes the first step of photosynthetic CO2 fixation. However, the extreme low carboxylation efficiency of Rubisco makes it the most attractive target for improving photosynthetic efficiency. Extensive studies have focused on re-engineering a more efficient enzyme, but the effort has been impeded by the limited understanding of its structure-function relationships and the lack of an efficient selection system towards its activity. To address the unsuccessful molecular engineering of Rubisco, we developed an Escherichia coli-based activity-directed selection system which links the growth of host cell solely to the Rubisco activity therein. A Synechococcus sp. PCC7002 Rubisco mutant with E49V and D82G substitutions in the small subunit was selected from a total of 15,000 mutants by one round of evolution. This mutant showed an 85% increase in specific carboxylation activity and a 45% improvement in catalytic efficiency towards CO2. The small-subunit E49V mutation was speculated to influence holoenzyme catalysis through interaction with the large-subunit Q225. This interaction is conserved among various Rubisco from higher plants and Chlamydomonas reinhardtii. Knowledge of these might provide clues for engineering Rubisco from higher plants, with the potential of increasing the crop yield.
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Affiliation(s)
- Zhen Cai
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
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231
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Stitt M, Gibon Y. Why measure enzyme activities in the era of systems biology? TRENDS IN PLANT SCIENCE 2014; 19:256-65. [PMID: 24332227 DOI: 10.1016/j.tplants.2013.11.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 11/05/2013] [Accepted: 11/08/2013] [Indexed: 05/22/2023]
Abstract
Information about the abundance and biological activities of proteins is essential to reveal how genes affect phenotypes. Over the past decade, mass spectrometry (MS)-based proteomics has revolutionized the identification and quantification of proteins, and the detection of post-translational modifications. Interpretation of proteomics data depends on information about the biological activities of proteins, which has created a bottleneck in research. This review focuses on enzymes in central metabolism. We examine the methods used for measuring enzyme activities, and discuss how these methods provide information about the kinetic and regulatory properties of enzymes, their turnover, and how this information can be integrated into metabolic models. We also discuss how robotized assays could enable the genetic networks that control enzyme abundance to be analyzed.
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Affiliation(s)
- Mark Stitt
- Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14476 Potsdam-Golm, Germany.
| | - Yves Gibon
- INRA, University of Bordeaux, UMR 1332 Fruit Biology and Pathology, F-33883 Villenave d'Ornon, France
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232
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Wang B, Du Q, Yang X, Zhang D. Identification and characterization of nuclear genes involved in photosynthesis in Populus. BMC PLANT BIOLOGY 2014; 14:81. [PMID: 24673936 PMCID: PMC3986721 DOI: 10.1186/1471-2229-14-81] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2013] [Accepted: 03/17/2014] [Indexed: 05/29/2023]
Abstract
BACKGROUND The gap between the real and potential photosynthetic rate under field conditions suggests that photosynthesis could potentially be improved. Nuclear genes provide possible targets for improving photosynthetic efficiency. Hence, genome-wide identification and characterization of the nuclear genes affecting photosynthetic traits in woody plants would provide key insights on genetic regulation of photosynthesis and identify candidate processes for improvement of photosynthesis. RESULTS Using microarray and bulked segregant analysis strategies, we identified differentially expressed nuclear genes for photosynthesis traits in a segregating population of poplar. We identified 515 differentially expressed genes in this population (FC ≥ 2 or FC ≤ 0.5, P < 0.05), 163 up-regulated and 352 down-regulated. Real-time PCR expression analysis confirmed the microarray data. Singular Enrichment Analysis identified 48 significantly enriched GO terms for molecular functions (28), biological processes (18) and cell components (2). Furthermore, we selected six candidate genes for functional examination by a single-marker association approach, which demonstrated that 20 SNPs in five candidate genes significantly associated with photosynthetic traits, and the phenotypic variance explained by each SNP ranged from 2.3% to 12.6%. This revealed that regulation of photosynthesis by the nuclear genome mainly involves transport, metabolism and response to stimulus functions. CONCLUSIONS This study provides new genome-scale strategies for the discovery of potential candidate genes affecting photosynthesis in Populus, and for identification of the functions of genes involved in regulation of photosynthesis. This work also suggests that improving photosynthetic efficiency under field conditions will require the consideration of multiple factors, such as stress responses.
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Affiliation(s)
- Bowen Wang
- National Engineering Laboratory for Tree Breeding, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, P. R. China
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants, Ministry of Education, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, P. R. China
| | - Qingzhang Du
- National Engineering Laboratory for Tree Breeding, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, P. R. China
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants, Ministry of Education, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, P. R. China
| | - Xiaohui Yang
- National Engineering Laboratory for Tree Breeding, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, P. R. China
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants, Ministry of Education, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, P. R. China
| | - Deqiang Zhang
- National Engineering Laboratory for Tree Breeding, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, P. R. China
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants, Ministry of Education, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, P. R. China
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233
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Ito H, Tanaka A. Evolution of a new chlorophyll metabolic pathway driven by the dynamic changes in enzyme promiscuous activity. PLANT & CELL PHYSIOLOGY 2014; 55:593-603. [PMID: 24399236 DOI: 10.1093/pcp/pct203] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Organisms generate an enormous number of metabolites; however, the mechanisms by which a new metabolic pathway is acquired are unknown. To elucidate the importance of promiscuous enzyme activity for pathway evolution, the catalytic and substrate specificities of Chl biosynthetic enzymes were examined. In green plants, Chl a and Chl b are interconverted by the Chl cycle: Chl a is hydroxylated to 7-hydroxymethyl chlorophyll a followed by the conversion to Chl b, and both reactions are catalyzed by chlorophyllide a oxygenase. Chl b is reduced to 7-hydroxymethyl chlorophyll a by Chl b reductase and then converted to Chl a by 7-hydroxymethyl chlorophyll a reductase (HCAR). A phylogenetic analysis indicated that HCAR evolved from cyanobacterial 3,8-divinyl chlorophyllide reductase (DVR), which is responsible for the reduction of an 8-vinyl group in the Chl biosynthetic pathway. In addition to vinyl reductase activity, cyanobacterial DVR also has Chl b reductase and HCAR activities; consequently, three of the four reactions of the Chl cycle already existed in cyanobacteria, the progenitor of the chloroplast. During the evolution of cyanobacterial DVR to HCAR, the HCAR activity, a promiscuous reaction of cyanobacterial DVR, became the primary reaction. Moreover, the primary reaction (vinyl reductase activity) and some disadvantageous reactions were lost, but the neutral promiscuous reaction (NADH dehydrogenase) was retained in both DVR and HCAR. We also show that a portion of the Chl c biosynthetic pathway already existed in cyanobacteria. We discuss the importance of dynamic changes in promiscuous activity and of the latent pathways for metabolic evolution.
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Affiliation(s)
- Hisashi Ito
- Institute of Low Temperature Science, Hokkaido University, N19 W8, Kita-ku, Sapporo, 060-0819 Japan
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234
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Scales JC, Parry MAJ, Salvucci ME. A non-radioactive method for measuring Rubisco activase activity in the presence of variable ATP: ADP ratios, including modifications for measuring the activity and activation state of Rubisco. PHOTOSYNTHESIS RESEARCH 2014; 119:355-65. [PMID: 24390640 PMCID: PMC3923112 DOI: 10.1007/s11120-013-9964-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Accepted: 12/19/2013] [Indexed: 05/19/2023]
Abstract
Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) catalyzes carboxylation of ribulose-1,5-bisphosphate, the first in a series of reactions leading to the incorporation of atmospheric CO₂ into biomass. Rubisco requires Rubisco activase (RCA), an AAA+ ATPase that reactivates Rubisco by remodelling the conformation of inhibitor-bound sites. RCA is regulated by the ratio of ADP:ATP, with the precise response potentiated by redox regulation of the alpha-isoform. Measuring the effects of ADP on the activation of Rubisco by RCA using the well-established photometric assay is problematic because of the adenine nucleotide requirement of 3-phosphoglycerate (3-PGA) kinase. Described here is a novel assay for measuring RCA activity in the presence of variable ratios of ADP:ATP. The assay couples the formation of 3-PGA from ribulose 1,5-bisphosphate and CO₂ to NADH oxidation through cofactor-dependent phosphoglycerate mutase, enolase, PEP carboxylase and malate dehydrogenase. The assay was used to determine the effects of Rubisco and RCA concentration and ADP:ATP ratio on RCA activity, and to measure the activation of a modified Rubisco by RCA. Variations of the basic assay were used to measure the activation state of Rubisco in leaf extracts and the activity of purified Rubisco. The assay can be automated for high-throughput processing by conducting the reactions in two stages.
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Affiliation(s)
- Joanna C. Scales
- 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
| | - Michael E. Salvucci
- Arid-Land Agricultural Research Center, U.S. Department of Agriculture-Agricultural Research Service, 21881 N. Cardon Lane, Maricopa, AZ 85138 USA
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235
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Mueller-Cajar O, Stotz M, Bracher A. Maintaining photosynthetic CO2 fixation via protein remodelling: the Rubisco activases. PHOTOSYNTHESIS RESEARCH 2014; 119:191-201. [PMID: 23543331 DOI: 10.1007/s11120-013-9819-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Accepted: 03/19/2013] [Indexed: 05/19/2023]
Abstract
The key photosynthetic, CO2-fixing enzyme Rubisco forms inactivated complexes with its substrate ribulose 1,5-bisphosphate (RuBP) and other sugar phosphate inhibitors. The independently evolved AAA+ proteins Rubisco activase and CbbX harness energy from ATP hydrolysis to remodel Rubisco complexes, facilitating release of these inhibitors. Here, we discuss recent structural and mechanistic advances towards the understanding of protein-mediated Rubisco activation. Both activating proteins appear to form ring-shaped hexameric arrangements typical for AAA+ ATPases in their functional form, but display very different regulatory and biochemical properties. Considering the thermolability of the plant enzyme, an improved understanding of the mechanism for Rubisco activation may help in developing heat-resistant plants adapted to the challenge of global warming.
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Affiliation(s)
- Oliver Mueller-Cajar
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore,
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236
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Way DA, Yamori W. Thermal acclimation of photosynthesis: on the importance of adjusting our definitions and accounting for thermal acclimation of respiration. PHOTOSYNTHESIS RESEARCH 2014; 119:89-100. [PMID: 23812760 DOI: 10.1007/s11120-013-9873-7] [Citation(s) in RCA: 157] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Accepted: 06/12/2013] [Indexed: 05/05/2023]
Abstract
While interest in photosynthetic thermal acclimation has been stimulated by climate warming, comparing results across studies requires consistent terminology. We identify five types of photosynthetic adjustments in warming experiments: photosynthesis as measured at the high growth temperature, the growth temperature, and the thermal optimum; the photosynthetic thermal optimum; and leaf-level photosynthetic capacity. Adjustments of any one of these variables need not mean a concurrent adjustment in others, which may resolve apparently contradictory results in papers using different indicators of photosynthetic acclimation. We argue that photosynthetic thermal acclimation (i.e., that benefits a plant in its new growth environment) should include adjustments of both the photosynthetic thermal optimum (T opt) and photosynthetic rates at the growth temperature (A growth), a combination termed constructive adjustment. However, many species show reduced photosynthesis when grown at elevated temperatures, despite adjustment of some photosynthetic variables, a phenomenon we term detractive adjustment. An analysis of 70 studies on 103 species shows that adjustment of T opt and A growth are more common than adjustment of other photosynthetic variables, but only half of the data demonstrate constructive adjustment. No systematic differences in these patterns were found between different plant functional groups. We also discuss the importance of thermal acclimation of respiration for net photosynthesis measurements, as respiratory temperature acclimation can generate apparent acclimation of photosynthetic processes, even if photosynthesis is unaltered. We show that while dark respiration is often used to estimate light respiration, the ratio of light to dark respiration shifts in a non-predictable manner with a change in leaf temperature.
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Affiliation(s)
- Danielle A Way
- Department of Biology, Western University, London, ON, Canada,
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237
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Rosnow J, Yerramsetty P, Berry JO, Okita TW, Edwards GE. Exploring mechanisms linked to differentiation and function of dimorphic chloroplasts in the single cell C4 species Bienertia sinuspersici. BMC PLANT BIOLOGY 2014; 14:34. [PMID: 24443986 PMCID: PMC3904190 DOI: 10.1186/1471-2229-14-34] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 01/15/2014] [Indexed: 05/11/2023]
Abstract
BACKGROUND In the model single-cell C4 plant Bienertia sinuspersici, chloroplast- and nuclear-encoded photosynthetic enzymes, characteristically confined to either bundle sheath or mesophyll cells in Kranz-type C4 leaves, all occur together within individual leaf chlorenchyma cells. Intracellular separation of dimorphic chloroplasts and key enzymes within central and peripheral compartments allow for C4 carbon fixation analogous to NAD-malic enzyme (NAD-ME) Kranz type species. Several methods were used to investigate dimorphic chloroplast differentiation in B. sinuspersici. RESULTS Confocal analysis revealed that Rubisco-containing chloroplasts in the central compartment chloroplasts (CCC) contained more photosystem II proteins than the peripheral compartment chloroplasts (PCC) which contain pyruvate,Pi dikinase (PPDK), a pattern analogous to the cell type-specific chloroplasts of many Kranz type NAD-ME species. Transient expression analysis using GFP fusion constructs containing various lengths of a B. sinuspersici Rubisco small subunit (RbcS) gene and the transit peptide of PPDK revealed that their import was not specific to either chloroplast type. Immunolocalization showed the rbcL-specific mRNA binding protein RLSB to be selectively localized to the CCC in B. sinuspersici, and to Rubisco-containing BS chloroplasts in the closely related Kranz species Suaeda taxifolia. Comparative fluorescence analyses were made using redox-sensitive and insensitive GFP forms, as well comparative staining using the peroxidase indicator 3,3-diaminobenzidine (DAB), which demonstrated differences in stromal redox potential, with the CCC having a more negative potential than the PCC. CONCLUSIONS Both CCC RLSB localization and the differential chloroplast redox state are suggested to have a role in post-transcriptional rbcL expression.
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Affiliation(s)
- Josh Rosnow
- School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA
| | - Pradeep Yerramsetty
- Department of Biological Sciences, State University of New York, Buffalo, NY 14260, USA
| | - James O Berry
- Department of Biological Sciences, State University of New York, Buffalo, NY 14260, USA
| | - Thomas W Okita
- Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340, USA
| | - Gerald E Edwards
- School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA
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238
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Diffusion Limitation and CO2 Concentrating Mechanisms in Bryophytes. ADVANCES IN PHOTOSYNTHESIS AND RESPIRATION 2014. [DOI: 10.1007/978-94-007-6988-5_6] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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239
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Bhardwaj U, Bhardwaj A, Kumar R, Leelavathi S, Reddy VS, Mazumdar-Leighton S. Revisiting rubisco as a protein substrate for insect midgut proteases. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2014; 85:13-35. [PMID: 24338735 DOI: 10.1002/arch.21140] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Gene fragments encoding the large subunit (LS) of Rubisco (RBCL) were cloned from various species of host plants of phytophagous Lepidoptera and expressed as recombinant proteins in Escherichia coli. Recombinant RBCLs were compared among each other along with casein and native Rubisco as proteinaceous substrates for measuring total midgut protease activities of fourth instar larvae of Helicoverpa armigera feeding on casein, Pieris brassicae feeding on cauliflower, and Antheraea assamensis feeding on Litsea monopetala and Persea bombycina. Cognate rRBCL (from the pertinent host plant species) substrates performed similar to noncognate rRBCL reflecting the conserved nature of encoding genes and the versatile use of these recombinant proteins. Casein and recombinant RBCL generally outperformed native Rubisco as substrates, except where inclusion of a reducing agent in the enzyme assay likely unfolded the plant proteins. Levels of total midgut protease activities detected in A. assamensis larvae feeding on two primary host species were similar, suggesting that the suite(s) of digestive enzymes in these insects could hydrolyze a plant protein efficiently. Protease activities detected in the presence of protease inhibitors and the reducing agent dithiothreitol (DTT) suggested that recombinant RBCL was a suitable protein substrate for studying insect proteases using in vitro enzyme assays and substrate zymography.
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Affiliation(s)
- Usha Bhardwaj
- Plant-Insect Interactions Group, Department of Botany, Delhi University, Delhi, India
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240
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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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241
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Korkhovoy VI, Blume YB. Biodiesel from microalgae: Ways for increasing the effectiveness of lipid accumulation by genetic engineering methods. CYTOL GENET+ 2013. [DOI: 10.3103/s0095452713060030] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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242
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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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243
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Dubouzet JG, Strabala TJ, Wagner A. Potential transgenic routes to increase tree biomass. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2013; 212:72-101. [PMID: 24094056 DOI: 10.1016/j.plantsci.2013.08.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 08/21/2013] [Accepted: 08/22/2013] [Indexed: 05/05/2023]
Abstract
Biomass is a prime target for genetic engineering in forestry because increased biomass yield will benefit most downstream applications such as timber, fiber, pulp, paper, and bioenergy production. Transgenesis can increase biomass by improving resource acquisition and product utilization and by enhancing competitive ability for solar energy, water, and mineral nutrients. Transgenes that affect juvenility, winter dormancy, and flowering have been shown to influence biomass as well. Transgenic approaches have increased yield potential by mitigating the adverse effects of prevailing stress factors in the environment. Simultaneous introduction of multiple genes for resistance to various stress factors into trees may help forest trees cope with multiple or changing environments. We propose multi-trait engineering for tree crops, simultaneously deploying multiple independent genes to address a set of genetically uncorrelated traits that are important for crop improvement. This strategy increases the probability of unpredictable (synergistic or detrimental) interactions that may substantially affect the overall phenotype and its long-term performance. The very limited ability to predict the physiological processes that may be impacted by such a strategy requires vigilance and care during implementation. Hence, we recommend close monitoring of the resultant transgenic genotypes in multi-year, multi-location field trials.
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244
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Flexas J, Niinemets U, Gallé A, Barbour MM, Centritto M, Diaz-Espejo A, Douthe C, Galmés J, Ribas-Carbo M, Rodriguez PL, Rosselló F, Soolanayakanahally R, Tomas M, Wright IJ, Farquhar GD, Medrano H. Diffusional conductances to CO2 as a target for increasing photosynthesis and photosynthetic water-use efficiency. PHOTOSYNTHESIS RESEARCH 2013; 117:45-59. [PMID: 23670217 DOI: 10.1007/s11120-013-9844-z] [Citation(s) in RCA: 172] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 04/25/2013] [Indexed: 05/19/2023]
Abstract
A key objective for sustainable agriculture and forestry is to breed plants with both high carbon gain and water-use efficiency (WUE). At the level of leaf physiology, this implies increasing net photosynthesis (A N) relative to stomatal conductance (g s). Here, we review evidence for CO2 diffusional constraints on photosynthesis and WUE. Analyzing past observations for an extensive pool of crop and wild plant species that vary widely in mesophyll conductance to CO2 (g m), g s, and foliage A N, it was shown that both g s and g m limit A N, although the relative importance of each of the two conductances depends on species and conditions. Based on Fick's law of diffusion, intrinsic WUE (the ratio A N/g s) should correlate on the ratio g m/g s, and not g m itself. Such a correlation is indeed often observed in the data. However, since besides diffusion A N also depends on photosynthetic capacity (i.e., V c,max), this relationship is not always sustained. It was shown that only in a very few cases, genotype selection has resulted in simultaneous increases of both A N and WUE. In fact, such a response has never been observed in genetically modified plants specifically engineered for either reduced g s or enhanced g m. Although increasing g m alone would result in increasing photosynthesis, and potentially increasing WUE, in practice, higher WUE seems to be only achieved when there are no parallel changes in g s. We conclude that for simultaneous improvement of A N and WUE, genetic manipulation of g m should avoid parallel changes in g s, and we suggest that the appropriate trait for selection for enhanced WUE is increased g m/g s.
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Affiliation(s)
- Jaume Flexas
- Research Group on Plant Biology under Mediterranean Conditions, Departament de Biologia, Universitat de les Illes Balears, Carretera de Valldemossa Km 7.5, 07122, Palma de Mallorca, Illes Balears, Spain,
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Galmés J, Aranjuelo I, Medrano H, Flexas J. Variation in Rubisco content and activity under variable climatic factors. PHOTOSYNTHESIS RESEARCH 2013; 117:73-90. [PMID: 23748840 DOI: 10.1007/s11120-013-9861-y] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 05/25/2013] [Indexed: 05/05/2023]
Abstract
The main objective of the present review is to provide a compilation of published data of the effects of several climatic conditions on Rubisco, particularly its activity, state of activation, and concentration, and its influence on leaf gas exchange and photosynthesis. The environmental conditions analyzed include drought, salinity, heavy metals, growth temperature, and elevated [O3], [CO2], and ultraviolet-B irradiance. The results show conclusive evidence for a major negative effect on activity of Rubisco with increasing intensity of a range of abiotic stress factors. This decrease in the activity of Rubisco is associated with down-regulation of the activation state of the enzyme (e.g., by de-carbamylation and/or binding of inhibitory sugar phosphates) in response to drought or high temperature. On the contrary, the negative effects of low temperature, heavy metal stress (cadmium), ozone, and UV-B stress on Rubisco activity are associated with changes in the concentration of Rubisco. Notably, in response to all environmental factors, the regulation of in vivo CO2 assimilation rate was related to Rubisco in vitro parameters, either concentration and/or carboxylation, depending on the particular stress. The importance of the loss of Rubisco activity and its repercussion on plant photosynthesis are discussed in the context of climate change. It is suggested that decreased Rubisco activity will be a major effect induced by climate change, which will need to be considered in any prediction model on plant productivity in the near future.
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Affiliation(s)
- Jeroni Galmés
- Research Group on Plant Biology Under Mediterranean Conditions, Universitat de les Illes Balears, Ctra. de Valldemossa Km. 7.5, 07122, Palma, Spain,
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246
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Wachter RM, Salvucci ME, Carmo-Silva AE, Barta C, Genkov T, Spreitzer RJ. Activation of interspecies-hybrid Rubisco enzymes to assess different models for the Rubisco-Rubisco activase interaction. PHOTOSYNTHESIS RESEARCH 2013; 117:557-66. [PMID: 23613007 DOI: 10.1007/s11120-013-9827-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 04/08/2013] [Indexed: 06/02/2023]
Abstract
Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is prone to inactivation from non-productive binding of sugar-phosphates. Reactivation of Rubisco requires conformational remodeling by a specific chaperone, Rubisco activase. Rubisco activase from tobacco and other plants in the family Solanaceae is an inefficient activator of Rubisco from non-Solanaceae plants and from the green alga Chlamydomonas reinhardtii. To determine if the Rubisco small subunit plays a role in the interaction with Rubisco activase, a hybrid Rubisco (SSNT) composed of tobacco small subunits and Chlamydomonas large subunits was constructed. The SSNT hybrid, like other hybrid Rubiscos containing plant small subunits, supported photoautotrophic growth in Chlamydomonas, but growth in air was much slower than for cells containing wild-type Rubisco. The kinetic properties of the SSNT hybrid Rubisco were similar to the wild-type enzyme, indicating that the poor growth in air was probably caused by disruption of pyrenoid formation and the consequent impairment of the CO2concentrating mechanism. Recombinant Rubisco activase from Arabidopsis activated the SSNT hybrid Rubisco and hybrid Rubiscos containing spinach and Arabidopsis small subunits at rates similar to the rates with wild-type Rubisco. However, none of the hybrid Rubiscos was activated by tobacco Rubisco activase. That replacement of Chlamydomonas small subunits with plant small subunits does not affect the species-specific interaction between Rubisco and Rubisco activase suggests that the association is not dominated by the small subunits that surround the Rubisco central solvent channel. Therefore, the geometry of a side-on binding mode is more consistent with the data than a top-on or ring-stacking binding mode.
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Affiliation(s)
- Rebekka M Wachter
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ, 85287, USA
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247
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Rae BD, Long BM, Badger MR, Price GD. Functions, compositions, and evolution of the two types of carboxysomes: polyhedral microcompartments that facilitate CO2 fixation in cyanobacteria and some proteobacteria. Microbiol Mol Biol Rev 2013; 77:357-79. [PMID: 24006469 PMCID: PMC3811607 DOI: 10.1128/mmbr.00061-12] [Citation(s) in RCA: 242] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cyanobacteria are the globally dominant photoautotrophic lineage. Their success is dependent on a set of adaptations collectively termed the CO2-concentrating mechanism (CCM). The purpose of the CCM is to support effective CO2 fixation by enhancing the chemical conditions in the vicinity of the primary CO2-fixing enzyme, D-ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO), to promote the carboxylase reaction and suppress the oxygenase reaction. In cyanobacteria and some proteobacteria, this is achieved by encapsulation of RubisCO within carboxysomes, which are examples of a group of proteinaceous bodies called bacterial microcompartments. Carboxysomes encapsulate the CO2-fixing enzyme within the selectively permeable protein shell and simultaneously encapsulate a carbonic anhydrase enzyme for CO2 supply from a cytoplasmic bicarbonate pool. These bodies appear to have arisen twice and undergone a process of convergent evolution. While the gross structures of all known carboxysomes are ostensibly very similar, with shared gross features such as a selectively permeable shell layer, each type of carboxysome encapsulates a phyletically distinct form of RubisCO enzyme. Furthermore, the specific proteins forming structures such as the protein shell or the inner RubisCO matrix are not identical between carboxysome types. Each type has evolutionarily distinct forms of the same proteins, as well as proteins that are entirely unrelated to one another. In light of recent developments in the study of carboxysome structure and function, we present this review to summarize the knowledge of the structure and function of both types of carboxysome. We also endeavor to cast light on differing evolutionary trajectories which may have led to the differences observed in extant carboxysomes.
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Affiliation(s)
- Benjamin D Rae
- Division of Plant Science, Research School of Biology, The Australian National University, Canberra, ACT, Australia
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248
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Evans JR. Improving photosynthesis. PLANT PHYSIOLOGY 2013; 162:1780-93. [PMID: 23812345 PMCID: PMC3729760 DOI: 10.1104/pp.113.219006] [Citation(s) in RCA: 184] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Accepted: 06/26/2013] [Indexed: 05/18/2023]
Abstract
Photosynthesis is the basis of plant growth, and improving photosynthesis can contribute toward greater food security in the coming decades as world population increases. Multiple targets have been identified that could be manipulated to increase crop photosynthesis. The most important target is Rubisco because it catalyses both carboxylation and oxygenation reactions and the majority of responses of photosynthesis to light, CO₂, and temperature are reflected in its kinetic properties. Oxygenase activity can be reduced either by concentrating CO₂ around Rubisco or by modifying the kinetic properties of Rubisco. The C₄ photosynthetic pathway is a CO₂-concentrating mechanism that generally enables C₄ plants to achieve greater efficiency in their use of light, nitrogen, and water than C₃ plants. To capitalize on these advantages, attempts have been made to engineer the C₄ pathway into C₃ rice (Oryza sativa). A simpler approach is to transfer bicarbonate transporters from cyanobacteria into chloroplasts and prevent CO₂ leakage. Recent technological breakthroughs now allow higher plant Rubisco to be engineered and assembled successfully in planta. Novel amino acid sequences can be introduced that have been impossible to reach via normal evolution, potentially enlarging the range of kinetic properties and breaking free from the constraints associated with covariation that have been observed between certain kinetic parameters. Capturing the promise of improved photosynthesis in greater yield potential will require continued efforts to improve carbon allocation within the plant as well as to maintain grain quality and resistance to disease and lodging.
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Affiliation(s)
- John R Evans
- Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia.
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249
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Sage RF. Photorespiratory compensation: a driver for biological diversity. PLANT BIOLOGY (STUTTGART, GERMANY) 2013; 15:624-638. [PMID: 23656429 DOI: 10.1111/plb.12024] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 02/07/2013] [Indexed: 06/02/2023]
Abstract
This paper reviews how terrestrial plants reduce photorespiration and thus compensate for its inhibitory effects. As shown in the equation φ = (1/Sc/o )O/C, where φ is the ratio of oxygenation to carboxylation, Sc/o is the relative specificity of Rubisco, O is stromal O2 level and C is the stromal CO2 concentration, plants can reduce photorespiration by increasing Sc/o or C, or by reducing O. By far the most effective means of reducing φ is by concentrating CO2, as occurs in C4 and CAM plants, and to a lesser extent in plants using a glycine shuttle to concentrate CO2 into the bundle sheath. Trapping and refixation of photorespired CO2 by a sheath of chloroplasts around the mesophyll cell periphery in C3 plants also enhances C, particularly at low atmospheric CO2. O2 removal is not practical because high energy and protein investment is needed to have more than a negligible effect. Sc/o enhancement provides for modest reductions in φ, but at the potential cost of limiting the kcat of Rubisco. An effective means of decreasing φ and enhancing carbon gain is to lower leaf temperature by reducing absorbance of solar radiation, or where water is abundant, opening stomata. By using a combination of mechanisms, C3 plants can achieve substantial (>30%) reductions in φ. This may have allowed many C3 species to withstand severe competition from C4 plants in low CO2 atmospheres of recent geological time, thereby preserving some of the Earth's floristic diversity that accumulated over millions of years.
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Affiliation(s)
- R F Sage
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada.
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Galmés J, Perdomo JA, Flexas J, Whitney SM. Photosynthetic characterization of Rubisco transplantomic lines reveals alterations on photochemistry and mesophyll conductance. PHOTOSYNTHESIS RESEARCH 2013; 115:153-66. [PMID: 23703453 DOI: 10.1007/s11120-013-9848-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 05/10/2013] [Indexed: 06/02/2023]
Abstract
Improving Rubisco catalysis is considered a promising way to enhance C3-photosynthesis and photosynthetic water use efficiency (WUE) provided the introduced changes have little or no impact on other processes affecting photosynthesis such as leaf photochemistry or leaf CO2 diffusion conductances. However, the extent to which the factors affecting photosynthetic capacity are co-regulated is unclear. The aim of the present study was to characterize the photochemistry and CO2 transport processes in the leaves of three transplantomic tobacco genotypes expressing hybrid Rubisco isoforms comprising different Flaveria L-subunits that show variations in catalysis and differing trade-offs between the amount of Rubisco and its activation state. Stomatal conductance (g s) in each transplantomic tobacco line matched wild-type, while their photochemistry showed co-regulation with the variations in Rubisco catalysis. A tight co-regulation was observed between Rubisco activity and mesophyll conductance (g m) that was independent of g s thus producing plants with varying g m/g s ratios. Since the g m/g s ratio has been shown to positively correlate with intrinsic WUE, the present results suggest that altering photosynthesis by modifying Rubisco catalysis may also be useful for targeting WUE.
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Affiliation(s)
- Jeroni Galmés
- Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears, Ctra. de Valldemossa Km.7.5, 07122 Palma, Spain.
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