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McQueen E, Sakakibara N, Kamogawa K, Zwijnenburg MA, Tamaki Y, Ishitani O, Sprick RS. Visible-light-responsive hybrid photocatalysts for quantitative conversion of CO 2 to highly concentrated formate solutions. Chem Sci 2024:d4sc05289g. [PMID: 39416289 PMCID: PMC11474659 DOI: 10.1039/d4sc05289g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2024] [Accepted: 10/05/2024] [Indexed: 10/19/2024] Open
Abstract
Photocatalysts can use visible light to convert CO2 into useful products. However, to date photocatalysts for CO2 conversion are limited by insufficient long-term stability and low CO2 conversion rates. Here we report hybrid photocatalysts consisting of conjugated polymers and a ruthenium(ii)-ruthenium(ii) supramolecular photocatalyst which overcome these challenges. The use of conjugated polymers allows for easy fine-tuning of structural and optoelectronic properties through the choice of monomers, and after loading with silver nanoparticles and the ruthenium-based binuclear metal complex, the resulting hybrid systems displayed remarkably enhanced activity for visible light-driven CO2 conversion to formate. In particular, the hybrid photocatalyst system based on poly(dibenzo[b,d]thiophene sulfone) drove the very active, durable and selective photocatalytic CO2 conversion to formate under visible light irradiation. The turnover number was found to be very high (TON = 349 000) with a similarly high turnover frequency (TOF) of 6.5 s-1, exceeding the CO2 fixation activity of ribulose-1,5-bisphosphate carboxylase/oxygenase in natural photosynthesis (TOF = 3.3 s-1), and an apparent quantum yield of 11.2% at 440 nm. Remarkably, quantitative conversion of CO2 (737 μmol, 16.5 mL) to formate was achieved using only 8 mg of the hybrid photocatalyst containing 80 nmol of the supramolecular photocatalyst at standard temperature and pressure. The system sustained photocatalytic activity even after further replenishment of CO2, yielding a very high concentration of formate in the reaction solution up to 0.40 M without significant photocatalyst degradation within the timeframe studied. A range of experiments together with density functional theory calculations allowed us to understand the activity in more detail.
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Affiliation(s)
- Ewan McQueen
- Department of Pure and Applied Chemistry, University of Strathclyde Thomas Graham Building, 295 Cathedral Street Glasgow G1 1XL UK
| | - Noritaka Sakakibara
- Department of Chemistry, School of Science, Tokyo Institute of Technology 2-12-1-NE-2 Ookayama, Meguro Tokyo 152-8550 Japan
| | - Kei Kamogawa
- Department of Chemistry, School of Science, Tokyo Institute of Technology 2-12-1-NE-2 Ookayama, Meguro Tokyo 152-8550 Japan
| | - Martijn A Zwijnenburg
- Department of Chemistry, University College London 20 Gordon Street London WC1H 0AJ UK
| | - Yusuke Tamaki
- Department of Chemistry, School of Science, Tokyo Institute of Technology 2-12-1-NE-2 Ookayama, Meguro Tokyo 152-8550 Japan
| | - Osamu Ishitani
- Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University 1-3-1 Kagamiyama, Higashi-Hiroshima Hiroshima 739 8526 Japan
| | - Reiner Sebastian Sprick
- Department of Pure and Applied Chemistry, University of Strathclyde Thomas Graham Building, 295 Cathedral Street Glasgow G1 1XL UK
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Oh ZG, Askey B, Gunn LH. Red Rubiscos and opportunities for engineering green plants. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:520-542. [PMID: 36055563 PMCID: PMC9833100 DOI: 10.1093/jxb/erac349] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 09/01/2022] [Indexed: 06/15/2023]
Abstract
Nature's vital, but notoriously inefficient, CO2-fixing enzyme Rubisco often limits the growth of photosynthetic organisms including crop species. Form I Rubiscos comprise eight catalytic large subunits and eight auxiliary small subunits and can be classified into two distinct lineages-'red' and 'green'. While red-type Rubiscos (Form IC and ID) are found in rhodophytes, their secondary symbionts, and certain proteobacteria, green-type Rubiscos (Form IA and IB) exist in terrestrial plants, chlorophytes, cyanobacteria, and other proteobacteria. Eukaryotic red-type Rubiscos exhibit desirable kinetic properties, namely high specificity and high catalytic efficiency, with certain isoforms outperforming green-type Rubiscos. However, it is not yet possible to functionally express a high-performing red-type Rubisco in chloroplasts to boost photosynthetic carbon assimilation in green plants. Understanding the molecular and evolutionary basis for divergence between red- and green-type Rubiscos could help us to harness the superior CO2-fixing power of red-type Rubiscos. Here we review our current understanding about red-type Rubisco distribution, biogenesis, and sequence-structure, and present opportunities and challenges for utilizing red-type Rubisco kinetics towards crop improvements.
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Affiliation(s)
- Zhen Guo Oh
- Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, USA
| | - Bryce Askey
- Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, USA
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3
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Ang WSL, How JA, How JB, Mueller-Cajar O. The stickers and spacers of Rubiscondensation: assembling the centrepiece of biophysical CO2-concentrating mechanisms. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:612-626. [PMID: 35903998 DOI: 10.1093/jxb/erac321] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 07/21/2022] [Indexed: 06/15/2023]
Abstract
Aquatic autotrophs that fix carbon using ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) frequently expend metabolic energy to pump inorganic carbon towards the enzyme's active site. A central requirement of this strategy is the formation of highly concentrated Rubisco condensates (or Rubiscondensates) known as carboxysomes and pyrenoids, which have convergently evolved multiple times in prokaryotes and eukaryotes, respectively. Recent data indicate that these condensates form by the mechanism of liquid-liquid phase separation. This mechanism requires networks of weak multivalent interactions typically mediated by intrinsically disordered scaffold proteins. Here we comparatively review recent rapid developments that detail the determinants and precise interactions that underlie diverse Rubisco condensates. The burgeoning field of biomolecular condensates has few examples where liquid-liquid phase separation can be linked to clear phenotypic outcomes. When present, Rubisco condensates are essential for photosynthesis and growth, and they are thus emerging as powerful and tractable models to investigate the structure-function relationship of phase separation in biology.
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Affiliation(s)
- Warren Shou Leong Ang
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore
| | - Jian Ann How
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore
| | - Jian Boon How
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore
| | - Oliver Mueller-Cajar
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore
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4
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Iñiguez C, Aguiló-Nicolau P, Galmés J. Improving photosynthesis through the enhancement of Rubisco carboxylation capacity. Biochem Soc Trans 2021; 49:2007-2019. [PMID: 34623388 DOI: 10.1042/bst20201056] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 09/07/2021] [Accepted: 09/09/2021] [Indexed: 12/14/2022]
Abstract
Rising human population, along with the reduction in arable land and the impacts of global change, sets out the need for continuously improving agricultural resource use efficiency and crop yield (CY). Bioengineering approaches for photosynthesis optimization have largely demonstrated the potential for enhancing CY. This review is focused on the improvement of Rubisco functioning, which catalyzes the rate-limiting step of CO2 fixation required for plant growth, but also catalyzes the ribulose-bisphosphate oxygenation initiating the carbon and energy wasteful photorespiration pathway. Rubisco carboxylation capacity can be enhanced by engineering the Rubisco large and/or small subunit genes to improve its catalytic traits, or by engineering the mechanisms that provide enhanced Rubisco expression, activation and/or elevated [CO2] around the active sites to favor carboxylation over oxygenation. Recent advances have been made in the expression, assembly and activation of foreign (either natural or mutant) faster and/or more CO2-specific Rubisco versions. Some components of CO2 concentrating mechanisms (CCMs) from bacteria, algae and C4 plants has been successfully expressed in tobacco and rice. Still, none of the transformed plant lines expressing foreign Rubisco versions and/or simplified CCM components were able to grow faster than wild type plants under present atmospheric [CO2] and optimum conditions. However, the results obtained up to date suggest that it might be achievable in the near future. In addition, photosynthetic and yield improvements have already been observed when manipulating Rubisco quantity and activation degree in crops. Therefore, engineering Rubisco carboxylation capacity continues being a promising target for the improvement in photosynthesis and yield.
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Affiliation(s)
- Concepción Iñiguez
- Research Group on Plant Biology Under Mediterranean Conditions, Universitat de les Illes Balears-INAGEA, Palma, Balearic Islands, Spain
- Department of Ecology, Faculty of Sciences, University of Málaga, Málaga, Spain
| | - Pere Aguiló-Nicolau
- Research Group on Plant Biology Under Mediterranean Conditions, Universitat de les Illes Balears-INAGEA, Palma, Balearic Islands, Spain
| | - Jeroni Galmés
- Research Group on Plant Biology Under Mediterranean Conditions, Universitat de les Illes Balears-INAGEA, Palma, Balearic Islands, Spain
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5
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Bouvier JW, Emms DM, Rhodes T, Bolton JS, Brasnett A, Eddershaw A, Nielsen JR, Unitt A, Whitney SM, Kelly S. Rubisco Adaptation Is More Limited by Phylogenetic Constraint Than by Catalytic Trade-off. Mol Biol Evol 2021; 38:2880-2896. [PMID: 33739416 PMCID: PMC8233502 DOI: 10.1093/molbev/msab079] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Rubisco assimilates CO2 to form the sugars that fuel life on earth. Correlations between rubisco kinetic traits across species have led to the proposition that rubisco adaptation is highly constrained by catalytic trade-offs. However, these analyses did not consider the phylogenetic context of the enzymes that were analyzed. Thus, it is possible that the correlations observed were an artefact of the presence of phylogenetic signal in rubisco kinetics and the phylogenetic relationship between the species that were sampled. Here, we conducted a phylogenetically resolved analysis of rubisco kinetics and show that there is a significant phylogenetic signal in rubisco kinetic traits. We re-evaluated the extent of catalytic trade-offs accounting for this phylogenetic signal and found that all were attenuated. Following phylogenetic correction, the largest catalytic trade-offs were observed between the Michaelis constant for CO2 and carboxylase turnover (∼21-37%), and between the Michaelis constants for CO2 and O2 (∼9-19%), respectively. All other catalytic trade-offs were substantially attenuated such that they were marginal (<9%) or non-significant. This phylogenetically resolved analysis of rubisco kinetic evolution also identified kinetic changes that occur concomitant with the evolution of C4 photosynthesis. Finally, we show that phylogenetic constraints have played a larger role than catalytic trade-offs in limiting the evolution of rubisco kinetics. Thus, although there is strong evidence for some catalytic trade-offs, rubisco adaptation has been more limited by phylogenetic constraint than by the combined action of all catalytic trade-offs.
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Affiliation(s)
- Jacques W Bouvier
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
- Doctoral Training Centre, University of Oxford, Oxford, United Kingdom
| | - David M Emms
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | - Timothy Rhodes
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Jai S Bolton
- Doctoral Training Centre, University of Oxford, Oxford, United Kingdom
| | - Amelia Brasnett
- Doctoral Training Centre, University of Oxford, Oxford, United Kingdom
| | - Alice Eddershaw
- Doctoral Training Centre, University of Oxford, Oxford, United Kingdom
| | - Jochem R Nielsen
- Doctoral Training Centre, University of Oxford, Oxford, United Kingdom
| | - Anastasia Unitt
- Doctoral Training Centre, University of Oxford, Oxford, United Kingdom
| | - Spencer M Whitney
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Steven Kelly
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
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6
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Ślesak I, Ślesak H. The activity of RubisCO and energy demands for its biosynthesis. Comparative studies with CO 2-reductases. JOURNAL OF PLANT PHYSIOLOGY 2021; 257:153337. [PMID: 33421837 DOI: 10.1016/j.jplph.2020.153337] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 10/14/2020] [Accepted: 11/24/2020] [Indexed: 06/12/2023]
Abstract
Most CO2 on Earth is fixed into organic matter via reactions catalysed by enzymes called carboxylases. CO2-fixation via carboxylases occurs in the Calvin-Benson-Bassham (CBB) cycle, and the crucial role in this cycle is played by RubisCO (D-ribulose 1,5-bisphosphate carboxylase/oxygenase). CO2 can also be fixed by pathways, where a reduction of CO2 to formate or carbon monoxide (CO) occurs. The latter reactions are performed by so-called CO2-reductases e.g. formate dehydrogenase (FDH), carbon-monooxide (CO) dehydrogenase (CODH), and crotonyl-CoA reductase/carboxylase (CCR). In general, a simple model of enzymatic activity based only on a turnover rate of an enzyme for an appropriate substrate (kcat) is insufficient. Based on estimated metabolic costs of each amino acid, the average energetic costs of amino acid biosynthesis (Eaa), and the total costs (ET) for selected CO2-fixing enzymes were analyzed concerning 1) kcat for CO2 (kC), and 2) specificity factor (Srel) for RubisCO. A comparison of Eaa and ET to their kC showed that CODH and FDHs do not need to be more efficient enzymes in CO2 capturing pathways than some forms of RubisCO. CCR was the only both low-cost and highly active CO2-fixing enzyme. The obtained results showed also that there exists an evolutionarily conserved trade-off between Srel of RubisCOs and the energetic demands needed for their biosynthesis. Phylogenetic analysis demonstrated that RubisCO, CODH, FDH, and CCR are enzymes formed as a result of parallel evolution. Moreover, the kinetic parameters (kC) of CO2-fixing enzymes were plausibly optimized already at the early stages of life evolution on Earth.
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Affiliation(s)
- Ireneusz Ślesak
- The Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Niezapominajek 21, 30-239, Kraków, Poland.
| | - Halina Ślesak
- Institute of Botany, Faculty of Biology, Jagiellonian University, Gronostajowa 9, 30-387 Kraków, Poland
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7
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Gunn LH, Martin Avila E, Birch R, Whitney SM. The dependency of red Rubisco on its cognate activase for enhancing plant photosynthesis and growth. Proc Natl Acad Sci U S A 2020; 117:25890-25896. [PMID: 32989135 PMCID: PMC7568259 DOI: 10.1073/pnas.2011641117] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Plant photosynthesis and growth are often limited by the activity of the CO2-fixing enzyme Rubisco. The broad kinetic diversity of Rubisco in nature is accompanied by differences in the composition and compatibility of the ancillary proteins needed for its folding, assembly, and metabolic regulation. Variations in the protein folding needs of catalytically efficient red algae Rubisco prevent their production in plants. Here, we show this impediment does not extend to Rubisco from Rhodobacter sphaeroides (RsRubisco)-a red-type Rubisco able to assemble in plant chloroplasts. In transplastomic tobRsLS lines expressing a codon optimized Rs-rbcLS operon, the messenger RNA (mRNA) abundance was ∼25% of rbcL transcript and RsRubisco ∼40% the Rubisco content in WT tobacco. To mitigate the low activation status of RsRubisco in tobRsLS (∼23% sites active under ambient CO2), the metabolic repair protein RsRca (Rs-activase) was introduced via nuclear transformation. RsRca production in the tobRsLS::X progeny matched endogenous tobacco Rca levels (∼1 µmol protomer·m2) and enhanced RsRubisco activation to 75% under elevated CO2 (1%, vol/vol) growth. Accordingly, the rate of photosynthesis and growth in the tobRsLS::X lines were improved >twofold relative to tobRsLS. Other tobacco lines producing RsRubisco containing alternate diatom and red algae S-subunits were nonviable as CO2-fixation rates (kcatc) were reduced >95% and CO2/O2 specificity impaired 30-50%. We show differences in hybrid and WT RsRubisco biogenesis in tobacco correlated with assembly in Escherichia coli advocating use of this bacterium to preevaluate the kinetic and chloroplast compatibility of engineered RsRubisco, an isoform amenable to directed evolution.
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Affiliation(s)
- Laura H Gunn
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
| | - Elena Martin Avila
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
| | - Rosemary Birch
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
| | - Spencer M Whitney
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
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8
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Davidi D, Shamshoum M, Guo Z, Bar‐On YM, Prywes N, Oz A, Jablonska J, Flamholz A, Wernick DG, Antonovsky N, de Pins B, Shachar L, Hochhauser D, Peleg Y, Albeck S, Sharon I, Mueller‐Cajar O, Milo R. Highly active rubiscos discovered by systematic interrogation of natural sequence diversity. EMBO J 2020; 39:e104081. [PMID: 32500941 PMCID: PMC7507306 DOI: 10.15252/embj.2019104081] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Revised: 04/30/2020] [Accepted: 05/07/2020] [Indexed: 11/09/2022] Open
Abstract
CO2 is converted into biomass almost solely by the enzyme rubisco. The poor carboxylation properties of plant rubiscos have led to efforts that made it the most kinetically characterized enzyme, yet these studies focused on < 5% of its natural diversity. Here, we searched for fast-carboxylating variants by systematically mining genomic and metagenomic data. Approximately 33,000 unique rubisco sequences were identified and clustered into ≈ 1,000 similarity groups. We then synthesized, purified, and biochemically tested the carboxylation rates of 143 representatives, spanning all clusters of form-II and form-II/III rubiscos. Most variants (> 100) were active in vitro, with the fastest having a turnover number of 22 ± 1 s-1 -sixfold faster than the median plant rubisco and nearly twofold faster than the fastest measured rubisco to date. Unlike rubiscos from plants and cyanobacteria, the fastest variants discovered here are homodimers and exhibit a much simpler folding and activation kinetics. Our pipeline can be utilized to explore the kinetic space of other enzymes of interest, allowing us to get a better view of the biosynthetic potential of the biosphere.
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Affiliation(s)
- Dan Davidi
- Department of Plant and Environmental SciencesWeizmann Institute of ScienceRehovotIsrael
- Present address:
Department of GeneticsHarvard Medical SchoolBostonMAUSA
| | - Melina Shamshoum
- Department of Plant and Environmental SciencesWeizmann Institute of ScienceRehovotIsrael
| | - Zhijun Guo
- School of Biological SciencesNanyang Technological UniversitySingaporeSingapore
| | - Yinon M Bar‐On
- Department of Plant and Environmental SciencesWeizmann Institute of ScienceRehovotIsrael
| | - Noam Prywes
- Department of Molecular and Cell BiologyUniversity of CaliforniaBerkeleyCAUSA
| | - Aia Oz
- Migal Galilee Research InstituteKiryat ShmonaIsrael
- Tel Hai CollegeUpper GalileeIsrael
| | - Jagoda Jablonska
- Department of Biomolecular SciencesWeizmann Institute of ScienceRehovotIsrael
| | - Avi Flamholz
- Department of Molecular and Cell BiologyUniversity of CaliforniaBerkeleyCAUSA
| | - David G Wernick
- Department of Plant and Environmental SciencesWeizmann Institute of ScienceRehovotIsrael
- Present address:
BASF Enzymes LLCSan DiegoCAUSA
| | - Niv Antonovsky
- Department of Plant and Environmental SciencesWeizmann Institute of ScienceRehovotIsrael
- Present address:
Laboratory of Genetically Encoded Small MoleculesThe Rockefeller UniversityNew YorkNYUSA
| | - Benoit de Pins
- Department of Plant and Environmental SciencesWeizmann Institute of ScienceRehovotIsrael
| | - Lior Shachar
- Department of Plant and Environmental SciencesWeizmann Institute of ScienceRehovotIsrael
| | - Dina Hochhauser
- Department of Molecular GeneticsWeizmann Institute of ScienceRehovotIsrael
| | - Yoav Peleg
- Department of Life Sciences Core FacilitiesWeizmann Institute of ScienceRehovotIsrael
| | - Shira Albeck
- Department of Life Sciences Core FacilitiesWeizmann Institute of ScienceRehovotIsrael
| | - Itai Sharon
- Migal Galilee Research InstituteKiryat ShmonaIsrael
- Tel Hai CollegeUpper GalileeIsrael
| | | | - Ron Milo
- Department of Plant and Environmental SciencesWeizmann Institute of ScienceRehovotIsrael
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9
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Zhou Y, Whitney S. Directed Evolution of an Improved Rubisco; In Vitro Analyses to Decipher Fact from Fiction. Int J Mol Sci 2019; 20:ijms20205019. [PMID: 31658746 PMCID: PMC6834295 DOI: 10.3390/ijms20205019] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 10/02/2019] [Accepted: 10/04/2019] [Indexed: 01/01/2023] Open
Abstract
Inaccuracies in biochemically characterizing the amount and CO2-fixing properties of the photosynthetic enzyme Ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase continue to hamper an accurate evaluation of Rubisco mutants selected by directed evolution. Here, we outline an analytical pipeline for accurately quantifying Rubisco content and kinetics that averts the misinterpretation of directed evolution outcomes. Our study utilizes a new T7-promoter regulated Rubisco Dependent Escherichia coli (RDE3) screen to successfully select for the first Rhodobacter sphaeroides Rubisco (RsRubisco) mutant with improved CO2-fixing properties. The RsRubisco contains four amino acid substitutions in the large subunit (RbcL) and an improved carboxylation rate (kcatC, up 27%), carboxylation efficiency (kcatC/Km for CO2, increased 17%), unchanged CO2/O2 specificity and a 40% lower holoenzyme biogenesis capacity. Biochemical analysis of RsRubisco chimers coding one to three of the altered amino acids showed Lys-83-Gln and Arg-252-Leu substitutions (plant RbcL numbering) together, but not independently, impaired holoenzyme (L8S8) assembly. An N-terminal Val-11-Ile substitution did not affect RsRubisco catalysis or assembly, while a Tyr-345-Phe mutation alone conferred the improved kinetics without an effect on RsRubisco production. This study confirms the feasibility of improving Rubisco by directed evolution using an analytical pipeline that can identify false positives and reliably discriminate carboxylation enhancing amino acids changes from those influencing Rubisco biogenesis (solubility).
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Affiliation(s)
- Yu Zhou
- Australian Research Council Center of Excellence for Translational Photosynthesis, Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton, ACT 0200, Australia.
| | - Spencer Whitney
- Australian Research Council Center of Excellence for Translational Photosynthesis, Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton, ACT 0200, Australia.
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Atmospheric CO 2 captured by biogenic polyamines is transferred as a possible substrate to Rubisco for the carboxylation reaction. Sci Rep 2018; 8:17724. [PMID: 30531865 PMCID: PMC6286370 DOI: 10.1038/s41598-018-35641-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 10/22/2018] [Indexed: 11/17/2022] Open
Abstract
Biogenic polyamines are involved in a wide range of plant cellular processes, including cell division, morphogenesis and stress responses. However, the exact roles of biogenic polyamines are not well understood. We recently reported that biogenic polyamines that have multiple amino groups can react with CO2 and accelerate calcium carbonate formation in seawater. The ability of biogenic polyamines to capture atmospheric CO2 prompted us to examine their roles in photosynthesis. Here, we demonstrated that atmospheric CO2 captured by biogenic polyamines is a candidate substrate for the carboxylation reaction of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco), which is an enzyme involved in the first major step of carbon fixation during photosynthesis, and that biogenic polyamines can accelerate the carboxylation reaction of this enzyme because of their specific affinity for CO2. Moreover, the results of our nuclear magnetic resonance (NMR) analysis showed that putrescine, which is the most common biogenic polyamine, reacts with atmospheric CO2 and promotes the formation of carbamate derivatives and bicarbonate in aqueous environments. A sufficient amount of CO2 is well known to be produced by carbonic anhydrase from bicarbonate in vivo. The present study indicates that CO2 would be also produced by the equilibrium reaction from carbonate produced by biogenic polyamines and would be used as a substrate of Rubisco, too. Our results may suggest a new photosynthetic research strategy that involves CO2-concentrating mechanisms and also possibly constitutes a potential tool for reducing atmospheric CO2 levels and, consequently, global warming.
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11
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Benedetti M, Vecchi V, Barera S, Dall’Osto L. Biomass from microalgae: the potential of domestication towards sustainable biofactories. Microb Cell Fact 2018; 17:173. [PMID: 30414618 PMCID: PMC6230293 DOI: 10.1186/s12934-018-1019-3] [Citation(s) in RCA: 117] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Accepted: 10/31/2018] [Indexed: 12/22/2022] Open
Abstract
Interest in bulk biomass from microalgae, for the extraction of high-value nutraceuticals, bio-products, animal feed and as a source of renewable fuels, is high. Advantages of microalgal vs. plant biomass production include higher yield, use of non-arable land, recovery of nutrients from wastewater, efficient carbon capture and faster development of new domesticated strains. Moreover, adaptation to a wide range of environmental conditions evolved a great genetic diversity within this polyphyletic group, making microalgae a rich source of interesting and useful metabolites. Microalgae have the potential to satisfy many global demands; however, realization of this potential requires a decrease of the current production costs. Average productivity of the most common industrial strains is far lower than maximal theoretical estimations, suggesting that identification of factors limiting biomass yield and removing bottlenecks are pivotal in domestication strategies aimed to make algal-derived bio-products profitable on the industrial scale. In particular, the light-to-biomass conversion efficiency represents a major constraint to finally fill the gap between theoretical and industrial productivity. In this respect, recent results suggest that significant yield enhancement is feasible. Full realization of this potential requires further advances in cultivation techniques, together with genetic manipulation of both algal physiology and metabolic networks, to maximize the efficiency with which solar energy is converted into biomass and bio-products. In this review, we draft the molecular events of photosynthesis which regulate the conversion of light into biomass, and discuss how these can be targeted to enhance productivity through mutagenesis, strain selection or genetic engineering. We outline major successes reached, and promising strategies to achieving significant contributions to future microalgae-based biotechnology.
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Affiliation(s)
- Manuel Benedetti
- Dipartimento di Biotecnologie, Università di Verona, Strada Le Grazie 15, 37134 Verona, Italy
| | - Valeria Vecchi
- Dipartimento di Biotecnologie, Università di Verona, Strada Le Grazie 15, 37134 Verona, Italy
| | - Simone Barera
- Dipartimento di Biotecnologie, Università di Verona, Strada Le Grazie 15, 37134 Verona, Italy
| | - Luca Dall’Osto
- Dipartimento di Biotecnologie, Università di Verona, Strada Le Grazie 15, 37134 Verona, Italy
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12
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Ren W, Xie J, Hou X, Li X, Guo H, Hu N, Kong L, Zhang J, Chang C, Wu Z. Potential molecular mechanisms of overgrazing-induced dwarfism in sheepgrass (Leymus chinensis) analyzed using proteomic data. BMC PLANT BIOLOGY 2018; 18:81. [PMID: 29739327 PMCID: PMC5941328 DOI: 10.1186/s12870-018-1304-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 04/30/2018] [Indexed: 06/01/2023]
Abstract
BACKGROUND This study was designed to reveal potential molecular mechanisms of long-term overgrazing-induced dwarfism in sheepgrass (Leymus chinensis). METHODS An electrospray ionisation mass spectrometry system was used to generate proteomic data of dwarf sheepgrass from a long-term overgrazed rangeland and normal sheepgrass from a long-term enclosed rangeland. Differentially expressed proteins (DEPs) between dwarf and normal sheepgrass were identified, after which their potential functions and interactions with each other were predicted. The expression of key DEPs was confirmed by high-performance liquid chromatography mass spectrometry (HPLC-MS) using a multiple reaction monitoring method. RESULTS Compared with normal sheepgrass, a total of 51 upregulated and 53 downregulated proteins were identified in dwarf sheepgrass. The amino acids biosynthesis pathway was differentially enriched between the two conditions presenting DEPs, such as SAT5_ARATH and DAPA_MAIZE. The protein-protein interaction (PPI) network revealed a possible interaction between RPOB2_LEPTE, A0A023H9M8_9STRA, ATPB_DIOEL, RBL_AMOTI and DNAK_GRATL. Four modules were also extracted from the PPI network. The HPLC-MS analysis confirmed the upregulation and downregulation of ATPB_DIOEL and DNAK_GRATL, respectively in dwarf samples compared with in the controls. CONCLUSIONS The upregulated ATPB_DIOEL and downregulated DNAK_GRATL as well as proteins that interact with them, such as RPOB2_LEPTE, A0A023H9M8_9STRA and RBL_AMOTI, may be associated with the long-term overgrazing-induced dwarfism in sheepgrass.
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Affiliation(s)
- Weibo Ren
- Institute of Grassland Research, Chinese Academy of Agriculture Sciences, No.120 East Wulanchabu Road, Hohhot, 010010, Inner Mongolia, China
| | - Jihong Xie
- Institute of Grassland Research, Chinese Academy of Agriculture Sciences, No.120 East Wulanchabu Road, Hohhot, 010010, Inner Mongolia, China
| | - Xiangyang Hou
- Institute of Grassland Research, Chinese Academy of Agriculture Sciences, No.120 East Wulanchabu Road, Hohhot, 010010, Inner Mongolia, China
| | - Xiliang Li
- Institute of Grassland Research, Chinese Academy of Agriculture Sciences, No.120 East Wulanchabu Road, Hohhot, 010010, Inner Mongolia, China
| | - Huiqin Guo
- Faculty of life sciences, Inner Mongolia Agriculture University, Hohhot, 010018, Inner Mongolia, China
| | - Ningning Hu
- Institute of Grassland Research, Chinese Academy of Agriculture Sciences, No.120 East Wulanchabu Road, Hohhot, 010010, Inner Mongolia, China
| | - Lingqi Kong
- Institute of Grassland Research, Chinese Academy of Agriculture Sciences, No.120 East Wulanchabu Road, Hohhot, 010010, Inner Mongolia, China
| | - Jize Zhang
- Institute of Grassland Research, Chinese Academy of Agriculture Sciences, No.120 East Wulanchabu Road, Hohhot, 010010, Inner Mongolia, China
| | - Chun Chang
- Institute of Grassland Research, Chinese Academy of Agriculture Sciences, No.120 East Wulanchabu Road, Hohhot, 010010, Inner Mongolia, China
| | - Zinian Wu
- Institute of Grassland Research, Chinese Academy of Agriculture Sciences, No.120 East Wulanchabu Road, Hohhot, 010010, Inner Mongolia, China.
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13
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Gomez-Fernandez BJ, Garcia-Ruiz E, Martin-Diaz J, Gomez de Santos P, Santos-Moriano P, Plou FJ, Ballesteros A, Garcia M, Rodriguez M, Risso VA, Sanchez-Ruiz JM, Whitney SM, Alcalde M. Directed -in vitro- evolution of Precambrian and extant Rubiscos. Sci Rep 2018; 8:5532. [PMID: 29615759 PMCID: PMC5883036 DOI: 10.1038/s41598-018-23869-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 03/19/2018] [Indexed: 11/09/2022] Open
Abstract
Rubisco is an ancient, catalytically conserved yet slow enzyme, which plays a central role in the biosphere's carbon cycle. The design of Rubiscos to increase agricultural productivity has hitherto relied on the use of in vivo selection systems, precluding the exploration of biochemical traits that are not wired to cell survival. We present a directed -in vitro- evolution platform that extracts the enzyme from its biological context to provide a new avenue for Rubisco engineering. Precambrian and extant form II Rubiscos were subjected to an ensemble of directed evolution strategies aimed at improving thermostability. The most recent ancestor of proteobacteria -dating back 2.4 billion years- was uniquely tolerant to mutagenic loading. Adaptive evolution, focused evolution and genetic drift revealed a panel of thermostable mutants, some deviating from the characteristic trade-offs in CO2-fixing speed and specificity. Our findings provide a novel approach for identifying Rubisco variants with improved catalytic evolution potential.
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Affiliation(s)
| | - Eva Garcia-Ruiz
- Department of Biocatalysis, Institute of Catalysis, CSIC, Cantoblanco, 28049, Madrid, Spain
| | - Javier Martin-Diaz
- Department of Biocatalysis, Institute of Catalysis, CSIC, Cantoblanco, 28049, Madrid, Spain
| | | | - Paloma Santos-Moriano
- Department of Biocatalysis, Institute of Catalysis, CSIC, Cantoblanco, 28049, Madrid, Spain
| | - Francisco J Plou
- Department of Biocatalysis, Institute of Catalysis, CSIC, Cantoblanco, 28049, Madrid, Spain
| | - Antonio Ballesteros
- Department of Biocatalysis, Institute of Catalysis, CSIC, Cantoblanco, 28049, Madrid, Spain
| | - Monica Garcia
- División de Tecnología Química y Nuevas Energías, Centro del Tecnología Química, Repsol S.A, 28935, Móstoles, Spain
| | - Marisa Rodriguez
- División de Tecnología Química y Nuevas Energías, Centro del Tecnología Química, Repsol S.A, 28935, Móstoles, Spain
| | - Valeria A Risso
- Facultad de Ciencias, Departamento de Química Física, Universidad de Granada, 18071, Granada, Spain
| | - Jose M Sanchez-Ruiz
- Facultad de Ciencias, Departamento de Química Física, Universidad de Granada, 18071, Granada, Spain
| | - Spencer M Whitney
- Research School of Biology, The Australian National University, Acton, Australian Capital Territory, 2601, Australia
| | - Miguel Alcalde
- Department of Biocatalysis, Institute of Catalysis, CSIC, Cantoblanco, 28049, Madrid, Spain.
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14
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Vitlin Gruber A, Feiz L. Rubisco Assembly in the Chloroplast. Front Mol Biosci 2018; 5:24. [PMID: 29594130 PMCID: PMC5859369 DOI: 10.3389/fmolb.2018.00024] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 02/27/2018] [Indexed: 01/13/2023] Open
Abstract
Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) catalyzes the rate-limiting step in the Calvin-Benson cycle, which transforms atmospheric carbon into a biologically useful carbon source. The slow catalytic rate of Rubisco and low substrate specificity necessitate the production of high levels of this enzyme. In order to engineer a more efficient plant Rubisco, we need to better understand its folding and assembly process. Form I Rubisco, found in green algae and vascular plants, is a hexadecamer composed of 8 large subunits (RbcL), encoded by the chloroplast genome and 8 small, nuclear-encoded subunits (RbcS). Unlike its cyanobacterial homolog, which can be reconstituted in vitro or in E. coli, assisted by bacterial chaperonins (GroEL-GroES) and the RbcX chaperone, biogenesis of functional chloroplast Rubisco requires Cpn60-Cpn20, the chloroplast homologs of GroEL-GroES, and additional auxiliary factors, including Rubisco accumulation factor 1 (Raf1), Rubisco accumulation factor 2 (Raf2) and Bundle sheath defective 2 (Bsd2). The discovery and characterization of these factors paved the way for Arabidopsis Rubisco assembly in E. coli. In the present review, we discuss the uniqueness of hetero-oligomeric chaperonin complex for RbcL folding, as well as the sequential or concurrent actions of the post-chaperonin chaperones in holoenzyme assembly. The exact stages at which each assembly factor functions are yet to be determined. Expression of Arabidopsis Rubisco in E. coli provided some insight regarding the potential roles for Raf1 and RbcX in facilitating RbcL oligomerization, for Bsd2 in stabilizing the oligomeric core prior to holoenzyme assembly, and for Raf2 in interacting with both RbcL and RbcS. In the long term, functional characterization of each known factor along with the potential discovery and characterization of additional factors will set the stage for designing more efficient plants, with a greater biomass, for use in biofuels and sustenance.
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Affiliation(s)
- Anna Vitlin Gruber
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Leila Feiz
- Boyce Thompson Institute, Cornell University, Ithaca, NY, United States
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15
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Uchida H, Kato K, Suzuki K, Yokota A, Kawano S, Matsunaga S, Okada S. Algal Genes Encoding Enzymes for Photosynthesis and Hydrocarbon Biosynthesis as Candidates for Genetic Engineering. CYTOLOGIA 2018. [DOI: 10.1508/cytologia.83.7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Hidenobu Uchida
- Graduate School of Agricultural and Life Sciences, The University of Tokyo
| | - Ko Kato
- Graduate School of Biological Sciences, Nara Institute of Science and Technology
| | - Kensaku Suzuki
- Tohoku Agricultural Research Center, National Agriculture and Food Research Organization
| | - Akiho Yokota
- Graduate School of Biological Sciences, Nara Institute of Science and Technology
| | - Shigeyuki Kawano
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo
| | - Shigeki Matsunaga
- Graduate School of Agricultural and Life Sciences, The University of Tokyo
| | - Shigeru Okada
- Graduate School of Agricultural and Life Sciences, The University of Tokyo
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16
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Abstract
Abstract
Since the discovery of its role in the CO2 fixation reaction in photosynthesis, RuBisCO has been one of the most extensively researched enzymes in the fields of biochemistry, molecular biology, and molecular genetics as well as conventional plant physiology, agricultural chemistry, and crop science. In addition, the RuBisCO and RuBisCO-like genes of more than 2000 organisms have been sequenced during the past 20 years. During the course of those studies, the origin of the RuBisCO gene began to be discussed. Recent studies have reported that the RuBisCO gene emerged in methanogenic bacteria long before photosynthetic organisms appeared. The origin of similar early genes might have allowed this gene to overcome changes in global environments during ancient and recent eras and to participate in the fixation of 200 GT of CO2 annually. In this review, I focus on several points that have not been discussed at length in the literature thus far.
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Affiliation(s)
- Akiho Yokota
- R & D Department, Plant Hi-Tech Institute, Ltd., Ikoma, Japan
- Yokota CREST Laboratory, c/o Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Japan
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17
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Ślesak I, Ślesak H, Kruk J. RubisCO Early Oxygenase Activity: A Kinetic and Evolutionary Perspective. Bioessays 2017; 39. [PMID: 28976010 DOI: 10.1002/bies.201700071] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 08/10/2017] [Indexed: 11/09/2022]
Abstract
RubisCO (D-ribulose 1,5-bisphosphate carboxylase/oxygenase) is Earth's main enzyme responsible for CO2 fixation via carboxylation of ribulose-1,5-bisphosphate (RuBP) into organic matter. Besides the carboxylation reaction, RubisCO also catalyzes the oxygenation of RuBP by O2 , which is probably as old as its carboxylation properties. Based on molecular phylogeny, the occurrence of the reactive oxygen species (ROS)-removing system and kinetic properties of different RubisCO forms, we postulated that RubisCO oxygenase activity appeared in local microoxic areas, yet before the appearance of oxygenic photosynthesis. Here, in reviewing the literature, we present a novel hypothesis: the RubisCO early oxygenase activity hypothesis. This hypothesis may be compared with the exaptation hypothesis, according to which latent RubisCO oxygenase properties emerged later during the oxygenation of the Earth's atmosphere. The reconstruction of ancestral RubisCO forms using ancestral sequence reconstruction (ASR) techniques, as a promising way for testing of RubisCO early oxygenase activity hypothesis, is presented.
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Affiliation(s)
- Ireneusz Ślesak
- The Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Niezapominajek 21, Kraków 30-239, Poland
| | - Halina Ślesak
- Institute of Botany, Jagiellonian University, Gronostajowa 9, Kraków 30-387, Poland
| | - Jerzy Kruk
- Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, Krakow 30-387, Poland
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18
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Mueller-Cajar O. The Diverse AAA+ Machines that Repair Inhibited Rubisco Active Sites. Front Mol Biosci 2017; 4:31. [PMID: 28580359 PMCID: PMC5437159 DOI: 10.3389/fmolb.2017.00031] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 04/29/2017] [Indexed: 11/13/2022] Open
Abstract
Gaseous carbon dioxide enters the biosphere almost exclusively via the active site of the enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco). This highly conserved catalyst has an almost universal propensity to non-productively interact with its substrate ribulose 1,5-bisphosphate, leading to the formation of dead-end inhibited complexes. In diverse autotrophic organisms this tendency has been counteracted by the recruitment of dedicated AAA+ (ATPases associated with various cellular activities) proteins that all use the energy of ATP hydrolysis to remodel inhibited Rubisco active sites leading to release of the inhibitor. Three evolutionarily distinct classes of these Rubisco activases (Rcas) have been discovered so far. Green and red-type Rca are mostly found in photosynthetic eukaryotes of the green and red plastid lineage respectively, whereas CbbQO is associated with chemoautotrophic bacteria. Ongoing mechanistic studies are elucidating how the various motors are utilizing both similar and contrasting strategies to ultimately perform their common function of cracking the inhibited Rubisco active site. The best studied mechanism utilized by red-type Rca appears to involve transient threading of the Rubisco large subunit C-terminal peptide, reminiscent of the action performed by Clp proteases. As well as providing a fascinating example of convergent molecular evolution, Rca proteins can be considered promising crop-improvement targets. Approaches aiming to replace Rubisco in plants with improved enzymes will need to ensure the presence of a compatible Rca protein. The thermolability of the Rca protein found in crop plants provides an opportunity to fortify photosynthesis against high temperature stress. Photosynthesis also appears to be limited by Rca when light conditions are fluctuating. Synthetic biology strategies aiming to enhance the autotrophic CO2 fixation machinery will need to take into consideration the requirement for Rubisco activases as well as their properties.
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Affiliation(s)
- Oliver Mueller-Cajar
- School of Biological Sciences, Nanyang Technological UniversitySingapore, Singapore
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19
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Identification and expression analysis of non-photosynthetic Rubisco small subunit, OsRbcS1-like genes in plants. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/j.plgene.2016.09.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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20
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Sharwood RE, Ghannoum O, Kapralov MV, Gunn LH, Whitney SM. Temperature responses of Rubisco from Paniceae grasses provide opportunities for improving C 3 photosynthesis. NATURE PLANTS 2016; 2:16186. [PMID: 27892943 DOI: 10.1038/nplants.2016.186] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 10/27/2016] [Indexed: 05/03/2023]
Abstract
Enhancing the catalytic properties of the CO2-fixing enzyme Rubisco is a target for improving agricultural crop productivity. Here, we reveal extensive diversity in the kinetic response between 10 and 37 °C by Rubisco from C3 and C4 species within the grass tribe Paniceae. The CO2 fixation rate (kcatc) for Rubisco from the C4 grasses with nicotinamide adenine dinucleotide (NAD) phosphate malic enzyme (NADP-ME) and phosphoenolpyruvate carboxykinase (PCK) photosynthetic pathways was twofold greater than the kcatc of Rubisco from NAD-ME species across all temperatures. The declining response of CO2/O2 specificity with increasing temperature was less pronounced for PCK and NADP-ME Rubisco, which would be advantageous in warmer climates relative to the NAD-ME grasses. Modelled variation in the temperature kinetics of Paniceae C3 Rubisco and PCK Rubisco differentially stimulated C3 photosynthesis relative to tobacco above and below 25 °C under current and elevated CO2. Amino acid substitutions in the large subunit that could account for the catalytic variation among Paniceae Rubisco are identified; however, incompatibilities with Paniceae Rubisco biogenesis in tobacco hindered their mutagenic testing by chloroplast transformation. Circumventing these bioengineering limitations is critical to tailoring the properties of crop Rubisco to suit future climates.
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Affiliation(s)
- Robert E Sharwood
- Research School of Biology, Australian National University, Canberra Australian Capital Territory 2601, Australia
- ARC Centre of Excellence for Translational Photosynthesis, Australian National University, Canberra Australian Capital Territory 2601, Australia
| | - Oula Ghannoum
- ARC Centre of Excellence for Translational Photosynthesis, Australian National University, Canberra Australian Capital Territory 2601, Australia
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales 2753, Australia
| | - Maxim V Kapralov
- School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool L3 3AF, UK
| | - Laura H Gunn
- Research School of Biology, Australian National University, Canberra Australian Capital Territory 2601, Australia
| | - Spencer M Whitney
- Research School of Biology, Australian National University, Canberra Australian Capital Territory 2601, Australia
- ARC Centre of Excellence for Translational Photosynthesis, Australian National University, Canberra Australian Capital Territory 2601, Australia
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21
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Characterization of the heterooligomeric red-type rubisco activase from red algae. Proc Natl Acad Sci U S A 2016; 113:14019-14024. [PMID: 27872295 DOI: 10.1073/pnas.1610758113] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The photosynthetic CO2-fixing enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco) is inhibited by nonproductive binding of its substrate ribulose-1,5-bisphosphate (RuBP) and other sugar phosphates. Reactivation requires ATP-hydrolysis-powered remodeling of the inhibited complexes by diverse molecular chaperones known as rubisco activases (Rcas). Eukaryotic phytoplankton of the red plastid lineage contain so-called red-type rubiscos, some of which have been shown to possess superior kinetic properties to green-type rubiscos found in higher plants. These organisms are known to encode multiple homologs of CbbX, the α-proteobacterial red-type activase. Here we show that the gene products of two cbbX genes encoded by the nuclear and plastid genomes of the red algae Cyanidioschyzon merolae are nonfunctional in isolation, but together form a thermostable heterooligomeric Rca that can use both α-proteobacterial and red algal-inhibited rubisco complexes as a substrate. The mechanism of rubisco activation appears conserved between the bacterial and the algal systems and involves threading of the rubisco large subunit C terminus. Whereas binding of the allosteric regulator RuBP induces oligomeric transitions to the bacterial activase, it merely enhances the kinetics of ATP hydrolysis in the algal enzyme. Mutational analysis of nuclear and plastid isoforms demonstrates strong coordination between the subunits and implicates the nuclear-encoded subunit as being functionally dominant. The plastid-encoded subunit may be catalytically inert. Efforts to enhance crop photosynthesis by transplanting red algal rubiscos with enhanced kinetics will need to take into account the requirement for a compatible Rca.
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22
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Sharwood RE, Sonawane BV, Ghannoum O, Whitney SM. Improved analysis of C4 and C3 photosynthesis via refined in vitro assays of their carbon fixation biochemistry. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:3137-48. [PMID: 27122573 PMCID: PMC4867899 DOI: 10.1093/jxb/erw154] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Plants operating C3 and C4 photosynthetic pathways exhibit differences in leaf anatomy and photosynthetic carbon fixation biochemistry. Fully understanding this underpinning biochemical variation is requisite to identifying solutions for improving photosynthetic efficiency and growth. Here we refine assay methods for accurately measuring the carboxylase and decarboxylase activities in C3 and C4 plant soluble protein. We show that differences in plant extract preparation and assay conditions are required to measure NADP-malic enzyme and phosphoenolpyruvate carboxylase (pH 8, Mg(2+), 22 °C) and phosphoenolpyruvate carboxykinase (pH 7, >2mM Mn(2+), no Mg(2+)) maximal activities accurately. We validate how the omission of MgCl2 during leaf protein extraction, lengthy (>1min) centrifugation times, and the use of non-pure ribulose-1,5-bisphosphate (RuBP) significantly underestimate Rubisco activation status. We show how Rubisco activation status varies with leaf ontogeny and is generally lower in mature C4 monocot leaves (45-60% activation) relative to C3 monocots (55-90% activation). Consistent with their >3-fold lower Rubisco contents, full Rubisco activation in soluble protein from C4 leaves (<5min) was faster than in C3 plant samples (<10min), with addition of Rubisco activase not required for full activation. We conclude that Rubisco inactivation in illuminated leaves primarily stems from RuBP binding to non-carbamylated enzyme, a state readily reversible by dilution during cellular protein extraction.
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Affiliation(s)
- Robert E Sharwood
- ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, Australian National University, Canberra ACT 2601, Australia
| | - Balasaheb V Sonawane
- ARC Centre of Excellence for Translational Photosynthesis, Hawkesbury Institute for the Environment, Western Sydney University, Richmond NSW 2753, Australia
| | - Oula Ghannoum
- ARC Centre of Excellence for Translational Photosynthesis, Hawkesbury Institute for the Environment, Western Sydney University, Richmond NSW 2753, Australia
| | - Spencer M Whitney
- ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, Australian National University, Canberra ACT 2601, Australia
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23
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Carmo-Silva E, Scales JC, Madgwick PJ, Parry MAJ. Optimizing Rubisco and its regulation for greater resource use efficiency. PLANT, CELL & ENVIRONMENT 2015; 38:1817-32. [PMID: 25123951 DOI: 10.1111/pce.12425] [Citation(s) in RCA: 210] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 08/01/2014] [Accepted: 08/03/2014] [Indexed: 05/19/2023]
Abstract
Rubisco catalyses the carboxylation of ribulose-1,5-bisphosphate (RuBP), enabling net CO2 assimilation in photosynthesis. The properties and regulation of Rubisco are not optimal for biomass production in current and projected future environments. Rubisco is relatively inefficient, and large amounts of the enzyme are needed to support photosynthesis, requiring large investments in nitrogen. The competing oxygenation of RuBP by Rubisco decreases photosynthetic efficiency. Additionally, Rubisco is inhibited by some sugar phosphates and depends upon interaction with Rubisco activase (Rca) to be reactivated. Rca activity is modulated by the chloroplast redox status and ADP/ATP ratios, thereby mediating Rubisco activation and photosynthetic induction in response to irradiance. The extreme thermal sensitivity of Rca compromises net CO2 assimilation at moderately high temperatures. Given its central role in carbon assimilation, the improvement of Rubisco function and regulation is tightly linked with irradiance, nitrogen and water use efficiencies. Although past attempts have had limited success, novel technologies and an expanding knowledge base make the challenge of improving Rubisco activity in crops an achievable goal. Strategies to optimize Rubisco and its regulation are addressed in relation to their potential to improve crop resource use efficiency and climate resilience of photosynthesis.
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Affiliation(s)
| | - Joanna C Scales
- Plant Biology and Crop Science, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK
| | - Pippa J Madgwick
- Plant Biology and Crop Science, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK
| | - Martin A J Parry
- Plant Biology and Crop Science, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK
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24
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Tanaka S, Mochizuki Y, Komeiji Y, Okiyama Y, Fukuzawa K. Electron-correlated fragment-molecular-orbital calculations for biomolecular and nano systems. Phys Chem Chem Phys 2015; 16:10310-44. [PMID: 24740821 DOI: 10.1039/c4cp00316k] [Citation(s) in RCA: 197] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Recent developments in the fragment molecular orbital (FMO) method for theoretical formulation, implementation, and application to nano and biomolecular systems are reviewed. The FMO method has enabled ab initio quantum-mechanical calculations for large molecular systems such as protein-ligand complexes at a reasonable computational cost in a parallelized way. There have been a wealth of application outcomes from the FMO method in the fields of biochemistry, medicinal chemistry and nanotechnology, in which the electron correlation effects play vital roles. With the aid of the advances in high-performance computing, the FMO method promises larger, faster, and more accurate simulations of biomolecular and related systems, including the descriptions of dynamical behaviors in solvent environments. The current status and future prospects of the FMO scheme are addressed in these contexts.
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Affiliation(s)
- Shigenori Tanaka
- Graduate School of System Informatics, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan.
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25
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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: 66] [Impact Index Per Article: 6.6] [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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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: 29] [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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Ho SH, Ye X, Hasunuma T, Chang JS, Kondo A. Perspectives on engineering strategies for improving biofuel production from microalgae--a critical review. Biotechnol Adv 2014; 32:1448-59. [PMID: 25285758 DOI: 10.1016/j.biotechadv.2014.09.002] [Citation(s) in RCA: 147] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 09/18/2014] [Accepted: 09/19/2014] [Indexed: 10/24/2022]
Abstract
Although the potential for biofuel production from microalgae via photosynthesis has been intensively investigated, information on the selection of a suitable operation strategy for microalgae-based biofuel production is lacking. Many published reports describe competitive strains and optimal culture conditions for use in biofuel production; however, the major impediment to further improvements is the absence of effective engineering strategies for microalgae cultivation and biofuel production. This comprehensive review discusses recent advances in understanding the effects of major environmental stresses and the characteristics of various engineering operation strategies on the production of biofuels (mainly biodiesel and bioethanol) using microalgae. The performances of microalgae-based biofuel-producing systems under various environmental stresses (i.e., irradiance, temperature, pH, nitrogen depletion, and salinity) and cultivation strategies (i.e., fed-batch, semi-continuous, continuous, two-stage, and salinity-gradient) are compared. The reasons for variations in performance and the underlying theories of the various production strategies are also critically discussed. The aim of this review is to provide useful information to facilitate development of innovative and feasible operation technologies for effectively increasing the commercial viability of microalgae-based biofuel production.
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Affiliation(s)
- Shih-Hsin Ho
- Organization of Advanced Science and Technology, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan
| | - Xiaoting Ye
- Organization of Advanced Science and Technology, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan
| | - Tomohisa Hasunuma
- Organization of Advanced Science and Technology, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan
| | - Jo-Shu Chang
- Department of Chemical Engineering, National Cheng Kung University, Tainan 701, Taiwan; Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 701, Taiwan; Center for Bioscience and Biotechnology, National Cheng Kung University, Tainan 701, Taiwan.
| | - Akihiko Kondo
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan; Biomass Engineering Program, RIKEN, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
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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: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 12/06/2013] [Accepted: 01/20/2014] [Indexed: 05/19/2023]
Abstract
Because of its catalytic inefficiencies, Rubisco is the most obvious target for improvement to enhance the photosynthetic capacity of plants. Two hypotheses are tested in the present work: (1) existing Rubiscos have optimal kinetic properties to maximize photosynthetic carbon assimilation in existing higher plants; (2) current knowledge allows proposal of changes to kinetic properties to make Rubiscos more suited to changed conditions in chloroplasts that are likely to occur with climate change. The catalytic mechanism of Rubisco results in higher catalytic rates of carboxylation being associated with decreased affinity for CO2, so that selection for different environments involves a trade-off between these two properties. The simulations performed in this study confirm that the optimality of Rubisco kinetics depends on the species and the environmental conditions. In particular, environmental drivers affecting the CO2 availability for carboxylation (Cc) or directly shifting the photosynthetic limitations between Rubisco and RuBP regeneration determine to what extend Rubisco kinetics are optimally suited to maximize CO2 assimilation rate. In general, modeled values for optimal kinetic reflect the predominant environmental conditions currently encountered by the species in the field. Under future climatic conditions, photosynthetic CO2 assimilation will be limited by RuBP-regeneration, especially in the absence of water stress, the largest rise in [CO2] and the lowest increases in temperature. Under these conditions, the model predicts that optimal Rubisco should have high Sc/o and low kcat(c).
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Affiliation(s)
- J Galmés
- Research Group in Plant Biology under Mediterranean Conditions, Department of Biology, Universitat de les Illes Balears, Carretera de Valldemossa km 7.5, 07122 Palma, Illes Balears, Spain.
| | - M À Conesa
- Research Group in Plant Biology under Mediterranean Conditions, Department of Biology, Universitat de les Illes Balears, Carretera de Valldemossa km 7.5, 07122 Palma, Illes Balears, Spain
| | - A Díaz-Espejo
- Irrigation and Crop Ecophysiology Group, Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS, CSIC), Avenida Reina Mercedes 10, 41012 Sevilla, Spain
| | - A Mir
- Computational Biology and Bioinformatics Research Group, Department of Mathematics and Computer Science, Universitat de les Illes Balears, Carretera de Valldemossa km 7.5, 07122 Palma, Illes Balears, Spain
| | - J A Perdomo
- Research Group in Plant Biology under Mediterranean Conditions, Department of Biology, Universitat de les Illes Balears, Carretera de Valldemossa km 7.5, 07122 Palma, Illes Balears, Spain
| | - U Niinemets
- Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 1, Tartu 51014, Estonia
| | - J Flexas
- Research Group in Plant Biology under Mediterranean Conditions, Department of Biology, Universitat de les Illes Balears, Carretera de Valldemossa km 7.5, 07122 Palma, Illes Balears, Spain
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Sharwood RE, Whitney SM. Correlating Rubisco catalytic and sequence diversity within C3 plants with changes in atmospheric CO2 concentrations. PLANT, CELL & ENVIRONMENT 2014; 37:1981-1984. [PMID: 24934767 DOI: 10.1111/pce.12386] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [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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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: 2.4] [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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31
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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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32
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Parry MAJ, Andralojc PJ, Scales JC, Salvucci ME, Carmo-Silva AE, Alonso H, Whitney SM. Rubisco activity and regulation as targets for crop improvement. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:717-30. [PMID: 23162118 DOI: 10.1093/jxb/ers336] [Citation(s) in RCA: 247] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Rubisco (ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase) enables net carbon fixation through the carboxylation of RuBP. However, some characteristics of Rubisco make it surprisingly inefficient and compromise photosynthetic productivity. For example, Rubisco catalyses a wasteful reaction with oxygen that leads to the release of previously fixed CO(2) and NH(3) and the consumption of energy during photorespiration. Furthermore, Rubisco is slow and large amounts are needed to support adequate photosynthetic rates. Consequently, Rubisco has been studied intensively as a prime target for manipulations to 'supercharge' photosynthesis and improve both productivity and resource use efficiency. The catalytic properties of Rubiscos from diverse sources vary considerably, suggesting that changes in turnover rate, affinity, or specificity for CO(2) can be introduced to improve Rubisco performance in specific crops and environments. While attempts to manipulate plant Rubisco by nuclear transformation have had limited success, modifying its catalysis by targeted changes to its catalytic large subunit via chloroplast transformation have been much more successful. However, this technique is still in need of development for most major food crops including maize, wheat, and rice. Other bioengineering approaches for improving Rubisco performance include improving the activity of its ancillary protein, Rubisco activase, in addition to modulating the synthesis and degradation of Rubisco's inhibitory sugar phosphate ligands. As the rate-limiting step in carbon assimilation, even modest improvements in the overall performance of Rubisco pose a viable pathway for obtaining significant gains in plant yield, particularly under stressful environmental conditions.
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Affiliation(s)
- Martin A J Parry
- Plant Biology and Crop Science, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK.
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33
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Hanson MR, Gray BN, Ahner BA. Chloroplast transformation for engineering of photosynthesis. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:731-42. [PMID: 23162121 DOI: 10.1093/jxb/ers325] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Many efforts are underway to engineer improvements in photosynthesis to meet the challenges of increasing demands for food and fuel in rapidly changing environmental conditions. Various transgenes have been introduced into either the nuclear or plastid genomes in attempts to increase photosynthetic efficiency. We examine the current knowledge of the critical features that affect levels of expression of plastid transgenes and protein accumulation in transplastomic plants, such as promoters, 5' and 3' untranslated regions, RNA-processing sites, translation signals and amino acid sequences that affect protein turnover. We review the prior attempts to manipulate the properties of ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco) through plastid transformation. We illustrate how plastid operons could be created for expression of the multiple genes needed to introduce new pathways or enzymes to enhance photosynthetic rates or reduce photorespiration. We describe here the past accomplishments and future prospects for manipulating plant enzymes and pathways to enhance carbon assimilation through plastid transformation.
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Affiliation(s)
- Maureen R Hanson
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA.
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34
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Structural mechanism of RuBisCO activation by carbamylation of the active site lysine. Proc Natl Acad Sci U S A 2012; 109:18785-90. [PMID: 23112176 DOI: 10.1073/pnas.1210754109] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) is a crucial enzyme in carbon fixation and the most abundant protein on earth. It has been studied extensively by biochemical and structural methods; however, the most essential activation step has not yet been described. Here, we describe the mechanistic details of Lys carbamylation that leads to RuBisCO activation by atmospheric CO(2). We report two crystal structures of nitrosylated RuBisCO from the red algae Galdieria sulphuraria with O(2) and CO(2) bound at the active site. G. sulphuraria RuBisCO is inhibited by cysteine nitrosylation that results in trapping of these gaseous ligands. The structure with CO(2) defines an elusive, preactivation complex that contains a metal cation Mg(2+) surrounded by three H(2)O/OH molecules. Both structures suggest the mechanism for discriminating gaseous ligands by their quadrupole electric moments. We describe conformational changes that allow for intermittent binding of the metal ion required for activation. On the basis of these structures we propose the individual steps of the activation mechanism. Knowledge of all these elements is indispensable for engineering RuBisCO into a more efficient enzyme for crop enhancement or as a remedy to global warming.
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35
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Venkatesh J, Park SW. Plastid genetic engineering in Solanaceae. PROTOPLASMA 2012; 249:981-99. [PMID: 22395455 PMCID: PMC3459085 DOI: 10.1007/s00709-012-0391-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Accepted: 02/21/2012] [Indexed: 05/23/2023]
Abstract
Plastid genetic engineering has come of age, becoming today an attractive alternative approach for the expression of foreign genes, as it offers several advantages over nuclear transformants. Significant progress has been made in plastid genetic engineering in tobacco and other Solanaceae plants, through the use of improved regeneration procedures and transformation vectors with efficient promoters and untranslated regions. Many genes encoding for industrially important proteins and vaccines, as well as genes conferring important agronomic traits, have been stably integrated and expressed in the plastid genome. Despite these advances, it remains a challenge to achieve marked levels of plastid transgene expression in non-green tissues. In this review, we summarize the basic requirements of plastid genetic engineering and discuss the current status, limitations, and the potential of plastid transformation for expanding future studies relating to Solanaceae plants.
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Affiliation(s)
- Jelli Venkatesh
- Department of Molecular Biotechnology, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul, 143-701 Republic of Korea
| | - Se Won Park
- Department of Molecular Biotechnology, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul, 143-701 Republic of Korea
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36
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Stephenson PG, Moore CM, Terry MJ, Zubkov MV, Bibby TS. Improving photosynthesis for algal biofuels: toward a green revolution. Trends Biotechnol 2011; 29:615-23. [DOI: 10.1016/j.tibtech.2011.06.005] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Revised: 05/30/2011] [Accepted: 06/14/2011] [Indexed: 10/18/2022]
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Bracher A, Starling-Windhof A, Hartl FU, Hayer-Hartl M. Crystal structure of a chaperone-bound assembly intermediate of form I Rubisco. Nat Struct Mol Biol 2011; 18:875-80. [PMID: 21765418 DOI: 10.1038/nsmb.2090] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Accepted: 05/20/2011] [Indexed: 11/09/2022]
Abstract
The form I Rubisco of autotrophic bacteria, algae and plants is a complex of eight large (RbcL) and eight small (RbcS) subunits. It fixes atmospheric CO(2) in the dark reaction of photosynthesis. As shown for the cyanobacterial enzyme, folding of the RbcL subunits is mediated by the GroEL-GroES chaperonin system, and assembly requires the specialized chaperone RbcX, a homodimer of ~15-kDa subunits. Here we present the 3.2-Å crystal structure of a Rubisco assembly intermediate, consisting of the RbcL(8) core with eight RbcX(2) molecules bound. The structure reveals the molecular mechanism by which RbcX(2) mediates oligomeric assembly. Specifically, RbcX(2) provides positional information for proper formation of antiparallel RbcL dimers, thereby preventing RbcL-RbcL misalignment and off-pathway aggregation. The RbcL(8)(RbcX(2))(8) structure also suggests that RbcS functions by stabilizing the '60s loop' of RbcL in the catalytically active conformation.
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Affiliation(s)
- Andreas Bracher
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany.
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Ishikawa C, Hatanaka T, Misoo S, Miyake C, Fukayama H. Functional incorporation of sorghum small subunit increases the catalytic turnover rate of Rubisco in transgenic rice. PLANT PHYSIOLOGY 2011; 156:1603-11. [PMID: 21562335 PMCID: PMC3135941 DOI: 10.1104/pp.111.177030] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Accepted: 05/06/2011] [Indexed: 05/17/2023]
Abstract
Rubisco limits photosynthetic CO(2) fixation because of its low catalytic turnover rate (k(cat)) and competing oxygenase reaction. Previous attempts to improve the catalytic efficiency of Rubisco by genetic engineering have gained little progress. Here we demonstrate that the introduction of the small subunit (RbcS) of high k(cat) Rubisco from the C(4) plant sorghum (Sorghum bicolor) significantly enhances k(cat) of Rubisco in transgenic rice (Oryza sativa). Three independent transgenic lines expressed sorghum RbcS at a high level, accounting for 30%, 44%, and 79% of the total RbcS. Rubisco was likely present as a chimera of sorghum and rice RbcS, and showed 1.32- to 1.50-fold higher k(cat) than in nontransgenic rice. Rubisco from transgenic lines showed a higher K(m) for CO(2) and slightly lower specificity for CO(2) than nontransgenic controls. These results suggest that Rubisco in rice transformed with sorghum RbcS partially acquires the catalytic properties of sorghum Rubisco. Rubisco content in transgenic lines was significantly increased over wild-type levels but Rubisco activation was slightly decreased. The expression of sorghum RbcS did not affect CO(2) assimilation rates under a range of CO(2) partial pressures. The J(max)/V(cmax) ratio was significantly lower in transgenic line compared to the nontransgenic plants. These observations suggest that the capacity of electron transport is not sufficient to support the increased Rubisco capacity in transgenic rice. Although the photosynthetic rate was not enhanced, the strategy presented here opens the way to engineering Rubisco for improvement of photosynthesis and productivity in the future.
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Sen L, Fares MA, Liang B, Gao L, Wang B, Wang T, Su YJ. Molecular evolution of rbcL in three gymnosperm families: identifying adaptive and coevolutionary patterns. Biol Direct 2011; 6:29. [PMID: 21639885 PMCID: PMC3129321 DOI: 10.1186/1745-6150-6-29] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Accepted: 06/03/2011] [Indexed: 11/10/2022] Open
Abstract
Background The chloroplast-localized ribulose-1, 5-biphosphate carboxylase/oxygenase (Rubisco), the primary enzyme responsible for autotrophy, is instrumental in the continual adaptation of plants to variations in the concentrations of CO2. The large subunit (LSU) of Rubisco is encoded by the chloroplast rbcL gene. Although adaptive processes have been previously identified at this gene, characterizing the relationships between the mutational dynamics at the protein level may yield clues on the biological meaning of such adaptive processes. The role of such coevolutionary dynamics in the continual fine-tuning of RbcL remains obscure. Results We used the timescale and phylogenetic analyses to investigate and search for processes of adaptive evolution in rbcL gene in three gymnosperm families, namely Podocarpaceae, Taxaceae and Cephalotaxaceae. To understand the relationships between regions identified as having evolved under adaptive evolution, we performed coevolutionary analyses using the software CAPS. Importantly, adaptive processes were identified at amino acid sites located on the contact regions among the Rubisco subunits and on the interface between Rubisco and its activase. Adaptive amino acid replacements at these regions may have optimized the holoenzyme activity. This hypothesis was pinpointed by evidence originated from our analysis of coevolution that supported the correlated evolution between Rubisco and its activase. Interestingly, the correlated adaptive processes between both these proteins have paralleled the geological variation history of the concentration of atmospheric CO2. Conclusions The gene rbcL has experienced bursts of adaptations in response to the changing concentration of CO2 in the atmosphere. These adaptations have emerged as a result of a continuous dynamic of mutations, many of which may have involved innovation of functional Rubisco features. Analysis of the protein structure and the functional implications of such mutations put forward the conclusion that this evolutionary scenario has been possible through a complex interplay between adaptive mutations, often structurally destabilizing, and compensatory mutations. Our results unearth patterns of evolution that have likely optimized the Rubisco activity and uncover mutational dynamics useful in the molecular engineering of enzymatic activities. Reviewers This article was reviewed by Prof. Christian Blouin (nominated by Dr W Ford Doolittle), Dr Endre Barta (nominated by Dr Sandor Pongor), and Dr Nicolas Galtier.
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Affiliation(s)
- Lin Sen
- CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China
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Suárez R, Miró M, Cerdà V, Perdomo JA, Galmés J. Automated flow-based anion-exchange method for high-throughput isolation and real-time monitoring of RuBisCO in plant extracts. Talanta 2011; 84:1259-66. [PMID: 21641435 DOI: 10.1016/j.talanta.2011.01.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 01/01/2011] [Accepted: 01/12/2011] [Indexed: 11/17/2022]
Abstract
In this work, a miniaturized, completely enclosed multisyringe-flow system is proposed for high-throughput purification of RuBisCO from Triticum aestivum extracts. The automated method capitalizes on the uptake of the target protein at 4°C onto Q-Sepharose Fast Flow strong anion-exchanger packed in a cylindrical microcolumn (105 × 4 mm) followed by a stepwise ionic-strength gradient elution (0-0.8 mol/L NaCl) to eliminate concomitant extract components and retrieve highly purified RuBisCO. The manifold is furnished downstream with a flow-through diode-array UV/vis spectrophotometer for real-time monitoring of the column effluent at the protein-specific wavelength of 280 nm to detect the elution of RuBisCO. Quantitation of RuBisCO and total soluble proteins in the eluate fractions were undertaken using polyacrylamide gel electrophoresis (PAGE) and the spectrophotometric Bradford assay, respectively. A comprehensive investigation of the effect of distinct concentration gradients on the isolation of RuBisCO and experimental conditions (namely, type of resin, column dimensions and mobile-phase flow rate) upon column capacity and analyte breakthrough was effected. The assembled set-up was aimed to critically ascertain the efficiency of preliminary batchwise pre-treatments of crude plant extracts (viz., polyethylenglycol (PEG) precipitation, ammonium sulphate precipitation and sucrose gradient centrifugation) in terms of RuBisCO purification and absolute recovery prior to automated anion-exchange column separation. Under the optimum physical and chemical conditions, the flow-through column system is able to admit crude plant extracts and gives rise to RuBisCO purification yields better than 75%, which might be increased up to 96 ± 9% with a prior PEG fractionation followed by sucrose gradient step.
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Affiliation(s)
- Ruth Suárez
- Department of Chemistry, University of the Balearic Islands, Carretera de Valldemossa km 7.5, E-07122 Palma de Mallorca, Illes Balears, Spain
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Coupled chaperone action in folding and assembly of hexadecameric Rubisco. Nature 2010; 463:197-202. [DOI: 10.1038/nature08651] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2009] [Accepted: 11/09/2009] [Indexed: 12/19/2022]
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43
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Direct photosynthetic recycling of carbon dioxide to isobutyraldehyde. Nat Biotechnol 2009; 27:1177-80. [DOI: 10.1038/nbt.1586] [Citation(s) in RCA: 663] [Impact Index Per Article: 41.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Accepted: 10/07/2009] [Indexed: 11/08/2022]
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Abstract
Dwindling petroleum feedstocks and increased CO(2)-concentrations in the atmosphere currently open the concept of using CO(2) as raw material for the synthesis of well-defined organic compounds. In parallel to recent advances in the chemical CO(2)-fixation, enzymatic (biocatalytic) carboxylation is currently being investigated at an increased pace. On the one hand, this critical review provides a concise overview on highly specific biosynthetic pathways for CO(2)-fixation and, on the other hand, a summary of biodegradation (detoxification) processes involving enzymes which possess relaxed substrate specificities, which allow their application for the regioselective carboxylation of organic substrates to furnish the corresponding carboxylic acids (145 references).
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Affiliation(s)
- Silvia M Glueck
- Research Centre Applied Biocatalysis, University of Graz, Heinrichstrasse 28, A-8010 Graz, Austria
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45
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Whitney SM, Kane HJ, Houtz RL, Sharwood RE. Rubisco oligomers composed of linked small and large subunits assemble in tobacco plastids and have higher affinities for CO2 and O2. PLANT PHYSIOLOGY 2009; 149:1887-95. [PMID: 19233903 PMCID: PMC2663749 DOI: 10.1104/pp.109.135210] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2009] [Accepted: 02/15/2009] [Indexed: 05/19/2023]
Abstract
Manipulation of Rubisco within higher plants is complicated by the different genomic locations of the large (L; rbcL) and small (S; RbcS) subunit genes. Although rbcL can be accurately modified by plastome transformation, directed genetic manipulation of the multiple nuclear-encoded RbcS genes is more challenging. Here we demonstrate the viability of linking the S and L subunits of tobacco (Nicotiana tabacum) Rubisco using a flexible 40-amino acid tether. By replacing the rbcL in tobacco plastids with an artificial gene coding for a S40L fusion peptide, we found that the fusions readily assemble into catalytic (S40L)8 and (S40L)16 oligomers that are devoid of unlinked S subunits. While there was little or no change in CO2/O2 specificity or carboxylation rate of the Rubisco oligomers, their Kms for CO2 and O2 were reduced 10% to 20% and 45%, respectively. In young maturing leaves of the plastome transformants (called ANtS40L), the S40L-Rubisco levels were approximately 20% that of wild-type controls despite turnover of the S40L-Rubisco oligomers being only slightly enhanced relative to wild type. The reduced Rubisco content in ANtS40L leaves is partly attributed to problems with folding and assembly of the S40L peptides in tobacco plastids that relegate approximately 30% to 50% of the S40L pool to the insoluble protein fraction. Leaf CO2-assimilation rates in ANtS40L at varying pCO2 corresponded with the kinetics and reduced content of the Rubisco oligomers. This fusion strategy provides a novel platform to begin simultaneously engineering Rubisco L and S subunits in tobacco plastids.
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Affiliation(s)
- Spencer Michael Whitney
- Molecular Plant Physiology, Research School of Biological Sciences, Australian National University, Canberra, Australian Capital Territory 2601, Australia.
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46
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Tanaka A, Makino A. Photosynthetic research in plant science. PLANT & CELL PHYSIOLOGY 2009; 50:681-3. [PMID: 19376784 PMCID: PMC2669890 DOI: 10.1093/pcp/pcp040] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
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47
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Liggins JR, Gready JE. Putative functional role for the invariant aspartate 263 residue of Rhodospirillum rubrum Rubisco. Biochemistry 2009; 48:2226-36. [PMID: 19231887 DOI: 10.1021/bi802159e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Although aspartate residue D263 of Rhodospirillum rubrum Rubisco is close to the active site and invariant in all reported Rubiscos, its possible functional and structural roles in Rubisco activity have not been investigated. We have mutagenised D263 to several selected amino acids (asparagine, alanine, serine, glutamate, and glutamine) to probe possible roles in facilitating proton movements within the active site and maintaining structural positioning of key active-site groups. The mutants have been characterized by kinetic methods and by differential scanning calorimetry (DSC) to examine the effects of the substitutions on the stability of the folded state. We show that D263 is essential for maintaining effective levels of catalysis with the mutations reducing carboxylation variously by up to 100-fold but having less than 10% effect on the carboxylase/oxygenase specificity of the catalytic reaction. Removing the charge of the residue 263 side chain significantly strengthens binding of the activating (carbamylating) CO(2) molecule. In contrast, a charge on the 263 site has only a small influence on binding of the positively charged Mg(2+) ion, suggesting that the local protein structure provides different shielding of the formal charges on the Mg(2+) ion and the epsilon-lysine group of K191. Interestingly, introduction of an internal cavity (D263S and D263A) and insertion of an extra -CH(2)- group (D263E and D263Q) have opposite effects on catalysis, the former relatively small and the latter much larger, suggesting that the extra side-chain group induces a specific structural distortion that inhibits formation of the transition state. As the DSC results show that the mutations only slightly increase the kinetic stability of the folded state, we conclude that the rate-limiting (activated) step of unfolding involves substantial unfolding of the structure but not in the region of site 263. In summary, interaction of D263 with H287 of a largely electrostatic nature appears critical for maintaining correct positioning of catalytic groups in the active site. The conservation of D263 can thus be accounted for by its contribution to the maintenance of a finely tuned structure in this region abutting the active site.
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Affiliation(s)
- John R Liggins
- Molecular Plant Physiology Group, Research School of Biological Sciences, John Curtin School of Medical Research, Australian National University, Canberra ACT 0200, Australia
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48
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Saito Y, Ashida H, Sakiyama T, de Marsac NT, Danchin A, Sekowska A, Yokota A. Structural and functional similarities between a ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO)-like protein from Bacillus subtilis and photosynthetic RuBisCO. J Biol Chem 2009; 284:13256-64. [PMID: 19279009 DOI: 10.1074/jbc.m807095200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The sequences classified as genes for various ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase (RuBisCO)-like proteins (RLPs) are widely distributed among bacteria, archaea, and eukaryota. In the phylogenic tree constructed with these sequences, RuBisCOs and RLPs are grouped into four separate clades, forms I-IV. In RuBisCO enzymes encoded by form I, II, and III sequences, 19 conserved amino acid residues are essential for CO(2) fixation; however, 1-11 of these 19 residues are substituted with other amino acids in form IV RLPs. Among form IV RLPs, the only enzymatic activity detected to date is a 2,3-diketo-5-methylthiopentyl 1-phosphate (DK-MTP-1-P) enolase reaction catalyzed by Bacillus subtilis, Microcystis aeruginosa, and Geobacillus kaustophilus form IV RLPs. RLPs from Rhodospirillum rubrum, Rhodopseudomonas palustris, Chlorobium tepidum, and Bordetella bronchiseptica were inactive in the enolase reaction. DK-MTP-1-P enolase activity of B. subtilis RLP required Mg(2+) for catalysis and, like RuBisCO, was stimulated by CO(2). Four residues that are essential for the enolization reaction of RuBisCO, Lys(175), Lys(201), Asp(203), and Glu(204), were conserved in RLPs and were essential for DK-MTP-1-P enolase catalysis. Lys(123), the residue conserved in DK-MTP-1-P enolases, was also essential for B. subtilis RLP enolase activity. Similarities between the active site structures of RuBisCO and B. subtilis RLP were examined by analyzing the effects of structural analogs of RuBP on DK-MTP-1-P enolase activity. A transition state analog for the RuBP carboxylation of RuBisCO was a competitive inhibitor in the DK-MTP-1-P enolase reaction with a K(i) value of 103 mum. RuBP and d-phosphoglyceric acid, the substrate and product, respectively, of RuBisCO, were weaker competitive inhibitors. These results suggest that the amino acid residues utilized in the B. subtilis RLP enolase reaction are the same as those utilized in the RuBisCO RuBP enolization reaction.
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Affiliation(s)
- Yohtaro Saito
- Nara Institute of Science and Technology, Graduate School of Biological Sciences, Ikoma, Nara, Japan
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49
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Abstract
Despite recent elucidation of the three-dimensional structure of major photosynthetic complexes, our understanding of light energy conversion in plant chloroplasts and microalgae under physiological conditions requires exploring the dynamics of photosynthesis. The photosynthetic apparatus is a flexible molecular machine that can acclimate to metabolic and light fluctuations in a matter of seconds and minutes. On a longer time scale, changes in environmental cues trigger acclimation responses that elicit intracellular signaling between the nucleo-cytosol and chloroplast resulting in modification of the biogenesis of the photosynthetic machinery. Here we attempt to integrate well-established knowledge on the functional flexibility of light-harvesting and electron transfer processes, which has greatly benefited from genetic approaches, with data derived from the wealth of recent transcriptomic and proteomic studies of acclimation responses in photosynthetic eukaroytes.
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Affiliation(s)
- Stephan Eberhard
- Université Pierre et Marie Curie, Institut de Biologie Physico-Chimique, F-75005 Paris, France
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50
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Mueller-Cajar O, Whitney SM. Directing the evolution of Rubisco and Rubisco activase: first impressions of a new tool for photosynthesis research. PHOTOSYNTHESIS RESEARCH 2008; 98:667-75. [PMID: 18626786 PMCID: PMC2758363 DOI: 10.1007/s11120-008-9324-z] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2008] [Accepted: 06/26/2008] [Indexed: 05/18/2023]
Abstract
During the last decade the practice of laboratory-directed protein evolution has become firmly established as a versatile tool in biochemical research by enabling molecular evolution toward desirable phenotypes or detection of novel structure-function interactions. Applications of this technique in the field of photosynthesis research are still in their infancy, but recently first steps have been reported in the directed evolution of the CO(2)-fixing enzyme Rubisco and its helper protein Rubisco activase. Here we summarize directed protein evolution strategies and review the progressive advances that have been made to develop and apply suitable selection systems for screening mutant forms of these enzymes that improve the fitness of the host organism. The goal of increasing photosynthetic efficiency of plants by improving the kinetics of Rubisco has been a long-term goal scoring modest successes. We discuss how directed evolution methodologies may one day be able to circumvent the problems encountered during this venture.
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Affiliation(s)
- Oliver Mueller-Cajar
- Molecular Plant Physiology, Research School of Biological Sciences, Australian National University, P.O. Box 475, Canberra, Australian Capital Territory 2601 Australia
- Department of Cellular Biochemistry, Max-Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Spencer M. Whitney
- Molecular Plant Physiology, Research School of Biological Sciences, Australian National University, P.O. Box 475, Canberra, Australian Capital Territory 2601 Australia
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