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Wietrzynski W, Traverso E, Wollman FA, Wostrikoff K. The state of oligomerization of Rubisco controls the rate of synthesis of the Rubisco large subunit in Chlamydomonas reinhardtii. THE PLANT CELL 2021; 33:1706-1727. [PMID: 33625514 PMCID: PMC8254502 DOI: 10.1093/plcell/koab061] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 02/12/2021] [Indexed: 05/22/2023]
Abstract
Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) is present in all photosynthetic organisms and is a key enzyme for photosynthesis-driven life on Earth. Its most prominent form is a hetero-oligomer in which small subunits (SSU) stabilize the core of the enzyme built from large subunits (LSU), yielding, after a chaperone-assisted multistep assembly process, an LSU8SSU8 hexadecameric holoenzyme. Here we use Chlamydomonas reinhardtii and a combination of site-directed mutants to dissect the multistep biogenesis pathway of Rubisco in vivo. We identify assembly intermediates, in two of which LSU are associated with the RAF1 chaperone. Using genetic and biochemical approaches we further unravel a major regulation process during Rubisco biogenesis, in which LSU translation is controlled by its ability to assemble with the SSU, via the mechanism of control by epistasy of synthesis (CES). Altogether this leads us to propose a model whereby the last assembly intermediate, an LSU8-RAF1 complex, provides the platform for SSU binding to form the Rubisco enzyme, and when SSU is not available, converts to a key regulatory form that exerts negative feedback on the initiation of LSU translation.
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Affiliation(s)
- Wojciech Wietrzynski
- Sorbonne Université, CNRS, Institut de Biologie Physico-Chimique, Unité Mixte de Recherche 7141, 75005 Paris, France
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
- Helmholtz Pioneer Campus, Helmholtz Zentrum München, 85764 Neuherberg, Germany
| | - Eleonora Traverso
- Sorbonne Université, CNRS, Institut de Biologie Physico-Chimique, Unité Mixte de Recherche 7141, 75005 Paris, France
| | - Francis-André Wollman
- Sorbonne Université, CNRS, Institut de Biologie Physico-Chimique, Unité Mixte de Recherche 7141, 75005 Paris, France
| | - Katia Wostrikoff
- Sorbonne Université, CNRS, Institut de Biologie Physico-Chimique, Unité Mixte de Recherche 7141, 75005 Paris, France
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Dong Y, Gao M, Qiu W, Song Z. Effects of microplastic on arsenic accumulation in Chlamydomonas reinhardtii in a freshwater environment. JOURNAL OF HAZARDOUS MATERIALS 2021; 405:124232. [PMID: 33087286 DOI: 10.1016/j.jhazmat.2020.124232] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 10/05/2020] [Accepted: 10/07/2020] [Indexed: 06/11/2023]
Abstract
Chlamydomonas reinhardtii plays a critical role in the biogeochemical cycling of arsenic (As) and purification of water bodies contaminated with As. We investigated the effects of microplastic pollution on the ability of C. reinhardtii to accumulate As. We revealed that different sized [100 nm (S) and 5 µm (L)] polystyrene microplastics (PSMP) at different concentrations (50 and 100 mg L-1) interacted with the phospholipid structure in C. reinhardtii. Dispersion forces disrupted the structure and function of membrane proteins, reducing the accumulation and efflux of As(III) and inhibiting the As(V)-As(III)-MMA-DMA detoxification process in C. reinhardtii cells. The maximum As accumulation rates of C. reinhardtii in the control groups, L50, L100, S50, and S100 treatments were 53.71, 50.95, 48.42, 43.83, and 39.11 μg g-1 h-1, respectively. Further, PSMPs and As(III) triggered "oxidative bursts" in cells, damaging cell membranes and reducing chlorophyll content and Rubisco activity. As a result, photosynthesis, respiration, and growth were inhibited. When compared with an absence of PSMP, the addition of L- (S-) sized PSMP to the As-containing solution would result in a lower (higher) impact on C. reinhardtii. Overall, this study demonstrated that microplastics significantly affect As accumulation in C. reinhardtii. Our results indicate that the critical role of this algal species in As cycling in earth's pedo- and hydrosphere may be impeded by microplastic pollution.
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Affiliation(s)
- Youming Dong
- Agro-Environmental Protection Institute, Ministry of Agriculture of China, Tianjin 300191, China
| | - Minling Gao
- Department of Civil and Environmental Engineering, Shantou University, Shantou 515063, China
| | - Weiwen Qiu
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 4704, Christchurch 8140, New Zealand
| | - Zhengguo Song
- Department of Civil and Environmental Engineering, Shantou University, Shantou 515063, China.
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Comparative Proteomic Analysis on Fruit Ripening Processes in Two Varieties of Tropical Mango (Mangifera indica). Protein J 2019; 38:704-715. [DOI: 10.1007/s10930-019-09868-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Van Ruyskensvelde V, Van Breusegem F, Van Der Kelen K. Post-transcriptional regulation of the oxidative stress response in plants. Free Radic Biol Med 2018; 122:181-192. [PMID: 29496616 DOI: 10.1016/j.freeradbiomed.2018.02.032] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 02/22/2018] [Accepted: 02/23/2018] [Indexed: 12/30/2022]
Abstract
Due to their sessile lifestyle, plants can be exposed to several kinds of stresses that will increase the production of reactive oxygen species (ROS), such as hydrogen peroxide, singlet oxygen, and hydroxyl radicals, in the plant cells and activate several signaling pathways that cause alterations in the cellular metabolism. Nevertheless, when ROS production outreaches a certain level, oxidative damage to nucleic acids, lipids, metabolites, and proteins will occur, finally leading to cell death. Until now, the most comprehensive and detailed readout of oxidative stress responses is undoubtedly obtained at the transcriptome level. However, transcript levels often do not correlate with the corresponding protein levels. Indeed, together with transcriptional regulations, post-transcriptional, translational, and/or post-translational regulations will shape the active proteome. Here, we review the current knowledge on the post-transcriptional gene regulation during the oxidative stress responses in planta.
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Affiliation(s)
- Valerie Van Ruyskensvelde
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; Center for Plant Systems Biology, VIB, 9052 Ghent, Belgium
| | - Frank Van Breusegem
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; Center for Plant Systems Biology, VIB, 9052 Ghent, Belgium.
| | - Katrien Van Der Kelen
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; Center for Plant Systems Biology, VIB, 9052 Ghent, Belgium
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Zhan Y, Dhaliwal JS, Adjibade P, Uniacke J, Mazroui R, Zerges W. Localized control of oxidized RNA. J Cell Sci 2015; 128:4210-9. [PMID: 26449969 DOI: 10.1242/jcs.175232] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 09/23/2015] [Indexed: 12/23/2022] Open
Abstract
The oxidation of biological molecules by reactive oxygen species (ROS) can render them inactive or toxic. This includes the oxidation of RNA, which appears to underlie the detrimental effects of oxidative stress, aging and certain neurodegenerative diseases. Here, we investigate the management of oxidized RNA in the chloroplast of the green alga Chlamydomonas reinhardtii. Our immunofluorescence microscopy results reveal that oxidized RNA (with 8-hydroxyguanine) is localized in the pyrenoid, a chloroplast microcompartment where CO2 is assimilated by the Calvin cycle enzyme Rubisco. Results of genetic analyses support a requirement for the Rubisco large subunit (RBCL), but not Rubisco, in the management of oxidized RNA. An RBCL pool that can carry out such a 'moonlighting' function is revealed by results of biochemical fractionation experiments. We also show that human (HeLa) cells localize oxidized RNA to cytoplasmic foci that are distinct from stress granules, processing bodies and mitochondria. Our results suggest that the compartmentalization of oxidized RNA management is a general phenomenon and therefore has some fundamental significance.
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Affiliation(s)
- Yu Zhan
- Biology Department & Centre for Structural and Functional Genomics, Concordia University, 7141 Sherbrooke W, Montreal, Quebec, Canada H4B 1R6
| | - James S Dhaliwal
- Biology Department & Centre for Structural and Functional Genomics, Concordia University, 7141 Sherbrooke W, Montreal, Quebec, Canada H4B 1R6
| | - Pauline Adjibade
- Department of Molecular Biology, Medical Biochemistry, and Pathology, Laval University, Centre de Recherche le CHU de Quebec, Quebec, Canada G1V 4G2
| | - James Uniacke
- Biology Department & Centre for Structural and Functional Genomics, Concordia University, 7141 Sherbrooke W, Montreal, Quebec, Canada H4B 1R6
| | - Rachid Mazroui
- Department of Molecular Biology, Medical Biochemistry, and Pathology, Laval University, Centre de Recherche le CHU de Quebec, Quebec, Canada G1V 4G2
| | - William Zerges
- Biology Department & Centre for Structural and Functional Genomics, Concordia University, 7141 Sherbrooke W, Montreal, Quebec, Canada H4B 1R6
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Grabsztunowicz M, Górski Z, Luciński R, Jackowski G. A reversible decrease in ribulose 1,5-bisphosphate carboxylase/oxygenase carboxylation activity caused by the aggregation of the enzyme's large subunit is triggered in response to the exposure of moderate irradiance-grown plants to low irradiance. PHYSIOLOGIA PLANTARUM 2015; 154:591-608. [PMID: 25594504 DOI: 10.1111/ppl.12322] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 12/11/2014] [Accepted: 12/20/2014] [Indexed: 06/04/2023]
Abstract
Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is highly regulated in response to fluctuations in the environment, including changes in irradiance. However, no complex data are available on Rubisco regulatory mechanisms triggered in plants which are submitted to moderate-low irradiance shift. Therefore, we investigated in a comprehensive way the changes at the level of amount of Rubisco protein, its structural organization and carboxylase activity of the holoenzyme as triggered by exposure of moderate irradiance-grown Arabidopsis thaliana plants to low irradiance conditions. An exposure of moderate irradiance-grown plants to low irradiance for a single photoperiod caused the exclusion of a certain pool of Rubisco under altered conditions owing to oxidative modifications resulting in the formation of protein aggregates involving Rubisco large subunit (LS). As a result, both initial and total Rubisco carboxylase activities were reduced, whereas Rubisco activation state remained largely unchanged. The results of the determination of reactive oxygen species indicated that a moderate/low irradiance transition had stimulated (1) O2 accumulation and we strongly suggest that Rubisco oxidative modifications leading to formation of aggregates encompassing Rubisco-LS were triggered by (1) O2 . When moderate irradiance regime was resumed, the majority of Rubisco-LS containing aggregates tended to be resolubilized, and this allowed Rubisco carboxylation activities to be largely recovered, without changes in the activation state of the enzyme. In the longer term, these results allow us to better understand a complexity of Rubisco regulatory mechanisms activated in response to abiotic stresses and during recovery from the stresses.
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Affiliation(s)
- Magda Grabsztunowicz
- Department of Plant Physiology, Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University, Poznań, 61 614, Poland
| | - Zbigniew Górski
- Department of Physical Chemistry, Institute of Chemistry & Technical Electrochemistry, University of Technology, Poznań, 60 965, Poland
| | - Robert Luciński
- Department of Plant Physiology, Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University, Poznań, 61 614, Poland
| | - Grzegorz Jackowski
- Department of Plant Physiology, Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University, Poznań, 61 614, Poland
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Morisse S, Zaffagnini M, Gao XH, Lemaire SD, Marchand CH. Insight into protein S-nitrosylation in Chlamydomonas reinhardtii. Antioxid Redox Signal 2014; 21:1271-84. [PMID: 24328795 PMCID: PMC4158989 DOI: 10.1089/ars.2013.5632] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
AIMS Protein S-nitrosylation, a post-translational modification (PTM) consisting of the covalent binding of nitric oxide (NO) to a cysteine thiol moiety, plays a major role in cell signaling and is recognized to be involved in numerous physiological processes and diseases in mammals. The importance of nitrosylation in photosynthetic eukaryotes has been less studied. The aim of this study was to expand our knowledge on protein nitrosylation by performing a large-scale proteomic analysis of proteins undergoing nitrosylation in vivo in Chlamydomonas reinhardtii cells under nitrosative stress. RESULTS Using two complementary proteomic approaches, 492 nitrosylated proteins were identified. They participate in a wide range of biological processes and pathways, including photosynthesis, carbohydrate metabolism, amino acid metabolism, translation, protein folding or degradation, cell motility, and stress. Several proteins were confirmed in vitro by western blot, site-directed mutagenesis and activity measurements. Moreover, 392 sites of nitrosylation were also identified. These results strongly suggest that S-nitrosylation could constitute a major mechanism of regulation in C. reinhardtii under nitrosative stress conditions. INNOVATION This study constitutes the largest proteomic analysis of protein nitrosylation reported to date. CONCLUSION The identification of 381 previously unrecognized targets of nitrosylation further extends our knowledge on the importance of this PTM in photosynthetic eukaryotes. The data have been deposited to the ProteomeXchange repository with identifier PXD000569.
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Affiliation(s)
- Samuel Morisse
- 1 Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, FRE3354 Centre National de la Recherche Scientifique, Institut de Biologie Physico-Chimique, Université Pierre et Marie Curie , Paris, France
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Michelet L, Zaffagnini M, Morisse S, Sparla F, Pérez-Pérez ME, Francia F, Danon A, Marchand CH, Fermani S, Trost P, Lemaire SD. Redox regulation of the Calvin-Benson cycle: something old, something new. FRONTIERS IN PLANT SCIENCE 2013; 4:470. [PMID: 24324475 PMCID: PMC3838966 DOI: 10.3389/fpls.2013.00470] [Citation(s) in RCA: 266] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 10/30/2013] [Indexed: 05/18/2023]
Abstract
Reversible redox post-translational modifications such as oxido-reduction of disulfide bonds, S-nitrosylation, and S-glutathionylation, play a prominent role in the regulation of cell metabolism and signaling in all organisms. These modifications are mainly controlled by members of the thioredoxin and glutaredoxin families. Early studies in photosynthetic organisms have identified the Calvin-Benson cycle, the photosynthetic pathway responsible for carbon assimilation, as a redox regulated process. Indeed, 4 out of 11 enzymes of the cycle were shown to have a low activity in the dark and to be activated in the light through thioredoxin-dependent reduction of regulatory disulfide bonds. The underlying molecular mechanisms were extensively studied at the biochemical and structural level. Unexpectedly, recent biochemical and proteomic studies have suggested that all enzymes of the cycle and several associated regulatory proteins may undergo redox regulation through multiple redox post-translational modifications including glutathionylation and nitrosylation. The aim of this review is to detail the well-established mechanisms of redox regulation of Calvin-Benson cycle enzymes as well as the most recent reports indicating that this pathway is tightly controlled by multiple interconnected redox post-translational modifications. This redox control is likely allowing fine tuning of the Calvin-Benson cycle required for adaptation to varying environmental conditions, especially during responses to biotic and abiotic stresses.
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Affiliation(s)
- Laure Michelet
- Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, FRE3354 Centre National de la Recherche Scientifique, Institut de Biologie Physico-Chimique, Université Pierre et Marie CurieParis, France
| | - Mirko Zaffagnini
- Laboratory of Plant Redox Biology, Department of Pharmacy and Biotechnology (FaBiT), University of BolognaBologna, Italy
| | - Samuel Morisse
- Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, FRE3354 Centre National de la Recherche Scientifique, Institut de Biologie Physico-Chimique, Université Pierre et Marie CurieParis, France
| | - Francesca Sparla
- Laboratory of Plant Redox Biology, Department of Pharmacy and Biotechnology (FaBiT), University of BolognaBologna, Italy
| | - María Esther Pérez-Pérez
- Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, FRE3354 Centre National de la Recherche Scientifique, Institut de Biologie Physico-Chimique, Université Pierre et Marie CurieParis, France
| | - Francesco Francia
- Laboratory of Plant Redox Biology, Department of Pharmacy and Biotechnology (FaBiT), University of BolognaBologna, Italy
| | - Antoine Danon
- Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, FRE3354 Centre National de la Recherche Scientifique, Institut de Biologie Physico-Chimique, Université Pierre et Marie CurieParis, France
| | - Christophe H. Marchand
- Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, FRE3354 Centre National de la Recherche Scientifique, Institut de Biologie Physico-Chimique, Université Pierre et Marie CurieParis, France
| | - Simona Fermani
- Department of Chemistry “G. Ciamician”, University of BolognaBologna, Italy
| | - Paolo Trost
- Laboratory of Plant Redox Biology, Department of Pharmacy and Biotechnology (FaBiT), University of BolognaBologna, Italy
| | - Stéphane D. Lemaire
- Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, FRE3354 Centre National de la Recherche Scientifique, Institut de Biologie Physico-Chimique, Université Pierre et Marie CurieParis, France
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Gigova L, Ivanova N, Gacheva G, Andreeva R, Furnadzhieva S. RESPONSE OF TRACHYDISCUS MINUTUS (XANTHOPHYCEAE) TO TEMPERATURE AND LIGHT(1). JOURNAL OF PHYCOLOGY 2012; 48:85-93. [PMID: 27009653 DOI: 10.1111/j.1529-8817.2011.01088.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The effects of different temperatures and light intensities on growth, pigments, sugars, lipids, and proteins, as well as on some antioxidant and proteolytic enzymes of Trachydiscus minutus (Bourr.) H. Ettl, were investigated. The optimum growth temperature and light intensity were 25°C and 2 × 132 μmol photons · m(-2 ) · s(-1) , respectively. Under these conditions, proteins were the main biomass components (33.45% dry weight [dwt]), with high levels of carbohydrates (29% dwt) and lipids (21.77% dwt). T. minutus tolerated temperatures between 20°C and 32°C, with only moderate changes in cell growth and biochemical composition. Extremely low (15°C) and high (40°C) temperatures decreased chl and RUBISCO contents and inhibited cell growth. The biochemical response of the alga to both unfavorable conditions was an increase in lipid content (up to 35.19% dwt) and a decrease in carbohydrates (down to 13.64% dwt) with much less of a change in total protein content (in the range of 30.51%-38.13% dwt). At the same time, the defense system of T. minutus was regulated differently in response to heat or cold treatments. Generally, at 40°C, the activities of superoxide dismutase (SOD), catalase (CAT), and proteases were drastically elevated, and three polypeptides were overexpressed, whereas the glutathione reductase (GR) and peroxidase (POD) activities were reduced. In contrast, at 15°C, all these enzymes except GR were suppressed. The effect of light was to enhance or decrease the temperature stress responses, depending on intensity. Our studies demonstrate the broad temperature adaptability of T. minutus as well as the potential for the production of valuable algal biomass.
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Affiliation(s)
- Liliana Gigova
- Institute of Plant Physiology and Genetics, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Natalia Ivanova
- Institute of Plant Physiology and Genetics, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Gergana Gacheva
- Institute of Plant Physiology and Genetics, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Raina Andreeva
- Institute of Plant Physiology and Genetics, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Sevdalina Furnadzhieva
- Institute of Plant Physiology and Genetics, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
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Uniacke J, Zerges W. Stress induces the assembly of RNA granules in the chloroplast of Chlamydomonas reinhardtii. ACTA ACUST UNITED AC 2008; 182:641-6. [PMID: 18710928 PMCID: PMC2518703 DOI: 10.1083/jcb.200805125] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Eukaryotic cells under stress repress translation and localize these messenger RNAs (mRNAs) to cytoplasmic RNA granules. We show that specific stress stimuli induce the assembly of RNA granules in an organelle with bacterial ancestry, the chloroplast of Chlamydomonas reinhardtii. These chloroplast stress granules (cpSGs) form during oxidative stress and disassemble during recovery from stress. Like mammalian stress granules, cpSGs contain poly(A)-binding protein and the small, but not the large, ribosomal subunit. In addition, mRNAs are in continuous flux between polysomes and cpSGs during stress. Localization of cpSGs within the pyrenoid reveals that this chloroplast compartment functions in this stress response. The large subunit of ribulosebisphosphate carboxylase/oxygenase also assembles into cpSGs and is known to bind mRNAs during oxidative stress, raising the possibility that it plays a role in cpSG assembly. This discovery within such an organelle suggests that mRNA localization to granules during stress is a more general phenomenon than currently realized.
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Affiliation(s)
- James Uniacke
- Biology Department, Concordia University, Montreal, Quebec, Canada
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Marín-Navarro J, Moreno J. Cysteines 449 and 459 modulate the reduction-oxidation conformational changes of ribulose 1.5-bisphosphate carboxylase/oxygenase and the translocation of the enzyme to membranes during stress. PLANT, CELL & ENVIRONMENT 2006; 29:898-908. [PMID: 17087473 DOI: 10.1111/j.1365-3040.2005.01469.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The role of cysteines 449 (Cys449) and 459 (Cys459) from the large subunit (LS) of ribulose 1-5-bisphosphate carboxylase/oxygenase (Rubisco) in the reduction-oxidation (redox) regulation of the enzyme was assessed by site-directed mutagenesis of these residues and chloroplast transformation of Chlamydomonas reinhardtii. In vitro studies indicated that mutations C449S, C459S or C449S/ C459S do not affect the activity and proteolytic susceptibility of the enzyme in the reduced state. However, when oxidized, the mutant enzymes differed from the wild type (WT), showing an increased resistance to inactivation and, in the case of the double mutant (DM), an altered structural conformation as reflected by the kinetics of proteolysis with subtilisin. The response of the DM strain to saline stress revealed that the absence of Cys449 and Cys459 intensifies Rubisco degradation and the covalent disulfide and non-disulfide polymerization of the enzyme in vivo. Saline stress also induced Rubisco translocation to a membrane (M) fraction that contained only covalently polymerized enzyme. Rubisco mobilization to this M fraction was enhanced also in the DM strain. Altogether, these results indicate that Cys449 and Cys459 participate in the modulation of the conformational changes promoted by oxidative modifications retarding processes related to the catabolism of the enzyme in vivo.
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Affiliation(s)
- Julia Marín-Navarro
- Departament de Bioquimica i Biologia Molecular, Universitat de València, Dr Moliner 50, Burjassot E46100, Spain
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