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Dey D, Tanaka R, Ito H. Structural Characterization of the Chlorophyllide a Oxygenase (CAO) Enzyme Through an In Silico Approach. J Mol Evol 2023; 91:225-235. [PMID: 36869271 DOI: 10.1007/s00239-023-10100-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 02/16/2023] [Indexed: 03/05/2023]
Abstract
Chlorophyllide a oxygenase (CAO) is responsible for converting chlorophyll a to chlorophyll b in a two-step oxygenation reaction. CAO belongs to the family of Rieske-mononuclear iron oxygenases. Although the structure and reaction mechanism of other Rieske monooxygenases have been described, a member of plant Rieske non-heme iron-dependent monooxygenase has not been structurally characterized. The enzymes in this family usually form a trimeric structure and electrons are transferred between the non-heme iron site and the Rieske center of the adjoining subunits. CAO is supposed to form a similar structural arrangement. However, in Mamiellales such as Micromonas and Ostreococcus, CAO is encoded by two genes where non-heme iron site and Rieske cluster localize on the distinct polypeptides. It is not clear if they can form a similar structural organization to achieve the enzymatic activity. In this study, the tertiary structures of CAO from the model plant Arabidopsis thaliana and the Prasinophyte Micromonas pusilla were predicted by deep learning-based methods, followed by energy minimization and subsequent stereochemical quality assessment of the predicted models. Furthermore, the chlorophyll a binding cavity and the interaction of ferredoxin, which is the electron donor, on the surface of Micromonas CAO were predicted. The electron transfer pathway was predicted in Micromonas CAO and the overall structure of the CAO active site was conserved even though it forms a heterodimeric complex. The structures presented in this study will serve as a basis for understanding the reaction mechanism and regulation of the plant monooxygenase family to which CAO belongs.
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Affiliation(s)
- Debayan Dey
- Graduate School of Life Science, Hokkaido University, N10 W8, Sapporo, 060-0810, Japan
- Institute of Low Temperature Science, Hokkaido University, N19 W8, Sapporo, 060-0819, Japan
| | - Ryouichi Tanaka
- Institute of Low Temperature Science, Hokkaido University, N19 W8, Sapporo, 060-0819, Japan
| | - Hisashi Ito
- Institute of Low Temperature Science, Hokkaido University, N19 W8, Sapporo, 060-0819, Japan.
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2
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Bai WP, Li HJ, Hepworth SR, Liu HS, Liu LB, Wang GN, Ma Q, Bao AK, Wang SM. Physiological and transcriptomic analyses provide insight into thermotolerance in desert plant Zygophyllum xanthoxylum. BMC PLANT BIOLOGY 2023; 23:7. [PMID: 36600201 PMCID: PMC9814312 DOI: 10.1186/s12870-022-04024-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 12/22/2022] [Indexed: 05/25/2023]
Abstract
BACKGROUND Heat stress has adverse effects on the growth and reproduction of plants. Zygophyllum xanthoxylum, a typical xerophyte, is a dominant species in the desert where summer temperatures are around 40 °C. However, the mechanism underlying the thermotolerance of Z. xanthoxylum remained unclear. RESULTS Here, we characterized the acclimation of Z. xanthoxylum to heat using a combination of physiological measurements and transcriptional profiles under treatments at 40 °C and 45 °C, respectively. Strikingly, moderate high temperature (40 °C) led to an increase in photosynthetic capacity and superior plant performance, whereas severe high temperature (45 °C) was accompanied by reduced photosynthetic capacity and inhibited growth. Transcriptome profiling indicated that the differentially expressed genes (DEGs) were related to transcription factor activity, protein folding and photosynthesis under heat conditions. Furthermore, numerous genes encoding heat transcription shock factors (HSFs) and heat shock proteins (HSPs) were significantly up-regulated under heat treatments, which were correlated with thermotolerance of Z. xanthoxylum. Interestingly, the up-regulation of PSI and PSII genes and the down-regulation of chlorophyll catabolism genes likely contribute to improving plant performance of Z. xanthoxylum under moderate high temperature. CONCLUSIONS We identified key genes associated with of thermotolerance and growth in Z. xanthoxylum, which provide significant insights into the regulatory mechanisms of thermotolerance and growth regulation in Z. xanthoxylum under high temperature conditions.
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Affiliation(s)
- Wan-Peng Bai
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems; College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, People's Republic of China
| | - Hu-Jun Li
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems; College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, People's Republic of China
| | - Shelley R Hepworth
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems; College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, People's Republic of China
- Department of Biology, Institute of Biochemistry, Carleton University, Ottawa, ON, Canada
| | - Hai-Shuang Liu
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems; College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, People's Republic of China
| | - Lin-Bo Liu
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems; College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, People's Republic of China
| | - Gai-Ni Wang
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems; College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, People's Republic of China
| | - Qing Ma
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems; College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, People's Republic of China
| | - Ai-Ke Bao
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems; College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, People's Republic of China
| | - Suo-Min Wang
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems; College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, People's Republic of China.
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Liu J, Knapp M, Jo M, Dill Z, Bridwell-Rabb J. Rieske Oxygenase Catalyzed C-H Bond Functionalization Reactions in Chlorophyll b Biosynthesis. ACS CENTRAL SCIENCE 2022; 8:1393-1403. [PMID: 36313167 PMCID: PMC9615114 DOI: 10.1021/acscentsci.2c00058] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Indexed: 05/03/2023]
Abstract
Rieske oxygenases perform precise C-H bond functionalization reactions in anabolic and catabolic pathways. These reactions are typically characterized as monooxygenation or dioxygenation reactions, but other divergent reactions are also catalyzed by Rieske oxygenases. Chlorophyll(ide) a oxygenase (CAO), for example is proposed to catalyze two monooxygenation reactions to transform a methyl-group into the formyl-group of Chlorophyll b. This formyl group, like the formyl groups found in other chlorophyll pigments, tunes the absorption spectra of chlorophyllb and supports the ability of several photosynthetic organisms to adapt to environmental light. Despite the importance of this reaction, CAO has never been studied in vitro with purified protein, leaving many open questions regarding whether CAO can facilitate both oxygenation reactions using just the Rieske oxygenase machinery. In this study, we demonstrated that four CAO homologues in partnership with a non-native reductase convert a Chlorophyll a precursor, chlorophyllidea, into chlorophyllideb in vitro. Analysis of this reaction confirmed the existence of the proposed intermediate, highlighted the stereospecificity of the reaction, and revealed the potential of CAO as a tool for synthesizing custom-tuned natural and unnatural chlorophyll pigments. This work thus adds to our fundamental understanding of chlorophyll biosynthesis and Rieske oxygenase chemistry.
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Wang J, Li X, Chang JW, Ye T, Mao Y, Wang X, Liu L. Enzymological and structural characterization of Arabidopsis thaliana heme oxygenase-1. FEBS Open Bio 2022; 12:1677-1687. [PMID: 35689519 PMCID: PMC9433822 DOI: 10.1002/2211-5463.13453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 06/06/2022] [Accepted: 06/09/2022] [Indexed: 11/10/2022] Open
Abstract
Arabidopsis thaliana heme oxygenase‐1 (AtHO‐1), a metabolic enzyme in the heme degradation pathway, serves as a prototype for study of the bilin‐related functions in plants. Past biological analyses revealed that AtHO‐1 requires ferredoxin‐NADP+ reductase (FNR) and ferredoxin for its enzymatic activity. Here, we characterized the binding and degradation of heme by AtHO‐1, and found that ferredoxin is a dispensable component of the reducing system that provides electrons for heme oxidation. Furthermore, we reported the crystal structure of heme‐bound AtHO‐1, which demonstrates both conserved and previously undescribed features of plant heme oxygenases. Finally, the electron transfer pathway from FNR to AtHO‐1 is suggested based on the known structural information.
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Affiliation(s)
- Jia Wang
- School of Life Sciences, Anhui University, Hefei, China
| | - Xiaoyi Li
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | | | - Tong Ye
- School of Life Sciences, Anhui University, Hefei, China
| | - Ying Mao
- School of Life Sciences, Anhui University, Hefei, China
| | - Xiao Wang
- School of Life Sciences, Anhui University, Hefei, China
| | - Lin Liu
- School of Life Sciences, Anhui University, Hefei, China
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5
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Dey D, Dhar D, Fortunato H, Obata D, Tanaka A, Tanaka R, Basu S, Ito H. Insights into the structure and function of the rate-limiting enzyme of chlorophyll degradation through analysis of a bacterial Mg-dechelatase homolog. Comput Struct Biotechnol J 2021; 19:5333-5347. [PMID: 34745453 PMCID: PMC8531759 DOI: 10.1016/j.csbj.2021.09.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Revised: 09/20/2021] [Accepted: 09/21/2021] [Indexed: 12/13/2022] Open
Abstract
The Mg-dechelatase enzyme encoded by the Stay-Green (SGR) gene catalyzes Mg2+ dechelation from chlorophyll a. This reaction is the first committed step of chlorophyll degradation pathway in plants and is thus indispensable for the process of leaf senescence. There is no structural information available for this or its related enzymes. This study aims to provide insights into the structure and reaction mechanism of the enzyme through biochemical and computational analysis of an SGR homolog from the Chloroflexi Anaerolineae (AbSGR-h). Recombinant AbSGR-h with its intact sequence and those with mutations were overexpressed in Escherichia coli and their Mg-dechelatase activity were compared. Two aspartates - D34 and D62 were found to be essential for catalysis, while R26, Y28, T29 and D114 were responsible for structural maintenance. Gel filtration analysis of the recombinant AbSGR-h indicates that it forms a homo-oligomer. The three-dimensional structure of AbSGR-h was predicted by a deep learning-based method, which was evaluated by protein structure quality evaluation programs while structural stability of wild-type and mutant forms were investigated through molecular dynamics simulations. Furthermore, in concordance with the results of enzyme assay, molecular docking concluded the significance of D34 in ligand interaction. By combining biochemical analysis and computational prediction, this study unveils the detailed structural characteristics of the enzyme, including the probable pocket of interaction and the residues of structural and functional importance. It also serves as a basis for further studies on Mg-dechelatase such as elucidation of its reaction mechanism or inhibitor screening.
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Affiliation(s)
- Debayan Dey
- Graduate School of Life Science, Hokkaido University, Sapporo 060-0810, Japan.,Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan
| | - Dipanjana Dhar
- Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan.,Department of Natural History Sciences, Hokkaido University, Sapporo 060-0810, Japan
| | - Helena Fortunato
- Department of Natural History Sciences, Hokkaido University, Sapporo 060-0810, Japan
| | - Daichi Obata
- Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan
| | - Ayumi Tanaka
- Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan
| | - Ryouichi Tanaka
- Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan
| | - Soumalee Basu
- Department of Microbiology, University of Calcutta, Kolkata 700019, India
| | - Hisashi Ito
- Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan
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Eggers R, Jammer A, Jha S, Kerschbaumer B, Lahham M, Strandback E, Toplak M, Wallner S, Winkler A, Macheroux P. The scope of flavin-dependent reactions and processes in the model plant Arabidopsis thaliana. PHYTOCHEMISTRY 2021; 189:112822. [PMID: 34118767 DOI: 10.1016/j.phytochem.2021.112822] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 05/23/2021] [Accepted: 05/24/2021] [Indexed: 06/12/2023]
Abstract
Flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) are utilized as coenzymes in many biochemical reduction-oxidation reactions owing to the ability of the tricyclic isoalloxazine ring system to employ the oxidized, radical and reduced state. We have analyzed the genome of Arabidopsis thaliana to establish an inventory of genes encoding flavin-dependent enzymes (flavoenzymes) as a basis to explore the range of flavin-dependent biochemical reactions that occur in this model plant. Expectedly, flavoenzymes catalyze many pivotal reactions in primary catabolism, which are connected to the degradation of basic metabolites, such as fatty and amino acids as well as carbohydrates and purines. On the other hand, flavoenzymes play diverse roles in anabolic reactions most notably the biosynthesis of amino acids as well as the biosynthesis of pyrimidines and sterols. Importantly, the role of flavoenzymes goes much beyond these basic reactions and extends into pathways that are equally crucial for plant life, for example the production of natural products. In this context, we outline the participation of flavoenzymes in the biosynthesis and maintenance of cofactors, coenzymes and accessory plant pigments (e. g. carotenoids) as well as phytohormones. Moreover, several multigene families have emerged as important components of plant immunity, for example the family of berberine bridge enzyme-like enzymes, flavin-dependent monooxygenases and NADPH oxidases. Furthermore, the versatility of flavoenzymes is highlighted by their role in reactions leading to tRNA-modifications, chromatin regulation and cellular redox homeostasis. The favorable photochemical properties of the flavin chromophore are exploited by photoreceptors to govern crucial processes of plant adaptation and development. Finally, a sequence- and structure-based approach was undertaken to gain insight into the catalytic role of uncharacterized flavoenzymes indicating their involvement in unknown biochemical reactions and pathways in A. thaliana.
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Affiliation(s)
- Reinmar Eggers
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, 8010, Graz, Austria
| | - Alexandra Jammer
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, 8010, Graz, Austria
| | - Shalinee Jha
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, 8010, Graz, Austria
| | - Bianca Kerschbaumer
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, 8010, Graz, Austria
| | - Majd Lahham
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, 8010, Graz, Austria
| | - Emilia Strandback
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, 8010, Graz, Austria
| | - Marina Toplak
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, 8010, Graz, Austria
| | - Silvia Wallner
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, 8010, Graz, Austria
| | - Andreas Winkler
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, 8010, Graz, Austria
| | - Peter Macheroux
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, 8010, Graz, Austria.
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Liu W, Chen G, Chen J, Jahan MS, Guo S, Wang Y, Sun J. Overexpression of 7-hydroxymethyl Chlorophyll a Reductase from Cucumber in Tobacco Accelerates Dark-Induced Chlorophyll Degradation. PLANTS (BASEL, SWITZERLAND) 2021; 10:plants10091820. [PMID: 34579353 PMCID: PMC8465020 DOI: 10.3390/plants10091820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 08/28/2021] [Accepted: 08/30/2021] [Indexed: 05/09/2023]
Abstract
7-hydroxymethyl chlorophyll (Chl) a reductase (HCAR) plays critical roles in the Chl cycle and degradation during leaf senescence, however, its function in horticultural crops remains unknown. Here, we identified an HCAR gene (CsHCAR) from cucumber (Cucumis sativus L.) and investigated its roles in response to dark-induced Chl degradation. CsHCAR encoded 459 amino acids, which were orthologous to Arabidopsis HCAR, had the conserved domains, and localized in the chloroplast. Gene expression analysis showed that CsHCAR expression was the highest in senescent leaves and was responsive to different stresses and phytohormone treatments. Overexpression of CsHCAR in tobacco accelerated dark-induced Chl degradation through enhancing the expression of Chl catabolic genes. After 10 d of darkness treatment, the biomass of CsHCAR overexpression plants was reduced. Furthermore, the value of net photosynthetic rate, maximum quantum yield of photosystem II, and effective quantum yield of photosystem II in CsHCAR overexpression plants was significantly reduced in comparison to that in wild-type (WT) plants. The photosynthetic protein content, including Lhcb1, Lhcb2, Lhcb4, RbcS, and RbcL in CsHCAR overexpression plants exhibited a lower level as compared to that observed in WT plants. In addition, the expression of genes encoding these proteins in CsHCAR overexpression plants was significantly lower than that in WT plants. Moreover, CsHCAR overexpression plants inhibited the dark-induced accumulation of reactive oxygen species (ROS). These results indicate that CsHCAR affects the stability of photosynthetic proteins in chloroplasts, positively regulates Chl degradation, and plays an important role in maintaining ROS homeostasis in leaves.
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Affiliation(s)
| | | | | | | | | | - Yu Wang
- Correspondence: (Y.W.); (J.S.)
| | - Jin Sun
- Correspondence: (Y.W.); (J.S.)
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8
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A Synthetic Cytokinin Improves Photosynthesis in Rice under Drought Stress by Modulating the Abundance of Proteins Related to Stomatal Conductance, Chlorophyll Contents, and Rubisco Activity. PLANTS 2020; 9:plants9091106. [PMID: 32867335 PMCID: PMC7569833 DOI: 10.3390/plants9091106] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 08/21/2020] [Accepted: 08/24/2020] [Indexed: 02/07/2023]
Abstract
Drought susceptible rice cultivar PTT1 (Pathumthani1) was treated with drought (-72 kPa) and CPPU (N-2-(chloro-4-pyridyl)-N-phenyl urea) @ 5 mg/L at tillering and grain-filling stages. Plants were tested for the effect of synthetic cytokinin on the parameters influencing the process of photosynthesis. Exogenous spray of CPPU improved the stomatal conductance of rice leaves, which was severely reduced by drought. The abundance intensities of proteins, associated with the stomatal conductance (ZEP, NCED4, PYL9, PYL10, ABI5, SnRK4, Phot1, and Phot2), were also in agreement with the positive impact of CPPU on the stomatal conductance under drought stress. Among the photosynthetic pigments, Chl b contents were significantly reduced by drought stress, whereas CPPU treated plants retained the normal contents of Chl b under drought stress. Subsequently, we examined the abundance intensities of chlorophyll synthase and HCR proteins, implicated in the biosynthesis of chlorophyll pigments and the conversion of Chl b to Chl a, respectively. The results indicated a drought-mediated suppression of chlorophyll synthase. However, CPPU treated plants retained normal levels of chlorophyll synthase under drought stress. In addition, drought stress induced HCR proteins, which might be the cause for reduced Chl b contents in drought stressed plants. Further, CPPU treatment helped the plants sustain photosynthesis at a normal rate under drought stress, which was comparable with well-watered plants. The results were further confirmed by examining the abundance intensities of two key proteins, RAF1 and Rubisco activase, implicated in the assembly and activation of Rubisco, respectively. CPPU treatment reversed the drought mediated suppression of these proteins at both of the growth stages of rice under drought stress. Based on the results, it can be suggested that synthetic cytokinins help the plants sustain photosynthesis at a normal rate under drought stress by positively influencing the determinants of photosynthesis at a molecular level.
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Wang J, Guo Q, Liu L, Wang X. Crystal structure of Arabidopsis thaliana cytidine deaminase. Biochem Biophys Res Commun 2020; 529:659-665. [PMID: 32736689 DOI: 10.1016/j.bbrc.2020.06.084] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 06/17/2020] [Indexed: 11/19/2022]
Abstract
Cytidine deaminase (CDA) catalyzes the (deoxy)cytidine deamination to (deoxy)uridine, which involves in the catabolic and salvage pathways of pyrimidine nucleotides in plants. CDA serves as a prototype of the cytidine deaminase superfamily that contains a number of RNA editing enzymes. Arabidopsis thaliana has only one functional CDA, AtCDA1. We solved the crystal structures of AtCDA1, which is a dimeric zinc-containing enzyme and each protomer consists of an N-terminal zinc-binding catalytic domain and a C-terminal non-catalytic domain. Both domains adopt a typical α/β/α sandwich fold. In vitro biochemical assays showed that the ribose moiety of cytidine is required for ligand binding, and structural analyses revealed a conserved catalytic mechanism is adopted by AtCDA1.
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Affiliation(s)
- Jia Wang
- CAS Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Haidian, Beijing, 100093, China; Graduate School, University of Chinese Academy of Sciences, Shijingshan, Beijing, 100049, China
| | - Qi Guo
- CAS Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Haidian, Beijing, 100093, China; Graduate School, University of Chinese Academy of Sciences, Shijingshan, Beijing, 100049, China
| | - Lin Liu
- School of Life Sciences, Anhui University, Hefei, Anhui, 230601, China
| | - Xiao Wang
- School of Life Sciences, Anhui University, Hefei, Anhui, 230601, China.
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Abstract
Two cytochrome P450 enzymes, CYP97A3 and CYP97C1, catalyze hydroxylations of the β- and ε-rings of α-carotene to produce lutein. Chirality is introduced at the C-3 atom of both rings, and the reactions are both pro-3R-stereospecific. We determined the crystal structures of CYP97A3 in substrate-free and complex forms with a nonnatural substrate and the structure of CYP97C1 in a detergent-bound form. The structures of CYP97A3 in different states show the substrate channel and the structure of CYP97C1 bound with octylthioglucoside confirms the binding site for the carotenoid substrate. Biochemical assays confirm that the ferredoxin-NADP+ reductase (FNR)-ferredoxin pair is used as the redox partner. Details of the pro-3R stereospecificity are revealed in the retinal-bound CYP97A3 structure. Further analysis indicates that the CYP97B clan bears similarity to the β-ring-specific CYP97A clan. Overall, our research describes the molecular basis for the last steps of lutein biosynthesis.
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11
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Przybyla-Toscano J, Roland M, Gaymard F, Couturier J, Rouhier N. Roles and maturation of iron-sulfur proteins in plastids. J Biol Inorg Chem 2018; 23:545-566. [PMID: 29349662 PMCID: PMC6006212 DOI: 10.1007/s00775-018-1532-1] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 12/14/2017] [Indexed: 12/28/2022]
Abstract
One reason why iron is an essential element for most organisms is its presence in prosthetic groups such as hemes or iron–sulfur (Fe–S) clusters, which are notably required for electron transfer reactions. As an organelle with an intense metabolism in plants, chloroplast relies on many Fe–S proteins. This includes those present in the electron transfer chain which will be, in fact, essential for most other metabolic processes occurring in chloroplasts, e.g., carbon fixation, nitrogen and sulfur assimilation, pigment, amino acid, and vitamin biosynthetic pathways to cite only a few examples. The maturation of these Fe–S proteins requires a complex and specific machinery named SUF (sulfur mobilisation). The assembly process can be split in two major steps, (1) the de novo assembly on scaffold proteins which requires ATP, iron and sulfur atoms, electrons, and thus the concerted action of several proteins forming early acting assembly complexes, and (2) the transfer of the preformed Fe–S cluster to client proteins using a set of late-acting maturation factors. Similar machineries, having in common these basic principles, are present in the cytosol and in mitochondria. This review focuses on the currently known molecular details concerning the assembly and roles of Fe–S proteins in plastids.
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Affiliation(s)
- Jonathan Przybyla-Toscano
- Université de Lorraine, Interactions Arbres-Microorganismes, UMR1136, 54500, Vandoeuvre-lès-Nancy, France
| | - Mélanie Roland
- Université de Lorraine, Interactions Arbres-Microorganismes, UMR1136, 54500, Vandoeuvre-lès-Nancy, France
| | - Frédéric Gaymard
- Biochimie et Physiologie Moléculaire des Plantes, CNRS/INRA/Université Montpellier 2, SupAgro Campus, 34060, Montpellier, France
| | - Jérémy Couturier
- Université de Lorraine, Interactions Arbres-Microorganismes, UMR1136, 54500, Vandoeuvre-lès-Nancy, France
| | - Nicolas Rouhier
- Université de Lorraine, Interactions Arbres-Microorganismes, UMR1136, 54500, Vandoeuvre-lès-Nancy, France.
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Synthesis of 7-substituted chlorophyll- a derivatives as chlorophyll- b analogs with specific visible absorption bands. Tetrahedron 2018. [DOI: 10.1016/j.tet.2017.12.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Piao W, Han SH, Sakuraba Y, Paek NC. Rice 7-Hydroxymethyl Chlorophyll a Reductase Is Involved in the Promotion of Chlorophyll Degradation and Modulates Cell Death Signaling. Mol Cells 2017; 40:773-786. [PMID: 29047257 PMCID: PMC5682254 DOI: 10.14348/molcells.2017.0127] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Revised: 08/10/2017] [Accepted: 08/23/2017] [Indexed: 11/30/2022] Open
Abstract
The loss of green coloration via chlorophyll (Chl) degradation typically occurs during leaf senescence. To date, many Chl catabolic enzymes have been identified and shown to interact with light harvesting complex II to form a Chl degradation complex in senescing chloroplasts; this complex might metabolically channel phototoxic Chl catabolic intermediates to prevent oxidative damage to cells. The Chl catabolic enzyme 7-hydroxymethyl Chl a reductase (HCAR) converts 7-hydroxymethyl Chl a (7-HMC a) to Chl a. The rice (Oryza sativa) genome contains a single HCAR homolog (OsHCAR), but its exact role remains unknown. Here, we show that an oshcar knockout mutant exhibits persistent green leaves during both dark-induced and natural senescence, and accumulates 7-HMC a and pheophorbide a (Pheo a) in green leaf blades. Interestingly, both rice and Arabidopsis hcar mutants exhibit severe cell death at the vegetative stage; this cell death largely occurs in a light intensity-dependent manner. In addition, 7-HMC a treatment led to the generation of singlet oxygen (1O2) in Arabidopsis and rice protoplasts in the light. Under herbicide-induced oxidative stress conditions, leaf necrosis was more severe in hcar plants than in wild type, and HCAR-overexpressing plants were more tolerant to reactive oxygen species than wild type. Therefore, in addition to functioning in the conversion of 7-HMC a to Chl a in senescent leaves, HCAR may play a critical role in protecting plants from high light-induced damage by preventing the accumulation of 7-HMC a and Pheo a in developing and mature leaves at the vegetative stage.
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Affiliation(s)
- Weilan Piao
- Department of Plant Science, Plant Genomics and Breeding Institute, and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826,
Korea
| | - Su-Hyun Han
- Department of Plant Science, Plant Genomics and Breeding Institute, and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826,
Korea
| | - Yasuhito Sakuraba
- Department of Plant Science, Plant Genomics and Breeding Institute, and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826,
Korea
| | - Nam-Chon Paek
- Department of Plant Science, Plant Genomics and Breeding Institute, and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826,
Korea
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14
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Hu X, Kato Y, Sumida A, Tanaka A, Tanaka R. The SUFBC 2 D complex is required for the biogenesis of all major classes of plastid Fe-S proteins. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 90:235-248. [PMID: 28103400 DOI: 10.1111/tpj.13483] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 01/04/2017] [Accepted: 01/09/2017] [Indexed: 05/15/2023]
Abstract
Iron-sulfur (Fe-S) proteins play crucial roles in plastids, participating in photosynthesis and other metabolic pathways. Fe-S clusters are thought to be assembled on a scaffold complex composed of SUFB, SUFC and SUFD proteins. However, several additional proteins provide putative scaffold functions in plastids, and, therefore, the contribution of SUFB, C and D proteins to overall Fe-S assembly still remains unclear. In order to gain insights regarding Fe-S cluster biosynthesis in plastids, we analyzed the complex composed of SUFB, C and D in Arabidopsis by blue native-polyacrylamide gel electrophoresis. Using this approach, a major complex of 170 kDa containing all subunits was detected, indicating that these proteins constitute a SUFBC2 D complex similar to their well characterized bacterial counterparts. The functional effects of SUFB, SUFC or SUFD depletion were analyzed using an inducible RNAi silencing system to specifically target the aforementioned components; resulting in a decrease of various plastidic Fe-S proteins including the PsaA/B and PsaC subunits of photosystem I, ferredoxin and glutamine oxoglutarate aminotransferase. In contrast, the knockout of potential Fe-S scaffold proteins, NFU2 and HCF101, resulted in a specific decrease in the PsaA/B and PsaC levels. These results indicate that the functions of SUFB, SUFC and SUFD for Fe-S cluster biosynthesis cannot be replaced by other scaffold proteins and that SUFBC2 D, NFU2 and HCF101 are involved in the same pathway for the biogenesis of PSI. Taken together, our results provide in vivo evidence supporting the hypothesis that SUFBC2 D is the major, and possibly sole scaffold in plastids.
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Affiliation(s)
- Xueyun Hu
- Institute of Low Temperature Science, Hokkaido University, Sapporo, 060-0819, Japan
- School of Life Science and Engineering, Southwest University of Science and Technology, Mianyang City, Sichuan, 621010, China
| | - Yukako Kato
- Institute of Low Temperature Science, Hokkaido University, Sapporo, 060-0819, Japan
| | - Akihiro Sumida
- Institute of Low Temperature Science, Hokkaido University, Sapporo, 060-0819, Japan
| | - Ayumi Tanaka
- Institute of Low Temperature Science, Hokkaido University, Sapporo, 060-0819, Japan
| | - Ryouichi Tanaka
- Institute of Low Temperature Science, Hokkaido University, Sapporo, 060-0819, Japan
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15
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Zanello P. The competition between chemistry and biology in assembling iron–sulfur derivatives. Molecular structures and electrochemistry. Part V. {[Fe4S4](SCysγ)4} proteins. Coord Chem Rev 2017. [DOI: 10.1016/j.ccr.2016.10.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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16
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Hu X, Page MT, Sumida A, Tanaka A, Terry MJ, Tanaka R. The iron-sulfur cluster biosynthesis protein SUFB is required for chlorophyll synthesis, but not phytochrome signaling. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 89:1184-1194. [PMID: 28004871 PMCID: PMC5347852 DOI: 10.1111/tpj.13455] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 12/07/2016] [Accepted: 12/09/2016] [Indexed: 05/08/2023]
Abstract
Proteins that contain iron-sulfur (Fe-S) clusters play pivotal roles in various metabolic processes such as photosynthesis and redox metabolism. Among the proteins involved in the biosynthesis of Fe-S clusters in plants, the SUFB subunit of the SUFBCD complex appears to be unique because SUFB has been reported to be involved in chlorophyll metabolism and phytochrome-mediated signaling. To gain insights into the function of the SUFB protein, we analyzed the phenotypes of two SUFB mutants, laf6 and hmc1, and RNA interference (RNAi) lines with reduced SUFB expression. When grown in the light, the laf6 and hmc1 mutants and the SUFB RNAi lines accumulated higher levels of the chlorophyll biosynthesis intermediate Mg-protoporphyrin IX monomethylester (Mg-proto MME), consistent with the impairment of Mg-proto MME cyclase activity. Both SUFC- and SUFD-deficient RNAi lines accumulated the same intermediate, suggesting that inhibition of Fe-S cluster synthesis is the primary cause of this impairment. Dark-grown laf6 seedlings also showed an increase in protoporphyrin IX (Proto IX), Mg-proto, Mg-proto MME and 3,8-divinyl protochlorophyllide a (DV-Pchlide) levels, but this was not observed in hmc1 or the SUFB RNAi lines, nor was it complemented by SUFB overexpression. In addition, the long hypocotyl in far-red light phenotype of the laf6 mutant could not be rescued by SUFB overexpression and segregated from the pale-green SUFB-deficient phenotype, indicating it is not caused by mutation at the SUFB locus. These results demonstrate that biosynthesis of Fe-S clusters is important for chlorophyll biosynthesis, but that the laf6 phenotype is not due to a SUFB mutation.
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Affiliation(s)
- Xueyun Hu
- Institute of Low Temperature ScienceHokkaido UniversitySapporo060‐0819Japan
- School of Life Science and EngineeringSouthwest University of Science and TechnologyMianyang621010China
| | - Mike T. Page
- Biological SciencesUniversity of SouthamptonSouthamptonUK
| | - Akihiro Sumida
- Institute of Low Temperature ScienceHokkaido UniversitySapporo060‐0819Japan
| | - Ayumi Tanaka
- Institute of Low Temperature ScienceHokkaido UniversitySapporo060‐0819Japan
| | - Matthew J. Terry
- Biological SciencesUniversity of SouthamptonSouthamptonUK
- Institute for Life SciencesUniversity of SouthamptonSouthamptonUK
| | - Ryouichi Tanaka
- Institute of Low Temperature ScienceHokkaido UniversitySapporo060‐0819Japan
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17
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Matsuda K, Shimoda Y, Tanaka A, Ito H. Chlorophyll a is a favorable substrate for Chlamydomonas Mg-dechelatase encoded by STAY-GREEN. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2016; 109:365-373. [PMID: 27810676 DOI: 10.1016/j.plaphy.2016.10.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 10/18/2016] [Accepted: 10/23/2016] [Indexed: 05/08/2023]
Abstract
Mg removal from chlorophyll by Mg-dechelatase is the first step of chlorophyll degradation. Recent studies showed that in Arabidopsis, Stay Green (SGR) encodes Mg-dechelatase. Though the Escherichia coli expression system is advantageous for investigating the properties of Mg-dechelatase, Arabidopsis Mg-dechelatase is not successfully expressed in E. coli. Chlamydomonas reinhardtii SGR (CrSGR) has a long, hydrophilic tail, suggesting that active CrSGR can be expressed in E. coli. After the incubation of chlorophyll a with CrSGR expressed in E. coli, pheophytin a accumulated, indicating that active CrSGR was expressed in E. coli. Substrate specificity of CrSGR against chlorophyll b and an intermediate molecule of the chlorophyll b degradation pathway was examined. CrSGR exhibited no activity against chlorophyll b and low activity against 7-hydroxymethyl chlorophyll a, consistent with the fact that chlorophyll b is degraded only after conversion to chlorophyll a. CrSGR exhibited low activity against divinyl chlorophyll a and chlorophyll a', and no activity against chlorophyllide a, protochlorophyll a, chlorophyll c2, and Zn-chlorophyll a. These observations indicate that chlorophyll a is the most favorable substrate for CrSGR. When CrSGR was expressed in Arabidopsis cells, the chlorophyll content decreased, further confirming that SGR has Mg-dechelating activity in chloroplasts.
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Affiliation(s)
- Kaori Matsuda
- Institute of Low Temperature Science, Hokkaido University, N19 W8, Sapporo, 060-0819, Japan
| | - Yousuke Shimoda
- Institute of Low Temperature Science, Hokkaido University, N19 W8, Sapporo, 060-0819, Japan
| | - Ayumi Tanaka
- Institute of Low Temperature Science, Hokkaido University, N19 W8, Sapporo, 060-0819, Japan; CREST, Japan Science and Technology Agency, N19 W8, Sapporo, 060-0819, Japan
| | - Hisashi Ito
- Institute of Low Temperature Science, Hokkaido University, N19 W8, Sapporo, 060-0819, Japan; CREST, Japan Science and Technology Agency, N19 W8, Sapporo, 060-0819, Japan.
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