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Mahieu CI, Mancini AG, Vikram EP, Planells-Palop V, Joseph NM, Tward AD. ORAOV1, CCND1, and MIR548K Are the Driver Oncogenes of the 11q13 Amplicon in Squamous Cell Carcinoma. Mol Cancer Res 2024; 22:152-168. [PMID: 37930255 PMCID: PMC10831340 DOI: 10.1158/1541-7786.mcr-23-0746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 09/29/2023] [Accepted: 11/02/2023] [Indexed: 11/07/2023]
Abstract
11q13 amplification is a frequent event in human cancer and in particular in squamous cell carcinomas (SCC). Despite almost invariably spanning 10 genes, it is unclear which genetic components of the amplicon are the key driver events in SCC. A combination of computational, in vitro, ex vivo, and in vivo models leveraging efficient primary human keratinocyte genome editing by Cas9-RNP electroporation, identified ORAOV1, CCND1, and MIR548K as the critical drivers of the amplicon in head and neck SCC. CCND1 amplification drives the cell cycle in a CDK4/6/RB1-independent fashion and may confer a novel dependency on RRM2. MIR548K contributes to epithelial-mesenchymal transition. Finally, we identify ORAOV1 as an oncogene that acts likely via its ability to modulate reactive oxygen species. Thus, the 11q13 amplicon drives SCC through at least three independent genetic elements and suggests therapeutic targets for this morbid and lethal disease. IMPLICATIONS This work demonstrates novel mechanisms and ways to target these mechanisms underlying the most common amplification in squamous cell carcinoma, one of the most prevalent and deadly forms of human cancer.
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Affiliation(s)
- Céline I. Mahieu
- Department of Otolaryngology, Head and Neck Surgery, University of California San Francisco, San Francisco, Calfornia
| | | | - Ellee P. Vikram
- Department of Otolaryngology, Head and Neck Surgery, University of California San Francisco, San Francisco, Calfornia
| | - Vicente Planells-Palop
- Department of Otolaryngology, Head and Neck Surgery, University of California San Francisco, San Francisco, Calfornia
| | - Nancy M. Joseph
- Department of Pathology, University of California San Francisco, San Francisco, California
| | - Aaron D. Tward
- Department of Otolaryngology, Head and Neck Surgery, University of California San Francisco, San Francisco, Calfornia
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Hoh D, Froehlich JE, Kramer DM. Redox regulation in chloroplast thylakoid lumen: The pmf changes everything, again. PLANT, CELL & ENVIRONMENT 2023. [PMID: 38111217 DOI: 10.1111/pce.14789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 11/28/2023] [Accepted: 12/05/2023] [Indexed: 12/20/2023]
Abstract
Photosynthesis is the foundation of life on Earth. However, if not well regulated, it can also generate excessive reactive oxygen species (ROS), which can cause photodamage. Regulation of photosynthesis is highly dynamic, responding to both environmental and metabolic cues, and occurs at many levels, from light capture to energy storage and metabolic processes. One general mechanism of regulation involves the reversible oxidation and reduction of protein thiol groups, which can affect the activity of enzymes and the stability of proteins. Such redox regulation has been well studied in stromal enzymes, but more recently, evidence has emerged of redox control of thylakoid lumenal enzymes. This review/hypothesis paper summarizes the latest research and discusses several open questions and challenges to achieving effective redox control in the lumen, focusing on the distinct environments and regulatory components of the thylakoid lumen, including the need to transport electrons across the thylakoid membrane, the effects of pH changes by the proton motive force (pmf) in the stromal and lumenal compartments, and the observed differences in redox states. These constraints suggest that activated oxygen species are likely to be major regulatory contributors to lumenal thiol redox regulation, with key components and processes yet to be discovered.
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Affiliation(s)
- Donghee Hoh
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, Michigan, USA
| | - John E Froehlich
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, Michigan, USA
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA
| | - David M Kramer
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, Michigan, USA
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA
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Willems P, Huang J, Messens J, Van Breusegem F. Functionally annotating cysteine disulfides and metal binding sites in the plant kingdom using AlphaFold2 predicted structures. Free Radic Biol Med 2023; 194:220-229. [PMID: 36493985 DOI: 10.1016/j.freeradbiomed.2022.12.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 11/14/2022] [Accepted: 12/01/2022] [Indexed: 12/12/2022]
Abstract
Deep learning algorithms such as AlphaFold2 predict three-dimensional protein structure with high confidence. The recent release of more than 200 million structural models provides an unprecedented resource for functional protein annotation. Here, we used AlphaFold2 predicted structures of fifteen plant proteomes to functionally and evolutionary analyze cysteine residues in the plant kingdom. In addition to identification of metal ligands coordinated by cysteine residues, we systematically analyzed cysteine disulfides present in these structural predictions. Our analysis demonstrates most of these predicted disulfides are trustworthy due their high agreement (∼96%) with those present in X-ray and NMR protein structures, their characteristic disulfide stereochemistry, the biased subcellular distribution of their proteins and a higher degree of oxidation of their respective cysteines as measured by proteomics. Adopting an evolutionary perspective, zinc binding sites are increasingly present at the expense of iron-sulfur clusters in plants. Interestingly, disulfide formation is increased in secreted proteins of land plants, likely promoting sequence evolution to adapt to changing environments encountered by plants. In summary, Alphafold2 predicted structural models are a rich source of information for studying the role of cysteines residues in proteins of interest and for protein redox biology in general.
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Affiliation(s)
- Patrick Willems
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052, Ghent, Belgium; VIB Center for Plant Systems Biology, VIB, 9052, Ghent, Belgium; Department of Biomolecular Medicine, Ghent University, 9052, Ghent, Belgium; Center for Medical Biotechnology, VIB, 9052, Ghent, Belgium.
| | - Jingjing Huang
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052, Ghent, Belgium; VIB Center for Plant Systems Biology, VIB, 9052, Ghent, Belgium
| | - Joris Messens
- VIB-VUB Center for Structural Biology, Vlaams Instituut voor Biotechnologie, B-1050, Brussels, Belgium; Structural Biology Brussels, Vrije Universiteit Brussel, B-1050, Brussels, Belgium; Brussels Center for Redox Biology, Vrije Universiteit Brussel, B-1050, Brussels, Belgium
| | - Frank Van Breusegem
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052, Ghent, Belgium; VIB Center for Plant Systems Biology, VIB, 9052, Ghent, Belgium
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Song Q, Wang X, Liu Y, Brestic M, Yang X. StLTO1, a lumen thiol oxidoreductase in Solanum tuberosum L., enhances the cold resistance of potato plants. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2022; 325:111481. [PMID: 36181944 DOI: 10.1016/j.plantsci.2022.111481] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Revised: 09/19/2022] [Accepted: 09/26/2022] [Indexed: 06/16/2023]
Abstract
Cold stress reduces plant photosynthesis and increases the accumulation of reactive oxygen species (ROS) in plants, thereby dramatically affecting plant growth, crop productivity and quality. Here, we report that lumen thiol oxidoreductase 1 (StLTO1), a vitamin K epoxide reductase (VKOR)-like protein in the thylakoid membrane of Solanum tuberosum L., enhances the cold tolerance of potato plants. Under normal conditions, overexpression of StLTO1 in plants promoted plant growth. In addition, potato plants overexpressing StLTO1 displayed enhanced photosynthetic capacity and increased capacity for scavenging ROS compared to StLTO1 knockdown and wild-type potato plants under cold conditions. Overexpression of StLTO1 in potato plants also improved cold-regulated (COR) gene expression after cold stress. Our results suggest that StLTO1 acts as a positive regulator of cold resistance in potato plants.
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Affiliation(s)
- Qiping Song
- College of Life Science, State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, Shandong Agricultural University, Taian, 271018, China
| | - Xipan Wang
- College of Life Science, State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, Shandong Agricultural University, Taian, 271018, China
| | - Yang Liu
- College of Life Science, State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, Shandong Agricultural University, Taian, 271018, China
| | - Marian Brestic
- Department of Plant Physiology, Slovak University of Agriculture, Tr. A. Hlinku 2, 949 76 Nitra, Slovak Republic
| | - Xinghong Yang
- College of Life Science, State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, Shandong Agricultural University, Taian, 271018, China.
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Hypoxia-Induced Aquaporins and Regulation of Redox Homeostasis by a Trans-Plasma Membrane Electron Transport System in Maize Roots. Antioxidants (Basel) 2022; 11:antiox11050836. [PMID: 35624700 PMCID: PMC9137787 DOI: 10.3390/antiox11050836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 04/06/2022] [Accepted: 04/13/2022] [Indexed: 02/06/2023] Open
Abstract
In plants, flooding-induced oxygen deficiency causes severe stress, leading to growth reduction and yield loss. It is therefore important to understand the molecular mechanisms for adaptation to hypoxia. Aquaporins at the plasma membrane play a crucial role in water uptake. However, their role during hypoxia and membrane redox changes is still not fully understood. The influence of 24 h hypoxia induction on hydroponically grown maize (Zea mays L.) was investigated using an oil-based setup. Analyses of physiological parameters revealed typical flooding symptoms such as increased ethylene and H2O2 levels, an increased alcohol dehydrogenase activity, and an increased redox activity at the plasma membrane along with decreased oxygen of the medium. Transcriptomic analysis and shotgun proteomics of plasma membranes and soluble fractions were performed to determine alterations in maize roots. RNA-sequencing data confirmed the upregulation of genes involved in anaerobic metabolism, biosynthesis of the phytohormone ethylene, and its receptors. Transcripts of several antioxidative systems and other oxidoreductases were regulated. Mass spectrometry analysis of the plasma membrane proteome revealed alterations in redox systems and an increased abundance of aquaporins. Here, we discuss the importance of plasma membrane aquaporins and redox systems in hypoxia stress response, including the regulation of plant growth and redox homeostasis.
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Lu Y, Yuan L, Zhou Z, Wang M, Wang X, Zhang S, Sun Q. The thiol-disulfide exchange activity of AtPDI1 is involved in the response to abiotic stresses. BMC PLANT BIOLOGY 2021; 21:557. [PMID: 34814838 PMCID: PMC8609882 DOI: 10.1186/s12870-021-03325-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 11/01/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Arabidopsis protein disulfide isomerase 1 (AtPDI1) has been demonstrated to have disulfide isomerase activity and to be involved in the stress response. However, whether the anti-stress function is directly related to the activities of thiol-disulfide exchange remains to be elucidated. RESULTS In the present study, encoding sequences of AtPDI1 of wild-type (WT) and double-cysteine-mutants were transformed into an AtPDI1 knockdown Arabidopsis line (pdi), and homozygous transgenic plants named pdi-AtPDI1, pdi-AtPDI1m1 and pdi-AtPDI1m2 were obtained. Compared with the WT and pdi-AtPDI1, the respective germination ratios of pdi-AtPDI1m1 and pdi-AtPDI1m2 were significantly lower under abiotic stresses and exogenous ABA treatment, whereas the highest germination rate was obtained with AtPDI1 overexpression in the WT (WT- AtPDI1). The root length among different lines was consistent with the germination rate; a higher germination rate was observed with a longer root length. When seedlings were treated with salt, drought, cold and high temperature stresses, pdi-AtPDI1m1, pdi-AtPDI1m2 and pdi displayed lower survival rates than WT and AtPDI1 overexpression plants. The transcriptional levels of ABA-responsive genes and genes encoding ROS-quenching enzymes were lower in pdi-AtPDI1m1 and pdi-AtPDI1m2 than in pdi-AtPDI1. CONCLUSION Taken together, these results clearly suggest that the anti-stress function of AtPDI1 is directly related to the activity of disulfide isomerase.
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Affiliation(s)
- Ying Lu
- College of Life Science, State Key Laboratory of Crop Biology, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China
- Institute of Shandong River Wetlands, Jinan, Shandong, 271100, People's Republic of China
| | - Li Yuan
- College of Life Science, State Key Laboratory of Crop Biology, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China
| | - Zhou Zhou
- College of Life Science, State Key Laboratory of Crop Biology, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China
| | - Mengyu Wang
- College of Life Science, State Key Laboratory of Crop Biology, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China
| | - Xiaoyun Wang
- College of Life Science, State Key Laboratory of Crop Biology, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China
| | - Shizhong Zhang
- College of Life Science, State Key Laboratory of Crop Biology, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China.
| | - Qinghua Sun
- College of Life Science, State Key Laboratory of Crop Biology, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China.
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Wu J, Rong L, Lin W, Kong L, Wei D, Zhang L, Rochaix JD, Xu X. Functional redox links between lumen thiol oxidoreductase1 and serine/threonine-protein kinase STN7. PLANT PHYSIOLOGY 2021; 186:964-976. [PMID: 33620491 PMCID: PMC8195503 DOI: 10.1093/plphys/kiab091] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 02/11/2021] [Indexed: 05/07/2023]
Abstract
In response to changing light quantity and quality, photosynthetic organisms perform state transitions, a process which optimizes photosynthetic yield and mitigates photo-damage. The serine/threonine-protein kinase STN7 phosphorylates the light-harvesting complex of photosystem II (PSII; light-harvesting complex II), which then migrates from PSII to photosystem I (PSI), thereby rebalancing the light excitation energy between the photosystems and restoring the redox poise of the photosynthetic electron transport chain. Two conserved cysteines forming intra- or intermolecular disulfide bonds in the lumenal domain (LD) of STN7 are essential for the kinase activity although it is still unknown how activation of the kinase is regulated. In this study, we show lumen thiol oxidoreductase 1 (LTO1) is co-expressed with STN7 in Arabidopsis (Arabidopsis thaliana) and interacts with the LD of STN7 in vitro and in vivo. LTO1 contains thioredoxin (TRX)-like and vitamin K epoxide reductase domains which are related to the disulfide-bond formation system in bacteria. We further show that the TRX-like domain of LTO1 is able to oxidize the conserved lumenal cysteines of STN7 in vitro. In addition, loss of LTO1 affects the kinase activity of STN7 in Arabidopsis. Based on these results, we propose that LTO1 helps to maintain STN7 in an oxidized active state in state 2 through redox interactions between the lumenal cysteines of STN7 and LTO1.
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Affiliation(s)
- Jianghao Wu
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Liwei Rong
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Weijun Lin
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lingxi Kong
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Dengjie Wei
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lixin Zhang
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng 475004, China
| | - Jean-David Rochaix
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng 475004, China
- Department of Molecular Biology, University of Geneva, Geneva 1211, Switzerland
- Department of Plant Biology, University of Geneva, Geneva 1211, Switzerland
| | - Xiumei Xu
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng 475004, China
- Author for communication:
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Chin-Fatt A, Menassa R. A V HH-Fc Fusion Targeted to the Chloroplast Thylakoid Lumen Assembles and Neutralizes Enterohemorrhagic E. coli O157:H7. FRONTIERS IN PLANT SCIENCE 2021; 12:686421. [PMID: 34122494 PMCID: PMC8193579 DOI: 10.3389/fpls.2021.686421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 04/26/2021] [Indexed: 06/12/2023]
Abstract
Chimeric fusion proteins comprising a single domain antibody (VHH) fused to a crystallizable fragment (Fc) of an immunoglobulin are modular glycoproteins that are becoming increasingly in demand because of their value as diagnostics, research reagents and passive immunization therapeutics. Because ER-associated degradation and misfolding may potentially be limiting factors in the oxidative folding of VHH-Fc fusion proteins in the ER, we sought to explore oxidative folding in an alternative sub-compartment, the chloroplast thylakoid lumen, and determine its viability in a molecular farming context. We developed a set of in-house expression vectors for transient transformation of Nicotiana benthamiana leaves that target a VHH-Fc to the thylakoid lumen via either secretory (Sec) or twin-arginine translocation (Tat) import pathways. Compared to stromal [6.63 ± 3.41 mg/kg fresh weight (FW)], cytoplasmic (undetectable) and Tat-import pathways (5.43 ± 2.41 mg/kg FW), the Sec-targeted VHH-Fc showed superior accumulation (30.56 ± 5.19 mg/kg FW), but was less than that of the ER (51.16 ± 9.11 mg/kg FW). Additionally, the introduction of a rationally designed de novo disulfide bond enhances in planta accumulation when introduced into the Sec-targeted Fc fusion protein from 50.24 ± 4.08 mg/kg FW to 110.90 ± 6.46 mg/kg FW. In vitro immunofluorescent labeling assays on VHH-Fc purified from Sec, Tat, and stromal pathways demonstrate that the antibody still retains VHH functionality in binding Escherichia coli O157:H7 and neutralizing its intimate adherence to human epithelial type 2 cells. These results overall provide a proof of concept that the oxidative folding environment of the thylakoid lumen may be a viable compartment for stably folding disulfide-containing recombinant VHH-Fc proteins.
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Affiliation(s)
- Adam Chin-Fatt
- Agriculture and Agri-Food Canada, London Research and Development Centre, London, ON, Canada
- Department of Biology, University of Western Ontario, London, ON, Canada
| | - Rima Menassa
- Agriculture and Agri-Food Canada, London Research and Development Centre, London, ON, Canada
- Department of Biology, University of Western Ontario, London, ON, Canada
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Gu X, Chen IG, Harding SA, Nyamdari B, Ortega MA, Clermont K, Westwood JH, Tsai CJ. Plasma membrane phylloquinone biosynthesis in nonphotosynthetic parasitic plants. PLANT PHYSIOLOGY 2021; 185:1443-1456. [PMID: 33793953 PMCID: PMC8133638 DOI: 10.1093/plphys/kiab031] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 01/13/2021] [Indexed: 05/25/2023]
Abstract
Nonphotosynthetic holoparasites exploit flexible targeting of phylloquinone biosynthesis to facilitate plasma membrane redox signaling. Phylloquinone is a lipophilic naphthoquinone found predominantly in chloroplasts and best known for its function in photosystem I electron transport and disulfide bridge formation of photosystem II subunits. Phylloquinone has also been detected in plasma membrane (PM) preparations of heterotrophic tissues with potential transmembrane redox function, but the molecular basis for this noncanonical pathway is unknown. Here, we provide evidence of PM phylloquinone biosynthesis in a nonphotosynthetic holoparasite Phelipanche aegyptiaca. A nonphotosynthetic and nonplastidial role for phylloquinone is supported by transcription of phylloquinone biosynthetic genes during seed germination and haustorium development, by PM-localization of alternative terminal enzymes, and by detection of phylloquinone in germinated seeds. Comparative gene network analysis with photosynthetically competent parasites revealed a bias of P. aegyptiaca phylloquinone genes toward coexpression with oxidoreductases involved in PM electron transport. Genes encoding the PM phylloquinone pathway are also present in several photoautotrophic taxa of Asterids, suggesting an ancient origin of multifunctionality. Our findings suggest that nonphotosynthetic holoparasites exploit alternative targeting of phylloquinone for transmembrane redox signaling associated with parasitism.
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Affiliation(s)
- Xi Gu
- Institute of Bioinformatics, University of Georgia, Athens, GA 30602, USA
| | - Ing-Gin Chen
- School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA
| | - Scott A Harding
- School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
- Department of Plant Biology, University of Georgia, Athens, GA 30602, USA
| | - Batbayar Nyamdari
- School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
- Department of Plant Biology, University of Georgia, Athens, GA 30602, USA
| | - Maria A Ortega
- School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
- Department of Plant Biology, University of Georgia, Athens, GA 30602, USA
| | - Kristen Clermont
- School of Plant and Environmental Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - James H Westwood
- School of Plant and Environmental Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Chung-Jui Tsai
- Institute of Bioinformatics, University of Georgia, Athens, GA 30602, USA
- School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
- Department of Plant Biology, University of Georgia, Athens, GA 30602, USA
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Liu M, Zhang Q, Wang C, Meng T, Wang L, Chen C, Ren Z. CsWRKY10 mediates defence responses to Botrytis cinerea infection in Cucumis sativus. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2020; 300:110640. [PMID: 33180717 DOI: 10.1016/j.plantsci.2020.110640] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 08/16/2020] [Accepted: 08/17/2020] [Indexed: 06/11/2023]
Abstract
Cucumber (Cucumis sativus) is one of the most widely cultivated vegetable crops in the world, and its yield is often reduced due to the infection of Botrytis cinerea (B. cinerea), which causes a serious disease. However, few genes involved in the response to B. cinerea have been identified in cucumber. In this study, we identified that CsWRKY10 plays a key role in the cucumber resistance to B. cinerea because that the overexpression of CsWRKY10 significantly increased the susceptibility to B. cinerea in cucumber. After the pathogen infection, the enzyme activities of catalase, superoxide dismutase and peroxidase in transgenic plants were affected, resulting in the decrease in reactive oxygen species (ROS) contents. In addition, the light microscopic images showed that overexpression of CsWRKY10 promoted the spore germination and mycelia elongation of B. cinerea in cucumber. Importantly, after B. cinerea infection, the contents of jasmonic acid (JA) are decreased, and the expression levels of JA- and salicylic acid- related defence genes significantly changed in transgenic plants. In contrast, overexpression of CsWRKY10 enhanced resistance to Corynespora cassiicola in cucumber. Collectively, this study indicated that CsWRKY10 negatively regulates the resistance of cucumber to B. cinerea by reducing the ROS contents and inhibiting the JA-mediated resistance signalling pathway, but strengthens resistance to Corynespora cassiicola.
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Affiliation(s)
- Mengyu Liu
- State Key Laboratory of Crop Biology, Shandong Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops in Huang-Huai Region, Ministry of Agriculture, College of Horticultural Science and Engineering, Shandong Agricultural University, Tai'an, Shandong 271018, China.
| | - Qingxia Zhang
- State Key Laboratory of Crop Biology, Shandong Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops in Huang-Huai Region, Ministry of Agriculture, College of Horticultural Science and Engineering, Shandong Agricultural University, Tai'an, Shandong 271018, China.
| | - Can Wang
- State Key Laboratory of Crop Biology, Shandong Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops in Huang-Huai Region, Ministry of Agriculture, College of Horticultural Science and Engineering, Shandong Agricultural University, Tai'an, Shandong 271018, China.
| | - Tianqi Meng
- State Key Laboratory of Crop Biology, Shandong Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops in Huang-Huai Region, Ministry of Agriculture, College of Horticultural Science and Engineering, Shandong Agricultural University, Tai'an, Shandong 271018, China.
| | - Lina Wang
- State Key Laboratory of Crop Biology, Shandong Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops in Huang-Huai Region, Ministry of Agriculture, College of Horticultural Science and Engineering, Shandong Agricultural University, Tai'an, Shandong 271018, China.
| | - Chunhua Chen
- State Key Laboratory of Crop Biology, Shandong Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops in Huang-Huai Region, Ministry of Agriculture, College of Horticultural Science and Engineering, Shandong Agricultural University, Tai'an, Shandong 271018, China.
| | - Zhonghai Ren
- State Key Laboratory of Crop Biology, Shandong Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops in Huang-Huai Region, Ministry of Agriculture, College of Horticultural Science and Engineering, Shandong Agricultural University, Tai'an, Shandong 271018, China.
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The Role of Chloroplast Gene Expression in Plant Responses to Environmental Stress. Int J Mol Sci 2020; 21:ijms21176082. [PMID: 32846932 PMCID: PMC7503970 DOI: 10.3390/ijms21176082] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 08/18/2020] [Accepted: 08/20/2020] [Indexed: 12/16/2022] Open
Abstract
Chloroplasts are plant organelles that carry out photosynthesis, produce various metabolites, and sense changes in the external environment. Given their endosymbiotic origin, chloroplasts have retained independent genomes and gene-expression machinery. Most genes from the prokaryotic ancestors of chloroplasts were transferred into the nucleus over the course of evolution. However, the importance of chloroplast gene expression in environmental stress responses have recently become more apparent. Here, we discuss the emerging roles of the distinct chloroplast gene expression processes in plant responses to environmental stresses. For example, the transcription and translation of psbA play an important role in high-light stress responses. A better understanding of the connection between chloroplast gene expression and environmental stress responses is crucial for breeding stress-tolerant crops better able to cope with the rapidly changing environment.
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Wessendorf RL, Lu Y. Photosynthetic characterization of transgenic Synechocystis expressing a plant thiol/disulfide-modulating protein. PLANT SIGNALING & BEHAVIOR 2019; 15:1709708. [PMID: 31889463 PMCID: PMC7053882 DOI: 10.1080/15592324.2019.1709708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 12/18/2019] [Accepted: 12/22/2019] [Indexed: 06/10/2023]
Abstract
A previous study showed that introducing an Arabidopsis thaliana thiol/disulfide-modulating protein, Low Quantum Yield of Photosystem II 1 (LQY1), into the cyanobacterium Synechocystis sp. PCC6803 increased the efficiency of Photosystem II (PSII) photochemistry. In the present study, the authors provided additional evidence for the role of AtLQY1 in improving PSII photochemical efficiency and cell growth. Light response curve analysis showed that AtLQY1-expressing Synechocystis grown at a moderate growth light intensity (50 µmol photons m-2 s-1) had higher minimal, maximal, and variable fluorescence than the empty-vector control, under a wide range of actinic light intensities. Light induction and dark recovery curves demonstrated that AtLQY1-expressing Synechocystis grown at the moderate growth light intensity had higher effective PSII quantum yield, higher photochemical quenching, lower regulated heat dissipation (non-photochemical quenching), low amounts of reduced plastoquinone, and higher amounts of oxidized plastoquinone than the empty-vector control. Furthermore, growth curve analysis indicated that AtLQY1-expressing Synechocystis grew faster than the empty-vector control at the moderate growth light intensity. These results suggest that transgenic expression of AtLQY1 in Synechocystis significantly improves PSII photochemical efficiency and overall cell growth.
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Affiliation(s)
- Ryan L. Wessendorf
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI, USA
| | - Yan Lu
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI, USA
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Wessendorf RL, Lu Y. Introducing an Arabidopsis thaliana Thylakoid Thiol/Disulfide-Modulating Protein Into Synechocystis Increases the Efficiency of Photosystem II Photochemistry. FRONTIERS IN PLANT SCIENCE 2019; 10:1284. [PMID: 31681379 PMCID: PMC6805722 DOI: 10.3389/fpls.2019.01284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2019] [Accepted: 09/13/2019] [Indexed: 06/10/2023]
Abstract
Photosynthetic species are subjected to a variety of environmental stresses, including suboptimal irradiance. In oxygenic photosynthetic organisms, a major effect of high light exposure is damage to the Photosystem II (PSII) reaction-center protein D1. This process even happens under low or moderate light. To cope with photodamage to D1, photosynthetic organisms evolved an intricate PSII repair and reassembly cycle, which requires the participation of different auxiliary proteins, including thiol/disulfide-modulating proteins. Most of these auxiliary proteins exist ubiquitously in oxygenic photosynthetic organisms. Due to differences in mobility and environmental conditions, land plants are subject to more extensive high light stress than algae and cyanobacteria. Therefore, land plants evolved additional thiol/disulfide-modulating proteins, such as Low Quantum Yield of PSII 1 (LQY1), to aid in the repair and reassembly cycle of PSII. In this study, we introduced an Arabidopsis thaliana homolog of LQY1 (AtLQY1) into the cyanobacterium Synechocystis sp. PCC6803 and performed a series of biochemical and physiological assays on AtLQY1-expressing Synechocystis. At a moderate growth light intensity (50 µmol photons m-2 s-1), AtLQY1-expressing Synechocystis was found to have significantly higher F v /F m , and lower nonphotochemical quenching and reactive oxygen species levels than the empty-vector control, which is opposite from the loss-of-function Atlqy1 mutant phenotype. Light response curve analysis of PSII operating efficiency and electron transport rate showed that AtLQY1-expressing Synechocystis also outperform the empty-vector control under higher light intensities. The increases in F v /F m , PSII operating efficiency, and PSII electron transport rate in AtLQY1-expressing Synechocystis under such growth conditions most likely come from an increased amount of PSII, because the level of D1 protein was found to be higher in AtLQY1-expressing Synechocystis. These results suggest that introducing AtLQY1 is beneficial to Synechocystis.
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Affiliation(s)
| | - Yan Lu
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI, United States
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Liu X, Li R, Dai Y, Yuan L, Sun Q, Zhang S, Wang X. A B-box zinc finger protein, MdBBX10, enhanced salt and drought stresses tolerance in Arabidopsis. PLANT MOLECULAR BIOLOGY 2019; 99:437-447. [PMID: 30712230 DOI: 10.1007/s11103-019-00828-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Accepted: 01/21/2019] [Indexed: 05/22/2023]
Abstract
The expression of MdBBX10 was significantly induced by different stresses and ABA treatments. Overexpression of MdBBX10 in Arabidopsis significantly enhanced abiotic stresses tolerance by ABA signalling. The roles of B-box domain(s) containing proteins (BBXs) in regulation of flowering and light morphogenesis of plants were intensively studied. However, the roles of plant BBXs in abiotic stresses are poorly understood. A B-box protein encoding gene from apple (MdBBX10) was found to be up-regulated from gene expression profile under salt stress. qRT-PCR analysis indicated that the expression of MdBBX10 was significantly induced by different stresses and exogenous abscisic acid (ABA) in apple roots and leaves. The β-glucuronidase activity driven by the promoter of MdBBX10 was also strongly induced by NaCl, H2O2, polyethylene glycol and exogenous ABA, which was consistent to the existence of rich cis-acting elements related to the abiotic stresses in the promoter sequence. Over-expression of MdBBX10 in Arabidopsis significantly enhanced tolerance to abiotic stresses, with higher germination ratio and longer length of roots than the wild type plants. Transgenic plants of over-expressing MdBBX10 lines were more sensitive to exogenous ABA than the wild type plants. Under abiotic stress treatments, the transcript levels of ABA- and stress-related genes were higher in MdBBX10-overexpressing plants than wild type plants. Over-expression of MdBBX10 could enhance plant's ability to scavenge reactive oxygen species (ROS) under stresses, which is correlated with the expression of ROS-scavenging genes. These results provided the evidences that MdBBX10 plays an important role in enhanced plant tolerance to abiotic stresses, which were involved in ABA-mediated response and ROS response.
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Affiliation(s)
- Xin Liu
- State Key Laboratory of Crop Biology, College of Life Science, Shandong Agricultural University, Taian, 271018, Shandong, People's Republic of China
| | - Rong Li
- State Key Laboratory of Crop Biology, College of Life Science, Shandong Agricultural University, Taian, 271018, Shandong, People's Republic of China
| | - Yaqing Dai
- State Key Laboratory of Crop Biology, College of Life Science, Shandong Agricultural University, Taian, 271018, Shandong, People's Republic of China
| | - Li Yuan
- State Key Laboratory of Crop Biology, College of Life Science, Shandong Agricultural University, Taian, 271018, Shandong, People's Republic of China
| | - Qinghua Sun
- State Key Laboratory of Crop Biology, College of Life Science, Shandong Agricultural University, Taian, 271018, Shandong, People's Republic of China
| | - Shizhong Zhang
- State Key Laboratory of Crop Biology, College of Life Science, Shandong Agricultural University, Taian, 271018, Shandong, People's Republic of China.
| | - Xiaoyun Wang
- State Key Laboratory of Crop Biology, College of Life Science, Shandong Agricultural University, Taian, 271018, Shandong, People's Republic of China.
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Meyer AJ, Riemer J, Rouhier N. Oxidative protein folding: state-of-the-art and current avenues of research in plants. THE NEW PHYTOLOGIST 2019; 221:1230-1246. [PMID: 30230547 DOI: 10.1111/nph.15436] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2018] [Accepted: 08/01/2018] [Indexed: 06/08/2023]
Abstract
Contents Summary 1230 I. Introduction 1230 II. Formation and isomerization of disulfides in the ER and the Golgi apparatus 1231 III. The disulfide relay in the mitochondrial intermembrane space: why are plants different? 1236 IV. Disulfide bond formation on luminal proteins in thylakoids 1240 V. Conclusion 1242 Acknowledgements 1242 References 1242 SUMMARY: Disulfide bonds are post-translational modifications crucial for the structure and function of thousands of proteins. Their formation and isomerization, referred to as oxidative folding, require specific protein machineries found in oxidizing subcellular compartments, namely the endoplasmic reticulum and the associated endomembrane system, the intermembrane space of mitochondria and the thylakoid lumen of chloroplasts. At least one protein component is required for transferring electrons from substrate proteins to an acceptor that is usually molecular oxygen. For oxidation reactions, incoming reduced substrates are oxidized by thiol-oxidoreductase proteins (or domains in case of chimeric proteins), which are usually themselves oxidized by a single thiol oxidase, the enzyme generating disulfide bonds de novo. By contrast, the description of the molecular actors and pathways involved in proofreading and isomerization of misfolded proteins, which require a tightly controlled redox balance, lags behind. Herein we provide a general overview of the knowledge acquired on the systems responsible for oxidative protein folding in photosynthetic organisms, highlighting their particularities compared to other eukaryotes. Current research challenges are discussed including the importance and specificity of these oxidation systems in the context of the existence of reducing systems in the same compartments.
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Affiliation(s)
- Andreas J Meyer
- INRES-Chemical Signalling, University of Bonn, 53113, Bonn, Germany
| | - Jan Riemer
- Institute of Biochemistry, University of Cologne, 50674, Cologne, Germany
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Zhang H, Ding Y, Zhi J, Li X, Liu H, Xu J. Over-expression of the poplar expansin gene PtoEXPA12 in tobacco plants enhanced cadmium accumulation. Int J Biol Macromol 2018; 116:676-682. [PMID: 29758311 DOI: 10.1016/j.ijbiomac.2018.05.053] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 05/10/2018] [Accepted: 05/10/2018] [Indexed: 12/30/2022]
Abstract
As important cell wall proteins in plants, expansins are involved in a serious of abiotic stress resistance such as drought, heat, salt, even heavy metals. To understand the role of expansins in cadmium (Cd) stress, we analyzed the expression patterns of 36 expansin genes in Populus tomentosa. A Cd-induced expansin gene, PtoEXPA12, was identified, cloned, and transformed into tobacco plants. After treatment with Cd, the transgenic plants showed stronger symptoms of Cd toxicity as to the wild-type tobacco plants. Further physiological tests showed that the transformants had higher relative electrolyte leakage and superoxide dismutase activity, more malondialdehyde and H2O2 content, and lower chlorophyll content in Cd stress. Cd content measurement showed it is 1.40-2.07-fold higher and 1.29-1.38-fold higher separately in roots and shoots of transgenic plants than those in wild-type plants, while the transfer coefficient value kept invariably even decreased. Therefore, PtoEXPA12 was really involved in Cd uptake and accumulation, and led to Cd toxicity of cells. It would be a potentially applicable part in phytoremediation system.
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Affiliation(s)
- Hao Zhang
- National Engineering Laboratory of Tree Breeding, Beijing Forestry University, 100083, China
| | - Yana Ding
- National Engineering Laboratory of Tree Breeding, Beijing Forestry University, 100083, China
| | - Junkai Zhi
- National Engineering Laboratory of Tree Breeding, Beijing Forestry University, 100083, China
| | - Xiaoyu Li
- National Engineering Laboratory of Tree Breeding, Beijing Forestry University, 100083, China
| | - Huabo Liu
- National Engineering Laboratory of Tree Breeding, Beijing Forestry University, 100083, China
| | - Jichen Xu
- National Engineering Laboratory of Tree Breeding, Beijing Forestry University, 100083, China.
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17
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Kang ZH, Wang GX. Redox regulation in the thylakoid lumen. JOURNAL OF PLANT PHYSIOLOGY 2016; 192:28-37. [PMID: 26812087 DOI: 10.1016/j.jplph.2015.12.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Revised: 12/04/2015] [Accepted: 12/04/2015] [Indexed: 06/05/2023]
Abstract
Higher plants need to balance the efficiency of light energy absorption and dissipative photo-protection when exposed to fluctuations in light quantity and quality. This aim is partially realized through redox regulation within the chloroplast, which occurs in all chloroplast compartments except the envelope intermembrane space. In contrast to the chloroplast stroma, less attention has been paid to the thylakoid lumen, an inner, continuous space enclosed by the thylakoid membrane in which redox regulation is also essential for photosystem biogenesis and function. This sub-organelle compartment contains at least 80 lumenal proteins, more than 30 of which are known to contain disulfide bonds. Thioredoxins (Trx) in the chloroplast stroma are photo-reduced in the light, transferring reducing power to the proteins in the thylakoid membrane and ultimately the lumen through a trans-thylakoid membrane-reduced, equivalent pathway. The discovery of lumenal thiol oxidoreductase highlights the importance of the redox regulation network in the lumen for controlling disulfide bond formation, which is responsible for protein activity and folding and even plays a role in photo-protection. In addition, many lumenal members involved in photosystem assembly and non-photochemical quenching are likely required for reduction and/or oxidation to maintain their proper efficiency upon changes in light intensity. In light of recent findings, this review summarizes the multiple redox processes that occur in the thylakoid lumen in great detail, highlighting the essential auxiliary roles of lumenal proteins under fluctuating light conditions.
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Affiliation(s)
- Zhen-Hui Kang
- Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, Bioengineering College of Chongqing University, Chongqing 400030, China
| | - Gui-Xue Wang
- Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, Bioengineering College of Chongqing University, Chongqing 400030, China.
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Yu ZB, Yang XJ, Du JJ, Wan CM, Xu JN, Wang WJ, Feng YG, Wang XY. A homologue of vitamin K epoxide reductase in Solanum lycopersicum is involved in resistance to osmotic stress. PHYSIOLOGIA PLANTARUM 2016; 156:311-322. [PMID: 26294083 DOI: 10.1111/ppl.12376] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 05/14/2015] [Accepted: 06/02/2015] [Indexed: 06/04/2023]
Abstract
Vitamin K epoxide reductase (VKOR) exists widely in the chloroplasts of higher plants and plays important roles in redox regulation. However, investigations of plant VKOR function have primarily focused on VKOR from Arabidopsis, and knowledge concerning this function is therefore quite limited. In this study, Solanum lycopersicum was used to study the function of VKOR. Transcription level analysis revealed that SlVKOR (S. lycopersicum VKOR) expression was upregulated by salt or drought stress. To further investigate the function of SlVKOR in plants, we generated sense and antisense transgenic S. lycopersicum homozygotes at T2 generation plants. Compared with wild-type (WT) plants, the leaf disks of the SlVKOR overexpression plants retained a much higher percentage of chlorophyll after salt or drought treatment, whereas the antisense transgenic plants displayed an opposite response. The overexpressed plants displayed lower levels of H2O2 and superoxide anion radical (O2(·-)) than WT plants, whereas antisense plants accumulated considerably more H2O2 and O2(·-). The activities of reactive oxygen scavenger enzymes, including superoxide dismutase, peroxidase, ascorbate peroxidase and catalase, were consistent with the accumulation of reactive oxygen species. Based on these results, we suggest that SlVKOR is involved in resistance to salt or drought stress.
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Affiliation(s)
- Zhi-Bo Yu
- College of Life Science, State Key Laboratory of Crop Biology, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China
| | - Xiao-Jian Yang
- College of Life Science, State Key Laboratory of Crop Biology, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China
| | - Jia-Jia Du
- College of Life Science, State Key Laboratory of Crop Biology, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China
| | - Chun-Mei Wan
- College of Life Science, State Key Laboratory of Crop Biology, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China
| | - Jia-Ning Xu
- College of Life Science, State Key Laboratory of Crop Biology, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China
| | - Wen-Jun Wang
- Jinan Academy of Agricultural Sciences, Jinan, Shandong, 250300, People's Republic of China
| | - Yue-Guang Feng
- Jinan Academy of Agricultural Sciences, Jinan, Shandong, 250300, People's Republic of China
| | - Xiao-Yun Wang
- College of Life Science, State Key Laboratory of Crop Biology, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China
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Lu Y. Identification and Roles of Photosystem II Assembly, Stability, and Repair Factors in Arabidopsis. FRONTIERS IN PLANT SCIENCE 2016; 7:168. [PMID: 26909098 PMCID: PMC4754418 DOI: 10.3389/fpls.2016.00168] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 01/31/2016] [Indexed: 05/18/2023]
Abstract
Photosystem II (PSII) is a multi-component pigment-protein complex that is responsible for water splitting, oxygen evolution, and plastoquinone reduction. Components of PSII can be classified into core proteins, low-molecular-mass proteins, extrinsic oxygen-evolving complex (OEC) proteins, and light-harvesting complex II proteins. In addition to these PSII subunits, more than 60 auxiliary proteins, enzymes, or components of thylakoid protein trafficking/targeting systems have been discovered to be directly or indirectly involved in de novo assembly and/or the repair and reassembly cycle of PSII. For example, components of thylakoid-protein-targeting complexes and the chloroplast-vesicle-transport system were found to deliver PSII subunits to thylakoid membranes. Various auxiliary proteins, such as PsbP-like (Psb stands for PSII) and light-harvesting complex-like proteins, atypical short-chain dehydrogenase/reductase family proteins, and tetratricopeptide repeat proteins, were discovered to assist the de novo assembly and stability of PSII and the repair and reassembly cycle of PSII. Furthermore, a series of enzymes were discovered to catalyze important enzymatic steps, such as C-terminal processing of the D1 protein, thiol/disulfide-modulation, peptidylprolyl isomerization, phosphorylation and dephosphorylation of PSII core and antenna proteins, and degradation of photodamaged PSII proteins. This review focuses on the current knowledge of the identities and molecular functions of different types of proteins that influence the assembly, stability, and repair of PSII in the higher plant Arabidopsis thaliana.
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Lu Y, Peng JJ, Yu ZB, Du JJ, Xu JN, Wang XY. Thylakoid membrane oxidoreductase LTO1/AtVKOR is involved in ABA-mediated response to osmotic stress in Arabidopsis. PHYSIOLOGIA PLANTARUM 2015; 154:28-38. [PMID: 25171375 DOI: 10.1111/ppl.12268] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2014] [Revised: 07/04/2014] [Accepted: 07/13/2014] [Indexed: 06/03/2023]
Abstract
Arabidopsis lumen thiol oxidoreductase 1 (LTO1) - the At4g35760 gene product - was previously found to be related to reactive oxygen species (ROS) accumulation. Here, we show that ROS accumulated in a mutant Arabidopsis line (lto1-2, mutant of LTO1/AtVKOR) under osmotic stress at a higher level than that observed in wild-type and transgenic complemented plants of the lto1-2 mutant (lto1-2C, transgenic complemented plants of lto1-2). Because ROS accumulation in osmotic stress is triggered by abscisic acid (ABA), an ABA-responsive gene, Annexin 1 (AnnAt1), was selected to study the response. Osmotic stress or exogenous ABA can significantly upregulate the transcription of AnnAt1 in wild-type and lto1-2C plants. Only a slight change in the transcriptional abundance of AnnAt1 was observed under osmotic stress in the lto1-2 mutant, but exogenous ABA application could increase the expression of AnnAt1, which suggested that exogenous ABA had a partial complementation role. Because the transcription of AnnAt1 is regulated by ABRE (ABA-responsive elements) binding proteins (AREBs)/ABRE binding factors (ABFs), the expression of AREBs/ABFs was also analyzed. The transcription of AREBs/ABFs in the lto1-2 mutant was not induced by osmotic stress but was significantly upregulated by exogenous ABA, which significantly differs from the wild-type and lto1-2C plant responses. Similarly, the expression of another ABA-responsive gene, RD29B (responsive to desiccation stress gene 29B), in the lto1-2 mutant was also upregulated by exogenous ABA. The partial complementation of mutants by ABA indicated that the ABA signal transduction pathway was not significantly affected in the lto1-2 mutant. Taken together, these results suggest that LTO1 is involved in ABA-mediated response to osmotic stress, possibly by affecting the biosynthesis of endogenous ABA.
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Affiliation(s)
- Ying Lu
- College of Life Science, Shandong Agricultural University, Taian, 271018, China
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Hallin EI, Guo K, Åkerlund HE. Violaxanthin de-epoxidase disulphides and their role in activity and thermal stability. PHOTOSYNTHESIS RESEARCH 2015; 124:191-198. [PMID: 25764016 PMCID: PMC4412432 DOI: 10.1007/s11120-015-0118-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 03/05/2015] [Indexed: 05/28/2023]
Abstract
Violaxanthin de-epoxidase (VDE) catalyses the conversion of violaxanthin to zeaxanthin at the lumen side of the thylakoids during exposure to intense light. VDE consists of a cysteine-rich N-terminal domain, a lipocalin-like domain and a negatively charged C-terminal domain. That the cysteines are important for the activity of VDE is well known, but in what way is less understood. In this study, wild-type spinach VDE was expressed in E. coli as inclusion bodies, refolded and purified to give a highly active and homogenous preparation. The metal content (Fe, Cu, Ni, Mn, Co and Zn) was lower than 1 mol% excluding a metal-binding function of the cysteines. To investigate which of the 13 cysteines that could be important for the function of VDE, we constructed mutants where the cysteines were replaced by serines, one by one. For 12 out of 13 mutants the activity dropped by more than 99.9%. A quantification of free cysteines showed that only the most N-terminal of these cysteines was in reduced form in the native VDE. A disulphide pattern in VDE of C9-C27, C14-C21, C33-C50, C37-C46, C65-C72 and C118-C284 was obtained after digestion of VDE with thermolysin followed by mass spectroscopy analysis of reduced versus non-reduced samples. The residual activity found for the mutants showed a variation that was consistent with the results obtained from mass spectroscopy. Reduction of the disulphides resulted in loss of a rigid structure and a decrease in thermal stability of 15 °C.
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Affiliation(s)
- Erik Ingmar Hallin
- Department of Biochemistry and Structural Biology, Lund University, P.O. Box 124, 221 00 Lund, Sweden
| | - Kuo Guo
- Department of Biochemistry and Structural Biology, Lund University, P.O. Box 124, 221 00 Lund, Sweden
| | - Hans-Erik Åkerlund
- Department of Biochemistry and Structural Biology, Lund University, P.O. Box 124, 221 00 Lund, Sweden
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Hallin EI, Guo K, Åkerlund HE. Violaxanthin de-epoxidase disulphides and their role in activity and thermal stability. PHOTOSYNTHESIS RESEARCH 2015; 124:191-198. [PMID: 25764016 DOI: 10.1007/s11120-015-0118-119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 03/05/2015] [Indexed: 05/25/2023]
Abstract
Violaxanthin de-epoxidase (VDE) catalyses the conversion of violaxanthin to zeaxanthin at the lumen side of the thylakoids during exposure to intense light. VDE consists of a cysteine-rich N-terminal domain, a lipocalin-like domain and a negatively charged C-terminal domain. That the cysteines are important for the activity of VDE is well known, but in what way is less understood. In this study, wild-type spinach VDE was expressed in E. coli as inclusion bodies, refolded and purified to give a highly active and homogenous preparation. The metal content (Fe, Cu, Ni, Mn, Co and Zn) was lower than 1 mol% excluding a metal-binding function of the cysteines. To investigate which of the 13 cysteines that could be important for the function of VDE, we constructed mutants where the cysteines were replaced by serines, one by one. For 12 out of 13 mutants the activity dropped by more than 99.9%. A quantification of free cysteines showed that only the most N-terminal of these cysteines was in reduced form in the native VDE. A disulphide pattern in VDE of C9-C27, C14-C21, C33-C50, C37-C46, C65-C72 and C118-C284 was obtained after digestion of VDE with thermolysin followed by mass spectroscopy analysis of reduced versus non-reduced samples. The residual activity found for the mutants showed a variation that was consistent with the results obtained from mass spectroscopy. Reduction of the disulphides resulted in loss of a rigid structure and a decrease in thermal stability of 15 °C.
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Affiliation(s)
- Erik Ingmar Hallin
- Department of Biochemistry and Structural Biology, Lund University, P.O. Box 124, 221 00, Lund, Sweden
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Wan CM, Yang XJ, Du JJ, Lu Y, Yu ZB, Feng YG, Wang XY. Identification and characterization of SlVKOR, a disulfide bond formation protein from Solanum lycopersicum, and bioinformatic analysis of plant VKORs. BIOCHEMISTRY (MOSCOW) 2015; 79:440-9. [PMID: 24954595 DOI: 10.1134/s0006297914050083] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Homologs of vitamin K epoxide reductase (VKOR) exist widely in plants. However, only VKOR of Arabidopsis thaliana has been the subject of many studies to date. In the present study, the coding region of a VKOR from Solanum lycopersicum (JF951971 in GenBank) was cloned; it contained a membrane domain (VKOR domain) and an additional soluble thioredoxin-like (Trx-like) domain. Bioinformatic analysis showed that the first 47 amino acids in the N-terminus should act as a transit peptide targeting the protein to the chloroplast. Western blot demonstrated that the protein is localized in thylakoid membrane with the Trx-like domain facing the lumen. Modeling of three-dimensional structure showed that SlVKOR has a similar conformation with Arabidopsis and cyanobacterial VKORs, with five transmembrane segments in the VKOR domain and a typical Trx-like domain in the lumen. Functional assay showed that the full-length of SlVKOR with Trx-like domain without the transit peptide could catalyze the formation of disulfide bonds. Similar transit peptides at the N-terminus commonly exist in plant VKORs, most of them targeting to chloroplast according to prediction. Comparison of sequences and structures from different plants indicated that all plant VKORs possess two domains, a transmembrane VKOR domain and a soluble Trx-like domain, each having four conservative cysteines. The cysteines were predicted to be related to the function of catalyzing the formation of disulfide bonds.
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Affiliation(s)
- Chun-Mei Wan
- College of Life Sciences, Shandong Agricultural University, Taian, Shandong, 271018, P. R. China.
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Bölter B, Soll J, Schwenkert S. Redox meets protein trafficking. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:949-56. [PMID: 25626173 DOI: 10.1016/j.bbabio.2015.01.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 01/16/2015] [Accepted: 01/19/2015] [Indexed: 11/15/2022]
Abstract
After the engulfment of two prokaryotic organisms, the thus emerged eukaryotic cell needed to establish means of communication and signaling to properly integrate the acquired organelles into its metabolism. Regulatory mechanisms had to evolve to ensure that chloroplasts and mitochondria smoothly function in accordance with all other cellular processes. One essential process is the post-translational import of nuclear encoded organellar proteins, which needs to be adapted according to the requirements of the plant. The demand for protein import is constantly changing depending on varying environmental conditions, as well as external and internal stimuli or different developmental stages. Apart from long-term regulatory mechanisms such as transcriptional/translation control, possibilities for short-term acclimation are mandatory. To this end, protein import is integrated into the cellular redox network, utilizing the recognition of signals from within the organelles and modifying the efficiency of the translocon complexes. Thereby, cellular requirements can be communicated throughout the whole organism. This article is part of a Special Issue entitled: Chloroplast Biogenesis.
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Affiliation(s)
- Bettina Bölter
- Department Biologie I-Botanik, Ludwig-Maximilians-Universität, Großhadernerstr. 2-4, D-82152 Planegg-Martinsried, Germany; Munich Center for Integrated Protein Science CiPSM, Ludwig-Maximilians-Universität, Feodor-Lynen-Strasse 25, D-81377 Munich, Germany
| | - Jürgen Soll
- Department Biologie I-Botanik, Ludwig-Maximilians-Universität, Großhadernerstr. 2-4, D-82152 Planegg-Martinsried, Germany; Munich Center for Integrated Protein Science CiPSM, Ludwig-Maximilians-Universität, Feodor-Lynen-Strasse 25, D-81377 Munich, Germany.
| | - Serena Schwenkert
- Department Biologie I-Botanik, Ludwig-Maximilians-Universität, Großhadernerstr. 2-4, D-82152 Planegg-Martinsried, Germany; Munich Center for Integrated Protein Science CiPSM, Ludwig-Maximilians-Universität, Feodor-Lynen-Strasse 25, D-81377 Munich, Germany
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Photosystem II repair in plant chloroplasts--Regulation, assisting proteins and shared components with photosystem II biogenesis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:900-9. [PMID: 25615587 DOI: 10.1016/j.bbabio.2015.01.006] [Citation(s) in RCA: 189] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Revised: 01/07/2015] [Accepted: 01/15/2015] [Indexed: 01/30/2023]
Abstract
Photosystem (PS) II is a multisubunit thylakoid membrane pigment-protein complex responsible for light-driven oxidation of water and reduction of plastoquinone. Currently more than 40 proteins are known to associate with PSII, either stably or transiently. The inherent feature of the PSII complex is its vulnerability in light, with the damage mainly targeted to one of its core proteins, the D1 protein. The repair of the damaged D1 protein, i.e. the repair cycle of PSII, initiates in the grana stacks where the damage generally takes place, but subsequently continues in non-appressed thylakoid domains, where many steps are common for both the repair and de novo assembly of PSII. The sequence of the (re)assembly steps of genuine PSII subunits is relatively well-characterized in higher plants. A number of novel findings have shed light into the regulation mechanisms of lateral migration of PSII subcomplexes and the repair as well as the (re)assembly of the complex. Besides the utmost importance of the PSII repair cycle for the maintenance of PSII functionality, recent research has pointed out that the maintenance of PSI is closely dependent on regulation of the PSII repair cycle. This review focuses on the current knowledge of regulation of the repair cycle of PSII in higher plant chloroplasts. Particular emphasis is paid on sequential assembly steps of PSII and the function of the number of PSII auxiliary proteins involved both in the biogenesis and repair of PSII. This article is part of a Special Issue entitled: Chloroplast Biogenesis.
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Du JJ, Zhan CY, Lu Y, Cui HR, Wang XY. The conservative cysteines in transmembrane domain of AtVKOR/LTO1 are critical for photosynthetic growth and photosystem II activity in Arabidopsis. FRONTIERS IN PLANT SCIENCE 2015; 6:238. [PMID: 25941528 PMCID: PMC4400859 DOI: 10.3389/fpls.2015.00238] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Accepted: 03/25/2015] [Indexed: 05/20/2023]
Abstract
Thylakoid protein vitamin K epoxide reductase (AtVKOR/LTO1) is involved in oxidoreduction. The deficiency of this compound causes pleiotropic defects in Arabidopsis thaliana, such as severely stunted growth, smaller sized leaves, and delay of flowering. Transgenic complementation of wild-type AtVKOR (VKORWT) to vkor mutant lines ultimately demonstrates that the phenotype changes are due to this gene. However, whether AtVKOR functions in Arabidopsis through its protein oxidoreduction is unknown. To further study the redox-active sites of AtVKOR in vivo, a series of plasmids containing cysteine-mutant VKORs were constructed and transformed into vkor deficient lines. Compared with transgenic AtVKORWT plants, the size of the transgenic plants with a single conservative cysteine mutation (VKORC109A, VKORC116A, VKORC195A, and VKORC198A) were smaller, and two double-cysteine mutations (VKORC109AC116A and VKORC195AC198A) showed significantly stunted growth, similar with the vkor mutant line. However, mutations of two non-conservative cysteines (VKORC46A and VKORC230A) displayed little obvious changes in the phenotypes of Arabidopsis. Consistently, the maximum and actual efficiency of photosystem II (PSII) in double-cysteine mutation plants decreased significantly to the level similar to that of the vkor mutant line both under normal growth light and high light. A significantly decreased amount of D1 protein and increased accumulation of reactive oxygen species were observed in two double-cysteine mutations under high light. All of the results above indicated that the conservative cysteines in transmembrane domains were the functional sites of AtVKOR in Arabidopsis and that the oxidoreductase activities of AtVKOR were directly related to the autotrophic photosynthetic growth and PSII activity of Arabidopsis thaliana.
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Affiliation(s)
| | | | | | | | - Xiao-Yun Wang
- *Correspondence: Xiao-Yun Wang, State Key Laboratory of Crop Biology, College of Life Science, Shandong Agricultural University, Daizong Street 61, Tai´an, Shandong 271018, China
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Midorikawa T, Endow JK, Dufour J, Zhu J, Inoue K. Plastidic type I signal peptidase 1 is a redox-dependent thylakoidal processing peptidase. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 80:592-603. [PMID: 25182596 DOI: 10.1111/tpj.12655] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 08/08/2014] [Accepted: 08/21/2014] [Indexed: 05/09/2023]
Abstract
Thylakoids are the photosynthetic membranes in chloroplasts and cyanobacteria. The aqueous phase inside the thylakoid known as the thylakoid lumen plays an essential role in the photosynthetic electron transport. The presence and significance of thiol-disulfide exchange in this compartment have been recognized but remain poorly understood. All proteins found free in the thylakoid lumen and some proteins associated to the thylakoid membrane require an N-terminal targeting signal, which is removed in the lumen by a membrane-bound serine protease called thylakoidal processing peptidase (TPP). TPP is homologous to Escherichia coli type I signal peptidase (SPI) called LepB. Genetic data indicate that plastidic SPI 1 (Plsp1) is the main TPP in Arabidopsis thaliana (Arabidopsis) although biochemical evidence had been lacking. Here we demonstrate catalytic activity of bacterially produced Arabidopsis Plsp1. Recombinant Plsp1 showed processing activity against various TPP substrates at a level comparable to that of LepB. Plsp1 and LepB were also similar in the pH optima, sensitivity to arylomycin variants and a preference for the residue at -3 to the cleavage site within a substrate. Plsp1 orthologs found in angiosperms contain two unique Cys residues located in the lumen. Results of processing assays suggested that these residues were redox active and formation of a disulfide bond between them was necessary for the activity of recombinant Arabidopsis Plsp1. Furthermore, Plsp1 in Arabidopsis and pea thylakoids migrated faster under non-reducing conditions than under reducing conditions on SDS-PAGE. These results underpin the notion that Plsp1 is a redox-dependent signal peptidase in the thylakoid lumen.
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Affiliation(s)
- Takafumi Midorikawa
- Department of Plant Sciences, University of California, One Shields Avenue, Davis, CA, 95616, USA
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Liu Y, Xie L, Gong G, Zhang W, Zhu B, Hu Y. De novo comparative transcriptome analysis of Acremonium chrysogenum: high-yield and wild-type strains of cephalosporin C producer. PLoS One 2014; 9:e104542. [PMID: 25118715 PMCID: PMC4131913 DOI: 10.1371/journal.pone.0104542] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Accepted: 07/09/2014] [Indexed: 11/19/2022] Open
Abstract
β-lactam antibiotics are widely used in clinic. Filamentous fungus Acremonium chrysogenum is an important industrial fungus for the production of CPC, one of the major precursors of β-lactam antibiotics. Although its fermentation yield has been bred significantly over the past decades, little is known regarding molecular changes between the industrial strain and the wild type strain. This limits the possibility to improve CPC production further by molecular breeding. Comparative transcriptome is a powerful tool to understand the molecular mechanisms of CPC industrial high yield producer compared to wild type. A total of 57 million clean sequencing reads with an average length of 100 bp were generated from Illumina sequencing platform. 22,878 sequences were assembled. Among the assembled unigenes, 9502 were annotated and 1989 annotated sequences were assigned to 121 pathways by searching against the Kyoto Encyclopedia of Genes and Genomes pathway (KEGG) database. Furthermore, we compared the transcriptome differences between a high-yield and a wild-type strain during fermentation. A total of 4329 unigenes with significantly different transcription level were identified, among which 1737 were up-regulated and 2592 were down-regulated. 24 pathways were subsequently determined which involve glycerolipid metabolism, galactose metabolism, and pyrimidine metabolism. We also examined the transcription levels of 18 identified genes, including 11 up-regulated genes and 7 down-regulated genes using reverse transcription quantitative -PCR (RT-qPCR). The results of RT-qPCR were consistent with the Illumina sequencing. In this study, the Illumina sequencing provides the most comprehensive sequences for gene expression profile of Acremonium chrysogenum and allows de novo transcriptome assembly while lacking genome information. Comparative analysis of RNA-seq data reveals the complexity of the transcriptome in the fermentation of different yield strains. This is an important public information platform which could be used to accelerate the research to improve CPC production in Acremonium chrysogenum.
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Affiliation(s)
- Yan Liu
- China State Institute of Pharmaceutical Industry, Zhangjiang Institute, Shanghai, China
- Shanghai Institute of Pharmaceutical Industry, Shanghai, China
| | - Liping Xie
- China State Institute of Pharmaceutical Industry, Zhangjiang Institute, Shanghai, China
- Shanghai Institute of Pharmaceutical Industry, Shanghai, China
| | - Guihua Gong
- China State Institute of Pharmaceutical Industry, Zhangjiang Institute, Shanghai, China
- Shanghai Institute of Pharmaceutical Industry, Shanghai, China
| | - Wei Zhang
- China State Institute of Pharmaceutical Industry, Zhangjiang Institute, Shanghai, China
- Shanghai Institute of Pharmaceutical Industry, Shanghai, China
| | - Baoquan Zhu
- China State Institute of Pharmaceutical Industry, Zhangjiang Institute, Shanghai, China
- * E-mail: (YH); (BZ)
| | - Youjia Hu
- China State Institute of Pharmaceutical Industry, Zhangjiang Institute, Shanghai, China
- Shanghai Institute of Pharmaceutical Industry, Shanghai, China
- * E-mail: (YH); (BZ)
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Nikkanen L, Rintamäki E. Thioredoxin-dependent regulatory networks in chloroplasts under fluctuating light conditions. Philos Trans R Soc Lond B Biol Sci 2014; 369:20130224. [PMID: 24591711 PMCID: PMC3949389 DOI: 10.1098/rstb.2013.0224] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Plants have adopted a number of mechanisms to restore redox homeostasis in the chloroplast under fluctuating light conditions in nature. Chloroplast thioredoxin systems are crucial components of this redox network, mediating environmental signals to chloroplast proteins. In the reduced state, thioredoxins control the structure and function of proteins by reducing disulfide bridges in the redox active site of a protein. Subsequently, an oxidized thioredoxin is reduced by a thioredoxin reductase, the two enzymes together forming a thioredoxin system. Plant chloroplasts have versatile thioredoxin systems, including two reductases dependent on ferredoxin and NADPH as reducing power, respectively, several types of thioredoxins, and the system to deliver thiol redox signals to the thylakoid membrane and lumen. Light controls the activity of chloroplast thioredoxin systems in two ways. First, light reactions activate the thioredoxin systems via donation of electrons to oxidized ferredoxin and NADP+, and second, light induces production of reactive oxygen species in chloroplasts which deactivate the components of the thiol redox network. The diversity and partial redundancy of chloroplast thioredoxin systems enable chloroplast metabolism to rapidly respond to ever-changing environmental conditions and to raise plant fitness in natural growth conditions.
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Affiliation(s)
- Lauri Nikkanen
- Molecular Plant Biology, Department of Biochemistry, University of Turku, , Turku 20014, Finland
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The chloroplast protein LTO1/AtVKOR is involved in the xanthophyll cycle and the acceleration of D1 protein degradation. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2014; 130:68-75. [DOI: 10.1016/j.jphotobiol.2013.11.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2013] [Revised: 10/11/2013] [Accepted: 11/05/2013] [Indexed: 11/19/2022]
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Järvi S, Gollan PJ, Aro EM. Understanding the roles of the thylakoid lumen in photosynthesis regulation. FRONTIERS IN PLANT SCIENCE 2013; 4:434. [PMID: 24198822 PMCID: PMC3813922 DOI: 10.3389/fpls.2013.00434] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 10/12/2013] [Indexed: 05/20/2023]
Abstract
It has been known for a long time that the thylakoid lumen provides the environment for oxygen evolution, plastocyanin-mediated electron transfer, and photoprotection. More recently lumenal proteins have been revealed to play roles in numerous processes, most often linked with regulating thylakoid biogenesis and the activity and turnover of photosynthetic protein complexes, especially the photosystem II and NAD(P)H dehydrogenase-like complexes. Still, the functions of the majority of lumenal proteins in Arabidopsis thaliana are unknown. Interestingly, while the thylakoid lumen proteome of at least 80 proteins contains several large protein families, individual members of many protein families have highly divergent roles. This is indicative of evolutionary pressure leading to neofunctionalization of lumenal proteins, emphasizing the important role of the thylakoid lumen for photosynthetic electron transfer and ultimately for plant fitness. Furthermore, the involvement of anterograde and retrograde signaling networks that regulate the expression and activity of lumen proteins is increasingly pertinent. Recent studies have also highlighted the importance of thiol/disulfide modulation in controlling the functions of many lumenal proteins and photosynthetic regulation pathways.
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Affiliation(s)
| | | | - Eva-Mari Aro
- *Correspondence: Eva-Mari Aro, Molecular Plant Biology, Department of Biochemistry, University of Turku, FIN-20014 Turku, Finland e-mail:
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Karamoko M, Gabilly ST, Hamel PP. Operation of trans-thylakoid thiol-metabolizing pathways in photosynthesis. FRONTIERS IN PLANT SCIENCE 2013; 4:476. [PMID: 24348486 PMCID: PMC3842002 DOI: 10.3389/fpls.2013.00476] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 11/04/2013] [Indexed: 05/08/2023]
Abstract
Thiol oxidation to disulfides and the reverse reaction, i.e., disulfide reduction to free thiols, are under the control of catalysts in vivo. Enzymatically assisted thiol-disulfide chemistry is required for the biogenesis of all energy-transducing membrane systems. However, until recently, this had only been demonstrated for the bacterial plasma membrane. Long considered to be vacant, the thylakoid lumen has now moved to the forefront of photosynthesis research with the realization that its proteome is far more complicated than initially anticipated. Several lumenal proteins are known to be disulfide bonded in Arabidopsis, highlighting the importance of sulfhydryl oxidation in the thylakoid lumen. While disulfide reduction in the plastid stroma is known to activate several enzymatic activities, it appears that it is the reverse reaction, i.e., thiol oxidation that is required for the activity of several lumen-resident proteins. This paradigm for redox regulation in the thylakoid lumen has opened a new frontier for research in the field of photosynthesis. Of particular significance in this context is the discovery of trans-thylakoid redox pathways controlling disulfide bond formation and reduction, which are required for photosynthesis.
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Affiliation(s)
- Mohamed Karamoko
- Department of Molecular Genetics, The Ohio State UniversityColumbus, OH, USA
- Department of Molecular and Cellular Biochemistry, The Ohio State UniversityColumbus, OH, USA
| | - Stéphane T. Gabilly
- Department of Molecular Genetics, The Ohio State UniversityColumbus, OH, USA
- Department of Molecular and Cellular Biochemistry, The Ohio State UniversityColumbus, OH, USA
| | - Patrice P. Hamel
- Department of Molecular Genetics, The Ohio State UniversityColumbus, OH, USA
- Department of Molecular and Cellular Biochemistry, The Ohio State UniversityColumbus, OH, USA
- *Correspondence: Patrice P. Hamel, Department of Molecular Genetics, The Ohio State University, 500 Aronoff Laboratory, 318 West 12th Avenue, 43210 Columbus, OH, USA e-mail:
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